SE439490B - MICROBITES OF EXPANDED THERMOPLAST AND PROCEDURE FOR ITS PREPARATION - Google Patents

Description

J I lO 50 QO 7800560-0 writing papers, which are individually coarsely squeezed in the hand and then allowed to return to the degree made possible by the resilience when releasing the pressure by opening the hand.

Further examination with SEM in other magnifications as at (i) l800 x (in attached fig. 3) of part of the same position as in Pig. H shows formations of what appear to be separate and distorted contours of broken boundaries of, before the fracture, an expanded honeycomb pattern of cells' hexagonal and pentagonal cross-sections, (ii) MOOO x (in Fig. 2) shows that they are very reminiscent about randomly spread and partially overlapping not completely open rose petals. Other magnifications with SEM in the range from 500 x to 5000 x show that the microbites resemble very small coral formations (at least in Figs. 7 to 9) in wave-like appearance (magnified 1000 x as in Fig. 10) and in a slightly rippled grooved formation ( magnified 10,000 x, Fig. 11 and lä, and 000 X in Figs. 12 and 15).

The term "styrene polymer" includes not only polystyrene, but also thermoplastic polymers of any polymerizable substituted styrene, as well as copolymers of styrene with one or more other compatible polymerizable substances such as nuclear alkylated or halogenated styrenes such as ring-methyl- or chloro-substituted styrenes. or even alpha-methylstyrene or with beta-unsaturated esters, ethers, amides or nitriles of acrylic acid and their alpha-alkylated homologues, vinyl esters of aliphatic and aromatic carboxylic acids, N-vinyl compounds of N-vinylcarbazole, N-vinylimidazole or N -viny pyrrolidone.

Such thermoplastic copolymers of styrene should usually contain at least about 50% by weight of styrene, or styrene may be the predominant component or be present in at least as much as any higher component present in any terpolymer. The copolymers of styrene also include any of the various impact polystyrenes which contain a major portion of styrene and a minor portion of a styrene-butadiene rubber (commonly referred to as SBR, sometimes referred to as Buna-S) which is prepared, for example, by emulsion polymerization of about 75 portions of butadiene. and about 25 parts of styrene. Thus, the styrene polymers also include styrene alloys (ie, pressure or melt blends) of polystyrene with other compatible polymers usually of ethylenically unsaturated monomers.

The term "polyethylene" in the term "an expanded polyethylene" or "a polyethylene" refers to a high molecular weight product (at least 6000) and is generic as comprising low density polyethylene (specific gravity less than 0.92), the high density product (specific density above 0.9 Å, 10 50 RO 7800560-0 usually 0.9 H1 to 0.965) and the polymer product having an average density (a mixture of both high and low) as well as impregnable polyethylene (for example an extruded melt mixture of polyethylene with 10 Z polystyrene , which may be called "polyethylene-polystyrene alloy"), all of which are available in the form of flakes or cubes similar to polystyrene groats.

The term "small pieces" includes any of the divided free-flowing forms of any styrene polymer and any of the polyolefins from polyethylene to polymethylpentene, such as the various sizes of granules prepared by cutting or extruded polymer in short lengths, usually called groats or crystals (as is the case with a styrene polymer) or groats or cubes of a polyethylene-polystyrene alloy, the different sizes of styrene polymer beads obtained by suspension polymerization or otherwise by e.g. forms the obtained particles by decomposing any of these different polymer forms and the so-called "grinding" including coarsely ground polymer or waste or other wastes of such polymer (of varying size, eg thickness 0,3 cm, 0,6 cm wide and 0,9 cm long) and any other molds with small size of any of these.

Small pieces of expandable styrene polymer can be prepared by conventional and suitable known methods, e.g. by preparing small pieces of expandable styrene polymer, as described in U.S. Pat. No. 2,983,692. An expandable polyethylene-styrene alloy can be prepared in a similar manner. Small pieces of expandable styrene polymer can be prepared from expandable polystyrene by suitable known methods. According to a process for producing small pieces of expandable styrene polymer, they are heated, for example with air or water vapor, described in U.S. Pat. No. 2,983,692 (column H, lines 65-69), "to a temperature higher than that of the styrene polymer. softening point "described in U.S. Pat. No. 3,010,95U (column, lines 20-23). See also U.S. Pat. No. 3,259,559H (column 2, lines 2U-27). Small pieces of expanded polyethylene-polystyrene alloy can be produced in a similar manner.

Expanded small pieces of polyethylene, polypropylene, polybutene or polymethylpentene can be prepared by preparing the respective corresponding expanded polyolefin according to suitable known methods, incorporating with the special polyolefin (before extrusion) a chemical foaming agent (a so-called pneumatogen, usually a complex nitrogen-containing organic compound, which decomposes at the extruded temperature during the release of nitrogen gas), and the spray temperature is regulated so that the penumatogen agent decomposes when the polyolefin leaves the spray nozzle outlet as summarized in Allin's Publishing Extrusion Technology by Plastícs Publishing L. Corp .; New York, N.Y. 1968, p. 221, after which the expanded polyolefins are reduced to small pieces by cutting or otherwise.

Certain physical properties of the microbits of the present invention are shown by photomicrographs of the dry microbubbles in the first fifteen figures of the accompanying drawings, of which Figs. 1 - 9, 1a and 15 relate to microbicides of polystyrene and Figs. low density polyethylene and in which Fig. 1 is a photomicrograph at magnification 161 x by emitted light; Fig. 2 is a SEN photomicrograph of the microbits at a magnification of H000 x; Fig. 5 is an enlarged photomicrograph 1800x of approximately the area which gave the lower left quarter shown in Fig. Ä; Fig. H is a photomicrograph SBM at magnification 360x; Fig. S is a photomicrograph taken at a magnification of 100x; Fig. 6 is a photomicrograph SEM at a magnification 500x of the area which gave the illustrated center portion of Fig. 5; Fig. 7 is a photomicrograph SEN at a magnification 1000x of the area which gave the illustrated portion of Fig. 6; Fig. 8 is a photomicrograph SEM at a magnification 2000x of the area which gave the prominent right portion of Fig. 7; Fig. 9 is a photomicrograph SEM at magnification 5000x and shows the area shown in the lower right quarter of Fig. 8; Fig. 10 is a photomicrograph SEM at magnification 1000 x showing microbubbles of polyethylene and obviously of the position which gave the area in the lower left quarter of the upper right quarter of Fig. 13; Fig. 11 is a photomicrograph SEM at a magnification of 10,000 X and encompassing the inclined area visible approximately in the middle of Fig. 10; Fig. 12 is a photomicrograph SEM at magnification 000x and covers the inclined area shown in lower magnification approximately in the middle of Fig. 11; Fig. 13 is a photomicrograph SEM at magnification 380x of the same microbubbles of polyethylene as shown in Figs. 10-12; Fig. Lü is a photomicrograph SEM at a magnification of 10,000 x of microbits made of polystyrene and Fig. 15 is a photomicrograph SBM at a magnification of 20,000 x of an inclined area of polystyrene microhites shown in Fig. 14. Fig. 16 is a schematic illustration of a system for removing the entrapped water from the microbubbles of the invention, as obtained in the aqueous slurry starting from the atomizing device, wherein the microbubbles are prepared from the expanded starting polymer (described in more detail in Example 2). below). The expanding microchips according to the invention are prepared by continuously feeding expanded small pieces of a styrene polymer or any of said polyolefins and water into a limited and finely decomposing zone, having a feed inlet, repeatedly propelling the resulting mixing the starting pieces in the water through a circulating path by repeatedly striking the pieces in the water of a plurality of striking surfaces, spaced apart and rotating about the axis of the circular path at a speed of from about 4700 to about 8000 rpm, and simultaneously driving these striking surfaces the expanded small pieces to and against corner-shaped edges of a dispersed plurality of substantially circular openings (a) having a diameter of from about 0.102 to about 5.175 mm to substantially rectangular openings having a width of from about 0.25M to about 5.175 mm and length from about 5.81 to about 12.7 mm and (b) these are arranged in a screening pattern in a curved plane which is radial t separated out of reach of the striking surfaces to such an extent that it only needs to be sufficient to avoid a collision between the openings and the bearing surfaces, e.g. from about 0.508 to 1.06 mm, whereby the small pieces of each expanded polymer are torn, cut and sheared into microbubbles and the amount of water added is adjusted so to the added amount of small pieces of expanded polymer that the contents of the atomizing zone are prevented from reaching a temperature would affect the integrity of the output pieces and / or the desired microbits.

The production of these microbubbles of styrene polymer or of a polyolefin (from polyethylene to polymethylpentene), and consequently also the process according to the present invention, can be carried out by disintegrating and expanding small pieces of starting styrene polymer or polyolefin in a atomizing machine (e.g. proposed by the Fitzpatrick Company at 832, Industrial Drive, Elmhurst, Illinois 60126, USA, according to their Bulletin No. 152, copyright 1968) using cutting edge fixed blades (identified therein by "Code DS-225") for to replace blades or other atomizing means, mounted for rotation in the atomizing chamber of model DASO6, both shown on page. 5 in this bulletin.

This chamber is liquid-tight closed e.g. of a cover, which is shown in their "code MüÄD6" or "Code MAMHD6" (upper half of page 3 of the said bulletin 152).

The atomizing chamber of model DAS06 has a rectangular, horizontal section and has a pair of opposite parallel and completely vertical walls, which are joined at each of their opposite ends by a separate wall of a pair of opposite, vertically curved 10 ß. ) LD 50 55 BO 1 7800560-0 walls each with its convex surface facing outwards.

Sixteen identical, rib-shaped atomizing arms are separately detachable but firmly supported with their snug-fitting and adjacent bases circled around and locked to the drive shaft and intermediate its free outer mounting ends. These arms extend radially from the shaft (eg 127 mm from its axis to the outer end of each arm), the first in each group of four consecutive of these arms extending horizontally against a curved wall, the second in each group of four extends vertically, the third in each group of four extends towards the second curved wall and the fourth in each group of four extends vertically downwards.

Each arm has a rectangular section in a plane, which runs through the entire length of the center of the shaft and the length of the arm and through the arm separated by 1800 from it. The outer end of the Tarje arm angles its two wider sides (width 25, H mm) and the sloping side (width 9.525 mm) facing the direction of rotation also meets at right angles the two wider lengths of each meet at right its narrow or gen. This narrow sides, which are parallel to each other along most of their width and with the rear third of their surfaces tapered towards each other and ending in a knife edge at the rear end.

Each exposed end of the shaft extends through its respective stuffing box at its adjacent end of the two parallel vertical walls, further through a bearing supported on a respective pin attached to the machine foundation and spaced outwardly away from the respective. wall.

The one-door pulley is mounted on each shaft end, which extends outwards from its resp. mounting pin.

The bottom of the atomizing chamber is a replaceable bowl-shaped and curved sieve convexly curved downwards with an inner diameter (from the center of the drive shaft) equal to the length of an atomizing arm plus a clearance of 0.762 mm). The total rectangular circumferential opening of the sieve has such a dimension and shape that it can be releasably fitted for liquid-tight cooperation with the bottom of the four walls of the atomizing chamber.

The screen has zigzag staggered rows of, for example, circular holes with diameters ranging from 0.102 to about 5.175 mm arranged close to each other and with sufficient space between them for the screen to hold under the operating conditions.

The lid of the chamber, with the exception of the inlet of the filling hopper for supplied starting material at one side, is curved and convex upwards with a radius (from the center line of the drive shaft) which is sufficient for the rotating arms to have a clearance of 0.762 mm from the inwardly facing the surfaces of a plurality (e.g., three) of pre-rupture arms (about 20.52 cm long and 6.55 mm wide) projecting by 1.5 mm along their entire length into in the interior of the atomized chamber, and extending spaced apart parallel to the centerline of the drive shaft.

The selected drive pulley on the drive shaft is coupled by means of drive belts from a motor shaft drive pulley, and can be driven at speeds in the range from about 70,000 to about 8,000 rpm, and more efficiently from about 5,000 to about 7,500 rpm.

The microbits of the present invention have different areas of application such as e.g. to filter and improve fluid, both liquid and gaseous. This is accomplished, for example, by mixing the selected microbubbles of styrene polymer or polyolefin into the liquid to be improved and then filtering them out, or by filtering the liquid to be improved through a bed of the microbubbles. The polymer microbubbles thereby remove invisible and loose or invisibly suspended organic material from the liquid and usually leave the liquid free from evolution of this material even after long storage.

For illustrative purposes, tap water drained in Matawan, New Jersey, USA, was filtered through a Whatman No. 2 filter paper in an amount of U75.2 cm 3 down into a first pure Mason jar with a volume of 9U6.5 cm 3 carefully sealed. the microbubbles (prepared from small pieces of expanded polystyrene) were wetted with about 20 cmš of water from the same tap, mixed with about U75.2 cmš of the tap water and then filtered through as then another filter paper Whatman No. 2 into a similar second clean Mason jar with volume 914653 a? and tiiisiöts tightly.

A week later, a slight yellow haze could be noted in the first jar, but the water (mixed with the micro-pieces) in the second jar was still completely clear. The yellow turbidity in the first jar increased in amount and density with later precipitation to the bottom of the jar during an observation period of three months. However, the water filtered through the polystyrene microbubbles into the second can was still completely clear.

To illustrate use in filtering and improving a gaseous fluid, these polymer microbubbles can also be used as packing material in air filters by mixing with suitable paper fibers and preparing into sheets for use in air filter frames.

Comparable results from liquid and gas filtration are obtained by microbubbles of a polyethylene. Microbits of the other polyolefins are also useful.

Certain batches of these polymer microbubbles, prepared according to the invention, e.g. by means of the above-described comminuting machine using a screen with circular openings of certain sizes, is obtained containing varying amounts from very small or sometimes up to about 20% or thereabouts of fibrous particles having even finer size than in the ranges described above, such as down to widths of 15 or 10 μm. Usually, the presence of any such quantities of these smaller sizes does not cause any inconvenience to the particular intended use of the microbubbles.

However, if required, these finer sizes can be removed by filtering out by means of available screening means or other suitable means, e.g. a high-capacity centrifugal holder manufactured by Kason Corp., Newark, New Jersey, USA. The microbubbles are uniformly fed with a feed screw with outlet into a helical paddle which rotates in a horizontally located cylindrical sealing chamber, wherein the centrifugal force accelerates the movement of the microbite particles towards the screen, which is attached to its cessation basket. to vibrate freely.

In carrying out the present process, the operating conditions can cause an increase in the temperature of the charged small pieces of styrene polymer or polyolefin, which decompose in the atomizing zone. This may be more prominent in some styrenic polymers than in others, so that in some cases the temperature increase may reach a level such that at this temperature and higher, non-tiny pieces of the styrenic polymers can be torn or sheared easily or satisfactorily under prevailing operating conditions. and they may also have a tendency to prolong or otherwise modify the reaction of the material being treated, thereby affecting adversely desired tearing or shearing of the blank pieces or what has already been torn or sheared away from them. This should be avoided, for example, by adding larger amounts of water with the small pieces.

The finished atomized polymer microbubbles, emanating from the atomizer, clearly show the water holding property to a degree of from about HO to 50 times their own dry weight, and with the water thus retained they form a non-fluidized plastic mass which can be deformed and rolled without to become fluid. The water is not released from this mass during drainage or ordinary filtration, but requires pressure or suction, but the mass still retains a considerable amount of water. High pressure, for example, reduces the mass to a water content of only about 50%.

Thus, the amount of water introduced into the atomizing chamber should be at least sufficient for the mixture of water and prepared polymer microspheres to be sufficiently fluidized to flow easily through the openings in the atomizer screen. The amount of water should suitably be from about 55 to about 100 times the weight of microbubbles produced from a modified styrene polymer.

It is advantageous to mix the starting pieces of expanded styrenic polymer or polyolefin with an amount of water sufficient to substantially completely wet their exposed surfaces before being fed into the atomizing chamber.

It is also advantageous to carry out the procedure according to the invention. the small pieces in the finely divided zone are driven by the impact surfaces alternatively (i) to and towards corner edges of at least one pre-breaking surface or impact surface (of at least one pre-breaking rod described above in the paragraph beginning on page 6 and ends on page 7) spaced circumferentially away from the openings and radially similarly out of reach of the striking surfaces as the openings are, and then (ii) to and towards the openings.

It is also favorable if the percussion arms are axially and angularly separated from each other.

In certain applications of the microbial or polyolefin microbubbles, they may be used with the water held by them, or any minor amount retained after application of pressure or vacuum, or both, in order to remove as much of the possible , as desired.

In order to remove the rest of the water when it is desired to obtain dry microbubbles, the product is in one way frozen with the water content remaining after partial water removal by means of pressure and / or vacuum.

The frozen micro-pieces are then left to thaw or heated to thaw and reach a temperature which is just above the freezing temperature or up to the ambient temperature, at which the still retained water is freely drained away. When the entire amount that can be drained has given off, the remaining water can be squeezed out and / or removed with a vacuum followed by final drying.

Another and more practical way of removing the water held by the microbubbles emitted by the atomizing means is further described in the following in relation to the system illustrated in Fig. 16.

The invention is illustrated by, but not limited to, the following working examples.

Example 1 - Microbites of expanded extruded polystyrene groats N25 l with expansion agent impregnated extruded polystyrene groats (crystals) expanded from about 6.35 to about 19? mm mainly round groats with a bulk density of g per liter were atomized in a kn l5 FJ k) I 'zaoosso-o w ._- atomizing machine (described on page 5, paragraph 2 - page f paragraph 3) provided with an inlet feeder with a diameter of 10.16 cm and a length of 7.6 and a curved bottom screen with holes having a diameter of 0.66 mm.

The rotor was set to operate at 6,000 rpm and the feeder was adjusted to charge the expanded polystyrene manifolds at a speed of 35.1 liters per 5 minutes (ie H25 liters per hour). The starting small pieces of expanded polystyrene, which were to be introduced into the feeder, were wetted with a sufficient amount of water to substantially completely cover their outer surfaces. The so-wet small pieces of expanded polystyrene were continuously charged to the feeder at a rate of 35.1 liters per 5 minutes, while injecting water into the atomizing chamber through the two jet openings with a diameter of 1.6 mm at a rate of 7.57 liters per minute.

The mixture of microbubbles of expanded polystyrene starting from the screen bottom of the atomizing chamber was collected in open cylinders with drainage pins in the bottom, in which the free water sank to the bottom and the polystyrene microbubbles with bound water held by them in the proportion 2 parts microbits per 98 parts water, step , thanks to trapped air, to the upper surface of the open water. The free water was drained, leaving a plastic mass of (decomposed) microbubbles of expanded polystyrene in the water physically bound to them. The plastic mass weighed 255.15 kg and contained 5.1 kg of microbubbles with 250.05 kg of water bound to them. 27.2ü kg of the plastic mass was then placed in a bag of tightly woven, double cotton fabric and subjected to pressure until 22.71 liters of water were squeezed out. The remaining .08 kg containing Shn g microbubbles of expanded polystyrene were then dried in an open oven dish at UEOC. In this context, for example, microbubbles, prepared according to Example 1 from expanded polystyrene fragments prepared from new polystyrene (sometimes referred to as "prime") having a density of 1.1, showed a density of 1.0. This density is thus 90.9%. of the density of the original starting polystyrene crystals, from which the small pieces of expanded polystyrene were prepared, which in turn formed the starting material for the finished microbiits of polystyrene, The density of the dry microbites according to the invention is thus substantially the same as the density of the expanded styrene polymer from which it expanded. the styrene polymer was prepared which in turn was used as a starting material for the preparation of the present microbubbles.15 KU UW UO ll 7800560-0 Example 2 - Expanded impregnated polystyrene waste Approx. 2.5 cm long pieces of impregnated polystyrene waste with a bulk density of 16 g per liters were treated with the same steps as in Example 1, but fed at a rate of 28.32 liters per 6 minutes. and with the rotor set at 6500 rpm, thus obtaining a plastic mass similar to that obtained in Example 1, except that it exhibited a lighter shade of gray-pink than the main mass of the impregnated starting waste.

If one replaces the starting pieces of expanded polystyrene in each of Examples 1 and 2 with a different amount of small pieces of arbitrary density of expanded new or waste polystyrene, any expanded styrene-acrylonitrile copolymer, any other expanded styrene polymer or any any other polyolefin useful herein described above, and if one separately repeats the respective steps of any of these examples with the same or slightly different water proportions or other rotor speeds, the corresponding relatively similar microbubbles of any other expanded styrene polymer, or of any other preferably polyolefin usable described above. The respective corresponding additional examples are to be construed as being presented in full printed form in order to avoid that the present description becomes too extensive.

I By replacing the sight bottom in the atomizer, described above (see p. 6, lines 27 - 36) with a sight of the same total dimensions, but instead showing a herringbone pattern of rectangular openings, 12 ,? mm long and 0.25U mm wide, and using the thus modified atomizer repeatedly Examples 1 and 2, the selected starting material of expanded styrene polyurethane strands or small pieces of expanded polyolefin similarly gives a yield of the same type of respective end product of microbites, which essentially completely or completely to 100% has a width of 5 to 15 μm, varying lengths up to about 325 μm and is from substantially completely to completely free of intact cells.

The at least 98% of water contained in the fluid mixture or slurry of microbubbles of styrene polymer or polyolefin in water starting from the atomizer, e.g. according to Example 1 or 2 or any modification thereof (as obtained, for example, according to lines 1 - 21) above can be largely removed to form blocks, cakes or mats, which feel dry, of microbites of resp. . styrene polymer or polyolefin having, for example, as much as 8ü 5 solid particles or more, by means of a water removal method using a system, e.g. shown sohematically in Fig. 16., išo vaooseo-o mg According to this process for making bricks, cakes or mats, which feel dry, prepared by resn. microbubbles from the strongly aqueous slurry thereof starting from the atomizer, a first perforated support member (eg metal cloth) is arranged between the slurry of polymer microbits and a vacuum source to thereby apply reduced pressure to the aqueous slurry via the support member to an extent which at least is sufficient to deposit on the carrier element a soluble adhesive layer or web (with a practical thickness of about 3.2 mm) of microbubbles with intermediate reduced water content, which is low enough to allow the web to maintain its continuity on the carrier element, brings the free surface of the adhesive microbit web into contact with a second perforated element, thereby forming a sandwich construction of microbite web between the two perforated elements covering the free exposed side of each perforated element with a continuous layer É of water-absorbent sheet material with higher water absorption capacity ä n the microbite web, applying the resulting five-ply assembly to a pressure to allow the layers of water-absorbent sheet material to absorb their practically possible amount of water from the microbial mat via the perforated elements interposed therebetween, separating each layer of water-absorbent sheet material from its resp. adjacent perforated elements and separates each perforated element from its resp. surface of the mat of microbubbles with further reduced water content, after which this mat is finally discharged.

A feature of this method is that it can be performed continuously as each perforated element and water absorbent sheet learns continuously and an additional step is included, wherein each separate water absorbent material sheet is then fed (after the pressure application step) through a drying zone in order to remove absorbed water from these sheets to an extent that allows the sheets to be used again to absorb water from successive additional portions of microbit mat with intermediate reduced water content taken up from the exit end of the vacuum application step.

Thus, when each perforated element is continuous, the first of them is returned to the starting slurry under the influence of vacuum in order to pick up a continuous barrel of depositing mat of microbubbles. At the same time, the second continuous and perforated element returns to the outlet end of the vacuum zone in order to "complete" the sandwich formation of the continuously forming web, of microbubbles between the two opposite perforated elements. Thereafter, in turn, each of the two continuous water-absorbent sheets is continuously brought into contact with the free surface of its respective perforated elements.

The continuous pressure applied to the five-layer assembly increases the continuous absorption of water from the microbite mat into the continuously opposing water-absorbent sheets via the perforated elements of the continuous microbite web. This web is then discharged continuously after the removal of the water-absorbent sheets, followed by separation of the perforated elements, each water-absorbent sheet continuing through its resp. torkzon.

Referring to Fig. 16, the slurry of microbubbles in water is discharged from the atomizer into the tank 10, which receives the starting slurry. A vacuum cylinder 11 is mounted spaced upwardly from the bottom of the tank 10 and inwardly from its ends and is rotatably mounted on its horizontal shaft 12 coaxially with the vacuum cylinder 11 and supported on the outside of the tank 10 in bearings (not shown), which are rotors - only mounted on supports (not shown). A first continuous metal cloth filter 13 (eg HO mesh, perforated element) is supported on idle rollers 1 and 15 and moves in the direction marked by the arrow a downwards below and around the lower half of the vacuum cylinder 11 where the metal cloth 13 passing through the slurry picks up a deposited web of microbites with partially reduced water content.

A second sheet metal filter 17 (also the one with the dimension 100 mesh, perforated element) is supported over the rollers 18 and 19 and passes over the clamping roller 20 and below the guide rollers 21 and 22 in the direction marked by the arrow b, the web of microbubbles with intermediate water content to the filter 15 in a sandwhich-like manner arranged between it and the filter 17.

A continuous water-absorbent piece of felt 24 supported on rollers 25 and 26 moves in the direction indicated by the arrow c below the tension roller 27 and around the guide roller 28 and then continues to the guide roller 29. Thereby covering the extent of the filter lay, extending over the distance between the rollers 28 and 29, the exposed surface of the sheet metal filter 15.

A second water-absorbent felt piece 31 carried over the rollers 32 and 35 moves in the direction of the arrow d below the idle rollers BH and 35 and over the tension roller 56, the felt piece 31 being brought over the distance between the rollers 52 and 53 with the exposed underside of the felt piece 17. This completes the assembly comprising five layers of microbite web in a sandwich-like manner, arranged between the metal cloth filters 13 and 17 covered by the felt pieces 2H and 2H, respectively. 31. lO l5 '50 55 HO 7800560-0 lä Between the two pairs of resp. opposing idle rollers 28 and 32 and 29 and 31 pass this five-layer assembly between opposing pressure rollers 38 and 39, their length of 56 cm applying a total pressure of e.g. H08 kg (thus 7.3 kg / cm) via the pressure roller 33 against this unit. When the felt pieces 2U and 31 are separated at the joint by the rollers 29 and 33, the filters are separated later when the filter 17 passes down over the idle roller 19. Then the microbite web, reduced to a cake with 8H% solid particles, is removed from the filter 17 by the separating blade HO and falls into the receiver H1 for the cake of microbites. At the same time, the first or upper filter 13 passes upwards around the idle roller H2 and any cake of microbubbles, sizing to this filter, is removed therefrom with the upper separating blade H3 and falls into the receiver Ål for the microbite cake. If the previous water-reducing system is operated with a vacuum cylinder 11 with a diameter of 28 cm and a length of 56 cm at a speed of 10 rpm with an added material amount of 11, Ä liters / min slurry of styrene polymer microbubbles (containing 2% solids) from the atomizer, a wet 3.175 mm thick layer of microbits was obtained and with a previous pressure of 7.3 kg / cm at the pressure roller 38, a yield of 10.9 kg / h containing 8H% solids was obtained in in the form of styrene polymer microbubbles.

I sin resp. drying zone (not shown), each water-absorbent sheet can be dried with hot air (or other suitable means) and can be passed between pressure rollers when its water content is high enough for a substantial portion thereof to be extruded.

The foregoing systems and devices for removing water from microbubbles or other liquid inert to them are not limited to the use of expanded polystyrene microbubbles described above. The process and system are also similarly useful for microbubbles of any of the other expanded styrenic polymers as well as useful for microbubbles of any polyolefin. Nor is the system limited to the previously stated dimensions and embodiments shown in the illustrative drawing, but may be modified to provide such other practical production capacity, and the various components may be varied to meet particular requirements of the plant's production. and capacity as well as its space requirements. This system for withdrawing such a large amount of water from the microbits is not limited to the use of a rotating vacuum cylinder to form the web of high water microbubbles to be passed through the pressure rollers 38, 39, (Fig. 16). The slurry 10 BO HO vaooseo-0 receiving tank 10 and the vacuum cylinder 11 along with its shaft can be eliminated and the rollers 18, 20 and 21 moved approximately to the left of the previous position of the tank 10 with the filter 17 correspondingly extended.

Thereafter, the highly liquid slurry product is fed from the atomizer to a stuffing box (similar to the machine vessel from which the pulp is fed to the flat wire in papermaking) located above the filter 17 (slightly to the right of the roller 18) and discharged on this filter.

There, the free water is drained, which accompanies the microbubbles through the first portion of the filter 17 after passage over the roller 18. Before the filter 17 reaches the pressure rollers 38 and 39, it passes over a suction box (in much the same as at the outlet end of the flat wire) where part of the water held by the micro-pieces is discharged. The roller 15 is moved slightly to the right to be located just to the right of the extension upwards from the roller 18. The filter 13 is shortened and kept taut by running under the roller, replacing the cylinder 11 and located near the cloth filter 17 as it passes the suction box.

The layer of wet microbites on the filter 17 is sandwiched between the filters 15 and 17 as they continue after the roll 18 to and through the nip between the pressure rollers 59 and 39.

Water-absorbent sheets 2ü and 31 are advantageously made of cotton felt, but may consist of any suitable water-absorbent sheet material having a greater affinity for water than the apparent surface tension which holds the water to the microbubbles.

The atomizing machine is not limited to the particular details of the illustrative utility unit described on p. 5, line 2H to p. row 8. For example, the number of atomizing arms can be varied up to 32, depending on the production needs of the plant and the shape of the housing can be changed accordingly. Some change in specific parts of the atomizing arms is also possible. The properties which achieve the effective atomizing function should be maintained, while allowing some modification in other areas of the arms.

Nor are the disintegrating arms limited to, for example, particular length and number, but either of these may be varied in relation to the particular manufacturing plant and in some cases may be omitted.

The nature of the atomizing function and the appearance of the microbites (according to Figs. 1 - 5) show that the individual microbite particles do not show significant uniformity in the contour line.

The starting styrene polymers and polyolefins (from polyethylene to polymethylpentene), which are expanded small pieces converted into microbits according to the invention, are thermoplastic, which also shows that they can be extruded. vsuosso-o ¿16 The present microbites feel dry, even though they hold a considerable amount of water (eg as much as 80 5), which means that the microbites do not wet their fingers when you feel them and Wheller does not wet the palm when they are held in the hand. Although the invention has been explained by a detailed description of certain particular embodiments thereof, it is to be understood that various modifications and substitutions may be made within the scope of the appended claims, which are also intended to cover the equivalents of these embodiments. ., _._...,,

Claims (20)

7800560-0 l? - PATENTKRAV 1. Microbites as such, or in the form of a water-based suspension, of an expanded, thermoplastic, expanded form non-brittle polymer in the form of a styrene polymer, a polyolefin selected from polyethylene, polypropylene, polybutene and polymethylpen , or copolymers or mixtures of said styrene polymer or polyolefin, characterized in that they (a) are from about 40 to about 325 μm long and from about 20 to about 325 μm wide, (b) are substantially completely free from intact cells, (c) substantially lacks uniformity in the contour of the individual microbite particles, and (d) has a density that is from about 85 percent of to substantially the same as, the density of the corresponding unexpanded polymer. Microbites according to claim 1, characterized in that the thermoplastic polymer is a styrene polymer. Microbits according to claim 2, characterized in that the styrene polymer is polystyrene. 4. Microbites according to claim 3, characterized in that the expanded polystyrene is a waste of expanded polystyrene. 5. Microbites according to claim 1, characterized in that the thermoplastic polymer is a polyolefin. Microbites according to claim 5, characterized in that the polyolefin is a polyethylene. 7. Microbites according to claim 6, characterized in that the polyethylene is a molten alloy with about 10% by weight of polystyrene. Microbits according to claim 5, characterized in that the polyolefin is polypropylene. 9. Microbits according to claim 5, characterized in that the polyolefin is a copolymer of polypropylene having from about 20 to about 30% by weight of polyethylene. 10. Microbites according to claim 5, characterized in that the polyolefin is a melt alloy of polypropylene with a copolymer of polyethylene, of which up to about 30% by weight is polyvinyl acetate, and that the polypropylene exceeds at least 50% by weight of the melt alloy. 11. ll. Microbites according to any one of the preceding claims, in the form of said suspension, characterized in that the suspension contains from about 1 to about 2% by weight of microbites. J Microbites according to one of Claims 1 to 10, characterized in that they feel dry to the touch and contain from about 16 to about 100% by weight of solid particles in the form of microbubbles, the remainder being essentially only water. 13. A process for producing microbubbles according to any one of claims 1 to 12 from small pieces of the expanded thermoplastic polymer, characterized in that again expanded atomizing zone with inlet is fed into expanded small pieces of the expanded polymer and water. , repeatedly propelling the resulting mixture of said starting pieces into the water in a circular path by repeatedly striking them in the water with a plurality of striking surfaces separated from each other and rotating about the axis of the circular path at from about 4700 to about 8000 rpm ., that at the same time by means of the striking surfaces these expanded small pieces are driven to and towards corner-shaped edges of a separate plurality of substantially circular openings, which (i) have a diameter of from about 0.102 to about 3.175 mm to substantially 'rectangular openings with a width of from about 0.254 to about 3.75 mm and a length of from about 3.81 to about 12.7 mm and (ii) are arranged in a screening pattern in a curved square radially spaced outwardly out of reach of the striking surfaces to a degree which need only be sufficient to avoid collision between the openings and the striking surfaces, e.g. from about 0.508 mm to 1.016 mm, in order to repeatedly tear, break up and shear the small pieces of the expanded polymer into microbubbles, selecting the amount of water added in relation to the inserted polymer pieces so as to prevent the contents of the atomizing zone. from reaching a temperature which would have a detrimental effect on the original properties of the starting pieces, which enable the production of the micro - pieces. A method according to claim 13, characterized in that the surfaces of the small pieces of expanded thermoplastic polymer are wetted with water before being introduced into the atomizing zone. 15. A method according to claim 15, characterized in that the small pieces of expanded thermoplastic polymer in the atomizing zone are driven by the striking surfaces or alternatively (i) up to and around corner-shaped edges of at least one pre-breaking surface located between the feed inlet and the many openings and spaced around the circumference away from the openings and radially out of reach of the striking surfaces in a manner similar to the openings and (ii) to and towards these openings. A method according to claim 15, characterized in that a plurality of these disintegrating surfaces are provided, which are elongate and extend over approximately the width of the atomizing zone parallel to the axis of the circular web and separated from each other around the circumference around the axis. . Method according to any one of claims 13-16, characterized in that the microbubbles leave the atomizing zone in the form of a slurry of them in water containing at least about 1 percent of the microbubbles as solid particles, whereby the slurry is vacuum filtered to thereby increase the solids content to at least 16% by weight. Method according to one of Claims 13 to 16, characterized in that the microbubbles continuously leave the atomizing zone in the form of a slurry in the water, which slurry is then applied to a surface of a movable continuous first sheet of a non-water-absorbent perforated member to continuously provide on the first surface a removably adherent continuous web of partially dewatered microbubbles, applying suction to the second surface of the first perforated member, thereby removing a portion of the amount of water from the microbite web, covering the initially uncovered surface of the microbite web with one surface of a second movable continuous sheet of a non-water-absorbing perforated element in order to provide a movable sandwich-like structure of the microbic web between opposite and opposite facing surfaces of the two perforated elements, continuously covering the exposed surface of each of the the perforated elements by means of a continuous web of a water-absorbent sheet material with a stronger absorbent affinity for the water than the surface tension which holds the water at the microbits, and that the resulting assembly comprising five layers is successively passed through the nip between opposing rollers in a pressure roller pairs so provided that they provide sufficient pressure against the five-layer assembly to significantly increase the water absorption traction 7800560-0 QD shos the water-absorbent sheet material from the web of microbits, and when the successive portions of the five-layer roller assembly are left the microbits from the perforated sheet material, whereby a product of microbits is obtained, which, calculated on the weight, consists of from about 50 to about 90 percent solid microbite particles. A method according to claim 18, characterized in that the slurry of microbites in the water is continuously fed into a liquid limiting zone, wherein a rotatable vacuum drum is supported partially immersed in an accumulation of the slurry held in this zone, and that it is brought first non-water-absorbent perforated member to pass into this accumulation of slurry held in the restricting zone and around, below and in contact with the submerged portion of the rotating vacuum drum, thereby maintaining suction in the drum as it rotates in the accumulation of slurry , the first perforated element moving in contact with the drum, a continuous layer of water-containing microbubbles is constantly provided along this perforated element and, when said element leaves the accumulation of slurry and approaches the second perforated element, the layer of water-containing microbubbles sandwiched between the two perforated elements when they ssa both are brought close enough to each other for the other perforated element to meet and be in continuous contact with the layer of water-containing microbites. A method according to claim 18, characterized in that, after the microbubbles have been removed from the position between the perforated elements, the water-absorbent sheet material is treated in order to remove water therefrom before returning it again to contact with the exposed surface of the perforated element. its respective perforated elements, between which an additional number of microbubbles have been arranged in a sandwich-like manner, from which water is to be absorbed.