Note: Descriptions are shown in the official language in which they were submitted.
~L253326
Field of the Inveneion
The present invention is directed generally eO a process and apparatus for
making an oriented continuous strand mat. More partlcularly, the present in-
ventlon is directed to an oriented continuous ~trand mat of glass fibers. Most
~peclfically, the present lnventlon 18 dlrected to sn orlented contlnuous
glass flber strand mat havlng lncressed tensile strength ln one
dlrectlon. The orlented con~lnuous glass fiber strand mat 18 formed by
deploylng contlnuous filaments of glnss flbers onto the movlng surface of
a chaln conveyor or other slmilar movable support surface~. The
fllaments are deposited on the conveyor by a plurallty of feeders whlch
are structured to produce both generally clrcular filament arrays and
generally elosgated elliptical loop fllament arrays. The two arrsys are
arranged in any deslred pattern to produce a continuous glass fiber
strand mat whlch, when lncorporated ln 8 ther~oplastlc resln forms a
moldable sheet having superior hlgh tensile strength in a desired
direction. Elongated elllptical loop fllament arrays are formed uslng an
alr ~et nozzle and a plsnar, generally vertical, deflector plate
posltloned ln the dlrectlon of travel of the chaln conveyor.
Descrlption of the Prior Art
Contlnuou~ strand glass fibcr mat~ which src incorporated into
suitabla thermoplastic resins to form glass fiber reinforced
thermoplastlc resln sheet are generally known in the art, Exemplary of
patents directed to these mat~, sheets and processes and appsrAtus for
their manufncture are the followlng patents, all of which are asslgned to
~S,$
~L253~2~
the ass~gnee of the subJect applicaelon:
.S. Patents Inventor~3 Issuc Date
3,664,909 AcXley May 23, 1972
3,684,645 Temple et al Au~ust 15, 1972
3,713,962 AcXley January 30, 1973
3,850,723 Ac~ley November 26, 1974
3,883,333 Ackley Uay 13, 1975
3,915,681 Ackley October 28, 1975
4,158,557 Drummon~ June 17, 1979
4,208,000 Drummond June 1~, 1980
4,277,531 Plcone July 7, 1981
4,315,789 Tongel Febr~ary 16, 1982
4,335,176 Baumann June 15, 1982
4,340,406 Neubauer et al July 20, 1982
4,342,581 Neubauer et al Au~ust 3, I982
4,345,927 Picone Au~ust 24, 1982
4,404,717 Neubauer et al Septemba~ 20, 1983
Typ~cally for~lng continuou3 strand glass mats, a plurality of
strant feed~ng Q~semblles are placed above a moving belt or conveyor
which i8 preferably foraminous in nature. The strand feetsrs reciprocate
back and forth parallel to each other and in a dlrection which i8
generslly transverse to the dlrectlon of travel of the movlng belt or
conveyor. Strand~ of glass fiber filaments are fed to the strand feeder~
from suitable supply means, such a~ an array of formlng psckages ln a
support or creel, or from a plurallty of glass flber forming bushings.
Each feeder lncludes a belt puller os a wheel puller assembly that
provldes the pulling force to take the strand from the supply and dlrect
it down on~c a chaln conveyor or slmilar movlng support.
Inltlally, glas~ f1ber strands were placed o~ deposlted onto
the chain conveyor from the wheol puller or belt puller dlrectly. The
several strand feeders each produced 8 generally slnusoldal array of
strand material on the travellng belt. Thls was due to the relative
motlons of the reclprocating feeders mov~ng transversely across the
- 2 -
S ~3z6
endless moving conveyor. A typlcal mat forming assembly uses twelve
strand feeders 80 thae the mat product wa3 formed as an overlapplng array
of plural sinusoldal strand~. These mats having the ma~orlty of strands
running across the mat ~nstead of along the length of the mat produced a
glass flber reInforced thermoplastic resin sheet usable ln many stamping
and forming processes.
The sinusoidal configuratlon of glass flber strands sometlmes
resulted in a glass fiber reinforced thermoplastlc resin shQets having
non-controllable tenslle strength characterlstics 80 a deflector was
employet intermedlate the belt or wheel puller of the feeder assembly and
the chain conveyor. Such as deflector, in the form of a convex surfaced
disk or plste, 18 disclosed in U.S. Patent No. 4,345,927. Thls convex
deflector functions to provide a surface upon whlch the strands impinge,
are somewhat separated into filaments, and fall onto the chain conveyor
to form a mat having a reduced fllament orlentation. Flber glass
reinforced thermoplastlc resln sheet~ formed uslng mats having reduced
orientation glass fiber Rtrands are more isentropic than were previous
sheets havln~ glafis fiber~ formed in generally ~inusoldal loops.
Recently, a demand has arisen for a stnmpable fiber ~lass
reinforced thermoplastic sheet whlch wlll have increased tenslle strength
ln the longltudinal direction of the mat. Exemplary of such a usage is
ln vehicle bumper back-up beams. Increased tensile strength in the
longitudinal direction of the thermoplastic sheet can be accomplished by
increaslng the amount~ of glass fiber strands in the longitudinal
direct~on of the mat formed on the chain conveyor. A~ obvious way to
accompllsh this is to suspend a roll of strands above the chain conveyor
and to deploy them onto the mat in the direction of chain travel.
~253;~26
.
Unfortunately such a ~olutlon present~ problem3. First, serands must be
placed on a beam which usually requires drying. Commercially acceptable
mats are currently formed of wet strands from elther wet forming package3
or dlrectly from bushings whose filaments are sized for such an
application. The lndusery does not produce a wet roll beam in a suitable
size for such an application. Even more importantly, in a sheet which
will be ~tamped and molded, it i8 essential that the glas~ flber
reinforcement flows or moves wleh the thermoplastic re~in sheet during
stamplng to provide a strong finishet component. Continuous straight
serands do not bend or deform when they are used ln 8 mat which i8 then
stamped or molded and thus, non-uniform reinforcement can result. Stlll
further, if sn end is lost on a beamed strand, the mat uniformlty wlll be
lost unles~ the entlre length of mat i8 rethreaded where the end wa~
lost. As may be seen in ~everal of the above-recited prior patents, the
layered mat i8 transferred from a first chaln conveyor to a second
ad~acent conveyor for needllng. Thus, ln addltlon to provldlng the
requisite strength in one dlrecelon, the mat must also be capable of
transferring from the formlng conveyor to other conveyors or equlpment.
It wlll thus be seen that there 1~ a need for a process and
apparatus whlch will produce A layered glass flber mat usable to form a
stampable flber glass relnforced thermoplastlc resln sheet with increased
strength in one dlrection. Such a ~heet, can be produced from a
plurallty of the glass flber relnforclng fllaments which are deployed
coextensive with the length of the formed sheet. Sheees havlng fllamentR
80 deployed have increased tenslle strength in the longltudinal dlrecelon
and are particularly desirable for certain appllcatlon~ such as; for
example, automobile bu~per back-up beams. The orlented continuous qtrand
~L2s3;~26
mat produced in accordance with this disclosure provides such a product.
Here described is an oriented continuous strand mat.
Also described is an oriented, continuous loop strand mat.
Yet further described is an oriented, continuous strand, needled mat
incorporable with a thermoplastic resin to provide a stampable fiber ~lass
reinforced thermoplastic resin sheet havin~ hi~h tensile stren~th in one
direction.
The oriented, continuous strand, needled mat may have interleaved
layers of two types of oriented strands.
Still further described is an apparatus for making an oriented
continuous strand mat.
The oriented, continuous strand mat described is readily transferable
from one conveyor to another conveyor durin~ manufacture.
Even still further described is an oriented, needled, continuous
strand mat havin~ elongated elliptical strand loops having their long axis
oriented alon~ the lon~ axis of the mat conveyor.
~ ~5332~
As will be discussed in greater detail, the
oriented continuous strand mat is
comprlsed of interlesved layers of elongated elliptical 3trand loops and
generally circular or randomly arrayed loops of strands of glass fiber
filaments. A plurality of strand feeding assemblies are positloned
ad~acent each other above an elongated chain conveyor or other foramlnous
support. The several strand feeders each traverse back and forth across
the chain conveyor in a direction generally perpendicular to the
longltudlnal direction of travel of the conveyor. Each strand feeder
includes a strand pulllng means such as a wheel or belt puller and each
such strsnd feeder receives strands of glass fiber filaments from a
supply which may be a forming package, roving ball, or may be a bushing
assembly from which the filaments are attenusted.
The strands from the several feedlng means are deployed on the
travellng chain conveyor and build up ln an interleaved, layered
fashlon. Selected ones of the strand feeders carry elongated deflector
plates whose long dimen310n ls colinear wlth the length of the chaln
conveyor. The deflectlng surface of each such elongated deflector plate
18 generally plsnar and 18 posltioned generally perpendicular to the
chaln conveyor. An air flow amplifler nozzle 18 positloned between the
strand feeder and the deflector plate to dlrece strands passlng through
the nozzle agalnst the deflcctor plate, Thl~ nssemblnge form~ elongAted
elliptlcal loops of filaments as the strands strike the elongated
deflector plate. These elongated loops then fall onto the chaln conveyor
with their long axis oriented along the length of the conveyor.
Intermediate the spaced elongated loop forming strand feeders are
-- 6 --
~2~;3326
po~ltloned strand feeders whlch form loops having a smaller c~rcular
orlentatlon. T*.ese clrcular loops are lnterleaved with the elllptlcal
loops during mae formation and the composite loop orientatlon given to
the flnished mat gives the thermopla~tlc resin sheets into which these
orieneed continuous loop~ are incorporated higher tenslle strength in the
longltudlnal dlrectlon of the so-formed sheets.
A thermoplastlc resln sheet havlng an oriented, needled strand
mat ln accordance disclosure ls stampable or otherwlse
formable lnto numerous artlcles such as aueomotlve bumper back-up beams
whlch have a hlgh tensile strength ln the longltudlnal dlrection of the
sheet. Due to the contlnuous loop nature of the glass fibers forming the
mat, the stamped articles have a generally unlfor~ concentratlon of
relnforcing fllaments in ali pares of the formed article. This ls ln
contrase to a sheet for~ed from elongated dlscontlnuous fllaments whlch
do not readlly bend and flow wlth the thermoplastlc resin durlng
moldlng. Thus the sheets formed from mats made ln accordance with the
present lnvæntlon are commerclally useful.
The orlented contlnuous strand glass fiber mat
described is formed on the chain conveyor as an
lnterleaved array of elongated elllptlc&l loop strands and lnterspaced,
generally circular or randomly arrayed strands. Such a composite
orlentatlon of s~rand loops 18 readlly transferrable from the first
formlng conveyor to the secont atJacent needling conveyor wlthout
appreciable mat defor~ation. Such mct integrlty is a result of the
seversl different strand loop components shapes. Whlle the elongated
elliptlcal loop6 glve high tensile strength ln thelr long dlmenslon, a
mat made solely of such loops lacks the approprlate strength to allow
:L:253326
handling durlng transfer fro~ one conveyor to the next. The inclusion of
generally circular or randomly arrayed loops results in a mat that is
prope~ly needleable and which has the requisite amount of tenslle
st~ength ln all dlrectlons wh~le having hlgher tensile strength ln the
longltudlnal dlrection of the sheet ~nto whlch the ~at ls lncorporated.
The process of forming an oriented contlnuous strand mat has several
different loop orientatlons interleaved to form the composite mat and results
in a thermoplastic resln sheet having increased tenslle strength in the
longltudinal direction of the sheet when the mat described ~s lncorporated
therein. By using an air flow amplifyin~ nozzle in con~unctlon with an
elongated deflector plate which ~s pogitioned intermediate the strand feeder
and the chain conveyor, the elon~ated loops of filaments are formed and
deployed onto the chain conveyor in an expeditious manner. The process of mat
forming and the apparatus used therefor thus cooperate to for,m a mat usable to
produce a stampable thermoplastic resin sheet having commercially desirable
properties such as high tensile strength ln the longitudinal direction of the
sheet.
Hore particularly, in accordance with a first aspect of the invention
there is provided, a glass fiber mat of consolidated glass fiber strands
comprising one group of continuous strands in the form of circular loops, a
second group of strands in the form of elliptical loops with the long axis of
the eLliptical loops parallel to one side of the mat.
In accordance with a second aspect of the invention, there is
provided, a glass fiber mat comprising a needled mat of continuous glass fiber
strands of two distinct geometric configurations; one group of contlnuous
strands being in the form of generally circular loops and a second group of
strsnds being in the form of elliptical loops, and wherein the long axis of
the elliptical loops of strands all lie in a plane parallel to one side of
said mat.
In accordance with a third aspect of the invention, there is
provided, a thermoplastic fiber glass reinforced sheet comprising a
thermoplastic resin filled mat of glass fiber strands whlch have been needled
and wherein the mat is formed from loops of continuous glass strands which are
elliptical and loops of continuous glass strands which are circular, the
majority of the strands being elliptical and the long axis of the elliptical
loops being parallel to each other and one side of the sheet
Embodiments of the invention will now be described with reference to
the accompanying drawings wherein,
o
~L2~i33~6 -
Flg. 1 is a sche~atic perSpect~ve view of a contlnuous strand
~at for~ing asse~bly embodying the present invention;
Flg. 2 ls a schematic perspectlve view of a generallyknown
prior art s~rand feeder and deflector plate ~ssembly; and
Fig. 3 ls a schematlc perspectlve view of a strand feeder
having an air flow ampliflcation nozzle and a deflector plate ln
accordance with the present disclosure.
Description of the Preferred Embodlment
Referring lnitially to Fig. 1, there msy be seen generally at
10 a somewhat schematlc representation of an assembly for making a novel
oriented contlnuous strand mat.
Such mat forming assemblies areknown generally, as may be seen in U.S.
Patent Nos. 3,883,333 and 4,404,717, both of which are assigned to the
assigneF of the present appllcation. While a rigorous discussion of this
generally known mat forming assembly ls not believed necessary at this
~uncture, the followlng overview will facllltate unterstanding of the
present inventlon. A plurality of strand feeders, generally lndicated at
12, are posltlone,d above an endless conveyor 14 whlch 18 drlven by spaced
drive rollers 16. Endless conveyor 14 has a foraminous surfsce nnd is
typically a chaln conveyor. Each strnnd feeder 12 18 5upported for
movement above chain conveyor 14 with the movement of each strAnd feeder
12 being generally transverse to the direction of motion of chaln
conveyor 14, with chaln conveyor 14 moving from left to right in Fig. 1.
Chain conveyor 14 will thus be understood at moving in lts longitudinal
~.2S3326 `
d~recelon while the various serand feeders 12 move bsck and forth across
and above chaln conveyor 14. Each of the strand feeders 12 is supplied
with glass flber strands from a suitable supply source which may be a
forming package, roving ball or 2 fllament forming bushlng assembly.
~ f the supply is from a bushing, the process shown and
described in U.S. Patent No. 3,883,333 may be employed and is preferred
if the strands used by feeders 12 are made directly from a uolten glass
source. As shown ln chat patent, the fibers of gla6s are drawn from a
moleen glass source gathered lnto strands and the strands are then fed
directly to mat conveyor.
If the strands are supplled fro~ forming packages or roving,
ehe packages or roving are placed on creels and the strands or rovlngs
are pulled from the creeled packages. Whatever the supply source, the
strands are pulled therefrom by thè serand feeders 12 and are deployed
b~ck and forth across the wldth of the movlng entless chaln conveyor 14.
In Fig. I only four strand feeders are sche~stlcally shown. It will be
understood that in a typlcal ~anufscturing as~embly slxteen such strand
feeders are po6:Ltloned serlslly one after another above chain conveyor
14. Twelve of these strand feeders 12 are prlmary feeders and the four
remainlng feeders are back ups whlch automatically begln to operate upon
fallure of one of the orlglnal twelve.
The strands pulled by the sctlve strand feeder~ 12 are lald
down on the chaln conveyor ln an endless lnterleaved manner to form a
contlnuous strand mat, shown schematically at 18 in Fig. 1. The varlous
fllaments deposlted on chain conveyor by the various strand feeders 12
are, oriented in a specific pattern or manner to form a mat 18 having
particular properties. It will
-- 10 --
~2~3326
be understood that the several strand feeders 12 are controlled to form a
mat 18 havlng a generally constant width and a constant thlckness, whlch
thickness can be controlled by varylng either strand traverse speeds,
chaln speed, or both.
Once mat 18 has been formed on chaln conveyor 14 by the
lnterleavlng and lnterlayerlng of the plurallty of oriented contlnuous
strand loop~, as formed by the
strand feeders in a manner to be dlscussed more fully subsequenely, the
mat 18 is passed under suitable drylng means represented by an overhead
hot air dlscharge hood 20 and a cooperating air exhaust d~ct 22, The
for2ed ~at is then transferred from chaln conveyor 14 to 8 6econd
neetl~ng conveyor 24 where lt passes between generàlly known spaced
needling boards 26. Here a plurallty of barbed needles are used to
lntertwlne the filaments of the mat to thereby inpart the mechanlcal
strength of the mat 18. The needllng process 18 described ln asslgnee's
U.S. Patent No. 4,335,176.
Contlnuous strand gl8ss flber mats for~ed generally ln the
~anner set forth herelnabove have found great utllity as relnforcement
for thermoplastlc resin sheets to for~ stampable glass flber relnforced
thermoplastic resln sheets. The ~heets formed ln the past have been
dlrected to ones having isotropic propertles; l.e., propertles such as
tensile strength whlch are equal ln all dlrQctlons. HowevQr, new
lndustrlal uses, such as stamped automotlve bumper back-up beams have
speclfled a sheet havlng lncreused tensile strength ln the longltudinal
dlrection of the sheet. Thls means that the contlnuous strand mat used
to make such a sheet must have a hlgher concentratlon of strand~ or
fllaments ln the longltudlnal dlrectlon of the mat. As was dlscussed
-- 11 --
~,,253~26
earller such 8 strand concentration i5 not accomplishable merely by
interleavlng a plurallty of straight endless strands ln the mat slnce a
sheet forlDed of such ~ mat may not stamp and form properly. Appllcants
have found thst the strands may be fonDed in elongated loops havlng a
generally slliptical shape with the long axis of the elllpse belng
orlented ln the longltudlnal directlon of the endless rnae conveyor 14,
and ~at for~Ded therefrom wlll possess the deslred tlrectlonal strength
characteristics. In a preferred process, the elongated ellipsoldal loops
are in~erleaved with conventlonal circular loops to provlde sufficlent
~echanical strength and ~at integrity to properly transfer the mat from
the chain conveyor 14 to the needllng conveyor 24. When only elllp~lcal
loops are employed, lt ls found that on occasion the rnat tends to wrap
around roll 16. Th~s will cause the operatlon to be shut down for
clearlng of the roll prlor to restart. Consequently, ln accordance w-th
a preferred embodiment of the invention, it has been found that a suitable
mae l8, useable to produce stampable fiber glass relnforced thermoplastlc
resln sheets havlng lncreased tenslle strength ln the longltudlnal
direction of the sheets, may be formed as an orlented contlnuous strand
mat havlng lnterlesved or lnterlayered arrays of dlfferent shsped layers
of strands or fllaments. Partlcularly, ln accordance ~lth a preferred
embodlment of the present invention, there are provided both circular or
randomly arrayed layers of filaments nnd layers of clongated elliptical
continuous loops or ~trands. Whlle various layering patterns can be
utllized for particular requlrements, it has been dete~Dined ln
accordancc ~:iek a prcferred embodlment of the present inventlon that a
mat havlng circular or randomly arrayed loops of strands or fllaments as
the top and bottom layers and as every third layer thereinbetween, wlth
- 12 -
~æs33z6
the other two layers between the circular or random loop layers belng of
the elongated elliptlcal serand type, l~e., having a long axls arranged
ln the longltud1nal dlrectlon of the mat, will form a mat that is
mechanlcally strong and that has the properties of increased tensile
streng~h ln the longitudinal direction of the sheet a~d which will
transfer fro~ the for~lng conveyor to other moving surfaces wi~h ease.
Turning now to Figs. 2 and 3 there may be seen strand feeders
useable to form the circular loop and elliptical loop continuous strand
or fllame~t arrays. Clrcular strand feeder 30 is generally similar to
the assembly shown in U.S. Patent No. 4,345,927, assigned to the
assignee of the present application. Circular strand feeder 30
receives strands 32 from a suitable
source of supply and feeds the strands by way of an endless belt 34
between spaced driven pulling wheels 36, 38 and 40. The pulled strands
42 are then fed against a deflector plate 44 structured to produce a
plurality of filaments 46 which are deposited onto chain conveyor 14 as a
plurallty of generally small circula~ loops 48. While not specificslly
sho~n, it will be understood that circular strand feeder 30 is
contlnually traversed across above the surface of chain conveyor 14 so
that the continuous array of small clrcular or randomly orlentet loops of
filaments wlll be deployed across the chain conveyor 14 at n width
determined by the width of tho ~hcct to bc formcd.
Referrlng now more particularly to Fig. 3, there mny be seen an
elliptical strand feeder 50 embodying the present invention.
Strands or filaments 52 from a sultable supply package array or from
bushlng assemblles (not shown) are fed through a guide bushing 54 and
onto an endless pulling belt 56 of conventlonal deslgn. This belt 56 and
- 13 -
~L2'53326
the strands 52 are passed about pulling wheels 58, 60, 62, and 64 and the
pulled strand~ 66 are then fed lnto an air flow nozzle 68. A suitable
nozzle for such useage ls set forth ln U.S. Patent No. 4,046,492 which ls
assigned to Vortec Corporatlon of Cinclnnatl, Ohio. Air flow nozzle 68
is supplled wlth compressed alr from a sultsble supply source (not shown)
and acts to redlrect the dlrection of travel of the pulled strands or
f~laments 66. Alr flow nozzle 68 doe~ not increase the speed of travel
of strands 66 since thls speed has been established by the belt puller
56. However, alr nozzle 68, in addltion to redirecting the strands, does
also appear to have an aspirating effect on the strands and greatly
reduces flla~ent wrappage on pulling wheel 60, for exa~ple.
Pulled strands 66 pass through air flow nozzle 68 and are
dlrected against an elongated deflector plate, generally at 70, which is
carried by, and moves wlth elliptical strand puller 50 back and forth ln
a transverse manner above endless conveyor chain 14. Elongated deflector
plate 70 has a planar deflecting face 72 whose longitudinal elongated
dimens10n is generally parallel to the dIrection of chain conveyor 14's
travel. The plane of deflectory face 72 is generally perpendicular to
the ~urface of conveyor 14. Alr nozzle 68 is also carried by elliptical
strand feeder 50 and ls oriented so that the pulled strands 66 which pass
therethrough lmpinge against planar deflecting face 72 of the elongated
deflector plate 70 at a substantial angle. These strands hit plansr
deflecting face 72 and are di~tided into filamentary arrays which disperse
forwardly and rearwardly along planar deflecting face 72 to form
continuous elongated elliptical loops 74 that are then deposited onto the
surfsce of chain conveyor. As m~y be seen in Flg. 3, the longitudinal
length or axis of the elonga~ed elliptical loop~ 74 is orlented along the
- 14
~L~53~26
longitudlnal length or dlrection of travel of chaln conveyor 14. The
degree of elongatlon of the contlnuous loops 74 of filamenes 66 is
regulatable by controlling such varlables as the speed of traversal of
serand pulley 50 above conveyor 14, the speed at whlch the pulled strands
66 are dellvered to air flow nozzle 68, the alr flow through nozzle 68,
and the speed of travel of chaln conveyor 14. By proper adjustments of
these variables, a pattern of elongated elllptlcal loops of contlnuous
strands can be deployed on chaln conveyor 14 ln a desired psttern.
As was dlscussed prevlously, the several serially arranged
strand Eeeders are, arranged in
a fashion that, ln a preferred embodiment, places a layer of clrcular or
rando~ filaments from a clrcular feeder 30 on the top and bottom surfaces
of the ~at and as every third layer therelnbetween. The two ad~acent
layers between each thlrd clrcular layer of strands are layers of
ellIptlcal elongated lops formed by elliptlcal strand feeders 50. It
wlll of course be understood that varlous other layerlng or lnterleavlng
patterns are posslble by proper selectlon and posltlonlng of the circular
and elllptical strand feeders 30 and 50, respectlvely, Thus, as shown in
Flg. 1, the flrs~ Eeeder on the left slde of the drawlng and the next two
feeders are lylng down cIrcular strands and the fourth feeder, elliptical
strands.
The glass fiber mat l4 for~ed by the interlenving of the small
clrcular or random loops of fllament~ for~ed by clrcular strand feeders
30 and the elongated elliptical loops of filaments for~ed by elllptlcal
strand feeders 50, are lncorporated into thermoplastlc reslnous sheets to
form stampable fiber glass reinforced thermoplastlc resln sheets havlng
lncreased tenslle strength ln the longltudlnal dlrectlon of the sheet.
_ 15 _
~L2533Z6
,
The needled mats are then i~pregnated with a hot molten thermoplastlc
from an extruder and after thorough lmpregnation in a suitable press~ the
resin is cooled to form the finished fiber ~188s reinforced thermoplastic
resln sheet. One such process, which iY continuou3, i8 described in
asgi~nee's German Patent DE-PS 2948235, dated S June 1985,
Inven~or John A. Baumann. A batchin~ operation to also
produce such lamlnates ls described in sssignee'3 U.S. Paeent No.
3,713,962, where the laminates sre made from mat and thermoplastic
sheets, which are melted in the lamlnating press to provlde the resin
impregnating the mat and other sub~ected to coollng to produce the
finslhed sheets. The lmpregnation of mats prepared
as here described with resins generally involves a continuous
operation of feeding molten thermoplastic resin between two mats and
two thermoplastlc sheets, one over each mat into a lamlnatlng zone where
pressure is applled to the sandwlch of resin sheets, mat and molten
plaselc for a period of time sufficient eo allow the mae to be thoroughly
impre~nated. The ~at and resln are then cooled in a similar pressure
zone to solidlfy the resin and form the finished sheets. Thls is a
continuous process wlth material contlnuously leaving from the hot to the
cold end and ls shown clearly ln asslgnee's German Patent No. 2948235.
The sheets resultlng from these operatlons for~ stampable,
fiber g~ass relnforced thermoplastlc rQsln shcets hsvln~ lncreased
tensile strength ln the longltudlnal dlrection of the sheet. Thls ls due
to the increased filament concentratlon ln the longltudinsl dlrectlon
which is a tesult of the elllpticsl shape o the contlnuous loops formed
by the elongated deflector pla~e 70 of the elllptical strand feeders 50.
Further, slnce these reinforcements ate contlnuous loops instead of
discon~inuous strlps or thrcads, the stamped products are uniform in
- 16 -
~ 5332~
fiber conceneratlon due to the ablllty of the glass fiber reinforcements
to bend and move wlth the reslns. Thus a commerclally deeirable and
useable product is formed by the apparatus and ln accordance with the
method here described.
Typical thermoplastlc resins sulted for preparin~ these
products are homopolymers and copolymers of reslns such as: (1) vinyl
resins for~ed by the polymerlzatlon of the vlnyl halides or by the
copolymerizatlon of vlnyl halldes wlth unsaturated polymerlzable
compounds, e.g., vinyl esters; alpha, beta-unsaturated aclds; slpha,
beta-unsaeurated esters; alpha, beta-unsaturated ketones; alpha,
beta-unsaturated aldehydes and unsaturated hydrocarbons such a~
butadlenes and styrenes; (2) poly-alpha-olefins such as polyethylene,
polypropylene, polybutylene, polyisoprene and the llke lncludlng
copolymers of pcly-alpha-oleflns; (3) phenoxy resins; (4) polyamldes such
as polyhexamethylene adlpamlde; (5) polysulfones; (6) polycarbonates; (7)
polyacetyls; (8) polethylene oxlde; (9) polystyrene, including copolymers
of styrene with monomerlc compounds such as acrylonltrlle and butadlene;
(IO) acryllc reslns as exempllfled by the polymers of methyl acrylate,
acrylamlde, metholoacrylamlde, acrylonltrlle and copolymers of these
styrene, vlnyl pyrldines, etc.; (11) neoprene; (12) polyphenylene oxlde
reslns; (13) polymer6 such as polybutylene terephthalate and
polyethyleneterephthnlate; and (14) cellulose esters. Thls list ls not
meant to be llmltlng or exhsu~tlve but merely illustrates the wide range
of polymerlc materlals whlch may be employed lnpractislng the present invention.
It ls also contemplated that flllers may be employed in the
thermoplastlc resins where desired. These flllers can be any of a
varlety of conventlonal resln flllers known ln the art, talc, calclum
~ 25~
carbonate, clays, dlatomaceous earehs belng a few of those typlcally
used.
While preferred embodlmenes of an oriented
eontinuous strand mat of glass fiber filaments have
been set forth fully and completely herelnabove, it wlll be evldent to
one of ordlnary sklll ln the are that a number of changes in; for
example, the type of chain conveyor, the strand feeder eraversing means,
the type of strand puller such as a belt or wheel used, and the llke can
be ~ade wlthout departlng from the true splrlt and scope of the present
lnventlon which is to be llmlted only by the following clalms.
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