CA2124833A1 - Abrasive filaments comprising abrasive filled thermoplastic elastomer, methods of making same, articles incorporating same, and methods of using said articles - Google Patents

Abstract

An abrasive filament, including a thermoplastic elastomer having abrasive particles dispersed and adhered therein, exhibits improved life over previously known abrasive-filled polymeric filaments. Previously known abrasive-filled nylon filaments have limited stiffness and lose their stiffness as temperatures approach 70 ·C.
The abrasive filaments of the present invention are more efficient and more resistant to flex fatigue failure than abrasive-filled nylon filaments. Methods of making abrasive filaments of the invention, articles including the abrasive filaments, and methods of abrading surfaces using the abrasive articles of the invention are also described.

Description

2 ~
~ wo 93/18891 Pcr/uss3/012sl ABRASIYE FILAMENTS COMPRISING ABRASIVE-FILLED THERMOPLASTIC ELASTOMER, METHODS
OF MAKING SAME, ARTI~LES INCORPORATING SAME.

llECH ~ CAL EnELD
The present inven~on relates to abrasive filaments comprising at least one layer componer.t which includes an abrasive-filled thermoplastic elastomer.
BACKGROU~D ART
Abrasive-filled nylon filaments were developed in the late 1950's as a man made al~ernative to natural abrasive filaments. At about that time an exlrusion process was developed for dispersing abrasive particles uniformly in a1~ nylon:matrix in the ~orm of a filament (U.S. Pat. Nos. 3,522,342 and

3,947,169). A re~iew of nylon abrasive filaments is presented by YVatts, J.H., "Abrasive Monofilaments^Cri~ical Factors that Affe~t Brush Tool PerfonnanceH, Society of Manufacturing Engineers Technical Paper, 1988, a written version of a preseneation by the author at ~he WESTEC Conference, held March 21-24, 20 1988. As expl~e~ by Waets, as filaments of this ~pe wear, new abrasive par~cles are exposed. An a~rasive filament brush tool made using a plu~
of these filaments is thus regenerated during use. Some of ~;he advan~es of nylon abrasive filaments are their safe~, cleanliness, cut~ng speed~ low cost, superior radius and finish control, ad~peabili~, and ease in design.
A key property of nylon and other thermoplastic materials is its "memory". In a brush filament this is referred to in the art as ~bend ~ecovery", or the tendency for a deflected filament to return to its original deployment. Ihe bend recovery for nylon is generally over ~%, i.e., the filament returns to about 90% of its original deployment af~er being deflec~ed.
Over time in operation, such as in a brush tool, most ~brasive-filled polymenc filaments will take a set shape, and unless the filaments of the brush 2~833 W093/18~91 - 2 - Pcr/US93/012 tool recover, the brush tool becomes soft and loses its effectiveness. Bend recovery is determined by filament diameter, relaxation time, strain, deflectiontime, and environmental conditions. Among synthetic filaments made to da~, nylon offers the best bend recovery from strain held for an extended period of S time.
While adequate for many purposes9 the inventors herein have found that the various abrasive-filled nylon filaments have property limitations which maketheir use less than optimal as abrasive filarnents. Abrasive-filled nylon filaments have limited stiffness and may lose their stiffness as filament 10 temperature approaches 70C, and thus may not be suitable for removing heavy --scale or burrs when elevated filament temperatures are developed. Temperature resistance is critical in maintaining fdament stiffness. Elevated temperatures generally affect all abrasive-filled nylon filaments in a similar way: stiffness, as measured by the bending (tangent) modulus, decreases as temperature increases.
~ ~ 15 Heat generation is normally not a problem in long filament deburring whcre - ~ brush tool speeds are low. However, in short trim power brushes, tool pressurc on the part and/or high s~peed in a dry environment can gene~ate high tcmperatures at ~e filamcnt tips.
- ~ Another limitation of abrasive-filled nylon filaments is ~at moisture 20 from any source can have a noticeable affect on brush t~ol performance of brush tools incorporating ~em. Moisture affects filament stiffness and thereby tool aggressiveness. Nylon 6,12 retains stiffiless better ~an other nylon m~terials and is 2-3 times st;ffer than other types of nylon in high humidi~ or when saturated with oils, solvents or when water is present.
In most abrasive-filled polymeric filaments, as the degree of abrasive loading increases, the tensile strength and flex fatigue resistance tend to decrease, due to insufficient binding of abrasive and polymer. Bending modulus for a filament can be simply defined as the resistance to bending. This is an inherent characteristic of the polymer used for the abrasive filament.
30 Bending modulus is gene~ally independent of the filament diameter, and since ; the bending modulus of a family of ablasive filaments made from the same , ~ :

~ WO 93/18891 2 1 2 ~ 8 3 3 PCr/US93/01251 polymer will be the same, the m~un charactenstics which affect filament stiffness are the diarneter and length of the filarnent.
The abrasive cutting ability of abrasive-filled nylon filaments exhibits the - distinct characteristic of cuffing relatively well at the onset of the operation, 5 followed by clear loss of abrasive action within about 1 hour. FIG. 7 shows the degradation in cufflng ability of abrasive-filled nylon filaments, filled with a typical aluminum oxide abrasive, when the filaments are attached to a hub to form a brush and the hub rotated so that the filaments strike a stationary workpiece. FIG. 7 represents the cut obtained on a cold rolled steel (1018) 10 plate as a function of bme at a constant load of 1.36 Kg. Equipment is -typically designed to reverse the brush operation to restore the abrasive action to its oridnal level of activity. An abrupt increase in cut can be achieved if the brush is~dressed", for example, by operaiing the brush against a wire screen.
This is shown at 2 hours 15 minutes in FIG. 7.
Ailothe~r problem associated with ab~asive-filled nylon filaments is ~eir ~- poor~fla~fatigue rcsistance. Over extended pe~iods of operation the f~aments - ~ tend t~-~`brGilc near the point of attachment to the hub, an inconvenience to the user, resultulg in dec eased life an~d economic valw of the brush.
~Tt~e~present invention addresses some of the problems mentioned above 20 with abrasive-filled nylon and other filari ents by presentine an abrasive filament .
- ~ ~ compnsing a thetrnoplastic elastomer having abrasive panicles dis~ersed and adhe~ ~erein.
Abrasive filament embodiments within the invention having first and second components, as described in greater detail below, may ha~re ab~asive 25 particles in one or more elongate filamen~ componen~s. These abrasive filaments are to be distinguished stlucturally from composite abrasive filaments' ' comprising ai "preformed" core at least partially coated with a coating of abrasive-filled the~noplastic elastomer. In the latter, the preformed core and coating have markedly different mechanical properties, such as tensile strength.30 Tensile strength may be significantly higher in composite abrasive filaments due to the~ tensile~ strength of the prefonned eore.

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Experimentation with and production of abrasive filaments has a long history. Representative of the state of the art are U.S. Pat. Nos. 2,328,998;
2,643,945; 2,793,478; 2,920,947; 3,146,560; 3,260,582; 3,522,342;
3,547,608; 4,172,440 4,507,361; 4,627,950; 4,585,464; 4,866,888; 5,068,142;
5 and 5,082,720.
Other patents of interest include U.S. Pat. Nos. 2,643,94S; 3,669,850;
3,696,563; 3,8S4,898; a~id 4,097,246, as well as Prench patent application No.
2,6i4,773, and European Patent Application 0282,243.
It shoul'd be clear at this point that Applicant does not contend that he 10 has been the first to incolyo~e abrasive grains into a plastic or resinous filament. It should also be clear that there is a distinction between a core-sheath arrangement and a preformed core coated with a plastic material filled with abrasive grains. The present invention is concerned with abrasive filaments comprising at least one elongate filamen't component cornprising 15 abrasive-filled thntoplastic elastom compositions, which have the une%pected p~ of exhibiting much higher abrasion efficiency (weight of workpiece removd per weigbt of filament lost) and many times the flex fatigue life compared to previously known abla~ive ~ilaments. Much higher levels of abrasive action were observed than would have been expected.
Thermoplastic dastomers are defined and revicwed in 'rhermoelastic Elastomers. ComDreh~nsive Review, edited by N.R. Legge, G. Holden and H.E. Schroeder, Hanser PuUishers, New York, 1987 (referred to herein as ~Legge et al.". Therrnoplastic elastomers (as defined by Legge et al. and used herein) are generally ~e reaction product of a low equivalent weight 25 polyfunctional monomer and a high equivalent weight piolyfunctional monomer, wherein the low equivalent weight polyfunctional monomer is capable on polymerizadon of forming hard a segment (and, in conjunction with other hard ~' segments, crystalline hard regions or domains) and the high equivalent weight polyfunctional monomer is capable on polymerization of producing soft, fle~ible 30 chains connecting the hard regions or dbmains. This type of material has not ~ been suggested for use in abrasive filaments.

: ' 212~83S3 -~ wo 93/18891 Pcr/us93/ol2sl "Thermoplas~ic elastomers" differ from ~thermoplastics" and "elastomers" (a generic term for substances emulating natural rubber in that they stretch under tension, have a high tensile strength, retract rapidly, and substantially recover their original dimensions) in that thermoplastic elastomers, 5 upon heating above the melting temperature of the hard regions, form a homogeneous melt which can be processed by thermoplastic techniques (unlike elastomers), such as injection molding, extrusion, blow molding, and the lilce.
Subsequent cooling leads again to segregation of hard and soft regions resultingin a material having elastomeric properties, however, which does not occur lO with thermoplastics.
Comme cially available thermoplastic elastomers include segmented polyester thermoplastic elastomers, segmented polyurethane thermoplastic elastomers, segmented polyamide thermoplastic elastomers, blends of thermoplasdc elastomers and thermoplastic polymers, and ionomeric ~~ l5 thermoplasdc elastomels.
- ~ "Segmented thmr~lastic dastomer"; as used herein, refers to the sub-chss of th oplaslic elasioms which are based on polymers which are the reac~n product of a high oquivalent weight polyfunctional monomer and a low equhalent weight polyfunctional monomer.
"Ionomeric dlermophstic elastomers~ refers to a su~class of thermoplastic dastomers based on ionic polymers (ionome~s). Ionomeric_ therm~plastic elastomers are composed of two or more flexible polymeric chains bound together at a plu~lity of positions by ionic associations or clusters. The ionomers are typically prepared by copolymerizatio~ of a 25 functionalized monomer with an olefinic unsaturated monomer, or direct functionalization of a~preformed polymer. Carboxyl-functionali~ed ionomas are obtained by direct copolymerization of acrylic or methacrylic acid with ethylene, styrene and similar comonomers by free-radical copolymerization.
- The resulting copolymer is generally available as the free acid, which can be 30 neutralized to thc degree desired with metal hydroxides, metal acetatest and similar salts.

;, ~ ' .
~' 2~ PCI/US93/012~
- 6 - ;. ;
The benefits of thermoplastic elastomers, inc!uding ease of processability combined with hard rubber characteristics, have given some unexpected abrasive binding and cufflng properties. Filaments made using at least one layer com~onent comprising an abrasive-filled ther~noplas~c elastomer produee S much higher levels of inidal cut, maintain their higher cutting ability once an equilibrium condition has been achieved, and exhibit much higher fle~ fatigue than abrasive-filled nylon filaments.

SUMMARY OF THE ~NVENTION
The present invention overcomes or reduces many of the problems ~associated with previously known abrasive filaments. In accardance with the present invendon, a abrasive filament is presented comprising a hardened organic polymeric material comprising a thermoplastic elastomer and abrasive partides adhered therein.
One preferred set of abrasive filament embodiments i~1cludes a hrst elongate filament component having a continuous surface throughout its leng~
and including a first hardened organic polymeric material. In these cmbodiments the abrasive filament furthcr includes a second elongate filament component coterminous with the first dongate filament component, including a 20 seoond hardened organic polymeric material in melt fusion adherent contact wi~h the first elongate filament component along the continuous sur~ace. The second hardened organic polymeric material can be the same or di~ferent than the first hardened organic polymeric mate~ial. At least one of the first and second hardened, organic polymeric materials includes a thermoplastic elastomer 25 having abIasive pardcles adhered therein.
Abrasive f~aments of ~,e invention exhibit improved, life over previously h~,own abrasive-filled nylon, fil,aments. Methods of malàng such abrasive f~,aments, articles including the abrasive filam,ents, an,d methods of abrading surfaces using the abrasive arti,cles are also presented.
As used herein the term, '~hardened" refers to ~,e physical state of the organ,ic polymeric materi~ when Ihe temperature of same is below the melting :

2 ! 2 ~ ~ 33 ~ wo 93/18891 PCI/USs3/012sl ~ - 7 -temperature of thermoplastic polymers used herein, and below melting or dissociation temperature of the hard regions (segmented thermoplastic dasto;ners) or ionic clusters (ionomeric thermoplastic elastomers), as determined through standard tests such as American Society of Testing S Materials (ASTM) test D2117. The term can also be used describe the room tempe~turc (i.e~ about lO to about 40 C) hardness (Shore D scale) in the case of the thcrmopbsdc ebstomas used herein It is preferred that the room .
temperaturc Shore D durometer hardness of the thermoplastic elastomers used in the invendon:be at:least about 30, more preferably ranging from about 30 to 10 about 90, as detennined by~ ASTM D790. The term "hardenedn is not meant to -include physical and/or chemical treatment of the thermoplastic :~; dastomedablasive: particle mixture to increase its hardness.
As used herein the term ablasive filament" means a structure wherein a hardened o~anic polymen~c ma~erial is at least partially filled with ablasive ; 15 :~ ;In cmbodiments :which ~nclude first and second elongate filament e :~o of the ~cross-sec~onal area of the hardened organic . ~ polymeric ma~ which includes abrasive par~cles to ~e cross-sectional area of:the~remai~ of thc f~amcnt may v~uy over a wide range. If the ab~asive filament of ~e invention has~a core-shea~ structure, ~and if only one~of the core ~- ~ 20: or`shea~ has abtasive par~cles therein, the tatio of cross-sectional areas of that part of ~e F.lam~t having abrasive panicles to that not having abitasive -: particles tanges from about l:l to about 20: l, prefe~ably from about l:l to about lO:1, more preferably from about l:1 to about 4 1, the cross-sections defined by a plane peTpendicular to the ab~asive fil~ment major axis. The 25 cross-sectional area of the sheath to that of the abrasive filament is preferably about 40% or greatcr. Tbe abrasive filaments can be of any length desired, and can of course be tound, oval, square, triangular, rectangular, polygonal, or .
~: multilobal (such as trilobal, tetralobal, and the like~ in cross-section.
. ~ .
Segmented thermoplastic elastomers are preferably the condensation 30 leacbon~ duct~of a~ high equivalent waght polyfunctional monomer ha~nng an :avelagc~functi~al~ of at~least 2 and an equivalent weight of at least about --,.~,. ~;
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wo 93/18x91 Pcr/llS93/012~
2i2~183~ -8- ;
350, and a low equivalent weight polyfunctional monomer having an average functionality of at least about 2 and an equivalent weight of less than about 300.
The high equivalent weight polyfuncdonal monomer is capabk on polymerizadon of forming a soft segmcnt, and the low equivalent weight S polyfunctional monomer is capable on polymerization of forming a hard segment. Segmented thermoplastic elastomers useful in the present invendon include polyester TPEs, polyurethane TPEs, and polyamide TPEs, and silicone elastomer/polyimide block copolymeAc TPEs, with the low and high equivalent weight polyfuncdonal monomers selected appropriately to produce the lO respecdve TPE.
- The segmented TPEs preferably include ~chain extenders", iow molecular weight (typically having an equivalent weight less than 300) compounds having from about 2 to 8 acdve hydrogen functionality, and which are known in the TPE art. P;udcularly preferred exarnples include ethylene 15 ~ dian~ine and l,~bu~anediol.
~ Thermoplastic polymer", or ~TP?? as used berein, has a more }imiting definition than the general definition? which is '?a material which softens and flows upon application of pr~sure and heat.~ It will of course be realized that TPEs me~et the general definition of TP, since TPEs wili also flow upon 20 application of pressure and heat. It is thus necessary to be more specific in the definition of ?'thermoplastic" for the puIposes of this invention.
"Tbermoplastic?', as used herein, means a material which flows upon application of pressure and heat, but which does not possess the elastic properties of an elastomer when below its melting temperature.
Blends of TPE and thermoplastic (I~) materials are also within the invention, allowing even greater flexibility in tailoring mechanical proper~es of the abrasive filaments of the invention.
Another aspect of the invention is an abrasive article comprised of at least one abrasive filament within the invention as above described? preferably 30 mounted to a substrate such as a hub adapted to be rotated at a high rate of revolution .

212~3 ' WO 93/18891 PCltUS93/01251 _ 9 A funher aspect of the invention is a method of making an ab~sive filament of the core-sheath type within the invention as above described, the method including the steps of (a) rendering a first organic polymeric material comprising a 5 thermoplastic elastomer molten and adding abrasive particles thereto;
(b) rendering a second organic polymeric material molten, the second organic polymeric polymer selected from the group consisting of thennoplastic elastomers, thermophstic polymers, and mixtures thereof;
(c) forcing the first a second molten organic materials simultaneously 10 throu~h distinct first and #cond passages: within the same die? the distinct pas~ges ~forang the~ first and second molten organic polymeric materials to - assume~e shape~of first;and s~ond elongate filament components in melt fusion adherent contact along a continuous surface of the first component, thus forming an ~abrasive filament precursor; and 15 ~ ; (d)~ ~ co:oling ~e-~abr;~ve filunent precursor to a temper~re sufficient to ihc~first and~ #cond molten~organic~polymeric materials and thus form ~e abhsiw filament.
~ ~ ~P efened ~are methods wherein ~e TPE of thç first (and second, if a TPE is~employed) romponent is segmented and wherein an extruder is used to -20~ ~render the~first and second organic polymeric materials molten. As used herein t he t~m ~"molten" means the organic polymeric materials are heated to a tcmpature at least above the melting temperature of the soft segment for TPEs, more preferably ab~ve the dissociation temperature of ~e hard regions or ionic clusters of the TPEs, or above the mel~ng temperature of TPs.
RIEF DE~SCRI~ON OF 'rHE DRAWING
; ~ FIGs. 1-5 each show an enlarged perspective view of one of five core-- ~ sheath embodiments of abrasive filaments within the invention, each having a portion of its sheath removed to show the core;
FIG~ 6 shows~a~perspec:bw view of one embodiment of a brush tool (in this case~a ~y~bmsh tool)~mcorpolating abrasive filaments of the invention;

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212 ~3;~ ' FIG. 7 is a bar graph which reveals the weight in grams removed from a workpiece (also referred to in the art as "cutn) as a function of time for a rotating brush tool having a pluraliq of pnor art abrasive-filled nylon filaments;
FIG. 8 is a perspective view of a filament extrusion die used to produce S core-sheath abrasive filament embodiments within the invention;
FIG. 9 is a plan view of the die shown in ~:IG. 8; and FIG. 10 is a cross-section of the die shown in FIGs. 8 and 9, taken along the lineD~l~.OE PREFERRBD EMBODlMENTS
Core-Sheath Abrasive P;lament Emb~iments Five core-sheath embodiments 10, 20, 30, 40, and 50 of abrasive - filarnents in accordance with the present invention are illushated in enlarged pe~re views in FIGs. 1-5, where in each embodiment it will be appreciated that a portion of the sheath has been removed to show the respec~ve cores. It will also be appleaated that the core or sheath (or both) - 15 containing the abrasive par~cles may have only a section or portion of the core -~ or shQth so fiL~ed.
Refring now to FIG. 1, an ~abrasive filament 10 has a first elongate filament component in the form of core~ 12, including a TPE 14 and abrasive rticles 16. The TPE 14 of the dongate filament component core 12 has 20 di~ throughout and adhered thein a plurality of ab~asive particles 16, such as aluminum o~ide or silicon carbide abrasive particles.
IG. 2 illust~ates an altemate abrasive filasnent embodiment 20, wherein ~lhe fisst elonga~e filamen~ component is in the form of a core 12a, formed froma first TPE 14a, and the sheath is formed of from a second TPE 18a and 25 abrasi~e particles 16ao In this embodiment, only the sheath includes abrasive particles.
FIG 3 illustrates another core-sheath abrasive filament embodiment 30 having a first TPE 14b and a second TPE 18b, and wherein both core and sheath include abrasive particles 16a and 17, respectively. Abrasive par~cles 30 16a and 17 may of course be ~he same or different in terms of type, particle size,~pasticle size dis~ibution, 8nd dis~ibution within the core and sheath.

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~12~833 --~ WO93/18891 PCl'/I~'S93/U1251 FIGs. 4 and 5 represent core-sheath abrasive filament embodiments 40 and 50, respecdvely, employing two different TPEs, or a TPE and a TPE/TP
blend, as the first and second components. The filament of embodiment 40 includes a first TPE 14c and abrasive particles 16c in the core component 12c S with a second TPE or TPErrP blend as sheath component 18c. The embodiment ~0 of FIG. S is the reverse of embodiment 40, with core 12d formed of a TPE or TPE/TP blend 14d, and sheath comprising a second TPE
18d and abrasive particles 16d.
Core diarneters, for abrasive filaments of the present invention which 10 are core-sheath:structures, for abrasive filaments used in typical hand-held - tools, are preW at least about 0.1 mm, while the ab~asive filaments themselves :pre ably :have a diameter ranging from about 1.0 mm to about 2.0 mm.
Abrasive filaments~of ~e invention having a diameter ranging frorn - : ~15 about ln :mm~ to about 2.0 mm bave an ultimate breal~ng force (measured using;à standard tensile tester known under the trade designation "Sintech~, according to ~e test described in Test Methods) of at least about 0.5 kg (un~nsilized), preferably at least about 1.0 kg (untensilized);: a 5096 fatigue failure: resistance of at least about 15~ minutes (according to the test described in , ~
20~ Test Me~hods); and an abrading efficiency (weight of workpiece removed per waght of filament lost) on cold rolled steel (1018) plate of at least about 2. As may be seen by ~e examples herein below, balancing these preferences may be workI)iece dependent.
The~moplasdc Elastomers : 25 ~ Segmented TPEs useful in the abrasive filaments the present invention generally and preferably comprise the reaction product of a high equivalent weight polyfunctional monomer ha~ring a func~onality of at le~st about 2 and an equivalent weight of at least about 350 adapted to form a soft segment upon ~: polymerization, and a reladvely low equivalent weight polyfunctional monomer 30 having~ a~funcdonality of ~at :most about 2 and an equivalent weight of at most about~ 300,: adapted to form~ a hard ~segment upon polymerization.
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wo 93/18891 PCl/US93/012 Chain extenders are typically used in segmented thermoplastic elastomers to increase the hard segment and hard domain size and thus provide one mechanism to alter the physical properties of the resultant segmented TPE.
Chain extenders useful in the segmented TPEs of the present inven~on S preferably have an active hydrogen funcdonality of ranging from about 2 to 8, preferably from about 2 to 4, and more preferably from about 2 to 3, and an equivalent weight less than about 300, more preferably less than about 200.
Well suited chain extenders are the linear glycols such as ethylene glycol, 1,4-butanediol, l,~hexanediol, and hydroquinone bis(2-hydroxyethyl) ether.
Segmented TPEs us~eful in the abrasive filaments of the present invention -preferably comprise segmented polyester TPEs, segmented polyurethane lPEs, and egmented ~polyamide TPEs. The low and high equivalent weight polyfunctional monomers are variously chosen to produce one of the above segmented TPEs. For e~am~le, if the TPE comprises a segmented polyester, -~ ~ 15~ such~as the segmented ~copoly(etherester)s, the low and hi8h equivalent weight ., ~
polyhlncli nal monomers are preferably poly(tetramethylene terephthalate) and poly(te~amethylene oxide), respectively. If the TPE comprises a segmented polyure~ane, the low equivalent weight polyfi~nctional monomer is preferably a - polyfbnctional isocyanate and the high equivalent weight polyfunctional 20 monomer is preferably a polyfunctional amine.
The weight percent of low equivalent weight polyfunctional mono~lner in ~e total weight of monomers which react to produce s~gmented TPEs preferably ranges from about 20 to about 60 percent, more preferably ranging from about 20 to about 40 percen~.
lonomers useful in forming ionomeric TPEs typically and preferably comprise the reaction product of a functionalized monomer with an olefinic unsaturated monomer, or comprise a polyfunc~donalized preformed polymer.
Within the terms "ionomeric TPEs" and "ionomers" are included anionomers, cationomers, and zwitterionomers.
- -~ 30 I~Es ~(segmented and ionomeric) useful in abrasive filaments of the , ~
invén~on preferably have Shore D durometer hardness values ranging from ~,,;

, "
,'',`-~: ' --~ WO 93/18~91 PCT/US93/012s about 30 to about 90, more preferably ranging from about 50 to about 80.
The mechanical properties of segmented thermoplastic elastomers (such as tensile strength and elongation at break) are dependent upon several factors.The proportion of the hard segments in the polymers which form the TPEs, 5 their chemical composition, their molecular weight distribution, the method ofpreparation, and the thermal history of the TPE all affect the degree of hard domain forrnation. Increasing the proportion of the low equivalent weight polyfunctional monomer tends to increase the hardness and the modulus of the resultant TPE while decreasing the ultimate elongation.
The upper use temperature of segmented TPEs is dependent upon the ~softening or meldng point of *e low equivalent weight polyfunctional monomer comprising the hard segments. For long term aging, the stability of the high equivalent weight polyfunctional monomer comprising the soft segment is also important. At elevated temperatures and with a lower percentage of hard 15 segments which can contribute to hard domains, bending modulus and tensile strength of the TPE are generally reduced.
Prefared TPEs having the above properties and useful in the invention include those formed from segmented polyesters represented by general formula I

zo~C~3c_o--~czz )~--o~c--o~ ~CYz 3--o~

and mixtures thereof wherein:
d and e are integers each ~anging from about 2 to about 6, and wherein d and e may be the same or different, but not differing by more than l integer; and x and y are integers selected so that the resulting segmented polyester TPE has a Shore D durometer hardness ranging from about 30 to about 90.

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Total molecular weight (number average) of segmented polyesters within general formula I ranges from about 20,000 to about 30,000; x ranges from about llO to about 125; and y ranges from about 30 to about llS, more preferably from about 5 to about 70.
S Preferred ionomers used to form ionomenc TPEs useful in the invention comprise the copolymenzation reaction product of a functionalized monomer and an olefinic unsaturated monomer, the ionomers being represented by general formula II

Rl I

- R~CH2 CHz) ~CH21~R3 ~II) D I~

,-~ 10 and n~i~ctures thereof wherein:
Rl, R~, and R3 which may be ~e same or different and are selected from the group consis~ng of hydrogen, alkyl, subsdtuted cyl, aryl, and substituted aryl;
m and n are integers which may be ~e same or diffe,rent ,which are selected so that ~e weight percentage of the functionalized monomer ranges from about 3 to about 25 weight percent of the total ionomer weight and so that the resul~ng ionomeAc TPE has a Shore D durometer ranging from about 3û to about 90;
D is a func~onal group selected from ~e group consisting of COO and SO3,; and M is selecte~ from the group consisting of Na, Zn, K, Li, Mg, Sr, and Pb.
Particularly preferred are those ionomers represented by general formula II
25 wherein Rl = R2 = R3 = CH3 and D = COO. A particularly preferred 2 1 2 4 ~ 3 3 --~ W093/18891 Pcr/~S93/01251 - 15 - ' ionomer is when Rl = CH3, D = COO, and M = Na, such an ionomer being commercially available, for example that known under the trade designation "Surl~n 85SO" (du Pont).
The values of m and n are normally not given by manufacturers but are S selected to provide the resulting ionomeric TPE with a room temperature Shore D durometer ranging from about 30 to about 90. Alternatively, m and n may be characterized as providing the molten ionomeric TE'E with a flow rate (formerly termed "mdt index" in the art) ranging from about lgmllO mins to about 10 gmsllO mins (as per ASTM test D1238-86, condition 190/2.16, 10 formerly D1238-79, condition E). Briefly, the test involves placing a sample -within the bore of a ver~cal, _ cyDnder which is fitted with an orifice at the bottom of the bore. A weighted piston is then placed within the cylinder bore, and the amount in grams of molten polymer exiting the cylinder through th~e odfice is recordeo in grams ~for a 10 minute period.
-~ 15Tbe functionalized monomer may be selected from ac~ylic acid, methaayDc acid, ~inyl acelate, and the like, and copolymers thereof, with yDc and rnedlacrylic acid panicularly preferred.
The olefinic monomer may be selected from ethylene, propylene, butadiene, styrene, and the iike, and copolymas thereof, with ethylene being 20 the olofinic monomer of choice due to its aYailability and relatively low cost.
The functionalized monomer and olefinic monomer are typically and ; ~ ~ preferable directly co~olymerized using free radiG~ls, such methods being well known in ~e ar~ and needing no filrther explana~on herein.
Particularly prefer~ed segmented polyamides useful in making segmented 25 polyamide ~Es useful in the invention are those segmented polyamides represented by general fonnula m !-` i I i , ' O O
11 ~I
HO- C--PA--C--O--PE--O----H ( II
: ~ Z

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WO 93/18~91 PCl`~US93/ûl~
2124~33 - 16-and mixtures thereof, wherein:
PA = a difunctional polyamide having equivalent weight less than about 300;
PE = a dihydroxypolyether block having equivalent weight of at least 3SO and comprising polymers selected from the group consisting of dihydr~xypolyoxye~ylene, dihydroxypolyoxypropylene, and dihydro~ypolyoxytetramethylene; and z = an integer selected to provide the resulting segmented polyamide TPE with a Shore D durometer hardness I-allgMg from about 30 to about 90.
Segmented polyamides within fonnula m are commercially available, such as those known under the ~rade designation "Pebax", available from Atochem Group of Elf Aqui~aine, with the 63 and 70 Shore D durometer`
1.~ versions being particularly prefe~red in the present invention.
Although values of z are proprietary to the manufacturers, and polymers wi~ general formula III may be cha~acterized according t~ hardness, they may alternatively be chara~terized according to their melt flow r~te (as described abov~), with values ~nging from about 1 gm/10 min to about 10 20 gm/10 mîn being prefer~ed (ASTM 1238-86, 19012.16).
Particularly preferred segmented polyuretllanes useful in mal~ing polyurethane TPEs useful in the Lnven~on are ~ose segmented polyuretha3les represented by general formula I~

212~83:~
~ WO 93/1XXgl - 17 - Pcr/US93/01251 ~0 ~ C~N~3C~N--C--o~C~12 )--O--C1--2 t IV) --N ~ C H~ N--C--O--~ p o l y o l ) ~ O E~

and n~ixtures thereof wherein:
polyol--a polyester polyol or polyether polyol having an average molecular w~ight ranging from about 600 to about 4000;
S and t = an integer selected to provide the resulting segmented polyurethane 'rPE with a Shore D durometer hardness ~nging from about 30 to about 90.
The value of ~t" is chosen relative to the molecular weigbt of the polyol 10 to give a ~ge of molecular weights; typically and preferably, ~e number average molecula~ weigh~ of segmented polyurethanes represented by general formula IV ~anges from about 35,000 to about 45,000.
ln general, segmented polyurethanes may be made by n~ixing the ISrst and sec~nd polyfune~onal monomers as~d chain e~tender together at 15 tempcratures above about 80 C. P~eferably, the ra~o of isocyana~e func~onal groups ~o isoeyanate rea~tive groups ~anges fr~m about 0.96 to about 1.1.
Values below about 0.96 result in polymers of insufficient molecular weight, while above about 1.1 theranoplas~c processing b~mes di~ficult due to excessive crossli~g reac~ons.
As men~oned previously, blends of TPEs and other polymers have also proven useful, such as the polyurethane/acryloni~rile-butadiene styrene blends known under the hade designation "Prevail", grades 3050, 3100, and 3150, all 2~ 2 ~8~ 18- Pcr/usg3/ol2~
from Dow Chemical. Grade 3050 has a melt flow rate (ASTM-1238-86, 230/2.16) of 26 gm/10 min, and a Shore D hardness of about 62.
Block copolymers regarded by those skilled in the plastics processing art as TPEs, including the elastomeric copolymers of silicones and polyimides, 5 may also prove useful in abrasive filaments of the invention. CommerciaUy available elastomeric copolymers of thermoplastic silicones and polyimides include those known under the trade designation "Siltem STM-1500", from GE
Silicones.
Each of the polymers within formulas I-IV as shown above are now 10 discussed in greater detail.
.
Se~mented Polyesters As noted above, if the TPE is based on a segmented polyester, such as the segmented copoly(etherester) as shown in formula I, the low and high 15 equuvalent weight polyfunctional monomers are preferably based on poly(tetramethylene terephthalate) which forms the hard segment upon poJymenzaoon and poly(tetrame~ylene oxide) which forms the soft segment upon polymerizadon, respectively. The poly(ether) component of the copoly(etherester) is prefera~ly derived from a-hydro-~
20 hydroxyoligo(tetra nethylene oxide) of number average molecular weight~anging from about 1,000 to about 2,000. The copoly(ester) component of the co~oly(etherester) is preferably based on poly(tetramethylene terephthalate) which fonns hard segments upon polymerization, having average molecular weights ranging from about 600 to about 3,000. The molecular weight for 25 copoly(etherester) polyesters within formula I pre~erably ~anges from about 20,000 to about 40,000.

Ionomers Ionomers whieh may behave as ionomeric TPEs and thus useful in the 30 present invention, such as those ionomers known under *e trade designation "SURLYN" (formula II), are preferably prepared by copolymerization of a 2 12~1g33 -" WO93/18X91 PCl`/US93/01251 . - 19-functionalized monomer and an olefinic unsaturated monomer, or by direct funcdonalizadon of a preformed polymer, as previously noted. Ionomers within formula II are particularly preferred for forming ionomeric TPEs for use in hardened composidons in abrasive filaments of the invendon. The large 5 quanddes of commercial quality ethylene/methacrylic acid copolymas, for example containing between about S and about 20 weight percent methacrylic acid component, makes these ionomers particularly useful in the present invendon.
M in formula II is typically and preferably chosen from sodium (Na) 10 and zinc (Zn), although ionomers using potassium (K), lithium (Li), magnesium 4~g), strondum (Sr) and lead (Pb) are considered within the scope of formula II.

Se~mented Polyamides Polyamides withiti formula m and useful forming segmented polyamide fv~ TPEs~ for use in the invendon are typically descdbed as polyether block amides (or ~PEB~"), wbein the latter may be obtained by the molten state polycondensation rescdon of dihydro~ypolyether blocks and dicarbo1cylic acid-based polyamide blocks as shown in formula m (wherein PA represer~ts 20 "polyamide" and PE represents "polyether"). Dicarboxylic polyamideblocks may be produced by the reaction of polyamide precursors with a dicarbo~ylic acid chain limiter. The reaction is preferably carried out at high temperature (preferably higher than 230C) and preferably under pressure (up to 2.5 MPa).
The molecular weight of ~e polyamide block is typically controlled by the 2S amount of chain limiter.
The polyamide precursor can be selected from amino acids such as aminoundecanoic ac d and aminododecanoic acid; lactams, such as caprolactam, ~ ~ lauryl lactam, and the like); dicarboxcylic acids (such as adipic acid, azelaic - ~ - acid, dodecanoic acid, and tbe Dke); and diamines (such as hexamethylene ~; 30 diaminè, dodecamethylene diamine, and the like).
, ., .,,., :

wo 93/18X91 PCr/USs3/012~q - 20 - `;
2 l 2 ~ 8 3 3 The dihydroxypolyether blocks may be produced from polyether precursors by either of two different reactions: an ionic polymerizadon of ethylene oxide and propylene oxide to form dihydroxypolyoxyethylene and dihydroxypolyoxypropylene polyether precursors; and cationic polymerization S of tetrahydrofuran for producing dihydro~cypolyo~cytetramethylene polyether precursors.
The polyether block amides are then produced by block copolymenzation of the polyamide precursors and dihydroxypolyether precursors. The block copolymerizadon is a polyesterificadon, typically l0 achieved at high temperature (preferably ranging from 230 to 280C) under -vacuum (l0 to 1,400 Pa) and the use of an appropriate catalyst such as Ti(OR)4, where R is a short chain alkyl. It is also generally necessary to introduce additives such as an antioxidant and/or opdcal brighteners during polymeIizadon.
~; 15 ;The~struc~re of the resulting polyether block amides comprises linear, chains of rigid polyamide segments and flexible polyether segments.
Sincc-polyan~ide and polyether segments are not miscible polyether bloclc amides such as those represented by formula m present a "biphasic" structure wherein each segment offers its own properdes to the polymer.
SeQmented Polvurethanes Segmented polyurethane I PEs useful in the present invention are prefe~bly fo~ned ~rom segmented polyurethanes within formula IV, which are compns~d of a high equivalent weight polyfunctional monomer and a low 25 equivalent weight polyfunctional monomer as above desc~ibed, and may also include a low molecular weight chain extender, also as above described. In thermoplastic polyurethane elastomers, the hard segment is formed by addition of the chain extender, for example, 1 ,4-butane diol, to a diisocyanate, for e~cample, 4,4'~iphenylmethane diisocyante (~I). Ihe soft segment consists 30 of long, fle~ible polyether or polyester polymeric chains which connect two or : more~hard: segments. At room temperatu~e, the low melting soft segments are .

2~æ~ ~,33 wo 93/l 889l Pcr/uss3/ol 251 -- 21 -- !
incompatible with the polar, high melting hard segments, which leads to a microphase separation.
Polyurethanes useful in forming segmented polyurethane TPEs are generally made from long chain polyols having an average molecular weight S ranging from about 600 to 4,000 (high equivalent weight polyfunctional monomer), chain extenders with a molecular weight ranging from about 60 to about 400, and polyisocyanates (low equivalent weight polyfunctional monomer). Preferred long chain polyols are the hydroxyl terminated polyesters and the hydroxyl terminated polyethers.
A preferred hydroxyl terminated polyester is made from adipic acid and an excess of a glycol such as ethylene glycol, 1,4-butanediol, 1,~hexanediol, neopentyl glycol, or mixtures of these diols.
Long chain polyether polyols useful in making polyurethanes within formula IV useful in making segmented polyurethane TPEs useful in abrasive 15 filamen~ of the invention are preferably of two classes: the poly(o%ypropylene)glycols and the poly(oxytetramethylene)glycols. The former glycoIs may be made by the base catalyzed addition of propylene oxide and/or ethylene o~cide to bifunctional initiators, for example, propylene glycol or water, while the latter may be made by cationic polymenzation of 20 tet~ahydrofu~an. Both of these classes of polye~ers have a functionali~ of about 2. Ihe ~ed polyethers of tetrahydrofuran and e~ylene or propxlene oxide may also be effectively used as the so~t segment in the polyurethane TPE.
In con~ast to other polyurethanes, only a few polyisocyanates are suitable for producing thennoplastic elastomer polyuredlanes. The most useful 25 preferred polyisocyanate is MDI, mentioned above. Others include he~amethylene diisocyanate (HDI), l-lsocyanat~3-isocyanatomethyl-3,5,5-trime~ylcyclohexane (IPDI); 2,4 and 2,6-toluene diisocyanate ~rDn; 1,4 ben~ene diisocyanate, and trans-cyclohexane-1,4-diisocyanate.

'' WO 93/18~91 PCl`JUS93/012~
2 1 2 ~1 8 3~ - 22 - ` `' Abrasive Particles Abrasive particles are preferably dispersed throughout and adhered within the hardened TPE coating. Abrasive particles useful in the abrasive fillaments of the present invention may be individual abrasive grains or 5 agglomerates of individual abrasive particles. Suitable agglomerated abrasive particles are described in U.S. Pat. Nos. 4,652,275 and 4,799,939. The abrasive particles may be of any known abrasive material commonly used in the abrasives art. Preferably, the abrasive particles h~ve a hardness of greater ithan about 7 Mohs, most preferably greater than about 9 Mohs. Examples of 10 suitable abrasive particles include individual silicon carbide abrasive particles ~including ref~y coa~ed silicon carbide abrasive particles), fused aluminum o~ude, heat Uealed fused aluminum o~ido, alumina zirconia, cubic boron nitride, garnet, pumice, sand, emery, mica, corundum, quar~, diamond, boron carbide, fused alun~ina, sintered alumina, alpha alumina-based ceramic material.- ~ ~ 15TSle ab~sive particles are preferably present at a weight percent (of filament component(s) containing the ablasive particles) ranging from about 0.1 to about 60, more prefeIably ranging from about 25 to about 50.
In order to ~chieve the highcr abrasive particle loadings it may be - ne~ssary, depending on the TPE~ and or TP employed, to coat the abrasive 20 par cles with a coupling agent prior to introduction into the polymer melt.
Alt~natively, ~e coupling agent is added to the polymer melt in the form of a pellet containing from about 10 to about 30 weight percent coupling agent, and from about 70 to 90 weight percent of a TPE.
Coupling agents found useful and thus preferred for use in this invention 25 are the neopentyl(diallyl~oxy titanates, such as neopen~yl(diallyl)o%y,tri(m-amino)phenyl titanate and neopentyl(diallyl)oxy,tri(dioctyl)phosphato titanate.
! ~ ' The size of the abrasive particles incoIporated into the abrasive filaments of the invention depends on the intended use of the filaments. For applications requiring cutting or rough finishing, larger abrasive par~cles are preferred, 30 while abrasive partides having smaller size are preferred for finishing applicat ons. Preferably, the average diameter of the abrasive particles is no , ~, .
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more than about 112 the diameter of the abrasive filament, more preferably no more than about l/3 of the diameter of the abrasive filament.

Abrasive Ar~cles Abrasive filaments of the invention may be incorporated into a wide variety of bNshes, dther clumped together to form an open, lofty abrasive pad, or attached to various substrates.
FIG. 6 shows one embodiment of a wheel brush 60 within the invention having a plurality of abrasive filaments 61 glued or otherwise attached to a 10 polymeric hub 62, such me*ods of atta:hment being well Imown in the art.
In the Examples below, a metal hub was employed, the construction of which is explained under the heading "Test Brush Constructionn.
In order to make a ~olymeric hub, a mold is typically fabricated so that abr~ve f~s can be employed in the form of abrasive bNshes as sl~own - ~ 15 FI~ 6 of this invenbon. A round base plate is fabricated with a 3.18 cm diameter~ center through hole which is adapted to accept a solid, cylindrical core pi~ece ha~ing outer diameter slightly less than 3.18 cm. Slots are machined intoone surl~ce of the base plate to create a radial pattan so ~at ~in metal spacerscan be~inserted therein. The slots extend radially, star~ng from a point about S20 cm fr~m ~e center through hole and éxtending to the periphery of the plate. Aright cylinder aoo mm I.D.) may then be fastened to the sur~ace of the base ~ .
plate having ~e slots so that the hole in the base plate and the cylinder are concentric.
The spacers may then be put in the slots, the solid, cylindrical core 25 piece inserted in ~he through hole, and a multiplici~h,r of abra~ive filaments having length equal to the slot length plus about 5 cm aligned within the spaceslef~ benveen'the spacers. The spacers provide a nnethod to unifornlly and closely distribute the abrasive filaments radially with a predetermined length.
The abrasive filaments can then be held firrnly with a clamp Iing, which fits ~- 30 over the end~of the filaments pointing towa~d the center through hole.

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wo 93/18xsl PC~r/US93/Ol?, - 24 -1~ ~ ~ 3 3 A polymeric cast hub is then fonned by pouring a liquid epoxy or other resin into the center cavity formed between the solid, cylindrical center core piece and the clamp ring. One resin found useful in assigneets copending application was the two-part epoxy resin hlown under the trade designation S "DP~20n, from 3M. When the resin is fully cured, the brush may be rem~ved from the device and then tested.
Another method of making abrasive brushes employing the abrasive filaments of the invention is by using a conventional 'tchannel" brushmal~ng machine.
The abrasive filaments of this invention can be inco~porated into brushes ~of many types and for myriad uses, such as cleaning, deburring, radiusing, imparting decorative finishes onto metal, plastic, and glass substrates, and like uses. Brush types include wheel brushes, cylinder brushes (such as printed circuit cleaning brushes), mini-grinder brushes, floor scrubbing brushes, cup 15 brushes, end bmshes, flared cup end brushes, circular flared end cup brushes,coated cup and variable aim end brushes, encapsulated end brushes, pilot bonding brushes, tube brushes of various shapes! coil sp~ing brushes, flue cleaning brushes, chimney and duct brushes, and the like. The filaments in any one brush can of course be the same or different in construction, configuration,20 length, etc.
Two particularly preferred uses of brushes employing filaments of ~e invention are printed circuit board cleaning and s~l plate clganing.

Metho~ of Makin~ ~brasive Fil~ments The following pa~agraphs discuss methods of producing core-sheath abrasive filaments within the invention. Embodiments which comprise a TPE
and abrasive particles adhered therein may be produced using the same equipment, however the ~sheath~ is not added to the filament structure.
Core-sheath abrasive filaments in accordance with the present invention 30 are made by an extrusion process, which includes the use of at least nvo extluders, the outlet of each connected to a die such as that shown perspectively 2124~33 O 93/18X91 Pcr/US93/01251 in FIG. 8. A first molten, organic po1ymeric material, comprising TP~ or TP
and adapted to form one filament component (or blend of TPE and TP) and a second molten organic polymeric material comprising TPE or TP, adapted to form the second elongate filament component, are extruded simultaneously 5 through distinct first and second passages within the same die. The distinct pa~sages force the first and second molten organic polymeric materials to assume the shape of first and second dongate filament components, in m~lt fusion adherent contact along a continuous surface of the first component, as one or more e~ttrudates from the die.
10Abrasive parlicla, along with optional coupling agents, fillers, ~igments, and the like, are added to at least one of the first and second molten organic polymuic malcrials upslream of the die. One or more abrasive filamént precursors are formed from the extrudate(s) by cooling the extrudate(s)(psefably by quenching in a cooling water bath or flowing stream of cooling 15 wat~ to a ICmpelah~re sufficient to harden the first and second molten organic Pb nc ma~ials. The abrasive filament precursors are then typically wound onto sui~able cores by winding machines well lalown in the art, where they are held until cut into individual abrasive filaments.
; ~ In the preferred method in accordance with the invention, a die such as 20 ~at shown in PIGs. 8-10, is attached to the exit of at least two extruders, an extrudcr being one preferred technique of rendering the organic polymeric matenals molten and mixing the abrasive particles therein. For each IPE the zone temperatures of the ex~uder and die temperature are preferably set at the temperatures commercially resommended for each TPE (see Table A), the main 25 lirr~iladon being the mcldng or dissociation temperatl~re of the hard domains or ionic clusters of the TPE. Preferred extruder zone and die temperatures are ' listed in Table A.
Refemng now specifically to FIGs. 8^10, FIG. 8 illustrates in - perspcctivc a dic which may be used to make core-sheath abrasive filaments of 30 the invcndon ac~ing to the abovc ~procedure, while FIG 9 presents a plan iew. An adapler-plate 81 is a~æhed via screws 9la and 9lb to first stage ,. :~;, , ~
,~:

2 1 2 ~;~18X91 - 26 - Pcr/US93/012 plate 82, which is in turn connected to second and third stage plates 83 and 84 via bolts 90a and 90b. A conduit 85 allows molten organic material to flow into the die from a first extruder and through core passages denoted as 87. A
second conduit 86 allows a second molten organic material to flow through S passages 88 and thus form sheaths in extrudates 89. If abrasive filaments of the invention having no sheath are desired, no molten organic material is allowed to cnter the die ~uough conduit 86. -Referring to FIG. lO, plugs 92a and 92b are provided to direct flow of molten organic material into tubing inserts 93a and 93b (FIG. lO). lnserts 93a lO and 93b having a given internal diameter or shape may be easily removed and - ~placed with other insats to control ~e shape and size of the core in core-sheath embodiments. Similarly, inserts 94a and 94b are provided to control the thicbless of the sheath of ~e extrudates which exit the die from exit ports 95a and 95b.
Vari~ons in structural details of dies such as that illustrated may vary.
For~e~ample, more than t~,vo extrudates may be produced from a single die, and a~plu~ality of dies may be employed in a manifold arrangement.

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The abrasive filament precursors can be oriented at draw ratios up to ~bout 5:1 to increase the tensile strength of the resulting abrasive filarnents of the invention; however, as this appears to drastically reduce the abrasion efficiency of the abrasive filaments (see Examples 29, 47, 49, 51, and 53), thisS is not preferred.
After the abrasive filament precursor has hardened it may have an optional coating (e.g. a plastic coating) applied thereover, for aesthetic, storage, or other purposes.
It should further be understood that the abrasive filaments and abrasive 10 particles can contain fillers, lubricants, and grinding aids in levels typically ~sed in the abrasives art.

EXAMPLES
The following examples are given as illustrations of the invention and 15~ are not ilr~ as~Gmita~ons thereof. ~In all examples, all parts and pe~n~ges are by wdght unless othennse stated. "P" refers to heat treated ablas:ive par~cles where used in con~uncdon with an abrasive particle desigr~tion, while the "grade" of abras:ive particles refers to that used by the~Grinding Wheel Institute (ANSI ASC~B74.18-1984). "CRS" refers to "cold 20 r~ stoel", while "a-Al2O3-cer" refers to alpha^alusnina-based ceramic abrasive particles. Worlcpiece removed and total filament weight loss values do not include initial 30 minutes brea~n period.

Test Metbods Fati~ue Failure Resi~ance This test was used to evaluate fatigue failure of abrasive filaments, the results of which can be used to predict relative usable life of a brush made from the abrasive filaments of the invention. The test procedure used was published and described~ in Technical Bulletin No. 6, ~Patigue Resistance and Some of the 30 Fa~s~at Aff~ctFlex~Life of Brush F~g Materials~, February, 1978, by du P~ont, Plas~c Products and Resins Department, Code # E-19743. The test , , ~ , -2 ~ 2~
,~ W093/18891 PCI`/US93/01251 procedure was followed exactly, with the excep~ion that the filarnent holding device on the tester was changed to four chuc~cs, each of which could be adjusted to firmly grasp one abrasive filament. In this test, the four chuc~s were affixed to a drive shaft, each of which was used to secure an individual 5 abrasive filament or control filament. The chucks were mounted 90 apart with each being spaced 50 mm from the center of the drive shaft. The drive shaft wæ operated at S00 rpm. As per the test procedure, the interference between the filaments and the impact bar was adjusted, depending upon the filament diameter. For a 1.02 mm diameter filament, the interference was 12.22 mm;
10 for 1.14 mm filament, the interference was 13.21 mm; for a 1.27 mm filament, ~he interference was 16.51; and for a 1.40 mm filament, the interference was adjusted to 18.16 mm. After securing four identical test filaments to the drive shaft, the drive shaft was rotated and the time required to cause 50% of the filaments to break was recorded. This value is reported in Table 7 for 15 ~mples 1-57 and Comparative Examples A-F.

Test Brush Construction Abrasive filaments of the invention were used to form abrasive brushes of ~e invendon by attaching one end of the abrasive filaments to a cast 20 aluminum, machined, tw~part hub.
The first part of the cast aluminum, machined hub consist~d of a S mm ~ick aluminum disc having a 32 mm center hole, a 102 mm outside diameter, and had a raised square cross~ onal surface at ~e penphery that was raised

4 mm.
The second part of the cast aluminum hub was machined from a 19 mm thick cast aluminum disc, also having a 32 mm center hole with a 102 mm outs;de diameter. The second part of the cast alusninum hub was machined to be S mm ~ick, with the exception of three circular raised surfaces on one side of the di~c, each concentric with the center hole: an outer, an intermediate, and 30 an inner circular raised surface, all three raised circ~lar surfaces parallel to the disc major suRaces. The outer circular raised surface had a square cross-wo 93/18Xgl Pcr/US93/012 2 1~ ~ 8 ~ion of 4 mm by 4 mm and an outside edge diameter of 102 mm. Thè ;
htermediate circular raised surface had an outside edge diameter of 73 mm and an inside edge diameter of 68 mm, and was rused 13 mm above the disc major surface.
S The annulus formed by one of the disc major surface and the intermediate raisod surface was machined to produce eight equally sized and spaced bores cactcnding radically through the annulus, each bore being 9 mm in diameter with the spacing between adjacent bores being about 3 mm. These bores defined holes into which abrasive filaments were subsequently placed.
10 Thc inner circular, raised surface had an inside edge diameter of 32 mm which, ~hcn the two hub parts were matd, defined the center hole of the hub. The inner raised surface outer edge had a diameter (measured from the hub center) of 44 mm and~ was r~used 13 mm above the disc major surface.
The inner raised surface and intermediate raised surface of the second 15 hub disc~defined the pla e against which~the fi~st hub part was placed. The square cross sections of the first and second hub parts opposed each o~er.
One end of appro~imately 500 to 2000 abrasive filaments, each about 83 mm k~ng, were placed into each of the eight bores. Sufficient number of 20 fil~nonts were place in each bore to essentially fill each bore. A two-part epmy adhesive liquid resin compssition (combinadon of ~he epoxy "Epi-Rezn WD 510, from Rhone-Poulenc, and the an~ine "Jeffan~ine~ D-230, available from Texaco Chemical Company, Bellaire, Texas) was placed over the filament end which protruded into the bore. The first part of the machined aluminum 25 hub was secured to the second part using four screws, 4 mm in diameter, through ~four holes equally spaced 42 mm from the center of the machined alun~inum hub. This caused the abrasive filaments to slight~y fan out with a - resultant filament tnm length of about 50 mm. After being held for approximately 24 hours at room temperature (about 25C, to allow the epoxy 30 resin t~ harden) the abrasive filament brushes were ready for subsequent -,:
-.~, 2~ 2~?,33 -~ W093~18891 PCliUS93/01251 - 31 -evaluations. The brushes had a 32 mm center hole and approximately 200 mm outside diameter.

Flat Plate Abrasion ~çsts Abrasive filament brushes, fabncated as just described for each of the 57 Example abrasive filaments and CompaIative Examples A-P, w ere weighed and separately mounted on a shaft connected to a 2.24 Kw (3hp) motor which operated at 1750 rpm. 1018CRS steel plates, 100 mm square by approximately 6 mm thick, were weighed and then brought in contact with each brush with a force of 13.3 Pa. At 15 minute intervals, the test brushes and steel pla~es wae again weighed to determine the weight loss of the steel plates and weigbt loss of the test brushes. After 8 test periods (120 minutes) the tes~ were concluded and the total cut (steel plate weight loss) was calculated. This value was divided by 2 to give average gsams cut per hour by each brush. The efficiency 15 (~) of the brushes was calculated by dividing the total plate weight loss by ~e total abrasive filament weight loss. Results are reported in Tables 2-6.

brasive Filam~nt T~nsile Stren Abrasive filaments of the invention were evaluated for their tensile 20 st~ength by measuring the force required to brçak a 100 mm long abrasive filament g~sped at each end by one of two jaws of a standard tensile tester (~mown under the trade designa~on "Sint~ch 2"), where the jaws wele initially spac~d 25 mm apart and then separated at the rate of 50 mm a minute. The ~orce required to break each filament was noted and recorded as ldlograms 2S for~e required, and reported in Table 7.

Abrasive Filament ExtrusiQn 57 abrasive filaments made in accordance with this invention were prep~red by the melt extrusion process. A twin screw e~truder fitted with two 30 30 mm diameter c~rota~ing screws having aIl LtD ratio of 30:1 (model ZSK-30, from Wemer-Pfleiderer), was employed in each case, along with a second wo 93/18891 Pcr/US93/01 single s3cr3ew extruder (from C.W. Brabender, having 1.78 cm diameter barrel, 30: l L/D ratio). The thermoplastic elastomers employed were first rendered molten by the twin screw ex~ruder (using zone and die temperatures in Table A
above for each TPE), whereupon abrasive particles were controllably added S through a feed port of the extruder barrel.
The extrusion die used was similar to that illustrated in FIG. 8-lO, but was equipped to provide 4 extrudates, rather than 2 as shown in tihe figures.
After exiting the extrusion die, the extrudates were cooled by causing the extrudates to pass through a water stream placed about lS0 mm from the e~
10 ports, after which the abrasive filament precursors were wound onto the same windup roll (sq~ste windup rolls could also be used). Abrasive filaments were~ subsequenlly cut from the roll. I~ is import~n~ ~o note that none of the coated filaments produced by the above method required orienting prior to being accumula~d on the roll, subsequent cut~ing into filaments, and fab~ication15 i~ brush~ devices, al~ough some abrasiw filament precursors were oriented at a draw ~ o of 3:1 to comp~ abrasivo performance with undrawn samples.
(A draw ratio of 3: l means the final length was about 3 times the original -leng~.) ~; The TPEs employed~ including some of their physical properties, are 20 listed in~Table l. Tables 2-6 lists TPE, abrasive particle type, size, etc., used in each~E~ample Flam~t, along with abrasion test data. Table 7 lists meshanical properties (force to break, fatigue ~ailure resis~ance) of the control filaments and abrasive filaments of the invention. The abrasive particle contentin each filament was determined by using a standard thermal burnoff technique.
l;our abrasive-filled nylon control filaments A-F were used to compare with ~amples 1-57. The composidon of the control filaments is indicated in the Tables. iComparative E~cample filaments A^D were commercially available (under the trade designadon "TYNEX~) from du Pont. Comparative Example filaments E and F were made by the inventors herein.
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-- wo93/18~91 PCI~l~S93/012sl 1 wt. % abrasive (% of core wt.) was as follows:
E~cample 1 = about 35;
Example 2 = 30;
S E~cample 3 = 45;
Example 4 = 16;
Examples 5-7 = 30;
~xample 8 = 45;
Examples A,B,C, = 30.

Cross-sec~onal area of abrasive component (9~o of total) was as follows:
E~unple 1 about 70-80 %;
E~camples 2,3 80-90 %;
Example 4 70-80 %;
Examples 5-7 70-80 %;
Examplc 8 80-90 %; ~
EJ~amples A-C 100 %. ~;
20 2 This corè included 0.2 wt. % (of core wt.) the coupling agent n~1penqrl(diallyl)c~y,-tri(dioc~l)phosphato titanate - 3 This ~ore included 0.2 wt. ~O (of core wt.) coupling agent n~Myl(diauyl)oxy~i(m-amino)phenyl titanate , ,:

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WO 93/18X91 PCI'/US93/012.fi`?~
- 36- .
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WO g3/l8~sl PCI/US93/01251 ~ 37 wt. % abrasive (% of core weight) was as follows:
E~cample9 = 38;
E~amples 1~12 = 44;
S Examples 13-20 - 35.
% cross-sec~onal area of core to toal aoss-sectional area:
E~ample 9 70-80%
E~camples 10-14 8~90 E~amples 15-16 "
EJumple 17 E~amplc 18 EDple 19 "
EJ~ample 20 "

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: ~, wo 93/18X91 PCr/US93/01 2 12 ~ 8 3 ~ wt. % abrasive in abrasive layer (% of total layer wt.) was as follows:
Examples 21-22 = 35%
Example23 50 S Example24 30 Exarnple 25 40 Exarnples 2~27 30 Examples 28-29 25 E~camplcs 3~32 35 EJcample33 55 Example 34 25 Examplc 35 30 Example 36 25 E~ample 37 30 Example 38 35 - E~cample39 40 EJcamples 40-42 30 E~es 43-45 35 ., ~ '' .~ .

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wO 93/18X91 Pcr/us93/
- 48 - ' 3Discussion of Results 21 ~ ~ 8 EMciency In general, brushes including ab~asive filaments of the invention were more efficient than brushes employing control filaments, with the exception of S Examples 11, 14, 18, 21, 26, 27, 29, 32, 39, 47~9, 51, and 53. The examples not exceeding the highest efficiency achieved for the controls (-7 =
2.46 for control filament D) may be explained as follows.
Brushes including example filaments 11 and 14 used much smaller abrasive particle size than did Control filament D (P180 A12O3 vs. 80 SiC).
The brush including example filament 18, using a polypropylene sheath .with a polyester TPE core including 120 SiC, although not as efficient as control fila nent D, was more efficient than brushes employing control filamentsA-C.
The brushes containing filaments of Example 21 exhibited chipping of 15 the core due to the plesenoe of the polyester TPE "Hytrel 8238". The brush employing Example filaments 26 used 180 grade SiC abrasive pa~icles, which tended to be less aggressive. The brush using Example filaments 27 used a softer grade of polyester TPE ("Hytrel 5526") but still outperformed Control filaments A, B, and C.
Brushes containing Example filaments 29, 47, 49, 51, and 53, all tensi~ at a draw ratio of 3:1, exhibited lower abrasion efficiency.
The brush containing Example filasnent 32 had only 545 filaments.
Similarly, the brush having l~xample filament 39 had the lowest ~nount of filaments of the ~rushes of E~amples 3~39, all other condi~ons ~eing equal.
The brush including Example filaments 48 had about 35% less filaments than control Example D.

Mechanical ProDer~çs Example abrasive filaments of the invention had better fle~c fa~gue resistance thrn the controls (Control C had 16 rninutes for 50 70 failure), e~cept .

... ...
~~wo 93/l889l 49 ~ Pcr/us93/0125 for Examples 9, 13, 14, 18, 21, 23, 33-35, 39, and 41. These Example filaments all had higher abrasive particle loadings than the control filaments.
The force to break was much higher for tensilized filaments (Examples 29, 47, 49, 51, and 53) of the invention, but the efficiency values dropped S significantly for those filaments, so that tensilizing of the filaments is notprcferred if optimum abrasion efficiency is desired. A balance must be struck betwecn tensile strength (forcc to brcalc/filament diameter) and abrasion efficiency, which can be determined without undue e~cperimentation according to thc above teachings.
Various modifications and alterations of this invention will become ~rent to those sl~lled in the art without depar~ng from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limi~d to the illustrated embodiments set for~ herdn.

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Claims (9)

CLAIMS:

Please cancel Claim 1.
1. [1]. An abrasive filament characterized by the features chat the abrasive filament has:
   (a) a first elongate filament component having a continuous surface throughout its length and being a first hardened organic polymeric material; and (b) a second elongate filament component coterminous with said first elongate filament component and being a second hardened organic polymeric material in melt fusion adherent contact with first elongate filament component along said continuous surface, the second hardened organic polymeric material being the same or different than the first hardened organic polymeric material, wherein at least one of the first and second hardened organic polymeric materials is a thermoplastic elastomer having abrasive particles dispersed and adhered therein.
2. [2]. An abrasive filament in accordance with claim 1 further characterized by the feature that said thermoplastic elastomer is selected from the group consisting of segmented thermoplastic elastomers [-] and ionomeric thermoplastic elastomers.
3. [3]. An abrasive filament in accordance with claim 1 further characterized by the feature that the first hardened organic polymeric material includes a coupling agent.
4. Please cancel Claim 5.
5. [5]. An abrasive article characterized by the features that the abrasive filaments have:
   (a) a first elongate filament component having a continuous surface throughout its length and being a first hardened organic polymeric material; and (b) a second elongate filament component coterminous with said first elongate filament component and being a second hardened organic polymeric material in melt fusion adherent contact with first elongate filament component along said continuous surface, the second elongate filament component comprising a second hardened organic polymeric material, the second hardened organic polymeric material being the same or different than the first hardened organic polymeric material, wherein at least one of the first and second hardened organic polymeric materials is a thermoplastic elastomer having abrasive particles adhered therein.
6. [6]. An abrasive article in accordance with claim 5 further characterized by the feature that said thermoplastic elastomer is selected from the group consisting of segmented thermoplastic elastomer [-] and ionomeric thermoplastic elastomers.
7. [7] . A method of making an abrasive filament, the abrasive filament being a first elongate filament component having continuous surface throughout its length and being a first hardened organic polymeric material, and a second elongate filament component coterminous with said first elongate filament component being a second hardened organic polymeric material in melt fusion adherent contact with said first elongate filament component along said continuous surface, the second hardened organic polymeric material being the same or different than the first hardened organic polymeric material, at least one of the first and second hardened organic polymeric materials being a thermoplastic elastomer having abrasive particles dispersed and adhered therein, said method characterized by the steps of:
   (a) rendering a first organic polymeric material which is a thermoplastic elastomer molten and adding abrasive particles thereto;
   (b) rendering a second organic polymeric material molten, the second organic polymeric polymer selected from the group consisting of thermoplastic elastomers thermoplastic polymers, and mixtures thereof;
   (c) forcing the first and second molten organic materials simultaneously through distinct first and second passages within the same die, the distinct passages forcing the first and second molten organic polymeric materials to assume the shape of first and second elongate filament components in melt fusion adherent contact along a continuous surface of the first component, thus forming an abrasive filament precursor; and (d) cooling the abrasive filament precursor to a temperature sufficient to harden the first and second molten organic polymeric materials and thus form the abrasive filament.
8. [8]. A method in accordance with claim [7] further characterized by the feature that said first abrasive filament component comprises a core and said second abrasive filament component comprises a sheath.
9. [9]. A method in accordance with claim [?] further characterized by the feature that said thermoplastic elastomer is selected from the group consisting of segmented thermoplastic elastomers [-] and ionomeric thermoplastic elastomers.