ANOTHER ALCOHOL OR POLYOL

FIELD OF INVENTION

[0001] The present application relates generally to novel liquid blends of organic compounds having a temperature at which a solid begins to form that is lower than the melting point of butanediol (including 1 ,4-butanediol). Methods of making and using the liquid blend are also disclosed herein.

BACKGROUND

[0002] Butanediol, including isomers thereof such as 1,4-butanediol (BDO, C4H10O2) and derivatives thereof are used in a wide variety of applications. 1,4-Butanediol is used industrially as a solvent and may be used as an intermediate in the production of paints, plastics, elastic fibers, and various polyurethane formulations (e.g., thermoplastic polyurethanes, cast elastomers, Spandex etc.). 1,4-butanediol may also be used to make solvent products, such as floor stripper, paint thinner.

[0003] 1,4-butanediol has a melting point of about 20 °C. As such, at room temperature (e.g., from about 18 °C to about 25 °C), 1,4-butanediol may be a solid or a very viscous liquid. In the handling of 1,4-butanediol and/or the processing of 1,4-butanediol into other formulations, undesirable solidification may occur. Additionally, 1 ,4-butanediol may become a super-cooled liquid, which appears to be a liquid that is ready for processing and/or formulating, but which also, when moved or exposed to air, crystalizes into a solid in a matter of seconds. This solidification can cause significant and costly delays in manufacturing and decreased efficiencies as a result of 1,4-butanediol being difficult to work with. To avoid solidification, measures may need to be taken to heat the infrastructure, tanks, and/or other equipment used during the handling and/or processing of 1,4-butanediol.

[0004] What is needed therefore, is a cost-effective and convenient method to improve the ability to utilize butanediol. In particular, what is needed is an improved methodology to maintain 1,4-butanediol in a usable state, for example, a homogeneous liquid state at reasonable temperatures, such as room temperature thereby reducing the need for specialized handling or specialized equipment.

SUMMARY

[0005] Embodiments of the present disclosure include a liquid blend comprising from about 1 wt% to about 99 wt% of 1,4-butanediol and from about 1 wt% to about 99 wt% of a modifier compound, the liquid blend may have a temperature at which a solid begins to form that is lower than the melting point of 1,4-butanediol.

[0006] In an embodiment of the instant disclosure, the modifier compound may be a mono-alcohol compound, a di-alcohol compound, or a tri-alcohol compound. In another embodiment, the modifier compound may be a di-alcohol compound selected from ethylene glycol, propylene glycol, 1,3-propanediol, 1,5-pentanediol (PDO), 1,6-hexanediol (HDO), 1,7-heptanediol, and 1,8-octanediol. In a specific embodiment, the modifier compound may be 1,5-pentanediol (PDO). In yet another embodiment, the liquid blend comprises from about 75 wt% to about 85 wt% of 1 ,4-butanediol and from about 15 wt% to about 25 wt% of 1,5- pentanediol, the liquid blend may have a temperature at which a solid begins to form that is lower than the melting point of 1,4-butanediol. In an embodiment, the color index of the liquid blend is improved compared to the color index of 1,4-butanediol. In another embodiment, the viscosity of the liquid blend is lower than the viscosity of the 1,4-butanediol at room temperature. In yet another embodiment, the hydrophilicity of the liquid blend is lower than the hydrophilicity of the 1,4-butanediol.

[0007] In a certain embodiment, a method of making a liquid blend is disclosed, the method comprises incorporating about 1 wt% to about 99 wt% of 1,5-pentanediol into a balance of 1,4-butanediol, wherein the liquid blend has a temperature at which a solid begins to form that is lower than a melting point of the 1 ,4-butanediol.

[0008] In a specific embodiment, a method of lowering a temperature at which a solid begins to form in 1,4-butanediol is disclosed, the method comprises adding about 1 wt% to about 99 wt% of 1,5-pentanediol into a balance of the 1,4-butanediol.

[0009] Also disclosed herein is a method of using the liquid blend to produce polyurethane, the method comprises (1) reacting an isocyanate component with an isocyanate-reactive component to form a polyurethane prepolymer; (2) reacting the polyurethane prepolymer with a chain extender, the chain extender comprises a liquid blend comprising about 1 wt% to about 99 wt% of 1,4-butanediol and about 1 wt% to about 99 wt% of 1,5-pentanediol; and (3) curing the resulting mixture from step (2).

[0010] Other features and advantages will become apparent from the following detailed description and drawing.

BRIEF DESCRIPTION OF THE FIGURES

[0011] In order to facilitate a fuller understanding of the present disclosure, reference is now made to the accompanying figures, in which like elements are referenced with like numerals. These figures should not be construed as limiting the present disclosure, but are intended to be illustrative only.

[0012] Fig. 1 is a graph illustrating the hydroxyl number of 1,5-pentanediol in 1,4- butanediol versus the mass fraction of the 1,5-pentanediol in the 1,4-butanediol;

[0013] Fig. 2 is a graph illustrating the effect on the temperature at which a solid begins to form by the addition of 1,5-pentanediol into 1,4-butanediol;

[0014] Fig. 3 shows the mechanical properties of polyurethanes elastomers prepared using 1 ,4-butanediol (BDO), 1 ,5-pentanediol (PDO), or 1,6-hexanediol (HDO) as a chain extender;

[0015] Fig. 4 shows dynamic mechanical analysis (DMA) of polyurethane prepared using

1.4- butanediol (BDO) as a chain extender;

[0016] Fig. 5 shows dynamic mechanical analysis (DMA) of polyurethane prepared using

1.5- pentanediol (PDO) as a chain extender; and

[0017] Fig. 6 shows dynamic mechanical analysis (DMA) of polyurethane prepared using

1.6- hexanediol (FIDO) as a chain extender.

DETAILED DESCRIPTION

[0018] To decrease the solidification temperature of 1,4-butanediol (BDO), a modifier compound may be added to BDO. In one embodiment, the modifier compound may be an alcohol compound. The alcohol compound can be a mono-alcohol compound, a di-alcohol compound (diol), or a tri-alcohol compound. In another embodiment, the modifier compound may be a diol, selected from ethylene glycol, propylene glycol, 1,2-propanediol, 1,3- propanediol, 1,5-pentanediol (PDO), 1 ,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol. In a specific embodiment, the modifier compound is PDO, which has a melting point of about - 18 °C. The BDO and PDO used in the instant disclosure may be produced from sources known to those skilled in the art, including but not limited to petroleum (petro-based), renewable feedstock (bio-based), or a mixture of petro-based and bio-based products. The BDO or PDO produced from petroleum or renewable feedstock may be substantially the same.

[0019] In the embodiments disclosed herein, 1,5-pentanediol may be added to 1,4- butanediol to form a liquid blend. The 1 ,5-pentanediol may be mixed with the 1,4-butanediol to specifically induce changes in the 1,4-butanediol on the molecular level (i.e., depression of a temperature at which a solid forms). Though not wishing to be bound by the following theory, it is thought that the mixture of 1,5-pentanediol and 1,4-butanediol induces changes in the crystallinity of 1 ,4-butanediol, and thus the liquid blend has a temperature at which a solid begins to form that is lower than the melting point of 1,4-butanediol alone. As illustrated in the Example section, the introduction of 1 ,5-pentanediol into 1,4-butanediol produces the liquid blend disclosed herein, which does not solidify when stored, transported, or processed at or below 20 °C. As such, the liquid blend is maintained in liquid form at or below room temperature, thus rendering the liquid blend easier to utilize (e.g., transport, store, etc.) and process than 1,4-butanediol alone.

[0020] The novel liquid blend described herein includes from about 1 wt% to about 99 wt% of 1,5-pentanediol and a balance of 1,4-butanediol (i.e., from about 99 wt% to about 1 wt% of 1,4-butanediol). In an example, the liquid blend consists of these two diols, with no other components. The lack of other components means that the total contents of the liquid blend are alpha-omega alkyldiols that i) render the chemical reactivity and concentration of the hydroxyl-groups quite similar to pure 1,4-butanediol (see Fig. 1) even though some amount of 1,5-pentanediol is present in the liquid blend and ii) does not significantly disrupt the function of the 1,4-butanediol when the liquid blend is used in most formulations. In an example, the liquid blend includes from about 75 wt% to about 85 wt% of the 1,4-butanediol and from about 15 wt% to about 25 wt% of the 1,5-pentanediol. In this particular example, the temperature of the liquid blend at which a solid begins to form ranges from about 4 °C to about 10 °C.

[0021] In addition to inducing changes in the crystallinity of the liquid blend, and thus reducing the temperature at which a solid begins to form, the inclusion of 1,5-pentanediol with 1,4-butanediol in the liquid blend may also induce changes in the viscosity, the color index, and/or the clarity of the liquid blend. In one embodiment, the color index of the liquid blend is improved compared to the color index of 1,4-butanediol. The color index can be quantified by measure its Refractive Index according to ASTM D1218-12. In another embodiment, the viscosity of the liquid blend is lower than a viscosity of 1,4-butanediol at room temperature. The liquid viscosity can be measured by a method as set forth in ASTM D445. In yet a further embodiment, a hydrophilicity of the liquid blend is lower than a hydrophilicity of 1,4-butanediol. 1,4-butanediol is hygroscopic, and thus absorbs moisture from the surrounding environment. 1,5-pentanediol is more hydrophobic, and reduces the ability of the 1,4-butanediol to absorb moisture. The hydrophilicity/hydrophobicity can be characterized by Advancing Contact Angle as set forth in ASTM D7334-08.

[0022] The liquid blend may be used in a variety of applications and/or products, including, for example, polyurethane formulations (e.g., thermoplastic polyurethanes, cast polyurethane elastomer formulations, polyurethane adhesive formulations, etc.) and coatings, polyester formulations (e.g., thermoplastic polyesters) and coatings, elastomers, solvent formulations, paints, plastics, etc. The improved properties of the liquid blend may improve the properties of the application and/or product. For example, a polyurethane formulation including the liquid blend may have improved clarity and/or color index. In addition to improving the melting point, viscosity, color index, clarity, and/or hydrophilicity of the application or product in which the liquid blend is included, the flexibility of the application or product may also be improved. Flexibility can be improved because the 1,5-pentanediol can soften the hard parts of the application or product. As an example, the 1,5-pentanediol can control the degree of hardness of the hard segments of elastomers.

[0023] In an example of the method for making the liquid blend and an example of a method for lowering the melting point of 1,4-butanediol, from about 1 wt% to about 99 wt% of 1,5-pentanediol is introduced into or added to a balance of 1,4-butanediol. The amount of 1 ,5-pentanediol may be adjusted in order to generate the liquid blend with a desirable melting point.

[0024] Without intending to be bound by theory, it is thought that the added PDO disrupts the organization of BDO molecular chains, which prevents BDO crystallization and leads to a lower solidification temperature. The liquid blend disclosed herein eliminates the heating process typically involved in the industrial application of BDO, which leads to a time- and energy-efficient production process. One skilled in the art would realize that melting temperature and solidification temperature refer to the same parameter, except they are measured in different ways. For the purpose of the application in this disclosure, solidification temperature is measured by observing the transition from a liquid to a white slurry indicating the formation of solid.

[0025] Also disclosed herein is a method of using the blend liquid to produce a polyurethane or polyurethane urea. The method comprises (1) reacting an isocyanate component with an isocyanate-reactive component to form a polyurethane prepolymer, (2) reacting the polyurethane prepolymer with a chain extender, the chain extender comprises a liquid blend comprising about 1 wt% to about 99 wt% of 1,4-butanediol and about 1 wt% to about 99 wt% of 1,5-pentanediol, and (3) curing the resulting mixture from step (2).

[0026] The isocyanate component may include, but is not limited to, isocyanates, diisocyanates, polyisocyanates, biurets of isocyanates and polyisocyanates, isocyanurates of isocyanates and polyisocyanates, and combinations thereof. In one embodiment, the isocyanate component includes an n-functional isocyanate, wherein "n" may be a number from 2 to 5, from 2 to 4, or from 3 to 4. It is to be understood that "n" may be an integer or may have intermediate values from 2 to 5. The isocyanate component may include an isocyanate selected from the group of aromatic isocyanates, aliphatic isocyanates, and combinations thereof. In another embodiment, the isocyanate component includes an aliphatic isocyanate such as hexamethylene diisocyanate, H12MDI, and combinations thereof. If the isocyanate component includes an aliphatic isocyanate, the isocyanate component may also include a modified multivalent aliphatic isocyanate, i.e., a product which is obtained through chemical reactions of aliphatic diisocyanates and/or aliphatic polyisocyanates. Examples include, but are not limited to, ureas, biurets, allophanates, carbodiimides, uretonimines, isocyanurates, urethane groups, dimers, trimers, and combinations thereof. The isocyanate component may also include, but is not limited to, modified diisocyanates employed individually or in reaction products with polyoxyalkyleneglycols, diethylene glycols, dipropylene glycols, polyoxyethylene glycols, polyoxypropylene glycols, polyoxypropylenepolyoxethylene glycols, polyesterols, polycaprolactones, and combinations thereof.

[0027] Alternatively, the isocyanate component may include an aromatic isocyanate. If the isocyanate component includes an aromatic isocyanate, the aromatic isocyanate may correspond to the formula R'(NCO) _z wherein R' is aromatic and z is an integer that corresponds to the valence of R'. Preferably, z is at least two. Suitable examples of aromatic isocyanates include, but are not limited to, tetramethylxylylene diisocyanate (TMXDI), 1,4- diisocyanatobenzene, 1,3-diisocyanato-o-xylene, 1,3-diisocyanato-p-xylene, 1 ,3- diisocyanato-m-xylene, 2,4-diisocyanato- 1 -chlorobenzene, 2,4-diisocyanato- 1 -nitro-benzene, 2,5-diisocyanato-l -nitrobenzene, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4- toluene diisocyanate, 2,6-toluene diisocyanate, mixtures of 2,4- and 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, 1 -methoxy-2,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'- dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'- diisocyanate, triisocyanates such as 4,4',4"-triphenylmethane triisocyanate polymethylene polyphenylene polyisocyanate and 2,4,6-toluene triisocyanate, tetraisocyanates such as 4,4'- dimethyl-2,2'-5,5'-diphenylmethane tetraisocyanate, toluene diisocyanate, 2,2'- diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate, corresponding isomeric mixtures thereof, and combinations thereof. Alternatively, the aromatic isocyanate may include a triisocyanate product of m-TMXDI and 1, 1,1 -trim ethylolpropane, a reaction product of toluene diisocyanate and 1,1,1-trimethyolpropane, and combinations thereof. In one embodiment, the isocyanate component includes a diisocyanate selected from the group of methylene diphenyl diisocyanates, toluene diisocyanates, hexamethylene diisocyanates, H12MDIs, and combinations thereof. The isocyanate component may have any % NCO content and any viscosity. The isocyanate component may also react with the isocyanate- reactive component and/or chain extender in any amount, as determined by one skilled in the art. Preferably, the isocyanate component and the isocyanate-reactive component and/or chain extender are reacted at an isocyanate index from 1 to 900, more preferably from 95 to 130, and alternatively from 105 to 130. In a specific embodiment, the chain extender can be the liquid blend disclosed herein.

[0028] The isocyanate-reactive component of the present invention may include one or more of a polyether polyol, a polyester polyol, and combinations thereof. As is known in the art, polyether polyols are typically formed from a reaction of an initiator and an alkylene oxide. Preferably, the initiator is selected from the group of aliphatic initiators, aromatic initiators, and combinations thereof. In one embodiment, the initiator is selected from the group of ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, trimethylene glycol, 1 ,2-butanediol, 1,3-butanediol, 1 ,4-butanediol, 1 ,2-pentanediol, 1 ,4-pentanediol, 1,5- pentanediol, 1,6-hexanediol, 1,7-heptanediol, butenediol, butynediol, xylylene glycols, amylene glycols, 1,4-phenylene-bis-beta-hydroxy ethyl ether, 1,3-phenylene-bis-beta- hydroxy ethyl ether, bis-(hydroxy-methyl-cyclohexane), thiodiglycol, glycerol, 1, 1, 1- trimethylolpropane, 1, 1, 1-trimethylolethane, 1,2,6-hexanetriol, .alpha. -methyl glucoside, pentaerythritol, sorbitol, aniline, o-chloroaniline, p-aminoaniline, 1,5-diaminonaphthalene, methylene dianiline, the condensation products of aniline and formaldehyde, 2,3-, 2,6-, 3,4-, 2,5-, and 2,4-diaminotoluene and isomeric mixtures, methylamine, triisopropanolamine, ethylenediamine, 1,3-diaminopropane, 1,3-diaminobutane, 1,4-diaminobutane, propylene diamine, butylene diamine, hexamethylene diamine, cyclohexalene diamine, phenylene diamine, tolylene diamine, xylylene diamine, 3,3'-dichlorobenzidine, 3,3'- and dinitrobenzidine, alkanol amines including ethanol amine, aminopropyl alcohol, 2,2-dimethyl propanol amine, 3-aminocyclohexyl alcohol, and p-aminobenzyl alcohol, and combinations thereof. It is contemplated that any suitable initiator known in the art may be used in the present invention.

[0029] In an embodiment, the alkylene oxide that reacts with the initiator to form the polyether polyol is selected from the group of ethylene oxide, propylene oxide, butylene oxide, amylene oxide, tetrahydrofuran, alkylene oxide-tetrahydrofuran mixtures, epihalohydrins, aralkylene oxides, and combinations thereof. In an alternative embodiment, the alkylene oxide is selected from the group of ethylene oxide, propylene oxide, and combinations thereof. Most preferably, the alkylene oxide includes ethylene oxide. However, it is also contemplated that any suitable alkylene oxide that is known in the art may be used in the present invention. The polyether polyol may include an ethylene oxide cap of from 5 to 20% by weight based on the total weight of the polyether polyol. It is to be understood that the terminology "cap" refers to a terminal portion of the polyether polyol. Without intending to be bound by any particular theory, it is believed that the ethylene oxide cap promotes an increase in a rate of the reaction of the polyether polyol and the isocyanate. The polyether polyol may also have a number average molecular weight of from 18 to 10,000 g/mol. Further, the polyether polyol may have a hydroxyl number of from 15 to 6,250 mg KOH/g. The polyether polyol may also have a nominal functionality of from 2 to 8. Further, further, the polyether polyol may also include an organic functional group selected from the group of a carboxyl group, an amine group, a carbamate group, an amide group, and an epoxy group.

[0030] Referring now to the polyester polyols introduced above, the polyester polyols may be produced from a reaction of a dicarboxylic acid and a glycol having at least one primary hydroxyl group. Suitable dicarboxylic acids may be selected from the group of, but are not limited to, adipic acid, methyl adipic acid, succinic acid, suberic acid, sebacic acid, oxalic acid, glutaric acid, pimelic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, and combinations thereof. Suitable glycols include, but are not limited to, those described above. The polyester polyol may also have a number average molecular weight of from 80 to 1500 g/mol. Further, the polyester polyol may have a hydroxyl number of from 40 to 600 mg KOH/g. The polyester polyol may also have a nominal functionality of from 2 to 8. Further, further, the polyester polyol may also include an organic functional group selected from the group of a carboxyl group, an amine group, a carbamate group, an amide group, and an epoxy group.

[0031] A catalyst component can be used to produce polyurethane in the current disclosure. In a specific embodiment, the catalyst component can be present in the isocyanate-reactive component to catalyze the flexible polyurethane foaming reaction between the isocyanate component and the isocyanate-reactive component. It is to be appreciated that the catalyst component is typically not consumed to form the reaction product of the isocyanate component and the isocyanate-reactive component. When utilized, the catalyst component can be present in the isocyanate-reactive component in an amount of from greater than 0 to about 2, more typically from about 0.10 to about 1 parts by weight based on 100 parts by weight of total polyol present in the isocyanate-reactive component. The catalyst component may include any suitable catalyst or mixtures of catalysts known in the art. Examples of suitable catalysts include, but are not limited to, gelation catalysts, e.g. crystalline catalysts in dipropylene glycol; blowing catalysts, e.g. bis(dimethylaminoethyl)ether in dipropylene glycol; and tin catalysts, e.g. tin octoate.

[0032] In other non-limiting embodiments described in further detail below, isocyanate and polyol can be reacted together to form a polyurethane prepolymer and the prepolymer can be reacted with more of the same or a different polyol(s) and/or diol(s) to form a polyurethane or sulfur-containing polyurethane. When the prepolymer method is employed, the prepolymer and diol(s) can be heated so as to reduce the prepolymer viscosity to about 200 cp or at most a few thousand centipoise so as to aid in mixing. As in the bulk polymerization, reaction should be conducted under anhydrous conditions with dry reactants. The reactants can be preheated to a temperature of at least about 100 °C, at least about 110 °C, or at least about 120 °C prior to reaction. The reactants can be maintained at a temperature of at least about 100 °C, at least about 110 °C or at least about 120 °C for at least about 10 minutes, or at least about 2 hours, to facilitate reaction. The mixture can be maintained at a pressure of ranging from about 2 to about 6 mm Hg (about 266.6 to about 800 Pascal (Pa)), or about 266.6 Pa for a time period of about 10 minutes to about 24 hours, or about 10 minutes to about 4 hours.

[0033] The polyurethane prepolymer may have a number average molecular weight (Mn) of less than about 50,000 grams/mole, or less than about 20,000 grams/mole, or less than about 10,000 grams/mole, or less than about 5,000 grams/mole, or at least about 1,000 grams/mole or at least about 2,000 grams/mole, inclusive of any range in between.

[0034] When polyurethane-forming components, such as polyols and isocyanates, are combined to produce polyurethanes, the relative amounts of the ingredients are typically expressed as a ratio of the available number of reactive isocyanate groups to the available number of reactive hydroxyl groups, i.e., an equivalent ratio of NCO:OH. For example, a ratio of NCO:OH of 1.0: 1.0 is obtained when the weight of one NCO equivalent of the supplied form of the isocyanate component is reacted with the weight of one OH equivalent of the supplied form of the organic polyol component. The polyurethanes of the present invention can have an equivalent ratio of NCO: OH ranging from about 0.9: 1.0 to about 1.1 : 1.0, or about 1.0: 1.0.

[0035] In some non-limiting embodiments, when the isocyanate and polyol are reacted to form a prepolymer, the isocyanate is present in excess, for example the amount of isocyanate and the amount of polyol in the isocyanate prepolymer can be selected such that the equivalent ratio of (NCO):(OH) can range from about 1.0:0.05 to about 1.0:0.7.

[0036] In some non-limiting embodiments, the amount of isocyanate and the amount of polyol used to prepare isocyanate-terminated polyurethane prepolymer or isocyanate- terminated sulfur-containing polyurethane prepolymer can be selected such that the equivalent ratio of (NCO):(SH+OH) can be at least about 1.0: 1.0, or at least about 2.0: 1.0, or at least about 2.5: 1.0, or less than about 4.5: 1.0, or less than about 5.5: 1.0; or the amount of isothiocyanate and the amount of polyol used to prepare isothiocyanate-terminated sulfur- containing polyurethane prepolymer can be selected such that the equivalent ratio of (NCS):(SH+OH) can be at least about 1.0: 1.0, or at least about 2.0: 1.0, or at least about 2.5: 1.0, or less than about 4.5: 1.0, or less than about 5.5: 1.0; or the amount of a combination of isothiocyanate and isocyanate and the amount of polyol used to prepare isothiocyanate/isocyanate terminated sulfur-containing polyurethane prepolymer can be selected such that the equivalent ratio of (NCS+NCO):(SH+OH) can be at least about 1.0: 1.0, or at least about 2.0: 1.0, or at least about 2.5: 1.0, or less than about 4.5: 1.0, or less than about 5.5: 1.0.

[0037] The ratio and proportions of the diol and the polyol can affect the viscosity of the prepolymer. The viscosity of such prepolymers can be important, for example when they are intended for use with coating compositions, such as those for flow coating processes. The solids content of such prepolymers, however, also can be important, in that higher solids content can achieve desired properties from the coating, such as weatherability, scratch resistance, etc. In conventional coatings, coating compositions with higher solids content typically require greater amounts of solvent material to dilute the coating in order to reduce the viscosity for appropriate flow coating processes. The use of such solvents, however, can adversely affect the substrate surface, particularly when the substrate surface is a polymeric material. In the present invention, the viscosity of the prepolymer can be appropriately tailored to provide a material with lower viscosity levels at higher solids content, thereby providing an effective coating without the need for excessive amounts of solvents which can deleteriously affect the substrate surface.

[0038] In some non-limiting embodiments in which optional amine curing agent is used, the amount of isocyanate-terminated polyurethane prepolymer or sulfur-containing isocyanate-terminated polyurethane prepolymer and the amount of amine curing agent used to prepare sulfur-containing polyurethane can be selected such that the equivalent ratio of (NH+SH+OH):(NCO) can range from about 0.80: 1.0 to about 1.1 : 1.0, or from about 0.85: 1.0 to about 1.0: 1.0, or from about 0.90: 1.0 to about 1.0: 1.0, or from about 0.90: 1.0 to about 0.95: 1.0, or from about 0.95: 1.0 to about 1.0: 1.0.

[0039] In some non-limiting embodiments, the amount of isothiocyanate or isothiocyanate/isocyanate terminated sulfur-containing polyurethane prepolymer and the amount of amine curing agent used to prepare sulfur-containing polyureaurethane can be selected such that the equivalent ratio of (NH+SH+OH):(NCO+NCS) can range from about 0.80: 1.0 to about 1.1 : 1.0, or from about 0.85: 1.0 to about 1.0: 1.0, or from about 0.90: 1.0 to about 1.0: 1.0, or from about 0.90: 1.0 to about 0.95: 1.0, or from about 0.95: 1.0 to about 1.0: 1.0.

[0040] The thermal cure cycle can vary depending on the reactivity and molar ratio of the reactants. In a non-limiting embodiment, the thermal cure cycle can include heating the mixture from room temperature to a temperature of about 200 °C. over a period of from about 0.5 hour to about 72 hours; or from about 80 °C. to about 150 °C. for a period of from about 5 hours to about 48 hours.

[0041] Reference will now be made to specific examples illustrating the disclosure. It is to be understood that the examples are provided to illustrate exemplary embodiments and that no limitation to the scope of the disclosure is intended thereby.

EXAMPLES

EXAMPLE 1

Concentration of hydroxyl groups in the BDO/PDO liquid blend is similar to that ofBDO

[0042] Different amounts of 1,4-butanediol and 1,5-pentanediol were combined together to form samples of the liquid blend disclosed herein. The mass fraction of 1,5-pentanediol in 1 ,4-butanediol ranged from 0 to 1. The hydroxyl number (as milligrams KOH per gram of the liquid blend (mixture)) was determined by multiplying the moles of OH in the liquid blend by 56.1074 and by 1000. The results are shown in Fig. 1. This example illustrates that the concentration of the hydroxyl groups in the liquid blends disclosed herein are similar to pure 1,4-butanediol even though some amount of 1,5-pentanediol is present in the liquid blend.

EXAMPLE 2

BDO/PDO liquid blends have lower solidification temperatures compared to BDO [0043] Different amounts of 1,4-butanediol and 1,5-pentanediol were added to 15 mm diameter test tubes, respectively, to form 1 comparative sample and 4 samples of the liquid blend disclosed herein. The five different combinations tested included 0 wt% 1,5- pentanediol/100 wt% 1,4-butanediol (comparative sample), about 10 wt% l ,5-pentanediol/90 wt% 1 ,4-butanediol (sample 1), about 20 wt% l ,5-pentanediol/80 wt% 1,4-butanediol (sample 2), about 35 wt% l,5-pentanediol/65 wt% 1,4-butanediol (sample 3), and about 40 wt% l,5-pentanediol/60 wt% 1,4-butanediol (sample 4).

[0044] The test tubes were set in a bath of ice water and salt. A thermocouple was inserted into each test tube and the temperature was monitored. The thermocouple was used to stir the mixture as the mixture cooled. Stirring/mixing was performed consistently to prevent supercooling, although sample 4 may have had some super-cooling. The temperature of the mixture was recorded regularly until the mixture turned from a liquid to a white slurry (i.e., until the 1 ,4-butanediol crystalized from the 1,5-pentanediol liquid).

[0045] The results are shown in Fig. 2. The addition of 1,5-pentanediol to 1,4-butanediol lowered the temperature at which a solid formed for each of samples 1-4. The temperature at which the solid formed for samples 3 and 4 decreased significantly, as the ratios of the two components approach the eutectic point.

[0046] It was also observed that each mixture remained crystal clear until about a degree above the respective melting points. The mixtures hazed slightly and then within a degree or two cooler, a white snow-like solid was formed in the liquid. About a minute after that, the solid mass was formed.

EXAMPLE 3

Polynrethanes using BDO, PDO, or HDO as chain extender

[0047] Comparative screening between BDO, PDO, and HDO was performed in order to evaluate the performance of the three diols when used as chain extenders in MDI/Polyether, catalyzed PU elastomer systems. The samples were prepared on a lab scale, using mechanically assisted handmix method for blending, and a heated steel mold manually clamped.

[0048] All specimens presented a light yellow hue, probably caused by the color of the components of the system, principally MDI and amine catalysts. The sample prepared with 1 ,5-pentanediol had a slightly higher coloration that the other two specimens prepared with 1 ,4-butanediol and 1 ,6-hexanediol. The transmittance (clarity of the polymer) was superior for the specimen prepared with PDO. The other two samples had a slight opaqueness, with HDO being slightly better than BDO.

[0049] In order to achieve consistency in the extended polymer network, the stoichiometry of the systems was calculated using molar equivalents for the diols, rather than -OH equivalents for their incorporation in the system blends. Fig. 3 shows the mechanical properties of polyurethanes elastomers prepared using BDO, PDO, or HDO as a chain extender. Based on the results, it can be seen that the average mechanical properties of the three sample groups perform according to expectations when the carbon number of the diols increase, especially for hardness and tear resistance. For elongation at break, and peak stress, it becomes evident that the polymer containing diols with even carbon numbers perform slightly better than the one made with an odd carbon number. The difference cannot be considered significant enough to disqualify one in front of the others regarding its mechanical performance.

Table 1. Glass transition temperatures of the polyurethane elastomer samples obtained from DMA characterization.

[0050] The sample was analyzed using the dynamic temperature ramp method at a heating rate of 5 °C/min. using a TA Instruments RSA3 DMA. Table 1 summarizes the observations made for the sample. The error in the temperature is +/- 2 °C. Fig. 4 shows DMA of polyurethane elastomer prepared using BDO as a chain extender, Fig. 5 shows DMA of polyurethane elastomer prepared using PDO as a chain extender, Fig. 6 shows DMA of polyurethane elastomer prepared using HDO as a chain extender. A slight difference can be noted between the polymers containing diols with even and odd number of carbons in the chain extender and can be attributed to the difference in the crystallinity of the polymer's cross-linked network. This difference is not significant enough to disqualify one chain extender in front of the other. The HDO sample broke at 83.84 °C and E' of 1.356xl0 ⁵ Pa, which is consistent with a softer, more flexible polymer.

[0051] Even though difference in the crystallinity of the final PU polymer can be noticed between BDO and PDO, it is not significant enough to be considered as a critical factor that would disqualify PDO as a substitute for BDO as chain extender for this type of elastomer applications. Preparing testing specimens using a metering unit to control the mixing and corroborate the initial findings is recommended. It is also noticeable that in the specimens prepared, PDO gives the PU polymer better transmittance and optical qualities than BDO, even though a slight coloration was detected. With the right combination of polyols, amines, and isocyanate, the coloration can be averted.

[0052] Reference throughout the specification to "one example", "another example", "an example", and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the example is included in at least one example described herein, and may or may not be present in other examples. In addition, it is to be understood that the described elements for any example may be combined in any suitable manner in the various examples unless the context clearly dictates otherwise.

[0053] It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, a range from about 75 wt% to about 85 wt% should be interpreted to include the explicitly recited limits of 75 wt% to 85 wt%, as well as individual values, such as 77.5 wt%, 80 wt%, 83 wt%, etc., and sub-ranges, such as from about 76 wt% to about 84 wt%, from about 78 wt% to about 82 wt%, etc. Furthermore, when "about" is utilized to describe a value, this is meant to encompass minor variations (up to +/- 10%) from the stated value.

[0054] In describing and claiming the examples disclosed herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0055] Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific composition and procedures described herein. Such equivalents are considered to be within the scope of this disclosure, and are covered by the following claims.