Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
  • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
  • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
  • B01D53/0407—Constructional details of adsorbing systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
  • B01J20/16—Alumino-silicates
  • B01J20/18—Synthetic zeolitic molecular sieves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
  • B01J20/28004—Sorbent size or size distribution, e.g. particle size
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/2803—Sorbents comprising a binder, e.g. for forming aggregated, agglomerated or granulated products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/28042—Shaped bodies; Monolithic structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/3007—Moulding, shaping or extruding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/3092—Packing of a container, e.g. packing a cartridge or column
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/02—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using gas only or vacuum
  • F16F9/04—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using gas only or vacuum in a chamber with a flexible wall
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/102—Carbon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/106—Silica or silicates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/10—Inorganic adsorbents
  • B01D2253/106—Silica or silicates
  • B01D2253/108—Zeolites
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/302—Dimensions
  • B01D2253/304—Linear dimensions, e.g. particle shape, diameter
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/302—Dimensions
  • B01D2253/306—Surface area, e.g. BET-specific surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/34—Specific shapes
  • B01D2253/342—Monoliths
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
  • B01D2258/06—Polluted air
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2220/00—Aspects relating to sorbent materials
  • B01J2220/50—Aspects relating to the use of sorbent or filter aid materials
  • B01J2220/66—Other type of housings or containers not covered by B01J2220/58 - B01J2220/64

Definitions

• the present invention relates to a monolith including an adsorbent material such as activated carbon and to a method of manufacturing such a monolith.
• the invention relates to a method of casting a monolith in a rigid housing, that itself may optionally comprise a component of equipment with which such a monolith is ultimately to be used, starting from a mixture comprising powdered binder and an adsorbent material that is treated to enable powdered binder and the adsorbent material to fuse, that is bond, together to thereby form a solid self-supporting adsorbent material-containing entity (an absorbent material monolith).
• adsorbent materials for example activated carbon and other adsorptive materials
• activated carbon and other adsorptive materials are used to change the behaviour of air springs.
• adsorbent materials in loose particulate form are inappropriate in such uses because they degenerate into (carbon) dust in use which may cause unwanted noise and block the pneumatic valves.
• Self-supporting monoliths of adsorptive materials have thus in the past been proposed.
• Such self-supporting monoliths of activated carbon have been used and these are typically produced by using high liquid binder volumes (up to 20% by weight) in a mixture with carbon- containing materials. Such a mixture is typically extruded at very high pressure of around 20- 50 tonnes into long cylindrical lengths of 2-6 metres. Thereafter, a piece is placed in an oven for curing and drying and a finished cylinder is then sawn down to size. Conventionally typical lengths of around 50-120 mm have been suggested for insertion into air spring parts.
• liquid binder used in the manufacture of these conventional monoliths is liable to interfere with and/or at least partially fill or block many of the pores which are present on the surface of the adsorbent material and this will compromise the ability of the adsorbent material to adsorb and control the volume of the gas in the end use application, such as a gas strut or air spring.
• a still further disadvantage is that it is difficult for a monolith manufactured according to conventional techniques to bond with other elements due to its highly porous surface. This has required a component to which the monolith is being fitted to be heat shrunk around it. Such heat shrinking manufacturing techniques have in the past required very fine manufacturing tolerances and have resulted in monoliths being potentially subjected to severe mechanical stress that could lead to fracture over time. Further, conventional techniques use high compression and a binder mixture combined with the mixture of powder and granular carbon, which although advantageously produces in a monolith that sheds few if any particles of carbon which is critical for the application, the high compaction and filing fraction also disadvantageously results in a part with high flow resistivity to air. This manifests itself as a rise in damping at higher frequencies of the springs operation (over 5Hz and particularly over 10Hz). Such damping effects is a key concern in the emerging market of activated carbon holding air springs.
• the chamber will form part of an end use item such as an air spring.
• a casting mould such as a Marshall mould can be utilised.
• adsorbent material-containing monolith comprising:
• the rigid housing comprises an air spring component or a mould of a desired predetermined shape.
• the air spring component comprises an air spring piston.
• the one or more adsorbent materials are porous adsorptive materials, such as carbon-, silica gel- and zeolite-containing materials.
• suitable adsorbent (or porous absorptive materials) materials have small, low volume pores that increase the surface area available for adsorption, and further ideally such materials are in any particulate form, for example selected from granules, powder, pellets, filaments and fibres.
• the one or more adsorbent materials comprise activated carbon (also known as activated charcoal).
• the activated carbon is preferably in powdered, granular or pelletised forms, and powdered and/or granulated forms of activated carbon are preferred.
• the mixture comprises around 8-18 weight % of one or more powdered binder materials and at least 90 weight % of a remainder of one or more adsorbent materials.
• the one or more powdered binder materials make up around 10-12 weight % of the mixture. It is desirable to use as little of the one or more powdered binder materials as possible to reduce the risk of compromising the adsorptive ability of the one or more adsorptive materials.
• the mixture comprises from 0 - 5 weight %, preferably 0 - 2 weight %, of a further component such as water or a catalyst to initiate and/or propagate the polymerisation and/or cross-linking (curing, solidification) of the binder material.
• the mixture is treated to facilitate the fusion (i.e. the bonding) of the one or more powdered binder materials with the one or more adsorbent materials. This may result in at least some or all of the one or more adsorbent materials being fused with the one or more binder materials.
• the treatment step provides an adhesive matrix which holds the adsorbent material.
• the treatment step involves the use of heat and/or electromagnetic radiation (for example, UV and microwave radiation).
• the method comprises treating the mixture by heating the rigid housing containing the mixture to a temperature which is a melting temperature associated with at least one of the one or more powdered binder materials, or up to 10 °C above said melting temperature.
• the treatment step comprises heating the rigid housing containing the mixture to a temperature of around 90-100 °C.
• the rigid housing (and therefore the mixture contained therein) is either heated at a suitable heating rate and/or is maintained at a constant temperature, as required, so that the one or more powdered binder materials are uniformly melted.
• the melting temperature associated with at least one of the one of more powdered binder materials is reached, it is maintained constant (or substantially so) for a period of between 30 seconds and 120 minutes.
• the treatment step used in the method of the present invention optionally comprises treating the mixture by irradiation with electromagnetic radiation and/or further heating it to a temperature above the melting temperature of at least one of the one or more powdered binder materials, for example to a temperature which is at least a cross-linking temperature associated with at least one of the one or more powdered binder materials.
• this involves heating the mixture to a temperature of at least 130°C, optionally to at least 150°C.
• the further heating involves heating the mixture to a temperature of between 130 °C and 500 °C, and highly preferably to a temperature of between 130 °C and 150 °C.
• the preferred method further comprises maintaining the temperature of the mixture at, or within 10 °C above, the cross linking temperature associated with at least one of the one or more powdered binder materials for at least 5 minutes, and further preferably for a period of time which ensures that the one or more binder materials are sufficiently cured to produce a self-supporting adsorbent material monolith. It is necessary to take account of the excellent thermal insulation properties of the adsorbent material, particularly when this comprises an activated carbon-containing material.
• the one or more adsorbent materials comprise particles that have a 30-70 or 40-60 or 50-70 mesh size, although fine powdered adsorbent materials that have a 100-325 mesh ( ⁇ 0.147mm) may be used, either in addition to, or as an alternative to, 30-70 mesh size particles.
• the particles of the one or more adsorbent materials have a greater than 1000 sqm/g BET surface area and optionally a greater than 1200 sqm/g BET surface area.
• the rigid housing comprises a piston component having an open mouth at a first end of the rigid housing and an open neck at a remaining end of the rigid housing, the method further comprising: locating a neck filling block in the open neck prior to providing the mixture in the chamber region.
• the method further comprises locating a filter fabric disc over the neck filling block and in an abutting relationship with an inner surface of the block flush with a turned in inner surface of the rigid housing.
• the method further comprises pouring the mixture into the chamber region in the housing over the filter fabric disc to fill the chamber region.
• the method further comprises pouring the mixture to over fill the chamber region by at least 5%.
• the method further comprises locating a cover over the mixture of powdered epoxy resin and adsorbent material.
• the method further comprises locating a weight element over the cover.
• the one or more powdered binder materials comprise one or more polymers and/or one or more pre-polymers for the preparation of thermoplastic-type and/or thermosetting-type materials.
• Suitable thermoplastic-type materials i.e. polymer materials which become soft and flexible at a certain temperatures and then solidify on cooling, include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybenzimidazole, acrylic, nylon and Teflon.
• Thermosetting-type materials are materials which form by irreversibly hardening (curing) the one or more p re- polymers using heat, radiation or a suitable catalyst to create extensive cross- linking between polymer chains to produce a polymer network.
• Suitable pre-polymers include polyesters, epoxy resins, phenolic resins, vinyl esters, polyurethanes, silicones, polyamides and polyamide-imides.
• the one or more powdered binder materials comprise one or more pre-polymer materials which can convert from a dry state to a liquid, become tacky/adhesive and thereafter set such as by cross linking.
• Preferred one or more pre-polymer materials comprise an epoxy resin.
• Particularly suitable epoxy resin-containing pre-polymer materials are commercially available from Axalta Coating Systems, however, other epoxy resin-containing materials are also be useful.
• the present Applicant has found that epoxy resin-containing powdered binder materials are particularly advantageous as their adhesion (i.e. fusion/bonding) to the one or more adsorbent materials is very strong and only a small quantity of epoxy resin-containing pre-polymer is required to produce the desired self-supporting monolith structure.
• apparatus for an air spring comprising:
• At least one casing element comprising a first and further end region and a wall member extending between the first and further end regions wherein at least one opening is provided in each of the first and/or further end regions;
• At least one body of composite material at least partially disposed within a cavity defined by an inner surface of the wall member, said body of composite material comprising at least one adsorptive material and at least one solidified powdered binder material.
• a self-supporting monolith comprising:
• At least one body of composite material comprising at least one adsorptive material and at least one solidified powdered binder material.
• an air spring comprising:
• At least one casing element comprising a first and further end region and a wall member extending between the first and further end regions
• the at least one mixture comprises at least one adsorptive material and at least one powdered binder material.
• a method of manufacturing a self-supporting monolith comprising:
• the at least one mixture comprises at least one adsorptive material and at least one powdered binder material.
• a free-standing self-supporting monolith cast using the above method will not be so tightly bound as a conventional monolith which may depending on use, cause it to shed an unacceptable quantity of particles through natural abrasion as the part is handled or mounted into a plastic part.
• the mould may be lined with a non-woven highly porous filter membrane, e.g. made from polypropylene felt.
• the one or more powdered binder materials When the one or more powdered binder materials are treated to convert them from a dry powdered state to a liquid they become tacky/adhesive, and this will allow the filter membrane to bind onto the outer surface of the monolith as it solidifies, thereby to cover the de-moulded monolith fully and to perfectly maintain its precise external dimensions.
• the self-supporting de-moulded monolith may be coated with a latex-containing composition.
• the method for manufacturing an adsorbent material-containing monolith comprises an optional further step of applying an layer of a latex-containing coating to the outer surface of the solidified body of composite material (i.e. the self-supporting monolith).
• the latex-containing coating layer has proven very effective to prevent any particles of the one or more adsorbent materials being rubbed loose from the outer surface of the monolith, for example either during de-moulding or when the monolith is inserted into the end-use component (e.g. the piston of an air spring).
• a latex-containing coating composition is applied using a hand operable spray gun with a diffuse pattern nozzle.
• the latex-containing coating composition is sprayed onto the outer surface immediately after demoulding the monolith, and further preferably whilst the monolith is warm, for example, just after the monolith is removed from the oven following curing.
• any suitable latex-containing coating composition may be employed although particularly suitable examples comprise an aqueous dispersion of at least one latex material derived from a synthetic, and optionally also a natural, source.
• One or more further optional components may also be included in the composition, such as one or more mineral fillers (e.g. chalk), one or more pigments and one or more auxiliary agents.
• the auxiliary agents are included to fine-tune the product features and are typically thickening agents, de-foaming agents, wetting agents, dispersing agents and preservatives.
• the latex-containing coating composition contains the following ingredients (% by weight):
• Natural resins Natural resin derivatives: 0 - 25
• the weight of latex-containing coating composition sprayed onto the outer surface of a typical monolith used in an air spring is approximately 5 g and this is conveniently achieved using around 6 -8 puffs from a hand operable spray gun. When dried, this will produce a latex- containing coating (rubbery latex residue) which weighs around 2 g.
• the latex-containing coating layer is typically extremely thin and invisible to the naked eye.
• Certain embodiments of the present invention provide a method of manufacturing a self- supporting monolith comprising one or more adsorptive materials.
• the adsorptive material comprises activated carbon.
• the monolith can be manufactured in situ within a chamber/cavity region of a component where that monolith is ultimately to be located (for example, in situ within the piston component of an air spring or gas strut) or alternatively can be manufactured in a mould and thereafter moved and positioned at a desired location.
• Certain embodiments of the present invention enable the particles of the one or more adsorbent materials within the final (solidified) monolith to be spaced far apart.
• the provision of relatively large inter-particular voids results in a significant reduction in damping at higher frequencies.
• Certain embodiments of the present invention provide a free-standing monolith which is not so tightly bound as a conventional monolith of adsorbent material.
• Figure 1 illustrates preheating of a rigid housing formed by an air spring component such as a piston
• Figure 2 illustrates blocking an open neck of a preheated piston
• Figure 3 illustrates a mixture of powdered binder and adsorbent material held within a chamber region of the rigid housing which is a piston component of an air spring, a sacrificial cover located over said mixture and a weight applied on top of the sacrificial cover;
• Figure 4 illustrates the parts shown in Figure 3 after a heating and cross linking stage of the present invention
• Figure 5 illustrates a piston and associated activated carbon monolith
• Figure 6 illustrates an alternative embodiment of the present invention in which a monolith is not formed in situ with a component but rather is formed as a discrete monolith beatable at another desired location;
• Figure 7 illustrates the lining of a mould sidewall
• Figure 8 illustrates a dry mixture and cover in a mould
• Figure 9 illustrates a lid for the mould
• Figure 10 illustrates a lid compressed into the mould
• Figure 1 1 illustrates how sidewall material can be folded to create a self-supporting monolith
• Figure 12 illustrates how lids for multiple moulds of the type illustrated in Figures 6-1 1 may alternatively be provided by a single unit including multiple spaced apart cylindrical drivers as part of a single drive lid.
• Figure 1 illustrates how a rigid housing 100 can be preheated in an oven 1 10 or other such heating zone according to certain embodiments of the present invention.
• the rigid housing shown in Figure 1 is a piston of an air spring. It will be appreciated that certain embodiments of the present invention are applicable to use with a wide variety of a rigid housings or more broadly to the creation of a monolith including adsorbent material which can be located in a housing.
• the rigid housing shown in Figure 1 is a piston which enables a monolith to be provided in situ. That is to say the self-supporting monolith is manufactured in a final position within equipment in which it will be utilised.
• the rigid housing which is preheated may be a mould such as a Marshall mould in which a monolith can be created and thereafter transferred to a position for use.
• the oven 1 10 includes an oven floor 120 on which the rigid housing 100 can be located.
• User input devices 130 such as buttons, knobs or touch screen displays can be utilised to control temperature settings and timings so that the rigid housing is preheated to a desired temperature. This preheating occurs so that when a mixture is subsequently added and thereafter heated to melt and cure the mixture, shrinkage does not occur against relatively cooler walls of the rigid housing.
• Figure 2 illustrates the rigid housing 100 taken out of the preheating oven and located on a support surface.
• the support surface 200 may optionally be a part of the oven floor which is removable from the oven. Alternatively a support element 200 may be a separate element which is put in the oven and thereafter removed so as to reduce risk of thermal shock.
• the support 200 provides a lower end 210 of the rigid housing 100 with support.
• the rigid housing is a piston having an open neck 220 at a first end and an open mouth 230 at a remaining end.
• the open neck is filled with a neck filling block 240.
• This block is shaped and sized so as to substantially fill the open neck and an inner surface 250 of the block lies flush with an inner surface of the rigid housing surrounding the opening of the neck.
• a filter fabric disc 260 is located over the block.
• the piston wall defines an internal chamber 270.
• Figure 3 illustrates how a mixture of powdered epoxy resin and adsorbent material 300 is provided in the chamber region 270 of the piston.
• the powdered epoxy resin is an example of a powdered binder.
• a binder can convert from a dry state to a liquid, become tacky/adhesive and thereafter set such as by cross linking.
• the mixture provided can optionally overfill the chamber. This is because subsequently the mixture will reduce in volume and the overfill helps ensure that the end result substantially fills a desired volume of the chamber region of the piston.
• Figure 3 also illustrates how a cover 400 can be located over the mixture of powdered epoxy resin and adsorbent material.
• the cover 400 can act as a sacrificial element.
• Figure 3 further illustrates how a mass 500 which provides a weight is thereafter located over the cover 400 to lightly compress the mixture of powdered epoxy resin and adsorbent material.
• the cover 400 has an outer circumference (or outer periphery if a generally circular cross section piston is not used as the rigid housing) which is selected and configured to match with the inner circumference provided by the rim at the open mouth of the rigid housing.
• Figure 4 illustrates the elements shown in Figure 3 subsequent to a heating and curing step.
• the mixture of powdered epoxy resin and adsorbent material is heated which melts the resin material.
• This provides an adhesive matrix holding adsorbent material.
• the adhesive matrix is formed from a mixture of around 8-18% epoxy resin powder and a large proportion of adsorbent material.
• 8-18% epoxy resin powder can be matched with 92-82% of adsorbent material.
• Aptly a small percentage of up to 10% of additional material can be added to assist various aspects of the end product.
• the mixture reduces in volume and the mass helps urge the collapsing mixture into the chamber region within the rigid housing.
• the cover eventually comes to rest within the confines of the open rim of the rigid housing. This helps provide a flat surface.
• Figure 5 illustrates an end product with the piston containing a monolith 600 inside the piston (rigid housing).
• the block is removed and the piston is closed by a cover 700.
• Certain embodiments of the present invention use a relatively low amount of powdered epoxy resin mixed into a highly activated granular carbon, with no carbon powder.
• the mix is then poured into the air spring cavity and cured in situ, without the need for compression, other than a small weight used to help the mix fill out the cavity. This is because the powdered resin melts into liquid before curing. During this phase the mixture becomes plastic, causing the particles to adhere more closely together. This leads to some shrinkage.
• the capping of the mix with a small weight during this plastic phase stops the monolith mix from shrinking away from the walls, and keeps it adhered to them.
• the resulting monolith features relatively large inter-granular voids, compared to a monolith formed under high pressure and including carbon powder. This results in a significant reduction in damping at higher frequencies.
• a free-standing monolith cast using this method will not be so tightly bound as a conventional monolith which may depending on use, cause it to shed an unacceptable quantity of particles through natural abrasion as the part is handled or mounted into a plastic part.
• this issue can be overcome in various ways.
• Either the mould is lined with a polypropylene felt with a melt temperature less than 20°C higher than the monolith curing temperature, causing it to become tacky during curing.
• This in conjunction with the binding action of the epoxy powder within the monolith mix, allows the non-woven but highly porous filter membrane to bind onto the monolith during curing, fully covering the part but perfectly maintaining its precise external dimensions as it emerges from the mould.
• the self-supporting de-moulded monolith is coated with a latex-containing composition, as described above.
• the monolith mixture is cast directly into the plastic part, fully occupying the cavity so that its surfaces are not exposed to abrasion, according to the steps below.
• Step 1 (fig 1 ) - Heat the piston part to between 120 and 150°C in an oven for at least 10 minutes, to cause it to expand slightly and activating the surface to become receptive to bonding with the monolith binder.
• Step 2 Placing the piston upside down on a flat surface, insert a circle of non-woven filter material over the narrow opening at the base, using a prop disc underneath to minimise sag.
• the filter circle is a tough, needle-punched geotextile material with an open porosity and around 2.5mm thick, made from polypropylene fibres, with a melt temperature of around 170°C - only 15°C higher than the monolith’s curing temperature. This causes the fibres of the filter circle to become tacky, and better able to bind onto the monolith mixture.
• Step 3 (fig 3) - Weigh out the requisite amount of monolith mixture.
• the mixture shall be made of high-activity activated carbon material, comprising an approximate mesh size of 30/70, mixed in with a fine epoxy resin powder, with a ratio of around 10-15% by weight. No activated carbon powder is included, because it will add to air resistivity in the component when cured, causing air damping.
• the measured mix amount is then poured on top of the filter circle in the piston cavity, such that it overfills the piston, forming a mound that is proud of the top face of the part.
• the binder used is the Teodur E epoxy by Axalta. Other binder materials could of course be utilised. Aptly the binder converts to liquid when heated. Aptly the binder becomes tacky when heated. Aptly when heated beyond an activation temperature cross linking of the binder occurs to cure/set the binder. Aptly the binder when in liquid format spreads out and flows. Aptly the binder binds the monolith firmly without any significant compression being needed and without masking pores of the adsorbent material. Aptly the binder forms large numbers of tiny adhesion points when powder particles melt.
• the adsorptive material used can optionally be activated carbon. Aptly the activated carbon used is Cabot GCN3070 carbon. Aptly this has an average grain size of 0.5mm. Optionally the adsorptive material particles used have a narrow grain size distribution. This helps avoid small particles packing into voids left by bigger particles and thus helps to minimise airflow resistivity.
• the felt used for the filter circle can optionally be a geotextile material HPS 2.5 needle punched non-woven provided by GeoFabrics. Other materials which help prevent outgress of material and which act as protective layers can be utilised.
• Step 4 (fig 3) - Place a second filter circle on top of the mound.
• Step 5 (fig 3) - Place a weight, weighing around 1-3Kg, on top of the filter circle.
• Step 6 (fig 4) - Place the elements into the oven, now turned up to 155°C.
• the binder itself requires just 7 minutes to cure, but the monolith structure is deep and thermally insulating, so allow at least 40 minutes in the oven at this temperature.
• the binder in the monolith mix When the part is removed from the oven, the binder in the monolith mix will have liquefied before curing, so reducing the physical volume of the monolith mixture. The weight will therefore have sunk onto the lugs protruding from the face of the piston base, with the surface of the geotextile felt left perfectly flush with the top face of the lugs. This means that only a controlled amount of light compaction will have occurred, thereby allowing the particles to remain relatively uncompacted, so minimising air damping.
• Step 7 (fig 5) -
• the base-plate of the piston is thermally welded to the component around the rim and against the lugs.
• the lugs will partially melt during this process, causing the plate to become pressed against and thermally fused to the surface of the geotextile felt, which now acts as a 2mm thick shock absorbing spacer material, maintaining load against the underside of the carbon monolith.
• the walls of the piston shall shrink in line with the shrinkage of the monolith material itself, meaning that adhesion of the monolith material against the walls is preserved. Any movement of the monolith within the part is further prevented by the geotextile layer being pressed upwards against the underside of the monolith during the base plate welding process.
• Figure 6 illustrates an alternative embodiment of the present invention and illustrates a method of manufacturing a monolith element utilising a mould.
• a mould 800 has a base 810 and sidewall 820. Alternatively the base and sidewall may be integrally formed.
• the mould is lined with a liner.
• the mould 800 is first lined over its base with a polypropylene felt 825 which covers the base and slightly upstands from the base a small distance towards an open mouth 830 of the mould.
• the mould can be preheated to help avoid any subsequent contraction effects when a mixture added is melted and cured.
• An alternative liner may be used to prevent the melted binder material from sticking to the wall of the mould and may comprise a non-stick paper material of a type similar to that used in domestic baking; a PTFE coated non-stick paper material is preferred.
• PTFE is quite soft therefore it is further preferable to use a PTFE coated steel mould.
• the mould itself is made from a PTFE material, ideally 1-2 cm in thickness.
• Figure 7 helps illustrate how a sidewall of the mould can be covered by a further felt sheet 900 which is wrapped around the inside of the mould to help produce the liner. As illustrated in Figure 7 this strip of felt overlaps at its ends so that the whole of the inner surface of the mould is covered by the felt.
• Figure 8 helps illustrate how a mixture 1000 of powdered binder and adsorbent material is added to the mould and then a further disc of felt 1010 is added to cover an upper surface of the mixture.
• Figure 9 helps illustrate how a lid 1 100 can then be located through the open mouth of the mould.
• Figure 10 helps illustrate how the mixture and mould can thereafter be heated to melt the powdered binder and adsorbent material mixture. As this occurs the lid is compressed.
• Figure 1 1 helps illustrate how subsequent to heating and curing the upper ends of the felt liner can be folded down to cover the upper peripheral edge of the resultant monolith 1300.
• Figure 12 illustrates an alternative embodiment of the present invention similar to that shown and described with respect to Figures 6-1 1 but in which multiple monoliths can simultaneously be manufactured using a common lid and pressing piece and by simultaneously heating the moulds as desired.
• the inside of the mould is lightly greased with a petroleum jelly such as Vaseline.
• Two disks of polypropylene non-woven filter material between 0.3 mm and 1 mm thick are cut out.
• One disk has a diameter 10-20mm wider than the diameter of the mould. This is forced by hand to the base of the mould, such that there is an up-stand of material around the edge of around 5-10mm.
• a rectangle of the same filter material is dressed around the inner face of the walls of the mould such that a 10mm overlap is achieved.
• the rectangle is deliberately applied over the upstand tab of filter material protruding from the floor.
• the height of the wall membrane should be at least 20mm greater than the desired height of the monolith.
• the two membrane elements are then flamed together using a hand-held blow torch, as used in catering applications.
• the monolith mix is poured in, forming a mound that is higher than the desired monolith height.
• a smaller diameter disk of the filter membrane is placed on top of this mound, cut to fit within the inner diameter of the mould wall once it is dressed with the filter membrane.
• a weighted lid of a similar diameter to the smaller disk is then added on top.
• the lid shall be at least 40mm thick, and feature a stepped profile such that an upper section shall be broader than the internal diameter of the mould.
• a number of such cylinders may be placed adjacent to each other, and a single heavy lid be placed on top of them with multiple cylindrical upstands protruding underneath (a bit like a giant upside down Lego brick).
• the weighted lid shall eventually come to rest on the shoulders of the mould during curing, ensuring a perfect monolith height with a guaranteed light level of compaction.
• Curing shall occur at 155°C for 40 minutes, as with the other method.
• the monolith that eventually emerges from the mould will be wholly encapsulated by filter membrane, with an upstand of membrane of 10-15mm around the top edge. This membrane can be folded against the top surface and fused to the top membrane using the chef’s blow torch.
• the method ensures high precision authority over the diameter and height of the finished part, because both the monolith and the membrane coat have been formed within the mould under light compression.

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• 2018
  • 2018-07-06 GB GBGB1811101.3A patent/GB201811101D0/en not_active Ceased
• 2019
  • 2019-07-05 EP EP19737710.4A patent/EP3817854A1/de not_active Withdrawn
  • 2019-07-05 WO PCT/EP2019/068185 patent/WO2020008072A1/en active Search and Examination

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