DE1469165A1 - Process for the production of synthetic acrylic fibers or threads containing foams - Google Patents

Description

The invention relates to a method of manufacture of synthetic acrylic fibers or threads «which Contain foams.

Since fibers containing foams have a low apparent specific gravity, the use such fibers or filaments as a variety of bulky or bulky yarns for manufacture has been promoted and favored by various products »

In general, one method is used for obtaining fibers or filaments containing foams by wet spinning considered, in which one mixes a substance with the spinning solution in one step to blow gas through

809811/0933

"" 2 -

reaction with the component in a coagulating bath au produce. With regard to rayon materials so far has been a Process for the production of fibers or filaments containing foams by means of a sodium carbonate-sulfuric acid system generally known, but with regard to synthetic fibers or threads »there is no technically sufficient Production speed was obtained or the product obtained tended to be translucent or cloudy to become, no combination of a polymer! satIpinn solution, a coagulating bath and a propellant or foam-forming agent have been proposed by which this purpose could be successfully achieved.

According to the invention, synthetic acrylic fibers or filaments containing foams can be produced thereby be that at least one isocyanate compound or one type of isocyanate with a spinning solution for the Wet spinning of synthetic acrylic fibers or threads, mixes, which contains essentially no barrels Mix in a coagulating bath, which consists of a water-solvent system consists, weaves to form threads and then the threads.

The expression "synthetic acrylic fibers or threads ¹ *" used in the description denotes synthetic fibers which have been produced from a Pdfermerisat with a content of at least 85 mol # acrylonitrile units.

80981 1/0933

The spinning solution used according to the invention can be acrylic polymerizate dissolved in a solvent and can also from the polymerization of one Monomers exist in a solvent obtained reaction mixture. There is a need that the The spinning solution used in accordance with the invention contains essentially no water. In the presence of some water in the spinning solution, when mixing with isocyanate, not only would the water react with it and isocyanate would be consumed but it could also be spinning due to the foams formed in the spinning solution prior to spinning will be difficult · That for the preparation of the dope Useful solvents can be selected from those commonly found in the dope for hate spinning of synthetic acrylic fibers The solvent used may not contain the solvent have no residue which would react with the isocyanate under the working conditions · Examples of useful Solvents for the preparation of the spinning solution according to the invention are dimethylformamide, diet hy! Formamide, dimethylacetamide, Diethyl acetamide, ethylene carbonate, dimethyl sulfoxide, γ-butylolactone and acetone. The polymer consensus— tration in the spinning solution is 10-27% by weight, preferred wise 15 to 20% by weight.

Isocyanates, which are used as blowing agents or schauublldendeji Agents are used in the method according to the invention, are e.g. tolylene diisocyanate, ßhenyl-

809811/0933

«· 4 · -

isocyanate, ethyl isocyanate, hexamethylenediobocyanate, diphe: nylmethanediisooyanat, haphthylene diisocyanate, nitrodiphenyl diisocyanate and diphenylsulfone diisocyanate, and similar. The amount of isocyanate used is within » half of the range of 0.5-100% by weight, preferably 10-50% by weight, based on the amount of polymer in the Spinning solution · When used in an amount less than 0.5% the intended and desired purpose cannot be achieved, and when the isoyanate is in an amount of If more than 100%, based on the polymer, is used, the spinning solution will generally be gelled. The isocfranate can be mixed with the spinning solution under normal atmosphere and preferably mixed under pressure · If one small amount of water and a substance «like one as a color preventive agent that uses acid in the spinning solution Spinning solution are present and because when isocyanate is mixed with the spinning solution, the Isocjpnat with the substance would react in the dope and form a large amount of foams making spinning extremely difficult, mixing is preferably under one such pressure is applied to prevent or inhibit the formation of foams

In the process according to the invention, a water-solvent system is used as the Koagu-Ii erb ad. as Soap solvents for this B.B. called the following!

809311/0933

Dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, ethylene carbonate _v γ-butylolactone, tetrahydrofuran, acetone, dioxane, methanol, ethanol, butanol, propanol, and thloglycolic acid. If recovery is sought, it is advantageous to use the same solvent as the solvent used for the preparation of the spinning solution as the solvent in the coagulating bath.

If the isocyanate reacts with the water-solvent system, ^{K are} not always immediately "(necessarily ^ foams (carbon dioxide) formed" With reference to the accompanying drawing, FIGS. 1 and 2 explain the zone of direct foaming of the isocyanate-solvent-water -systems. in the drawing, TDI tolylene diisocyanate, phenyl isocyanate PI, DMSO Dimethylsjeflfoxyd and W represent hydrogen · the point P in Flg. 1 denotes a system that a% Tolylendilsocyanat, b, and c ^ Dimethylsplfoxyd% of water. the composition of a system is suitable for immediate foaming at 30 ° 0, is expressed by points which lie within the hatched zone in Fig. -1 · The same applies with respect to Fig. 2 · As can be seen from these figures, dimethyl sulfoxide has a · ability to accelerate the reaction between water and isocyanate. This phenomenon becomes old with reference to the other solvents and iso specified above oyanate observed. These

809811/0933

Fact puts a certain idea about the limit of the amount of solvent contained in the coagulating bath which is used in the method according to the invention · In a coagulating bath with a solution Average content of less than 30% by weight is the speed the reaction between isocyanate in the spinning solution and water in the coagulating bath is insufficient fast as the production or generation speed is low and the use of such a coagulating bath is unsuitable for mass production. Also, the tendency of the product was translucent or to become cloudy, observed.

On the other hand, in a coagulating bath with a solvent content of more than TO % by weight, isocyanate and water react directly with one another to give off carbon dioxide. However, since the coagulating force or strength of molecules in the threads is very weak and the foams would not remain in the threads, it is impossible to obtain the desired product. Accordingly, the amount of solvent contained in the coagulating bath used according to the invention is preferably 30-70% by weight. The temperature of the coagulating bath can vary between 5 β 80 ⁰ O Bchw ^ aken.

The spun thread with pores and skin formed inside it becomes 2 to 7 times its original

809811/0933

Length stretched using the usual stretching method of threads If the stretching amount is less than 2, is the physical property or quality of the product unsatisfactory, while on the other hand, if it is greater than 7 let, the foams inside the threads can disappear. To prevent the foams from disappearing, the threads are preferably stretched after the microstructure the thread is almost fixed and secured

According to a preferred embodiment of the invention it is possible to treat the sutures in a relaxed state by steam before the post-treatment or a finishing treatment, such as drying on the threads after their stretching is carried out Usually the amount or ratio of relaxation will vary

the

the relaxation (ratio / difference between the feed speed and the winding speed of the thread to wtcic "?% speed) between 10 and 30%. By the aluminum version of the steam treatment is possible, the tendency that foams disappear during drying, to reduce"

According to the method of the invention it is possible to produce the desired fibers or threads containing foams, which have a low apparent density and a not too much reduced tensile strength, with the g * · » desired production speed e and

809811/0933

m. ft a »

47
to produce the various products of synthetic acrylic fibers or threads by only slightly changing the existing procedures and conditions for the production of synthetic acrylic fibers or threads by means of wet spinning.

The invention is illustrated by the following examples explained in more detail

example 1

A dimethyl sulfoxide solution was used as the spinning solution with a content of 19% by weight of a copolymer, which contains 95 ♦ 7 mol% of acrylonitrile and 4.3 mol- * methyl acrylate, and 1% by weight of oxalic acid, used which but contained essentially no water (having a viscosity of 207 poise at 25 ° 0). This dope was made Tolylene diisocyanate ^ u & esetzi ^ -Hfid- as a foam-forming Medium or propellant under the overpressure of 2-3 kg / cm ! mixed until the amount thereof is 5% by weight of the spinning solution (26th % By weight of the copolymer).

This spinning solution was spun through a spinneret with openings with a diameter of 0.08 mm into a coagulating bath containing 55 parts of water and 45 parts of dimethyl sulfoxide at a temperature of 25% after the immersion length of the spun threads was 120 cm was made long _f the spun threads from the coagulating bath were made at a whale speed of 3 | | l

BAD ORIGINAL 8 U 9 6 1 I / U 9 3 3

Minute taken out * After the immersion length of the obtained threads was made 50 cm long in ^{water kept at 95-10O 0} O, the obtained threads were stretched to about five times the original length. The stretched filaments, the immersion length was 200 cm made long "were transferred into water of 25 ° C and washed with water · The washed filaments were treated by saturated steam at 100 ⁰ O / *} under a relaxation or relaxation ratio of 25%, the steam- ^{treated threads were heat-treated at 120 0} O for 6 minutes

The longitudinal and cross sections of the in the process dried and unstretched obtained according to this example Fadens are shown in Fig. 3, in which the designations Ebcs. Example, UDF unstretched thread, DF stretched F den and LO mean longitudinal section and TO mean cross-section (the same applies to the further examples below).

The dry tensile strength, dry elongation, knot strength and the bond strength ratio of the final product were 1.92 g / den, 34.5%, 1.17 g / den and 96%, respectively.

Examples 2 to 5

With the exception of the use of the table below I described isocyanates instead of tolylene diisocyanate according to Example 1, when carrying out the im

809811/0933

- ίο -

essentially the same working methods (procedures) and conditions as in Example 1, almost the same products as in Example 1 were obtained. The dry tensile strength and the dry elongation the products obtained are summarized in Table I.

Table I. Dry at
game
No. Dry eye
Isocyanate strength
fe / denj egg) 2 Phenyl isocyanate 1.9 23 3 Ethyl isocyanate 2.3 18th 4th Hexemethylene diisocyanate 1.9 20th 5 Diphenylmethanedi- 1.8
isocyanate 21

The length and cross sections of the unstretched and of the drawn threads are shown in FIG.

Example? 6-11

With the difference that the II in the table below indicated amounts as schmumbildendea with · tel used (Polylendiisocyanat were used, foams were prepared containing filaments essentially according to the same procedures and conditions as in Example 1. "The Trockenfestigk3it and Trockendohnung the obtained Products are also given in Table II. As can be seen from Table II,

809811/0933

. 11 ·

tend the physical properties of the obtained Products deteriorate when the amounts of isocyanate used compared with the amount of polymer are large, as in Examples 10 and 11

Table II Dry train
strength
(K / den) Dry
strain example Additional amount
to IDI * 2.8 36 6th 2 2.5 28 7th 5 2.3 31 8th 15th 1.9 23 9 30th 1.7 19th 10 60 1.4 16 11 80

% By weight of tolylene diisocyanate, "based on the polymer

The longitudinal and cross-sections of the undrawn threads and the drawn threads, which in Examples 6-11 are shown in Tig * 3. As from Fig It can be seen that the formation of foams may be insufficient if the amounts of isocyanate used are low are as in Examples 6 and 7.

example

Hit the deviation that as a spinning solution and as a solvent used in the coagulating bath dimethylformamide and that the concentration of the P <| jnaeripat8 in the

Spinning solution was 22% by weight and the viscosity was bie 25 ° 0 14-5 Poiee was essentially according to the working methods and with the means as described in Example 1, a thread obtained which, as in Pig. 3 under Ex 12 shown, contained foams

Examples 13-21

With the exception that dimethyl sulfoxide contents in the coagulating bath and bath temperatures as in the next » in Table III were used following essentially the same procedures and procedures Conditions as in Example i that include foams Threads as shown in Fig. 3 below Exs 13-21 are obtained

Table III Bath temperature C ⁰ O) example DliSO contents (%) ⁺ 30th 13th 50 45 14th 50 60 15th 50 30th 16 30th 45 17th 30th ÄO 18th 30th 30th 19th O 45 20th O 60 21 O

% by weight of dimethyl sulfoxide "in the coagulating bath

Ö0981 1/0933

The apparent specific gravity of the products obtained from each of the examples given above was within the range of about 0.5-1 »0

809811/0933

Claims (4)

Claims 1. 'Process for the production of foams containing synthetic acrylic fibers or threads, characterized in that that at least one type of isocyanate is mixed with a spinning solution containing essentially no water for wet spinning of synthetic acrylic fibers. mixes or threads, the mixture in one of a water- Solvent system existing coagulating bath spins and stretches the spun threads. 2. The method according to claim 1, characterized in that that / mTndesteno a type of isocyanate derived from the Group of tolylene diisocyanate, phenyl isocyanate, ethyl isocyanate, Hexaethylene diisocyanate, diphenylmethane diisocyanate, Naphthylene diisocyanate, itrddiphenyl diisocyanate and diphenyl sulfone diisocyanate is chosen, in an amount of 0.5 - 100 Gev / · - ^, based on the polymer in the spinning solution, mixes " 3. The method of claim 1 or 2, characterized in that there is used as coagulation bath a system consisting of a solvent from 30-70 wt .-% W _ater and 70-30 wt .-% · 4. The method according to any one of claims 1 to 3 _t, characterized in that the solvent for the coagulating bath at least «one compound from the group of BATH ORIGINAL 809811/0833 Dimethylformamide, diethylformamide, dimethylacetepid, diethylacetamide, Ethylene carbonate, y-butylolactone, tetrahydrofuran, Acetone, dioxane, methanol, ethanol, butanol, propanol and thioglycolic acid used 5. Method according to one of claims 1 to 4, characterized in that that after stretching the spun threads, the stretched threads are relaxed by means of steam in a Condition treated. 6 · Method according to one of claims 1 to 5, characterized characterized in that at least one type of isocyanate in a spinning solution with 10-27 Gev ..-% of an Acrylpolyiierisats, which is at least 85 mol% acrylic acid nitrile units contains, mincht in dimethyl sulfoxide, where the Isooyanate in an amount of 10-15% by weight, based on that Polymer is mixed in the solution, the mixture in one of 50-70% by weight of water and 70-30% by weight of dimethyl sulfoxide existing coagulating bath spins the threads obtained stretches and then treats the stretched threads with steam in a relaxed state 809811/0933