CA1133216A

CA1133216A - Process for production of embossed resin products

Info

Publication number: CA1133216A
Application number: CA341,687A
Authority: CA
Inventors: John J. Rosenfeld
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-12-12
Filing date: 1979-12-12
Publication date: 1982-10-12

Abstract

A continuous process is provided for the extrusion of molten waste polyvinyl chloride material for producing embossed articles, e.g., automotive mats or runners, from waste thermoplastic material, e.g., reclaimed polyvinyl chloride. The process includes (a) continuously feeding solid waste polyvinyl chloride into the inlet of a milling and melting machine and continuously removing molten waste polyvinyl chloride through an outlet channel having an infeed end and an outfeed end, the outlet channel surrounding a screw extruder mechanism; (b) continuously impelling the molten waste polyvinyl chloride material through the outlet channel by means of rotation of the screw extruder from the infeed end and through an outlet aperture in the screw extruder at the outfeed end of the outlet channel; (c) placing a continuously movable segmented screen changer in the outlet channel across the path of the impelled molten waste polyvinyl chloride; (d) continuously filtering the impelled molten waste polyvinyl chloride material through clean portions of the segmented screen changer as the segmented screen changer moves continuously across the path of impelled movement of the molten waste polyvinyl chloride material; (e) placing an extrusion die in the outlet channel downstream from the segmented screen changer; and (f) continuously extruding the filtered waste polyvinyl chloride material as a filtered molten mass through the die. Preferably the process includes the step of (g) continuously drawing the extruded filtered molten mass between a pair of embossing rollers; thereby continuously producing the embossed articles. This process is at least ten times as fast as the conventional compression molding technique, and uses waste polyvinyl chloride efficiently and effectively.

Description

3~16 This invention relates to a continuous process for preparing embossed products from waste thermoplastic resinous material. More particularly, it relates to a continuous process for the production of embossed automo-bile mats from waste polyvinyl chloride resin. The invention also relates to apl)aratus for carrying out such process.
Automotive mats today are being made by compression molding. It would be desirable to replace this slow molding process by a fast, e.g., 30 - 60 feet a minute continuous system, with output rates of 1000 lbs/hr. or more, or at least ten times the current rates of production by compression molding.
In the production of polyvinyl chloride, an average of 5%
waste is created. This waste is classified as such for colour, particle size, contamination, etc. It would be desirable to provide a system whereby contamination is left after processing techniques may be substantially eliminated.
A difficulty in the past in providing a continuous process involving the use of waste polyvinyl chloride has been that the screening of whatever contaminants are contained in the molten polyvinyl chloride must be accomplished with~ut any significant pressure drop at the head. It would therefore be desirable to provide a system whereby screening of contaminants can be accomplished without any such pressure drop.
Accordingly, a broad aspect of the present invention is to provide a continuous process for producing embossed products from waste thermoplastic materials.
An object of a specific aspect of this invention is to provide a continuous process for producing embossed automotive mats and similar or allied products from reclaimed polyvinyl chloride.
An object of another aspect of this invention is to provide a - method and apparatus for continuously screening i~purities out of molten reclaimed polyvinyl chloride.
An object of another aspect of this invention is to provide a method and apparatus for the continuous embossing of reclaimed polyvinyl . - 1 - .

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, chloride in which any residual contami~ation is substantially eliminated.
By one aspect of this inven~ion, a continuous process is provided for the extrusion of molten waste polyvinyl chloride material which com-prises: (a) continously feeding solid waste polyvinyl chloride into the in-let of a milling and melting machine and continuously removing molten waste polyvinyl chloride through an outlet channel having an infeed end and an outfeed end, the outlet channel surrounding a screw extruder mechanism;
(b) continuously impelling the molten waste polyvinyl chloride material through the outlet channel by means of rotation of the screw extruder from the infeed end and through an outlet aperture in the screw extruder at the outfeed end of the outlet channel; (c) placing a continuously movable seg-mented screen changer in the outlet channel across the path of the impelled molten waste polyvinyl chloride; (d) continuously filtering the impelled molten waste polyvinyl chloride material through clean portions of the segmented screen changer as the segmented screen changer moves continuously across the path of ijpelled movement of the molten waste polyvinyl chloride material; (e) placing an extrusion die in the outlet channel downstream from the segmented screen changer; and (f) continuously extruding the fil-tered waste polyvinyl chloride material as a filtered molten mass through the die.
By another aspect of this invention, a continuous process is pro-vided for the extrusion of molten waste polyvinyl chloride comprising: (a) continuously feeding a solid thermoplastic formulation consisting essential-ly of reclaimed polyvinyl chloride into the inlet of a milling and melting machine, and continuously removing molten thermoplastic formulation through an outlet channel having an infeed end and an outfeed end, the outlet chan-nel surrounding a screw extruder mec}-anism; (b) continuously impelling the molten thermoplastic formulation through the outlet chanllel by means of ro-`~

~133Zi6 tation of the screw extruder from the inf~ed cnd and through an outlet aperture in the screw extruder at the outfeed end of the outlet channel;
(e) placing a continuously movable segmented screen changer in the outlet channel across the path of the impelled molten thermoplastic compositiOn;
(d) continuously filtering the impelled molten thermoplastie formulatiOn through clean portions of the segmented screen changer as the segmented screen changer eontinuously moves across the path of impelled movement of the molten formulation; (e) placing an extrusion die in the outlet ehannel downstream from the segmented screen changer; and (f) eontinuously extrud-ing the filtered molten thermoplastic formulation as a filtered molten mass through the die.
By~a variant thereof, the proeess ineludes the step of: (g) con-tinuously drawing the filtered molten mass containing reclaimed polyvinyl chloride between a pair of embossing rollers, thereby continuously produe-ing embossed articles.
By another variant, the thermoplastic formulation comprises waste polyvinyl chloride, a filler, dioctyl phthalate, soybean oil, stabilizers, stearie aeid and a suitable eolour.
By yet another variant, the thermoplastie formulation eomprises waste polyvinyl chloride, a filler, dioctyl phthalate, soybean oil, stabilizers, nitrile rubber, stearic acid and a suitable colour.
By another aspect of this invention, there is provided, in combination, (a) a machine for milling and melting a water polyvinyl chloride material, the machine including an inlet opening for solid waste polyvinyl chloride and including an outlet channel having an infeed end and an outfeed end, the channel surrounding a screw extruder therein, and having an inlet feeding the screw extl-uder, the screw extruder having an outlet aperture at the outfeed end of the channel; (b) means for rotat-ing the screw extruder, thereby to extrudc molten wast~ polyvinyl chloride;

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(c) a segmented screen changer disposed in the outlet channel and actuata-ble to move continuously across the path of molten waste polyvinyl chloride material impelled from the machine; and (d) a die disposed in the outlet channel downstream of the segmented screen changer in the path of the im-pelled filtered molten waste polyvinyl chloride material; whereby the im-pelled filtered molten waste polyvinyl chloride material is continuously extruded through the die.
By a variant thereof, the combination includes (e) a pair o, em-bossing rollers operatively associated with the outlet channel downstream of the die and adapted to grip molten waste polyvinyl chloride material ex-truded through the die and to draw it therebetween to be embossed.
By another variant, the combination includes (f) a pair of meter-ing pump sections therein, connected to the infeed end of the channel, each metering pump section including a screw extruder therein.
By a variation thereof, the screw extruder is cored to within 1/2" of its tip and is oil cooled to minimize possible overheating.
By another variation, the screw extruder has a 28 to 1 ratio.
By a further variant, the combination includes (g) a vent sec-tion in the milling machine, and a devolatizing pump in the vent section, for release of vapor generated due to the melting of the waste polyvinyl chloride.
By another variant, the combination includes a hopper crammer for the filling of a hopper feeding the solid polyvinyl chloride to tlle in-feed of the milling and melting machine.
By yet another variant, the segmented screen changer (b) com-prises (a) a frame member disposed across the outlet channel and including an inlet aperture connectable to the aperture in the screw impeller for providing a source of molten waste polyvinyl chloride to be urged there-against; (b) an outlet aperture in the frame member, downstrcam from the r~, - 4 -:

-~33'~
inlet aperture and fed from the inlet aperture; (c) a slide track disposedin the outlet channel between the inlet aperture and the outlet aperture;
(d) a connectible and disconnectible set of filter plates containing a plurality of filter screens, thereby providing segmented filter screens, disposed between the inlet aperture and the outlet aperture and slidable along the slide track; (e) a pair of cooling heat exchangers, one being dis-posed adjacent to and upstream of the inlet aperture and the other being disposed adjacent to and upstream of the outlet aperture in the direction of movement of the filter plates; (f) a pair of cooling heat exchangers, one being disposed adjacent to and downstream of the inlet aperture and the other being disposed adjacent to and downstream of the outlet aperture, in the direction of movement of the filter plates; (g) means for causing clean filter plates to move in the slide track across the path of the molten waste polyvinyl chloride material; and (h) means for removing dirty filter plates at a dirty filtered end of the slide track, and for placing clean filter plates at a clean filtering end of the slide track.
In the accompanying drawings, Figure 1 is a schematic flow diagram of the process of aspect of this invention;
20 Figure 2A is a side elevational view of the screw of another as-pect of this invention, used in the extruder combination of another aspect of this invention;
Figure 2B is a rear end view of the mixing head forming part of the screw shown in Figure 2A;
Figure 2C is a side elevational view of the mixing head shown in Figure 2B;
Figure 2D is a side elevational view of the shank of the screw shown in Figure 2A;

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, 11332i6 Figure 3 is a cross section througn a screen changer of another aspect OI this invention;

Figure 4 is a perspective view of a continuous filter changer of an aspect of this invention;
Figure 5 is a perspective view of four filter plates used in the continuous filter changer of an aspect of this invention;
Figures 6A - 6G are various plan views, elevational views, end views, and cross-sectional views of the die assembly used in the extruder of an aspect of this invention forming part of ~he embossing system;
Figure 7A is a side elevational view of the embossing roller machine forming part of the continuous embossing system of an aspect of this invention;
Figure 7B is an end elevational view of the embossing roller machine of Figure 7A;
Figure 8A is a side elevational view, Figure 8B is a circumferential layout and Figure 8C is a partial cross-sectional view of the surface of a water cooled double shell embossing roll for a twin front auto mat used in the embossing roller machine shown in Figures 7A
and 7B;
Figure 9A is a side elevational view, Figure 9B is a circumferential layout showing in outline the location of the gripper holcs, Figure 9C is a plan view of the orientation of the gripper holcs, and Figure 9D is a cross section through typica] gripper holes of n water cooled double shell twin rear back up roll showing gripper details of an embossing roller used in the embossing roller machinc shown in Figures 7A and 7B;
Figures lOA, lOB and lOC are partial cross-section depth sections showing ~he profile of embossing rollers used itl ~hc cmlossing roller machine of Figures 7A and 7B;

- 5 a -Figure llA is a side elevational view, Figure llB is a cir-cumferential layout showing in outline, the location of the g}ipper holes, Figure llC is a plan view of the orien~ation of the gripper holes and Figure llD is a cross section through typical gripper holes of a water cooled double shell twin front back-up roll showing gripper details of an embossing roller used in the embossing roller machine of Figures 7A and 7B;
Figure 12A is a side elevational view, Figure 12B is a circumferential layout and Figure 12C is a partial cross-sectional view of the surface of a water cooled, double shell embossing roll for a twin rear auto mat used in the embossing roller machine shown in Figures 7A
and 7B;
Figure 13A is a layout, and Figure 13B is a partial cross section showing the profile of an embossing roll for providing a twin rear auto mat, used in the embossing roller machine shown in Figures 7A and 7B;
and Figure 14 is a layout of an embossing roll for providing : a twin front auto mat used in the emlossing roller marlline shown in Figure 7A

and 7B.

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1~3321~

In one embodiment of this invention, the process starts with the waste polyvinyl chloride arrival. The material is automatically bulked into specialiæed equipment that classifies and pulverizes the particle size polyvinyl chloride to the micron size needed: one example is a 300 mesh size. This material is then blended with various ingredients, e.g., stabilizers, plasticizers, lubricants, etc., as will be described hereinafter. It is then blown into the extruder embossing line.
This polyvinyl chloride is then processed through a special system which will be described in detail hereinafter, which prepares a well mixed and substantially completely devolatized hot melt. This hot - melt is delivered to embossing rollers, which will be described in detail hereinafter, through a continuous filter screen changer, which will also be described hereinafter. When a bead of recycled polyvinyl chloride is delivered to the embossing rollers, the pressure drop would restrict flow and create a void which would result in unacceptable products. The modified continuous filter screen changer of a~other aspect of this invention sub-stantially prevents this pressure drop, as the plate with the screen is moving continuously at a predetermined time phase.
The pressure between the pair of embossing rollers conveys the extruded polyvinyl chloride through the system and simultaneously embosses the desired design thereon. The embossing rollers may also score cut to the final shape, i.e., the embossing rollers may optionally also die cut and score the embossed mat.
The pulverizer contemplated herein is, e.g., a modification of a wind swept mill to pulverize the oversize polyvinyl chloride under controllable temperature up to 165F. The pulverized polyvinyl chloride is then bulked into mixers, e.g., Henschell Intensive Mixers, and then is fed automatically into the extruders as a dry blend.
A preferred extruder is a 4-1/2" 150 H.P. SCR controlled extruder . . .

- , ' 11332i6 having the following features:
1. a hopper crammer;

2. a 28 to 1 ratio;

3 a screw with the combinat;on of a double heating and mixing head in each metering pump to circumvent the need for compounding waste polyvinyl chloride resin;

4. a devolatizing pump at the vent section;

5. a continuous screen changer that can be controlled to travel at whatever scheduled speed desired. This will keep a constant head pressure to assure an uninter-rupted flow from the die to the embossing unit, i.e., substantially to eliminate pressure drops at the head (die).
The continuous process of an aspect of this invention can be operated at speeds of 30 to 60 feet per minute output rates of 1000 lbs.
per hr. or ten times or more the current rates using compression molding from polyvinyl chloride resin w~ste~
Figure 1 shows a portion of the flow system from the waste polyvinyl chloride resin to the extruded molten polyvinyl chloride resin.
Waste polyvinyl chloride resin is char~ed into the system via line 10 which leads to a storage hopper ]1. ~aste polyvinyl chloride resin as it arrives is off-grade for colour, and heavy in off-size particle size distribution and viscosity. From hopper 11, the resin is scalped and screened and is vacuumed preferably by a Conair 10 H.P. vacuum pumping system 12 into the mill 13 via vacuum feed line 14. The mill 13 preferably is a wind swept type which can produce 2500 lbs. per hr. (150 H.P.). The resin is then blown via line 15 into separator 16 which includes a classifier 17 for particle size distribution.
The retention (faster or slower) is determined by the particle size distribution of the classifier 170 From the classifier 17, polyvinyl chloride is fed via suction ~133Z16 line 18 (desirably connected to another Conair vacuum pumping system) to a storage tank 19. The product from the storage tank 19 may be passed to the bagger 20, where it is bagged for future use, or it may be blown, via tube 21, through a surge line 22 and via suction line 23 to intensive mixer 24, (e.g., a Henschell Intensive Mixer), where it is mixed with suitable stabil-izers, plasticizers, lubricants, etc.

The product leaving the intensive mixer 24 passes through scale control 25 and is drawn by suction line 26 to an ~xtruder tank 27 provided with an extruder mechanism 28.
The wind swept mill is an integral part of the series of appara-tus comprising one aspect of the present invention. The wind swept mill is engineered on the following principle:
Air-swept pulverizers grind, self-classify and convey in one operation to produce powders of critical fineness in large volume from a wide range of grindable materials. Maximum efficiency in particle size reduction is obtained by combining two unique operating principles:
1. utilization of a controlled air stream and centrifugal force as the continuous milling classifying and conveying medium; and 2. simultaneous three-way particle size reduction (by impact, shear and air-turbulence attrition).
Processors benefit from the air-swept principle of fine grinding - 7 a -~133Z16 and the unique mill design in the following ways:
Optimum reduction in size of particulars into the particle size distribution required.
Continuous three-way milling and recycle grinding of oversize particles plus pneumatic conveyance assures a steady output in volume most favourable for the product being milled.
Grinding is normally cool through use of an air stream as the milling medium.
Internal self-classification with regrinding of oversize ensures narrow distribution of particle size and uniformity of the milled product.
The finalization of the product distribution required in terms of outputs of 2500 lbs. per hr. will be the ability to control horsepower draw in uniform stages to the limits of its capabilities, i.e., 2500 lbs.
at full 150 H.P. draw without pressure peaks. This is provided by control of the gaps between the head and the casing.
The oversize polyvinyl chloride waste will be processed in this wind swept mill at rates of 1000 to 2500 lbs. per hr. Particle size dis-tribution will be compatible to dispersion in the combination of a double heating and mixing head of the extruder to an average particle size of, e.g., 300 mesh.
The final gaps on the wind swept mill are thus utilized to provide the proper particle size. While, in the past standard gaps are 90 thousandth inch, in the present invention the gaps will be in the range of ~lOO thousandth inch. Retention control is by air and temperature by instrumentation. The working of the combination of a double heating and mixing head in the screw will allow achievement of the homogenation of the dry blend and deliver it at output rates of 1000 to 2000 lbs. per hr. to the screen changer and die without a pressure drop at pressures under 2100 P.S.I.
The extruder 27 and mechanism 28 forms another aspect of this invention. The screw has been designed to be compatible at all desired li33Z16 output speeds and is shown in Figures 2A - 2D. The structure shown in these Figures is self explanatory and so no further detailed description will be given at this time. Preferably, as shown, the screw is 9 lt2"

screw having a ratio of approximately 28 to l vented with the combination of a double heating and mixing head.
Such metering section mixing head preferably has a 50 thou-sandth inch clearance at the metering section. It preferably has 16 flats in its full diameter, in and out grooves with the high side, 50 thousandth inch clearance and is 9 l/2" long. The screw preferably is cored to within l/Z" of its tip substantially to substantially prevent any overheating by means of an oil cooling heat control.
An essential element in the apparatus and method of aspects of ; the present invention is the continuous screen changer which provides another aspect of this invention and this is shown in Figures 3-5 herein.
Screen changers for molten plastics extruder are old in the art. Each such screen changer serves the basic purpose of substituting a clean filter for a dirty filter. The problem is to accomplish this task in an operating extrusion line without changing either the pressure or temperature of heat sensitive polyvinyl chloride.

A typical extrusion line might operate with a pressure drop of 1500 P.S.I. in the period immediately following the insertion of a clean filter by a conventional slide plate screen changer. At that pressure, a certain quality and quantity of filtered end product can be expected downstream. However, as time passes with the filter remaining in the melt flow collecting contaminants, these impurities begin to form a build-up on the upstream side of the filter itself. The filter begins to blind. The greater the build-up on the upstream side of the filter, the greater the pressure drop experienced by the extrudate as it passes through the filter pack. These changes in pressure cause several detrimental phenomena to occur.
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First, the production rate of the entire line is reduced. A
partially clogged filter simply does not permit the same amount of m~terial to pass through it as a filter which remains clear. Furthermore, the greater pressure on the upstream side of the filter causes an increase in shear on the polymer and, concurrent with this, an increase in temperature.
In other words, the basic operating parameters of the entire extrusion process are completely changed causing the system to be in a state of constant readjustment and inconsistent operation.
A blinding filter is also expensive in terms of energy consump-tion because the extruder, or melt pump, must use more and more horse-power to overcome the rising back pressure at the screen.
Accumulation of foreign matter on the filter will eventually increase to the point where a complete screen change becomes necessary.
At this point, a conventional slide plate screen changer will fire its slide plate across the melt flow, removing the old filter and replacing it with a clean one. I~hen this happens, there is an immediate, dramatic change in operating pressure as the flow returns to its original pressure level. The entire line must now read3ust, stabilizing momentarily at the lower pressure before the new filter too begins to blind and the entire pressure/temperature cycle begins anew. After a filter change, the con-stant attention of an operator is essential, and the product being turned out during the stabilization period is often unacceptable, particularly in lines where critical products are being made.
This kind of irregular operation causes many difficulties in a line extruding blown film or fine filaments. Often an interruption, or severe change in flow, can cause a thin bubble of blown film to collapse, requiring that it be completely restrung through the tower, an arduous and time-consuming procedure at best. For this same reason, slide plate screen changers are simply out of the question for use in fiber extrusion applications where restringing hundreds of delicate filaments can be a matter of hours. The present filtering technique on lines of this sort is a sand pack - a fine filtration system which requires complete shut down or duplicate equipment and switch over valving in order to be changed.
Basically, the continuous screen changer of an aspect of this invention consists of a body, a set of filter plates, two pairs of heat exchangers and an operating mechanism which may be of several different types. This opera,ing device exerts pressure against the filter plates to slide them along a track and cause the filters which are supported on the upstream side of the plates to pass through the melt flow at a regular, programmable rate~ The heat exchangers on either side of the body are used to create a thermal seal formed by the polymer itself, thereby sub-stantially eliminating any need for the sort of complex and expensive clamping arrangements which had heretofore been the rule.
The overall effect of this continuous screen changer of an aspect of this invention is to allow an entire extrusion line to function at one constant temperature/pressure balance, a stability of operation which results in unsurpassed economy (far less horsepower and energy required), and previously unattainable end product consistency.
The main obstacle in the past preventing realization of a con-tinuous screen changer has been the failure to develop a workable sealarrangement. Mechanical seals demand a combination of elaborate engineer-ing, precise machining techniques and sophisticated metallurgy that has made them a nightmare to achieve and more difficult to maintain.
These difficulties have been substantially overcome in the present continuous screen changer of an aspect of this invention because all the mechanical devices have been replaced with a very, very simple sealing design utilizing the thermodynamic characteristics of the polymer itself to form the seal.
There are two phenomena which make the screen changer of aspects of this invention possible. First, any thermoplastic material will experi-: :`
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ence a drastic reduction in shear strength when heated to its softeningrange. In this weaker (but not fluid) state, the polymer will provide little resistance to a positive shear force, yet it will not flow through a long, narrow gap. Second, when polymer is chilled and solidified against a smooth surface, it can be slid off that surface relatively easily. It is a fortunate fact that most polymers exhibit these thermodynamic charac-teristics over a fairly broad and easily attainable temperature range.
; As seen in Figure 3, it is now possible to understand how the seal is formed.
` 10 Polymer in the line is under pressure which causes it to flow through the screen changer body and its maze of filtering media. This same pressure tends to force the melt out through the space between the filter plates and the body, and with no mechanical sealing force to pre-vent such leakage, that is exactly what happens. The polymer begins to ooze its way outward through these gaps. Before the polymer can reach the outer edge, it comes across an area which is being cooled below the freezing temperature for that particular material by the heat exchangers.
When it reaches this point, the polymer can no longer continue to flow in its liquid state, so it freezes into a solid sheet of hardened plastic (typically 0.002" to 0.005"). This sheet of plastic is the seal, a seal which is continuously being formed and then passing out of the machine with the movement of the filter plate to be replaced by more hardened plastic.
In practice, the filter plates are placed in the screen changer before starting the extrusion line. The body is then heated to operating - temperature while the cooling air is turned to the "full on" position in the heat exchanger zones. (In some instances water or other heat exchanger liquid is used). This cools the seal area sufficiently to freeze the polymer. Adjustable dampers are used so that seal area temperatures may be varied to adapt to a variety of polymers. Virtually any material which ~1332i6 exhibits the characteristic of changing from a liquid to a solid over a definable temperature range can be filtered using this apparatus.
This unique sealing system substantially eliminates any need for expensive self-lubricating seal materials, specially heat-treated slide plates and exact machining. There is no need for constant retightening of seals either, because there is no longer any wear-producing friction, or any mechanical seals at all.
Since massive clamping systems are no longer required, the physical process of changing a screen is also greatly simplified because there are no tremendous frictional forces to be overcome. 177ith frictional resistance greatly reduced, it is possible to move the filter plate across the melt flow with a fraction of the force required in the past. Substan-tial energy savings can thus be realized in addition to the significant reduction in equipment cost when the massive hydraulic unit is eliminated.
Thus, as seen in Figure 3, the molten polymer flowing as shown by arrow 410 passes througll the outflow nozzle 411 of the machine body 412.
The transverse space between the upstream portion 411a of the nozzle 411 and the downstream portion 411b of the nozzle 411 provides a filter space 413, within which the continuously travelling filter 414 travels. Disposed on both the longitudinal sides of the nozzle 411 are cooling heat exchan-gers 415.
The filters operate as described above. Portion 414a permits the molten polymer to be filtered and pass through in the direction of arrow 416. Downstream portion 414b and upstream portion 414d provide seals by the "frozen" polymer. Downstream portion 414c is the dirty filter, while upstream portion 414e provides a clean filter.
A series of three filter plates which interlock end-to-end are used to transport the screen belt across the melt flow. Once these three travel their full length, the operator disconnects them and transports them to the driving side again. The cylinder at the end of its stroke , .

:1133216 returns to the start position. This is shown more clearly in Figures 4 and 5.
As seen in Figure 4, the main body 412 at the terminus of the screw feeder (not shown) includes a central circular nozzle 411. A trio of filter plates 420 (see Figure 5) are fitted to slide in upper 421 and lower 422 slide channels. Filter plates 420 are interlinked in a manner to be described hereinafter, and are hollow rectangular parallelepiped frames to transport the filter members 414.
Extending vertically at the downstream and upstream sides of the nozzle 411 (relative to the movement of the filter plates) and on each side face of the filter plates, are air-cooled heat exchangers 415. Cooling air is admitted through conduit 423 controlled by air controllers 424, 425.
An operating mechanism comprising a hydraulic or pneumatic cylinder 426 having an operating rod 427 engages with an end of a filter plate 420. The cylinder 426 is so progarmmed that as one filter plate 420 passes out of the channels defined by 421 and 422, at the outfeed end, the rod retracts enabling the "dirty" filter in the filter plate to be replaced by a clean filter, and to have the filter plate containing a "clean" filter placed in the infeed end and is again engaged by the rod 427. Thus, the filtering operation is substantially continuous.
As seen in Figure 5, each filter plate 420 includes a hollow framework 430. The upper framework includes a rectangular vertical keyway 431 at the leading edge 432 and a projecting cooperating key 433 at the trailing edge 434. Similarly, the bottom framework 435 includes a compat-ible key 436 at the leading edge 432 and a compatible vertical keyway 437 at the trailing edge 434. Since each filter plate 420 is identical, they may be "hooked together" by cooperation between keys 433/keyways 431 and keyway 437/key 436. Four such filter plates are shown.
The extruder and extruding mechanism of this aspect of the ~33Z16 invention also include an extruding die which is in the filtered molten polymer flow path downstream of the continuous filter screen. The die preferably is of the coat hanger style and one embodiment thereof is - shown in Figures 6A - 6G~ The structure shown in these Figures is self . explanatory and so no further detailed description will be given at this time. It is noted however that the lip has been modified to control the ~i~ desired flow pattern. The interior of the die is streamlined to minimize restrictions in flow of the molten polyvinyl chloride. Restrictions bars are also provided to control the flow pattern.
The filtered polymer after being extruded through the die passes into the embosser which includes counter-rotating embossing rollers.
The embossing roller machine is shown in Figures 7A and 7B. The structure shown in these Figures is self explanatory and so no further detailed description will be given at this time.
The embossing rollers are steel rolls which are embossed and/or score cut to their final weight and die cut performance. Various configurations of such rollers as used in the machine of Figures 7A and 7B are shown in Figures 8A - 14. The structure shown in these ~igures is self explanatory and so no further detailed description will be given at this time.

The following are two typical base formulas:
Base Formula for Vinyl Automotive Mats Polyvinyl chloride 52 lbs.

; Eillers (known by the Trade Mark MIN~X
with a refractive index close to polyvinyl chloride) 13 lbs.
Dioctyl phthalate (to softness required) 20.8 g Soybean oil 908 g Lar stabilizers 1100 g Stearic acid 40 g Master Batch Blue (colour is required) 800 g ~`~
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' ~133Z16 ; Base Formula for Rubber Vinyl Mats Polyvinyl chloride 36 lbs.
Filler with a refractory index close to polyvinyl chloride 18 lbs.
Dioctyl phthalate 22.6 g Soybean oil 3 lbs.
Stabilizers 1.5 lbs.
Nitrile rubber 10.8 lbs.
Stearic acid 40 g Colour 800 g In the start up of the overall process of an aspect of this invention, the gap sizes in the wind swept mill are adjusted to reach the desired particle size and output, synchronized to horsepower. The for-mulas are blended and tested for the physical properties required. The extruder screw is tested with the various formulations. The melts at the various levels are adjusted to operate at back pressures not in excess of 2100 P.S.I.
~le continuous screen changer is operated to move at the desired speed starting up to 2" per minute. Resulting pressure drops and die ~ flow configurations are adjusted to satisfy the parameters of the process.
All formulas, synchronized to the screw and continuous screen changer without vent flow are finely adjusted. Then the embossed rollers will be positioned and the test made for die cut and weight requirements.
The polyvinyl chloride mat will have the required physical properties and flexibility.

~33Z16 T'ne apparatus elements shown and described herein are all related to the intergrated systems of which key components are, 1. the air swept mill which substantially eliminates cryogenics; 2.
screw design for the secondary dry blend waste; 3. continuous filter changer for the plasticized polyvinyl chloride waste; and 4. the embossing of automotive mats and allied products.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A continuous process for the extrusion of molten waste poly-vinyl chloride material which comprises:
(a) continuously feeding solid said waste polyvinyl chloride into the inlet of a milling and melting machine and con-tinuously removing molten waste polyvinyl chloride through an outlet channel having an infeed end and an outfeed end, said outlet channel surrounding a screw ex-truder mechanism;
(b) continuously impelling said molten waste polyvinyl chloride material through said outlet channel by means of rotation of said screw extruder from said infeed end and through an outlet aperture in said screw extruder at the outfeed end of said outlet channel;
(c) placing a continuously movable segmented screen changer in said outlet channel across the path of said impelled molten waste polyvinyl chloride;
(d) continuously filtering said impelled molten waste poly-vinyl chloride material through clean portions of said segmented screen changer as said segmented screen changer moves continuously across the path of impelled movement of said molten waste polyvinyl chloride material;
(e) placing an extrusion die in said outlet channel down-stream from said segmented screen changer;
and (f) continuously extruding said filtered waste polyvinyl chloride material as a filtered molten mass through said die.

2. A continuous process for the extrusion of molten waste poly-vinyl chloride comprising:
(a) continuously feeding a solid thermoplastic formulation consisting essentially of reclaimed polyvinyl chloride into the inlet of a milling and melting machine, and continuously removing molten said thermoplastic formu-lation through an outlet channel having an infeed end and an outfeed end, said outlet channel surrounding a screw extruder mechanism;
(b) continuously impelling said molten thermoplastic formu-lation through said outlet channel by means of rotation of said screw extruder from said infeed end and through an outlet aperture in said screw extruder at the outfeed end of said outlet channel;
(c) placing a continuously movable segmented screen changer in said outlet channel across the path of said impelled molten thermoplastic composition;
(d) continuously filtering said impelled molten thermoplastic formulation through clean portions of said segmented screen changer as said segmented screen changer continu-ously moves across the path of impelled movement of said molten formulation;
(e) placing an extrusion die in said outlet channel down-stream from said segmented screen changer;
and (f) continuously extruding said filtered molten thermoplastic formulation as a filtered molten mass through said die.

3. The process of claims 1 or 2 including the step of:
(g) continuously drawing said filtered molten mass containing reclaimed polyvinyl chloride between a pair of embossing rollers;
thereby continuously producing embossed articles.

4. The process of claim 2 wherein said thermoplastic formulation comprises waste polyvinyl chloride, a filler, dioctyl phthalate, soybean oil, stabilizers, stearic acid and a suitable colour.

5. The process of claim 2 wherein said thermoplastic formulation comprises waste polyvinyl chloride, a filler, dioctyl phthalate, soybean oil, stabilizers, nitrile rubber, stearic acid and a suitable colour.

6. In combination:
(a) a machine for milling and melting a waste polyvinyl chloride material, said machine including an inlet open-ing for solid said waste polyvinyl chloride and including an outlet channel having an infeed end and an outfeed end, said channel surrounding a screw extruder therein, and having an inlet feeding said screw extruder, said screw extruder having an outlet aperture at the outfeed end of said channel;
(b) means for rotating said screw extruder, thereby to ex-trude molten waste polyvinyl chloride;
(c) a segmented screen changer disposed in said outlet chan-nel and actuatable to move continuously across the path of molten waste polyvinyl chloride material impelled from said machine;
and (d) a die disposed in said outlet channel downstream of said segmented screen changer in the path of said impelled filtered molten waste polyvinyl chloride material;
whereby said impelled filtered molten waste polyvinyl chloride material is continuously extruded through said die.

7. The combination of claim 6 including:
(e) a pair of embossing rollers operatively associated with said outlet channel downstream of said die and adapted to grip molten waste polyvinyl chloride material extruded through said die and to draw it therebetween to be em-bossed.

8. The combination of claim 6 including:
(f) a pair of metering pump sections therein connected to said infeed end of said channel, each said metering pump section including a screw extruder therein.

9. The combination of claim 8 wherein said screw extruder is cored to within 1/2" of its tip, and is oil cooled to minimize possible overheating.

10. The combination of claim 8 wherein said screw extruder has a 28 to 1 ratio.

11. The combination of claim 6 including:
(g) a vent section in said milling machine, and a devolatiz-ing pump in said vent section, for release of vapor generated due to the melting of said waste polyvinyl chloride.

12. The combination of claim 6 including:
(h) a hopper crammer for the filling of a hopper feeding said solid polyvinyl chloride to the infeed of said milling and melting machine.

13. The combination of claim 6 wherein said segmented screen changer (b) comprises:
(a) a frame member disposed across said outlet channel and including an inlet aperture connectable to said aperture in said screw impeller for providing a source of molten waste polyvinyl chloride to be urged thereagainst;
(b) an outlet aperture in said frame member, downstream from said inlet aperture and fed from said inlet aperture;
(c) a slide track disposed in said outlet channel between said inlet aperture and said outlet aperture;
(d) a connectible and disconnectible set of filter plates containing a plurality of filter screens, thereby pro-viding segmented filter screens, disposed between said inlet aperture and said outlet aperture and slidable along said slide track;
(e) a pair of cooling heat exchangers, one being disposed adjacent to and upstream of said inlet aperture and the other being disposed adjacent to and upstream of said outlet aperture in the direction of movement of the filter plates;
(f) a pair of cooling heat exchangers, one being disposed adjacent to and downstream of said inlet aperture and the other being disposed adjacent to and downstream of said outlet aperture, in the direction of movement of said filter plates;
(g) means for causing clean filter plates to move in said slide track across the path of said molten waste poly-vinyl chloride material;

and (h) means for removing dirty filter plates at a dirty filtered end of said slide track, and for placing clean filter plates at a clean filtering end of said slide track.