AU461663B2 - Improvements in and relating to flame retardant yarns - Google Patents

Description

38, 872 n2 'The present invention relates tc flame retardant

conjugate fibres or filaments.

Numerous proposals have been put forward for the

conferring of flame-retardance on melt extruded filaments

or fibres for use, for example, in the textile industries.

Many of the proposals involve the addition of halogen

containing adjuvants to the polymer prior to or during

spinning, but, because of their reactive nature at elevated

temperatures, the addition of such adjuvants leads to

undesirable effects. Adjuvants which produce undesirable

effects are hereinafter referred to as "reactive adjuvants".

By "reactive adjuvant" is meant a flame-retardant

halogen containing compound which when heated to at least

200°C in the presence of a fibre forming polymer or its

precursor causes the polymer or its precursor to become

coloured or sensitive to heat or light, or to give rise

to deposits on surfaces, to emit volatile products, or to

cause difficulties during subsequent processing of the polymer.

The applicants have now found that many of the

aforesaid difficulties can be at least reduced, whilst pre-

serving the flame-retardance of the fibre or filament, if

said fibre or filament consists of a flame-retardant core

containing a reactive adjuvant, surrounded by a polymer

sheath which has good surface properties and which is easily

processable, such as a sheath of polyester or polyamide.

In the term "polyester" we include copolyesters

and in the term "polyamide" we include copolyamides.

The present invention therefore provides a

flame-retardant conjugate filament consisting of two

components in sheath/core relationship, the sheath

4 61663

3 8,872m surrounding comprising a melt extrudable fibre-forming polymer reactive a flame-retardant melt extrudable core containing a

adjuvant as defined. More particularly the present invention consisting

of two components in sheath/core relationship, the sheath

comprising a fibre-forming polyester or a fibre-forming flame- polyamide and the core comprising a fibre-forming retardant polyamide or polyester. Surprisingly, it has been found that although

the core portion only of the filament contains a flame- retardant reactive additive the sheath/core filament, as

a whole, has improved flame-retardance properties and in

many instances is self-extinguishing. More particularly, the present invention provides

a flame-retardant conjugate filament consisting of two

components in sheath/core relationship, the sheath comprising a fibre-forming polyester or a fibre-forming polyamide and

the core comprising either a fibre-forming polyamide or bromo polyester containing halogen groups and preferably mixture groups or of a fibre-forming polyamide or polyester of which at least one constituent contains halogen groups

and preferably bromo groups.

461,663

3 8 ,872n2 compounds for Examples of preferred halogen containing a polyamide is the use in practising the present invention where

substrate are defined as follows: more The molecule of the compound comprises one or ring struc- benzene rings or one or more condensed benzene tures or a combination of said rings and ring structures. one or two links. Neighbouring benzene rings may be joined by a linkage If there is one link it may be a direct linkage or melt such as via groups which are stable in the polyamide 0 where R is H or alkyl _(CR2 -S02-, -O-(CR 2 m 2 or more and and n is 1 or more and preferably 2-6 and m is preferably 3-6, or, where R' is alkyl, aryl or (CH2 )p0,

where p>l and 0 indicates a benzene ring and where any there are two aromatic ring may carry halogen substituents. If links at least one linkage must be via one of the aforesaid groups. (ii) At least one benzene ring or condensed ring grouping. structure is substituted by at least one halogen to (iii) No halogen shall be in the ortho position or to any any other halogen nor to any polymer-reactive electron accepting group.

(iv) The molecule may be substituted by polymer- or polymerisable reactive groups, such as amide-forming groups benzene derivatives thereof and preferably separated from any group. ring or condensed ring structure by an alkylene further Any ring or condensed ring structure may be

substituted, preferably symmetrically, by non-reactive non-pole

groups such as methyl groups. A 461663

38,87 2 2

In the above definition, by the term "condensed ring

structure" we mean, for instance, a naphthalene or anthracene

type of structure. Symmetrical substitution on the molecule to give is preferred since such structures have been found of the the minimum interferences with the physical properties

basic polymer and of the yarn produced from it. element The preferred halogen is bromine since this

is more active than chlorine in conferring flame-resistance.

Examples of suitable compounds are: 3,6-dibromodurene bis(p-bromophenyl) ether

4-bromodiphenyl

2,7-dibromo-9,9-bis (B-carboxyethyl) fluorene hexabromodiphenyl for Examples of preferred halogen containing compounds is use in practising the present invention where a polyester dicar- the substrate include polymers derived from a brominated poly boxylic acid and/or a brominated glycol, for example, dibromo terephthalate) or poly(ethylene-

-2:7 dibromofluorene-9:9 diproprionate). Other suitable bromo

organic compounds include tetrabromo benzene, penta-bromo toluene,

acetylated tetrabromobisphenolA, deca bromo diphenyl and bis

(4-bromophenyl)ether. An enhanced flame-retardant effect can be obtained when, present in the in addition to the proportion of halogen compound of a core of the filament, there is present a proportion in the core, or in synergistic metal compound in the sheath or

4 61663

38, 872 172

both. The useful metal compounds are metal oxides, such as

antimony trioxide -or titanium dioxide. The proportion, or

proportions, of such compounds should preferably be such that

the overall content corresponds to from 0.5 to 5% by weight

expressed as metal on the total of core and sheath. The metal

compound should preferably be of low volatility under the

conditions of processing the polymer to a filament. The synergistic metal compound, if present, may be

incorporated at any stage in the preparation of the filament,

for example, during the preparation of the polymer, by mixing

into the formed polymer or by mixing into the melt at the

stage 'of melt spinning.

The core portion may also consist of an intrinsically

flame-retardant material.

The conjugate filaments of our invention may be made

from the two component parts by any of the convention methods of forming sheath/core filaments by melt spinning.

An advantage of the conjugate filaments of our invention

is that they possess an advantageous degree of fire retardancy without there being any substantial danger of disadvantageous

effects produced by the presence of harmful compounds at the

filament surface, e.g. discolouration and cross-linking.

Furthermore, in the said filaments, particularly when using the

above defined halogen compounds, there is a much reduced

tendency for the incorporated compound, when not forming part of

the polymer chain to be volatilised from the surface of the

filament during manufacture and processing, since the concen-

tration of adjuvant at the surface is nil. Additionally

6 461663

38,87 2 n2

excessive delustring resulting from the necessity to incorporate high loadings of antimony trioxide, for example, is alleviated by using an undelustred sheath. As regards the relative proportions of sheath and core,

this depends on the relative importance of the various advan-

tageous factors. Thus, the thicker the sheath, the less

likelihood is there of volatilisation of the adjuvant and the

less noticeable is any discolouring which may occur in the core

polymer. On the other hand, the thicker the sheath, the less

is the proportion of core, and therefore the higher is the

the core. A required proportion of flame-retarding adjuvant in in the preferred limit may be set for the content of adjuvant core at about 20% by weight, beyond which difficulty is exper-

ienced in processing. This allows the use of a very small minimum

value for the percentage of the cross-sectional area of the filament occupied by the core, for example 5-10. A practicable minimum for the thickness of the sheath is that for which.the percentage of the cross-sectional area of the filament occupied by the sheath is 5-10%. Polyesters for use in the process of our invention may,

for example, be based on terephthalic acid, naphthalene 2:6-

-dicarboxylic acid and 1:2-diphenoxyethane-pp'-dicarboxylic acid. Glycols on which the polyester may be based include than HO(CH 2 )nCH, wherein n is not less than 2 and not greater

and bis (hydroxymethyl) cyclohexane. Copolyesters may have as second acid a dicaphoxylic acid, for example, isophthalic,

adipic, sebacic or sulphoisophthalic acids, or a hydroxy- carboxylic acid, for example para. hydroxybenzoic acid. 461.663

38,8 72 172

Copolyesters for use in the process of our invention may also be based on two glycols; a second glycol may be a polyglycol. Polyamides and copolyamides for use in this Invention mE be prepared by the polymerisation of diamines and dibasic acidE or polyamide-fornting functional derivatives of these acids. As examples of suitable diamines may be listed linear polymertl lene aliphatic diamines of general formula H2 N(CH 2 )n NH 2 1 where n is not less than 14and not greater than 20, branched chain aliphatic diamines, for example 2,2,14-trimthylhxamethy: diamine; ether diaxines, ror example, 3,3'±bis(amenopropyl) ether, ethylene bis)3-aminopropyl) ether; cycloal~phatiC diamines, for example, l, 1 1-bis Caminomethyl)cyclohexafle, bis-

(4amino-cyclohexyl) methane; aryl aliphatic diamines, ror example, m-xylylene diamine, p-xylylene diamine; and heterocyC diamines, for example, piperazine. The above diamines may be condensed singly or In various combinations as appropriate and familiar to those skilled in the art with functional derivatives of oxalic acide with linear. PolymethYlene dicarboxylic ac-ids (or their poly- amide-forming function derivatives) of general formula (HO0C(CH )COOH, where m Is not less than 14 and not greater 2

than 20; with branched-chain aliphatic dicarboxylic acids, for example, 2-methyl butane, 1,J4-dcarboxylic acids, with cyclo-

aliphatic dicarboxylic acids, for example cyclohexafle 1,14- -dicarboxylic acid; with aromatic dicarboxylic acids, for example, -terephthalic, acid, isophthalic acid,

.8 *4 6t'663 terephthalic acid, naphthalene 1,4-dicarboxylic acid, benzo- phenone 2,4'-dicarboxylic acid; with arylaliphatic dicarboxylic acids, for example, 2,5-dimethyl p-phenylene diacetic acid,

2,2-bis Ip-carboxy-methpxy phenyll propane, bis jp-carboxy- methyl phenyll ether; with heterocyclic dicarboxylic acids, for

example, furan 2,5-di (p-propionic acid

Mixtures of these acids may be used to prepare copoly-

amides.

Polyamides and copolyamides may also be prepared from

e-amino- acids or the derived cyclic lactams, used either alone or in combination with the above diacids and diamines in

appropriate stoichiometric balance. For example, c-amino-

caproic acid, caprolactam, w-aminoundecanoic acid,w -amino-

dodecanoic acid, 7-heptanolactam, 8-octanolactam.

Other additives commonly present in polyester and/or

polyamides or other materials used for sheath and core may also

be present in the proportion in which they are commonly used.

Examples of such additives are delustrants, stabilisers, pigments

and optical whiteners, dye assistants and antistatic agents.

In order that the nature of our invention may be more easily

understood, we give hereinafter some nonlimitative examples

of methods by which it may be put into practice. In these

examples all parts and percentages are by weight.

Flame-retardance, as used in Examples 1 to 19, is

measured in the following manner.

The fibre or filament is knitted into hoseleg panels

(16" x and the panels scoured to free them from spinning

finish. The panels are tested for flammability as follows:

9 461663

38.87 9

The apparatus consists of a metal frame 16" x 3

wide, inclined at 450. The sample stocking panel when flat

measures 16" x A strip of glass fibre non-woven fabric 1

cut to 16" x To form the test a specimen of the sample

stocking panel is mounted centrally on the glass fibre

fabric. A line of staples is run vertically up the centre

of the composite panel, ends barely touching, and the two

parallel long edges are stapled at 4" intervals. The

positioning of the staples is important as they act as heat

conductors. The specimen is mounted on the metal frame with the bottom edge even with the bottom of the frame and held there by means of stentor pins protruding from theupper surfi of the frame. The holder is placed in a draught-free cabine the sliding door of which is closed to within 4" of the bott of the cabinet. A flame is applied to a fuse attached to the centre of the bottom edge of the specimen. The fuse is

made up of a piece of tissue paper measuring 4" x folded

6-fold to give a fuse measuring 1" x 14". The fuse is fixed the glass fibre so that 3/4" of it overlaps the specimen.

The fuse is lit by a match and by itself burns for 54 secon The fibres or filaments, or fabrics prepared therefrom, should preferably show the following results when tested in the above manner. Maximum Mean Burning Time (seconds) not greater than seconds. Maximum Mean Char Length (inches) not greater than inches. 4 61663s

38,87272

Flame-retardance for Examples 20-24 was measured as

follows:

Materials and Apparatus

1. 100% Glass Fibre woven fabric (Turner Brothers Asbestos Company Limited "Duraglas" Quality EKW211).

2. 67% Terylene/33 cotton 4oz woven fabric.

3. Stapler using 1cm staples. 4. A cabinet.

A sample holder. Procedure

1. Cut a piece of glass fabric 10" x 34" (Turner

Brothers Asbestos Company Limited "Duraglas" Quality

EKW211). 2. Remove every third strand of the horizontal weave (shortest length). 3. Ply up the fibre to be tested to approximately 150 denier. 4. Knit up the fibre as hose-leg on the Chell knitting

machine using medium tension. Cut 20" samples of the hose-leg. 6. Lay the glass fabric on one half of the sample, fold over the sample so that the glass fibre is sandwiched between two layers of fabric.

7. Staple the sample to the glass fabric with the fold

at the bottom. 8. Cut a piece of Terylene/cotton cabric 3" x 1".

4 61663

38, 87 2 72

9. Fold the Terylene/cotton fabric in two so that it

measures 1 x and staple this to the bottom edge of the

sample, so that the fold is at the bottom, and the material

is attached to either side of the sample. Mount the sample on the frame with the wick at the

bottom and so that it is held firmly, free from wrinkles.

11. Place the frame vertically in the cabinet situated

in a fume cupboard, with the fans on.

12. Expose the bottom edge of the wick to the flame

of a match for two seconds. 13. Start the stop-watch and close the front of the

cabinet. 14. Note the total time taken for the flame to extinguis'

and the type of flame. Measure the char melt length. This is the distance

between the bottom of the sample and the highest point where

the fabric has been damaged by the flame. Where possible six

samples of each variant should be tested for consistency of

results. EXAMPLE 1

74.67 parts of 6.6/6 copolyamide (90/10 w/w) were melt blended with 25.33 parts of hydrated hexamethylene diammonium salt of 2,7-dibromo-9,9-bis(B-carboxyethyl) fluorene (Br content 26.0%) for 30 minutes at 2850 in an atmosphere of

nitrogen. The resulting polymer had the following characterist

38.872 n2

Relative viscosity 26.3

Amine end groups 24.2 equiv./l06g Carboxyl end groups 70.5 equiv./10 6g Bromine content A sheath/core yarn was produced with 50% of the above bromine-containing copolyamide in the core and 50% of 6.6 polyamide containing 4% antimony trioxide in the sheath. The 5-filament yarn was drawn (DR 4.0) at 75°C to give a yarn of 44 dtx with the following properties: Tenacity 2.74 g/dtex

Extensibility 44.6%

The yarn was knitted into hoseleg panels (16" x and

the panels scoured to free from spinning finish. The panels were

tested for flammability as hereinbefore described. The

results obtained from the tests are given in Table 1 (see

Example 3). EXAMPLE 2 A core/sheath yarn was produced from 50% of the bromine- containing copolyamide of Example 1 in the core, and 50% of poly(ethylene terephthalate) containing 0.5% TiO2 and 3% antimony trioxide in the sheath, the 5-filament yarn was drawn (DR 4) at 100 0 C to give a yarn of 41 dtex with the following properties: Tenacity 2.28 g/dtex

Extensibility 23%

The yarn was knitted into hoseleg panels and the panels

tested for flammability as described. The flammability. results

obtained are given in Table 1 (see Example 3).

13 461663

38,872 n2

1 Comparative Example (90/10 containing 88.5 parts of 6.6/6 copolyamide parts of melt blenddd with 13.06 2% antimony trioxide were diammonium salt of 2,7-dibromo-9,9- the hydrated hexamethylene 1. as described in Example -bis 8 -carboxyethyl) fluorene the following characteristics: The resulting polymer had 32.3 Relative viscosity 26.0 equiv./l0 g Amine end groups 6 131.5 equiv./10 g Carboxyl end groups 3.49% Bromine content at 29500 to give a The polymer was melt spun had (DR 4.0) at room temperature, yarn which, after drawing

the following properties: 47.4 dtex Yarn gauge 3.02 g/dtex Tenacity 47.7% Extensibility hoseleg panels which were The yarn was knitted into as described. The results obtained tested for flammability

are given in Table 1. Comparative Example 2 halogen compound was melt 6.6 nylon containing no the yarn produced flame-tested spun as in Example 3 and given in Table 1. as a control. The results obtained are EXAMPLE 3 containing 2% antimony 91.97 parts of 6.6 polyamide, with 8.03 parts of 2,4,6,2'4'6'- trioxide, was melt blended Example 1. the manner described in -hexabromo-diphenyl in characteristics: This polymer had the following I' 461 663

38,87 2 n2

Relative viscosity 33.1

Amine end groups 4.2 equiv./l0 g

Carboxyl end groups 154.0 equiv./10 g

Bromine content 6.4%

A core/sheath yarn was produced from 50% of the above

bromine-containing polyamide in the core and 50% of 6.6

polyamide containing 4% antimony trioxide in the sheath.

The 2-filament yarn after drawing (DR 3.5) at 80 0 C had

the following properties: Yarn gauge 61.6 dtex

Tenacity 2.62 g/dtex

Extensibility 57.7%

The yarn was knitted into hoseleg panels and the panels tested for flammability as described. The flammability results are given in Table 1 below. The scoured test fabric had a bromine content of

4 6166 3

39, 979 n2--

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I00

ILI E0 C) 4 U '4)

4 4-1 0 '-I

V C 0 x :4,4 0w- C' :4' .r 0 0

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0 43

EJ *~1 4

4

'-4

V 0+ 3: 00 4)W Cul C, 4 0 i0 "-4 ,do 0 a '0.4 CMi 0 0 .l *E P 0 1A~ (DV N. F-4 +3 4. 0 43

'D0) 4' 0~e +3 0 94 '-4 00 r. :33 r-4 I4 V 0 :3v- 0 0 X P I V0 f4. A%'O 0U k A 00 in

Al 0 0 '-4 p4 i~t~w' 4) x r=i

I 46t96d~

38,8 7 2 7

It can be seen from the above results that both the mean burning time and the charred length of fabrics made from yarns containing halogen compounds were considerably lower than the values obtained with ordinary 6.6 nylon yarn and that, of the yarns containing halogen compounds the core/sheath yarns

gave fabrics with good white appearance.

EXAMPLE 4

A copolymer of ethylene: vinyl acetate (82:18) containing decabromodiphenyl was prepared and a core/sheath yarn

produced from 33% of the above bromine-containing copoly-

ethylene in the core and 67% of 6.6 polyamlde containing

4% antimony trioxide in the sheath. The 5-filament yarn was

drawn (DR 3.0) at 100°C,knitted into hoseleg panels and the

panels tested for flammability as described. The flammability results obtained are given in Table 2.

Comparative Example 3.

6.6 nylon containing no halogen compound was melt spun

at 295 C to give a 5-filament yarn non-core/sheath which

after drawing (DR 4.0) at room temperature was knitted into

hoseleg panels and flame-tested as a control. The results are given in Table 2.

EXAMPLE

88.15 parts of poly(4-methyl pentene 1) and 11.85

parts of decabromodiphenyl were mixed,purged with nitrogen

and heated under nitrogen, at 320°C for 25 mins, until the

mixture was melted. The mixture was stirred vigorously for

mins to produce a homogeneous melt. It was allowed to cool

with the stirrer removed from the melt. 17 461 663

38,872n2

The polymer contained 8.3% bromine. A sheath-core yarn

was produced with 50% of the above bromine-containing polymer

in the core and 50% of 6.6 polyamide containing 2% antimony trioxide in the sheath. The 5-filament yarn was drawn

(DR 4.0) at 900C to give a yarn of 42.3 decitex, extensibilit

of 29% and tenacity of 2.24 g/dtex. The yarn was knitted into hoseleg panels (16" x and the panels scoured to remove spinning finish. The panels were tested for flammability by the method. The results are given in Table 2. EXAMPLE 6 91.7 parts of 6.6 nylon containing 2% antimony trioxide and 8.3 parts of decabromodiphenyl were mixed, purged with nitrogen and heated In an oil bath at 285 0 C under stream of nitrogen for 20 mins until the mixture was melted. The mixture was stirred vigorously for 20 minutes, to produce a homogeneous, viscous melt and allowed to cool with the stirrer removed from the melt. The cream polymer had a relative viscosity of 24.4, a vicat softening point of 2660C, CEO 289.5 equiv/10 6 g and contained 8.29%.bromine. A sheath-core yarn was produced with 50% of the above bromine-containing polyamide In the core and 50% of 6.6 polyand containing 2% antimony trioxide in the sheath. The yarn was drawn (DR 4.0) at 600 C to give the following properties: Decitex 35.4 Tenacity g/dtex 2.58 Extensibility 19.3

38, 8 72 m

EXAMPLE 7 88.15 parts of Makrolon (Trade mark) (a polycarbonate supplied by Farbenfabriken Bayer AG) and 11.85 parts of decabromodiphenyl were mixed, purged with nitrogen and heated at 34000 for 35 minutes under nitrogen until the mixture was melted. The mixture was stirred vigorously for 10 minutes to produce a homogeneous, viscous melt. It was allowed to cool with the stirrer removed from the melt. The brown polymer had an inherent viscosity of 0.51, a vicat softening point of 178°C and contained 10.5% bromine. A sheath-core yarn was produced with of the above bromine-containing polymer in the core and of 6.6 polyamide containing 2% antimony trioxide in the sheath. The 5-filament yarn was drawn (DR 2.6) at 180 0 C to give a yarn of 49.8 decitex and 8.5% extensibility, The yarn was knitted into hoseleg panels (16" x 4") and the panels scoured to remove spinning finish. The panels were tested for flammability described previously.

The results are given in Table 2.

4 61663

38, 87 2 72

~0 V4 -P

co

co

Cd

*1 0

9.

F-4

4 6166 3

38,8 7 2/72

EXAMPLE 8

Powdered poly(ethylene terephthalate) (172 parts),

3 (8 parts) and the diacetate of tetrabromo bis phenol A

parts) were intimately mixed together in a rotary blender

at a speed of 2200 rpm for 3 mins. The mixture was used to

spin the core of sheath/core filament. The sheath was poly (ethylene terephthalate) containing 0.5% titanium dioxide as

delustrant. The sheath/core ratio was 1:1.

The yarn was spun through a 20 hole spinneret (0.015 inches in diameter hole) with a throughput of 10g per minute

for each component and with a wind up speed of 4,000 feet

per second per minute.

The yarn was plied up to 60 filaments and drawn over 0 a heated roll at 90 C and a hot plate at 180 0 C to give a

drawn yarn denier of 150 and a tenacity of 3.5g per denier.

The yarn was knitted into hoselegs on a 3.5 inch circular knitting machine and tested for flammability by the method

described. All samples were self-extinguishing and the

average char length was 5" and the average burning time was

seconds.

EXAMPLE 9

Powdered poly(ethylene terephthalate) as used in

Example 8 (174 parts). Sb 2 0 3 (6 parts) and decabromo- diphenyl (20 parts), were intimately mixed together as In Example 1 and spun as the core of a 1.1 sheath/core filament, using as sheath the polyethylene terephthalate of Example 8 and using similar conditions to Example 8 but with wind up speed 3,500 feet per minute. The yarn,

2.1 461663

38,87 2 72 of which had a superior colour to that of the yarn

comparative example 4, was drawn, knitted up into hoselegs

and tested as described. The average char length was

inches and the average burning time was 41 seconds.

Comparative Example 4

"Powdered poly(ethylene terephthalate) as used

Example 8 (187 parts), Sb 2 0 3 (3 parts) and decabromo- in

(10 parts) were intimately mixed together. The diphenyl

mixture was melt spun as homofilaments through a of spinneret (0.015" holes) at 280oC with throughput per minute 10.2g per minute and wind up speed 3,500 fee and and the coloured spun yarn plied up to 30 filaments The drawn over a hot roll and plate as in Example 8.

drawn yarn was knitted up and tested for flammability.

The average char length was 4.75 inches and the average

vurning time was-40 seconds.

Comparative Example

Powdered poly(ethylene terephthalate) as used

in Example 8 (187 parts), Sb 2 0 3 (3 parts) and the diacetate

of tetrabromo-bis phenol A (10 parts) were intimately

mixed together and then spun anddrawn into a homofilament

yarn as in Comparative Example.4. The coloured yarn was

knitted up into a hoseleg and tested for flammability.

The average char length was 5.5 inches and the average

burning time was 43 seconds.

EXAMPLE

Powdered poly(ethylene terephthalate) as used

in Example 8 (163 parts), Sb 2 0 3 (7 parts) and decabromo-

diphenyl (20 parts) were intimately mixed together and the

mixture used to melt spin the core of sheath/core 8, polyethylene terephthalate filaments as in Example

using a wind up speed of

4 6166 3 DG_.. -22-

38,8 79 m

3,500 feet per minute. The sheath/core ratio was 3:2.

The throughputs were 12 gm per minute for the sheaths

and 8 gm per minute for the cores. The yarn was drawn and knitted up into hoselegs and tested for flammability. The average char length was 4.5 inches and the average burning

time was 44 seconds. EXAMPLE 11 Powdered poly(ethylene terephthalate) as used in

Example 8 (178.4 parts), Sb 2 0 3 (5.0 parts) and decabromo- diphenyl (16.6 parts) were intimately mixed together and the mixture used for spinning the core of sheath polyethylene terephthalate core filaments in Example 8, using a wind up speed of 3,500 feet per minute. The sheath/core ratio was 2:3 and the throughputs were 8 gm per minute for the sheath and 12 gm per minute for the core. The yarn which had a superior colour to that of the yarn of comparative example 4 was drawn and knitted up into hose- legs which were tested for flammability. The average char length was 5.5 inches and the average burning time was 44.5 seconds. EXAMPLE 12 Powdered poly(ethylene terephthalate) as used in Example 8 (188 parts), and decabromodiphenyl (12 parts) were intimately mixed together and used to spin the core of sheath/ core filaments. The sheath was spun from a polymer mixture made up by mixing together 190 parts powdered poly(ethylene terephthalate) (as used for the core) and 10 parts antimony trioxide. The sheath/core ratio was 3:2 and the spinning 23 4 6L663

38,8 7 2 /2

were 12 sm per minute for the sheath and 8 throughputs The wind up speed was 3,500 gm per minute for the core.

feet per minute. colour to that of the The yarn which had a superior up into hose- comparative example 4 was drawn and then knitted

for flammability. The average char length legs and tested burning time was 43 seconds. was 5.5 inches and the average EXAMPLE 13 conjugate filaments A yarn consisting of 5 sheath/core spinner, with 60% by weight of was produced using a twin-rod containing 8.0% of decabromo- poly(ethylene terephthalate)

diphenyl as the core, and 40% by weight of 66 nulon containing

as the sheath. The yarn was by weight of antimony trioxide a draw ratio of hot drawn at a temperature of 120°C using properties: to 1 to give a drawn yarn with the following Bromine content 3.72%

Denier 33.5

Tenacity 1.34 g per denier

Extensibility 13.6% 40 filaments, 140 denier The drawn yarn was plied up to tested for flammability. Out of and knitted into hoselegs and

six samples tested, the average char length was 7 inches

52 seconds. and the average burning time was in appearance, The conjugate filament yarn was white dissolve 2.36% by weight whereas when an attempt was made to in 6.6 nylon of the flame-retardant agent (decabromodiphenyl) trioxide) by melt-blending, a (containing 2% of antimony containing 2% of bromin brown and bubbly polymer was obtained 24 461,663

38, 8 72/72

EXAMPLE 14 Powdered poly 1:4 butylene terephthalate (176.8 parts),

3 (5.2 parts) and decabromodiphenyl (18 parts) mixed in a tumbler mixer for 30 minutes. The mixture was used to spin the core of a sheath/core filament at 272°C. The sheath was 4GT polymer and was spun at 270 0 C. The sheath/core ratio was 1.2 (wt/wt). The yarn was spun through a 20 hole spinneret (0.015 inches diam hole) at 271 0 C with a throughput of 11.6 g/min for the core, 5.8 g/min for the sheath and a wind up speed of 3,800 ft/min. The yarns were plied up to provide a 60 filament yarn and drawnover a heated roll at 87 0 C and a hot plate at 160°C to give a drawn yarn dtex of 204 and a tenacity of 2.85

g/dtex, 2% modulus 25.7 g/dtex, extension 16.6% The yarn which was a good white colour was knitted into hoselegs on a 3.5 inch circular knitting machine and tested for flammability by the method described. In contrast, polybutylene terephthalate spun as a homofil and containing 6% by weight of decabromodiphenyl gave undesirably yellowish

coloured fibres. Six samples of the above hose legs were tested and all were found to Vurn totally 10") giving an average burning time for 100 seconds. Six samples of a control

fabric free from decabromodiphenyl were also tested and all these burnt totally giving an average burning time of 74 seconds.

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38, 872 /72

EXAMPLE (180.5 parts) Powdered polyethylene terephthalate (15 parts) were mixec Sb 2 0 3 (4.5 parts) and pentabromotoluene the core of a 1.2 sheath/core together and spun at 280°C as

filament. A 95 mole polyethylene terephthalate, containing 0.05% TiO 2 mole polyethylene adiphate copolymer as the sheath. No fumming of as delustrant was spun at 285°C 14. the additive occurred. Both were spun as in Example give an 80 filament The spun yarn was plied up to roll at 88°C and a hot plate yarn and this drawn over a hot 192 dtex, tenacity at 168°C. The drawn yarn properties were 85.26 g/dtex. 3.99 g/dtex, extension 15.0%, 2% modulus and six samples tested The drawn yarn was knitted up described. The average char for flammability by the method the average burning time l41 length was found to be 5h" and seconds. Comparative Example 6 (187 parts) Sb 2 0 3 Powdered polyethylene terephthalate and (10 parts) were mixed (3 and pentabromotoluene parts) was melt spun as homofilam kneaded for 6 hours. The mixture holes) at 286°C with a through a 3-hole spinneret (0.015" up speed of 3,000 ft/min throughput of 5.5 g/min and a wind f Severe fuming occurred. The spun yarn was plied up to 30 and a hot plate at 185°C. and drawn over a hot roll at 90°C and tested for flammability The drawn yarn was knitted up and the average burning tir The average char length was 5h" 43 seconds.

38,8872 n2

EXAM'PLE 16 Decabromodiphenyl 7.273 kg Sb 2 O03 2.727 kg Magnesium Stearate 100 kg The above mixture was tumbled for Ish our. 500 g paraffin wax was melted and dissolved in 8140 ml of trichloroethylene, added to the above mixture and mixed. The resulting paste was left to dry overnight, sieved

4 61,66 3

3 8 ,87 2n2 through 16, 32, and 72 mesh sieves and pelleted into 1/8

inch diameter pellets.

Sheath/core heterofilaments (2/3 w/w) were spun

from granulated polyethylene terephthalate containing

by weight of Ti02 as delustrant. The above pellets

of decabromodiphenyl were added at a rate of 28 per minute

to the screw feeding the core polymer, and the polyethylene 0 terephthalate was spun at 281-284 C through a 30 hole spinnere

(0.015 inches diameter holes) at a throughput of 7.58

Ib/hr and a wind up speed of 3,100 ft/minute. The spun

yarn was drawn over a hot roll at 89OC and a hot plate at

170°C.

The resulting drawn yarn of 148 dtex contained

4% by weight of decabromodiphenyl and 1.5% by weight of

Sb 2 0 3 and had a 5% modulus of 87 g per dtex, a tenacity

of 4 g per dtex and an extension to break of 17.9%. Six

knitted samples of the yarn were then tested for flammability

by the method described, giving an average char length of

inches and an average burning time of 44 seconds. EXAMPLE 17

Powdered polyethylene terephthalate containing

0.05% Ti02 as delustrant (174 parts), decabromodiphenyl

parts) and Sb2 0 3 (6 parts) were mixed and spun at

288 0 C as the core of a 1:1 sheath/core filament. Powdered

polyethylene terephthalate containing 0.5% Ti02 as

delustrant was spun at 280 0 C as the sheath.

The yarn was spun through a 20-hole spinneret

(0.015 ins diameter hole) with a throughput of 9.5 g/m

for each component and with a wind up speed of 3,500 ft/min.

4 6icsO3

38,872n2

The spun yarn was plied up to give a 60 filament

yarn and this was then rawn over a hot roll at 95 0 C and

a hot plate at 1700C. The drawn yarn properties were 147 dtex, tenacity 3.56 g/dtex, extension 2% modulus 80.5 g/dtex.

The drawn yarn was knitted up on the Chell circular head knitting machine and six samples testes for flammability

by the method described. The averate char length was 43/4" and the average burning time was 41 seconds.

Visual examination of the yarn showed that the yarn was a creamy colour and more acceptable than the corresponding

homofilament which gave an indesirably yellowish coloured fibre.

The words DURAOLAS and TERYLENE are recognized as Registered Trade Marks.

29 4 6663

Claims (4)

38,87 2 72 ARE AS FOLLOWS:- THE CLAIMS DEFINING THE INVENTION

1. A flame-retardant conjugate filament sheath/core relationship, consisting of two components in a a melt extrudable fibre- the sheath component comprising extrudable core forming polymer surrounding a melt flame-retardant adjuvant component containing a reactive as defined. wherein the 2. A filament according to Claim 1, and the core a. sheath is a polyester or a polyamide containing a flame- fibre-forming polyamide or polyester

retardant reactive adjuvant as defined. the 3. A filament according to Claim 1, wherein

flame-retardant adjuvant is a bromo compound.. 3, wherein 4. A filament according to Claim 2 or the flame- the melt extrudable core component containing and the flame- retardant reactive adjuvant is a polyamide the molecule retardant adjuvant is a compound in which benzene rings of the said compound comprises one or more structures or a or one or more condensed benzene ring at combination of said rings and ring structures, structure is least one benzene ring or condensed ring the substituted by at least one halogen group, to any halogen group is in the meta or para position accepting other halogen group or any other dlectron

group, the com- A filament according to Claim 4, wherein each said ring pound contains at least two benzene rings, group selected from being linked to another said ring by a -(CRn2 -S0 20,

-0-(CR 2)m-0- mI 2.

3 4 6166

3 8,872 2 where R is H or alkyl and n is 1 or more and

Rt

m is 2 or more, or where R' is alkyl, aryl or

(CH 2 )p0 where p> 1 and 0 indicates a benzene ring which

may carry a halogen substitutent.

6. ,A filament according to Claim 4 or 5, wherein

at least one of the benzene rings of the molecule contains

at least two halogen groups arranged symmetrically.

7. A filament according to Claim 4, 5 or 6,

wherein the molecule is substituted by one or more

amide-forming groups or polymerisable derivatives thereof.

8. A filament according to Claim 7,'wherein the

amide-forming group is a carboxyl group.

9. A filament according to Claim 7 or 8, wherein

the amide-forming group is attached to the benzene ring

via an alkyl group.

A filament according to any one of Claims

4-9, wherein the benzene ring or condensed ring structure

is substituted by an alkyl group.

11. A filament according to Claim 10, wherein

the alkyl group is methyl.

12. A filament according to Claim 4, wherein

the flame-retardant adjuvant is a bromo compound selected

from the group consisting of:

3,6-dibromodurene

bis(p-bromophenyl)ether

4-bromodiphenyl

2,7 dibromo bis (J carboxy-

ethyl)fluorene

hexabromodiphenyl

4 616 3

38,872/72 13. A filament according to Claim 3, wherein the melt

extrudable core component containing the flame-retardant

reactive adjuvant is a polyester and the reactive adjuvant

is a polymer derived from a brominated dicarboxylic acid

and/or a brominated glycol.

14. 'A filament according to Claim 13, wherein

the reactive adjuvant is poly(hexamethylene 2:5 dibromo

terephthalate) or poly(ethylene 2:7 dibromofluorene 9:9 diproprionate).

A filament according to Claim 3, wherein the

melt extrudable core component containing the flame-

retardant reactive adjuvant is a polyester and the reactive

adjuvant is tetrabromobenzene, pentabromotoluene,

acetylated tetrabromo-bis-phenol-A, decabromodiphenyl or

bis(4-bromophenyl)ether.

16. A filament according to any one of Claim 2-15

containing a metal oxide in the sheath or core components,

or both.

17. A filament according to Claim 16, wherein

the metal oxide is antimony trioxide.

18. A filament according to Claim 16, wherein the metal oxide is titanium dioxide.

19. A filament according to any one of Claims 16-18,

wherein the percentage by weight of the metal oxide contained

in the filament is in the range 0.5 to 5.0% expressed as

metal.

A filament according to any one of Claim 2-19

wherein the core portion contains up to 20% by weight of

the reactive adjuvant.

21. A filament according to any one of Claims 1-20,

4 61,663

3 8,872/72 wherein the cross-sectional area of the filament occupied

by the core component is at least 22. A conjugate filament according to Claim 1, substantially as hereinbefore described with reference

to the examples.

DATED 7th May, 1975.

o PHILLIPS ORMONDE AND FITZPATRICK,

Attorneys for IMPERIAL CHEMICAL INDUSTRIES LIMITED.

42dtC

4 61663

SQ72

461,663