Abstract: A process and a device are described for the continuous production of block foam by the foaming of a mixture which reacts to form polyurethane and which contains carbon dioxide dissolved under pressure, wherein the pressure of the reactive mixture is reduced on passing through a pressure reduction zone in the form of an aperture, and blockage of the aperture is prevented by the relative movement of the aperture-delimiting faces with respect to each other.

Abstract: An extrusion system utilizes single or tandem extruders and a mixer-cooler to extrude a foamable extrudate through a die in a sealable chamber. The foamable extrudate is shaped and calibrated within the chamber. The die is mounted on the end of a gel tube projecting through a gland seal in a fixed bulkhead forming the upstream end of the chamber. The gel tube and mixer-cooler are mounted on a movable carriage, movement of which may be used to adjust the die with respect to shaping and calibrating equipment inside the chamber. The mixer-cooler achieves a selected narrow range of uniform viscosity of the melt at the die depending on the size of the product and density. The chamber is preferably a vacuum chamber producing low density foams. The product exits the chamber to atmosphere on a continuous basis through a submerged orifice in a water baffle immersion seal.

Abstract: A foam extrusion assembly having a melt region which receives and melts a plurality of material pellets, an agent addition assembly which adds a foaming agent to the melted material pellets, and a mixing assembly which substantially mixes the melted material pellets and the foaming agent with one another. The mixing assembly includes a generally elongate barrel through which the melted material pellets and the foaming agent are urged generally from an inlet to an outlet of the barrel.

Abstract: An extrusion system utilizes single or tandem extruders and a mixer-cooler to extrude a foamable extrudate through a die in a sealable chamber. The foamable extrudate is shaped and calibrated within the chamber. The die is mounted on the end of a gel tube projecting through a gland seal in a fixed bulkhead forming the upstream end of the chamber. The gel tube and mixer-cooler are mounted on a movable carriage, movement of which may be used to adjust the die with respect to shaping and calibrating equipment inside the chamber. The mixer-cooler achieves a selected narrow range of uniform viscosity of the melt at the die depending on the size of the product and density. The chamber is preferably a vacuum chamber producing low density foams. The product exits the chamber to atmosphere on a continuous basis through a submerged orifice in a water baffle immersion seal.

Abstract: An apparatus for molding a continuous foamed plastics element (2), such as a floor construction member of the type comprising a substantially parallelepipedic central body (3) and at least one lateral projection (5,6), includes a mold (13) comprising a forming chamber (13a) and a stabilization chamber (13b) defined between a bottom wall (22), a pair of opposite side walls (20,21), and a cover (23). Advantageously, the cover (23) and/or one or both the side walls (20,21) of the mold (13) comprise a plurality of structurally independent segments which may be adjustably positioned toward and away from the bottom wall (22) of the mold (13) for independently adjusting, in a substantially continuous manner, the height of the molding seats of the central body (3) and/or of the lateral projection (5,6) of the continuous element (2) in each of the forming (13a) and stabilization (13b) chambers of the mold (13).

Abstract: A vacuum extrusion line of the horizontal barometric leg type includes a vacuum chamber having an extrusion die at one end and a water baffle immersion cooler at the other end for extracting the extrudate to atmosphere, extrudate shaping and sizing equipment downstream of the die, a large diameter fixed bulkhead at the die, and first and second large diameter movable sections surrounding the shaping and sizing equipment, a smaller fixed section of the chamber. The first section sealing against the second section and the fixed section and telescoping over the fixed section to form a gap with the second section being movable within the limits of the gap. The second section also seals against the large diameter fixed bulkhead. In this manner the downstream equipment can be fully exposed by movement of one or both movable sections and adequate volume and spatial working environment is provided for large through-put. A simplified lock mechanism facilitates the quick opening and closing of the chamber.

Abstract: A system for producing blocks of open-cell, flexible polyurethane foam material and for conditioning each freshly-manufactured block to impart thereto optimal flexible foam properties. The system includes means to pour the flowable constituents of the foam material to be manufactured into a production station at the inlet of a conveyor, the constituents interacting to create on the conveyor a block of open-cell flexible foam material which is then wrapped in a plastic film casing that exposes the leading and trailing end of the block so that the encased block is open ended. The conveyor transports the wrapped block toward the rear end of a gate in a conditioning station having a port therein whose front end is coupled by an air duct to a suction fan.

Abstract: An apparatus and process for producing polymeric foam, wherein reactive foam components and a low-boiling point frothing agent are brought together, sufficient pressure is applied to maintain the frothing agent in a liquid state and the mixture is passed through a permeable discharge head through which the mixture is discharged and wherein the pressure is reduced and froth is formed. The discharge head comprises one or more diffuser elements (80) having a structure such as to require division, divergence and convergence of flow paths in three dimensions within the axial thickness of the diffuser element, considered in the direction of flow therethrough. The diffuser element (80) is made of bonded, or sintered or sintered composite material, such as sintered wire.

Abstract: A formed laminate (20) is made by a method and apparatus (38) by compressing a flexible sheet (28) and a foamable liquid mixture (50) that has substantially completed expansion but not yet substantially cured so as to form the flexible sheet and provide a collapsed foam layer (30) bonded to the sheet. The flexible sheet (28) is preferably porous cloth, vinyl or leather. A film (56) which is preferably a nonadherent plastic such as polyethylene is preferably positioned in a vertically spaced relationship with the flexible sheet (28) either above or below the flexible sheet with the foamable liquid mixture received therebetween for the expansion prior to the compression that provides the formed laminate. The formed laminate (20) has particular utility as an article of apparel (22) and is preferably made by a quick reacting type foamable liquid mixture (50) which expands in about 8 to 25 seconds and most preferably in about 10 to 15 seconds.

Abstract: In a process for extruding polymer melts (25) to form hollow chamber sections (21) by pressing the polymer melt through a shaping tool (24) with an internal shaping mandrel (26) and by subsequently sizing and cooling the hollow chamber section strand in a sizing and cooling unit (31) it is provided for the sizing and cooling of the hollow chamber section strand to be carried out in the sizing and cooling unit under extrusion pressure. A device for carrying out this process is characterized in that shaping tool (24) and sizing and cooling unit (31) are rigidly connected to form a closed system so that the strand extrusion pressure prevailing in the shaping tool can be propagated into the sizing and cooling unit, and that the shaping mandrel (26) protrudes out of the shaping tool (24) into the sizing and cooling unit (31).

Abstract: The subject invention pertains to an apparatus with the continuous expansion of thermoplastic minipellets, particularly polypropylene. The apparatus comprises a mixing means for mixing the thermoplastic minipellets in water to form a slurry, which is connected to a pressurizing means to form a flow of pressurized slurry to a junction which in trains a blowing agent to form a pressurized slurry mixture, which is connected to a heating means to heat the pressurized slurry mixture. Once the pressurized slurry mixture is impregnated with the blowing agent, it flows through water more orifice plates for expansion of thermoplastic minipellets into an expansion vessel.

Abstract: The invention relates to a process for the manufacture of new shaped parts, preferably made from chipboards, wherein a mass formed from at least a binder and a small-particled material brought into contact with this binder is subjected to extrusion at elevated temperature and pressure. In the process according to the invention, a mass possessing a total moisture content of 6 to 25 wt. % or adjusted to the stated moisture content and made up of at least one biopolymeric preferably starch-containing binder, which converts into a melt and/or gel at extrusion temperatures and pressures, and further made up of the small-particled material, is subjected to extrusion and immediately thereafter undergoes decompression and spontaneous expansion.

Abstract: A process and a device are described for the production of polyurethane foam by application of a froth onto the conveyor belt of a block-foam installation, whereby the froth is applied onto the lower conveyor belt in a free, substantially vertical fall and flowing of the froth contrary to the direction of movement of the conveyor belt is prevented by a stationary, substantially vertical barrier arranged transversely on the conveyor belt.

Abstract: A method and device for continuously producing slabstock polyurethane foam wherein a polymerizable reaction mixture containing a blowing agent is applied onto a moving conveyor and allowed a free rise expansion and polymerization within a substantially closed space. The pressure in this space is maintained within a predetermined pressure range by continuously supplying gas to the space, in addition to the blowing gas produced by the reaction and by simultaneously exhausting gas from said space. In this way, pressure fluctuations are reduced in the space and further parameters such as the temperature can be controlled so as to enable production of a foam with constant properties.

Abstract: An apparatus for molding a continuous foamed plastic element, such as a floor element having a substantially parallelepipedic central body and at least one side lug, includes a mold in which respective molding cavities of the central body and of the side lug are defined between a bottom wall, a pair of opposite side walls and a cover. A mechanism adjustably positions at least one of the cover and one or both of the side walls of the mold, away from and towards the bottom wall, to regulate, in an adjustable and substantially continuous manner, the height of the molding cavities for at least one of the central body and the at least one side lug of the continuous element.

Abstract: An extruder projects through a bulkhead adapted to form part of a vacuum chamber, and a die is mounted on the end of the extruder within the bulkhead. The extruder projects through a gland seal which is formed in a sleeve surrounding the extruder. The seal includes a plurality of seal rings surrounding the extruder and packed in the sleeve and held in place in a preferred from by a yieldable retainer. A shaper is positioned downstream of the die and is clamped to the upstream end of the die. The shaper is mounted on tracks on a girder extending from the bulkhead clear of its periphery. The apparatus permits congruent axial movement of the extruder, die and shaper with respect to the bulkhead.

Abstract: A horizontal vacuum extrusion line includes a fixed bulkhead, a die inside the bulkhead, a telescoping vacuum chamber section and a fixed chamber section. A dam in the fixed section forms a pond for immersion cooling of the extrudate. A truss extends from the dam to the bulkhead supporting, shaping and calibration equipment and extends through the telescoping section. Fluid pressurizable seals at each end of the telescoping section are operable after the telescoping section is closed against the bulkhead and the telescoping and fixed sections are locked together. The telescoping section provide a more compact line and easier access to the complex equipment downstream of the die. The extrudate from the die passes down into the pond and then through an orifice in a hood projecting from the chamber into a lower level portion of the pond exposed to atmosphere. The hood also includes a tractor drive to push the extrudate through the underwater orifice.

Abstract: An apparatus are described for extruding a soft, low density elastomeric thermoplastic foam. A single screw extruder having a very large screw length to diameter ratio is provided to thoroughly mix the thermoplastic elastomer with a blowing agent. A thin, substantially taperless die is also provided to form extruded profiles. By using such an apparatus, a variety of complex-shaped extruded profiles may be easily produced.

Abstract: Foamed plastic is applied on a roof substrate by progressively dispensing expandable plastic foam material on the substrate along a path and progressively confining the vertical and lateral expansion of the material along the path and relative to the substrate. Apparatus for applying the foamed plastic comprises a platform having opposite ends and opposite sides having an endless belt supported on the platform for displacement relative thereto in the direction between the opposite ends. The belt is supported above the roof substrate by laterally spaced rails or by tracks on the belt, and a motor is provided on the platform for driving the belt to move the platform along the path. A dispensing gun is supported on the front end of the platform for dispensing expandable plastic foam material onto the substrate ahead of the belt and vertical and lateral expansion of the material is confined by the belt and rails or tracks as the platform moves along the path.

Abstract: A process and a system for the continuous manufacture of polymeric foams. Reactive chemical components and additives comprising a low boiling blowing agent are mixed under pressure; the mixture is then frothed before chemical reaction takes place by feeding the mixture through a pressure equalizing and frothing device having a pressure-drop zone opening into a frothing cavity having an output aperture to discharge the froth onto a moving substrate.

Abstract: A process and a system for the continuous manufacture of polymeric foams. Reactive chemical components and additives comprising a low boiling blowing agent are mixed under pressure; the mixture is then frothed before chemical reaction takes place by feeding the mixture through a pressure equalizing and frothing device having a pressure-drop zone opening into a frothing cavity having an output aperture to discharge the froth onto a moving substrate.

Abstract: A process and a system for the continuous manufacture of polymeric foams. Reactive chemical components and additives comprising a low boiling blowing agent are mixed under pressure; the mixture is then frothed before chemical reaction takes place by feeding the mixture through a pressure equalizing and frothing device having a pressure-drop zone opening into a frothing cavity having an output aperture to discharge the froth onto a moving substrate.

Abstract: An apparatus 1 for widening a foam sheet S obtained immediately after heating and foaming a foam sheet which has not been yet widened, while the foam sheet S is continuously received or supplied. The sheet widening apparatus 1 comprises: a pair of chains 2 constructed in the form of endless chains composed of links 22 having pin parts 21 and a driving device 3 meshing with these chains 2 and driving the chains 2 along such loci as to widen the space between the chains 2 from sheet receiving start points to sheet receiving end points. A method for widening a foam sheet by the sheet widening apparatus 1 comprises the steps of piercing both the side parts of the foam sheet S with the pins 21 at the sheet receiving start points; widening the space of width between the pins 21 along gently curved loci by drying the chains 2 while the pins 21 penetrating the foam sheet; and receiving the foam sheet S from the sheet receiving start points to the sheet receiving end points while the foam sheet is widened.

Abstract: The invention is directed to an apparatus for the production of polyurethane moldings endless in one dimension using at least two alternately operated mixheads for the reactive polyurethane components. Material which has been correctly conditioned by circulation of the reactive components through the mixhead not in operation arrives at that mixhead at least before it is put into operation and the components are delivered by units which are common to the mixheads, but independent of one another in regard to "mixing" and "conditioning".

Abstract: Disclosed is a method for providing accelerated release of a blowing agent from a solid, non-perforated plastic foam. The method relates (a) providing the solid, non-perforated plastic foam having the blowing agent and a permeability modifier therein and (b) perforating the foam at its surface to form a multiplicity of channels extending from the surface into the foam. The channels are in gaseous communication with the environment outside the foam and provide accelerated release of blowing agent.

Abstract: An apparatus for producing expanded thermoplastic microspheres, including a belt conveyor (A) having an endless belt (1) for conveying microspheres. A device (B) for infrared (IR) heating, including a plurality of IR lamps (4) is located above the belt (1). A dosing device (C) for the dried unexpanded microspheres is located at one end of the belt conveyor and in conjunction with the belt (1). A collecting device (D) for expanded microspheres is located at the other end of the belt conveyor and in conjunction with the belt (1).

Abstract: The present invention relates to a device for the continuous manufacture of slabstock polyurethane foam including a conveyor means (1), a mixing head (51) and means (6) for discharging the reaction mixture from the mixing head (51) onto the conveyor means (1). The device further includes a start board (7), a stop board, means for moving the start board (7) along the conveyor means at the beginning of a production run in such a manner that it obstructs the moving reaction mixture to thereby increase the height of the first portion of the produced foam, and means for moving the stop board at the end of a production run in such a manner that it pushes the foaming reaction mixture ahead to thereby increase the height of the end portion. In this way, no operator has to enter the foaming machine and the start and end profiles of the foam blocks are optimised.

Abstract: An apparatus for continuously foaming a polyimide prepolymer powder which is not susceptible to heating by microwave energy utilize a preheated conveyor belt to heat the powder in contact with and adjacent the surface of the conveyor belt to commence the reaction and foaming of the powder as it enters an oven which further heats the powder by convection and infrared radiation to form a continuous foam bun. The conveyor belt is cooled as it exits the oven to cool a bottom surface of the foam product to enable the foam product to be removed from the conveyor before interior portions of the foam product have cooled. Foam adhering to the conveyor belt, after the product has been removed, is cleaned from the conveyor belt, collected and mixed with and used as a filler in the prepolymer powder used in the process. In addition the mass of the powder entering the oven and the density and degree of cure of the foam bun exiting the oven are monitored to continuously control the process.

Abstract: Continuous 3-D forming machine using upper and lower revolving endless, flexible, forming belts produces three-dimensional patterned products from heated thermoplastic material. The mold belts revolve synchronously in elongated oval paths around their respective carriages moving in opposed face-to-face relationship defining one or more travelling mold channels progressing from an entrance to an exit. Formable heated thermoplastic material feeds into the entrance, and attractive 3-D products proceed from the exit. Revolving mold surfaces are operated at least 25.degree. F. above room temperature, for example in a range of 110.degree. F. to 140.degree. F., for providing aesthetic surface qualities on products having content which may be foamed to densities in the range of about 0.9 to about 0.4. Thermoplastics in such travelling mold channels are appropriately chilled when differentials .DELTA.

Abstract: A process for the continuous production of a high modulus article comprising a composite of an oriented plastic material and an oriented particulate material, said process including the steps of:a. continuously forcing an orientable plastics material, while it is close to or at its softening temperature and in admixture with an orientable particulate material, through a converging passage of which the cross-sectional area diminishes in the forward direction of plastic flow, thereby to produce an extrudate;b. deforming the extrudate, while it is maintained at or close to its melt temperature, to produce an oriented, deformed extrudate; andc. cooling the deformed extrudate to preserve the orientation and provide said composite. The foamed and unfoamed composite articles have strength, modulus and density values comparable to typical hardwoods or softwoods.

Abstract: An apparatus for forming venting channels in a continuously-formed foam product includes a plurality of channel-forming plates which are removably attachable to the upper endless-type conveyor of a rigid foam laminating apparatus. The channel-forming plates provide a molding surface to form transverse channels in the foam product during the foaming operation. The channel-forming plates are easily removed for repair and/or replacement and include a centering bar which accurately positions each plate on the endless conveyor. The channel-forming plates are configured to form generally U-shaped channels in the upper surface of the continuously formed foam product to provide venting channels when the foam product is cut and used in roof insulation. The product and venting channels therein are sized to provide a continuous channel when a plurality of the foam panels are used as well as to facilitate attachment to standard trusses or joists.

Abstract: A thermoforming technique for making a shaped article from a web of polystryrene foam sheet or the like, with simultaneous forming and perforation of the article. Serrated cutter and spaced mandrel elements mounted in opposing mold sections provide a perforated pattern in the sheet.

Abstract: The method of making polystyrene foam for foam products which includes utilizing atmospheric gases as the blowing agents or preferably mixing one or more of these gases and a blending agent which is non-volatile at the extrusion temperatures, introducing the mixture to a molten thermoplastic polystyrene resin containing nucleating agents such as sodium bicarbonate and citric acid and extruding the thermoplastic in the form of a foam. The resultant foam has substantially no residual blowing agent, is dimensionally stable at ambient temperatures and when used with a non-volatile blending agent can be made with small amounts of blowing agent permitting cooling of the melt without high loading on the extruder. The foam may be coextruded with one or more layers of thermoplastic film so that the resultant product is adapted for use for plates, cups, food containers or packaging and for labels for containers such as glass and plastic containers and for labels that are shrunk in place on a container.

Abstract: Disclosed is a method for providing accelerated release of a flammable blowing agent from a plastic foam. The method comprises (a) providing the plastic foam having the blowing agent and a permeability modifier therein and (b) perforating the foam at its surface to form a multiplicity of channels extending from the surface into the foam. The channels are in gaseous communication with the environment outside the foam structures and provide accelerated released of blowing agent.

Abstract: An apparatus for the continuous production of foamed plastics is described. The apparatus includes i) a continuous conveyor belt, and ii) a transversely reciprocating applicator device located over the belt for applying a foam-forming reaction mixture. The applicator device includes a mix head and a detachably mounted magazine plate having several openings thereon. Each opening has a casting tube connected thereto. Each casting tube has discharge holes on its underside. The plate is adjustable in such a way that the casting tubes can be connected successively to the outlet of the mixhead.

Abstract: A method of forming foam buns including the steps of pouring foam in a liquid state onto a fall plate, preventing the forming of skin on upper and lower surfaces of the foam during a creaming state thereof as the foam advances along the fall plate and onto and along a conveyor, removing the formed bun from the conveyor, and causing a cooling gas to be forced through upper and lower surfaces of the bun and through the bun to effectuate rapid cooling of the bun. To prevent a skin from forming on the lower surface the fall plate is insulated to prevent heat transfer from the lower surface to the fall plate and the consequent forming of a skin on the lower surface of the bun which would normally result.

Abstract: In order to guarantee substantially trouble-free operation when manufacturing sandwich elements on a double conveyor belt installation having a downstream cross cutter and cleaning device, the cleaning device disposed on a transport carriage i) is returned to the carriage of the cross cutter to pick up the next sandwich element, is braked and is then re-accelerated to a speed higher than the production speed, ii) is, after reaching a desired distance.

Abstract: In the continuous production of polyurethane block foam, in particular from fast-reacting reaction mixtures which expand with rise time of less than 1.5 minutes, to achieve a good foam quality and a rectangular cross-section a centrally disposed mixer (44) is used, disposed downstream of which is a rubber-elastic plate (22), which is located in the feeding table (21) and in turn has a centrally disposed prop (33), associated with which, at right angles to the production direction and mounted laterally and symmetrically relative to said prop, are at least two adjustable props (32).

Abstract: An irregularly shaped weather strip having first and second weather strip sections integrally formed as a unit. Each of the weather strip sections includes a sealing portion and an engagement portion. The sealing portion and the engagement portion of each of the weather strip sections are formed of first and second molding materials, respectively. The sealing portion of the first weather strip section having a cross-sectional configuration different from that of the sealing portion of the second weather strip section. Such a weather strip is manufactured by extruding the first and second molding materials. The sealing portion of the second weather strip section is modified by blowing hot air at a portion of the first molding material.

Abstract: A process for making porous flexible pipes from two feed streams containing a thermoplastic material and a thermoset material, in which the feed streams are delivered to a die head extruder in a substantially compaction-free and segregation-free manner to insure that the feed composition in the extruder is substantially the same as the initial feed composition. The process can be automated so that an operator can manufacture porous flexible pipes of desired porosity and other rheological and mechanical characteristics by simply entering a command which will simultaneously adjust the process parameters such as the temperature and/or pressure inside the extruder, and the post-extrusion tension to meet the special need.

Abstract: Method and apparatus for producing a molded article of a foamed thermoplastic resin and articles produced thereby. A molten mass of an expandable thermoplastic resin is accumulated in an accumulator while it is prevented from foaming. A quantity of the accumulated formable melt is extruded through a die orifice having a shape adapted to reflect the shape of the desire finished product. The extruded foamable melt commences foaming as it comes in contact with the atmosphere. As the extruded thermoplastic resin foams, it is pulled vertically downward from the die orifice by gravity. The downward-hanging, foamed, thermoplastic material is captured between the halves of a vertically-oriented mold before the foaming expansion of the foamable melt has been completed. The foamed thermoplastic material is compressed by the vertically-oriented mold into the desired shape.

Abstract: A supermicrocellular foamed material and a method for producing such material, the material to be foamed such as a polymerplastic material, having a supercritical fluid, such as carbon dioxide in its supercritical state, introduced into the material to form a foamed fluid/material system having a plurality of cells distributed substantially throughout the material. Cell densities lying in a range from about 10.sup.9 to about 10.sup.15 per cubic centimeter of the material can be achieved with the average cell sizes being at least less than 2.0 microns and preferably in a range from about 0.1 micron to about 1.0 micron.

Abstract: System and method for densifying expanded thermoplastic foam materials such as loose fill packing materials, larger blocks of such materials, and food and beverage service items to reduce the volume of such materials for recycling or disposal. The material is heated to soften the material and expel gas from cells within the material and thereby shrink the material to a reduced volume. In some embodiments, and the material is further densified by compacting the heat softened material to further reduce the volume.

Abstract: A process for the continuous or semi-continuous production of cellular plastic from a plastic mass containing a blowing agent and, optionally, other process-regulative substances and additives. The process starts by raw materials to a plastic processing machine and kneading the raw materials in the plastic processing machine under conditions of temperature and pressure which will produce an expanding mass only upon release of pressure. The expanding mass is transferred directly to a cooling zone to produce a continuous mass having high viscosity and rigidity and an approximately flat velocity profile under pressure formed by an upstream-directed pressure component. At varying intervals the plastic mass is transferred to a braking-retaining zone which may be an integral part of the cooling zone for build-up of the upstream-directed pressure component until the pressure in the plastic mass in the zones located upstream is sufficient to prevent expansion of the plastic mass.

Abstract: A process and apparatus for manufacturing a molding including a portion formed of hybrid of hard rubber and sponge rubber. The process includes steps of introducing the hard rubber and the sponge rubber into a conduit through a plurality of first ports and a plurality of second ports positioned between the first ports, thereby to form hybrid of the hard rubber and the sponge rubber in which a plurality of hard rubber filaments are uniformly embedded in the sponge rubber, and extruding the hybrid from a extrusion opening to form the hybrid portion. The apparatus includes a flow conduit for forming the hybrid, the flow conduit communicating with a sponge rubber feed pipe through a plurality of first ports and communicating with a hard rubber feed pipe through a plurality of second ports positioned between the first ports.

Abstract: The present invention provides an extruder for highly foamed plastic material for coating a central conductor of a coaxial insulated cable with an insulator made of a mixture of a plastic material, preferably polyethylene, and an inert gas, such as nitrogen gas, to serve as a foaming agent. An inert gas is introduced approximately halfway down the extruder through a lead-in portion. At the lead-in portion of the extruder is a vent portion wherein the screw is provided with a plurality of stirring blades extending radially from the screw toward the inner surface of the extruder. These stirring blades provide a mechanism by which the inert gas is mixed thoroughly into the plastic material. The above invention provides an apparatus for producing an insulating material in which an inert gas (such as nitrogen), rather than hydrocarbon chloride fluoride, is used as a foaming agent, thus avoiding potential harm to the ozone layer.

Abstract: The apparatus includes molding a plurality of recesses on a layer of foam material which is laid on a laying surface and moved forward. These recesses include a base open on the laying surface and are subsequently cross-linked by introducing steam under pressure through the bases of the recesses into cavities of the recesses formed during the molding step. The apparatus includes a conveyor element in which a plurality of plates disposed side-by-side are provided with protuberances corresponding to the recesses to be formed in the foam layer. The protuberances are open at their bases to enable introduction of steam into an inner space within each of the protuberances.

Abstract: An L-shaped mixing head for reaction injection molding apparatus comprises a first chamber wherein a plurality of reactive molding components are impingement mixed under high pressure. A second chamber intersecting with the first chamber quiets the resulting stream of mix product prior to its exiting the mixing head. The outlet end of the second chamber is defined by the inner surface of a sleeve, the material of which has a yield strength less than that of the materials of the mixing head body and the second plunger. Most preferably, the sleeve material is also chemically nonreactive with and nonadherent to the reactive molding components to be used therewith, both individually and as mixed.

Abstract: The extrusion head has a head body which accommodates a male element and defines, in co-operation with the male element, a passage for material to be extruded. The passage extends around the male element and leads outward through an extrusion hole which is located proximate to an end of the head. A cooling element is applied at the extrusion hole and a hole is defined therein for the passage of the extruded material. The latter hole has a configuration which corresponds to the profile of the extruded element to be obtained, in order to achieve the rapid cooling of the extruded element exiting from the extrusion hole.

Abstract: The extrusion head has a body which accommodates a male element and which defines, in co-operation with the male element, a passage for the material to be extruded. The passage extends around the male element and leads outward through an extrusion hole located proximate to an end of the head. The end of the male element which is orientated in the direction of flow of the material has at least one channel through which material is delivered inside the flow of material which flows out of the extrustion hole.