Abstract: Film, molded articles and fibers prepared from ethylene/&agr;-olefin interpolymer compositions are disclosed. The interpolymer compositions are blends prepared by combining specified amounts of a narrow molecular weight distribution, narrow composition distribution breadth index interpolymer, and a broad molecular weight distribution, broad composition distribution breadth index interpolymer, with each blend component having a specified density, melt index and degree of branching.

Abstract: A system and method for molding the shell of a medical device or other molded article is provided. The system includes a multi-axis rotational molding machine in which a mold is mounted. The mold has a cavity in the shape of the article to be molded. The mold seals to hold a vacuum. In operation, silicone or other molding material is inserted into the mold, vacuum is applied to the mold, the mold is rotated about at least two axes and a molding material coats the inside walls of the mold to form the shell or other desired article. A rotationally molded medical article is also provided.

Abstract: Anti-microbial activity is permanently applied to the surfaces of polyolefin objects by incorporating anti-microbial metals and metal salts into the surfaces. This is achieved by coating the selected surface of a preformed polyolefin part with the anti-microbial composition of this invention and then heating the surface of the object to fuse the coating into the polyolefin wall. Alternatively, the composition can be applied to the interior surface of a manufacturing mold at the start of the molding cycle from where it is incorporated into the wall of the molded object during its manufacture. The antimicrobial composition comprises from 0.5 to 5 weight percent of an anti-microbial additive in a hydrocarbon resin or polyolefin having a low melt index. This composition can be diluted with an organic or aqueous carrier for ease of application.

Abstract: This method for the manufacture of hollow bodies which do not contaminate the products contained therein, consists of maintaining the heat of molding of a hollow body, forming a container having an embouchure and produced by molding a first thermoplastic synthetic resin, in which there is applied in the interior thereof, a set amount of a second thermoplastic synthetic resin having a melting point lower than the temperature of the hollow body due to the residual molding heat thereof, after which the second resin is rotary molded within the hollow body, which acts as a mold, until the second resin, after being melted by the residual heat, has solidified forming a lining applied over the entire inner surface of the hollow body and the entire inner periphery of the rim of the embouchure.

Abstract: A method of manufacturing an optical disk includes spin-coating a substrate with a resin to form a light transmission layer without an additional cover. A spindle jig, which has a central shaft and is formed of a non-adhesive substance, is prepared. A resin is discharged on a surface of the spindle jig. The substrate is placed on the resin so that a recording layer of the substrate faces the spindle jig, and the substrate is spun to form the light transmission layer from the resin. The substrate, which is coated with the light transmission layer, is separated from the spindle jig. Accordingly, the resin is discharged not on a center of the substrate but around the center of the substrate. Thus, the additional cover is unnecessary, and thus a process of manufacturing the optical disk is simplified. Also, an entire surface of the substrate can be uniformly coated with the light transmission layer using the spindle jig and/or a dummy substrate formed of non-adhesive substances.

Abstract: This invention is an indicia transfer and method for its use to impart indicia to polyolefin objects during rotational molding. The transfer is a laminate of at least two, and preferably, three coats on a carrier sheet, which is preferably a flexible, transparent polymer sheet. The coats, as successive layers on the carrier sheet are: an optional backing coat of a backing-coat pressure sensitive adhesive, an indicia coat of a colorants in a graphic or alphanumerical array, and a top coat of a pressure sensitive adhesive. The pressure sensitive adhesive used for the backing coat has a transition melting temperature less than the surface temperature of the mold to which the transfer is to be applied while the top-coat pressure sensitive adhesive has a temperature sensitive adhesive which becomes tacky at the demolding temperature to enable transfer of the coats to the interior surface of a rotational mold.

Abstract: A molding process and apparatus are disclosed herewith including extruding a polymer from at least one nozzle into a mold cavity, and displacing at least one of the nozzle and the mold cavity during the step of extruding to deposit at least a portion of a layer of polymer into the mold cavity, and subsequently enclosing the mold cavity with a mating mold section to produce a molded part.

Abstract: An ocular lens having a desired shape without having a deformation induced by its process, and having a uniform coat layer on its surface, is proceeded by single mold polymerization. The ocular lens is produced by a process comprising a step of irradiating at least one part of the molding surface for the ocular lens of the mold with an excimer light, a step of coating a compound fixable to the ocular lens surface by an interaction with a polymerizable component in the ocular lens material, or its solution on the mold surface after irradiating with an excimer light, a step of filling the ocular lens material into the mold after coating, and polymerizing, a step of releasing a polymer obtained by the polymerization from the mold, and obtaining an ocular lens stock material having above-mentioned component fixed on its surface, and a step extracting unfixed unreacted components from obtained ocular lens stock material.

Abstract: A process for forming molded articles from particulate thermoplastic material, the process comprising: (a) providing a track having a plurality of process stations, (b) providing a mold assembly comprising a base, at least one hollow mold upstanding from the base, and guide means on the base for moving the mold assembly on the track, (c) preheating the mold assembly at a preheat station on the track, (d) moving the mold assembly from the preheat station to a transfer station on the track, (e) transferring the mold assembly from the transfer station to a molding station, (f) forming the molded articles by fusing particulate material to the at least one mold at the molding station, (g) transferring the mold assembly with the molded articles thereon from the molding station back to the transfer station, (h) moving the mold assembly from the transfer station to a cooling station on the track, (i) moving the mold assembly from the cooling station to an unloading station on the track, (j) removing the mol

Abstract: A mixture of a carrier and binder component and polymer powders is provided as a molding composition for sealing rotational molds or for reinforcing selected areas of rotationally molded parts. The carrier and binder component can be very low density polyethylene, petroleum jelly, hydrocarbon wax, hydrocarbon tackifier, or mixtures thereof, and the polymer powders are thermoplastics having a low melt index. The molding composition is applied to selected areas of the rotational mold, such as to the mating flanges of the mold halves to seal the parting line of the mold, or to areas within the mold where it is desired to have reinforced regions of greater wall thickness, such as ribs or bosses.

Abstract: A method of continuously forming integrally molded structures includes the steps of rotating a plurality of independently movable multisection mold assemblies about a plurality of axes, successively flowing a plurality of polymerizable mixtures over surfaces of each enclosed mold cavity while selectively heating mold sections thereof in a preselected heating profile and monitoring the flowing of each mixture, the heating of the mold sections and the formation of resins therefrom. The monitored mixture flowing, the mold section heating and the formation of each resin are coordinated with each monitored axis rotation. The molded structure is removed after it has achieved structural integrity within the mold cavity, and the steps are repeated to form a multiplicity of the integrally molded structures on a continuing basis. Also, multiaxis molding apparatus for conducting the above method.

Abstract: A method of forming a socket on a pipe of thermoplastic material is disclosed. In the process, an end section of the pipe is heated in a heating station. Then, the pipe is transferred to a socket-forming station having a socket-forming mandrel. This is followed by the socket-forming mandrel being introduced into the pipe end section, heated to a suitable socket-forming temperature, and the end section being formed into a socket. Prior to the pipe end section being heated in the heating station, a support is introduced into the end section in order to internally support the end section. The support remains in the end section after the socket-forming mandrel is introduced into the pipe and in the process the support is pushed deeper into the pipe.

Abstract: A method and apparatus for rotational molding provides a mold having first and second mold components defining therebetween a mold cavity. The first mold component includes a mold insert adapted to translated toward the second mold component to an inward position in the mold cavity. The first mold component includes spring assemblies for urging the mold insert inwardly, and a latch mechanism to restrain the mold insert in the outward disposition. The latch mechanism includes a touch pad which may be struck to trigger the latch mechanism and urge the mold insert inwardly into the mold cavity. In another aspect, the invention includes a method for rotational molding that employs the rotational mold described above. With the mold insert latched in the outward disposition, the rotational mold is separated and charged with thermoplastic material, closed and sealed, and placed in a furnace and rotated biaxially.

Abstract: A plastic canister for storing and shipping drill bits, especially roller cone drill bit, has a pin-holder built into the lid of the canister for ease of field dressing the bit. The lid and body of the container are slip fit to one another and indexed to each other for positive positioning in their relationship. Safety features include the use of a conductive plastic polymer, a non-rolling base, mating protrusions and recesses for stacking, recessed areas for strapping, and welded loop handles.

Abstract: Rotational moulding process for polymerizing or copolmerizing ethylene for manufacturing ethylene polymers or copolymers having a controlled particle size and morphology. Ethylene is polymerized or copolymerized under ethylene polymerizing conditions in the presence of a supported metallocene catalyst, where the average particle size of the catalyst particles is selected within the range of 14-40 &mgr;m and the residence time at the polymerization is selected so as to achieve a polymer where average particle size is between 0.2-0.5 mm and the proportion of fractions between 0.1-0.6 is at least 80%.

Abstract: Apparatus for extruding an elongated article comprising a die having an opening therethrough; an extruder for discharging extrudable material through said die opening; structure for rotational movement between said die and said extruder so as to provide said elongated article having a rotational profile.

Abstract: A core sphere or a wound-string core is held by a pair of bottom rollers and a pair of concave top rollers. Then, the bottom rollers are reciprocated in opposite directions respectively and rotated to rotate the core sphere or the wound-string core and wind rubber string, and a wound-string core of a predetermined diameter is obtained by pressurizing the core sphere or the wound-string core intermittently by the pair of top rollers with a predetermined pressure. Rotation frequency of the bottom roller is set to be 1100 rpm to 200 rpm, ratio of the rotation frequency of the bottom roller to number of the horizontal movement of the bottom roller is set to be 10:15 to 15:10, and ratio of pressurizing number of the top rollers to the number of the horizontal movement of the bottom roller is set to be 1:14 to 1:5.

Abstract: A variety of hollow structures with unique morphologies were manufactured with a rotational spinning technique. Phase separation of soluble solutions was induced within a filled mold as it was being rotated about one of its axis. As phase-separation occurs within this rotating mold, the increase in density of one phase results in sediment at the periphery under centrifugal forces. After or during sedimentation, gelation of the phase-separated particles fixes the tube morphology and the solvent remains in the center of the mold. The solvent is removed from the mold resulting in a tube. By controlling the rotational speed and the formulation chemistry, the tube dimensions and wall morphology can be manipulated. This technique offers a new approach to the manufacture of polymeric tubes. It requires small quantities of starting material, permits multi-layering of tubes, is applicable to diverse polymers and can result in highly diffusive hollow structures while maintaining good mechanical strength.

Abstract: A method for the production of a double-walled plastic container, comprises the following steps:

Abstract: A method is shown for manufacturing a polyethylene jacket of the type used in pre-insulated piping systems. A mandrel is first coated with a brittle polymeric coating. A melt profile of polyethylene is then extruded onto the mandrel and spirally wound to produce adjacent windings. The adjacent windings make contact to form a finished jacket which is in engagement with the brittle coating. After the jacket has set, an external compressive force is applied to the tubular member thus formed sufficient to crush the internal brittle coating, thereby freeing the polyethylene jacket from engagement with the mandrel. The jacket can then be removed from the mandrel.

Abstract: A multiaxis rotational molding apparatus includes a support portion, a molding portion and a control portion. The support portion includes an upstanding arcuate frame section. The molding portion includes an upstanding arcuate mold supporting assembly disposed within and spaced from the arcuate frame section. A mold assembly includes separable mold sections forming a substantially enclosed mold cavity carried within the mold supporting assembly. The control portion includes drive assemblies arranged in a preselected configuration adjacent the arcuate frame section selectively energized in coordination with adjacent drive assemblies for movement of the mold supporting assembly in a selected profile. Programmable memory stores preselected operating parameters. Monitors sense operating information form control components.

Abstract: A molded display form (i.e. a mannequin) or other article is provided, made of an elastomeric material having a pigment and/or dye mixed therein, said form having a selected uniform color throughout the thickness of said material. Any desirable color may be selected, e.g., skin color (to approximate that of any race) grey, tan, red, blue, yellow, metallic colors such as gold and silver, and mixtures thereof. White and black molded articles are also provided herein. The processes of this invention are especially suitable for producing articles having a uniform color throughout without streaking. The forms of this invention are non-brittle, resist burning, and stand up well to high temperatures. If they are scraped or chipped, the uniform color of the material throughout will make the injury less noticeable. The material is also soft enough that seam lines may eliminated by buffing with synthetic pads, and because of the uniform color of the material, there is no need to paint over the buffed surface.

Abstract: Disclosed and described is a tool for forming objects from clay. The tool, commonly referred to as a rib, comprises at least one irregular curved edge and a centrally located hole. The tool also comprises a curved taper region between the hole and the irregular curved edge.

Abstract: A method for embossing a cylindrical object such as a paint roller cover, especially using an apparatus that includes a shuttle and a rotatable shaft on the shuttle. The rotatable shaft includes two ends, with one end accepting a paint roller cover and with the other end being toothed for engagement with a gear rack. As the rotatable shaft is drawn in one direction by the shuttle, the toothed end engages the gear rack and rotates the rotatable shaft, thereby also rotating the paint roller cover. As the paint roller cover rotates, it is drawn by the shuttle over a die transfer plate having a design formed therein, and such design is transferred to the paint roller cover. The die transfer plate is heated to the desired temperature, and the speed of the shuttle is controllable so that time and temperature is controlled. Another controlled parameter is pressure.

Abstract: To make a seamless tube of polyimide, an amount of polyamic acid precursor to constitute the final tube is applied eveny as a solution to a cylindrical mandrel. The mandrel is rotated while a canted doctor blade smoothes the solution. The solvent is then expelled and the remaining precursor cured by heat.

Abstract: A method for manufacturing a transfer member suitable for use in an image forming system. A liquid polymer is applied to an internal surface of a rotating drum, spun flat, and cured in place. Additional components of the belt are applied to the rotating mold to form a multi-layered transfer member.

Abstract: Dendrimer additives incorporated in thermoplastic resins (such as polycarbonate resins) are effective to alter the surface characteristics of the thermoplastic resin. Such compositions can be injection molded to produce articles in which the dendrimer additive is concentrated at the surface of the article to alter the properties of the resin. By selection of the type of dendrimer additive, the resulting characteristics of the molded article may be controlled.

Abstract: A centrifugally cast hollow fiberglass reinforced plastic (FRP) column having angled corners and straight sides. Interiorly of the column adjacent each corner are angled corner fillers that have straight angled sides adhered to straight interior wall surfaces of the column adjacent the respective corners. During molding, the corner fillers are supported within the mold with their straight sides in parallel spaced relation to the straight interior walls of the mold adjacent the respective mold corners a distance slightly greater than the desired minimum wall thickness of the column, whereby when the mold is rotated, uncured FRP material within the mold will flow by centrifugal force into engagement with the interior walls of the mold and around the corner fillers into the space between the corner fillers and interior walls of the mold adjacent the respective mold corners to form a column having a substantially uniform FRP wall thickness.

Abstract: A method of manufacturing a screen device for permanent placement of a screen within a plastic structure. The method of manufacturing a screen device includes providing a mold comprised of an upper mold and a lower mold defining a mold cavity, positioning plastic within the mold cavity, positioning a screen upon a lower mold, securing the upper mold to the lower mold with the screen positioned within, performing rotational molding upon the mold, and removing the finished product from the mold. The finished product is comprised of a perimeter structure having an opening within with the screen completely enclosing the opening. The outer perimeter of the screen is molded directly into the inner wall of the finished product to prevent objects from passing about the outside portion of the screen.

Abstract: A method of making an article having a high moment of inertia and the article thus produced which method involves rotating a mold around a central axis, inserting higher density materials into said mold which will be centrifugally forced to the opposite ends of the mold. Then inserting a liquid which is less dense and which will fill the mold and after having infiltrated and attached to the first material that has been placed therein, will harden into solid form.

Abstract: A concrete column forming tube is provided for receiving poured concrete therein to produce a concrete column and which eliminates spiral seam lines and other undesirable characteristics on the outside surface of the formed concrete column and provides a construction which may be easily removed from the concrete column. The forming tube includes a spirally-wound cylindrical paper tube including multiple plies of paper adhered together, a centrifugally-cast plastic coating sprayed on an inside wall surface of the spirally-wound paper tube for producing an inside coated surface having a thickness and smoothness sufficient to eliminate spiral seam lines and other undesirable characteristics, and a tear strip positioned between the inside surface of the cylindrical paper tube and the plastic coating before centrifugal-casting and extending longitudinally of the forming tube over the entire length thereof and having a predetermined width and readily detachable from the plastic coating.

Abstract: A machine for casting radiation cured material with a mold set made of a clear, radiation cured material or other clear material, one or more radiation emitting devices preferably in the ultraviolet and visible range, a rotating mechanism to move the mold set from a horizontal or vertical load/unload position to vertical fill and cure position at the radiation devices, and one or more injection mechanisms attached to the mold set to fill the mold set and then seal at the part wall preventing cure of material in the line and resulting in a minimal gate mark. Alternatively the molds can be filled and then rotated before and during cure to create a hollow part.

Abstract: Simulated stone texture products are obtained when specially selected materials are properly admixed and formed via rotational molding. These products are manufactured from suitable molds according to a prescribed process methodology using synthetic polymeric materials instead of stone materials. Prerequisite surface textures are produced that effectively simulate the corresponding actual stone products.

Abstract: A molding arrangement and method, such as slush or rotational molding, for forming a thermoplastic shell or skin product. The mold arrangement includes a hollow mold housing provided with a mold shell thereon, which together define an air chamber located within the mold housing. A plurality of air flow control devices, such as centrifugal fans, are mounted within the mold housing and direct heated air into the air chamber through discharge channels defined within the mold housing. The mold arrangement also includes an elongate air supply and heating arrangement which generates heated air within the mold housing and along substantially the entire longitudinal extent thereof to effect uniform heating of the mold shell.

Abstract: A method of manufacturing a two-component skin by a “double slush” molding process is disclosed. In accordance with one aspect of the “double slush” molding process, after a first generally uniform layer of a moldable material that is at least partially cured is formed on a contoured surface of a mold, an additional amount of a moldable material is injected onto the at least partially cured first layer. Then, the mold is shaken to cause the additional moldable material to be generally evenly distributed on the first layer and form a second layer on top of the first layer. The mold also is heated to cure both the first and second layers and bond them together to form a two-component skin, shell, or body.

Abstract: A method of treating a disc plate. has the following operations of: molding a mold disc plate through an injection molding; and spinning the mold disc plate at a high spin speed. The spinning operation has at least one of the following two sub-operations of: reducing a warp of the mold disc plate with a centrifugal force caused during the spinning operation, and reducing a temperature of the mold disc plate during the spinning operation. Moreover, an apparatus of treating a disc plate has: a conveyer for conveying a mold disc plate obtained through an injection molding; a disc bench for receiving the mold disc plate conveyed with the conveyer; and a spin driver for spinning the disc bench when a temperature of the mold disc plate is higher than 90° C., to thereby spin the mold disc plate.

Abstract: A high impact resistant rotationally molded door and process for molding the door has the hinge post integrally attached to the rotationally molded skin of the door. A hinge member is provided that has a perforate U-shaped metal sheet bonded to preferably the upper portion of the hinge post. The sides of the U-shaped metal sheet are spaced sufficiently apart so that registration with the subsequently rotationally molded plastic skin of the door occurs. This hinge member at the perforate metal sheet rapidly heats during rotational molding. The perforate metal thus bonds to integrally mold with the skin of the door. This bonding occurs as the hinge post is molded within the hollow door construction along its hinging edge. The hinge member attaches at the perforate U-shaped metal sheet to the skin of the door while all other portions of the hinge post are free to move with respect to the door. The door is thus formed without door warping during curing and shrinking of rotationally molded plastic door body.

Abstract: Film, molded articles and fibers prepared from ethylene/&agr;-olefin interpolymer compositions are disclosed. The interpolymer compositions are blends prepared by combining specified amounts of a narrow molecular weight distribution, narrow composition distribution breadth index interpolymer, and a broad molecular weight distribution, broad composition distribution breadth index interpolymer, with each blend component having a specified density, melt index and degree of branching.

Abstract: A process for the production of polyolefin hollow articles comprises charging the polyolefin with a stabilizer combination comprising (a) at least one compound from the group of the organic phosphites or phosphonites, (b) one or more compounds selected from the group consisting of i.) hydroxylamine derivatives and ii.) amine oxide derivatives and (c) at least one compound from the group of the hindered amine stabilizers, filling this mixture into a mold, heating this mold in an oven to above 280° C., such that the stabilized polyolefin fuses, rotating the mold around at least 2 axes, the plastic spreading to the walls, and cooling the mold while still rotating, opening it and taking the resultant hollow article out.

Abstract: A method for forming a three dimensional polymeric structure includes providing at least one paint layer and providing a bonding layer coupled to the at least one paint layer to form an insert having a bonding surface provided by the bonding layer. A mold having a hollow interior bounded by an interior surface is further provided. The insert is positioned within the interior along a portion of the interior surface. At least one charge of thermoplastic material is deposited into the interior. The interior is heated while the mold is rotated and rocked. As a result, the thermoplastic material melts and is deposited against the interior surface of the mold and against the bonding surface of the insert to form a three dimensional structure within the interior. The three dimensional structure is then removed from the interior of the mold.

Abstract: Molding techniques and apparatus wherein at least one adjustable edge component can be used to alter the dimensions of the mold cavity between molding operations. Also disclosed are techniques for incorporating reinforcing composite elements into molded plastic parts. Most preferably, a rotomolding technique is used to fabricate a substantially homogenous composite panel for use as a partition or bulkhead.

Abstract: A method of producing magnetic recording disks includes positioning the disks between flat plates and increasing the temperature and pressure on the disks. Servo tracks are embossed on the disks by an embossing pattern on the flat plate. Servo tracks may be applied by a printing pattern on the flat plates. The flat plates are rotated during the process to relieve directional differences in the modulus of elasticity of the disk.

Abstract: An apparatus and method of manufacturing seal rings. The apparatus and method ensures that there is no wasted material during the manufacturing process and further ensures that the seal ring is manufactured to exacting standards without the need for any further milling processes. The apparatus and method has a mold which is heated and rotated at a predetermined rotation rate. A molten material is poured into the mold during the rotation thereof. The mold is then cooled and the rotation is decelerated so that the solidified material can be removed therefrom.

Abstract: The present invention provides a new and improved method of using a volatile liquid color system to prepare colorant-coated polymeric resin powders for use in rotational molding. The method according to the present invention includes simultaneously feeding polymeric resin pellets or granules and a volatile liquid color system into a grinding mill to produce a colorant-coated polymeric resin powder for use in rotational molding. During grinding, the volatile liquid color system coats the surface of the freshly ground polymeric resin powder and dries, leaving no residues that will volatilize during rotational molding or exude from the surface of rotationally molded parts during molding. The method of the present invention eliminates the need for additional processing steps after resin grinding, such as distributive mixing and drying. Rotational molded articles produced according to the present invention exhibit excellent color uniformity.

Abstract: A method for manufacturing a transfer member suitable for use in an image forming system. A liquid polymer is applied to an internal surface of a rotating drum, spun flat, and cured in place. Additional components of the belt are applied to the rotating mold to form a multi-layered transfer member.

Abstract: A bi-chromal ball production apparatus and method where the bi-chromal ball material is fed from opposite sides of the disk, reconfiguring the internal geometry of the apparatus, and precisely configuring the bi-chromal ball material feeding slit. The bi-chromal ball production apparatus has a disk that rotates, a first supply structure that supplies a first bi-chromal ball material to the disk from a first direction, a second supply structure tube that supplies a second bi-chromal ball material to the disk from a second direction and a motor that rotates the disk. The bi-chromal ball production apparatus includes a first reservoir and a first slit defined by the disk and a top body, a second reservoir and a second slit defined by the disk and a bottom body. An inner surface of each of the first and second reservoir is parabola shaped.

Abstract: Disclosed is a process for producing plastic parts, in which, with the aid of a heat-exchange medium, a mold is heated to the melting temperature of the plastic. As a result of rotation of a housing that carries the mold, the heat-exchange medium is brought repeatedly to the rear side of the mold and removed again. The heat-exchange medium used according to the invention is a thermally stable oil bath. The thermally stable oil is led through the feed line into the housing and contacts with the whole area of the rear of the mold. An inert gas blankets the oil in the housing. The oil is moved substantially turbulently as a result of the housing being rotated. The plastic powder is then applied to the mold in a manner known per se.

Abstract: Spherical particles having a diameter between 0.007″ and 0.040″ are formed from melt extruded thermo-plastic material suitable for casting on a heated mold surface and melting thereon to form a thin layer of material having a nominal thickness of 0.040″ that is cooled and removed from the mold surface as a part having a porosity less than a visually observable threshold. The process includes the steps of providing microspheres formed of blended and melt extruded thermo-plastic, plasticizers and pigment additives that constitute less than 5% by weight of the blend and shaped as a smooth round spherical particle; providing a heated casting surface and distributing a predetermined charge of such microspheres against the heated casting surface; melting the microspheres as a layer of thermoplastic material having a porosity less than 0.003 inches and thereafter cooling and removing the non-porous layer from the casting surface.

Abstract: A one-piece face mask with an integral inflatable cushion for use in providing an anesthetic to a patient. The mask has a dome shape outer wall terminating at its circumference in a thickened base on which the inflatable cushion is supported. The one-piece mask is formed by a combination of a rotational plastic molding process and gravity casting, which enables the different parts of the mask to be made of different thicknesses related to the function performed by the different parts in use of the mask.

Abstract: An improved rotational molding apparatus and method are provided for rotational molding of plastic articles having differently colored sections. The method and apparatus use a rotational mold having first and second mold shells separated by a removable partition member to form first and second interior spaces within the mold. A thin blade is held against the inner surface of at least one of the mold shells to define a plurality of compartments within the respective interior spaces. Differently colored molding materials, preferably plastic powders, are introduced into each of the compartments and caused to melt against the inner surfaces of the mold shells. The surfaces of the blade and the partition member are kept at a lower temperature than the inner surfaces of the mold shells to prevent the molding materials from melting against the surfaces of the blade and the partition member.