Composite foam containing enhanced macroencapsulations

Abstract

Composite foam containing enhanced macro-encapsulations. The composite foam is comprised of a polymer-infused matrix, a plurality of polymer beads or matrix cavities, and a plurality of interstitial microspheres. The polymer beads and matrix cavities have a width of 0.5 to 50 mm and are distributed throughout the infused matrix. Each of the polymer beads and matrix cavities is surrounded by a polymer-enhanced adhesive containing bead-coated microspheres, and each of the matrix cavities is partially occupied by polymer particles. The interstitial microspheres are distributed within the infused matrix intermediate the polymer beads or matrix cavities. The bead-coated microspheres have a size distribution of ± 20um or less.

Description

Technical Field

[0001] This disclosure generally relates to buoyancy materials, and more specifically, to a composite foam containing reinforced large inclusions. Background Technology

[0002] Unmanned underwater vehicles and other underwater vessels use buoyancy materials to maintain stability at different depths. Buoyancy materials are also used in seabed components such as wired observation nodes and unattended sensors to improve deployment efficiency and allow seabed components to remain submerged at specific depths.

[0003] Many subsea platforms face volume constraints due to transportation or operational requirements. These constraints reduce the available space for buoyancy materials. Therefore, buoyancy materials must be designed to fit into small, irregularly shaped pockets within the subsea platform. Consequently, a large number of uniquely shaped buoyancy components are needed to meet buoyancy requirements.

[0004] Composite foams are commonly used as buoyancy materials for various subsea platforms due to their high volumetric efficiency. In this respect, composite foams provide considerable buoyancy for a relatively small volume and can be configured to withstand hydrostatic pressures associated with the depth of the subsea platform. For example, commercially available composite foam systems can withstand hydrostatic pressures greater than 4500 psi. However, such foam systems have a relatively high density (e.g., greater than 0.40 g / cm³), which increases the operational weight of the subsea platform.

[0005] In view of the above, there is a need in the art for a buoyancy material that has relatively high hydrostatic compressive strength and relatively low density to meet the buoyancy requirements of seabed applications. Summary of the Invention

[0006] This disclosure addresses the aforementioned needs associated with buoyancy materials by providing a composite foam comprising a polymer injection matrix, a plurality of polymer beads or matrix cavities, and a plurality of interstitial microspheres. The polymer beads and matrix cavities have widths from 0.5 to 50 mm and are distributed throughout the injection matrix. Each polymer bead or matrix cavity is surrounded by a polymer-reinforced binder containing bead-covered microspheres, and each matrix cavity is partially occupied by polymer particles. The interstitial microspheres are distributed within the injection matrix between the polymer beads or matrix cavities. The size distribution of the bead-covered microspheres is ±20 μm or smaller.

[0007] A composition for composite foam is also disclosed. The composition comprises a quantity of polymer beads of one or more sizes, each polymer bead having a width of 0.5 to 50 mm. The composition also includes a polymer reinforcing adhesive configured to coat the polymer beads. Furthermore, the composition includes a quantity of bead-covered microspheres at least partially embeddable in the reinforcing adhesive, and the reinforcing adhesive is configured to be cured or solidified in a manner that produces a plurality of individual reinforcing polymer beads. The composition further includes a quantity of interstitial microspheres configured to be distributed within a powder bed of the reinforcing polymer beads. The composition also includes a polymer injection matrix configured to be injected into the powder bed of the reinforcing polymer beads and the interstitial microspheres, and the injection matrix is ​​configured to be cured or solidified in a manner that produces composite foam. The size distribution of the bead-covered microspheres is ±20 μm or smaller.

[0008] A method for manufacturing composite foam is also disclosed. The method includes coating a quantity of polymer beads with a polymer-reinforced adhesive to form an adhesive-coated polymer bead layer containing a sorted quantity of bead-covered microspheres. The method further includes allowing the reinforcing adhesive to cure or solidify in a manner that produces multiple individual reinforcing polymer beads. Furthermore, the method includes: placing a quantity of reinforcing polymer beads in a mold; and distributing a sorted quantity of interstitial microspheres among all the reinforcing polymer beads in the mold to obtain a powder layer. The method further includes: injecting the powder layer into the mold with a polymer injection matrix; and allowing the injection matrix in the powder layer to cure or solidify in the mold, thereby producing the composite foam. The polymer beads are provided in one or more sizes, each having a width of 0.5 to 50 mm. Furthermore, the size distribution of the bead-covered microspheres is ±20 μm or less.

[0009] The features, functions, and advantages discussed can be implemented independently in various versions of this disclosure or in combination with other versions, and further details can be found in the following description and figures. Attached Figure Description

[0010] This disclosure can be better understood by referring to the following detailed description taken in conjunction with the accompanying drawings, which illustrate preferred and exemplary versions but are not necessarily drawn to scale. The drawings are illustrative and are not intended to limit the specification or claims.

[0011] Figure 1 An example of an unmanned underwater vehicle that incorporates composite foam as a buoyancy material is shown. Figure 2 It is along Figure 1 The cross-sectional view of the currently disclosed composite foam is taken from line 2-2; Figure 3This is an enlarged view of a portion of a composite foam, which consists of an interstitial matrix containing multiple interstitial microspheres and also includes multiple reinforcing polymer beads (i.e., large inclusions), each of which comprises a polymer bead surrounded by a polymer reinforcing adhesive containing multiple bead-covered microspheres. Figure 4 yes Figure 3 An enlarged view of one of the reinforced polymer beads in the interstitial matrix, showing the internal structure of the polymer bead surrounded by a polymer-reinforced adhesive containing bead-covered microspheres; Figure 5 yes Figure 4 A magnified view of a portion of the reinforced polymer beads; Figure 6 This is an enlarged view of polymer beads in the form of expanded polystyrene beads; Figure 7 This is an enlarged view of an example of hollow microspheres; Figure 8 yes Figure 7 Cross-sectional view of hollow microspheres; Figure 9 It is a graph showing the isostatic compressive strength of two types of hollow glass microspheres with several different size distributions, and also shows the isostatic compressive strength of a large batch of the same two types of hollow glass microspheres; Figure 10 It is similar to Figure 3 An enlarged view of a portion of a composite foam containing multiple matrix cavities rather than polymer beads, and each matrix cavity contains polymer particles generated due to the shrinkage of the polymer beads during the curing or solidification of the injected matrix; Figure 11 yes Figure 10 An enlarged view of one of the matrix cavities in the interstitial matrix, showing the polymer particles contained therein; Figure 12 yes Figure 11 A magnified view of a portion of the stromal cavity; Figure 13 It is a table of six different composite foam components with different combinations of sieved or unsieved bead-covered microspheres and interstitial microspheres, and lists the density, hydrostatic compressive strength and depth of use for each composite foam component; Figure 14 yes Figure 13 The graph shows the relationship between hydrostatic compressive strength and density for each composite foam component listed below. Figure 15 This is a graph showing the functional relationship between water volume displacement and hydrostatic pressure during the hydrostatic compressive strength test of the composite foam sample. Figure 16 This is a flowchart of the operations included in the method of manufacturing composite foam; Figure 17 This is a schematic diagram of a certain amount of polymer beads being poured into a tilted glass. Figure 18 yes Figure 17 A magnified view of a portion of the polymer beads in a tilted glass; Figure 19 This is a schematic diagram of a polymer-reinforced adhesive being poured into a tilted glass to coat polymer beads and thus form adhesive-coated polymer beads; Figure 20 yes Figure 19 A magnified view of a portion of the adhesive-coated polymer beads; Figure 21 This is a schematic diagram of sieving a large batch of bead-covered microspheres using one of at least two mesh screens required to obtain a sorting quantity of bead-covered microspheres with the desired particle size distribution (e.g., no greater than ±20 μm). Figure 22 This is a schematic diagram showing the process of adding a sorted amount of hollow microspheres to bead-covered microspheres while rotating the glass until the aggregates of adhesive-coated polymer beads physically decompose into individual reinforcing polymer beads. Figure 23 yes Figure 22 A magnified view of a portion of the individual reinforced polymer beads; Figure 24 This is a schematic diagram of the tumbling process of reinforced polymer beads in a sealed container, where bead-covered microspheres are tumbled around the reinforced adhesive and polymer beads in a tumbler. Figure 25 yes Figure 24 A magnified view of a portion of the reinforced polymer beads; Figure 26 This is a schematic diagram of a container for reinforcing polymer beads installed in an oven to cure or solidify reinforcing adhesives; Figure 27 yes Figure 26 A magnified view of a portion of the reinforced polymer beads; Figure 28 yes Figure 27 A schematic diagram of the container when reinforced polymer beads are poured into a mold mounted on a mechanical vibrator; Figure 29 Is with Figure 21 The diagram shows a sieve for a large batch of interstitial microspheres arranged similarly. Figure 30 This is a schematic diagram of how a sorted amount of interstitial microspheres are added to reinforced polymer beads in a mold to form a powder layer; Figure 31 yes Figure 30 An enlarged view of a portion of the powder layer, showing interstitial microspheres filling the gaps between the reinforcing polymer beads; Figure 32 It is an exploded view of a mold assembly including a porous glass material configured to be placed on the top and bottom sides of the mold. Figure 33 yes Figure 32 A schematic diagram of the assembly of the mold components; Figure 34 This is a schematic diagram of a manufacturing system that includes a vacuum pump fluidly connected to the top side of a mold and a resin container fluidly connected to the bottom side of the mold and containing a gap-filling matrix. Figure 35 This is a schematic diagram of the manufacturing system during vacuum pump activation, which draws the gap-filling matrix into the bottom of the mold and injects the powder layer into the mold; Figure 36 yes Figure 35 A schematic diagram of the mold after injecting the injection matrix into the powder layer of reinforced polymer beads and the interstitial microspheres to produce a pre-cured composite foam; Figure 37 yes Figure 36 A magnified view of a portion of the composite foam in its pre-cured state; Figure 38 yes Figure 37 A schematic diagram of a mold installed in an oven for curing or solidifying a gap-filling matrix to produce composite foam and a post-cured state; Figure 39 This is a schematic diagram showing the cured composite foam after being removed from the mold; Figure 40 yes Figure 39 An enlarged view of a portion of the post-cured composite foam, showing multiple matrix cavities, each containing polymer particles generated during the curing or solidification process due to the shrinkage of polymer beads.

[0012] The accompanying drawings shown in this disclosure illustrate various aspects of the presented versions, and only the differences will be discussed in detail. Detailed Implementation

[0013] The disclosed versions will now be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, of the disclosed versions. In fact, several different versions may be provided, and these different versions should not be construed as limiting to the versions described herein. Rather, these versions are provided so that this disclosure will be exhaustive and will fully convey the scope of this disclosure to those skilled in the art.

[0014] This specification includes references to “configuration” and “(multiple) configurations”. Instances of the phrases “configuration” and “(multiple) configurations” do not necessarily refer to the same configuration. Similarly, this specification includes references to “an example” or “example”. Instances of the phrases “an example” or “example” do not necessarily refer to the same example. Specific features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.

[0015] As used herein, “comprising” is an open-ended term and, as used in the claims, does not exclude additional components, structures, or steps.

[0016] As used herein, "configured as" means that various parts or components can be described or claimed to be "configured as" to perform one or more tasks. In this context, "configured as" is used to denote a structure in which the parts or components include the structure that performs these tasks during operation. Therefore, even if the specified parts or components are not currently in operation (e.g., not enabled), it can be said that these parts or components are configured to perform tasks.

[0017] As used herein, an element or step cited in the singular and beginning with the word “a” or “one” should be understood to not necessarily exclude multiple elements or steps. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Similarly, as used herein, the term “combinations thereof” includes combinations having at least one associated listed item, wherein the combination may also include additional similar unlisted items.

[0018] As used in this article, when used with a list of items, the phrase "at least one" means that different combinations of one or more of the listed items can be used, and that only one of each item in the list may be required. In other words, "at least one" means any combination of items that can be used in the list and the number of items, but not all items in the list are required. The item can be a specific object, thing, or category.

[0019] Referring now to the accompanying drawings, which illustrate various examples of this disclosure, Figure 1 The image shows an unmanned underwater vehicle 100 comprising composite foam 102. The currently disclosed composite foam 102 has relatively high hydrostatic compressive strength and relatively low density, which enables the composite foam 102 to effectively meet requirements such as… Figure 1 This meets the buoyancy requirements of underwater applications such as the unmanned underwater vehicle 100. For example, composite foam 102 can withstand hydrostatic pressures greater than 4500 psi (i.e., operating depths greater than 7500 feet) while maintaining a pressure of less than 0.40 g / cm³. 3The density of the composite foam 102 is readily apparent. The composite foam 102 can be easily shaped into foam product 104, its shape complementing the internal bag section and / or external profile of an underwater vehicle. However, the composite foam 102 is not limited to seabed applications and can be implemented in any of a variety of ground-based, aircraft, and space-based applications.

[0020] Reference Figures 2 to 12 , Figure 2 The diagram shows a cross-sectional view of an example of composite foam 102, which consists of a polymer injection matrix 334 (i.e., resin) and a plurality of reinforcing polymer beads 324 (i.e., macrospheres) distributed throughout the injection matrix 334. Figures 3 to 5 ) or enhanced stromal cavity 326 ( Figures 10 to 12 The matrix consists of a mass of interstitial microspheres 302 distributed within the injection matrix 334 and between the reinforcing polymer beads 324 or the reinforcing matrix cavity 326. Each reinforcing polymer bead 324 consists of polymer beads 200 surrounded by a polymer reinforcing adhesive 320 (i.e., resin) containing multiple bead-covered microspheres 300. Each reinforcing matrix cavity 326 consists of a matrix cavity 206 surrounded by a polymer reinforcing adhesive 320 containing multiple bead-covered microspheres 300. The bead width 202 of each polymer bead 200 is... Figure 6 The width of each matrix cavity 206 is 207 mm, ranging from 0.5 to 50 mm. Figure 10 The diameter is 0.5 to 50 mm. The reinforcing adhesive 320 covering each polymer bead 200 or matrix cavity 206 comprises at least one layer of bead-covered microspheres 300, which are at least partially embedded in the reinforcing adhesive 320.

[0021] Figures 3 to 5 An example of a composite foam 102 is shown, which consists of an injection matrix 334 containing a plurality of reinforcing polymer beads 324 and a plurality of interstitial microspheres 302 distributed within the injection matrix 334 between the reinforcing polymer beads. Figure 4 yes Figure 3 An enlarged cross-sectional view of one of the reinforced polymer beads 324 shows the internal structure 204 of the polymer bead 200 and the reinforcing adhesive 320 covering the polymer bead 200 and containing bead-covered microspheres 300. Figure 5 yes Figure 4 An enlarged cross-sectional view of a portion of one of the reinforcing polymer beads 324 shows its honeycomb internal structure 204. Furthermore, Figure 5A bead-covered microsphere 300 is shown, most of which are fully embedded in a reinforcing adhesive 320, with a few partially embedded in the reinforcing adhesive 320. The reinforcing adhesive 320 bonds the bead-covered microspheres 300 to polymer beads 200 and to each other. An injection matrix 334 bonds the reinforcing polymer beads 324 together, bonds the interstitial microspheres 302 together, and bonds the interstitial microspheres 302 to the reinforcing polymer beads 324.

[0022] The reinforcing adhesive 320 may be a thermosetting or thermoplastic material. Similarly, the injection matrix 334 may be a thermosetting or thermoplastic material. The injection matrix 334 may be the same material as the reinforcing adhesive 320 or a different material. Examples of materials used for the reinforcing adhesive 320 and / or the injection matrix 334 include, but are not limited to, epoxy resins, epoxy amines, epoxy anhydrides, silicones, vinyl esters, polyurethanes, polyureas, polyesters, cycloolefins, phenolic resins, polyimides, polybenzimidazoles, and polyetherimides.

[0023] In the example of thermosetting materials, the reinforcing binder 320 and / or the injection matrix 334 can be formed as a mixture of liquid resin and a hardener or catalyst. An example of an epoxy resin is bisphenol A diglycidyl ether epoxy resin. The hardener can be any suitable polymerization initiator, such as an amine or alcohol hardener, and is mixed with the resin in an appropriate proportion to obtain a resin mixture that will harden or cure over time. Examples of hardeners include aliphatic polyamine hardeners and cyclic polyamine hardeners. Examples of commercially available two-part resin systems (i.e., resin and hardener) include DE NEEF. TM Denepox I-40, available from GCP Applied Technologies in Alfreta, Georgia; UltraThin2 Epoxy TM It is available from Pace Technologies in Tucson, Arizona; and CI-SLV TM Ultra-low viscosity structural injection epoxy resin is available from Simpson Strong Connections, Inc., Pleasanton, California. Other examples of resin systems include RTM6, available from Hessel, Inc., Stamford, Connecticut. TM 1078-1 TM and RTM200 TM Resin system; SICOMM 823 RTM available from SICOMM in Brussels, Belgium. TM Epoxy resin; and other low-viscosity injection resins.

[0024] In a further example, the composite foam 102 may optionally include one or more additives (not shown) to improve the manufacturability and / or properties of the composite foam 102. For example, expanded aluminum or carbon nanotubes (not shown) may be added to the injection matrix 334 to remove heat from the interior of the composite foam 102 during the final curing process. Alternatively or additionally, a wetting agent (not shown) may be added to improve the wettability of the surfaces of the reinforcing polymer beads 324 and the interstitial microspheres 302, thereby promoting resin impregnation with the injection matrix 334. The bead-covered microspheres 300 and / or the interstitial microspheres 302 may be treated with a tackifier such as a functionalized silane to improve adhesion to the reinforcing adhesive 320 and / or the injection matrix 334.

[0025] Figure 6 An example of polymer beads 200 in the form of expanded polystyrene (EPS) beads is shown. In the currently disclosed composite foam 102, the polymer beads 200 are formed from a low-density thermoplastic foam material. In this respect, the polymer beads 200 can be formed from any of a variety of thermoplastic materials, including but not limited to expanded polystyrene foam, expanded polypropylene foam, low-density polyethylene foam, and polyurethane foam. In some examples of composite foam 102, some polymer beads 200 may be formed from a first material, and the remainder of the polymer beads 200 may be formed from a second material (or a third material, etc.) different from the first material.

[0026] Polymer beads 200 can be formed from closed-cell foam. The material of polymer beads 200 ensures that reinforcing adhesive 320 does not significantly penetrate into polymer beads 200. For example, reinforcing adhesive 320 does not penetrate into each polymer bead 200 to a depth exceeding 10% of the bead width 202. Similarly, reinforcing adhesive 320 does not penetrate into each bead-covered microsphere beyond the microsphere diameter 304. Figure 8 The depth is 10% of the total depth. In some examples not shown, the polymer beads 200 may have a non-porous surface layer (not shown) that prevents the reinforcing adhesive 320 from entering the open-cell foam of the polymer beads 200 during and throughout the composite foam manufacturing process. Alternatively or additionally, the manufacturing process may be carried out in a manner that prevents the reinforcing adhesive 320 from entering the polymer beads 200 at any time during the manufacturing process.

[0027] In each of the composite foam 102 configurations disclosed herein, the true density of the polymer beads 200 is less than 0.1 g / cm³. 3 More preferably, the actual density of the polymer beads 200 is less than 0.05 g / cm³. 3 Most preferably, the actual density of the polymer beads 200 is between 0.02 and 0.04 g / cm³. 3Between. In this disclosure, the true density is the mass of the microspheres divided by the volume occupied by the microspheres, excluding the space volume between the microspheres. As mentioned above, the bead width 202 of the polymer beads 200 ( Figure 6 The diameter of the polymer beads 200 is 0.5 to 50 mm. In this disclosure, the bead width 202 of the polymer beads 200 is a measure of their maximum width. Although the illustration of the composite foam 102 shows polymer beads 200 of a single size, in other examples not shown, the composite foam 102 may have polymer beads 200 of two or more sizes distributed throughout the injection matrix 334. For example, the composite foam 102 may be provided in an arrangement in which a portion (e.g., 90%) of the polymer beads 200 in the composite foam 102 has a diameter of 3 mm, and the remaining portion (e.g., 10%) of the polymer beads 200 in the composite foam 102 has a diameter of 7 mm. Alternatively or additionally, the composite foam 102 may consist of polymer beads 200 in two or more size ranges (e.g., polymer beads 200 of 5.0 to 5.5 mm and polymer beads 200 of 7.0 to 7.5 mm).

[0028] The polymer beads 200 in the composite foam 102 have a generally spherical shape. For example, Figure 6 The polymer beads 200 in the composite foam 102 have a spherical shape. However, the polymer beads 200 can be provided in any of a variety of alternative shapes, such as elliptical (not shown) and / or irregular circular (not shown). Although the illustration of the composite foam 102 shows a single shape of polymer beads 200, the composite foam 102 may include polymer beads 200 having two or more different shapes.

[0029] Reference Figures 7 to 8 This image shows an enlarged view of an example of a microsphere representing bead-covered microspheres 300 and interstitial microspheres 302. In the example shown, the bead-covered microspheres 300 and interstitial microspheres 302 are hollow to minimize their density. However, in other examples not shown, the bead-covered microspheres 300 and / or interstitial microspheres 302 may be solid spheres or a combination of hollow and solid spheres. Unlike polymer beads 200, which may have a generally circular shape that is not necessarily spherical, the bead-covered microspheres 300 and interstitial microspheres 302 are spherical to provide a microsphere diameter 304 (…). Figure 8 The uniformity of the microsphere diameter 304 contributes to the wall thickness 336 (e.g., between the polymer beads 200 or matrix cavity 206 of the cured composite foam 102) Figure 3 and Figure 10The uniformity of the wall thickness 336 has a significant impact on the strength efficiency of the composite foam 102. In this regard, a minimum distance (i.e., wall thickness 336) is set between the matrix cavities 206 around the shell 208 of the polymer beads 200 or matrix cavity 206 (i.e., the reinforcing adhesive 320 containing the bead-covered microspheres 300) as a means of minimizing stress concentration in the composite foam 102 caused by the matrix cavities 206.

[0030] The density of the bead-covered microspheres 300 and / or the interstitial microspheres 302 is less than 0.6 g / cm³. 3 Preferably less than 0.4 g / cm³ 3 The bead-coated microspheres 300 and interstitial microspheres 302 are composed of glass (e.g., silica), ceramic, polymer, or other suitable materials. The bead-coated microspheres 300 may be formed of the same material as the interstitial microspheres 302, or of a different material. Alternatively or additionally, the bead-coated microspheres 300 may be provided in the same or different sizes as the interstitial microspheres 302.

[0031] In one example, the bead-covered microspheres 300 and the interstitial microspheres 302 are hollow glass microspheres (HGMS), such as S38 HGMS and S38HS HGMS, commercially available from 3M Company in St. Paul, Minnesota. S38 HGMS and S38HS HGMS are made of soda-lime borosilicate glass with a bulk density of 0.38 g / cm³. 3 S38 HGMS has a compressive strength of 4000 psi, while S38HSHGMS has a compressive strength of 5500 psi. K25 HGMS is another example of hollow glass microspheres available from 3M, which can be used as bead-covered microspheres 300 and / or interstitial microspheres 302. K25 HGMS is made of soda-lime borosilicate glass with a bulk density of 0.25 g / cm³. 3 The compressive strength is 750 psi. In another example of hollow glass microspheres, iM16K is available from 3M and is made of soda-lime borosilicate glass with a bulk density of 0.46 g / cm³. 3 The microspheres have a compressive strength of 16,000 psi and a relatively small diameter (e.g., 10 to 20 μm) compared to larger diameter S38 HGMS (20 to 100 μm) and K25 HGMS (20 to 100 μm).

[0032] In any one or more examples of composite foam 102 disclosed herein, the largest interstitial microsphere 302 and / or the largest bead-covered microsphere 300 may be at least 7 times smaller than the smallest polymer bead 200 or matrix cavity 206. In specific examples, the largest interstitial microsphere 302 and / or the largest bead-covered microsphere 300 may be at least 10 times smaller than the smallest polymer bead 200 or matrix cavity 206. Figure 7 As shown, the dimensions of the bead-covered microspheres 300 and the interstitial microspheres 302 refer to the microsphere diameter 304. In the currently disclosed composite foam 102, the bead-covered microspheres 300 and / or the interstitial microspheres 302 have a microsphere diameter 304 of 10 to 110 micrometers (µm).

[0033] The relatively small size of the bead-covered microspheres 300 minimizes the thickness of the reinforcing binder 320 covering the polymer beads 200. The primary purpose of the bead-covered microspheres 300 is to allow the reinforcing polymer beads 324 to be separated from each other and handled individually during manufacturing, as described below. The large size ratio (e.g., 7:1, 10:1, or greater) of the polymer beads 200 relative to the gap-filling microspheres 302 enhances their ability to flow through the powder layer 330 of the reinforcing polymer beads 324 and fill the gaps 332 between the reinforcing polymer beads 324, as... Figures 30 to 31 As shown, this will be described in more detail below.

[0034] It is noteworthy that in each example of composite foam 102 disclosed herein, the size distribution of the bead-covered microspheres 300 surrounding the polymer beads 200 or matrix cavity 206 is ±20 micrometers (µm) or smaller. In addition to the bead-covered microspheres 300, the interstitial microspheres 302 may also have a size distribution of ±20 µm or smaller. In this disclosure, size distribution refers to the percentage of microspheres with diameters within a specified size range. For example, composite foam 102 may be provided in a configuration in which at least 70% of the bead-covered microspheres 300 and / or at least 70% of the interstitial microspheres 302 have microsphere diameters 304 within the ±20 µm size range (e.g., microsphere diameters of 40 to 80 µm), and the remaining 30% or less of the microsphere diameters 304 are outside the size range (e.g., less than 40 µm or greater than 80 µm). In another example, the composite foam 102 can be provided in a configuration in which at least 90% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a size range of ±20 μm. In another example, at least 95% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a size range of ±20 μm. In yet another example, at least 99% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a size range of ±20 μm.

[0035] In some examples of composite foam 102, the size distribution of the bead-covered microspheres 300 and / or the size distribution of the interstitial microspheres 302 are no greater than ±10 μm. For example, composite foam 102 can be provided in a configuration in which at least 70% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a microsphere diameter 304 ranging from ±10 μm (e.g., microsphere diameter 304 is 43 to 63 μm). In another example, composite foam 102 can be provided in a configuration in which at least 90% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a size ranging from ±10 μm. In yet another example, at least 95% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a size ranging from ±10 μm. In yet another example, at least 99% of the bead-covered microspheres 300 and / or interstitial microspheres 302 have a size ranging from ±10 μm.

[0036] As described above, the relatively narrow size distribution of the bead-covered microspheres 300 and / or the interstitial microspheres 302 results in a relatively high hydrostatic compressive strength of the composite foam 102 at a relatively low density. For example, the currently disclosed composite foam 102 can be manufactured to provide a compressive strength greater than 3000 psi at a density of 0.34 to 0.38 g / cm³. The relatively high hydrostatic compressive strength of the composite foam 102 is partly due to the isostatic compressive strength of the microspheres, which is a function of their density and size (i.e., the microsphere diameter 304). Generally, the density and isostatic compressive strength of the microspheres increase as their size decreases.

[0037] For example, Figure 9 This is a performance graph of the aforementioned commercially available S38HS and K25 hollow glass microspheres under several different size distributions. As described below, this is achieved by using a stainless steel mesh screen 410 (e.g., Figure 21 and Figure 29 Large batches of S38HS and K25 hollow glass microspheres were sieved in increments of 10 μm, starting from 10 to 63 μm, to obtain the size distribution. Each increment was characterized by isostatic compressive strength and density. Figure 9 As shown, the density of K25 hollow glass microspheres in the size range of 63 to 75 μm is 0.19 g / cm³. 3 The isostatic compressive strength is approximately 300 psi. In contrast, smaller K25 hollow glass microspheres in the size range of 45 to 53 μm have a density of 0.25 g / cm³. 3 The isostatic compressive strength is approximately 600 psi, while the density of K25 hollow glass microspheres below 45 μm is 0.34 g / cm³. 3The isostatic compressive strength is approximately 800 psi. Notably, the isostatic compressive strength of K25 hollow glass microspheres smaller than 53 μm is higher than that of bulk K25 hollow glass microspheres with a relatively large size range of 20 to 100 μm and an average diameter of 40 μm (400 psi, as tested).

[0038] Still refer to Figure 9 The properties of S38HS hollow glass microspheres in the size range of 45 to 53 μm with a density of 0.30 g / cm³ are shown. 3 The isostatic compressive strength is approximately 2100 psi. In contrast, the density of smaller S38HS hollow glass microspheres in the 20 to 38 μm size range is 0.41 g / cm³. 3 Its isostatic compressive strength is approximately 4400 psi. For example... Figure 9 As shown, S38HS hollow glass microspheres with a size greater than 38 μm have a density comparable to K25 hollow glass microspheres, but their isostatic compressive strength is more than twice that of K25. Notably, the isostatic compressive strength of S38HS hollow glass microspheres with a size of 20 to 38 μm is higher than that of bulk S38HS hollow glass microspheres with a size range of 20 to 100 μm (3000 psi, as tested). In the development of the currently disclosed composite foam 102, S38HS hollow glass microspheres and iM16k hollow glass microspheres were used to demonstrate the effect of particle size (i.e., microsphere diameter 304) and size distribution (e.g., ±20 μm or less) on the mechanical properties of composite foam 102. In the case of iM16k, particle sorting (e.g., by sieving) does not affect the density or compressive strength within the range of interest.

[0039] Reference Figures 10 to 12 , Figure 10 It shows something similar to Figure 3 An enlarged view of a portion of the example composite foam 102, but Figure 10 The composite foam 02 comprises multiple matrix cavities 206 distributed throughout the injection matrix 334, rather than polymer beads 200. For example... Figures 10 to 11 As shown, each matrix cavity 206 is at least partially occupied by polymer particles 210 (e.g., less than 50%, more likely less than 10%). The polymer particles 210 are a result of the shrinkage of polymer beads 200 during the manufacture of the composite foam 102. The polymer beads 200 shrink when their temperature exceeds their glass transition temperature. Figures 3 to 5 The state of composite foam 102 before final curing or solidification is shown. However, this is an example of a manufacturing process not exceeding the glass transition temperature of polymer beads 200. Figures 3 to 5The state of composite foam 102 is also shown, wherein the polymer beads 200 retain the honeycomb internal structure 204 in the finally cured or solidified composite foam 102. Apart from the differences regarding the internal structure 204 of the polymer beads 200, Figures 3 to 5 All the above-mentioned properties of composite foam 102 are applicable to Figures 10 to 12 The composite foam 102, regardless of whether the glass transition temperature of the polymer beads 200 is exceeded during the manufacturing process.

[0040] Importantly, in each configuration of the composite foam 102 disclosed herein, the bead-covered microspheres 300 and the interstitial microspheres 302, in addition to reducing the density of the composite foam 102, also serve as spacers to control the spacing between the polymer beads 200 during manufacturing. Because the bead-covered microspheres 300 (and optionally, the interstitial microspheres 302) are relatively small in size and / or have a relatively narrow size distribution (e.g., ±20 μm or less), the composite foam 102 has a uniformly narrow wall thickness 336 between adjacent pairs of polymer beads 200 or matrix cavities 206. Figure 3 and Figure 10 As shown, the wall thickness 336 is the thickness of the reinforced polymer beads 324. Figure 3 ) or enhanced stromal cavity 326 ( Figure 10 The thickness of the reinforcing adhesive 320 (containing bead-covered microspheres 300) is a function of the thickness of the injected matrix 334 (containing interstitial microspheres 302) between the reinforcing polymer beads 324 or the reinforcing matrix cavities 326. In this disclosure, the wall thickness 336 at the narrowest point between at least 90% of adjacent pairs of polymer beads 200 or matrix cavities 206 in the composite foam 102 is 4 to 15 times the diameter of the largest bead-covered microspheres 300 and interstitial microspheres 302.

[0041] In any example of composite foam 102, some reinforcing polymer beads 324 may be in direct contact with each other, and / or some interstitial microspheres 302 may be in contact with the reinforcing polymer beads 324. Figure 3 ) or enhanced stromal cavity 326 ( Figure 10 Direct contact. In any configuration disclosed herein, composite foam 102 comprises 50 to 74 vol% of reinforcing polymer beads 324 or reinforcing matrix cavities 326, 20 to 30 vol% of interstitial microspheres 302, and the remainder as an injection matrix 334. For example, composite foam 102 may comprise 60 vol% of reinforcing polymer beads 324 or reinforcing matrix cavities 326, 20 vol% of interstitial microspheres 302, and 20 vol% of matrix. The aforementioned 74 vol% of reinforcing polymer beads 324 or reinforcing matrix cavities 326 represents optimal or perfect filling of the reinforcing polymer beads 324 in the powder layer 330, while the aforementioned 50 vol% of reinforcing polymer beads 324 or reinforcing matrix cavities 326 represents random filling of the reinforcing polymer beads 324 in the powder layer 330.

[0042] As described in more detail below, the reinforcing adhesive 320 surrounding each polymer bead 200 forms a relatively rigid outer shell 208. Figure 5 and Figure 12 The composite foam 102 is cured or solidified in a manner that increases its compressive strength. Although the shell typically has a high density, the use of bead-covered microspheres 300 in the reinforcing adhesive 320 covering relatively large polymer beads 200 (e.g., bead diameters of 1.5 to 50 mm) results in a slight increase in the overall density of the currently disclosed composite foam 102 relative to the density of conventional composite foams (not shown) using smaller polymer beads (e.g., less than 1.5 mm in diameter) (e.g., an increase of 0.02 to 0.03 g / cm³). 3 Because the shell 208 surrounds each polymer bead 200 ( Figures 3 to 5 ) or stromal cavity 206 ( Figures 10 to 12 The currently disclosed composite foam 102 achieves a 30% reduction in density while being 200% stronger than conventional composite foams. For example, as described above, composite foam 102 can achieve a density of 0.34 to 0.38 g / cm³. 3 It can be manufactured using an arrangement that provides a hydrostatic compressive strength greater than 3000 psi. In another example, composite foam 102 can be manufactured in a manner that results in a density of 0.36 to 0.42 g / cm³. 3 It is manufactured using an arrangement with a hydrostatic compressive strength greater than 4000 psi.

[0043] As described above, the performance improvement of the composite foam 102 is also partly attributable to the controlled size distribution of the bead-covered microspheres 300 (and optionally, the controlled size distribution of the interstitial microspheres 302). The ability to manufacture the composite foam 102 with this performance improvement is also partly attributable to several unique manufacturing techniques described below, such as techniques for forming the reinforcing polymer beads 324, and techniques for maintaining the close packing of the reinforcing polymer beads 314 when distributing the interstitial microspheres 302 within the powder layer 330 of the reinforcing polymer beads 324 prior to injection with the injection matrix 334. In addition to the performance improvement, the use of larger diameter polymer beads 200 (e.g., 1.5 to 50 mm) improves the manufacturability of the composite foam 102 (e.g., during polymer bead tumbling) compared to composite foams using smaller polymer beads 200 (e.g., less than 1.5 mm).

[0044] Now refer to Figure 13The table shows six different components of composite foam 102, which has different compositions of bead-covered microspheres 300 and interstitial microspheres 302 in both sieved and unsieved states. In this disclosure, "component" refers to the composition of composite foam 102. In this respect, each component includes a certain amount of polymer beads 200, polymer-reinforced binder 320, a certain amount of bead-covered microspheres 300, a certain amount of interstitial microspheres 302, and a polymer-injected matrix 334. As described above, the polymer beads 200 are formed from any of the thermoplastic foam materials listed above, preferably having a content of less than 0.1 g / cm³. 3 The true density, and can be supplied in one or more sizes, each having a bead width of 0.5 to 50 mm. The polymer-reinforced adhesive 320 comprises any of the thermosetting or thermoplastic resins listed above configured to coat the polymer beads 200. For example... Figure 5 and Figure 12 As shown, the bead-covered microspheres 300 are at least partially embedded in the reinforcing adhesive 320. The reinforcing adhesive 320 is configured to be cured (i.e., for thermosetting resins) or solidified (i.e., for thermoplastic resins) in a manner that produces a plurality of individually separable reinforcing polymer beads 324.

[0045] In each component, the interstitial microspheres 302 are configured to fill the gaps 332 between the reinforcing polymer beads 324. Figure 3 The bead-covered microspheres 302 and 303 are distributed within the powder layer 330 of the reinforced polymer beads 324 in a void manner. In any one or more components, the largest interstitial microsphere 302 may be at least 7 times smaller than the smallest polymer bead 200. Alternatively or additionally, in any one or more components, the largest bead-covered microsphere 300 may be at least 7 times smaller than the smallest polymer bead 200. In each component, the bead-covered microspheres 300 are provided in a size distribution of ±20 μm or less. In some components, the interstitial microspheres 302 may also be provided in a size distribution of ±20 μm or less. The microsphere diameter 304 of the bead-covered microspheres 300 and / or interstitial microspheres 302 is preferably 10 to 110 μm. The bead-covered microspheres 300 and interstitial microspheres 302 may be composed of glass (e.g., silica), ceramic, polymer, or other materials, and may have a density of less than 0.6 g / cm³. 3 The density.

[0046] As described above, the polymer infusion matrix 334 for each component comprises any of the thermosetting or thermoplastic resins listed above. The infusion matrix 334 is configured to be infused into the powder layer 330 of the reinforcing polymer beads 324 and the interstitial microspheres 302. As described below, the polymer infusion matrix 334 is infused in a manner that removes air from the powder layer 330. When infusion is complete, the interstitial microspheres 302 and the reinforcing polymer beads 324 are encapsulated within the infusion matrix 334, which binds the reinforcing polymer beads 324 together, binds the interstitial microspheres 302 together, and adheres the reinforcing polymer beads 324 to the interstitial microspheres 302. As described above, during manufacturing, the infusion matrix 334 does not significantly penetrate into the reinforcing polymer beads 324 or the interstitial microspheres 302.

[0047] For each component, the injection matrix 334 is configured to be cured (i.e., for thermosetting resins) or solidified (i.e., for thermoplastic resins) in a manner that produces composite foam 102. When the injection matrix 334 is cured or solidified at a temperature exceeding the glass transition temperature of the polymer beads 200, the size of each polymer bead 200 can shrink up to 20 times or more of its original size to form polymer particles 210. Figures 10 to 11 The polymer particles 210 are contained within a matrix cavity 206, which is surrounded by a shell 208 composed of a cured or solidified reinforcing adhesive 320 containing bead-covered microspheres 300. When the temperature of the polymer beads 200 is maintained below the glass transition temperature during manufacturing, the honeycomb internal structure 204 within the polymer beads 200 can be preserved, thereby forming a honeycomb-like structure. Figures 3 to 5 The composite foam 102 shown.

[0048] Reference Figures 13 to 14 , Figure 13 The six different composite foam 102 components listed herein (not shown) were tested according to the methods described below and Figures 17 to 40 The sample was manufactured as shown. The sample was used to demonstrate the performance improvement of the currently disclosed composite foam 102 compared to the prior art foam 106. Figure 14 The six components are identical except for the size distribution of the bead-covered microspheres 300 and the interstitial microspheres 302. More specifically, the sorted (e.g., sieved) and unsorted (e.g., unscrewed or batched) amounts of the aforementioned S38HS HGMS and iM16k HGMS are used for the bead-covered microspheres 300 used to manufacture the reinforcing polymer beads 324. The size distribution of the sorted S38HS HGMS is ±20 μm or smaller. For the interstitial microspheres 302, the interstitial spaces 332 between the reinforcing polymer beads 324 are filled using both sorted (i.e., ±20 μm or smaller) and unsorted (e.g., batched) versions of S38HS HGMS before the powder layer 330 is infused with the injection matrix 334.

[0049] Each specimen was cored from a larger piece of composite foam 102. Epoxy resin was used to seal the outer surface of the specimen. Each specimen was then subjected to hydrostatic compression, and the water volume displacement was recorded.

[0050] Figure 15 This is a graph showing the functional relationship between water volume displacement and the hydrostatic pressure applied to the specimen (i.e., hydrostatic compression). Based on this relationship, the hydrostatic compressive strength of each specimen was characterized. For example, a change in water volume displacement without a corresponding change in hydrostatic pressure indicates a compression event has occurred in the specimen

[108] . Figure 15 In the figure, initial extrusion event 108 is represented by an initial fracture with a linear slope, which occurs at approximately 4700 psi. Initial extrusion event 108 is likely due to the permeation of the pressurized medium (i.e., water) into the closed-cell foam. Following initial extrusion event 108, the hydrostatic pressure increases slightly, after which the slope fractures again, indicating further extrusion of the sample.

[0051] Figure 13 The hydrostatic compression test results for each component of the composite foam 102 are listed, including density, extrusion pressure, and corresponding underwater service depth. In this disclosure, the service depth includes a safety factor of 1.5 to account for potential material defects, manufacturing tolerances, and / or unexpected conditions or loads on the composite foam. Calculating the service depth for each component involves determining the extrusion pressure of the composite foam specimen (i.e., Figure 13 The “composite foam extrusion strength” (e.g., by hydrostatic compression test). Working pressure of each component ( Figure 13 (Not shown in the diagram) is calculated by dividing its extrusion pressure by a safety factor (e.g., 1.5). Using depth (i.e., Figure 13 The “composite foam application depth” is calculated by dividing the working pressure by the hydrostatic pressure gradient. ρg It is determined by ), where, ρ It is the density of the medium (e.g., water). g It is gravitational acceleration.

[0052] The density and extrusion pressure of each component, such as Figure 14 As shown. Figure 13As shown, the composition using sorted (e.g., sieved) amounts of S38HS HGMS for bead-covered microspheres 300 and / or interstitial microspheres 302 has a density 17% lower than that of prior art foam 106 with similar strength, and its compressive strength (i.e., compressive strength) is more than four times that of foam with similar density. The use of unsorted microspheres was also included to demonstrate that performance improvements are provided by sorting bead-covered microspheres 300 and interstitial microspheres 302 to a size distribution of ±20 μm or smaller. For example, using sieved S38HS HGMS as the composition for interstitial microspheres 302 has a density of 0.42 g / cm³ compared to using unsieved S38HS HGMS as interstitial microspheres 302. 3 Component 3 has a lower density (0.36 g / cm³) and a compressive strength of 4125 psi. 3 It also exhibits higher compressive strength (4619 psi). In another example, component 6 using sieved S38HS HGMS as interstitial microspheres 302 has a density of 0.39 g / cm³ compared to component 6 using unsieved S38HS HGMS as interstitial microspheres 302. 3 The component with a compressive strength of 2227.5 psi has a lower density (0.37 g / cm³). 3 ) and higher compressive strength (3705 psi).

[0053] Now refer to Figure 16 And additional reference Figures 17 to 40 , Figure 16 A flowchart illustrating the operations included in the currently disclosed method 500 for manufacturing composite foam 102 is shown.

[0054] Reference Figures 17 to 23 Step 502 of the method includes coating a certain amount of polymer beads 200 with a polymer-reinforced adhesive 320, the polymer-reinforced adhesive having a sorted amount 308 of bead-covered microspheres 300 that are at least partially embedded in the reinforcing adhesive 320. Figure 17 The illustration shows polymer beads 200 being poured into a container 420 of a tilted glass 418. Container 420 may be cylindrical or have other shapes. Container 420 defines a rotation axis (not shown) that may be oriented at a non-perpendicular angle. Figure 18This is an enlarged view of some of the polymer beads 200 in the tilted glass 418. As mentioned above, the polymer beads 200 can be supplied in one or more sizes. However, each polymer bead 200 has a bead width 202 of 0.5 to 50 mm. In one example, the bead width 202 of each polymer bead 200 is greater than 1.5 mm. In another example, the bead width 202 of each polymer bead 200 is between 3.0 and 3.5 mm. As mentioned above, the polymer beads 200 are formed from low-density thermoplastic foam materials such as expanded polystyrene and / or expanded polypropylene. The polymer beads 200 have a density of less than 0.1 g / cm³. 3 The true density. For example, the true density of polymer beads 200 can be less than 0.05 g / cm³. 3 More preferably, it is between 0.02 and 0.04 g / cm³. 3 between.

[0055] Reference Figures 19 to 20 Step 502 of the method includes pouring reinforcing adhesive 320 onto polymer beads 200 until fully coated, thereby forming adhesive-coated polymer beads 322. As described above, the reinforcing adhesive 320 can be a thermosetting resin or a thermoplastic resin. In the example of a thermosetting resin, the reinforcing adhesive 320 can be prepared by mixing epoxy resin with a suitable hardener in a relevant proportion until homogeneous. Figure 19 As shown, while the polymer beads 200 are agitated, for example, by using a stirring rod 412, a reinforcing adhesive 320 is poured onto the polymer beads 200 in container 420. The amount of reinforcing adhesive 320 poured onto the polymer beads 200 is provided at a predetermined weight ratio of reinforcing adhesive 320 to polymer beads 200 (e.g., 10:1). The polymer beads 200 are agitated (e.g., by using the stirring rod 412) until each polymer bead 200 is completely covered by the reinforcing adhesive 320. In this stage, as... Figure 20 As shown, the polymer beads 322 coated with adhesive clump together or stick together to form a large number of large aggregates 328.

[0056] Reference Figure 21 Before or during step 502, the method includes sieving a large batch 306 of bead-covered microspheres 300 to obtain a sorting quantity 308 of bead-covered microspheres 300 having a desired size distribution of ±20 μm or less (e.g., ±10 μm or less). In some examples, the largest bead-covered microsphere 300 is at least 7 times smaller than the smallest polymer bead 200. As described above, the microsphere diameter 304 of the bead-covered microspheres 300 is... Figure 8 The preferred size is 10 to 110 μm. Figure 21The process of sieving a large batch of bead-covered microspheres 300 306 using a mesh sieve 410 is illustrated. Depending on the initial size range of the large batch of bead-covered microspheres 306 306, multiple mesh sieves 410 with different mesh sizes (e.g., at least two mesh sieves) may be required during the sieving operation. As mentioned above, the bead-covered microspheres 300 can have a mesh size of less than 0.6 g / cm³. 3 It has a density and can be formed from glass, ceramics, polymers or other suitable materials.

[0057] Reference Figures 22 to 23 Step 502 of the method includes adding bead-coated microspheres 300 of sorted quantity 308 to adhesive-coated polymer beads 322. For example... Figure 22 As shown, while physically agitating the polymer beads 200 and rotating the container 420 about its non-vertical axis, a sorting amount of 308 bead-covered microspheres 300 is added. For example, the mixture can be manually agitated using a stirring rod 412 while the container 420 is rotating. Figure 23 As shown, the process of adding bead-covered microspheres 300 while rotating the container 420 and physically agitating the mixture causes the bead-covered microspheres 300 to embed within the reinforcing adhesive 320 covering each polymer bead 200. The addition of the bead-covered microspheres 300 gradually reduces the cohesive forces between the aggregates 328 of the adhesive-coated polymer beads 322, causing them to physically break down or unclump rather than remain in a clumped state. This process continues until the adhesive-coated polymer beads 322 begin to tumble freely, thereby producing a certain amount of individual reinforcing polymer beads 324. The excess bead-covered microspheres 300 are then removed from the tilted glass 418.

[0058] Reference Figures 24 to 27 Step 502 of the method includes removing the reinforced polymer beads 324 from the tilted glass 418 and placing the reinforced polymer beads 324 in the sealed container 420. (As...) Figure 24 As shown, the sealed container 420 can be mounted on a multi-axis tumbling machine 414, which is configured to rotate the container 420 about multiple degrees of freedom. Step 502 includes tumbling the reinforcing polymer beads 324 in the sealed container 420 at a predetermined temperature (e.g., room temperature) for a predetermined time period (e.g., 16 hours) to solidify the reinforcing adhesive 320 and the bead-covered microspheres 300 surrounding the polymer beads 200. Figure 25 As shown, the process of tumbling the reinforcing polymer beads 324 results in a uniform thickness of the reinforcing adhesive 320 covering each polymer bead 200.

[0059] Reference Figures 26 to 27 After the tumbling process is completed, step 504 of the method includes allowing the reinforcing adhesive 320 to cure or solidify in a manner that produces a plurality of reinforcing polymer beads 324, such as Figure 27 As shown. In the case where the reinforcing adhesive 320 is a thermosetting resin, the reinforcing polymer beads 324 are cured at a predetermined temperature (e.g., 55°C) for a predetermined time (e.g., 2 hours). For example, as... Figure 26 As shown, the sealed container 420 can be transferred to the oven 430. In the case where the reinforcing adhesive 320 is a thermoplastic resin, step 502 of coating the polymer beads 200 with the reinforcing adhesive 320 may involve heating the reinforcing adhesive 320 to reduce its viscosity when coating the polymer beads. Bead-covered microspheres 300 are added until the aggregates 328 of the adhesive-coated polymer beads 322 physically break down into individual reinforcing polymer beads 324. The reinforcing polymer beads 324 can then be flipped over as the thermoplastic resin is allowed to solidify.

[0060] Reference Figure 28 Step 506 of the method includes placing a certain amount of reinforcing polymer beads 324 into mold 404. While the mold 404 shown has a cylindrical shape, it can also be provided in any size, shape, or configuration. To increase the filling rate of the reinforcing polymer beads 324 within mold 404, step 506 may optionally include pouring the reinforcing polymer beads 324 into mold 404 while simultaneously agitating or shaking it. For example, as... Figure 20 As shown, mold 404 can be mounted on mechanical vibrator 416 for vibrating mold 404 at a high frequency (e.g., 1500 to 2000 rpm) for a predetermined time period (e.g., 1 to 3 minutes) during and / or after receiving reinforced polymer beads 324. Alternatively or additionally, mold 404 can be agitated by tapping its sides during and / or after pouring reinforced polymer beads 324 into it.

[0061] Reference Figure 29 For an example where the configuration (e.g., microsphere diameter, size distribution, microsphere material, etc.) of the sorted quantity 308 of bead-covered microspheres 300 differs from the configuration of the interstitial microspheres 302, the method may include sieving a large batch 306 of interstitial microspheres 302 to obtain a sorted quantity 308 of interstitial microspheres 302 having the desired microsphere size and a size distribution of ±20 μm or less, which may also be the size distribution of the bead-covered microspheres 300 mentioned in step 502. As described above, in any example, the largest interstitial microsphere 302 may be at least 7 times smaller than the smallest polymer bead 200 or matrix cavity 206, which may also be the size ratio of the bead-covered microspheres 300 mentioned in step 502. The microsphere diameter 304 of the interstitial microspheres 302 is preferably 10 to 110 μm. Figure 29 The use of methods similar to those described above is shown. Figure 21The process of screening a large batch of 306 bead-covered microspheres 300 uses a mesh screen 410 to screen a large batch of 306 interstitial microspheres 302.

[0062] Reference Figures 30 to 31 Step 508 of the method includes distributing the sorted amount 308 of interstitial microspheres 302 among all the reinforcing polymer beads 324 in the mold 404 to obtain a powder layer 330. For example... Figure 30 As shown, step 508 may include pouring the sorted amount 308 of interstitial microspheres 302 into the mold 404 while oscillating the mold 404 using a mechanical vibrator 416. The mold 404 may also oscillate while the interstitial microspheres 302 are being sieved on one or more screens 410 (not shown), causing the sorted amount of interstitial microspheres 302 to fall into the mold 404. The mold 404 may be oscillated or vibrated before, during, and / or after the sorted amount 308 of interstitial microspheres 302 is added to the powder layer 330 of the reinforcing polymer beads 324. The oscillation of the mold 404 may continue until the entire free volume of the interstitial gaps 332 between the reinforcing polymer beads 324 is filled with the interstitial microspheres 302 in a manner that the interstitial microspheres 302 are uniformly distributed throughout all the reinforcing polymer beads 324, such as... Figure 31 As shown. As a means of minimizing the amount of void space in the powder layer 330, vacuum pressure (not shown) can be applied alternately or simultaneously to one side of the mold 404 while filling microspheres 302 are added to the powder layer 330 on the opposite side of the mold 404.

[0063] In some examples, the sorted quantity 308 of interstitial microspheres 302 is added to the reinforcing polymer beads 324 to achieve 50 to 74 vol% of the reinforcing polymer beads 324 relative to the combined volume of the interstitial microspheres 302, the reinforcing polymer beads 324, and the remaining space to be filled by the injection matrix 334. In some examples, the interstitial microspheres 302 may constitute 20 to 30 vol% of the combined volume. As described above, 74 vol% of the reinforcing polymer beads 324 represents perfect filling of the reinforcing polymer beads 324 in the mold 404, while 50 vol% of the reinforcing polymer beads 324 represents random filling of the reinforcing polymer beads 324.

[0064] Reference Figures 32 to 35 Step 510 of the method includes injecting the powder layer 330 into the mold 404 using a polymer injection matrix 334. As described above, the injection matrix 334 can be a thermosetting resin or a thermoplastic resin. If the injection matrix 334 is a thermosetting resin, the method includes mixing the resin with an appropriate amount of hardener to obtain a homogeneous resin mixture.

[0065] Figures 32 to 33An example of a mold assembly 402 is shown, which has a porous glass frit 422 or other porous material placed on a top side 406 of the mold, and a porous glass frit 422 placed on a bottom side 408 of the mold. The porous glass frit 422 allows the powder layer 330 to be liquid-impregnated within the mold 404. A manifold 424 is mounted on one side of the mold 404 to introduce the injection matrix 334. The manifold 424 is configured to ensure that the injection matrix 334 is introduced across the entire cross-section of the powder layer 330.

[0066] Figure 34 An example of a manufacturing system 400 for injecting powder layer 330 into mold 404 is shown. Manufacturing system 400 includes a resin container 428 containing a resin mixture (i.e., injection matrix 334). Resin container 428 is fluidly connected to manifold 424. Furthermore, manufacturing system 400 includes a vacuum source 426, such as a vacuum pump (not shown), fluidly connected to the top side 406 of the mold. As described above, powder layer 330 is sealed at both ends of mold 404 by porous glass frit 422, which allows powder layer 330 to be impregnated with a liquid having a pore size smaller than that of minimum interstitial microspheres 302, but large enough to allow injection matrix 334 to pass through.

[0067] Reference Figures 34 to 35 Step 510, which involves injecting the powder layer 330 with the injection matrix 334, includes applying a vacuum pressure to the side of the mold 404 opposite to the side where the injection matrix 334 is introduced. In the example shown, the injection is initiated by activating the vacuum source 426 to generate a vacuum pressure, which is used to draw the injection matrix 334 from the resin container 428 upward into a manifold 424 on the bottom side 408 of the mold, through the porous glass frit 422, through the powder layer 330, and out from the porous glass frit 422 on the top side 406 of the mold, as shown. Figure 35 As shown. Optionally, positive pressure can be applied to the resin container 428 simultaneously to accelerate the resin injection process.

[0068] In step 510, a vacuum pressure is applied for a predetermined time (e.g., 1 to 3 hours) to reduce the amount of resin-molten powder layer 330 and / or until a suitable amount of injection matrix 334 leaves the top side 406 of the mold and / or until the entire powder layer 330 is saturated with injection matrix 334. Advantageously, suctioning the injection matrix 334 through the powder layer 330 in an upward direction (opposite to the downward direction) improves the reduction and removes air bubbles that would otherwise be trapped in the powder layer 330.

[0069] Figure 36A mold 404 is shown after injecting an injection matrix 334 into a powder layer 330 of reinforcing polymer beads 324 and interstitial microspheres 302, resulting in a pre-cured composite foam 102. Step 512 of the method includes allowing the injection matrix 334 in the powder layer 330 to cure (e.g., for thermosetting resins) or solidify (e.g., for thermoplastic resins) within the mold 404. For example, the composite foam 102 is allowed to cure at room temperature for a predetermined time period (e.g., 12 hours). Figure 37 This is an enlarged view of a portion of composite foam 102 in a pre-cured state, wherein polymer beads 200 are typically in their original state, having Figure 5 The honeycomb-like internal structure 204 is shown.

[0070] Reference Figure 38 An example of a mold 404 placed in an oven 430 is shown for the final curing of composite foam 102. During the final curing process, the composite foam 102 is heated to a high temperature (e.g., 135°C) and held for a short period (e.g., 2 hours). After final curing and cooling, as shown... Figure 39 As shown, composite foam 102 is removed from mold 404.

[0071] Figure 40 yes Figure 39 An enlarged view of a portion of the post-cured composite foam 102, showing multiple matrix cavities 206 injected into a matrix 334. As described above, each matrix cavity 206 contains polymer particles 210, which are polymer beads 200 (…) due to the high temperatures associated with the final curing process. Figure 37 This is caused by shrinkage. The above steps are preferably performed by producing a post-cured composite foam 102 with a wall thickness of 336 (mm). Figure 3 and Figure 10 The diameter of the largest bead-covered microsphere 300 and the interstitial microsphere 302 is 4 to 15 times. As mentioned above, the wall thickness 336 is the narrowest point between each adjacent pair of polymer beads 200 or matrix cavity 206 in the composite foam 102.

[0072] In its post-cured state, composite foam 102 can be molded into foam product 104 as needed. For example, composite foam 102 can be processed into foam product 104, the shape of which is similar to that of unmanned underwater vehicle 100 (e.g., Figure 1 The shapes of the internal pouch and / or external contour of a submarine application are complementary.

[0073] Advantageously, the currently disclosed composite foam 102 can withstand hydrostatic pressures greater than 4500 psi (operational depth greater than 7500 feet) and has a density of less than 0.40 g / cm³. 3This represents a significant improvement over the most advanced foam systems currently available. The improved performance characteristics of the composite foam 102 are partly a result of controlling the particle size distribution of the bead-covered microspheres 300 in combination with controlling the particle size distribution of the interstitial microspheres 302. Furthermore, several steps in the manufacturing process enable the low density of the composite foam 102. For example, as... Figure 22 As shown, while physically agitating (e.g., with a stirring rod 412) the polymer beads 200 during rotation of the tilted glass 418, adding a sorted amount 308 of bead-coated microspheres 300 to the binder-coated polymer beads 322 improves the hydrostatic compressive strength of the composite foam 102 while minimizing the density increase (e.g., 0.02 to 0.03 g / cm³). 3 Furthermore, by first filling mold 404 with reinforced polymer beads 324, and then shaking mold 404, a tightly filled state is achieved. Figure 28 Then add gap-filling microspheres 302 ( Figure 30 This prevents the polymer beads 200 from moving away from each other. When the interstitial microspheres 302 are added, preventing the polymer beads 200 from moving away from each other results in a lower density composite foam 102, which can be achieved by mixing the reinforcing polymer beads 324, the interstitial microspheres 302 and the injection matrix 334 together, and then pouring the bead-microsphere-matrix mixture into a mold.

[0074] Many modifications and other versions and examples of this disclosure will occur to those skilled in the art upon which this disclosure pertains, taking advantage of the teachings presented in the foregoing description and related drawings. The versions and examples described herein are illustrative and not intended to be limiting or exhaustive. While specific terminology is used herein, it is used only in a general and descriptive sense and not for limiting purposes. In addition to those listed herein, functionally equivalent methods and apparatuses within the scope of this disclosure are also possible based on the foregoing description. Such modifications and variations should fall within the scope of the appended claims. This disclosure is limited only by the full scope of the appended claims together with their equivalents.

[0075] This disclosure also includes the following provisions: Clause 1. A component for use in composite foams, said component comprising: A quantity of polymer beads of one or more sizes, with each polymer bead having a width of 0.5 to 50 mm; A polymer-reinforced adhesive configured to coat the polymer beads; A certain amount of bead-covered microspheres, at least partially embeddable in the reinforcing adhesive, and the reinforcing adhesive is configured to be cured or solidified in a manner that produces a plurality of individual reinforcing polymer beads; A certain amount of interstitial microspheres, the interstitial microspheres being configured to be distributed within the powder layer of the reinforcing polymer beads; and A polymer-injected matrix is ​​configured to be injected into the powder layer of the reinforcing polymer beads and the interstitial microspheres, and the injection matrix is ​​configured to be cured or solidified in a manner that generates a composite foam. The bead-covered microspheres have a size distribution of ±20 μm or smaller.

[0076] Clause 2. The composition according to Clause 1, wherein the interstitial microspheres have a size distribution of ±20 μm or less.

[0077] Clause 3. The composition according to Clause 1, wherein the bead-covered microspheres and / or the interstitial microspheres have a width of 10 to 110 μm.

[0078] Clause 4. The composition according to Clause 1, wherein the bead-covered microspheres and the interstitial microspheres have a content of less than 0.6 g / cm³. 3 The density.

[0079] Clause 5. The composition according to Clause 1, wherein at least one of the quantity of bead-covered microspheres and the quantity of interstitial microspheres is composed of at least one of the following materials: glass, ceramic, polymer.

[0080] Clause 6. The composition according to Clause 1, wherein the polymer beads are composed of at least one of the following thermoplastic materials: expanded polystyrene foam, expanded polypropylene foam, low-density polyethylene foam, and polyurethane foam.

[0081] Clause 7. The composition according to Clause 1, wherein the polymer beads have a content of less than 0.1 g / cm³. 3 The true density.

[0082] Clause 8. The composition according to Clause 1, wherein at least one of the reinforcing adhesive and the injection matrix comprises at least one of the following thermosetting or thermoplastic materials: epoxy resin, epoxy amine, epoxy acid base, silicone, vinyl ester, polyurethane, polyurea, polyester, cycloolefin, phenolic resin, polyimide, polybenzimidazole, polyetherimide.

[0083] Clause 9. A composite foam, said composite foam comprising: Polymer injection matrix; A plurality of polymer beads of one or more sizes distributed throughout the injection matrix and at least one matrix cavity, each of the polymer beads and matrix cavities having a width of 0.5 to 50 mm and surrounded by a polymer-reinforced binder containing bead-covered microspheres, and each matrix cavity being partially occupied by polymer particles; and A certain amount of interstitial microspheres are distributed within the injected matrix, between the polymer beads or the matrix cavity. The bead-covered microspheres have a size distribution of ±20 μm or smaller.

[0084] Clause 10. The composite foam according to Clause 9, wherein the interstitial microspheres have a size distribution of ±20 μm or less.

[0085] Clause 11. The composite foam according to Clause 9, wherein the wall thickness of the composition of the reinforcing adhesive and the injected matrix at the narrowest point between at least 90% of adjacent pairs of polymer beads or matrix cavities in the composite foam is 4 to 15 times the diameter of the largest bead-covering microspheres and interstitial microspheres.

[0086] Clause 12. The composite foam according to Clause 9, wherein the bead-covered microspheres and the interstitial microspheres have a density of less than 0.6 g / cm³. 3 The density.

[0087] Clause 13. The composite foam according to Clause 9, wherein the bead-covered microspheres and / or the interstitial microspheres are composed of at least one of the following materials: glass, ceramic, polymer.

[0088] Clause 14. The composite foam according to Clause 9, wherein at least one of the reinforcing adhesive and the injection matrix is ​​composed of at least one of the following thermosetting or thermoplastic materials: epoxy resin, epoxy amine, epoxy acid base, silicone, vinyl ester, polyurethane, polyurea, polyester, cycloolefin, phenolic resin, polyimide, polybenzimidazole, polyetherimide.

[0089] Clause 15. The composite foam according to Clause 9, wherein the composite foam comprises 50 to 74 vol% of reinforcing polymer beads or reinforcing matrix cavities, 20 to 30 vol% of interstitial microspheres, and the remainder as the injected matrix.

[0090] Clause 16. A method for manufacturing composite foam, the method comprising the following steps: A certain amount of polymer beads are coated with a polymer-reinforced adhesive to form adhesive-coated polymer beads containing sorted beads covering microspheres; The reinforcing adhesive is allowed to cure or solidify in a manner that produces multiple individual reinforcing polymer beads; A certain amount of the reinforced polymer beads are placed in a mold; In the mold, a sorted amount of interstitial microspheres are distributed among all the reinforcing polymer beads to obtain a powder layer; The powder layer is injected into the mold using a polymer injection matrix; and The injected matrix in the powder layer is allowed to solidify or solidify in the mold, thereby producing the composite foam. The polymer beads are provided in one or more sizes, each having a width of 0.5 to 50 mm, and the beads cover the microspheres with a size distribution of ±20 μm or less.

[0091] Clause 17. The method according to Clause 16 further includes the following steps: At least one of the bead-covered microspheres and the interstitial microspheres is sieved in large batches to obtain a sorting quantity with a particle size distribution of ±20 μm or smaller.

[0092] Clause 18. The method according to Clause 16, wherein the step of coating the polymer beads with the reinforcing adhesive comprises the following steps: Place the polymer beads in a glass; The reinforcing adhesive is poured onto the polymer beads until fully coated, thereby forming adhesive-coated polymer beads; and While the glass is being rotated, the bead-coated microspheres are added to the adhesive-coated polymer beads until the aggregates of the adhesive-coated polymer beads physically break down into individual reinforcing polymer beads.

[0093] Clause 19. The method according to Clause 16, the method comprising performing the steps of: coating the polymer beads with bead-covered microspheres; placing the reinforcing polymer beads in the mold; and distributing the interstitial microspheres in all of the reinforcing polymer beads in a manner that produces the composite foam, wherein: The composition of the reinforcing adhesive and the injected matrix has a wall thickness at the narrowest point between at least 90% of adjacent pairs of polymer beads in the composite foam that is 4 to 15 times the diameter of the largest bead-covering microspheres and interstitial microspheres.

[0094] Clause 20. The method according to Clause 16, the method further comprising providing the reinforcing polymer beads, the interstitial microspheres, and the injection matrix in the following volume percentages: 50 to 74 vol% reinforced polymer beads, 20 to 30 vol% interstitial microspheres, and the remainder as the injection matrix.

Claims

1. A component for composite foams, said component comprising: A quantity of polymer beads of one or more sizes, with each polymer bead having a width of 0.5 to 50 mm; A polymer-reinforced adhesive configured to coat the polymer beads; A certain amount of bead-covered microspheres, at least partially embeddable in the reinforcing adhesive, and the reinforcing adhesive is configured to be cured or solidified in a manner that produces a plurality of individual reinforcing polymer beads; A certain amount of interstitial microspheres, wherein the interstitial microspheres are configured to be distributed within the powder layer of the reinforcing polymer beads; as well as A polymer-injected matrix is ​​configured to be injected into the powder layer of the reinforcing polymer beads and the interstitial microspheres, and the injection matrix is ​​configured to be cured or solidified in a manner that generates a composite foam. The bead-covered microspheres have a size distribution of ±20 μm or smaller.

2. The composition according to claim 1, wherein, The interstitial microspheres have a size distribution of ±20 μm or smaller.

3. The composition according to claim 1, wherein, The bead-covered microspheres and / or the interstitial microspheres have a width of 10 to 110 μm.

4. The composition according to claim 1, wherein, The bead-covered microspheres and the interstitial microspheres have a density of less than 0.6 g / cm³. 3 The density.

5. The component according to claim 1, wherein, At least one of the certain amount of bead-covered microspheres and the certain amount of interstitial microspheres is composed of at least one of the following materials: Glass, ceramics, polymers.

6. The component according to claim 1, wherein, The polymer beads are composed of at least one of the following thermoplastic materials: Expanded polystyrene foam, expanded polypropylene foam, low-density polyethylene foam, polyurethane foam.

7. The component according to claim 1, wherein, The polymer beads have a content of less than 0.1 g / cm³. 3 The true density.

8. The component according to claim 1, wherein, At least one of the reinforcing adhesive and the injection matrix is ​​made of at least one of the following thermosetting or thermoplastic materials. Composition: Epoxy resin, epoxy amine, epoxy acid and base, silicone, vinyl ester, polyurethane, polyurea, polyester, cycloolefin, phenolic resin, polyimide, polybenzimidazole, polyetherimide.

9. A composite foam, said composite foam comprising: Polymer injection matrix; A plurality of polymer beads of one or more sizes distributed throughout the injected matrix and at least one matrix cavity, each of the polymer beads and the matrix cavity having a width of 0.5 to 50 mm and being surrounded by a polymer-reinforced adhesive containing bead-covered microspheres, and each of the matrix cavities being partially occupied by polymer particles; as well as A certain amount of interstitial microspheres are distributed within the injected matrix, between the polymer beads or the matrix cavity. The bead-covered microspheres have a size distribution of ±20 μm or smaller.

10. A method for manufacturing composite foam, the method comprising the following steps: A certain amount of polymer beads are coated with a polymer-reinforced adhesive to form adhesive-coated polymer beads containing sorted beads covering microspheres; The reinforcing adhesive is allowed to cure or solidify in a manner that produces multiple individual reinforcing polymer beads; A certain amount of the reinforced polymer beads are placed in a mold; In the mold, a sorted amount of interstitial microspheres are distributed among all the reinforcing polymer beads to obtain a powder layer; The powder layer is injected into the mold using a polymer injection matrix; as well as The injected matrix in the powder layer is allowed to solidify or solidify in the mold, thereby producing the composite foam. The polymer beads are provided in one or more sizes, each having a width of 0.5 to 50 mm, and the beads cover the microspheres with a size distribution of ±20 μm or less.

Images