Thermoplastic polyurethane composition

Abstract

The invention relates to a thermoplastic polyurethane material with a high modulus of elasticity, low density, and resistance to repeated cyclic deformation. The thermoplastic polyurethane composition is formed from the reaction product of a polyol component containing a polyether polyol such as poly(tetramethylene ether glycol) and a polyol component containing a blend of polybutadiene diol, a diisocyanate component, and a chain extender component.

Description

Background

[0001] The utility of thermoplastic polyurethane materials for a variety of applications is being appreciated in many new industries. However, it is often difficult to find a single thermoplastic polyurethane composition that has combinations of properties that are suited for certain applications. For example, many applications will require high modulus and hardness, but also the ability to withstand cyclic deformations and varying temperature ranges. Often polyamide-co-polyethers are used for these applications because they have high flex modulus, low density, and good low temperature fatigue resistance. However, thermoplastic polyurethane compositions that have high flex modulus lack low temperature cyclic fatigue behavior and are undesirably heavy. One reason for this is because in order to achieve the high flex modulus, the hard segment content of the thermoplastic polyurethane is increased, which also increases density and glass transition temperature. The higher density and glass transition temperatures result in less desirable performance when subject to cyclic deformations. Therefore, it is object of this invention to provide a thermoplastic polyurethane composition having the unexpected combination of properties including high modulus, low density, and the ability to sustain cyclic deformations. WO9856841 A1 discloses, according to its abstract, polyurethane elastomer systems for industrial and paper mill rolls and more particularly to polyurethane covered rolls made from a polyurethane composition of a polyurethane prepolymer cured with an aromatic diamine and a hydroxylterminated polybutadiene resin. WO2016098073 A1 discloses, according to its abstract, partially crosslinked polyurethane polymers comprising diisocyanates and aliphatic hydrocarbon soft segments with a short-chain diol chain extender and a multifunctional amine and / or alcohol crosslinker to provide a polyurethane polymer with useful properties for the production of medical implant devices such as heart valves. US2019055342 A1 discloses, according to its abstract, a thermoplastic polyurethane composition imparted with crosslinking sites, which comprise a thermoplastic polyurethane containing crosslinking sites incorporated into the molecule of a polyol and / or a chain extender. US2019256641 A1 discloses, according to its abstract, method of preparing a thermoplastic polyurethane includes reacting specific amounts of a hydrogenated polydiene diol, a poly(alkylene oxide) diol, a chain extender, and a diisocyanate in the presence of a solvent.Summary of the Invention

[0002] The present invention is a thermoplastic polyurethane composition comprising the reaction product of a polyol component and a diisocyanate component, wherein the polyol component comprises a mixture of a polyether polyol and polybutadiene polyol, as defined in the appended claims. Examples of polyether polyols include poly(tetramethylene ether glycol), polypropylene glycol, polyethylene glycol, and polyoxymethylene. The polybutadiene polyol may include unsaturated polybutadiene polyols or diols or polybutadiene diol. In one embodiment, the polyol component comprises or consists of a mixture of poly(tetramethylene ether glycol) and polybutadiene polyol. In another embodiment, the polyol component comprises or consists of a mixture of poly(tetramethylene ether glycol) and unsaturated polybutadiene polyol. In still another embodiment, the polyol component comprises a polyether component that is a blend of poly(tetramethylene ether glycol) and an ethylene oxide endcapped poly(propylene glycol) and polybutadiene polyol. The thermoplastic polyurethane composition includes a chain extender component, as defined in the appended claims. The invention also includes articles made from the thermoplastic polyurethane composition of the invention.Detailed Description

[0003] Thermoplastic polyurethane compositions are generally formed from the reaction product of a polyol component, a diisocyanate component, and optionally, a chain extender component. In the thermoplastic polyurethane composition of the present invention, the polyol component is a blend of polyols, wherein the blend includes a polyether polyol and a polybutadiene polyol.The Polyol Component

[0004] The polyol component used in the thermoplastic polyurethane composition of the present invention is a blend of polyols, wherein the blend contains a polyether polyol and a polybutadiene polyol.

[0005] Polyether polyols are typically derived from a diol or polyol having a total of from 2 to 15 carbon atoms, in some embodiments an alkyl diol or glycol which is reacted with an ether comprising an alkylene oxide having from 2 to 6 carbon atoms, typically ethylene oxide or propylene oxide or mixtures thereof. For example, hydroxyl functional polyether can be produced by first reacting propylene glycol with propylene oxide followed by subsequent reaction with ethylene oxide. Primary hydroxyl groups resulting from ethylene oxide are more reactive than secondary hydroxyl groups and thus are preferred. Useful commercial polyether polyols include poly(ethylene glycol) comprising ethylene oxide reacted with ethylene glycol, poly(propylene glycol) comprising propylene oxide reacted with propylene glycol, poly(tetramethylene ether glycol) comprising water reacted with tetrahydrofuran which can also be described as polymerized tetrahydrofuran, and which is commonly referred to as PTMEG. Suitable polyether polyols also include polyamide adducts of an alkylene oxide and can include, for example, ethylenediamine adduct comprising the reaction product of ethylenediamine and propylene oxide, diethylenetriamine adduct comprising the reaction product of diethylenetriamine with propylene oxide, and similar polyamide type polyether polyols. Copolyethers can also be utilized in the described compositions. Typical copolyethers include the reaction product of THF and ethylene oxide or THF and propylene oxide. These are available from BASF as PolyTHF ®< B, a block copolymer, and PolyTHF ®< R, a random copolymer.

[0006] In one embodiment, polyether polyols used in the present invention have a number average molecular weight (Mn) as determined by assay of the terminal functional groups of about 700 to about 10,000, for example, from about 1,000 to about 5,000, or even from about 1,000 to about 3,000, or even 1000 to about 2500, or even about 2000 to about 2500. In one embodiment, the number average molecular weight of the polyether polyol used in the present invention is less than 3000.

[0007] In one embodiment, the polyether polyol used in the polyol component of the present invention comprises or consists of poly(tetramethylene ether glycol). In another embodiment, the polyether polyol used in the polyol component is a blend of polyether polyols. For example, the blend of polyether polyols comprises or consists of poly(tetramethylene ether glycol) and ethylene oxide end capped poly(propylene glycol).

[0008] The polyol component of the present invention also includes a polybutadiene polyol. In one embodiment, the polybutadiene polyol is unsaturated. In one embodiment, the polybutadiene polyol comprises or consists of polybutadiene diol, which as used herein, also refers to hydroxyl terminated polybutadiene. The molecular weight of the polybutadiene polyol used to form the thermoplastic polyurethane of the present invention depends on the desired characteristics of article to be made. Polybutadiene polyols suitable for forming a thermoplastic polyurethane composition according to the present invention may have a molecular weight from about 100 to about 10,000, for example from about 300 to about 5,000, further for example from about 1,000 to about 3,000, for example, 2,000. In some embodiments, the polybutadiene polyol has an OH functionality of 2.0 to 3.0, for example, 2.0 to 2.6.

[0009] In one embodiment, the polybutadiene polyol is unsaturated, such that the polybutadiene polyol contains double bonds along the butadiene chain.

[0010] Commercially available polybutadiene polyols useful in the present invention include KRASOL ™< LBH P-2000, KRASOL ™< LBH 2000, and KRASOL ™< HLBH P-2000 available from Cray Valley, and NISSO ™< PB G 2000, NISSO ™< PB-G1400, NISSO ™< PB-GI1000, and NISSO PB-GI2000 available from Nippon Soda Co.Polyisocyanate Component

[0011] The thermoplastic polyurethane compositions described herein are made using a polyisocyanate component and this is a diisocyanate component. The polyisocyanate and / or polyisocyanate component may include one or more polyisocyanates. In some embodiments, the polyisocyanate component includes one or more diisocyanates.

[0012] Suitable polyisocyanates include aromatic diisocyanates, aliphatic diisocyanates, or combinations thereof. In some embodiments, the polyisocyanate component includes one or more aromatic diisocyanates. In some embodiments, the polyisocyanate component is essentially free of, or even completely free of, aliphatic diisocyanates. In other embodiments, the polyisocyanate component includes one or more aliphatic diisocyanates. In some embodiments, the polyisocyanate component is essentially free of, or even completely free of, aromatic diisocyanates.

[0013] Examples of useful polyisocyanates include aromatic diisocyanates such as 4,4'-methylenebis(phenyl isocyanate) (MDI), m-xylene diisocyanate (XDI), 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, phenylene-1,4-diisocyanate (PDI), phenylene-1,3-diisocyanate, naphthalene-1,5-diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), and toluene diisocyanate (TDI); as well as aliphatic diisocyanates such as isophorone diisocyanate (IPDI), 1,4-cyclohexyl diisocyanate (CHDI), decane-1,10-diisocyanate, lysine diisocyanate (LDI), 1,4-butane diisocyanate (BDI), isophorone diisocyanate (PDI), hexane diisocyanate (HDI), 1,4-Bis (isocyanatomethyl) cyclohexane (1,4-H6XDI), and dicyclohexylmethane-4,4'-diisocyanate (H12MDI). Mixtures of two or more polyisocyanates may be used. In one embodiment, the diisocyanate used in the present invention comprises or consists of MDI.Chain Extender Component

[0014] The thermoplastic polyurethane composition of the present invention is made using a chain extender component selected from 1,4-butanediol (BDO), neopentyl glycol, dipropylene glycol (DPG), 2-butyl-2-ethyl-1,3-propandiol (BEPD), and mixtures thereof.

[0015] In some embodiments, the chain extender includes BDO.

[0016] In one embodiment of the present invention, the chain extender comprises or consists of 1,4-butane diol. In another embodiment, the chain extender component comprises or consists of 2-butyl-2-ethyl-1,3-propane diol. In another embodiment, the chain extender component comprises or consists of dipropylene glycol. In still another embodiment, the chain extender comprises or consists of neopentylglycol. In another embodiment, the chain extender component comprises mixtures of chain extenders selected from 1,4-butane diol, 2-butyl-2-ethyl-1,3-propane diol, dipropylene glycol, and neopentylglycol.

[0017] The hard segment content of a thermoplastic polyurethane composition is defined as the combined weight percent of the diisocyanate component and the chain extender component. The thermoplastic polyurethanes of the present invention have a hard segment content of 54 % to 75% by weight.

[0018] The thermoplastic polyurethane of the present invention comprises the reaction product of a polyether polyol and polybutadiene polyol, a diisocanate component, and a chain extender component.

[0019] The polyol component comprises a mixture of a polyether polyol and polybutadiene polyol, wherein the polyether polyol is at least 50% by weight of the polyol component. In one such embodiment, the polyether polyol greater than 50% by weight of the polyol component. In another embodiment, polyol component comprises a mixture of polyether polyol and polybutadiene polyol in weight ratios from 90:10 or 80:20 to 60:40, even further for example, 70:30 to 60:40.

[0020] In another embodiment of the present invention, the thermoplastic polyurethane comprises the reaction product of a polyol component and a diisocyanate component, where the polyol component comprises or consists of a mixture of poly(tetramethylene ether glycol) and unsaturated polybutadiene diol and a diisocyanate component. In such an embodiment, the polyol component may comprise a mixture of poly(tetramethylene ether glycol) and polybutadiene diol in weight ratios from 90:10 or 80:20 to 60:40, even further for example, 70:30 to 60:40

[0021] Thermoplastic polyurethane compositions of the present invention may be made using any process now known or hereafter developed. For example, in one embodiment, the "one-shot" process may be used, where the reactants (polyol component, diisocyanate, and optionally, the chain extender component) are added to an extruder reactor and reacted. In another embodiment, the thermoplastic polyurethane may be prepared utilizing a pre-polymer process. In the pre-polymer process, the polyol intermediates are reacted with generally an equivalent excess of one or more diisocyanates to form a pre-polymer solution having free or unreacted diisocyanate therein. Subsequently, a chain extender, as noted above, is added in an equivalent amount generally equal to the isocyanate end groups as well as to any free or unreacted diisocyanate compounds. Typically, the pre-polymer route can be carried out in any conventional device including an extruder.

[0022] Optionally, it may be desirable to utilize catalysts such as stannous and other metal carboxylates as well as tertiary amines. Examples of suitable catalysts which in particular accelerate the reaction between the NCO groups of the diisocyanates and the hydroxy groups of the polyols and chain extenders are the conventional tertiary amines known from the prior art, e.g. triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo[2.2.2]octane and the like, and also in particular organometallic compounds, such as titanic esters, iron compounds, e.g. ferric acetylacetonate, tin compounds, e.g. stannous diacetate, stannous dioctoate, stannous dilaurate, or the dialkyltin salts of aliphatic carboxylic acids, e.g. dibutyltin diacetate, dibutyltin dilaurate, or the like, phenyl mercuric propionate, lead octoate, iron acetylacetonate, magnesium acetylacetonate, or bismuth compounds such as bismuth octoate, bismuth laurate, and the like.

[0023] Various types of optional components can be present during the polymerization reaction, and / or incorporated into the TPU elastomer described above. These include, but are not limited to, antioxidants, biocides, compatibilizers, electro-dissipative antistatic additives, fillers / reinforcing agents, flame and fire retardants, fungicides, impact modifiers, pigments, colorants, plasticizer, polymers, rheology modifiers, slip additives, and UV stabilizers. All of the additives described above may be used in an effective amount customary for these substances.

[0024] These additional additives can be incorporated into the components of, or into the reaction mixture for, the preparation of the TPU resin, or after making the TPU resin. In another process, all the materials can be mixed with the TPU resin and then melted or they can be incorporated directly into the melt of the TPU resin.

[0025] Thermoplastic polyurethane compositions of the present invention exhibit unexpected properties including a flex modulus measured according to ASTM D790 of at least 160MPa while exhibiting the ability to withstand at least 30,000 low temperature fatigue cycles measured according to ASTM D1052 at -10°C. In some embodiments, the thermoplastic polyurethane compositions according to the present invention have a flex modulus of at least 160 MPa or even 200 MPa and exhibit the ability to withstand at least 40,000 low temperature fatigue cycles. Another unexpected property associated with the inventive thermoplastic polyurethanes of the present invention is the transparency of such materials. In one embodiment, the materials showing the unexpected flex modulus and ability to withstand low temperature fatigue cycles additionally show transparency. In one embodiment, the thermoplastic polyurethane of the present invention exhibits a haze of 22% or less as measured according to ASTM D1003 on 75mil injection molded plaques. The present invention also includes an article made with a thermoplastic polyurethane exhibiting these unique and unexpected properties and a method for making such articles by known methods such as molding or extruding.

[0026] Thermoplastic polyurethane compositions of the present invention may be used in a variety of applications, including but not limited to industrial applications including hose and tubes and wire and cables such as high-pressure tubes, wire and cable coatings / insulation, footwear applications such as running shoes, cleated shoes, winter and summer sports equipment and applications such as snowboard, ski equipment, mountain climbing equipment, kayak and rafting equipment, golf equipment, golf balls, cycling equipment, personal protective equipment and applications such as shin guards, helmet and applications in personal electronic components.

[0027] A series of thermoplastic polyurethane sample compositions were formed by reacting the components noted in Table 1. The isocyanate component for all samples is MDI. Table 1 Polyol componentBlend ratioChain extenderHard segment (%) 1< Hardness (D) 2< Flex modulus (MPa) 3< Low temp Fatigue (# of cycles) 4< Haze (%) 75 mill thickness 5< * 1PTMEG: PBD60:40BDO8018522PTMEG: PBD60:40BDO7518053PTMEG: PBD60:40BDO6674114040K+4PTMEG: PBD60:40BDO6464100740K+ * 5PTMEG: PBD20:80BDO59144 * 6PTMEG: PBD40:60BDO595957PTMEG: PBD60:40BDO596669940K+8PTMEG: PBD70:30BDO596354340K+229PTMEG: PBD80:20BDO59587 * 10PTMEG: PBD90:10BDO5915311PTMEG: PBD60:40BDO545544440K+ * 12PTMEG: PBD60:40BDO499113PTMEG: PBD 6< 60:40BDO5938314PTMEG: PBD 7< 60:40BDO5937015PPG: PBD60:40BDO59350 * 16PTMEG: EO capped PPG: PBD35:15:50BDO6493817PTMEG: PBD60:40BDO:BEPD (30:70)545822840K+5.318PTMEG: PBD60:40BDO:DPG (20:80)545917240K+19PTMEG: PBD60:40DPG546016040K+20PTMEG: PBD60:40BEPD546228940K+21PTMEG: PBD60:40BDO:NPG: BEPD (30:20:50)5960522PTMEG: PBD60:40BDO:BEPD (30:70)596755340K+23PTMEG: PBD60:40BDO:DPG (20:80)596436240K+24PTMEG: PBD60:40NPG5971925PTMEG: PBD60:40BDO:NPG (10:90)59691 * C1PTMEG100BDO801951 * C2PTMEG100BDO751214 * C3PTMEG100BDO69759706K2.4 * C4PTMEG100BDO66484 * C5PTMEG100BDO:DPG (87:13)667042315K1.5 * C6PTMEG100BDO64345 * C7PTMEG100BDO62320 * C8PTMEG100BDO59120 * C9PTMEG100BDO586511640K+5.9 * C10PTMEG100BDO49Low 8< * C11PBD100BDO80792100 * C12PBD100BDO6471100 * C13PBD100BDO59Low 8< 100 * C14PBD100BEPD6471 * C15PBD100DPG64165 * C16Polycaprolactone diol100BDO-6530620K42.5 * C17Sebacis:BDO100BDO:DPG (93:7)-5511540K+11.2 1< Hard Segment is the total weight % of the polyisocyanate component and chain extender component. 2< Hardness is measured using a Durometer according to ASTM D2240. 3< Flex modulus was measured according to ASTM D790. 4< Low temp fatigue was measured according to ASTM D1052 at -10 °C. The flex angle was 60°and the frequency was 1.7Hz. The testing was discontinued after 40K cycles 5< Haze was measured according to ASTM D1003 on 75mil injection molded plaques 6< PBD 6< is polybutadiene polyol with average molar mass of 2900g / mol, OH functionality of 2.4 (approx.). The isomer ratio of 1,2-vinyl, 1,4-trans and 1,4-cis is approximately 22,58 and 20% respectively. The commercial name is Polyvest HT 7< PBD 7< is polybutadiene polyol with average molar mass of 2800g / mol, OH functionality of 2.4-2.6 (approx.). The ratio of 1,2-vinyl, 1,4-trans and 1,4-cis isomers is approximately 20,60 and 20% respectively. The commercial name is Poly bd R45LTO. 8< The samples were too soft (low flex modulus) for reliable flex modulus testing. * = not according to the present invention.

[0028] The results in Table 1 show that the combination of poly(tetramethylene ether glycol) and polybutadiene diol provide an unexpected and synergistic effect in terms of flexural modulus and ability to withstand cyclic deformations. It would generally be expected that the addition of polybutadiene diol to a thermoplastic polyurethane composition including a polyether polyol would lower the flex modulus, but as the data in Table 1 illustrates, the flex modulus of thermoplastic polyurethanes containing the combination is unexpectedly higher. In addition, the inventive examples are able to withstand a high number of cyclic deformations.

[0029] As used herein, the transitional term "comprising", which is synonymous with "including", "containing," or "characterized by", is inclusive or open-ended and does not exclude additional, un-recited elements or method steps. However, in each recitation of "comprising" herein, it is intended that the term also encompass, as alternative embodiments, the phrases "consisting essentially of" and "consisting of", where "consisting of" excludes any element or step not specified and "consisting essentially of" permits the inclusion of additional un-recited elements or steps that do not materially affect the basic and novel characteristics of the composition or method under consideration.

[0030] While the invention has been explained in relation to its preferred embodiments, it is to be understood that various modifications thereof falling within the scope of the appended claims will become apparent to those skilled in the art upon reading the specification.

Claims

1. A thermoplastic polyurethane comprising the reaction product of: (a) a polyol component comprising a mixture of a polyether polyol and polybutadiene polyol, wherein the polyol component comprises at least 50% by weight polyether polyol; and (b) a diisocyanate component; and (c) a chain extender component selected from 1,4-butanediol, 2-butyl-2-ethyl-1,3-propandiol, dipropylene glycol, neopentyl glycol, and mixtures thereof, wherein the thermoplastic polyurethane has a hard segment content of 54% to 75% by weight, wherein the hard segment content is defined as the combined weight of the diisocyanate component and the chain extender component.

2. The thermoplastic polyurethane of claim 1, wherein the polyether polyol comprises or consists of poly(tetramethylene ether glycol), polypropylene glycol, polyethylene glycol, polyoxymethylene, or mixtures thereof.

3. The thermoplastic polyurethane of claim 1 or 2, wherein the polybutadiene polyol comprises or consists of unsaturated polybutadiene polyol.

4. The thermoplastic polyurethane of claims 1 to 3, wherein the polyol component comprises greater than 50% by weight polyether polyol.

5. The thermoplastic polyurethane of any of claims 1 to 4, wherein the polyol component comprises a mixture of polyether polyol and unsaturated polybutadiene polyol in a weight ratio from 90:10 to 40:60.

6. The thermoplastic polyurethane of claim 5, wherein the polyol component comprises a mixture of polyether polyol and unsaturated polybutadiene polyol in a weight ratio from 80:20 to 60:

407. The thermoplastic polyurethane of any of claims 1 to 6, wherein the polyether polyol has a number average molecular weight of 500 to 3000 or 1000 to 2500, measured by assay of terminal functional groups.

8. The thermoplastic polyurethane of any of claims 1 to 7, wherein the diisocyanate component comprises or consists of an aromatic diisocyanate.

9. The thermoplastic polyurethane of any of claims 1 to 8, wherein the diisocyanate component comprises or consists of 4,4'-methylenebis(phenyl isocyanate).

10. The thermoplastic polyurethane of any of claims 1 to 9, wherein the polybutadiene polyol comprises or consists of polybutadiene diol.

11. The thermoplastic polyurethane of any of claims 1 to 10, wherein the polyether polyol comprises poly(tetramethylene ether glycol).

12. The thermoplastic polyurethane of any of claims 1 to 11, wherein the polyether polyol component comprises a mixture of poly(tetramethylene ether glycol) and ethylene oxide end capped poly(propylene glycol).

13. The thermoplastic polyurethane of any of claims 1 to 10, wherein the polyether polyol comprises polypropylene glycol.

14. An article made from the thermoplastic polyurethane composition of any of claims 1 to 13.