CA1205255A - Antisoiling nylon carpet yarns - Google Patents

Abstract

IMPROVED ANTISOILING NYLON CARPET YARNS
ABSTRACT OF THE DISCLOSURE
Polyamide carpet fibers coated with a certain class of fluorine-containing addition polymer are described. The coating is chemically bonded to the fiber surface through amide linkages (-NHCO-) of the polyamide. The coating imparts antisoiling properties of a permanent nature to the fibers. Where applied to carpet yarn, the coating has good retention through carpet dyeing operations and does not significantly interfere with the ability of the carpet to take up dye, even in the casse of foam dyeing which is particularly sensitive to fluorocarbon coatings.

Description

~z~s2~js ~1- l4-54(8156)A

I~PROVED A~TISOILING ~YLON CARPET YARNS

Field of the inventlon This lnvention relate~ to polyamide fibers coQted ~ith a certain class o~ flourine-cont~ining addltion p~ly~ers. The coatin~ i~parts ~ntisoiling properties to the fibers and i~ chemically bonded to~ the fiber 3urface. The chemical bonding of the co~ting to the fiber ~urface imparts anti~oiling properties of a permanent nature to the fiber. The t~rm "fibers" Q9 used herein mean~ fiber3 in the form of either conti~uous fila~ent~ or staple. The term yarn a~ used her~ es~s ~ continuou3 strand of fibers.
Descri tion of the Prior Art Considerable research and development efforts ha~e been directed to providing carpeting ha~ing good lS antisoiline properties~ It i9 ~enerally known that the ~nti80iling propertie~ of carpeting can be improved by treRting eith~r the pile of the finiahed carpeting or the yarn fro~ ~hich the carpeting pile iY con~tructed with an 8nti~0ili~g a~ent. Fluorins-containin3 co~pounds ~referr~d to hereinafter a9 fluorochemical~), although espe~ive, are generally considered to be the be~t choice of antisoiling agent9 for thi~ purpose. ~he fluoroche~ical~ are con~entionally applied to the carpet pile or y~rn surface ~rom an aqueou~ medium. The ; .

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surf&ce i8 then dried to remove the ~ater and leave the fluorochemical behind a~ a coating, with the coating being held to the 3urface by van der Wasls attractive forces. Under ~uch condition3, if the fluorochemical is applied to the yarn rather than to the finished carpeting pile, a significant amount oP fluorochemical comes off from the yarn during normal carpet dyeing operations. This requires that the yarn be initially coated with a 8reater amou~t of the expen~i~e fluorochemical thaD is actually needed in the carpet.
SUMMARY OP THE INVENTION
., .
In accordRnce ~ith the pre3ent invention polyamide fiber~ u~eful in the con~truction of carpeting are pro~ided havin~, a~ a coating, a fluorine-contsining addition polymer chemically bcnded to the fiber throueh amide linkages of the polyamide. The addition polymer i~ characterized ir having a carbon-carbon backbone and ~ubstituent groups pend~nt therefrom, ~ome of which contain fluorine atoms attached directly to aliphatic carbon atoms and others of ~hich ere capable of chsmically bondin& to the polyamide fiber through chain-extending amide group~ or linkages (e.~ HCO-). The coated fiber~ are characterized in that the addition polymer contain~ a suffiGient amount of fluorine to provide at le~st lOO parts per ~illion (ppm) of fluorine, based on the weight of the fibers (o.w.f.).
The ~luorine of the coating imparts excellent antisoiling properties (includin~ antiYtaining and aoil relea3e properties~ to the fiber~ and fabrics made therefrom.
The coated fibers of the invention are convenie~tly prepared, for example, by coating the polyamide fiber~ with an aqueou~ di3psr~ion of the addition polymer and then heating the coated fibers ~5Z~

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under conditions of ti~e and temperature 3ufficient to dry the fibers and effect chemical bonding between the polyamide fibers and the addition poly~sr, for example, at a temperature of 190 C for e period of about 10 minutes. The fibers may be in the form of yarn or in fabric form (a,g. carpet pile). Chemical bonding of the addition polymer to the polyamide fiber i9 beli~ved to tske place, at least in part, by trans-amidation in which, for e~ample, carboxylic acid sub~tituent groupR
of the addition polymer react with amide linkage~
(-NHCO-) of the polyamide according to the following mechanism:
2 ~ H~~6 ~ ~~~~ - CH-~H + HO-C -~0 O G=O O
OH - ~H
Chemical bonding of the addition pclymer to the polyamide fiber greatly impro~s the retention of ths polymer to the fiber during normal csrpet dyeing ~ ' operation~ and over the life of the carpet. When `~ applied to carpek yarn, the coating does not significantly interfere with the sbility of the yarn to take up dye, even in the case of foam dyeing, which i8 particularly ~ensitive to fluorocarbon coatin~s.
PREFER~ED EMBODIM3NTS OF THE INVENTION
Addition polymer u9~ful in preparing the coated fibers of the pre~ent inYention ha~e a carbon-carbon backbone and substitu~nt groups pendant therefrom, 90~e of which are capable of chemically bonding to polyamide fiber throueh amide linka~es of the polyamids (such groups being referred to herein as "reactive groups") and others of ~hich contain fluorine atoms attached to aliphatic carbo~ atoms (~uch groups being referred to herein as "fluorine-containin~ groups"). In general, the addition polymers compri3e repeating units of the formula ~;ZQ5~i5;

-4- 14-54(8156~A

R R
- C ----~ C --R R' and of the formula - C--C -R R"
where R i8 hydrogen or a group that is nonreactive with S amide linkage3 of polyamide~ (such ~roups being referrred to herein 8S "non-reactive ~roups"), H' is a reactive group, ~ueh a~, a carboxylic acid group (e.g.
-COO~- or CH2COOH~, a phenol, alcohol, phosph~te, pho~phite, phosphonate, ~ulfate or sulfonate group, and R" i~ a fluorine-containin~ group. The addition polymers are convenlently prepared by reacting one or more monoMers of the formula R R' (Component A) with o~e or more monomPr~ of the formula R R

R R"
(Component ~) in a mole ratio ranging from 1:10 to 10:1 under conditions selected to effect polymerization. In general, if the Component A content of the polymer is le~s than about 10 mole %, there ~ill not be ~uf`ficient chemical bondine between the addition polymer and polyamide to prevent ~i~nificant losses of the coating during carp~t dyeing operations. On the other hand, if the Component ~ content of the polymer is less than about 10 mole %, the anti oiling proparties of the coated fiber will not be ~ignificantly enhsnced. In any avent, the addition polymer should contain a sufficient amount of Component B to provide a coated fiber containing at least 100 ppm of fluorine o.w.f. When the ~2~S;~:~S
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coated fiber~ compri3es le98 than about 100 ppm of fluorine, the Antisoiling properties of the fibers are not ~ignificantly enhanced for carpet applications.
Preferablyl the coated fibers compri~es 300 to 1500 ppm S of fluorine o.w.f. In general, increa~ing the ppm of fluorine above about 1500 ppm o.w.f. does not 3ignificsntly increase the antisoilin~ properties of the fiber~. Representative Component A monomers-that mQy be used in prep~ring the sddition polymers include, but are not limited to, acrylic acid ~AA), methacrylic (MAA) and other organic acid~. Representative Component B
monomers that may be u~ed in prepsrin~ the addition polymer~ include, but are not llmited to, perfluoroalkyl acrylutes or methacrylates of the general formulP
CF3(CF2)XCnH2~00CCR=CH2, for example, l,l-dihydroper-fluorooctyl methacryl~te (FOM) and the corresponding acrylate(FOA), and 3ulfamides, such as~
~ 8 (CH2)p CH2=C~ -C-O-CnH~ -N ll ~CF~m C~
O
where R has the same meaning a3 previously defined, x is an integer from 5 to 11; n i~ 0, 1 or 2; m is 3 to 15;
ehd p i3 O, 1, 2 or 3. Preferably, x is an inte~er from

5 to 9, n is 2, m i8 7 and p i~ 0. ~.ixtures of the monomers may alco be u~ed; for eYample, ~i~tures of perfluoroalkyl acrylates where x ranges from 5 to 11.
Generally, when selectin~ commercially available monomers for use in preparing the addition copolymers, R
will be hydrogen or e low~r slkyl group ~uch a~ methyl or ethyl.
Addition polymers useful in practicing the pr2sent invention may conveniently be prepared by an aqueous ~mul~ion polymeri~stlon techniques under conditions that fflvor formation of block copolymers.

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According to this technique Component A (e.g., acrylic acid) and Component ~ (e.g., l,~-dihydroperfluorooctyl acrylate) are polymerized in the presence of water, a free radical initiator (e.g., K2S20~3) and ~n emulsifier (e.g., sodium lauryl sulfate). The acrylic acid and initiation dissolve in the water phase and the acrylate (~OA) doeq not. The emulsifier $s added in a concentration abo~e the critical micelle concentration and forms micelles which are in equilibrium ~ith dis~olved emulsifier molecule3. The water insoluble acrylate monomer (FOA ) is solubili~ed in the micelles.
Although ~he resulting product i9 mostly block copolymer, it contains some random copolymer. Also, the block copolymer is not completely soluble in solvents which ~ould be expected to dissolve the copolymer (e.g.
N,N-dimethylacetamide, N,N dimethylformamide and hexRfluoroisopropanol), indicating that the copolymer i~
branched or crosslinked. Random copolymers can be similarly prepared by carrying out the foregoing emul~ion polymerization in the! presence of a strong election dono~ uch as N,I~-dimethylformamida (DMF). In thi~ instance the acrylic acicl monomer forms ~ater insoiuble complexes and most OI tho acrylic acid is in the DM~ phase alon~ ~ith the FOA, Nhereb~ a random copolymer of acrylic acid and ~OA i9 formed. This product, ho~everj is al90 a mi~Eture of random and block copolymerq but in thi3 i~stance it is mostly random copoly~er.
Accordin~ to one embodiment of the in~rention, 30~ the addition polymer oontains, in addition to repeatin~S
units of formulas tI ~ a~d (II ), repeating units of the formula R R
C ,.. ~ _ P~ R''' ~ ,...

5~
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where R ie a~ previously defined and ~''' i~ a nonreactive group (i.e. A g~O~p nonreactive ~ith amide linkages) such A~

~ O~CH3 or -COCH~ .
According to this embodiment, the addition polymer i~
prepared by copolymeri~ing in addition to Component A
and Component B, a third component (Component C) compriqing one or more other vinyl monomers of the formula C= C
R R''' copolymerizable ~ith Components A and B, such as styrene (Sty), vinyl acetate (VA), methyl methacryIate (~.A), vinyl chloride (YC)~ vinylidene chloride (VDC), vinyl pyrrolidone (VP). Addition polymer~ containing Compon~nt C may be in the form of random copolymers or block copolymers, including block copoly~era in which one or more ef the blocks oonsist of a random copolymer, ~or e~ample, ~ block copolymer consi3ting of acrylic acid blocks and block~ consi~tine of a random compolymer of FOA and ~tyrene or a block copolymer con~i3ting of AA/FOA/Sty, MAA/FOM/St~, AA/FOA/VA and MAA/FCM/Sty/VA.
When Component C i9 used in forming addition poly~erq uitable for u~e in practicin~ the pres nt invention, preferablyt at least lO mole % of the monomer~ ahould ` compri~e Component A monomers and another lO mole g should compri~e Component B.
The fluorine-containing addition polymer is conve~iently applied to polyamide fibers from a finish compri~ing an aqucous diqper3ion of the polymer.
Preferably the fiber~ are in the form of a yarn. ~he 30 fini~h msy be applied to the fibers in a con~entional manner, for eYample, by spraying th~ finish onto fiber~

%5~i -8- 14-54(8156)A

of a polyamide yarn or by passing such a yarn over a freely rotating roll (finish roll) psrtially immersed in a bath of the finish or by any other suitable means.
The polyamide yarn to ~hich the finish haq been applied 5 i9 heated under conditions of time and temperature sufficient to dry the yarn and effect chemical bonding of the polymer to the polyamide fibers of the yarn. If desired, however, pile fibers of fini~hed carpeting may be similarly treated to provide the coated fibera.
The fluorine-containing addition polymer may be applied to any polyamide fiber in accordance with the pre~ent invention. Polyamide fibers of major commercial importance are those shaped from nylon and, eYpecially, those ~haped from nylon 66 which is polyhexamethylene adipamide and those shaped from nylon 6*~hich is polycaprolactam. Other polyamides from ~hich the fibers may be shaped include: nylon ll*which is the polymer of ll-amino undecanoic acid; nylon 610*which is polyhe~amethylene ~ebacamide; and copolymers of nylon 66*
or nylon 6*in which a portion of the nylon 66*or nylon 6*
mono~ers are replaced by other monomer~ copolymerizable there~ith, for example, a nylon 66/6*copolymer or nylon 66/6TA*copolymer where 6TA is hexamethylene terephthalamide.
Although it is intended that the co~ted fiber of the pre3ent invention may be used in all textile applications, the fibers have particular value for carpet yarn applications ~here there has been a need to provide a fluorocarbon-coated yarn having good retention and abra~ion re~i~tance of the coating through carpet dyeing operetion~. The fibers of the present invention fulfill this need.
The follo~ing example~ are given to further illustrate the invention. In the examples~ "ppm of fluorine" means parts by ~eight of fluorine per million * Trade M~r~s .

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parts by ~ei~ht of nylon yarn; "F-Retention" means the weight ratio of fluorine on the yarn just after dyeing to that on the yarn just prior to dyeing expressed a~ a percentage; and "C-16 Contact Angle" msans the contact angle in degree~ of droplets of linear hexadec~ne (C-16) on the coated nylon surface. The highest po~sible angle obtainable ~ith a fluorochemical is about 76 degrees.
Percentages ~i~en in the examples are weight percentage~.
EXA~PL~ I
In thi~ example ~ix aqueous dispersions, each containing one of the copolymer~ of methylacrylic acid (MAA) and 1,1-dihydroperfluorooctyl methacrylate (FoP13 listed in Table I, are prepared u~ing the following 1S procedure which favors formation of block copolymer~.
230ml of uater and 5g of sodium lauryl sulfate are added to a 500ml fla~k and heated to 80C under nitrogen.
1.0~ of catalyst (K2S208) is added snd dissolved. 20g of FOM and an amount of methyl~crylic acid corresponding to the monomer ratio shown in I'able I below are then added. The content~ of the flask are heated to and maintained at 80 C for one hour with stirring to effect polymerization of the monomers. The content3 of the flask (co~prisine an aqueous dispersion containing FOM/MAA copolymer and a precipitate containing byproduct3 such as MAA homopolymer) are then cooled to room temperature and the ~queo~ls di3persion i9 decanted from the pracipitate. Two sets of nylon 66 films wers coated uith the ~queous dispersions of the copolymers.
Analysis indic~tes the product to be mostly 2 block copolymer containing a small amo~nt of random copolymer.
Each ~et of film~ con3ists of si~ film3 each coated with one of the copolymer3 dispersionsO Each coated film was prepared by immer~ing the film in one of the di3per3ion~
for 10 seconds and then removing the excess dispersion ~2~352S5 -10- 14-54(8156)A

from the film with blotting paper. Aq ~hown in Table I, one set of the fil~ wa~ heat~treated in a laboratory oven for lO minutes et 190C to effect chemical bonding of the FOM/MAA copolymer to the nylon 66 film. The other set of film~ was not heat treated. All of the coated films ~ere then blank dyed at the boil for one hour in a blan~ dyeing ~olution. (Blank dyeing simulate3 normal carpet dyeing conditions.) ~he solution was prepared by dissolving lO moles of each phosphoric acid, boric acid and acetic acid in 500 ml of water, then adjusting the pH to 4.0 with NaOH snd flnally diluting with water to R total volume of lOOO
ml~ The contact angle of droplets of linear hexadecane on the sur~ace of each nylon film i3 then measured and given in Table I, below, along with other data relating to the coated films. The contact angles were measured using a com~ercially available gonio~eter designed for measuring such angle3.
TABL~ I

Contact Angle Mol~ar Di3persion (degree~) R~tio Copolymer FluGrine Blank-Dyed Film FOM/M.AA ~/Q % Unheated Heated A 0.05 30 0.26 0 38 B 0.08 32 0.57 0 53 C 0.13 31 0.78 0 60 D -33 25 l.O 10 63 E 1.0 78 3.9 20 67 F 9.0 60 3.6 20 46 The result~ ~iven in Table I sho~ that coating3 chemically bonded to the nylon ~urface in accordance with the pre~ent invention (e.g., via a haat treatment) have good retention to the nylon sur~ace during dyeing, a~ mea~ured by the C-16 Contact Angle. The results also show the effect of the FOM/~AA ~olar ratio on th~

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contact angle. The results show that the contact angle increase~ with FOM content of the copolymer up to a point and thereafter decreaaes.
~AMPLE 2 In this example nylon cPrpet yarn~ are coated with various fluor~acrylate/acrylic acid copolymer~ in accordance with the present invention. Aqueou3 dispersions of the copolymera are prepared u9ing the procedure described in Example l by copolymerizing component3 in which a fluoroacrylate component consisting of a mixture of perfluoroalkyl acrylate (FPA) of the for~ula CF3(CF2)XCH2CH200CCH~CH2, where x rangea from 5 to 11, an acid component consi~ting of acrylic acid (AA) and a third co~ponent, when present, consisting of styrene (Sty), methyl methacrylate (XA~ or vinyl acetate (VA). The copolymers and the molar ratio of the monomers used in their preparation are given in Table II. When the third ; 2~ component i~ present the resulting copolymer i3 belîeved to be mostly a bIock copolymer co~prising blocks composed of acrylic acid and blocks composed a random copoly~er of PFA and the third component, the block copolymer being repre~ented in Table II, for e~ample, as AA/PFA~gty. Each polymer i8 applied to a yarn from a finish comprising an aqueou~ diaperaion of the polymer.
The re~ultant coated yarn wAs heat-treated at 190C for lO minutes and then blank dyed as described in Example 1. After blank-dyeing, the contact angle was determined as well ~s the amount of fluorine (ppm) re~ainin8 on the yarn. The amount of fluorine retained on the yarn after blank-dyeing expressed as a percentage of fluorine on the yarn before blank-dyei~g (F~etention) ~as alao deter~ined. The raaulta Mre gi~en in ~abl~ II.

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Table II
Molar F F-Retention Contaat Angle Y_ Co~oly~er Rstio ~ g (Degree) l PFA -- 564 65 54 (Control) 2 AA/PPA l:l 655 99 60 3 AA/PFA~Sty lol:l 599 99 59 4 AA/PFA+MA l:l:l 589 9~ 61 5 AA/PP'A~VA l:l:l 716 81 58 6 ~ntreated -- ~- -- <20 The dats given in Table II clearly show the fluorochemical-coated yarns of the pre~ent in~ention (yarn~ 2-5) lose very little of their coating during normal carpet dyeing operation~. In related e~periments, results ~imilar to those sho~n in Table II
are also obtained with yarn~ coated with the polymer described in Exampl0 l, i.e. FO~/MAA, in a mole ratio of 1 : 1 .

In this exsmple, experime~ts are conducted to demon~trate the outstanding ability of the coated fibers of the present invention to provide carpet pilin~ that can be fosm dyed without difficulty, in particular, ~ithout lo~s of appearance, due to "frosting".
Frosting is the appearance re3ulting from the pre~ence of undyed ibers in the carpet piling ~hich actually ei~e the appearance of frost on the surface of the piling.
~ylon 66 carpet yarns are coated with various copolymers, polymers and ~OA homopolymer as sho~n in Tabla III. An a~ueous disp0rsion of each of the polymer~ listed in Table III i~ prepsred usin~ the general procedure descrlbed in E~ample l. E~ah polymer is applied to the yarn~ from a spin finish compri~ing an flqueous dispersion of the polymer. The yarns are then -13- 14-54(8156)A

he~t treated at 190 C for lO minutes in an oven and then tufted to provide cut pile carpet samples. The samples are Rubjected to a conventional foam dyeing operation.
The appearance of the dyed carpet sample~ i~ th~en rated S on a scale ranging from l (worst) to lO (best). A
sample rated l would be stron~ly froqted. In another test, a drop of oil (hexadecane) i9 placed on top of the pile of the dyed carpet and the time required for the drop to be absorbed by the pile is recorded. The re~ults of the experiment are given in Table III.
TABLE III
- Molar F on F~ Oil Ratio Fiber Drop Foam Yarn ~oating , ~ (%) Te t Dyein~
l None ~ Zero lO
2 AA/FOA 3 1 56087 3 days lO
3 AA/FOA~VA 1:1:1 650lOO 3 days 9 4 AA/FOA~MA 1:1:1 71081 ~ dayslO
AA/FOA~MA 1:1:1 69093 2 dayslO
6 AA/FOAISty 1:1:1 60099 sev. hrs

7 FOA homopolymer 56065 3 days 6 *Fluorine ret2ntion It i9 contemplated that instead of treating fiber~ with the oopolymer~ de~cribed in the above examples copolymer~ may be u3ed in which the fluorine-containing units R R
-- C C -R R''' thereof are provided by using a sulfonamide in ~ddition to or in~tead of the fluorine-containing monomers described therein. Suitable sulfonamides include tho~e commercially available and of the formula ~I.Z9~S5 ~14- 14-54(8156 3A

3( 2 )7 ~ - N ~ CH2CH20CCR=C~2 ~here n i8 O, 19 2, or 3 and R i~ prefer~bly -H or -CH3.

~ ~ ' :~ :

:

Claims (17)

1. The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
   
   l. A polyamide fiber having an addition polymer chemically bonded to the surface thereof, said addition polymer having a carbon-carbon backbone with fluoride-containing substituent groups pendant therefrom wherein the fluorine atoms of the groups are attached directly to aliphatic carbon atoms and are present in an amount sufficient to provide at least 100 ppm of fluorine o.w.f.
2. 2. The fiber of claim l wherein said polyamide is nylon.
3. 3. The fiber of claim 1 wherein said polyamide is nylon 66.
4. 4. The coated fiber of claim 3 in the form of a yarn.
5. 5. A coated polyamide fiber obtained by coating a polyamide fiber with a copolymer having a carbon-carbon backbone where some of the substituent groups contain fluorine atoms attached directly to aliphatic carbon atoms (fluorine-containing groups) and others of which are groups capable of reacting with amide linkages of the polyamide fiber (reactive groups) and then treating the resulting coated fiber to effect a chemical bond between said reactive groups and said polyamide through amide linkages of the polyamide, wherein said coated fiber comprises sufficient fluorine atoms to provide at least 100 ppm of fluorine o.w.f.
6. 6. The costed fiber of claim 5 wherein said polyamide is nylon 66.
7. The coated fiber of claim 6 in the form of a yarn.
8. 8. The reaction product obtained by costing a polyamide fiber with a polymer comprising recurring units of the formula and recurring units or the formula and then treating the resulting coated fiber to effect a chemical bond between R' groups of said polymer and said polyamide through amide linkages of said polymide, wherein R' is a group capable of reacting with amide linkages of polyamides, R'' is a group containing fluorine atoms attached directly to aliphatic carbon atoms and R is hydrogen or a group nonreactive with said polyamide, said product comprising sufficient fluorine atoms to provide at least 100 ppm of fluorine based on the weight of fiber.
9. 9. The reaction product of claim 8 wherein said polyamide is a nylon.
10. 10. The reaction product of claim 9 in the form of a coated yarn.
11. 11. The coated yarn of claim 10 wherein R is hydrogen or methyl, R' is - COOH and R'' is where n is 0, 1 or 2; and s is an integer from 5 to 11, inclusive; p is 0, 1, 2 or 3; and m is an integer from 3 to 15, inclusive.
12. 12. The coated yarn of claim 10 wherein R is
13. 13. The coated yarn of claim 11 wherein said polyamide is nylon 66.
14. 14. The coated yarn of claim 11 wherein said addition polymer also contains repeating units of the formula where R''' is a group which is nonreactive with amide linkages.
15. 15. The coated yarn of claim 14 wherein R''' is a phenyl group and R is hydrogen or methyl.
16. 16. The coated yarn of claim 14 wherein R''' is and R is hydrogen or methyl.
17. 17. The coated yarn of claim 14 wherein R''' is and R is hydrogen or methyl.