DE2418948A1 - PROCESS FOR THE PRODUCTION OF HARD POLYURETHANE FIBERS - Google Patents

Description

DR. BERG DIPL.-5NG. STAPF

PATENT LAWYERS β MUNICH SO. MAUERKIRCHERSTR. 45 2418948

Attorney file 24 940 April 19, 1974

Be / Sch

MONSANTO COMPANY St. Louis, Missouri 63166 / USA

"Process for the production of polyurethane hard fibers"

The invention "relates to improving the stretching behavior of a permanently conjugated yarn formed by melt-spinning a segmented elastomer Polyurethane is formed with a hard (non-elastomeric) fiber. In particular, the invention relates to certain critical values of the polyurethane leading to less

Gases C-14-54-0145 -2-

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(MW 9t 82 73 »7043 98 3310 Ttlagramnwt BERGSTAPFPATENT MOnchan TELEX 05 24 560 IERG d Bonki Baywixh · Varaiiubank MOnchtn 453100 Pottxdwdci MOndiMi« 53 43

Fractions and accruals or vVicklern lead if the conjugated Yarn is subsequently drawn.

There has recently been reference to conjugating an elastomeric segmented polyurethane with a non-elastomeric one or hard fiber, the view that the resulting melt-spun conjugated yarn must be drawn, before it is suitable for its intended and end use. It was previously not known that such a yarn could be reproduced to produce that at technically practical speeds with an acceptably low number of yarn breaks and winders can be drawn per kg of yarn.

It has now been found that these and other difficulties encountered in the prior art by Stoichiometric settings can be avoided, so that the final polyurethane polymer when it is melt-spun is used, between 1 and 45 and preferably between 1 and 27 microequivalents (yuq) of unreacted isocyanate groups contains per g of polymer, as will be discussed in more detail below.

The invention will be further understood from the following detailed description in conjunction with the accompanying drawing, in which the figure in a schematic representation of the Represents a process for the production of the desired drawn conjugated yarn

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As shown generally in the figure, the conjugate yarn is made through a sequence of operations, most of which are known as such. A polyurethane polymer produced according to the invention is shown as block 20, as will be described in more detail below. The final polyurethane polymer is melted, for example by a screw extruder 22, and the conjugate spinning unit 24 supplied. A hard polymer is located in block 26 before, is melted by means of the screw extruder 28 and also fed to the conjugate spinning unit 24. The two molten polymers are in the spinning unit 24 brought together and as a molten bicomponent filament stream 30 spun. The thread 30 is in Block 32 quenched (cooled to solidification) such as by a cooled air stream to form of solidified spun conjugate thread 34. The spun conjugate thread 34 is then optionally subjected to further processes in block 36, these possibly Procedures performed include such conventional steps as applying a spin finish formulation on the thread, winding the spun thread on intermediate spindles, etc.

The bicomponent thread 34, after having been subjected to the processes in block 36 as desired, becomes a draw zone 38 supplied in which he is in a stretching ratio

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is drawn from at least 2.0 to 1. Usually the draw ratio will be between about 3 and 5 to 1, largely depending on the properties of the hard polymer.

The drawn thread 40 obtained is used in further work processes, which are represented by the block 42, fed where it is wound, twisted and wound, underneath controlled voltage is heated or the like. The processes, as far as described here, with the exception of manufacture and composition of the polyurethane as above shown in block 20 are known to those skilled in the art.

The polyurethanes useful in practicing this invention are formed by taking together (1) polymeric diol with high molecular weight and terminal hydroxyl groups with a molecular weight between Ö00 and 3000 (preferably between 1800 and 2200), (2) a polyol with low molecular weight and (3) a diisocyanate. Small amounts of additives can also, if desired, to be available. Typical additives are stabilizers against light, heat or oxidation, such as hindered ones Phenols j materials for reducing the toughness of the freshly extruded polyurethane polymer, wherein a Typical examples of this are the alkylene-bis-amides are pigments or fillers such as titanium dioxide; or catalysts.

The high molecular weight diol can be a polyether or

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be a polyester. Suitable polyethers include poly (oxyethylene) glycol, Poly- (oxypropylene) -glycol, poly- (1.4-oxyToutylene) -glycol, Poly (oxypropylene) poly (oxyethylene) glycol, etc. Suitable polyesters are obtained by the condensation reaction a dicarboxylic acid with a glycol or from a polymerizable lactone. Preferred polyester derive from adipic, glutaric or sebacic acid, including one or more of these acids with a moderate excess of glycols such as ethylene glycol, 1,4-butylene glycol, Propylene glycol, diethylene glycol, dipropylene glycol, 2,3-butanediol, 1,3-butanediol, 2,5-hexanediol, 1,3-dihydroxy-2,4,4-trimethylpentane or mixtures of such diols are reacted. Suitable polyesters can be made by reacting a polymerizable Lactones such as caprolactone can be made with an initiator such as a glycol.

Many different conventional glycols can be used as the low molecular weight polyol or as a chain extender be used. Typical examples are 1,4-butanediol, Ethylene glycol, propylene glycol and 1,4-B-hydroxyethoxybenzene. The combination of polyol with low molecular weight and diisocyanate is preferably selected in terms of type and amount so that that you have a polyurethane polymer with a melting point according to differential thermal analysis (DTA) in the range from 200 to 235 ° C. The polyol should primarily consist of one or more diols with a molecular weight be composed below 500, although, as explained above,

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it may be desirable to include as part of the polyol a small molar amount of a multi-ionic compound, the three or contains more hydroxyl groups per molecule. In such a case, the last named connection have a molecular weight up to 1500. Amounts up to 0.3 moles of the multifunctional compound per mole of diol High molecular weight can be used, although usually only about 1/10 or less of that amount Control of viscosity must be added. Typical multifunctional polyvalent compounds are glycerine, Trimethylol propane, hexanetriol and the like.

Suitable diisocyanates can be from a variety of grades can be selected such as alicyclic, aromatic, arylaliphatic and aliphatic diisocyanates. Particularly valuable diisocyanates are 2,4-tolylene diisocyanate, 4.4 * -dicyclohexylmethane diisocyanate, 4.4 * -diphenylmethane diisocyanate, (meta- or para-) - xylylene diisocyanate, 1,4-cyclohexane diisocyanate, 1.6-hexamethylene diisocyanate and 1.4-tetramethylene diis ocyanate.

It was found that the improved stretching behavior of the conjugated yarn is achieved when the polyurethane polymer is between 1 and 45 microequivalents unreacted Contains isocyanate groups per g of polymer, measured immediately before spinning. Preferably such a Polyurethane polymer produced by ever

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Moles of high molecular weight diol between 2.2 and 8.5 moles of low molecular weight polyol and a small excess of diisocyanate sufficient to contain between 1 and microequivalents of free isocyanate in the substantially completely reacted polyurethane polymer obtained, measured immediately prior to spinning , to build. Preferably, between 3.0 and 6.5 moles of polyol or chain extenders per mole of high molecular weight diol are used because polymers with less than 3.0 moles of polyol tend to be excessively tacky while those with greater than 6.5 moles tend to be to have lower elastomeric properties. These reagents are preferably combined by first heating a premix of the hydroxyl compounds and then mixing the diisocyanate into the premix. The temperatures of the reagents when mixed in should be above the melting point of all reagents and below about 180 ° C. Temperatures from 90 to 110 ^° C. are preferred. After mixing the reagents, the molten mixture is exothermic, and in the temperature range between 100 and 18O ° C (preferably between 120 and 17O ⁰ C) until the molten mixture solidifies, a time at which the polymerization is not yet completely finished is. The polymerization is continued in the solid state at a temperature or temperatures between room temperature and 180 ^° C. to complete completion. When the content of the unreacted isocyanate group is 1 to 45 (preferably 1 to 30 or less) yuäq isocyanate groups per g of the

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The final polyurethane polymer is reached ready for melt spinning.

example

One mole of poly (butylene adipate), acid number 1.5, hydroxyl number 55, is mixed at a temperature of 100 ⁰ G with 5.34 moles of 1.4-butanediol. The premix obtained is mixed thoroughly with 6.4 mol 4.4 ^{f-diphenylmethane} diisocyanate, for which purpose it is stirred for one minute quickly. The reaction mixture obtained by mechanical mixing is then poured into a heated mold in an oven heated to 130.degree. The reaction mixture solidifies into a polymer with a low molecular weight within two or three minutes. If the oven temperature is then ^{increased to 150 °} C. for 6 minutes, the molecular weight is increased. The polymer is then removed from the oven gehäxelt in flakes of desired size and stored at temperatures below 50 ⁰ C in closed containers.

The procedure of the example is repeated using the Adjusts the amount of diisocyanate so that the content of unreacted isocyanate groups in the polyurethane polymer at the time of spinning several days later has the value given in Table I. The polyurethane polymer was conjugated side by side with nylon 6 (a typical hard polymer) melt-spun at a temperature of 226 C, air quenched, coated with a spin finish, and at a speed of

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- Q -

Recorded 274.3 m per minute. The conjugated thread obtained contains between 20 and ÜOfi polyurethane, for example 50fo. The filament is conventionally drawn at a draw ratio of 4.0 to 1 at a speed of 365.7 meters per minute to produce a crimped, side-by-side conjugate yarn with a drawn denier of about 26. The draw-twist behavior is given in Table I below.

Table I.

Unconverted NCO in the bridge during average spinning, Mäq / g stretch / kg (0.453 kg) threads

0.43

0.20

0.145 0.099 0.041 0.021

At low unreacted isocyanate concentrations the fractions per unit of weight are reduced even further. More than about 0.145 breaks per kg of yarn are off economically unacceptable, while a fraction size of less than 0.041 and preferably less than 0.021 per kg is very desirable in an industrial process.

According to a particularly preferred embodiment of the invention

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a. 60 b. 50 c. 45 d. 40 e. 30th f. 27

- ίο -

This increasingly desirable level of behavior can be achieved by using a polyurethane with about 1 Ms 45 and preferably not more than 30yueq unreacted Isocyanate groups per g of polymer at the time used in spinning. Optimal results are obtained if not more than 27 / eq unreacted isocyanate groups per g of polymer are present at the time of spinning.

Furthermore, it is possible according to the invention, the stoichiometry to control the polyurethane reagents so that the desired content of unreacted isocyanate groups within a reasonable time after the initial formation of the polymer has occurred. This is done by that the stoichiometric ratio is set so that the content of unreacted isocyanate groups (measured 4.8 hours after the reagents are mixed) between 10 and 120 (preferably between 50 and 85) / eq per g of polymer. The amount of unreacted isocyanate groups is then, if necessary, (for example by storing the polymer at room temperature) to a final value at the time of spinning between 1 and 45 / ueq per g lowered. Higher initial values than 120yueq per g of polymer would require an excessively long storage time in order to later achieve acceptable stretching behavior to achieve, while a polyurethane polymer is obtained with lower initial values than 10yuäq per g of polymer would indicate that the melt viscosity is too low for an acceptable

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exhibits spinning behavior. The viscosity can, if necessary, by adding small amounts of a raultifunctional compound having three or more hydroxyl groups as part of the low molecular weight polyol increase. Usually a satisfactory increase in viscosity can be achieved with the addition of very small amounts of the multifunctional Compound such as 0.01 or 0.02 moles of triol per mole of high molecular weight diol. because such small molar amounts of the multi-functional compound used v / ground, the molecular weight of this component should advantageously be relatively high to the To reduce the effect of minor errors in calibration; Molecular weights up to 1500 are suitable. Such multifunctional high molecular weight compounds can be made by Polyethoxylating a triol or by other conventional means Process are produced.

Unreacted isocyanate groups in the narrower preferred one The range from ^ 0 to 85 / eq per g of polymer is characteristic for polymers that have the desired viscosity and that can be spun after a reasonable long storage time at room temperature, resulting in a conjugated yarn with great drawing properties.

In a third embodiment, it is possible according to the invention, vieiaxi a given polyurethane / p of which is to be conjugated spun at the desired degree to be achieved

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to determine stretching behavior, it was found that the unreacted isocyanate content NCO ^ in microequivalents per g of polymer, measured for a few hours Tm, below the polymer sate reagents are mixed can become the minimum polymerisation age in hours T at hemming temperature before spinning to the desired unreacted content of isocyanate groups according to the to achieve the following Gmung

5.75

where X is the desired unreacted isocyanate content for Time of spinning is. X can be between 1 and 45 / ueq per g of polymer are in accordance with the broader range according to this invention, with a markedly superior one Stretching behavior is obtained when X is less than 30. Optimal results are achieved when X is less than 27 is.

The content of unreacted isocyanate groups can by means of different procedures can be determined. Ks now follows, in an exemplary manner, a method for determining it, it is based on adding an excess of dibutylamine in dry toluene to the polymer sample and then the excess of dibutylamine with a standard hydrochloric acid solution to a bromophenol blue end point

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titrated.

The dibutyl reagent is prepared by dissolving about 0.65 g of dibutylamine (Fisher Scientific Co., Catalog No. 1260 or equivalent) in 1 liter of dry toluene, Heagens quality. Bromophenol blue indicator solution is prepared by dissolving 0.04% by weight of bromophenol blue indicator in dry isopropyl alcohol, reagent quality. Thoroughly dried RN ^f -dimetnylacetamide (DuPont solvent quality or equivalent) is provided for this purpose.

4 g of a typical sample of the polyurethane polymer is at the temperature of liquid nitrogen at atmospheric Pressure frozen and finely pulverized using a Spex Freezer Mill, Catalog 6700 or equivalent used.

About 1.0 g of powdered polymer, weighed to a G accuracy of 0.0001 g, is transferred to a clean, dry 125 ml flask. 20 ml dibutylamine reagent and 15 ml dry N.N * - Dimethylacetamide are injected into the Flask transferred. A magnetic bucket that comes with an inert material, such as polytetrafluoroethylene, is placed in the flask and the flask is closed. The flask is then placed on a magnetic stirrer and stirred slowly for 30 minutes. A control becomes manufactured in the same way as described in this paragraph, except that the powdered polymer is omitted

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50 ml of anhydrous isopropyl alcohol is then added to each flask added and the stopper rinsed during this addition. Thereafter, Add 2 ml of bromophenol blue indicator solution to each flask added and with vigorous stirring the materials v / ground titrated in both flasks to a yellow end point, which is stable for 15 seconds, using 0.01 II hydrochloric acid. The unreacted isocyanate (HCO) then corresponds to the formula

(AB) χ Hx 1000 -, sample weight, g

where A is the ml of hydrochloric acid required for the control, B is the ml of hydrochloric acid required for the sample and IT indicate the normality of the hydrochloric acid solution.

In the description and in the claims, the term "hard polymer ^{11 is used} for those melt ver spinnable polymers which are continuously stretched or stretched in the Jjäxige by at least 100 / o by stretching at a temperature between room temperature and 150 ^{0 C in spun fiber form} and which in essentially fully stretched form have a maximum further elongation of 80 $ before breakage, this further elongation being essentially fully recoverable after the stress has been removed (springback) $ 100

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subjected to their initial length and then relaxed, stretched or stretched by at least 100 ^ before breakage. The various nylons or polyamides are suitable for typical hard polymers; the polyesters such as polyethylene terephthalate; and the polyolefins, such as polyethylene and polypropylene «

In summary, the present invention provides a conjugated elastomeric polyurethane Hartfasergarn, which is critical stoichiometry in the production of Polyurethanpolymerisats improv ^ x ¹ U is concerned, the latter being prepared by reacting a diol with a high Llolekulargewicht, a diol having a low Liolekulargewicnt and a diisocyanate is reacted in such a way that the poljmrethane obtained contains 1 to 45 (preferably 1 to 27) microequivalents of unreacted isocyanate groups per g of polymer at the time of melt spinning.

-Pat ent claims-

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Claims (3)

- 16 patent claims: 1. Process for improving the stretching behavior of conjugated Threads of a hard polymer and an elastomeric polyurethane, which is the reaction product of a diol with a molecular weight between 800 and 3000, a diol with a molecular weight below 500 and a diisocyanate is, by g-e denotes that one a polyurethane is used which has a content of unreacted isocyanate groups between 1 and 45 microequivalents has per g of polymer when it is with the hard polymer is fed to a conjugate spinning system to form conjugate threads. 2. The method according to claim 1, characterized that a polyurethane polymer is used which contains the reaction product from 2.5 to 8.5 mol of diol contains a lower molecular weight than 500 per mole of diol with a higher molecular weight and sufficient diisocyanate, that 4.8 hours after their reaction a polymer is present that contains more than 45 and "up to 120 microequivalents of unreacted isocyanate groups per g of polymer and that the polymer is stored at room temperature until the content of unreacted isocyanate groups to 1 to 45 microequivalents is reduced. 3. The method according to claim 2, characterized -17-409844 / 0927 draws that a diol with a higher molecular weight is used, which is the reaction product of adipic acid and 1,4-butanediol and that the diol with lower molecular weight is 1,4 ^{-butanediol and that the diisocyanate is 4.4 f -diphenylmethane diisocyanate.} 409844/0927 Lee rs * e i t e