CA1047194A - Block copolymer of poly(dioxa-alkylene amide) and polyamide - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Novel block copolymer formed by melt blending a melt spinnable polyamide such as nylon-6 and a poly(dioxa-amide) such as poly(4,7-dioxadecamethylene adipamide) which is also known as 30203-6 is disclosed. Said copolymer has utility as a fiber. The fiber of disclosed copolymer, for example, of nylon-6 and said poly(dioxa-amide) has moisture absorption char-acteristics similar to that of cotton. Resulting copolymer is also known as 30203-6/6. Furthermore, the resulting fiber still maintains the other desirable properties of the major con-stituent, for example, nylon-6.

Description

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CROSS REFERENCES TO RELATED APPLICATIONS

This application is related to Canadian Serial No.
213,649 filed same date by Robert M. Thompson and Richard S. Stearns; title of the application is Copolymer of Blocks of Alternating Poly(Dioxa-amide) and Polyamide.

This application is also related to Canadian Serial Nos. 213,636 and 213,634, both filed same date by present inventor and titled Block Copolymer of Poly(Oxa-Amide) and Polyamide, and, Block Copolymer of Poly(Dioxa-Arylamide) and ~olyamide, respectively. This application is also related to Canadian Serial No. 213,637, filed same date by Elmer J.
Hollstein. Subject matter of the latter application relates to a method for the hydrogenation of a dinitrile which is a precursor of the hydrophilic polymer disclosed within the aforementioned related applications.

BACKGROUND OF THE INVENTION

It is known that commercially important polyamides, such as nylon-6, have excellent physical properties in many respects. However, for certa:in textile application fabrics and similar products prepared from such nylons are somewhat deficient in moisture absorption. This characteristic is important because according to Encyclopedia of Polymer Science & Technology, Vol~ 10, Section Polyamide Fibers, moisture absorption determines rapid drying, comfort factors, ease and cost of dyeing and hand or feel of the fabric. To overcome this moisture absorption deficiency many attempts have been made but none have been commercially successful to date.

Disclosed herein is a novel block copolymer which can be converted into a fiber having moisture absorpt:ion ~ ~ ~ -2-......

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properties similar to that of cotton, the present commercial standard of comparison. This novel block copolymer consists of a certain polyamide and a certain poly(cLioxa-amide). Sur-prisingly, the incorporation of certain po]y(dioxa-amide) into a certain polyamide does not adversely effect the man~ desirable fiber properties of the polyamide and yet substantially im-proves its moisture absorption property. Also the copolymer can be formed into a desired shape by extrusion, in~ection molding and other well known thermoplastic forming methods.

Generally, copolymers containing the amide ~unction, t l~
i.e., -N-C- can be formed by melting two polyamides. Thus when two different polyamides are mixed and heated above their melting points they form copolymers. This process is also known as melt blending. However, the length of time the polymers are maintained at a temperature above their melting points has a profound e~ect on the resulting structure. As the mixing at the elevated temperature begins the rnass is a physical mixture of two different compounds. But gradually as the heating continues the mixture is converted into a copolymer characterized as a "block" copolymer. However, if the blending and heating continues the length of the 'Iblocks'' decrease and sequences of "alternating" appear. If the blending and heating occurs for a suf~icient time, all the ''blocks" disappear and only "alternating" sequences exis-t.
At present there is no known direct way of determining chain sequences of such a polymer. But indirect methods exist and these are discussed in detail hereinafter. Controlled de-composition of such a copolymer will yield all identifiable components that make up the copolymer ~ut will not indicate sequences.

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As inferred from the previous discussion, the terms "block" and "alternating" can easily be misapplied.

However, facilitating the characterizing of a polymer and/or copolymer is consideration of its starting materials and the methods used to prepare the polymers. Thus for example if caprolactam ~CO(CH2)5NH~ is properly processed the resulting polymer is HOCCO(CH2)5NH~nH or alternatively nylon-6. The latter can be designated a homopolymer. Thus the latter is a chain-like molecule composed of recurring units (monomeric). By comparison a copolymer consists of two monomeric units, that is to say, each monomeric unit could by i-tself form a homopolymer.
Thus for example a butadiene-styrene copolymer consists of butadlene which could form a butadiene homopolymer and styrene which could form a styrene homopolymer. And -the butadiene(a)-styrene(b) copolymer could have an alternating sequence. The sequence would be a "-abababab-" structure. The latter has a regularly alternating pattern. Other possible patterns of alternating copolymers are'~andom", i.e., -cdcdcddcccddcdcdcc-;
and "short sequence", i.e., -eefffeeffeeefffee-. Examples of such alternating copolymers are as follows. Chemical Abstract 8876L~f, ~ol. 70, 1969, (Japanese Patent 28,o37/68 discloses an alternating copolymer having moisture retention properties prepared from the combination of (a) salt of bis(~-aminopropoxy) ethane (also referred to as 30203) and adipic acid and (b) the monomer caprolactam. British Patent 1,169,276 discloses an alternating copolymer having improved hydrophylic properties prepared from the combination of (a) salt (I) of H N(CH2)3-0~CH2-C(CH3)2-CH2-0-(CH2)3NH2 P
acid and (b) the monomer caprolactam; also an alternating copolymer of the aforementioned salb (I) and hexamethylene diammonium adipate (H3 N(CH2)6NHCO(CH2)4COO)-; also referred ~o~
to as nylon 6-6 salt. Chemical Abstract 4514h, vol. 49, 1955, discloses an alternating copolymer prepared from the (a) salt ) 2 ( 2)3 (CH2)4-0-(cH2)3-NH2 and adipic acid and (b) nylon 6-6 salt. Salt (II) upon heating forms a cream-colored material; such discoloration detracts from its utility where clarity is required. U. S. Patent 3,522,329 discloses an alternating copolymer prepared from the (a) salt of diamine of polyethylene oxide (HOCH2CH2(0-CH2CH2)nOH) and adipic acid and (b) ~- caprolactam (also called caprolactam). U. S. Patent 3,514,498 discloses an alternating copolymer prepared from the (a) salt of diamine of polyethylene oxide and adipic acid and (b) ~-caprolactam.

A block copolymer can resul-t when a m-lxture of polymer "A" and polymer "B", both of ~hich contain amides is properly processed. Thus the resulting block copolymer contains rela-tively long chains of a particular chemical composition, the chains being separated by a polymer of different chemical composition, thus diagrammatically ¦ A ¦ B r A ¦.
A block copolymer can also contain relatively long chains of a particular chemical composition but in this type the chains are separated by a low molecular weight "coupling group~'; thus diagrammatically ~ . Within each of the aforementioned polymer chains, i.e., A and/or B can be a homopolymer or an alternating copolymer. Examples of some of these polymers are as follows. The previously mentioned U. S.
Patent 3,514,498 also discloses a block (alternating) copolymer prepared from two polymers; (a) polymer resulting from the salt of diamine of polyethylene oxide and adipic acid and ~-caprolactam and (b) poly-~ capramide (nylon-6). U. S.
Paten-t 3,549,724 also discloses a block (alternating) copolymer prepared from (a) polymer prepared from polyethylene oxide diammonium adipate and ~-caprolactam and (b) nylon-6 or nylon-6,6. U. S. Patent 3,160,677 discloses a block copolymer prepared from (a) a polymer prepared from dibutyl oxalate [(COOC4Hg)2~ and a diamine and (b) polycaprolactam.

Contrary to expectations based on the previously discussed art it has now been found that it is possible to pre-pare a composition comprising a block copolymer of polyamide and poly(dioxa-amide) having moisture uptake equivalent to that of cotton. In addition fibers of the copolymer have overall fiber properties substantially equivalent to that of such nylons as nylon-6.

SUMMAR~ 0~ THE INVENTION

Present invention resides in a novel composition.
It has utility as a fiber as well as other utilities. The com-position is a block copolymer of a certain polyamide and a certain poly(dioxa-amide). The polyamide portion of -the mole-cule is a bivalent radical of a mel-t spinnable polyamide.
The poly(dioxa-amide) portion of this molecule contains both a double oxygen linkage, i.e., -R-O-R-O-R- and amide linkage, H O
"
i.e., -N-C-. The following repeating structural formula depicts the composition of this invention:

~ Rl R R2 R o O bivalent H , / 2 ~1 H " ll radical of _ N CH2-C-C-O-R4-0-C-C-CH2-N-C-R -C - _ melt ' ' f ' spinnable H R3 R3 H _ Y polyamide z wherein Rl, R2, R is selected from the group consisting of 3 H, Cl-C10 alkyls and C3-C10 iso~lkyls, ~0~7~
R4 is selected ~rom the group consisting o~ Cl-C10 alkylenes and C3-Clo isoalkylenes, R5 is selected ~rom the group consisting o~ CO-ClO
alkylenes and C3-Clo isoalkylenes, and y = 2-100 z = 2-150 The molecular weight of the copolymer is about 5,000-100,000.
DESCRIPTION

As stated hereto~ore one portion o~ the novel compo-sition ls a melt spinnable polymer. Melt spinnable re~ers to a process wherein the polymer, a polymide, is heated to above its melting temperature and while molten forced through a spinnet. The latter is a plate containing ~rom one to many thousand ori~ice, through which the molten polymer is ~orced under pressure. The molten polymer is a continuous filament and depending on the number of ori~ices many filaments can be ~ormed at the same -time. The molten filaments are cooled, sol-idi~ied, converged and ~inally collected on a bobbin. I'his technique is described in greater detai.l in Encyclopedia o~
Polymer Science & Technology, Vol. 8, Man-Made Fibers, Manu~acture.

I~ a single fiber is extruded, as in the case when lt is intended to be knitted into hosiery, the product is called a monofilament. When the product is expected to be converted into a fabric by knitting or weaving, the number o-~ monofilaments is in the range o~ 10-100. Such a product is known as a multi~ilament yarn. Yarns ~or industrial application, such as in the construction o~ tire cords, usually contain 3 several hundred to a thousand or more ~ilaments~ When the fibers are used to make a spun yarn, i.e., a yarn formed by twisting short lengths of fibers together, as is the practice with cotton, the number of orifices can rise to tens of thousands. The extruded material is cut into pieces in the range of 1-5 inches long to produce "staple" fiber. This staple fiber is converted into spun yarn in the same manner as cotton. Polymer of present invention can be prepared into the aforementioned forms by the various methods disclosed.

Also, the polymers of present invention can be used to prepare nonwovens. Nonwoven refers to a material used as a fabric made without weaving, and in particular having textile fibers bonded or laminated together by adhesive resin, rubber or plastlc or felted together under pressure. Many such methods are described in detail in Manual of Nonwovens, Prof. Depl-Inq and Dr. Radko Kroma, Textile Trade Press, Manchester, England.

Polyamides which are crystallizable and have at least a 30C difference between melting point and the temperature at ; which the molten polymer undergoes decomposition can be melt spun. Fxamples of melt spinnable polyamides are as follows:
nylon-6,10 [poly(hexamethylene sebacamide)]; nylon-6 [poly(penta-methylene carbonamide)J; nylon-6,6 (hexamethylene adipamide);
nylon-ll [poly(decamethylene carbonamide)]; M~D-6 [poly(metaxy-lene adipamide)]; PACM-9 [bis(para aminocyclohexyl) methane azelamide]; PACM-10 Cbis(para aminocyclohexyl)methar~esebacamide];
and PAC~-12 [bis(para aminocyclohexyl)methane dodecanoamide].
Others are listed in ~ncyclopedia of Polymer Science & Technology, Vol. lO,Section Polyamide Fibers, table 12. Methods for pre-paring these polyamides are well known and described in numerous patents and trade journals.

~47~4 The poly(dioxa-amide) portion of the composition can be prepared by the following generalized scheme:
,Rl ~R2 ,Rl ~R2 ,R2 ~Rl (1) N=C-C=C\ -~ HO-R4-OH --3 N-C-C-C-O-R4-0-C-C-C-N

(I) (II) (III) ,Rl ~Rl ,R2, ~Rl

(2) (III) ~ H2 ---~ N~I2-cH2-c-c-o-Rl~-o-lc-c\-cH2 2 (IV) Rl jR2 ,R2 jRl

(3) (IVJ+ HOOCR5COOH --~ (OOcR5cOO)(N~I3~cH2-c-c-o-R4-o-c-c-cH2-NH3~) (V) -H2 ,Rl ~R2 R2 jRl O O
(~) (V) ~ H2 ~CI- ~-O-RL~-O-C-C-CH2-N-C-R5-C :1 Reaction (1) is often referred to as cyanoethylation;
particularly wherein Rl=R2=R3=H; also these R's can be C1-C10 alkyls or C3-C10 isoalkyls. R4 can be one of the following:
Cl-C10 alkylene and C3-C10 isoalkylene. Reaction (2) is a hydrogenation. Reaction (3) is the reaction between a diacid and diamine resulting in a salt. R5 can be one of the following:
CO-ClO alkylene and C3-C10 isoalkylene. Reaction (4) is often referred to as a condensa-tion polymerization. Here the repeating unit contains fewer atoms than the monomer, and necessarily, the molecular weight of the polymer as formed is less khan the sum ~7~
of the molecular weights of all the original monomer units which were combined in the reaction to form the polymer chain.
Examples of Cl-C10 alkyls are methyl, prop;yl, butyl, pentyl, etc;
examples of the C3-Clo isoalkyls are isopropyl,~ isobutyl, isopentyl and the like Examples of Cl-C10 alkylenes are as follows: methylene, dimethylene, trimethylene, and the like;
examples of C3-Clo isoalkylenes are as follows: methyltri-methylene, 2-methyltetramethylene and the like.

A variation of preparation reactions (1) and (2) are also disclosed in Chemical Abstracts 3935K, Vol. 71 (1969) S. Afr-lcan Pate~t 6,704,646.

Examples of HO-RL~OH o:~ reactlon (1) are as follows:
ethylene glycol, propylene glycol and trimethylene glycol.
Examples of HOOCR5COOH of reaction (3) are as follows: oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, undecanedioic, a,~-diethyl succinic, and a-methyl-a-ethyl suberic.

Examples of poly (dioxa-amide) polymer that can be prepared in the aforementioned generalized scheme are the following:

O O
H
~ ( H2)3-o-(cH2)2-o~(c~I2)3-N-c-(cH )4-C--~
poly(4,7-dioxadecamethylene adipamide), also 30203-6 O O
H ll 11 ~ ( 2)3 (CH2)2-o-(cH2)3-N-c-(cH2)g-c~3 poly(4,7-dioxadecamethylene sebacamide) also 30203-10 O O

~ ( 2)3 0-(CH2)4-0-(C~I2)3-N-c-(cH2)L~-c-~

poly(4,9-dioxadodecamethylene adipamide) also 30403-6 CH O O

~N-(cH2)3-o-cH2-c-cH2-o-(cH2)3-N-c(cH2)L~

poly(4,8-dioxa-6,6-dimethyl undecamethylene adipamide) ~ N-CH2-CH-CH2-0-(CH2)2-0-CH2-CH-CH2-N-C-(CH2)4-poly(4,7-dioxa-2,9-dimethyl dodecamethylene adipamide) O CH O
H H n ; 3 ll ( 2)3 ( I2)2 -(C~I2)3-N-C-CH2-CH-CH2-CH2-C-}

poly(l~,7-dioxadecamethylene-2-methyladipamide) The polymers of present in~ention can also contain an antioxidant such as 1,3,5-trimethyl-2,4,6-tris-(3,5-ditertiarybutyl-4-hydroxybenzyl) benzene Small amounts of antioxidant, e.g., 0.5 weight percent, are satisfactory, however, as little as 0.01 weight percent can be used or as much as 2.0 weight percent also can be satisfactory. Antioxidants other than the aforementioned one can be used. The antioxidant generally would be mixed in combination with the two polymers prior to melt blending. Other usual additives for polyamides such as delustrants and/or light stabilizers can also be incorporated.

XAMPLES

The following describes how the various ~ovel polymers and their precursors were prepared, and the in~luence o~ cer~ain variables upon their properties. Also reported are results on comparative polymers.

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1. Preparation of 1,2-bis(~-cyanoethoxyethane) (NC-(cH2l20-(cH2 ~ -O(CH2)2 CN~

To a 5 liter double walled (for water cooling) glass reactor with a bottom drain and stopcock was charged 930 grams (15 moles) of ethylene glycol and ~5.6 grams of 40~ aqueous KOH
solution. Some 1620 grams (30.6 moles of acrylonitrile (NC-CH=CH2) were then added dropwise with stirring at such a rate that the temperature was ~ept below 35C. After -the addition was completed the mixture was stirred an additional hour and then allowed to stand overnight. The mixture was then neutral-Lzed to a pH of 7 by the addition of 6 molar HCl. A-fter washing wi-th saturated ~aCl solution three times, the product was separated from the a~ueous layer, dried over CaC12 and passed through an A1203 column to insure that all basic materials had been removed. The yield obtained was 90~ o~ theortical.

2. Preparation of 1~,7-dioxadecamethylenediamine ~ 2(CH2)3-0(CH212-0-(C~I2)3 - 2) In an 800 milliliter hydrogenation reactor was charged 150 grams of 1,2-bis(~-cyanoethyloxyethane), 230 milliliters of d-Loxane and abou-t 50 grams Raney Co. After purging the air, the re~ctor was pressurized with hydrogen up to 2,000 psi and heated to 110C. As the hydrogen was consumed additional hydrogen was added until pressure remained constant. Upon cooling, the pressure was released and the catalyst was filtered. The dio-xane was removed by atmospheric distillation. The remaining mixture was distilled by a 3 foot spinning band distillation unit. The diamine distilled at 123-12~C and 3.75 mm Hg.
About 98 grams of 99.95~ pure material were obtained. The material can be referred -to as 30203 diamine.

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3. Preparation and Polymerization o~ Poly (~,7-dioxadecamethylene adipamide) (30203-6) To a solution o~ 41.50 grams of adipic acid dissolved in a mixture of 250 milliliters of isopropanol and 50 milli-liters of ethanol was added, with stirring, 50 grams of the 30203 diamine dissolved in 200 milliliters of isopropanol. An exothermic reaction occurred. Upon cooling, a polymer salt crystallized out of solution. The salt was collected on a Buchner fu~nel and subsequently recrystallized from a mixture of L~oO milliliters of ethanol and 300 milliliters of isopropanol ~ t~ e ~ e~ g~ ~
a melting point of 182C and the p~I of a 1~ solution was 6.9.
85 grams (92~ yield of theortical) of the salt was obtained.

About L~o grams of the polymer salt were charged to a heavy walled glass polymer "D" tube. Then the neck of the tube was constricted for sealing and purged of air by evacuating and filling with nitrogen 5 times. Finally the tube was heated in an aluminum block for 2 hours at 200C. After cooling the tip of the tube was broken off and the remaining portion was bent over at a L~5 angle by heating and then connec-ted to a manifold and purged of air with nitrogen vacuum cycles~ The tubes were heated at 222C under nitrogen at atmospheric pres-sure for 6 hours using methyl salicylate vapor baths. On cooling, the tubes were broken and the polymer plug crushed to 1/8" size pieces. The resulting polymers had inherent viscosi-ties ranging from 0.9 to 1.1 in a meta-cresol solution.

L~. Polymer Melt Blending Suitable amounts of dried 30203-6 polymer and nylon-6 were charged to a large test tube having two openings in the ~0~719~
rubber stopper. The openings were for a helical stirrer and a nitrogen inlet. The container was purged of air. Afterwards the nitrogen filled container was heated using a suitable liquid-vapor bath. The mixture of the two polymers was agitated with the helical stirrer powered by an air motor for the required time. Before allowing the molten polymer to cool the stirrer was lifted to drain the polymer. After solidifi-cation the material was broken up and dried for spinning.

5. Polymer Spinning and Drawing After the aforementioned melt blending the polymer was charged to a micro spinning apparatus consisting of stainless steel tube (5/8" O.D. x 12") with a .037" capillary. The tube was heated with a vapor bath to the temperature consistent with the polymer. Generally about 245C was used. Nitrogen was swept through the polymer until the polymer melted and sealed ~, the capillary. After the polymer was completely melted and a uniform temperature had been reached (about 30 minutes) the nitrogen pressure was increased by about 30-50 psig (depending on the polymer melt viscosity) to ex-trude the polymer.

Due to the nature of this apparatus~ it could not be equipped with a filter system to remove particles from polymer melt. This made spinning polymers that were prone to form gel particles as nylon-6,6 difficult to spin continuously.

The fiber as it left the tube was drawn on a series of rollers and wound up on a bobbin. The first roller or feed roll was travelling at 35 ft./min. The filament was wrapped 5 times around this. After crossing a hot pipe maintained at about 50C the filament was wrapped around the second roller or a draw roll (5 times) which speed varied depending on the draw -1~-~7~4 ratio required (130-175 ft./min.) Unlike commercial draw rolls, the fiber tended to abrade itself; that is the fiber coming off rubbed against fiber coming on. This made higher draw ratios difficult to obtain. The third roll had a re-movable bobbin and was driven at a slightly lower speed than the draw roller.

Draw ratio refers to the ratio of the speed of the second roller or draw roll to the speed of the first ro:Ller or feed roll. Thus if the second roller was travelling at 175 feet per minute and the first roller at 35 feet per minute the draw ratio is 5 (175/35). This difference in speeds of the rollers stretches the fiber. Stretching or drawing orientates the molecules, i.e., places them in a single plane runnlng in the same direction as the fiber.

6. Results of Tests and Comparative Runs The accompanying Table I shows the ef~ect of melt blending's temperature and time on various properties of several block copolymers having different proportions of poly_(dioxa-amide) and polyamide. Also shown are comparative results.

Comparison of runs 1, 3 and 5 indicate that at rela-tively low temperatures and short blending time the addition of substantiaL amounts of 3030-6 into nylon 6 does not substan-tially lower the melting point of the resulting 3020-6/6.
~ecreases in tensile and initial modules are noted while an increase in elongation e~ists.

Comparison of runs 5, 6 and 7 indicate -chat as the blending time at a constant temperature increases a decrease in melting point occurs. Thls indicates a decrease in the ~15-J~047~94 amount o~ "blocks" and further indicates an increase in the amount of "alternating."

Indirectly, it is known that crystallinity o~ a block copolymer falls of~ as the alternating sequences increase. Thus properties dependent on crystallinity such as melting point and tensile decrease as alternating increases.

The fact that inherent viscosity, a measurement indicating molecular weight, increase9 means that the molecular weight is increasing thereby eliminating degradation as a reason for the change in melting point. The increase in blending time also causes a reduction in tensile, elongation and initial modulus.

; Comparison of runs 7, 8 and 9 indicate that while maintaining a constant blending time, as the temperature o~
blending increases, decreases occur in inherent viscosity and melting point. Also decreases in tensile and initial modulus occur.

Tensile, elongation (elongation to rupture), and initial modulus (textile modulus) and the methods ~or obtaining such values are defined and described in Kirk-Othmer, Encyclo-pedia of Chemical Technology, 2nd ed., Vol. 20, Textile Testing.

Accompanying Table II shows the moisture regain of several block copolymers having di~ferent proportions of poly-(dioxa-amide) and polyamide. Also shown are comparative results for nylon-6 and cotton.

Comparison of runs 1-6 (Table II) demonstrate that increasing the amount o~ poly(dioxa-amide) in the block copolymer '3L~47~
increases moisture regain substantially compared to the moisture regain o~ nylon-6 at various relative humidities. Also com-parison o~ runs 7 and 6 indicate that said block copolymer con-taining 30~ 30203-6 has a moisture regain better than cotton at 95~ and 85~ relative humidities and almost equal at lower levels of 65~ and 75~ relative humidities.

Moisture regain re~ers to the amount o~ moisture a dried sample of fiber picks up in a constant relative humidity atmosphere. Measurement o~ this property was carried using a series o~ humidity chambers made from desicators containing suitable saturated salt solutions (i.e., NaN02-65~;
NaCl-75~, KCl-85~, Na2S03-95~, To determine moisture regaln ~irst a sample o~ the fiber was dried in a vacuum desicator over P205. A~ter a constant weight was obtained the sample was placed in one o~
the appropriate chambers. The chamber was then evacuated to speed up equilibrium. The ~iber remained in the chamber until a constant weight was obtained. The increase in weight of the sample over the dried sample was the amount o~ moisture regained.

Accompanying Table III shows the e~fect of boil o~
on moisture regain of several block copolymers prepared at dif~erent blending temperatures and times. Also shown are weight losses which occurred during boil off. Comparative da-ta for nylon-6 is also reported.

Boil o~ refers to the placement of the ~iber in boiling water for a speci~ied length o~ time. A~terwards the weight loss was determined. Also after following the procedure described ~or determining mois-ture regain the incremental lncrease in ~ moisture regain at 65~ relative humidity was ~)47~94 determined. Boil off can be considered as akin to a dye treatment.

The increase in moisture regain as a result of boil off is thought to best be u~derstood by the followi~g explanation. By placing the fiber in boiling water portions of the fiber relax. Thus the orientated amorphous sections tend to open up. Boiling off speeds up the relaxation of this unnatural state. This opening up permits the ~iber to take up more moisture than it otherwise would be capable of.
Heating the fiber~ by other than placing in boiling water, will also relax the fiber. ~eight loss comparisons of run 3, 2 and 1 indicate again that as blending time is increased the polymer becomes more alternating.

Accompanying Table IV demonstrates the effect o~
various draw ratios in moisture regain~ tensile, elongation and înitial modulus of se~eral block copolymers of poly(ether amide) and polyamide.

The data indicates that as draw ra-tios were increased generally moisture regain clecreased except at a 95~ relati~e humidity. Also as the draw ratios were increased tensile and initial modulus increased but elongation decreased.

Accompanying Table V shows the effect of percent of 30203-6 in 30203-6/6 on dye uptake. The data indicates that as the percent of 30303-6 in 30203-6/6 increases d~e uptake increases. Compared ~o water molecules, dyes are larger molecules and cannot penetrate the crystalline structure of nylon fiber, thus dye uptake can be related to the amount of amorphous regions in the fiber~

The amount of dye uptake was measured in the following 7~
manner. The preweighed fibers were dyed in suitable containers at room temperature. The concentration of the "direct yellow 28" in the a~ueous dye solution was measured before and after spectrophotometrically. The dyeing was considered complete when no decrease in dye concentration was observed over several hours. Prior to dyeing it was determined that the initial concentration of the dye in the both had to be greater than 5.8 x 10-5 grams/milliliter so that the measured dye absorption was independent of the initial dye concentra-tion.

Accompanying Table Vl describes the relative oxida-tion degradation of a block copolymer of poly(dioxa-amide) and polyamide. The data indicates that -the polymer 30203-6~6.
suffers tenacity losses when exposed to air at elevated temperatures; comparison of runs 4, 5, and 6. However, the data also indicates that a small amount of antioxiaant, e.g., 1,3,5-trimethyl-2,4,6 -tris-(3,5-ditertiarybutyl-4-hydroxy benzyl) benzene, at least prevents tenacity losses and perhaps e~en increases tenacity; comparison of runs 8 and 5, 9 and 6.
Also shown is the relative stability of nylon-6; the increase in tenacity of nylon-6 in comparative run 2 is believed to be the result of annealing, Surprisingly in run 5, although a tenacity loss was sustained, virtually no disco~oration occurred.

In runs 7, 8 and 9 the aforementioned antioxidant was added in the amount of 0.5 weight ~ prior to melt blending.

The data of Table Vl was obtained in the following manner. The fibers listed in the table were placed in a forced air oven maintained at 120C for the listed times. After ~11 47~94 su-~icient time has passed, samples were removed and tested for changes in tenacity.

Analogous results are obtained when nylon-6,10;
nylon-ll, MXD-6, PACM-12 and other are used in place o~ nylon-6 in the polymer melt blending step (4). Also, analogous results are obtained when in step (3), adipic acid is replaced with one o~ the ~ollowing acids: oxalic, malonic, succinic, glutaric, pimelic, suberic, azelaic, sebacic, undecanedioic, ~,~-dièthyl succinic and ~-methyl-~-ethyl suberic. When the ethylene glycol o~ step (1) is replaced with one of the ~ollowing glycols:
trimethylene, propylene and tetramethylene analogous results are obtained.

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Claims (19)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A block copolymer having a molecular weight of about 5,000-100,000 and the following repeating structural formula:

wherein R1, R2, R3 is selected from the group consisting of H, C1-C10 alkyls and C3-C10 isoalkyls, R4 is selected from the group consisting of C1-C10 alkylenes and C3-C10 isoalkylenes, R5 is selected from the group consisting of CO-C10 alkylenes and C3-C10 isoalkylenes, and y = 2-100 z = 2-150.

2. A copolymer according to Claim 1 wherein the copolymer is hydrophilic.

3. A copolymer according to Claim 2 wherein the copolymer has a percent moisture regain of at least 4% at a relative humidity of 65%.

4. A copolymer according to Claim 1 wherein the bivalent radical polyamide is selected from the group consisting of nylon-6 and PACM-12.

5. A copolymer according to Claim 4 wherein the copolymer is hydrophilic.

6. A copolymer according to Claim 5 wherein the copolymer has a percent moisture regain of at least 4% at a relative humidity of 65%.

7. A copolymer according to Claim 6 wherein the bivalent radical polyamide is selected from the group consisting of nylon 6 and PACM-12.

8. A copolymer according to Claim 7 wherein R1, R2 and R3 are H and R4 and R5 are C1-C10 alkylenes.

9. A copolymer according to Claim 8 wherein the copolymer has a percent moisture regain of at least 4% on a relative humidity of 65%.

10. A copolymer according to Claim 8 wherein R4 is a C2 alkylene and R5 is a C4 alkylene.

11. A fiber obtained by spinning the copolymer of Claim 1.

12. A fiber obtained by spinning the copolymer of Claim 8.

13. A fiber obtained by spinning the copolymer of Claim 10.

14. A fiber obtained by melt spinning the copolymer of Claim 1.

15. A fiber obtained by melt spinning the copolymer of Claim 8.

16. A fiber obtained by melt spinning the co-polymer of Claim 10.

17. A monofilament obtained by extrusion of the copolymer of Claim 1.

18. A monofilament obtained by extrusion of the copolymer of Claim 8.

19. A monofilament obtained by extrusion of the copolymer of Claim 10.