CA2022096A1 - Black synthetic fibre - Google Patents

Abstract

BLACK SYNTHETIC FIBRE

ABSTRACT

A polyamide composition for use in making high strength black nylon 6,6 fibre. The composition comprises of nylon 6,6 polymer; at least 0.4 wt% of carbon black based on the weight of the composition: in the range of about 0.006 to 0.1 wt% based on the weight of the composition of an organic pigment having a mean particle size in the range of about 0.05 to 0.2 microns, the pigment being heat stable at the melting point of the nylon and being insoluble in the nylon. The components (a) (b) and (c) are blended together at a temperature at or above the melting point of the polymer to provide an even dispersion of (b) and (c) in (a).

Description

POLYAMIDE COMPOSITION
BACXG~OUND OF THE INVENTION

This invention relates to a polyamide composition, and more particularly to a composition for making high strength black nylon 6,6 fibre. ~-~
The term "high-strength" as used herein refers to ~ -~
nylon 6,6 fibre which has been drawn to a draw ratio of between about 4.6 and 5.2, and which has a minimum tenacity of 7.0 gra~s per denier.
To make black nylon 6,6 fibre, a concentrate of carbon black in a nylon 6 carrier or the like may be blended with molten nylon 6,6. It has been found by applicant that when nylon 6,6 polymer is blended with carbon black concentrate, the maximum draw ratio obtainable with filaments formed from the polymer is generally about 4.3, which i8 unacceptably low for high-strength applications.
It is desired to provide high strength, black nylon 6,6 fibre.

SUMMARY OF THE INVENTION
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Accordingly, the invention provides a polyamide composition for use in making high strength black nylon 6,6 fibre, said composition comprising:
a) nylon 6,6 polymer;
b) at least 0.4 wt% of carbon black based on the weight of said composition;

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c) in the range of about 0.006 to 0.1 wt% based on the welght of fiaid composition of an organic pigment ~aving a particle ~ize in the range o~ about 0.05 to 0.2 microns, :~
said pigment being heat ~table at the melting polnt of sald nylon and being lnsoluble in sald nylon; ::~
wherein (a) (b) and ~c) are blended together at a temperature at or above the melting polnt of said polymer to provide an even dispersion of (b) and (c) in (a).
In another one of its aspects, the invention :~
provides high strength black nylon 6,6 fibre, said fibre being made from a polyamide composition which is spun lnto filaments and drawn to a draw ratio of about 4.6 to 5.2, .
said composition comprising:
a) nylon 6,6 polymer; ~ :~
b) at least 0.4 wt% of carbon black based on the weight of said composition; :~
c) in the range of about 0.006 to 0.1 wt% based on . :
the weight of said composition of an organic pigment having a particle size in the range of about 0-05 to 0.2 microns, 6aid pigment being heat stable at the melting point of said -~;:
nylon and being insoluble in said nylon;
wherein (a) (b) and (c) are blended together at a temperature at or above the melting point of said polymer to provide an even dispersion of (b) and (c) in (a).
In still another one of its aspects, the invention provides a process for making high strèngth, blacX nylon 6,6 fibre, said process comprising the steps of: ~ -blending together at a temperature at or above the melting point of nylon 6,6 to provide a polyamide composition, the following components~
a) nylon 6,6 polymer;
b) at least 0.~ wt% carbon black;
c) in the range of about 0.006 to 0.1 wt% based on ~

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the weiqht of said compositlon of an organic pigment having a particle size in the r~nge of about 0.05 to 0.2 microns, said plqment belng heat stable at the melting point of said nylon and belng insoluble in sald nylon;
spinning sald composltion to form filaments;
drawing said filaments to a draw ratio ~n the range of about 4.6 to 5.2.
It has been found by applicant that when carbon black is added to nylon 6,6, the maximum draw ratio obtainable in fibre prepared from nylon 6,6 is unacceptably low for high-strength applications. With the present invention, the draw rat~o of fila~ents made of nylon 6,6 containing carbon black can be raised to the acceptable ranqe for making high-strength nylon 6,6 fibre.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
'...... .................................................................. .... :.:, The draw ratlo of filaments made from the compo~ition of the present invention is preferably in the range of about 4.6 to 5.2 and most preferably is in the range of 4.75 to 5.2. Fibres that can only be drawn to a ratio below thi~ range will generally be too physically weak for high-strength fibre applications.
The organic pigment used in the present invention may be any pigment that will allow processing of the filaments of the polyamide composition at the acceptable range of draw ratios for ma~ing high strength fibre. The pigment is preferably indanthrone blue, alphaphthalocyanine blue or phthalocyanine green. The amount of pigment used is preferably between 0.010 and 0.067 wt% and is most preferably between 0.010 and 0.040 wt% based on ths total ~;
weight of the composition.

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I~ too little pigment iB added, t~e draw ratio obtainable wlll be too low and if too ~uch plgment iB added, unacceptable tints in the fibre may develop, and the strength obtalnable from the fibre composltion may be limlted due the presence of excessive pigment. The mean particle BiZQ of the pigment i8 preferably ln the range of 0.05 to 0.2 microns and is most preferably in the range of o.OSS to 0.13 microns.
The amount of carbon black used should be sufficient to impart a black colour to the yarn. Most preferably about 0.4 to 1.3 wt% carbon black is used.
Preferably concentrates of both the organic pigment and the carbon black are prepared by dispersing them in -polymeric carriers before they are mixed with nylon 6,6 polymer, since it is difficult to mix powdered carbon black and pigments directly with nylon 6,6 polymer. The polymeric carriers are preferably nylon 6 and the like.
The carbon black concentrate may al60 contain other additives including ionomer, lubricants and plasticizers used to help provide good dispersion of the carbon black.
The amount of carrier used should be sufflcient to facilitate the mixing of the nylon 6,6 polymer with the pigment or with carbon black and all of the additives.
Alternatively, the pigment, the carbon blacX and all of the additives may be combined with a single carrier to provide ~;
a pigment/carbon blacX concentrate.
The concentrates may be formed into pellets. These pellets may then be added to nylon 6,6 flake and subsequently extruded to form the polyamide composition.
Alternatively, the concentrates may be extruded separately ~- --and then injected into an extruder containing molten nylon ~6,6. The method used to combine the pigment, carbon blacX
and nylon 6,6 i~ not essential to the invention, provided that the carbon black and the pigment are evenly dispersed in the polymer before it is spun into filaments.

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5 202~6 The lnventlon will be further de~cribed, by way of illustration only, with referenc~ to the ~vllowlng example~.
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EXAMPLe 1 , -A dry blend of 300 grams of nylon 6,6 flake and 6 grams of black colour concentrate of the formula given in Table 1 was extruded under nitrogen in a lab extruder at a rate of 1 lb/hr at typical conditions for nylon 6,6 fibre making processes. The resultant composition was spun into 7 filaments and attempts were made to draw the fibre with rollers to a draw ratio of 4.79 and wind it up at 1082 meter6 per minute to make 44 dtex fibre.
It was found that it was impossible to run this process as in all cases the fibre broke immediately as attempts were made to string it up to the w~nder.

~ABLE 1 Black Colour Concentrate Formula Nylon carrier resins 62.9 wt~
Hydrocarbon resin 4.8 wt%
Plasticizers and lubricants 5.2 wt~
Carbon 81ack 27.0 wt~
Soluble ~lue toner 0.3 wt%

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EX~LE 2 A dry blend of the same compo~ition as Example 1 wa~
prepared, except that about 1 gram of an organic pigment concentrate comprising about 85 wt% nylon 6 and 15 wt~
indanthrone blue pigment of a mean particle size of about o.l microns was also added to the blend. The blend wa~
extruded and spun into filaments and drawn a~ described in Example 1 at draw ratios of 4.79 (Sample 1) and 5.12 (Sample 2).
No breakage of the fibre occurred and the fibre was easily strung up to the winder. The physicals of the resultant fibre are given in Table 2.

TA~LE 2 ~ -Physical Properties ~., Sample 1 Sample 2 Decitex: 44 42.0 Break Strength (N) 2.6 2.6 Elongation (%) 19.44 14.22 Tenacity (gram/denier) 6.7 7.03 Pigment in Fibre (wt%) 0.048 0.048 ~
These physical properties are acceptable from a ~ -commercial viewpoint and, based on experiments with a broad range of regular and coloured nylon 6,6 compositions, are equivalent to a 7.5 gram per denier product at a draw ratio of 4.8 when scaled up to a full commercial spinning machine.

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EXAMPL~ 3 Dry blends of the same composition A8 Example 2 were prepared, except that in one sample (Sample 3) 2.02 grams of a p~gment concentrate containing 20 wt%
alphapthalocyanine blue of a mean particle size of 0.1 ~icrons in a nylon 6 carrier was substituted for the indanthrone blue concentrate and in another sample (Sample 4) 2.0 gram of a pigment concentrate containing lS wt%
phthalocyanine green of a mean particle size of 0.1 microns in a nylon 6 carrier was substituted for the indanthrone blue concentrate.
These samples were extruded, spun and drawn as outlined in Example 1 and processed read~ly into f~bre without breakage.
The physical properties of these samples are reported in Table 3 below.

Physical Properties SamDle 3 ~ample 4 Decitex: 46 45-5 Break Strength (N) 2.5 2.5 Elongation (%) 16.75 18.58 Tenac$ty (gram/den,er) 6.0 6.16 These phy~ical properties are acceptable from a commercial viewpoint and would translate to a 7.0 gram per denier product at full commercial ~cale.

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EXA~L~ 4 Dry blends of the same composition as Example 2 were prepared, except that in one sample (Sample 5) 2 grams of a concentrate Or 20 wt% monoazo blue dye (a polymer-soluble colourant) in a nylon 6 carrier was substituted for the indanthrone blue concentrate and in another sample (Sample 6), 1 gram o~ a concentrate of anthraquinone red of a mean particle diameter of 0.5 ~icrons in a nylon 6 carrier was substituted for the indanthrone blue concentrate. The samples were then extruded, spun, and drawn as outlined in Example 1.
It was found that the filaments produced using both of these samples broke during drawing. `~ -;~
EXAMPLE 5 ~ -Dry blends of the same composition as Example 2 were prepared, except that the amount of indanthrone blue concentrate added was varied to provide three compositions (Samples 7, 8 and 9) with different amounts of indanthrone blue. A fourth cqmposition (Sample 10) was prepared by making a concentrate of carbon black and indanthrone blue by combining indanthrone blue with the carbon black and the additives of Table 1 to provide a single dispersion in a carrier resin and then combining the concentrate with nylon 6,6. The results obtained after extruding, spinning an~
drawing the compositions by the method outlined in Example 1 are reported in TABLE 4.

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-Sample 7 ~gm~Sample 9 Sample 10 Amount blue ln fibre (wt ~): 0.097 0.034 0.015 0.006 Decitex: 45.6 44.0 44.3 4s.0 Break Strength (N): 2.5 2.6 2.6 2.4 -Elongation (%3:18.16 18.4 15.62 lS.99 10 Tenacity(gpd) 6.3 6.7 6.5 6.12 Samples 7 to 10 all produced acceptable yarns.

~XAMPLe 6 A sample (Sample 11) comprising 98.2 wt% nylon 6, 6 flake and 1.8 wt% of black colour concentrate (see Table 1) was preparsd. A second sample (Sample 12) comprising 98.1 wt% nylon 6,6 flake, 1.7 wt % blac~ colour concentrate (see -Table 1) and 0.2 wt % pi~ment concentrate (85 wt~ nylon 6 carrier and 15 wt% indanthrone blue pigment, mean particle -~
size 0.0~ microns) was also prepared. These samples were each separat~ly run on a full scale commercial spinning machine operating at speeds above 2000 meters per minute and capacity over several hundred pounds per hour. The maximum draw ratio for each sample was determined by modifying the draw roller speeds. The maximum draw ratio for Sample 11 was found to be about 4.3 (product properties unacceptable for high strength applications) and for Sample 12 was found to be about 5.0 (product acceptable for high strength applications).

Claims (18)

1. A polyamide composition for use in making high strength black nylon 6,6 fibre, said composition comprising:
a) nylon 6,6 polymer;
b) at least 0.4 wt% of carbon black based on the weight of said composition;
c) in the range of about 0.006 to 0.1 wt% based on the weight of said composition of an organic pigment having a mean particle size in the range of about 0.05 to 0.2 microns, said pigment being heat stable at the melting point of said nylon and being insoluble in said nylon;
wherein (a) (b) and (c) are blended together at a temperature at or above the melting point of said polymer to provide an even dispersion of (b) and (c) in (a).

2. The composition of claim 1 having a draw ratio in the range of 4.75 to 5.2.

3. The composition of claim 1 wherein the mean particle size of (c) is in the range of about 0.055 to 0.13 microns.

4. The composition of claim 1 wherein said organic pigment is selected from indanthrone blue, alpha phthalo cyanine blue and phthalo cyanine green.

5. The composition of claim 1 wherein the amount of (c) used is between 0.010 and 0.067 wt%.

6. The composition of claim 5 wherein the amount of (c) used is between 0.010 and 0.040 wt%.

7. High strength black nylon 6,6 fibre, said fibre being made from a polyamide composition which is spun into filaments and drawn to a draw ratio of about 4.6 to 5.2, said composition comprising;
a) nylon 6,6 polymer.
b) at least 0.4 wt% of carbon black based on the weight of said composition;

c) in the range of about 0.006 to 0.1 wt% based on the weight of said composition of an organic pigment of a mean particle size in the range of about 0.05 to 0.2 microns, said pigment being heat stable at the melting point of said nylon and being insoluble in said nylon;
wherein (a) (b) and (c) are blended together at a temperature at or above the melting point of said polymer to provide an even dispersion of (b) and (c) in (a).

8. The fibre of claim 7 having a draw ratio in the range of 4.75 to 5.2.

9. The fibre of claim 7 wherein the mean particle size of (c) is in the range of about 0.055 to 0.13 microns.

10. The fibre of claim 7 wherein said organic pigment is selected from indanthrone blue, alphaphthalocyanine blue and phthalocyanine green.

11. The fibre of claim 7 wherein the amount of (c) used is between 0.010 and 0.067 wt%.

12. The fibre of claim 11 wherein the amount of (c) used is between 0.010 and 0.040 wt%.

13. A process for making high strength, black nylon 6,6 fibre, said process comprising the steps of:
blending together at a temperature at or above the melting point of nylon 6,6 to provide a polyamide composition, the following components:
a) nylon 6,6 polymer:
b) at least 0.4 wt% carbon black;
c) between about 0.006 and 0.1 wt% based on the weight of said composition of an organic pigment of a mean particle size between about 0.05 and 0.4 microns, said pigment being heat stable at the melting point of said nylon and being insoluble in said nylon:
d) spinning said composition to form filaments:
e) drawing said filaments to a draw ratio between about 4.6 and 5.2.

14. The process of clam 13 wherein said draw ratio is in the range of 4.75 to 5.2.

15. The process of claim 13 wherein the mean particle size of said pigment is in the range of about 0.055 to 0.13 microns.

16. The process of claim 13 wherein said organic pigment is selected from indanthrone blue, alphaphthalocyanine blue and phthalocyanine green.

17. The process of claim 13 wherein the amount of organic pigment used is between 0.010 and 0.067 wt%.

18. The process of claim 17 wherein the amount of organic pigment used is between 0.010 and 0.040 wt%.