Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
  • C08J9/08—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • 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
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
  • B29C44/34—Auxiliary operations
  • B29C44/3442—Mixing, kneading or conveying the foamable material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • 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
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
  • B29C44/34—Auxiliary operations
  • B29C44/3469—Cell or pore nucleation
  • B29C44/348—Cell or pore nucleation by regulating the temperature and/or the pressure, e.g. suppression of foaming until the pressure is rapidly decreased
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0066—Use of inorganic compounding ingredients
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • 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
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
  • B29C44/34—Auxiliary operations
  • B29C44/36—Feeding the material to be shaped
  • B29C44/38—Feeding the material to be shaped into a closed space, i.e. to make articles of definite length
  • B29C44/42—Feeding the material to be shaped into a closed space, i.e. to make articles of definite length using pressure difference, e.g. by injection or by vacuum
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/06—CO2, N2 or noble gases
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2323/04—Homopolymers or copolymers of ethene
  • C08J2323/06—Polyethene

Definitions

• Foamed polymer articles are widely employed in the industry due to the highly desirable attribute of providing high strength associate with solid polymer articles, while also delivering a reduction of density and therefore in the amount of polymer used to form an article of a selected volume. Additionally, the industry enjoys the benefits provided by the reduction in the weight of a foamed article compared with its solid counterpart, while still obtaining the benefits of strength, toughness, impact resistance, etc. delivered by the polymer itself.
• thermoplastic polymers to make such foam articles.
• commercial guidelines and industrial practice employ a melt mixing apparatus operable to maintain a pressure to limit expansion of a gas in the interior of the apparatus while melt mixing the gas or a source of a gas with the thermoplastic polymer, further at a temperature above a melt temperature of the thermoplastic polymer.
• melt mixing apparatus operable to maintain a pressure to limit expansion of a gas in the interior of the apparatus while melt mixing the gas or a source of a gas with the thermoplastic polymer, further at a temperature above a melt temperature of the thermoplastic polymer.
• Such processes and apparatuses are designed to minimize formation of pneumatoceles, or pockets of gas, that would otherwise form by expansion of the gas in the molten thermoplastic polymer.
• a thermoplastic polymer may include a source of a gas or the gas itself dissolved or dispersed therein, while including no pneumatoceles or substantially no pneumatoceles.
• a mixture of molten thermoplastic polymer and a gas that is at or above the temperature at which it would form pneumatoceles at atmospheric pressure, while including no pneumatoceles or substantially no pneumatoceles may be referred to as a molten pneumatic mixture.
• the temperature at which the gas, or pneumatogen, would form pneumatoceles in the molten pneumatic mixture at atmospheric pressure may be referred to as the critical temperature.
• Melt mixing apparatuses well known in the art are thus designed and adapted to make and dispense molten pneumatic mixtures. Further, such apparatuses are suitable to make molten pneumatic mixtures by adding a nascent, latent, or potential gas that is released at a characteristic temperature or that forms by exothermic or endothermic chemical reaction at a characteristic temperature.
• the critical temperature of a nascent, latent, or potential gas is the temperature at which the reaction occurs or a gas is released into the thermoplastic polymer. All such materials and processes are well understood and melt mixing apparatuses of varying design are widely available commercially for this purpose.
• Melt mixing apparatuses commonly employed are single screw or twin screws extruders modified to have a pressurized chamber at the distal end of the screw to receive a set amount, or “shot” of a molten pneumatic mixture that travels during mixing by operation of the screw to urge the molten pneumatic mixture toward the pressurized chamber.
• the molten pneumatic mixture is dispensed from the melt mixing apparatus and is directed by fluidly connected tubes, pipes, etc. into the cavity of a mold that obtains a desired shape. Dispensing is generally carried out to maximize the amount of foaming (pneumatocele formation) that occurs in the mold cavity by release of the pressure while the thermoplastic polymer is still molten. The expanded foam in the cavity is then cooled to result in a foamed article. Foamed parts molded using this methodology are referred to in the art as injection molded foam parts. The techniques are generally limited in scope to make parts having thicknesses of about 2 cm or less.
• Injection molding processes employing pneumatogen sources to induce a foam structure in molded parts can be understood from a recent peer-reviewed journal article by Bociaga et al., “The influence of foaming agent addition, talc filler content, and injection velocity on selected properties, surface state, and structure of polypropylene injection molded parts.” Cellular Polymers 2020, 39(1) 3-30. In this publication the process conditions typically employed for molding of standard injection molded ISO test bars of 4.1 mm thickness were systematically changed to create 16 different combinations of the process settings and formulation variables (concentration of pneumatogen source, filler content, injection velocity, injection time, hold time, and hold pressure).
• Described herein is a method of making a molten polymer foam.
• the method includes: adding a thermoplastic polymer and a pneumatogen source to an extruder; heating and mixing the thermoplastic polymer and pneumatogen source in the extruder under a pressure to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the critical temperature of the pneumatogen source; collecting an amount of the molten pneumatic mixture in a collection area of the extruder; defining an expansion volume in the collection area to cause a pressure to drop (depressurization) in the collection area; allowing an expansion period of time to elapse after the defining; and dispensing a molten polymer foam from the collection area.
• the expansion volume is selected to provide between 10% and 300% of the total expected molten foam volume in the collection area, further wherein the rate of depressurization (that is, the rate of defining the pressure drop) is at least 0.01 GPa/s, in embodiments 0.1 GPa/s or greater; and in some embodiments is 1.0 GPa/s or even greater, such as up to 5.0 GPa/s.
• Depressurization rates of greater than 0.01 GPa/s are referred to herein as “rapid depressurization”.
• rapid depressurization is coupled with a high backpressure, wherein backpressure is the amount of pressure required e.g.
• high backpressure means a backpressure of 500 kPa or greater, such as a backpressure of 500 kPa and as high as 25 MPa, further as limited by the injection molding machine employed to carry out the depressurization.
• a stabilized molten polymer foam is obtained that is capable of forming polymer foam articles having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in the interior thereof, and are further characterized as having a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles throughout the entirety' of the article, and total article volumes of 1000 cm 3 and greater, 2000 cm 3 or greater, 3000 cm 3 or greater, 4000 cm 3 or greater, or 5000 cm 3 or greater, or 2000 cm 3 to 5000 cm 3 or even greater.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety' thereof.
• the molten pneumatic mixture is subjected to 1 to 5 cycles of pressurization followed by depressurization (obtaining a pressure drop), prior to dispensing the molten polymer foam from the collection area.
• the dispensing is dispensing to a forming element; in some embodiments the forming element is a mold. In embodiments there is a fluid connection between the collection area of the extruder and the mold. In embodiments, the dispensing is an unimpeded flow of the molten polymer foam. In some embodiments, the dispensing is dispensing a linear flow of molten polymer foam. In embodiments, the molten polymer foam contacts the mold and partially, substantially, or completely fills the mold cavity.
• the method further comprises cooling the dispensed molten polymer foam to a temperature below a melt transition of the thermoplastic polymer.
• one or more additional materials to the extruder wherein the one or more materials are selected from colorants, stabilizers, brighteners, nucleating agents, fibers, particulates, and fillers.
• the pneumatogen source is a pneumatogen and the addition is a pressurized addition.
• the pneumatogen source comprises a bicarbonate, a polycarboxylic acid or a salt or ester thereof, or a mixture thereof.
• a polymer foam article made in using the methods, materials, and apparatuses described herein.
• the polymer foam article has a foam structure throughout the entirety thereof characterized as a continuous polymer matrix defining a plurality of pneumatoceles therein.
• a surface region of a polymer foam article comprises compressed pneumatoceles.
• the surface region is the region extending 500 microns from the surface of the article.
• thermoplastic polymer foam articles having a foam structure throughout the entirety thereof that is a continuous polymer matrix defining a plurality of pneumatoceles therein, further wherein a surface region of the article comprises compressed pneumatoceles.
• the surface region is the region of the article extending 500 microns from the surface thereof.
• the article comprises compressed pneumatoceles more than 500 microns from the surface thereof.
• the polymer foam article comprises a shape and a volume wherein a sphere having a diameter of 2 cm or more would fit within the polymer foam article in at least one location, without protrading from the surface.
• the polymer foam article further includes one or more locations wherein a sphere having a diameter of 2 cm would not fit within the polymer foam article, and would protrude from the surface.
• the polymer foam article has a volume of more than 1000 cm 3 , 1000 cm 3 to 5000 cm 3 , 2000 cm 3 to 5000 cm 3 or even more than 5000 cm 3 .
• the polymer foam article has a shape and a volume wherein at least one (theoretical) sphere having a diameter between 2 cm and 1000 cm, such as between 20 cm and 1000 cm, would fit within the polymer foam article in at least one location, without protruding from the surface of the article.
• the polymer foam article comprises a volume of more than 2000 cm 3 and a shape and a volume wherein a sphere having a diameter of 2 cm or more would fit within the polymer foam article in at least one location, without protruding from the surface.
• the polymer foam article comprises a volume between 2000 cm 3 and 5000 cm 3 and a shape and volume wherein a sphere having a diameter of at least 20 cm would fit within the polymer foam article in at least one location, without protruding from the surface.
• the polymer foam article further comprises a volume of more than 5000 cm 3 and a shape wherein a sphere having a diameter of 20 cm to 1000 cm would fit within the polymer foam article in at least one location, without protruding from the surface.
• the polymer foam article comprises a shape wherein one sphere having a diameter of 20 cm to 1000 cm would fit within the polymer foam article in at least one location, without protruding from the surface; in other embodiments, the polymer foam article has a shape wherein two spheres having a diameter of 20 cm to 1000 cm would fit within the polymer foam article without protruding from the surface. In still other embodiments, the polymer foam article has a shape wherein three or more spheres having a diameter of 20 cm to 1000 cm would fit within the polymer foam article without protruding from the surface.
• materials used to make the polymer foam articles are not particularly limited and include thermoplastic polymers selected from polyolefins, polyamides, polyimides, polyesters, polycarbonates, poly (lactic acid)s , acrylonitrile- butadiene-styrene copolymers, polystyrenes, polyurethanes, polyvinyl chlorides, copolymers of tetrafluoroethylene, polyethersulfones, polyacetals, polyaramids, polyphenylene oxides, polybutylenes, polybutadienes, polyacrylates and methacryates, ionomeric polymers, poly ether-amide block copolymers, polyaryletherkeytones, polysulfones, polyphenylene sulfides, polyamide-imide copolymers, poly(butylene succinate)s, cellulosics, polysaccharides, and copolymers, alloys, admixtures, and blend
• a first polymer foam article in accordance with any of the embodiments described herein, and formed in accordance with any of the methods described herein is also a source of thermoplastic polymer for forming a second polymer foam article in accordance with the methods described herein.
• the first polymer foam article is a recycled material feedstock when used to make a second polymer foam article.
• FIGS. 1A-1B illustrate a melt mixing apparatus useful for carrying out the methods described herein.
• FIG. 2-1 is a photographic image of a part molded according to the standard foam molding process as described in Example 1.
• FIG. 2-2 is a photographic image of a part molded according to a molten-foam injection molding (MFIM) process as described in Example 1.
• MFIM molten-foam injection molding
• FIG. 2-3 is a photographic image of a piece cut from the part made according to the standard foam molding process as described in Example 1.
• FIG. 2-4 is a photographic image of a piece cut from the part made according to the MFIM process as described in Example 1.
• FIG. 2-5 is a photographic image of a piece cut from the part made according to the standard foam molding process as described in Example 1.
• FIG. 2-6 is a photographic image of a piece cut from the part made according to the MFIM process as described in Example 1.
• FIG. 3A is a photographic image of a cross section of Part A made according to a standard foam molding process and cut into two pieces to reveal a cross section, as described in Example 2.
• FIG. 3B is a photographic image of a cross section of Part B made according to an MFIM process and cut into two pieces to reveal a cross section, as described in Example 2.
• FIG. 4A is a photographic image of a cross section of Part C made according to an MFIM process and cut into two pieces to reveal a cross section, as described in Example 2.
• FIG. 4B is a photographic image of a cross section of Part D made according to a standard foam molding process and cut into two pieces to reveal a cross section, as described in Example 2.
• FIG. 5 is a graph including plots of part density versus decompression volume for various decompression times for Trial B as described in Example 3.
• FIG. 6 is a graph including plots of strain versus time for parts made in Trials A, B, and C as described in Example 4.
• FIG. 7 shows photographic images of views in different aspects of Parts A, B, and C as described in Example 4.
• FIG. 8 shows photographic images views of cross sections of Part A', B', C', and D' as described in Example 4.
• FIG. 9 is a drawing of two parts as described in Example 5.
• FIG. 10 is an isometric image of a tomography scan of the first part made according to an MFIM process as described in Example 6.
• FIG. 11 is an image of the cross section plane shown in FIG. 10 as described in Example 6.
• FIG. 12 is a graph including plots of average cell size and cell count against cell circularity for the first part made as described in Example 6.
• FIG. 13 is drawing of an X-ray tomographic image of a cross section of a second (spherical) part as described in Example 6.
• FIG. 14 is a graph including plots of average cell size and cell count against cell circularity for the second (spherical) part made as described in Example 6.
• FIG. 15 is a micrograph of a fracture surface of a fractured three-inch diameter composite sphere made according to an MFIM process, as described in Example 7.
• FIG. 16 is an image a micrograph of a fracture surface of a fractured three-inch diameter composite sphere made according to an MFIM process, as described in Example 7.
• FIG. 17 is an image a micrograph of a fracture surface of a fractured three-inch diameter composite sphere made according to an MFIM process, as described in Example 7.
• FIG. 18 is an image a micrograph of a fracture surface of a fractured three-inch diameter composite sphere made according to an MFIM process, as described in Example 7.
• FIG. 19 shows micrograph images of cross sections from ISO bar parts made according to standard foam molding process runs 10, 11, 14, and 15, as described in Example 8.
• FIG. 20 shows micrograph images of cross sections from ISO bar parts made according to MFIM process runs 9, 10, 15, and 16, as described in Example 8.
• FIG. 21 shows a micrograph of a cross section of an ISO bar part made according to the MFIM process of Run 9 and stress-strain plots of replicate parts made according to the MFIM process of Run 9, as described in Example 8.
• FIG. 22 includes a micrograph of a cross section of an ISO bar part made according to the standard foam molding process of Run 10 and stress-strain plots of replicate parts made according to the standard foam molding process of Run 10, as described in Example 8.
• FIG. 23 includes two images from X-ray tomography of an ISO bar part made according to the standard foam molding process of Run 15, as described in Example 8.
• FIG. 24 includes two images from X-ray tomography of an ISO bar part made according to the MFIM process of Run 9, as described in Example 8.
• FIG. 25 is an image from an X-ray scan of a large tensile bar part made according to an MFIM process, as described in Example 9.
• FIG. 26 includes cross sections of eight large tensile bar parts made according to MFIM processes, as described in Example 9.
• FIG. 27 is an X-ray tomography image of a large tensile bar part made according to an MFIM process, as described in Example 9.
• FIG. 28 includes a series of X-ray tomographic images at different depths within a tensile bar part made according to an MFIM process and a series of images at different depths within a tensile bar part made according to a standard foam molding process, as described in Example 10.
• FIG. 29 is a graph including a plot of cell count versus depth for the tensile bar part made according to an MFIM process and a plot of cell count versus depth for the tensile bar part made according to a standard foam molding process, as described in Example 10.
• FIG. 30 is a graph including a plot of cell circularity versus depth for the tensile bar part made according to an MFIM process and a plot of cell circularity versus depth for the tensile bar part made according to a standard foam molding process, as described in Example 10.
• FIG. 31 is a graph including a plot of cell size versus depth for the tensile bar part made according to an MFIM process and a plot of cell size versus depth for the tensile bar part made according to a standard foam molding process, as described in Example 10.
• FIG. 32 is a photograph of Sample 20 made according to a reverse MFIM process, as described in Example 12.
• FIG. 33 is a photograph of Sample 10 made according to an MFIM process, as described in Example 12.
• FIG. 34 is a photograph showing a cross section of Sample 20 made according to a reverse MFIM process, as described in Example 12.
• FIG. 35 is a photograph showing a cross section of Sample 10 made according to an MFIM process, as described in Example 12.
• FIG. 36 is a plot of cell count versus depth (distance from surface) for Sample 10 (MFIM) and Sample 20 (Reverse MFIM) as described in Example 12.
• FIG. 37 is a plot of cell size versus depth (distance from surface) for Sample 10 (MFIM) and Sample 20 (Reverse MFIM) as described in Example 12.
• FIG. 38 is a graph including a plot of averaged stress versus strain for Sample 10 (MFIM) and a plot for Sample 20 (Reverse MFIM) from compression modulus measurements, as described in Example 12.
• FIG. 39 is a graph including a plot of averaged stress versus strain for Sample 10 (MFIM) and a plot for Sample 20 (Reverse MFIM) from flexural modulus measurements, as described in Example 12.
• FIG. 40 is a graph of plots of stress versus strain from compression modulus measurements made of three metallocene polyethylene (mPE) materials of different densities and made according to MFIM processes, as described in Example 14.
• mPE metallocene polyethylene
• FIG. 41 illustrates a mold configuration usefill for carrying out the methods described herein.
• FIG. 42 is a photograph showing a part, Part 111, made without a decompression step, as described in Example 15.
• FIG. 43 is a part, Part 87, made according to an MFIM process as described in Example 15.
• FIG. 44 is a plot of injection pressure against barrel volume for the molding processes of Part 111 and the molding process of Part 87 as described in Example 15.
• FIG. 45 is a photograph of a cross section of Part 16A as described in Example 16.
• FIG. 46 is a photograph of a cross section of Part 16AR as described in Example 16.
• FIG. 47 is a photograph of a cross section of Part 16B as described in Example 16.
• FIG. 48 is a photograph of a cross section of Part 16BR as described in Example 16.
• FIG. 49 is a photograph of a cross section of Part 16C as described in Example 16.
• FIG. 50 is a photograph of a cross section of Part 16CR as described in Example 16.
• FIG. 51 is a photograph of a cross section of Part 16D as described in Example 16.
• FIG. 52 is a photograph of a cross section of Part 16DR as described in Example 16.
• FIG. 53 is a photograph of a cross section of Part 16E as described in Example 16.
• FIG. 54 is a photograph of a cross section of Part 16ER as described in Example 16.
• FIG. 55 is a photograph of Part 1 made using no decompression, as described in Example 17.
• FIG. 56 is a photograph of a cross section of Part 2 made with a decompression time of 0.5 seconds, as described in Example 17.
• FIG. 57 is a photograph of a cross section of Part 3 made with a decompression time of 7 seconds, as described in Example 17.
• FIG. 58 is a photograph of a cross section of Part 1 after sectioning, as described in Example 18.
• FIG. 59 is a photograph of a cross section of Part 2 after sectioning, as described in Example 18.
• FIG. 60 shows a photograph of three brick parts made, as described in Example 19, with one decompression step, three decompression steps, and five decompression steps.
• FIG. 61 shows magnified images of three brick parts made, as described in Example 19, with one decompression step, three decompression steps, and five decompression steps.
• FIG. 62 is a plot of compressive strength versus compressive strain measured for three parts made as described in Example 19, using one decompression step, three decompression steps, and five decompression steps.
• FIG. 63 is a graphical representation of the force at peak measured during stress- strain tests of three parts made as described in Example 19, using one decompression step, three decompression steps, and five decompression steps.
• FIG. 64 is a graphical representation of the energy at peak measured during stress- strain tests of three parts made as described in Example 19, using one decompression step, three decompression steps, and five decompression steps.
• FIG. 65 shows a photograph of a cross section of a spherical SURLYN(TM) part after sectioning and a magnified image of the cross section close to the spherical surface of the part, as described in Example 20.
• FIG. 66 shows a photograph of a cross section of a spherical polyethylene part after sectioning and a magnified image of the cross section close to the spherical surface of the part, as described in Example 20.
• FIG. 67 is a photograph of the two parts made as described in Example 21.
• FIG 68 is a photographic image of the fourth part, molded using a decompression time of 10 seconds after applying a depressurization rate of 0.0009 GPa/sec, as described in Example 17.
• FIG. 69 is a photographic image of the fifth part, molded using a depressurization rate of 0.0629 GPa/sec, as described in Example 17.
• FIG. 70 is a photograph of a sectioned block, Block 45 of 60, made as described in Example 22.
• FIG. 71 is a photograph of a sectioned block, Block 27 of 60, made as described in Example 22.
• FIG. 72 is a photograph of a sectioned block, Block 60 of 60, made as described in Example 22.
• FIG. 73 is a photograph of a fort built with bricks made as described in
• FIG. 74 shows photographic images of cross sections of parts made from 0%, 25%, 50%, and 100% recycled plastic, and on the right magnified images of the cross sections for parts made from 0% and 100% recycled material, as described in Example 23.
• Corresponding reference characters indicate corresponding parts throughout the drawings.
• polymer matrix including “continuous polymer matrix”, ‘thermoplastic polymer matrix”, “molten polymer matrix” and like terms refer to a continuous solid or molten thermoplastic polymer phase or an amount of a solid or molten thermoplastic polymer defining a continuous phase.
• molten mixture means a molten thermoplastic polymer or mixture of molten thermoplastic polymers, optionally including one or more additional materials mixed with the molten thermoplastic polymer or mixture thereof.
• molten pneumatic mixture means a mixture of a thermoplastic polymer and a pneumatogen source, wherein the polymer is at a temperature above a melt temperature thereof and the temperature of the mixture exceeds the critical temperature of the pneumatogen source, further wherein the mixture is characterized as having no pneumatoceles or substantially no pneumatoceles.
• the molten pneumatic mixture is present under a pressure sufficient to prevent pneumatocele formation, or substantially prevent pneumatocele formation, or cause the pneumatogen source to be dissolved or dispersed within the thermoplastic polymer either as a gas or a supercritical liquid.
• “Substantially prevent pneumatocele formation”, “substantially no pneumatoceles” and like terms with respect to a molten pneumatic mixture means that while pressure conditions may be used to prevent pneumatocele formation in a molten mixture, defects, wearing of parts, and the like in processing equipment may cause unintentional pressure loss that does not interfere overall with obtaining and maintaining a pressurized molten mixture.
• foam As used herein, “foam”, “polymer foam”, thermoplastic polymer foam”, “molten foam”, “molten polymer foam” and similar terms refer generally to a continuous polymer matrix defining a plurality of pneumatoceles as a discontinuous phase dispersed therein.
• the term “pneumatocele” means a discrete void defined by and surrounded by a continuous thermoplastic polymer matrix.
• pneumatogen means a gaseous compound capable of defining a pneumatocele within a molten thermoplastic polymer matrix.
• critical temperature means the temperature at which a pneumatogen source produces a pneumatogen at atmospheric pressure.
• the term “pneumatogen source” refers to a latent, potential, or nascent pneumatogen, added to or present within a thermoplastic polymer matrix, such as dissolved in the matrix and/or present as a supercritical fluid therein; or in the form of an organic compound that produces a pneumatogen by a chemical reaction; or a combination of these; or wherein the pneumatogen source is a pneumatogen, becomes a pneumatogen, or produces a pneumatogen at a critical temperature characteristic of the pneumatogen source.
• rapidly depressurization means a pressure drop that occurs at a rate of greater than 0.01 GPa/s, such as 0.01 GPa/s to 5 GPa/s.
• high backpressure means a backpressure of 500 kPa or greater, such as a backpressure of 500 kPa to 25 MPa, further wherein backpressure is the threshold amount of pressure required e.g. in the collection area or throughout the barrel of an injection molding machine that initiates depressurization.
• the term "about" modifying, for example, the quantity of an ingredient in a composition, concentration, volume, process temperature, process time, yield, flow rate, pressure, and like values, and ranges thereof, employed in describing the embodiments of the disclosure, refers to variation in the numerical quantity that can occur, for example, through typical measuring and handling procedures used for making compounds, compositions, concentrates or use formulations; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of starting materials or ingredients used to carry out the methods, and like proximate considerations.
• the term “substantially” means “consisting essentially of, as that term is construed in U.S. patent law, and includes “consisting of as that term is construed in U.S. patent law.
• a composition that is "substantially free” of a specified compound or material may be free of that compound or material, or may have a minor amount of that compound or material present, such as through unintended contamination, side reactions, or incomplete purification.
• a “minor amount” may be a trace, an immeasurable amount, an amount that does not interfere with a value or property, or some other amount as provided in context.
• a composition that has "substantially only” a provided list of components may consist of only those components, or have a trace amount of some other component present, or have one or more additional components that do not materially affect the properties of the composition.
• “substantially” modifying, for example, the type or quantity of an ingredient in a composition, a property, a measurable quantity, a method, a value, or a range, employed in describing the embodiments of tire disclosure refers to a variation that does not affect the overall recited composition, property, quantity, method, value, or range thereof in a manner that negates an intended composition, property, quantity, method, value, or range.
• the claims appended hereto include equivalents according to this definition.
• any recited ranges of values contemplate all values within the range and are to be construed as support for claims reciting any sub-ranges having endpoints which are real number values within the recited range.
• a disclosure in this specification of a range of fiom 1 to 5 shall be considered to support claims to any of the following ranges: 1-5; 1-4; 1-3; 1-2; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.
• a method of extruding a molten polymer foam comprises, consists essentially of, or consists of adding a thermoplastic polymer and a pneumatogen source to an inlet situated on a first end of an extruder; heating and mixing the thermoplastic polymer and the pneumatogen source in the extruder to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the critical temperature of the pneumatogen source; collecting an amount of the molten pneumatic mixture in a barrel region of the extruder located proximal to a second end of the extruder; forming an expansion volume in the barrel region, wherein the forming causes a pressure to drop in the barrel region; allowing a period of time to elapse after the pressure drop; and dispensing a molten polymer foam fiom the extruder.
• the extruder is any machine designed and adapted for melting, mixing, and dispensing thermoplastic polymers and mixtures thereof, optionally with one or more additional materials such as fillers, nucleating agents, diluents, stabilizers, brighteners, and the like; and further wherein the extrader includes a collection area for a collecting a mass of mixed, molten material and further is capable of forming an expansion volume in the collection area that is coupled with a pressure drop.
• Extruders are well known in the industry' and are broadly used for melting, mixing, and manipulating molten thermoplastic polymers.
• the extruder is adapted and designed for melting, mixing, and dispensing a mixture of a thermoplastic polymer and a pneumatogen source.
• Such extruders are adapted to obtain molten pneumatic mixtures under a pressure sufficient to prevent or substantially prevent pneumatocele formation in the molten pneumatic mixture.
• extruders useful to carry out the present methods include an interior volume, referred to in the art as the “barrel” of the extruder, designed and adapted for receiving a solid thermoplastic polymer, further for carrying out the melting and mixing thereof.
• the extruder defines an interior volume designed for receiving a solid thermoplastic polymer and a pneumatogen or a pneumatogen source, further for carrying out the melting of at least the polymer and for mixing the pneumatogen or pneumatogen source with the molten polymer to obtain a molten pneumatic mixture.
• the extruder further includes a collection area for a collecting a mass of a molten pneumatic mixture material.
• the extruder further includes means of forming an expansion volume in the collection area that is coupled with a pressure drop.
• the extruder is an injection molding machine.
• the extruder is a SODICKTM molding machine sold by Plustech Inc. of Schaumburg, IL.
• the extruder includes either one or two members known in the art as “screws” disposed within the interior volume, known in the art as a “barrel”.
• the screws have a right circular cylindrical shape overall, and further include one or more protruding thread members referred to as ‘‘flights”.
• the extrader is a single screw extruder, defined as including one screw movably disposed within the barrel for rotation of the cylinder around the axis thereof, for lateral movement of the cylinder along the axis thereof, or a combined movement comprising both rotation and lateral movement.
• the extruder is a twin screw extruder, defined as including two screws movably disposed within the barrel in substantially parallel and proximal relationship with respect to each other, further where each screw' is movably disposed within the barrel for rotation of the cylinder around the axis thereof, for lateral movement of the cylinder along the axis thereof, or a combined movement comprising both rotation and lateral movement.
• the screws of a twin screw extruder are further arranged so that the action of the screws when turned in counter-rotating fashion define a designed mixing and transportation pattern of a molten thermoplastic polymer disposed within the barrel.
• the extruder is further adapted and designed to receive a solid thermoplastic polymer.
• the barrel of the extrader is further adapted and designed to receive a solid thermoplastic polymer by including an inlet situated near a first end of the extruder and adapted to add a solid thermoplastic polymer to the barrel.
• the solid thermoplastic polymer is added to the inlet in any suitable format, for example beads, pellets, powders, ribbons, or blocks, which are all familiar formats to those of skill.
• the extruder includes second, third, or even fourth or higher numbers of inlets designed and adapted for adding or introducing one or more additional materials comprising one or more solids, liquids, or gases to the interior volume of the extruder, further for mixing the one or more additional materials with the thermoplastic polymer.
• the interior volume of the extruder is adapted for receiving, containing, and melting a thermoplastic polymer and optionally one or more additional materials; and subjecting the thermoplastic polymer and the optional one or more additional materials to heat, shear and mixing to form a molten mixture, while contemporaneously transporting the molten mixture in a direction generally proceeding from the first end thereof to a second end thereof.
• the shear, mixing, and transportation is accomplished by rotating the screw or counter-rotating two screws.
• the extruder interior volume, or a portion thereof, is surrounded or partly surrounded by one or more heat sources.
• Heat sources suitably adapted for heating the interior volume of an extruder include, in various embodiments, heated water jackets, heated oil jackets, electrical resistance heaters, open or jacketed flames, or another heat source.
• the heat source is operable to raise a temperature in the interior volume of the extruder.
• the temperature is suitably selected by the operator for melting a thermoplastic polymer and/or maintaining a desired temperature within a portion of the interior volume of the extruder.
• an extruder is adapted to include more than one heat source, wherein tire heat sources are independently operable to enable one of skill to provide a range of temperature “zones” within the interior volume. Additional temperature zones may be included in some extruders in association with adding one or more materials to an inlet thereof or dispensing one more materials from an outlet thereof. In embodiments, temperatures within the one or more temperature zones are set by the operator for increased control and optimization of melting, mixing, shearing, and transportation of the thermoplastic polymer and optionally one or more additional materials.
• the extrader is conventionally designed and adapted to apply and maintain a pressure within tire interior volume thereof during the heating, mixing and transportation of a molten mixture.
• the extruder is designed and adapted to apply and maintain a first pressure within the interior volume or barrel during the heating, mixing and transportation of a molten mixture.
• the pressure inside the barrel during the heating, mixing and transportation of a molten pneumatic mixture is sufficient to prevent or substantially prevent leakage of molten pneumatic mixture from the barrel.
• the pressure within the barrel is sufficient to prevent a molten pneumatic mixture from developing pneumatoceles when a temperature within the barrel exceeds the critical temperature of the pneumatogen source.
• the pressure within the barrel is substantially sufficient to prevent a molten pneumatic mixture from developing pneumatoceles when a temperature within the barrel exceeds the critical temperature of the pneumatogen source.
• substantially refers to inadvertent leaking of material or inadvertent loss of pressure from the barrel due to manufacture, age, or manner of use of the extruder and/or tire screw as is familiar to one of skill. Further in such embodiments
• substantially in the context of “sufficient to prevent a molten pneumatic mixture from developing pneumatoceles”, means that a small percentage, such as up to 10% of the pneumatogen may inadvertently form pneumatoceles while the pressure is maintained on a molten pneumatic mixture; but that it is the goal of the operator to maintain sufficient pressure to prevent pneumatoceles from forming.
• the barrel of the extruder includes a collection area for collecting an amount of a molten mixture in preparation for dispensing the molten mixture from the extruder.
• the mass of the molten mixture is selected by the user.
• the molten mixture is a molten pneumatic mixture.
• building a shot the term of art used to describe the collecting of a mass of a molten pneumatic mixture in a collection area of the barrel of the extruder.
• a mass of a molten pneumatic mixture is collected by transporting the molten pneumatic mixture from the first end toward the second end of the extruder - that is, toward and into the collection area - by the rotation of the screw or screws (or another mixing element) and by further allowing the molten pneumatic mixture to accumulate in the collection area until the entirety of the desired mass of molten pneumatic mixture is collected and is disposed in the collection area of the barrel.
• the collection area is situated between the screw or screws and the second end of the extrader.
• the collection area is in pressurized communication with the remainder of the barrel, while in other embodiments the collection area is pressurably isolated relative to the remainder of the barrel, for example by providing an o-ring, check ring, or other sealing mechanism annularly disposed around the screw or screws to seal or pressurably isolate the collection area from the extruder barrel.
• a mass of molten pneumatic mixture, or “shot” is collected or “built” in the collection area by transporting the molten pneumatic mixture toward and into the collection area by the rotation of the screw or screws (or another mixing element).
• a shot is said to be built when the entire selected mass of molten pneumatic mixture is disposed within the collection area.
• melt mixing apparatuses such as the mechanical elements and features of an extruder or other melt mixing apparatus, and further the foregoing description of methods of making and collecting molten pneumatic mixtures in a shot, is in accord with conventional apparatuses and methods of using such apparatuses to make molten pneumatic mixtures and to build shots thereof.
• a shot of molten pneumatic mixture is conventionally prevented or substantially prevented from developing pneumatoceles while present in the barrel, including during the mixing, heating, transporting, and collecting and further while disposed within the collection area.
• a nozzle, gate, door, or other movable barrier situated between the collection area and an outlet situated on the second end of the extruder in some embodiments a shut-off nozzle, as will be recognized by one of skill in the art of injection molding) is opened, providing fluid connection from the barrel to the outlet to dispense the shot from the extruder.
• a mechanical plunger is applied to urge the molten pneumatic mixture from the barrel and through the outlet.
• the extruder screw or screws are suitably employed in a lateral plunging movement in a direction toward the second end of the extruder, which in turn urges the molten pneumatic mixture from the collection area of the barrel and through the outlet.
• the shot is not mixed or subjected to applied shear or extension while the expansion volume is in the process of being defined. In embodiments, the shot is not transported during the expansion period. In embodiments, the shot is allowed to stand, or reside, undisturbed or substantially undisturbed in the collection area during the expansion period. In any of the foregoing embodiments, the shot may be heated during the expansion period; however, in some embodiments, no heat is added to the shot during the expansion period.
• a molten polymer foam may be dispensed from the second end of the extruder.
• the molten polymer foam includes a plurality of pneumatoceles. Without being limited by theory, we believe that the pneumatoceles form when the molten pneumatic mixture is subjected to the expanded volume and accompanying pressure drop (second pressure). In accord with known principles of physics, the formation of the pneumatoceles is likely caused by the defining of the expanded volume and concomitant pressure drop in the collection area of the barrel, together with the expansion period in which the pneumatoceles form by action of the pneumatogen.
• defining the expansion volume after building the shot results in superior properties attributable to the molten polymer foam that is dispensed.
• forming a molten pneumatic mixture under pressure followed by lowering the pressure and concomitantly forming a defined volume prior to dispensing the mixture (such as into a mold cavity) results in a molten polymer foam that upon cooling provides solidified polymer foam articles having unexpected and highly beneficial physical properties.
• the structure of articles made using the molten polymer foam dispensed from an extruder after the expansion period is different both macroscopically and microscopically from polymer foams made by conventional methods; and exhibit superior properties suitable for structural members, for example.
• the polymer foam articles made using the methods, apparatuses, and materials described herein that are characterized as having a continuous thermoplastic matrix throughout the entirety thereof, and a plurality of pneumatoceles distributed throughout the entirety of the polymer foam article.
• the defining of the expansion volume in a single screw extruder is suitably achieved by moving the screw laterally toward a first end of the extruder and away from the collection area of the extruder where the shot is collected.
• the defining of the expansion volume in a twin screw extruder is achieved by moving both screws laterally toward a first end of the extruder and away from the region of the extruder where the shot is collected.
• the lateral moving is optionally accompanied by rotation of the screw or screws. That is, the one or two screws may be rotated during the lateral moving or the rotation may be stopped during the lateral moving.
• the defining of the expansion volume by lateral movement of the one or two screws is advantageously selected by the operator of an extruder to provide a selected expansion volume. That is, the distance of the lateral movement of the screw or screws is suitably selected by the operator to define the selected expansion volume.
• the expansion volume is targeted by the operator to add sufficient volume to the collection area to accommodate the total expected molten polymer foam volume; or some percentage of thereof.
• the total theoretical molten polymer foam volume of a shot may be calculated based on the amount of thermoplastic polymer and pneumatogen source plus any additional materials added to build the shot, further assuming all of the pneumatogen source will contribute to formation of pneumatoceles in the molten polymer foam to be obtained.
• the total expected molten polymer foam volume is the theoretical molten polymer foam volume, minus the expected amount of pneumatogen source dissolved in the polymer at the selected pressure (and therefore not contributing to pneumatoceles).
• industrially obtained pneumatogen sources are supplied with information suitable to calculate the total expected molten polymer foam volume based on the amount of pneumatogen source added to make the shot, and other processing conditions.
• the expansion volume is the difference between the shot volume and the expected molten polymer foam volume.
• the expansion volume is targeted to provide between 10% and 300% of the total expected molten polymer foam volume in the collection area, for example between 15% and 300%, or between 20% and 300%, or between 25% and 300%, or between 30% and 300%, or between 35% and 300%, or between 40% and 300%, or between 45% and 300%, or between 50% and 300%, or between 55% and 300%, or between 60% and 300%, or between 65% and 300%, or between 70% and 300%, or between 75% and 300%, or between 80% and 300%, or between 85% and 300%, or between 90% and 300%, or between 100% and 300%, or between 100% and 200%, or between 200% and 300%, or 100% to 105% or 100% to 110% or 100% to 115% or 100% to 120% or 105% to 110% or 110%
• the expansion volume is targeted to provide between 0.1% and 10% of the total expected molten polymer foam volume in the collection area, for example between 0.2% and 10%, or between 0.5% and 10%, or between 1.0% and 10%, or between 1.5% and 10%, or between 2% and 10%, or between 2.5% and 10%, or between 3% and 10%, or between 3.5% and 100%, or between 4% and 10%, or between 4.5% and 10%, or between 5% and 10%, or between 6% and 10%, or between 7% and 100%, or between 8% and 10%, or between 9% and 10%, or between 1% and 9%, or between 1% and 8%, or between 1% and 7%, or between 1% and 6%, or between 1% and 5%, or between 1 % and 4.5%, or between 1% and 4%, or between 1% and 3.5%, or between 1% and 3%, or between 1% and 2.5%, or between 1% and 2%, or between 1% and 1.5%, or between 1.5% and 2%, or between 2% and 2.5%
• a period of time is allowed to pass, or elapse, prior to dispensing the molten polymer foam from the extrader.
• the period of time is referred to as the expansion period.
• no mixing, transporting, shearing, or other physical manipulation or additional volume changes are carried out within the collection area during the expansion period. Instead, in such embodiments the shot is allowed to stand within collection area during the expansion period.
• a molten polymer foam is dispensed from the extruder outlet.
• the molten polymer foam is dispensed into a mold cavity, and the molten polymer foam is cooled to a temperature below a melt transition of the thermoplastic polymer to obtain a solidified polymer foam article.
• the expansion period is selected by the operator to be about 5 seconds to 600 seconds, depending on the mass of the sample, pneumatogen source and amount, and any additional materials present in the shot.
• the expansion period is 5 seconds to 600 seconds, or 5 seconds to 500 seconds, or 5 seconds to 400 seconds, or 5 seconds to 300 seconds, or 20 seconds to 600 seconds, or 20 seconds to 500 seconds, or 20 seconds to 400 seconds, or 20 seconds to 300 seconds, or 10 seconds to 200 seconds, or 20 seconds to 200 seconds, or 30 seconds to 200 seconds, or 40 seconds to 200 seconds, or 50 seconds to 200 seconds, or 5 seconds to 190 seconds, or 5 seconds to 180 seconds, or 5 seconds to 170 seconds, or 5 seconds to 160 seconds, or 5 seconds to 150 seconds, or 5 seconds to 140 seconds, or 5 seconds to 130 seconds, or 5 seconds to 120 seconds, or 5 seconds to 110 seconds, or 5 seconds to 100 seconds, or 5 seconds to 90 seconds, or 5 seconds to 80 seconds, or 5 seconds to 70 seconds, or 5 seconds to 60 seconds, or 5 seconds to 50 seconds, or
• expansion periods such as 600 seconds to 2000 seconds or even longer, may be suitably selected by the operator depending on the mass of the sample, pneumatogen source and amount, and any additional materials present in the shot. That is, even a very long residence time in the collection area - 30 minutes or even longer - does not result in any deleterious effects to the molten pneumatic mixture or to the solidified polymer foams that result after dispensing and cooling the polymer foam. This result is unexpected, since the molten polymer foam has been allowed an expansion volume, and thus pneumatoceles have formed and are dispersed within the molten, flowable polymer.
• molten polymer foam One of skill would not expect the molten polymer foam to remain molten and undisturbed under reduced pressure for up to 30 minutes or even longer, without significant migration of pneumatoceles from the molten material, and concomitant loss of the continuous polymer matrix defining a plurality of pneumatoceles dispersed throughout the entirety of the resulting polymer foam articles.
• a molten polymer foam is obtained that requires no expansion period (expansion period of 0 seconds) or requires only an expansion period of 0.1 second to 5 seconds, such as 0-1 second, 1-2 seconds, 2-3 seconds, 3-4 seconds, or 4-5 seconds to provide a molten polymer foam capable of forming the polymer foam articles described herein. In an injection molding machine, this means that depressurization may be immediately followed by dispensing the molten polymer foam.
• the expansion period is selected by the operator to be about 5 seconds to 0 seconds, depending on the mass of the sample, pneumaiogen source and amount, and any additional materials present in the shot.
• the expansion period is 5 seconds to 0.2 seconds, or 5 seconds to 0.3 seconds, or 5 seconds to 0.4 seconds, or 5 seconds to 0.5 seconds, or 5 seconds to 0.6 seconds, or 5 seconds to 0.7 seconds, or 5 seconds to 0.8 seconds, or 5 seconds to 0.9 seconds, or 5 seconds to 1 seconds, or 5 seconds to 2 seconds, or 5 seconds to 3 seconds, or 5 seconds to 4 seconds, or 0.1 seconds to 4 seconds, or 0.1 seconds to 3 seconds, or 0.1 seconds to 2 seconds, or 0.1 seconds to 1 second, or 1 second to 2 seconds, or 2 seconds to 3 seconds, or 3 seconds to 4 seconds, or 4 seconds to 5 seconds.
• Example 17 demonstrates an exemplary' but nonlimiting expansion period of 0.5 seconds. This expansion period is sufficient to result in a polymer foam article having a continuous polymer matrix defining a plurality of pneumatoceles dispersed throughout the entirety of the article, as shown in FIG. 56.
• the depressurization at the selected depressurization rate to provide a pressure drop, followed by maintaining the reduced pressure for a selected period may be referred to as a “depressurization step”.
• the rate of depressurization is inversely related to tire expansion period required to obtain a molten polymer foam that in turn provides a polymer foam article when applied to a forming element as described in any of the embodiments herein.
• an expansion time of 0 seconds to 5 seconds may be suitably selected.
• no expansion period is required in order to form a molten polymer foam that is dispensed to a forming element to provide a polymer foam article having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in the interior thereof, without protruding from the surface.
• rapid depressurization is coupled with a high backpressure required to initiate the depressurization, such as a backpressure of greater than 500 kPa, such as a backpressure of 500 kPa to 25 MPa or even higher, to obtain a very large volume polymer foam article.
• the polymer foam articles having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in the interior thereof are further characterized as having a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles throughout the entirety of the article.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety thereof.
• a depressurization step is followed by one or more additional pressurization/depressurization steps, for example 1 to 5 cycles of pressurization followed by depressurization.
• a pressurization step is carried out by reducing the volume in the collection area proximal to the molten pneumatic mixture, wherein the reduced volume results in a pressure increase (pressurization). The pressure increase is then maintained for a pressurization period of less than one second prior to carrying out a second depressurization step.
• the rate of pressurization in a pressurization step is selected to be 0.0059 GPa/sor more . That is, in embodiments, the rate of the defining of a reduced volume in the collection area, causing a pressure increase in the collection area, is 0.0059 GPa/s or more.
• one or more pressurizaiion/depressurizaiion cycles are suitably carried out prior to dispensing a molten polymer foam from the collection area.
• collecting a shot in the collection area under a pressure is a first pressurization step, and the first pressurization step is followed by a first depressurization step to complete a first pressurization/depressurization cycle.
• a molten polymer foam is dispensed from the collection area after a first pressurization cycle.
• a second pressurization step is carried out followed by a second depressurization step, to complete a second pressurization/depressurization cycle.
• each pressurization cycle includes an individually selected reduced volume (or applied pressure) in the collection area as well as pressurization rate and pressurization time, in accordance with the foregoing parameters for pressurization.
• each depressurization cycle includes an individually selected expanded volume (or reduced pressure), expansion (depressurization) rate, and expansion period in accordance with the foregoing parameters for depressurization.
• a customized pressurization/depressurization profile may be suitably determined by the operator to achieve optimal results for forming a polymer foam article as described below.
• a molten pneumatic mixture is subjected to 1 to 5 cycles of pressurization/depressurization, prior to dispensing the molten polymer foam from the collection area, further wherein each step in each cycle may be individually customized for pressure change, rate of pressure change, and period of maintaining the pressure change, in order to provide an optimized volume/time or pressure/time profile within the collection area.
• the polymer foam articles are generally characterized as monolithic articles having a continuous polymer matrix defining a plurality of pneumatoceles dispersed throughout the entirety of the article.
• the polymer foam articles are particularly characterized as having a continuous polymer matrix defining a plurality of pneumatoceles dispersed in a surface region of the article, wherein the surface region is defined as the area of the article between the article surface (the polymer foam-air interface) and a distance 500 microns interior from the surface.
• FIG. 1 A is a schematic diagram of an exemplary single screw injection molding apparatus 20 in accordance with disclosed embodiments herein, that is useful to perform the methods described herein to make molten polymer foams and polymer foam articles also disclosed herein. As shown in FIG.
• injection molding system 20 includes barrel 21, attached to motor or drive section 24 and mold section 26.
• Barrel 21 includes first end 21a, second end 21b, and defines hollow' interior barrel portion 22.
• Barrel portion 22 further defines nozzle 36 proximal to barrel second end 21b.
• Screw 30 is disposed within barrel portion 22 and comprises screw tip portion 34. Screw 30 is operably coupled to the motor section 24 for rotation of screw 30 around the central axis thereof; or for lateral movement indicated by arrow Z. Lateral movement of screw 30 may be in a direction generally from barrel first end 21a toward barrel second end 21b; or in a direction from barrel second end 21b toward barrel first end 21a. Lateral movement of screw 30 in either direction is optionally further coupled with rotational movement.
• Screw' 30 further includes one or more flights 31 which are mixing elements for mixing and transporting materials present within barrel portion 22 generally from barrel first end 21a toward barrel second end 21b.
• Screw 30 is disposed within barrel portion 22 in pressurably sealed relationship therein, to enable pressures in excess of atmospheric pressure to be maintained within barrel portion 22, by screw flights 31 within the barrel 21 and further by situation of check valve 32.
• Shutoff valve 37 is connected to barrel 21 near second end 20b, and is operable to control a fluid connection, a pressurized connection, or both between nozzle 36 and mold section 26.
• Check valve 32 disposed within barrel portion 22 and surrounding screw 30 is operable to prevent backpressure from urging materials residing in barrel portion 22 toward barrel first end 21a and thus provides a pressurably sealed, fluidly sealed, or pressurably fluidly sealed relationship between shutoff valve 37 and check valve 32.
• mold section 26 includes two mold sections 38 as shown. Mold sections 38 are removably joined together to define cavity 39. In some embodiments, one or more of the mold sections 38 are movable to allow for ejection of a solidified polymer foam article therefrom. In some embodiments, the mold sections 38 are situated in touching relation to each other; in other embodiments mold sections 28 are spaced apart by a gap. [00147] In embodiments, the methods disclosed herein are suitably carried out using an apparatus such as system 20 shown in FIGS. 1A-1B. In FIG.
• a selected mass of mixture 42A comprising a selected amount of thermoplastic polymer, pneumatogen source, and optionally one or more additional materials is added to barrel section 22 through inlet 28, as indicated by arrow A.
• the pneumatogen source is a pneumatogen and inlet 28 or another inlet (not shown) is a gas inlet in pressurized connection with barrel section 22; and the pneumatogen is added to the gas inlet at a selected pressure, while non-gaseous materials are added to inlet 28.
• motor 24 is operable to rotate screw 30. The rotation of screw 30 transports and mixes the mixture 42A to the screw tip 34.
• a heat source (not shown) is suitably employed to add heat to mixture 42A within the barrel portion 22.
• Motor 24 rotates screw 30 to transport mixture 42A present in barrel portion 22 in a direction generally proceeding from first end 21a of barrel 21 towards second end 21b, until reaching screw tip 34. Additionally, the rotation of screw 30 provides mixing of mixture 42A during the transportation.
• heating elements or heating bands (not shown) proximal to barrel portion 22 operate to heat mixture 42A. Multiple heating zones may be present proximal to barrel portion 22 to vary the temperature inside barrel portion 22 between first end 21a and second end 21b of barrel 21.
• screw 30 rotating within barrel portion 22 is operable to mix mixture 42A; and heat is added to the mixture as it is transported, thereby raising the temperature of the mixture above a melting point of the thermoplastic polymer to transform mixture 42A into molten pneumatic mixture 42B at least by reaching second end 21b of barrel 21.
• disposition of screw 30 within barrel portion 22, further wherein flights 31 are in contact with barrel 21 during rotation of screw 30; combined with check valve 32, shutoff valve 37 in a closed position, or both provides a pressurably sealed relationship within barrel portion 22 whereby the molten pneumatic mixture 42B is present in barrel portion 22 under a pressure in excess of atmospheric pressure.
• the pressure within barrel portion 22 is sufficient to prevent or substantially prevent pneumatocele formation, even if the pneumatogen source is above its critical temperature.
• rotation of screw 30 operates to transport the pressurized molten pneumatic mixture toward screw tip 34, transporting or building up a selected mass of pressurized molten pneumatic mixture 42B within a collection area 40 of barrel portion 22.
• Collection area 40 is defined as the region within the volume of barrel portion 22 extending between check valve 32 and shutoff valve 37 in FIG. 1A, further as a region of barrel portion 22 situated along X distance of barrel 21.
• a selected mass or “shot” of pressurized molten pneumatic mixture 42B is collected, or built up, in collection area 40 of barrel portion 22. Pressure within the collection area 40 is sufficient to prevent or substantially prevent pneumatocele formation in the molten pneumatic mixture. In embodiments, the shot substantially fills collection area 40.
• FIG. 1 A depicts a molten pneumatic mixture apparatus 20 wherein screw 30 is positioned to collect a shot of in collection area 40.
• the shot includes the selected mass of molten pneumatic mixture 42B and is disposed under a pressure within collection area 40.
• FIG. IB depicts apparatus 20 wherein screw 30 is positioned to define an expansion volume 44 within collection area 40.
• FIG. IB shows screw 30 in a position resulting from lateral movement of screw 30 toward barrel first end 21a; that is, screw 30 is retracted in FIG. IB relative to FIG. 1A. Retraction and the resulting partial displacement of screw 30 from collection area 40 defines an expansion volume 44 within collection area 40 and further causes a pressure to drop within collection area 40.
• screw 30 is retracted from collection area 40 at a rate that causes a rapid depressurization within collection area 40, such as 0.01 GPa/sec or greater. In some embodiments, rotation of screw 30 is halted before the retracting. In some embodiments, rotation of screw 30 is halted during the retracting, or after the retracting is completed.
• the retraction distance of screw 30, that is, the distance of lateral movement of screw 30 toward barrel first end 21a is selected by the operator to provide a suitable expansion volume 44.
• expansion volume 44 is selected by the operator to provide collection area 40 having a total volume that matches the total expected molten polymer foam volume of the shot; in such embodiments, the total volume in collection area 40 after adding expansion volume 44 is the total expected molten polymer foam volume of the molten pneumatic mixture 42B of FIG. IB. In other embodiments, expansion volume 44 is selected by the operator to provide collection area 40 having a total volume that is a percentage of the total expected molten polymer foam volume of a molten pneumatic mixture or shot residing in collection area 40; that is, the total volume in collection area 40 after adding expansion volume 44 equals about 50% to 120% of the total expected molten polymer foam volume. In some embodiments, expansion volume is set to provide a total volume in the collection area to accommodate 100% of the total expected molten polymer foam volume.
• expansion period a period of time, referred to as the “expansion period” is allowed to elapse or pass while the shot is held within collection area 40 as shown in FIG. IB, specifically wherein collection area 40 includes expansion volume 44.
• the expansion period is selected by an operator to be between 0 seconds and 2000 seconds.
• dining the expansion period the shot is allowed to stand undisturbed or substantially undisturbed within collection area 40.
• “undisturbed” means that the shot is not subjected to any processes causing mixing, shearing, or transporting (flow) of the shot during the expansion period.
• substantially undisturbed means that the shot is not purposefully perturbed by mixing, shearing, or transporting processes carried out during the expansion period but e.g. heat differentials, leakage, and other manufacturing issues may lead to inadvertent stress or strain to the shot residing in the collection area during the expansion period.
• a rapid rate of depressurization rate can be achieved, for example at least 0.01 GPa/s, such as 0.1 GPa/s to 5 GPa/s, or higher than 5 GPa/s depending on the apparatus employed and variables such as mass of molten polymer in the collection area 40, amount of pneumatogen or pneumatogen source mixed with or dissolved in the molten polymer, and the like.
• rapid depressurization is coupled with a high backpressure required to initiate the depressurization, such as a backpressure of greater than 500 kPa, such as a backpressure of 500 kPa to 25 MPa or even higher.
• the molten polymer foam is dispensed to a forming element, such as a mold, and cooled; or it is repressurized/depressurized for one or more additional cycles prior to dispensing to a forming element and cooled; and the resulting polymer foam articles are further characterized as having a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles throughout the entirety of the article.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety' thereof.
• rapid depressurization optionally coupled with high backpressure in an injection molding machine, enables formation of very large volume polymer fbam articles of nearly unlimited size and volume to be formed.
• polymer foam articles having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in tire interior thereof, without protruding from the surface; or even larger articles are suitably formed using rapid depressurization and optionally high backpressure.
• the volume and dimensions achievable using rapid depressurization are limited only by the amount of molten polymer that can be collected and machine limitations in introducing the pressure drop.
• the polymer foam articles having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in the interior thereof are further characterized as having a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles throughout the entirety of the article.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety thereof.
• rapid depressurization optionally coupled with high backpressure in an injection molding machine, allows an expansion period of 0 seconds to 5 seconds to be selected, while still enabling formation of polymer foam articles having a shape and volume sufficient to accommodate a theoretical sphere having a diameter of at least 2 cm and as much as 1000 cm or more, in at least one location in the interior thereof, without protruding from the surface.
• the selection of an expansion period of 0 seconds to 5 seconds is based on the type of thermoplastic polymer type used, amount of pneumatogen or pneumatogen source, and other specific and individual considerations of the operator in forming a polymer foam article in accord with the methods disclosed herein.
• Rapid depressurization particularly when used concomitant with high backpressure, provides a stabilized molten polymer foam that does not require an expansion period, or requires only a very short expansion period, to obtain a molded polymer foam article further characterized as having a continuous thermoplastic polymer matrix defining a plurality' of pneumatoceles throughout the entirety of the article.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety thereof.
• rapid depressurization optionally coupled with high backpressure in an injection molding machine, allows an expansion period of 600 seconds to 2000 seconds to be selected, while still enabling formation of polymer foam articles having a shape and volume sufficient to accommodate a theoretical sphere having a diameter of at least 2 cm and as much as 1000 cm or more, in at least one location in the interior thereof, without protrading from the surface.
• Rapid depressurization particularly when used concomitant with high backpressure, provides a stabilized molten polymer foam that can withstand 30 minutes or more of residence time inside an injection molding machine and still be dispensed to a forming element to obtain a molded polymer foam article further characterized as having a continuous thermoplastic polymer matrix defining a plurality' of pneumatoceles throughout the entirety' of tire article.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety thereof.
• the stability of the molten polymer foam is increased further, when employing an injection molding apparatus or machine such as the apparatus shown in FIGS. 1A-1B, by coupling rapid depressurization with high backpressure to initiate the depressurization.
• the stability of the molten polymer foam is evidenced by the surprising results that very large articles can be formed in a forming element; that the expansion period may be shortened or excluded; and also that a very long expansion period does not cause the stabilized molten polymer foam to collapse during the subsequent dispensing, molding, and cooling.
• nozzle shutoff valve 37 as shown in FIG. IB is opened and a molten polymer foam is dispensed from barrel 22.
• the molten polymer foam flows into cavity 39.
• the dispensing may be pressurized dispensing by mechanical means such as plunging using lateral movement of the screw, or by applying a pressurized gas to the collection area, but applying pressure is not necessary to dispense the molten polymer foam in some embodiments.
• pressure at nozzle 36 as shown in FIGS 1 A-1B dining dispensing of the molten polymer foam is 1 psi (about 7 kPa) to 20 psi (about 138 kPa) in excess of gravity, such as, without adding external sources of pressure such as by plunging the molten polymer foam using additional lateral movement of the screw 30 toward barrel second end 21b in FIGS. 1A-1B.
• the dispensing is accomplished by maintaining fluid connection between nozzle 36 and cavity 39. In some such embodiments the fluid connection is further a pressurized connection.
• pressure at nozzle 36 as shown in FIGS 1A-1B during dispensing of the molten polymer foam is about 500 kPa to 500 MPa, such as 1 MPa to 400 MPa, or 2 MPa to 300 MPa, or 3 MPa to 200 MPa, or 500 kPa to 1 MPa, 1 MPa to 10 MPa, 10 MPa to 50 MPa, 50 MPa to 100 MPa, 100 MPa to 200 MPa, or 200 MPa to 500 MPa, for example by laterally urging screw 30 toward barrel second end 21b in FIGS. 1A-1B or by applying another source of pressure, such as an applied gas pressure.
• another source of pressure such as an applied gas pressure
• screw 30 is urged back towards barrel second end 21b; that is, screw 30 is returned partially or completely to the position shown in FIG. 1 A in a pressurization step, which reduces the volume in collection area 40 and pressurizes the molten pneumatic mixture.
• the reduced volume within collection area 40 causes a pressure to increase within collection area 40.
• rotation of screw 30 is halted before the pressurization. In some embodiments, rotation of screw 30 is halted during the pressurization, or after the pressurization is completed.
• the pressurization distance of screw 30, that is, the distance of lateral movement of screw 30 toward barrel second end 21b is selected by the operator to provide a suitable volume and pressure. After a selected pressurization period, the operator may select dispensing of the molten pneumatic mixture, or may select one or more additional pressurization/depressurization cycles prior to the dispensing.
• the operator may select the rates of pressurization and depressurization in addition to volume/pressure and the time of maintaining the pressurization or depressurization. Additionally, the operator may suitably select rapid depressurization, high backpressure, or both for each one or more of the depressurization steps of the one or more cycles.
• the molten polymer foam is cooled or allowed to cool until it reaches a temperature below a melt transition of the thermoplastic polymer, such as the temperature present in ambient conditions of the surrounding environment.
• a melt transition of the thermoplastic polymer such as the temperature present in ambient conditions of the surrounding environment.
• pneumatoceles may continue to nucleate and/or develop (grow in size) after the molten polymer foam is dispensed and before the temperature cools sufficiently to reach a melt transition temperature of the thermoplastic polymer.
• Cooling of the molten polymer foam is accomplished using conventional methods for cooling of injection molded articles and includes immersing the mold in a liquid coolant having a set temperature, or spraying the mold with a liquid coolant, such as liquid water; impinging an air stream onto the mold; ambient air cooling; and the like without limitation.
• a liquid coolant such as liquid water
• apparatus 20 configured as shown in FIG. IB is employed to form a molten polymer fbam.
• FIG. IB shows screw 30 in a position resulting from lateral movement of screw 30 toward barrel first end 21a; that is, screw 30 is retracted in FIG. IB relative to FIG. 1A. Retraction and the resulting partial displacement of screw' 30 from collection area 40 defines an expansion volume 44 within collection area 40 and further causes a pressure to drop within collection area 40.
• Apparatus 20 configuration as shown in FIG. IB is employed to mix, heat, and transport molten pneumatic mixture 42B toward second end 21b of barrel 21 in substantially the same way as described above.
• apparatus 20 in the configuration shown in FIG. IB is employed to mix, heat, and transport molten pneumatic mixture 42B toward second end 21b of barrel 21; and then screw 30 is urged toward first end 21a of barrel 21 to pressurize the molten pneumatic mixture residing in collection area 40. Pressurization is following by rapid depressurization, optionally employed with a high backpressure, to obtain a stabilized polymer foam as described above
• thermoplastic polymer or mixture thereof that is useful for injection molding and/or for forming polymer foams, is usefully combined with any industrially usefill pneumatogen source using conventional technology such as a standard injection molding apparatus, optionally together with one or more additional materials as selected by the operator of the apparatus.
• thermoplastic polymers useful in conjunction with the methods, apparatuses, and articles described herein include any thermoplastics or mixtures thereof that are known in the industry to be usefill for injection molding, or injection molding of polymer foam articles; and mixtures of such polymers.
• Useful polymers are characterized as having a melt flow viscosity suitable for use in injection molding, such as in shot formation.
• the thermoplastic polymers may include a degree of crosslinking that is thermoreversible or that does not otherwise prevent a sufficient viscous melt flow for injection molding processes.
• thermoplastic polymers usefill in conjunction with the methods, apparatuses, and articles described herein include olefinic polymers such as polyethylene, polypropylene, poly a-olefins and various copolymers and branched/crosslinked variations thereof including but not limited to low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), thermoplastic polyolefin elastomer (TPE), ultra-high molecular weight polyethylene (UHMWPE), and the like; polyamides (PA), polyimides (PI), polyesters such as polyester terepthalate (PET) and polybutyene terepthalate (PBT), polyhydroxyalkanoates (PHA) such as polyhydroxybutyrate (PHB), polycarbonates (PC), poly (lactic acid)s (PLA), acrylonitrile-butadiene-styrene copolymers (ABS), polystyrenes, polyurethanes including thermoplastic polyamides (PA), polyimi
• mixed stream recycled plastics are useful in embodiments as the thermoplastic polymer.
• ocean waste plastics are mixed streams of polymeric waste harvested from oceans and beaches, and having exemplary content of 10%- 90% polyolefin content, 10%-90% PET content, l%-25% polystyrene content, and l%to 50% unknown polymer content.
• Such mixed plastic streams and waste plastic streams are similarly usefully to form molten polymer foams and polymer foam articles using the methods and apparatuses described herein.
• Example 11 shows the use of a mixed stream ocean waste plastic source having 20% recycled content.
• polymer foam articles made in accordance with the methods described herein may be recycled using the methods described herein. That is, in embodiments, a first polymer foam article in accordance with any of the embodiments described herein, and formed in accordance with any of the methods described herein, is also a source of thermoplastic polymer for farming a second polymer foam article in accordance with the methods described herein. In embodiments, the polymer foam articles described herein are suitably recycled employing any of the methods described herein for making a polymer foam article.
• a polymer foam article may be recycled, for example, by simply grinding a first polymer foam article made in accordance with the methods described herein, or otherwise dividing it into pieces of suitable size for direct use in a melt mixing apparatus; and applying the divided first polymer foam article to a melt mixing apparatus.
• the melt mixing apparatus may be an injection molding machine or an extruder.
• a second polymer foam article may be formed by carrying out any of the methods described herein for forming a polymer foam article, employing the divided first polymer foam article as the feedstock or source of polymer.
• mixed feedstocks may also be used, such as mixed sources of divided polymer foam articles (different thermoplastics, additives, and the like); or mixtures of divided polymer foam articles with other plastic materials such as virgin or used plastic sources.
• polystyrene foam articles is observed over a range of polymeric materials including but not limited to low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), high-impact polystyrene (HIPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA), thermoplastic polyurethane (TPU), and thermoplastic olefin (TPO).
• LDPE low-density polyethylene
• HDPE high-density polyethylene
• PP polypropylene
• HIPS high-impact polystyrene
• PET polyethylene terephthalate
• PBT polybutylene terephthalate
• PA polyamide
• TPU thermoplastic polyurethane
• TPO thermoplastic olefin
• Pneumatogen sources are widely available in the industry and conditions usefill to deploy pneumatogens during melt mixing are well understood and broadly reported. Accordingly, any pneumatogen source usefill for injection molding, reaction injection molding, or other methods of making of polymer foams, is usefill herein to form the molten polymer foams and solidified polymer foam articles in accordance with the methods, apparatuses, and polymer foam articles described herein.
• Pneumatogens usefill in connection with the methods and apparatuses described herein include air, CO2, and N2, either as encapsulated within a thermoplastic in the form of beads, pellets, and the like or in latent form, wherein a chemical reaction generates CO2 or N2 when heated within the melt mixing apparatus.
• Suitable pneumatogen sources include sodium bicarbonate, compounds based on a polycarboxylic acid such as citric acid, or a salt or ester thereof such as sodium citrate or the trimethyl ester of sodium citrate; mixtures of sodium bicarbonate with apolycarboxylic acid such as citric acid; sulfonyl hydrazides including p-toluene sulfonyl hydrazide (p-TSH) and 4,4’-oxybis-(benzenesulfonyl hydrazide) (OBSH), pure and modified azodicarbonamides, semicarbazides, tetrazoles, and diazinones.
• the pneumatogen source is optionally further encapsulated in a carrier resin designed to melt during the heating, mixing, and collection of a shot.
• usefill pneumatogen sources include commercially available compositions such as HYDROCEROL® BIH 70, HYDROCEROL® BIH CF-40-T, or HYDROCEROL® XH-901, all available from Clariant AG of Switzerland; PCX 7301, available from RTP Company of Winona, MN; PCX 27314, available from RTP Company of Winona, MN; CELOGEN ® 780, available from CelChem LLC of Naples, PL; ACTAFOAM® 780, available from Galata Chemicals of Southbury, CT; ACTAFOAM® AZ available from Galata Chemicals of Southbury, CT; ORGATER MB.BA.20, available from ADEKA Polymer Additives Europe of Mulhouse, France; ENDEX 1750TM, available from Endex International of Rockford, IL; and FOAMAZOLTM 57, available from Bergen International of East Rutherford, NJ.
• compositions such as HYDROCEROL® BIH 70, HY
• the pneumatogen source is a pneumatogen, wherein the pneumatogen is applied as a gas to a melt mixing apparatus, such as an apparatus similar to the extruder shown in FIGS 1A-1B.
• the gas is caused to dissolve within the thermoplastic polymer by direct pressurized addition to and mixing within the melt mixing apparatus.
• the gas becomes a supercritical fluid by pressurization, either prior to or contemporaneously with dissolution into the molten thermoplastic polymer.
• Applying a pneumatogen directly to an injection molding apparatus is referred to industrially as the MUCELL® process, as employed by Trexel Inc. of Wilmington, DE.
• a pneumatogen is usefully employed as the pneumatogen source in conjunction with the methods described herein by direct application of the pneumatogen to the thermoplastic polymer and one or more additional materials to form a molten pneumatic mixture.
• the pneumatogen source is added to the thermoplastic polymer, and any optionally one or more additional materials, in an amount that targets a selected density reduction of the thermoplastic polymer, in accordance with conventional art associated with desirable polymer foam density- and operation of pneumatogens and pneumatogen sources to form thermoplastic polymer foams.
• the amount of the pneumatogen source added to the thermoplastic polymer is not particularly limited; accordingly, we have found that up to 85% density reduction is achieved without the use of polymer or glass bubbles or the like, to provide a polymer foam article having the unique and surprising characteristics reported below and further having a targeted density' reduction of up to 85%.
• density reduction means a percent mass reduction in a polymer foam article compared to the same article without adding a pneumatogen (source) to make the article (that is, a polymer article excluding or substantially excluding pneumatoceles).
• the molten polymer foams and the polymer foam articles described herein suitably exclude glass or polymer bubbles, while providing a selected density reduction of up to 85%, for example 30% to 85%, such as 35% to 85%, 40% to 85%, 45% to 85%, 50% to 85%, 55% to 85%, 60% to 85%, 65% to 85%, 70% to 85%, 75% to 85%, 30% to 35%, 35% to 40%, 40% to 50%, 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75%, 75%, to 80%, or 80% to 85%.
• Including glass or polymer bubbles further extends the available density reduction of a polymer foam article made in accord with the methods herein. In some embodiments greater than 85% density reduction may be achieved.
• the polymer foam articles benefitting from the density reduction nonetheless are characterized as having a continuous polymer matrix throughout with pneumatoceles dispersed therein, including molded articles having a shape and a volume wherein a theoretical sphere, such as a glass or metal ball or marble, having a diameter of 2 cm would fit within the polymer foam article in at least one location, without protruding from the surface.
• the polymer foam articles have a shape and a volume wherein a sphere having a diameter of 2 cm - 1000 cm or more would fit within the polymer foam article in at least one location, without protruding from the surface.
• the polymer foam articles have a shape and a volume wherein a sphere having a diameter of 2 cm - 1000 cm would fit within the polymer foam article in at least one location, without protrading from the surface and further have a total article volume greater than 1000 cm 3 , a volume of at least 2000 cm 3 , a volume between 1000 cm 3 to 5000 cm 3 , a volume between 2000 cm 3 to 5000 cm 3 , or a volume of more than 5000 cm 3 .
• the shape of the polymer foam article is not limited and may generally be cuboid, spheroid, toroid, or any other shape desired.
• the amount of the pneumatogen source added to the thermoplastic polymer is not particularly limited; accordingly, we have found that up 85% of the total volume of a polymer foam article comprises pneumatoceles.
• the total volume of the pneumatoceles as a percent of the total volume of tire polymer foam article is referred to as the “void fraction” of the article; thus, void fraction of up to about 85% is achieved without including polymer or glass bubbles or the like, to provide a polymer foam article having the unique and surprising characteristics reported below and further having a targeted void fraction of up to 85% of tire volume of the polymer foam article.
• the molten polymer foams and the polymer foam articles described herein suitably exclude glass or polymer bubbles, while providing a void fraction of up to 85%, for example 5% to 85%, such as 10% to 85%, 15% to 85%, 20% to 85%, 25% to 85%, 30% to 85%, 35% to 85%, 40% to 85%, 45% to 85%, 50% to 85%, 55% to 85%, 60% to 85%, 65% to 85%, 70% to 85%, 75% to 80%, 80% to 85%, 5% to 10%, 10% to 15%, 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 50%, 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75%, 75% to 80%, or 80% to 85%.
• 5% to 85% such as 10% to 85%, 15% to 85%, 20% to 85%, 25% to 85%, 30% to 85%, 35% to 85%
• Including glass or polymer bubbles further extends the available void fraction of a polymer foam article made in accord with the methods herein. In some embodiments greater than 85% void fraction may be achieved.
• the polymer foam articles having 85% void fraction are nonetheless are characterized as having a continuous polymer matrix throughout with pneumatoceles dispersed therein, including molded articles having a shape and a volume wherein a sphere having a diameter of 2 cm - 1000 cm would fit within the polymer foam article in at least one location, without protruding from the surface and further have a total article volume greater than 1000 cm 3 , a volume of 2000 cm 3 or more, a volume between 1000 cm 3 to 5000 cm 3 , a volume between 1000 cm 3 and5000 cm 3 , or between 12000 cm 3 and5000 cm 3 , or a volume greater than 5000 cm 3 .
• thermoplastic polymer and a pneumatogen source are admixed prior to applying the admixture to a melt mixing apparatus for heating and mixing.
• thermoplastic polymer and a pneumatogen source are added separately to a melt mixing apparatus, such as by two different inlets or ports available for adding materials to the melt mixing apparatus.
• a solid mixture including both a thermoplastic polymer and a pneumatogen source are added as a single input to a melt mixing apparatus for heating and mixing.
• one or more additional materials are included or added to a melt mixing apparatus along with the thermoplastic polymer and pneumatogen source; such additional materials are suitably mixed or admixed with the thermoplastic polymer, the pneumatogen source, or both; or the one or more additional materials are added separately, such as by- in individual port or inlet to a melt mixing apparatus.
• suitable additional materials include colorants (dyes and pigments), stabilizers, brighteners, nucleating agents, fibers, particulates, and fillers.
• Specific examples of some suitable materials include talc, titanium dioxide, glass bubbles or beads, thermoplastic polymer particles, fibers, beads, or bubbles, and thermoset polymer particles, fibers, beads, or bubbles.
• suitable materials include fibers such as glass fibers, carbon fibers, cellulose fibers and fibers including cellulose, natural fibers such as cotton or wool fibers, and synthetic fibers such as polyester, polyamide, or aramid fibers; and including microfibers, nanofibers, crimped fibers, shredded or chopped fibers, phase- separated mixed fibers such as bicomponent fibers including any of the foregoing mentioned polymers, and thermosets formed from any of the foregoing polymers.
• suitable additional materials are waste materials, further shredded or chopped as appropriate and including woven or nonwoven fabrics, cloth, or paper; sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates; and other biological, organic, and mineral waste streams and mixed streams thereof.
• suitable additional materials are minerals such as calcium carbonate and dolomite, clays such as montmorillonite, sepiolite, and bentonite, micas, wollastonite, hydromagnesite/huntite mixtures, synthetic minerals, silica agglomerates or colloids, aluminum hydroxide, alumina-silica composite colloids and particulates, Halloysite nanotubes, magnesium hydroxide, basic magnesium carbonate, precipitated calcium carbonate, and antimony oxide.
• suitable additional materials include carbonaceous fillers such as graphite, graphene, graphene quantum dots, carbon nanotubes, and C «o buckeyballs.
• additional materials include thermally conductive fillers such as boronitride (BN) and surface-treated BN.
• one or more additional materials are included or added to a melt mixing apparatus along with the thermoplastic polymer and pneumatogen source in an amount of about 0.1% to 50% of the mass of the thermoplastic polymer, for example 0.1% to 45%, 0.1% to 40%, 0.1% to 35%, 0.1% to 30%, 0.1% to 25%, 0.1% to 20%, 0.1% to 15%, 0.1% to 10%, 0.1% to 9%, 0.1%to 8%, 0.1% to 7%, 0.1% to 6%, 0.1%to 5%, 0.1% to 4%, 0.1%to 3%, 0.1%to 2%, 0.1% to 1%, l%to 50%, 2% to 50%, 3% to 50%, 4% to 50%, 5% to 50%, 6% to 50%, 7% to 50%, 8% to 50%, 9% to 50%, 10% to 50%, 11% to 50%, 12% to 50%, 13% to 50%, 14% to 50%, 15% to 50%,
• a method of forming and collecting a molten polymer foam includes the following: heating and mixing a thermoplastic polymer and a pneumatogen source to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the critical temperature of the pneumatogen source and a pressure applied to molten pneumatic mixture is sufficient to substantially prevent formation of pneumatoceles; collecting a selected amount of the molten pneumatic mixture in a collection area; defining an expansion volume in the collection area proximal to the molten pneumatic mixture that results in a pressure drop; maintaining the expansion volume for an expansion period of time; and collecting a molten polymer foam from the collection area.
• the molten pneumatic mixture is undisturbed or substantially undisturbed during the expansion period.
• defining the expansion volume is accomplished at a rapid rate of depressurization (that is, the rate of defining the pressure drop) which is at least 0.01 GPa/s, in embodiments 0.1 GPa/s or greater; and in some embodiments is 1.0 GPa/s or even greater, such as up to 5.0 GPa/s; or 0.01 GPa/s to 5.0 GPa/s, or or 0.1 GPa/s to 5.0 GPa/s, or 1 GPa/s to 5.0 GPa/s, or 0.01 GPa/s to .0 GPa/s, or 0.01 GPa/s to 3.0 GPa/s, or 0.01 GPa/s to 2.0 GPa/s, or 0.01 GPa/s to 1.0 GPa/s, or 0.01 GPa/s to 0,1 GPa/s, or 0.1
• rapid depressurization is coupled with a high backpressure, that is, a backpressure of 500 kPa or greater, such as a backpressure of 500 kPa to 25 MPa, or 1 MPa to 25 MPa, or 2 MPa to 25 MPa, or 3 MPa to 25 MPa, or 4 MPa to 25 MPa, or 5 MPa to 25 MPa, or 6 MPa to 25 MPa, or 7 MPa to 25 MPa, or 8 MPa to 25 MPa, or 9 MPa to 2 MPa, or 10 MPa to 25 MPa, or 500 kPa to 20 MPa, or 500 kPa to 15 MPa, or 500 kPa to 12 MPa, or 500 kPa to 10 MPa, or 500 kPa to 9 MPa, or 500 kPa to 8 MPa, or 500 kPa to 7 MPa, or 500 kPa to 6 MPa, or 500 kPa to 5 MPa, or 500 kPa to 4 MPa, or 500
• a stabilized molten polymer foam is obtained that requires no expansion period or requires a shortened expansion period of 0 to 5 seconds such as 0-1 second, 1-2 seconds, 2-3 seconds, 3-4 seconds, or 4-5 seconds to provide a molten polymer foam capable of forming the polymer foam articles described herein, including articles having a shape and a volume wherein a sphere having a diameter of 2 cm - 1000 cm, that is, including 20 cm and above, would fit within the polymer foam article in at least one location, without protrading from the surface; and further have a total article volume greater than 1000 cm 3 , a volume of 2000 cm 3 or more, or a volume between 1000 cm 3 and 5000 cm 3 , between 2000 cm 3 and 5000 cm 3 , or a volume greater than 5000 cm 3 .
• collecting the molten polymer foam includes applying the molten polymer foam to a cavity defined by a mold; and cooling the molten polymer foam below a melt temperature of the thermoplastic polymer to obtain a polymer foam article.
• the cooled polymer foam article obtains the shape and dimensions of the mold, further wherein polymer foam is characterized as a continuous polymer matrix having pneumatoceles distributed throughout the entirety of the article.
• the molten polymer foam is applied to a mold cavity by allowing the molten polymer foam to flow and enter a mold cavity by gravitational force; in some such embodiments the flow is unimpeded and is allowed to fall into an open cavity.
• the molten polymer foam is applied under pressurized flow to a forming element.
• the molten polymer foam is delivered to a mold cavity by fluid connection thereto from a nozzle or other means of delivery of molten polymer foam from a collection area of a melt mixing apparatus.
• an extrader is adapted and designed to dispense a molten mixture from an outlet into a forming element, which is a mold defining a cavity therein, and designed and adapted to receive a molten polymer mixture, such as a molten pneumatic mixture.
• a forming element is a mold configured and adapted to receive a molten thermoplastic polymer dispensed from an outlet, further wherein a mold is characterized as generally defining a void or cavity having the selected shape and dimensions of a desired article.
• dispensing from an extruder is accomplished by mechanical plunging, by applying a gaseous pressure from within the barrel of the extruder, or a combination thereof.
• an outlet, valve, gate, nozzle, or door to the collection area is simply opened after the expansion period has passed, and the molten polymer foam is allowed to flow unimpeded through the outlet; the molten flow is then directed to a cooling or other processing apparatus, or the molten flow is allowed to pour into a forming element.
• the forming element is fluidly connected to the outlet and is further designed and adapted to be filled with a molten mixture so that the molten mixture obtains a selected shape when cooled and solidified.
• the forming element is fluidly connected to the extruder outlet such that a pressure is maintained between the collection area, the outlet, and the forming element or mold.
• Any conventional thermoplastic molding or forming process associated with injection molding of polymer articles, such as polymer foam articles, is suitably employed to mold the molten polymer foams described herein.
• the molten polymer foam is allowed to flow unimpeded through the outlet, or is plunged under a pressure from the outlet without further impedance of flow, the molten flow eventually impinges on a surface, such as a surface generally perpendicular to the direction of the molten flow.
• a surface such as a surface generally perpendicular to the direction of the molten flow.
• the molten polymer foam is dispensed into a mold cavity, followed by cooling the molten polymer foam to a temperature below a melt transition of the thermoplastic polymer, to obtain a solidified polymer foam article.
• the molten polymer foam is allowed to flow, or is “poured” unimpeded from the outlet of a melt mixing apparatus and into a mold that is configured as an open container.
• the open container mold is completely filled with molten polymer foam; in other embodiments the open container mold is partially filled with molten polymer foam.
• the molten polymer foam is dispensed by plunging, or urging the screw of the extruder laterally in a direction toward the nozzle.
• the dispensing includes partially filling the mold cavity with molten polymer foam, wherein 50% or less of the mold cavity volume is occupied by the molten polymer foam, such as 1% to 50%, or 5% to 50%, or 10% to 50%, or 20% to 50%, or 30% to 50%, or 40% to 50%, or 1% to 40%, or 1% to 30%, or 1% to 20%, or 1% to 10%, or 1% to 5% of the mold cavity' volume is occupied by the molten polymer foam after the dispensing.
• 50% or less of the mold cavity volume is occupied by the molten polymer foam, such as 1% to 50%, or 5% to 50%, or 10% to 50%, or 20% to 50%, or 30% to 50%, or 40% to 50%, or 1% to 40%, or 1% to 30%, or 1% to 20%, or 1% to 10%, or 1% to 5% of the mold cavity' volume is occupied by the molten polymer foam after the dispensing.
• the dispensing includes substantially filling the mold cavity with molten polymer foam, wherein 50% to 99.9% of the mold cavity' volume is occupied by the molten polymer foam, such as 50% to 99.5%, or 50% to 99%, or 50% to 98%, or 50% to 97%, or 50% to 96%, or 50% to 95%, or 95% to 99.9%, or 96% to 99.9%, or 97% to 99.9%, or 98% to 99.9%, or 99% to 99.9%, or 99.5% to 99.9% of the mold cavity volume is filled with the molten polymer foam after the dispensing.
• the dispensing includes completely filling the mold cavity with molten polymer foam, wherein 100% of the mold cavity is occupied by the molten polymer foam after the dispensing.
• a coiled molten flow substantially free of shear, or a substantially linear molten flow is provided by fluid connection between the outlet of the extrader and into a mold cavity.
• the molten flow may obtain a coiled molten flow, either by impinging on a perpendicular surface thereof or by flowing down a substantially vertical wall or side of a mold cavity and collecting at the bottom of the mold cavity.
• FIG. 41 shows a variation of the extruder of FIGS 1A-1B wherein mold 26 of apparatus 20 is situated on a substantially horizontal surface 100.
• FIG. 41 there is no shutoff valve 37 at distal end 21b of barrel 21; instead, in FIG. 41, collection area 40 extends to a mold valve 137 situated proximal to mold cavity 39 defined within mold 26.
• mold valve 137 is operable to define collection area 40, or to provide an outlet for dispensing a molten polymer foam to mold cavity 39 via a substantially linear horizontal flow 110.
• Mold valve 137 is situated a height H above horizontal surface 100, and a height H2 above the floor or bottom 120 of mold 26 as situated on horizontal surface 100.
• mold valve 137 is selectively opened to provide fluid connection between collection area 40 and mold cavity 39.
• mold valve 137 is selectively opened to provide a substantially linear horizontal flow 110 of molten polymer foam entering mold cavity 39.
• the linear flow flows downward over the distance H2, and in some embodiments obtains a coiled molten flow as it proceeds to fill mold cavity 39.
• Other related variations of the methods and apparatuses are contemplated to provide a coiled molten flow as described herein.
• the coiling and folding flow pattern is visible at the surface of the article.
• An example of such a visible flow pattern may be seen in e.g. FIGS. 2-2 and 2-4.
• the interior of the article is free of or substantially free of flow patterns, interlaces, or other evidence of coils and folds.
• cryogenic fracturing of such polymer foam articles does not result in fracturing at any discernible interface between coils and folds; and both macroscopic and microscopic inspection of the interior of such polymer foam articles obtains a homogeneous appearance with respect to flow patterns.
• the physical properties of such polymer foam articles are consistent with the physical properties obtained by subjecting the molten polymer foam to a directed fluid flow, via fluid connection between an outlet of a melt mixing apparatus and a mold, or subjecting the molten polymer foam to pressurized directed fluid flow.
• the methods herein include partially, substantially, or completely filling a mold with the molten polymer foam formed in accordance with the foregoing described methods, then cooling the molten polymer foam to form a solidified polymer foam; and in embodiments further removing the solidified polymer foam article from the mold.
• the molten polymer foam is a stabilized molten polymer foam.
• the cooling is cooling to a temperature below a melt transition of the thermoplastic polymer.
• the cooling is cooling to a temperature in equilibrium with the ambient temperature of the surrounding environment.
• the mold further includes one or more vents for pressure equalization in the mold during filling thereof with molten polymer foam, but in other embodiments no vents are present. After cooling, a polymer foam article may be removed from the mold for further modification or use.
• the polymer foam continues to expand after removal of the polymer foam article from the mold. That is, the polymer foam article expands after removal of the article from the mold, and the density of the article decreases as a result of the post-mold expansion.
• Table 1 provides useful but non-limiting examples of processing conditions employed to make a molten polymer foam using a conventional single screw extruder type reaction injection molding apparatus, further by employing one or more representative thermoplastic polymers and a citric acid-based pneumatogen source as indicated.
• molds usefully employed to form the polymer foam articles made using the methods, and materials disclosed herein include molds that define cavities that may be filled by a single shot of molten polymer foam, or a series of cavities that may be filled by a single shot of molten polymer foam. As such, the size of the mold cavity is limited only by the size of the shot that can be built in the melt mixing apparatus employed by the user.
• Representative mold cavities having volumes of up to 1x10 3 cm 3 are useful for making large parts such as automobile cabin or exterior parts, I-beam construction parts, and other large plastic items suitably employing a polymer foam.
• the shape of the mold cavities are not particularly limited and may be complicated in terms of overall shape and even surface patterns and features, for example shapes recognizable as dumbbells, tableware, ornamental globes with raised geographical features, human or animal or insect shapes, framework or encasement shapes for framing or encasing e.g. electronic articles, appliances, automobiles, and the like, shapes for later disposing and fitting screws, bolts, and other non-thermoplastic items into or through the polymer foam article; and the like are all suitable mold shapes for molding a polymer foam article as described herein.
• the cavity includes a thickness gradient of up to 300% as to one or more regions of the cavity.
• Table 2 provides useful but non-limiting examples of mold cavity volumes and dimensions of molds usefill to mold the molten polymer foams, either by pressurized flow or by unimpeded flow of the molten polymer foam into the mold. Additionally, larger mold volumes, such as up to 100,000 cm 3 or larger are useful where shot mass is suitably increased.
• a polymer foam article is formed using the foregoing described methods, materials, and apparatuses.
• the polymer foam article is a discrete, monolithic object made by forming or molding a molten polymer foam in accordance with any of the methods and materials disclosed above as well as variations thereof which are combinable in any part and in any manner to form a molten polymer foam as described above.
• any combination of the foregoing methods results in formation of a polymer foam article comprising, consisting essentially of, or consisting of a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles.
• the continuous thermoplastic polymer matrix comprises, consists of, or consists essentially of a solid thermoplastic polymer, that is, the thermoplastic polymer is present at a temperature below a melt transition thereof.
• the continuous thermoplastic polymer matrix further includes one or more additional materials dispersed in the solid thermoplastic polymer.
• the polymer foam articles obtain densify reductions, based on the densify of the thermoplastic polymer and any other materials added to form the polymer foam, of a selected percent based on the amount of pneumatogen source added to the shot. In embodiments, a density reduction of 30%, 40%, 50%, 60%, 70% and even up to 80% to 85% densify' reduction, as selected by the user. In embodiments, up to 85% densify reduction is achieved solely by the presence of pneumatoceles distributed discontinuously in the polymer matrix. In embodiments, the polymer foam articles exclude hollow particulates such as polymer or glass bubbles added to the shot prior to forming the polymer foam article using the methods and apparatuses described herein.
• the polymer foam articles herein are characterized as having a continuous thermoplastic polymer matrix throughout the entirety thereof or substantially throughout the entirety thereof.
• very large polymer foam articles may be suitably formed from the molten polymer foams disclosed herein to include a continuous polymer matrix defining a plurality of pneumatoceles.
• “Large polymer foam articles” are those having a shape and a volume wherein a sphere having a diameter of 20 cm would fit within the article in at least one location, without protruding from the surface.
• a “large polymer foam article” has a shape and a volume wherein a sphere having a diameter of 20 cm would fit within the polymer foam article in at least one location, without protrading from the surface, and further has a total volume of 1000 cm 3 or more, for example 2000 cm 3 or more, 3000 cm 3 or more, 4000 cm 3 or more, or 5000 cm 3 or more, or any volume between 1000 cm 3 and 5000 cm 3 ; or between 2000 cm 3 and 5000 cm 3 and including volumes up to 10,000 cm 3 , up to 20,000 cm 3 , up to 50,000 cm 3 , or even up to 100,000 cm 3 or greater.
• Large polymer foam articles may be suitably formed from stabilized molten polymer foam to include a continuous polymer matrix defining a plurality of pneumatoceles throughout the entirety thereof.
• the volume of the article is limited only by the size of the mold cavity and the size of the shot that can be collected in the melt mixing apparatus.
• a large article is formed from a single shot dispensed from a single outlet of a melt mixing apparatus, that is, without splitting of the molten polymer foam flow' to multiple simultaneous distribution pipes, nozzles, or other methods of directing multiple molten streams simultaneously into a single mold cavity.
• thick polymer foam articles may be suitably formed to include a continuous polymer matrix defining a plurality of pneumatoceles. Thickness as used herein refers to straight line distance through the interior of a polymer foam article between any two points on the surface thereof. “Thick” articles are defined as having a thickness of 2 cm or more, such as 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, or even 50 cm or more.
• a polymer foam article is formed using the methods and materials described herein that is characterized as being both large and thick, further wherein the large, thick polymer foam article is nonetheless characterized as having a continuous polymer matrix defining a plurality of pneumatoceles throughout the article.
• a large, thick article is formed from a single shot dispensed from a single outlet of a melt mixing apparatus, that is, without splitting of the molten polymer foam flow to multiple simultaneous distribution pipes, nozzles, or other methods of directing multiple molten streams simultaneously into a single mold cavity.
• the polymer foam articles formed using the methods described herein have a shape and a volume wherein a (theoretical) sphere having a diameter of 2 cm would fit within the polymer foam article in at least one location, without protruding from the surfece of the article.
• the polymer foam articles include a shape and a volume wherein a (theoretical) sphere having a diameter of greater than 2 cm would fit within the polymer foam article in at least one location, without protrading from the surfece of the article.
• the polymer foam articles have a shape and a volume wherein a (theoretical) sphere having a diameter of 2 cm to 1000 cm would fit within the polymer foam article in at least one location, without protruding from the surface of the article; for example, in one or more embodiments, a (theoretical) sphere having a diameter of 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, 50 cm, 60 cm, 70 cm, 80 cm, 90 cm, 100 cm, 200 cm, 300 cm, 400 cm, 500 cm, 600 cm, 700 cm, 800 cm, 900, 1000 cm, 3 cm-4 cm, 5 cm-6 cm, 7 cm-8 cm, 9 cm- 10 cm, 11 cm- 12 cm, 13 cm- 14 cm, 15 cm- 16 cm, 17 cm- 18 cm, 19 cm-20 cm, 20
• the polymer foam articles formed using the methods described herein have a shape and a volume wherein two or more (theoretical) spheres having a diameter of 2 cm would fit within the polymer foam article without overlapping, and without any of the spheres protruding from the surface of the article.
• two or more (theoretical) spheres having a diameter of 2 cm would fit within the polymer foam article without overlapping, and without any of the spheres protruding from the surface of the article.
• 2, 3, 4, 5, 6, 7, 8, 9, 10, 10-15 15-20, 20-25, 25-30, 30-35, 35-40,40- 45, 45-50, 50-55, 55- 60, 60-65, 65-70, 70-75, 75-80, 80-85, 85-90.
• the polymer foam articles have a shape and a volume wherein a (theoretical) sphere having a diameter of 2 cm would fit within the polymer foam article in at least one location without protrading from the surface of the article
• the polymer foam article further includes one or more locations wherein a (theoretical) sphere having a diameter of 2 cm would not fit, such that the theoretical sphere placed in such a location would protrude from the surface of the article.
• Such articles are shown in FIGS. 2-2, 32, and 33. FIG.
• FIGS. 32 and 33 show a polymer foam article made in accord with Example 12: a molded 9 inch (22.9 cm) diameter sphere having a cylindrical feature attached, wherein the diameter of the cylindrical feature varies between 5.64 mm and 8.99 mm, depending on where the cylinder is measured.
• the cylindrical features integrally connected to the spheres in FIGS 32 and 33 have a diameter smaller than 2 cm, and accordingly would not accommodate a theoretical 2 cm diameter sphere without the sphere protruding from the cylinder surface.
• obtaining a rapid depressurization rate that is, depressurization rate of at least 0.01 GPa/s to 5 GPa/s
• obtaining a rapid depressurization rate that is, depressurization rate of at least 0.01 GPa/s to 5 GPa/s
• obtaining a rapid depressurization rate that is, depressurization rate of at least 0.01 GPa/s to 5 GPa/s
• provide the unexpected advantage of enabling very large volume polymer foam articles to be formed that is, polymer foam articles having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in the interior thereof, without protruding from the surface.
• rapid depressurization is coupled with a high backpressure required to initiate the depressurization, such as a backpressure of greater than 500 kPa, such as a backpressure of 500 kPa to 500 MPa or even higher, to obtain a very large volume polymer foam article.
• the polymer foam articles having a shape and volume sufficient to accommodate a theoretical 20 cm - 1000 cm diameter sphere in at least one location in the interior thereof are further characterized as having a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles throughout tire entirety of the article.
• a surface region extending 500 microns from the surface of the article comprises compressed pneumatoceles throughout the entirety thereof.
• Example 22 An exemplary but non-limiting very large polymer foam article is demonstrated in Example 22 and shown in FIG. 73, wherein a solid rectangular cuboid polymer foam article having a volume of about 17,000 cm 3 is formed, further wherein the article would fit two theoretical 20 cm diameter spheres in the interior thereof without either of the spheres protruding from the surface of the article.
• the slower-cooling interior of larger articles show minimal or no evidence of pneumatocele coalescence during cooling.
• the pneumatoceles remain intact or substantially intact during cooling of the molten polymer foam and do not coalesce during cooling, resulting in a continuous polymer matrix regardless of size, thickness, or volume of the polymer foam article formed.
• the continuous polymer matrix as a structural feature of the polymer foamed articles in accord with the foregoing methods, apparatuses, and materials is characterized as present throughout the entirety of the polymer foamed article, including the surface region thereof.
• the surface region may be suitably characterized as the interior area of a polymer foam article that is 500 microns or less from the surface.
• the surface region as defined herein is a portion of the area of a foamed article conventionally referred to the “skin layer”, which is a region free or pneumatoceles or substantially free of pneumatoceles in polymer foam articles made using conventional methods.
• Conventionally formed foam articles include a skin layer that is at least as thick as the surface region, that is, 500 microns thick; but often the skin layer is much thicker and may proceed as far as 1 mm, 1.5 mm, 2 mm, 2.5 mm, even 3 mm from the surface of the article.
• the polymer foam articles formed using the presently disclosed methods obtain a true foam structure from tire surface thereof and throughout the entire thickness and volume thereof.
• microscopic inspection reveals evidence of pneumatoceles on the surface of the polymer foam articles formed using the conditions, processes, and materials disclosed herein Accordingly, the methods disclosed herein obtain unexpected results in terms of the continuous nature of the polymer matrix structure throughout the entirety of the polymer foam article, in any direction, and in every region thereof including within the interior of very large and/or thick polymer foam articles and also at the surface and in the surface region of the article.
• a polymer foam article made using the methods disclosed herein may appear to have a skin layer: that is, the surface region of the article can appear to be different from the interior region of the article.
• the surface regions of polymer foam articles made by the present methods include a plurality of compressed pneumatoceles. Macroscopically the compressed pneumatoceles create an appearance suggesting a skin layer; however, microscopic inspection reveals that the visually apparent difference arises from a “flattened” or compressed disposition of the continuous polymer matrix near the surface of the article.
• a surface region of a polymer foamed article made using the methods disclosed herein includes a plurality of compressed pneumatoceles.
• the compressed pneumatoceles are present in the surface region of a polymer foam article made using the methods disclosed herein.
• compressed pneumatoceles are present within an interior area of a polymer foam article that is 500 microns or less from the surface.
• compressed pneumatoceles are present within an interior area of a polymer foam article that is as far as 2 cm from the surface.
• Compressed pneumatoceles are defined as pneumatoceles having a circularity of less than 1, wherein a circularity value of zero represents a completely non-spherical pneumatocele, and a value of 1 represents a perfectly spherical pneumatocele.
• pneumatoceles having circularity of less than 0.9 are observed in the surface region of foamed polymer articles, further wherein 10% to 90%, or 10% to 80%, or 10% to 70%, or 10% to 60%, or 10% to 50%, or 10% to 40%, or 10% to 30%, or 10% to 20%, or 20% to 80%, or 20% to 70%, or 20% to 60%, or 20% to 50%, or 20% to 40%, or 20% to 30%, or 30% to 70%, or 30% to 60%, or 30% to 50%, or 30% to 40% of the pneumatoceles in the surface region have a circularity of 0.9 or less.
• an average circularity in the surface region of the foamed polymer articles is 0.70 to 0.95, such as 0.75 to 0.95, or 0.80 to 0.95, or 0.85 to 0.95, or 0.90 to 0.95, or 0.70 to 0.90, or 0.70 to 0.85, or 0.70 to 0.80, or 0.70 to 0.75, or 0.70 to 0.75, or 0.75 to 0.80, or 0.80 to 0.85, or 0.85 to 0.90, or 0.90 to 0.95.
• compressed pneumatoceles are present in a polymer foam article more than 500 microns from the surface thereof.
• compressed pneumatoceles are present up to 1 mm from the surface of a polymer foam article, or up to 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 1 cm, or more from the surface thereof.
• the region of compressed pneumatoceles in the polymer foam article corresponds to 0.01% to 70% of the total volume of the article, for example 0.1% to 70%, or 0.5% to 70%, or 1% to 70%, or 2% to 70%, or 3% to 70%, or 4% to 70%, or 5% to 70%, or 6% to 70%, or 7% to 70%, or 8% to 70%, or 9% to 70%, or 10% to 70%, or 15% to 70%, or 20% to 70%, or 30% to 70%, or 40% to 70%, or 50% to 70%, or 60% to 70%, or 0.01% to 60%, or 0.01% to 60%, or 0.01% to 50%, or 0.01% to 40%, or 0.01% to 30%, or 0.01% to 20%, or 0.01% to 10%, or 0.01% to 9%, or 0.01% to 8%, or 0.01% to 7%, or 0.01% to 6%, or 0.01% to 5%, or 0.01% to 4%, or 0.01% to 3%, or 0.01% to 2%, or 0.01% to
• FIGS. 12 and 14 shows a plot of average pneumatocele size and average pneumatocele count versus average pneumatocele circularity for two polymer foam articles made using the presently disclosed methods. Quantitative analysis of pneumatocele size and distribution reveals an inverse relationship between the average pneumatocele size and pneumatocele circularity, and an inverse relationship between the average pneumatocele size and the number of pneumatoceles.
• FIG. 18 additionally shows visual evidence that pneumatoceles are present to the surface of the polymer foam articles formed using the methods, materials, and apparatuses as described herein.
• FIG. 18 additionally shows visual evidence that a plurality of compressed pneumatoceles are present substantially 500 microns from the surface of the polymer foam articles formed using the methods, materials, and apparatuses as described herein.
• the polymer foam articles presently disclosed obtain a significant difference from foam articles of the prior art.
• the “skin layer”, or first 500 microns of thickness of a foam article made by conventional processes include no pneumatoceles or substantially no pneumatoceles, it is a feature of the prior art foam articles generally that the pneumatoceles are spherical wherever they are located. Thus, at the thickness in a conventional foam article where pneumatoceles are observed, they are generally spherical, having circularity near or about 1.
• Compressed pneumatoceles are not formed using conventional methodology to make foamed articles, and therefore no distribution of pneumatocele circularity is observed in such conventional foam articles. Further, pneumatoceles are not even formed in the first 500 microns thickness of a foam article made by conventional processes, so no comparisons regarding pneumatoceles can be drawn as to the surface region of the foamed polymer articles as described herein and the foamed articles made using conventional injection molding methods. [00216] Further, conditions, processes, and materials disclosed herein are suitably optimized to form polymer foam articles having different physical properties depending on the targeted end use or application. For example, the density of a polymer foam article is suitably varied as a function of expansion volume.
• a molten polymer foam is suitably dispensed by splitting the flow of molten polymer foam into 2, 3, 4, or more pathways heading to multiple molds or mold sections to form multiple polymer foam articles from a single shot.
• two shots are used to fill a single mold, wherein the first shot is different from the second shot in terms of the thermoplastic polymer content or ratio of mixed polymers, the pneumatogen source, the one or more additional materials optionally included, density, void fraction, depth of the region of compressed pneumatoceles, or some other material or physical property' difference.
• a polymer foam article made using the methods disclosed herein was subjected to fastener pull out testing according to ASTM D6117.
• the polymer foam articles obtain superior pull out strength over foam articles made using conventional foaming methods.
• the polymer foam articles formed using the materials, methods, and apparatuses disclosed herein require no pre-drilling, tapping or engineering of the fastener location.
• a polymer foam article made using the methods disclosed herein was subjected to ballistic testing.
• NU National Institute of Justice
• a series of 3 inch thick polymer foam articles were formed from poly ether-amide block copolymers (PEBAX®), linear low density polyethylene (LLDPE), and polypropylene using a citric acid based pneumatogen source.
• PEBAX® poly ether-amide block copolymers
• LLDPE linear low density polyethylene
• Polypropylene using a citric acid based pneumatogen source.
• Polymer foam articles made using all three of these thermoplastic polymers were found to stop .22 LR handgun bullets, passing NIJ Level I; and were found to stop 9mm LUGER® handgun bullet, passing NIJ Levels II and HA.
• cc means “cubic centimeter’’ or “cubic centimeters” (cm 3 ), “sec” means “second” or “seconds”.
• a mixture was prepared by blending a polymer (which may be in the form of pellets, powder, beads, granules and the like) with a foaming agent (blowing agent) and any other additives such as a filler.
• the mixture was introduced to the injection unit, and the rotating injection unit screw moved the mixture forward in the injection unit barrel, thus forming a heated fluid material in accordance with normal injection molding processes.
• B) A set volume of the material was dosed to the front of the barrel of the injection unit by rotation of the screw, thus moving the set volume from the feed zone to the front of the screw.
• a mixture was prepared by blending a polymer (which may be in the form of nurdles, pellets, powder, beads, granules and the like) with a chemical foaming agent, and any other additives such as a filler. The mixture was introduced to the injection unit, and the rotating injection unit screw moved the material forward in the injection unit barrel, thus forming a heated fluid material in accordance with normal injection molding processes.
• B) A set volume of the material was dosed to the front of the barrel of the injection unit by rotation of the screw, thus moving the set volume from the feed zone to the front of the screw.
• the screw was rotated to move the material between the screw and the nozzle, thereby providing the set volume.
• compression the screw was moved backwards away from the nozzle without or substantially without rotation so as to avoid moving more of the material to the front of the screw.
• the decompression rate that is, the rate of depressurization, is 0.006 GPa or less.
• a space free of the mixture between the screw and the nozzle was created within the barrel, the intentional space having a volume termed herein “decompression volume”.
• FIG. 2-1 is a photographic image of the first part, molded using the standard foam molding process. As seen in the image, the standard foam process did not yield a part that filled the mold cavity, and the part did not match the shape of the spherical cavity of the mold.
• FIG. 2-2 is a photographic image of the second part, molded using the MFIM process. As seen in the image, the MFIM process yielded a part that entirely or substantially filled the spherical mold cavity and the part matched or substantially matched the shape of the spherical cavity of the mold.
• FIGs 2-3 and 2-5 are photographic images of one of the pieces of the part made according to the standard foam molding process. As seen in the images, the first part contained a large hollow cavity.
• FIGs 2-4 and 2-6 are photographic images of one of the pieces of the second part. As seen in the images, the second part lacked the large hollow cavity of the standard foam process part. The MFIM part had a cell structure throughout.
• Example 2
• Two parts were formed by foam injection molding, a Part A in accordance with a standard foam molding process, and a Part B in accordance with an MFIM process.
• LDPE/talc pellets were dry-blended with foaming agent and mixed during loading into the molding machine.
• Part B a mixture of low-density polyethylene (LDPE), talc, and
• Hydrocerol® BIH 70 was formed and fed into a Van Dorn 300 injection molding machine to provide a polymer shot inside the barrel. After the shot accumulated in the front of the screw, the screw was translated backwards away from tire injection nozzle without rotation in accordance with the MFIM method to create a space between the screw and the nozzle, the space having a decompression volume. Then, the mixture foamed into the space prior to injection into the mold.
• TABLES 4-7 below show the polymer, mold, machine, and processing settings used in Example 2.
• FIG. 3B show the resulting cross sections of Part A and Part B respectively.
• Part A had a thick outer region extending nearly 0.8 inches (20.3 mm) from the surface, indicating that more than 50% of the molded part was completely solid.
• the density of Part A was 0.84 g/cc.
• FIG. 3B shows a cross section of Part B molded according to the MFIM process using the settings shown in TABLE 4 and TABLE 5.
• Part B had a foam structure that includes a distribution of cell sizes and shapes. A solid, unfoamed outer region is nearly absent from Part B. The density of Part B was 0.35 g/cc.
• a sphere cavity mold was used to form a further two parts, Part C and Part D, by foam injection molding. The same mixture composition of LDPE, talc, Hydrocerol® BIH 70 was used to form Parts C and D. Part C was made by the MFIM process, Part D by the standard foam molding process.
• FIG. 4 A is a photographic image of a cross section of Part C made by the MFIM process (471 g, required cooling time 160 seconds).
• FIG. 4B is a photographic image of the cross section of Part D molded using standard foaming process targets (1360 g, required cooling time 800 seconds).
• Part C made according to the MFIM process showed cells throughout the part, whereas Part D made according to the standard foam molding process showed a region adjacent to the outer surface of the part that was free or substantially free of cells (“solid”). Part C was less dense than Part D.
• Example 3 block parts w r ere molded using the MFIM process at various decompression volumes (Trial A) and various decompression volumes and decompression times (Trial B).
• TABLES 8-10 show' the material composition, mold geometry information, and processing settings used for Trials A and B.
• Trial A [00244] In Trial A, all variables were held constant except the volume ratio of polymer to decompression volume (empty space) in the barrel prior to injection. The settings for each sample run of Trial A are shown in TABLE 10:
• Trial B five moldings under the same conditions as Trial A were conducted three times; once with a decompression time 20 seconds (same as Trial A), once with a decompression time of 70 seconds, and once a decompression time of 120 seconds. Hie 15 resultant foam-molded parts were weighed and the density calculated using the volume of the mold cavity. The part density was plotted as a function of decompression volume for each of the three decompression times. The plots are shown in FIG. 5. As seen in FIG. 5, part density varied as a function of decompression volume. Further, as shown in FIG. 5, the greater the decompression time, the denser the part.
• Example 4 two series of trials were run using the MFIM process, Series I and Series II.
• Series I a constant injection speed was used but mold close height was varied.
• Series II mold close height was increased with increasing injection speed.
• Series 11 all conditions were kept constant except injection speed (cc/sec) and mold close height.
• LDPE/talc pellets were dry blended with the foaming agent and mixed dining loading into the molding machine.
• TABLES 12-13 below show the material composition of the injected blend and the base mold configuration used for the trials.
• a strain gauge (Kistler Surface Strain Sensor Type 9232A. available from Kistler Holding AG. Winterthur. Switzerland) was mounted just above or inside tire molding cavity.
• the strain sensor contained two piezoelectric sensors that measured the strain of the aluminum cavity as a function of time during the molding cycle. The strain measurement was used as an indirect measure of the force acting on the surface of the mold cavity resulting from the injection of molten foam and any subsequent additional foaming that occurred within the mold cavity.
• the cavity strain measurements are shown in FIG. 6 for Trial A, 1.02 mm gap height (line A); Trial B, 0.76 mm mold close height (line B); and Trial C, 0.51 mm mold close height (line C).
• the strain (unit extension per unit length) is plotted versus time in seconds. The strain curves indicate that the pressure was higher in Trial C than in Trial B and Trial B was higher than in Trial A.
• FIG. 7 includes photographic images showing a side view', a top view, an oblique view, and a bottom view of Parts A, B, and C.
• Parts A and B showed evidence of collapse, as the parts did not sufficiently match the mold cavity shape.
• Part A showed more collapse than Part B.
• Part C was more folly formed than either of Parts A and B in that the edges of Part C were better defined, and Part C conformed better to the mold cavity shape, and the interior of the part appeared more homogenous.
• Parts A’, B’ C’, and D’ showed no evidence of collapse, had well defined edges and surfaces, and appeared fairly uniform. Accordingly, parts were made using the MFIM process using drastically different injection rates by controlling the pressure within the cavity during injection, e.g. by varying mold close height.
• Example 5 the same LDPE composite material as Examples 1-3 was used in a non-standard two cavity mold with molding parameters as shown in TABLES 16-18.
• Example 5 produced the parts 51 shown in FIG. 9. During injection the molten foam melt entered through the sprue 52 and split off into two separate channels to fill the parts 51 substantially simultaneously. Accordingly, the MFIM process could be used to form parts by splitting the melt into multiple pathways in the mold.
• a first part was molded using a formulation of 15 wt.% talc / 85 wt.% polycarbonate composite was blended with 3 wt.% Hydrocerol® XH-901 prior to loading into the injection molding machine.
• the first part was formed using the MFIM process. Process details are provided in TABLES 19 and 20.
• the part was made using a 4x2x2 block mold (5.08 x 10.16 x 10.16 cm) with a mold cavity volume of 524.4 cc and a sprue volume of 17.4 cc. The sprue was cut from the part, and the part was then subject to X- ray tomography to quantify the cellular structure formed within the 5.08 x 10.16 x 10.16 cm geometry.
• the instrument measured the attenuation of the X-ray radiation due to the component geometry and the density of the material used.
• the column data were calculated using the Feldkamp reconstruction algorithm, a standard technique for tire industry.
• the instrument had a flat panel detector of 1536 x 1920 pixels for an ultimate resolution of 3.5 pm under the conditions of this measurement.
• FIG. 10 An isometric image of a foil Zeiss 3D Tomography scan of the first part is shown in FIG. 10, with the solid polymer fraction shown as transparent, the cells shaded for visualization, and the cutting plane A-A for single cross-section indicated.
• FIG. 11 is a single-plane cross section A-A selected from the X-ray data with a threshold analysis applied to allow for discrete cell identification and subsequent quantitative analysis.
• the circularity of the cross-sections of the cells was obtained.
• the circularity of these cross sections was used as a measure of the sphericity of the cells. Accordingly, circularity and sphericity are used interchangeably in the Examples.
• Quantitative analysis shown in FIG. 12 revealed a cell distribution of both counts and average size as a function of the circularity of each cell. A circularity value of zero represents a completely non-spherical cell, and a value of 1 represents a perfectly spherical cell.
• the data showed a distribution of cell sizes and shapes. With the exception of the most deformed cells (indicated by 0.1-0.2 on the circularity scale), there was an inverse relationship between the average cell size and the number of cells of a given circularity. Further, there is an inverse relationship between the average cell size and the number of cells.
• LDPE low-density' polyethylene
• FIG. 13 is an x-ray tomographic image of a cross section of the sphere. As seen in FIG. 13, the outer region contained a plethora of smaller cell sizes with larger cells in the central region.
• FIG. 14 shows a plot of average cell size and average cell count versus average cell circularity and reveals an inverse relationship between the average cell size and the circularity and an inverse relationship between the average cell size and the number of cells.
• An MFIM process was used to mold an LDPE composite sphere (92 wt. % polymer, 5 wt. % talc, and 3 wt. % Hydrocerol® BIH 70) with a diameter of three inches (7.62 cm) and the resulting foam cell structure detailed in FIGs 15-18. Molding conditions are provided in TABLE 23. The part was molded on an Engel Victory' 340 Ton injection molding press in a custom designed, water cooled aluminum mold. The volume of the mold cavity was 15.38 in 3 (252 cc), the shot size was 5 in 3 (82 cc), and the decompression volume in the barrel was 5 in 3 (82 cc). The decompression time was 77 seconds. The molded part weight was 80.31 g, yielding a final part density of 0.32 g/cc.
• the part was aged in ambient conditions for 24 hours, then scored and submerged in liquid nitrogen for two minutes. After removal from the liquid nitrogen, the sphere was fractured along the scored surface line and the fracture surface was imaged using an environmental scanning electron microscope (ESEM) (FEI Quanta FEG 650). The images shown in FIGs 15-18 are micrographs at various magnifications taken of the fracture surface of the sphere part using a large field detector, 5.0 kV and 40 Pa of pressure.
• ESEM environmental scanning electron microscope
• the white box in FIG. 15 indicates the area detailed in FIG. 16.
• the white box in FIG. 16 indicates the area detailed in FIG. 17.
• the cells to the left of the image are larger and relatively spherical, whereas those cells to the right side of the photograph appear progressively flattened as they approach the surface of the sphere.
• FIG. 18 details the area indicated by the white box in FIG. 17. As seen in FIG. 18, there is a gradual transition from spherical to “flattened” or compressed cells moving towards the surface of the part.
• the study was designed to investigate the influence of foaming agent concentration, talc content, and process conditions on selected properties of injection molded foam parts.
• a standard ISO tensile bar mold having cavity dimensions of 4.1 mm in thickness, 10 mm width in the gauge length, and 170 mm in length was used. No special venting was developed for the ISO bar mold.
• a second study was carried out using process variables specific to MFIM, specifically decompression volume and decompression time, while pressure and holding time (important variables in the published study) were set to a constant value of zero kN and zero seconds respectively.
• the designed study required 16 combinations of processing conditions/polymer formulation (16 runs) for each of the standard molding and MFIM molding studies. Multiple replicates were conducted of each run, producing replicate parts for each run. TABLE 25 outlines the variation between runs in both the standard and MFIM designed runs. The runs were conducted in a random order to avoid bias. The L/T ratio for the ISO tensile bar is 40.5.
• FIG. 21 shows a representative cross section and a series of stress/strain plots for the five parts tested from MFIM Run 9.
• FIG. 22 shows a representative cross section and a series of stress/strain plots for the five parts tested from standard foam process Run 10.
• FIG. 23 X-ray tomography scans (completed under conditions described in Example 5) were completed for a randomly selected replicate part from Run 15 of the standard foam molding process (shown in FIG. 23) and for a randomly selected replicate part produced during Run 9 of the MFIM process (shown in FIG. 24). Both FIG. 23 and FIG. 24 show a “top” view, taken at 50% depth and a “side” view, also taken at 50% depth.
• the ISO bar produced via the MFIM process as shown in FIG. 24 includes a high population of elongated cells and cells are found in the region adjacent to the surface of the part.
• tensile bars of LDPE were molded using the MFIM process on an Engel Victory' 340 Ton injection molding machine.
• the mold included an aluminum material modified tensile bar cavity having dimensions of 24 cm in length, a thickness of 2.54 cm, and a variable width with gauge length of 6 cm and a gauge width of 2.54 cm tapering to flanges of 3.5 cm in width.
• the large tensile bar was fed from a cold sprue and runner system through a gate 1.0 cm in diameter.
• the material formulations consisted of LDPE with or without talc, always containing 2 wt % foaming agent Clariant Hydrocerol® BIH 70.
• the melt temperature was set to the profile detailed in TABLE 26, and residence time in the barrel was 13 minutes before building a shot for injection. After building the shot, the screw was retracted to give a decompression volume of either 4.0 cubic inches (66 cc) or 6.0 cubic inches (98 cc) and the LDPE foaming agent mixture was allowed to foam for either 15 or 45 seconds into the empty barrel space prior to injection. The study was completed for both unfilled LDPE and 15% talc filled LDPE. Detailed process conditions are shown in TABLE 26.
• FIG. 25 shows an X-ray scan of one of the parts from this study, showing the overall shape of each part.
• FIG. 26 depicts a cross section of each test bar molded in the study, cut from the middle of the gauge length, with the variable parameters indicated.
• the sample set includes two primary groups: samples made with talc and samples made without talc.
• the sample set on the left depicts those parts made without talc. These parts display a smaller cell structure in the core of the part, and the integrity of the developed cell structure is largely unaffected by the changes in decompression ratio and decompression time, indicating the decompression ratios and times were all within an acceptable range.
• the sample set on the right depicts those bars containing 15 wt% talc. Some smearing on the part surfaces resulted from knife damage on the low-modulus LDPE and is not representative of part quality. The cell structure in the talc parts was consistently larger, and the circularity of the cells was slightly lower than the talc-free equivalents. [00292] An X-ray tomography image was taken of a cross section from the major surface about 50% into the MFIM part made with 15% talc, 6 in 3 (98 cc) decompression volume, and 15 seconds decompression time. The image is shown in FIG. 27.
• a tensile bar part was made using a standard foam molding process from LDPE loaded with 15 wt% talc, and 2 wt% Hydrocerol® BIH 70 using processing parameters as described for Example 9, but without the decompression step of the MFIM process.
• This standard foam molding part was compared with the MFIM part made with 15% talc, 6 in 3 (98 cc) decompression volume, and 15 seconds decompression time from Example 9.
• X-ray tomography images were taken of a central portion of each of the parts (MFIM molding and standard foam molding) at a variety of depths from a major surface. Cross section images were also recorded. The images are shown in FIG. 28.
• cell count was higher in the MFIM molded part at all depths.
• the part molded using the standard foam molding process appears to have no or substantially no cells in the region or “skin” adjacent to the surface, e.g. in about the first 2.5 mm of depth from the major surface, whereas cells are present in the part molded using the MFIM process within the region between about 2.5 mm below the surface and the surface.
• cell size was generally larger for the standard foam molded tensile bar part, but fell off rapidly to zero in the regions proximal the outer surfaces (e.g. within 2.5 mm of the surface). In contrast, cell size was more uniform through the depth of the MFIM-molded part, and cells continued right to the surface. [00298] The same trends are seen by visual examination of the cross sections shown in FIG. 28. Within 2.5 mm of any outer surface, the standard foam molded part appears to lack cells, whereas cells are visible up to the outer surface in the MF1M part.
• a large sample of recovered ocean plastic was analyzed using differential scanning calorimetry and was estimated to consist of approximately 85 wt% of HDPE, with the balance comprising polypropylene and contaminants.
• the variant process termed herein “reverse MFIM” process was as follows:
• a mixture was prepared by blending a polymer (which may be in the form of pellets, powder, beads, granules, and the like) with a chemical foaming agent, and any other additives such as a filler.
• the mixture was introduced to the injection unit, and the rotating injection unit screw moved the material forward in the injection molding machine barrel, thus forming a heated fluid material in accordance with normal injection molding processes.
• B) The screw was moved backwards towards the hopper, creating an intentional space between the screw and the nozzle within the barrel.
• a set volume of the material was dosed to the front of the barrel of the injection unit by rotation of the screw, thus moving the set volume from the feed zone to the front of the screw and into the intentional space created in step B.
• the screw was rotated to move melted material to the space in the barrel between the screw and the nozzle, thereby providing the set volume.
• the set volume occupied only part of the intentional space, thereby providing volume for the shot to foam and expand, the decompression volume.
• the material sat in the barrel between the screw and the nozzle for a period of time, termed herein the “decompression time”. During the decompression time, the material expanded due to foaming to fill or partially fill the space created in step (B).
• E) The molten foam was injected into the mold cavity by forward translation of the screw and/or rotation of the screw.
• Sample 10 and Sample 20 were both molded of virgin LDPE containing 2% Hydrocerol® BIH 70, 2% talc, and 1% yellow colorant. Molding was carried out on the Engel Duo 550 Ton injection molding machine (available from Engel Machinery Inc. of York, PA, USA). The mold was a spherical cavity within an aluminum mold fed by a cold runner and sprue.
• Two further sphere parts, Parts 22 and 24, were prepared under the same conditions and with the same polymer/talc/colorant/foaming agent mix as Sample 20.
• the average stress versus the average strain (reverse MFIM method) was plotted and is also shown in FIG. 38. as seen in FIG. 38, the compression moduli of the parts made by the MFIM process (average of Parts 6 and 7) and the parts made by the reverse MFIM process (average of Parts 22 and 24) are similar.
• Parts were fabricated using MFIM methods as described herein, of various shapes and materials as shown in TABLE 30.
• the parts were cross sectioned. In all cases, a region proximal the surfaces included cells of lower size, but moving away from a surface, cell size increased. The region of reduced cell size closer to the surfaces transitioned to a larger cell size further from the surface. While the transition was gradual and so there was no a distinct layer of smaller size and a distinct layer of larger size, using microscopy the relative areas of the region of smaller or “compressed” cells and the region of larger cells was estimated by eye and confirmed by tight microscopy, and is shown in TABLE 30. While the numbers are only estimates, examination of the images showed that the depth of the region and the percent area that was occupied by “compressed” cells varied widely, perhaps depending on part shape, material, and/or run conditions.
• a first part was molded using a formulation of 98 wt.% metallocene polyethylene was blended with 2 wt.% Hydrocerol® BIH 70 prior to loading into the injection molding machine.
• the first part was formed using the MFIM process. Process details are provided in TABLE 31 and TABLE 32.
• the part was made using a 2”x4”x4” block mold (5.08 x 10.16 x 10.16 cm) with a mold cavity volume of 524.4 cc and a sprue volume of 17.4 cc. The sprue was cut from the part, and the part was then subject to compression load testing to quantify the compressive strength properties of the cellular structure formed within the 2”x4”x4” geometry.
• Compression testing was carried out on an Instron Universal Testing System (available from Instron USA, Norwood, Massachusetts, USA). Each molded foam block was placed between the testing platens and stabilized within an environmental chamber at 30 °C for five minutes prior to testing. The instrument was equipped with a 250 kN load cell. The compression test rate was 5 mm/min.
• Part 87 was molded using the MFIM process with 10 seconds of calculated decompression time and a decompression volume of 65.55 cc.
• Part 111 was molded under the same conditions, but while a period of 10 seconds for decompression was allowed, as with Part 87, the screw was not translated backwards to allow a decompression volume. Accordingly, the decompression volume was 0 cc.
• Both Part 87 and Part 111 were photographed.
• FIG. 42 is a photographic image of Part 111 molded using no decompression step. As seen in the image, the process without the decompression step did not yield a part that filled the mold cavity, and the part did not match the shape of the cylindrical cavity of the mold.
• FIG. 43 is a photographic image of Part 87 molded using a decompression volume of 69.55 cc. As seen in the image, the molding process using a decompression volume of 69.55 cc yielded a part that entirely or substantially filled the cylindrical mold cavity, and the part matched or substantially matched the shape of the cylindrical cavity of the mold.
• the injection pressure (or specific injection pressure) was calculated by multiplying the measured hydraulic pressure of the ram by the machine intensification ratio, which for the Engle Victory 160 Ton molding machine is 7.222.
• the intensification ratio is a geometric factor to calculate the pressure amplification due to geometric differences between the hydraulic ram and the tip of the injection molding screw at the molten polymer interface.
• the injection pressure was plotted against barrel volume as displayed in FIG. 44 for the molding processes of both Parts 111 and 87.
• Referring to the plot for Part 111 in FIG. 44 as expected an immediate pressure increase was observed as the barrel volume between the nozzle and the screw (i.e. in front of the screw) was decreased to less than the shot volume of about 53 cc by translation of the screw towards the nozzle.
• a final injection pressure of approximately 65 MPa at the nozzle was achieved with approximately 20 cc of molten polymer mixture remaining in the barrel.
• the onset of rapid pressure rise (at a barrel volume of about 73 cc) for Part 87 was at a greater volume than that of onset of rapid pressure rise for Part 111 (at about 53 cc).
• the difference between these "onset volumes” suggests a higher volume of shot for Part 87 before injection into the mold due to expansion of the shot by foaming thereof into the decompression volume within the barrel. Accordingly, the extra volume is labeled "Barrel Foaming" to reflect this possibility.
• Part 16A and Part 16B Two spherical foam molded parts, Part 16A and Part 16B, were separately made, each ftom a mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight) using the MFIM process. Each of Parts 16A and 16B was cut through the middle (widest part) into two pieces to expose a cross section of the part, and a photograph taken of the cross section.
• Part 16C and 16D were made from a mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight) using the MFIM process. However, Parts 16C and 16D were made using a reduced clamp force when compared with the process used to make Parts 16A and 16B. Each of Parts 16C and 16D was cut through the middle (widest part) into two pieces to expose a cross section of the part, and a photograph taken of the cross section.
• Part 16E was made from a mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight) using tire MFIM process. Part 16E differed from Parts 16A and 16B in using a different decompression ratio (the ratio between the shot volume and the decompression volume). Part 16E was cut through the middle (widest part) into two pieces to expose a cross section of the part, and a photograph taken of the cross section.
• RAPID Granulator Open-Hearted 400-60 (available from RAPID Granulator AB of Bredaryd, Sweden), which produced a regrind in the form of flakes.
• the regrind from each of Parts 16A, 16B, 16C, 16D, and 16E was then used as feedstock for injection molding to make a new spherical foamed part, 16AR, 16BR, 16CR, 16DR, and 16ER respectively.
• Each of Parts 16AR, 16BR, 16CR, 16DR, and 16ER was cut through the middle (widest part) into two pieces to expose a cross section of the part, and a photograph taken of the cross section.
• Screw rotate delay time for all foam molding processes was 40 seconds.
• Virgin refers to fresh mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight).
• FIG. 45 is the photograph of a cross section of Part 16A, FIG. 46 of Part 16AR, FIG. 47 of Part 16B, FIG. 48 of Part 16BR, FIG. 49 of a cross section of Part 16C, FIG. 50 of Part 16CR, FIG. 51 of Part 16D, FIG. 52 of Part 16DR, FIG. 53 of Part 16E, and FIG. 54 is the photograph of a cross section of Part 16ER.
• FIGS. 45-54 collectively show that each of MFIM-molded Parts 16A, 16B, 16C, 16D, and 16E was successfully recycled into a further MFIM-molded part; Parts 16AR, 16BR, 16CR, 16DR, and 16ER respectively.
• thermoplastic resins including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), high-impact polystyrene (HIPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA), thermoplastic polyurethane (TPU), and thermoplastic olefin (TPO).
• LDPE low-density polyethylene
• HDPE high-density polyethylene
• PP polypropylene
• HIPS high-impact polystyrene
• PET polyethylene terephthalate
• PBT polybutylene terephthalate
• PA thermoplastic polyurethane
• TPO thermoplastic olefin
• FIG. 55 is a photographic image of the part molded using no decompression. As seen in the image, the process without decompression did not yield a part that filled the mold cavity, and the part did not match the shape of the spherical cavity of the mold.
• FIG. 56 is a photographic image of the second part, molded using a decompression time of 0.5 seconds after applying a depressurization rate of 0.0059 GPa/sec. As seen in the image, the molding process using 0.5 seconds of decompression time yielded a part that entirely or substantially filled the spherical mold cavity and the part matched or substantially matched the shape of the spherical cavity of the mold.
• FIG. 57 is a photographic image of the third part, molded using a decompression time of 7 seconds after applying a depressurization rate of 0.0059 GPa/sec. As seen in the image, the molding process using 7 seconds of decompression time yielded a part that entirely or substantially filled the spherical mold cavity and the part matched or substantially matched the shape of the spherical cavity of the mold.
• FIG 68 is a photographic image of the fourth part, molded using a decompression time of 10 seconds after applying a depressurization rate of 0.0009 GPa/sec. As seen in the image, the molding process using a low depressurization rate of 0.0009 GPa/sec did not yield a part that substantially filled the mold cavity, though the part substantially matched the spherical shape of the mold.
• FIG 69 is a photographic image of the fifth part, molded using a depressurization rate of 0.0629 GPa/sec. As seen in the image, the molding process using the stated conditions yielded a part that substantially filled the spherical mold cavity and the part matched or substantially matched the shape of the spherical cavity of the mold.
• Decompression rate is determined by the speed of lateral movement of the screw away from the collection area of the injection molding machine, which may be set by the operator.
• a second part was molded using 1000 psi (6895 kPa) of back pressure and a decompression rate of 16 cubic inches per second (292 cc/sec).
• An aluminum mold having a cold sprue and runner system feeding a 6-inch diameter sphere cavity was employed for both parts.
• the melt delivery system for each part was the same, as were most of the processing conditions.
• the process settings used to produce each part are detailed in TABLE 36.
• FIG. 58 is a photographic image of
• FIG. 59 is a photographic image of Part 2, molded using a back pressure of 6895 kPa and a decompression rate of 0.001 GPa/s.
• the molding process utilizing a rapid decompression rate of 292 cc/sec, coupled with backpressure of 1000 psi (6895 kPa) yielded a part that entirely or substantially filled the spherical mold cavity and the part matched or substantially matched the shape of the spherical cavity of the mold.
• a mixture of 98.5 parts by weight of post-industrial polypropylene in the form of granules and 1.5 parts by weight of foaming agent (Hydrocerol® BIH 70, available from Clariant AG of Muttenz, Switzerland) was foam molded using the MFIM process with a 2.25 x 3.875 x 8 inch (5.7 x 9.8 x 20.3 cm) mold cavity to produce a 2.25 x 3.875 x 8 inch (5.7 x 9.8 x 20.3 cm) brick.
• Processes 19- ID, 19-3D, and 19-5D were performed in the same manner using many of the same processing conditions, except for the number of decompression steps. Further, the cooling time of the shot before decompression was adjusted to maintain the same shot residence time in the barrel in all three runs: multiple decompression steps would have led to a longer cycle residence time of the shot in the barrel for a larger number of decompression steps. In addition, the shot volume for each run was adjusted to produce three bricks of as similar weight to each other as possible.
• Process 19-1D was an MFIM process with one decompression step, in which after the shot was introduced to the front of the barrel (between the nozzle and the screw) and left for a cooling adjustment period, the screw was translated backward (away from the nozzle) to provide a decompression volume for ten seconds (decompression time). Immediately after the decompression step, the screw was translated forwards (toward the nozzle) to inject the shot into the mold.
• Process 19-3D was performed in a similar manner, except that the screw was translated backward from a pre-translation position to provide the decompression volume for ten seconds (decompression time), and then translated forward to the pre-translation position; then backward for a second time to again provide the decompression volume for ten seconds decompression time, then translated forward to the pre-translation position; and then backward for a third time and left for a decompression time of ten seconds before injection. Accordingly, run 19-3D had three decompression steps instead of the single decompression step of run 19- ID.
• Process 19-5D was performed in a similar manner as run 19-3D, except that five ten-second decompression steps were performed.
• a brick from each process type was cut into two halves of 1 x 4 x 8 inch (2.5 x 10.2 x 20.3 cm), and the 4 inch x 8 inch cross section of each was photographed. The photographs are displayed in FIG. 60. Parts molded with five decompression steps showed larger voids near the area where the melt enters the cavity.
• FIG. 62 Plots of compressive strength versus compressive strain for bricks from each process type are shown in FIG. 62.
• Bricks made by all three processes had a similar maximum compressive strength of about 5.2 MPa. It was noted that the brick tested for five the 19-5D process has a large void near the gate.
• the objective of the present example was to make parts having a higher void fraction than those previously made using the MFIM process.
• Two parts were made; a foam-molded sphere of 8.25 cm diameter made from a SURLYNTM ionomer (available from the Dow Chemical Company, of Midland, Michigan, USA) incorporating 4% by weight Hydrocerol® BIH 70 foaming agent (available from Clariant AG of Muttenz, Switzerland), and a foam-molded sphere of approximately six-inch diameter (approximately 15.2 cm) of a blend of 90 parts by weight low-density polyethylene and 10 parts by weight of high-density polyethylene incorporating 3% by weight of the BIH 70 foaming agent.
• Processing variables were adjusted to achieve high void fractions. Processing parameters used to mold the SURLYN sphere into a 7.62 cm diameter spherical cavity by an MFIM process are displayed in TABLE 38 and those for the 15.24 cm diameter polyethylene sphere in TABLE 39. It is noted that the SURLYN sphere solidified and was removed from the mold, and further expansion during cooling resulted in a sphere larger than the cavity used to mold the sphere.
• FIG. 65 is a diagrammatic representation of FIG. 65.
• FIG. 66 is a diagrammatic representation of FIG. 66.
• the images confirmed a cell structure across the cross section including within 500 microns of the surface of the sphere.
• Equation 1 The equation for the density of a foamed part is described in Equation 1: where M is the mass of the foamed part and V is the volume of the foamed part.
• Equation 2 The void fraction equation is described in Equation 2: where P polymer is the density of the material.
• An objective of the present example was to demonstrate that an article could be made by an MFIM process in which the mold was only partially filled.
• Two flowerpots were molded from low-density polyethylene (comprising 1.5% by weight Hydrocerol® BIH 70 foaming agent, available from Clariant AG of Muttenz, Switzerland) using an MFIM process by foam injection into a mold having a mold cavity of volume 10860.20 cc.
• Run SF produced a flowerpot by filling or substantially filling the mold cavity.
• a second run, Run PF was performed with a lower shot volume and lower decompression volume in order to only partially fill the mold cavity and produce a partially filled part.
• the average actual block dimensions for the 60 blocks were 20.005 ⁇ 0.114 cm by 19.964 ⁇ 0.659 cm by 40.066 ⁇ 0.061 cm.
• Block 45 Three of the 60 blocks were taken, Block 45, Block 27, and Block 60. Each block was cut into 16 sub-blocks, which were stacked and photographed to show the foam structure of the block in cross-section. A photograph of the sub-blocks from Block 45 is shown in FIG. 70, the sub-blocks from Block 27 in FIG. 71, and the sub-blocks from Block 60 in FIG. 72.
• FIG. 73 A photograph of a fort built from the MFIM foam blocks is shown in FIG. 73.
• Cinder blocks with three channels were also made from high-impact polystyrene.
• Post industrial regrind (P.I.R.) in the form of flakes was obtained from Engineered Plastics LLC of Erie, PA, USA.
• the P.I.R had a melt index of between 8 and 12, and was of mixed colors.
• the P.I.R. flakes were made from scrap laundry detergent lids and other scrap polypropylene items.
• plastic compositions were made having 0%, 25%, 50%, and 100% by weight of the pelletized P.I.R., 2% by weight of weight Hydrocerol® BIH 70 foaming agent, and the remainder being virgin polypropylene.
• Each of the four compositions was used to mold a brick on an Engel Duo 340 Ton injection molding machine (available from Engel Machinery Inc. of York, PA, USA) using a mold having a cuboid cavity of 5.715 cm by 9.842 cm by 20.32 cm.
• a total of 60 bricks was molded from the polypropylene made of 100% by weight P.I.R
• Part 119 was molded using an MFIM process with 1800 seconds of calculated decompression time and a decompression volume of 14.75 cc.
• Part 120 was molded using an MFIM process with 0 seconds of calculated decompression time. The screw was not translated backwards to allow a decompression volume. Accordingly, the decompression volume was 0 cc.
• Part 119 formed using the molding process having a decompression volume of 14.75 cc and a decompression time of 1800 seconds, was completely filled out and the shape of the part matched the shape of the mold cavity.
• Part 120 formed using the process with no decompression tim,e did not yield a part that filled the mold cavity. The part was sunken in around the molded flat portion of the cylinder shape, and the part did not match the shape of the cavity of the mold.

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