Note: Descriptions are shown in the official language in which they were submitted.
~.~~3~ 1~
~ RD-15,981)
This invention relate~ to thermoplastic
composite laminates with ductile interleaves~ More
particularly, it concerns laminate~ in whioh the the
complimentary thermoplastic refiins and interleaf
copolymer resins are co~patibilized to produce an
integral, layered composite~
9~L3~
The production of light weight, shaped
objects, such as auto body parts, which have high i~p~ct
strength, that can be laid up or molded into co~ple~
shape~, and that will retain dimensional stability oYer
a wide variety of use conditions has been an enduring
goal o~ plastics researchers and manufacturers for
several decades. Recently, great advances towards this
goal have been made using reinforced plastics or
composites, in which two or more layers of re~inou~
shesting, sometimes using fibrou~ reinforce~ent, are
laminated together to form a lamina~ed co~posite wherein
the physical propertie~ of the resulting laminate exceed
what would bç e~pected considering the properties o~ the
individual layers~
Some of the most encouraging re~ults have been
achieved with laminates employing reinforced résin
layers in conjunction with an unreinforced layer of a
di~ferent re3in~ In the area o~ high performance
co~posites, i.e., as for aircraft pan~l , U.S. Patent
4,539,253, to Hirschbuehler, et al, disclose an interleafed
fiber re~in matrix co~position wherein a rein~orced
ther~o~et epoxy resin sheet i~ layered with a
fiber-rein~orced interleaf resin including a thermose~
epoxy and a rubbery vinyl addition polymer.
U.S. Patent 2,719,100 to ~anigan discloses a
pEocess fo~ hea~-sealing thermoplastic laminates, that
i8, bonding to~ether (by heat) the co~ponent layers of
-2- ~D-15,981~
thermoplastic films, e.g., poly(ethylene terephthal~te),
PET, by interposing a substantially amorphou~ ther~o-
plastic film between adjacent layers o ten~ilized,
i.e., stretched, film to be heat-se~led. T~e heat-sealing
p~ocess results in a strong, light-weight bonded film
useful for packaging. ~owever~ because the process
requires tensilization to make the l~minated film, it is
diffieult to produce such films having a thickness
substantially greater than 0~007W in a continuous type
of stretching apparatus. Thus, thickne~s is a limiti~g
factor.
Kennedy, in U.S. Patent 3,357,874, describes a
process for laminating polyester films and other
"addends~ onto the surface of a shaped polyester article
by treating the surface with an acid wash (e.g., 85~
sulfuric acid3, to leave the surface in an amorphous
conditionO When the amorphous surface of the film is
brought into contact with an addend material, a la~ina~e
is formed having a strong interface adhesion between the
component layers. However, the use of an acid treatme~t
i-~ costly and makes the substrates difficult to ha~dle.
U.S. Patents 3,798,116 and 3,969,176, to
Bassett, et al, de~cribe a method for preparing bonded
polyester film~ having a bead ~ype heat seal between the
plies o~ the composite film.
U.S. Patent 4,041,206, to Tsunashima, et al,
teaches that PET or poly~butylene terephthalate), P~T,
films can be laminated directly to a cry~talline
poly~butylene terephthalate) or poly(hexylene
terephthalate) copolyester blended with 10-~0 weight
percen~ PET or P~T, said copolyester containing 50-~0
mole percent terephthalic acid units. The resulting
films are transparent, tough, slippery and have
excellent heat-adhe~ive properties, making ~hem useful
in general packaging, pbotographic films and electriCal
~3~
_3 (RD-15,9Bl)
insulation. However 9 no mention is made of the
sui~ability of this system for reinforced, dimen~ionally
stable objects.
U.S. Patent 4~314,002 to oizumi, et al~
di closes circui~ board laminates co~p~ising alterna~ing
fiber-reinforced curable ther~oset re3in layer. and
unreinforced cured resin layers in which the same or a
di~ferent re~in may be used in ~oth types of layer~O
The reinforced layers, e.g., linter paper or kraft p~per
impregnated with a thermoset resin, are separated by
cured resin layers, forming an integral la~inate in
which voids between layers due to c~ntraction during
curing are eliminated.
U.S. 4,373,002 to Peterson-~oj di~closes a
heat-sealable laminated material co~prising a layer o
stretched crys~alline polye~ter and a layer of
cyclohexane-modified, heat-3ealable amorphous polyester
~aterial, which layers are joined by lamination or
coextrusion and then subjected to a joint stretching
operation. Th0 resulting la~inate is heat-sealable and
also exhibits high tensile strength.
The foregoing pate~ts de~onstrate that
considerable work has been done in the area of re~in
la~inates, both reinforced and unreinforced, which
obtain ad~antageous propertie~ by promoting, in various
ways, clo~e bonding between the re~pective layers, to
give an integral composite. There is ~till a strong
need, however, for reinforced co~posite~ utilizing
thermopla~tic resins to produce articles h~ving high
impact strength.
It ha~ now been surprisingly discovered that
unique, interleafed fiber-reinforced ther~oplastic
composites can be fo~med using layers of a fiber-
rei~forced ther~oplastic re~in separated by layers
of a duc~ile thermoplas~ic in~erleaf copoly~er resin~
3~
_4~ ~RD-lS,981)
The composites of the present invention are distinguished
from foregoing composite~ in that the interleaf block
copolymer resin is compatible with the fibee-reinforced
thermoplastic resin ss as to undergo a co-crystalliza~ion
or co vitrifica~ion, resulting in chemical interlayer
bonding which has not been seen in prior art laminates~
Such co-cry tallization is achieved without any of the
surface treatment techniques (acid treatment,
tensilization, precuring, etc.) seen in prior processes.
The intelleaf copolymer resin form-R a ductile~
tough, rubbery layer, and, in th2 final co~posite o~ the
invention, will form a diffuse interface with the fiber-
reinforced, or "~inder~, resin. The final thermoplastic
composites have high impact strength and high resistan.e
to delamination.
While not intending to be bound by any theory
of operation, it is believed that the following factors
may be i~portant in providing the advantageous r~ults
obtained with the present inventiono
(i) Adhesion between the reinforced substrate
and the interlayer occurs because the binder resin in
the substrate and the hard blocks (hereinafter (a)) in
the block copolymer of the interlayer mix with a
negative Gibbs free energy. This may be a consequence
of a co-crystalli2ability or of some o~her thermodynamic
driving force, such as negative mixing enthalpy or
positive entropic energy.
(ii) The soft block3 (hereina~ter (b)) in the
block copolymer of t~e interlayer al~ay~ have low Tg, in
fact alwa~s les~ than 25~C and typically les-~ than
-~0C. This does not guarantee that they will be
incompatible with the binder resin in the composite
substrate, thus demixing during cool down. They mus~ be
chosen on rigorous thermodynamic considerations to
insure demixing.
3~
_5- ` (RD-15,9Bl)
C~
The drawing illustra~es in perspective v1e~ a
detail o~ an interlea~ed, fiber-reinforced thermoplastic
composite of this inven~ion, showing the different layers included therein.
6Y~` ~9~
Provided in acccordance with the pres@nt
invention are laminated fiber-reinforced thermopla~tic
GOmpOS i te5 comprising:
~1) at least one fiber-reinforced layer
comprising reinorcing filaments coated with at least
one thermoplastic binder resin, and on at least one
surface of said fiber-reinforced layer~
(2) a~ le st one interleaf layer comprising a
block copolymer resin comprising polymer segments of
(a) a least one thermoplastic resin
co-crystallizable or co;vitrifiable with
said binder resin, and
(b) a~ leas~ one co-resin having a gla~s
transition temperature (~g) substantially
lower than said co-crystallizable
thermsplastic resin.
Al~o contemplatad herein is a proce~s for producin~
laminated fiber-rein~orced thermoplastic composite~
comprising:
(1) forming a fiber-reinforced thermoplastic
resin substrate co~prising fibrou~ reinforcement coated
~ith at least one thermoplastic binder resin,
(2) introducin~ on at least one sur~ace of
said sub~trate an interleaf layer comprising a block
copolymer resin compri~ing polymer segments of
(a) at least one thermoplastic r~sin
co-crystallizable or co-vitriflable with
said binder resin, and
3 t~;
~6~ l 5 , 9 ~ ~ )
(b) at least one polymer h~ving a Tg
substantiallly lower than s~ld
co-crystallizable resin, and
~3~ consolidating said fiber-reinfor~ed substrate
and said interleaf layer unde~ su~ficient heat and
pressure to ef~eot co-crystallization or co-vitrification
of said thermoplastic coocrystallizable re~i~ at the
interface between said substrate and said interleae
layer, suoh that an integral composite is obtained.
ETAILED DESCRIPTION OF T~E INV~TION
The novel ther~oplastic composites of this
invention use complemen~ary pairs of thermoplastic
resins, which can be engineered to make integral, toughg
fiber-reinforced, thermoplastic laminates with ductile
interleaf layers. It is known that layers o~ a duotile
resin included between fiber-rein~orced plies of a
composite can augmen~ th~ survivability of such
composi~es during tran~verse impact loading or other
deformation modes associated with interply delamination.
~owever, the exact nature of the re~in, the thickne~s of
the interleaf layer, and the quality of the bonding at
the interface between the interleaf layer and other
layers oP the la~inate are critical to the successful
perfor~ance of the finished co~posite. In the pre3ent
invention, for the first time, co~tinuous interlayer
co-crystallization or co-vitrification leads to a type
of diffuse bond between the reinforced layers and the
interleaves, giving the finished composites of the
present invention exceptional resistance to transverse
impact loading and resistance to shear and chemical
delamination.
The thermopla~tic resins in the ductile
interleaves and the binder resins of the reinforced
layers ~ust be ~co~plementary,~ i.e., the binder re~in
and at least one segment of the interleaf copolymer must
~2~ 6
-7~ (~D-15,9~1)
be diffusible in one another in the molten state, and
upon crystallization or vitrification of the binder
resin and the co--dif~usibl~ interleaf copolymer segment,
they form a diffuse, continuous interlayer bond. The
interleaf copolymer mus~ also include non~di~fusible
segmen~s, which will prevent the total dissolution o~
the interleaf resin into the binder layer, thus
maintaining the interleaf as a separateO ~uctile layer
even with substantial intermixing (co-dif~usion) of the
binder resin and other co-polymer segments. It i~ not
critical that either the binder resin or the co-di~fusible
components of the interleaf copolymer be crystallizable
resinc, as long as the two polymers exhibit a high
degree of chemical compatibility, resulting in a
diffuse, continuous interlayerO The term ~co-crystalli~a-
tion~, when referring to ~he interaction and bonding
between the binder resin and the co-diffusible ~egments
of the interleaf copoly~er, i~ expre~sly intended to
cover not only cases where both components are co-
crystallizable, bu~ also cases where they are co-
vitrifiable due to other ther~odynamic consideration~.
The binder resin and interleaf copolymer may
be selected from a wide variety of known resins that
would be complementary a~ described above, or may be
~5 specifically syntheqized with laminated composites of
the present in~ention in mind. Among such resins, given
illustratively, are aromatic polyesters, polyamides and
polyurethanes. The polyesters preferred for use herein
include poly(l,4-bu~ylene terephthalate) and poly(ethylene
tereph~halate) with minor amoun~s of polyes~ers derived
from an aliphatic or cycloaliphatic diol, or mixture~
thereof, containing from 3 to about 10 carbon atom~ and
at least one aromatic dicarboxylic acid. Preferred
polyesters are derived from an aliphatic diol and an
aroma~ic dicarboxylic acid have repeating units of the
following general formula:
~3~
-B- (RD-15,g81)
O =~ C--
~ CE12 ) n ~ ~ C--/~
wherein n is an integer~ preferably 2 or 4, e.g.,
poly(l,4-butylene terephthalate~.
Also contemplated herein are the above
polyester with additional amoun~s of polyol~ and~or
acids in the amounts of from 0.5 to 50 weight percent
based on the total resin compo3ition~ The acids can be
aliphatic or cycloaliphatic with the number of carbon
atoms covering the sa~e range. Polyalkylene ether
glycols can also be used where the alkylene portion ha~
from 2 to 10 carbon atom~ and the entire ylycol ~ortion
varies in molecular weight from 100 to 10,000. All such
polye~ters can be made following the teachings of, for
example, U.S. Patents 2,465,319 7 3~047,539 and 4,556,688.
lS When employed a~ the binder re~in for a
composite to be used in the temperature range of from
about 40 to about +150C, PBT exhibits a combination of
modulus and toughne~s which ~ake it particularly
preferred.
In for~ing the composites of this invention,
the binder re~in, which may be crystalline or
semi-crystalline or amorphous, i~ juxtaposed with a
suitable fibrous reinforc~ment, eOg.~ a fabric, roving,
yarn, tow, mat or tape o~ unidirectionally aligned
continuous rein~orcing ~ilaments. The reinforcement can
comprise a wide variety o~ materials including but not
limi~ed ~o carbon, glass, graphite, cellulose,
polyaramid, silicon carbide, boron, polyester, rayon,
polybenzimidazole, polybenæothiazole and m~al-coated
polybenzothiazole.
For sheet-like la~inates according to th2
inven~ion, the reinforcing material will pre~erably be
~29~
-9 (RD~15,981)
woven into a f abric or a Elat, non-woven mat. Pre~erred
as a rein~orcing fabric of high strength rein~orcing
filaments is ~AGNAMI~E~ A370 (~ercule , Inc.~, a
balanced 8-harness satin weave of ~000-count tows n
~ercules MAGNAMITE~ ~S4, high strength ca~bon fibers.
Tha fibrous reinforcement is juxtaposed with
the binder resin by any of a number of w011 known
method~, su~h as coating9 dipping, spraying, co-extrusion,
wetting, etc~ Fo~ the purposes herei~, the term
~coatingU will encompass all known methods by which the
reinforcement and binder resin are permanently
juxtaposed, this in~ludes embodiments wherein the
~ibrous reinforcement is surface coated, as well as
instance wherein the ~ibrous rein~orcement, in whatever
form, is thorougly coated and impregnated with the
binder resin. In cases wh~re the binder resin is in the
form of a sheet or film, it is preferred to layer the
fibrous reinfo~cement with the binder resin ~il~ and
join the resin and reinforcement components under
pre~sure, with heat if desired, e.g., 50-300C.
In preparing the interl~af film copoly~er, the
thermoplastic resin segment can comprise a number o
polymers, including by way o~ example, aromatic
polyesters, polya~ides and polyurethanes. Almost any
kind of thermoplastic re~in i~ suitable for incorporation
into the interleaf copolymer t provided it is comple~e~ary
with the binder re3in, that is to say, they are mutually
co-diffu~ible in the amorphous state and are
co-cry~tallizable or co-vitrifiable as defined above.
The second polymer seg~ent of the interleaf
copoly~er c n also compr$se a ~umber of compounds.
Typically, thi~ polymer will have a glass transition
temperature, Tg, substantially lower than the interleaf
copolymer segment which is codiffusible with the binder
resin. This ~elastomeric~ copoly~er segment, the ~so~t~
-10- (RD~15,981)
segment is selected to be phase separable ~rom the
"hard~ blocks preven~ing total dissolution o~ the
interleaf into ~he binder resln at lamination
temperatures, ensuring ~he pre~ence of a distinct
S interleaf layer. Preferred as interleaf copolymer~ are
poly~etherimide es~ers), such as General Electric
Company's LOMOD J resin and copolymers of PBT and
polytetrahydrofuran (PT~F), such as DuPont'~ ~YTR~L
thermoplastic elastomer. Segment length and overall
degree of polymeri~ation of the interleaf copolymer
may be varied by known techni~ues t in order to obtain
particular desired properties.
In a preferred embodiment, PBT of the formula
(~ ~f~ OC~2C~2C~2C~2o)p
is employed as the binder resin coating a fabric or mat
of reinforcing filaments, and an interlea~ copoly~er
film comprising segmented PBT and PT~F is employed
h~ving the formula
O ~` O
( (C ~ cocEl~c~2cEl2c~2o)X(CE~2CE~2C~2C~2)y)c~
where p, q, x and y are variables adjusted to obtain an
appropriate balance between modulus, ductility and
toughne~s. Because the PBT segments of the copolymer
can co-crystall~ze with the PB~ binder resin and due to
interlayer-diffu~ion of PBT components in th~ binder
resin and the copolymer, the in~erface between ~hem is
broadened by diffusion at lamination temperatures above
the melting poin~ of P~T, and a continuous inter~ayer
adhesion is promoted. At the same time, the PT~F
segments in the copolymer prevent the to~al dissolu~ion
~2~3~
~ (RD-15,9~1)
of the interlea~ resin into the binder re~in, due to a
positive heat of solution between the dissimilar
species.
The interleaf copolymer may also be prepared
using conventional methods known to those skilled in the
art. The copolymer may be advanta~eou~ly extruded a~ a
film with a par~icular desired ~hickne~ or may be
thinned to a lesser thickness using a conventional
compre~sion molding press.
Tempera~ures and pressure for ~or~ing the
thermoplastic interleafed composites will be varied
according to the selec~ed resin and targeted applicakion~
The fiber-reinforced thermoplastic layer and
interleaf film copolymer can be joined using technique~
w~ll known in the art, such as lamination, casting,
coating, or spraying the interleaf onto a reinforced
fiber-resin substrate.
For la~inated, p~nel-like composites of thl~
invention, any sequence o~ fiber-rein~orced ther~oplastic
29 sheets and interleaf copolymer film can be used. That
is to say, the layers can be laid up in alternating
layers, in any orien~ation, to any number of desired
layers. As one illustration, given in the drawing, three
plies are depicted. T~e corner of a sheet-like
composite accoeding to the invention is depicted,
wherein a woven fabric of rein~orcing filaments is used
a~ the fibrous reinforcement~ The filaments of warp
1 are interwoven to form a sheet with the ~ilament~ 0
weft 2, and are coated with binder resin, e.g., P~T,
to form integral fiber-reinforced layers 3 and 4.
Interlayer film 5 is sandwiched between reinforced
layers 3 and 4, and after consolida~ion under pressure,
an inte~ral composite is formed. The rein~orced layers
may be arranged in any ori~n~ation to take advantage
of the physical properties of the reinforcing fila~en~s
~;293~3~6
-12- (RD-15 ,981 )
or the physical characteristics of the weaYe, in the
case of a woven reinforcing fabric. Those skilled in
the art will appreciate the wide variety of layups that
5 are contemplated by the present invention,.
$he following examples illustrate tha novel
methods and composites of the present invention and are
not to be construed to limit the scope of the appended
10 claims in any manner.
Pre~aration of Fiber-Reinforced Sheets
A faber-reinforced thermoplastic sheet wa~
prepared using poly(l, 4-butylene terephthalate ), VALOX~
310, General Electric Company, as the binder resin and
woven high strength, high modulus carbon fibers,
~AGNAMIT~ A370, ~ercules, Inc., as the reinforcing
substrate. ~AGN~ITE A370 is a balanced 8-harne~s
satin weave of 3000-count tows of MAGNA~ITE- AS4 high
strength, carbon fibers. The carbon fiber fabric was
20 heated to 450C in flowinq nitrogen to re~ove any
sizing .
A fiber-resin co~posite sheet was prepared
using carbon fiber fabric cut to 1~.0 x 11.4 cm in size.
The swatches were cut with tha sides parallel to the
warp and weft of the fabric. The 14.0 cm dimension wa~
always parallel to the warp direction, Because of the
particular weave, the front and back sides of the fabric
appeared differently, with one side having fibers
primarily in the warp direction. This side was
designated the ~s~rong~ qides the other side was
designated as the Uweaka side.
A sym~etric lay-up using four layers of carbon
~iber fabric and two extruded film layers of the PBT
resin was assembled. The average PBT film thickness was
0.0337 cm. T~e six layer~, viewed fro~ the top, were
~93~l6
13 (RD-15,981)
assembled in a mat~ched die, positive-pre3sure,
tool-steel mold in the following sequence: fabric
~weak)~P~T film/fabric (weak)/ fabric (strong)/PBT
filmffab~ic (~trong)~ The inner mold walls were treated
w~th FREKOTE~ 44 mold relea~e agent according to the
manufacturer's ins~ructioAs.
Th~ cold mold was placed between the platen~ of
a 445 kN pre s (Pasadena ~ydraulics Inc.~. Th~ platens
were made to lightly clamp the mold for positive heat
transfer. To facilitate rapid heating, the platen~ we~e
preheated elec~rically to 260C. ~hen the mold
temperature, according to an e~bedded therMocouple, had
reached 200C, co~pre~sive loading was introduced
gradually until 250C, when the maxi~um force of l8 kN
was reached. The hot mold was quickly trans~erred to a
Waba h high-produc~ion pre~s with water-cooled pla~en~,
where the mold was allowed to cool under load control at
19 k~ After cooling9 the compo-~ite was removed from
the mold.
The resultant fiber-resin composite sheet had
glossy, s~ooth suEface~. When dropped on a h~rd
surface, the composite produced a glassy ring. A
section was taken using a Buehler saw, and the section
wa~ embedd~d in pott$ng epoxy and polished using
3tandard m~tallurglcal polishing technique~. There wa3
complete wettlng of the fabric surface and no interfaci~l
cracking.
Another section w~ cut and trea~ed at 500C
in flowing nitrogen to ash th~ binder resinO T~e fiber
weight fraction was 74.4~. Differential scanning
calorimetry on sha~ed composi~e fragments in~icated the
re~in in the PBT composite to be 36.2% crystalline.
Combining these measuremen~s, the fiber volu~e frac~ion
was calculated to be 67.6~.
~'~9~
-14- (~D-15t9~1)
An interlea film wa~ p~epared Prom a
thermoplastic elastomer, copoly(ethermide ester), LO~OD
~-200 (&eneral Electric Co~pany~. The thermoplastic
elasto~er wa~ an extruded fil~ with an average thick~e~
of 0.036 c~ S~o~io~ of film were thinned down to
abou~ 0.011 cm using 222 kN of force in the 445 kN
Pasadena Hydraulics press. Th~ fllm wa~ placed between
heavy gage aluminu~ foil sheets coated with polytetra-
fluoroethylene (PTFE), also k~own a~ Dupont's T~LON~resin, the platens were preheated to 190C, and the
foil/film/foil sandwich was left under load or 100
seconds.
EXAMPLE 1
Three thin fiber-reinforced PBT composite
sheets were made according to the above procedure,
except that each composite was made from two carbonofiber
swatch*s and one P3T film. The swatche-~ were oriented
weak/strong and the stacking seque~ce was ~abric/~ilm/
fabric. The three thin co~posi1 e~ were interleaved in a
cold matched-die, posit~ve-pres3ure mold with three of
the pre-thinned poly(etherimide e~ter) fil~3 in the
following unsymmetrical sequence: composite/
interlea~/composite~in~erleaf/composite/interleaf. The
molding conditions were the same as used to produce the
fiberresin composite sheet~.
The lamina~ed composite plaque obtained had a
smooth, high-gloss surface finish. T~e plaque wa~ fourld
to contain approximately 15S poly(etherimide ester) by
VolU~2. A glassy ring was produced by dropping the
plaque on a hard sur~ace.
Specimens of the PBT/poly(etherimide ester)
laminated composite la~inates were placed in
1,1,2-trichloroethane at 2SC. The polyletherimide
~9~6 RD-15981
ester) dissolved very quickly whereas the PBT showed no
apparent solvation after several house. An embedded
and polished section oE the laminated composite was
exposed to circulating 1,1,2-trichloroethane at 25C
for several hours, then dried in air. Microsaopic
examination revealed long thin areas, outside of the
flattened, impregnated fiber tows, where the
unreinforced poly(etherimide ester) had been
extracted. A polished section was examined before
trichioroethane extraction showed no evidence of
delamination between the interleaf regions and the
impregnated carbon fiber fabric.
Many obvious variations will suggest
themselves to those skilled in the art in light of the
above detailed description. For example, instead of
using poly(1,4-butylene terephthalate) as the
thermoplastic resin, other resins, e.g., polyamide or
polyurethane, can be used. Instead of fabric
comprising reinforcing carbon fibers, other fibers,
such as glass, cellulose, graphite, polyaramide,
silicon carbide, boron, polyester, rayon,
polybenzimidazole, polybenzothiazole, metal coated
poly(benzothiazole) or mixtures of any of the foregoing
can be substituted. In the place of the complementary
thermoplastic resin of the interleaf copolymer, other
resins can instead be employed as long as they are
co-diffusible and co-crystallizable or co-vitrifiable
with the thermoplastic binder resin. For the polymer
(b) used in the interleaf copolymer, other polymers,
instead of poly(ethermide ester), can be employed so
long as the interleaf copolymer as a whole leads to the
formation of the impact and delamination resistant,
integral composites such as described above. Instead of
laminating the plies and interleaf films to form planar
1~3~91~i
-16 - (Rl:1~15 ~981 )
l~mislates ~ the interl~af can be in'crodu~ed onto the
reinforced th2~moplastlc ply by ca~ting 9 coating c~r
spraying, and shaped article~ of two or mult:Lple layer~
can be made.
S All such variation~ are with.irl the full
intend~d ~cope of the appended claim~a
