GB1592261A

GB1592261A - Method and a machine for processing polymeric materials which are or become in the course of processing viscous liquids

Info

Publication number: GB1592261A
Application number: GB33834/77A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-05-11
Filing date: 1977-08-12
Publication date: 1981-07-01
Also published as: AU517417B2; DE2732173C2; SE429519B; AU2742277A; BE860142A; DE2759878C2; FR2390259B1; JPS6147684B2; SE7708283L; CA1111225A; JPS53139688A; SU1011039A3; DE2732173A1; NL189284C; FR2390259A1; NL189284B; NL7712481A

Description

(54) IMPROVEMENTS IN OR RELATING TO A METHOD AND A MACHINE FOR PROCESSING POLYMERIC MATERIALS WHICH ARE, OR BECOME IN THE COURSE OF PROCESSING, VISCOUS LIQUIDS (71) I, ZEHEV TADMOR of 608 Wyndham Road, Teaneck, New Jersey, United States of America, a citizen of Israel, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to improvements in or relating to a method and a machine for processing polymeric materials which are, or become in the course of pressing, viscous liquids for example plastics materials.

An important machine at the present time for processing plastic and polymeric materials is the single screw extruder. The term processing includes one or more of the following operations: handling, conveying, pressurising and melting or plasticating of solid materials; conveying pressurising or pumping of liquid or molten materials; mixing, blending, dispersing and homogenising the materials and various liquid or solid additives; devolatilising the materials; bringing about any microscopic or macroscopic structural change in the materials by chemical reactions, e.g. polymerisation, cross-linking and foaming or by other means, to modify, alter or improve some property.

It is known that a screw extruder for processing plastic and polymeric materials may be considered as a shallow stationary channel defined by the root of the screw and the flights and a fourth wall defined by the inner surface of the barrel which moves relative to the stationary channel, (see for example Z. Tadmor and I.

Klein, "Engineering Principles of Plasticating Extrusion", Van Nostrand Reinhold Book Co., New York, 1970). The relative rotational movement of the barrel and the extruder screw drags material both in particulate solids and viscous liquid form toward the discharge end of the barrel and toward a screw flight bringing about conveying, pressurisation and pumping actions of solids and viscous liquids, and mixing dispersion and homogenisation of the viscous liquids. Heat energy from the barrel together with frictional heat generation and viscous heat generation create a relatively thin film of melt on the barrel surface, which is dragged by the said relative motion toward a screw flight where it is scraped off bringing about an efficient melting and plasticating action. Material on the root of the screw and flights of the screw cannot be scraped off, neither do these walls, which are stationary relative to the processed material, bring about any dragging action toward the discharge end of the barrel to facilitate conveying, pressurisation or pumping of the solids and viscous material, nor do they facilitate the mixing, dispersing and homogenisation process. In the screw extruder, therefore, the single surface, that of the barrel, is the sole agent for processing material.

The present invention provides a method of processing material which is or becomes in the course of such processing a viscous polymeric liquid, comprising supplying material to be processed through an inlet opening to an annular channel circumferentially disposed around a rotor and rotatable with the rotor in a housing having a surface coaxial with the axis of the rotor the surface closing the channel to form an annular passage, rotating the rotor whereby to drag material in the channel around the annular passage towards an outlet opening through which it is to be discharged, effecting the discharge by blocking the channel adjacent the outlet opening, and restricting discharge through the outlet opening whereby the blocking and the restricting produce a circulatory motion in a mass of liquid material accumulated in the channel upstream of the block in the channel.

The present invention also provides a machine suitable for use in carrying out a method as set out in the last preceding paragraph comprising a rotor having an annular channel disposed circumferentially therearound, a housing within which the rotor is mounted for rotation the housing having a surface coaxial with the axis of the rotor closing the annular channel to form an annular passage, an inlet opening by which material to be processed can be supplied to the annular passage, an outlet opening from the annular passage downstream of the inlet opening, a block member in the passage adjacent the outlet opening to discharge material from the outlet opening, the discharge through the outlet opening being restricted whereby the blocking and the restricting produce a circulatory motion in a mass of liquid material accumulated in the channel upstream of the block in the channel.

In the treatment of polymeric and plastic materials having similar characteristics, such as material normally processed in screw type extruders and which are, or become in the course of processing, high viscosity liquids, coordination of physical design factors and operational controls in a method and machine in accordance with the invention enables processing, including conveying and pressurisation of solids; melting or plasticating of solid materials; conveying; pressurising or pumping of liquid or molten material; mixing, blending, dispersing and homogenising the material, devolatilisation and combination of these process treatments, in relation to solid material feed and viscous material feed or combinations of both. The method and machine can feed various shaping dies such as sheeting and profile dies, cross head dies, cable and wire coating dies, pelletisers, and much other sequentially arranged processing apparatus.

A method and machine in accordance with the invention can be used to bring about microscopic or macroscopic structural changes in the material to modify, alter or improve some property of the material, by chemical reaction such as polymerisation of prepolymers and monomers leading to viscous polymeric liquids, cross-linking, chain break down, foaming and the like.

Materials which may be processed by the method and machine of the present invention include plastics materials and polymeric materials normally liquid or reducible by heat or mechanical energy, or diluent to viscous liquid or deformable state, and which have sufficient stability to avoid serious degradation under treatment conditions. Such materials include but are not limited to thermoplastic, thermosetting and elastomeric polymeric materials such as for example, polyolefins (e.g. polyethylenes, polypropylenes), vinylchloride polymers (e.g.

polyvinylchloride), fluorine containing polymers, polyvinylacetate based polymers, acrylic based polymers, styrene based polymers (e.g. polystyrene), polyamides (e.g.

nylons), polyacetals, polycarbonates, cellulose based plastics, polyesters, polyurethanes, phenolic and amino plastics, epoxy based resins, silicone and inorganic polymers, polysulphone based polymers, various natural based polymers and the like together with copolymers and blends of those materials with each other or with solvents or diluents or with different solid and liquid additives. Also, it is contemplated that chemically reactive materials such as materials or mixtures of materials which may form polymers which are viscous liquids at some stage of their formation and at the temperatures maintained in the channel(s) may be fed to the machine for reaction and processing in the channel(s).

Efficient processing of materials in carrying out a method according to the present invention is achieved by co-ordinating the rate of material feed to and discharge from the annular processing channel(s), temperature control and speed of the channel walls, having regard to the properties of the material and the geometry of the channel.

Design factor variables include the geometry of the annular channel(s), the nature of any feeding device, the dimensions and location of the opening(s), the shape of channel block(s), and the dimension(s) and location(s) of the outlet opening(s).

Machines in accordance with the invention for practising a method in accordance with the invention comprise one or more annular channels disposed circumferentially around a driven rotor for rotational movement relative to a housing of which an internal cylindrical surface coaxial with the rotor co-operates with the walls of the channel or channels to form the enclosed annular passage or enclosed annular passages, the channels having a radial depth greater than their width. Conveniently an inlet opening for feeding the plastic or polymeric material into each annular passage extends through the housing and an outlet opening for discharge of material from each passage is suitably disposed circumferentially a major portion of a complete revolution from the inlet opening. A block member, suitably a channel block supported by the housing projects into each channel of a machine in accordance with the invention to hold the plastic or polymeric material for relative movement with respect to the channel side walls and may thus wipe or scrape the side walls moving past it, and is located between the outlet opening and the inlet opening to each annular passage to direct material towards the outlet opening.

In carrying out a method in accordance with the invention a machine in accordance with the invention generally similar to the first illustrative machine described hereinafter may conveniently be used. In this machine the annular channels are formed between spaced discs extending outwardly from a shaft; the discs are conveniently spaced apart by spacers and the space between opposed faces of the discs is readily altered by use of different spacers thus to change the channel width and the depth of the channels can be altered by use of annular spacers having different diameters. The number of channels may be altered by removing or adding discs to enable operation with different material, different energy input, different processing rates and so on.

By reason of the straightforward relations in a machine and method in accordance with the invention data derived from machines constructed with annular channels of rectangular cross-section may be transferred to more sophisticated machines with a good measure of confidence. However, the channels may have other shapes in cross-section, thus where discs are used to provide the channels, the discs may be of any shape or cross-section and need not necessarily be flat. Wedge shaped or fin shaped discs may be useful for certain functions.

Alternatively, the channels may be annular grooves or passageways formed in a driven rotor.

Temperature of the material as supplied and during the course of processing in the machine will be controlled so that the viscosities and flow characteristics of the material being processed are determinable.

The inter-relationship of rate of feed and discharge of liquid viscous plastic and polymeric materials in a method in accordance with the invention, to an annular rectangular processing channel and the speed of the channel walls with respect to the properties of the selected material and temperature and to the geometry of the channel, assuming: isothermal, laminar, steady, fully developed flow of an incompressible power law model non-Newtonian fluid, neglecting gravitational and inertial (centrifugal) forces is expressed by the following equation:

In the above equation: Q=volumetric flow rate (in3/sec.).

N=frequency of channel rotation (r.p.s.).

Outside radius of annular channel (in.).

Rs=inside radius of annular channel (in.).

a=Rs/Rd.

H=width of annular channel (in.).

P=pressure (psi).

0=angle (radians) dP Pout-Pin = =angular pressure gradient (psi/rad.).

do 2 7r Pout=exit pressure (psi).

Pin=inlet pressure (psi).

9=fraction of circumference from inlet to outlet.

s=l/n empirical parameter of the 'power-law' model fluid: \=myn1 ?=non-Newtonia viscosity (Ibfsec/in2).

m=empirical parameter (Ib,sec n/in2).

n=empirical parameter.

y=shear rate, (I/sec).

In the above equation the first term on the right-hand side is the 'drag flow' and the second term is the 'pressure' flow. This equation also applies for Newtonian fluids in which s=n=l and m= is the Newtonian viscosity.

As illustration to the use of the above equation a melt pump for polymeric material will be designed. It is required to pump 1,000 lbs/hr melt and generate a 1500 psi pressure at the discharge. The power-law parameters of this melt at the processing temperature are m=l Ib,sec 0.5/in2 and n=0.5. Assuming Pin=0 and =0.75,- the required gradient is dP de 1500 =318.3 psi/rad (2) (n) (0.75) Further assuming that the density of this melt at the processing temperature and the average pressure is 50 lb./ft3, the volumetric flow rate is (1000) (1728) Q= -9.6 in3/sec (3600) (50) Substitution of the available data into the design equation with a=0.5 gives 3166.1 (sec-')H4(in4) 9.6=2.356N(r.p.s.)H(in)R(in2)- Rd (in) The above equation provides the required relationship between Rd, H and N.

Next by selecting a reasonable N value e.g. 30 RPM, the relationship between Rd and H is obtained as shown in Figure 6. Thus, a disc radius of 6.3" is the optimum with a channel width of 0.24". Therefore, an annular rectangular channel of outside diameter of 12.6", inside diameter of 6.3" and width of 0.24" rotating at 30 r.p.m.

pumps 1,000 Ib./hr. melt and generates 1;500 psi, pressure.

It is observed that the annular channel is narrow and deep and this may pose difficulties in effectively feeding material to be treated in a manner to reach the bottom of the channel. In practice, this problem can be solved in a machine in accordance with the invention either by providing sufficient undercut in the housing (as shown in Figure 5 of the accompanying drawings undercut 70 is provided in housing 41) or using a plurality of channels with the first stage somewhat wider than the optimum.

Where the material to be fed is particulate solid material, it is preferred to have a first channel as narrow as possible, but suitably wide for gravitational feeding. For common polymeric materials in particulate form, this is of the order of about 0.25" to about 2.5".

For practical considerations, the speed of the rotor and channel will generally not exceed 500 RPM and desirably will not exceed about 250 RPM. Lower limits of rotor and channel speed may be as low as about 10 RPM.

Conveniently a feed for introduction of plastic or polymeric material or the like to the annular processing channel in a machine in accordance with the invention is designed for operation with the particular material and state of the material to be processed. Where the plastic or polymeric material to be processed is granular, the feeder will be designed to ensure filling the channels from bottom to top for effective use of the processing surfaces of the channel. A simple hopper leading through the inlet opening may be useful with some granular materials while with others it may be important to have mechanical feed such as a screw or ram type feed. Where the material to be processed is a viscous liquid, the feeder may be a conduit through which the liquid flows to the channel or may be a pump such as a screw type or gear type device for supplying material at a desired rate and pressure.

In a machine according to the present invention having more than one channel, the outlet opening from one channel may be led through a conduit to the inlet of a further channel for further processing. This arrangement is particularly valuable since the series pressure producing and pumping action of successive processing channels is cumulative so that high outlet pressure is readily secured. It will be understood that successive channels may each have different geometry from other channels for best processing of material supplied to it. Also, material processed in-and discharge from one channel or a given number of channels operating in parallel may be fed to one channel or to any suitable number of channels operating in parallel.

Separate feeders and inlet openings may be provided to feed each channel or any combination of channels with polymeric or plastic material which may be the same as or different from the material fed to any other channel or combination of channels. Different materials processed by separate channels or combinations of channels may be discharged through separate outlet openings and may be supplied to separate extrusion nozzles or, may be fed to a nozzle for co-extrusion, for example with one material as a core and another material as a coating.

There now follows detailed descriptions, to be read with reference to the accompanying drawings, of first and second machines for processing polymeric material e.g. plastics material and methods of processing the material using such machines. It will be realised that these machines and methods have been selected for description to illustrate the invention by way of example and not of limitation of the invention.

In the accompanying drawings: Figure 1 is a schematic perspective view of the first illustrative machine for processing polymeric material which is exploded to show the various parts; Figure 2 is a perspective view partially in section of the first illustrative machine; Figure 3 is a flattened sectional view of a channel of the first illustrative machine taken around the channel at a selected radius and illustrating the movement of material within the channel; Figure 4 is a sectional elevational view of the second illustrative machine for processing polymeric material taken on the line of IV-IV of Figure 5 parallel to and along an axis of rotation of a rotor of the second illustrative machine; Figure 5 is a sectional end elevational view of the second illustrative machine taken along the line V-V of Figure 4 perpendicular to the axis of rotation of the rotor; and Figure 6 is a graph on which are plotted the relationship of channel width and channel diameter for given operating conditions.

The first illustrative machine comprises a rotor 10 shown as a number of spaced disc-like elements 12 mounted on a drive shaft 14 for rotation within a housing 16, with the shaft 14 journalled in end plates 18 of the housing 16. The rotor 10 is constructed with annular, suitably cylindrical, surface portions 20 and with at least one annular channel 22 formed with spaced opposed side walls 24 disposed with an annular surface portion 20 on each side of the channel. The housing 16 provides an annular, suitably cylindrical, surface 26 coaxial with and in close relation to the annular surface portions 20 of the rotor to form with the channel(s) 22 enclosed annular passage(s).

An inlet opening 28 through the housing 16 is provided for introduction of plastic or polymeric material for processing from a suitable feeder, shown as a hopper 30, into the annular channel(s) 22. It will be understood that suitable plastic or polymer material feeding devices will be used which may be a simple gravity feeder hopper as shown or may be a screw feeder, a ram feeder, a disc-type preheater feed and so on depending on the character of the plastic or polymeric material and the difficulty of controlling its supply to the channel(s) 22.

Block members viz. channel blocks 32 mounted on the housing 16 extend into each channel 22 at a circumferential position at least a major portion of a complete revolution of the rotor 10 from the inlet opening 28 to provide an end wall 34 to the annular channel 22 and scraper portions in close relation to the walls 24 of the channel. The channel block 32 has a shape complementary to and fitting closely within the channel 22 into which it extends and the end wall 34 facing the annular channel 22 may be radially disposed or at another suitable angle depending upon the material and treatment desired. Adjacent to the channel block 32, upstream from it, i.e. counter to the direction of movement of the channel, an outlet opening 36 through the housing 16 is provided, the opening 36 also being disposed a major portion of a complete revolution from the inlet opening 28 in the direction of rotation of the rotor 10.

In operation of the first illustrative machine in carrying out an illustrative method of processing plastic or polymeric material, the material in solid or liquid state is fed by the feeder which distributes the material into each channel 22 through the inlet opening 28. As the rotor 10 turns, the main body of material is held by the end walls 34 of the channel blocks 32 so that the channel side walls 24 move (simultaneously, towards the outlet opening 36) relative to the body of the material in the channel 22 and the material adjacent the opposed side walls 24 of the channel 22 is dragged forward by the side walls toward the end wall 34 of the channel block 32 with a gradual build up of pressure reaching a maximum value at the channel block 32 where material is discharged from the channel 22 through the outlet opening 36. The melting mechanism is schematically shown in Figure 3 where the material is a granular solid. As shown, the granules are compacted into a solid bed as a result of the relative motion between the rotating side walls 24 of the channel 22 and the solids within the channel. Optionally, the side walls 24 may be preheated, but in any case, the relative movement generates frictional heat and forms a film of molten plastic or polymeric material on the side walls 24 of the channel 22. The molten film thus formed, moves with the walls 24 and is vigorously sheared by motion relative to the main body of plastic or polymeric material in the channel to generate further heat by viscous dissipation. The action of the side walls 24 of the channel 22 in dragging forward material on its surface builds up pressure progressively along the length of travel of the side walls reaching a maximum value at the channel block 32. The channel block 32 scrapes off and collects viscous liquid material carried forward by the side walls of the channel and this material accumulates as a pool against the end wall of the channel block and may be discharged from the channel through the opening 36, into which it is directed by the block 32, by the built up pressure.

As shown schematically in Figure 3, continued supply of material dragged forward by the channel walls produces a strong circulatory motion in the pool of molten material and this circulatory motion gives a vigorous mixing action. Similar vigorous mixing action can be achieved with liquid fed material by appropriate selection of operational controls.

As shown in Figures 1 and 2, a die 38 may be disposed directly in the outlet opening 36 of the first illustrative machine.

The geometry of the channel 22 must achieve a balance of the various purposes which the channel serves. Since the channel walls 24 are a primary processing member, a narrow and deep channel 22 will be used in which the depth of the channel is greater than, and preferably a plurality of times as great as, the width of the channel. The cross-section of the channel must be of appropriate shape and the space between opposed side walls 24 must be sufficiently wide to enable material fed to it to reach the root of the channel and fill the channel directly; but a balancing factor is that the pumping or pressurising ability of the channel 22 be maintained close to the optimum and not be made so wide as to decrease the pressurising ability. Melting, mixing and pumping or pressurising action increases as the rate of passage of channel walls area past the material increases; but the ratio of channel wall area to channel volume must be balanced so that where solid material is fed to the channel it will fill a portion of the channel for melting at a desired rate by the action of the channel walls and that the molten material will fill a portion of the channel sufficient to produce desired mixing and pumping or pressurising of the material for discharge. The linear speed of portions of the channel walls at a given rate of rotation increases directly as the radial distance of each wall portion from the axis of rotation and it has been found that the variation in processing action due to difference in radial distance from the axis may be compensated by increasing the space, H, between side walls bounding a channel in proportion to-the distance, R, from the axis so that H/R is a constant. A simple arrangement would involve forming the channel walls as spaced truncated cones of which the vertices would substantially coincide at the axis of rotation.

Channels such as formed by opposed side walls 24 of discs 12 mounted adjustably in spaced relation on a drive shaft 14 as in Figure 1 will operate to process polymer materials, and this construction has advantages for experimental analysis of processing of various viscous and solid materials.

The outlet opening 36 through the housing 16 is disposed at least a major portion of a complete revolution of the rotor 10 from the inlet opening 28 in a position to receive and discharge processed material reaching the channel blocks 32. Control of the rate at which processed material is allowed to discharge from the channel is an important factor in determining the extent to which the material is processed and the outlet opening 36 is constructed and arranged to provide this discharge control. Discharge may be restricted by the size of the opening or by a throttling valve or other device in the outlet opening. The discharge rate may also be restricted by connecting the outlet opening to a further processing stage such as an extrusion nozzle or die 38 of the like which may provide desired flow resistance controlling the rate of discharge from the outlet and the extent of processing of material in the channel.

The second illustrative machine, see Figures 4 and 5, comprises two processing channels which are connected in series, apart from this and where hereinafter described, the construction, arrangement and operation of the second illustrative machine is generally similar to the first illustrative machine. In the second illustrative machine, a rotor 40 is mounted for rotation in a housing 41 on a drive shaft 42 journalled in end walls 44 of the housing 41. Annular channels 46 and 47 are provided with the opposed side walls 48 in fixed relation to each other providing a wedge shaped channel cross-section and with relatively wide cylindrical surface portions 50 at each side of the channels 46 and 47. These cylindrical surface portions 50 are in close sliding fit with the coaxial cylindrical inner surface 51 of the housing 41 so that the inner surface 51 of the channels 46 and 47 form enclosed annular passages.

Chambers 52, 54 and 56 are provided on the outside of each of the walls 48 of the channels for introduction of a temperature control fluid for heat transfer through the walls of the channel. Heat transfer fluid is supplied to these chambers through an axial passage 58 constructed in the shaft 42 through which temperature control fluid flows to a first chamber 52 through tubes 60, then from the first chamber 52 through a channel 62 to the second chamber 54, then through a channel 64 to the third chamber 56 and through a tube 66 to a further passageway 68 in the shaft 42.

As shown more clearly in Figure 5, the interior surface 51 of the housing 41 is cylindrical over most of its extent but is provided with an undercut 70 adjacent a material inlet opening 71 to channel 46. This undercut 70 is of a width such that its walls 72 extend out over the cylindrical portions 50 of the rotor 40 to form an intake chamber 74 so that when viscous liquid material is supplied through the inlet opening 71, the viscous liquid material is dragged by the cylindrical surface 50 of the rotor to the nip where the surface of the walls 72 of the undercut 70 approaches the cylindrical surface 50 of the rotor. This action facilitates squeezing of the viscous material into the channel 46.

A channel block 76 is mounted on the housing 41 and has a shape complementary to and fitting closely swithin the channel 46 to hold the main body of plastic or polymeric material for motion relative to the walls 48 of the channel 46 and to scrape off viscous liquid material carried forward by the side walls 48 for discharge as processed material through an outletopening 78. A passageway 80 is provided to conduct processed material from outlet opening 78 to an inlet opening 82 into the annular channel 47 for further processing. A channel block 84 mounted on the housing 41 has a shape complementary to and fitting closely within channel 47 to hold the main body of plastic or polymeric material in that channel for motion relative to the walls 48 and to scrape off viscous liquid material carried forward by the walls 48 for discharge as processed material through an outlet opening 86.

Referring to Figure 5, the provision of an optional further mixing structure, viz. an obstruction 88 is shown. This obstructio by controlling the discharge and adjusting the channel block some or all of the material may be recycled. If all material is recycled, e.g. by closing the outlet opening, batch operation is obtained. If part of the material is recycled, continuous operation is obtained.

By use of these options a variety of procedures may be carried out. Thus, the channel block may be set for recycling some or all of the material to bring material in the channel to a selected condition, further material may then be added either through the inlet opening 71 or through the port 92 or both for mixing or combination with the material which has been brought to the selected condition in the channel.

The following Examples are given as of assistance in understanding the invention and it is to be understood that the invention is not restricted to the particular procedures, proportions, materials, temperatures or other details of the process.

EXAMPLES In carrying out a processing operation the first illustrative machine was set up with the rotor 10 having a channel gap width of 0.25" and an outside diameter of 7.5" and inside diameter of 4.5". The inlet opening 28 to the housing 16 of the first illustrative apparatus was connected by a conduit (not shown) to receive molten low density polyethylene from a screw extruder, and the outlet opening 36 from the housing was connected to a restricted orifice.

The following results were obtained: Channel Temp.

Rotor Speed Material Flow Pressure Rise wall temp. Material out (r.p.m.) (Ib./hr.) (Pout-Pin) (psi) (OF.) in ("F.) ("F.) 21 183.5 490 400 410 424 21 141.0 870 300 420 396 19 64.2 1275 300 420 396 55.5. 279 1510 300 420 423 73.5 275 1705 300 418 423 A further example comprises the same processor with a channel width of 0.75" gravitationally fed by solid low density polyethylene pellets: Rate of Discharge Rotor Speed Channel wall Plasticating Temp.

(r.p.m.) temp. (OF.) Ib./hr. (OF.) 26.6 400 23.3 348 75.5 400 46.2 368 153.6 400 79.2 408 WHAT I CLAIM IS: 1. A method of processing material which is or becomes in the course of such processing a viscous polymeric liquid, comprising supplying material to be processed through an inlet opening to an annular channel circumferentially disposed around a rotor and rotatable with the rotor in a housing having a surface coaxial with the axis of the rotor the surface closing the channel to form an annular passage, rotating the rotor whereby to drag material in the channel around the annular passage towards an outlet opening through which it is to be discharged, effecting the discharge by blocking the channel adjacent the outlet opening, and restricting discharge through the outlet opening whereby the blocking and the restricting produce a circulatory motion in a mass of liquid material accumulated in the channel upstream of the block in the channel.

2. A method according to Claim 1 in which processing of the material in the channel is achieved by co-ordinating the rate of material feed to and discharge from the channel, temperature, and the speed of rotation of the rotor.

3. A method according to any one of the preceding claims in which the material being processed is transported through a plurality of annular channels spaced axially along the rotor, material being discharged from one annular channel into a further annular channel for further processing.

4. A method according to any one of the preceding claims in which the material, during its flow from inlet to outlet, passes at least one obstruction

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. by controlling the discharge and adjusting the channel block some or all of the material may be recycled. If all material is recycled, e.g. by closing the outlet opening, batch operation is obtained. If part of the material is recycled, continuous operation is obtained. By use of these options a variety of procedures may be carried out. Thus, the channel block may be set for recycling some or all of the material to bring material in the channel to a selected condition, further material may then be added either through the inlet opening 71 or through the port 92 or both for mixing or combination with the material which has been brought to the selected condition in the channel. The following Examples are given as of assistance in understanding the invention and it is to be understood that the invention is not restricted to the particular procedures, proportions, materials, temperatures or other details of the process. EXAMPLES In carrying out a processing operation the first illustrative machine was set up with the rotor 10 having a channel gap width of 0.25" and an outside diameter of 7.5" and inside diameter of 4.5". The inlet opening 28 to the housing 16 of the first illustrative apparatus was connected by a conduit (not shown) to receive molten low density polyethylene from a screw extruder, and the outlet opening 36 from the housing was connected to a restricted orifice. The following results were obtained: Channel Temp. Rotor Speed Material Flow Pressure Rise wall temp. Material out (r.p.m.) (Ib./hr.) (Pout-Pin) (psi) (OF.) in ("F.) ("F.) 21 183.5 490 400 410 424 21 141.0 870 300 420 396 19 64.2 1275 300 420 396 55.5. 279 1510 300 420 423 73.5 275 1705 300 418 423 A further example comprises the same processor with a channel width of 0.75" gravitationally fed by solid low density polyethylene pellets: Rate of Discharge Rotor Speed Channel wall Plasticating Temp. (r.p.m.) temp. (OF.) Ib./hr. (OF.) 26.6 400 23.3 348 75.5 400 46.2 368 153.6 400 79.2 408 WHAT I CLAIM IS:

1. A method of processing material which is or becomes in the course of such processing a viscous polymeric liquid, comprising supplying material to be processed through an inlet opening to an annular channel circumferentially disposed around a rotor and rotatable with the rotor in a housing having a surface coaxial with the axis of the rotor the surface closing the channel to form an annular passage, rotating the rotor whereby to drag material in the channel around the annular passage towards an outlet opening through which it is to be discharged, effecting the discharge by blocking the channel adjacent the outlet opening, and restricting discharge through the outlet opening whereby the blocking and the restricting produce a circulatory motion in a mass of liquid material accumulated in the channel upstream of the block in the channel.

extending into the annular channel upstream of the outlet opening and is thereby subiected to processing.

5. A method according to Claim 4 in which the material is subjected to an additional mixing step within the annular channel upstream of the outlet opening.

6. A method according to Claim 4 in which the material downstream of the obstruction is divided whereby a void is created within the material from which gases and volatile substances are drawn.

7. A method according to any one of the preceding claims in which the material to be processed comprises materials or mixtures of materials which may react to form polymers.

8. A method according to claim 5 in which the material downstream of the obstruction is divided whereby a void is created within the material into which further material is supplied for mixing or combination with the material already in the annular channel.

9; A method according to any one of the preceding claims in which a portion of the material is transported past the block in the channel and recirculated around the annular channel and the rest of the material is discharged through the outlet opening.

10. A method according to any one of the preceding claims in which batch processing of the material in the annular channel is controlled by intermittent closing of the outlet opening.

11. A method according to any one of the preceding claims in which the material in the annular channel is transported between spaced truncated conical walls so that the material is transported as a body the width of which is greater the further the radial distance from the axis df the rotor.

12. A method according to any one of the preceding claims in which the material is fed simultaneously into a plurality of annular channels axially adjacent each other and processed therein.

13. A method according to any one of Claims 1 to 11 in which the material is fed into one annular channel and is transferred to a plurality of further annular channels for further processing.

14. A method according to either one of Claims 12 and 13 in which the material is processed in a plurality of annular channels all of which are of equal volume and similar geometric configuration.

15. A method according to either one of Claims 12 and 13 in which the material is processed in a plurality of annular channels of varying volume and geometric configuration from one another.

16. A method according to either one of Claims 14 and 15 in which the material is fed through separate inlet openings to separate annular channels or combinations thereof, and is discharged through outlet openings from separate channels, or combinations of said channels.

17. A method according to any one of the preceding claims in which the material is supplied to an intake chamber including a surface sloping towards a cylindrical surface of the rotor at an outer edge of and rotating with the annular channel and is dragged by the cylindrical surface into the nip between said sloping surface and said cylindrical surface and thereby squeezed into the annular channel.

18. A method according to any one of the preceding claims in which said annular channel rotates at a frequency of rotation from 10 to 500 r.p.m.

19. A method of processing material which is, or becomes in the course of processing, a viscous polymeric liquid substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

20. A method of processing material which is or becomes in the course of processing, a viscous polymeric liquid substantially as hereinbefore described with reference to Figures 3 to 5 of the accompanying drawings.

21. A machine suitable for use in carrying out a method according to any one of the preceding claims comprising a rotor having an annular channel disposed circumferentially therearound, a housing within which the rotor is mounted for rotation the housing having a surface coaxial with the axis of the rotor closing the annular channel to form an annular passage, an inlet opening by which material to be processed can be supplied to the annular passage, an outlet opening from the annular passage downstream of the inlet opening, a block member in the passage adjacent the outlet opening to discharge material from the outlet opening, the discharge through the outlet opening being restricted whereby the blocking and the restricting produce a circulatory motion in a mass of liquid material accumulated in the channel upstream of the block in the channel.

22. A machine according to Claim 21 in which the rotor comprises discs extending outwardly from a shaft of the rotor and spaced apart to provide the annular channel.

23. A machine according to Claim 22 in which adjacent, opposite surfaces of the discs forming side walls of the annular channel are arranged radially normal to the axis of the rotor.

24. A machine according to Claim 22 in which the surfaces forming side walls of the annular channel comprise truncated cones coaxial with the axis of rotation of the rotor.

25. A machine according to any one of Claims 21 to 24 in which the block member extending into the annular channel provides a clearance relative to the channel walls.

26. A machine according to Claim 25 in which the block member is adjustable within the annular channel whereby the clearance with the channel walls can be varied.

27. A machine according to any one of Claims 21 to 26 in which at least one obstruction is adjustable within the annular channel whereby the clearance with the channel walls can be varied.

28. A machine according to any one of Claims 21 to 27 in which at least one obstruction is a mixing element.

29. A machine according to any one of Claims 21 to 28 in which at least one obstruction is so constructed and arranged that the material is split into film-like layers adhering to the walls of the channel downstream of said obstruction.

30. A machine according to Claim 29, comprising an opening in the housing leading into the annular channel downstream of said obstruction so constructed and arranged that the material is split.

31. A machine according to any one of Claims 21 to 30 comprising means for circulating temperature control fluid.

32. A machine according to any one of Claims 21 to 31 comprising means for closing the outlet opening for batch processing of material in the annular channel.

33. A machine according to any one of Claims 21 to 32 comprising a plurality of annular channels arranged axially on the rotor adjacent one another.

34. A machine according to Claim 33 in which the outlet opening of one of the annular channels is connected with the inlet opening of a further annular channel by a conduit.

35. A machine according to either one of Claims 33 and 34 in which the annular channels are of similar geometric configuration.

36. A machine according to either one of Claims 33 and 34 in which the annular channels differ in geometric configuration from one another.

37. A machine according to any one of Claims 33 to 36, in which the outlet opening of one, or a plurality of annular channels is connected with the inlet opening of one, or a plurality of annular channels of similar, or different configuration, by means of one, or a plurality of conduits.

38. A machine according to Claim 37 in which each of the annular channels is provided with at least one obstruction extending into said channel.

39. A machine according to any one of Claims 21 to 38 in which an upstream wall of the block member is radial to the axis of the rotor.

40. A machine according to any one of Claims 21 to 39 comprising an intake chamber to which the inlet opening leads, the chamber extending across the channel and over a cylindrical surface of the rotor at an outer edge of and rotating with the annular channel and the chamber comprising a surface sloping towards said cylindrical surface of the rotor, the construction and arrangement being such that in the operation of the machine material is dragged by said cylindrical surface as the rotor rotates into the nip between the sloping surface and the cylindrical surface and thereby squeezed into the annular channel.

41. A machine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

42. A machine constructed, arranged and adapted to operate substantially as herein before described with reference to Figures 4 and 5 of the accompanying drawings.