Provided is a production apparatus capable of producing a flexible tube whose hardness is naturally varied along the length direction thereof. This mixing valve includes: a first valve configured to distribute a first resin to a resin supply path and a resin discharge path; and a second valve configured to distribute a second resin to the resin supply path and the resin discharge path. In the mixing valve, the mixing proportion between the first resin and the second resin is increased or decreased in association with molding of the flexible tube, by changing a distribution ratio of the first resin in the first valve and a distribution ratio of the second resin in the second valve while keeping constant the total of the supply mounts of the first resin and the second resin supplied to a die.

The present disclosure provides processes for producing polyethylene resins. In at least one embodiment, a polyethylene has: a density of from about 0.91 g/cm.sup.3 to about 0.94 g/cm.sup.3; a value of Mz of about 1,500,000 g/mol or greater; and a ratio of Mz to Mw of about 7 or greater. A process includes introducing a first feed stream having ethylene monomer and a first free radical initiator to a first inlet of a first reaction zone, where the first reaction zone has a first inlet temperature. The process further includes introducing a second feed stream having ethylene monomer and a second free radical initiator to a second inlet of a second reaction zone, where the second reaction zone has a second inlet temperature that is the same or different than the first inlet temperature.

An extruder assembly includes a rolling assembly. An extrusion block includes a plurality of extruding ports that receive an extrudable material from the rolling assembly. A regulating mechanism is positioned within, above, or otherwise near each extruding port of the plurality of extruding ports. The regulating mechanism is operable with respect to the rolling assembly to modify a flow of extrudable material through each respective extruding port.

The smoothing device for plastic films comprises plastic-melt-producing means (1, 5), an adjustable slit die (10) and a roller smoothing unit (16) having cooled smoothing rollers (11, 12), which form an adjustable smoothing gap (13) between each other. Optionally, further rollers (15) are arranged downstream. A thickness gauge (23) measures the thickness of the plastic-film web (22). A controller (30) for controlling the thickness of the plastic-film web (22) may set a setpoint thickness (SD) of the plastic-film web (22) and the volumetric flow rate (SS) of the plastic melt or the line speed (LS). The controller (30) captures the current torques and rotational speeds of the rollers (11, 12, 15) and the current thickness (FD, FD1-FDn) of the plastic-film web (22).

The controller (30) sends setpoint rotational speed signals (C0S, C2S-CnS, CAS) calculated from the captured torques of the rollers (11, 12, 15) to the drives of the rollers and a smoothing-gap setpoint distance signal (GW) for adjusting the smoothing gap (13), and furthermore—in the case of a specified line speed (LS)—setpoint plastic-melt volumetric flow rate signals (SS) to the plastic-melt-producing means, or—in the case of a specified plastic-melt volumetric flow rate (SS)—setpoint line speed signals (LS) to the drives of the rollers (12).

A method of manufacturing a mixture PTFE thread using a mixture PTFE powder consisting of PTFE: 73-95 wt %, MoS.sub.2: 3-25 wt %, Al.sub.2O.sub.3: 1-5 wt %, and Al(OH).sub.3: 1-5 wt % comprises heat-retaining step for adding 18-25 wt % kerosene of a solvent to the mixture PTFE powder and keeping it warm at 30-50° C. for 40 to 50 hours, extruding the heat-retained mixture PTFE powder into a rod shape with a circular or elliptical cross section at the cylinder temperature of 70-90° C., rolling the extrusion at 100-150° C. into a 0.3-0.7 mm thick sheet shape, multiple-folding the sheet and passing the sheet through an oven at 250-270° C. at the rate of 10-40 cm/s, and stretching the folded sheet with a stretch ratio of 200-600% in multiple stages after heating the sheet at 450-500° C.

The invention relates to novel processes for determining the quality of an uncrosslinked rubber mixture by means of ultrasound and to an apparatus suitable for this purpose.

A method and apparatus for the pelletization of plastics and/or polymers, in which a melt coming from a melt generator is supplied via a diverter valve having different operating positions to a plurality of pelletizing heads through which the melt is pelletized. The plurality of pelletizing heads have different throughput capacities and are used sequentially for the start-up of the pelletizing process, with the melt first being supplied to a first pelletizing head having a smaller throughput capacity and then the melt volume flow being increased and the diverter valve being switched over such that the melt is diverted by the diverter valve to a second pelletizing head having a larger throughput capacity.

A co-injection extrusion apparatus and method. The first extruder cooperates with a first material delivery channel for delivering a first material to a die. The second extruder cooperates with a second material delivery channel for delivering a second material to a die. A first plunger is positioned in the first material delivery channel and a second plunger is positioned in the second material delivery channel. The plungers are movable between a first position in which to the plunger is extended in a respective material delivery channel toward the die, and a second position in which the plunger is retracted in the respective material delivery channel away from the die.

A molding apparatus that adsorbs thermoplastic resin extruded in a sheet form from an extruding machine, onto a cavity of a mold, and shapes the thermoplastic resin into a shape according to the cavity is provided. The molding apparatus may include a frame that is positioned on a periphery of the mold and is movable relative to the mold, wherein a suction part for suctioning the thermoplastic resin is provided in a contact surface of the frame to contact the thermoplastic resin, and the suction part is provided in a linear shape along with a longitudinal direction of the frame positioned on the periphery of the mold.

A method for using the quantity of heat output from an extrudate during a cooling operation in an extrusion process, wherein a fluid, in particular air, is guided along the extrudate and/or through the die counter to an extrusion direction, at least some of the heat from the extrudate and/or the die is transmitted to the fluid, the heated fluid is supplied from a first sub region of a process chain, comprising at least one die, a calibrating and cooling device and a take-off apparatus, via a connecting region, preferably consisting of at least one connecting pipe, to a second sub region of the process chain, comprising at least one suction apparatus. In the connecting region, an extraneous fluid can be added to the heated fluid in order to reduce the actual temperature of the heated fluid at least below a predetermined maximum value before said fluid is supplied to the second sub region of the process chain.