Lubricious thermoplastic compounds and thermoplastic articles made therefrom

Abstract

Lubricious thermoplastic articles are formed from thermoplastic compounds including (a) thermoplastic elastomer selected from thermoplastic polyurethane, polyether block amide, and combinations thereof; and (b) from about 5 to about 20 weight percent, by weight of the compound, of hydrophilic water-insoluble polymer selected from polyolefin-polyoxyalkylene block copolymer, crosslinked polyvinylpyrrolidone, and combinations thereof. The thermoplastic compounds are capable of providing enhanced lubricity in the thermoplastic articles without significant degradation in mechanical properties such as elongation and tensile strength, as compared to thermoplastic articles formed from the neat thermoplastic elastomer and subjected to the same heat processing history.

Claims

1. A lubricious thermoplastic article formed from a thermoplastic compound comprising: (a) thermoplastic elastomer that is thermoplastic polyurethane; and (b) from about 5 to about 20 weight percent, by weight of the compound, of hydrophilic water-insoluble polymer that is crosslinked polyvinylpyrrolidone; wherein the crosslinked polyvinylpyrrolidone is a powder having a particle size distribution wherein at least 95% of particles have a particle size of less than 250 micrometers; and the crosslinked polyvinylpyrrolidone is crosslinked prior to inclusion into the thermoplastic compound.

2. The article of claim 1, wherein the hydrophilic water-insoluble polymer consists of crosslinked polyvinylpyrrolidone.

3. The article of claim 1, wherein the article has a Relative Dynamic COF of less than about 0.9.

4. The article of claim 3, wherein the article has at least one of a Relative Tensile Strength at Break of greater than about 0.8 and a Relative Elongation at Break of greater than about 0.8.

5. The article of claim 1, wherein the article has a Relative Dynamic COF of less than about 0.6, and wherein the article has at least one of a Relative Tensile Strength at Break of greater than about 1 and a Relative Elongation at Break of greater than about 1.

6. The article of claim 1, wherein the article has a Relative Dynamic COF (Wet) of less than about 0.5, and wherein the article has both a Relative Tensile Strength at Break of greater than about 1 and a Relative Elongation at Break of greater than about 1.

7. The article of claim 1, wherein the thermoplastic compound further comprises one or more additives selected from the group consisting of antimicrobial agents; antioxidants and stabilizers; colorants; radiopaque agents; and combinations thereof.

8. The article of claim 1, wherein the article is a catheter.

9. A method of making the article of claim 1, the method comprising the steps of: (a) providing ingredients comprising the thermoplastic elastomer and the hydrophilic water-insoluble polymer; (b) melt mixing the ingredients to provide the thermoplastic elastomer compound; and (c) forming the thermoplastic elastomer compound to provide the article for the intended use without a subsequent step of applying a lubricity enhancing agent to the article prior to the intended use.

10. The method of claim 9, wherein the step of forming comprises extruding the thermoplastic elastomer compound.

11. The method of claim 9, further comprising the step of inserting the article into a human body.

Description

EMBODIMENTS OF THE INVENTION

(1) In some embodiments, the invention is directed to thermoplastic compounds.

(2) In other embodiments, the invention is directed to thermoplastic articles.

(3) In further embodiments, the invention is directed to methods of making thermoplastic articles.

(4) Required and optional features of these and other embodiments of the disclosed invention are described.

(5) As used herein, the term compound means a composition or mixture resulting from melt mixing, or compounding, a neat polymer resin and at least one other ingredient including but not limited to one or more additives, or one or more other polymer resins, or both.

(6) As used herein, the term formed from (including related terms such as forming) means, with respect to an article (or component of an article) and a thermoplastic material, that the article (or component of the article) is extruded, molded, shaped, pressed, or otherwise made from the thermoplastic material under sufficient heating to enable such forming. As such, the term formed from (including related terms such as forming) means, in some embodiments, the article (or component of an article) can comprise, consist essentially of, or consist of, the material; and, in other embodiments, the article (or component of an article) consists of the material because the article (or component of an article) is, for example, made by an extrusion process or a molding process.

(7) As used herein, the term free of a certain component or substance means, in some embodiments, that no amount of that component or substance is intentionally present, and, in other embodiments, that no functionally effective amount of that component or substance is present, and, in further embodiments, that no amount of that component or substance is present.

(8) As used herein, the term Dynamic COF means the dynamic coefficient of friction of a specimen under wetted conditions as determined according ASTM D1894.

(9) As used herein, the term Elongation at Break means the percent elongation at break of a specimen as determined according to ASTM D412.

(10) As used herein, the term Hardness means the hardness of a specimen as determined according to ASTM D2240. Hardness is reported as Shore A hardness unless specifically identified otherwise.

(11) As used herein, the term, Tensile Strength at Break means the tensile strength at break of a specimen as determined according to ASTM D412.

(12) As used herein, the term Relative Dynamic COF means the ratio of the Dynamic COF for a specimen thermoplastic article formed from a thermoplastic compound including a neat polymer resin and at least one other ingredient relative to the Dynamic COF for a control thermoplastic article formed from the neat polymer resin alone and subjected to the same heat processing history as the thermoplastic compound.

(13) As used herein, the term Relative Elongation at Break means the ratio of the Elongation at Break for a specimen thermoplastic article formed from a thermoplastic compound including a neat polymer resin and at least one other ingredient relative to the Elongation at Break for a control thermoplastic articled formed from the neat polymer resin alone and subjected to the same heat processing history as the thermoplastic compound.

(14) As used herein, the term Relative Hardness means the ratio of the Hardness for a specimen thermoplastic article formed from a thermoplastic compound including a neat polymer resin and at least one other ingredient relative to the Hardness for a control thermoplastic articled formed from the neat polymer resin alone and subjected to the same heat processing history as the thermoplastic compound.

(15) As used herein, the term Relative Tensile Strength at Break means the ratio of the Tensile Strength at Break for a specimen thermoplastic compound including a neat polymer resin and at least one other ingredient relative to the Tensile Strength at Break for the neat polymer resin alone when subjected to the same heat processing history as the specimen thermoplastic compound.

(16) Thermoplastic Articles Formed from Thermoplastic Compounds

(17) Some aspects of the invention are directed to lubricious thermoplastic articles formed from thermoplastic compounds.

(18) According to the invention, lubricious thermoplastic articles are formed from thermoplastic compounds including (a) thermoplastic elastomer selected from thermoplastic polyurethane, polyether block amide, and combinations thereof, and (b) from about 5 to about 20 weight percent, by weight of the compound, of hydrophilic water-insoluble polymer selected from polyolefin-polyoxyalkylene block copolymer, crosslinked polyvinylpyrrolidone, and combinations thereof.

(19) The thermoplastic compounds are capable of providing enhanced lubricity in the thermoplastic articles, while also avoiding significant degradation in mechanical properties such as elongation and tensile strength, as compared to thermoplastic articles formed from the neat thermoplastic elastomer and subjected to the same heat processing history.

(20) In some embodiments, lubricous thermoplastic articles have a Relative Dynamic COF of less than about 0.9. In other embodiments, lubricous thermoplastic articles have a Relative Dynamic COF of less than about 0.8, or less than about 0.7, or less than about 0.65, or less than about 0.6, or less than about 0.55, or less than 0.5.

(21) In some embodiments, lubricous thermoplastic articles have at least one of a Relative Tensile Strength at Break of greater than about 0.8 and a Relative Elongation at Break of greater than about 0.8. In other embodiments, lubricous thermoplastic articles have at least one of a Relative Tensile Strength at Break of greater than about 0.9, or greater than about 0.95, or greater than about 1, and a Relative Elongation at Break of greater than about 0.9, or greater than about 0.95, or greater than about 1.

(22) For example, in some embodiments, lubricous thermoplastic articles have a Relative Dynamic COF of less than about 0.6, and at least one of a Relative Tensile Strength at Break of greater than about 1 and a Relative Elongation at Break of greater than about 1; and, in other embodiments, lubricous thermoplastic articles have a Relative Dynamic COF of less than about 0.5, and a Relative Tensile Strength at Break of greater than about 1 and a Relative Elongation at Break of greater than about 1.

(23) In some embodiments, lubricious thermoplastic articles have an exterior surface, and the exterior surface is free of any secondary lubricity enhancing agent; that is, any lubricity enhancing agent other than or in addition to the hydrophilic water-insoluble polymer compounded with the thermoplastic elastomer to provide the thermoplastic compounds. Secondary lubricity enhancing agents include any lubricity enhancing agent applied to the lubricious thermoplastic articles as a secondary coating.

(24) In some embodiments, lubricous thermoplastic articles are catheters or other medical devices.

(25) Thermoplastic Elastomer

(26) According to the invention, thermoplastic compounds include thermoplastic elastomer (TPE) selected from thermoplastic polyurethane (TPU), polyether block amide (PEBA), and combinations thereof.

(27) Suitable TPE includes conventional or commercially available TPU and PEBA.

(28) As used herein, the terms TPU or polyurethane includes polymers containing urethane (also known as carbamate) linkages, urea linkages, amide, or combinations thereof (i.e., in the case of poly(urethane-urea)s). Thus, thermoplastic polyurethanes of the invention contain at least urethane linkages and, optionally, urea or amide linkages.

(29) In general, suitable TPU can be based on aliphatic chemistries or aromatic chemistries. One or more TPU chemistries can be used as the TPU in the thermoplastic compounds of the present invention.

(30) The term aromatic refers to TPUs derived from mononuclear aromatic hydrocarbon groups or polynuclear aromatic hydrocarbon groups. The term includes those TPUs derived from arylene groups. The term arylene group means a divalent aromatic group.

(31) The term aliphatic refers to TPUs derived from saturated or unsaturated, linear, branched, or cyclic hydrocarbon groups. This term is used to encompass those TPUs derived from alkylene (e.g., oxyalkylene), aralkylene, and cycloalkylene (e.g., oxycycloalkylene) groups, for example. The term alkylene group means a saturated, linear or branched, divalent hydrocarbon group. Particularly preferred alkylene groups are oxyalkylene groups. The term oxyalkylene group means a saturated, linear or branched, divalent hydrocarbon group with a terminal oxygen atom. The term aralkylene group means a saturated, linear or branched, divalent hydrocarbon group containing at least one aromatic group. The term cycloalkylene group means a saturated, linear or branched, divalent hydrocarbon group containing at least one cyclic group. The term oxycycloalkylene group means a saturated, linear or branched, divalent hydrocarbon group containing at least one cyclic group and a terminal oxygen atom.

(32) Non-limiting examples of commercially available TPU include grades of the PELLETHANE brand, such as grade 2363-80AE, available from Lubrizol; and grades of the ELASTOLLAN brand, such as grade 1180A 10, available from BASF. Other commercially available medical grades of TPU also can be used.

(33) In general, PEBA is a block copolymer containing a hard segment of polyamide and a soft segment of polyether.

(34) Non-limiting examples of commercially available PEBA include grades of the PEBAX brand, such as grades 3533 SA01 and 7233, available from Arkema; and grades of the VESTAMID brand available from Evonik. Other commercially available medical grades of PEBA also can be used.

(35) Hydrophilic Water-Insoluble Polymer

(36) According to the invention, thermoplastic compounds include hydrophilic water-insoluble polymer.

(37) Suitable hydrophilic water-insoluble polymer includes polyolefin-polyoxyalkylene block copolymer, crosslinked polyvinylpyrrolidone, and combinations thereof.

(38) While not intending to be limited by theory, it is believed that suitable hydrophilic water-insoluble polymer possesses characteristics, such as certain chemical structure and certain molecular weight, which make it capable of blooming to the surface of a thermoplastic article formed from the thermoplastic compound. It is further believed that, when such blooming occurs, the hydrophilic portion of the hydrophilic water-insoluble polymer becomes available at the surface and thereby provides enhanced lubricity.

(39) Suitable polyolefin-polyoxyalkylene block copolymer includes conventional and commercially available polyolefin-polyoxyalkylene block copolymer.

(40) In some embodiments, the polyolefin-polyoxyalkylene block copolymer is selected from polypropylene-polyoxyethylene block copolymer.

(41) In further embodiments, the polypropylene-polyoxyethylene block copolymer has a molar ratio of polyoxyethylene to polypropylene that is less than about 1:1. For example, in some embodiments, the molar ratio of polyoxyethylene to polypropylene ranges from about 0.6:1 to about 0.9:1.

(42) Non-limiting examples of commercially available polyolefin-polyoxyalkylene block copolymer include grades of the PELESTAT brand, such as grade 300, available from Sanyo. Other commercially available grades of polyolefin-polyoxyalkylene block copolymer also can be used.

(43) Suitable crosslinked polyvinylpyrrolidone includes conventional and commercially available crosslinked polyvinylpyrrolidone, which also may be referred to as crospovidone, crospovidonum, insoluble polyvinylpyrrolidone, and crosslinked PVP.

(44) In some embodiments, the crosslinked polyvinylpyrrolidone is a powder having a particle size distribution wherein at least 95% of particles have a particle size of less than 250 micrometers.

(45) Non-limiting examples of commercially available crosslinked polyvinylpyrrolidone include grades of the KOLLIDON brand, such as grades CL, CL-F, and CL-SF, available from BASF. These different grades of KOLLIDON differ from each other at least in their particles size distributions, bulk densities, and swelling behaviors. Other commercially available grades of crosslinked polyvinylpyrrolidone also can be used.

(46) Optional Other Additives

(47) In some embodiments, thermoplastic compounds include one or more optional additives.

(48) Suitable optional additives include conventional or commercially available plastics additives. Those skilled in the art of thermoplastics compounding, without undue experimentation, can select suitable additives from available references, for example, E. W. Flick, Plastics Additives Database, Plastics Design Library (Elsevier 2004).

(49) Optional additives can be used in any amount that is sufficient to obtain a desired processing or performance property for the thermoplastic elastomer compound and/or the overmolded thermoplastic article. The amount should not be wasteful of the additive nor detrimental to the processing or performance of the thermoplastic elastomer compound and/or the thermoplastic article.

(50) Non-limiting examples of additives suitable for use in the invention include one or more selected from antimicrobial agents; antioxidants and stabilizers; colorants; radiopaque agents; and combinations thereof.

(51) Ranges of Ingredients

(52) Table 1 below shows the acceptable, desirable, and preferable ranges of ingredients for various embodiments of the thermoplastic compounds of the invention in terms of weight percent based on total weight of the thermoplastic compound. Other possible ranges of ingredients for certain embodiments of the disclosed invention are as described elsewhere herein.

(53) Thermoplastic compounds of the disclosed invention can comprise, consist essentially of, or consist of these ingredients. Any number between the ends of the ranges is also contemplated as an end of a range, such that all possible combinations are contemplated within the possibilities of Table 1 as embodiments of compounds for use in the disclosed invention. Unless expressly stated otherwise herein, any disclosed number is intended to refer to both exactly the disclosed number and about the disclosed number, such that either possibility is contemplated within the possibilities of Table 1 as embodiments of compounds for use in the disclosed invention.

(54) TABLE-US-00001 TABLE 1 Ranges of Ingredients in the Thermoplastic Compound (wt. %) Acceptable Desirable Preferable Thermoplastic Elastomer 55-95 65-95 75-95 Hydrophilic Water-Insoluble 5-20 5-20 5-20 Polymer Optional Other Additives 0-40 0-30 0-20

(55) The weight percent ranges identified in Table 1 reflect a fully compounded thermoplastic compound; that is, one not requiring any dilution with additional thermoplastic polymer resin. Nonetheless, using an expected dilution or let-down ratio, it is possible to compute a masterbatch or concentrated form of the present invention that can be used to prepare a thermoplastic compound that includes ingredients in the weight percent ranges identified in Table 1. Accordingly, it is possible to form thermoplastic articles from either a fully compounded approach or a masterbatch/let-down approach.

(56) Processing

(57) Preparation of the thermoplastic compounds of the present invention is uncomplicated once the proper ingredients have been selected. The compounds can be made in batch or continuous operations.

(58) Mixing in a continuous process typically occurs in an extruder that is elevated to a temperature that is sufficient to melt the polymer matrix with addition of all additives at the feed-throat, or by injection or side-feeders downstream. Extruder speeds can range from about 200 to about 700 revolutions per minute (rpm), for example, from about 300 rpm to about 600 rpm. Typically, the output from the extruder is pelletized for later processing.

(59) Generally, subsequent preparation of thermoplastic articles of the present invention also is uncomplicated once thermoplastic compounds of the present invention are provided. For example, thermoplastic articles of the present invention can be made by extrusion, injection molding, blow molding, rotational molding, thermoforming, calendering, and the like.

(60) Processing techniques are described in available references, for example, Dominick V. Rosato et al., Plastics Design Handbook (Springer 2013).

(61) Methods of Making Thermoplastic Articles

(62) Some aspects of the invention are directed to a method of making lubricious thermoplastic articles.

(63) According to the invention, the method includes the steps of (a) providing ingredients comprising the thermoplastic elastomer and the hydrophilic water-insoluble polymer; (b) melt mixing the ingredients to provide the thermoplastic elastomer compound; and (c) forming the thermoplastic elastomer compound to provide the article for the intended use without a subsequent step of applying a lubricity enhancing agent to the article prior to the intended use.

(64) In some embodiments, the step of forming includes extruding the thermoplastic elastomer compound.

(65) In some embodiments, the intended use includes inserting the lubricious thermoplastic article into a human body.

USEFULNESS OF THE INVENTION

(66) It has been found that, by adding certain of hydrophilic water-insoluble polymer as disclosed herein to thermoplastic elastomer such as thermoplastic polyurethane and polyether block amide to provide thermoplastic compounds, the lubricity of thermoplastic articles formed from the thermoplastic compounds can be enhanced while avoiding significant degradation in mechanical properties such as elongation and tensile strength, as compared to thermoplastic articles formed from the neat thermoplastic elastomer and subjected to the same heat processing history.

(67) Accordingly, thermoplastic compounds of the disclosed invention can be used to make any thermoplastic article that requires enhanced lubricity. Thermoplastic compounds of the disclosed invention are especially useful for making thermoplastic articles for biomedical applications, including but not limited to catheters, tubing, connectors, valves, trocars, and the like.

EXAMPLES

(68) Non-limiting examples of thermoplastic compounds of various embodiments of the disclosed invention are provided.

(69) Table 2 below shows sources of ingredients for the thermoplastic compounds of the Examples.

(70) TABLE-US-00002 TABLE 2 Ingredient Description Brand Source Thermoplastic polyurethane PELLETHANE Lubrizol elastomer 2363-80A Thermoplastic polyurethane ELASTOLLAN BASF elastomer 1180A 10 Polyether block amide elastomer PEBAX 3533 SA01 Arkema Polyether block amide elastomer PEBAX 7233 Arkema Polypropylene-polyoxyethylene PELESTAT 300 Sanyo block copolymer Crosslinked polyvinylpyrrolidone KOLLIDON CL-F BASF Crosslinked polyvinylpyrrolidone KOLLIDON CL BASF Crosslinked polyvinylpyrrolidone KOLLIDON CL-SF BASF Radiopaque agent BARIUM SULFATE Multiple

(71) Table 3 below show the formulations and certain properties of the Examples 1 to 4.

(72) TABLE-US-00003 TABLE 3 1 2 3 4 Example Wt. % Ingredients PELLETHANE 2363-80A 90 85 ELASTOLLAN 1180A 10 PEBAX 3533 SA01 90 70 PEBAX 7233 PELESTAT 300 10 15 10 10 KOLLIDON CL-F KOLLIDON CL KOLLIDON CL-SF BARIUM SULFATE 20 TOTAL 100 100 100 100 Properties Hardness (Shore A) 83 84 86 88 Relative Hardness (unitless) 0.95 0.97 1.01 1.04 Tensile Strength at Break 2932 3004 1744 1622 (psi) Relative Tensile Strength 1.07 1.10 0.89 0.91 at Break (unitless) Elongation at Break (%) 336 461 555 511 Relative Elongation at 1.07 1.47 1.09 0.97 Break (unitless) Dynamic COF (unitless) 0.85 0.77 0.196 0.335 Relative Dynamic COF 0.48 0.43 0.12 0.37 (unitless)

(73) Table 4 below show the formulations and certain properties of the Examples 5 to 7.

(74) TABLE-US-00004 TABLE 4 5 6 7 Example Wt. % Ingredients PELLETHANE 2363-80A 90 90 ELASTOLLAN 1180A 10 PEBAX 3533 SA01 90 PEBAX 7233 PELESTAT 300 KOLLIDON CL-F 10 KOLLIDON CL 10 KOLLIDON CL-SF 10 BARIUM SULFATE TOTAL 100 100 100 Properties Hardness (Shore A) 87 88 Relative Hardness (unitless) 1.00 1.01 Tensile Strength at Break 2529 1711 (psi) Relative Tensile Strength 0.92 0.62 at Break (unitless) Elongation at Break (%) 554 554 Relative Elongation at 1.76 1.76 Break (unitless) Dynamic COF (unitless) 0.126 0.11 0.314 Relative Dynamic COF 0.07 0.06 0.20 (unitless)

(75) Table 5 below show the formulations and certain properties of the Examples 8 to 10.

(76) TABLE-US-00005 TABLE 5 8 9 10 Example Wt. % Ingredients PELLETHANE 2363-80A ELASTOLLAN 1180A 10 75 PEBAX 3533 SA01 72 PEBAX 7233 75 PELESTAT 300 KOLLIDON CL-F 5 5 8 KOLLIDON CL KOLLIDON CL-SF BARIUM SULFATE 20 20 20 TOTAL 100 100 100 Properties Hardness (Shore A except * = 86 70 * 86 Shore D) Relative Hardness (unitless) 1.01 1.00 1.02 Tensile Strength at Break 2697 5633 2354 (psi) Relative Tensile Strength 0.89 0.82 1.28 at Break (unitless) Elongation at Break (%) 601 211 542 Relative Elongation at 1.09 0.86 1.04 Break (unitless) Dynamic COF (unitless) 0.535 0.187 0.396 Relative Dynamic COF 0.45 0.87 0.40 (unitless)

(77) Without undue experimentation, those having ordinary skill in the art can utilize the written description, including the Examples, to make and use aspects of the disclosed invention.

(78) All documents cited in the Embodiments of the Invention are incorporated herein by reference in their entirety unless otherwise specified. The citation of any document is not to be construed as an admission that it is prior art with respect to the disclosed invention.

(79) While particular embodiments of the disclosed invention have been illustrated and described, it would be obvious to those skilled in the art that various other modifications can be made without departing from the spirit and scope of the invention. The appended claims are intended to cover all such modifications that are within the scope of the disclosed invention.