Lubricating thermoplastic compounds and thermoplastic articles made therefrom

Abstract

The present invention relates to lubricated thermoplastic compounds and thermoplastic articles made therefrom. The thermoplastic compound comprises: (a) a thermoplastic elastomer selected from the group consisting of thermoplastic polyurethanes, polyether block amides, and combinations thereof; and (b) from 5% to 20% by weight, based on the weight of the compound, of a cross-linked polyvinylpyrrolidone insoluble in water; wherein the article is a medical device; the crosslinked polyvinylpyrrolidone is a powder having a particle size distribution wherein at least 95% of the particles have a particle size of less than 250 microns. The thermoplastic complexes are capable of providing enhanced lubricity in thermoplastic articles without significant reduction in mechanical properties, such as elongation and tensile strength, compared to thermoplastic articles formed from pure thermoplastic elastomers and subjected to the same heat treatment history.

Description

[0001] This application is a divisional application of a patent application for "Lubricated Thermoplastic Compounds and Thermoplastic Articles Made Therefrom" with application number 202080009044.4, which is the application after the PCT international application with international application number PCT / US2020 / 012544 and international filing date of January 7, 2020, enters the Chinese national phase.

[0002] Priority Claim

[0003] This application claims the priority benefit of U.S. Provisional Application Serial No. 62 / 792,497, Attorney Docket No. 12019006, filed on January 15, 2019, which is hereby incorporated by reference in its entirety. Technical Field

[0004] The present invention relates to thermoplastic compounds that can be formed into thermoplastic articles with improved lubricity without a significant decrease in the required mechanical properties, making the thermoplastic articles particularly suitable for manufacturing thermoplastic articles for biomedical applications (e.g., catheters). Background Art

[0005] There is a need for medical devices such as catheters. Typically, catheters are made of polymeric materials that can provide a combination of biological, chemical, and physical properties that are necessary or desirable for in vivo biomedical applications. Important properties include biocompatibility, anticoagulability, good mechanical properties, and ease of processing. Another important property is surface lubricity, which enables the catheter to be easily inserted into and removed from the body.

[0006] Typically, improved surface lubricity of catheters is provided by methods involving applying a hydrophilic coating to the outer surface of the catheter or some other form of surface treatment. This method is problematic for at least two reasons. First, the method is not cost-effective because it involves secondary processing outside of the molding of the catheter itself (e.g., by extrusion). Second, the coating applied to the catheter surface may exhibit poor durability and is prone to wear during the processing, handling, and / or use of the catheter.

[0007] In U.S. Patent Application Publication No. 2007 / 0287800, which was granted to Acquarulo et al. and assigned to Foster Corporation (“Foster”), attempts were made to provide increased surface lubricity in a catheter by methods other than surface coating. Foster discloses a lubricious polymer blend that is a blend of certain hydrophilic polymers (e.g., polyethylene glycol) and certain thermoplastic resins (e.g., thermoplastic polyurethane). Although Foster discloses that the coefficient of friction of the blend is lower than that of the base resin used alone, Foster also points out that, unfortunately, certain mechanical properties of the blend are significantly worse than those of the base resin used alone. SUMMARY OF THE INVENTION

[0008] Accordingly, there is a need for a thermoplastic blend that can provide enhanced lubricity in a thermoplastic article (such as a catheter) without the drawbacks of secondary processing or surface coating, while also avoiding a significant decrease in mechanical properties such as elongation and tensile strength.

[0009] The above need is met by one or more aspects of the disclosed invention.

[0010] One aspect of the invention is a lubricious thermoplastic article formed from a thermoplastic blend comprising: (a) a thermoplastic elastomer selected from thermoplastic polyurethane, polyether block amide, and combinations thereof; and (b) a water-insoluble hydrophilic polymer in an amount of from about 5 wt% to about 20 wt% based on the weight of the blend, the water-insoluble hydrophilic polymer selected from: polyolefin-polyoxyalkylene block copolymers, crosslinked polyvinylpyrrolidone, and combinations thereof.

[0011] Another aspect of the invention is a method of preparing a thermoplastic article disclosed herein for a desired use. The method comprises the steps of: (a) providing a composition comprising a thermoplastic elastomer and a water-insoluble hydrophilic polymer; (b) melt blending the composition to provide a thermoplastic elastomer blend; and (c) forming the thermoplastic elastomer blend to provide an article for the desired use without a subsequent step of applying a lubricity enhancer to the article prior to the desired use.

[0012] The features of the invention will become apparent with reference to the following embodiments. There are various variations of the features mentioned in the above aspects of the disclosed invention. Additional features may also be incorporated into the above aspects of the disclosed invention. These variations and additional features may exist alone or in any combination. For example, the various features discussed below in connection with any aspect of the invention may be incorporated into any aspect of the invention individually or in any combination. DETAILED DESCRIPTION

[0013] In some embodiments, the present invention relates to a thermoplastic blend.

[0014] In other embodiments, the present invention relates to a thermoplastic article.

[0015] In other embodiments, the present invention relates to a method for manufacturing a thermoplastic article.

[0016] The essential and optional features of these and other embodiments of the disclosed invention are described.

[0017] As used herein, the term "blend" refers to a composition or mixture obtained by melt mixing or compounding a pure polymer resin and at least one other component, where the at least one other component includes, but is not limited to, one or more additives and / or one or more other polymer resins.

[0018] As used herein, the term "molded from" (including related terms such as "formed"), in relation to an article (or article part) and a thermoplastic material, means that the article (or article part) is extruded, molded, shaped, pressed, or otherwise made from the thermoplastic material under conditions of sufficient heating to enable such formation. Thus, in some embodiments, the term "molded from" (including related terms such as "formed") means that the article (or article part) may contain the material, consist essentially of the material, or consist of the material; and, in other embodiments, the article (or article part) consists of the material because the article (or article part) is made, for example, by extrusion processing or injection molding processing.

[0019] As used herein, in some embodiments, the term "free of" a certain component or substance means that the amount of that component or substance is not present in a deliberate manner, and in other embodiments, the term means that no functionally effective amount of that component or substance is present, and in other embodiments, the term means that no amount of that component or substance is present.

[0020] As used herein, the term "dynamic COF" refers to the dynamic coefficient of friction of a specimen measured under wet conditions in accordance with ASTM D1894.

[0021] As used herein, the term "elongation at break" refers to the elongation at break of a specimen measured in accordance with ASTM D412.

[0022] As used herein, the term "hardness" refers to the hardness of a specimen measured in accordance with ASTM D2240. Unless otherwise specified, the hardness is recorded as Shore A hardness.

[0023] As used herein, the term "tensile strength at break" refers to the tensile strength at break of a specimen measured in accordance with ASTM D412.

[0024] As used herein, the term "relative dynamic COF" refers to the ratio of the dynamic COF of a test thermoplastic article formed from a thermoplastic blend comprising a pure polymer resin and at least one other component to the dynamic COF of a control thermoplastic article formed from only the pure polymer resin and having undergone the same thermoprocessing history as the thermoplastic blend.

[0025] As used herein, the term "relative elongation at break" refers to the ratio of the elongation at break of a test thermoplastic article formed from a thermoplastic blend comprising a pure polymer resin and at least one other component to the elongation at break of a control thermoplastic article formed from only the pure polymer resin and having undergone the same thermoprocessing history as the thermoplastic blend.

[0026] As used herein, the term "relative hardness" refers to the ratio of the hardness of a test thermoplastic article formed from a thermoplastic blend comprising a pure polymer resin and at least one other component to the hardness of a control thermoplastic article formed from only the pure polymer resin and having undergone the same thermoprocessing history as the thermoplastic blend.

[0027] As used herein, the term "relative elongation strength at break" refers to the ratio of the elongation strength at break of a test thermoplastic blend comprising a pure polymer resin and at least one other component to the elongation strength at break of the pure polymer resin when it has undergone the same thermoprocessing history as the thermoplastic blend.

[0028] Thermoplastic article formed from a thermoplastic blend

[0029] Some aspects of the present invention relate to lubricated thermoplastic articles formed from thermoplastic blends.

[0030] According to the present invention, a lubricated thermoplastic article is formed from a thermoplastic blend comprising: (a) a thermoplastic elastomer selected from thermoplastic polyurethanes, polyether block amides, and combinations thereof; and (b) a water-insoluble hydrophilic polymer in an amount of from about 5 wt% to about 20 wt% based on the weight of the blend, the water-insoluble hydrophilic polymer being selected from: polyolefin-polyalkylene oxide block copolymers, crosslinked polyvinylpyrrolidone, and combinations thereof.

[0031] Compared to a thermoplastic article formed from a pure thermoplastic elastomer and subjected to the same heat treatment history, the thermoplastic composition can provide enhanced lubricity in the thermoplastic article while also avoiding a significant decrease in mechanical properties such as elongation and tensile strength.

[0032] In some embodiments, the relative dynamic COF of the lubricated thermoplastic article is less than about 0.9. In other embodiments, the relative dynamic COF of the lubricated thermoplastic article is 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.

[0033] In some embodiments, the lubricated thermoplastic article has at least one of the following properties: a relative tensile strength greater than about 0.8 and a relative elongation at break greater than about 0.8. In other embodiments, the lubricated thermoplastic article has one of the following properties: a relative tensile strength greater than about 0.9, or greater than about 0.95, or greater than about 1 and a relative elongation at break greater than about 0.9, or greater than about 0.95, or greater than about 1.

[0034] For example, in some embodiments, the lubricated thermoplastic article has a relative dynamic COF of less than about 0.6 and has at least one of the following properties: a relative tensile strength greater than about 1 and a relative elongation at break greater than about 1; and in other embodiments, the lubricated thermoplastic article has a relative dynamic COF of less than about 0.5 and has a relative tensile strength greater than about 1 and a relative elongation at break greater than about 1.

[0035] In some embodiments, the lubricated thermoplastic article has an outer surface, and the outer surface does not contain any second lubrication enhancer; that is, any lubrication enhancer other than the water-insoluble hydrophilic polymer compounded with the thermoplastic elastomer to provide the thermoplastic blend. The second lubrication enhancer includes any lubrication enhancer applied as a second coating to the thermoplastic article.

[0036] In some embodiments, the lubricated thermoplastic article is a catheter or other medical device.

[0037] Thermoplastic elastomer

[0038] According to the present invention, the thermoplastic blend includes a thermoplastic elastomer (TPE) selected from thermoplastic polyurethane (TPU), polyether block amide (PEBA), and combinations thereof.

[0039] Suitable TPEs include conventional or commercially available TPUs and PEBAs.

[0040] As used herein, the term "TPU" or "polyurethane" includes polymers containing urethane (also known as carbamate) bonds, urea bonds, amides, or combinations thereof (i.e., in the case of poly(urethane-urea)). Thus, the thermoplastic polyurethane of the present invention contains at least urethane bonds and optionally urea bonds or amide bonds.

[0041] Typically, suitable TPUs can be based on aliphatic chemicals or aromatic chemicals. In the thermoplastic blend of the present invention, one or more TPU chemicals can be used as the TPU.

[0042] The term "aromatic" refers to a TPU derived from a mononuclear aromatic hydrocarbon group or a polynuclear aromatic hydrocarbon group. This term includes those TPUs derived from arylene groups. The term "arylene" refers to a divalent aromatic group.

[0043] The term "aliphatic" refers to a TPU derived from a saturated or unsaturated, straight-chain, branched, or cyclic hydrocarbon group. For example, this term is used to cover those TPUs derived from alkylene groups (e.g., oxyalkylene), aralkylene groups, and cycloalkylene groups (e.g., oxycycloalkylene). The term "alkylene" refers to a saturated, straight-chain or branched divalent hydrocarbon group. Particularly preferably, the alkylene is oxycycloalkylene. The term "oxyalkylene" refers to a saturated, straight-chain or branched divalent hydrocarbon group having a terminal oxygen atom. The term "aralkylene" refers to a saturated, straight-chain or branched divalent hydrocarbon group containing at least one aromatic group. The term "cycloalkylene" refers to a saturated, straight-chain or branched divalent hydrocarbon group containing at least one cyclic group. The term "oxycycloalkylene" refers to a saturated, straight-chain or branched divalent hydrocarbon group containing at least one cyclic group and a terminal oxygen atom.

[0044] Non-limiting examples of commercially available TPUs include those under the PELLETHANE brand from Lubrizol Corporation, such as grade 2363 - 80AE; and those under the ELASTOLLAN brand from BASF Corporation, such as grade 1180A 10. Other commercially available TPU grades may also be used.

[0045] Generally, PEBA is a block copolymer containing polyamide hard segments and polyether soft segments.

[0046] Non-limiting examples of commercially available PEBA include those under the PEBAX brand from Arkema, such as grade 3533SA01 and grade 7233; and those under the VESTAMID brand from Evonik. Other commercially available PEBA grades may also be used.

[0047] Water-insoluble hydrophilic polymer

[0048] According to the present invention, the thermoplastic blend comprises a water-insoluble hydrophilic polymer.

[0049] Suitable water-insoluble hydrophilic polymers include polyolefin-polyoxyalkylene block copolymers, crosslinked polyvinylpyrrolidone, and combinations thereof.

[0050] Without being bound by theory, it is believed that suitable water-insoluble hydrophilic polymers have characteristics such as certain chemical structures and certain molecular weights that enable them to bloom on the surface of thermoplastic articles formed from thermoplastic blends. It is also believed that when such blooming occurs, the hydrophilic portions of the water-insoluble hydrophilic polymers become available at the surface, thereby providing enhanced lubricity.

[0051] Suitable polyolefin-polyalkylene oxide block copolymers include common commercially available polyolefin-polyalkylene oxide block copolymers.

[0052] In some embodiments, the polyolefin-polyalkylene oxide block copolymer is selected from polypropylene-polyethylene oxide block copolymers.

[0053] In other embodiments, the molar ratio of polyethylene oxide to polypropylene in the polypropylene-polyethylene oxide block copolymer is less than about 1:1. For example, in some embodiments, the molar ratio of polyethylene oxide to polypropylene ranges from about 0.6:1 to about 0.9:1.

[0054] Non-limiting examples of commercially available polypropylene-polyethylene oxide block copolymers include those available under the PELESTAT brand from Sanyo, such as the 300 grade. Other commercially available polypropylene-polyethylene oxide block copolymer grades may also be used.

[0055] Suitable crosslinked polyvinylpyrrolidone includes conventional commercially available crosslinked polyvinylpyrrolidone, which may also be referred to as crospovidone, crospovidonum, insoluble polyvinylpyrrolidone, and crosslinked PVP.

[0056] In some embodiments, the crosslinked polyvinylpyrrolidone is a powder having a particle size distribution in which at least 95% of the particles have a particle size less than 250 microns.

[0057] Non-limiting examples of commercially available crosslinked polyvinylpyrrolidone include those of the KOLLIDON brand from BASF, such as the CL grade, the CL-F grade, and the CL-SF grade. These different grades of KOLLIDON differ from each other at least in their particle size distribution, bulk density, and swelling behavior. Other commercially available crosslinked polyvinylpyrrolidone grades may also be used.

[0058] Optional other additives

[0059] In some embodiments, the thermoplastic blend comprises one or more optional additives.

[0060] Suitable optional additives include conventional or commercially available plastic additives. A person skilled in the art of thermoplastic compounding can select suitable additives from available references without undue experimentation. Such references are, for example, E.W. Flick, Plastics Design Library's Plastic additive database (Plastics Additives Database) (Elsevier 2004).

[0061] The optional additives can be used in any amount sufficient to provide the desired processing or performance characteristics to the thermoplastic elastomer blend and / or the overmolded thermoplastic article. This amount should not result in waste of the additive or be detrimental to the processing or performance of the thermoplastic elastomer blend and / or the thermoplastic article.

[0062] Non-limiting examples of additives suitable for the present invention include one or more selected from the following: antimicrobial agents; antioxidants and stabilizers; colorants; contrast agents; and combinations thereof.

[0063] Range of components

[0064] Table 1 below shows the acceptable, desired, and preferred ranges of the components of various embodiments of the thermoplastic blend of the present invention, in weight percentages based on the total weight of the thermoplastic blend. Other possible ranges of components for certain embodiments of the disclosed invention are described elsewhere herein.

[0065] The thermoplastic blends of the disclosed invention can comprise these components, consist essentially of these components, or consist of these components. Any value between the range endpoints is also considered an endpoint of a range, such that all possible combinations are considered to be within the possible ranges shown in Table 1 as embodiments of the blends used in the disclosed invention. Unless expressly stated otherwise herein, any disclosed numerical value means that exact disclosed value and "about" that disclosed value, such that any possibility within the possibilities of Table 1 is considered as some embodiments of the blends used in the disclosed invention.

[0066]

[0067]

[0068] The weight percentage ranges determined in Table 1 reflect "fully compounded" thermoplastic compounds; that is, no dilution with additional thermoplastic polymer resin is required. Nevertheless, using the expected dilution or "let-down ratio", the masterbatch or concentrated form of the present invention that can be used to prepare a thermoplastic compound can be calculated, and the thermoplastic compound contains components within the weight percentage ranges determined in Table 1. Thus, thermoplastic articles can be formed by a fully compounded method or a masterbatch / dilution (let-down) method.

[0069] Processing

[0070] Once suitable components are selected, the preparation of the thermoplastic compounds of the present invention is not complicated. The compounding can be carried out in a batch or continuous operation mode.

[0071] Mixing carried out in a continuous process is usually carried out in an extruder, the temperature of which is raised to a level sufficient to melt the polymer matrix, and all additives are added at the feed throat or through a downstream injection or side feeder. The extruder speed range can be from about 200 to about 700 revolutions per minute (rpm), for example from about 300 to about 600 rpm. Usually, the output of the extruder is granulated for later processing.

[0072] Generally, once the thermoplastic compounds of the present invention are provided, the subsequent preparation of the thermoplastic articles of the present invention is not complicated. For example, the thermoplastic articles of the present invention can be prepared by extrusion, injection molding, blow molding, rotational molding, thermoforming, calendering, etc.

[0073] Processing techniques are described in available references, such as Dominick V. Rosato et al., Plastics Design Handbook (Springer 2013).

[0074] Method for manufacturing a thermoplastic article

[0075] Some aspects of the present invention relate to methods for preparing lubricated thermoplastic articles.

[0076] According to the present invention, the method comprises the steps of: (a) providing a composition comprising a thermoplastic elastomer and a water-insoluble hydrophilic polymer; (b) melt mixing the composition to provide a thermoplastic elastomer compound; and (c) forming the thermoplastic elastomer compound to provide an article for the intended use without a subsequent step of applying a lubrication enhancer to the article prior to the intended use.

[0077] In some embodiments, the forming step comprises extruding the thermoplastic elastomer compound.

[0078] In some embodiments, the intended uses include: inserting a lubricated thermoplastic article into the human body.

[0079] Utility of the present invention

[0080] It has been found that by adding certain water-insoluble hydrophilic polymers disclosed herein to thermoplastic elastomers (such as thermoplastic polyurethanes and polyether block amides) to provide a thermoplastic blend, the lubricity of the thermoplastic article formed from the thermoplastic blend can be improved, while avoiding a significant reduction in mechanical properties (such as elongation at break and tensile strength) compared to a thermoplastic article formed from a pure thermoplastic elastomer and subjected to the same heat treatment history.

[0081] Accordingly, the thermoplastic blends of the disclosed invention can be used in any thermoplastic article where enhanced lubricity is desired. The thermoplastic blends of the disclosed invention are particularly suitable for preparing thermoplastic articles for biomedical applications, including but not limited to: catheters, tubes, connectors, valves, trocars, etc.

[0082] Examples

[0083] Non-limiting examples of thermoplastic blends of various embodiments of the disclosed invention are provided.

[0084] Table 2 below shows the sources of the components of the thermoplastic blends of the examples.

[0085]

[0086] Table 3 below shows the formulations and certain properties of Examples 1 to 4.

[0087]

[0088] Table 4 below shows the formulations and certain properties of Examples 5 to 7.

[0089]

[0090] Table 5 below shows the formulations and certain properties of Examples 8 to 10.

[0091]

[0092] Without undue experimentation, one of ordinary skill in the art can use the specification, including the examples, to make and use the various aspects of the disclosed invention.

[0093] Unless otherwise indicated, all documents referred to in the embodiments of the present invention are incorporated herein by reference in their entirety. The citation of any document does not constitute an admission that it is prior art relative to the disclosed invention.

[0094] While the specific embodiments of the disclosed invention have been described and illustrated, it will be apparent to those skilled in the art that various other modifications may be made without departing from the spirit and scope of the invention. The appended claims are intended to cover all such modifications within the scope of the disclosed invention.

Claims

1. A lubricated thermoplastic article formed from a thermoplastic blend, the thermoplastic blend comprising: (a) a thermoplastic elastomer selected from thermoplastic polyurethanes, polyether block amides, and combinations thereof; and (b) 5 wt% to 20 wt% of a water-insoluble crosslinked polyvinylpyrrolidone, based on the weight of the blend; wherein, the article is a medical device; wherein the crosslinked polyvinylpyrrolidone is a powder having a particle size distribution, wherein at least 95% of the particles have a particle size less than 250 microns.

2. The article according to claim 1, wherein, the relative dynamic COF of the article is less than 0.

9.

3. The article according to claim 2, wherein, the article has at least one of the following properties: a relative tensile strength greater than 0.8 and a relative elongation at break greater than 0.

8.

4. The article according to any one of claims 1 to 3, wherein, the relative dynamic COF of the article is less than 0.6, and the article has at least one of the following properties: a relative tensile strength greater than 1 and a relative elongation at break greater than 1.

5. The article according to any one of claims 1 to 3, wherein, the relative dynamic COF (wet) of the article is less than 0.5, and the article has the following two properties: a relative tensile strength greater than 1 and a relative elongation at break greater than 1.

6. The article according to any one of claims 1 to 3, wherein, the thermoplastic blend further comprises one or more additives selected from the group consisting of: antimicrobial agents; antioxidants and stabilizers; colorants; contrast agents; and combinations thereof.

7. The article according to any one of claims 1 to 3, wherein, the article is a catheter.

8. A method for manufacturing an article according to any one of claims 1 to 7 for an intended use, the method comprising the steps of: (a) providing a composition comprising a thermoplastic elastomer and a water-insoluble hydrophilic polymer; (b) melt-mixing the composition to provide a thermoplastic elastomer blend; and (c) forming the thermoplastic elastomer blend to provide an article for the intended use without a subsequent step of applying a lubrication enhancer to the article prior to the intended use.

9. The method according to claim 8, wherein, the forming step comprises: extruding the thermoplastic elastomer blend.

10. The method according to claim 8 or 9, wherein, the intended use includes: inserting the article into the human body.

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