Note: Descriptions are shown in the official language in which they were submitted.
~9~
EXPAMDED STYRENE-POI.Y~ERS AND POLYOLEFIN
This invention is that of (a) micro bits of' an expanded
th~rmoplastic polymer which i~ non-brit~le in its expanded ~orm
and selected from a styrene~polymer, a polyethylene~ polypro-
pylene, a polybutene9 and a poly-methylpentene, and ~b~ a method
for preparing these micro-bi~s from bi~pieces of the respecti~e
styrene-polymer or polysle~in ~rom polyethylene to the poly
-methylpentene~
These micro-bits~ which briefly may be called expanded
styrene polymer or expanded polyolefin micro~bits, of the inven
tion Si) range in size from about 325 microna in length and also
from possibl~ about the same in width down to about ~0 microns
or less in lengt~ and to about 20 microns or less in widthp (ii)
have a speci~ic gravity of ~rom about 85 percent, to about the
same as that, of the s~arting polymer which was expanded and then
i .
15~ disintegrated:]nto the micro~bits; (iii) are substantially com~ i
pletely to entirely~compl~tely ~ree o~ intact cells of the expanded
polymer ~rom which ~hey were produced and (iv) their particles lack
uni~ormi-~y in outli~e.
Viewed ~a) a~ a magni~ioation of, for example, 161 times (by
; 20 transmitted light, ~in FXGo 1 below) they appear as clusters o~
randomly arrayed ~ibers,:and (b) under a sca~ning electron micro-
scope (abbreviated SEM) at magnifications o~ 360 and 380 times (in
FIGS. 4 and 13) th~y appear much like irregular separate pieGe
writing paper that were indi~idually compress~d coarsely in the
hand and then àllowed to rebo~nd to the exten~ pos~ible ~rom the
resilience a~ter releasing:-the pressure by opening the hand.
Further SEM examination at other:magni~ications as at (i) 1800
times Sin FIG. ~ below) of part o~ the same looation as in FIG. ~
s~ows~ormations of~what~appear to be extended apart and distorted
outlines o~ ruptured boundaries of what be~ore being ruptured was an
expanded honeycQmb array o~ h~xagonal;~d pentago~al cross ~ection~ o~
~2
cells, (ii) 4000 times (in FIG. 2) shows them to appear much like that
of ran~omly spread apart and partially overlapping not quite fully
open rose petals. Other SEM magni~ications ranging from 500 to 5~00
times show the micro-bits to resemble minute coral formations (as in
at least FIGSo 7 to 9), in wave-like appearanc2 (magnif.ied 1000 times
as in FIG~ 10~, and in somewhat ruffled ~luted formation (magni~ied
10~000 times, FIGS 11 and 14, and 20,000 times~ FIGS. 12 and 15).
The expression "styrene polymer" embraces not only polystyrene
itself but also thermoplastic polymers of any poly~erizable substituted
styrenes as well as eopolymers of styrene with one or more other com-
patible polymerizable substances as the nuclear-allcylate~ or -halo-
genated styrenes such as the ring~me-thyl or -chlorine-substituted
styrenesj or even alpha-methyl styrene, or with beta unsaturated
esters9 ethers, amides, or nitriles of acrylic acid and their alpha
: 15 -position-alkylated homoloGs, vinyl esters o~ a:liphatic and aromatic
carboxylic aci~s, N-vinyl compounds of N-vinylcarbazole 9 N~vinyl-
imidazole or N-vlnylpyrrolidone.
Such thermoplastic copol~ners of styrene usually should contain
at least about 50~,~ o~ ~xtyrene by weigh-tt or lt may be the predomina~ing
component or at least equal in predominance to any other hi~her
present co~ponent of any terpolymers.. The copolymers of styrene
include also any of the various impact polystyrene containin~ a major
~art o~ styrene and a minor part o~ a styrene-buta~iene rubber (usual-
ly d~sienated SBR, sometimes called Buna-S), ~or example, as produced
;~ 25 by emulsion po].y~eriza-tion of ~bout 75 parts o~ butadiene and about
25 parts o~ .styrene. Thu5 ~ styrene polymers also include styrene
alloys (i.e. pressure or melt ~nixtures~ o~ polystyrene with other
compatiblQ poly~ers generally of ethylenlcally unsaturated monomer~,
The te ~ 'ipolyethylene 1l in the expression l'an expanded poly~
ethylene" or ~!a polye~yl~ne" int~nds ~th~ h m~lecul~r weight.
~ J
~2A-
3'~
(at least 60~0) product an~ is generic as embracing low ~.ensity
no1yethylenP (speci~ic gravity below 0.92), the hi~h density procluct
(sp. g. over 0.94, ~enerally 0.941 to ~.965)~ and the meflium density
polymer J?ro-luct (a b~en~ of both the hiGh an~ low), as ~e].l as the
impr~natabl~ polyethyl~ne (e.g~ an extrude~ melt mix of polyethylene
wi.th 10~ poly.~tyrene and which can be calJ.ed "polyethyle~e-poly
styrene al].oy"); all of which are ava.ilable in f1ak~ or in oube.s
simi.lar to ~olystyrene pPllet.
The term "bit pieces" inc.ludes any of -the ~iscretc free-:rlo~in~
~orms n~ ~a11y 0~ th~ ~t,yrenc-~?olymers an~ o~ ~ny o~ the polyole~s
~rom polyetllylcne to th~ T?oly-rnethy].penteno, such as thP various siz~;
o~ crallule.s mad~ l~y cut1;.ing the respective e:~trucled ~ol.ymer into
small. lcn~th,s u.~ually called pe1lets or cry.s-tal (as ~i-th 7.t styrene
-j?olymPr) or pellets or cubes of a pol.yethylene-polystyrenc al.loy,
.15 the ~ariou~s si.zes of styrere-polymer beads obtainecl ~rom suspension
po~?..ymerizati.on or otherwi.se as by mo].di.nG the J?arti~cs ob-tained b~
.i.sinte~ral;i.n~ ,3ny o~ -~hese dif~rent pc?lymer forms, a11d the so-calle~
"grin~" incl.udin~ the coars~ly groun~ molde~ polymer or waste or oth~r
scrap .sueh po].~fm~r (o:~ ~arious ~:i.ze3, e.g. ~ ]./8 inch thic~nes.~ 4
il~ch ~lidth, and 3/8~inch len~th~, and ~ny other small size~ shapes
of an~y o~ l;hem.
.pandable styrene-polymer bi-t-pieces can be pr~parcd by
s~i~a~le lcno~l1 m~thods 9 for examl~le, prep~rin~ expandable st~rene
-pcllynner bit-pieces as disclosed in U. S. paten~ No. 2,~33,692
issued ~ay 9~ l9~ ,xpanclable polyethylene styrene a1loy can b~
~repared similarly.
r~xpancled ~tyrenc polymer bj.t~piec~s can be prepare~ from
evpandabl~ polystyrene by s~titable lcnown mcthods. 3ne ~c-thod for
~reparin~ expallded .s~yrene polymer bit pieces is by he~-ting them,
~or:examp3.~p wi.th ai~r or steam as disclos~d in U.S. pa~en* 2~9~3,69Z
~ '7~
(column 4 lines 65-69), "to a temperature above the so~tenin~ point
o~ the styrene pol~ner" as disclosed in U. S. patent No. 3,001,954
(column 3 lines 20-23). See also U. S/ patent No. 3~259r594 tcolumn
2 lines 24-27). Expanded polyethyl~ne-polys-tyrene ~lloy bit-pieces
can be prepared s.imilarly.
Expanded bit-pieces of the polyethylene, polypropylene9 pQiy
butene or poly methylpentene can be produced by preparing the respec-
tiYe expande~ polyolefin by suitable known methods inoluding incor~
porating into the specific polyolefin (before extruding it~ a
chemical ~oamin~ agent (so-called pneumato~en, usually a complex
nitro~en-containing organic compoun~ that decomposes at the ex-trusion
t~mperature, liberatin~ nitrogen) with extrusion temperature adjusted
so that the pneumatogen decomposes as the polyolefin leaves the out-
let of the e~trusion die, as briefly described in Plas~ics Extrusion
Technology, by Allan L. Gri~, Reinhold Publishin~ Corp., New Yor~,
N.~. (1968) pace 2219 and reducing the expanded polyole~ins into
~: blt-pieces by cutting or otherwise.
Certain physical ~ea-tures o~ the micro-bits o~ the invention are
sho~ by the ~hotomicrographs of tlle dry micro-bits in the ~irst
~iPteen f`i~lres o~ the accompanyin~ drawinGs, of which F~GS. 1 to 9,
14 and 15 are o~ polystyre~e ~icro-bi-ts and FIGS. 10 to 13 are of
low density pol~leth~lene micro~bits, and wherein
FIG. 1 is a pho~omicrograp~ at a ma~nificatio~ of 161 times, by
transmitted ll~ht~;
FIG. 2 is a SEM~photomicrograph of the micro-bits at magnifica~
tion o~ 4~000 times;
FIG, 3 is a SEM microphotograph at magnification of 1800 times
o~ about the area that gave ~he lower le~t qua~ter see~ in FIG, 4;
FlG. 4 is a S~M microphotograph take~ at magnification o~ 360
times;
4;~
3'~ ~
~IG. 5 is a microphoto~raph taken at ~ magnification of l~O
tirnes;
I~IG. 6 i~s a S~ mlcrophotocraph taken a-t magnification of 5~0
times of the area -that ~ave the del.inea-tcd center portion of FIG, 5;
FIG. 7 is a SFJM photomicro~raph a-t l,n~O times magnification
of the arca tl~at gave the de].ineated portion of FIG. 6;
FIG. ~ is a S~M photomicrograph at magnification of Z,OOO tim~s
of the area 1;hat gave the prominent ri~ht portion of FIG~ 7;
FIG. 9 is a SEM photomi~ro~raph takcn a-t magni~ication of 5,000
ln time.s and shows the area th~t a~peared in the lower right hand quarter
of FIG. ~;
~IG. l~ ;.s a SE~ ~hotomicro~raph taken a~ ma~nification of ln~O
time~ of ~olye-thyIene micro~b.its and ~parcntly o~ the loca-tion that
ave tl1e area in -ti1e Iot1er left hand ~uarter of the up~er ri~ht hand
quartcr of ~IG. 13;
: FIG7 1.l i..s a ,~F.,M pho-tom.icro~ra~h takcn a-t magni~.ication of
lO,O~O times and ~mbracing t.he area of the slide fieen in about the
center ~f ~.IG. 10;
~ FIG, 12 i~ a ~S~M ~hotor,1ioroGraph taken a~t maGni:fication o~
2n 2~ 0 timos and coverin~ ~.he area of th~ ~lide seen .in lo~l~r magni-
fica~ion in about ~h~ mid~le o~ FIGo ll;
FI~. .L3 is a S~M~ho-tomicroc~raph ~aken at magni~ication o~ 380
times o~ tl1e same pol~ethylene micro~bit.~ involved in FIG~. lO to 12;
~ ;'.IG. 14 i~s a SEM ~ho-torn.i.~rogrira~h l;aken at ma~n.ification of
Z5 lO,O~O t~r;les o~ l~olys~yl~n~ micro-hits; c~n~l
FIC, 15 is a S~ photomicro~raph at ma~nifica~ion o* 20,~0
time~ o~ a portion o~ the polystyrene micro-bits sli~e view~d in
FIG~ 140
::
'
~5-
3~7
FIG. 16 is a schematic illustration of a s~stem for remo~ing
the trapped water from the mi.cro-bits of the invention as obtained
in the aqueous slurry leaving the comminutor wherein the micro-bits
are produced from the expanded startin~ polymer (a~ more fully de
scribed shortly after Example 2 below).
The expanded micro-bits of the invention are prepared by con-
tinuously feeding expanc7~d bit-pieces of a styrene-polymer cr any of
the aforesaid polyol.efin~ and wa-ter into a con~ined comminuting zon~
ha~in~ a feed inlet to it, repeatedly impelling the resulting mixtur~
of the startinG bit-pieces in -the ~ater t,hrou~h a circular path by
repeated impact on them in -the t~a-ter by a plnrality o~ impact sur-
faces spaced a~art from one another and rotated around the axis of
said circular path at from about 4700 to about 8000 revolutions per
minute, an~ a t the same time by said impact surfaces ~riving said
expanded bit-pieces~to~and a~ainst corner-shaped edges of a dispersed
- plurality of ~rom substantially circular orifices (a) having a dia-
me~er of from aboub 0.102 to about 3.17~ millimeters (i.e. mm.) to
substantially rectangular orifices ~rom about 0.254 to about 3.175
mm. in width by from about 3.81 to about 12.7 mm. in length, ànd ( b )
20 ~ being arranged in screenin~ array in an arcua-te plane spaced radially
out o~ range of s~id impact surfaces to an extent that need be cnly
sufficient to avoid collision between said orifices and said impact
surfaces, as ~rom about 0.508 to 1.016 mm., and thereby repeatedly
tearing, ripping aild shearin~ micro-bits of the respective expanded
2~ polymer from said bit-pleces thereof; said fed in water being so
propor~lQned to said fed~in~expanded polymer bit~pieces to prevent
~the content o~ the~co ~ lnuting zone ~rom reaching a tempera~ure that
would adversely effect~ e ~ntegri~y o~ said starting bi~-pieces
and~or the desired~ mloro-bitsO ~ `
~ ~ ~ f
~6
:
'7
The pre~aration o~ these micro-bits of a styrene-polymer or o~
a polyolefin (~rom a polyethylene to a poly-methylpentene), and so
also t,he method o~ the invention, can be conducted by disintegrating
: ~he respective starting expanded st~rene-polymer or polyolefin bit
-pieces in a comminuting machine (such as that produced by FitzpatriGk
Company, of 832 Industrial Drive, Eimhurst, Illinoi~ 60126, U.S.A.)9
acGording to their Bulletin No. 152 copyright 1968~ using the broach-
ed ~ixed blades (identified therein by "Code DS 225") to replace the
blades or other comminuting elements, moun-ted for rotation in the
co~inuting chamber model ~AS06~ both shown on that bulletin's page
5~ m at chamber is liquid-ti~htly capped7 for example, by a cover
such as shown in theîr Code M44D6 or Code MA44D6 (upper hal~ of
page 3 o~ their Bulletin 152).
That model DAsO6 comminuting chamber is rectan~ular in hori-
zontal cross-section and has a pair o~ opposed parallel entirely
vertical walls integrally Joined at each o~ their opposite ends by
~ a aeparate one or a pair o~ opposed vertically arcuate walls each
::~ with its con~ex ~ace e~ osed to the exterior.
Sixteen identicalg slat-shaped comminuting arms are separately
removably but fixedly carried with their snugly ad~acent to one
another bases encircled about~ ~nd keyed to, the operating sha~t and
intermediate its ~ree outer mounting ends. m ese arms extend radial-
ly out from t~e s~a~t (e.g. 127 mm. ~rom its axis to the outer end
of each arm) w.ith the first of each consecutive four o~ them extend-
ing horizontal1y toward one arcuate wall, the~second of each ~ourexteDding vertioally9 the thind four of them extending toward ~he
: other arouate wall~ and the ~ourth ~our of them extending ~ert~cally
downwa~d.
Earh arm is rec~angular in c~o~s~sec~ion in a plane ~unning
30 throu~h the entlre length o~ the s~aft's a~cl5 and o~ ~ha~ arm, and
::
'7~
of each arm 180 removed from it~ The outer end of eaoh arm meets at
right angles with its two wider sides (25.4 mm. width) and its narrow
or impact side ~9.525 mm. wide) ~acing the direc~ion of rotation.
That narrow side also meets at right angles with the t~o wider side~
which are paralle~ to one another for most o~ their width and with
the trailing third of their surfaoes t.apering to one another a~d ter-
minating in a knife ed~e o~ their trailing end~
Each free exposed end of the sha~t extends through its respective
stu~fing box in its neighboring one of the two parallel vertioal walls
on throuLrh a bearing carried on a respcctive trunnion a~.~ixed to the
m~chine's ~oundation and spaced outwardly away from the respective wall.
A drlving pulley is mounted on each end o~ the shaft extending out-
wardly ~rom its respective mounting -trunnion.
The bottom o~ the comminuting chamber is an exchangeable dish
-~ha~ed, arcuate screen curved convexly downward with an inside radius
rom t~he axls of the operatlng shaft~ equal to the length of a com-
mlnuti:n~ arm plus~0~762~mm~. clearance) The screen's overall rec-
,
tangular peripheral opening has such dimensions and shape to enable it
: to be removably fitted in a liquid-tight engagement with the ~ottom of
the four ~alls o~ ~he comminutingr chamber~
m e screen ha~ sta~gered rows of, for example, circular holes
varylng~ln fl.iameter as~rom;0.102 to about 3.175 mm. and closely
spaced to one another with surficient space between them ~or the screen
to~hold up under workln~r conditions.
: 25~ Except ~or its starting material feed hopper inlet a-t one side
of:;it;~ the rest o~ the chamber's cover is arcuate :and convex upwardly
with~a radlus (from~the~axls of ~the operatir~ shaft) sufficien~ for the
rotatlng a3ms to have a~ 0.;762 mm. clearance from ~the lnwardly faclng
~ ;sur~aoes o~ a plurali~y (eOg- three~ pre-brea~er bars (about 20,32 cmO
30 ~ lon~ and 6.3~ mm~ wide) :protrudlne for 3.175 mm. along their entire
:
-8-
~ 3'~ ~
length into the interior of the oomminuting Ghamber~ and extending
spaced apart ~rom one another and parallel to the axis o~ the Dpera-
ting shaft.
The selected driving pulley on the operating shaft is connected
by driving belts extending from a mQtor shaft drive pulley ~nd can be
op~rated at speeds embracing the range o~ from about 4700 to about
8000 r.p.m., and more effectively from about 5000 to about 7500 r.p.m~
The micro-bits of the invention are variously applicable, for
example, in filtering and impro~ing ~luids~ both liquid and gaseous,
lQ That is done, for example~ by admixing the selected styrene-polymer
or polyolefin micro bits into the liquid to be impro~ed and there-
after filtering them out, or by ~iltering the liquid to be impro~ed
through a bed of the micro-bits. m e polymer micro-bits thereby re~
move invisible dissol~ed or invisibly suspended organic material ~rom
the liquid and ord:inarily leave it free ~rom development thereof even
after long standing.
:~ To illustrate~:tap water in Matawan9 New Jersey, U~SoA~ was
filtered through a ~hatman No~ 2 filter paper to the extent of 473.2
cubic centimeters ~i e. cc.) into a first clean, 946.3 cc. Mason jar
which then W~6 tightl~ sealed. 0.4 g~ams of the micro-bits (prepared
from expanded polystyrene bit-pieces) were wetted with about 20 cc.
of this same tap water and admixed with about 473.2 cc. of the tap
water and then ~iltered through another l~hatman No. Z filter ~aper
into a similar second clean, 946O33 Mason jar and tightly sealed~
A week later a slight yellow ha~e wa~ noted in the first jar,
but the water (which had been admixed with the ~icro-bits) in the
: :
second jar still was per~ectly clear. The yellow haze in the fir~t
ar;increased:in amount and in density with later settling to the
bottom~ o~ -the~ Jar~during observati~on over a period of three months~
: 30 - Yet the water that had been :~iltered through the poly~yrene micro
bits into the~second ~ar wa8 still per~ectly clear.
~: : :
.
37 ~ ~
Illustrating use in ~iltering and improving a gaseous fluid,
~hese polymer micro bits also can be used as the packing in air
filters by being admixed with sui~able paper-making fibers and
made up into sheets for loading into air ~ilter frames.
Comparable liquid and gas filtering result~ are pro~ided by
micro~bits of a polyethylene. Micro~bi~s oX the other polyole~in~
are similarly use~ul.
Some batches o~ these polymer micro-bits o~ the invention
produr.ed, ~or example, b~ the abo~e-descri~ed comminuting machi~e
10 using a screen having circular openings of sorne sizes, are obtained
with content of varying amounts from ~ery little or at times up
to about 20% or so of fibrous particles s-till finer in size than
: that in the ran~es desoribed earlier above, for example, down to
15 microns or to 10 microns or so in ~idt~. Generally the pres
. ~15 ence of any such amounts of these smaller sizes may not introduc~
: ~ any disadvantage in the particular use that is to be made o~ the
micro-bits. : ~
`: :However, i~ need be, these finer si~es can be removed by
being filtered out by available screening or other suitable means~
for example, a high capacity centrifugal si~ter produced by the
Kason Corporation, oP Newar~9 New Jersey, U.S.A. This invol~es
:~ ~ uni~ormly ~eeding the~micro bits by a feed screw di~charging into
a h~elical paddle ro~ating in a horizontally positioned cylindrical
si~ting chamber wherein centri~ugal__orce accelerates movem~nt o~
Z5~ ~he micra-bi~ pa~ticles against the siev~ whi~ a~taohed to i~
::: :::: : ;:
~:
~la-
.
,~
su~porting basket in a ma~ner ~hat allows the sleeve ~o ~ibra~e
~reely.
~n conducting the method o~ ~he inventio~, the operating
conditions may cause an increase in -~emperature of the charge v~
expanded styrene~polymer or polyolefin bit~ieces being di~in~
tegrated in the comminu~ing zone, Tha~ may be mors mar~ed with
some styrene-polymers than wit~ others, so that ln ~ome o~ them
the temperature rise may reach a level suoh tha~ at it and higher
t~e styrene-polymer bit-pieces would not readily or satis~actorily
tear or shear un~er ~he particular operating conditions and poss~
~ly have a tendency to stretch or o~herwise modi~y the reac~ion
o~ the material being tre~ted, and so ad~brsely e~ect the
desired tearing or shearing o~ the starting bit-pieces or ~J~at
already has been to~n or shorn ~rom th~m. m at is to be a~oided,
as by feeding more water with ~he bit~pieces~
The finished comminuted polymer micro-bi~s leavin~ the
comminutor mani~es~ the p~operty o~' holding onto water to the
exken~ o~ :~rom possibly about 40 to 50 times their dr~y weight,
a~d wi~ch i ts so held water ~orming a non-:~luid plastic mass which
is de~or~able and ¢arl roll, but w~thout becoming ~luid . me water
is not released ~rom this mass by dralning or o~inary ~iltra~ion,
~ut requires pressure or æuction, but yet it retains a signi~i-;ant
amount o~ wa~er. For example, sQme high pre~sure reduces the mass
to a wa~er content OI on~y about 50 percen~.
~5 The propo~ion o~ water fed in~o t~e comminu~ing c~am~er then
should ~e at least enough ~o~ the mix~ure o~ wat~r ~d produced polymer
micro-bi~s ~o be ~u~lc~en~ly :~u~d ~eadily to now ~hrou~ t~a~ orif~e8
(
~9 3'7~ ~
of the screen bo-ttom of the comminutor. Con~eniently9 th~ water should
be lrom about 55 to a~out lOO times ~he weight of the produced expanded
: styrene-polymer micro-bits.
It is beneficial also to admix the starting expanded styrene
~pol~ner or polyolefin bit pieces with an amount of water su~ficient
substan-tially completely to wet their exposed surfaces before ~eeding
them into the comminuting chamber~
It is advanta~eous also to the conduct of the method of the inven-
tion that the bit-pieces in the comminutin~ zone are driven by the im~
pact surfaces alternately (i) to and against cornered ed~es of at least
one pre breakin~ or impact surface (of at least one pre-breaker bar dc-
scribed above, page 8 line Z7 to page 9 line 2) spaced circumferential-
ly away from said ori~ices and radially similarly out of range o~ said
impact sur~aces as are said orifices, and then (ii) to and against said
orif1ces.
It is also advantageous that ~he impact arms be axially and angu-
larly spaced away from one another. -
~ : For som~ u.se.s to:~be made of these styrene-polymer or polyolefin.
; m.icro-bits, they can be used with the water which is held by them or
'O any lower amount that is retained after either or both o~ application
o~ pressure or vacuum to remoYe AS much as it is desirable to remove
of that which thus can be removed.
To~remove the rest o~ the water when dry micro-bits are desired,
one way is to freeze the product having the wa~er co:itent left after
its partial removal by pres,sure and/or vacuum. Then the frozen micro
-bi~ts are left, or heated,~o thaw out and attain a temperature just
abo~e ~reezin~ or up tG ambient, at which the still retained water
then ~reely dra1ns o~ hen all that can drain o~ has lefty ~he
:residual water c~n be ~xpres~e~ a~/or withdr~n ~y ~acuum ~ollowed
:30 by ~inal dryin~
:'
~ 3 ~ ~ ~
Another anc~ more prac-tical way to remove the water held by the
micro~bi-ts di.schar~ed by the comminutor is described further below
in relation to the system .illustratec] in FIG, 16 o~ the drat~1in~s.
The inven-tion is illustrated by, but not restricted to, -the
followin~ examples:
a ~ - ~ :
~5 li-ters o~ e~pan~in~a~ent .impre~nated, extruded polystyrene pellets
(crystal) expanded to f'rom about 6.35 to abou-t 12.7 mm. substantially
round pellet;s havin~ a bullc density ol 12 ~rams per liter ~!ere com-
rninuted in a comminutin~ machine (as des~ribe~. on pa~e 7 line 4 topa~e ~ line 6) ecluipped ~ith an input, feeder 1~.16 cm. in diameter by
7,G2 cm. long and a bottom arcuate screen with holes o~ O..lO16 mm.
niameter.
Th~ ro-tor is set to run at 6,~ r.p.m. an~ the J.'eecler set to
].5 char~ the expanded polystyrene bj.t-pieces a-t the rate o~ ~5.4 li-ters
~ever~ 5 n,inutes (i.e. ~25 liters per hour). The startin~ expanded
:polys~tyrene bit-pieces to~ be lntroduce~ in~to the fec~er ~ere wetted
~: ~ with sufI1c1ent water qub~stant,ially completel~ to cover their outer
surface.s. The thus wettP~ expandecl pol~styr.ene bit-pieces were char~ecl
ZO irlto t~le ~e~r con-tinuously at a r~te o~ 35.4 li.ters cvery 5 minutrs,
~hil~ at the s~m~ time water was injected i.nto the co~minutin~ ch~mber
throu~h ~lle two 1.6 mm.~diameter Jet orlfices at a rate o:~ 7.57 liters
~er inj.nute.
The m.ixture of l;he c~n~e~ poj~.ly~tyrelle micro~ s .le~vinG the
~5 screen bottom of the comminut:ing chamber was collected in open ~ru~s
wi.th ~otto1n drain ~lugs:, wherein the free w~ter sett].e~ to -the bottom
~an~ ~he ~o.l~styrene~mlcro bi~s ~Jith the boun~ ter held by th~rn in
the ~ro]~ortion of 2 parts of mlcro-bits to 9~ ~arts o~ ~later, due to
~the entrapped air~ rose on top o~ the ~ree waterO The ~ree water
was drain~d o~ leavin~ ~hind a plastic mass o~ t~e (disintegrated~
13-
. '
3~7~
expanded polystyrene micro-bits in the water physically bound to them,
The plastic mass wei~he~ 255.15 kilos and contained 5~1 kilos of miGro
-bi~s with 25~.05 kilo.~ of water boun~ by them.
27.24 I~.ilos o~ the plastic mass ~hen placed i~ a close weave
double cotton bag wer~ subjected to pressure until 22.71 liters of
water were expr~sse~. The remaining 4,08 ~ilos containing 544 grams
OI expanded polystyrene micro-bit;s then were dried in an open dish in
an oven maintained at 110F.
In this connection1 ~or example, micro-bits produced as in
1~ Example 1 from expande~ polystyrene bit-pieces prepared from v.ir~in
~sometimes call~d "prime" 3 poly,s-tyrene havin~ a density of 1.1, showed
a density o~ 1~0. That is 90.9 percent of the density o~ the original
starting polystyrene crystals, from which there was prepared the ex-
pande~ polystyrene bit-pieces usçd as the starting material from which
; 15 the ultimate polystyrene micro-bits were prepared. The density o~
; the dry micro-bits o~f the invention thus is substantially the same as
that of the sty~ene-poIymer from.which there was prepared the expanded (~
styrene-polymer that wa.s used as the starting material used in pre-
paring the aforesaid micro-bits.
~.e 2 - ~ = ~ ^ One inc~
O
pieces o~ impregnated polystyrene scrap having a bulk density of 16
: : grams per liter we~e treate~ by the same steps as in Example 1 but
~ed at the rate of Z8.32 liters in 6 minutes and with the rotor at
6500 rcp.m.; and in the .same way yielded a plastic mass like that
25: obtained in Example 1 except ~or its havin~ a lighter grayish pink
hue than that o~ the bulk o~ t~e starting impregnated scrap.
Replacipg the starting:expanded polystyrene bit-pie¢es of each
o~ Examples 1 and 2 by som~ other ~antlty o~ any other d.e~si~y o~
: .
: :
~: :
.
~14
3~
bit-pieces ol virgin or scrap expanded polystyrene, or of any
expanded styrene-acrylonitrile copolymer or o~ any other ex~
panded styrene-polymer or any above described herein applicable
polyolefin; and separately respectively repeating the steps o~
either o~ those examples with the same or somewhat different
proportions of water or different rotor rate9 ~rovides the
corresponding relatively similar micro-bits o~ any o~her e~panded
styrene polymer cr of any e~panded above described herei~ applic~
able polyolefin, ~he respective corresponding additional ex~mples
are to be oonsidered as i~ presented herein in completely writte~
out form, to avoid making this specification prolix~
By replacing the screen bottom of the comminutor described
above (page ~ lines 4 to 24) by a screen o~ the same o~erall
dimensions but instead having a herring-bone array o~ rectangular
ori~ices 12.7 mm, lo~g by Q.254 mm. wide, and using the thus
: changed comminutor in repeating Example 1 and Example 2, the
: selected startîng mat~rial expanded styrene polymer bit-pieces
or expanded polyoleîin bit-pieces similarly yields the same type
o:~ respective end product micro-bits being to the extent oî sub~
stantially co~pletely or entirely completely 1005S 0:~ ~rom about
5 to 15 micro~s wide and o~ many Yarying lengths up ~o about ~25
microns ar~d from substantially comple~ely to com~letely free o~
intact cells.
me at least 9~ percen~ OI water in the ~luid mix*ure or
Z5 ~ ~lurry of s~yrene- polymer or polyolefln micro bi'cs in wat~r
.
leavi.ng the commin~tor, as ~rom the operation o:f either Example 1
or 2 or any modification o~ them (such as provided by the second
and third just preceding paragraphs), can be removed considerably
to provide dry-to-the touch chunks, cakes or mats of the respec-
tive styrene-polymer or po~yolefin micro~blts having, for ex-
ample/ as much as 84 percen-t solids or more, by a water-elim~na~
tion method USiPg a system such as is schematically shown in ~IG.
16.
Thls method o~ produc~ng~such dry-to the-touch chunks,
0 cakes or mats o~ -these respective polymer micro-bits ~rom the
highly aqueou$ slurry o* them leaving the comminutor involves
in-terposing a first ~oraminou$ carrier mernber (e.g. wire gauze~
between said polymer mi.cro~bits s-urry and a source of vacuum an~
th~reby to apply reduced pressure -to said aqueous slurry through
said carrier member to an ex-tent at least sufflcient -to deposit
- on said carrier member a removably adhering layer or web (of
practical thicknessS say, about 3.2 rnm.~ of said micro-bits with
an intermediate reduced wa-ter content (for example, sol.ids con
ten-t o~ at least 16% by weight) low enough to enable -the web
to retain its continuity on said carrier member, con-tacting
-the free sur~ace o~ the adher:ing m:lcro~bits web with a second
foramlnous member thereby forming a sandwich of the micro~bits
web between both said foraminou~ membersg covering the ~ree e~
~ posed ~ide o~ each ~oramino~ member with a continuous layer o~
wa-ter~absorbent shee-t material h;aving a greater water absorp-ticn
capacity than that o~ said micro-bit,s web; then subjecting the
re~ulting five layer assembly to pressure to enable the layers
o~ water-absorbent sheet material to absorb its practical capable
extent of wa-ter ~rom~-the micro~bits mat through the interposed
: : :
B
foraminous member3, and thereafter separa~ting ~ach layer o~ ter
-absorbent sheet material from its respectively contiguous forami~ous
member and separatin~ each foraminous member from its respective sur~
face ol the further reduced in water content micro-bits mat, and
dischargirl~ said lat-ter mat,
A feature of this m~thod is ~hat it can be operated continously
in tll~t ~ach foraminous member and water-absorbent sheet is continuous
and there i.5 included a further step of then passing each separate
water-absorbent mat~ri~l sheet (after the pr~ssure-applyinG st~p)
throu~,h a dryill¢ zon~ to rid these she~ts o~ absor~ed water ~o an
e~tellt to en~le using -them ~ain to ab.sorb water ~rom succes~ive
fur~ther ~ortions of intermediate la-t;er content r~duced micro-bits
m~t picked up from the exit ~nd o~ the vacuurn application step.
Thus, ~Yith each foraminous member bein~ continuous the first
15 one of ~h~m is re turned to the starting slurry there again under the
~ influence of the vacuum to continue to pick up a continuous run o~
; depositi.n~ Micro-bits ma-t. At thc same time, the second continuous
foraminolls member returns to the discharge end o~ the vacuum zone
to com~lete thc s~nd~ichin~ o~ the continuously forming micro-bits
~leb be-twee~l the t~o oppose~3 continuous :Coraminous membersO Then
in turn each of the t~lo cont~nuous water-absorbent sheets continuous-
ly contac-ts tho free sur~ace o:f i ts respec-tive ~orarllino-ls member.
'i'he continuous ~ressure applied to the moving five-layer
avs~m~ cl~hances the cont~nuous absorp-tiorl of water from tlle Inicro
-bits ~:eb into the continuously o~pos~d water~a~sorbin~ sh~ets
through t,he for~minous members from -the continuous micro-bits w~b.
This web: thcn contlnuously is d.i,schar~ed a~-ter the withdrawal of the
water-absorbent sheets followed by the separation of th~ foraminous
; mcmbers, wi~h each water absorbent ~he~t continuin~ on through its
3~ re~pcctive drying ~one.
~17
Referring now to FIC~ 16 the slurry of micro-bits in water
is discharged from the comminutor into the starting slurry-receiving
tank 10. Spaced upwardly from the bottom of tank 10 and i~wardly
from its ends, vacuum drum 11 is mounted rotatably on its horizontal
shaft 12 coaxial with vacuum d~lm 11, and supported outside of tan~
10 on bushings ~not shown) rotatably mounted on supports (ngt s~own).
A first continuous wire gauze Iilter screen 13 (e.g~ 40 mesh, for-
aminou~ member~ supported on idler rollers 14 and 15 travels in the
direction shown by arro~J a downwardly under and around the lower
half of vacuum drum 11 where the wire gauze 13 passing through the
slurry picks up a web deposit of partially water content reduced
micro-bits.
A second wire gauze ~ilter screen 17 (also 40 mesh, foramino~s
member) supported over rollers 1~ and 19 pas.ses over tensioning
roller 20 and under guide rollers 21 and 22 in the dire~tion show~
. by arrow b, thereby the intermediate water content micro-bits web
adhering to filter~screen 13 is sandwic~ed between i~ and filter
screen 17.
~ A sontinuous water-absorbing felt sheet 24 supported on rolle~s
25 and 26 travels in the direction shown by arrow c under te~sioning
roller 27 and around guide roller 28 and ~here continuing to guide
; roller 29.~ m ereby~he:stre~ch of screen 13 extending over the
: : distance between rollers 28 and 29 covers the exposed ~urface of
wire gauze screen 13.
~ A second water-absorbent felt sheet 31 suppor~ed over rollers
: 32~:and 33 travels~in the direction shown by arrow d under idler
: rollers 34 and 35~and over tensioning roller 36, whereby felt sheet
31 for the distance:bétween rollers 32 and 33 contacts ~he exposed
under~ide of filter screen i~. T~at the~ completes the ~i~e layered
;30 ~ assembly o~ micro-bits web s~dwiched betweQn the ~ir~ gauze filter
`
~8~
. .
~ ~ 3~7~ ~
screens 13 and 17 covered by the felt sheets 24 and 31 respectively.
Intermediate the two pairs of respectively opposed idler
rollers 28 amd 32 an~ Z9 and 319 this five-layered assembly passes
between opposed pressure roll~rs 38 a~d ~9, ~hereby their 56 cm.
length applies a total pressure o~, for example, ~08 kilos (thus
7,3 kilos per centimeter, i.e. cm.) by pressure roller 38 again~t
that assembly.
After ~elt sheets 24 and ~1 separate at the junctions of rollers
29 and 33, the filter screens later separate as screen 17 passes down
o~er idler roller 19. Then the micro-bits web reduced to a cake o~
84 percent solids is removed from screen 17 by separator blade ~0
and drops into micro-bits cake receiver 41. At the same time the
~irst or upper ~ilter screen 13 passes upwardly around idler roller
42 and any micro-bits cake adhering to that screen is removed from
it by upper separator blade 4~ and drops i~to micro bits cake
recei~er 41.
~perating the fore~oing water content reducing system with a
:. 28 cm. in diameter and 56 cm. in length vacuum drum 11 at a sp~ed f!
of 10 revolutions per minute (r.pOm.) with a feed o~ 11.4 liters
per minute of styrene-polymer.micro~bits slurry ~containing 2 per~
cent o~ solids~ ~rom ~he corrlminutor provided a 30175 mm. thick wet
mlsro-bits layer, and with the foregoing 7.~ ~ilos per cm. pres.sura
by pressure roller 38 ga~e a yield o~ 10.9 kilos per hour containing
~4 percent o~ solids ~ styrene~polymer micro-bits~
; 25 In its respecti~e drying zone (not shown) each water absorbent: ~ sheet can be hot air ~or suitably otherwise) dried and with prelim-
inary passage between pressure rolls when its water content is high
enough that a signi~icant part o~ it can be expressed.
The foregoing .system and apparatus for remo~al ~rom micro;bits
of wa~er or other llquid inert ~o them i~ not limited ~o its aust
above described specîfic use on expanded poly~tyrene micro-bits. m e
: method and system also are applicakle similarly to micro-bits o~ any
of the other expanded styrene~polymers as well as to tho~e o~ any
~19~
~3~
polyole.fin micro-bi'cs. So also, the system is not r~stricted to
the earlier above indicated dimensions or layout shown in the
illustrative drawing~ but can be modi~ied to provide such other
production capacity as is practical and ~ariation in layout o~
the respective pa~ts to meet particular requirements of plant pro-
: duction capacity and plant space accommodations.
mis system for withdrawing such large content of water ~rom
the micro-bits is not limited to using a rotating vacuum drum to
provide the web o~ high water conten~ micro-bits to be passed
through pressure rolls 38, 39 ( FIGo 16~ ~ Slurr~-receiving tank 10
and vacuum drum 11 and its shaft can be eliminated and rollers 18,
Z0 and 21 moved to about the le~t o~ the ~ormer location of tank
10 with filter screen 17 correspondingly extended.
Then the highly liquid slurry product from the commi~utor is
~ed to a feed box (similar to the head-box from which paper pulp
~ is ~ed to the fourdrinier in paper making); located above ~ilter: ~ screen 17 (slightly to tbe right o~ roller 18) and discharging
onto that screen~ There ~he free water accompanying the micro-bi~
drains through the early portion of screen 17 after passing o~er
roller 18. Before screen 17 reaches pressure rolls 38 and 39 it
passes o~er a suction box (much li~e that at the fou~drinier di~-
~; : charge end) where part o~ thewRter held by the micro bits is with
drawn.
Roller 15 i~ moved somewhat to the right so as to be located
: 2~ just to the righ~ of the e~tension upward ~rom roller 18. Screen
13~is shortened and maintained taut by running under a roller re-
placing drum ll and posi~ioned ad~jaoent to wire screen 17 as it
travels past ~he suctlon box. m e layer o~ wet micro~bits started
on screen 17 ls sandwiohed between screens 13 and 17 as they con~
~0 tinue a~ter roller l8 to and through ~he nip be~ween pressure rolls
:~ 3~ and 39.
.
~ -2~-
~ 3 ~
Water-a~sorben-t sheets 24 and 31 bene~icially are of cotton
~elt but can be o~ any other suitable water;absorbent sheet
material having a grea-ter ai~inity f~r wa~er than the apparent
surface tensio~ holding the water to the micro-bits~
The comrninu~ing machine is not limited to the speci~ic
details of the i~lustrative appl~.cable unit described at page 7
line 4 to page 9 line 6. For example~ the mAmber o~ comminutirlg
arms can be varied even up to 32 in relation to the specific
plant production needs and the conXiguration of the housing can
be mod.i~ied accordingly. Some variation in certain parts o~ the
cornminuting arms also are possible. mose o~ its ~eatures which
pro~ide the effective commlnuting function should be retained
while allowing some varia~ion in o~her areas o~ these arm~. Also,
the pre-breaker bars are not limited, for example, ~o the speoi-
15~ ~ic length or number, ~or either oan be ~aried with respect to
:
the speci~ic~p~oduction plan and in some cases they might be
omltted. ~ ~ ¦
e nature o~ the comminuting operatian and the appearance
o~ the micro bits (as in FIGS. 1 to 5) show that the indi~idual
micro-~it particles have no signi~icant uniformity in outline.
at the starting styrene-polymers and polyole~ins (~rom
a polyethylene to a poly-methylpentene), the expanded bit pieces
o~ which are conve~ked into -the micro-bits of the invention, are
thermoplastic shows tha^t they also are ex-trudable.
: 25 That:the mîcro-blts~herein, even though holding a consider
able amount of~wa-ter~e~g. as much a~ about 80 percent); are said
to :be dry-to-the-touch means that the micro~bits when touchQd do
not wet the flngers or th~e palm o~ the hand wl~aen held in :it.
:~ ~ While the inven-tior~ has been e~ ined by d~tail~d descrip-
~30 tlon o~ ce~aln speci~ic embodlments of it~ it is understood that
various modificat:ions~ and su~stitutions may be made in them within
~he scope o~ the ~?Rended clalms whic~ are in~ended ~l~o ~o coYer
~qui~ale~ts o~ t;hefie embodiments.
~:
~1~
