CA1068045A

CA1068045A - Flame-resistant modacrylic fibers and filaments having improved thermostability and process for their manufacture

Info

Publication number: CA1068045A
Application number: CA239,954A
Authority: CA
Inventors: Bernd Huber; Hans-Jerg Kleiner
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1974-10-19
Filing date: 1975-10-17
Publication date: 1979-12-11
Also published as: ATA791075A; DE2449469B1; IE41757B1; ES441742A1; BE834668A; FR2288166B1; SE7511679L; CH583785A5; IE41757L; DK467575A; DE2449469C2; NL7512061A; LU73604A1; AT339465B; FR2288166A1; IT1043464B; GB1523914A

Abstract

Abstract of the disclosure:
The invention provides filaments and fibers on the basis of modacrylic polymers wherein the fiber-forming substance com-prises a copolymer of 35 to 85% by weight of acrylonitrile 5 to 45% by weight of vinyl chloride, vinyl bromide, vinyli-dene chloride or a mixture thereof, and 5 to 30% by weight of a carboxyphosphinic acid derivative of the formula

Description

10~8045 Thls invention relates to flame-resistant fibers and fi-laments of copolymers of acrylonitrile with vinyl chloride, viryl br~mide and/or vinylidene chloride, which copolymers are modified with carboxyphosphinic acid derivatives of the formula I

R1 \ X O
/ P - Y - O - C - C = C~2 (I), in which R1 and R2 represent lower alkyl or haloalkyl radicals having at most 8 carbon atoms, R3 is a hydrogen atom or a methyl group, X stands for an oxygen or a sulfur atom and Y
represents a branched or linear alkylene group having from 1 to 6 carbon atoms.
It is general knowledge to render polymers flame-resi-stant by the addition or incorporation of phosphorus-contain-i~g compounds. So far vinyl or all~ phosphonic acid deriva-` tives have been proposed as phosphorus-containingmodifying agents. In German Offenlegungsschrift 2,052,568 carboxylic ; 20 acid derivatives of phosphine oxide are described. U.S.S.R.
Patent 168,438 discloses the use of carboxyphosphonic acid and carboxyphosphinic acid derivatives for the m~nufacture of flame-resistant polystyrene.
It has been observed that the flame resistance of copoly-mers of acrylonitrile with vinyl bromide, vinylidene chloride and/or vinyl chloride can be considerably improved by adding derivatives of phosphine oxide, while the corresponding phos~
phonic acid derivatives practically do not improve the flame 29 resistance by synergism. A drawback of the polymers and espe-

- 2 -;` , ~

.~ . , - ,; . . . ~ . . , ~ ." . , -- -~o68045 cially of the filaments and fibers produced therewith, which have been modified with the phosphine oxide derivatives accord-ing to the process described in German Offenlegungsschrift 2,052,568, is, however, their poor thermostability.
It has now surpr1sing1y been found th~t copolymers of acrylonitrile with vinyl chloride, vinyl bromide and/or vin~ll-dene chloride which have been modified with carboxy-phosphinic acid derivatives and the filaments and fibers of these polymers have a considerably improved thermostability with a comparable flame-resistance. Consequently, the filaments and fibers made from the said polymers have a much lower tendency to turn yel- - -low at elevated temperature than the hitherto known modacrylic `~
filaments and fibers modified with flame retardants. The term modacrylic fibers is intended to include multi-polymer fiber -~
material composed o~ at least 35% by weight and at most 85%
by weight of acrylonitrile units.
The filaments and fibers which have been modified accord-in~ to the invention are obtained by spinning products obtain-ed bYdopolyme~ing~ acrylonitrile and optionally other unsatu-rated compounds having an activated double bond with vinyl chloride, vinyl bromide and/or vinylidene chloride and carboxy-:;
phosphinic acid derivatives according to the above formula I.
; Thecopolymers from which the filaments and fibers are made preferably contain from 5 to 45% by weight of vinyl chloride, vinyl bromide and/or vinylidene chloride units and 5 to 30%
by weight of units derived from compounds of formula I, the ; percentages by weight being calculated on the total polymer.
Filaments and fibers having optimum properties are ob-29 tained from a fiber material prepared by copolymerization of ' ~068045 acrylonitrile and optionally further unsaturated compounds with activated double bond with 10 to 30% by weight of vinyl chloride, vinyl bromide and/or vinylidene chloride and 8 to 20% by weight of carboxy-phosphinic acid derivatives of formula I.
The compounds of formula I are preferably prepared by the process described in Canadian Application No. 239,929 filed concurrently herewith by reacting, for example, an alcohol of the formula II
R ~ X ..
P - Y - OH (II) R2'~
in which Rl, R2, X and Y have the aforesaid meaning with a . stoichiometric amount of an acid halide of the formula III
: .
;~ Z - CO - C = CH2 (III) . 15 R3 in which Z represents a halogen atom and R3 has the aforesaid ; meaning, in an inert solvent, for example toluene, with the addition of equimolecular amounts of a base, for example triethyl amine, and of a polymerization inhibitor at a temperature in the range of from 20 to 50DC. After having filtered off the hydro-chloride formed, the solvent is removed and the product is distil-led under reduced pressure.
: The copolymers used for making the filaments and fibers according to the invention can be prepared, for example, with . 25 the use of the following phosphorus-containing carboxylic acid derivatives of formula I: the acrylic and methacrylic acid esters of the methyl, ethyl, propyl, or isobutyl ester of methyl-..
. -- 4 --~; -~ 06BC)45 hydroxymethyl-phosphinic acid, the methyl, ethyl7 propyl, or isobutyl ester of ethyl-hydroxymethyl phosphinic acid, the isobutyliesters of methyl-2-hydroxyethyl phosphinic acid and propyl-2-hydroxyethyl thiophosphinic acid, the propyl ester Ol pru~yl-2-hyuro~yethyl-phûsphinic a~id, the meth~rl, eth~l, propyl, n-butyl, isobutyl, or pentyl ester of methyl-(2-hydroxy-2-methyl-ethyl)-phosphinic acid, the isobut~l ester of methyl-

3-hydroxypropyl-phosphinic acid and the isopropyl ester of butyl-3-hydroxypropyl-phosphinic acid.
The polymerization of the phosphorus-containing carboxylic acid derivatives of formula I with acrylonitrile and other unsaturated compounds with activated double bond is carried out according to any copolymerizat~on process known for acry-lonitrile, i.e. with the action of ionic, free radical or re- ;~
dox catalysts, either in solution or in dispersion, by solu-tion, bead or precipitation polymerization or by polymerization ; in substance. In general, free radical or redox polymerization is preferred to ionic polymerization which gives lower de-grees of polymerization and lower yields especially in the case of acrylic acid esters.
Suitable catalyst systems are, for example, hydrogen per-oxide, potassium or ammonium peroxo disulfate, dibenzoyl per-oxide, tert. butyl hydroperoxide, di-tert. butyl peroxide, ; .~
and other organic peroxides; diazomethane, azoisobutyric acid dinitrile and derivatives thereof, diazonium and diazo com-pounds, inorganic and organicperoxides in combination with ferrous salts, sodium bisulfite, sulfinic acids,or mercaptans.
The polymerization can also be initiated by radi~al forming 29 radiation.

. .

~068045 As solvents or diluents a great number of organic compounds can be used, for example dimethyl formamide, chlorobenzene, methanol,~ethanol, i-propanol, or acetone. The polymerization is preferably carried out in an aqueous medium. When the polymerization is carried out in neterogeneous ~n~s~ the usu~l emulsifiers and protective colloids can be added.
Suitable comonomers with ac~ivated double bond are, for example the following compounds: acryl amide, acrylic acid, and the esters thereof, vinyl esters and ethers, such as, for example, vinyl acetate, ~inyl stearate, vinyl butyl ether, haloacetic acid vinyl esters such as bromoacetic acid vinyl ester, dichloroacetic acid vinyl ester, trichloroacetic acid vinyl ester, styrene, and maleic imide.
Experiments have shown that filaments and fibers made from polymers obtained by polymeriæation of carboxylic acid der~vatives of the formula I with acrylonitrile alone exhibit a pcor flame resistance. The flame resistance is optimized when halogen containing comonomers such as vinyl chlor~de, vinyl bromide and/or vinylidene chloride are incorporated be-sides acrylonitrile into the polymer. Only under these condi-tions flame-resistant filaments or fibers are obtained.
The polymers obtained are soluble in the solvents known for polyacrylonitrile, for example dimethyl formamide, dimethyl acetamide, dimethyl sulfoxide, or ethylene carbonate. The so-lutions prepared with the aforesaid solvents can be spun by ! .
the known wet spinning processes for polyacrylonitrile, forexample by pressing the polymer solutions through a spinneret into a coagulation bath consisting of the solvent and a non 29 solvent, drawing the filaments formed in further baths, freeing ; ' .

b . ' ~: , . ~ ' ' ..
~ 068(~4S
them from the solvent used and drying the filaments obtained.
Owing to the good thermostability of the polymers of the in-vention they can also be spun into filaments and fibers by a known dry spinning process. Staple fibers are then obtained b~- ~-u~ti~ h~ ~uw h~urdi~ u a ~V~Il p~C~
The following examples illustrate the invention, the parts being by weight unless otherwise stated.
E X A M P ~ E 1:
A one liter steel vessel was continuously charged with 250 ml/hr of a monomer mixture consisting of 71 parts acrylo-~ ~ nitrile, 15 parts vinyiidene chloride and 14 parts ~~ of a compo~nd of the formula ., _ . .. . .. . . ..
CH O O
3 ~ " ll ~ \ / P - CH2 - CH2 - O - C - CH = CH2 ; H3C
250 ml/hr of a solution of 10 g sodium acetate, 15 g sodium methallyl sulfonate and Mohr salt in 1.750 ml water, adjusted to pH 2.5 with sulfuric acid, and ` variable amounts of a solution of potassium peroxodisulfate ` in water and of a solution of sodium disulfite in water.
; The proportion by weight of potassium peroxodisulfate to ~odium disulfite was 1:4. The required amounts were deter-mined by the desired degree of polymerization.
The polymerization was carried out at 55C under pres-sure. The polymer suspension formed was continuously dicharg-ed after a residence time of 1 hour, the conversion obtained 29 amounting to approximately 80%. The polymer was carefully ~ ~ .

~068045 washed and dried.
The relative viscosity was measured at 25C ln a 0.5 polymer solution in dimethyl formamide.
While stirring at O to -20C the polymer was introduced ~nto dime+hy1 formamide and stirring of thQ mi~ture W9Q con-`~ tinued for 30 minutes at 60C. The solution was then filtered and degassed. The spinning solution obtained had a polymer ~` content of 15 to 30% by weight, calculated on the total so-; lution. The solution was spun through a spinneret having 100 - 10 orifices each with a diameter of 80 microns ~nto a coagulating bath consisting of 65~ dimethyl formamide and 35% water and having a temperature of 30C. The filaments obtained were drawn to about 4 times the original length in two further hot baths of diminishing dimethyl formamide content, washed with water and dried on hot godets. ~fter drying, the filaments ., we^e drawn again by 25% of their length. The filaments obtain-ed were then steamed at 110C and a knitted hose was made . , th,refrom on a ciroular knitting machine of Messrs. Velha.
The textile properties of the filaments indicated in the following Table 2 were measured after steaming. The knitted hose obtained was repeatedly washed, dried and its burning behavior was tested on a semi-circle tester according to DIN
54 331.
The thermostability was measured with the pulverulent polymer and the filaments spun therefrom.
... . .
The pulverulent polymer was passed through a sieve and then heated for 2 hours to 150C in a drying cabinet. The fibers were likewise heated to a temperature of 150C for 2 ` 29 hours in a drying cabinet. After heating the brightness was .., ., . ~.

--, .. ~ ~.............................. . .
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iO68045 measured in a reflectance photometer Elrepho of Messrs. Zeiss with a colorimetric filter FMY/C equalized against a calibrat-ed ~gO working standard.
The results obtained are indicated in the following Tables 1 and 2. ~;
E X A M P ~ E S 2 and 3:
; In the manner described in Example 1 further copolymers were prepared and filaments were spun therefrom. The variables and the results obtained are listed in the following Tables 1 and 2.

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:, HOE_74/F 300 ~,CI 68045 The results of the tables show that the thermostability of modacrylic filaments and fibers and of the copolymers from which they are made substantially depends on the type of the phosphorus derivative used. With an approximately equal phos-~norus content irl the c~poly~er the fl~me-resistance ob~ained is practically equal with the use of phosphinic acid derivativ-es and phosphine oxide derivatives but, after heating for a prolonged period of time, the copolymer modified with a phos-phine oxide derivative is strongly colored as distinctly re-sults from the values o~ brightness.

. . .

Claims

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

1. Flame-resistant filaments and fibers of modacrylic polymers in which the filament- or fiber-forming polymer com-prises a copolymer of (a) 35 to 85% by weight of acrylonitrile, (b) 5 to 45% by weight of vinyl chloride, vinyl bromide, vinyl-idene chloride and mixtues thereof, (c) 5 to 30% by weight of a carboxyphosphinic acid derivative of the formula wherein R1 and R2 represent alkyl or haloalkyl radicals having at most 8 carbon atoms, R3 represents a hydrogen atom or a methyl group, X represents an oxygen atom or a sulfur atom, and Y is an alkylene group having from 1 to 6 carbon atoms, or a branched alkylene group having from 1 to 6 carbon atoms, and (d) 0 to 15% by weight of a member of the group of other un-saturated compounds with an activated double bond.

2. Filaments and fibers as claimed in claim 1 in which (c) is present in an amount of from 8 to 20% by weight.

3. Filaments and fibers as claimed in claim 1 or claim 2 in which in (c), in the compound of the given formula, R1 represents CH3, R2 represents , R3 represents H, X represents an oxygen atom and Y represents -CH2-CH2-.

4. Filaments and fibers as claimed in claim 1 or claim 2 in which in (c), in the compound of the given formula, R1 represents CH3, R2 represents , R3 represents CH3, X represents an oxygen atom and Y represents -CH2-.

5. Filaments and fibers as claimed in claim 1 or claim 2 in which (b) is vinylidene chloride.

6. A process for the preparation of flame-resistant filaments and fibers of a modacrylic polymer as defined in claim 1, in which a mixture of (a) 35 to 85% by weight acrylonitrile, (b) 5 to 45% by weight vinyl chloride, vinyl bromide, vinyli-dene chloride, and mixtures thereof, (c) 5 to 30% by weight of a carboxy-phosphinic acid derivative as defined in claim 1, and (d) 0 to 15% by weight of a member of the group of other un-saturated compounds with an activated double bond, is polymerized, the resultant is dissolved in an aprotic sol-vent and the resultant solution is spun into filaments or fibers.

7. A process as claimed in claim 6 in which the poly-merization is carried out in the presence of a catalyst.

8. A process as claimed in claim 6 or claim 7 in which the polymerization is carried out in an aqueous system.