KR20240027062A - Polymer foam articles and methods of making polymer foams - Google Patents

Abstract

Molded polymer foam articles having novel foam structures are described. The polymer foam article includes a continuous polymer matrix defining a plurality of pneumatoceles therein that are present throughout the article. The surface region is further characterized as having compressed pneumatocytes. The novel foam structures include shapes and volumes such that spheres with a diameter of even 2 cm to 1000 cm fit into at least one location within the article without protruding from the surface of the article, and further have a polymer total volume of more than 1000 cm ³ This is also achieved when molding foam articles. Methods for making stabilized molten polymer foams and methods for making molded polymer foam articles using the stabilized molten polymer foams are also described.

Description

Polymer foam articles and methods of making polymer foams

Foamed polymer articles are widely used in industry due to their highly desirable properties of providing the high strength associated with solid polymer articles, while also providing a reduction in density and thus the amount of polymer used to mold articles of selected volumes. do. Additionally, the industry is taking advantage of the benefits provided by the reduction in the weight of foam articles compared to their solid counterparts, while still reaping the benefits of strength, toughness, impact resistance, etc. provided by the polymer itself.

Accordingly, the industry has developed several now common methods for incorporating gases into thermoplastic polymers to produce such foam articles. For forming foamed thermoplastic polymer articles using gases, commercial guidelines and industrial practice also provide for melt mixing the thermoplastic polymer with the gas or a source of gases, at a temperature above the melting temperature of the thermoplastic polymer, while melting the gas inside the apparatus. Use a melt mixing device operable to maintain pressure to limit expansion of the melt. Such methods and devices are designed to minimize the formation of pneumatoceles, or pockets of gas, that would otherwise be formed by expansion of gas in the molten thermoplastic polymer. Accordingly, while present in and disposed within a melt mixing device, the thermoplastic polymer may contain a source of gas or the gas itself dissolved or dispersed therein, while it may not contain pneumatocytes or may substantially contain pneumatocytes. do not include. A mixture of a molten thermoplastic polymer and a gas at or above a temperature that will form pneumatocytes at atmospheric pressure is a molten pneumatic mixture, which does not contain pneumatic cells or is substantially free of pneumatic cells. It can be referred to as. The temperature at which a gas, or pneumatogen, will form a pneumatocyte in a pneumatic mixture melted at atmospheric pressure may be referred to as the critical temperature. Melt mixing devices well known in the art are thus designed and adapted for producing and dispensing molten pneumatic mixtures. Such devices are also suitable for preparing molten pneumatic mixtures by adding initial, latent, or latent gases that are released at a characteristic temperature or formed by exothermic or endothermic chemical reactions at a characteristic temperature. The initial, latent, or latent gas critical temperature is the temperature at which the reaction occurs or the gas is released into the thermoplastic polymer. All such materials and methods are well understood, and melt mixing devices of various designs are widely commercially available for this purpose. A commonly used melt mixing device consists of a screw to receive a set amount, or "shot", of the molten pneumatic mixture that is moved during mixing by the action of a screw to push the molten pneumatic mixture towards a pressurization chamber. It is a single screw or twin screw extruder modified to have a pressure chamber at the end of the extruder.

Upon building a set quantity or shot in a pressurization chamber, the molten pneumatic mixture is dispensed from the melt mixing device and directed by fluidly connected tubes, pipes, etc. to the cavity of the mold to achieve the desired shape. Dispensing is generally performed to maximize the amount of foaming (pneumatocell formation) that occurs in the mold cavity by the release of pressure while the thermoplastic polymer is still molten. The expanded foam in the cavity is then cooled to form a foam article. Foam parts molded using this methodology are referred to in the art as injection molded foam parts. The technology is generally limited in scope to manufacturing parts with a thickness of about 2 cm or less.

Injection molding processes that use pneumatogen sources to induce foaming structures in molded parts are described in a recent peer-reviewed paper 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." It can be understood from [Cellular Polymers 2020, 39(1) 3-30]. In this literature, the process conditions typically used for the molding of standard injection molded ISO test bars of 4.1 mm thickness are systematically varied to vary the process settings and formulation parameters (concentration of pneumatogen source, filler content). , injection speed, injection time, holding time, and holding pressure) were created. The authors note that although manipulating the process and formulation results in some variation of the foam structure in the resulting foam parts, all variables are related to a very characteristic region near the surface of the injection molded foam article that is free or substantially free of pneumatocytes. It is taught that a part has been created with a “skin layer,” which is a term in the art to describe .

Inspection of the surface of an injection molded foam article, and an area extending about 500 microns below the surface in any direction, reveals solid thermoplastic regions - i.e., regions that are either free of pneumatocytes or contain pneumatocytes. There is practically no such thing. Foam parts resulting from injection molding according to conventional injection molding processes include skin layer features. Additionally, the skin layer of most such parts is significantly thicker than 500 μm and may be 1 mm, 2 mm, 3 mm, or even thicker depending on the method, device and materials used.

To manufacture large foam parts (such as pallets or trolley bodies, for example), such conventional methods are such that large mold cavities induce excessive pressure drops as the molten pneumatic mixture flows and expands during filling of the mould; This is insufficient, as pneumatocytes may form but may coalesce or leak from the viscous polymer flow during subsequent filling. Therefore, in some cases of “structural foam” molding, multiple nozzles are used simultaneously to rapidly fill large or thick mold cavities. In other cases, significant back pressure is applied within the mold cavity to prevent pneumocell formation during filling; The release of pressure after filling of the mold operates substantially to allow the formation of pneumatocytes within the mold cavity. Both approaches are commonly used in a single process.

However, the structural foam molding process does not solve the problem of effectively preventing industry from developing very large parts. As is well understood, areas near the surface of the molten mass will cool more rapidly than its interior, and a cooling gradient in temperature develops within the mass. The rate of cooling is slowest at the deepest points within the mass. In connection with a large mold cavity filled with a mass of molten polymer or pneumatic mixture, the internal region of the mass can be cooled very slowly, so that the viscous flow of the thermoplastic allows pneumatic cell coalescence, forming a large void. This destroys the intended continuous polymer matrix that forms polymer pockets and defines such foams. This effect can be exacerbated by shrinkage of the polymer's volume as it cools to a temperature below its melt transition. In the case of large foam parts, this effect can even lead to complete collapse of the foam structure inside the part.

The combined strength and density reductions associated with foam articles are not realized without a continuous polymer matrix throughout the part. Foam parts with large polymer-free zones or voids compromise the structural integrity of the part, making such parts unsuitable for their intended use. These serious technical problems have limited the industrial application of polymer foams to many other very useful and beneficial applications. Accordingly, there is a continuing need to provide improved methods for making foam articles, especially large or thick foam articles. There is a continuing need to obtain parts with an overall continuous foam structure. It is particularly desirable to obtain parts with a thickness of more than 2 cm and with a continuous foam structure throughout. There continues to be a need in industry to address such needs using conventional devices and materials.

Methods for making molten polymer foams are described herein. The method includes: adding a thermoplastic polymer and a pneumatogen source to an extruder; heating and mixing the thermoplastic polymer and the pneumatic source in an extruder under pressure to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the critical temperature of the pneumatic source; collecting a quantity of molten pneumatic mixture in a collection zone of the extruder; defining an expansion volume in the collection zone to cause the pressure to drop (depressurization) in the collection zone; allowing an expansion period to elapse after confinement; and dispensing the molten polymer foam from the collection zone. In an embodiment, the expansion volume is selected to provide 10% to 300% of the total expected molten foam volume in the collection zone, and further, the depressurization rate (i.e., the rate defining the pressure drop) is at least 0.01 GPa/s. , in an embodiment, at least 0.1 GPa/s; and in some embodiments at least 1.0 GPa/s, for example up to 5.0 GPa/s. Depressurization rates greater than 0.01 GPa/s are referred to herein as “rapid depressurization.” In some such embodiments, rapid depressurization is coupled with high back pressure, for example in the collection zone, or in one or more additional zones of the device used to effect depressurization, for example in the injection molding machine for initiating depressurization. The amount of pressure required in the barrel section, and further "high back pressure" refers to a back pressure greater than 500 kPa, such as a back pressure of 500 kPa, and a back pressure as high as 25 MPa, limited by the injection molding machine utilized to perform the depressurization. do.

By using the methods described herein, further utilizing rapid depressurization of the molten pneumatic mixture in the collection zone, in embodiments further utilizing high back pressure to initiate rapid depressurization, theoretically between 20 cm and 1000 cm Characterized by having a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout the article, having a shape and volume sufficient to receive a sphere of diameter at at least one location therein, and having a total article volume of 1000 cm. Obtaining a stabilized molten polymer foam capable of forming polymer foam articles measuring at least ³ , at least 2000 cm ³ , at least 3000 cm ³ , at least 4000 cm ³ , or at least 5000 cm ³ , or between 2000 cm ³ and 5000 cm ³ or more. do. In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

The inventors also utilize rapid depressurization of the collection zone, and in embodiments further utilize high back pressure, so that an expansion period of 0 to 5 seconds is used to form a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout the article. It has been further discovered that a polymer foam article can be obtained characterized by having. The inventors have further discovered that expansion periods of 600 to 2000 seconds or even longer can be achieved by utilizing metal depressurization and, in embodiments, utilizing additional high back pressure. The molten pneumatic mixture is undisturbed or substantially undisturbed during the expansion period.

In some embodiments, 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 zone.

In an embodiment, the distribution is to a molded element; In some embodiments, the forming element is a mold. In an embodiment, there is a fluid connection between the collection area of the extruder and the mold. In an embodiment, the dispensing is an unimpeded flow of molten polymer foam. In some embodiments, the dispensing is 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.

In an embodiment, the method further comprises cooling the dispensed molten polymer foam to a temperature below the melt transition of the thermoplastic polymer. In an embodiment, one or more additional substances are added to the extruder, wherein the one or more substances are selected from colorants, stabilizers, brighteners, nucleating agents, fibers, particulates, and fillers. In an embodiment, the pneumatogen source is pneumatogen and the addition is a pressure addition. In another embodiment, the pneumatogen source comprises a bicarbonate, polycarboxylic acid or salt or ester thereof, or mixtures thereof.

Also disclosed herein are polymer foam articles made using the methods, materials, and devices described herein. In an embodiment, the polymer foam article has a foam structure throughout characterized by a continuous polymer matrix defining a plurality of pneumatocytes therein. In an embodiment, the surface area of the polymer foam article comprises compressed pneumatocytes. In an embodiment, the surface area is an area extending 500 microns from the surface of the article.

Also disclosed herein is a thermoplastic polymer foam article, wherein the article has an overall foam structure that is a continuous polymer matrix defining a plurality of pneumatocytes therein, the surface area of the article comprising compressed pneumatocytes. Includes. In some embodiments, the surface area is an area of the article extending 500 microns from the surface of the article. In some embodiments, the article comprises pneumatocytes compressed to greater than 500 microns from its surface.

In an embodiment, the polymeric foam article comprises a shape and volume such that spheres at least 2 cm in diameter fit into at least one location within the article without protruding from the surface of the polymeric foam article. In some such embodiments, the polymeric foam article further comprises one or more locations where the 2 cm diameter spheres protrude from the surface of the polymeric foam article rather than being contained within it. In embodiments, the polymer foam article has a volume greater than 1000 cm ³ , 1000 cm ³ to 5000 cm ³ , 2000 cm ³ to 5000 cm ³ or even greater than 5000 cm ³ . In an embodiment, the polymer foam article has a shape and volume wherein at least one (theoretical) sphere with a diameter of 2 cm to 1000 cm, such as 20 cm to 1000 cm, fits into at least one location within the article without protruding from the surface of the polymer foam article. has In an embodiment, the polymeric foam article comprises a volume greater than 2000 cm ³ and a shape and volume such that spheres at least 2 cm in diameter fit into at least one location within the article without protruding from the surface of the polymeric foam article. In an embodiment, the polymeric foam article comprises a volume of 2000 cm ³ to 5000 cm ³ and includes a shape and volume such that spheres with a diameter of at least 20 cm fit into at least one location within the article without protruding from the surface of the polymeric foam article. do. In an embodiment, the polymeric foam article further comprises a volume greater than 5000 cm ³ and has a shape and volume wherein spheres of 20 cm to 1000 cm in diameter fit into at least one location within the article without protruding from the surface of the polymeric foam article. Includes. In an embodiment, the polymeric foam article comprises a sphere having a diameter between 20 cm and 1000 cm shaped to fit into at least one location within the article without protruding from the surface of the polymeric foam article; In another embodiment, the polymer foam article has a shape in which two spheres, ranging from 20 cm to 1000 cm in diameter, fit within the article without protruding from the surface of the polymer foam article. In yet another embodiment, the polymer foam article has a shape such that three or more spheres ranging from 20 cm to 1000 cm in diameter fit within the article without protruding from the surface of the polymer foam article.

In an embodiment, the materials used to prepare the polymer foam article are not particularly limited and include polyolefins, polyamides, polyimides, polyesters, polycarbonates, poly(lactic acid), acrylonitrile-butadiene-styrene copolymers, Polymers, polystyrene, polyurethane, polyvinyl chloride, copolymers of tetrafluoroethylene, polyethersulfone, polyacetal, polyaramid, polyphenylene oxide, polybutylene, polybutadiene, polyacrylates and methacrylates, ionomer polymers. , polyether-amide block copolymer, polyaryletherchitone, polysulfone, polyphenylene sulfide, polyamide-imide copolymer, poly(butylene succinate), cellulosics, polysaccharides, and these. and thermoplastic polymers selected from copolymers, alloys, mixtures, and blends. In some embodiments, the thermoplastic polymer is a mixed plastic waste stream. The continuous polymer matrix optionally further comprises one or more additional materials selected from colorants, stabilizers, brighteners, nucleating agents, fibers, particulates, and fillers.

The inventors have discovered that polymer foam articles molded using the above methods are 100% recyclable by subsequent melt molding processes. Polymer foam articles made according to the methods described herein can be recycled using the methods described herein. Accordingly, in an embodiment, a first polymer foam article according to any of the embodiments described herein and molded according to any of the methods described herein may also be used to mold a second polymer foam article according to the methods described herein. It is a source of thermoplastic polymers for In such embodiments, the first polymer foam article is a recycled material feedstock when used to make the second polymer foam article.

Other purposes and features will be partly apparent and partly pointed out below.

1A and 1B illustrate melt mixing equipment useful for carrying out the methods described herein.
Figure 2A is a photographic image of a part molded according to the standard foam molding process described in Example 1.
2B is a photographic image of a part molded according to the molten-foam injection molding (MFIM) process described in Example 1.
Figure 2C is a photographic image of a piece cut from a part manufactured according to the standard foam molding process described in Example 1.
2D is a photographic image of a piece cut from a part manufactured according to the MFIM process described in Example 1.
Figure 2E is a photographic image of a piece cut from a part manufactured according to the standard foam molding process described in Example 1.
2F is a photographic image of a piece cut from a part manufactured according to the MFIM process described in Example 1.
Figure 3A is a photographic image of a cross-section of Part A, as described in Example 2, manufactured according to a standard foam molding process and cut into two pieces to reveal the cross-section.
3B is a photographic image of a cross-section of Part B, as described in Example 2, manufactured according to the MFIM process and cut into two pieces to reveal the cross-section.
Figure 4A is a photographic image of a cross-section of Part C, as described in Example 2, manufactured according to the MFIM process and cut into two pieces to reveal the cross-section.
Figure 4B is a photographic image of a cross-section of Part D, as described in Example 2, manufactured according to a standard foam molding process and cut into two pieces to reveal the cross-section.
Figure 5 is a graph containing a plot of part density versus decompression volume for various decompression times for Test B as described in Example 3.
Figure 6 is a graph containing plots of strain versus time for parts made in Test A, Test B, and Test C as described in Example 4.
Figure 7 shows photographic images from various side views of Part A, Part B, and Part C as described in Example 4.
Figure 8 shows photographic images of the cross sections of Part A', Part B', Part C', and Part D' as described in Example 4.
Figure 9 is a drawing of two parts as described in Example 5.
Figure 10 is an isometric image of a tomography scan of a first part manufactured according to the MFIM process as described in Example 6.
Figure 11 is an image of the cross-sectional plane shown in Figure 10 as described in Example 6.
FIG. 12 is a graph including a plot of average cell size and cell count versus cell circularity for a first part manufactured as described in Example 6.
Figure 13 is a diagram of an X-ray tomography image of a cross section of a second (spherical) part as described in Example 6.
Figure 14 is a graph including a plot of average cell size and cell count versus cell circularity for a second (spherical) part manufactured as described in Example 6.
Figure 15 is a micrograph of the fracture surface of a fractured 3-inch diameter composite sphere prepared according to the MFIM process, as described in Example 7.
Figure 16 is a photomicrograph image of the fracture surface of fractured 3-inch diameter composite spheres prepared according to the MFIM process, as described in Example 7.
Figure 17 is a photomicrograph image of the fracture surface of fractured 3-inch diameter composite spheres prepared according to the MFIM process, as described in Example 7.
Figure 18 is a photomicrograph image of the fracture surface of fractured 3-inch diameter composite spheres prepared according to the MFIM process, as described in Example 7.
Figure 19 shows photomicrograph images of cross-sections of ISO bar parts made according to the standard foam molding process runs 10, 11, run 14, and run 15, as described in Example 8.
Figure 20 shows photomicrograph images of cross-sections of ISO bar parts made according to the MFIM process Runs 9, 10, Run 15, and Run 16, as described in Example 8.
Figure 21 shows a micrograph of a cross-section of an ISO bar part made according to the MFIM process of Run 9 and a stress-strain plot of a replica part made according to the MFIM process of Run 9, as described in Example 8.
Figure 22 shows a micrograph of a cross-section of an ISO bar part made according to the standard foam molding process of Run 10 and a stress-strain plot of a replica part made according to the standard foam molding process of Run 10, as described in Example 8. Includes.
Figure 23 includes two images from X-ray tomography of an ISO bar part manufactured according to the standard foam molding process in Run 15, as described in Example 8.
Figure 24 includes two images from X-ray tomography of an ISO bar part manufactured according to the MFIM process in Run 9, as described in Example 8.
Figure 25 is an image from an X-ray scan of a large tensile bar part manufactured according to the MFIM process, as described in Example 9.
Figure 26 includes cross-sections of eight large tensile bar parts manufactured according to the MFIM process, as described in Example 9.
Figure 27 is an X-ray tomography image of a large tensile bar made according to the MFIM process, as described in Example 9.
28 shows a series of Contains a series of images.
29 includes a plot of cell coefficient versus depth for a tensile bar part made according to the MFIM process and a plot of cell coefficient versus depth for a tensile bar part made according to a standard foam molding process, as described in Example 10. This is a graph that does.
30 is a plot of cell circularity versus depth for tensile bar parts made according to the MFIM process and a plot of cell circularity versus depth for tensile bar parts made according to the standard foam molding process, as described in Example 10. It is a graph containing .
31 includes a plot of cell size versus depth for a tensile bar part made according to the MFIM process and a plot of cell size versus depth for a tensile bar part made according to a standard foam molding process, as described in Example 10. This is a graph that does.
Figure 32 is a photograph of Sample 20 prepared according to the reverse MFIM process, as described in Example 12.
33 is a photograph of Sample 10 prepared according to the MFIM process, as described in Example 12.
Figure 34 is a photograph showing a cross-section of Sample 20 prepared according to the reverse MFIM process, as described in Example 12.
Figure 35 is a photograph showing a cross-section of Sample 10 prepared according to the MFIM process, as described in Example 12.
Figure 36 is a plot of cell count versus depth (distance from surface) for Sample 10 (MFIM) and Sample 20 (Inverse MFIM) as described in Example 12.
Figure 37 is a plot of cell size versus depth (distance from surface) for Sample 10 (MFIM) and Sample 20 (Inverse MFIM) as described in Example 12.
Figure 38 is a graph including a plot of average stress versus strain for sample 10 (MFIM) and a plot for sample 20 (inverse MFIM) from compressive modulus measurements, as described in Example 12.
Figure 39 is a graph including a plot of average stress versus strain for sample 10 (MFIM) and a plot for sample 20 (inverse MFIM) from bending modulus measurements, as described in Example 12.
Figure 40 is a graph of a plot of stress versus strain from compression modulus measurements made of three metallocene polyethylene (mPE) materials of different densities and made according to the MFIM process, as described in Example 14.
Figure 41 illustrates a mold configuration useful for performing the methods described herein.
Figure 42 is a photograph showing part 111, a part manufactured without the depressurization step, as described in Example 15.
Figure 43 is part 87, a part manufactured according to the MFIM process, as described in Example 15.
Figure 44 is a plot of injection pressure versus barrel volume for the molding process of part 111 and the molding process of part 87 as described in Example 15.
Figure 45 is a cross-sectional photograph of part 16A, as described in Example 16.
Figure 46 is a cross-sectional photograph of part 16AR, as described in Example 16.
Figure 47 is a cross-sectional photograph of part 16B, as described in Example 16.
Figure 48 is a cross-sectional photograph of part 16BR, as described in Example 16.
Figure 49 is a cross-sectional photograph of part 16C, as described in Example 16.
Figure 50 is a cross-sectional photograph of part 16CR, as described in Example 16.
Figure 51 is a cross-sectional photograph of part 16D, as described in Example 16.
Figure 52 is a cross-sectional photograph of component 16DR, as described in Example 16.
Figure 53 is a cross-sectional photograph of part 16E, as described in Example 16.
Figure 54 is a cross-sectional photograph of component 16ER, as described in Example 16.
Figure 55 is a photograph of Part 1 manufactured without reduced pressure, as described in Example 17.
Figure 56 is a cross-sectional photograph of Part 2, manufactured with a decompression time of 0.5 seconds, as described in Example 17.
Figure 57 is a cross-sectional photograph of Part 3, manufactured with a decompression time of 7 seconds, as described in Example 17.
Figure 58 is a cross-sectional photograph of Part 1 after cutting, as described in Example 18.
Figure 59 is a cross-sectional photograph of Part 2 after cutting, as described in Example 18.
Figure 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.
Figure 61 shows enlarged images of three brick parts made as described in Example 19 with 1 decompression step, 3 decompression steps, and 5 decompression steps.
Figure 62 is a plot of compressive strength versus compressive strain measured for three parts manufactured as described in Example 19 using one decompression step, three decompression steps, and five decompression steps.
Figure 63 is a graphical representation of the force at peak measured during stress-strain testing of three parts manufactured as described in Example 19 using one decompression step, three decompression steps, and five decompression steps.
Figure 64 is a graphical representation of the energy at peaks measured during stress-strain testing of three parts manufactured as described in Example 19 using one decompression step, three decompression steps, and five decompression steps.
Figure 65 shows a photograph of a cross-section of a spherical SURLYN(TM) part after cutting and an enlarged image of a near-spherical cross-section of the part, as described in Example 20.
Figure 66 shows a photograph of a cross-section of a spherical polyethylene part after cutting and a magnified image of a near-spherical cross-section of the part, as described in Example 20.
Figure 67 is a photograph of two parts manufactured as described in Example 21.
Figure 68 is a photographic image of a fourth part formed using a depressurization rate of 0.0009 GPa/sec followed by a depressurization time of 10 seconds, as described in Example 17.
Figure 69 is a photographic image of the fifth part molded using a depressurization rate of 0.0629 GPa/sec, as described in Example 17.
Figure 70 is a photograph of block 45, which is a cross-sectional block out of 60 blocks manufactured as described in Example 22.
Figure 71 is a photograph of block 27, a cross-sectional block out of 60 blocks manufactured as described in Example 22.
72 is a photograph of block 60, which is a cross-sectional block among 60 blocks manufactured as described in Example 22.
Figure 73 is a photograph of a fort built with bricks manufactured as described in Example 22.
74 is a photographic image of a cross-section of parts made from 0%, 25%, 50%, and 100% recycled plastic as described in Example 23, and on the right, cross-sections for parts made from 0% and 100% recycled material. Shows an enlarged image of .
Corresponding reference signs indicate corresponding parts throughout the drawings.

Although this disclosure provides reference to preferred embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of the invention. Various embodiments will be described in detail with reference to the drawings, with like reference numbers indicating like parts and assemblies throughout the several drawings. References to various embodiments do not limit the scope of the claims appended hereto. Additionally, any embodiments presented herein are not intended to be limiting, but merely suggest some of the many possible embodiments pertinent to the appended claims.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art. In case of conflict, this document, including definitions, will control. Preferred methods and materials are described below, but methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All publications, patent applications, patents and other references mentioned herein are hereby incorporated by reference in their entirety. The materials, methods and examples disclosed herein are illustrative only and are not intended to be limiting.

As used herein, “polymer matrix,” including “continuous polymer matrix,” “thermoplastic polymer matrix,” “molten polymer matrix ,” and similar terms, refers to a continuous solid or molten thermoplastic polymer phase or element that defines a continuous phase. Indicates the quantity of solid or molten thermoplastic polymer.

As used herein, “ molten mixture ” means a molten thermoplastic polymer or a mixture of molten thermoplastic polymers, optionally including one or more additional substances admixed with the molten thermoplastic polymer or mixture thereof.

As used herein, " molten pneumatic mixture " means a mixture of a thermoplastic polymer and a pneumatic source, wherein the polymer is at a temperature above its melting temperature and the temperature of the mixture is above the critical temperature of the pneumatogen source; The mixture is also characterized by being free of pneumatocytes or substantially free of pneumatocytes. The molten pneumatic mixture is under a pressure sufficient to prevent pneumatic cell formation, substantially prevent pneumatic cell formation, or cause the pneumatogen source to dissolve or disperse within the thermoplastic polymer as a gas or supercritical liquid. “Substantially preventing pneumatic cell formation,” “substantially free of pneumatic cells,” and similar terms, with respect to molten pneumatic mixtures, mean that the pressure conditions will be used to prevent pneumatic cell formation in the molten mixture. On the other hand, it means that defects in process equipment, wear and tear of parts, etc. can cause unintended pressure losses that do not generally interfere with obtaining and maintaining a pressurized molten mixture.

As used herein, “ foam ,” “polymer foam,” “thermoplastic polymer foam,” “molten foam,” “melted polymer foam,” and similar terms generally refer to a plurality of pneumatites as discontinuous phases dispersed therein. It represents a continuous polymer matrix defining the cell.

As used herein, the term “ pneumatocell ” refers to discrete pores defined by and surrounded by a continuous thermoplastic polymer matrix.

As used herein, the term “ pneumatogen ” refers to a gaseous compound capable of defining pneumatocytes in a molten thermoplastic polymer matrix.

As used herein, the term “ critical temperature ” means the temperature at which a pneumatogen source produces pneumatogen at atmospheric pressure.

As used herein, the term “ pneumatogen source ” means added to or present within a thermoplastic polymer matrix, such as dissolved in the matrix and/or present therein as a supercritical fluid; It is in the form of an organic compound that produces pneumatogens by a chemical reaction; represents a latent, latent, or early pneumatogen, or a combination thereof; The pneumatogen source is pneumatogen, becomes pneumatogenic, or produces pneumatogen at a critical temperature characteristic of the pneumatogen source.

As used herein, the term “rapid depressurization” means a pressure drop that occurs at a rate greater than 0.01 GPa/s, such as between 0.01 GPa/s and 5 GPa/s.

As used herein, the term "high back pressure" means a back pressure of 500 kPa or more, such as between 500 kPa and 25 MPa, and further back pressure is, for example, the pressure required across the barrel or in the collection area of the injection molding machine to initiate depressurization. is the critical mass of

As used herein, the terms “comprise,” “includes,” “having,” “have,” “may,” “contains,” and variations thereof are open ended and do not exclude the possibility of additional actions or structures. It is intended to be a transitional phrase, term, or word. Singular forms include plural references unless the context clearly indicates otherwise. This disclosure also contemplates other embodiments that “comprise,” “consist of,” and “consist essentially of” the embodiments or elements set forth herein, whether or not explicitly set forth therein.

As used herein, the term “optional” or “optionally” means that a subsequently described event or circumstance may but does not have to occur, and that the detailed description includes instances where the event or circumstance occurs and instances where it does not. do.

As used herein, the amounts, concentrations, volumes, process temperatures, process times, yields, flow rates, pressures, and similar values of components in the composition, and ranges thereof, are used to describe embodiments of the disclosure. The term “about” means, for example, through typical measuring and handling procedures used in the preparation of a compound, composition, concentrate or dosage form for use; Through accidental errors in this process; Indicates changes in numerical quantities that may occur through differences in manufacturer, source, or purity of the starting materials or ingredients used in carrying out the method, and similar proximate considerations. The term “about” also includes different amounts due to aging of a formulation with a particular initial concentration or mixture, and different amounts due to mixing or processing of a formulation with a particular initial concentration or mixture. When modified by the term “about,” the claims appended hereto include equivalents to such amounts. Additionally, when “about” is used to describe a range of values, for example, references to “about 1 to 5” are replaced with “1 to 5” and “about 1 to about 5,” unless explicitly limited by context. 5" and "1 to about 5" and "about 1 to 5."

As used herein, the term “substantially” means “consisting essentially of” as that term is interpreted in the United States patent law, and includes “consisting essentially of” as that term is interpreted in the United States patent law. For example, a composition that is “substantially free” of a specified compound or substance may be free of such compound or substance or may contain incidental amounts of such compound or substance present, such as through unintended contamination, side reactions, or incomplete purification. You can have it. “Incidental amount” may mean a trace, immeasurable amount, an amount that does not interfere with the value or characteristic, or some other amount as provided by the context. A composition having “substantially” a given list of ingredients may consist solely of these ingredients, may have trace amounts of some other ingredients present, or may contain one or more additional ingredients that do not materially affect the properties of the composition. It may have constituents. Additionally, "substantially", for example, used to describe embodiments of the present disclosure, to modify the type or amount, property, measurable amount, method, value, or range of a component of the composition, refers to the intended composition. , indicates a change that does not affect the overall stated composition, property, amount, method, value, or range thereof in a way that invalidates the property, quantity, method, value, or range. When modified by the term “substantially,” the claims appended hereto include equivalents under that definition.

As used herein, any stated range of values considers all values within the range and should be construed as support for claims reciting any sub-range with endpoints that are real values within the stated range. By way of hypothetical illustrative example, the disclosure herein of a range from 1 to 5 will be deemed to support claims for any one of the following ranges: 1 to 5; 1 to 4; 1 to 3; 1 to 2; 2 to 5; 2 to 4; 2 to 3; 3 to 5; 3 to 4; and 4 to 5.

In embodiments disclosed herein, a method for extruding a molten polymer foam includes adding a thermoplastic polymer and a pneumatogen source to an inlet located at the first end of the extruder; heating and mixing the thermoplastic polymer and the pneumatic source in an extruder to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the critical temperature of the pneumatic source; collecting an amount of the molten pneumatic mixture in a barrel region of the extruder disposed proximate the second end of the extruder; forming an expansion volume in the barrel area, wherein the formation causes a pressure drop in the barrel area; allowing a certain period of time to elapse after the pressure drop; and dispensing the molten polymer foam from the extruder.

In an embodiment, the extruder may be any one designed and suitable for melting, mixing and dispensing thermoplastic polymers and mixtures thereof, optionally together with one or more additional substances such as fillers, nucleating agents, diluents, stabilizers, brighteners, etc. It is a machine; The extruder also includes a collection zone for collecting the mass of mixed, molten material, and also allows for the formation of an expansion volume in the collection zone coupled with a pressure drop. Extruders are well known in industry and are widely used for melting, mixing and manipulating molten thermoplastic polymers. In an embodiment, the extruder is adapted and designed for melting, mixing and dispensing mixtures of thermoplastic polymers and pneumatogen sources. Such extruders are adapted to obtain a molten pneumatic mixture under pressure sufficient to prevent or substantially prevent pneumatic cell formation in the molten pneumatic mixture.

In an embodiment, an extruder useful for carrying out the process of the present invention has an internal volume, referred to in the art as a “barrel” of the extruder, designed and adapted to receive the solid thermoplastic polymer and to effect melting and mixing thereof. Includes. In an embodiment, the extruder receives a solid thermoplastic polymer and a pneumatogen or pneumatogen source and further at least performs melting of the polymer and mixes the pneumatogen or pneumatogen source with the molten polymer to form a molten pneumatic Define the internal volume designed to obtain the mixture. In an embodiment, the extruder further includes a collection zone for collecting lumps of molten pneumatic mixture material. In an embodiment, the extruder further comprises means for forming an expansion volume in the collection zone coupled with a pressure drop.

In an embodiment, the extruder is an injection molding machine. In an embodiment, the extruder is a SODICK™ molder sold by Plustech Inc., Schaumburg, Illinois. In an embodiment, the extruder includes one or two members, known in the art as “barrels”, disposed within an internal volume, known in the art as “screws”. In an embodiment, the screw has an overall right circular cylindrical shape and also includes one or more protruding threaded members, referred to as “flights”. In some embodiments, the extruder comprises one screw movably disposed within the barrel for rotation of the cylinder about its axis, lateral movement of the cylinder along its axis, or combined movement including both rotation and lateral movement. It is a single screw extruder defined as: In another embodiment, the extruder is a two-screw extruder, which is defined as comprising two screws movably disposed within the barrel in substantially parallel and proximate relation to each other, wherein each screw extends a cylindrical axis about its axis. It is movably disposed within the barrel for rotation, lateral movement of the cylinder along its axis, or combined movement including both rotation and lateral movement. The screw of a two-screw extruder is also arranged so that when turned in a counter-rotating manner, the action of the screw defines a designed mixing and transport pattern of the molten thermoplastic polymer disposed within the barrel.

In embodiments, the extruder is also adapted and designed to accommodate solid thermoplastic polymers. In an embodiment, the barrel of the extruder is also adapted and designed to receive the solid thermoplastic polymer by including an inlet located near the first end of the extruder and adapted to add the solid thermoplastic polymer to the barrel. The solid thermoplastic polymer is added to the inlet in any suitable format, such as beads, pellets, powders, ribbons or blocks, all formats familiar to those skilled in the art. In an embodiment, the extruder is an extruder designed and adapted for adding or introducing one or more additional substances comprising one or more solids, liquids or gases into the internal volume of the extruder and for mixing the thermoplastic polymer with one or more additional substances. It includes a second, third or even fourth or more number of injection ports. The internal volume of the extruder receives, contains, and melts the thermoplastic polymer and optionally one or more additional materials; Suitable for subjecting the thermoplastic polymer and optionally one or more additional materials to heat, shear and mixing to form a molten mixture while simultaneously transporting the molten mixture in a generally proceeding direction from its first end to its second end. I get angry. In embodiments where the extruder is a single-screw extruder or a two-screw extruder, shearing, mixing and transport are achieved by rotation of the screw or counter-rotation of two screws.

In an embodiment, the extruder internal volume, or a portion thereof, is surrounded or partially surrounded by one or more heat sources. Heat sources suitably adapted to heat the internal volume of the extruder include, in various embodiments, a heated water jacket, a heated oil jacket, an electrical resistance heater, an open or jacketed flame, or another heat source. The heat source is operable to increase the temperature in the internal volume of the extruder. The temperature is appropriately selected by the operator to melt the thermoplastic polymer and/or maintain the desired temperature within a portion of the internal volume of the extruder. In embodiments, the extruder is adapted to include more than one heat source, the heat sources being independently operable so that one skilled in the art can provide a range of temperature "zones" within the internal volume. Additional temperature zones may be included in some extruders in connection with adding one or more substances to their inlet or dispensing one or more substances from their outlet. In embodiments, the temperature within one or more temperature zones is set by the operator for increased control and optimization of melting, mixing, shearing, and transport of the thermoplastic polymer and, optionally, one or more additional materials.

Extruders are typically designed and adapted to apply and maintain pressure within their internal volume during heating, mixing and transport of the molten mixture. In embodiments, the extruder is designed and adapted to apply and maintain a first pressure within the interior volume or barrel during heating, mixing and transport of the molten mixture. In embodiments, the pressure within the barrel during heating, mixing and transport of the molten pneumatic mixture is sufficient to prevent or substantially prevent leakage of the molten pneumatic mixture from the barrel. In an embodiment, the pressure within the barrel is sufficient to prevent the molten pneumatic mixture from generating pneumatocytes when the temperature within the barrel exceeds the critical temperature of the pneumatogen source. In an embodiment, the pressure within the barrel is substantially sufficient to prevent the molten pneumatic mixture from generating pneumatocytes when the temperature within the barrel exceeds the critical temperature of the pneumatogen source. In such embodiments described in this paragraph, "substantially" means preventing unintended leakage of material or unintended loss of pressure from the barrel due to the manufacturer, age, or manner of use of the extruder and/or screw, as will be familiar to those skilled in the art. indicates. Also in such embodiments, “substantially” in the context of “sufficient to prevent the molten pneumatic mixture from developing pneumatic cells” means while the pressure is maintained against the molten pneumatic mixture, such as up to 10 This means that a small percentage of pneumatogens may unintentionally form pneumatocytes; However, this means that the operator's goal is to maintain enough pressure to prevent pneumocells from forming.

In an embodiment, the barrel of the extruder includes a collection zone for collecting a quantity of the molten mixture in preparation for dispensing the molten mixture from the extruder. The mass of molten mixture is selected by the user. In an embodiment, the molten mixture is a molten pneumatic mixture. In such embodiments, the art term used to describe collecting the mass of molten pneumatic mixture in the collection area of the barrel of the extruder is referred to as "construction of the shot." As will be understood by those skilled in the art of injection molding, to build a shot, a mass of molten pneumatic mixture is directed from the first end of the extruder to the second end - i.e., towards the collection area and To the collection zone - transporting the molten pneumatic mixture by rotation of a screw or screws (or another mixing element) until the entire mass of the desired molten pneumatic mixture is collected and placed in the collection zone of the barrel. It is collected by allowing it to accumulate in the collection area. The collection zone is located between the screw or screws and the second end of the extruder. In some embodiments the collection zone is in pressurized communication with the rest of the barrel, while in other embodiments the collection zone is sealed or pressurized away from the extruder barrel, for example with o-rings, check rings, or screws. or by providing another sealing mechanism arranged annularly around the screws, the collection area is pressurized and isolated from the rest of the barrel.

In conventional injection molding to form thermoplastic polymer foams, a mass, or "shot", of molten pneumatic mixture is pushed toward and into a collection zone by rotation of a screw or screws (or another mixing element), causing the melt to melt. The pneumatic mixture is collected or "built up" in a collection area by transporting it. When the entire selected mass of molten pneumatic mixture is placed within the collection zone, a shot is said to be constructed. Those skilled in the art will understand that the above detailed description of the mechanical elements and features of a melt mixing device, such as an extruder or other melt mixing device, and also of the method of preparing and collecting the melted pneumatic mixture in shots, will be appreciated by It will be understood that the method of using such a device to prepare a pneumatic mixture and construct a shot thereof will be understood.

In accordance with these known methods and devices, a shot of molten pneumatic mixture is typically shot in which pneumatic cells are generated while present in the barrel and also while placed within the collection area, including during mixing, heating, transport and collection. is prevented or substantially prevented. Typically, when the desired shot is collected in the collection zone, a nozzle, gate, door or other movable barrel (in some embodiments, injection molding techniques) is positioned between the collection zone and an outlet located at the second end of the extruder. A shutoff nozzle (as would be appreciated by one of ordinary skill in the art) opens, providing fluid connection from the barrel to the outlet to dispense the shot from the extruder. In some embodiments, when the gate or door is opened, a mechanical plunger is applied to push the molten pneumatic mixture out of the barrel and through the outlet. In an embodiment, the extruder screw or screws are suitably used in a lateral plunging movement in a direction towards the second end of the extruder, which eventually pushes the molten pneumatic mixture out of the collection area of the barrel and through the outlet.

The inventors have established a shot of molten pneumatic mixture in the collection zone of the extruder and then forming, providing or defining an expansion volume in the collection zone of the extruder, wherein the confinement is accompanied by a pressure drop in the collection zone; allowing a period of time to elapse after confinement, referred to herein as the expansion period; It was found to be advantageous to dispense the shot from the extruder after the expansion period. In such embodiments the shot is dispensed in the form of a molten polymer foam. In an embodiment, the expansion volume is defined proximate to the shot placed within the collection zone of the extruder. In an embodiment, the shot is not mixed or subjected to application shear or stretching while the expansion volume is in the process of being defined. In an embodiment, the shot is not transported during the expansion period. In an embodiment, the shot settles, remains, is undisturbed, or is substantially undisturbed in the collection area during the expansion period. In any of the above embodiments, the shot may be heated during the expansion period; In some embodiments, heat is not applied to the shot during the expansion period.

After the expansion period has elapsed or has passed, the molten polymer foam can be dispensed from the second end of the extruder. The molten polymer foam includes a plurality of pneumatocytes. Without being bound by theory, the inventors believe that a pneumatic cell is formed when a molten pneumatic mixture is subjected to an expanded volume and an accompanying pressure drop (second pressure). In accordance with known physical theory, the formation of pneumatocytes is caused by the confinement of the expanded volume and the concomitant pressure drop in the collection zone of the barrel, with a period of expansion during which the pneumatocytes are formed by the action of pneumatogens. You can. In some embodiments, confinement of the expansion volume following construction of the shot results in superior properties resulting from the dispensed molten polymer foam. In other words, the present inventors have shown that the formation of a molten pneumatic mixture under pressure, followed by a pressure drop and subsequent distribution of the mixture (e.g. into a mold cavity) after the formation of a confined volume, provides an unexpected and highly beneficial physical effect when cooling is provided. It has been found that this results in a molten polymer foam giving a solidified polymer foam article with properties.

The inventors have found that molten polymer foam dispensed from an extruder according to the above method yields significant technical advantages. These benefits are observed in solidified polymer foams resulting from cooling the molten polymer foam to a temperature below the melt transition temperature of the thermoplastic polymer. The structure of articles made using molten polymer foam dispensed from the extruder after an expansion period is both macroscopically and microscopically different from polymer foams made by conventional methods; For example, it exhibits excellent properties suitable for structural members. Polymeric foam articles made using the methods, devices, and materials described herein are characterized by having a continuous thermoplastic matrix throughout and a plurality of pneumatocytes distributed throughout the polymeric foam article. This feature applies to articles having a shape and volume such that spheres with a diameter of 2 cm fit into at least one location within the article without protruding from the surface of the polymer foam article. This feature applies to articles having a shape and volume such that spheres with a diameter of 2 cm fit into at least one location within the article without protruding from the surface of the polymer foam article; Additionally the article has a total volume of greater than 1000 cm ³ , greater than 2000 cm ³ , between 2000 cm ³ and 5000 cm ³ , or even greater than 5000 cm ³ .

In an embodiment, confinement of the expansion volume in a single screw extruder is suitably achieved by moving the screw laterally towards the first end of the extruder and away from the collection zone of the extruder where the shots are collected. In an embodiment, confinement of the expansion volume in a two-screw extruder is achieved by moving both screws laterally toward the first end of the extruder and away from the area of the extruder where the shots are collected. The lateral movement is optionally accompanied by rotation of the screw or screws. That is, one or two screws can be rotated during lateral movement or rotation can be stopped during lateral movement. It will be appreciated that confinement of the expansion volume by lateral movement of one or two screws advantageously allows the foam to be selected by the operator of the extruder to provide a selected expansion volume. That is, the distance of lateral movement of the screw or screws is appropriately selected by the operator to define the selected expansion volume.

Accordingly, in embodiments, the expansion volume is the total expected molten polymer foam volume; Alternatively, it is aimed by the operator to add sufficient volume to the collection area to accommodate some percentage of this. The total expected molten polymer foam volume of the shot is based on the amount of thermoplastic polymer and pneumatogen source and any additional materials added to build the shot, and also from the molten polymer foam from which all pneumatogen sources are obtained. It can be calculated assuming that it contributes to the formation of pneumatocytes. 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 (and thus not contributing to pneumatocytes) at the selected pressure. Those skilled in the art will recognize that industrially obtained pneumatogen sources are provided with suitable information to calculate the total expected molten polymer foam volume based on the amount of pneumatogen source added to make the shot, and other process conditions. You will understand. The solubility of the pneumatogen in the polymer as well as the pressure applied during processing must also be taken into account. In an embodiment, the expansion volume is the difference between the shot volume and the expected molten polymer foam volume. In an embodiment, the expansion volume is 10% to 300% of the total expected molten polymer foam volume in the collection zone, such as 15% to 300% of the difference between the shot volume and the expected molten polymer foam volume, or 20%. % to 300%, or 25% to 300%, or 30% to 300%, or 35% to 300%, or 40% to 300%, or 45% to 300%, or 50% to 300%, or 55% From 300% to 300%, or from 60% to 300%, or from 65% to 300%, or from 70% to 300%, or from 75% to 300%, or from 80% to 300%, or from 85% to 300%, or from 90% 300%, or 100% to 300%, or 100% to 200%, or 200% to 300%, or 100% to 105%, or 100% to 110%, or 100% to 115%, or 100% to 120%, or 105% % to 110% or 110% to 115% or 115% to 120% or 120% to 125% or 120% to 150% or 150% to 200% or 200% to 250% or 250% to 300% or 10% to 95%, or 10% to 90%, or 10% to 85%, or 10% to 80%, or 10% to 75%, or 10% to 70%, or 10% to 65%, or 10% to 60%, or 10% to 55%, or 10% to 50%, or 10% to 45%, or 10% to 40%, or 10% to 35%, or 10% to 30%, or 10% to 25% %, or 10% to 20%, or 10% to 15%, or 15% to 20%, or 20% to 25%, or 25% to 30%, or 30% to 35%, or 35% to 40% , or 40% to 45%, or 45% to 50%, or 50% to 55%, or 55% to 60%, or 60% to 65%, or 65% to 70%, or 70% to 75%, or 75% to 80%, or 80% to 85%, or 85% to 90%, or 90% to 95%, or 95% to 100%.

In other embodiments, the expansion volume is 0.1% to 10% of the total expected molten polymer foam volume in the collection zone, such as 0.2% to 10% of the difference between the shot volume and the expected molten polymer foam volume, or 0.5% to 10%, or 1.0% to 10%, or 1.5% to 10%, or 2% to 10%, or 2.5% to 10%, or 3% to 10%, or 3.5% to 100%, or 4 % to 10%, or 4.5% to 10%, or 5% to 10%, or 6% to 10%, or 7% to 100%, or 8% to 10%, or 9% to 10%, or 1% to 9%, or 1% to 8%, or 1% to 7%, or 1% to 6%, or 1% to 5%, or 1% to 4.5%, or 1% to 4%, or 1% to 3.5%, or 1% to 3%, or 1% to 2.5%, or 1% to 2%, or 1% to 1.5%, or 1.5% to 2%, or 2% to 2.5%, or 2.5% to 3 %, or 3% to 3.5%, or 3.5% to 4%, or 4% to 4.5%, or 4.5% to 5%, or 5% to 6%, or 6% to 7%, or 7% to 8% , or 8% to 9%, or 9% to 10%.

After the expansion volume has been defined, in some embodiments, a period of time is passed or allowed to elapse before dispensing the molten polymer foam from the extruder. In an embodiment, the period is referred to as the expansion period. In some embodiments, no mixing, transport, shearing, or other physical manipulation, or additional volume change, is performed within the collection zone during the expansion period. Instead, in such embodiments, the shot remains within the collection area for an expansion period. At the end of the expansion period, the molten polymer foam is dispensed from the extruder outlet. In an embodiment, the molten polymer foam is dispensed into a mold cavity and the molten polymer foam is cooled to a temperature below the melt transition of the thermoplastic polymer to obtain a solidified polymer foam article.

In an embodiment, the expansion period is selected by the operator to be about 5 to 600 seconds, depending on the mass of the sample, pneumatogen source and amount, and any additional substances present in the shot. In an embodiment, the inflation 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. 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 from 5 seconds to 180 seconds, or from 5 seconds to 170 seconds, or from 5 seconds to 160 seconds, or from 5 seconds to 150 seconds, or from 5 seconds to 140 seconds, or from 5 seconds to 130 seconds, or from 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 seconds, or 5 seconds to 40 seconds, or 5 seconds to 30 seconds, or 5 seconds to 20 seconds, or 5 seconds to 10 seconds, or 10 seconds to 15 seconds, or 15 seconds to 20 seconds, or 20 seconds to 25 seconds. , or 25 seconds to 30 seconds, or 30 seconds to 35 seconds, or 35 seconds to 40 seconds, or 40 seconds to 45 seconds, or 45 seconds to 50 seconds, or 50 seconds to 55 seconds, or 55 seconds to 60 seconds, or 60 seconds to 70 seconds, or 70 seconds to 80 seconds, or 80 seconds to 90 seconds, or 90 seconds to 100 seconds, or 100 seconds to 110 seconds, or 110 seconds to 120 seconds, or 120 seconds to 130 seconds, or 130 seconds to 140 seconds, or 140 seconds to 150 seconds, or 150 seconds to 160 seconds, or 160 seconds to 170 seconds, or 170 seconds to 180 seconds, or 180 seconds to 190 seconds, or 190 seconds to 200 seconds, or 200 seconds seconds to 250 seconds, or 250 seconds to 300 seconds, or 300 seconds to 350 seconds, or 350 seconds to 400 seconds, or 400 seconds to 450 seconds, or 450 seconds to 500 seconds, or 500 seconds to 550 seconds, or 550 seconds to It's 600 seconds.

Additionally, the inventors have discovered that the expansion period, such as 600 to 2000 seconds or more, can be appropriately selected by the operator depending on the mass of the sample, the pneumatogen source and amount, and any additional substances present in the shot. That is, even very long residence times in the collection zone - more than 30 minutes - do not have any detrimental effect on the molten pneumatic mixture or on the solidified polymer foam that results after dispensing and cooling the polymer foam. This result is unexpected because the molten polymer foam allows the volume to expand, thereby forming pneumatocytes and dispersing within the molten, flowable polymer. Those skilled in the art will recognize that a molten polymer foam can be prepared for up to 30 minutes or more without significant migration of pneumatocytes from the molten material and without concomitant loss of the continuous polymer matrix defining the plurality of pneumatocytes dispersed throughout the resulting polymer foam article. One would not expect it to melt and remain undisturbed under reduced pressure.

In an embodiment, using the method described herein, by using rapid depressurization of the molten pneumatic mixture in the collection zone, and in an embodiment further using high back pressure to initiate the rapid depressurization, the polymer foam described herein No expansion period is required to provide a molten polymer foam capable of forming an article (expansion period of 0 seconds) or 0.1 to 5 seconds, such as 0 to 1 second, 1 to 2 seconds, 2 to 3 seconds, 3 seconds. A molten polymer foam is obtained that requires an expansion period of only 4 to 4 seconds, or 4 to 5 seconds. In injection molding machines, this means that the molten polymer foam can be dispensed immediately after depressurizing. Accordingly, when using rapid depressurization, the expansion period is selected by the operator to be about 5 to 0 seconds, depending on the mass of the sample, the pneumatogen source and amount, and any additional substances present in the shot. In an embodiment, the inflation 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. seconds to 0.8 seconds, or 5 seconds to 0.9 seconds, or 5 seconds to 1 second, 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 to 2 seconds, or 0.1 to 1 second, or 1 to 2 seconds, or 2 to 3 seconds, or 3 to 4 seconds, or 4 to 5 seconds. Example 17 shows an exemplary but non-limiting expansion period of 0.5 seconds. This expansion period is sufficient to produce a polymer foam article with a continuous polymer matrix defining a plurality of pneumatocytes dispersed throughout the article, as shown in Figure 56.

Maintaining the reduced pressure for a selected period of time after depressurizing at a depressurization rate selected to provide a pressure drop may be collectively referred to as the “depressurization step.” Unexpectedly, the inventors have discovered that the depressurization rate is inversely proportional to the expansion period required to obtain a molten polymer foam that ultimately provides a polymer foam article when applied to a molded element as described in any of the embodiments herein. . Specifically, the inventors have found that an inflation time of 0 to 5 seconds can be suitably selected by applying rapid depressurization. That is, in the collection zone, by depressurizing the molten pneumatic mixture at a rate of 0.01 GPa/s to 5.0 GPa/s or more, in some embodiments, a sphere theoretically having a diameter of 20 cm to 1000 cm is formed at at least one location therein. No expansion period is required to form a molten polymer foam that is dispensed onto the molding element providing a polymer foam article with a shape and volume sufficient to accommodate it without protruding from the surface. In some such embodiments, rapid depressurization is coupled with high backpressures required to initiate depressurization, such as greater than 500 kPa, such as from 500 kPa to 25 MPa or more, in order to obtain very large volumes of polymer foam articles. A polymer foam article theoretically of sufficient shape and volume to accommodate at least one location therein a sphere having a diameter ranging from 20 cm to 1000 cm has a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout the article. It is additionally characterized by: In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

In some embodiments, the depressurization step is followed by one or more additional pressurization/depressurization steps, for example, 1 to 5 cycles of pressurization followed by depressurization. The pressurization step is carried out by reducing the volume in the collection zone close to the molten pneumatic mixture, the reduced volume causing an increase in pressure (pressurization). The pressure increase is then maintained for a pressurization period of less than 1 second before performing a second depressurization step. Additionally, the pressurization rate in the pressurization step is selected to be at least 0.0059 GPa/s. That is, in an embodiment, the velocity defining the reduced volume in the collection zone, causing an increase in pressure in the collection zone, is greater than or equal to 0.0059 GPa/s.

Accordingly, in embodiments, one or more pressurization/depressurization cycles are suitably performed prior to dispensing the molten polymer foam from the collection zone. For example, collecting shots in a collection zone under pressure is a first pressurization step, and the first pressurization step is followed by a first depressurization step to complete the first pressurization/depressurization cycle. In some embodiments, the molten polymer foam is dispensed from the collection zone after the first pressing cycle. In another embodiment, the second pressurization step is performed followed by a second depressurization step, thereby completing the second pressurization/depressurization cycle. A third, fourth or fifth pressurization/depressurization cycle may be performed additionally prior to dispensing the molten polymer foam from the collection zone. In Example 19, a single pressurization/depressurization cycle is compared to three to five pressurization/depressurization cycles, and the resulting polymer foam articles are described.

In each of the 1 to 5 pressurization/depressurization cycles, each pressurization cycle includes a pressurization rate and pressurization time as well as an individually selected reduced volume (or applied pressure) in the collection zone according to the above parameters for pressurization. Additionally, in each of the 1 to 5 pressurization/depressurization cycles, each decompression cycle includes an expansion volume (or reduced pressure), expansion (decompression) rate, and expansion period individually selected according to the above parameters for decompression. . In this way, a customized pressurization/depressurization profile can be appropriately determined by the operator to achieve optimal results for forming polymer foam articles as described below. Accordingly, in some embodiments, the molten pneumatic mixture is subjected to 1 to 5 cycles of pressurization/depressurization prior to dispensing the molten polymer foam from the collection zone, and further each step of each cycle is performed to achieve optimal pressure within the collection zone. The pressure change, rate of pressure change and duration of pressure change retention can be individually tailored to provide volume/time or pressure/time profiles.

Using any of the above methods provides several significant technical advantages, as described in the sections below, when the molten polymer foam is cooled to a temperature below the melt temperature of the thermoplastic polymer to obtain a solidified polymer foam. Causes the formation of polymer foam. Polymeric foam articles are generally characterized as monolithic articles having a continuous polymer matrix defining a plurality of pneumatocytes distributed throughout the article. In an embodiment, the polymer foam article is characterized as having a continuous polymer matrix defining a plurality of pneumatocytes dispersed, inter alia, in the surface area of the article, wherein the surface area is the surface of the article (polymer foam-air interface) and the surface of the article. It is defined as the area of the article between an internal distance of 500 microns.

A representative embodiment of an apparatus useful in carrying out the above method is shown in Figure 1A. 1A is a schematic diagram of an exemplary single-screw injection molding apparatus 20 according to embodiments disclosed herein, i.e., useful for carrying out the methods described herein for making molten polymer foams and polymer foam articles also disclosed herein. am. As shown in FIG. 1A , injection molding system 20 includes a motor or drive section 24 and a barrel 21 attached to a mold section 26. Barrel 21 includes a first end 21a, a second end 21b and defines a hollow inner barrel portion 22. Barrel portion 22 also defines a nozzle 36 proximate the barrel second end 21b. The screw 30 is disposed within the barrel portion 22 and includes a screw tip portion 34. The screw 30 is configured to rotate the screw 30 about its central axis; or operably connected to the motor section 24 for lateral movement indicated by arrow Z. The lateral movement of the screw 30 is generally in the direction from the barrel first end 21a to the barrel second end 21b; Alternatively, it may be in a direction from the second end of the barrel (21b) to the first end of the barrel (21a). The lateral movement of the screw 30 in either direction is optionally also coupled with a rotational movement. The screw 30 also includes one or more flights 31, which are generally mixing elements for mixing and transporting the substances present in the barrel portion 22 from the barrel first end 21a towards the barrel second end 21b. do. The screw 30 is arranged in the barrel part 22 in a pressure-sealed relationship therein, and by means of the screw flights 31 in the barrel 21 and also by the situation of the check valve 32, the barrel part 22 It makes it possible for pressures to be maintained in excess of atmospheric pressure. A shut-off valve (37) is connected to the barrel (21) near the second end (20b) and is adapted to control the fluid connection, the pressurized connection, or both, between the nozzle (36) and the mold section (26). It is operable. A check valve (32) disposed within the barrel portion (22) and surrounding the screw (30) is operable to prevent back pressure from pushing material present in the barrel portion (22) toward the barrel first end (21a), whereby providing a pressure-sealed, fluid-sealed, or pressurized-fluid-sealed relationship between the isolation valve 37 and the check valve 32, respectively.

Also with reference to Figure 1A, mold section 26 includes two mold sections 38 as shown. Mold sections 38 are removably joined together to define a cavity 39. In some embodiments, one or more of the mold sections 38 are movable to allow discharge of solidified polymer foam articles therefrom. In some embodiments, mold sections 38 are positioned in contacting relationship with each other; In another embodiment, the mold sections 28 are spaced apart by a gap.

In embodiments, the methods disclosed herein are suitably performed using devices such as system 20 shown in FIGS. 1A and 1B. 1A, a selected mass of mixture 42A comprising selected amounts of thermoplastic polymer, pneumatogen source, and optionally one or more additional materials is flowed through inlet 28 into barrel section 22 as indicated by arrow A. is added to In some embodiments, the pneumatogen source is pneumatogen, and inlet 28 or another inlet (not shown) is a gas inlet that is pressurized with barrel section 22; The pneumatogen is added to the gas inlet at a selected pressure, while the non-gaseous material is added to the inlet 28. During addition of mixture 42A to barrel portion 22 through inlet 28, motor 24 is operable to rotate screw 30. Rotation of the screw 30 transports and mixes the mixture 42A to the screw tip 34. A heat source (not shown) is suitably used to heat the mixture 42A within the barrel portion 22. The motor 24 rotates the screw 30 to move the barrel 21 in a direction generally proceeding from the first end 21a toward the second end 21b of the barrel 21 until the screw tip 34 is reached. The mixture 42A present in section 22 is transported. Additionally, rotation of screw 30 provides mixing of mixture 42A during transport. As the mixture 42A is transported and mixed by rotation of the screw 30, a heating element or heating band (not shown) proximate the barrel portion 22 operates to heat the mixture 42A. Multiple heating zones may be present proximate the barrel portion 22 to vary the temperature inside the barrel portion 22 between the first end 21a and the second end 21b of the barrel 21. During transport, a screw 30 rotating within the barrel portion 22 is operable to mix the mixture 42A; Heat is applied to the mixture while it is being transported, above the melting point of the thermoplastic polymer to transform mixture 42A into molten pneumatic mixture 42B by reaching at least the second end 21b of barrel 21. Raise the temperature of the mixture. Additionally, coupled with a check valve (32), a shut-off valve (37) in the closed position, or both; Additionally, the arrangement of the screw 30 within the barrel portion 22, where the flights 31 are in contact with the barrel 21 during rotation of the screw 30, provides a pressure-sealed relationship within the barrel portion 22, thereby preventing melting. The pneumatic mixture 42B is present in the barrel portion 22 under pressure exceeding atmospheric pressure. The pressure within barrel portion 22 is sufficient to prevent or substantially prevent pneumatocyte formation even when the pneumatogen source exceeds its critical temperature.

Rotation of the screw 30 also operates to transport the press-molded pneumatic mixture toward the screw tip 34, thereby depositing a selected portion of the press-molded pneumatic mixture 42B within the collection region 40 of the barrel portion 22. Transport or build chunks. The collection zone 40 is the area within the volume of the barrel portion 22 extending between the check valve 32 and the shut-off valve 37 in FIG. 1A and also the barrel portion located along the X distance of the barrel 21. It is defined as the area of (22). Selected chunks or “shots” of pressurized molten pneumatic mixture 42B are collected or built up in collection zone 40 of barrel portion 22. The pressure within collection zone 40 is sufficient to prevent or substantially prevent pneumatic cell formation in the molten pneumatic mixture. In an embodiment, the shot substantially fills collection zone 40.

Constructing a shot of molten pneumatic mixture 42B is accomplished using conventional methods familiar to those skilled in the art. Customary and known variations of the methods and materials used in the construction of shots for injection molding are included in the methods described herein. Once the shot is constructed, it can be applied to the methods disclosed herein to obtain all of the technical advantages disclosed herein with respect to the formation of polymer foams and polymer foam articles. For example, methods such as the MUCELL® high pressure process used by Trexel Inc., Wilmington, Mass., to form the shot, are suitably used, and include pressurized mixing to prevent or substantially prevent pneumocell formation. Addition of a gaseous pneumatogen source directly to the extruder is followed by shot collection. Various patent techniques and industry literature also describe special melt mixing and conveying designs for obtaining molten pneumatic mixtures and forming shots, such as special screw designs for mixing and counterflow patterns, etc.; Any of these may be usefully used in conjunction with shot forming methods and devices to form shots and collect the shots under pressure within the collection zone of the melt mixing device as described herein.

When the shot is formed and collected in the collection zone, an expansion volume is confined therein, and further expansion is accompanied by a drop in pressure in the collection zone and in the proximity of the shot. In embodiments, the pressure drop is achieved at a rate of at least 0.01 GPa/s. Accordingly, Figure 1A shows the molten pneumatic mixture device 20 with the screw 30 positioned to collect the shots in the collection zone 40. The shot contains a selected mass of molten pneumatic mixture 42B and is placed under pressure within the collection zone 40. At this stage of the method, also with reference to FIG. 1A , FIG. 1B shows the device 20 where the screw 30 is positioned to define an expansion volume 44 within the collection zone 40 . More specifically, Figure 1b shows the screw 30 in a position resulting from a lateral movement of the screw 30 towards the first end 21a of the barrel; That is, the screw 30 is retracted in FIG. 1B compared to FIG. 1A. The retraction of the screw 30 from the collection zone 40 and the resulting partial displacement defines an expansion volume 44 within the collection zone 40 and also causes a drop in pressure within the collection zone 40 . In some embodiments, screw 30 is retracted from collection zone 40 at a rate that causes rapid depressurization within collection zone 40, such as greater than 0.01 GPa/sec. In some embodiments, rotation of screw 30 is stopped prior to retraction. In some embodiments, rotation of screw 30 is stopped during retraction or after retraction is complete. The distance of retraction of the screw 30, i.e. the distance of lateral movement of the screw 30 towards the first end 21a of the barrel, is selected by the operator to provide a suitable expansion volume 44.

In some embodiments shown in FIG. 1B , expansion volume 44 is selected by the operator to provide collection zone 40 with a total volume that matches the total expected molten polymer foam volume of the shot; In such an embodiment, the total volume in collection zone 40 after addition of expansion volume 44 is the total expected molten polymer foam volume of molten pneumatic mixture 42B of FIG. 1B. In another embodiment, the expansion volume 44 is configured to provide a collection zone 40 with a total volume that is a percentage of the total expected molten polymer foam volume of the molten pneumatic mixture or shot present in the collection zone 40. selected by the operator; That is, the total volume in collection zone 40 after addition of expansion volume 44 is about 50% to 120% of the total expected molten polymer foam volume. In some embodiments, the expansion volume is set to provide the total volume in the collection zone to accommodate 100% of the total expected molten polymer foam volume.

After retracting the screw 30 to define the expansion volume 44 as shown in Figure 1B, a period of time, referred to as the "expansion period", during which the shot remains within the collection area 40 as shown in Figure 1B. As this passes or passes, in particular the collection zone 40 comprises an expansion volume 44 . The inflation period is selected by the operator to be from 0 to 2000 seconds. In an embodiment, the shot remains undisturbed or substantially undisturbed within the collection area 40 during the expansion period. In embodiments, “undisturbed” means that the shot is not subjected to any processes that cause mixing, shearing, or transport (flow) of the shot during the expansion period. In embodiments, “substantially undisturbed” means that the collection area is not purposefully disturbed by mixing, shearing or transport processes performed during the expansion period, but is subject to, for example, heat differentials, leaks and other manufacturing issues in the collection area during the expansion period. This means that it may cause unintended stress or strain in the existing shot.

By rapidly retracting the screw 30, the inventors have discovered that by rapidly retracting the screw 30, the device used and the mass of the molten polymer in the collection zone 40, the amount of pneumatogen or pneumatogen source dissolved in or mixed with the molten polymer, Depending on variables such as amount, it has been found that rapid depressurization rates can be achieved, for example at least 0.01 GPa/s, such as 0.1 GPa/s to 5 GPa/s, or greater than 5 GPa/s. In an embodiment, rapid depressurization is coupled with a high backpressure required to initiate depressurization, such as greater than 500 kPa, such as between 500 kPa and 25 MPa. After rapid depressurization, the molten polymer foam is distributed into a molding element such as a mold and cooled; It is re-pressurized/de-pressurized for one or more additional cycles before being distributed to the molding elements and cooled; The resulting polymeric foam article is further characterized as having a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout the article. In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

When further used in conjunction with the methods described herein to form molten polymer foams, the rapid pressure drop (depressurization) optionally coupled with high back pressure in the injection molding machine provides several unexpected advantages.

First, rapid depressurization, optionally coupled with high back pressure in the injection molding machine, allows the formation of very large volume polymer foam articles of almost unlimited sizes and volumes. Accordingly, a polymer foam article having a shape and volume sufficient to receive a sphere theoretically having a diameter from 20 cm to 1000 cm at at least one location therein without protruding from the surface; Or even larger articles are suitably formed using rapid depressurization and optionally high back pressure. The volumes and dimensions achievable using rapid depressurization are limited only by the amount of molten polymer that can be collected and the limitations of the machine in introducing the pressure drop. A polymer foam article theoretically of sufficient shape and volume to accommodate at least one location therein a sphere having a diameter ranging from 20 cm to 1000 cm has a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout the article. It is additionally characterized by: In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

Secondly, rapid depressurization, optionally combined with high back pressure in the injection molding machine, allows an expansion period of 0 to 5 seconds to be selected, and a sphere with a theoretical diameter of more than 2 cm and up to more than 1000 cm is placed on the surface at at least one location inside the article. It still allows the formation of polymer foam articles with a shape and volume sufficient to receive them without protruding from them. The selection of the expansion period from 0 to 5 seconds will depend on the type of thermoplastic polymer used, the amount of pneumatogen or pneumatogen source, and other specific and individual considerations of the operator in forming polymer foam articles according to the methods disclosed herein. It is based on Rapid depressurization, especially when used with high back pressure, provides a stabilized molten polymer foam that requires no or only a very short expansion period, defining a plurality of pneumatocytes throughout the article. A molded polymer foam article is obtained, further characterized as having a continuous thermoplastic polymer matrix. In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

Thirdly, rapid depressurization, optionally combined with high back pressure in the injection molding machine, allows an expansion period of 600 to 2000 seconds to be selected, in which spheres with a theoretical diameter of more than 2 cm and up to more than 1000 cm are placed on the surface at at least one location inside the article. It still allows the formation of polymer foam articles with a shape and volume sufficient to receive them without protruding from them. Rapid depressurization, especially when used with high back pressure, provides a stabilized molten polymer foam that can withstand residence times of 30 minutes or more inside the injection molding machine and still be distributed to the molding elements, thereby providing plurality of particles throughout the article. A molded polymer foam article is obtained, further characterized as having a continuous thermoplastic polymer matrix defining pneumatocytes of In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

Accordingly, a stabilized molten polymer foam is formed using the method described herein, particularly the method described herein where rapid depressurization is used. The stability of the molten polymer foam is further increased when using an injection molding machine such as the apparatus shown in Figures 1A and 1B by combining rapid depressurization with high back pressure to initiate depressurization. The stability of molten polymer foams is remarkable, with the surprising result that very large articles can be formed in the molding elements; This is evidenced by the surprising results that the expansion period can be shortened or eliminated, and also by the surprising result that the stabilized molten polymer foam does not collapse during subsequent dispensing, molding and cooling due to the very long expansion times.

After the expansion period has elapsed, the nozzle shutoff valve 37 shown in FIG. 1B is opened and the molten polymer foam is dispensed from the barrel 22. In the embodiment shown in Figures 1A and 1B, molten polymer foam flows into cavity 39. Dispensing may be by mechanical means, such as plunging using lateral movement of a screw, or by pressurized dispensing by application of pressurized gas to a collection zone, but in some embodiments a device may be used to dispense the molten polymer foam. It is not necessary to apply pressure. In an embodiment, the pressure at the nozzle 36 as shown in FIGS. 1A and 1B during dispensing of the molten polymer foam is increased by an additional force of the screw 30 towards the barrel second end 21b in FIGS. 1A and 1B. Without the addition of an external source of pressure, such as by plunging the molten polymer foam using lateral movement, the pressure ranges from 1 psi (about 7 kPa) to 20 psi (about 138 kPa) above gravity. In an embodiment, dispensing is achieved by maintaining fluid connection between nozzle 36 and cavity 39. In some such embodiments, the fluid connection is also a pressurized connection. In an embodiment, the pressure of the nozzle 36 (also referred to as the injection pressure) as shown in FIGS. 1A and 1B during dispensing of the molten polymer foam is, for example, the barrel second end 21b in FIGS. 1A and 1B. ), or by applying another source of pressure equal to the applied gas pressure, 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.

Alternatively, after retracting the screw 30 and maintaining the position of the screw 30 during the expansion period as shown in Figure 1b, the screw 30 is pressed back toward the barrel second end 21b. ; That is, the screw 30 is partially or fully returned to the position shown in Figure 1A in the pressing step, which reduces the volume of the collection zone 40 and pressurizes the molten pneumatic mixture. The reduced volume within collection zone 40 increases the pressure within collection zone 40. In some embodiments, rotation of screw 30 is stopped prior to pressurization. In some embodiments, rotation of screw 30 is stopped during pressurization or after pressurization is complete. The pressing distance of the screw 30, i.e. the distance of lateral movement of the screw 30 towards the second end 21b of the barrel, is selected by the operator to provide an appropriate volume and pressure. After a selected pressurization period, the operator can choose to dispense the molten pneumatic mixture, or one or more additional pressurization/depressurization cycles prior to dispense.

In embodiments such as where 1 to 5 pressurization/depressurization cycles are used, the operator can select the rate of pressurization and depressurization in addition to the volume/pressure and time to maintain the pressurization or depressurization. Additionally, the operator may select rapid depressurization, high backpressure, or both as appropriate for each one or more of the depressurization stages of one or more cycles.

Once placed within the cavity 39 defined by the mold portion 38 shown in FIGS. 1A and 1B, the molten polymer foam reaches a temperature below the melt transition of the thermoplastic polymer, such as that present at ambient conditions in the ambient environment. It is allowed to cool or cool until it cools. In some embodiments where the expansion volume is set to provide a total volume in the collection zone that is less than 100% of the total expected molten polymer foam volume, the pneumatocel is formed after the molten polymer foam has been dispensed and at a temperature similar to the melting of the thermoplastic polymer. Nucleation and/or evolution (growth in size) may continue before cooling sufficiently to reach the transition temperature. Cooling of the molten polymer foam is accomplished using conventional methods for cooling of injection molded articles, including immersing the mold in a liquid coolant having a set temperature or spraying the mold with a liquid coolant such as liquid water; directing a stream of air to the mold; Ambient air cooling; Including without limitation, etc.

In an alternative embodiment of the method, apparatus 20 configured as shown in Figure 1B is used to form a molten polymer foam. Figure 1b shows the screw 30 in a position resulting from a lateral movement of the screw 30 towards the first end 21a of the barrel; That is, the screw 30 is retracted in FIG. 1B compared to FIG. 1A. The retraction of the screw 30 from the collection zone 40 and the resulting partial displacement defines an expansion volume 44 within the collection zone 40 and also causes a drop in pressure within the collection zone 40 . The apparatus 20 configuration as shown in Figure 1b is used to mix, heat and transport the molten pneumatic mixture 42B towards the second end 21b of the barrel 21 in substantially the same manner as described above. . Additionally, coupled with a check valve (32), a shut-off valve (37) in the closed position, or both; Additionally, the arrangement of the screw 30 within the barrel portion 22, where the flights 31 are in contact with the barrel 21 during rotation of the screw 30, provides a pressure-sealed relationship within the barrel portion 22, thereby preventing melting. The pneumatic mixture 42B is present in the barrel portion 22 under a pressure exceeding atmospheric pressure. The pressure within barrel portion 22 is sufficient to prevent or substantially prevent pneumatocyte formation even when the pneumatogen source exceeds its critical temperature. However, in this alternative embodiment, the molten pneumatic mixture is transported through a check valve (32) and to a collection zone (40) further augmented by an expansion volume (44).

Additionally, in this alternative embodiment, in the configuration shown in FIG. 1B, device 20 mixes, heats and moves molten pneumatic mixture 42B toward second end 21b of barrel 21 and ; The screw 30 is then pressed towards the first end 21a of the barrel 21 to pressurize the molten pneumatic mixture present in the collection zone 40. Pressurization is effected by rapid depressurization, optionally utilized with high back pressure, to obtain stabilized polymer foams as described above.

It is an advantage of the process disclosed herein that conventional materials and equipment for extrusion and injection molding are useful in carrying out the process. No special equipment or material requirements are necessary to perform the disclosed methods. Accordingly, any thermoplastic polymer or mixture thereof useful for injection molding and/or forming polymer foams may be prepared using conventional techniques such as standard injection molding equipment, optionally with one or more additional materials selected by the operator of the equipment. It is usefully combined with industrially useful pneumatogen sources.

In embodiments, thermoplastic polymers useful in connection with the methods, devices, and articles described herein include: any thermoplastic plastic or mixture thereof known in the industry to be useful 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 shot forming. As such, thermoplastic polymers may be thermoreversible or otherwise contain a degree of crosslinking that does not prevent sufficiently viscous melt flow for injection molding processes.

In embodiments, thermoplastic polymers useful with the methods, devices, and articles described herein include olefin-based polymers such as polyethylene, polypropylene, poly α-olefins and various copolymers thereof, and branched/crosslinked modifications such as, but not limited to, low density polyethylene ( LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), thermoplastic polyolefin elastomer (TPE), ultrapolymer weight polyethylene (UHMWPE), etc.; Polyamides (PA), polyimides (PI), polyesters such as polyester terephthalate (PET) and polybutylene terephthalate (PBT), polyhydroxyalkanoates (PHA) such as polyhydroxybutyrate (PHB), Polycarbonate (PC), poly(lactic acid) (PLA), acrylonitrile-butadiene-styrene copolymer (ABS), polystyrene, polyurethane such as thermoplastic polyurethane elastomers (PU, TPU), polycaprolactone, polyvinyl Chloride (PVC), copolymers of tetrafluoroethylene, polyethersulfone (PES), polyacetal, polyaramid, polyphenylene oxide (PPO), polybutylene, polybutadiene, polyacrylates and methacrylates (acrylics). , ionomer polymers (SURLYN® and similar ionically functionalized olefin copolymers), polyether-amide block copolymers (PEBAX®), polyaryletherchitones (PAEK), polysulfones, polyphenylene sulfide (PPS) , polyamide-imide copolymers, poly(butylene succinate), cellulosic, polysaccharides, and copolymers, alloys, mixtures, and blends thereof, which are described herein. It is usefully used in conjunction with the method described in .

With regard to the non-limiting use of polymer blends and mixtures, the inventors have found that mixed stream recycled plastics are useful in embodiments as thermoplastic polymers. Accordingly, in an embodiment, the marine waste plastic is harvested from the ocean and beaches and has a polyolefin content of 10% to 90%, a PET content of 10% to 90%, a polystyrene content of 1% to 25%, and a polyolefin content of 1% to 50%. A mixed stream of polymeric waste having an exemplary content of unknown polymer content. Such mixed plastic streams and waste plastic streams, including but not limited to those collected from oceans and beaches, are similarly useful for forming molten polymer foams and polymer foam articles using the methods and devices described herein. Example 11 illustrates the use of a mixed stream marine waste plastic source with a 20% recycled content.

Additionally, the inventors have discovered that polymer foam articles made according to the methods described herein can be recycled using the methods described herein. That is, in embodiments, a first polymer foam article according to any of the embodiments described herein and formed according to any of the methods described herein may also be used to form a second polymer foam article according to the methods described herein. It is a source of thermoplastic polymers. In an embodiment, the polymeric foam articles described herein are appropriately recycled using any of the methods described herein for making polymeric foam articles. Accordingly, the polymer foam article can be prepared, for example, by simply grinding the first polymer foam article prepared according to the method described herein, or alternatively by shredding and dividing into suitable sizes for direct use in a melt mixing device; And the first polymer foam article can be recycled by subjecting it to a melt mixing device. The melt mixing device may be an injection molding machine or an extruder. When the melt mixing device is an injection molding machine, using the split first polymer foam article as a source of feedstock or polymer, performing any of the methods described herein to form a polymer foam article, thereby forming a second polymer foam article. A polymer foam article may be formed. In this way, a mixed source of segmented polymer foam articles (different thermoplastics, additives, etc.); Alternatively, blended feedstocks may also be used, such as mixtures of split polymer foam articles with other plastic materials, such as virgin or used plastic sources.

The above recyclability of polymer foam articles includes low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), high-impact polystyrene (HIPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), It is observed across a variety of polymeric materials, including but not limited to polyamides (PA), thermoplastic polyurethanes (TPU), and thermoplastic olefins (TPO). Recyclability is observed for single component polymer foams, blends of polymers with additives including any of the additives listed herein, and mixtures and formulations of two or more polymers. Example 16 illustrates this surprising and unexpected result. Because it is difficult to use 100% recycled thermoplastics for processes such as extrusion and injection molding, the plastics industry typically supplies mixed plastic waste streams for industrial recycling purposes, and as such recycled plastic items are often or contains only a portion of recycled material mixed with virgin plastic, such as 10% to 50% recycled plastic by volume. However, using the methods described herein, 100% recycled plastic materials can be used to make the polymer foam articles described herein. Additionally, 100% virgin thermoplastic materials can be used to make the polymer foam articles described herein as well as mixtures of recycled and virgin material feedstocks, and the polymer foam articles formed from these feedstocks can be subjected to subsequent injection molding. Alternatively, it is 100% recyclable in the extrusion process.

Pneumatogen sources are widely available in industry, and the conditions useful for using pneumatogen during melt mixing are well understood and widely reported. Accordingly, any pneumatogen source useful in injection molding, reaction injection molding, or other methods of making polymer foams can be used to form molten polymer foams and solidified polymer foam articles according to the methods, devices, and polymer foam articles described herein. It is useful in this hospital. Pneumatogens useful in connection with the methods and devices described herein include air, CO ₂ , and N _{2 ,} in latent form or encapsulated in thermoplastics, such as bead pellets, where the chemical reaction is achieved by heating in a melt mixing device. When generated, CO ₂ or N ₂ is generated. Such chemical reactions are exothermic or endothermic, as appropriate, without limitation, with respect to their use in combination with the methods and devices disclosed herein. Suitable pneumatogen sources include sodium bicarbonate, compounds based on polycarboxylic acids such as citric acid, or salts or esters thereof such as sodium citrate or trimethyl ester of sodium citrate; mixtures of sodium bicarbonate and polycarboxylic acids such as citric acid; Sulfonyl hydrazides such as p -toluene sulfonyl hydrazide (p-TSH) and 4,4'-oxybis-(benzenesulfonyl hydrazide) (OBSH), pure and modified azodicarbonamides, semicarbazides , tetrazole, and diazinon. In any of the above, the pneumatogen source is optionally also encapsulated in a carrier resin designed to melt during heating, mixing and collection of the shot.

In embodiments, useful pneumatogen sources include commercially available compositions such as HYDROCEROL® BIH 70, HYDROCEROL® BIH CF-40-T, or HYDROCEROL® XH-901 (all from Clariant AG, Switzerland); FCX 7301 (RTP Company, Winona, MN); FCX 27314 (RTP Company, Winona, MN); CELOGEN ® 780 (CelChem LLC, Naples, FL); ACTAFOAM® 780 (Galata Chemicals, Southbury, CT); ACTAFOAM® AZ (Galata Chemicals, Southbury, CT); ORGATER MB.BA.20 (ADEKA Polymer Additives Europe, Mulhouse, France); ENDEX 1750™ (Endex International, Rockford, IL); and FOAMAZOL™ 57 (Bergen International, East Rutherford, NJ).

In some embodiments, the pneumatogen source is pneumatogen, and the pneumatogen is applied as a gas to a melt mixing device, such as a device similar to the extruder shown in FIGS. 1A and 1B. In such embodiments, the gas is dissolved in the thermoplastic polymer by direct pressure addition to and mixing within the melt mixing device. In some embodiments, the gas is rendered supercritical fluid by pressurization prior to or concurrently with dissolution into the molten thermoplastic polymer. Applying pneumatogens directly to an injection molding device is industrially represented as the MUCELL® process used by Trexel Inc., Wilmington, Delaware. Special equipment is required for this process, such as a controlled, pressurized fluid connection from a gas reservoir (tank, cylinder, etc.) to the inlet of the extruder device to form a pressurized relationship with the barrel while the thermoplastic polymer is also added to and melted in the barrel. do. Where such specialized equipment is available, the pneumatogen may be used as a 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. It is useful.

The pneumatogen source is in an amount aimed at reducing the selected density of the thermoplastic polymer, according to conventional techniques relating to the pneumatogen and the operation of the pneumatogen source to form a thermoplastic polymer foam and the desired polymer foam density. polymer, and optionally one or more additional substances. The amount of pneumatogen source added to the thermoplastic polymer is not particularly limited; Accordingly, the inventors have found that density reductions of up to 85% can be achieved without the use of polymers or glass bubbles, etc., providing polymer foam articles with the unique and surprising characteristics reported below and also having a target density reduction of up to 85%. . As used herein, “density reduction” refers to a polymer foam article relative to the same article without the addition of a pneumatogen (source) to produce the article (i.e., a polymer article that excludes or substantially excludes pneumatocytes). Means percent mass reduction. Accordingly, in embodiments, the molten polymer foams and polymer foam articles described herein suitably exclude glass or polymer bubbles while retaining up to 85%, such as 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 a selected density reduction of 80% to 85%. Incorporating glass or polymer bubbles also further expands the available density reduction of polymer foam articles made in accordance with the methods herein. In some embodiments, density reductions of greater than 85% can be achieved.

Polymer foam articles that nevertheless benefit from reduced density have a shape and volume that allows a theoretical sphere, such as a glass or metal ball or bead with a diameter of 2 cm, to fit into at least one location within the article without protruding from the surface of the polymer foam article. characterized as having a continuous polymer matrix throughout, with pneumatocytes dispersed therein. In an embodiment, the polymer foam article has a shape and volume such that spheres ranging from 2 cm to 1000 cm or more in diameter fit into at least one location within the article without protruding from the surface of the polymer foam article. In an embodiment, the polymeric foam article has a shape and volume such that spheres ranging from 2 cm to at least 1000 cm in diameter fit into at least one location within the article without protruding from the surface of the polymeric foam article, and further have a total article volume of more than 1000 ^cm3. , at least 2000 cm ³ , 1000 cm ³ to 5000 cm ³ , 2000 cm ³ to 5000 cm ³ , or greater than 5000 cm ³ . The shape of the polymer foam article is not limited and can generally be a cuboid, spheroid, toroid, or any other desired shape.

As mentioned above, the amount of pneumatogen source added to the thermoplastic polymer is not particularly limited; Accordingly, the inventors have found that up to 85% of the total volume of the polymer foam article contains pneumatocytes. The total volume of pneumatocytes as a percentage of the total volume of the polymer foam article is expressed as the “void fraction” of the article; A porosity of up to about 85% is achieved without the inclusion of polymer or glass bubbles, etc., providing a polymer foam article that has the unique and surprising characteristics reported below and also has a target porosity of up to 85% of the volume of the polymer foam article. Accordingly, in embodiments, the molten polymer foams and polymer foam articles described herein suitably exclude glass or polymer bubbles while retaining up to 85%, such as 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%. Incorporating glass or polymer bubbles also expands the available porosity of polymer foam articles made in accordance with the methods herein. In some embodiments, porosity greater than 85% can be achieved. Nevertheless, a polymer foam article with 85% porosity has a shape and volume in which spheres ranging from 2 cm to 1000 cm in diameter fit into at least one location within the article without protruding from the surface of the polymer foam article, and further have a total article volume of A molded article having a size greater than 1000 cm ³ , greater than 2000 cm ³ , 1000 cm ³ to 5000 cm ³ , 1000 cm ³ to 5000 cm ³ , or 12000 cm ³ to 5000 cm ³ , or greater than 5000 cm ³ , as well as dispersed therein. It is characterized by having a continuous polymer matrix throughout with pneumatocytes.

In some embodiments, the thermoplastic polymer and pneumatogen source are mixed prior to applying the blend to a melt mixing device for heating and mixing. In another embodiment, the thermoplastic polymer and pneumatogen source are added separately to the melt mixing device, such as by means of two different inlets or ports available for adding materials to the melt mixing device. In yet another embodiment, the solid mixture comprising both the thermoplastic polymer and the pneumatogen source is added as a single input to a melt mixing device for heating and mixing.

In an embodiment, one or more additional materials are included or added to the melt mixing device along with the thermoplastic polymer and pneumatogen source; Such additional materials may be suitably mixed or blended with the thermoplastic polymer, pneumatogen source, or both; One or more additional substances are added separately, such as by separate ports or inlets, to the melt mixing device. Examples of 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. Additional examples of suitable materials include fibers such as glass fibers, carbon fibers, cellulose fibers and fibers containing cellulose, natural fibers such as cotton or wool fibers, and synthetic fibers such as polyester, polyamide, or aramid fibers; and microfibers, nanofibers, crimped fibers, shredded or chopped fibers, phase-separated mixed fibers such as bicomponent fibers comprising any of the above-mentioned polymers, and from any of the above-mentioned polymers. Includes formed thermoset. Further examples of suitable additional materials also include waste materials, including woven or non-woven fabrics, fabrics or papers, which are suitably shredded or shredded; sand, gravel, crushed stone, slag, recycled concrete and artificial soil aggregates; and other biological, organic, and mineral waste streams and mixed streams. Further examples of suitable additional materials include minerals such as calcium carbonate and dolomite, clays such as montmorillonite, sepiolite, and bentonite, mica, wollastonite, hydromagnesite/huntite mixtures, synthetic minerals, silica aggregates or colloids, aluminum. Hydroxides, alumina-silica complex colloids and particulates, halloysite nanotubes, magnesium hydroxide, basic magnesium carbonate, precipitated calcium carbonate, and antimony oxide. Additional examples of suitable additional materials include carbonaceous fillers such as graphite, graphene, graphene quantum dots, carbon nanotubes, and C ₆₀ buckeyballs. Further examples of suitable additional materials include thermally conductive fillers such as boronitride (BN) and surface-treated BN.

In an embodiment, the one or more additional substances may represent about 0.1% to 50% of the mass of the thermoplastic polymer, such as 0.1% to 45%, 0.1% to 40%, 0.1% to 45% of the mass of the thermoplastic polymer added to the melt mixing device. 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%, 1% 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%, 20% to 50%, 25% to 50%, 30% to 50%, 35% to 50% , 40% to 50%, 45% to 50%, 0.1% to 2%, 2% to 5%, 5% to 10%, 10% to 15%, 15% to 20%, 20% to 25%, 25 % to 30%, 30% to 35%, 35% to 40%, 40% to 45%, or 45% to 50%, or added to a melt mixing device with the thermoplastic polymer and pneumatogen source to produce a shot. forms.

Accordingly, it will be understood by those skilled in the art that, in a melt mixing device other than an extruder, the following process will result in a molten polymer foam having significant technical advantages as described in the sections below. A method of forming and collecting a molten polymer foam includes the following steps: heating and mixing a thermoplastic polymer and a pneumatic source to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture is pneumatic The pressure applied to the molten pneumatic mixture exceeds the critical temperature of the gen source and is sufficient to substantially prevent the formation of pneumatic cells; collecting a selected amount of molten pneumatic mixture in a collection zone; defining an expansion volume in a collection zone proximate to the molten pneumatic mixture causing a pressure drop; maintaining the inflation volume during the inflation period; and collecting the molten polymer foam from the collection zone. In embodiments, the molten pneumatic mixture is undisturbed or substantially undisturbed during the expansion period. In embodiments, defining the expansion volume is achieved with rapid depressurization (i.e., a rate defining the pressure drop) of at least 0.01 GPa/s, in embodiments greater than 0.1 GPa/s; in some embodiments greater than or equal to 1.0 GPa/s, such as up to 5.0 GPa/s; or 0.01 GPa/s to 5.0 GPa/s, 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 GPa/s to 1.0 GPa/ s, or 1.0 GPa/s to 2.0 GPa/s, or 2.0 GPa/s to 3.0 GPa/s, or 3.0 GPa/s to 4.0 GPa/s, or 4.0 GPa/s to 5.0 GPa/s. In some such embodiments, rapid depressurization is performed at high backpressures, i.e., at least 500 kPa, such as 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 4 MPa. 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 kPa to 3 MPa, or 500 kPa to 2 MPa, or 500 kPa to 1 MPa, or 1 MPa to 5 MPa, or 5 MPa to 10 MPa. It is linked to back pressure.

In an embodiment, using the method described herein, by using rapid depressurization of the molten pneumatic mixture in the collection zone, and further using high back pressure to initiate the rapid depressurization, the diameter is at least 20 cm. spheres measuring from 2 cm to 1000 cm comprising a polymer foam article having a shape and volume that fits into at least one location within the article without protruding from the surface of the article, and further having a total article volume of greater than 1000 cm ³ , greater than or equal to 2000 cm ³ , or No expansion period is required to provide a molten polymer foam capable of forming the polymer foam articles described herein, including articles that are 1000 cm ³ to 5000 cm ³ , 2000 cm ³ to 5000 cm ³ , or greater than 5000 cm ³ . , a stabilized molten polymer foam is obtained that requires a shortened expansion period of 0 to 5 seconds, such as 0 to 1 second, 1 to 2 seconds, 2 to 3 seconds, 3 to 4 seconds, or 4 to 5 seconds.

In some embodiments, collecting the molten polymer foam includes applying the molten polymer foam to a cavity defined by the mold; and cooling the molten polymer foam below the melting temperature of the thermoplastic polymer to obtain the polymer foam article. In embodiments where the molten polymer foam is applied to the cavity of the mold, the cooled polymer foam article acquires the shape and dimensions of the mold, and the polymer foam is characterized by a continuous polymer matrix with pneumatocytes distributed throughout the article. do. In an embodiment, the molten polymer foam is applied to the mold cavity by allowing the molten polymer foam to flow by gravity and enter the mold cavity; In some such embodiments, flow is allowed to enter the open cavity unimpeded. In another embodiment, the molten polymer foam is applied under pressurized flow to the molding element. In an embodiment, the molten polymer foam is delivered from a nozzle to the mold cavity by fluid connection thereto, or by other means of delivery of the molten polymer foam from a collection area of the melt mixing device.

For example, in an embodiment, the extruder is adapted and designed to dispense the molten mixture from an outlet to a molding element, which is a mold defining a cavity therein, and is designed to receive a molten polymer mixture, such as a molten pneumatic mixture. and adapted. In an embodiment, the molding element is a mold configured and adapted to receive the molten thermoplastic polymer dispensed from the outlet, wherein the mold generally defines a cavity or cavities having the selected shape and dimensions of the desired article. .

In embodiments, dispensing from the extruder is achieved by mechanical plunging, application of gas pressure from inside the barrel of the extruder, or a combination thereof. In other embodiments, the outlet, valve, gate, nozzle, or door to the collection zone is simply opened after the expansion period has elapsed and the molten polymer foam flows unobstructed through the outlet; The molten stream is then sent to cooling or other processing equipment, or the molten stream is poured into forming elements. In another embodiment, the forming element is designed and adapted to be fluidically connected to the outlet and filled with the molten mixture so that the molten mixture acquires the selected shape when cooled and solidified. In some embodiments, the forming element is fluidly connected to the extruder outlet so that pressure is maintained between the collection zone, the outlet, and the forming element or mold. Any conventional thermoplastic molding or forming method associated with injection molding of polymer articles, such as polymer foam articles, is suitably used to mold the molten polymer foams described herein.

In some embodiments where the molten polymer foam flows unimpeded through the outlet, or is plunged under pressure from the outlet without additional impedance of the flow, the molten flow eventually flows to a surface, such as generally in the direction of the melt flow. hits a vertical surface. The present inventors believe that the flow under these circumstances may be characterized by sustained melting, as reported by Batty and Bridson, "Accurate Viscous Free Surfaces for Buckling, Coiling, and Rotating Liquids" Symposium on Computer Animation , Dublin, July 2008. It was observed that generally cylindrical (coiling) and planar (folding) patterns are obtained during the flow.

In an embodiment, after the molten polymer foam is dispensed into the mold cavity, the molten polymer foam is cooled to a temperature below the melt transition of the thermoplastic polymer to obtain a solidified polymer foam article. In an embodiment, the molten polymer foam flows or “pours” unimpeded from the outlet of the melt mixing device and into a mold that is configured as an open container. In an embodiment, the open container mold is completely filled with molten polymer foam; In another embodiment, the open container mold is partially filled with molten polymer foam. In another embodiment, the molten polymer foam is dispensed by plunging or pushing the screw of the extruder laterally in a direction toward the nozzle.

During dispensing the molten polymer foam into the mold cavity, the molten polymer foam flows into the mold cavity, contacts the cavity surfaces, and then advances to fill the mold cavity. In embodiments, dispensing includes partially filling the mold cavity with molten polymer foam, such that no more than 50% of the mold cavity volume is occupied by 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 dispensing. In another embodiment, dispensing includes substantially filling the mold cavity with molten polymer foam, such that 50% to 99.9% of the mold cavity volume is occupied by molten polymer foam, such as 50% to 99.5%, or 50% to 99.9% of the mold cavity volume. % 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% From 99.9% to 99.9%, or from 98% to 99.9%, or from 99% to 99.9%, or from 99.5% to 99.9% of the mold cavity volume is filled with molten polymer foam after dispensing. In still other embodiments, dispensing includes completely filling the mold cavity with molten polymer foam, with 100% of the mold cavity being occupied by molten polymer foam after dispensing.

In some embodiments relating to the molten flow described above, a substantially shear-free coiled molten flow, or a substantially linear molten flow, is provided by fluid communication between the outlet of the extruder and within the mold cavity. In some such embodiments, a coiled melt flow can be obtained by impinging the melt flow against its vertical surface or by flowing down a substantially vertical wall or side of the mold cavity and collecting at the bottom of the mold cavity. there is. A schematic diagram of one such embodiment is shown in Figure 41, which shows a variation of the extruder of Figures 1A and 1B, with the mold 26 of the device 20 positioned on a substantially horizontal surface 100. Regarding the elements shown in Figures 1a and 1b, there is no shut-off valve 37 at the distal end 21b of the barrel 21; Instead, in FIG. 41 , collection zone 40 extends to mold valve 137 located proximate mold cavity 39 defined within mold 26. Accordingly, the mold valve 137 is operable to define a collection zone 40 or to provide an outlet for dispensing the molten polymer foam to the mold cavity 39 via a substantially linear horizontal flow 110. . The mold valve 137 is positioned at a height H above the horizontal surface 100 and at a height H2 above the bottom or bottom 120 of the mold 26 positioned on the horizontal surface 100 . 41 , mold valve 137 is selectively opened to provide fluid communication between collection zone 40 and mold cavity 39. Accordingly, mold valve 137 is selectively opened to provide a substantially linear horizontal flow 110 of molten polymer foam entering mold cavity 39. Upon entering the mold cavity 39, the linear flow flows downward over a distance H2, in some embodiments obtaining a coiled melt flow as it progresses to fill the mold cavity 39. Other related variations of the methods and devices are contemplated to provide the coiled melt flow described herein.

In an embodiment, upon cooling and removing a polymer foam article from an open container or mold positioned as shown in Figure 41, a coiling and folding flow pattern is visible at the surface of the article. Examples of such visible flow patterns can be seen, for example, in Figures 2B and 2D. Upon cryofracturing and microscopic examination of the interior of a polymer foam article formed using coiling and folding flow, the interior of the article is free or substantially free of flow patterns, interfaces, or other evidence of coils and folds. For example, cryogenic fracture of such polymer foam articles does not cause fracture at any discernible interface between coils and folds; Both macroscopic and microscopic examination of the interior of such polymer foam articles yields a homogeneous appearance with respect to the flow pattern. The physical properties of such polymer foam articles are determined by subjecting the molten polymer foam to a driven fluid flow, or by pressurizing the molten polymer foam to a driven fluid flow, through a fluid connection between the outlet of the melt mixing device and the mold. It is consistent with the physical properties obtained by application.

In some embodiments, the methods herein include substantially filling a mold with molten polymer foam formed according to the method described above, followed by cooling the molten polymer foam to form a solidified polymer foam; Embodiments also include removing the solidified polymer foam article from the mold. In an embodiment, the molten polymer foam is a stabilized molten polymer foam. In an embodiment, cooling is cooling to a temperature below the melt transition of the thermoplastic polymer. In an embodiment, cooling is cooling to a temperature that is in equilibrium with the ambient temperature of the surrounding environment. In some embodiments, the mold also includes one or more vents for pressure equalization in the mold during its filling with molten polymer foam, but in other embodiments no vents are present. After cooling, the polymer foam article can be removed from the mold for further modification or use.

In some embodiments, after cooling the molten polymer foam to form a solidified polymer foam article and removing the polymer foam article from the mold, 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 post-molding expansion.

In accordance with any of the above detailed descriptions, Table 1 shows that by using a conventional single screw extruder type reaction injection molding apparatus and also using one or more representative thermoplastic polymers as shown and a citric acid-based pneumatogen source, Provides useful but non-limiting examples of processing conditions used to prepare molten polymer foams.

[Table 1]

In embodiments, the dimensions of molds usefully used to form polymer foam articles made using the methods and materials disclosed herein can be cavities that can be filled by a single shot of molten polymer foam or a single shot of molten polymer foam. It includes a mold defining a series of cavities that can be filled by shots. As above, the size of the mold cavity is limited only by the size of the shot that can be built in the melt mixing device used by the user. Representative mold cavities with a volume of up to 1x10 ⁵ cm ³ are useful for manufacturing large parts such as automotive cabin or exterior parts, I-beam construction parts, and other large plastic articles that make suitable use of polymer foams. Furthermore, the shape of the mold cavity is not particularly limited and can be complex with respect to the overall shape and even surface patterns and features, for example dumbbells, tableware, decorative globes with protruding geographical features, human or animal or insect figures, A framework or encasement shape for framing or encasing, for example electronics, appliances, automobiles, etc., for the subsequent placement and fitting of screws, bolts and other non-thermoplastic articles into or through polymer foam articles. shape; etc. are all suitable mold shapes for molding the polymer foam articles described herein. In some embodiments, the cavity includes a thickness gradient of up to 300% for one or more regions of the cavity.

Conforming to any of the above detailed descriptions, Table 2 provides a useful list of mold cavity volumes and mold dimensions useful for molding molten polymer foam by pressurized or unimpeded flow of the molten polymer foam into the mold. Non-limiting examples are provided. Additionally, larger mold volumes, such as up to 100,000 cm ³ or more, are useful if the shot mass is appropriately increased.

[Table 2]

Any of the methods, processes, uses, machines, devices, or individual features thereof described above are freely combinable with one another to form polymer foams and polymer foam articles with unique and surprising characteristics. Accordingly, in embodiments, polymeric foam articles are formed using the methods, materials, and devices described above. Polymer foam articles are prepared by forming or molding a molten polymer foam according to any of the methods and materials disclosed above as well as variations thereof that can be combined in any manner to form the molten polymer foam described above. It is a separate, integrated object.

Accordingly, terms used in the above discussion to refer to methods, materials and devices are used hereinafter to refer to articles made using one or more of the methods, materials and devices included in the above discussion.

In an embodiment, any combination of the above methods results in the formation of a polymer foam article comprising, consisting essentially of, or consisting of a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes. The continuous thermoplastic polymer matrix comprises, consists of, or consists essentially of a solid thermoplastic polymer, ie the thermoplastic polymer exists at a temperature below its melting transition. In an embodiment, the continuous thermoplastic polymer matrix also includes one or more additional materials dispersed in the solid thermoplastic polymer.

The polymer foam article gains a density reduction, based on the density of the thermoplastic polymer and any other materials added to form the polymer foam, of a selected percentage based on the amount of pneumatogen source added to the shot. In embodiments, density reductions of 30%, 40%, 50%, 60%, 70% and even up to 80% to 85% are selected by the user. In an embodiment, density reduction of up to 85% is achieved solely by the presence of discontinuously distributed pneumatocytes in the polymer matrix. In embodiments, the polymeric foam article excludes hollow particulates such as polymer or glass bubbles added to the shot prior to forming the polymeric foam article using the methods and devices described herein.

Also in connection with reduced density, as mentioned above, the polymer foam articles herein are characterized as having a continuous thermoplastic polymer matrix throughout or substantially throughout. The inventors have discovered that large-scale polymer foam articles can be suitably formed from the molten polymer foams disclosed herein to include a continuous polymer matrix defining a plurality of pneumatocytes. A “large polymer foam article” is one with a shape and volume such that a sphere 20 cm in diameter fits into at least one location within the article without protruding from the surface of the article. In some embodiments, a “large polymer foam article” has a shape and volume such that spheres 20 cm in diameter fit into at least one location within the article without protruding from the surface of the polymer foam article, and further have a total volume of at least 1000 cm ³ , for example, at least 2000 cm ³ , at least 3000 cm ³ , at least 4000 cm ³ , or at least 5000 cm ³ , or any volume between 1000 cm ³ and 5000 cm ³ ; or between 2000 cm ³ and 5000 cm ³ and 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 more.

Large polymer foam articles can suitably be formed from a molten polymer foam that has been stabilized to include a continuous polymer matrix defining a plurality of pneumatocytes throughout it. The volume of the article is limited only by the size of the mold cavity and the size of the shots that can be collected in the melt mixing device. In embodiments, large articles are formed from a single shot distributed from a single outlet of a melt mixing device, i.e., directing the molten polymer foam stream into multiple simultaneous distribution pipes, nozzles, or multiple melted streams simultaneously into one mold cavity. Formed without division in any other way.

Additionally, the inventors have discovered that thick polymer foam articles can be suitably formed to include a continuous polymer matrix defining a plurality of pneumatocytes. As used herein, thickness refers to the straight line distance through the interior of a polymer foam article between any two points on the surface of the article. “Thick” items are those over 2 cm, 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. It is defined as having a thickness of more than 45 cm, 45 cm, or even 50 cm. In some embodiments, polymeric foam articles characterized as large, thick are formed using the methods and materials described herein, and the large, thick polymeric foam articles nonetheless define a plurality of pneumatocytes throughout the article. It is characterized by having a continuous polymer matrix. In embodiments, large, thick articles can be prepared from a single shot distributed from a single outlet of a melt mixing device, i.e., by directing the molten polymer foam flow into multiple simultaneous distribution pipes, nozzles, or multiple melted streams simultaneously into one mold cavity. Formed without division in any other way.

In an embodiment, polymeric foam articles formed using the methods described herein have a shape and volume such that a (theoretical) sphere 2 cm in diameter fits into at least one location within the article without protruding from the surface of the polymeric foam article. In some embodiments, the polymeric foam article comprises a shape and volume such that a (theoretical) sphere greater than 2 cm in diameter fits into at least one location within the article without protruding from the surface of the polymeric foam article. In an embodiment, the polymer foam article has a shape and volume such that a (theoretical) sphere with a diameter of 2 cm to 1000 cm fits into at least one location within the article without protruding from the surface of the polymer foam article; For example, in one or more embodiments, the diameter is 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 cm-25 cm, 25 cm-30 cm, 30 cm-35 cm, 35 cm- 40cm, 40cm-45cm, 45cm-50cm, 50cm-60cm, 60cm-70cm, 70cm-80cm, 80cm-90cm, 90cm-100cm, 100cm-200cm , 200cm-300cm, 300cm-400cm, 400cm-500cm, 500cm-600cm, 600cm-700cm, 700cm-800cm, 800cm-900, or even 900cm-1000cm. The (theoretical) sphere fits into at least one location within the article without protruding from the surface of the polymer foam article. In an embodiment, a polymer foam article formed using the method described herein is shaped to fit within the article without overlapping two or more (theoretical) spheres with a diameter of 2 cm and none of the spheres protruding from the surface of the polymer foam article, and It has volume. For example, 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. 90-95, 95-100, 100-200, 200-300, 300-400, 400-500, 500-1000, 1000-1500, 1500-2000 or even more than 2000 2 cm spheres, without overlapping, polymer foam It fits within the article without protruding from the surface of the article.

In some embodiments of a polymer foam article having a shape and volume such that a (theoretical) sphere with a diameter of 2 cm fits into at least one location within the article without protruding from the surface of the polymer foam article, the polymer foam article has a sphere with a diameter of 2 cm ( It further includes one or more locations where the theoretical sphere does not fit, wherein the theoretical sphere protrudes from the surface of the article. Such articles are shown in Figures 2b, 32 and 33. Figure 2B shows a polymer foam article made according to Example 1: a molded 6 inch (15.2 cm) diameter sphere with attached cylindrical features, the diameter of the cylindrical features being between 6.25 mm and 10.40 mm depending on where the cylinder is measured. It varies between. The cylindrical feature integrally connected with the sphere in FIG. 2B has a diameter less than 2 cm and therefore cannot accommodate a theoretical sphere of 2 cm in diameter therein without the sphere protruding from the cylindrical surface. Likewise, Figures 32 and 33 are polymer foam articles made according to Example 12: a molded 9 inch (22.9 cm) diameter sphere with attached cylindrical features, the diameter of the cylindrical features being 5.64 mm depending on where the cylinder is measured. It varies from 8.99 mm to 8.99 mm. The cylindrical features integrally connected with the spheres in FIGS. 32 and 33 have a diameter smaller than 2 cm and therefore cannot accommodate a theoretical sphere of 2 cm in diameter without the sphere protruding from the cylindrical surface.

In particular, the inventors have demonstrated that obtaining rapid depressurization rates, i.e., depressurization rates of at least 0.01 GPa/s to 5 GPa/s, can be achieved with the methods described herein to form molten polymer foams in very large volumes. The unexpected possibility of forming a polymer foam article, i.e., a polymer foam article having a shape and volume sufficient to theoretically accommodate a sphere with a diameter of 20 cm to 1000 cm within it at least in one location, without protruding from the surface. provides advantages. In some such embodiments, rapid depressurization is coupled with high backpressures required to initiate depressurization, such as greater than 500 kPa, such as between 500 kPa and 500 MPa, in order to obtain very large volumes of polymer foam articles. A polymer foam article theoretically of sufficient shape and volume to accommodate at least one location therein a sphere having a diameter ranging from 20 cm to 1000 cm has a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout the article. It is additionally characterized by: In some such embodiments, the surface area extending 500 microns from the surface of the article includes compressed pneumatocytes throughout.

An exemplary, but non-limiting, very large polymer foam article is shown in Example 22 and in Figure 73, in which a solid, rectangular cuboid polymer foam article with a volume of about 17,000 cm ³ is formed, and further the article is formed on the surface of the article. Two theoretical 20 cm diameter spheres fit inside it, without a single sphere protruding from it.

The manufacture of large, thick, or large and thick polymer foam articles is problematic in the industry due to the cooling gradient of the molten foam after it has been distributed into cavities having such dimensions. The interior of such articles tends to cool very slowly, and some of the thermoplastic polymer placed in the mold cavity may remain above its melting temperature before the thermoplastic solidifies (achieving a temperature below its melt transition). Allow significant coalescence of pneumatocytes to occur. In sharp contrast, the inventors have discovered that large articles, thick articles, and large thick articles can be suitably formed using the methods, materials, and devices disclosed herein, and wherein the formed polymer foam articles have pneumatocytes distributed throughout the article. It was found to be characterized by a continuous polymer matrix. The slower-cooling interiors of larger articles show minimal or no evidence of pneumocell coalescence during cooling. The pneumatocytes 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 the size, thickness or volume of the polymer foam article formed.

This feature of the polymer foam articles described herein is surprising and unexpected: prior art methods result in foams that are prone to pneumatic cell coalescence during cooling. Accordingly, the prior art molten polymer foam placed in the interior volume of the mold can be cooled slowly to completely coalesce the pneumatocytes, thereby allowing the interior of large or thick articles formed using conventional polymer foaming methods to adhere to their interior. Very large gaps or even completely collapsed structures can be obtained. In sharp contrast, molten polymer foams formed according to the method of the present invention do not undergo substantial pneumatocell coalescence or collapse of the continuous polymer matrix during cooling of the molten polymer foam. Accordingly, large, thick polymer foam articles having a continuous polymer matrix throughout are achieved using the methods, materials, and devices described herein.

A structural feature of the polymer foam article according to the methods, devices and materials is that a continuous polymer matrix is present throughout the polymer foam article, including its surface area. The surface area may be appropriately characterized as the interior region of the polymer foam article that is less than 500 microns from the surface. The surface area, as defined herein, is that portion of a region of a foamed article, commonly referred to as the "skin layer," which is an area free of pneumatocytes or substantially free of pneumatocytes in a polymer foam article made using conventional methods. am. Typically formed foam articles include a skin layer at least as thick as the surface area, say 500 microns thick; Often the skin layer is much thicker and can extend 1 mm, 1.5 mm, 2 mm, 2.5 mm or even 3 mm from the surface of the article. However, polymer foam articles formed using the methods disclosed herein achieve a true foam structure from their surfaces and throughout their thickness and volume. In embodiments, microscopic examination reveals evidence of pneumatocytes on the surface of polymer foam articles formed using the conditions, methods, and materials disclosed herein. Accordingly, the methods disclosed herein can be used throughout the polymer foam article, in any direction, and in all areas thereof - within very large and/or thick polymer foam articles and also at the surface of the article and within the surface area. Included - in, unexpected results are obtained with regard to the continuous nature of the polymer matrix structure.

The following examples include analysis of the surface area of multipolymer foam articles prepared using the methods disclosed herein and exhibiting this continuous foam structure. To the naked eye, polymer foam articles made using the methods disclosed herein may appear to have a skin layer: that is, the surface area of the article may appear different from the interior area of the article. However, the inventors have found that, in sharp contrast to the skin layer, which is characterized by the absence of pneumatocytes, the surface area of the polymer foam article produced by the method of the present invention contains a plurality of compressed pneumatocytes. . To the naked eye, compressed pneumatocytes create an appearance suggestive of a skin layer; Microscopic examination reveals that visually apparent differences arise from a “flattened” or compressed arrangement of the continuous polymer matrix near the surface of the article.

Accordingly, a gradual transition from spherical pneumatocytes to compressed pneumatocytes moving toward the surface of a polymer foam article formed using the conditions, methods and materials disclosed herein, for example as shown in Figures 17 and 18. exists. Accordingly, in an embodiment, the surface area of a polymer foam article made using the methods disclosed herein includes a plurality of compressed pneumatocytes. In an embodiment, compressed pneumatocytes are present in the surface area of a polymer foam article made using the methods disclosed herein. In some such embodiments, the compressed pneumatocytes are within the interior region of the polymer foam article less than 500 microns from the surface. In some such embodiments, the compressed pneumatocytes are present within the interior region of the polymer foam article up to 2 cm from the surface. A compressed pneumatocell is defined as a pneumocell with a circularity of less than 1, with a circularity value of 0 indicating a perfectly non-spherical pneumatocell and a value of 1 indicating a perfectly spherical pneumatocell. In an embodiment, pneumatocytes having a circularity of less than 0.9 are observed in the surface area of the foamed polymer article, and are also present in 10% to 90%, or 10% to 80%, or 10% of the pneumatocytes in the surface area. From 70% to 70%, or from 10% to 60%, or from 10% to 50%, or from 10% to 40%, or from 10% to 30%, or from 10% to 20%, or from 20% to 80%, or from 20% 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%, has a circularity of 0.9 or less. In an embodiment, the average circularity in the surface area of the foamed polymer article 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.

In an embodiment, the compressed pneumatocytes are within the polymer foam article greater than 500 microns from the surface of the article. For example, in embodiments, the compressed pneumatocytes are at most 1 mm from the surface of the polymer foam article, or at most 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 1 cm, or more. In some embodiments, the area of compressed pneumatocytes in the polymer foam article corresponds to 0.01% to 70% of the total volume of the article, such as 0.1% to 70%, or 0.5% to 70% of the total volume of the article. %, 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 1%, or 0.01% to 0.1%.

Figures 12 and 14 show plots of average pneumatocell size and average pneumatocell coefficient versus average pneumatocell circularity for two polymer foam articles made using the methods disclosed herein. Quantitative analysis of pneumatocell size and distribution reveals an inverse relationship between average pneumatocell size and pneumatocell circularity, and between average pneumatocell size and number of pneumatocells.

Figure 18 also shows visual evidence that pneumatocytes are present on the surface of polymer foam articles formed using the methods, materials and devices described herein. Figure 18 also shows visual evidence that a plurality of compressed pneumatocytes are present substantially 500 microns away from the surface of a polymer foam article formed using the methods, materials and devices described herein. In this sense, the polymer foam articles disclosed in the present invention differ significantly from the foam articles of the prior art. The "skin layer", or first 500 microns of thickness, of a foam article made by conventional methods does not contain or is substantially free of pneumatocytes, which generally have a spherical shape wherever they are placed. This is a characteristic of prior art foam articles. Accordingly, at typical thicknesses in foam articles at which pneumatocytes are observed, they are generally spherical with a circularity of approximately 1 or about 1. Compressed pneumatocytes are not formed using conventional methodologies for making foam articles, and therefore the distribution of pneumatocell circularity is not observed in such conventional foam articles. Additionally, pneumatocytes do not form even in the first 500 microns of thickness of foam articles made by conventional methods, so there is no need to worry about the surface area of the foamed polymer articles described herein and the foam articles made using conventional injection molding methods. No comparison can be made regarding Matocell.

Additionally, the conditions, methods and materials disclosed herein are suitably optimized to form polymer foam articles with different physical properties depending on the targeted end use or application. For example, the density of a polymer foam article varies appropriately as a function of expansion volume. By lowering the expansion volume, the density of the resulting polymer foam article is reduced in a generally linear manner, as shown, for example, in Figure 5. As can also be seen from Figure 5, increasing the expansion period results in the formation of more dense polymer foam articles. Such conditions and other variables, all within the scope of the conditions, methods and materials disclosed herein, are suitably used to change the physical properties of the resulting polymer foam article.

In one variation of the conditions, methods and materials disclosed herein, the molten polymer foam is appropriately distributed by splitting the flow of molten polymer foam into two, three, four or more paths directed to multiple molds or mold sections, Form multiple polymer foam articles from a single shot. In another variation of the conditions, methods and materials disclosed herein, two shots are used to fill a single mold, the first shot comprising the thermoplastic polymer content or proportion of blended polymers, the pneumatogen source, and optionally included It differs from the second shot with respect to one or more additional materials, density, porosity, depth of region of compressed pneumatocytes, or some other material or physical property difference.

In another variation of the conditions, methods, and materials disclosed herein, polymer foam articles made using the methods disclosed herein were subjected to fastener pull out testing in accordance with ASTM D6117. Polymer foam articles achieve excellent pull-out strengths for foam articles made using conventional foaming methods. Additionally, polymer foam articles formed using the materials, methods and devices disclosed herein do not require pre-drilling, tapping or engineering of fastener locations.

In yet another variation of the conditions, methods, and materials disclosed herein, polymer foam articles made using the methods disclosed herein are subjected to ballistic testing. Using guidelines from the National Institute of Justice (NIJ) "Ballistic Resistance of Body Armor NIJ Standard-0101.06", a series of 3-inch thick polymer foam articles were prepared using a citric acid-based pneumatogen source to form a polyether-amide block aerial. It was formed from polymer (PEBAX®), linear low density polyethylene (LLDPE), and polypropylene. Polymer foam articles made using all three of these thermoplastic polymers have been found to pass NIJ Level I, stopping a .22 LR pistol bullet; It has passed NIJ Level II and IIA and has been shown to stop 9 mm LUGER® pistol bullets.

experimental section

The following examples are intended to further illustrate the invention and are not intended to limit the scope of the invention in any way. Examples 1 and 11 were performed on an Engel Duo 550 Ton injection molding machine (Engel Machinery Inc., York, Pa.). Examples 2-4 were performed on a Van Dorn 300 injection molding machine (Van Dom Demag, Strongville, OH). Unless otherwise indicated, the remaining examples were performed on an Engel Victory 340 Ton injection molding machine (Engel Machinery Inc., York, Pa.).

In the examples herein, “cc” means “cubic centimeter” (cm ³ ) and “sec” means “second.”

Standard foam molding and MFIM

In the examples herein, two direct injection expansion foam molding techniques were used, referred to herein as “standard foam molding” and “melt foam injection-molding” (“MFIM”).

In standard foam molding, the following general process is used: A) The mixture is composed of a polymer (which can be in the form of pellets, powders, beads, granules, etc.) and a foaming agent (blowing agent) and any other additives such as fillers. The mixture was introduced into an injection device, and the rotating injection device screw moved the mixture forward in the injection device barrel, forming a heated fluid material according to a typical injection molding process. B) A set volume of material was dosed in front of the barrel of the injection device by rotation of the screw, moving the set volume from the feed compartment to the front of the screw. During this feeding phase, the screw was rotated to move the molten mixture forward into the space in the barrel between the screw and the nozzle to provide a set volume. C) The molten mixture was injected into the mold cavity by forward movement of the screw and/or rotation of the screw.

In the melt foam injection-molding (MFIM) method, the following general procedure is used: A) the mixture is composed of a polymer (which can be in the form of nurdles, pellets, powders, beads, granules, etc.) and a chemical blowing agent, and optionally It was prepared by combining other additives such as fillers. The mixture was introduced into the injection device, and the rotating injection device screw moved the material forward in the injection device barrel, forming a heated fluid mass according to a typical injection molding process. B) A set volume of material was dosed in front of the barrel of the injection device by rotation of the screw, moving the set volume from the feed compartment to the front of the screw. During this feeding phase, the screw was rotated to move material between the screw and the nozzle to provide a set volume. C) Once the material has been moved forward of the screw, in a step referred to herein as “depressurization”, the screw is moved back away from the nozzle without or substantially without rotation to avoid moving the material further forward of the screw. Unless otherwise specified, the decompression rate, or depressurization rate, is less than or equal to 0.006 GPa.

An intentional space was created within the barrel between the screw and the nozzle, with a mixture-free space, a volume referred to herein as the “reduced pressure volume”. D) Material remains in the barrel between the screw and the nozzle for a period of time, referred to herein as “decompression time”. During the decompression time, the material foamed due to the pressure drop caused by the space added in step (C). E) The molten foam was injected into the mold cavity by forward movement of the screw and/or rotation of the screw.

Example 1

Two parts were foam molded using a blend of low density polyethylene blended with 2% by weight of Hydrocerol® BIH 70 blowing agent from Clariant AG, Muttenz, Switzerland. Molding was performed using an Engel Duo 550 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). The mold cavity was (approximately) spherical in shape with a diameter of 6 inches (15.24 cm). The first part was molded using a standard foam molding process and the second part was molded using the MFIM process. An aluminum mold with a cooling sprue and runner system supplying a 6 inch diameter spherical cavity was used for both parts. The melt delivery system for each part was identical, as were most process conditions. The process settings for the MFIM process and the standard foam molding process used as a control are detailed in Table 3. From each method, parts were produced with approximately equivalent masses.

[Table 3]

The first part and the second part were photographed. 2A is a photographic image of a first part molded using a standard foam molding process. As shown in the image, the standard foaming method did not yield a part that filled the mold cavity, and the part did not match the shape of the mold's spherical cavity.

Figure 2B is a photographic image of a second part molded using the MFIM process. As shown in the image, the MFIM process yielded a part that completely or substantially filled the spherical mold cavity, and the part matched or substantially matched the shape of the mold's spherical cavity.

The first part, molded using a standard foam molding process, was cut into two pieces. Figures 2C and 2E are photographic images of one of the pieces of the part manufactured according to the standard foam molding process. As seen in the image, the first part contained a large hollow cavity.

The second part molded according to the MFIM process was cut into two pieces. 2D and 2F are photographic images of one of the pieces of the second part. As seen in the image, the second part did not have the large hollow cavities of the standard foam method parts. MFIM parts have an overall cellular structure.

Example 2

Two parts were formed by foam injection molding, part A according to the standard foam molding method and part B according to the MFIM process. In both methods, the LDPE/talc pellets were dry-blended with the blowing agent and mixed during loading into the molding machine.

For Part B, a mixture of low density polyethylene (LDPE), talc, and Hydrocerol® BIH 70 was formed and fed into a Van Dom 300 injection molding machine to provide polymer shots in the barrel. After the shot was accumulated in front of the screw, the screw was moved backwards away from the injection nozzle without rotation according to the MFIM method to create a space between the screw and the nozzle, a space with a reduced pressure volume. The mixture was then foamed into space before injection into the mold.

The same process was used for part A, except that the screw was not pulled back away from the nozzle after the shot was deposited in front of the screw, i.e. the decompression volume was zero. Shots were metered to fill the mold cavity under standard foam molding conditions with the goal of 10% weight reduction compared to solid parts.

Tables 4-7 below show the polymer, mold, machine, and processing settings used in Example 2.

[Table 4]

[Table 5]

[Table 6]

[Table 7]

Part A and Part B were each cut in half to expose the cross section. Figures 3a and 3b show the resulting cross-sections of part A and part B, respectively. As shown in Figure 3A, 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.

Figure 3b shows a cross-section of Part B molded according to the MFIM process using the settings shown in Tables 4 and 5. As shown in Figure 3b, part B had a foam structure containing a distribution of cell sizes and shapes. The solid, non-foamed outer region is virtually absent from Part B. The density of Part B was 0.35 g/cc.

A spherical cavity mold was used to form two additional parts, Part C and Part D, by foam injection molding. The same mixture composition of LDPE, talc, and Hydrocerol® BIH 70 was used to form Part C and Part D. Part C was manufactured by the MFIM process and Part D was manufactured by the standard foam molding process. Both methods produced spherical or approximately spherical parts with a 6 inch (15.24 cm) diameter. Part C and Part D were cut into two pieces through the middle (widest part) to expose the cross section of the parts. Figure 4a is a photographic image of a cross-section of part C (471 g, required cooling time 160 seconds) manufactured by the MFIM process. Figure 4b is a photographic image of a cross-section of part D (1360 g, required cooling time 800 seconds) molded using a standard foam method target.

Similar results were obtained with block mold. Part C, manufactured according to the MFIM process, exhibited cells throughout the part, whereas Part D, manufactured according to the standard foam molding process, exhibited areas adjacent to the outer surface of the part that were cell-free or substantially free (“solid”). Part C was less dense than Part D.

Example 3

In Example 3, block parts were formed using the MFIM process at various decompression volumes (Test A) and at various decompression volumes and decompression times (Test B).

Tables 8-10 show the material composition, mold geometry information, and processing settings used in Test A and Test B.

[Table 8]

[Table 9]

Composite LDPE/talc pellets were mixed with blowing agent immediately before molding.

Test A

In Test A, all parameters were held constant except for the ratio of the volume of polymer to the depressurized volume (empty space) in the barrel prior to injection. The settings for each sample run of Test A are shown in Table 10:

[Table 10]

The volume of molten foam injected into the polymer cavity was constant, but the density of the molten foam was a function of the polymer shot/reduced pressure volume ratio. Polymer shot/reduced pressure volume was varied to produce parts with weights and densities as shown in Table 11:

[Table 11]

The results in Table 11 show that by reducing the mass and volume of polymer in the molten foam shot with a proportional increase in depressurization volume, the density of the resulting part can be changed.

exam B

In Test B, five moldings were performed three times under the same conditions as Test A; This was performed once with a decompression time of 20 seconds (same as Test A), once with a decompression time of 70 seconds, and once with a decompression time of 120 seconds. Fifteen resulting foam-molded parts were weighed and the density was calculated using the volume of the mold cavity. Part density was plotted as a function of decompression volume for each of the three decompression times. The plot is shown in Figure 5. As shown in Figure 5, part density varied as a function of decompression volume. Additionally, as shown in Figure 5, the longer the decompression time, the more dense the part.

Example 4

In Example 4, two series of tests, Series I and Series II, were run using the MFIM process. In Series I, a constant injection speed was used but the mold closure height was varied. In Series II, the mold closure height was increased with increasing injection speed. In series II, all conditions were kept constant except injection speed (cc/sec) and mold closure height. In the test, LDPE/talc pellets were dry blended with blowing agent and mixed during loading into the molding machine.

Tables 12 to 13 below show the material composition of the injected mixture and the base mold configuration used for testing.

[Table 12]

[Table 13]

Series I

In Series I, an injection speed of 394 cubic centimeters per second was used, and three tests were run: Test A with a mold closure height of 1.02 mm, producing Part A; Test B with a mold closure height of 0.76 mm producing Part B, and Test C with a mold closure height of 0.51 mm producing Part C. The settings for the Series I tests are shown in Table 14:

[Table 14]

During each molding cycle (Test A, Test B, and Test C respectively), a strain gauge (Kistler Surface Strain Sensor Type 9232A, Kistler Holding AG, Winterthur, Switzerland ) was mounted directly on or inside the mold cavity. The strain sensor contained two piezoelectric sensors that measured the strain of the aluminum cavity as a function of time during the forming cycle. Strain measurements were 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 occurring within the mold cavity. Test A, 1.02 mm gap height (line A); Test B, 0.76 mm mold closure height (line B); and Test C, cavity strain measurements for 0.51 mm mold closure height (line C) are shown in Figure 6. In Figure 6, strain (unit extension per unit length) is plotted against time (seconds). The strain curves indicate that the pressure was higher in Test C than in Test B, and Test B was higher than Test A.

7 includes photographic images showing side, top, oblique, and bottom views of Part A, Part B, and Part C. Part A and Part B showed evidence of collapse as the parts were not sufficiently matched to the mold cavity geometry. Part A showed more collapse than Part B. Part C was more fully formed than Part A and Part B in that the edges of Part C were better defined, Part C conformed better to the mold cavity shape, and the interior of the part was more homogeneous.

It was believed that the part may partially collapse in the cavity during molding if sufficient pressure is not applied to stabilize the foam in the cavity during solidification. Therefore, in Series II, the mold was closed more tightly with a slower injection speed to maintain sufficient pressure to prevent collapse of the part during molding.

Series II

In Series II, the gap between mold halves, and the mold closure height, were systematically reduced as the injection speed was reduced. The molding conditions used were the same as in Series I except that the injection speed and mold closure height used were as shown in Table 15:

[Table 15]

In Trial A', Trial B', Trial C', and Trial D', four parts were manufactured, Part A', Part B', Part C', and Part D', respectively.

Parts A', B', C', and D' were each cut into two pieces and cross sections were photographed. A photographic image is shown in Figure 8. To produce a part that would not collapse prior to solidification, the mold halves had to be gradually closed, as shown in Table 15, until they were actually pressed together (indicated by the negative dimension).

Part A', Part B', Part C', and Part D' showed no evidence of collapse, had well-defined edges and surfaces, and exhibited considerable uniformity. Therefore, parts were manufactured using the MFIM process using drastically different injection rates by adjusting the pressure within the cavity during injection, for example by varying the mold closure height.

Example 5

In 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.

[Table 16]

[Table 17]

[Table 18]

Example 5 produced part 51 shown in FIG. 9. During injection, the molten foam melt enters through the sprue 52 and is divided into two separate channels to fill the part 51 substantially simultaneously. Therefore, the MFIM process could be used to form parts by splitting the melt into multiple passes in the mold.

Example 6

The first part was molded using a formulation of 15% talc/85% polycarbonate composite by weight blended with 3% Hydrocerol® XH-901 prior to loading into the injection molding machine. The first part was formed using the MFIM process. Method details are provided in Tables 19 and 20. The part was manufactured 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. A sprue was cut from the part, and the part was then subjected to X-ray tomography to quantify the formed cell structure within a 5.08 x 10.16 x 10.16 cm geometry.

[Table 19]

[Table 20]

X-ray tomography was performed using a Zeiss Metrotom 800 130 kV imaging system (Carl Zeiss AG, Oberkochen, Germany). The device measured the attenuation of X-ray radiation due to component geometry and density of materials used. Column data was calculated using the Feldkamp reconstruction algorithm, a standard technique in the industry. The device had a flat panel detector of 1536 x 1920 pixels for a peak resolution of 3.5 μm under the conditions of these measurements.

An isometric image of a full Zeiss 3D tomography scan of the first part is shown in Figure 10, with the solid polymer portion shown as transparent, cells shaded for visualization, and cut plane A-A for a single cross section shown. Figure 11 is a single-plane section A-A selected from X-ray data with threshold analysis applied to allow individual cell identification and subsequent quantitative analysis.

The circularity of the cross section of the cell was obtained. The circularity of this cross section was used as a measure of the sphericity of the cell. Accordingly, circularity and sphericity are used interchangeably in the examples. The quantitative analysis shown in Figure 12 revealed the distribution of cells in both count and average size as a function of the circularity of each cell. A circularity value of 0 indicates a perfectly non-spherical cell, and a value of 1 indicates a perfectly spherical cell. The data showed the distribution of cell size and shape. Except for the most deformed cells (represented at 0.1-0.2 on the circularity scale), there was an inverse relationship between the average cell size and the number of cells for a given circularity. Additionally, there was an inverse relationship between average cell size and number of cells.

Using the MFIM process, a second spherical part with a diameter of 6 inches (15.24 cm) was molded from low density polyethylene (LDPE) using the polymer formulation and process parameters as listed in Tables 21 and 22. LDPE/talc pellets were dry blended with blowing agent, Hydrocerol® BIH 70 and mixed during loading into the molding machine.

[Table 21]

[Table 22]

Figure 13 is an x-ray tomography image of a cross section of a sphere. As shown in Figure 13, the outer region contained a plethora of smaller cell sizes along with larger cells in the central region.

Figure 14 shows a plot of average cell size and average cell coefficient against average cell circularity and reveals an inverse relationship between average cell size and circularity and an inverse relationship between average cell size and number of cells.

Example 7

Using the MFIM process, 3 inch (7.62 cm) diameter LDPE composite spheres (92 wt% polymer, 5 wt% talc, and 3 wt% Hydrocerol® BIH 70) were molded, and the resulting foam cell structure is shown in Figure 15. This is detailed in Figures 18 through 18. Molding conditions are provided in Table 23. Parts were molded on an Engel Victory 340 Ton injection molding press in a custom-designed, water-cooled aluminum mold. The mold cavity volume 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). Decompression time was 77 seconds. The molded part weight was 80.31 g, resulting in a final part density of 0.32 g/cc.

[Table 23]

After removal from the mold, the parts were aged at ambient conditions for 24 hours, then scored and immersed in liquid nitrogen for 2 minutes. After removal from liquid nitrogen, the spheres were fractured along scored surface lines and the fracture surfaces were imaged using an environmental scanning electron microscope (ESEM) (FEI Quanta FEG 650). The images shown in Figures 15-18 are micrographs taken at various magnifications of the fracture surface of a spherical part using a large field detector, 5.0 kV, and a pressure of 40 Pa.

The white squares in Figure 15 represent the areas detailed in Figure 16. The white squares in Figure 16 represent the areas detailed in Figure 17.

In Figure 17, the cells on the left side of the image are larger and relatively spherical, while the cells on the right side of the photo appear progressively flatter as they approach the surface of the sphere.

The image in FIG. 18 details the area shown in white square in FIG. 17. As shown in Figure 18, moving towards the surface of the part there is a gradual transition from spherical to "flat" or compressed cells.

Example 8

To establish baseline differences between parts of standard thickness manufactured under standard foam molding conditions, a recently published study of standard foam injection molding (Paultkiewicz et al. , Cellular Polymers 39 , 3-30 (2020)) A 16-run statistical analysis was used to establish a molding parameter baseline using a designed experiments (DOE) approach. To closely mimic the baseline study, the materials (standard molding grade polypropylene with 0 wt%, 10 wt%, and 20 wt% talc; and 0 wt%, 1 wt%, and 2 wt% Hydrocerol® BIH 70 (blowing agent)) was formulated to the specifications listed in the literature. A study was designed to investigate the influence of blowing agent concentration, talc content, and process conditions on selected properties of injection molded foam parts. A standard ISO tensile bar mold was used with cavity dimensions of 4.1 mm thick, 10 mm wide at the gauge length, and 170 mm long. Special venting for ISO bar molds has not been developed. After ensuring that the injection molding machine, material formulation, and process window could reproduce the results published by Paultkiewicz et al., setting the pressure and holding time (important variables in the published study) to constant values of 0 kN and 0 s, respectively. , a second study was performed using process variables specific to MFIM, particularly decompression volume and decompression time.

Molding was completed using an Engel Victory 340 Ton machine equipped with water cooling. The constant and variable process conditions used are shown in Table 24 for both the “standard” foam molding process and the MFIM molding process.

[Table 24]

The designed study required 16 combinations of process conditions/polymer formulations (16 runs) for each of the standard molding and MFIM molding studies. Multiple iterations of each run were performed to create duplicate parts for each run. Table 25 lists run-to-run changes for both standard and MFIM designed runs. Runs were performed randomly to avoid bias. The L/T ratio for ISO tensile bars is 40.5.

[Table 25]

Five samples per series were mechanically tested for tensile strength and fracture surface imaged after fracture after forming of 32 unique process combinations in two 16-run DOE studies. A representative selection of ISO bar cross sections from runs 10, run 11, run 14, and run 15 of the standard foam molding process are shown in Figure 19, and ISO bars from runs 9, run 10, run 15, and run 16 of the MFIM process. A representative selection of cross sections is shown in Figure 20.

The differences between the standard foam molding technique adopted from recent literature and the MFIM process are evident when examining the cross-sectional images. The structure in a standard process bar consists of relatively few but well-defined, spherical cells flanked on all sides by thick regions of polymer devoid of cells. The cross-sectional images obtained from the standard foam molding process are in good agreement with those in the literature by Paultkiewicz et al. and are representative of current industry standards. In contrast, a typical cross section of an MFIM molded ISO bar shows a cell structure with more asymmetric, deformed cells.

In the MFIM cross-section the cells also progress to the area adjacent to the surface in almost all cases and are thinner, similar to previous examples described herein, but with a L/T ratio (40.5) that is nonetheless larger than previously described. It's a part. The results clearly show that the adoption of a decompression step in MFIM, in combination with eliminating the standard foam molding process variables of holding pressure and time, results in significantly different cell structures in the molded parts.

Tensile testing of five replica parts from MFIM Run 9 was performed. Figure 21 shows representative cross sections and a series of stress/strain plots for five parts tested from MFIM Run 9.

Tensile testing was performed on five replica parts from Run 10 manufactured using a standard foam molding process. Figure 22 shows representative cross sections and a series of stress/strain plots for five parts tested from standard foam process run 10.

The average tensile strength of the five parts from MFIM run 9 was less than the average tensile strength of the five parts from standard foam molding process run 10. However, the MFIM part exhibited greater strain (elongation) at fracture.

More cells were visible in the cross section of the MFIM part from run 9 (102 cells) than in the standard foam molding process part from run 10 (19 cells).

X-ray tomography scans of randomly selected replica parts from run 15 of the standard foam molding process (shown in Figure 23) and randomly selected replica parts manufactured during run 9 of the MFIM process (shown in Figure 24) (Example 5 completed under the conditions described in). Figures 23 and 24 both show a “top” view taken at 50% depth and also a “side” view taken at 50% depth.

In the expanded cell structure of the standard foam molding process ISO bar (Figure 23), the cells were circular in shape and the area adjacent to the surface of the bar lacked cells.

In contrast, ISO bars manufactured via the MFIM process shown in Figure 24 contain a high population of elongated cells, with the cells found in areas adjacent to the surface of the part.

Example 9

To investigate the dependence of the final cell structure on the MFIM process conditions, eight tensile bars of LDPE were molded using the MFIM process on an Engel Victory 340 Ton injection molding machine. The mold contains an aluminum material modified tensile bar cavity with dimensions of variable width, with a gauge length of 6 cm and a gauge width of 2.54 cm, tapering to a flange of 24 cm long, 2.54 cm thick, and 3.5 cm wide. included. Large tension bars were fed from a cold sprue and runner system through a gate with a diameter of 1.0 cm. The material formulation consisted of LDPE with or without talc, always containing 2% by weight of the blowing agent Clariant Hydrocerol® BIH 70. The melt temperature was set to the profile detailed in Table 26 and the residence time in the barrel was 13 minutes prior to construction of the shot for injection. After construction of the shot, the screw was retracted to provide a reduced pressure volume of 4.0 cubic inches (66 cc) or 6.0 cubic inches (98 cc) and the LDPE foam mixture was allowed to foam into the empty barrel space prior to injection for 15 or 45 seconds. did. Studies were completed on both unfilled LDPE and 15% talc filled LDPE. Detailed process conditions are shown in Table 26.

[Table 26]

Figure 25 shows an X-ray scan of one of the parts from this study, showing the overall geometry of each part.

Figure 26 shows a cross-section of each of the test bars formed in the study, cut from the middle of the gauge length, with variable parameters indicated. The sample set includes two basic groups: samples prepared with talc and samples prepared without talc. In Figure 26, the sample set on the left shows parts manufactured without talc. These parts exhibit a smaller cell structure in the core of the part, and the integrity of the resulting cell structure is not significantly affected by changes in decompression rate and decompression time, indicating that both decompression rate and time are within acceptable ranges.

The sample set on the right shows a bar containing 15% talc by weight. Some smearing on the part surface resulted from knife damage to the low-modulus LDPE and is not representative of part quality. The cell structure was consistently larger in the talc parts, and the circularity of the cells was slightly lower than that of the talc-free equivalents.

^An The image is shown in Figure 27.

Example 10

Tensile bar parts were made using a standard foam molding process from LDPE loaded with 15 wt% talc, and 2 wt% Hydrocerol® BIH 70, using the process parameters described for Example 9, but without the pressure reduction step of the MFIM process. Manufactured. This standard foam molded part was compared to the MFIM part made with 15% talc from Example 9, 6 in ³ (98 cc) reduced pressure volume, and 15 seconds reduced pressure time. Using the method described in Example 6, X-ray tomography images of the central portion of each part (MFIM molded and standard foam molded) were taken at various depths from the major surfaces. Cross-sectional images were also recorded. The image is shown in Figure 28.

Perform X-ray tomographic analysis of cell count, cell circularity, and average cell size (longest dimension of the cell) on images of each tensile bar component (MFIM and standard method materials) at each depth from the major surface. did. Cell count, cell circularity, and average cell size were each plotted against depth of section; Each plot is shown in Figures 29 to 31, respectively.

As shown in Figure 29, cell counts were higher in MFIM molded parts at all depths. As shown throughout the examples and figures, parts molded using standard foam molding processes have no or substantially no cells in the area or “skin” adjacent to the surface, e.g., at a depth of approximately the first 2.5 mm from the major surface. On the other hand, cells exist in the area between the surface and approximately 2.5 mm below the surface in parts molded using the MFIM process.

As shown in Figure 30, cell circularity was generally greater in the standard foam molding process samples than in the MFIM-molded parts, except for the middle of the MFIM part where circularity was also higher in the MFIM molded samples.

As shown in Figure 31, cell size was generally larger for standard foam molded tensile bar parts, but rapidly dropped to zero in areas close to the outer surface (e.g., within 2.5 mm of the surface). In contrast, the cell size was more uniform through the depth of the MFIM-molded part, and the cells continued all the way to the surface.

The same trend appears by visual inspection of the cross section shown in Figure 28. Within 2.5 mm of any external surface, standard foam molded parts appear to lack cells, whereas cells are visible all the way to the external surface in MFIM parts.

Example 11

A large sample of recovered marine plastic was analyzed using differential scanning calorimetry and estimated to consist of approximately 85% HDPE by weight, with the remainder containing polypropylene and contaminants.

Two parts were successfully molded from marine plastic using the MFIM process, 4"x4"x2" bricks and 15.24 cm diameter spheres on an Engel Duo 550 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). Molding was performed using . Both parts had a central gate and were filled by a viscous coil-folding flow.

Process parameters and characteristics of the produced parts are listed in Table 27 and Table 28, respectively:

[Table 27]

[Table 28]

Example 12

A sphere with a diameter of 9 inches (22.86 cm), “Sample 10,” was molded using the MFIM process described herein. Additionally, a second sphere, sample 20, measuring 9 inches (22.86 cm) in diameter, was molded using a modified method. The modified method, referred to herein as the “reverse MFIM” method, was as follows:

A) The mixture is prepared by combining the polymer (which can be in the form of pellets, powders, beads, granules, etc.) with a chemical blowing agent and any other additives such as fillers. The mixture was introduced into the injection machine and the rotating injection machine screw moved the material forward in the injection molding machine barrel, thereby forming a heated fluid mass according to the typical injection molding process. B) The screw was moved back toward the hopper, creating an intentional space between the screw and the nozzle in the barrel. C) A set volume of material is dosed in front of the barrel of the injection device by rotation of the screw, moving the set volume from the feed compartment to the front of the screw and into the intentional space created in step B. During this feeding phase, the screw is rotated to move the molten material into the space within the barrel between the screw and the nozzle to provide a set volume. However, the set volume occupied only a portion of the intended space, providing a volume for the shot to foam and expand, a decompression volume. D) Material remains in the barrel between the screw and the nozzle for a period of time, referred to herein as “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 movement of the screw and/or rotation of the screw.

Thus the normal and reverse MFIM processes are: In the MFIM process, the screw is rotated to introduce the shot to the front of the barrel and then the screw is moved back to allow space for decompression; The reverse method differed in that the screw was moved back to allow for a depressurized space and then the screw was rotated to introduce a shot of material into the intentionally created space.

Samples 10 and 20 were both molded from virgin LDPE containing 2% Hydrocerol® BIH 70, 2% talc, and 1% yellow colorant. Molding was performed on an Engel Duo 550 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). The mold was a spherical cavity within an aluminum mold supplied by cooling runners and sprues.

Process parameters are shown in Table 29:

[Table 29]

The density of both parts, Sample 10 and Sample 20, was 0.214 g/cc with a density reduction of 77% in all cases.

A photograph of sample 20 is shown in Figure 32 and a photograph of sample 10 is shown in Figure 33, with each spherical component mounted on a stand. As can be seen in the figure, sample 20 made using the “reverse MFIM process” exhibited a non-uniform surface, whereas the surface of sample 10 made using the MFIM process was much more uniform. The average wrinkle depth was estimated using light microscopy and X-ray tomography. The average wrinkle depth was measured to be less than 50 microns for sample 10, but 565 microns for sample 20.

Samples 10 and 20 were each cut in half to provide cross-sections at their maximum diameter. Cross sections of four pieces were photographed. One half of sample 20 prepared by the inverse MFIM method is shown in FIG. 34 and one half of sample 10 is shown in FIG. 35. Rigorous examination of the edges showed that, unlike parts manufactured elsewhere in the examples by standard foam methods, in Samples 10 and 20 the cells were found all the way to the surface, for example within 2.5 mm of the surface.

X-ray tomography was performed on the first inch of sample depth for Samples 10 and 20, and using the method described in Example 6, cell counts and cell sizes were determined for different distances from the surface of each sample. Measured. The plots are given in Figures 36 and 37, where "MFIM" represents sample 10 and "inverse MFIM" represents sample 20.

Two additional sphere parts, part 6 and part 7, were prepared under the same conditions as sample 10 and with the same polymer/talc/colorant/blowing agent mix, i.e. by the MFIM method. Five cuboid parts, each measuring approximately 2 inches by 2 inches by 1 inch, were cut from each of Part 6 and Part 7, and tested for compression modulus (stress versus strain). Mean stress versus mean strain (MFIM method) was plotted and shown in Figure 38.

Two additional sphere parts, Part 22 and Part 24, were prepared under the same conditions as Sample 20 and with the same polymer/talc/colorant/blowing agent mix. Five cuboid parts, each measuring approximately 2 inches by 2 inches by 1 inch (approximately 5.1 cm by 5.1 cm by 5.1 cm), were cut from each of Part 22 and Part 24, and tested for compression modulus (stress versus strain). The average stress versus average strain (inverse MFIM method) was plotted and also shown in Figure 38. As shown in Figure 38, the compression coefficients of parts manufactured by the MFIM process (average of Parts 6 and 7) and parts manufactured by the reverse MFIM process (average of Parts 22 and 24) are similar.

Five strips were cut each from Part 6 and Part 7 (MFIM) and Part 22 and Part 24 (Reverse MFIM). Each strip was approximately 1 inch x 1 inch x 8 inches. The bending modulus (stress versus strain) was tested for both strips, and the results were averaged for 10 MFIM-manufactured strips and the results were averaged for 10 reverse MFIM streams. The results are plotted in Figure 39.

Example 13

Parts of various shapes and materials as shown in Table 30 were fabricated using the MFIM method described herein. The part was sectioned. In all cases, areas close to the surface contained cells of smaller size, but as one moved away from the surface, cell size increased. Regions of reduced cell size closer to the surface transitioned to larger cell sizes further away from the surface. Although the transition was gradual, so that there were no distinct layers of the smaller size and no distinct layers of the larger size, the relative zones of the areas of the smaller or "squeezed" cells and the areas of the larger cells were estimated visually using a microscope. Confirmed by light microscopy and shown in Table 30. Although the numbers are only estimates, examination of the images indicated that the depth of region and percentage area occupied by "squeezed" cells varied greatly, possibly depending on part geometry, material, and/or run conditions.

[Table 30]

Example 14

The first part was molded using a formulation of 98% by weight metallocene polyethylene blended with 2% by weight Hydrocerol® BIH 70 prior to loading into the injection molding machine. The first part was formed using the MFIM process. Method details are provided in Table 31 and Table 32. Parts were manufactured using a 2"x4"x4" block mold (5.08 Load testing was applied to quantify the compressive strength properties of cellular structures formed within a 2"x4"x4" geometry.

[Table 31]

[Table 32]

Compression tests were performed on an Instron Universal Testing System (Instron USA, Norwood, MA). Each molded foam block was placed between test platens and stabilized in an environmental chamber at 30° C. for 5 minutes prior to testing. The device was equipped with a 250 kN load cell. The compression test speed was 5 mm/min.

The results showed that the compression modulus was 19 MPa for sample A (0.37 g/cc), 39 MPa for sample B (0.45 g/cc), and 55 MPa for sample C (0.57 g/cc). As shown in Figure 40, the compressive strength of metallocene polyethylene (mPE) blocks increases with increasing density.

Example 15

Two sample parts, Part 87 and Part 111, were foam molded using a blend of low density polyethylene with 2.5% by weight Hydrocerol® BIH 70 blowing agent (Clariant AG, Mutents, Switzerland). Molding was performed using an Engel Victory 160 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). The mold contains a cylindrical cavity with a diameter of 6.35 cm and a height of 5.715 cm, with a total volume of 180.33 cm3. An aluminum mold with a cooled sprue and runner system supplying the cylindrical shape described was used for both parts. The melt delivery system for each part was identical, and the only difference in process settings between the two parts was the reduced pressure volume.

The process settings used to create each part are detailed in Table 33. The first part (part 87) was molded using the MFIM process with a calculated decompression time of 10 seconds and a decompression volume of 65.55 cc. The second part (part 111) was molded under the same conditions, but like part 87, while a 10 second period was allowed for depressurization, the screw was not moved back to allow for depressurization volume. Therefore, the decompression volume was 0 cc.

[Table 33]

Both part 87 and part 111 were photographed. Figure 42 is a photographic image of part 111 molded without using a decompression step. As shown in the image, the method without the decompression step did not yield a part that filled the mold cavity, and the part did not match the shape of the mold's cylindrical cavity.

Figure 43 is a photographic image of Part 87 molded using a reduced pressure volume of 69.55 cc. As shown in the image, the molding process using a reduced pressure volume of 69.55 cc yielded a part that completely or substantially filled the cylindrical mold cavity, and the part matched or substantially matched the shape of the cylindrical cavity of the mold.

During the molding process used to manufacture Parts 87 and 111, the hydraulic ram pressure in front of the screw (i.e. between the screw and the nozzle) and the barrel volume were taken readings from the injection molding machine. Hydraulic ram pressure was recorded as a function of barrel volume as the injection progressed.

The injection pressure (or specific injection pressure) was calculated as the measured pressure of the ram times the mechanical reinforcement ratio, which is 7.222 for the Engle Victory 160 Ton. Reinforcement ratio is a geometric factor for calculating the pressure amplification due to the geometric difference between the tip of the injection molding screw and the hydraulic ram at the molten polymer interface. Injection pressure was plotted against barrel volume as shown in Figure 44 for the molding process of both Part 111 and Part 87.

Referring to the plot for part 111 in Figure 44, as expected, the instantaneous pressure when the barrel volume between the nozzle and the screw (i.e., in front of the screw) is reduced below the shot volume of about 53 cc as the screw moves toward the nozzle. an increase was observed. 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.

Considering part 87, 53.3 cc of shot was manufactured, then 65.5 cc of decompression volume was added to the shot for a total possible shot volume of 118.8 cm3. Referring to the plot for part 87, as the screw moves toward the nozzle, the pressure first begins to rise when the barrel volume in front of the screw is approximately 90 cc. The barrel volume then slowly rises until just above approximately 70 cc, when the pressure begins to rise rapidly, and after the barrel volume decreases below 53 cc, equilibrium pressure is reached. The pressure/volume profile for the molding process of part 87 was very different than that for the molding process of part 111. In particular, the rapid pressure rise onset for part 87 (at a barrel volume of approximately 73 cc) was larger in volume than the rapid pressure rise onset for part 111 (at approximately 53 cc). The difference between these “starting volumes” suggests that the shot volume for part 87 before being injected into the mold is larger due to expansion of the shot by foaming into a depressurized volume in the barrel. Accordingly, the additional volume is labeled “barrel foam” to reflect this possibility.

Example 16

Two spherical foam molded parts, Part 16A and Part 16B, were separately manufactured using the MFIM process from a mixture of virgin low-density polyethylene (85 parts by weight) and talc (15 parts by weight), respectively. Parts 16A and 16B were each cut into two pieces through the middle (widest part) to expose a cross-section of the parts, and the cross-sections were photographed.

Two additional parts, Part 16C and Part 16D, were prepared using the MFIM process from a mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight). However, parts 16C and 16D were manufactured using reduced clamp force compared to the method used to manufacture parts 16A and 16B. Parts 16C and 16D were each cut into two pieces through the middle (widest part) to expose the cross-section of the parts, and the cross-sections were photographed.

An additional part, part 16E, was manufactured using the MFIM process from a mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight). Part 16E differed from Parts 16A and 16B in that it utilized a different decompression ratio (ratio between shot volume and decompression volume). Part 16E was cut into two pieces through the middle (widest part) to expose a cross-section of the part, and the cross-section was photographed.

Parts 16A, 16B, 16C, 16D, and 16E were each added to a RAPID Granulator Open-Hearted 400-60 (RAPID Granulator AB, Bredarid, Sweden) and milled to produce regrind in the form of flakes. . The regrinds from each of parts 16A, 16B, 16C, 16D, and 16E were then used as feedstock for injection molding to produce new spherical foam parts 16AR, 16BR, 16CR, 16DR, and 16ER, respectively.

Each of parts 16AR, 16BR, 16CR, 16DR, and 16ER was cut into two pieces through the middle (widest part) to expose the cross-section of the parts, and the cross-sections were photographed.

The screw rotation delay time for all foam molding processes was 40 seconds. The different process settings used to create the part are detailed in Table 34. Virgin refers to a fresh mixture of virgin low density polyethylene (85 parts by weight) and talc (15 parts by weight).

[Table 34]

Figure 45 is a cross-sectional photograph of part 16A, Figure 46 is part 16AR, Figure 47 is part 16B, Figure 48 is part 16BR, Figure 49 is a cross-section of part 16C, Figure 50 is part 16CR, Figure 51 is part 16D, Figure 52 is a photograph of part 16DR, Figure 53 is a cross-sectional photograph of part 16E, and Figure 54 is a cross-sectional photograph of part 16ER. 45-54 show additional MFIM-molded parts 16A, 16B, 16C, 16D, and 16E, respectively; Collectively, this is shown to be successfully recycled into parts 16AR, 16BR, 16CR, 16DR, and 16ER, respectively.

A variety of additional products include low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), high-impact polystyrene (HIPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyamide (PA). ), were manufactured using the MFIM process from a variety of virgin thermoplastics, including thermoplastic polyurethane (TPU) and thermoplastic olefin (TPO). These additional polymer foam articles were all successfully recycled by regrinding as described in this example and by using the regrinded material as feedstock in an additional MFIM process, further as shown in Figures 45-54. Polymer foam articles made by recycling refer to those formed from recycled material feedstock. In this example, a recycled polymer foam article is successfully formed from 100% recycled material feedstock by using the MFIM process. Additionally, all of the polymer foam articles formed using the MFIM process in this example are recyclable and thus also constitute a potentially recyclable material feedstock.

Example 17

Five parts were foam molded using a blend of low density polyethylene blended with 2% by weight of Hydrocerol® BIH 70 blowing agent. Molding was performed using an Engel Duo 340 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). The mold cavity was approximately spherical in shape with a diameter of 6 inches (15.24 cm). The first part was molded using the MFIM process without decompression, the second part had a calculated decompression time of 0.5 seconds and a decompression volume of 164 cc, and the third part had a decompression time of 7 seconds and a decompression volume of 164 cc. It was. The back pressure was set at 6895 kPa, and the third method used a depressurization rate of 0.0059 GPa/sec. The fourth and fifth parts were molded with a difference of almost two orders of magnitude in the depressurization rates used.

Aluminum molds with a cooled sprue and runner system supplying 6 inch diameter sphere cavities were used for all five parts. The melt delivery system for each part was identical, as were most process conditions. The process settings used to create each part are detailed in Table 35.

[Table 35]

Each of the five parts was photographed. Figure 55 is a photographic image of a part molded without using decompression. As shown in the image, the method without decompression did not yield a part that filled the mold cavity, and the part did not match the shape of the mold's spherical cavity.

Figure 56 is a photographic image of a second part molded using a depressurization time of 0.5 seconds after applying a depressurization rate of 0.0059 GPa/sec. As shown in the image, the molding process using a 0.5 second decompression time yielded a part that completely or substantially filled the spherical mold cavity, and the part matched or substantially matched the shape of the spherical cavity of the mold.

Figure 57 is a photographic image of the third part formed using a depressurization time of 7 seconds after applying a depressurization rate of 0.0059 GPa/sec. As shown in the image, the molding process using a 7 second decompression time yielded a part that completely or substantially filled the spherical mold cavity, and the part matched or substantially matched the shape of the spherical cavity of the mold.

Figure 68 is a photographic image of the fourth part formed using a depressurization time of 10 seconds after applying a depressurization rate of 0.0009 GPa/sec. As shown 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, even though the part substantially conformed to the spherical shape of the mold.

Figure 69 is a photographic image of the fifth part molded using a depressurization rate of 0.0629 GPa/sec. As shown in the image, the molding process using the described 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.

Example 18

Two parts were foam molded using a blend of low density polyethylene blended with 2% by weight of Hydrocerol® BIH 70 blowing agent (Clariant AG, Mutents, Switzerland). Molding was performed using an Engel Duo 340 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). The mold cavity was approximately spherical in shape with a diameter of 6 inches (15.24 cm). The first part was molded using the MFIM process with a back pressure of 100 psi (689 kPa) and a depressurization rate of 1 cubic inch per second (16.4 cc/s). Back pressure can be set by the operator. The rate of decompression is determined by the speed of lateral movement of the screw away from the collection area of the injection molding machine, which can be set by the operator. The second part was molded using a back pressure of 1000 psi (6895 kPa) and a depressurization rate of 16 cubic inches per second (292 cc/secs). An aluminum mold with a cooling sprue and runner system supplying a 6 inch diameter sphere cavity was used for both parts. The melt delivery system for each part was identical, as were most process conditions. The process settings used to create each part are detailed in Table 36.

[Table 36]

Each of the two parts was photographed. Figure 58 is a photographic image of Part 1 molded using a back pressure of 689 kPa and a decompression rate of 16.4 cc/sec. As shown in the image, this molding process did not yield a part that substantially filled the mold cavity, and the part did not match the shape of the mold's spherical cavity.

Figure 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. As shown in the image, the molding process using a rapid depressurization rate of 292 cc/sec combined with a back pressure of 1000 psi (6895 kPa) yielded a part that completely or substantially filled the spherical mold cavity, with the part remaining in the mold. It matched or substantially matched the shape of the spherical cavity.

Example 19

A mixture of 98.5 parts by weight of post-industrial polypropylene in granular form and 1.5 parts by weight of blowing agent (Hydrocerol® BIH 70, Clariant AG, Muttenz, Switzerland) was mixed into a 2.25 x 3.875 x 8 inch (5.7 x 9.8 x 20.3) cm) and foam molded using the MFIM process using a mold cavity to produce a 2.25 x 3.875 x 8 inch (5.7 x 9.8 x 20.3 cm) brick. Three of these individual foam molding processes, 19-1D, 19-3D, and 19-5D, were performed to produce three polymer foam bricks.

Processes 19-1D, 19-3D, and 19-5D were performed in the same manner using most of the same processing conditions except for the number of decompression steps. Additionally, shot cooling time prior to decompression was adjusted to maintain the same shot residence time in the barrel for all three runs: with multiple decompression steps, the cycle residence time of the shot in the barrel will be longer during a greater number of decompression steps. You can. Additionally, the shot volume for each run produced three bricks of similar weight to each other as possible.

Process 19-1D is an MFIM process with one depressurization step, in which a shot is introduced in front of the barrel (between the nozzle and the screw), held for a cooling adjustment period, and then the screw is moved backwards (away from the nozzle) for 10 seconds. The decompression volume was provided for (decompression time). Immediately after the depressurization step, the screw was moved forward (towards the nozzle) to inject the shot into the mold.

The screw is moved backwards from the pre-translation position and then forward to the pre-translation position to provide a decompression volume for 10 seconds (decompression time); It is then moved back a second time to provide decompression volume for another 10 second decompression time, and then moved forward to the pre-move position; Process 19-3D was then carried out in a similar manner except that it was moved back a third time and held for a 10 second decompression period before injection. Accordingly, Run 19-3D had three decompression steps instead of the single decompression step of Run 19-1D.

Run 19-5D was performed in a similar manner to Run 19-3D except that five 10-second decompression steps were performed.

By executing several runs of each process, brick parts were created for each process type. Parameters for the three process types are shown in Table 37:

[Table 37]

Bricks of each process type were cut into two halves measuring 1 x 4 x 8 inches (2.5 x 10.2 x 20.3 cm), and each 4 inch x 8 inch section was photographed. The photograph is shown in Figure 60. Parts molded using five decompression steps showed larger voids near the area where the melt entered the cavity.

In addition, the surface side of each cross-section brick was photographed at 12x magnification. The image shows a cross-section of each molded brick, with the original outer surface and edges also visible. The photograph is shown in Figure 61. Each brick exhibited cells within 500 micrometers of the surface.

Half of the bricks from each process type were subjected to compression testing. Compression testing was performed on an Instron Universal Testing System (Instron USA, Norwood, MA) using a modified ASTM D1621 standard test. Each molded foam block was placed between test platens and stabilized in an environmental chamber at 30° C. for 5 minutes prior to testing. The device was equipped with a 250 kN load cell. The compression test speed was 5 mm/min.

A plot of compressive strength versus compressive strain for bricks for each process type is shown in Figure 62. Bricks produced by all three processes had similar ultimate compressive strengths of approximately 5.2 MPa. The bricks tested for the five 19-5D processes were noted to have large voids near the gates.

Half of the bricks from each process type were subjected to impact testing using an Instron Drop Tower (Instron USA, Norwood, MA, USA). Parts for each process type were tested three times along the center of the part for average maximum force and energy readings. The test results for force at peak are shown in Figure 63 and energy at peak are shown in Figure 64. The maximum force recorded for all three process types was similar, with an average of 3228 N. The maximum energy recorded for all three process types was also very similar, with an average of 6.2 J.

In general, no significant differences were observed in compressive strength, impact force, and impact energy for parts resulting from processes involving only one compression step, only three compression steps, and only five compression steps. Mechanical properties were very similar, and all three process types produced parts with cells within 500 microns of the part surface.

Example 20

The goal of this example was to manufacture a part with a higher porosity than previously manufactured using the MFIM process. Two parts were manufactured; Foam molded spheres with a diameter of 8.25 cm made of SURLYN™ ionomer (Dow Chemical Company, Midland, MI, USA) containing 4% by weight Hydrocerol® BIH 70 blowing agent (Clariant AG, Mutents, Switzerland), and BIH 70 blowing agent. A foam molded sphere about 6 inches (about 15.2 cm) in diameter of a blend of 90 parts by weight low density polyethylene and 10 parts by weight high density polyethylene comprising 3% by weight.

Processing parameters were adjusted to achieve high porosity. The processing parameters used to mold SURLYN spheres into 7.62 cm diameter sphere cavities by the MFIM process are shown in Table 38, and the processing parameters for 15.24 cm diameter polyethylene spheres are shown in Table 39. It is noted that the SURLYN spheres are solidified and removed from the mold, and expand further during cooling, resulting in spheres larger than the cavities used to mold the spheres.

[Table 38]

[Table 39]

Each part was cut into two halves, and the cross sections were colored using a black marker pen. The cross section was photographed. A 25x magnified image of the cross-section near the surface was then generated.

A photograph and enlarged image of the SURLYN sphere are shown in Figure 65.

A photograph and enlarged image of the polyethylene spheres are shown in Figure 66.

The images confirmed the cellular structure across a cross section encompassing within 500 microns of the sphere surface.

Each sphere was weighed and the porosity was calculated as follows: Density of the foamed part ( ) is written in Equation 1 below:

Equation 1,

In the above equation, M is the mass of the foamed part and V is the volume of the foamed part.

The porosity equation is given in Equation 2 below:

Equation 2,

In the above equation, is the density of the material.

Part density and porosity data are listed in Table 40:

[Table 40]

Example 21

The purpose of this example was to demonstrate that articles can be manufactured by the MFIM process with the mold only partially filled.

Two flowerpots were molded from low-density polyethylene (containing 1.5% by weight of Hydrocerol® BIH 70 blowing agent from Clariant AG, Mutents, Switzerland) using the MFIM process by foam injection in a mold with a mold cavity of 10860.20 cc in volume. . Run SF manufactured the flower pots by filling, or substantially filling, the mold cavity. A second run-in, Run PF, was performed with a lower shot volume and lower depressurization volume to only partially fill the mold cavity and produce a partially filled part.

MFIM mold parameters were identical for both runs except for shot volume and depressurization volume. The parameters (settings) for both runs are shown in Table 41:

[Table 41]

The volumes of both planter parts were measured using a three-dimensional scanning arm, the FARO® Quantum ScanArm (FARO, Lake Mary, FL). The resulting part volumes are shown in Table 41. The two parts are shown in FIG. 67 with the run SF part on the left and the run PF part on the right. The results of this example show that partially filled molds can produce parts by the MFIM process. The volume of the part from the partially filled mold was approximately half that of the part manufactured from the substantially filled mold, but it still had the important characteristics of a flowerpot, namely, the part had structural integrity and was free of holes.

Example 22

Sixty blocks were made from high impact polystyrene with 0.376% by weight Hydrocerol® BIH 70 blowing agent (Clariant AG, Muttenz, Switzerland) using the MFIM process. Each block was rectangular in shape and had dimensions of approximately 20 cm x 20 cm x 40 cm. The processing parameters used for block manufacturing are shown in Table 42:

[Table 42]

Hot sprue and runner systems supplied to the mold: The temperatures of the hot sprue and runner systems are shown in Table 43.

[Table 43]

The actual block dimensions averaged over 60 blocks were 20.005 ± 0.114 cm x 19.964 ± 0.659 cm x 40.066 ± 0.061 cm.

Three of the 60 blocks were taken: block 45, block 27, and block 60. Each block was cut into 16 sub-blocks, stacked and photographed to reveal the block's foam structure in cross-section. A photograph of the sub-block of block 45 is shown in Figure 70, the sub-block of block 27 in Figure 71, and the sub-block of block 60 in Figure 72.

A photograph of a fort made from MFIM foam blocks is shown in Figure 73.

A cinder block with three channels was also made from high-impact polystyrene.

Other materials that have been successfully used to make cinder blocks include polypropylene, polypropylene filled with 20% glass fiber by weight, and recycled polypropylene.

Other materials that have been successfully used to make solid blocks include polypropylene filled with 20% glass fiber by weight and polypropylene filled with 10% glass fiber by weight.

Example 23

In this example, blocks were manufactured from post-industrial reground polypropylene using the MFIM process.

Post industrial regrind (P.I.R.) in flake form was obtained from Engineered Plastics LLC, Erie, Pennsylvania, USA. The P.I.R. had a melt index of 8 to 12 and was of mixed color. P.I.R. The flakes were made from scrap laundry detergent caps and other scrap polypropylene items.

The flakes were combined with 2% by weight of green olefin color and then pelletized (reground) using a two-screw extruder.

Four plastic compositions were prepared with 0%, 25%, 50% and 100% by weight of pelletized P.I.R., 2% by weight of Hydrocerol® BIH 70 blowing agent, and the balance virgin polypropylene.

Bricks were molded using each of the four compositions on an Engel Duo 340 Ton injection molding machine (Engel Machinery Inc., York, PA, USA) using a mold with a cuboid cavity measuring 5.715 cm x 9.842 cm x 20.32 cm. A total of 60 bricks were molded from polypropylene made with 100% P.I.R. by weight.

Process parameters for the MFIM process are shown in Table 44.

[Table 44]

Four bricks (made from each composition) were cut to reveal the foam structure and cross-section of the bricks. Four cross-sections were taken and photographs are shown in Figure 74, along with enlarged views of the cross-section of a brick made of 100% virgin polypropylene and a cross-section of a brick made of 100% P.I.R. The average inner cell size is P.I.R. It was found to increase as the content increased.

Example 24

Two parts were foam molded using a blend of low density polyethylene blended with 2.5% by weight of Hydrocerol® BIH 70 blowing agent (Clariant AG, Mutents, Switzerland). Molding was performed using an Engel Victory 160 Ton injection molding machine (Engel Machinery Inc., York, PA, USA). The mold contains a cylindrical cavity with a diameter of 6.35 cm and a height of 5.717 cm, with a total volume of 180.33 cm ³ . An aluminum mold with a cooled sprue and runner system supplying the cylindrical shape described was used for both parts. The melt delivery system for each part was identical, and the only difference in process settings between the two parts was the depressurization time.

The process settings used to create each part are detailed in Table 45. The first part (part 119) was molded using the MFIM process with a calculated decompression time of 1800 seconds and a decompression volume of 14.75 cc. The second part (part 120) was molded using the MFIM process with a calculated decompression time of 0 seconds. The screw was not moved back to allow for depressurized volume. Therefore, the decompression volume was 0 cc.

[Table 45]

Part 119, formed using a molding process with a reduced pressure volume of 14.75 cc and a reduced pressure time of 1800 seconds, was fully filled, and the shape of the part matched the mold cavity shape.

Part 120, formed using a process without decompression time, did not yield a part that filled the mold cavity. The part was dented around the molded flat part of the cylindrical shape, and the part did not conform to the cavity shape of the mold.

Claims (24)

A polymer foam article having a continuous thermoplastic polymer matrix defining a plurality of pneumatoceles throughout the article, wherein a sphere with a diameter of 20 cm is additionally positioned at at least one location within the article without protruding from the surface of the article ( fit), furthermore wherein the article has a total volume of at least 2000 cm ³ . 2. The polymer foam article of claim 1, wherein the surface area extending 500 microns from the surface of the article comprises compressed pneumatocytes throughout. 3. The polymer foam article of claim 2, further comprising compressed pneumatocytes greater than 500 microns from the surface of the article. 4. The polymeric foam article of any preceding claim, further comprising at least one location where the spheres with a diameter of 2 cm protrude from the surface of the article without being contained within the polymeric foam article. 5. The polymer foam article according to any one of claims 1 to 4, having a total volume of between 2000 cm ³ and 5000 cm ³ . 5. The polymer foam article according to any one of claims 1 to 4, having a total volume of greater than 5000 cm ³ . 7. The polymer foam article of any one of claims 1 to 6, wherein the plurality of spheres having a diameter of 2 cm fit within the article without protruding from the surface of the article. 8. The polymer foam article according to any one of claims 1 to 7, wherein the two spheres, each 20 cm in diameter, fit within the article without protruding from the surface of the article. 8. The polymer foam article according to any one of claims 1 to 4, 6 or 7, wherein the three spheres, each 20 cm in diameter, fit within the article without protruding from the surface of the article. 10. The method according to any one of claims 1 to 9, wherein the thermoplastic polymer is polyolefin, polyamide, polyimide, polyester, polycarbonate, poly(lactic acid), acrylonitrile-butadiene-styrene copolymer, polystyrene, Polyurethane, polyvinyl chloride, copolymers of tetrafluoroethylene, polyethersulfone, polyacetal, polyaramid, polyphenylene oxide, polybutylene, polybutadiene, polyacrylates and methacrylates, ionomer polymers, polyether- Amide block copolymer, polyaryletherchitone, polysulfone, polyphenylene sulfide, polyamide-imide copolymer, poly(butylene succinate), cellulosic, or polysaccharide, or any copolymer thereof, A polymer foam article selected from an alloy, mixture, or blend. 10. The polymer foam article of any one of claims 1 to 9, wherein the continuous polymer matrix comprises a polyolefin, a polyamide, an ionically functionalized olefin copolymer, or a polyether-amide block copolymer. 12. The polymer foam according to any one of claims 1 to 11, wherein the continuous polymer matrix further comprises one or more additional substances selected from colorants, stabilizers, brighteners, nucleating agents, fibers, particulates, and fillers. article. 12. The polymer foam article of any one of claims 1 to 11, wherein the continuous polymer matrix further comprises talc, a colorant, or both talc and a colorant. 14. The method of any one of claims 1 to 13, comprising a reduction in density of 30% to 85% based on the mass of the pneumatocel, pneumatogen, or identical polymer article excluding the pneumatogen source. , a polymer foam article. 15. The polymer foam article of any one of claims 1 to 14, comprising a porosity of 70% to 85%. A method of forming a molten polymer foam comprising:
heating and mixing a thermoplastic polymer and a pneumatic source to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the temperature at which the pneumatogen source produces pneumatogen at atmospheric pressure, and the molten pneumatic mixture is heated and mixed to form a molten pneumatic mixture. The pressure applied to the pneumatic mixture is sufficient to substantially prevent the formation of pneumatic cells;
collecting a selected amount of molten pneumatic mixture in a collection area;
defining an expansion volume in a collection area proximate to the molten pneumatic mixture causing a pressure drop at a rate between 0.01 GPa/s and 5 GPa/s; and
A method comprising dispensing molten polymer foam from a collection area. 17. Method according to claim 16, wherein the method is carried out using an injection molding machine and further the back pressure is set between 500 kPa and 25 MPa. 18. The method of claim 16 or 17 further comprising allowing 0 to 5 seconds to elapse after the confining step and before the dispensing step, wherein the molten pneumatic mixture remains substantially undisturbed in the collection zone. How to. 18. The method of claim 16 or 17 further comprising allowing 600 to 2000 seconds to elapse after the confining step and before the dispensing step, wherein the molten pneumatic mixture remains substantially undisturbed in the collection zone. How to. A stabilized molten polymer foam comprising:
heating and mixing a thermoplastic polymer and a pneumatic source to form a molten pneumatic mixture, wherein the temperature of the molten pneumatic mixture exceeds the temperature at which the pneumatogen source produces pneumatogen at atmospheric pressure, and the molten pneumatic mixture is heated and mixed to form a molten pneumatic mixture. The pressure applied to the pneumatic mixture is sufficient to substantially prevent the formation of pneumatic cells;
collecting a selected amount of molten pneumatic mixture in a collection area; and
Defining an expansion volume in a collection area proximate to the molten pneumatic mixture causing a pressure drop at a rate of 0.01 GPa/s to 5 GPa/s to form a stabilized molten polymer foam. , stabilized molten polymer foam. 21. The stabilized molten polymer foam of claim 20, further wherein the back pressure during the expansion volume limiting step is between 500 kPa and 25 MPa. Use of an injection molding machine to form a stabilized molten polymer foam from a molten pneumatic mixture, comprising lowering the pressure inside the injection molding machine proximate the pneumatic mixture at a rate of 0.01 GPa/s to 5 GPa/s. , Usage. 23. Use according to claim 22, wherein the back pressure during pressure drop is further between 500 kPa and 25 MPa. Use of a stabilized molten polymer foam to form a polymer foam article having a continuous thermoplastic polymer matrix defining a plurality of pneumatocytes throughout, wherein spheres with a diameter of 20 cm do not protrude from the surface of the article. It is intended to fit into at least one location, and in addition, the goods have a total volume of more than 2000 cm ³ .