IL27945A - Elastic fibers from mixed diols - Google Patents

Description

Patents Form No. 3 PATENTS AND DESIGNS ORDINANCE.

SPECIFICATION, "ELASTIC FIBERS FROM MIXED DIOLS" I / WE , ????^9... c?^^ a corporation organized and existing under the laws of the State of Delaware,. United States of America,, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described aud ascertained in and by the following statement : - This invention relates to synthetic, linear, segmented polymers. More particularly, this invention relates to synthetic, linear, segmented polymers produced from a mixture of organic diols and to elastic fibers produced therefrom.

In recent years polyurethane polymers, typified structurally by the presence of low-melting, amorphous segments joined to high-melting, crystalline segments, have found wide application in the manufacture of elastic fibers and filaments. Although description of these complex polymers varies greatly, common to all is a polyurethane structure formed by reacting a hydroxy1- terminated polyester or polyether or mixture of the two with an excess of a diisocyanate to give an isocyanate-terminated "prepolymer" which prepolymer is then further joined by reaction of its terminal isocyanate groups with dlfunctional agents having two active hydrogen atoms (as determined by the test described in J, Am. Chem. Soc. l+9,3l8l (1927) known as "extenders", typically diamines, diols or water.

The dihydroxy compounds employed to form the amorphous segments of these previously known segmented elastomers have been either polyether diols, polyester diols or mixtures of polyesters and polyethers. While several of these prior synthetic elastic fibers have found commercial success, they all suffer from one or more serious deficiencies. There are, therefore, constant attempts being made to improve certain properties of these fibers while maintaining acceptable parameters of the other desirable properties. One very important property to be considered in these synthetic elastic fibers is that property called "outcurve modulus". While more fully explained hereinafter, this property may be briefly defined as resistance to inasmuch as when these fibers are used in garments, it is this property which determines the strength of the garment when the fibers are in a relaxed state.

While suggestions have been made heretofore that the diol employed in producing these elastic fibers may be a mixture of diols, there has not been a great deal of activity in that direction since nowhere was it suggested how to regulate the mixture in order to significantly improve the properties of the resulting fibers.

It is an object of this invention to provide a synthetic linear polymer.

It is a further object of this invention to provide a synthetic linear polymer from a certain critical mixture of diols.

It is a further object of this invention to provide an elastic fiber having improved properties.

It is a further object of this invention to provide an elastic fiber from a novel synthetic linear segmented polymer which fiber has improved outcurve modulus.

It is a further object of this invention to provide an elastic fiber composed of a linear segmented elastomer produced from a certain mixture of diols.

Briefly, in accordance with this invention, there is provided a synthetic, linear segmented polymer comprising the reaction product of (A) a random mixture of (I) 20 to 80 mole percent of a first diol selected from the group consisting of polymeric polyether glycols and polymeric polyester glycols having a melting point below about 60°C. and a molecular weight above about llj.00 and (II) 80 to 20 mole percent of a second glycols and polymeric polyester glycols having a melting point below about 60°C. and a molecular weight between about 1+00 and 1000, with (B) an aromatic diisocyanate in a molar ratio of di- isocyanate to total diol of between 1.2 :1 and 2.5:1 to form an isocyanate- terminated polymer and thereafter reacting said isocyanate- terminated polymer with (C) a compound having two active hydrogen atoms selected from the group consisting of diamines and dihydroxy compounds. Further, in accordance with this invention, elastic fibers are spun from these polymers which show unexpected improvement over prior art fibers. The fibers produced from the polymers of the instant invention exhibit an unexpectedly superior outcurve modulus in relation to elastic fibers heretofore known. Nor is this property improvement accomplished at the expense of other properties. Elongation and tenacity of the fibers of this invention remain well above the required minimum. The elastic fibers of the present invention are particularly suitable for almost all commercial adaptations. While the polymers of this invention are generally spun into mono- component fibers, they may also be employed to form conjugate fibers composed of the linear segmented polymer of this invention and another fiber- forming polymer.

As stated above, the polymers of this invention are prepared from a random mixture of a first diol having a molecular weight above about 11+00 and a second diol having a molecular weight between about 1+00 and 1000. It has been found that the mixture must contain certain minimum amounts of each diol in order to give a fiber with the desired property improvement. While not wishing to be bound to any particular theory of operation, it is thought that the unexpected property improve- > in the molecular structure which, in turn, is the result of the random placement of the different size groups, i.e., polyester and/or polyether groups of differing molecular weight, throughout the molecule. In any event, by employing a mixture of diols in accordance with this invention, superior properties are characteristic of the resulting fibers. It has been found that in order to produce these superior properties the dlol mixture must contain at least 20 mole percent of the diol having a molecular weight above about 11+00 and at least 30 mole percent of the diol having a molecular weight between about 1+00 and 1000. The exact reasons for these minimums is not completely understood at this time, however, it is theorized that they correspond to the minimum amount of chain disruption necessary for significant property improvement. The diol mixture is therefore composed of 20 to 80 mole percent, preferably 1+0 to 60 mole percent of a diol having a molecular weight above about ll+OO and 20 to 80 mole percent, preferably 60 to 1+0 mole percent of a diol having a molecular weight between about 1+00 and 1000.

As used herein the term "outcurve modulus" refers to the stress, in grams per denier, at 1 0 percent extension during the second cycle of extension and relaxation at 25°C.

The diol mixture employed in forming the fibers of the present invention is one which is liquid at temperatures below about 60°C, that is, the melting point of both diols is below about 60°C. The diols employed to form the mixture may be polyester diols, polyether diols or mixtures of the two. In fact, in some cases it is preferable to employ a mixture of a polyester diol and a polyether diol. Among the polyester diols which may be mentioned are those prepared by reacting acids, glycols are the polymethylene glycols, e.g., ethylene, propylene, butylene, decamethylene, substituted polymethylene glycols, and cycloaliphatic glycols, such as cyclohexane diol. These glycols may be reacted with the proper molar ratio of aliphatic, cycloaliphatic or aromatic acids or their ester-forming derivatives to produce polymers terminated essentially with hydroxyl groups carboxyl. although the presence of a i^ groups is not detrimental. Suitable acids for preparing polyesters and/or copolyesters are succinic, adipic, suberic, sebacic, isophthalic, terephthalic and other like acids. The alkyl and halogen substituted derivatives of these acids may also be used. Other type polyesters, such as polycarbonates and polyester amides may also be used. Besides the classical polyesters, that is, those formed by reaction of a glycol with an acid, it is also within the purvue of this invention, and indeed sometimes even preferred, to employ a polyester produced by the opening of a lactone ring, for example, caprolactone , by reaction with a glycol. Thus, the polyester diols employed to produce the fibers of this invention may be polycaprolactone, polymethylcaprolactone and the like and copolymers of these polyesters as well as copolymers of these polyesters with the other previously mentioned polyesters. The polyether glycols employed in the polymers and fibers of this invention may be homopolymers or copolymers.

The essential features are that they be difunctional and have a melting point below 60°C. The polyethers are primarily poly (alkyleneoxide ) glycols, such as poly(ethyleneoxide ) glycol and poly (tetramethyleneoxide ) glycol. Some of the oxygens may be replaced with sulphur atoms and/or some of the alkylene groups may be replaced with arylene or cycloaliphatic radicals. Even the compositions may still be copolymers, such as copolyether derived from more than one glycol.

The polyester and polyether diols from which the segmented polymers and elastic fibers of this invention are derived may contain a single type of linkage such as in conventional polyesters and polyethers or they may have more than one type of linkage, as in polyesters or polyethers chain-extended with dilsocyanate or acid anhydride. In such a case, for example, when chain-extended with diisocyanates, an occasional urethane linkage occurs in the polymer chain. The polyester and polyether may be substituted with halogen, alkyl and other similar groups which do not interfere with the subsequent polymerization under the conditions employed.

The mixture of the diols is reacted with an aromatic dilsocyanate, such as p,p '-diphenylmethane dilsocyanate or toluene dilsocyanate. In accordance with this invention the dilsocyanate is employed in a molar ratio of between 1,2:1 and 2.5:1, preferably, 1.1+ :1 and 2.0:1. It has been found that by employing such molar ratios the desired results in terms of elastic and tensile properties of the fiber are obtained. The reaction is frequently effected by mixing the diol mixture and the aromatic dilsocyanate under anhydrous conditions either at room temperature or at a moderately elevated temperature, for example, 70 to 150°C, to form a liquid prepolymer which is an essentially linear polyurethane having terminal isocyanate groups.

Representative of the aromatic diisocyanates that may be mentioned are such materials as m- and p-phenylene dilsocyanate, toluene dilsocyanate, p,p '-diphenyl dilsocyanate and 1,5-naphthalene dilsocyanate, and in this category we include diisocyanate. Many other aromatic diisocyariates suitable for reaction with the diols to yield polyurethane prepolymers capable of being cured to the elastomerlo state are disclosed in the prior art and it is the desire to emphasize that the invention embraces the use of any and all such aromatic diisocya- nates, insofar as th y function to yield fibers having the requisite physical properties.

The prepolymer formed by reaction of the aromatic diisocyanate with the mixture of diols is chain-extended with a compound having two active hydrogen atoms as determined by the test described by ohler in J. Am. Chem. Soc, Volume 1+ * pages 31-81 (I927). In accordance with this invention, these chain-extending agents may be either diols such as ethylene glycol and other like diols, or diamines such as ethylenediamine, propanediamine, hydrazine, l,3-benzenebis (methylamine ) dihydra-zides and the like. Chain-extending agents are well known to the art and it is thought unnecessary to repeat all operable chain-extending agents here. Suffice it to say that any chain-extending agent previously known is operable in the process to produce the fibers of the present invention provided they do not adversely affect the properties of the fiber. The preferred chain-extending agents are ethylene diamine and dihydrazide.

It is generally more convenient to carry out the reaction both for the formation of the prepolymer and the chain-extension reaction in a solution. Any solvent may be employed which is a solvent for and non-reactive with, under the reaction conditions employed, the diols and diisocyanate, the prepolymer product and the chain-extending agent. Illustrative of suitable solvents are dimethylformamide, dimethylacetamide , dimethyl- The temperature of the prepolymerization reaction is not critical to the extent that temperatures as high as 100eC, may be employed. However, when operating under the high temperature there is a greater tendency toward the formation of gel which acts detrimentally on the final fiber properties. It is generally preferred to operate at a temperature of between 2$°C. and 50°C. These same temperatures are ordinarily employed during the chain-extension reaction.

Generally, the chain-extending agent is added to the prepolymer in a stoichiometric amount, that is, about one mole of chain-extending agent for each mole of prepolymer.

However, to prevent cross-linking, it is sometimes necessary to employ enough chain- extending agent to react with all free isocyanate groups, i.e., at least the chemical equivalent of diamine groups to isocyanate groups. Thus, the chain-extending agent is generally added in amounts slightly greater than stoichiometric.

The fibers of this invention are prepared from the polymer solution by dry or wet- spinning. Conventional con-ditions are used for dry- spinning except that the elastic filaments usually have to be talced or lubricated because they tend to be somewhat tacky immediately after extrusion. When wet-spinning, the spinning speeds are usually lower than the dry-spinning speeds, but this procedure has definite advantage when larger denier filaments are being prepared. In wet- spinning, solutions of the polymer, for example, in dimethylformamide or dimethylacetamide, are usually extruded into hot water baths.

In order to more fully describe this invention, the following examples are given by way of illustration. It is are not to be considered limiting in any manner.

EXAMPLE I This is a control example used to indicate the fiber properties obtained from prior art polymers. 300 grams (0.105 mole) of polycaprolactone internally extended with toluene diisocyanate and having a molecular weight of 28 0 is reacted with 51+ .6 grams ( 0.211+ mole) and '-methylene diphenyl diisocyanate in 191 grams of dimethylacetamide for about 1+5 minutes at temperatures within the range of 30 to 50°C. The prepolymer thus formed is added to a solution of 5.95 grams ( 0.1 mole) of ethylenediamine in dimethylacetamide to give a spinning dope containing 15 percent solids. Fibers were wet-spun from this dope and had the properties indicated in Table I.

EXAMPLE II A random mixture of 120 grams ( 0.01+2 mole) of polycaprolactone internally extended with toluene diisocyanate and having a molecular weight of 2850 and 80 grams ( 0.096 mole) of polycaprolactone having a molecular weight of 831+ is reacted with 6I.5 grams ( 0.25 mole) of Ι+,Ι+'-ηκ^ηΥ1®116 diphenyl diisocya-nate in 11+0.8 grams of dimethylacetamide for about 1+5 minutes at 30 to 50°C. The prepolymer thus formed is added to 5. 2 grams ( 0.097 mole) of ethylenediamine in dimethylacetamide to give a spinning dope of 15 percent solids. Fibers were wet- spun from this dope and the properties are given in Table I.

EXAMPLE III A random mixture of 130 grams ( 0.01+5 mole) of polycaprolactone internally extended with toluene diisocyanate and having a molecular weight of 2850 and 0 grams ( 0. 092 mole) of polytetramethylene glycol having a molecular weight of 750 diisocyanate in 138.9 grams of dimethylacetamide for about 60 minutes at 30 to 50°C. This prepolymer is then reacted with 7.66 grams (0.127 mole) of ethylenediamine in dimethylacetamide to give a spinning dope of l8 percent solids. Fiber was wet spun from this dope and fiber properties are given in Table I.

EXAMPLE IV A random mixture of 120 grams (0.01+2 mole) of polycaprolactone internally extended with toluene diisocyanate and having a molecular weight of 2850 and 80 grams (0.131+ mole) of polyethylene glycol having a molecular weight of 600 is reacted with 77.1+ grams (0.31 mole) of 1+,1+ '-methylene diphenyl diisocyanate in 11+9.3 grams of dimethylacetamide for about 60 minutes at 30 to 50°C. The prepolymer thus formed is added to a solution of 7·3 grams (0.12 mole) of ethylenediamine in dimethylacetamide to give a spinning dope of 15 percent solids. Fibers were wet- spun from this dope and had the properties indicated in Table I.

EXAMPLE V A random mixture of 130 grams (0.052 mole) of poly-tetramethylene glycol having a molecular weight of 2507 and 70 grams (0.12 mole) of polycaprolactone having a molecular weight of 550 is reacted with 67.9 grams (0.27 mole) of !+,!+ '-methylene diphenyl diisocyanate in 11+1+.2 grams of dimethylacetamide for 1 hour at 30 to 50°C. The prepolymer thus formed is added to a solution of 5·3ΐ+ grams (Ο.Ο89 mole) of ethylenediamine in dimethylacetamide to give a spinning dope of 15 percent solids.

Fibers were wet- spun from this dope and had the properties indicated in Table I.

EXAMPLE VI polytetramethylene glycol having a molecular weight of 2050 and 50 grams (0.09 mole) of polycaprolactone having a molecular weight of 550 is reacted with 61.5 grams (0.21+ mole) of 1+,1+'-methylene diphenyl diisocyanate in 11+0.8 grams of dimethylacetamide for about 1 hour at 30 to 50°C. The prepolymer thus formed is added to a solution of 6.23 grams (0.101+ mole) of ethylenedlamine in dimethylacetamide to give a spinning dope of 15 percent solids. Fibers were wet- spun from this dope and had the properties indicated in Table I.

TABLE I Tenacity, Elongation Out curve g/d % modulus, g/d Example I .665 52 0.0275 Example II I.II+ 532 0.01+21 Example III . 95 51+3 Ο. Ο368 Example IV .91 552 O.Oij.05 Example V .86 591 0.01+56 Example VI .70 568 0.01+15 It will be apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore, it is not intended to be limited in any way except as indicated In the appended claims.

Claims (10)

HAVING HOW particularly described and ascertained the nature « „ of our said invention and in what manner the same is to he performed, we declare that what we claim is t

1. A process for preparing a synthetic, linear, segmented polymer characterized by reacting (A) a random mixture of (I) 80 to 20 mole percent of a first diol selected from the group consisting of polymeric polyether glycols and polymeric polyester glycols having a melting point below about 60°C. and a molecular weight above about ll+OO and (II) 20 to 80 mole percent of a second diol selected from the group consisting of polymeric polyether glycols and polymeric polyester glycols having a melting point below about 60°C. and a molecular weight between about 1+00 and 1000, with (B) an aromatic diisocyanate in a molar ratio of diisocyanate to total diol of between 1,2:1 and 2.5:1 to form an isocyanate- terminated polymer and thereafter reacting said isocyanate- erminated polymer with . (C) a compound having two active hydrogen atoms and selected from the group consisting of diamines and dihydroxy compounds.

2. The process of Claim 1, characterized in that (I) is a polyester glycol and (II) is a polyether glycol.

3. The process of Claim 1, characterized in that (I) is a polyether glycol and (II) is a polyester glycol.

4. 1+. The process of Claim 1, characterized in that (I) is present in an amount between 2+0 and 60 mole percent and (II) is present in an amount between 60 and 1+0 mole percent.

5. The process of any of Claims 2-1+, characterized in that the aromatic diisocyanate is 1+,1+ '-methylene di- phenyl diisocyanate. ¾

6. The process of any of Claims 2-1+, characterized in that (C) is ethylene-diamine .

7. The process of Claim 1, characterized in that (I) is polytetramethylene glycol and (II) is a polyester. 279^5/2

8. The process of claim 1> characterized n that (∑) Is polyoaprolactone and (II) Is a polyether,

9. * The process f claim 7» characterised In that (II) Is polyoaprolactone,

10. The process of olalm 1 , characterized in that the organic dilsooyanate is k$k*-methylene dlphenyl dilsooyanate and (C) is ethylenedlamine. 11· A process for preparing a synthetic linear, segmented polymer substantially as deeoribed in the herein Examples* 12· Elastic fibers whenever produced by the proeess claimed In any one of the preceding claims*