Patent Application
20130331510
1. Field of the Invention
Embodiments of the invention generally relate to polyurethanes having resistance to hydrocarbons and articles made therefrom.
2. Description of the Related Art
Conventional polyurethanes generally have poor resistance to hydrocarbons at high temperatures, such as, temperatures greater than 100 degrees Celsius. That is, most polyurethanes tend to degrade, swell, or dissolve in the presence of hydrocarbons. This property severely restricts the range of utility for articles comprising such conventional polyurethanes used in the presence of hydrocarbons.
Thus it is desirable to provide polyurethane articles that are resistant to hydrocarbons at high temperatures.
Embodiments of the invention generally relate to polyurethanes having resistance to hydrocarbons and articles made therefrom. In one embodiment, a hydrocarbon resistant polycarbonate elastomer containing article is provided. The hydrocarbon resistant polycarbonate elastomer is prepared from a reaction mixture comprising (a) one or more difunctional polycarbonate polyols comprising repeating units from one or more alkane diols having 2 to 20 carbon atoms with a number average molecular weight between 500 and 3,000, and (b) one or more organic polyisocyanate components, wherein the article is selected from filter caps, conduits, containers, seals, mechanical belts, liners, coatings, rollers and machine parts.
So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
Embodiments of the invention generally relate to polyurethanes having resistance to hydrocarbons and articles made therefrom. More particularly, embodiments of the invention generally relate to articles comprising hydrocarbon resistant polycarbonate elastomers, made from polycarbonate polyols, that are resistant to hydrocarbons at high temperatures. It has been found by the inventors that the hydrocarbon resistant polycarbonate elastomers described herein maintain their dimensional stability when exposed to hydrocarbons, such as diesel fuel, at temperatures up to at least 121 degrees Celsius.
In one embodiment, a hydrocarbon resistant polycarbonate elastomer containing article is prepared from a reaction mixture comprising (a) one or more difunctional polycarbonate polyols comprising repeating units from one or more alkane diols having 2 to 20 carbon atoms, (b) one or more organic polyisocyanate components, and (c) a chain extender comprising diols having 2 to 6 carbon atoms.
Component (a) may comprise one or more difunctional polycarbonate polyols. The one or more difunctional polycarbonate polyols may comprise repeating units from one or more alkane diols having 2 to 20 carbon atoms.
The one or more difunctional polycarbonate polyols may have a number average molecular weight from about 500 to about 5,000, preferably, from about 500 to about 3,000, more preferably, from about 1,800 to about 2,200.
The one or more difunctional polycarbonate polyols may have a hydroxyl number average from about 22 to about 220 mg KOH/g, for example, from about 51 to 61 mg KOH/g.
The one or more difunctional polycarbonate polyols may have a viscosity from about 4,000 to about 15,000 centipose (cp) measured at 60 degrees Celsius by parallel plate rheometry.
The one or more difunctional polycarbonate polyols may be prepared by reacting at least one polyol mixture comprising one or more alkane diols with at least one organic carbonate. The one or more difunctional polycarbonate polyols may be obtained by subjecting at least one polyol mixture and at least one carbonate compound to a polymerization reaction. With respect to the method for performing the polymerization reaction, there is no particular limitation, and the polymerization reaction can be performed by using conventional methods known in the art.
The one or more alkane diols may be selected from the group comprising aliphatic diols having 4 to 50 carbon atoms in the chain (branched or unbranched) which may also be interrupted by additional heteroatoms such as oxygen (O), sulphur (S) or nitrogen (N). Examples of suitable diols are 1,4-butanediol, 1,5-pentanediol, 1,6-hexandiol, 1,7-heptanediol, 1,2-dodecanediol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, bis(2-hydroxyethyl)ether, bis(6-hydroxyhexyl)ether or short-chain C2, C3 or C4 polyether diols having a number average molecular weight of less than 700 g/mol, and also combinations thereof. Exemplary polycarbonate polyols comprising repeating units from one or more alkane diol components are available from Arch Chemicals, Inc., under the trade name Poly-CD™220 carbonate diol and from Bayer MaterialScience, LLC, under the tradename DESMOPHEN® polyols.
The at least one carbonate compound may be selected from alkylene carbonates, diaryl carbonates, dialkyl carbonates, dioxolanones, hexanediol bis-chlorocarbonates, phosgene and urea. The alkylene carbonates may include ethylene carbonate, trimethylene carbonate, 1,2-propylene carbonate, 5-methyl-1,3-dioxane-2-one, 1,2-butylene carbonate, 1,3-butylene carbonate, 1,2-pentylene carbonate, and the like. Moreover, dialkyl carbonates may include dimethyl carbonate, diethyl carbonate, di-n-butyl carbonate, and the like and the diaryl carbonates may include diphenyl carbonate.
The polymerization reaction may be aided by a catalyst. Examples of the catalyst may include metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, cobalt, zinc, aluminum, germanium, tin, lead, antimony, arsenic, and cerium and compounds thereof. As the metallic compounds, oxides, hydroxides, salts, alkoxides, organic compounds, and the like may be mentioned. Of these catalysts, it is preferred to use titanium compounds such as titanium tetrabutoxide, titanium tetra-n-propoxide, titanium tetra-isopropoxide, and titanium 2-ethyl hexanoate, tin compounds such as di-n-butyltin dilaurate, di-n-butyltin oxide, and dibutyltin diacetate, lead compounds such as lead acetate and lead stearate.
Component (a) may comprise at least 40 wt. %, 45 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt. %, 70 wt. %, 75 wt. %, 80 wt. %, or 85 wt. % of the total reaction system. Component (a) may comprise up to 45 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt. %, 70 wt. %, 75 wt. %, 80 wt. %, 85 wt. %, or 90 wt. % of the total reaction system. In certain embodiments, component (a) may comprise from 40 wt. % to about 90 wt. % or from 60 wt. % to 80 wt. % of the total reaction system.
Component (b) may comprise one or more organic polyisocyanate components. The isocyanate functionality is preferably from about 1.9 to 4, and more preferably from 1.9 to 3.5 and especially from 2.0 to 3.3. The one or more organic polyisocyanate components may be selected from the group comprising a polymeric polyisocyanate, aromatic isocyanate, cycloaliphatic isocyanate, or aliphatic isocyanates. Exemplary polyisocyanates include, for example, m-phenylene diisocyanate, 2,4- and/or 2,6-toluene diisocyanate (TDI), the various isomers of diphenylmethanediisocyanate (MDI), and polyisocyanates having more than 2 isocyanate groups, preferably MDI and derivatives of MDI such as biuret-modified “liquid” MDI products and polymeric MDI (PMDI), 1,3 and 1,4-(bis isocyanatomethyl)cyclohexane, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), bis(4-isocyanatocyclohexyl)methane or 4,4′ dimethylene dicyclohexyl diisocyanate (H12MDI), and combinations thereof, as well as mixtures of the 2,4- and 2,6-isomers of TDI, with the former most preferred in the practice of the invention. A 65/35 weight percent mixture of the 2,4 isomer to the 2,6 TDI isomer is typically used, but the 80/20 weight percent mixture of the 2,4 isomer to the 2,6 TDI isomer is also useful in the practice of this invention and is preferred based on availability. Pure 100% 2,4 TDI may also be used. Suitable TDI products are available under the trade name VORANATE™ which is available from The Dow Chemical Company. Preferred isocyanates include methylene diphenyl diisocyanate (MDI) and or its polymeric form (PMDI) for producing the prepolymers described herein. Such polymeric MDI products are available from The Dow Chemical Company under the trade names PAPI® and VORANATE®. Suitable commercially available products of that type include PAPI™ 94 and PAPI™ 27 which are available from The Dow Chemical Company.
Component (b) may comprise at least 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, 40 wt. %, or 45 wt. % of the total reaction system. Component (b) may comprise up to 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, 40 wt. %, 45 wt. %, or 50 wt. % of the total reaction system. In certain embodiments, component (b) may comprise from 15% to 50% by weight or from about 20% to 25% by weight of the total reaction system.
The reaction system may further comprise (c) one or more chain extenders. A chain extender is a material having two isocyanate-reactive groups per molecule. In either case, the equivalent weight per isocyanate-reactive group can range from about 30 to less than 100, and is generally from 30 to 75. The isocyanate-reactive groups are preferably aliphatic alcohol, primary amine or secondary amine groups, with aliphatic alcohol groups being particularly preferred. The chain extender is typically used in quantities such as up to 20 wt. %, up to 15 wt. %, up to 10 wt. %, or up to 5 wt. % of the total reaction system. In certain embodiments, the chain extender is from 0.015 to 10% by weight of the total reaction system.
Representative chain extenders include ethylene glycol, diethylene glycol, 1,3-propane diol, 1,3-butanediol, 1,4-butanediol, dipropylene glycol, 1,2-butylene glycol, 2,3-butylene glycol, 1,6-hexanediol, neopentylglycol, tripropylene glycol, 1,2-ethylhexyldiol, ethylene diamine, 1,4-butylenediamine, 1,6-hexamethylenediamine, 1,5-pentanediol, 1,3-cyclohexandiol, 1,4-cyclohexanediol; 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol, N-methylethanolamine, N-methyliso-propylamine, 4-aminocyclohexanol, 1,2-diaminotheane, 1,3-diaminopropane, hexylmethylene diamine, methylene bis(aminocyclohexane), isophorone diamine, 1,3-bis(aminomethyl), 1,4-bis(aminomethyl) cyclohexane, diethylenetriamine, 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine, and mixtures or blends thereof. Suitable primary diamines include for example dimethylthiotoluenediamine (DMTDA) such as Ethacure 300 from Albermarle Corporation, diethyltoluenediamine (DETDA) such as Ethacure 100 from Albemarle (a mixture of 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine), isophorone diamine (IPDA), and dimethylthiotoluenediamine (DMTDA).
The reaction system may further comprise one or more catalyst components (d). Catalysts are typically used in small amounts, for example, each catalyst being employed from 0.0015 to 5% by weight of the total reaction system. The amount depends on the catalyst or mixture of catalysts and the reactivity of the polyols and isocyanate as well as other factors familiar to those skilled in the art.
Although any suitable catalyst may be used. A wide variety of materials are known to catalyze polyol reactions including amine-based catalysts and tin-based catalysts. Preferred catalysts include tertiary amine catalysts and organotin catalysts. Examples of commercially available tertiary amine catalysts include: trimethylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethylbenzylamine, N,N-dimethylethanolamine, N,N-dimethylaminoethyl, N,N,N′,N′-tetramethyl-1,4-butanediamine, N,N-dimethylpiperazine, 1,4-diazobicyclo-2,2,2-octane, bis(dimethylaminoethyl)ether, triethylenediamine and dimethylalkylamines where the alkyl group contains from 4 to 18 carbon atoms. Mixtures of these tertiary amine catalysts are often used.
Examples of commercially available amine catalysts include NIAX™ A1 and NIAX™ A99 (bis(dimethylaminoethyl)ether in propylene glycol available from Momentive Performance Materials), NIAX™ B9 (N,N-dimethylpiperazine and N-N-dimethylhexadecylamine in a polyalkylene oxide polyol, available from Momentive Performance Materials), DABCO® 8264 (a mixture of bis(dimethylaminoethyl)ether, triethylenediamine and dimethylhydroxyethyl amine in dipropylene glycol, available from Air Products and Chemicals), DABCO 33LV® (triethylene diamine in dipropylene glycol, available from Air Products and Chemicals), DABCO® BL-11 (a 70% bis-dimethylaminoethyl ether solution in dipropylene glycol, available from Air Products and Chemicals, Inc), NIAX™ A-400 (a proprietary tertiary amine/carboxylic salt and bis (2-dimethylaminoethyl)ether in water and a proprietary hydroxyl compound, available from Momentive Performance Materials); NIAX™ A-300 (a proprietary tertiary amine/carboxylic salt and triethylenediamine in water, available from Momentive Performance Materials); POLYCAT® 58 (a proprietary amine catalyst available from Air Products and Chemicals), POLYCAT® 5 (pentamethyl diethylene triamine, available from Air Products and Chemicals) POLYCAT® 8 (N,N-dimethyl cyclohexylamine, available from Air Products and Chemicals) and POLYCAT® 41 (a proprietary amine catalyst available from Air Products and Chemicals).
Examples of organotin catalysts are stannic chloride, stannous chloride, stannous octoate, stannous oleate, dimethyltin dilaurate, dibutyltin dilaurate, other organotin compounds of the formula SnRn(OR)4-n, wherein R is alkyl or aryl and n is 0-2, and the like. Organotin catalysts are generally used in conjunction with one or more tertiary amine catalysts, if used at all. Commercially available organotin catalysts of interest include KOSMOS® 29 catalyst (stannous octoate from Evonik AG), DABCO® T-9 and T-95 catalysts (both stannous octoate compositions available from Air Products and Chemicals).
Additives such as surface active agents, antistatic agents, plasticizers, fillers, flame retardants, pigments, stabilizers such as antioxidants, fungistatic and bacteriostatic substances and the like are optionally used in the reaction system.
It is known that polyether polyols are prone to thermo oxidative degradation at high temperatures. The ether linkage in the presence of oxygen or any other species that can generate a free radical is prone to degradation. Polyesters are generally considered to be stable to hydrocarbons due to the polar ester linkage in the backbone. The polyester linkages are however susceptible to degradation by additives present in the hydrocarbon especially additives which have hydroxyl linkages that can hydrolyze the polyester linkages. Polycarbonate linkages due to the nature of its backbone are more stable than polyesters and perform better at high temperatures. For example, the embodiments of the present invention may not degrade at temperatures at temperatures up to at least 100, 110, 120, 121, 130, 140 or 150 degrees Celsius. Furthermore the embodiments of the invention may exhibit a loss in tensile strength of less than 5, 10, 15, or 20% at these temperatures.
Embodiments of the present invention are suitable for applications in which the hydrocarbon resistant article is exposed to hydrocarbons preferably when used in the form of hydrocarbon resistant conduits, containers, seals, mechanical belts, linings, coatings, rollers, machine parts and the like. Conduits include, for example, pipes, hoses, tubing, gasoline lines, and the like. Containers include, for example, tanks, bottles, flasks, pans, and the like. Mechanical belts include, for example, belts which transfer energy from such energy sources as engines, turbines and the like to other moving apparatus such as fans, other parts of engines and the like, such as automotive belts, truck belts, pump belts and the like as well as belts used for transport such as conveyor belts and the like. Seals include, for example, gaskets; adhesive seals which serve an adhesive function such as hydrocarbon filter seals including fuel filter endcaps; pipe seals; adhesive construction seals and the like; seals which fill gaps such as construction seals, door seals, window seals, shingle seals, and the like; o-rings, and the like; and any polyurethane article which separates other articles and reduces gaps between said articles. Linings include, for example, linings of conduits, containers and the like, such as linings for hoses, pipes, tubing, tanks, bottles, boilers, pans and the like. Coatings include, for example, surface coverings and other coatings on any object, preferably on an object which may contact or be immersed in hydrocarbons, such a conduit, container, roller, machine part and the like. Machine parts include gears, parts for such equipment as oil field equipment, down-hole equipment, engine parts, pump parts (particularly parts for pumps for petroleum and petroleum products) and the like. Rollers include textile rollers, printing rollers, paper mill rollers, metal processing rollers and the like.
Exemplary of a type of seal of particular utility is a filter endcap for a hydrocarbon filter. A filter endcap is an object which is at one or more ends of a hydrocarbon filter. Advantageously, the filter endcap fits between the filter and a housing for the filter. Preferably, a filter endcap also confines flow of hydrocarbon so that it goes through the filter. Hydrocarbons suitably filtered include petroleum products such as fuels, feedstocks and the like, lubricants, such as oils and the like and other hydrocarbon materials such as solvents, cleaning fluids, and the like. One typical configuration of a filter having two endcaps is shown in
As illustrated in
Those skilled in the art will recognize that the hydrocarbon resistant polycarbonate elastomer described herein is particularly suitable for other applications in which the polymer is exposed to hydrocarbons or other materials which similarly swell commonly-encountered polyurethanes.
Objects and advantages of the embodiments described herein are further illustrated by the following examples. The particular materials and amounts thereof, as well as other conditions and details, recited in these examples should not be used to limit embodiments described herein. Unless stated otherwise all percentages, parts and ratios are by weight. Examples of the invention are numbered while comparative samples, which are not examples of the invention, are designated alphabetically.
A description of the raw materials used in the examples is as follows.
Polyol A is a polycarbonate polyol having an average molecular weight of about 2,000, commercially available as POLY-CD™220 carbonate diol from Arch Chemicals, Inc.
Polyol B is a polyester polyol which is a copolymer of glycerine, diethylene glycol and adipic acid with an average functionality of 2.9 and a hydroxyl number of 74 commercially available as STEPANPOL™ AA60 from the Stepan Company.
Polyol C is an ether polyol (Poly(tetra)methylene) glycol (PTMEG) with a number average molecular weight of approximately 2,000 and a hydroxyl number of 60 commercially available as TERATHANE® 2000 from INVISTA™.
The chain extender is 1,4 butane diol commercially available from Sigma-Aldrich Company.
The amine catalyst is a moderately active trimerization catalyst commercially available as POLYCAT® 41 from Air Products and Chemicals.
The isocyanate is polymeric MDI (PMDI) with a functionality of 2.7, commercially available as PAPI™ 27 from The Dow Chemical Company.
Example 1 and comparative samples A and B were filter caps made using the formulations depicted in Table I. For example 1, the amounts and types of polycarbonate polyol, chain extender, and amine catalyst were mixed at 60 degrees Celsius using a FlackTek SpeedMixer™ mixer at 2,350 rpm for twenty seconds. The isocyanate component was added to the mixture and the final mixture was mixed at 2,350 rpm for 20 seconds. The material was poured in a mold and a pleated paper filter was hand potted. The elastomer was cured for 2 minutes before demolding. The molded filter caps were fully cured at room temperature for 24 hours before any further testing. Test plaques were also made with the formulation for tensile testing. The test plaques were made by pouring the formulation between a TEFLON® polymer coated aluminum sheet and compression molded at 50 degrees Celsius at 20,000 psi for 30 minutes. The plaques were cured overnight at 80 degrees Celsius and then used for further testing. Sample A and sample B were each prepared using a similar process.
The tensile properties of the elastomers were obtained on microtensile bar samples that were punched out from the plaques. The bar samples were dogbone shaped with a width of 0.815 inches and length of 0.827 inches. The tensile properties were measured using a Monsanto Tensometer from Alpha technologies. The dogbones were clamped pneumatically and pulled at a strain rate of 5 inches/minute.
The filter caps and dogbones were exposed to No. 2 Diesel fuel at 121 degrees Celsius for 500 hours. The filter caps were removed and visibly inspected for visual degradation. Only the PC polyol based elastomer filter cap (example 1) survived the test. The filter cap based on the polyether formulation (sample B) completely degraded and the filter cap based on the polyester formulation (sample A) showed visible swelling.
The tensile properties of the dogbones before and after ageing were compared. The data is shown in the Table II below. Polyether samples were not available for this study. PTMEG with a number average molecular weight of about 2,000 obtained from INVISTA™ was used as an ether substitute. The samples were marked as pass if the drop in tensile strength after exposure was less than 20%. Table II clearly shows that both the ester and ether did not pass the test. Surprisingly PC performed exceptionally well in this test.
While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US12/24952 | 2/14/2012 | WO | 00 | 8/14/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61442895 | Feb 2011 | US |
