CA1294772C - Composite fiber blends - Google Patents

Abstract

ABSTRACT

The instant invention involves a process used in preparing fibrous tows which may be formed into polymeric plastic composites. The process involves the steps of (a) forming a tow of strong filamentary materials; (b) forming a thermoplastic polymeric fiber; (c) intermixing the two tows;
and (d) withdrawing the intermixed tow for further use.

Description

BACKGROUND OF INVENTION
.
This invention relates to processes for preparing fibers useful in forming composite articles. More particular-ly, this invention relates to fiber blends containing strong reinforcing fibers which are useful in preparing composite articles.
Fiber-reinforced products have been known for several years. See, for example, U.S. Paten-t ~os. 3,914,499, 3,969,171 and 4,214,931, as well as U.S. Patent No. 4,341,835.
; 10 Also, it is known to intermix two similar or differ-ent types of fibers, particularly to obtain high bulk. See, for example, U.S. Patent Nos. 4,219,997, 4,218,869, 3,959,962, 3,968,638, and 3,958,310. And the combining of different types ,. , of fibers has been facilitated using various types of fluid jets. See, e.g., the '310 patent and U.S. Patent No.
4,147,020. However, in the '020 patent, after combining the yarns are cut into short lengths.
U.S. Patent No. 4,226,079, issued October 7, 1980, discloses the combining of two different types of fibers, in order to produce a bulk yarn. The fibers are intermixed in a jet intermixing zone. However, the fibers disclosed in the patent are polyester and polyamid. No disclosure is made in the combining of carbon and thermoplastic fibers.
U.S. Patent No. 3,175,351 discloses a method of bulk-ing continuous filament yarns. In addition, it is disclosed that the two yarns which are combined may be of different com-positions. However, none of the compositions is a carbon fiber.

U.S. Patent No. 3,859,158 discloses the preparation of carbon fiber reinforced composite articles by forming an ~`'J' 71012-177 ~ 7 ~

open weave of a carbon fiber and coating with a carbonaceous material. U.S. Patent No. 4,368,234 discloses complex woven materials used for reinforcement which are formed from alterna-ting bands of graphite fibers and low modulus fibers.

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~ ~` ~ t ~ 7 72 However, the woven materials disclosed in this patent are subsequently impregnated with a thermosetting resin and cured.
Commonly assigned U.S. Patent No. 4,479,999 to Buckley and McMahon, discloses an improved woven fabric comprised of fusible and infusible fibers wherein the infusible fibers include graphite or carbon fibers, and the fusible fibers are thermoplastic in nature. According to the patent l-~L~b~
fusible and infusible fibers are woven in to a fabric and thermally bonded togather by heating above the melting point of the fusible fiber. This patent application does not disclose, however, the preparation of linearly intermixed fiber tow products or that such products are useful in forming composite articles. The patent application also does not disclose the preparation of such materials using a gas jet intermixing means.
In the prior art, there were two distinct methods of forming fiber-reinforced composites. The first and older method involved simply forming a tape or fabric prepreg by painting or coating reinforcing fiber two or fabric with a solution and/or low viscosity melt of a thermosetting material which was then cured. The second process involved the extrusion of reinforcing fiber tapes impregnated with high melting, thermoplastic polymers. These tapes or fabrics were then used in forming the composite. However, the prepreg formed by both of these processes were somewhat difficult to handle. Specifically, prior art thermoplastic tapes were stiff and "boardy" and could not be dra~ed across intricately shaped molds. While thermoset prepregs were somewhat more flexible, they were often quite tacky and difficult to handle. As a result, the use of both types of tapes was limited.

A

7~2 ~ ccordingly, it is an object of this invention to prepare fibrous blends which are useful in forming fiber-reinforced composites.
It is another object of this invention to prepare materials, e.g., fabrics, which may be formed into composites.
These and other objectives are obtained by employing the process of the instant invention.
SUMMARY OF THE INVENTION
In one aspect therefore, the present invention provides a continuous fiber tow useful in forming composite articles which comprises an intimately intermixed blend of about 90 to about 30~ by volume, based on the total fiber content, of continuous, spun thermoplastic fibers having a melting point of at least about 50C and about 10 to about 70~ by volume, based on the total fiber content, of continuous, non-thermoplastic reinforcing fibers wherein there is a substantially uniform distribution of the thermoplastic fibers and the reinforcing fibers within the intermixed tow, said thermoplastic fibers and said reinforcing fibers having been intermixed in a relatively tension-free state.
In another aspect, the invention provides a process for preparing a fiber tow useful in forming composite articles which comprises:
(a) forming a continuous tow of continuous, non-thermoplastic reinforcing fibers;
(b) forming a continuous tow of continuous, spun thermoplastic polymer fibers having a melting point of at least about 50C;
(c) spreading the non-thermoplastic reinforcing fiber tow;
(d) spreading the thermoplastic polymer fiber tow;
(e) intimately intermixing the spread thermoplastic D

polymer fiber tow and the spread non-thermoplastic reinforcing fiber tow when in a relatively tension-free state; and (f) withdrawing the intimately in-termixed tow.
In yet another aspect, the invention provides a process for forming a composite article which comprises applying to a mold a continuous fiber tow containing a mixture of about 90 to about 30% by volume, based on the total fiber content, of continuous, spun thermoplastic fibers having a melting point of at least about 50C, and about 10 to about 70% by volume, based on the total fiber content~ of continuous, non-thermoplastic reinforcing fibers, the fibers being intimately intermixed when in a relatively tension-free state whereby there is a substantially uniform distribution of the thermoplastic fibers and the reinforcing fibers within the tow, and heating the tow to above the melting point of the thermoplastic fibers.
Basically, the process of the invention involves (a) forming a fiber tow from a multitude of strong filamentary reinforcement materials; (b) forming a thermoplastic polymeric fiber tow; (c) intermixing the two tows when in a relatively tension-free state; and (d~ withdrawing the intermixed tows for use. The filamentary reinforcing material is preferably non-thermoplastic. The intermixed tows may then be employed in forming various fiber-reinforced composites.
The fiber blends prepared according to the instant invention are flexible and handleable and have good draping ~ properties, so that they can be used to form intricately shaped ; articles. In addition, because of the intermixing of the two fibers, good wetting of the reinforcing fiber by the 7s7z thermoplastic material is obtained when appropriate heat and pressure are applied to the mold. Good wetting is obtained in large measure because of the substantially uniform distribution of the thermoplastic fiber and the reinforcing fiber within the : fiber blend. Specifically, the products of the instant invention .Eind particular utility in end-use applications where a small radius of curvature in the final product is desired.
For e~ample, using the prior art tapes, it was not possible in many instances to prepare articles which had 90 bend, because the tapes would crack or deform at -the bend line. ~owever, the processes of the instant invention may be employed with radii of curvature as low as 0.002 in.

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~ ' ~.2~772 DESCRIPTION OF THE DRAW1~6S
FIG. 1 ~s a diagramat~c vlew of the varlous devices used ln carry~ng out one of the processes of the lnstant invention.
FIG. 2 is a dlagramatic view of the various devices used in carrying out another version of the proceses o~ t~e instant lnvention.
FIG. 3 is a perspectlve v~ew of the gas spread~n~ means used in carrying out a part of the prccess of the ~nstant ~nvention.
FIG. 4 is a perspect~ve view of the same device with the top removed.

2:

DET~ILED DESCRIPTIO~ OF I~VENTIO~
h The thermoplast1C polymers wh1ch are useful ln carry~ng out the instant ~nvent10n const~tute vlrtually any type o~
relat~vely high ~olecular weight thermoplastle polymer, including polyethylene, polypropylene1, polyester, the var10lls polyamides, poly~mldes, polyamidimides, polyetherlm1des~
polysulfones (e.g., polyether sulfones~, polyether ether ketones, polybutylene terephthalate and the 11ke. The melt~ng point of the polymer must be at least 50F. and preferably at least 200F. above amblent conditions. Higher melt~ng temperatures ~nsure that there w~ll be no undue st~cking or b~nd~ng of the spun fibers pr~or to use. In . . additlon to one component polymer systems, m1xtures.of varlous thermoplastic polymers may also be employed to advantage where specif~c comb~natlons of properties are desired.
Of part~cular ~mportance are the 1iquld crystal polymers or LCP's. Examples of these polymers include the wholly aromat~c polyester reslns which are discussed in the following publ~cations: (a) Polyesters of Hydroxybenzo~c Acids, by Russell Gilkey and John R~ Caldwell, J. o~ Applled Polymer Sc~., Vol. II, Pages 198 to 20~ (1959~; (b) Polyarylates (Polyesters From Aromatlc D~carbox~llc Aclds and Bisphenols), by G. B~er, Polymer, Yol. 159 Pages 527 to 535 (August 1974); (c) Aromatic Polyester Plasttcs~ by S. G.
Cottis, Modern Plast1cs, Pages 62 to 63 (July 1975); and (d) r Poly(p-Oxyben~oyl Systems): Homopolymer for Coat~ngs:
Copolymers for Compression and In~ectlon MoldinQ, by Roger S.
Storm ~nd Steven G. Cott~s9 Coatlngs Plast. Prepr~nt, VolO
34, No. 1, Pages 194 to 197 (Aprll 1974). See also~ U.S.
Patent Nos. 3,039,994; 3,169,121; 3,321,437; 3,5539167;

3,637,595; 3,651,0149 3,723,388; 3,759,870; 3,7b7,621;
3,778,410; 3,787,370; 3,790,528; 3,829,406; 3,890,256; and 3,975,487.
Other polyesters are dlsclosed9 for lnstance, ~n (a) Polyester X7GOA Sel~ Re~nforced Thermoplast~c~ by ~.J.
.. ~ ~A.-~ 6--~2~7~
~ackson, Jr., H.F. Kuhfuss, and T.F. Gray~ Jr., 30th Anniversary Technlcal Conference, 1975 Reinforced Plast~cs/Compos~tes Inst~tute, The Soc~ety o~ the Plast~cs Industry, Inc., Sect~on 17-D, Pages 1 to 4; (b) Belgian Patent Nos. 838,935 and 828,936; (c) Dutch Patent No~
7505551; (d~ West German Patent Nos. 2520819; 2520820;
2722120; 2834535; 2834536 and 2814537; (e) Japanese Patent Hos. 43-223; 2132-116; and 3021-293; and (f) U.S. Patent Nos.
3,991,083; 4,991,014; 4,057,597; 4,066,620; 4,067,852;

4,075~262; 4,083,829; 4,093,595; 4,112,212; 4,118,372;
4,130,545; 4,130,702; 4,146,702; 4,153,779; 4,156,070;
4,159,365; 4,160,755; 4,161,470; 4,169,933; 4,181,792;
4,183,895; 4,184,996; 49188,476; 4~191,681; 4,201,856;
4,21g,461; 4,224~433; 4~226,970; 4,230,817; 4,23~,143;
4,238,598; 4~238,bOO; 4,239,913; 4,242,496; 4,245,082;
4,245,804; 4,247,514; 4,256,624; 4,265,~02; 4,267,289;
~ ~.
4,269,965; 4,279~803; and 4,299,756.
The polyesters and copolyesters which are preferred consist essent~ally of structural unlts having recurring groups of the formula O - Rl -O ~ and (II) ~ OC - R2 ~ CO ~ and/or (III) ~ O - R3 - C~

where~n units I and I}, if present, are present ~n substantially equ~molar amounts; Rlz ~2 and R3 are rad~cals selected from the group of (1) single and fused s7x-membered aromatic carbocyclic ring systems wherein the cha1n-extend~ng bonds of the rlng system ~f attached to the same rtng-, are pos~tioned 1,3-~ or 1,4- (preferably 194-) to each other, and ~ attached to different rings, are preferably ~n posit~ons parallel and oppos1tely dlrected~ and (2) mult~ple six-membered aromat~c carboxcycllc ring systems ln whlch the ~ndividual rings are ~o~ned by a che~ical bond or ~
trans-vinylene group and ~n which the chain extendlng bonds .'~ ' lZ3~t7~2 of each rlng are ln the 1~3~ or 1,4- (pre~erably 1,4-) posltlons; R2 may also be ~ or ~ - A- -where~n A 15 a d1valent radical containtng one or two bicycl~c ~n-chain atoms; and R3 may also be wherein ~he aliphattc port~on is attached to the carbonyl group. Preferred group (l~ radicals are phenylene and Preferred group (2) radlcals are two-r1ng systems.
Illustrat~ve of (l) are and of (2) are H H
; ~ - and ~ C = C ~

The foregoing r~ng systems~ except for R2 as tndlcated below, ~ ;
are also tntended to tnclude one or more substttuents, e.g., chloro, bromo, ~luoro, or lower alkyl (1-4 carbon atoms) on the rtng or rings~ The R2 aromatic ring systems should preferably be unsubstltuted when only one kind of unlt I ~nd one klnd of un~t II are used, t.e., when a homopolymer 1s formed to ~nsure obtaintng oriented ftbers. In the case o~
copolymers, 1t ts preferred tha~ the R2 aromae~c ring systems be unsubstituted because o~ therma7 or hydrolytlc ~nstabll~ty and/or cost of the R2-rtng substttuted copolymers.
Also tncluded are those (co~polyesters whereln up to 25 , ~ mol X, preferably up to 5 mol X, based on the total I, ~I and .. .
III unlts, are aromatic polymer-~orm1ng unlts (1.eO, un1ts where~n the cha1n extendlng functlonal groups are attached to aromatic rtngs) not conform~ng to those described above and whlrh do not lnterfere w~th the anlsotrop1c melt formlng capab11~ty of the polymers. A non-11m1t~ng 11st of these unlts 1ncludes Ct C

~ ~~

and ` The (co)polyesters, as ment~aned above, m3y compr1se ; UhitS I and II in substantlally equimolar amounts or may r comprlse un1t III or may comprise a oomb1nation of un1ts I, II, and III and, o~ course, more than one k~nd of un1t (I~
and/or III) can be present 1n the polymer.
Preferred (co)polyesters of the 1nventlon cons1st essent1alty of un1ts I and II. In such polymers, 1t ls preferred that Rl ~s selected from the group of 1,4-phenyl~
ene; chloro-D d~chloro~ bromo-, d1bromo-, methyl-, d1methyl-7~2 and fluoro-1,4-phenylene; 4,4'-biphenylene, 3,3',5,5'-tetra-methyl-4,4'-biphenylene and R2 is selected from the group of trans-1,4-cyclohexylene; trans-2,5-dimethyl-1,4-cyclohexylene;
trans-vinylenebis(1,4-phenylene); 4,4'-biphenylene; 2,6-napthy-lene; and 1,4-phenylene and with the proviso that more than one kind of unit I or II are present. Of such copolyesters, two types are particularly preferred because of properties and cost. In the first type, the polymers consist essentially of the recurring units (.~)n O _ ~ O_,_C--~ C _ , and --C--Y--C

; wherein X is selected from the group of chloro-, bromo-, fluoro-, and methyl radicals; n is 1 or 2; and Y is selected from the group of 4,4'-biphenylene and 2,6-naphthylene, the ratio of O O O O
-C - ~ C - to - C - Y --C -units being within the range of 4:1 to 1:4. In the second type, the polymers consist essentially of the recurring units C~3 C~3 fH3 _ ~ ~ O--and H3 CE~3 CH3 O O
il 11 --C ~ Z--C--, ~ -- 10 --wherein Z is selected from the group of 4,4'-biphenylene, 2,6-naphthylene, and 1,4-phenylene, the ratio of \33 IH3 - ~ 0-t - O ~ } / ~ O _ lOa -, ,~, ,, 7'72 units belng w~th~n the range of 4:1 to 3:2. ~lth each type . "
of polymer, up to ~5 mol percent of non~conform1ng unlts may be present as descr~bed a~ove.
A l~st of useful d1carboxyllc aclds ~ncludes terephthal~c ac1d, 4,4'-bibenzo~c acldg 4,4'-oxyd~benzo~c acid, 4,4'-thiodlbenzoic acid, 4-carboxyphenoxyacettc acld, 4,4'-trans-tilbened~carboxyl~c acid, 2,6-naphthalene-dicarboxylic acid, ethyleneoxy-4,4'-dibenzo~c ac~d, ~so-phthal1c acid, the halogen and methyl substituted der~vat1ves of the forego~ng d1carboxylic ac~ds, 1~4-trans-cyclohexane-d~carboxylic ac1d, 2,5-d~methyl-1,4-trans-cyclohexanedi-carboxyl~c acid, and the like.
A nonl~m~t~ng list of phenolic carboxylic aclds lncludes 6-hydroxy-2-napht~olc acid, 4-hydroxy-4'carboxy azoben ene, ferul~c acid, 4-hydroxybenzolc acid, 4-(4'-hydroxyphenoxy)-benzolc acid and 4-hydroxyc1nnam~c acid and the alkyl, alkoxy and halogen subst1tuted vers~ons of these compounds.
Of the (co)polyesters containing only type III un~ts, the polymers consisting essentially of the recurring un~ts Ol H H D
-C ~ 0 and -O ~ ~ are preferred.

(1,4-benzoate unit) (1,4-c~nnamate unit) The (co) polyesters are prepared preferably by melt polycondensat~or of der~vatfves of d~hydric phenols and aromat1c-allphatic, aromatic and cycloal~phat~c dicarboxyl~c acids or their derivat~ves. A convenlent preparat~ve method 1s the melt polycondensat~on of the d~acetate of a d~hydrlc phenol with a dlcarboxyl1c ac~d. Alternat~vely, phenol~c carboxylic ac~ds or their derlvatives may be used as co-reactants ~n the preparat~on of potyesters and copolyesters.

4L 7 ~ 2 ; ~
A 11st of useful dihydric phenols, preferably ln the -:
form of their d7acetate derlvat~ves ~ncludes hydroqu~none, chlorhydroqu1none, bromohydroqulnone~ methylhydroqulnone, d~methylhydroqv1none, d~chlorohydroqulnone, dlbromohydro~
qulnone, 4,4'-ox~diphenol, 4,4'-lsopropylldened~phenol, 4,4'-thlod~phenol, 4,4'-biphenol, 3,5,3',5'-tetramethyl-4,4'-b1sphenol, 3,5,3'5'-tetrachloro-4,4'-b~phenol; 2,6-dihydroxynaphthalene, 2,7-d~hydroxynaphthalene~ and 4,4'-methylenediphenol and the 11ke.
In addttion, it is posslble to prepare an~so~rop1c polymers by polymer~z~ng methylacryloxy benzotc acid utili~ing an alkall metal hydrox~de and free radlcal in~tlators as described ~n U.S. Patent Nos. 4,112,21?, 4,130,702 and 4,160,755, Useful phenol~c-carboxylic ac~d derivat~es lnclude p-acetoxybenzo~c acld and p-acetoxyc~nnam1c acid and the l~ke.
A nonllm~ting l~st of Yarious polyesters and copo1ymers includes: poly(methyl-1,4-phenylene, 2,5-dimethyl-trans-hexahydroterephthalate); copoly(methyl-1-4-phenylene trans-hexahydroterephthalate/terephthalate) (8/2); copoly(chloro-1,4-phenylene trans-hexahydroterephthalate/isophthalate) (9/1) and (8/2); copoly(ethyl-1,4-phenylene ~erephthalate/-2,6 naphthalate) (7/3); copoly(tert. butyl-1,4 phenylene/-3,3',5,5'-tetramethyl-4,4'-b~phenylene/terephthalate) (7/3);
copoly(chloro-1,4-phenylene/-3,3'~5,5'-tetrachloro-4,4'-b~
phenylene terephthalate) (7~3)O
The l~quid crysta~ po~ymers including wholly aroma.t~c polyesters and poly(ester-amlde)s whlch are su~table for use 1n the present ~nvent~on may be formed by a var~ety of ester form~ng techn~ques whereby organic monomer rompounds possessing funct~onal groups which, upon condensation, form the requ1site returr1ng moiet1es are re~cted. For ~nstance~
the functional groups of the organ~c monomer compounds may be carboxyllc ac~d groups, hydroxyl groups, ester groups, acryoxy groups, acld halldes, am~ne groups, etc. The organ1c monomer compounds may be reacted ln the ~bsence of ~ heat exchange fluld via a mel~ acldolysis procedure. They~
accordingly may be heated lnltlally to form ~ melt solutlon of the reactants with the reac~lon cont~nu~ng as sald polymer particles are suspended there~n. A vacuum may be appl~ed to fac~lltate removal of volatiles formed dur1ng the final state of the consensation (e.g., acetic acid or water).
Commonly-asslgned U.S. Patent No. 4,0839829, ent~tled "Melt Processable Thermotrop~c Wholly Aromatlc PolyesterU, descr~bes a slurry polymerlzatlon process whlch ~ay be employed to form the wholly aromatlc polyesters whlch are preferred for use in the present ~nvenelon. Accordlng to such a process, the solid product ls suspended ln a heat exchange med~um. The d~sclosure of thls patent has prevlously bQen incorporated here~n by re~erence in lts entlrety. Although that patent ~s directed to ~he preparat~on of wholly aromatlc polyesters, the process may also be employed to ~or~ poly(ester-amide)s.
When emp70y~ng the elther the melt acidolysis or slurry procedure of U.S. Patent No. 4,083,8~9, the organ~c monomer reactants from which the wholly aromatlc polyesters are derived may be lnitially prov~ded ~n a modifled form whereby the usu~l hydroxy groups of such monomers are esterlfled (i~e., they are provlded as lower acyl esters). The lower acyl groups preferably have ~rom about ~wo to about four ~!
carbon atoms. Preferably~ ~he acetate esters o~ organic monomer reactants are prov~ded, When poly(ester-am{de)s are to be ~ormed, an am~ne group may be provlded as a lower acyl am~de.
Representative ca~alysts wh~ch optlonally may b~
employed ln either the melt acldolysis procedure or ln the slurry procedure of U.S. Patent No. 4,083,829 ~nclude d~alkyl tin ox1de (e.g., dlbutyl tln oxide)~ dlaryl ttn oxide, t~tanlum dioxide, ant~mony tr~oxlde, alkoxy titan~um sll~cates, tltanlum ~lkoxldes, alkal~ and ~lkal~ne earth i-'7 - Z ~3 `, metal salts of carboyxl~c ac~ds (e.g., ~lnc acetate)~ the gaseous acld catalysts such as Lew~s ~c~ds (e.g., BF3), hydrogen halides (e.g., HCl)9 etc. The quant~ty of catalyst utllized typ~cally ls about 0.001 to 1 percent by welght based upon the total monomer we~ght, and most commonly about 0.01 to D.2 percen~ by ~e~ght.
The wholly aromat~c polyesters and poly(ester-am~de)s suitable for use tn the present ~nventlon tend to be substantlally insoluble ln common polyester solvents and accord~ngly are not susceptlble to solution process~ng. As d~scussed prev~ously~ they can be read~ly processed by common melt process~ng techn~ques. Most sultable wholly aromatlc polymers are soluble ln pentafluorophenol to a l~m~ted extent.
The wholly aromatic polyes~ers wh~ch are preferred for use ~n the present lnvention common1y exh~b~t a weight average molecular welght of about 2,000 to 200,000, and preferably about 10,000 to 50,000, and most prPferably about 20,000 to 25,000. The wholly aromatio poly(ester-amide)s whlch are preferred for use In the present invention commonly exhib~t a molecular we~ght o~ about 5,000 to 50,000, and preferably about 10~000 to 30,000; e.g., lS,000 to 17,000, Such molecular we~ght may be determined by gel permeat~on chromatography and other standard techn~ques not lnvolY~ng the solut~on~ng of the polymer, e.g.~ by end group determ~nation v~a ~nfrared spectroscopy on compress~on molded f~lms. Alternat~vely~ l~ght scatterlng technlques ln a pentafluorophenol solutlon may be employed ~o determine the molecular welgh~
The wholly aromat~c polyes~ers and poly~ester-am~de)s additionally commonly exh~b~t an 1nherent vlscos~ty (I.V.) of at least approxlmately 2.0 dl./g., e.g., approximately 2~0 to 10.0 dl.lg., when d~ssolved at a concentratlon of O.l percent by we~ght ln pentafluorophenol at 60C.
For the purposes 3f the present lnventton, the aromat~c rings ~h~ch are ~ncluded ~n the polymer b~ckbones of the polymer components may include substitution of at least some of the hydrogen atoms present upon an aromatic ring. Such substituents include alkyl groups of up to four carbon atoms;
alkoxy groups having up to four carbon atoms; halogens; and additional aromatic rings, such as phenyl and substituted phenyl. Preferred halogens include fluorine, chlorine and ; bromine. Although bromine atoms tend to be released from organic compounds at high temperatures, bromine is more stable on aromatic rings than on aliphatic chains, and therefore is suitable for inclusion as a possible substituent on the aromatic rings.
It is emphasized that an important aspect of the present invention which complements the concept of substantially uniform distribution of intermixed fibers is the combination of compatible thermoplastic materials with non-thermoplastic materials or materials having a sufficiently high melting temperature, whereupon effective bonding and integration can be achieved by application of heat and pressure sufficient to melt the thermoplastic material but not sufficient to melt the reinforcing material. Thus, the use of relatively high melting thermoplastic materials are contemplated as reinforcing fibers of the present invention, although such materials are referred to as "non-thermoplastic"
throughout the specification and claims solely for the sake of brevity.
The reinforcing fibers useful herein are metallic or ceramic, amorphous, polycrystalline or single-crystal reinforc-ing fibers or filaments. Common examples are carbon, glass, boron and boron nitride, ceramic fibers, such as silicon carbide, silicon nitride and alumina, aramides, ordered polymers, etc.

D

~ t7t2 The use of carbon fibers as reinforcing fibers is specifically described and claimed in co-pending Canadian Patent Application No. 476,472 filed on March 14th, 1985.

- 15a -77;~ ~j The glass f~bers utlllzed are manu~actured and marketed ``
commerclally. The ftbers are drawn from ~ molten supply of glass conta~ned ~n a platinum conta~ner having a large pluraltty of very fine holes tn the bottom thereof from whtch the molten glass is drawn at h~gh rates of speed whtch attenuate the glass tnto extremely ftne d~ameter. The glass ~tlaments are pretreated as drawn from the plat~num conta~ner, usually called a ~bush~ng" w~th a s~ze serv~ng to enhance the compatablltty of the ult1mate glass yarn w~th the thermoplast~c flber wh~ch ts utll1zed.
The glass fibers contemplated are cont1nuous glass f~bers tn the form of unstranded f~laments, stranded glass ftlaments, untwisted bundles of stranded glass ftlaments tncluding twis~less rovlng al~ here~nafter referred to as glass fibers.
S~ze com~osttions are contemplated hereln and those preferred for use tn the pract~ce of the present tnventton are those conventionally used in the treatment of glass fibers. Such size composit~ons conta~n, as the essenttal component, a glass fiber anchor~ng agent such as an organo silicon compound or a Werner complex compound.
Preferred anchor1ng agents are ~he amlno s11anes, such as gamma-am~nopropyltriethoxy s~lane1 N-(betaam~noethyl)-gamma-aminopropyltriethoxy s~lane, etc. However, use can also be made of any o~ the organo silanes as well as the correspondtng stlanols and polysiloxanes. Representat~ve o~
other suttable anchor~ng agents wh~ch can be used 1n the practtce of th~s tnventton are the-organo s~licons, thetr hydrolysts products and polymertzatton products (polys~lo- -xane).

2 ~ 77~ ;~

Instead of organo silIcon as descr~bed above, use csn also bs made of Werner complex compounds c~ntaln1ng a carboxylato group coordlflated wlth the trlvalent nuclear chromlc atoms, and ln whlch the carboxylato group may also contaln an amlno group or an epoxy group. Sultable Werner complex compounds lnclude stearato chromlc chlorlde, methacrylato chrom1c chlorlde, aminopropylato chromic chlorlde, glyclne chrom~c complex or glyclato chrom~c chlor~de.
Ceramlc f1bers rontemplated for use herein lnclude slllcon carb~de (composed of ultraflne beta-SlC crystals), sillcon n~tr~de (S13N41 and alumina (A1~03) fibers.
Any slltcon carb~de fiber system w1~h the requlsi~e strength can be used~ although a multl~ ment 5ill on carb~de yarn with an aYerage ~ilament dlameter up eo 50 microns ls preferred and yarn wlth average fllamen~ diameter of 5 to 15 microns ls especially pre~erred. If a slllcon carbide monofilament fs used, a typical silicon carbtde monof11ament of approximately 140 m1crons diameter ls avatlable from AVC0 Systems Division, Lowell, Mass. ~his flber exhibits an average tens~te strength of up to 3~50 MPa, has a temperature capab111ty of over 1300~. ~nd ~s stable ln ox~d~zlng envlronments.
Alumlna f~bers have been available for several years~
They have been o~ part~cular lnterest for appl~catlon ln metal matrix compos~tes because of thelr excellen~ strength and modulus. espec~ally at hi~h temperature. The two princ~pal types of alum~na flber had been, however, the-large dlameter (~ 350J~) single crystal rods or alumlna wh~skers. J
The problems of handling and prosess~ng of whiskers and the very high cost of the slngle crys~al f~ber dampened the enthusiasm ~or their use ln composltes. The-s~tuatlon changed. however, ~1~h the advent of hlgh quallty alumlna yarns wh~ch, because of ~helr low potentlal cost and attractlve mechanical propert1es, could be serlously consldered for use ln composltes. In general, these flbers are produced by E.I. DuPont de Nemours, Inc., 3M Corporatlon ~;~
and 1n the USA and Su~ttomo Chemicals Co., Japan.
The DuPont f~ber, referred to as f1ber FP~ 1s ~ round cross sectlon, 20~ m d1ameter, contlnuous 1ength yarn hav~ng 2T0 fibers per tow. It ~s ~va~lable 1n two forms. Type I ls pure alpha alum1na whlle Type II 1s s~m11ar but coated wlth a th1n layer of glass. Type II was or19~nally 1ntended for res~n matrix composites and Type I for me~al matrlx compo-s1tes; however, ~t ~s found by th1s 1nvent~on that both are sultable for ceram~c compos~tes. Although the 1n1t~al f1ber strength ls not part~cularly htgh, on the order of 1380 MPA
(200,000 ps1), it ~s very lmportant to note that th1s strength ~s stable and not affected by handl1ng and ls not much d~ferent from that realized In compos~tes rein~orced with alum~na rods o~ ln~t~ally h~gher unhandled Npr1st1n2 strength.
The Sumitomo Chemicals fiber are atso produced 1n yarn form; however, there the sim~lar1ty w~th fiber FP ends.
This ~1b~r is not pure alumina and in fact, ~t 1s the pre~
sence of some SiO~ and a very flne structure which permit a claimed use temperature to be 1350C.
On the basis of spec~flc mechan~cal properties this fiber 1s attract~ve. Its low density and high tens~le strength provide a specif~c strength nearly tw~ce that of f1ber FP wh11e the spec~fic modulus approximately equals the FP property. The Sumitomo fiber appears to have superlnr handl eab111 ty .
The known propertles of boron n~tride~ properties such as except1Onally high heat resistance (1800F. ir oxid~z1ng 5000F. ln reduc~ng atmospheres), d1electr1c strength (9S0 v./m~lJ, high surface and volume res~st1v1ty and low diss~-pation factor over a wlde temperature range, make it a pot~
ent1ally attract1ve h1gh temperature re1nforc1n~ fiber cand~-date. The ftbers ~ay vary 1n d1ameter, athough those 7'72 preferred are about lO mlcrons ln dlametel and f~bers hav~ng diameters up to about 30 m~crons may be used. Contlnuous boron nltrlde flbers (99~X boron nltr1de) are avallable commerclally from the Carborundum Corporatlon.
The reinforclng f~bers ~hioh are part~cularly useful herein have bundle or tow den~ers ln the range of ~rom l to lO0,000 and ~llament counts of from 300 ta 300,000, preferably den~ers of lO00 to 16,000 and fllament counts of 3,000 to 24,000. The fibers also should exhlblt a tenslle strength of at least about 100,000 ps1 and a tenslle modulus of about 10~120x106psl.
The thermoplast~c flbers whlch are part1cularly useful hereln have bundle cross-sectional areas rang~ng from about twlce that of the reinforcing fiber tows to about one-half that o~ the relnforclng fiber tow. Bundle or tow denler wlll be ln the range of l to 50 and t~e fiber count w~ll depend upon slngle f~lament denler (hlgher oounts are required with lower denier fllaments). However, 1n general, from about lO
to about 150,000 filaments, preferably 100 to lO,000 fllaments, are employed. The modulus of the flber should be ln the range of 50,000 to 500,000 p51. The thermoplastlG
flber also must exhib~t a meltlng po~nt of more than 50F., preferably more than 200F., aboYe ambient temperatures. And of course, the flber must melt and fuse at temperatures no hlgher than about 1~000F., prefera~ly no hlgher than 800Fo>
tn order to be useful hereln.
The weight ratlo of the two fibers whlch are ln~ermlxed can vary wldely. However9 ln order to prepare satisfactory compos1tes, lt ls necessary that sufflc~ent thermoplastlc polymer fiber be employed to obtaln complete wettlng of the reinforclng fibers. Generally, no less than abou~ 30 percent, by volume, of the thermoplast~c polymer flbers may be employed. The max~mum amount of thermoplastic polymer ~ 72 depends upon the strength propert~es wh1ch are re~u~red. In general, when less than about ten percent, by volume o~ the reinforcing fiber is present, the resulting composite pro-ducts have strength and stiffness propertles wh~ch are poor ~n relatlon to products contain~ng higher amounts of rein-forcing fibers and exhibit little or no ~mprovement over unreinforced matrices. Prefer3bly about 20 to about 60 percent, by volume of the reinforcing fiber mater~al should be present in the combined tow.
In addition to the reinforcirlg fiber and the thermo-plastic fibers which are used herein, ~t is contemplated to add carbon fibers to the fiber blends of the instant Invent-ion as reinforcing fibers. In the event additional car~bon fibers are added, lt is possible to reduce the amount of the reinforcing fiber which is used to as low as approx~mately 10 volume percent. However, the maximum combined amount of the added carbon ~iber plus the amount of the re1nforcing fiber which ~s employed should not exceed the upper limit specif~ed above for the reinforcing fiber alone.
In FIGURE 1 of the instant invention, a reinforc1ng fiber tow (1) is obtained having the properties specified above. The fibers from the reinforcing fiber tow are passed through a fiber guide (3) and onto a first Godet roll (4).
The first Godet~roll is synchron~zed with a second Godet ro11 (11) at rates of speed such that the second Godet roll re-volves slightly sl~wer than the first Godet roll. Hence~ the flbers between the two Godet rolls~ wh1ch are subsequently ~.
spread and intermixed during the process of the invent~on re-main in a low tensioned (approaching tension-free) st~te ` _-which provides for effective fiber intermixlng. Individual thermoplastic polymer fibers, such as polybutylene terephth-alate fibers, are mounted on a bobbin rack (2) and the fibers are fed through a fiber guide (3) onto the first Godet roll (4). A tension comh may be employed after the ~bers leave the bobbin and before they are brought lnto contact with the Godet roll. This tension comb serves to improve the contact of the fiber with the Godet roll and to increase the width of ~the fiber tow~
~7~ m~ 20-At this po~nt in the process neither the reinforc~ng fibers nor the thermoplastic fibers are lnterm~xed or are ln contact. Rather, both are wrapped separately around the first Godet roll (4) to prov~de tension control. After leaving the Godet roll, the indiv~dual f1bers separately pass through a fiber guide (5) to maintlain d~rectional control.
After leav~ng the fiber guide (5), the thermoplastic polymer fibers pass ~hrough a f~ber comb (6). The fiber comb having a plurality of spaced-apart f~ngers acts to maintatn as sep-arate the various fine yarns of the thermoplastic polymerlc f~ber so as to preserve separat10n of the ~ndlvldual fibers.
The reinforcemen~ flbers, on the other hand, after leav~ng the flber guide (5), are directed into a gas banding ~et (7).
The gas bandlng jet showing in FIGS. 3 and 4 ~s used to uniformly spread the fiber tows. A gas "banding" jet can also be used as an intermixing means whereby the gas jet serves to uniformly intermix the two f~ber tows. The banding jet consists of a gas box (40) into wh1ch compressed a~r or another gas is fed through a convent~onal adjustable gas metering means (413. The pre~erred pressure of gas flow 1nto the gas ~et ~s in the range o~ approx~mately 0.5 to 10 ps~O
One, or more than one, gas ex1t ports (44) are provided to cause gas from within the gas box to imp~nge ~n a generally perpendicular fashion upon the fiber tow which passes across the ex~t ports. Preferably, the exit ports are V-shaped and pointed in the direction o~ movement of the f~ber tow across the box.
As shown in FIG. 4, the gas banding jet ls prov~ded w~th shims (46) or other means to allow a gas box cover (48) to be attached, so that a flow channel for the f~bers ls provided.
The gas box cover ~s held in place by convenlent attachment means, such as clamps (49).
In an alternative process shown ~n FIG. 2 both the thermoplastic ~ber and the reinforcing fiber are sub~ect to gas banding jet treatment (26) and (27). However, parti-cularly with lower molecule we~ght, less high meltlng polymers, such as polybutylene terephthalate, a f1ber comb 7'7;~: ~

having a pluraltty o~ spaced-apart flngers, as descr~bed above, may be employed in place of the banding ~et.
After ~he f~bers are spread by bandtng ~ets or bandlng iets in comb~nation w1th combs, they are lntermixed us~ng an in~erm~x~ng means (8). In FI6. I the lntermixlng means 1s a palr of stationary rods or bars. The flbers from the spread relnforcement flber tow and the fibers from ~he spread thermoplastlc tow or yarns both lnltlally come lnto contact together on the bottom of the f~rst statlonary rod or bar.
The ftbers then are deflected across ~he top of the second statlonary bar or rod and, as a result, are lntermlxed. In order to ensure complete lnterm~xlng, ~t ts necessary that both f~bers be uniformly spread across the~r enttre w~dth and that the area within which both ~ibers are spread be vlrtually ldentical. Finally, ~t ~s necessary that ~ntermlx~ng be undertaken ~n a relat~vely tenslon-~ree state.
If high tens~on is imparted to either of the fiber tows, Pull (or optimal) 1ntermixing may not occur. After pass~ng over and under the stationary bars, the combined fib4~-tow-may-be~
further interm~xed us~ng an air entanglement jet as descrlbed above.
After lntermixing, the flbers pass through a comb (9~ to maintaln dlmens~onal s~ablttty and through twlst guides (10) to impart a slight twlst to the intermlxed fibers. The ~wlst ..... . .
ls imparted in order to malntain the ~nterm~x~ng of the f~bersO Instead of uslng an actual half-tw~st, false~
tw~st~ng of the fibers uslng methods well known in the art may be employed. In the alternatlve, a f~ber wrap may be used to hold the interm~xed flbers together. The overwrap J
may be of any convenlent type of fiber. However, 1t ~s preferred that the overwrap consist of a re7atively small quantity of thermoplastlc ~lbers.
The mlxed fibers are then wrapped around a second Godet roll (11) whlch, as pointed out above, serves in con~unct~on with the f~rst Godet roll to prov~de a relat~vely tenslon-free zone to allow flber intermixlng. The flbers are then taken up hy a take-up roll (12) for storage~ 0~ course, lt ~s posslble to ~mpart false-tw~sting or actual tw~st~ng or to wrap the flber tow w~th another f~ber e~ther before or after the Godet roll. In add~tlon, the ~nterm~xed flbers may be made stab1e by applicat~on of an appropr~ate ftber fin~sh wh~ch serves to hold the ~nterm~xed f1bers together and enable eas~er handllng ~n subsequent operatlons, such as weav~ng.
FIG. 2 1s similar to FIGo 1 but 1s the process most preferred when a l~qu~d crystal type polymer or other hlgher melt~ng po~nt polymer ~s used. In FIG. 2 a roll of rein-forc~ng f~lamentary materlal (21) feeds f1ber through tension comb (22) and onto Godet roll (25). Llqu~d crystal f1bers from a roll (23) are fed through a guide (24) and onto the same Godet roll (25). Separation 1s ma~ntained between both fibers on the Godet roll. As po~nted out above, the flrst Godet roll t25), when used in combination w~th the opt~onal second Godet roll (35), serves to ~aintaln the fibers 1n a relatively tens~on-free state during the in~ermixing process.
High ~ension during intermixing must be avoided to assure that complete interm~x1ng occurs.
After the re~nforcing fibers and the 11quid crystal fibers leave the f~rst Godet roll they are both fed into gas band~ng jets (26) and (27) through gu~des ~28) and (29), respect~vely~ In the gas band1ng jet the flbers are spread to a unlform width. The fibers then pass through a second set of fiber guldes (30) and (31) and are tntermixed uslng stat~onary, longitud~nally extended bars shown at (32). In general 3 ~nterm1xing occurs as the thermoplastlc bundle ~s fed onto the same bar ~n the same areas as 1s the reinforce- s ment fiber. At this point ~n the processing, the w~dt-h of both tows is the same, and as they are brough~ slmultaneously lnto contact with the same area of the bar, intlmate ~nterm~x~ng occurs. In an alternat~ve ln~erm1xlng process~
the two f~ber tows are fed s~multaneously ~nto a gas ~et or other gaseous ~nterm~xing dev~ce 1n a rela~vel~ ~enslon~free state. In addl~on, the f~bers may be fed lnto a gas ~e~ ~or ~2~34772 further ~nterm~xing after they have been treated on the statlonary bars, In the gas 1ntermlxing means a ~et of alr impinges on the f~bers, preferably perpendicular to thelr direction of flow.
Fol 1 ow~ ng 1ntermlx~ng, the fibers are fed through twist guides (33) to add at leas~ a half-tw~st per yard to the fiber to ensure d~mens~onal stabllity., Ftbers then pass through a guide (34~ onto a second Godet roll (35) and from there onto a take-up roll (36).
In use, ~he ~nterm~xed ~bers may be filament wound, or otherwise assembled an~ placed on a mold, and heated under pressure to the flow temperature of ~he thermoplasttc polymer to form composite articles wh~ch are use~ul ln a var~ety of end-uses where high strength, high sti~fness and low weight are essent~al. For example, the composites formed from products prepared according to thls ~nvention may be used ~n forming spacecraft, airplane or automob11e structural components. In additlon, the reinforced fiher blends of the instant invention f~nd part~cular util~ty ~n those end-uses where complex, three-dimensional shapes are involYed. As pointed out above, the compos~t~ons of the instant invent1On are particularly useful where there ls a small radius of curvature requir~ng substantial bendlng and shaping of the compos1t~ons of the instant ~nvention. The only l~miting factor ln forming re~n~orced f~ber shaped articles uslng the compositions of the instant tnvention ~s the "bendability" o~ , the reinforc~ng fiber 1tself. Therefore, utillz~ng the j -compositions of the instant ~nventlon, 1t ls poss~ble to L
prepare materials havlng a min~mum rad~us of curva~ure of about 0.002 in., preferably as low as 0.003 ln. However, with prior art thermoplastlc tapes, the minimum rad1us of curvature is about 0.005 in. (Even then fiber d~rectionality or alignment is distorted.) As structural elements formed from the fiber tows of this invention are heated under ' ` . ;.
pressure ahove the melt1ng polnt o~ the thermoplastlc ~lber, these f~bers melt and fuse the f1bers together form~ng a consol~dated compos~te product contaln~ng well-d1spersed reinforc~ng f~bers. Using the f~ber blends of the ~nstant inYent~on~ it is poss1ble to prepare recreat10nal articles, such dS te~n1s racquet frames, racquetball racquet frames, hockey sticks, ski poles, fishin3 rods, golf club shafts and the 11ke.
The f~bers of the instant 1nvention find particular utility in filament winding applicdtions. As po~nted out above, in the prior art ~t was extremely d~ff~eult to prepare composlte art~cles utillz~ng the pr10r art f~ber tapes.
These tapes, which are prepared on extremely large scale, are difficul~ to handle on a small scale, and it ~s particularly d1fflcult to Form them into ~ntricately shaped artlcles.
Wh~le the pr~or art employed the filament winding process w~th sucoess, th1s process was limited to use of re~nforc~ng fibers in combtnat~on w~th thermosetting resins ~f long, thln rods were to be prepared. In the prior art proc2ss, the reinforc~ng f~ber was wound onto a mold a~ter applying a thermosetting coat~ng or coa~ed with the thermosetting material after windlng. As a result, however, lt was often difficult for the thermosett1ng material actually to pene-trate and/or achleve good wetting of closely wound products.
Util~zing the process of ~he 1nstant ~nvention in a modified fllament wind~ng procedure, ~t ~s posslble to prepare lntr~cately shaped art~cles when the fiber blends are oriented 1n directions not parallel to the long ax~s of the article, utilizing thermop1astic polymers tn con~unct~on wlth fiber reinforcements. This modlf~ed f~1ament w~nding process beg~ns with the use of the interm~xed tows of the instant lnvent~on. These tows may be fed d~rectly to a filament winder. As the fl1ament ~inder moves around or up and down the mandrel or form~ the re~nforcement ~ber/thermoplast1c ~ w~ 25 _ ~41~2 .` ~
flber tow ~s applled dlrectly to the mold and heated us~ng a radiant heater or other suitable means for immediately melt~ng and fusing the thermoplast~c polymer~c fibers with1n the re~nforcing f~ber tow. 2n other words, the re~nforcing fiber/thermoplast~c ~iber ~ow should be heated under pressure as soon as or soon after ~t meets the mandrel. After full melt~ng and resol~dtficat10n occurs, the mandrel elther may be dissolved us~ng a sultable solvent, may be pulled from the product, or the mandrel may actually become a part of the product.
Another un~que use ~or the fiber blends prepared according to the instant ~nvention ~s ~n forming woven fabrics ut~lizlng standard techn1ques. According to thls process, ~he tow of the lnstant invention is used either alone or in combination with other tows or fibers to form a woven mat. Ihe woven fabrics prepared according to the process of this ~nvention may be applied to the desired mold or otherwise used in forming a composlte. The previous method of choice of forming such materials involved lay~ng down a layer of reinforc~ng fibers, e.g.~ glass f~bers, followed by a 1ayer of thermoplastic film, followed by another layer of glass, etc. Now the materials can be combined in a solid woven layer and much more readily applied to a mold. After the composlte is formed, it ~s then he~ted under pressure above the flow polnt of the thermoplastic polymer, and a composlte having good mechanical strength and stiffness properties results. The strength and stlffness enhancement can occur ~n one or more d~rectlons, ~.e., those d~rect~ons along which nelnforcement fiber 1s allgned parallel to the definlng vector.

_ "

- ~29477,~

A llqu~d cryst~l polymertc (LCP) ffber tow based upon copolymer prepared from 6-hydroxy-2-naph~hoic acfd and p-hydroxy benzolc ac1d 1s obta1ned. The LCP has a density of 1.4 g/cc, and the tow ~tself ~s formed of 660 f~laments (2.25 denier per fllament). ~he tow had an tnitfal modulus of 5670 gms, a tenacity of 10.5 g/denier, and ~n elongation of 2%.
The second fiber to be used for inter~x~ng w~th the LCP
fiber ls E-glass fiber (204 filament count des~gnated as EC6 150 l/C), having 3 denslty of 2055 gtcc, a tensile strength of 300,000 psl, a tensile modulus of 10,500,000 psi and an ultlmate elongation of 2.8X. The glass flber ~s avallable from both PPG Industr1es and OCF.
Bobbins containfng the LCP polymer~c f~ber tow and the glass f1ber tow are spaced apart on a bobbin rack. F~bers from both bobbins are fed onto and separately wrapped around a Godet roll, so that upon mix~ng the m1xed tow contains approxlmately 50~ by volume of liquid crystal polymer and approx~mately SO~ by volume of glass. The LCP polymer~c fiber fs subject to a 50 gram we19ht on a tens~oning device prior to be~ng wrapped around the Godet roll, tn order to maintafn smooth track~n; on the roll. Af~er leav~ng ~he Gode~ roll, both flbers are separately subjec~ed to a~r jet banding treatments utlliz1ng an air jet which i~pinges a1r appro~fmately perpend~cular to the f1ber ~hrough Y-shaped nozzles. The Jet for the llqu~d crystal polymer ~s operated at 5 ps~, while the glass ftber ~et was operated at 4 ps~
After leaving the band~ng jets, the fibers are brought toge~her over the top and underneath o~ two paral lel, longitudinally extended~ staggered stat~onary bars and are fed through fiber guldes fnto an entanglement ~et, wh~ch ls sfm~lar ~n des19n to the gas band~ng ~et and operated at a gas pressure of 7 psi~, Following fntfmAte ~nter~ixlng of the two ~ows, the fibers are t~ken up on a t~ke-up roll ht a take-up speed of 7-8 m/m1n.

2~ 4 7 72 The composite panels (3-l/2" X lO") are prepared using 20 layers of the intermixed fiber tow. Each layer ~s prepared by first wrapp~ng a heated drum with a Kapton fllm and then filament w~nding parallel rows of the fiber blend prepared above onto the Kapton wrapped drum. A layer o~
Kapton film is then placed over the drum, and the entire wrapped drum is heated so as to temporar~ly fuse the fibers together. The compos~te conta~n~ng th~ 20 ~used layers 1s placed in a pressure mold, heated to about 315C. and held at this temperature for f~ve minutes without appllcatlon of significant mold pre~sure. The mold pressure is then ~n-creased to 500 Ps! and held at about 315 temperature and under such increased pressure for thirty minutes. The material is then cooled at ~0C. and removed from the mold.
The resulting mater~al contains about 50X by volume of E-glass fiber and has a panel thickness of about 0.103".
Util~z~ng the same process, a six-ply 3-1/2" X lO"
composite panel 1s prepared having a glass f~ber volume of about 60X. a panel thickness of about 0~035~O The composltes are evaluted and exhibit excellent tensileg flexural and compression properties.

. ~ . 12~47~2 ';'~',f,~
.' `'` '.1',~,.

Ut~lfzfng the same glass flber as descrlbed ~n Exa~ple l, an approxlmate SOX by volume polyhutylene terephthalate (PBT)~glass flber blend fs prepared. The polybutylene terephthalate materfal has a densfty of 1.34 g/cc and a denfer of 1520 g~9OOOm. The polybutylene terephthalate has a draw ratfo of 2.25-1, an 1n~tlal modulus o~ 24 9, a tenac1ty of 5.3 g/denler, an elgonatfon of 28~, a me1tlng pofnt of 227C. and a denler per filament of 2.7~ Ten packages of 33 f11ament count yarn are employed on ;~ creel, and all packages are merged lnto a slngle polybutylene terephthalate ffber tow on a Godet roll. Ma1ntafned separately, hut on the same Godet roll, ten packages of 408 fllament count glass flber (Tyep ECK 75 211) to provf~fe a total approxfmate hlend of 50/50 by volume glass flber/PBT.
The polybutylene terephthalate tow ls fed through a ~fber comb havfng approxlmately 30 tee~h, ~hfle the glass fiber tow is fed through ~ gas bandlng ~et operatfng as descrfbed fn Example l, at a pressure of about 2-1/2 to 3-l/2 psl. The two tows are then 1ntermlxed over and under parallel extend1ng rods by feedlng both tows 1nto the same area on ~he bars. Intermfx1ng ~s alded by the use of a second gas bandlng Jet of the type descr1bed ln Exampl2 l, operat1ng at 2-l/2 to 3-l/2 psl. After leavlng the bandlng fet, the flhers are fed through a second f1ber comb wh1ch was arranged parallel to the dlrectlon of flnw of the f1her, so as to prov~de a tensfonlng path to ald in lntermlx1ngO After leavfng the comb, t~e ~lbers are fed through twfst guldes to _-provlde~approxlmately a one-half twfst per yard, s~ as to ma~ntafn the ffbers in thelr lntermlxe~,state. The flbers are then wrapped around a second 6Odet roll and t~ken up at a speed of 7-8 m/mln. In order to m~nfmlze tenslon durlng the lntermixlng process, the second Godet roll is operated at a sllghely lower speed than the flrst Godet roll.
3-l/2 X lO" panel compos1tes are prepared generally as descr1bed fn Example l and evaluated satlsfactorlly.

``` ~ 77Z ':(;
. ~ 5 .
A sample of the PBT/glass ftber blend prepared above ls ,. ~ . .
wrapped w1th 90 den1er polybu~ylene terephthalate yarn as descrlbed above at four.wraps per 1n. to form a compact y~rn su1table for fabr1c weaving. The PBT fabrlc wrap ~s chosen, so that 1t would form a part of the matrix upon compos1te fabr1cat10n. The result1ng wrapped yarn ~s then d~vlded ~nto 96 d~fferent yarn segments and placed on spools mounted on a speclal creel.. A 6" w1de fabric ls then woven on a mod1f~ed Draper XD loom, us1ng a pla~n weave pattern. The resul~ng woven product has d~mensions of 16 ends per 1nch X 15 p1cks per lnch and weighs ca. 0.05 oz./yd2. The fabr~c ~s ca. lO
m~ls 1n thickness, 1s soft but compact, and exh1b~ts good d1mens~onal stability~ Sat1sfactory fiber composites hav1ng 1rregular shapes are prepared from the resulting fabr~c.

' ,.

EXA~PLE 3 An approx~mate 50/50X by volume blend ls prepared based upon ~he glass fiber descr1bed 1n Example l and a polyether ether keSone (PEEK) thermoplastlc polymer. The flber prepared from the PEEK has a densit~ of 1.3 g/cc~ a meltlng po1nt of 338C., an 1nltial modulus of 53 grams~ a tenac~ty of 2.7 g/denier3 an elongatlon of 65X, and ln lO f~laments per package tows a dpf of 367 (g/9OOOm). Four (lO filaments per package) tows are placed on a creel and the ~bers are blended together on a Gode~ roll, but ma1nta1ned separately from the glass f1ber ~hlch ls also wrapped around the Godet roll. The PEEK f1ber ls then direc~ed through a flber comb as descrlbed ln Example 2 and lnto a gas bandlng jet. The glass f1ber after leav1ng the Godet roll also enters a gas banding ~et. Both jets are operating a~ a pressure o~ about 3 psi. After leaving the jets the f1bers are ~n~ermlxed above and below two parallel, long1tud1nally ex~ended rods and are fed through ~ second parallel fiber comb, twlsted to ma1nta~n d1mens~onal stability, fed over a second Godet roll and taken up at a speed of ~-lO m/mln. A satlsfactory compos~tion results.

_ 31 -

Claims (32)

1. A continuous fiber tow useful in forming composite articles which comprises an intimately intermixed blend of about 90 to about 30% by volume, based on the total fiber content, of continuous, spun thermoplastic polymer fibers having a melting point of at least about 50°C and about 10 to about 70% by volume, based on the total fiber content, of continuous, non-thermoplastic reinforcing fibers wherein there is a substantially uniform distribution of the thermoplastic fibers and the reinforcing fibers within the intermixed tow, said thermoplastic fibers and said reinforcing fibers having been intermixed in a relatively tension-free state.

2. A continuous fiber tow useful in forming composite articles, said tow being formable into articles having a radius of curvature of at least 0.002 in., which comprises an intimately intermixed blend of about 90 to about 30% by volume, based on the total fiber content, of continuous, spun thermo-plastic polymer fibers having a melting point of at least about 50°C and about 10 to about 70% by volume, based on the total fiber content, of continuous, non-thermoplastic reinforcing fibers wherein there is a substantially uniform distribution of the thermoplastic fibers and the reinforcing fibers within the intermixed tow, said thermoplastic fibers and said rein-forcing fibers having been intermixed in a relatively tension-free state.

3. The tow of claim 1 or 2 wherein the thermoplastic polymer fiber is present at the 80 to 40% level, and the reinforcing fiber is present at the 20 to 60% level.

4. The tow of claim 1 or 2 wherein the reinforcing fibers are formed from the group consisting of metallic, ceramic, amorphous, polycrystalline and single-crystal fibers.

5. The tow of claim 1 or 2 wherein the reinforcing fibers are formed from glass, boron, aramid or ceramic fibers.

6. The tow of claim 1 or 2 wherein the thermoplastic polymer fiber is formed from a material selected from the group consisting of polyethylene, polypropylene, polyesters, nylons, polyamidimides, polyetherimides, polyether sulfones, polyether ether ketones, and wholly aromatic polyester resins.

7. The tow of claim 1 or 2 wherein the thermoplastic polymer fiber is formed from a liquid crystal polymer.

8. The tow of claim 1 or 2 wherein the thermoplastic polymer fiber is formed from a wholly aromatic polyester.

9. A process for preparing a fiber tow useful in forming composite articles which comprises:
(a) forming a continuous tow of continuous, non-thermoplastic reinforcing fibers;
(b) forming a continuous tow of continuous, spun thermoplastic polymer fibers having a melting point of at least about 50°C;
(c) spreading the non-thermoplastic reinforcing fiber tow;

(d) spreading the thermoplastic polymer fiber tow;
(e) intimately intermixing the spread thermoplastic polymer fiber tow and the spread non-thermoplastic reinforcing fiber tow when in a relatively tension-free state; and (f) withdrawing the intimately intermixed tow.

10. A process for preparing a fiber tow useful in forming composite articles which comprises:
(a) forming a continuous tow of continuous, non-thermoplastic reinforcing fibers;
(b) forming a continuous tow of continuous, spun thermoplastic polymer fibers having a melting point of at least about 50°C;
(c) spreading the non-thermoplastic reinforcing fiber tow;
(d) spreading the thermoplastic polymer fiber tow;
(e) intimately intermixing the spread thermoplastic polymer fiber tow and the spread non-thermoplastic reinforcing fiber tow when in a relatively tension-free state by employing a gas intermixing means; and (f) withdrawing the intimately intermixed tow.

11. The process of claim 9 or 10 wherein the reinforcing fibers are formed from a material selected from the group consisting of metallic, ceramic, amorphous, polycrystalline and single-crystal fibers.

12. The process of claim 11 wherein the reinforcing fibers are formed from glass, boron, aramid or ceramic fibers.

13. The process of claim 9, 10 or 12 wherein the thermo-plastic polymer fiber is formed from a material selected from the group consisting of polyethylene, polypropylene, polyesters, nylons, polyamidimides, polyetherimides, polyether sulfones, polyether ether ketones and wholly aromatic polyester resins.

14. The process of claim 9, 10 or 12 wherein the thermo-plastic polymer is a liquid crystal polymer.

15. The process of claim 9, 10 or 12 wherein the thermo-plastic polymer is a wholly aromatic polyester.

16. The process of claim 10 wherein the gas intermixing means comprises a gas box having a gas impingement means which directs a generally perpendicular gas flow onto the fibers.

17. The process of claim 9 wherein intermixing is effected by an intermixing means which is a longitudinally extended rod wherein the reinforcing fiber tow and the thermoplastic fiber tow are brought into simultaneous contact in the same area of the rod in a relatively tension-free state.

18. The process of claim 17 wherein a second rod is employed.

19. The process of claim 9 or 10 wherein the intermixed tow contains about 10 to about 70% by volume of reinforcing fibers.

20. The process of claim 9, 10 or 12 wherein the inter-mixed tow contains about 20 to about 60% by volume of reinforcing fibers.

21. The process of claim 9, 10 or 12 wherein the inter-mixed tow contains about 10 to about 70% by volume of a reinforcing fiber selected from the group consisting of glass boron and ceramic fiber, and wherein the thermoplastic fiber is selected from the group consisting of polyethylene, poly-propylene, polyesters, nylons, polyamidimides, polyetherimides, polyether sulfones, polyether ether ketones, and wholly aromatic polyester resins.

22. A process for forming a composite article which comprises applying to a mold a continuous fiber tow containing a mixture of about 90 to about 30% by volume, based on the total fiber content, of continuous, spun thermoplastic polymer fibers having a melting point of at least about 50°C, and about 10 to about 70% by volume, based on the total fiber content, of continuous, non-thermoplastic reinforcing fibers, the fibers being intimately intermixed when in a relatively tension-free state whereby there is a substantially uniform distribution of the thermoplastic fibers and the reinforcing fibers within the tow, and heating the tow to above the melting point of the thermoplastic polymer fibers.

23. The process of claim 22 wherein the reinforcing fibers are formed from a material selected from the group consisting of metallic, ceramic, amorphous, polycrystalline and single-crystal fibers.

24. The process of claim 23 wherein the reinforcing fibers are formed from a material selected from glass, boron or ceramic fibers.

25. The process of claim 22, 23 or 24 wherein the thermo-plastic polymer fiber is formed from a material selected from the group consisting of polyethylene, polypropylene, polyesters, nylons, polyamidimides, polyetherimides, polysulfones, polyether ether ketones, and wholly aromatic polyester resins.

26. The process of claim 22 wherein the thermoplastic polymer is a liquid crystal polymer.

27. The process of claim 22 wherein the thermoplastic polymer is a wholly aromatic polyester.

28. The process of claim 22 wherein the intermixed tow contains about 20 to about 60% by volume of non-thermoplastic reinforcing fibers.

29. The process of claim 22 wherein the intimately inter-mixed fiber tow is applied to a mold employing a filament winding process.

30. The process of claim 22 wherein the fiber tow is applied to a mold in the form of a woven fabric.

31. The process of claim 23 wherein the composite article is a recreational article.

32. The process of claim 31 wherein the composite article is a tennis racquet frame.