| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | January 9, 2001 |
| PATENT TITLE |
Preparation of poly (urethaneurea) fibers |
| PATENT ABSTRACT | A process for the preparation of poly(urethaneurea) fibers by reacting a blocked aliphatic diamine with a capped glycol prepolymer, followed by extrusion spinning, is provided |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | March 25, 1999 |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A reaction extrusion spinning process for the manufacture of a poly(urethaneurea) fiber comprising the steps of: (a) contacting a diisocyanate with a polyether diol derived from the group consisting of tetramethylene glycol, 2-methyl-1,4-butanediol, tetrahydrofuran, and 3-methyltetrahydrofuran in a molar ratio of approximately 1.2-2.0:1 to form a capped glycol; (b) contacting the product of step (a) with an aliphatic diamine carbamate under shear in the substantial absence of solvent and at a temperature sufficient to cause reaction of said aliphatic diamine carbamate with said capped glycol to form poly(urethaneurea), wherein said aliphatic diamine is selected from the group consisting of 2-methyl-1,5-pentenediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, m-xylylenediamine, N-methyl-bis(3-aminopropyl)amine, bis(4-aminocyclohexyl)methane, and an aliphatic diamine having the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2, wherein n is an integer of 1-12; and (c) extrusion spinning said poly(urethaneurea) through a spinneret having a diameter of about 0.15-0.41 mm at a temperature above that required in step b and sufficient thermally to reform the poly(urethaneurea) into a fiber having a denier of about 62-1840. 2. The process of claim 1 wherein said diisocyanate is bis(4-isocyanatophenyl)methane. 3. The process of claim 1 wherein the aliphatic diamine carbamate is 1,6-hexamethylenediamine carbamate. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION This invention is related to a reaction extrusion spinning process for the preparation of poly(urethaneurea) fibers. BACKGROUND OF THE INVENTION Poly(urethaneurea) polymers have many uses. For example, such polymers are used to make the fiber known as spandex. As used herein, "spandex" has its customary meaning, that is, a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer comprised of at least 85% by weight of a segmented polyurethane. Poly(urethane-urea) polymers are typically made by forming a prepolymer from a polymeric diol and a diisocyanate, and then reacting this prepolymer ("capped glycol") with a diamine in a solvent. Finally, the polymer solution is forced through a spinneret into a column in which the solvent is evaporated from the solution, forming the fiber. The reaction of the capped glycol with the diamine is often carried out in solution, and the desired fiber is spun from that solution. From an economic standpoint it would be desirable to be able to prepare poly(urethaneureas) in the substantial absence of solvent and, furthermore, to be able either to spin directly into spandex, or to isolate such polymers for later spinning. The use of blocked diamines for making poly(urethaneurea), from which spandex is made, is described in U.S. Pat. No. 5,302,660, showing the preparation of the poly(urethaneureas) in the presence of solvents. U.S. Pat. No. 3,635,908 discloses the use of polyamine carbamates in preparing polyurethaneurea thermoplastic products and the extrusion of films using, for example, screw-type extruders. The pclyurethaneureas are based on an extensive list of polymeric polyols, polyamine carbamates and polyisocyanates. There remains a need for a method of obtaining poly(urethaneurea) of specific compositions which can be extrusion spun into spandex fibers. SUMMARY OF THE INVENTION This invention concerns a process for the manufacture of a poly(urethaneurea) fiber which comprises the steps of: (a) contacting a diisocyanate with a polyether diol in a molar ratio of approximately 1.2-2.0:1 to form a capped glycol; (b) contacting the product of step (a) with a blocked aliphatic diamine under shear in the substantial absence of solvent and at a temperature sufficient to cause reaction of said blocked aiphatic diamine with said capped glycol to form poly(urethaneurea), wherein said aliphatic diamine is selected from the group consisting of 2-methyl-1,5-pentenediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, m-xylylenediamine, N-methyl-bis (3-aminopropyl)amine, bis(4-aminocyclohexyl)methane, and an aliphatic diamine having the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2, wherein n is an integer of 2-12; and (c) extrusion spinning said poly(urethaneurea) at a temperature above that required in step (b) and sufficient thermally to reform the poly(urethaneurea) into a fiber. DETAILED DESCRIPTION OF THE INVENTION The process described herein can be carried out using a blocked aliphatic diamine. The term "blocked" herein means that the amine functions are modified so that they do not react (or the reaction is greatly retarded) with the other functionality (isocyanate) when at lower temperatures, such as ambient temperature, but that at higher temperatures, the blocked functionality "unblocks," i.e., becomes reactive with the other functionality. Such blocked amines are well known in the art. See, for instance, Z. W. Wicks, Jr., Progress in Organic Coatings, vol. 3, p. 73-99 (1975) and U.S. Pat. No. 3,635,908, Canadian Patent 1,004,821, and Czech Patent 203,548, hereby all incorporated by reference. The term "aliphatic diamine" herein means a compound that has amino groups directly bound to an aliphatic or cycloaliphatic carbon atom. There can be other nonreactive functional groups or other hydrocarbyl groups (such as an aromatic ring) present in the aliphatic diamine. The amino groups are either primary and/or secondary amino groups. It is preferred, however, that both amino groups are primary. Preferred aliphatic diamines have the formula H.sub.2 N(CH.sub.2).sub.n NH.sub.2, wherein n is an integer from 2 to 12, preferably 2 to 6, and more preferably 2. Another preferred aliphatic diamine is bis(4-aminocyclohexyl)-methane. Other conventional diamines include, for example, ethylenediamine, hexamethylenediamine, 1,3-propanediamine, 2-methyl-1,5-pentanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, m-xylelenediamine, and N-methyl-bis(3-aminopropyl)amine. An aliphatic diamine can be blocked by a variety of known blocking agents. Preferably, however, the blocked aliphatic diamine is in the form of a carbamate, i.e., the amine "salt" of CO.sub.2. Such carbamates are well known in the art. The term "capped glycol" herein means an isocyanate prepolymer, that is, the reaction product of a polymeric glycol with a diisocyanate. The terms "polymeric glycol" or "polymeric diol" herein mean a polyether, which contains two hydroxyl groups, most commonly end groups, on the polymer. Suitable polyether diols can be homopolymers or copolymers and include those derived from tetramethylene glycol, 2-methyl-1,4-butanediol, tetrahydrofuran, and 3-methyltetrahydrofuran, and copolymers thereof. A preferred polyether diol is polytetramethyleneether diol with a number average molecular weight of 1000 to 5000. Polyurethaneureas made from polyether diols are called polyetherurethaneureas. The diisocyanate can be an aliphatic or aromatic diisocyanate, such as toluene diisocyanate, bis(4-isocyanatophenyl)methane, isophorone diisocyanate, hexamethylene diisocyanate, and bis(4-isocyanatocyclohexyl)methane. A preferred diisocyanate is bis(4-isocyanatophenyl)methane. In the reaction to prepare the capped glycol (prepolymer), an excess of diisocyanate over polyether diol is utilized. Preferably the molar ratio of diisocyanate:polymeric diol is about 1.2 to about 2.0, more preferably about 1.5 to about 1.8. If desired, a monoamine such as diethylamine can be added to control the molecular weight of the final polyurethaneurea. The temperature at which the process of forming a poly(urethaneurea) is carried out is dependent upon the temperature at which the blocked diamine in the process is unblocked and the resulting diamine reacts with a capped glycol. This temperature can vary according to the particular aliphatic diamine, capped glycol, and blocking agent(s) used, but must not be above the temperature at which any of the starting materials or the poly(urethaneurea) product undergo substantial amounts of unwanted decomposition. Typically, this means a temperature below about 250.degree. C. Unblocking temperatures for various combinations of blocking groups and amines are well known in the art or can be readily determined. The term "contacting" herein means that the components are physically contacted with one another. At least at the start of the process, they can be separated within one or more discrete phases. For instance, an aliphatic diamine carbamate can be a solid, while an isocyanate prepolymer (capped glycol) can be a liquid. In any case, it is preferred that the mixture of the components be reasonably homogeneous. Any solids present will preferably have a relatively small particle size. The time necessary to carry out this part of the process can vary with the temperature and will depend on the nature of the particular reactants selected. Such times and temperatures are readily ascertainable to the skilled artisan using routine techniques. Other materials can also be present in the process. For instance, catalysts for the reactions involved, chain stoppers such as (blocked) monoamines which can control the molecular weight of the poly(urethaneurea) formed, antioxidants, and pigments such as TiO.sub.2, can also be present. As indicated above, the process is carried out in the substantial absence of solvent for the starting materials and the polyurethaneurea. The term "solvent" herein means any liquid which can act as a solvent for any one or more of the starting materials or for the product poly(urethaneurea), and which solvent itself is not a reactant or product of the reactions taking place in the process. Small amounts of solvent can be present when needed for convenience. For instance, small amounts of catalyst can be added as a solution. To allow for such small amounts of solvent, the "substantial absence of solvent" shall mean that less than 5% by weight of the total process mixture is solvent. Preferably less than 1% by weight, and more preferably substantially no solvent should be present. During the time in which unblocking and chain extension take place, the process mixture is suitably subjected to shear. The degree of shear or agitation that is required can depend on a variety of factors, but the minimum amount is that required to produce a poly(urethaneurea) polymer which is soluble in a suitable solvent. If insufficient shear is used in the process of this invention, the properties of the product can be adversely affected. For example, gel formation can occur in the absence of shear and deleteriously affect extrusion spinning. The shear required can be produced by known means, for example, by a high-shear mixer. Such high shear mixers include the so-called Atlantic mixer, various sigma-blade-type mixers, Buss.RTM. kneaders, and the like. A particularly useful type of mixer is a reactor-extruder, for example, as described by H. Mark et al., Ed., Encyclopedia of Polymer Science and Engineering, Vol. 14, John Wiley & Sons, New York, 1988, at p. 169-189. A reactor-extruder not only can provide heating and mixing of the process mixture as required, it can also be used to form the product poly(urethaneurea) into a useful shape or form. The poly(urethaneurea) that is formed is soluble in a suitable solvent. A suitable solvent is one in which the particular poly(urethaneurea) that is made is soluble, assuming it is not crosslinked, and which solvent does not cause decomposition or reaction of the poly(urethaneurea). The term "soluble" herein means that, upon dissolution of the poly(urethaneurea), substantially no visible gel (i.e., visible to the naked eye) is formed. The solution formed upon dissolution can be filtered and the residue, if any, on the filter visually inspected for gel. The poly(urethaneureas) produced according to the present invention are particularly useful for preparing spandex fibers. They give fibers with excellent properties, and are relatively easy to form into fibers. Simultaneous with, or just subsequent to the formation of the poly(urethaneurea), the fiber can be extrusion spun from, for example, a reactor-extruder, by heating the polymer to a temperature at which the polymer is reformed. As used herein, extrusion spinning the resulting poly(urethaneurea) means the formation of a fiber. When using blocked chain-extenders such as ethylenediamine dicarbamate or hexamethylenediamine dicarbamate, the polymer forming step requires a temperature sufficient to melt the diamine carbamate, e.g. 150.degree. C. Due to the intermolecular hydrogen bond strength of the resulting urea groups, the polymer reformation step into fiber requires temperatures higher than the formation step, for example, 190.degree. C. Furthermore, due to the material viscosity relationship with temperature, for practical production rates, fiber formation requires temperatures >190.degree. C. The polymer product is thermally labile and intolerant of sustained high temperatures and thus the duration of the fiber formation step should be kept short. Considering the need to bring the reactants to a polymerization temperature first, followed by the need to heat the system further for reforming into fiber, a twin-screw extruder was used, operated with a thermal gradient having the highest temperature at the melt die. Insufficient heating in the reforming step can result in excessive pressure at the extruder die thus stalling the equipment. Excessive heating during the reformation step can result in polymer degradation resulting in fibers with poor physical properties, e.g., low break tenacity and unload power. In the Examples, Type A capped glycol is the reaction product of 1800 number average molecular weight polytetramethyleneether glycol and bis(4-isocyanatophenyl)methane in a ratio of 1.7 moles diisocyanate per mole of polymeric glycol. Type B capped glycol is a like polymer but with a ratio of 1.59 moles diisocyante per mole of polymeric glycol. |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
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