JP3047102B2 - Polyurethane - Google Patents

Description

The present invention relates generally to polyurethanes, and more particularly to block copolymers of polyurethanes and fluoroalkylsiloxanes. The polyurethane block copolymers can be formulated to be spun in the air or thermoplastic, or they can be formulated to be generally thermoset if desired, or tailored for injection molding or extrusion applications. Can be. Polyurethane-
Not only can fluoroalkylsiloxane copolymers be formulated to be spinnable in air, but they have improved properties over polyurethane homopolymers in features such as solvent resistance, bioresistance, thrombus resistance and tensile strength. Provide properties.

Over the years, numerous approaches have been taken to provide polymers suitable for spinning or molding. Some of these approaches include toughness, good wear resistance,
It generally involves the use and development of polyurethane materials that tend to have desirable properties such as beneficial flexibility and good adhesion. The significance of such properties and many of the many beneficial properties will depend on whether the polyurethane is manufactured as a fiber, molding resin, paint, elastomer or foam. For example, polyurethane typically provides fibers with high modulus, good electrical resistance, high moisture resistance, and an advantageous crystalline structure. Many of these properties are useful in forming so-called spandex fibers containing segmented polyurethane materials. Often they are in the form of poly (urea-urethane) which is very elastic and cannot be easily annealed. Further, they typically must be spun under water or other liquid. Also, to prevent significant transmission of the knit when knitting such fibers under tension, the spandex fibers are typically wrapped around the spandex fibers to provide lubricity during knitting to minimize the consequences of these tensions. Tagron or nylon fiber is wound. At times, it provides fibers that are not as or more resilient than typical spandex segmented polyurethanes, can be knitted with less tension, and can be annealed to remove residual tension if desired. It is desirable. This type of property is particularly desirable for the production of artificial blood vessels from spun fibers.

Moldable polyurethane resins have beneficial properties including excellent hardness, flexibility, abrasion resistance, impact resistance, weather resistance, acid and alkali resistance, and the like. Even though polyurethanes as a whole exhibit these types of beneficial properties, further improvements are required. For example, when attempting to develop a moldable or thermoset polyurethane for medical or surgical use, it is typically less thrombogenic,
And contains improved solvents and biological resistance. It is desirable to provide a polyurethane type material that is particularly resistant to oils and body fluids. There is also a general need for improved tensile strength of polyurethanes.

The invention is for use as a moldable resin or for use as an air-spinnable material, including the ability to spin into fibers that are sufficiently thin to be suitable for spinning vascular and non-woven vascular grafts. Along these lines generally provide improved polyurethanes, including the ability to be tailored. The urethane polymer component of the spinnable block copolymer is formed from a reactant charge that is slightly excess and not isocyanate excess. The copolymer of polyurethane and fluoroalkylsiloxane is a poly (fluorosilicone-urethane) having a skeleton having repeating isocyanate groups and repeating organosiloxane groups.

It is therefore a general object of the present invention to provide improved polyurethane materials and methods for their polymerization and production.

It is another object of the present invention to provide an improved polyurethane that can be spun into very fine filaments in air.

Another object of the present invention is that the fiber can be spun in water if it is simply wound on a bobbin, but the movement of the fiber along the length of the vascular prosthesis results in excessive stretching and its cutting, which makes it nonwoven in water. It is to provide an improved polyurethane which cannot be spun into an artificial blood vessel.

It is another object of the present invention to provide an improved fiber-forming segmented polyurethane that can be spun in combination with the generation of an electrostatic field.

It is another object of the present invention to provide an improved polyurethane material suitable for spinning vascular grafts and the like.

Another object of the present invention is to provide an improved copolymer or block copolymer of a polyurethane and a fluoroalkylsiloxane that exhibits solvent and biological resistance, thrombus resistance, and increased tensile strength when compared to a polyurethane homopolymer. That is.

Another object of the present invention is to provide a poly (fluorosilicone-urethane) that exhibits a controlled solubility that is satisfactory for fiber spinning in air.

These and other objects, features and benefits of the present invention are:
It will be clearly understood from a consideration of the following detailed description.

Polymers according to the present invention can be generally classified as polyurethanes because the backbone contains urethane groups and often urea groups, and those groups are repeating units within the polymer backbone. In its most preferred form, the polymer is a block copolymer of a polyurethane and a fluoroalkylsiloxane so as to provide the polymer with improved physical properties. Without the addition of a fluoroalkylsiloxane, the polymer is a segmented polyurethane homopolymer. Such copolymers are preferably soluble in polar organic solvents, and such as the conditions that occur when winding a fiber extrudate under tension on a mandrel.
It can be extruded through a fine orifice through an elongated continuous fiber or strand that is strong enough to minimize its breakage when subjected to stress conditions and stretched immediately after leaving the orifice. By properly controlling the reactant charge to form a high molecular weight urethane polymer, it is formulated to be fiber-forming or spinnable in air. If a moldable polymer is desired, the reactant charge is designed to form pseudo-crosslinks by allophanate formation and may be performed by formation of chain extended burettes.

The formation of the polyurethane moiety according to the present invention involves reacting the hydroxyl groups of the macroglycol (high molecular weight glycol; hereinafter the same) component with the isocyanate groups of the diisocyanate compound to form a prepolymer. If one wishes to make a poly (fluorosilicone-urethane) copolymer, the prepolymer reactant charge will include a fluoroalkylsiloxane component.

Complete polymerization of the prepolymer is achieved by the addition of the desired chain extender. Typically, when a hydroxyl-terminated fluoroalkyl siloxane is included in the prepolymer charge, one -NCO of the diisocyanate component reacts with the hydroxy group of the macroglycol molecule, and the other -NCO group of the diisocyanate becomes Reacts with hydroxyl groups of the fluoroalkylsiloxane component to form a copolymer. Prepolymerization and chain extension will typically be carried out in the presence of a suitable solvent and under suitable reaction conditions, but especially if the polymer is not extruded into fibers, for example, to synthesize the polymer in block form. If no solvent is required, non-solvent reactions can also be performed.

Although the polymers of the present invention can be prepared in non-solvent systems as is known in the art, they are particularly suitable for fiber spinning applications, especially from high viscosity solvent solutions to porous tubes such as biocompatible vascular prostheses. When it is intended to be used for fiber spinning, it is desirable to produce the polymer in a solvent system. When manufacturing in a solvent,
Polymers are usually synthesized with less than 60% solids.
Above 60% solids, the polymer is difficult to mix due to its high viscosity. The polymer can be synthesized in a single step rather than a multi-step approach of producing a prepolymer and then polymerizing it further with a chain extender. In general, one-step polymerizations form polymers that are uncontrolled in their structure and crystallize differently than polymers prepared by a two-step approach.

Suitable macroglycols for the preparation of the polymers according to the invention are hydroxy-terminated compounds having the general formula HO-R-OH, such as polyesteramides, polycaprolactone or polyacrylates. In the above formula, R is a polyester, polyether, polyolefin, or polycarbonate. A suitable molecular weight range is 200 to 3000 daltons. Tri- or higher functional polyols can be copolymerized with these macroglycols if it is desired to provide a crosslinked thermoset product. Examples of macro glycols are tetramethylene glycol, polyethylene glycol, polypropylene glycol, polyester diol and polycarbonate diol.

The other polyester portion of these macroglycols (R
Part) generally comprises the reaction product of a dihydric alcohol and a dibasic carboxylic acid. Instead of free dicarboxylic acid,
The corresponding dicarboxylic anhydrides or the corresponding lower alcohol esters of dicarboxylic acids or mixtures thereof can also be used in the preparation of the polyester polyol moiety. The dicarboxylic acids may be aliphatic, cycloaliphatic, aromatic and / or heterocyclic, and may be optionally substituted. Dihydric alcohols that can be used include, for example, ethylene glycol, propylene glycol, hexane-1,6-
Diols and diethylene glycol.

The polycaprolactone portion of these macroglycols includes polyesters made by polymerization of lactones, such as e-caprolactone, or by condensation of hydroxycarboxylic acids, e.g., e-hydroxycaproic acid, with starting materials containing hydroxyl groups. . Representative polyether macroglycol moieties include polyethers made from ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, and mixtures thereof. Exemplary polyacrylate macroglycol moieties include dihydroxy functional acrylic copolymers. Representative polyesteramide macroglycol moieties are made by replacing a small amount of the diol used to make the described polyesters with compounds such as ethanolamine, isopropanolamine, ethylenediamine and 1,6-hexamethylenediamine.

The diisocyanate reactant according to the invention has the general formula OCN-
R'-NCO, where R 'is a hydrocarbon, which may include aromatic or non-aromatic structures, including aliphatic and alicyclic structures. Exemplary isocyanates are preferably MDI, i.e. 4,4-methylenebiphenyl isocyanate or
Contains 4,4'-diphenylmethane diisocyanate. Other exemplary isocyanates are hexamethylene diisocyanate and 2,4-tolylene diisocyanate and 2,6
-Tolylene diisocyanate such as tolylene diisocyanate, 4,4'-tolidine diisocyanate, m-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate , 1,1
0-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 3,3'-dimethyl-4,4'-
Includes diphenylmethane diisocyanate, 1,5-tetrahydronaphthalenediisocyanate, and mixtures of such diisocyanates.

When a poly (fluorosilicone urethane) block copolymer is to be prepared, the fluoroalkylsiloxane blocks are typically silanol (Si-OH) terminated monomers, but they may be amine terminated monomers and the like. Such poly (fluoroalkylsiloxane) blocks must have a molecular weight in the range of about 200 to 3000 daltons, and the fluoroalkylsiloxane can have a fluorine content in the range of 1 to saturation. An alkoxy-terminated fluorosilicone or a cyclized fluorosilicone that reacts with a glycol to produce a chain extended hydroxy-terminated fluorosilicone that can react with an isocyanate can also be included in the polyfluoroalkylsiloxanes according to the present invention. Preferably, the polyfluoroalkylsiloxane is a silanol terminated polymethyl-3,3,3-trifluoropropylsiloxane.

The chain extender for completing the polymerization of the prepolymer comprises 2
Or it must have two or more functional groups. A preferred and well-known chain extender is 1,4-butanediol. Generally speaking, most diols or diamines are suitable, including ethylene glycol, propylene glycol, ethylene diamine, methylene dianiline and the like.

As for the solvent, a polar solvent such as dimethylacetamide is included to ensure a complete and homogeneous reaction. Other suitable solvents of generally polar nature include dimethylformamide, tetrahydrofuran, cyclohexanone and 2-pyrrolidone.

Such polar solvents are themselves typically suitable at relatively low fluoroalkylsiloxane reactant levels (on the order of 20% or less), but for high fluoroalkylsiloxane monomer content these solvent When used alone, the resulting polymer tends to become cloudy, but to preserve and optimize solubility,
Such conditions are typically improved by the addition of a common or binary solvent. Exemplary binary solvents include methyl ethyl ketone, acetone, cyclohexanone, and the like.

Other ingredients such as catalysts, antioxidants, and extruders can be included, but if you want a medical grade polymer,
There is a tendency or preference to exclude such components. In this regard, preferred amine-containing solvents, such as dimethylacetamide, tend to catalyze the reaction and nothing else. Such additives may be necessary when the polyurethane solution is not polymerized.

When it is desired to provide a polyurethane copolymer which is a high molecular weight plastic fiber-forming polymer soluble in polar solvents, the ratio of the equivalents of the diisocyanate component to the sum of the equivalents of the hydroxyl and amino group containing components is generally less than 1. There must be. This equivalence ratio results from a reaction charge of active hydrogen excess, not isocyanate excess.
This ratio is the relative isocyanate equivalent weight (from diisocyanate) to the total equivalent weight of active hydrogen-containing groups present from the reaction charge (from the combination of macroglycol, hydroxy functional chain extender, and fluoroalkylsiloxane present). Indicates the ratio. In practice, this ratio is conveniently determined by formulating a reaction charge having a ratio of about 1 or a slight isocyanate excess such that gelation is observed. The charge is then reduced slightly by small increments of the isocyanate charge, and such repetition is continued until gelation is no longer seen. If a non-fibrous polyurethane is desired, this equivalence ratio must be greater than or equal to 1 to form a polymer suitable for injection molding or extrusion. Ratios greater than 1 can form pseudocrosslinks through allophanate formation, and further chain extension can be obtained through the formation of burettes.

The ratio of chain extender to macroglycol plus fluoroalkylsiloxane determines the hardness and modulus of the polyurethane copolymer. At very low ratios, such as below 0.1, the product is gummy; at very high ratios, such as above 10, the product is very crystalline and specific elastomeric. The preferred range for this equivalent day is about 0.5 to about 5.

The main limiting factor for the possible ratio of fluoroalkylsiloxane to the total concentration of macroglycol and fluoroalkylsiloxane is the solubility of the fluoroalkylsiloxane in the polymerization solvent system. It has been discovered that a ratio of 0.1 provides a suitable copolymer of polyurethane and fluoroalkylsiloxane.

Polyurethanes prepared according to the present invention to 50% solids content provide a polymer solution viscosity of about 500,000 to 3,000,000 centipoise. The molecular weight of the polyurethane varies primarily with the ratio of macroglycol to chain extender, with higher ratios of macroglycol and fluoroalkylsiloxane to chain extender yielding higher molecular weights within limits. Typical molecular weight ranges for the polyurethane copolymers according to the invention are from about 50,000 to about 30.
It is of the order of 0,000 daltons, preferably of the order of about 150,000 daltons or more, such molecular weights being determined by measurement with polystyrene standards.

EXAMPLE Using only well-dried or pre-distilled reactants in a dehumidified glove box, 242.57 g of polytetramethylene glycol (molecular weight 658.06) and silanol-terminated polymethyl-3,3,3-trifluoropropylsiloxane (molecular weight 7
35) 30.10 g and 250,000 g of dimethylacetamide were added to a well-dried Erlenmeyer flask. The flask was shaken until the contents were clear and placed in an oven at 95 ° C. for 1 hour. 194.16 g of MDI (molecular weight 250) was added into a disposable bottle and stored in an oven at 43 ° C. for 30 minutes. The solution from the flask was added to the MDI solution and mixed for 1 hour at ambient temperature (about 40 ° C. in a glove box). The reaction color changed from clear to yellow during the reaction. The reaction product was a prepolymer of MDI, polytetramethylene glycol and fluoroalkylsiloxane in dimethylacetamide solution.

The polymerization was terminated by adding a solution containing 33.17 g of 1,4-butanediol (molecular weight 90.00) and 250 g of dimethylacetamide. The butanediol solution was heated to 95 ° C. before adding to the prepolymer, and only half of the solution was added, waiting 30 minutes before adding the remaining solution. After mixing for an additional 30 minutes at ambient temperature, the copolymer is placed in an oven at 70 ° C.
And heated for 2-12 hours.

The resulting copolymer was clear gray and formed fibers in air. After cooling, the polymer became noticeably white, sticky and opaque. Addition of cyclohexanone as a binary solvent or co-solvent for dimethylacetamide as a 50/50 blend tended to increase the clarity of the polymer solution during the reaction. The poly (fluorosilicone / urethane) copolymer exhibited a modulus of Shore 80A, contained 10% equivalents of fluorosilicone relative to equivalents of polytetramethylene glycol, and had 50% solids. The ratio of butanediol to macroglycol plus fluoroalkylsiloxane was 1 and the isocyanate ratio was 0.99.
It was eight.

It will be understood that the described embodiments of the invention are illustrative of some of the applications of the principles of the present invention. Numerous modifications are possible by those skilled in the art without departing from the spirit and scope of the invention.

Claims (8)

(57) [Claims] 1. A reaction product comprising a glycol reactant having a terminal hydroxyl group, a diisocyanate reactant having a terminal isocyanate group, and a poly (fluoroalkylsiloxane) reactant having a terminal hydroxyl group or a terminal amino group. Wherein the glycol reactant is selected from the group consisting of a bifunctional polyester polyol, a bifunctional polyether polyol, a bifunctional polyolefin polyol, a bifunctional polycarbonate polyol, a bifunctional polyesteramide polyol, a bifunctional polycaprolactone polyol and a bifunctional polyacrylate polyol. A poly (fluorosilicone urethane) block copolymer, which is a bifunctional polyol. 2. A reaction product of a glycol reactant having a terminal hydroxyl group, a diisocyanate reactant having a terminal isocyanate group, a poly (fluorosiloxane) reactant having a terminal hydroxyl group or a terminal amino group, and a chain extender. Wherein the glycol reactant comprises a bifunctional polyester polyol, a bifunctional polyether polyol, a bifunctional polyolefin polyol, a bifunctional polycarbonate polyol, a bifunctional polyesteramide polyol, a bifunctional polycaprolactone polyol and a bifunctional polyacrylate polyol. A poly (fluorosilicone urethane) block polymer, which is a bifunctional polyol selected from the group. 3. The poly (fluorosilicone urethane) block copolymer of claim 2, wherein said chain extender is a diol or diamine chain extender. 4. The poly (fluoroalkylsiloxane)
3. The poly (fluorosilicone urethane) block copolymer of claim 1 or 2, wherein the reactant has a molecular weight of 200 to 3000 daltons. 5. The poly (fluorosiloxane urethane) of claim 1 or 2, wherein the equivalent ratio of isocyanate groups to the sum of hydroxyl and amino groups in all reaction components is less than 1 and is fiber-forming in air. Block polymer. 6. The poly (fluorosilicone urethane) block copolymer according to claim 1, wherein the equivalent ratio of isocyanate groups to the total of hydroxyl groups and amino groups in all reaction components is 1 or more, and the composition is thermosetting. 7. A fiber obtained by extruding a solution of the poly (fluorosilicone urethane) block copolymer of claim 5 dissolved in a polar solvent in the air and spinning it. 8. A biocompatible artificial blood vessel made of fibers obtained by extruding and spinning a solution of the poly (fluorosilicone urethane) block copolymer according to claim 1 in a polar solvent.