MXPA01007473A - Polyurethane elastomers having improved hydrolysis resistance - Google Patents

Abstract

The disclosed invention relates to a polyurethane elastomer that has improved hydrolysis resistance. The polyurethane elastomer is made by reacting a polyol blend of an aromatic dicarboxylic acid based polyester polyol, analiphatic dicarboxylic acid based polyester polyol, and a blowing agent. The polyol blend is reacted with an isocyanate terminated prepolymer. The aromatic dicarboxylic acid based polyester polyol is the reaction product of an aliphatic alcohol and ortho-phthalic acid. The aliphatic dicarboxylic acid based polyester polyol is the reaction product of adipic acid and glycols.

Description

POLYURETHANE ELASTOMERS PROVIDED OF IMPROVED RESISTANCE TO HYDROLYSIS TECHNICAL FIELD to invention is related to polyester polyurethane elastomers resistant to hydrolysis. More particularly, the invention relates to polyurethane elastomers useful in footwear, especially shoe soles.

BACKGROUND ART Polyester polyurethanes for applications such as footwear have to exhibit excellent flexural and hydrolysis resistance properties. Polyester polyurethane elastomers prepared with ester polyols aromatics, such as polyester o-phthalic acid polyols, have excellent resistance to hydrolysis. However, these elastomers have poor flexural properties. Polyester polyurethanes prepared with polyester aliphatic polyols, such as polyester polyols of adipic acid, have excellent flexibility, but poor resistance to hydrolysis.

Polyurethane polyester elastomers prepared with aliphatic polyester polyols, such as adipic acid-based polyols, have used additives such as caprolactone and carbodii mides polyols, such as Staboxyl I, in an attempt to achieve improved properties. However, the caprolactone polyols are undesirably ca.os. The use of bodily fibers, such as Staboxyl I, does not produce polyester polyurethane elastomers that have a satisfactory resistance to hydrolysis as assessed by the retained tensile strength after running in wet environments. The retained tensile strength of polyester polyurethanes prepared with aliphatic polyester polyols including Staboxyl 1, is only about 60-70% of the original t-action strength after wet aging at 70 ° C and under a relative humidity 100% for seven days. In those applications where polyester polyurethanes are used as shoe soles, the retained tensile strength is conveniently about 75-90% of the tensile strength before aging.

Therefore, there is a need for polyester polyurethane formulations which can be used to produce polyurethanes which exhibit improved resistance to hydrolysis and which avoid the drawbacks of the art.

DESCRIPTION OF THE INVENTION The invention relates to polyurethanes having improvements in hydrolysis resistance and retaining tensile strength. The polyurethanes are prepared by reacting an isocyanate-terminated prepolymer with a polyol component including a mixture of polyester polyol prepared from a polyester polyol based on aliphatic carboxylic acid, preferably polyester polyol based on adipic acid, and a polyester polyol based on aromatic carboxylic acid, preferably polyester polyol based on o-phthalic acid. More specifically, the polyurethane elastomers are prepared by reacting a first component comprising a polyol component having a mixture of a polyester polyol based on aromatic dicarboxylic acid, and a polyester polyol based on aliphatic dicarboxylic acid, a blowing agent and Preferably, a chain extender, with a prepolymer terminated in isocyanate. The polyester polyol based on aromatic dicarboxylic acid is the reaction product of an aliphatic alcohol and ortho-phthalic acid. The aliphatic alcohol is any of ethylene glycol, diethylene glycol, hexanediol and ne op e n t i 1 d i. The aliphatic dicarboxylic acid is any of adipic acid, succinic acid, glutaric acid and suberic acid. The aromatic polyester polyol is present in the polyol mixture in an amount of about 12% by weight to about 26% by weight, preferably from about 15% by weight to about 20% by weight, based on that of the polyol mixture, the rest being constituted by the aliphatic polyester polyol. According to a preferred aspect, the ortho-phthalic acid reacted with the aliphatic alcohol has less than about 10% by weight in total of terephthalic acid and isophthalic acid. The polyester polyol based on aliphatic dicarboxylic acid is the reaction product of adipic acid and glycol or glycols, such as ethylene glycol, diethylene glycol, and 1,4-butadiene, and has an OH value of about 36 to about 56. The blowing agent is any of water, acetone, pentane, hexane, cyclopentane, (1, 1, 1, 2-tetraf-1-oxide), (1,1,1,3,3-pentafluoropropane) , (1, 1, 2, 2, 3, -pentafluoropropane), (1,1,1,2,3,3-hexafluoropropane), and methylene chloride, prefey water in an amount from about 0.02 to about 1.2% by weight based on the total weight of the po 11 or 1 component. In a more preferred aspect, the polyurethane elastomers of the invention are the reaction products of a first component comprising a polyol component that includes a polyol blend. formed of an aliphatic polyester polyol and an aromatic polyester polyol, with a second component which is a The diisocyanate prepolymer has approximately 15% NCO up to about 24% NCO. The aliphatic polyester polyol is the reaction product of ad-ad acid with di e 111 e ng 11 co 1 e 111 e ng 11 co 1. The aromatic polyester polyol is the reaction product of di eti 1 eng 1 i co 1 with ortho-ft to 1 ico acid. The aromatic polyester polyol is present in an amount of about 15% by weight to about 20% by weight of the polyol blend, the remainder being aliphatic polyol polyester. The polyol component also includes 1, 4 -bu t ndi or 1 as a chain extender and water as the blowing agent. Summarizing the invention, this will now be described in greater detail with reference to the following detailed description and non-limiting examples.

MODES FOR CARRYING OUT THE INVENTION Glossary: The following business names and terms have the meanings given below; 1. Dabco S25 of Air Products Co. is trie 111 in di ami na in 1, 4-bu t andi 1. 2. Daltorez P716 of Huntsman Polyurethanes, Inc. is a polyester polyol of e 111 eng 11 co 1 / diethylene glycol / adipic acid having functionality of 2.0 and 0Hv = 56. 3. Daltorez P720 from Huntsman Polyurethanes, Inc. is a polyester polyol prepared from e 111 e ng 11 co 1/1, 4-bu t andi o 1 Adipic acid, Fn = 2, OHv = 55 4. Daltorez P778 of Huntsman Po 1 yurethanes, Inc. is a polyester polyol of eti 1 e ng 1 i co 1 / dieti 1 eng 1 ico 1 / adipic acid which has a functionality of 2.0, a MW of 2500 and an OHv = 45. 5. Daltorez P779 from Huntsman Polyurethanes, Inc. is a polyester polyol of e t i 1 g 1 i c o / d i e t i 1 engl i c o 1 / i c i do adipico that has a functionality of 2.0, an OHv = 37. 6. Daltoped AP 17108 is a blend of polyester polyols from Huntsman Polyurethanes, Inc .; 7. Daltoped HF 54615 is a blend of polyester polyols from Huntsman P or 1 yur e t ha n e s, Inc., Daltoped HF; 54615 includes 86.5% Daltorez P716, 9.6% 1, 4 -butanediol, 2.8% Dabco S-25, 0.47% Niax DEOA-LF, 0.3% DC-193 and 0.33% water. 8. DC-193 is a silicone surfactant from Air Products Co. 9. Formrez 8009-146 by Witco Co. is a polyester polyol of isophthalic acid having a functionality of 2.0 and an OHv = 146. 10. Niax DEOA-LF is diethanolamine from Union Carbide Co. 11. Staboxyl I from Rhien Chemie is bis-2, 2 ', 6, 6' -tetraisopropyl-diphenylcarbodiimide. 12. Rubinate 1680 is a Huntsman urethamimine-modified MDI Pol yu retha ne s, Inc. 13. Rubinate 9044 is a diisocyanate diisocyanate from Huntsman Pol yuret ha ne s, Inc. 14. Rubinol F 481 is a polyether polyol prepared from EO / PO diol, finalized with EO, OHv = 30 from Huntsman Polyurethanes, Inc. 15. Stepanpol PS 1752 from Stepan Co. is a polyester polyol based on diethyl 1 ng 1 ico 1 - a nh i dr i do orthophthalic that has a MW of 640, a functionality of 2.0 and a hydroxyl index of 160-180 mg KOH / gm. 16. Stepanpol PS 3152 of Stepan Co. is a polyester polyol based on diethylene glycol-phthalic anhydride polyester polyol based on diethylene glycol phthalic anhydride having a functionality of 2.0, a P of 356, and a Hydroxyl Index of 300-330 mg KOH / gm. 17. Stepanpol PD-110LV from Stepan Co. is a polyester polyol based on diethylene glycol / ortho-phthalate having a functionality of 2.0, a MW of 975, and a Hydroxyl Index of 110-120 mg KOH / gm. 18. Stepanpol PH-56 from Stepan Co. is a polyester polyol of ortho-phthalate-l, 6-hexanediol having a functionality of 2.0, and a hydroxyl number of 53-59 mg KOH / gm. 19. Stepanpol PN-110 from Stepan Co. is a polyester polyol of ortho f t a 1 a t o - ne ope n t i 1 g 1 i c o 1 that has a functionality of 2.0, and a hydroxyl number of 110-120 mg KOH / gm. 20. Stepanpol PS 20-200A by Stepan Co. is a polymer polyol of orthophthalate-diethylene glycol having a hydroxyl number of 190-200 and a functionality of 2.0. 21. Stepanpol PS 2002 by Stepan Co. is a diethylene glycol orthophthalate polyester polyol that has a hydroxyl number of 200, and a functionality of 2.0. 22. Suprasec 2000 from Huntsman Po 1 yu r e t e s is a diphenylmethane diisocyanate prepolymer which is the reaction product of a polyester polyol and diphenylmethane diisocyanate, and having 17% NCO. The polyester polyol is the reaction product of a mixture of ethylene glycol / diethylene glycol with adipic acid. 23. Suprasec 2433 of Huntsman P or 1 and u r e t h a ne s is a diphenylmethane diisocyanate prepolymer which is the reaction product of polyester polyol and diphenylmethane diisocyanate, and having 18.7 to 19.3% NCO. The polyester polyol is EO / PO diol finalized in EO. 24. Suprasec -2544 by Huntsman Polyurethanes is a diphenylmethane diisocyanate prepolymer having 19% NCO. It is the reaction product of Rubinate 9044, Rubinol F 481, Daltorez P720, and Rubinate 1680. 25. Molecular weight, unless otherwise indicated, is the average index. In the present invention, a polyol component formed from a mixture of an aromatic polyester polyol and an aliphatic polyester polyol is reacted with an isocyanate prepolymer to produce a polyurethane having greatly improved hydrolysis resistance. The polyol component includes catalysts, blowing agents and optionally chain extenders and additives, all of which are suitable. Aromatic polyester polyols for use in the polyol component can be prepared by polycondensation of aromatic dicarboxylic acids or dicarboxylic acid derivatives, for example, aromatic dicarboxylic acid anhydrides or aromatic diesters, with aliphatic diols and / or triols. Suitable aromatic dicarboxylic acids are terephthalic acid and ortho-phthalic acid, preferably orthophthalic acid. More preferably, the aromatic dicarboxylic acid is ortho-phthalic acid having less than about 10% terephthalic acid and isophthalic acid. Other suitable aromatic acids that can be used to prepare the prepolymer include mixtures of ortho-phthalic acid with fatty acid dimers, such as C18 fatty acid dimers. Aliphatic diols and triols which can be used to prepare the aromatic polyester polyols are, for example: ethanediol, diethylene glycol, 1,4-bu ta ndi or 1, ne op ti ti 1 g 1 ico 1, 1,6-hexanediol, 1 , 3- and 1, 2 -pr op to ndi or 1, di pr op i 1 e ng 1 ico 1, triethylene glycol, tetraethyl. iicol, glycerin, trimethylolpropane and t r i e t i 1 or 1 p r ope, preferably diethylene glycol. Aromatic polyester polyols are prepared from any of the terephthalic acids, isophthalic acid, ortho-phthalic acid or mixtures thereof and ethylene glycol and / or diethylene glycol. More preferably, aromatic polyester polyols are prepared from ortho-phthalic acid and ethylene glycol and / or diethylene glycol. Preferably, the aromatic polyester polyol is formed from ortho-phthalic acid having a molecular weight of from about 256 to about 3000, preferably from about 344 to about 1500, more preferably about 640. The aromatic polyester polyols that can be to be used have molecular weights of from about 256 to about 3000, preferably from about 344 to about 1500, and functionalities from 2 to 3, preferably 2. These aromatic polyols have acid numbers less than 3, more preferably from about 0.2 to 0.8, and hydroxyl numbers from about 37 to about 438, preferably from about 75 to about 315. Examples of commercially available aromatic polyester polyols for use in the invention include Stepanpol PS-3152, Stepanpol PS 20-200A, Stepanpol PS 2002, Stepanpol PS 1752, Stepanpol PD-110 LV, Stepa npol PH-56, and Stepanpol PN-110, preferably Stepanpol PS 1752.

The aliphatic polyester polyols that can be used can be used. prepare, for example, from organic dicarboxylic acids having from 2 to 12 carbon atoms, preferably aliphatic dicarboxylic acids having from 4 to 6 carbon atoms, more preferably 6 carbon atoms, and polyfunctional alcohols, preferably diols having from 2 to 12 carbon atoms, more preferably from 2 to 4 carbon atoms. Typical dicarboxylic acids are: succinic acid, glutaric acid, adipic acid, and suberic acid, preferably adipic acid. The dicarboxylic acids can be used individually or in a mixture with one another, preferably the adipic acid is used alone. Instead of the free dicarboxylic acids, the corresponding dicarboxylic acid derivatives can be used, for example, esters of dicarboxylic acids of alcohols having from 1 to 4 carbon atoms, or dicarboxylic anhydrides. Examples of di- and polyfunctional alcohols that can be used, in particular, diols, are: ethanediol, diethylene glycol, 1,2- and 1,3-pr op andi or 1, dipr opi 1 eng 1 i co 1, 1, 4 -bu t andi o 1, 1, 5 - pent and io 1, 1, 6 -hexandi or 1, 1, 10 - of candium 1, preferably die 111 e ng 11 co 1. Examples of triols are glycerin and trimethylcyclopropane, preferably ethylene glycol ydie 111 e ng 11 co 1. The polyester polyols preferably have a functionality of 2 to 3 and a molecular weight of 1000 to 3000, more preferably of 1800 to 2500, and a functionality of 2.0 to 2.2. Polymeric aliphatic polyester emulsions available for use in the invention include Daltorez P716, Daltorez P778, Daltorez P779, and Daltorez P778, preferably Daltorez P778. The aromatic polyester polyol and the aliphatic polyester polyol can be mixed in weight ratios of aromatic polyester polyol: polyester polyol aliphatic from about 13:87 to 28.7: 71.3, preferably from about 16.6: 83.4 to about 22:78. Preferably, the aromatic polyester polyol is Stepanpol PS 1752 and the aliphatic polyester polyol is Daltorez P778, and the weight ratio of Stepanpol PS 1752 to Daltorez P778 is from about 13:87 to about 28.7: 71.2, preferably about 16.6: 83.4 to about 22:78. Catalysts suitable for use in the polyol component include tertiary amine-based catalysts and organometallic catalysts. Some examples of organometallic catalysts include organometallic compounds of lead, iron, bismuth and mercury. Examples of amine catalysts include t r i a 1 qu i 1 ami n a s and amines he t e r c o c i i ca s. Suitable compounds include, for example, trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylcyclohexylamine, dibutylcyclohexylamine, dimethe 1-ethane-1-amino, triethanolamine, diethylethanolamine, ethyldiethanolamine, dimethyl isopropanolamine, triisopropanolamine, triethylenediamine, tetramethyl-1,3-butanediamine, N, N , N ', N'-tetramethylethylenediamine, N, N, N', N ', -tetramethylhexanediamine-1,6, N, N, N', N ', N "-pentamethyldiethylenetriamine, bis (2-dimethylaminoethoxy) -methane, N, N, N '-trimethyl-N' - (2 -hydroxyethylethyldiamine, N, N-dimethyl-N ', N' - (2-hydroxyethyl) -ethylenediamine, tetramethylguanidine, N -methylpiperidine, N-ethylpiperidine, N -methylmorpholine, N-ethylmorpholine, 1,4-dimethylpiperidine, 1,2,4-trimethyl piperidine, - (2-dimethylaminoethyl) -morpholine Examples of commercially available catalysts for use in the polyol component include Dabco S25 and Niax DEOA- LF Ammonium catalysts are usually used in amounts ranging from 0.1 to 1.5% by weight, preferably from approximately 0.3 to 1.1% by weight, based on the total weight of the polyol component. At least one blowing agent is included in the polyol component. Suitable blowing agents include, for example, water and physical blowing agents. Useful physical blowing agents include ba or boiling point alkanes, partially or fully fluorinated hydrocarbons, etc. Suitable alkanes or boiling point include compounds such as, for example, acetone, pentane, hexane, c i c 1 op e n t a no, etc. Some examples of partially or fully fluorinated hydrocarbons include compounds such as HFC-134a (1, 1, 1, 2-tetrafluoroethane), HFC-245fa (1,1,1,3,3-pentafluorpropane), HFC-245ca (1 , 1,2,2,3-pentafluorpropane), HFC-236ca (1,1,1,2,3,3-he xa f 1 uo r op r opane). Methylene chloride is also a blowing agent suitable for the presently claimed invention. Likewise, mixtures of these various blowing agents can be used. It is preferable that the blowing agent comprises water.

When water is used as the sole blowing agent, it is usually employed in amounts between about 0.02 and 1.2% by weight and preferably between 0.05 and 0.7% by weight, based on the total weight of the polyol component of the polyol. the formulation. In the present invention, the blowing agents are added in the amount necessary to produce a foam of the desired density to be used, for example, as shoe soles. In shoe soles, the density of the molded foam is usually from about 0.2 to 1.2 g / cc, preferably from about 0.4 to 1.1 g / cc. Normally, densities can be as high as about 1 g / cc to 1.1 g / cc when used in double-density shoe soles where one. The outer sole of greater density is attached to a midsole of lower density. More preferably and optionally, chain extenders are included in the polyol mixture. Chain extenders include glycerols and diols having at least two hydroxyl groups and a MW of less than about 300. Examples of useful chain extenders are glycerols and diols having primary hydroxyl groups, glycerols and diols having secondary hydroxyl groups, and glycerols and diols having both primary and secondary hydroxyl groups. Preferably, the chain extenders are diols having primary hydroxyl groups and a molecular weight greater than about 62. Examples of these chain extenders include, but are not limited to, ethylene glycol, diethylene glycol, 1,4-butanediol, 2, 3 -bu t andi ol and 1, 2-pr ope ndi o 1, preferably 1, 4 -bu ta ndi o 1 and ethylene glycol. Various additives can be included in the polyol component. Examples of suitable additives include active surface additives such as emulsifiers and foam stabilizers. Examples which may be mentioned are N-stearic acid 1 - ', N'-bis-hydroxyethylurea, oleyl polyoxyethyleneamide, stearyl diethanolamide, stearic acid 1-diethylene, polyoxyethylene glycol monooleate, pentaerythritol ester 1 / acid It also contains oleic acid, a hydroxyethyl imidazole derivative of oleic acid, N-stearyl pr opylamine, and the sodium salts of castor oil or fatty acid sulfonates. As active surface additives, alkali metal or ammonium salts of sulfonic acid such as dodecyl acid can be used, as well as fatty acid salts. Other additives that can be used in the molding compositions of the present invention include the known internal mold release agents, pigments, cell regulators, flame retardant agents, plasticizers, colorants, fillers and reinforcing agents such as glass in powder form, and unsightly agents. Examples of fillers include calcium carbonate, talc, magnesium hydroxide, mica, clay, barium sulfate, natural silica, synthetic silica (white carbon), titanium oxide and carbon black. Among them, barium sulfate and synthetic silica are preferred. Foam stabilizers which optionally can also be employed include water-soluble polyester siloxanes. The structure of these compounds is generally that of a copolymer of ethylene oxide and propylene oxide attached to a po dime 111 s 11 oxane. A preferred foam stabilizer is the silicone surfactant supplied by Air Products Co. under the tradename DC-193. Isocyanate prepolymers are used in the preparation of the foams of the present invention. The prepolymer preferably has an NCO value of about 15 to about 26%, more preferably about 16-21%, and a functionality of 2.0 to 2.5, more preferably 2.0 to 2.1. The isocyanate-terminated prepolymers can be formed by various methods known in the art. Suitable isocyanate-terminated prepolymers can be prepared by reacting an excess of polymeric isocyanate or diisocyanate with polyols, including aminated polyols, amine-modified polyols or enamines, eg 11 or 1 s, polyester polyols or polyamines. The prepolymer can then be mixed with one or more additives such as MDI derivatives, p 1 a s 11 f i c an t e s and stabilizers. To prepare the prepolymer one or more chain extenders can also be used instead of the polyol (or instead of a part of the polyols). Examples of prepolymers suitable for use in the invention include prepolymers formed from Stepanpol PS 1752 and MDI, aromatic polyols such as Bisphenol A, and aliphatic polyols. Examples of available novel prepolymers that can be used in the invention include Suprasec 2000, Suprasec 2544, Suprasec 2980 and Suprasec 2433.

Preparation of polyester polyurethanes Side B (polyol component) and side A (isocyanate prepolymer) can be reacted at rates of about 92 to 106, preferably about 96 to about 100, more preferably about 98, to produce polyester polyurethanes. During the preparation of the polyester polyurethanes, additives are incorporated, if used, into the component of the "B" side, although they can be added to the component of the "A" side as long as they are not reactive with the isocyanate. The components included in the "B" side, including additives, can be mixed or stirred in a supply container or tank at a temperature of from about 20 to about 75 ° C, preferably from about 20 ° C to about 50 ° C. The stirring can be carried out with conventional propellant type agitators at about 50 to about 200 RPM.

Specific examples of B-side and isocyanate formulations are shown in Table I. In Table 1, Example I is a conventional formulation for shoe soles wherein the only polyol is the aliphatic polyester polyol available in Daltorez P778. Example 2 is similar to Example 1 but includes 1% of Staboxyl I, c a r bodi id. Examples 3 and 4 employ o-phthalic acid ester polyols, such as Stepanpol PS 1752 with aliphatic ester polyols such as Daltorez P778 and Daltorez P 716. All the amounts indicated in Table 1 are in percent by weight based on the total weight of the product. B side.

Preparation of molded polyurethane polyester In the preparation of molded polyurethane polyester, the "A" side and "B" side components are placed in separate containers equipped with agitators. The temperature of each component can vary from room temperature to approximately 70 ° C. Molded shoe soles are prepared by supplying each of the components of the "A" and "B" sides, by means of metering pumps, to a mixing head where they are mixed at pressures up to about 30 bar, preferably up to about 20 bars During mixing, the temperature of side B is about 40 ° C and the temperature of side A is about 35 ° C. The resulting mixture of components A and B; It is poured or injected in a mo 1 of. Once the mold is filled, the mold is closed and the mixture cured at a temperature of about 30 ° C to about 60 ° C for a time of about 1 to 30 minutes, preferably about 45 ° C to about 55 ° C approximately and for approximately 2 to 10 minutes.

Molded shoe soles can also be formed as soles for double density footwear. The soles for double density footwear are prepared by a two-stage injection method. In the first stage, the mixture of A-side and B-side components is injected into a dual-density molding cavity, such as the Caroline Boots double density sole mold from Amtrial, Inc. The double-density mold cavity it includes a closed mold cavity which is surrounded by an upper mold, a lower mold and side rings to produce a thin outer sole elastomer. When the elastomer of the outer sole is cured in the mold, the upper mold is removed to provide a space that allows the production of an intermediate sole. The upper footwear is present as a part of an outer mold. In the second step, another mixture of side-A and side-B components is injected into the mold between the upper shoe and the outsole, to produce an intermediate sole foam between the outer sole and shoe s. -order. The outer sole is then glued with the upper footwear.

The polyester polyurethanes produced in the manner described above were evaluated for flexural strength, tensile strength and tensile strength after aging in a wet environment. The flexural strength of polyester polyurethanes was evaluated according to the Ross bending test described in AS TM-D-1052-85. In the Ross flexure test, sheets of polyester polyurethane of the following measures 15.24 cm x 2.54 cm x 0.63 cm were used. A 2 mm slit was formed in the sheets and then repeatedly bent over a 25 mm diameter mandrel. The sheets that supported cycles of 50 kilos (KCS) of flexion at room temperature and cycles of 40 kilos at -15 ° C are considered acceptable. The tensile strength after aging in wet environments of polyester polyurethanes was evaluated in accordance with ASTM D 412-92. In the ASTM D 412-92 test, sheets of polyester polyurethanes of 15.24 cm x 2.54 cm x 0.32 cm were used. The tensile strength retention is calculated from the tensile strength before and after wet aging at 70 ° C, under a relative humidity of 100%, for seven days. The results are given in Table 2. The flexural strength of double-density shoe soles using polyester polyurethanes was evaluated according to the Bata Belt Test described in the SATRA PM 133 test method published by the SATRA Technology Center , UK. Shoe soles that withstand cycles of 35-50 kg of flexion are considered as low risk for fatigue cracking and therefore are acceptable. The results are shown in Table 2.

As shown in Table 2, samples 7-9 using the compositions of Example 3 retain a percentage as high as 93% of their original tensile strength. This exceeds the highest level of tensile strength retention that can be achieved with the prior art compositions utilizing aliphatic polyester polyols including the carbodiZed Staboxyl I. To further illustrate the invention, ester polyols of US Pat. -phthalate modified for use with polyester polyols based on adipic acid at various rates. Prepolymers formed from the modified polyols were also evaluated. These modified polyols are referred to as P 1752M and P 3152M. The prepolymer is referred to as S 2000M. The compositions evaluated are shown in Table 3. P 1752M is prepared using Stepanpol PS 1752 and adipic acid in a weight ratio of Stepanpol PS 1752 / adipic acid of 44/56. P 1752M is prepared by charging Stepanpol PS 1752 in a reactor and then heating it until the polyol temperature reaches 115 ° C. Adipic acid is added and the reactor temperature is raised to 150 ° C with stirring. A partial vacuum of 508 mm Hg is maintained and the temperature is maintained below 230 ° C, preferably from about 200 ° C to about 220 ° C. When the acid number of the reaction mixture is less than 2, as determined by titration, a vacuum of less than 50.8 mm Hg is applied until the reaction mixture reaches an OHv of 72-78. The P 3152M, which has a MW of 1450, is prepared according to the following procedure in two stages. In step 1, Stepanpol SP 3152 is reacted with adipic acid in a weight ratio of Stepanpol SP 3152: adipic acid of 1: 2, to achieve an intermediate compound terminated in acid. Stepanpol SP 3152 is added to the reactor and heated to 115 ° C. Adipic acid is added to the reactor and the temperature is raised to 150 ° C with stirring and under a partial vacuum of 508 mm Hg. The reaction is continued for two hours while maintaining the temperature below 230 ° C, preferably from about 200 ° C to about 220 ° C. The resulting acid-terminated intermediate is then cooled to 115 ° C and used in step 2.

In step 2, the intermediate compound terminated in acid is reacted with ethylene glycol in a molar ratio of intermediate compound terminated at c i do / e 111 e ng 11 c or 1 of 2: 3. Ethylene glycol is charged into the reactor containing the intermediate compound terminated in acid at a temperature of 115 ° C, with stirring. The temperature rises to 150 ° C under a partial vacuum of 508 mm Hg. The reaction is continued for two hours and the temperature is maintained below 230 ° C, preferably from about 200 ° C to about 220 ° C. When the acid number of the reaction mixture is less than 2, as determined by titration, a vacuum of less than 50.8 mm Hg is applied until an OHv of 72-78 is achieved.

Suprasec 2000 Prepared polyester polyurethanes exhibit excellent resistance to hydrolysis as well as excellent mechanical characteristics, including abrasion resistance, durability, stability and flexibility, thus being ideal for use in shoe soles.

Claims (17)

1. CLAIMS 1. Polyurethane elastomer having improved resistance to hydrolysis and comprising the reaction product of a first component including a polyol mixture having a polyester polyol based on aliphatic dicarboxylic acid, an acid-based polyester polyol aromatic dicarboxylic, chain extender and a blowing agent, and a second component having an isocyanate-terminated prepolymer, wherein, in the first component, the polyester polyol based on aromatic dicarboxylic acid is the reaction product of an aliphatic alcohol and ortho-phthalic acid, and wherein the aromatic dicarboxylic acid-based polyester polyol is present in the polyol mixture in an amount of about 12% by weight to about 27% by weight based on the weight of the polyol blend
2. 2. The polyurethane elastomer of claim 1, wherein the aliphatic alcohol is selected from the group consisting of ethylene glycol, diethylene glycol, hexanediol, 1,4-butanediol, n e or p e n t i 1 d i o 1 and mixtures thereof.
3. 3. The polyurethane elastomer of claim 1, wherein the aliphatic dicarboxylic acid is selected from the group consisting of adipic acid, succinic acid, glutaric acid and suberic acid.
4. 4. The polyurethane elastomer of claim 2, wherein the amount of polyester polyol of aromatic dicarboxylic acid is from about 14% by weight to about 27% by weight of the polyol mixture.
5. 5. The polyurethane elastomer of claim 1, wherein the isocyanate-terminated prepolymer contains about 17% NCO and is the reaction product of non-diisocyanate diphenyl ether and a polyester polyol which is the reaction product of a mixture of ethylene glycol / diethylene glycol with adipic acid.
6. 6. The polyurethane elastomer of claim 5, wherein the polyester polyol based on aliphatic dicarboxylic acid is the reaction product of adipic acid and a mixture comprising diethylene glycol and ethylene glycol.
7. 7. The polyurethane elastomer of claim 6, wherein the polyester polyol based on aliphatic dicarboxylic acid has an OH value of about 36 to about 56.
8. 8. The polyurethane elastomer of claim 1, wherein the blowing agent is selected from the group consisting of water, acetone, pentane, hexane, cyclo 1 open tan, (1,1,1,2-tetrafluoroethane), (1.1 , 1,3,3-pentafluoropropane), (1,1,2,2,3-pentafluorpropane), (1,1,1,2,3,3-hexaf 1o or r op r op an) and methylene chloride .
9. 9. The polyurethane elastomer of claim 8, wherein the blowing agent is water.
10. 10. The polyurethane elastomer of claim 8, wherein the blowing agent is water in an amount of about 0.02% to 1.2% by weight based on the total weight of the polyol component.
11. 11. The polyurethane elastomer of claim 1, wherein the isocyanate terminated prepolymer contains from about 18.7% NCO to about 19.3% NCO and is the reaction product of diphenylmethane diisocyanate and a polyester polyol which is an EO / PO diol finalized in EO
12. 12. The polyurethane elastomer of claim 1, wherein the isocyanate-terminated prepolymer has an NCO content of about 19% and is the reaction product of diphenylmethane diisocyanate, diphenylmethane diisocyanate modified with uretonimine, polyester polyol and polyether polyol.
13. 13. The polyurethane elastomer of claim 12, wherein the polyester polyol is the reaction product of ethylene glycol, 1,4-butanediol and adipic acid, and the polyester polyol is a diol terminated in ethylene oxide.
14. 14. The polyurethane elastomer of claim 1, wherein the chain extender is selected from the group consisting of ethylene glycol, diethylene glycol and 1,4-bu t a ndi or 1.
15. 15. Polyurethane elastomer having improved resistance to hydrolysis, wherein it comprises the reaction product of a first component that includes a polyol mixture having a polyester polyol based on ortho-phthalic acid formed as the reaction product of diethylene glycol with Orthophthalic acid with orthophthalic acid being substantially free of terephthalic and isophthalic acids, the ortho-phthalic acid being present in an amount of about 15% by weight to about 20% by weight with respect to the polyol mixture, a polyester polyol based on adipic acid formed as the reaction product of adipic acid and a mixture of e 111 e ng 11 co 1 / di e 111 e nglico 1, and water as a blowing agent, and a second component which is a diphenylmethane diisocyanate prepolymer containing from about 15% to about 24% NCO.
16. L6. The polyurethane elastomer of claim 15, wherein the aromatic polyester polyol is the reaction product of a polyester polyol based on diethylene glycol-ortho-phthalic anhydride and adipic acid in a weight ratio of polyester polyol to adipic acid of 44/56. .
17. 17. The polyurethane elastomer of claim 15, wherein the aromatic polyester polyol is the reaction product of an acid-terminated intermediate compound with ethylene glycol in a molar ratio of intermediate compound terminated by acid / ethylene glycol. 2: 3, and because the intermediate compound terminated in acid is the reaction product of a polyester polyol based on di eti 1 e ng 1 i co 1 / anphidic acid and adipic acid, in a weight ratio of polyester polyol based on diethyl 1 e ng 1 ico 1 / phthalic anhydride to adipic acid of 1: 2.