Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Reexamination Certificate
1999-03-25
2001-01-09
Niland, Patrick D. (Department: 1714)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
C264S176100, C264S17800F, C264S184000, C264S205000, C264S211120, C264S211240, C528S044000
Reexamination Certificate
active
06171537
ABSTRACT:
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
2
N(CH
2
)
n
NH
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
2
N(CH
2
)
n
NH
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
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° 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
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
E.I. Du Pont de Nemours and Company
Frank George A.
Niland Patrick D.
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