Thermoplastic polyurethane composition

Abstract

The present invention relates to a thermoplastic polyurethane (TPU) composition having adequate biostability and excellent environmental stress cracking resistance. The TPU composition comprises the reaction product of: a) a polyisocyanate comprising at least 50 wt% of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms, based on the total weight of the polyisocyanate component; b) a polyol comprising at least a hydroxyl-terminated poly(butadiene); and c) a chain extender comprising at least one diol chain extender; wherein the thermoplastic polyurethane composition has 22 wt% to 65 wt% hard segments, based on the total weight of the composition. The TPU composition is suitable for use in the manufacture of medical devices.

Description

Technical Field

[0001] This invention relates to thermoplastic polyurethane (TPU) compositions exhibiting excellent biostability and excellent resistance to environmental stress cracking. This combination of properties makes the TPU compositions described herein a useful material for medical applications. Background Technology

[0002] Thermoplastic polyurethane (TPU) is a widely used polymer material in the manufacture of medical devices. The physical properties of polyurethane can typically be tuned for various applications by selecting the type and amount of starting materials (e.g., polyols, isocyanates, and chain extenders) used in the composition to obtain polymers with properties particularly suitable for in vivo applications. Chemical, physical, and thermomechanical properties depend on the specific function, the type of tissue, cells, or fluid that will contact the medical device, and the acceptable or desired manufacturing process. Common considerations when selecting polymers for medical devices are based on parameters such as polymer stiffness, flexibility, chemical stabilizers (especially hydrolytic stability), polymer toxicity, and the degree of interaction between the polymer and tissue or blood. Specifically, biostability is crucial for implant applications.

[0003] For example, WO2016054320A1 discloses TPU compositions with non-softening and wet flexibility suitable for medical devices. However, their use in long-term implants may be compromised due to their sensitivity to oxidative attack and / or biostability.

[0004] One limitation of TPUs is that they can undergo many changes when exposed to chemical environments. Environmental stress cracking (ESC) can occur when polymers are under tensile stress in the presence of reactive chemical agents. The potential for ESC is a critical concern in medical devices. In medical applications, chemicals such as isopropanol can induce cracks in the material (microcracks bridged by polymer-precipitated fibers) and severely compromise its mechanical integrity. Cracking and embrittlement are hallmarks of inherent weaknesses in materials that can lead to unpredictable material failure. Furthermore, alcohols are common solvents used in the manufacturing and assembly of medical devices, as well as common cleaning agents in hospital environments.

[0005] Therefore, TPU is still needed, in addition to the other physical properties required for their use in medical devices, as well as appropriate biostability and the desired resistance to environmental stress cracking.

[0006] This invention addresses some or all of the requirements identified above, and solves some or all of the problems identified above. Summary of the Invention

[0007] The disclosed technology provides thermoplastic polyurethane (TPU) compositions with excellent biocompatibility and excellent resistance to environmental stress cracking. The TPU compositions also exhibit improved processability and suitable mechanical properties.

[0008] This invention provides a thermoplastic polyurethane composition comprising reaction products of at least the following substances: a) a polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one of the general formulas HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The thermoplastic polyurethane composition contains 22% to 65% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c). Specifically, the amount of hard segments can be 25% to 65% by weight, or 30% to 65% by weight. More specifically, the amount of hard segments can be 45% to 65% by weight. The present invention also relates to articles comprising the TPU compositions disclosed herein.

[0009] The present invention also provides a method for preparing the TPU composition disclosed herein, the method comprising the step of reacting the following substances: a) a polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The amount of hard segments in the composition is 22% to 65% by weight, based on the total weight of the composition. Specifically, the amount of hard segments can be 25% to 65% by weight, or 30% to 65% by weight. More specifically, the amount of hard segments can be 45% to 65% by weight. Detailed Implementation

[0010] The preferred features and implementation schemes will now be described in a non-restrictive manner.

[0011] Unless the context clearly indicates otherwise, the articles “one” and “a (kind)” are used in this text to refer to one (kind) or more (kinds) (i.e., at least one (kind)) the grammatical object of the article. For example, “a component” means one or more components.

[0012] Unless explicitly stated in the examples or otherwise, all numerical quantities of material amounts, reaction conditions, molecular weights, carbon number, etc., specified in this specification should be understood as being modified by the word “about.” As used herein, the term “about,” for example when referring to measurable values ​​(such as the amount or weight of a particular component or temperature), means a variation of ±20%, ±10%, ±5%, ±1%, ±0.5%, or specifically ±0.1% of the specified amount. Unless otherwise specified, all numerical quantities of material amounts or ratios specified in this specification are based on weight.

[0013] As used herein, the terms “comprising” or “including” (which are inclusive or open-ended and do not exclude additional unlisted elements or method steps) are intended to cover, in alternative embodiments, the phrases “consistently made of” and “composed of”, wherein “consistently made of” excludes any unspecified elements or steps and “consistently made of” allows the inclusion of additional unlisted elements or steps that do not materially affect the nature or essential and novel features of the composition or method under consideration.

[0014] The disclosed technology provides a thermoplastic polyurethane composition comprising reaction products of at least the following substances: a) a polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 22% to 65% by weight of hard segments based on the total weight of the composition, wherein the content of hard segments is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0015] Polyisocyanate components

[0016] The TPU compositions described herein are prepared using the following substances: (a) a polyisocyanate component comprising at least 50% by weight (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component.

[0017] Suitable aliphatic diisocyanates include linear and branched isocyanates, as well as alicyclic diisocyanates (i.e., cyclic aliphatic diisocyanates).

[0018] Specifically, the aliphatic diisocyanate (i) may be selected from: 1,4-diisocyanobutane (BDI), 1,5-diisocyanopentane (PDI), hexamethylene diisocyanate (HDI), 1,8-diisocyanooctane, 1,5-diisocyano-2-methylpentane, 1,5-diisocyano-2,2-dimethylpentane, 1,3-diisocyanocyclohexane, 1,4-diisocyanocyclohexane, 1,3-diisocyano-2-methylcyclohexane, 1,3-diisocyano-4-methylcyclohexane, 1,3-bis(isocyanomethyl)cyclohexane (HXDI), 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI), and mixtures thereof.

[0019] Aliphatic diisocyanates (i) can be linear aliphatic diisocyanates, more specifically hexamethylene diisocyanate (HDI).

[0020] The aliphatic diisocyanate (i) can be a cyclic aliphatic diisocyanate, specifically 1,3-bis(isocyanomethyl)cyclohexane (HXDI) or 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI). More specifically, the aliphatic diisocyanate (i) can be 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI).

[0021] Polyisocyanates (a) also include (ii) cyclic aliphatic isocyanates that are different from aliphatic diisocyanates (a)(i).

[0022] Cyclic aliphatic isocyanates (a)(ii) may have 6 to 12 carbon atoms. Specifically, cyclic aliphatic isocyanate (a)(ii) is 4,4'-diisocyanodicyclohexylmethane (H12MDI).

[0023] In some implementations, the polyisocyanate component is substantially free of or even completely free of aromatic diisocyanates.

[0024] Specifically, based on the total weight of the polyisocyanate components, the concentration of aliphatic diisocyanate (a)(i) can be from 55% to 75% by weight, more specifically from 60% to 65% by weight.

[0025] In some embodiments, the polyisocyanate component (a) is essentially composed of, or even composed of, the following: (i) an aliphatic diisocyanate having 6 to 10 carbon atoms and (ii) a cyclic aliphatic diisocyanate different from the aliphatic diisocyanate (i).

[0026] The polyisocyanate component (a) may include hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate dicyclohexylmethane (H12MDI).

[0027] The polyisocyanate component (a) may contain 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI) and 4,4'-diisocyanodicyclohexylmethane (H12MDI).

[0028] In some embodiments, the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic isocyanate (a)(ii) is from 1:1 to 3:1. Specifically, the weight ratio can be from 1:1 to 2:1, more specifically from 1:1 to 1.5:1, and even more specifically from 1.2:1 to 1.5:1.

[0029] polyol components

[0030] The TPU compositions described herein are prepared using the following substances: (b) a polyol component comprising at least hydroxyl-terminated poly(butadiene) (HTPB).

[0031] The term "hydroxyl-terminated poly(butadiene)" (HTPB) refers to a linear polybutadiene polymer with primary hydroxyl terminal groups.

[0032] Hydroxyl-terminated poly(butadiene) can be hydroxyl-terminated hydrogenated polybutadiene.

[0033] Specifically, the hydroxyl-terminated hydrogenated polybutadiene can be a compound selected from formula (I): (I)

[0034] Where X is an integer from 10 to 20, Y is an integer from 1 to 10, and Z is an integer from 10 to 60.

[0035] The hydroxyl-terminated hydrogenated polybutadiene can be a compound of formula (I), where Z is an integer from 20 to 40.

[0036] The hydroxyl-terminated hydrogenated polybutadiene can be a compound of formula (I), wherein X is an integer from 10 to 15, Y can be from 5 to 10, and Z can be from 35 to 45. Specifically, X is 13, Y is 7, and Z is 40. A suitable non-limiting example that can be used in the context of this invention is produced by Cray Valley under the trade name Krasol. ® HLBH-P2000 is a commercially available hydrogenated hydroxyl-terminated polyol.

[0037] The hydroxyl-terminated hydrogenated poly(butadiene) can be a compound of formula (I), wherein X is 15 to 20, Y is 1 to 5, and Z is 15 to 25. Specifically, X can be 17, Y can be 3, and Z can be 20. A suitable non-limiting example that can be used in the context of this invention is Nisso, a product of Nippon Soda Co., LTD, marketed under the trade name Nisso. ™ GI-1000 is a commercially available polybutadiene with hydroxyl-terminated ends.

[0038] In some embodiments, the polyol component may also include other optional polyols. Suitable polyols that can be used in combination with the hydroxyl-terminated poly(butadiene) polyols described above may include polyether polyols, polycarbonate polyols, polysiloxane polyols, polyester polyols (including polycaprolactone polyester polyols), polyamide oligomers, or any combination thereof.

[0039] In other embodiments, the polyol component used to prepare the TPU composition of the present invention does not contain one or more of these additional polyols, and in some embodiments, the polyol component is substantially composed of the aforementioned hydroxyl-terminated poly(butadiene) polyols. In one specific embodiment, the polyol component is composed of hydroxyl-terminated poly(butadiene), more specifically of hydroxyl-terminated hydrogenated polybutadiene.

[0040] Suitable polyether polyols may also be referred to as hydroxyl-terminated polyether intermediates and include polyether polyols derived from diols or polyols having a total of 2 to 15 carbon atoms. In some embodiments, the diol or diol reacts with an ether comprising an alkylene oxide (typically ethylene oxide or propylene oxide or mixtures thereof) having 2 to 6 carbon atoms. For example, hydroxyl-functionalized polyethers can be prepared by first reacting propylene glycol with propylene oxide, followed by reacting it with ethylene oxide. The primary hydroxyl groups produced by ethylene oxide are more reactive than secondary hydroxyl groups and are therefore preferred. Useful commercial polyether polyols include: poly(ethylene glycol) (PEG) comprising ethylene oxide reacted with ethylene glycol, poly(propylene glycol) comprising propylene oxide reacted with propylene glycol, and poly(tetramethylene glycol) (PTMEG) comprising water reacted with tetrahydrofuran. In some embodiments, the polyether intermediate comprises PTMEG or PEG or combinations thereof. Suitable polyether polyols also include polyamide adducts of epoxides, and may include, for example, ethylenediamine adducts comprising the product of the reaction of ethylenediamine and propylene oxide, diethylenetriamine adducts comprising the product of the reaction of diethylenetriamine and propylene oxide, and similar polyamide-type polyether polyols. Coethers may also be used in the techniques described herein. Typical coethers include the product of the reaction of THF and ethylene oxide or THF and propylene oxide. These can be Poly-THF. ® - B (a block copolymer) and poly-THF® - R (a random copolymer) was purchased from BASF. Various polyether intermediates typically have a number-average molecular weight (Mn) determined by measuring the terminal functional groups, with an average molecular weight greater than about 700, or even 700, 1,000, 1,500, or even 2,000, up to 10,000, 5,000, 3,000, 2,500, 2,000, or even 1,000. In some embodiments, the polyether intermediate comprises a blend of two or more polyethers with different molecular weights, such as a blend of PTMO with 2,000 Mn and PTMO with 1,000 Mn.

[0041] Suitable polycarbonates may also be referred to as hydroxyl-terminated polycarbonates and include those prepared by reacting a diol with a carbonate. U.S. Patent No. 4,131,731 is incorporated herein by reference for its disclosure of hydroxyl-terminated polycarbonates and preparations thereof. These polycarbonates are linear and have terminal hydroxyl groups that are substantially free of other terminal groups. The basic reactants are a diol and a carbonate. Suitable diols are selected from alicyclic and aliphatic diols containing 4 to 40, and / or even 4 to 12 carbon atoms, and polyoxyalkylene diols containing 2 to 20 alkoxy groups per molecule and 2 to 4 carbon atoms per alkoxy group. Suitable diols include aliphatic diols containing 4 to 12 carbon atoms, such as 1,4-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,6-2,2,4-trimethylhexanediol, 1,10-decanediol, hydrogenated dilinyldiol, and hydrogenated dioleyldiol; and alicyclic diols, such as 1,3-cyclohexanediol, 1,4-dihydroxymethylcyclohexane, 1,4-cyclohexanediol, 1,3-dihydroxymethylcyclohexane, 1,4-methylene-2-hydroxy-5-hydroxymethylcyclohexane, and polyalkylene glycols. The diol used in the reaction can be a single diol or a mixture of diols, depending on the desired properties in the finished product. Hydroxyl-terminated polycarbonate intermediates are generally those known in the art and in the literature. Suitable carbonates are selected from hydrocarbon carbonates consisting of 5 to 7-membered rings. Suitable carbonates used herein include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, 1,2-propylene carbonate, 1,2-buten carbonate, 2,3-buten carbonate, 1,2-ethylene carbonate, 1,3-penten carbonate, 1,4-penten carbonate, 2,3-penten carbonate, and 2,4-penten carbonate. Additionally, dialkyl carbonates, alicyclic carbonates, and diaryl carbonates are suitable herein. Dialkyl carbonates may contain 2 to 5 carbon atoms in each alkyl group, and specific examples are diethyl carbonate and dipropyl carbonate. Alicyclic carbonates, especially dialicyclic carbonates, may contain 4 to 7 carbon atoms in each ring structure, and may have 1 or 2 such structures. When one group is alicyclic, the other group may be alkyl or aryl. Conversely, if one group is aryl, the other may be alkyl or alicyclic. Suitable examples of diaryl carbonates are diphenyl carbonate, dimethyl carbonate, and dinaphthalene carbonate, which may contain 6 to 20 carbon atoms in each aryl group.

[0042] Suitable polysiloxane polyols include polysiloxanes terminated with α-ω-hydroxyl, amine, carboxylic acid, thiol, or epoxy groups. Examples include poly(dimethylsiloxane) terminated with hydroxyl, amine, carboxylic acid, mercapto, or epoxy groups. In some embodiments, the polysiloxane polyol is a hydroxyl-terminated polysiloxane. In some embodiments, the polysiloxane polyol has a number average molecular weight in the range of 300 to 5,000 or 400 to 3,000.

[0043] Polysiloxane polyols can be obtained through a dehydrogenation reaction between polysiloxane hydrides and aliphatic polyols or polyoxyalkylene alcohols to introduce hydroxyl groups onto the polysiloxane backbone. Suitable examples include α,ω-hydroxypropyl-terminated poly(dimethylsiloxane) and α,ω-aminopropyl-terminated poly(dimethylsiloxane), both of which are commercially available. Further examples include copolymers of poly(dimethylsiloxane) materials with poly(epoxyalkane).

[0044] Suitable polyester polyols may also be referred to as hydroxyl-terminated polyester intermediates and may include linear polyesters having a number-average molecular weight (Mn) of about 500 to about 10,000, about 700 to about 5,000, or about 700 to about 4,000, and typically have an acid value typically less than 1.3 or less than 0.5. Molecular weight is determined by measuring the terminal functional groups and is related to the number-average molecular weight. Polyester intermediates may be generated by: (1) esterification of one or more diols with one or more dicarboxylic acids or anhydrides, or (2) transesterification, i.e., the reaction of one or more diols with a dicarboxylic acid ester. To obtain a linear chain with predominantly terminal hydroxyl groups, a molar ratio of diol to acid exceeding one mole is generally preferred. The desired polyester dicarboxylic acid may be aliphatic, alicyclic, aromatic, or a combination thereof. Suitable dicarboxylic acids, which can be used alone or in mixtures, typically have a total of 4 to 15 carbon atoms and include: succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and their analogues. Anhydrides of the above-mentioned dicarboxylic acids, such as phthalic anhydride, tetrahydrophthalic anhydride, etc., may also be used. Adipic acid is generally the preferred acid. The diol that forms the desired polyester intermediate can be aliphatic, aromatic, or a combination thereof, including any diol described above in the chain extender section, and has a total of 2 to 20 or 2 to 12 carbon atoms. Suitable examples include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanediol, decamethylethylene glycol, dodecamethylethylene glycol, and mixtures thereof.

[0045] Suitable polyester polyols may include polyester diols derived from their own lactone monomers. Polycaprolactone polyester polyols are end-capped with primary hydroxyl groups. Suitable polycaprolactone polyester polyols may be made from ε-caprolactone and a bifunctional initiator (such as diethylene glycol, 1,4-butanediol, or any of the other diols and / or glycols listed herein). In some embodiments, the polycaprolactone polyester polyol is a linear polyester diol derived from its own lactone monomer.

[0046] Useful examples include CAPA ™ 2202A, a linear polyester diol with a number-average molecular weight (Mn) of 2,000, and CAPA ™ 2302A is a 3,000 Mn linear polyester diol, both of which are commercially available from Ingeviity Corporation. These materials can also be described as polymers of 2-oxetane heptanone and 1,4-butanediol.

[0047] Polycaprolactone polyester polyols can be made from 2-oxetaneheptanone and a diol, wherein the diol can be 1,4-butanediol, diethylene glycol, monoethylene glycol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, or any combination thereof. In some embodiments, the diol used to prepare the polycaprolactone polyester polyol is linear. Polycaprolactone polyester polyols can be made from 1,4-butanediol. In some embodiments, the polycaprolactone polyester polyol has a number average molecular weight of 500 to 10,000, or 500 to 5,000, or 1,000, or even 2,000 to 4,000, or even 3,000.

[0048] Suitable polyester polyols may include polyamide oligomers. The term "polyamide oligomer" refers to an oligomer having two or more amide bonds, or sometimes the amount of amide bonds will be specified. A subset of polyamide oligomers is telechelic polyamide. Telechelic polyamide is a polyamide oligomer having two functional groups of a single chemical type in a high percentage or a specific percentage, such as two terminal amine groups (meaning primary amine, secondary amine, or mixture), two terminal carboxyl groups, two terminal hydroxyl groups (again meaning primary hydroxyl groups, secondary hydroxyl groups, or mixture), or two terminal isocyanate groups (meaning aliphatic, aromatic, or mixture).

[0049] Specifically, the polyol component may have an average molecular weight of 1,000 to 3,000, preferably 1,000 to 2,000.

[0050] Chain extender components

[0051] The TPU compositions described herein are prepared using the following substances: (c) a chain extender component comprising at least one general formula HO-(CH2). xA diol chain extender with -OH groups, wherein x is an integer from 2 to 6 or even from 4 to 6. In other embodiments, x is 4.

[0052] Suitable examples include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol (BDO), 1,6-hexanediol (HDO), 1,3-butanediol, 1,5-pentanediol, and mixtures thereof.

[0053] In some implementations, the chain extender includes BDO, HDO, or a combination thereof.

[0054] In some implementations, the chain extender includes BDO.

[0055] In some implementations, the chain extender is essentially composed of BDO or even consists of BDO.

[0056] In some embodiments, the chain extender component may also include one or more additional chain extenders. These additional chain extenders are not excessively limited and may include diols (in addition to those mentioned above), diamines, and combinations thereof.

[0057] Polyurethane composition

[0058] The TPU compositions of the present invention can be prepared by conventional methods in the art for synthesizing polyurethane elastomers, such as, but not limited to, batch or one-step techniques. In the batch process, the components, namely diisocyanate, polyol, and chain extender, along with catalyst and any other additives (if desired), are introduced into a container, mixed, dispensed into a tray, and cured. The cured TPU can then be granulated and pelletized. The one-step process is carried out in an extruder (e.g., a single-screw or twin-screw extruder), in which the forming components are introduced into the extruder individually or as a mixture, and typically in one embodiment at a temperature of about 100°C to about 300°C, and in another embodiment at about 150°C to about 250°C, and even at a temperature of about 150°C to about 240°C.

[0059] One or more polymerization catalysts may be present during the polymerization reaction. Generally, any conventional catalyst can be used to react the diisocyanate with the polyol intermediate or chain extender. Examples of suitable catalysts for accelerating the reaction between the NCO group of the diisocyanate and the hydroxyl groups of the polyol and chain extender are conventional tertiary amines known in the art, such as triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo[2.2.2]octane, etc., and also specifically organometallic compounds, such as titanates, iron compounds such as iron acetylacetonate, tin compounds such as stannous diacetate, stannous dioctate, stannous dilaurate, or dialkyltin salts of aliphatic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, etc. The typical amount of catalyst used is 0.0001 parts by weight to 0.1 parts by weight per 100 parts by weight of the polyhydroxy compound (b).

[0060] TPU compositions can be prepared, for example, by a method comprising the following steps: (I) reacting the following components: a) the above-described polyisocyanate component; b) the above-described polyol component; and c) the above-described chain extender component.

[0061] The method may further include the following steps: (II) mixing the TPU composition of step (I) with one or more blend components, the blend components comprising one or more additional TPU materials and / or polymers, including any of the substances described above.

[0062] The method may further include the following steps: (II) mixing the TPU composition of step (I) with one or more additional additives selected from: pigments, ultraviolet stabilizers, ultraviolet absorbers, antioxidants, lubricants, heat stabilizers, hydrolysis stabilizers, crosslinking activators, flame retardants, layered silicates, fillers, colorants, reinforcing agents, adhesion modifiers, impact strength modifiers, and antimicrobial agents.

[0063] The method may further include the following steps: (II) mixing the TPU composition of step (I) with one or more blend components, the blend components comprising one or more additional TPU materials and / or polymers, including any of the substances mentioned above, and / or the following steps: (III) mixing the TPU composition of step (I) with one or more additional additives, the additional additives being selected from pigments, UV stabilizers, UV absorbers, antioxidants, lubricants, heat stabilizers, hydrolysis stabilizers, crosslinking activators, flame retardants, layered silicates, fillers, colorants, reinforcing agents, adhesion modifiers, impact strength modifiers, and antimicrobial agents.

[0064] In some embodiments, the TPU composition of the present invention may have a Shore A hardness of 60 to 100, or 75 to 100, or 80 to 100, or specifically 85 to 95, or more specifically 90 as measured by ASTM D2240.

[0065] In some embodiments, the TPU composition of the present invention may have a Shore D hardness of 50 to 70, specifically 55 to 65, more specifically 60 as measured by ASTM D2240.

[0066] The TPU compositions of the present invention have a hard segment content of 22% to 65% by weight based on the total weight of the composition. As used herein, the term "hard segment" refers to the combined weight of the polyisocyanate component and the chain extender component. The hard segment content of the TPU can be calculated by adding the weight percentage contents of the polyisocyanate and chain extender in the TPU and dividing the sum by the weight percentage contents of the chain extender, polyisocyanate, and polyol in the TPU.

[0067] Specifically, based on the total weight of the composition, the hard segment content can be from 25% to 65% by weight, or from 30% to 65% by weight.

[0068] More specifically, based on the total weight of the composition, the hard segment content can be 45% by weight or 65% by weight.

[0069] Specifically, the hard segment content can be from 45% to 50% by weight, which further improves the processability of TPU, i.e., the ability of TPU to be thermally processed into parts with acceptable properties, such as, but not limited to, the expected chemical, mechanical, and thermal properties of the polymer, and particularly the quality, optical properties, low defect rate, and desired texture of the final part. The remainder of the TPU is derived from the polyol component.

[0070] The molar ratio of the chain extender to the polyol in TPU is not limited, as long as the requirements for hardness and rapid shrinkage are met. In some embodiments, the molar ratio of the chain extender to the polyol (chain extender: polyol) is from 5.9:1 to 10:1, with a preferred range of 6.4:1 to 7.8:1.

[0071] Advantageously, the TPU compositions of the present invention exhibit excellent resistance to environmental stress cracking, specifically when exposed to chemical agents, and more specifically organic solvents such as isopropanol. Environmental stress cracking (ESC) can be determined by methods well known to those skilled in the art, such as ASTM D543-21. The working examples (Test Methods section) herein provide a detailed description of the determination of stress cracking.

[0072] In one embodiment, environmental stress cracking (ESC) is evaluated by bending an injection-molded bar in a fixture. Test specimens are prepared by injection molding a rectangular bar with dimensions of 12.5 cm × 1.3 cm × 0.032 cm (l × w × h). After processing, the specimens are conditioned at room temperature and 50% RH + / - 10% for at least two days. The specimen is mounted in a strain fixture and secured in place. Within the strain fixture, the specimen is bent on a curved surface with a radius of 0.724 cm. This radius and thickness of the specimen induce a high level of strain on the outer surface of the sample. The structure is then rubbed with a chemical reagent (isopropanol) onto the top of the specimen (the area with the greatest curvature). Cracks are identified by visual inspection.

[0073] Therefore, the technology described herein also provides a method for improving the environmental stress cracking resistance of TPU compositions, materials, and / or articles. This method involves preparing TPU materials by using the aforementioned polyisocyanate component, the aforementioned polyol component, and the aforementioned chain extender component in place of or in combination with the polyol and chain extender of the original TPU, thereby producing TPU compositions, materials, and / or articles with excellent environmental stress cracking resistance.

[0074] This article also includes a TPU composition wherein the hard segment content is 27% by weight and the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic diisocyanate (a)(ii) is 3:1.

[0075] This document also includes TPU compositions wherein the hard segment content is 30% by weight and the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic diisocyanate (a)(ii) is 1:1 to 3:1, specifically 1.5 to 3.1.

[0076] This article also includes a TPU composition wherein the hard segment content is 45% by weight and the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic diisocyanate (a)(ii) is 3:1.

[0077] This document also includes TPU compositions wherein the hard segment content is 50% to 60% by weight, and the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic isocyanate (a)(ii) is 1:1 to 2:1, preferably 1:1 to 1.5:1.

[0078] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate-dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is at least 50% by weight based on the total weight of the polyisocyanate components. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 45% to 65% by weight of hard segments based on the total weight of the composition, wherein the content of hard segments is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0079] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate-based dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is 50% by weight based on the total weight of the polyisocyanate components. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 60% to 65% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c). In this embodiment, the hydroxyl-terminated poly(butadiene) (HTPB) may specifically be a compound of formula (I), wherein X is 15 to 20, Y is 1 to 5, and Z is 15 to 25, preferably wherein X is 17, Y is 3, and Z is 20.

[0080] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate-dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is at least 50% by weight based on the total weight of the polyisocyanate components. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 45% to 55% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c). Specifically, the concentration of HDI can be more than 50% by weight, more specifically at least 60% by weight. In this embodiment, the hydroxyl-terminated poly(butadiene) (HTPB) can specifically be a compound of formula (I), wherein X is 10 to 15, Y is 5 to 10, and Z is 35 to 45, preferably wherein X is 13, Y is 7, and Z is 40.

[0081] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is from 75% to 100% by weight based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 45% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c). In this embodiment, the hydroxyl-terminated poly(butadiene) (HTPB) may specifically be a compound of formula (I), wherein X is 10 to 15, Y is 5 to 10, and Z is 35 to 45, preferably wherein X is 13, Y is 7, and Z is 40.

[0082] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate-dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is 60% by weight based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 50% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c). In this embodiment, the hydroxyl-terminated poly(butadiene) (HTPB) may specifically be a compound of formula (I), wherein X is 10 to 15, Y is 5 to 10, and Z is 35 to 45, preferably wherein X is 13, Y is 7, and Z is 40.

[0083] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate component comprising 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI) and 4,4'-diisocyanodicyclohexylmethane (H12MDI), wherein, based on the polyisocyanate component, 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI) is at least 60% by weight. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition has 60% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c). In this embodiment, the hydroxyl-terminated poly(butadiene) (HTPB) may specifically be a compound of formula (I), wherein X is 15 to 20, Y is 1 to 5, and Z is 15 to 25, preferably wherein X is 17, Y is 3, and Z is 20.

[0084] The TPU composition of the present invention may contain reaction products of at least the following substances: A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is at least 50% by weight or more than 50% by weight based on the total weight of the polyisocyanate components. Polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The thermoplastic polyurethane composition has 22% to 75% by weight of hard segments based on the total weight of the composition, wherein the content of hard segments is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0085] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is at least 50% by weight or more than 50% by weight based on the total weight of the polyisocyanate components. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The thermoplastic polyurethane composition has 27% to 75% by weight of hard segments based on the total weight of the composition, wherein the content of hard segments is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0086] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is at least 50% by weight or more than 50% by weight based on the total weight of the polyisocyanate components. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The thermoplastic polyurethane composition has 30% to 75% by weight of hard segments based on the total weight of the composition, wherein the content of hard segments is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0087] The TPU composition of the present invention may contain reaction products of at least the following substances: a) A polyisocyanate comprising hexamethylene diisocyanate (HDI) and 4,4'-diisocyanate dicyclohexylmethane (H12MDI), wherein the concentration of hexamethylene diisocyanate (HDI) is more than 50% by weight and at least 75% by weight, based on the total weight of the polyisocyanate components. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The thermoplastic polyurethane composition has 30% to 75% by weight of hard segments based on the total weight of the composition, wherein the content of hard segments is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0088] Other components or ingredients

[0089] The composition comprises the TPU component described above, and further comprises one or more additional components. These additional components include other polymeric materials that can be blended with the TPU described herein. These additional components also include one or more additives that can be added to the TPU or TPU-containing blends to affect the properties of the composition.

[0090] The TPU described herein can also be blended with one or more other polymers. There are no excessive limitations on the polymers that can be blended with the TPU described herein. In some embodiments, the composition includes two or more of the TPU materials. In some embodiments, the composition includes at least one of the TPU materials and at least one other polymer that is not one of the TPU materials. In some embodiments, the blend will have the same combination of the properties described above for the TPU composition. In other embodiments, the TPU composition will naturally have the described combination of properties; however, blends of the TPU composition with one or more of the other polymer materials described above may or may not have the described combination of properties.

[0091] Polymers that can be used in combination with the TPU materials described herein also include more conventional TPU materials, such as TPUs based on non-caprolactone polyesters, TPUs based on polyethers, or TPUs containing both non-caprolactone polyester and polyether groups. Other suitable materials that can be blended with the TPU materials described herein include polycarbonates, polyolefins, styrene polymers, acrylic polymers, polyoxymethylene polymers, polyamides, polyphenylene ethers, polyphenylene sulfides, polyvinyl chloride, chlorinated polyvinyl chloride, polylactic acid, or combinations thereof.

[0092] Polymers used in the blends described herein include homopolymers and copolymers. Suitable examples include: (i) polyolefins (PO), such as polyethylene (PE), polypropylene (PP), polybutene, ethylene propylene rubber (EPR), polyethylene oxide (POE), cyclic olefin copolymers (COC), or combinations thereof; (ii) styrene derivatives, such as polystyrene (PS), acrylonitrile butadiene styrene (ABS), styrene-acrylonitrile (SAN), styrene-butadiene rubber (SBR or HIPS), poly-α-methylstyrene, styrene-maleic anhydride (SMA), styrene-butadiene copolymers (SBC) (such as styrene-butadiene-styrene copolymers (SBS) and styrene-ethylene / butadiene-styrene copolymers (SEBS)), styrene-ethylene / propylene-styrene copolymers (SEPS), styrene-butadiene latex (SBL), SAN (EPDM) modified with ethylene propylene diene monomer, and / or acrylic elastomers (e.g., PS-SBR copolymers), or combinations thereof; (iii) thermoplastic polyurethanes (TPU) other than those listed above; and (iv) polyamides, such as Nylon. ™ The following include polyamides: (v) polyamides, such as polymethyl methacrylate, polymethyl methacrylate, methyl methacrylate-styrene (MS) copolymers, or combinations thereof; (vi) polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), or combinations thereof; (vii) polyoxymethylene, such as polyacetal; (viii) polyesters, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), copolyesters and / or polyester elastomers (COPE), including polyether-ester block copolymers, such as glycol-modified polyethylene terephthalate (PETG), polylactic acid (PLA), polyglycolic acid (PGA), copolymers of PLA and PGA, or combinations thereof; (ix) polycarbonate (PC), polyphenylene sulfide (PPS), polyphenylene ether (PPO), or combinations thereof; or combinations thereof.

[0093] In some embodiments, these blends include one or more additional polymeric materials selected from groups (i), (iii), (vii), (viii), or combinations thereof. In some embodiments, these blends include one or more additional polymeric materials selected from group (i). In some embodiments, these blends include one or more additional polymeric materials selected from group (iii). In some embodiments, these blends include one or more additional polymeric materials selected from group (vii). In some embodiments, these blends include one or more additional polymeric materials selected from group (viii).

[0094] Additional additives suitable for the TPU compositions described herein are not excessively limited. Suitable additives include pigments, UV stabilizers, UV absorbers, antioxidants, lubricants, heat stabilizers, hydrolysis stabilizers, crosslinking activators, flame retardants, layered silicates, radiation shielding agents (such as barium sulfate, tungsten metal, non-oxide bismuth salts), fillers, colorants, reinforcing agents, tack modifiers, impact strength modifiers, antimicrobial agents, and any combination thereof.

[0095] In some embodiments, the additional component is a flame retardant. Suitable flame retardants are not overly limited and may include boron phosphate flame retardants, magnesium oxide, dipentaerythritol, polytetrafluoroethylene (PTFE) polymers, or any combination thereof. In some embodiments, the flame retardant may include boron phosphate flame retardants, magnesium oxide, dipentaerythritol, or any combination thereof. A suitable example of a boron phosphate flame retardant is BUDIT. ® -326, which is commercially available from Budenheim USA, Inc. When present, the flame retardant component may be present in amounts from 0% to 10% by weight of the total TPU composition, or in other embodiments from 0.5% to 10% by weight of the total TPU composition, or from 1% to 10% by weight, or from 0.5% by weight, or from 1% to 5% by weight, or from 0.5% to 3% by weight, or even from 1% to 3% by weight.

[0096] The TPU compositions described herein may also contain additional additives, which may be referred to as stabilizers. Stabilizers may include antioxidants such as phenols, phosphites, thioesters, and amines; light stabilizers such as hindered amine light stabilizers and benzothiazole UV absorbers; and other process stabilizers; and combinations thereof. In one embodiment, a preferred stabilizer is Irganox from BASF. ® -1010 and Naugard from Chemtura ® -445. The amount of stabilizer is from about 0.1% to about 5% by weight of the TPU composition, in another embodiment from about 0.1% to about 3% by weight, and in another embodiment from about 0.5% to about 1.5% by weight.

[0097] In addition, various conventional inorganic flame retardant components can be used in TPU compositions. Suitable inorganic flame retardants include any of those known to those skilled in the art, such as metal oxides, metal oxide hydrates, metal carbonates, ammonium phosphate, ammonium polyphosphate, calcium carbonate, antimony oxide, clay, mineral clay (including talc), kaolin, wollastonite, nanoclay, montmorillonite clay commonly referred to as nanoclay, and mixtures thereof. In one embodiment, the flame retardant package includes talc. Talc in the flame retardant package promotes the high limiting oxygen index (LOI) property. The amount of inorganic flame retardant can be from 0% to about 30% by weight of the total weight of the TPU composition, from about 0.1% to about 20% by weight, or from about 0.5% to about 15% by weight in another embodiment.

[0098] Other optional additives may be used in the TPU compositions described herein. Additives include colorants, antioxidants (including phenols, phosphites, thioesters, and / or amines), anti-ozone agents, stabilizers, inert fillers, lubricants, inhibitors, hydrolytic stabilizers, light stabilizers, hindered amine light stabilizers, benzotriazole UV absorbers, heat stabilizers, anti-discoloration stabilizers, dyes, pigments, inorganic and organic fillers, reinforcing agents, and combinations thereof.

[0099] All of the above additives may be used in the commonly used effective amounts of these substances. The amount of non-flame retardant additives may be from about 0% to about 30% of the total weight of the TPU composition, from about 0.1% to about 25% of the total weight in one embodiment, and from about 0.1% to about 20% of the total weight in another embodiment.

[0100] These additional additives can be incorporated into the components used in the preparation of TPU resin or into the reaction mixture used in the preparation of TPU resin, or they can be incorporated after the preparation of TPU resin. In another method, all materials can be mixed with TPU resin and then melted, or they can be directly incorporated into the melt of TPU resin.

[0101] Products

[0102] The TPU compositions described herein can be used to prepare one or more articles. The specific types of articles that can be made from the TPU compositions described herein are not excessively limited.

[0103] Therefore, the present invention also provides an article made from the TPU composition described herein. Examples include, but are not limited to, medical applications, such as the TPU described herein being used in pacemaker heads; angiography, angioplasty, epidural catheters, thermodilution catheters, and urological catheters; catheter connectors; medical tubing; cartilage replacements, hair replacements, joint replacements, etc., as well as for personal care applications, pharmaceutical applications, healthcare product applications, or any other multiple applications. In some embodiments, these articles are prepared by extrusion, injection molding, or any combination thereof.

[0104] In some implementations, the article is a medical device or medical component. Specifically, the medical device or component is selected from cardiac pacemaker insulators, neural modulation lead insulators, heart valves, hydrocephalus shunts, gallbladder stents, balloon stents, and orthopedic articles.

[0105] The invention will be better understood by referring to the following embodiments, which are used to illustrate the invention but do not limit it.

[0106] Example

[0107] abbreviation

[0108] HS = Hard segment

[0109] HDI = Hexamethylene diisocyanate

[0110] H12MDI = 4,4'-diisocyanate dicyclohexylmethane.

[0111] 1,4-H6XDI = 1,4-bis(isocyanomethyl)cyclohexane

[0112] BDO = 1,4-Butanediol

[0113] PTEMG = Poly(tetramethylene ether) diol

[0114] HPBD = Hydroxyl-terminated poly(butadiene)

[0115] Test methods

[0116] a. Hardness

[0117] Hardness was determined using a hardness tester according to ASTM D2240.

[0118] b. Environmental stress cracking

[0119] Stress cracking resistance was determined by visually inspecting samples after exposure to isopropanol, as determined by ASTM D543-21. Test specimens were prepared using a rectangular bar with injection-molded dimensions of 12.5 cm × 1.3 cm × 0.032 cm (l × w × h). The specimens were equilibrated after treatment. The specimens were mounted in strain fixtures and secured in place. In the strain fixtures, the specimens were bent on a curved surface with a radius of 0.724 cm. This radius and thickness of the specimens resulted in a high level of strain on the outer surface of the specimens. Paper towels were then soaked in the chemical reagent (isopropanol) and rubbed onto the top of the specimens (the area with the greatest curvature). Cracking was usually instantaneous and visible to the naked eye. Repeated rubbing with saturated paper towels was performed multiple times. If cracking occurred, subsequent rubbing increased the depth and density of the cracks. Samples held in the strain position for several days after exposure showed no signs of the onset of cracking (initially no cracks) or showed deepened cracks (if cracking occurred initially).

[0120] Example 1

[0121] Test samples were prepared using a range of thermoplastic polymers containing H12MDI or HDI and H12MDI or HDI as diisocyanates. BDO was used as the chain extender. Detailed compositions are listed in Table 1. The stress cracking, hardness, and processability of the extruded films were determined.

[0122] Table 1

[0123] 1 Nisso ™ GI-1000 is a hydroxyl-terminated polybutadiene obtained from Nippon Soda Co.,LTD.

[0124] 2 Krasol ® HLBH-P2000 is a hydrogenated hydroxyl-terminated polyol derived from Cray Valley.

[0125] TPU compositions containing 45% to 65% by weight of hard segments and at least 50% by weight of HDI exhibit better tolerance to isopropanol.

[0126] Example 2

[0127] Test samples were prepared using a range of thermoplastic polymers containing either H12MDI or 1,4-H6XDI as diisocyanates. BDO was used as a chain extender. Detailed compositions are listed in Table 2. Stress cracking, hardness, and processability by injection molding were determined.

[0128] Table 2

[0129] 1 Nisso ™ GI-1000 is a hydroxyl-terminated polybutadiene obtained from Nippon Soda Co.,LTD.

[0130] Based on the total weight of the polyisocyanate component, TPU compositions containing 60% by weight of hard segments and 60% or 100% by weight of 1,4-H6XDI exhibit greater tolerance to cracking caused by isopropanol.

[0131] Example 3

[0132] Test samples were prepared using a range of thermoplastic polymers containing H12MDI or HDI and H12MDI or HDI as diisocyanates. BDO was used as the chain extender. Detailed compositions are listed in Table 3. The stress cracking, hardness, and processability of the extruded films were determined.

[0133] Table 3

[0134] 1 Krasol ® HLBH-P2000 and HLBH-P3000 are hydrogenated hydroxyl-terminated polyols derived from Cray Valley.

[0135] Example 4

[0136] The chemical resistance and biostability of different TPU samples after 24 hours of nitric acid exposure were determined. The composition of the TPU samples is summarized in Table 4.

[0137] Table 4

[0138] 1 Comparative example

[0139] 2 The representative TPU of WO2016054320A1.

[0140] Biostability was assessed by partially exposing a TPU film to 35% nitric acid for 24 hours, followed by polymer characterization. Nitric acid can be used as both a hydrolytic and oxidizing agent on the polymer. Resistance to hydrolysis and oxidative degradation is an important indicator of biostability. Chemical resistance was determined by the degree of chemical and physical changes in the polymer, through comparison of the material properties of TPU films unexposed to nitric acid and those immersed in room-temperature nitric acid for 24 hours. Test samples were prepared by extruding the film and cutting portions to the specimen dimensions defined in ASTM D1708. The samples were placed in 20 ml vials and immersed in 20 ml of 35% nitric acid for up to 24 hours. After this period, the TPU film samples were removed and thoroughly rinsed with deionized water to remove the acid. The samples were then dried under vacuum for at least 18 hours. The molecular weight change of the samples was then characterized by GPC, the tensile properties by ASTM D1708, and the visual and surface changes by light and scanning electron microscopy. The properties after nitric acid exposure were compared with those of the TPU film unexposed to nitric acid.

[0141] The changes in properties after 24 hours of nitric acid exposure are summarized in Table 5.

[0142] Table 5

[0143] 1 Tolerance after exposure to isopropanol

[0144] Various aspects and embodiments of the present invention are also defined by the following numbered clauses: 1. A thermoplastic polyurethane composition comprising a reaction product of the following substances: a) a polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The thermoplastic polyurethane composition has 45% to 65% by weight of hard segments based on the total weight of the composition, wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c).

[0145] 2. The thermoplastic polyurethane composition according to Clause 1, wherein the aliphatic diisocyanate (i) is a linear aliphatic diisocyanate.

[0146] 3. The thermoplastic polyurethane composition according to Clause 2, wherein the aliphatic diisocyanate (i) is hexamethylene diisocyanate (HDI).

[0147] 4. The thermoplastic polyurethane composition according to Clause 1, wherein the aliphatic diisocyanate (i) is a cyclic aliphatic diisocyanate.

[0148] 5. The thermoplastic polyurethane composition according to Clause 4, wherein the aliphatic diisocyanate (i) is 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI).

[0149] 6. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the concentration of the aliphatic isocyanate (i) is from 55% to 75% by weight based on the total weight of the polyisocyanate component.

[0150] 7. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the hard segment content is 45% to 60% by weight, preferably 45% to 50% by weight, based on the total weight of the composition.

[0151] 8. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the polyisocyanate (a) further comprises (ii) a cyclic aliphatic isocyanate different from the aliphatic diisocyanate (a)(i).

[0152] 9. The thermoplastic polyurethane composition according to Clause 8, wherein the cyclic aliphatic isocyanate (a) and (ii) is 4,4'-diisocyanate dicyclohexylmethane (H12MDI).

[0153] 10. The thermoplastic polyurethane composition according to clause 8 or 9, wherein the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic isocyanate (a)(ii) is from 1:1 to 3:1.

[0154] 11. The thermoplastic polyurethane composition according to Clause 10, wherein the hard segment content is 45% by weight, and the weight ratio of the aliphatic diisocyanate (a)(i) to the cyclic aliphatic diisocyanate (a)(ii) is 3:1.

[0155] 12. The thermoplastic polyurethane composition according to Clause 10, wherein the hard segment content is 50% to 60% by weight, and the weight ratio of the aliphatic diisocyanate (a)(i) to the cyclic aliphatic isocyanate (a)(ii) is 1:1 to 2:1, preferably 1:1 to 1.5:1.

[0156] 13. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the polyol component has an average molecular weight of 1,000 to 3,000, preferably 1,000 to 2,000.

[0157] 14. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the hydroxyl-terminated poly(butadiene) is hydroxyl-terminated hydrogenated polybutadiene.

[0158] 15. The thermoplastic polyurethane composition according to Clause 14, wherein the hydroxyl-terminated hydrogenated polybutadiene is a compound selected from formula (I): (I)

[0159] Where X is an integer from 10 to 20, Y is an integer from 1 to 10, and Z is an integer from 10 to 60.

[0160] 16. The thermoplastic polyurethane composition according to Clause 15, wherein Z is an integer from 20 to 40.

[0161] 17. The thermoplastic polyurethane composition according to clause 15 or 16, wherein X is 10 to 15, Y is 5 to 10, and Z is 35 to 45, preferably wherein X is 13, Y is 7, and Z is 40.

[0162] 18. The thermoplastic polyurethane composition according to clause 15 or 16, wherein X is 15 to 20, Y is 1 to 5, and Z is 15 to 25, preferably wherein X is 17, Y is 3, and Z is 20.

[0163] 19. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the chain extender (c) is BDO.

[0164] 20. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the thermoplastic polyurethane composition has a Shore A hardness of 60 to 100 or a Shore D hardness of 50 to 60 as measured by ASTM D2240.

[0165] 21. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the thermoplastic polyurethane composition has a Shore A hardness of 80 to 100, preferably 85 to 95, as measured by ASTM D2240.

[0166] 22. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the thermoplastic polyurethane composition has a Shore D hardness of 50 to 70, preferably 55 to 65, as measured by ASTM D2240.

[0167] 23. The thermoplastic polyurethane composition according to any one of the preceding clauses, wherein the thermoplastic polyurethane composition does not exhibit visible cracking upon exposure to isopropanol, as determined by ASTM D543-21.

[0168] 24. The thermoplastic polyurethane composition according to any one of the preceding clauses, further comprising one or more additional additives selected from: pigments, ultraviolet stabilizers, ultraviolet absorbers, antioxidants, lubricants, heat stabilizers, hydrolytic stabilizers, crosslinking activators, flame retardants, layered silicates, fillers, colorants, reinforcing agents, adhesion modifiers, impact strength modifiers, and antimicrobial agents.

[0169] 25. An article comprising a thermoplastic polyurethane composition according to any one of clauses 1 to 24.

[0170] 26. The article of manufacture as described in Clause 25, wherein the article of manufacture is a medical device or a component of a medical device.

[0171] 27. The article of manufacture according to Clause 26, wherein the medical device or component is selected from cardiac pacemaker insulators, neuromodulation lead insulators, heart valves, hydrocephalus shunts, gallbladder stents, balloon stents and orthopedic articles.

[0172] 28. A method for preparing a thermoplastic polyurethane composition according to any one of clauses 1 to 23, the method comprising the step of reacting the following substances: a) a polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component. b) A polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The amount of hard segments in the composition is 45% to 65% by weight, based on the total weight of the composition.

[0173] The invention has been explained with respect to its preferred embodiments; however, it should be understood that various modifications will become apparent to those skilled in the art upon reading this specification. Therefore, it should be understood that the invention disclosed herein is intended to cover these modifications that fall within the scope of the appended claims.

Claims

1. A thermoplastic polyurethane composition, said thermoplastic polyurethane composition comprising a reaction product of at least the following substances: a) a polyisocyanate, the polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component; b) a polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one of the general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to about 6; The thermoplastic polyurethane composition wherein the hard segment content is defined as the combined weight of the polyisocyanate component a) and the chain extender component c) based on the total weight of the composition.

2. The thermoplastic polyurethane composition according to claim 1, wherein the aliphatic diisocyanate (i) is a linear aliphatic diisocyanate.

3. The thermoplastic polyurethane composition according to claim 2, wherein the aliphatic diisocyanate (i) is hexamethylene diisocyanate (HDI).

4. The thermoplastic polyurethane composition according to claim 1, wherein the aliphatic diisocyanate (i) is a cyclic aliphatic diisocyanate.

5. The thermoplastic polyurethane composition according to claim 4, wherein the aliphatic diisocyanate (i) is 1,4-bis(isocyanomethyl)cyclohexane (1,4-H6XDI).

6. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the concentration of the aliphatic isocyanate (i) is from 55% to 75% by weight based on the total weight of the polyisocyanate component.

7. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the hard segment content is from 30% to 65% by weight.

8. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the hard segment content is from 45% to 65% by weight.

9. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the hard segment content is 45% to 60% by weight, preferably 45% to 50% by weight, based on the total weight of the composition.

10. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the polyisocyanate (a) further comprises (ii) a cyclic aliphatic isocyanate different from the aliphatic diisocyanate (a)(i).

11. The thermoplastic polyurethane composition according to claim 10, wherein the cyclic aliphatic isocyanate (a) and (ii) is 4,4'-diisocyanate dicyclohexylmethane (H12MDI).

12. The thermoplastic polyurethane composition according to claim 10 or 11, wherein the weight ratio of aliphatic diisocyanate (a)(i) to cyclic aliphatic isocyanate (a)(ii) is from 1:1 to 3:

1.

13. The thermoplastic polyurethane composition according to claim 12, wherein the hard segment content is 45% by weight, and the weight ratio of the aliphatic diisocyanate (a)(i) to the cyclic aliphatic diisocyanate (a)(ii) is 3:

1.

14. The thermoplastic polyurethane composition according to claim 12, wherein the hard segment content is 50% to 60% by weight, and the weight ratio of the aliphatic diisocyanate (a)(i) to the cyclic aliphatic isocyanate (a)(ii) is 1:1 to 2:1, preferably 1:1 to 1.5:

1.

15. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the polyol component has an average molecular weight of 1,000 to 3,000, preferably 1,000 to 2,000.

16. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the hydroxyl-terminated poly(butadiene) is hydroxyl-terminated hydrogenated polybutadiene.

17. The thermoplastic polyurethane composition according to claim 16, wherein the hydroxyl-terminated hydrogenated polybutadiene is a compound selected from formula (I): (I) Where X is an integer from 10 to 20, Y is an integer from 1 to 10, and Z is an integer from 10 to 60.

18. The thermoplastic polyurethane composition according to claim 17, wherein Z is an integer from 20 to 40.

19. The thermoplastic polyurethane composition according to claim 17 or 18, wherein X is 10 to 15, Y is 5 to 10, and Z is 35 to 45, preferably wherein X is 13, Y is 7, and Z is 40.

20. The thermoplastic polyurethane composition according to claim 17 or 18, wherein X is 15 to 20, Y is 1 to 5, and Z is 15 to 25, preferably wherein X is 17, Y is 3, and Z is 20.

21. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the chain extender (c) is BDO.

22. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the thermoplastic polyurethane composition has a Shore A hardness of 60 to 100 or a Shore D hardness of 50 to 60 as measured by ASTM D2240.

23. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the thermoplastic polyurethane composition has a Shore A hardness of 80 to 100, preferably 85 to 95, as measured by ASTM D2240.

24. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the thermoplastic polyurethane composition has a Shore D hardness of 50 to 70, preferably 55 to 65, as measured by ASTM D2240.

25. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the thermoplastic polyurethane composition does not exhibit visible cracking upon exposure to isopropanol, as determined by ASTM D543-21.

26. The thermoplastic polyurethane composition according to any one of the preceding claims, wherein the thermoplastic polyurethane composition further comprises one or more additional additives selected from: pigments, ultraviolet stabilizers, ultraviolet absorbers, antioxidants, lubricants, heat stabilizers, hydrolytic stabilizers, crosslinking activators, flame retardants, layered silicates, fillers, colorants, reinforcing agents, adhesion modifiers, impact strength modifiers, and antimicrobial agents.

27. An article comprising the thermoplastic polyurethane composition according to any one of claims 1 to 26.

28. The article of manufacture according to claim 27, wherein the article of manufacture is a medical device or a component of a medical device.

29. The article of claim 28, wherein the medical device or component is selected from cardiac pacing lead insulators, neural modulation lead insulators, heart valves, hydrocephalus shunts, gallbladder stents, balloon stents, and orthopedic products.

30. A method for preparing a thermoplastic polyurethane composition, the method comprising the step of reacting the following substances: a) a polyisocyanate, the polyisocyanate comprising at least 50% by weight of (i) an aliphatic diisocyanate having 6 to 10 carbon atoms based on the total weight of the polyisocyanate component; b) a polyol comprising at least hydroxyl-terminated poly(butadiene) (HTPB); and c) A chain extender comprising at least one of the general formula HO-(CH2). x -OH diol chain extenders, where x is an integer from 2 to 6; The amount of hard segments in the composition is from 22% to 65% by weight, based on the total weight of the composition.

31. The method for preparing a thermoplastic polyurethane composition according to claim 30, wherein the thermoplastic polyurethane composition is a composition as defined in any one of claims 1 to 26.

32. The method according to claim 30 or 31, wherein the amount of hard segments in the composition is from 30% to 65% by weight, based on the total weight of the composition.

33. The method according to any one of claims 30 to 32, wherein the amount of hard segments in the composition is 45% to 65% by weight based on the total weight of the composition.

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