Electrostatic dissipative thermoplastic polyurethane composition

Abstract

The present invention relates to an electrostatic dissipative thermoplastic polyurethane composition wherein a thermoplastic polyurethane is combined with electrostatic dissipative additives including an imidazolium liquid salt.

Description

TITLEELECTROSTATIC DISSIPATIVE THERMOPLASTIC POLYURETHANE COMPOSITIONBACKGROUND OF THE INVENTION

[0001] The present invention relates to electrostatic dissipative thermoplastic polyurethanes (TPU) compositions.

[0002] The formation and retention of charges of static electricity on the surface of most plastics is well known. Many plastic materials have a significant tendency to accumulate static electrical charges due to low electrical conductivity. This type of formation and retention of charges of static electricity can be problematic. The presence of static electrical charges on sheets of thermoplastic film, for example, can cause the sheets to adhere to one another thus making their separation for further processing more difficult. Moreover, the presence of static electrical charges causes dust to adhere to items packaged in a plastic bag for example, which may negate any sales appeal.

[0003] The increasing complexity and sensitivity of microelectronic devices makes the control of static discharge of particular concern to the electronics industry. Even a low voltage discharge can cause severe damage to sensitive devices. The need to control static charge buildup and dissipation often requires the entire assembly environment for these devices to be constructed of partially conductive materials and / or electrostatic dissipative (or discharge) (ESD) materials. It also may require that electrostatic protective packages, tote boxes, casings, and covers be made from conductive polymeric materials to store, ship, protect, or support electrical devices and equipment.

[0004] The prevention of the buildup of static electrical charges which accumulate on plastics during manufacture or use has been accomplished by the use of various ESD additives such as antistatic agents and ESD ingredients. These additives can be applied as a coating which may be sprayed or dip coated on the article after manufacture, although this method usually results in a temporary solution. Alternatively, thesematerials can be incorporated into a polymer used to make the article during processing, thereby providing a greater measure of permanence.

[0005] TPU materials have properties that are desirable for a number of applications, however, certain TPU materials have been found unsuitable for applications which require ESD properties. Thus, there is a need for TPU compositions that possess both ESD properties as well as the known physical properties generally attributable to TPU materials.SUMMARY OF THE INVENTION

[0006] The present invention provides an electrostatic dissipative thermoplastic polyurethane (ESD-TPU) composition comprising a thermoplastic polyurethane and an electrostatic dissipative additive. The thermoplastic polyurethane comprises the reaction product of a polyol intermediate, a diisocyanate, and a chain extender. In one embodiment, the electrostatic dissipative additive is an imidazolium liquid salt. In another embodiment, the electrostatic dissipative additive is propylene carbonate. In another embodiment, the electrostatic dissipative additive is a mixture of an imidazolium liquid salt and propylene carbonate.

[0007] For example, in one embodiment, the electrostatic dissipative thermoplastic polyurethane composition comprises (i) a thermoplastic polyurethane prepared from the reaction of a polyester polyol intermediate, a diisocyanate, and a chain extender, and (ii) an electrostatic dissipative additive comprising an imidazolium liquid salt, and propylene carbonate. As another example, the electrostatic dissipative thermoplastic polyurethane composition comprises (i) a thermoplastic polyurethane prepared from the reaction of a polyether polyol intermediate, a diisocyanate, and a chain extender and (ii) an electrostatic dissipative additive comprising an imidazolium liquid salt.DETAILED DESCRIPTION OF THE INVENTION

[0008] Various features and embodiments of the invention will be described below by way of non-limiting illustration.The Thermoplastic Polyurethane

[0009] The thermoplastic polyurethane (TPU) polymers used in this invention are made by reaction of three reactants. The first reactant is a polyol intermediate, the second reactant is a diisocyanate, and the third reactant is a chain extender. Each of the three reactants is discussed below.The Polyol Intermediate

[0010] In one embodiment, the polyol intermediate used to prepare the thermoplastic polyurethane for the present invention is a polyester polyol intermediate. Polyester polyols are prepared from the reaction of dialkylene glycols with dicarboxylic acids, or an ester or anhydride thereof.

[0011] Polyester polyol intermediates used in the present invention may include at least one terminal hydroxyl group, and in some embodiments, at least one terminal hydroxyl group and one or more carboxylic acid groups. In another embodiment, the polyester polyol intermediates include two terminal hydroxyl groups, and in some embodiments, two hydroxyl groups and one or more, or two, carboxylic acid groups. The polyester polyol intermediates are generally a substantially linear, or linear, polyester having a number average molecular weight (Mn) of from about 500 to about 10,000, about 500 to about 5000, or from about 1000 to about 3000, or about 2000.

[0012] In some embodiments, the polyester polyol intermediate may have a low acid number, such as less than 1.5, less than 1.0, or even less than 0.8. A low acid number for the polyester polyol intermediate may generally provide improved hydrolytic stability in the resulting TPU polymer. The acid number may be determined by ASTM D-4662 and is defined as the quantity of base, expressed in milligrams of potassium hydroxide that is required to titrate acidic constituents in 1.0 gram of sample. Hydrolytic stability' can also be improved by adding hydrolytic stabilizers to the TPU which are known to those skilled in the art of formulating TPU polymers.

[0013] Dialkylene glycols suitable for use in preparing the polyester polyol intermediate of the present invention may be aliphatic, cyclo-aliphatic, aromatic, or combinations thereof. Suitable glycols may contain from 2 or 4 or 6 to 20, 14, 8, 6 or 4 carbon atoms, and in some embodiments may contain 2 to 12, 2 to 8 or 6, 4 to 6, or even 4 carbon atoms. In some embodiments, the dialkylene glycol includes oxydimethanol, diethylene glycol, dipropylene glycol, 3,3-oxydipropan-l-ol, dibutylene glycol, or combinations thereof. In other embodiments, one or more of the dialkylene glycols listed may be excluded from the present invention. Blends of two or more glycols may be used. In some embodiments, monoalkylene glycols may be used in combination with the dialkylene glycols described above. In other embodiments, the glycol used to prepare the polyester polyol intermediate is free of monoalkylene glycols.

[0014] Dicarboxylic acids suitable for use in preparing the polyester polyol intermediate of the present invention may be aliphatic, cyclo-aliphatic, aromatic, orcombinations thereof. Suitable acids may contain from 2, 4, or 6 to 20, 15, 8, or 6 carbon atoms, and in some embodiments may contain 2 to 15, 4 to 15, 4 to 8, or even 6 carbon atoms. In some embodiments, the dicarboxylic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, isophthalic acid, terephthalic acid, cyclohexane dicarboxylic acid, or combinations thereof. In other embodiments, one or more of the dicarboxylic acids listed may be excluded from the present invention.

[0015] The polyester polyol intermediates of the present invention may also be derived from an ester or anhydride of one or more the dicarboxylic acids described above or combinations of such materials. Suitable anhydrides include succinic anhydride, alkyl and / or alkenyl succinic anhydride, phthalic anhydride and tetrahydrophthalic anhydride. In some embodiments, the acid is adipic acid. Blends of two or more acids may be used.

[0016] The polyester polyol intermediates of the present invention are prepared by reacting one or more of the dialkylene glycol described above with one or more of the dicarboxylic acids described above, and / or one or more of the esters or anhydrides thereof. In some embodiments, more than one equivalent of glycol is used for each equivalent of acid. The preparation includes (1) an esterification reaction of one or more dialkylene glycols with one or more dicarboxylic acids or anhydrides or (2) by transesterification reaction, i.e., the reaction of one or more dialkylene glycols with esters of dicarboxylic acids. Mole ratios generally in excess of more than one mole of glycol to acid are preferred so as to obtain linear chains having a preponderance of terminal hydroxyl groups.

[0017] In another embodiment, the polyol intermediate used in preparing the thermoplastic polyurethane of the present invention is a polyether polyol. Polyether polyol intermediates include polyether polyols 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, hy droxyl 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, polypropylene 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. In some embodiments, the polyether intermediate includes 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, di ethylenetri amine adduct comprising the reaction product of di ethylenetriamine 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 Poly THF® R, a random copolymer. The various polyether intermediates generally have a number average molecular weight (Mn) as determined by assay of the terminal functional groups which is an average molecular weight greater than about 700, such as from about 700 to about 10,000, from about 1,000 to about 5,000, or from about 1,000 to about 2,500. In some embodiments, the polyether intermediate includes a blend of two or more different molecular weight poly ethers, such as a blend of 2,000 Mn and 1,000 Mn PTMEG.

[0018] In some embodiments, the polyol intermediate comprises or consists of a polyester polyol. In other embodiments, the polyol intermediate comprises or consists of a polyether polyol. Mixtures of polyester polyols and / or polyether polyols are also within the scope of the invention.The Diisocyanate

[0019] The second reactant used to prepare the TPU for this invention is a diisocyanate. Suitable diisocyanates include: (i) aromatic diisocyanates such as: 4,4'- methylenebis-(phenyl isocyanate) (MDI), m-xylylene diisocyanate (XDI), phenylene- 1,4-diisocyanate, 1,5-naphthalene diisocyanate, diphenylmethane-3,3'-dimethoxy-4,4'- diisocyanate (TODI), and toluene diisocyanate (TDI); as well as (ii) aliphatic diisocyanates such as: isophorone diisocyanate (IPDI), 1.4-cyclohexyl diisocyanate (CHDI), decane- 1,10-diisocyanate, hexamethylene diisocyanate (HDI), and dicyclohexylmethane-4,4'-diisocyanate. In some embodiments, the diisocyanate is 4,4'-methylenebis(phenyl isocyanate) (MDI). In other embodiments, one or more of the diisocyanates listed may be excluded from the present invention.

[0020] A mixture of two or more diisocyanates can be used. Also, small amounts of isocyanates having a functionality greater than 2, such as tri-isocyanates can be used together with the diisocyanates. Large amounts of isocyanates with a functionality of 3 or more should be avoided as they will cause the TPU polymer to be cross linked.The Chain Extender

[0021] The third reactant for the thermoplastic polyurethane of this invention is a chain extender component. Suitable chain extenders include glycols and can be aliphatic, aromatic or combinations thereof. In some embodiments, the chain extenders are glycols having from 2 to about 12 carbon atoms.

[0022] In some embodiments, the glycol chain extenders are lower aliphatic or short chain glycols having from about 2 to about 10 carbon atoms and include, for instance: ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1 ,4-butanediol, 1,6-hexanediol, 1,3-butanediol, 1,5-pentanediol, 1,4-cyclohexanedimethanol, neopenty glycol, and the like. In some embodiments, the chain extender includes 1,4- butanediol.

[0023] Aromatic glycols may also be used as the chain extender to make the TPU including benzene glycol and xylene glycol. Xylene glycol is a mixture of 1,4- di(hydroxymethyl)benzene and l,2-di(hydroxymethyl)benzene. Benzene glycol specifically includes hydroquinone, bis(beta-hydroxyethyl)ether also known as 1 ,4-di(2- hydroxyethoxy)benzene; resorcinol, bis(beta-hydroxyethyl)ether also known as 1,3- di(2-hydroxyethyl)benzene; catechol, bis (beta-hydroxy ethyl) ether also known as 1,2- di(2-hydroxyethoxy)benzene; and combinations thereof.

[0024] A mixture of two or more glycols may be used as the chain extender in the TPU of this invention. In some embodiments, the chain extender is a mixture of 1,4- butanediol and 1,6-hexanediol. In other embodiments, one or more of the chain extenders listed may be excluded from the present invention.

[0025] Diamines may also be used as a chain extender, as is well known in the art. In one embodiment of the present invention, the chain extender contains a diamine as a co-chain extender in combination with one or more of the chain extenders described above. In other embodiments the present invention does not use any diamines in the preparation of its compositions.The Process of Making the TP U

[0026] The three reactants (the polyol intermediate, the diisocyanate, and the chain extender) are reacted together to form the TPU of this invention. Any known processes to react the three reactants may be used to make the TPU. In one embodiment, the process is a so-called "one-shot" process where all three reactants are added to an extruder reactor and reacted. The equivalent weight amount of the diisocyanate to the total equivalent weight amount of the hydroxyl containing components, that is, the polyester polyol intermediate and the chain extender glycol, can be from about 0.95 to about 1.10, or from about 0.96 to about 1.02, and even from about 0.97 to about 1.005. Reaction temperatures utilizing a urethane catalyst can be from about 175 degrees C to about 245 degrees C, and in other embodiment from 180 degrees C to 220 degrees C.

[0027] Generally, any conventional catalyst can be utilized to react the diisocyanate with the polyester polyol intermediates or the chain extender. Examples of suitable catalysts include the various alkyl amines, alkyl ethers or alkyl thiol ethers of bismuth or tin wherein the alkyl portion has from 1 to about 20 carbon atoms with specific examples including bismuth octoate, bismuth laurate, and the like. Preferred catalysts include the various tin catalysts such as stannous octoate, dibutyltin dioctoate, dibutyltin dilaurate, and the like. The amount of such catalyst is generally small, such as from about 20 to about 200 parts per million based upon the total weight of the polyurethane forming reactants.

[0028] The TPU can also be prepared utilizing a pre-polymer process. In the prepolymer route, the polyester 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. The reaction is generally carried out at temperatures of from about 80 degrees C to about 220 degrees C, or from about 150 degrees C to about 200 degrees C in the presence of a suitable urethane catalyst. 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. The overall equivalent ratio of the total diisocyanate to the total equivalent of the hydroxyl terminated polyesters and the chain extender is thus from about 0.95 to about 1.10, or from about 0.96 to about 1.02 and even from about 0.97 to about 1.05. The chain extension reaction temperature is generally from about 180 degrees C to about 250 degrees C, or from about 200 degrees C to about 240degrees C. Typically, the pre-polymer route can be carried out in any conventional device including an extruder. In such embodiments, the polyester polyol intermediates are reacted with an equivalent excess of a diisocyanate in a first portion of the extruder to form a pre-polymer solution and subsequently the chain extender is added at a downstream portion and reacted with the pre-polymer solution. Any conventional extruder can be utilized, including extruders equipped with barrier screws having a length to diameter ratio of at least 20 and in some embodiments at least 25.

[0029] In one embodiment, the ingredients are mixed in a single or twin screw extruder with multiple heat zones and multiple feed ports between its feed end and its die end. The ingredients may be added at one or more of the feed ports and the resulting TPU composition that exits the die end of the extruder may be pelletized.

[0030] In some embodiments, component (a), the polyester polyol intermediate includes poly(diethylene glycol adipate), component (b), the diisocyanate includes 4,4'- methylenebis-(phenyl isocyanate), and component (c), the chain extender includes butanediol, HQEE (hydroquinone bis(2-hydroxyethyl)ether), or combinations thereof.

[0031] The ESD additives as set forth herein may be combined with the TPU by any means or methods understood by those skilled in the art, whether now known or developed in the future. For example, the ESD additives may be incorporated into the TPU composition in situ during the TPU synthesis or may be compounded with a previously made TPU.The Electrostatic Dissipative Additive

[0032] The electrostatic dissipative thermoplastic polyurethane composition of the present invention also comprises an electrostatic dissipative additive. In one embodiment, the electrostatic dissipative additive comprises or consists of an imidazloium liquid salt. Imidazolium salts are made of a discrete organic cation and anion pair. In the present invention, the organic cation comprises or consists of an imidazolium cation. Examples of useful imidazolium liquid salts include l-methyl-3- octylimidazolium chloride; l-methyl-3-octylimidazolium bromide; l-methyl-3- octylimidazolium iodide; 1 -methyl-3-octylimidazolium hexafluorophosphate; 1-methyl- 3-octylimidazolium tetrafluoroborate; l-methyl-3-octylimidazolium hexafluoroantimonate; l-methyl-3-octylimidazolium trifluoromethanesulfonate; 1- methyl-3-octylimidazolium methyl sulfate; l-methyl-3-octylimidazolium ethyl sulfate; l-methyl-3-octylimidazolium acetate; l-methyl-3-octylimidazolium thiocyanate; 1-methy 1-3 -octylimidazolium dicyanamide; l-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)amide; l-Butyl-3-methylimidazolium tetrafluoroborate; 1- octyl-2,3-dimethylimidazolium chloride; l-octyl-2,3-dimethylimidazolium bromide; 1- octyl-2,3-dimethylimidazolium iodide; l-octyl-2.3-dimethylimidazolium hexafluorophosphate; l-octyl-2,3-dimethylimidazolium tetrafluoroborate; l-octyl-2,3- dimethylimidazolium hexafluoroantimonate; l-octyl-2,3-dimethylimidazolium trifluoromethanesulfonate; l-octyl-2,3-dimethylimidazolium methyl sulfate; 1-octyl- 2,3-dimethylimidazolium ethyl sulfate; l-octyl-2,3-dimethylimidazolium acetate; 1- octyl-2,3-dimethylimidazolium thiocyanate; l-octyl-2,3-dimethylimidazolium di cyanamide; l-octyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)amide; 1- ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide; l-decyl-3- methylimidazolium chloride; l-decyl-3-methylimidazolium bromide; l-decyl-3- methylimidazolium iodide; l-decyl-3-methylimidazolium hexafluorophosphate; 1- decyl-3-methylimidazolium tetrafluoroborate; 1 -decyl-3-methylimidazolium hexafluoroantimonate; l-decyl-3-methylimidazolium trifluoromethanesulfonate; 1- decyl-3-methylimidazolium methyl sulfate; l-decyl-3-methylimidazolium ethyl sulfate; l-decyl-3-methylimidazolium acetate; l-decyl-3-methylimidazolium thiocyanate; 1- decyl-3-methy limidazolium di cyanamide; 1 -decy 1-3-methylimidazolium bis(trifluoromethylsulfonyl)amide; l-Ethyl-3-methylimidazolium ethyl sulfate; 1- dodecyl-3-methylimidazolium chloride; l-dodecyl-3-methylimidazolium bromide; 1- dodecyl-3-methylimidazolium iodide; 1 -dodecyl-3-methylimidazolium hexafluorophosphate; l-dodecyl-3-methy limidazolium tetrafluoroborate; 1-dodecy 1-3- methylimidazolium hexafluoroantimonate; 1-dodecy 1-3-methylimidazolium trifluoromethanesulfonate; l-dodecyl-3-methylimidazolium methyl sulfate; 1-dodecyl- 3-methylimidazolium ethyl sulfate; l-dodecyl-3-methylimidazolium acetate; 1-dodecyl- 3 -methy limidazolium thiocyanate; l-dodecyl-3-methylimidazolium dicyanamide; 1- dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide; 1 -tetradecyl-3 - methylimidazolium chloride; 1 -tetradecyl-3 -methy limidazolium bromide; 1-tetradecyl- 3 -methy limidazolium iodide; l-tetradecyl-3-methylimidazolium hexafluorophosphate; l-tetradecyl-3-methylimidazolium tetrafluoroborate; l-tetradecyl-3-methylimidazolium hexafluoroantimonate; l-tetradecyl-3-methylimidazolium trifluoromethanesulfonate; 1- tetradecyl-3-methylimidazolium methyl sulfate; l-tetradecyl-3-m ethylimidazolium ethyl sulfate; l-tetradecyl-3-methylimidazolium acetate; 1 -tetradecyl-3-methylimidazolium thiocyanate; l-tetradecyl-3-methylimidazolium dicyanamide; 1- tetradecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide; l-hexadecyl-3- methylimidazolium chloride; 1 -hexadecyl-3 -methylimidazolium bromide: 1-hexadecyl- 3 -methylimidazolium iodide; l-hexadecyl-3-methylimidazolium hexafluorophosphate; 1 -hexadecyl -3-methylimidazolium tetrafluoroborate; l-hexadecyl-3-methylimidazolium hexafluoroantimonate; l-hexadecyl-3-methylimidazolium trifluoromethanesulfonate; 1- hexadecyl-3-methylimidazolium methyl sulfate; l-hexadecyl-3-methylimidazolium ethyl sulfate; l-hexadecyl-3-methylimidazolium acetate; l-hexadecyl-3- methylimidazolium thiocyanate; l-hexadecyl-3-methylimidazolium dicyanamide; 1- hexadecyl-3-m ethylimidazolium bis(trifluoromethylsulfonyl)amide.

[0033] In the present invention, the imidazolium liquid salt is added to the thermoplastic polyurethane in an amount of 0.5 parts per hundred to 25 parts per hundred or 1 parts per hundred to 20 parts per hundred, or even 1 part per hundred to 16 parts per hundred (based on 100 parts of the thermoplastic polyurethane).

[0034] In another embodiment, the present invention includes a co-solvent in addition to the imidazolium liquid salt. Suitable co-solvents include ethylene carbonate, propylene carbonate, dimethyl sulfoxide, tetramethylene sulfone, tri- and tetra ethylene glycol dimethyl ether, gamma butyrolactone, and N-methyl-2-pyrrolidone. In particular, propylene carbonate has surprisingly been found to lower the surface resistivity of thermoplastic polyurethane composition.

[0035] In one embodiment of the present invention, propylene carbonate is added to the thermoplastic polyurethane in an amount of 5 parts per hundred to 40 parts per hundred or 10 parts per hundred to 30 parts per hundred (based on 100 parts of the thermoplastic polyurethane).

[0036] In some embodiments of the invention, the thermoplastic polyurethane composition is substantially free to free of any or all metal containing salts, such as lithium salts. As used herein, “substantially free” means that the amount of the material in question is less than an amount that will affect the relevant performance of the fluid in a measurable way. “Substantially free” may also mean that the material in question is not intentionally added to the composition, but does not exclude the presence of such material as contaminants. “Substantially free” may also mean that the material in question may be present in amounts lower than the detection limit of standard test methods now known tothose skilled in the art or hereafter developed. In some embodiments, “substantially free” may mean less than 10 ppm by weight or even less than 5 ppm by weight.

[0037] An ESD-TPU compositions of the present invention has improved ESD properties compared other ESD-TPU compositions containing metal salts and, in some embodiments, the combination of the imadizolium liquid salt and propylene carbonate solvent show a synergistic improvement in ESD properties.

[0038] In some embodiments, the ESD-TPU polymer compositions of the present invention have a surface resistivity of no more than, or below l.OxlO8ohm / square. and / or a volume resistivity of no more than, or below, l.OxlO7ohm-square.

[0039] The electrostatic dissipative composition of the present invention may have several embodiments. For example, the present invention is an electrostatic dissipative thermoplastic polyurethane composition comprising (a) a thermoplastic polyurethane comprising the reaction product of a polyester polyol intermediate, a diisocyanate, and a chain extender; (b) an imidazolium liquid salt; and (c) propylene carbonate, wherein the imidazolium liquid salt is selected from l-ethyl-3-methylimidazoium bis(trifluoromethylsulfonyl) imide, l-butyl-3-methylimidazolium tetrafluoroborate, and mixtures thereof, and wherein the propylene carbonate is added to the thermoplastic polyurethane in an amount of 5 parts per hundred to 40 parts per hundred or 10 parts per hundred to 30 parts per hundred based on 100 parts of the thermoplastic polyurethane and the imidazolium liquid salt is added to the thermoplastic polyurethane in an amount of 0.5 parts per hundred to 25 parts per hundred or 1 part per hundred to 20 parts per hundred, or 2 parts per hundred to 16 parts per hundred based on 100 parts of the thermoplastic polyurethane. In another example of the present invention, an electrostatic dissipative thermoplastic polyurethane composition comprises (a) a thermoplastic polyurethane comprising the reaction product of a polyester polyol intermediate, 4,4'- methylenebis-(phenyl isocyanate), and 1.4-butanediol; (b) an imidazolium liquid salt; and (c) propylene carbonate, wherein the imidazolium liquid salt is selected from l-ethyl-3- methylimidazoium bis(trifluoromethylsulfonyl) imide, l-butyl-3-methylimidazolium tetrafluoroborate, and mixtures thereof, and wherein the propylene carbonate is added to the thermoplastic polyurethane in an amount of 5 parts per hundred to 40 parts per hundred or 10 parts per hundred to 30 parts per hundred based on 100 parts of the thermoplastic polyurethane and the imidazolium liquid salt is added to the thermoplastic polyurethane in an amount of 0.5 parts per hundred to 25 parts per hundred or 1 part perhundred to 20 parts per hundred, or 2 parts per hundred to 16 parts per hundred based on 100 parts of the thermoplastic polyurethane. In still another example, present invention is an electrostatic dissipative thermoplastic polyurethane composition comprising (a) a thermoplastic polyurethane comprising the reaction product of a polyether polyol intermediate, a diisocyanate, and a chain extender and (b) an imidazolium liquid salt wherein the imidazolium liquid salt is l-butyl-3-methylimidazolium tetrafluoroborate wherein the imidazolium liquid salt is added to the thermoplastic polyurethane in an amount of 0.5 parts per hundred to 25 parts per hundred or 1 part per hundred to 20 parts per hundred, or 2 parts per hundred to 16 parts per hundred, or 2 parts per hundred to 6 parts per hundred based on 100 parts of the thermoplastic polyurethane. In another example, present invention is an electrostatic dissipative thermoplastic polyurethane composition comprising (a) a thermoplastic polyurethane comprising the reaction product of a polyether polyol intermediate, 4,4'-methylenebis-(phenyl isocyanate), and 1 ,4-butanediol and (b) an imidazolium liquid salt wherein the imidazolium liquid salt is 1 -buty 1-3 -methyl imidazolium tetrafluoroborate wherein the imidazolium liquid salt is added to the thermoplastic polyurethane in an amount of 0.5 parts per hundred to 25 parts per hundred or 1 part per hundred to 20 parts per hundred, or 2 parts per hundred to 16 parts per hundred, or 2 parts per hundred to 6 parts per hundred based on 100 parts of the thermoplastic polyurethane.Addi ti onal Addi ti ves

[0040] The compositions of the present invention may further include additional useful additives, where such additives can be utilized in suitable amounts. These optional additional additives include opacifying pigments, colorants, mineral and / or inert fillers, stabilizers including light stabilizers, lubricants, UV absorbers, processing aids, antioxidants, antiozonates, and other additives as desired. Useful opacif ing pigments include titanium dioxide, zinc oxide, and titanate yellow. Useful tinting pigments include carbon black, yellow oxides, brown oxides, raw and burnt sienna or umber, chromium oxide green, cadmium pigments, chromium pigments, and other mixed metal oxide and organic pigments. Useful fillers include diatomaceous earth (superfloss) clay, silica, talc, mica, wallostonite. barium sulfate, and calcium carbonate. If desired, useful stabilizers such as antioxidants can be used and include phenolic antioxidants, while useful photostabilizers include organic phosphates, and organotin thiolates (mercaptides). Useful lubricants include metal stearates, paraffin oils andamide waxes. Useful UV absorbers include 2-(2'-hydroxyphenyl) benzotriazoles and 2- hydroxybenzophenones. Additives can also be used to improve the hydrolytic stability of the TPU polymer. Each of these optional additional additives described above may be present in, or excluded from, the compositions of the present invention.

[0041] When present, these additional additives may be present in the compositions of the present invention from 0 or 0.01 to 5 or 2 weight percent of the composition. These ranges may apply separately to each additional additive present in the composition or to the total of all additional additives present.Polymer Containinz Blends

[0042] The ESD-TPU polymers of the present invention may be blended with a matrix or base polymer to form a polymer blend. These blends may also be made with the salt-modified ESD-TPU polymers described above.

[0043] Suitable base polymers as defined herein can be a homopolymer or a copolymer. The base polymer may be a blend of multiple base polymers, and may further include any of the additional additives described above, including ESD additives. In some embodiments, the base polymer and / or the compositions of the present invention are substantially free to free of ESD additives.

[0044] The base polymer may include:(i) a polyolefin (PO), such as polyethylene (PE), polypropylene (PP), polybutene, ethylene propylene rubber (EPR), polyoxyethylene (POE), cyclic olefin copolymer (COC), or combinations thereof;(ii) a styrenic, such as polystyrene (PS), acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN), styrene butadiene rubber (SBR or HIPS), polyalphamethylstyrene, methyl methacrylate styrene (MS), styrene maleic anhydride (SMA), styrene-butadiene copolymer (SBC) (such as styrene-butadiene-styrene copolymer (SBS) and styrene-ethylene / butadiene-styrene copolymer (SEBS)), styrene- ethylene / propylene-styrene copolymer (SEPS), styrene butadiene latex (SBL), SAN modified with ethylene propylene diene monomer (EPDM) and / or acrylic elastomers (for example, PS-SBR copolymers), or combinations thereof;(iii) a thermoplastic polyurethane (TPU);(iv) a polyamide, such as Nylon™, including polyamide 6,6 (PA66), polyamide 1,1 (PA11), polyamide 1,2 (PA12), a copolyamide (COPA), or combinations thereof;(v) an acrylic polymer, such as polymethyl acrylate, polymethylmethacrylate, or combinations thereof;(vi) a polyvinylchloride (PVC), a chlorinated polyvinylchloride (CPVC), or combinations thereof;(vii) a polyoxymethylene, such as polyacetal;(viii) a polyester, 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) polylatic acid (PLA), or combinations thereof;(ix) a polycarbonate (PC), a polyphenylene sulfide (PPS), a polyphenylene oxide (PPO), or combinations thereof; or combinations thereof.

[0045] Polyvinyl chloride (PVC), vinyl polymer, or vinyl polymer material, as used herein, refers to homopolymers and copolymers of vinyl halides and vinylidene halides and includes post halogenated vinyl halides such as CPVC. Examples of these vinyl halides and vinylidene halides are vinyl chloride, vinyl bromide, vinylidene chloride and the like. The vinyl halides and vinylidene halides may be copolymerized with each other or each with one or more polymerizable olefinic monomers having at least one terminal CH2=C< grouping. As examples of such olefinic monomers there may be mentioned the alpha, beta-olefinically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, ethyl acrylic acid, alpha-cyano acrylic acid, and the like; esters of acrylic acid, such as methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, cyanoethyl acrylate, hydroxy ethyl acrylate, and the like; esters of methacrylic acid, such as methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, and the like; nitriles, such as acrylonitrile, methacrylonitrile, and the like; acrylamides, such as methyl acrylamide, N-methylol acrylamide, N-butyoxy methylacrylamide, and the like; vinyl ethers, such as ethyl vinyl ether, chloroethyl vinyl ether, and the like; the vinyl ketones; styrene and styrene derivatives, such as .alpha. -methyl styrene, vinyl toluene, chlorostyrene, and the like; vinyl naphthalene, allyl and vinyl chloroacetate, vinyl acetate, vinyl pyridine, methyl vinyl ketone; the diolefins, including butadiene, isoprene, chloroprene, and the like; and other polymerizable olefinic monomers of the types known to those skilled in the art. In one embodiment, the base polymer includes polyvinyl chloride (PVC) and / or polyethylene terephthalate (PET).Industrial Application

[0046] The compositions of the present invention, including the blends described above, are useful for a variety of applications. Some examples are tubes, paper trays, floor tiles, machine housings, construction and manufacturing equipment, and polymeric sheets and films. More specifically, examples include fuel handling equipment such as fuel lines and vapor return equipment, business equipment, coatings for floors such as for clean rooms and construction areas, applications, clean room equipment including garments, floorings, mats, electronic packaging, and housings, chip holders, chip rails, tote bins and tote bin tops, medical applications, battery parts such as dividers and / or separators, and generally shaped articles.

[0047] In one embodiment, the compositions of the present invention are used to make polymeric articles to be used as: packaging materials for electronic parts: internal battery separators for use in the construction of lithium-ion batteries; clean room supplies and construction materials; antistatic conveyor belts; parts for office machines; antistatic garments and shoes, or combinations thereof.

[0048] Electronic parts include ESD sensitive parts including semiconductors. The articles of the present invention may also be durable or consumable parts for clean room equipment and applications. Also included are construction and / or building materials for clean rooms and data centers, which may include items such as softwalls, curtains, flooring, benches, etc. The articles of the present invention also include laminated sheets, conveyor belts for manufacturing of food, pharmaceutical products, medical devices, and electronic components, or combinations thereof.

[0049] Furthermore, the compositions of the present invention may be used to prepare separators and other components of lithium-ion batteries, lithium-polymer batteries and fuel cells. Such uses of the compositions and articles of the present invention offer advantages over current batteries and fuel cells in the areas of improved safety, performance, cost, or combinations thereof. The compositions of the present invention may be used to construct separator layers that are placed between the anodes of the battery', as well as polymer electrolyte membranes.

[0050] The compositions can be used with various molding techniques including injection molding, compression molding, slush molding, extrusion, thermoforming cast, rotational molding, sintering, and vacuum molding. Articles of this invention may also be made from resins produced by the suspension, mass, emulsion or solution processes.

[0051] It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. For instance, metal ions (of, e.g.. a detergent) can migrate to other acidic or anionic sites of other molecules. The products formed thereby, including the products formed upon employing the composition of the present invention in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present invention; the present invention encompasses the composition prepared by admixing the components described above.EXAMPLES

[0052] The invention will be further illustrated by the following examples, which sets forth particularly advantageous embodiments. While the examples are provided to illustrate the present invention, they are not intended to limit it.ExamplesA TPU composition is prepared by 4,4'-methylenebis-(phenyl isocyanate), 1,4- butanediol and the polyol component as set forth in Table 1. Each TPU composition was then doped with the noted amounts of electrostatic dissipative additives (in parts per hundred (phr) based on 100 parts of the TPU) as noted in Table 1. ESD Additive 1 (ADD 1) is Lithium salt of bis((trifluoromethyl)sulfonyl) azanide, ESD Additive 2 (ADD 2) is l-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide and ESD Additive 3 (ADD 3) is l-Butyl-3-methylimidazolium tetrafluoroborate.

[0053] Table 11ESD properties are measured by ASTM D-257, at 50% relative humidity (RH). Resistance results are formatted such that 1.0E+10 indicates a result of 1.0 xl O10and so on.

[0054] The results show that the ESD TPU polymers of the present invention have ESD properties superior to ESD TPU using metal and additionally that the combination of imidazolium liquid salt and propylene carbonate exhibit an unexpected synergistic effect on ESD properties.

[0055] Each of the documents referred to above is incorporated herein by reference. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word "about." Unless otherwise indicated, all percent values, ppm values and parts values are on a weight basis. Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention can be used together with ranges or amounts for any of the other elements. As used herein, the expression "consisting essentially of' permits the inclusion of substances that do not materially affect the basic and novel characteristics of the composition under consideration.

Claims

What is claimed is:

1. An electrostatic dissipative thermoplastic polyurethane composition comprising:(a) a thermoplastic polyurethane comprising the reaction product of a polyol intermediate, a diisocyanate, and a chain extender; and(b) an imidazolium liquid salt.

2. The polyurethane composition of claim 1, wherein the polyol intermediate comprises or consists of a polyester polyol intermediate.

3. The composition of claim 2, wherein the polyester polyol intermediate comprises is prepared from the reaction of a dialkylene glycol and a dicarboxylic acid, or an ester or anhydride thereof.

4. The composition of claim 3, wherein the dicarboxylic acid contains from 4 to 15 carbon atoms and the dialkylene glycol contains from 2 to 8 carbon atoms.

5. The composition of claim 3 or 4, wherein the dicarboxylic acid is selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, isophthalic acid, terephthalic acid, cyclohexane dicarboxylic acid, and combinations thereof.

6. The composition of any of claims 2 to 5. wherein the dialkylene glycol is selected from the group consisting of oxydimethanol, diethylene glycol, dipropylene glycol, 3,3-oxydipropan-l-ol, dibutylene glycol, and combinations thereof.

7. The composition of any of claims 2 to 6, further comprising a co-solvent selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl sulfoxide, tetramethylene sulfone, tri- and tetra ethylene glycol dimethyl ether, gamma buty rolactone, N-methyl-2-pyrrolidone, and mixtures thereof.

8. The composition of claim 7, wherein the co-solvent comprises or consists of propylene carbonate.

9. The composition of claim 8, wherein the propylene carbonate is added to the thermoplastic polyurethane in an amount of 5 parts per hundred to 40 parts per hundred or 10 parts per hundred to 30 parts per hundred based on 100 parts of the thermoplastic polyurethane.

10. The composition of claim 1, wherein the polyol intermediate comprises or consists of a polyether polyol intermediate.

11. The composition of any preceding claim, wherein the diisocyanate is selected from the group consisting of 4,4'-methylenebis-(phenyl isocyanate), hexamethylene diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, m-xylylene diisocyanate, phenylene- 1,4-diisocyanate, naphthal ene-l,5-diisocyanate, diphenylmethane-3,3'- dimethoxy-4,4'-diisocyanate, toluene diisocyanate, isophorone diisocyanate, 1,4- cyclohexyl diisocyanate, decane- 1 ,10-diisocyanate, dicyclohexylmethane-4,4'- diisocyanate, and mixtures thereof.

12. The composition of claim 11, wherein the diisocyanate comprises or consists of 4,4'-methylenebis-(phenyl isocyanate).

13. The composition of any preceding claim, wherein the chain extender is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanedioL 1,3-butanediol. 1.5-pentanediol,1.4-cyclohexane-dimethanol, hydroquinone di(hydroxy ethyl) ether, neopentyglycol,1.4-bis(2-hydroxy ethoxy) benzene, and mixtures thereof.

14. The composition of claim 13, wherein the chain extender comprises or consists of 1,4-butanediol.

15. The composition of any preceding claim, wherein the imidazolium liquid salt is selected from the group consisting of l-methyl-3-octylimidazolium chloride; 1-methyl- 3-octylimidazolium bromide; l-methyl-3-octylimidazolium iodide; l-methyl-3- octylimidazolium hexafluorophosphate; l-methyl-3-octylimidazolium tetrafluoroborate; 1 -methyl-3-octylimidazolium hexafluoroantimonate; 1 -methyl-3-octylimidazoliumtrifluoromethanesulfonate; l-methyl-3-octylimidazolium methyl sulfate; l-methyl-3- octylimidazolium ethyl sulfate; l-methyl-3-octylimidazolium acetate; l-methyl-3- octylimidazolium thiocyanate; l-methyl-3-octylimidazolium dicyanamide; l-methyl-3- octylimidazolium bis(trifluoromethylsulfonyl)amide; l-Butyl-3-methylimidazolium tetrafluoroborate; l-octyl-2,3-dimethylimidazolium chloride; l-octyl-2,3- dimethylimidazolium bromide; l-octyl-2,3-dimethylimidazolium iodide; l-octyl-2,3- dimethylimidazolium hexafluorophosphate; l-octyl-2,3-dimethylimidazolium tetrafluoroborate; l-octyl-2,3-dimethylimidazolium hexafluoroantimonate; l-octyl-2,3- dimethylimidazolium trifluoromethanesulfonate; l-octyl-2,3-dimethylimidazolium methyl sulfate; l-octyl-2,3-dimethylimidazolium ethyl sulfate; l-octyl-2,3- dimethylimidazolium acetate; l-octyl-2,3-dimethylimidazolium thiocyanate; 1-octyl- 2,3-dimethylimidazolium di cyanamide; l-octyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)amide; 1 -ethyl-3-methy limidazolium bis(trifluoromethylsulfonyl)imide; 1 -decyl-3-methylimidazolium chloride; l -decyl-3- methylimidazolium bromide; l-decyl-3-methylimidazolium iodide; l-decyl-3- methylimidazolium hexafluorophosphate; l-decyl-3-methylimidazolium tetrafluoroborate; l-decyl-3-methylimidazolium hexafluoroantimonate; l-decyl-3- methylimidazolium trifluoromethanesulfonate; l-decyl-3-methylimidazolium methyl sulfate; l-decyl-3-methylimidazolium ethyl sulfate; l-decyl-3-methylimidazolium acetate; l-decyl-3-methylimidazolium thiocyanate; l-decyl-3-methylimidazolium di cyanamide; l-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide; 1-Ethyl- 3 -methy limidazolium ethyl sulfate; l-dodecyl-3-methylimidazolium chloride; 1- dodecyl-3-methylimidazolium bromide; l-dodecyl-3-methylimidazolium iodide; 1- dodecyl-3-methylimidazolium hexafluorophosphate; 1 -dodecyl-3-methylimidazolium tetrafluoroborate; l-dodecyl-3-methylimidazolium hexafluoroantimonate: l-dodecyl-3- methylimidazolium trifluoromethanesulfonate; l-dodecyl-3-methylimidazolium methyl sulfate; l-dodecyl-3-methylimidazolium ethyl sulfate; l-dodecyl-3-methylimidazolium acetate; l-dodecyl-3-methylimidazolium thiocyanate; l-dodecyl-3-methylimidazolium dicyanamide; l-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide; 1- tetradecyl-3-methylimidazolium chloride; l-tetradecyl-3-methylimidazolium bromide; l-tetradecyl-3-methylimidazolium iodide; l-tetradecyl-3-methylimidazolium hexafluorophosphate; l-tetradecyl-3-methylimidazolium tetrafluoroborate; 1-tetradecyl- 3 -methy limidazolium hexafluoroantimonate; l-tetradecyl-3-methylimidazoliumtrifluoromethanesulfonate; l-tetradecyl-3-methylimidazolium methyl sulfate; 1- tetradecyl-3-m ethylimidazolium ethyl sulfate; l-tetradecyl-3-methylimidazolium acetate; l-tetradecyl-3-methylimidazolium thiocyanate; l-tetradecyl-3- methylimidazolium dicyanamide; l-tetradecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide; l-hexadecyl-3-methylimidazolium chloride; 1- hexadecyl-3-methylimidazolium bromide; l-hexadecyl-3-methylimidazolium iodide; 1- hexadecyl-3-methylimidazolium hexafluorophosphate; l-hexadecyl-3- methylimidazolium tetrafluoroborate; l-hexadecyl-3-methylimidazolium hexafluoroantimonate; l-hexadecyl-3-methylimidazolium trifluoromethanesulfonate; 1- hexadecyl-3-methylimidazolium methyl sulfate; l-hexadecyl-3-methylimidazolium ethyl sulfate; l-hexadecyl-3-methylimidazolium acetate; l-hexadecyl-3- methylimidazolium thiocyanate; l-hexadecyl-3-methylimidazolium dicyanamide; 1- hexadecyl-3-m ethylimidazolium bis(trifluoromethylsulfonyl)amide, and mixtures thereof.

16. The composition of any preceding claim, wherein the imidazolium liquid salt comprises or consists of l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide.

17. The composition of any of claims 1 to 13, wherein the imidazolium liquid salt comprises or consists of l-butyl-3-methylimidazolium tetrafluoroborate.

18. The composition of any preceding claim, wherein the imidazolium liquid salt is added to the thermoplastic polyurethane in an amount of 0.5 parts per hundred to 25 parts per hundred or 1 part per hundred to 20 parts per hundred, or 2 parts per hundred to 16 parts per hundred based on 100 parts of the thermoplastic polyurethane.

19. A shaped polymeric article comprising the electrostatic dissipative thermoplastic polyurethane composition of any of the claims 1 to 18.

20. The polymeric article of claim 19, wherein the article is selected from the group consisting of packaging materials for ESD sensitive semiconductor and electronic parts, durable or consumable parts for clean room equipment and applications, constructionmaterials for clean rooms and datacenters, fibers, laminated sheets, conveyor belts, pharmaceutical products, medical devices, electronic components, separators for use in the construction of lithium-ion batteries, and polymer electrolyte membranes for use in the construction of lithium-polymer batteries and fuel cells.

21. A method of decreasing the surface resistivity of a polymeric article comprising molding an article using the thermoplastic polyurethane composition of any of claims 1 to 17.

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