MXPA98009157A - Rigid thermoplastic polyurethane comprising butanodiolunities and a glycol polyethylene - Google Patents

Abstract

The present invention relates to a rigid thermoplastic polyurethane (RTPU) comprising butanediol units (BDO) and a polyethylene glycol (PG) of the HO- (CH2O) nH type, wherein n is an integer from 2 to 6. The RTPU of the present invention addresses a problem in the art by providing a potentially lower cost alternative for an RTPU prepared from hexanediol, and further providing an RTPU which can be adapted to a desired toughness, Tg, yield strength and transparency. The RTPUs that are prepared from certain molar ratios of BDO and PEG exhibit a surprisingly high degree of tenacity manifested through an elongation at tensile rupture, increases

Description

RIGID OPLSTATE POLYURETHANE COMPRISING UNITS OF BUTANOPIOL AND A POLYETHYLENE GLYCOL DESCRIPTION OF THE INVENTION Rigid thermoplastic polyurethanes (RTPUs) are single phase or two phase polymers which can be prepared through the reaction of approximately stoichiometric amounts of: a) a diisocyanate with b) a diol, which comprises a low weight diol molecular (molecular weight of not more than 300) and a high molecular weight diol, generally on a scale of 500 to 8000). These RTPUs have a glass transition temperature (Tg) of not less than 50 ° C and typically have a hard segment content of not less than 75%. The description and preparation of the RTPUs is described, for example, by Goldwasser et al. , in the patent of E. U.A. 4, 376,834. In some cases, it is desirable to prepare optically transparent RTPUs, i.e., amorphous RTPUs having an individual Tg. These optically transparent RTPUs, which are usually prepared using hexanediol as the low molecular weight diol, are useful in a variety of applications that require toughness, chemical resistance and dimensional stability. Examples of useful products made from optically clear RTPU s include handles for toothbrushes, water or fuel filtration components, windows and connectors for intravenous delivery systems. Although hexanediol is an effective monomer for the preparation of optically transparent RTPUs, it may be desirable to use alternative monomers, which allow for greater flexibility in customary physical properties of the RTPU such as Tg and elastic limit. In addition, it could be desirable if said alternative monomers provided lower cost RTPUs. The present invention is a rigid thermoplastic polyurethane comprising: a) units of a diisocyanate; b) units of a polyethylene glycol having the structure HO- (C H2CH2O) n-H, wherein n is an integer from 2 to 6; c) butanediol units; and d) not more than 25% by weight of units of a high molecular weight diol based on the total weight of the rigid thermoplastic polyurethane, the rigid thermoplastic polyurethane further characterized as having a Tg of at least 50 ° C, provided that when polyethylene glycol is triethyl glycol, at least one of the following limitations apply: a) the mol to mol ratio of the triethylene glycol units to the butanediol units is from 25: 75 to 90: 1 0; b) the rigid thermoplastic polyurethane comprises no more than 0.9% by weight of high molecular weight diol units; or c) the thermoplastic polyurethane is optically stable. In one aspect, the present invention is a rigid urethane or thermoplastic polyol comprising: a) diisocyanate units. b) triethylene glycol units; c) butanediol units; and d) not more than 1.9% by weight of units of a high molecular weight diol r based on the total weight of the rigid thermoplastic polyurethane, the rigid thermoplastic polyurethane further characterized by having a Tg of at least 50 ° C. In another aspect, the present invention is a rigid thermoplastic polyurethane comprising: a) units of a diisocyanate; b) diethylene glycol units; c) butanediol units; and d) not more than 25% by weight of units of a high molecular weight diol based on the total weight of rigid thermoplastic polyurethane, the rigid thermoplastic polyurethane further characterized as having a Tg of at least 50 ° C. The present invention addresses a problem in the art by providing a potentially low cost alternative to an RTPU prepared from hexanediol, and further providing an RTPU that can be adapted to a desired toughness, Tg, elasticity, and transparency. It has been found that said RTP U can be prepared from the reaction of a diisocyanate with BDO and polyethylene glycol (PEG). The RTPU which is prepared from certain molar ratios of BDO and the PEG exhibits a surprisingly high degree of tenacity manifested by elongation to the ground by increased traction. FIG. 1 is a graph of the tensile elongation percentage of the RTP U versus the mole fraction of TEG to B OD used to prepare the RTPU. Figure 2 is a graph of the elongation to stretch by tensile of an RTP U against the mole fraction of DEG to BDO used to prepare the RTPU. Figure 3 is a graph of the tensile elongation percentage of an RTPU versus the mole fraction of E-300 to BDO used to prepare the RTPU.

Definition of Terms The term "mixture of a PEG and BDO" refers to a combination of polyethylene glycol and butanediol, which, when reacted with a diisocyanate, form a polymer comprising a base chain structure having PEG units and BDO. The term "units of" is used herein to refer to a repeating sequence of a molecular fragment r within the RTPU. For example, the term "butanediol units" is used herein to refer to the following repeat sequence within the RTPU: -O- (CH2) 4-O- Similarly, the term "triethylene glycol units" is used in the present to refer to the following repeat sequence within the RTPU: -O- (C H2CH 2 O) 3- The term "units of a diisocyanate" is used herein to refer to the following repeat sequence within the RTPU: O = C-NH-R-NH-C = O where R is an aromatic, aliphatic or cycloaliphatic group. The term "butanedioT" is used herein to refer to 1,4-butanediol The RTPU of the present invention can be prepared through the reaction of a diisocyanate with a PEG and a BDO Preferably, the PEG is TEG or DEG , most preferably TEG When the PEG is TEG, the preferred mol to mol ratio of TEG units to BDO units in the RTPU is 25:75, preferably 35:65, preferably 45:55 to 90:10 preferably at 75:25, and most preferably at 60:40 When PEG is DEG, the preferred mol to mol ratio is 25:75, preferably 40:60, and most preferably 50:50, preferably at 65:35, and most preferably at 60:40 When PEG is hexaethylene glycol (E-300), the preferred mol to mole ratio of E-300 to BDO is from 30:70 to 60:40. high that 60:40, E-300 to BDO, the Tg of the RTPU falls to less than 50 ° C. Preferred diisocyanates include aromatic, aliphatic and cycloaliphatic diisocyanates, and combinations s of them. Representative examples of these preferred diisocyanates can be found in the patents of E.U.A. 4,385,133; 4,522,975; and 5,167,899. Preferred diisocyanates include 4,4'-diisocyanatophenylmethane, p-phenylene diisocyanate, 1,3-bis (isocyanatomethyl) -cyclohexane, 1,4-diisocyanatocyclihexane, hexamethyle diisocyanate, 1,5-naphthalene diisocyanate, diisocyanate 3, 3'-dimethyl-4,4'-biphenyl, 4,4'-diisocyanatodicyclohexyl methane, and 2,4-toluene diisocyanate. Most preferred are 4,4'-diisocyanato-dicyclohexylmethane and 4,4'-diisocyanatodiphenylmethane. The most preferred is 4,4'-diisocyanatodiphenylmethane. The RTPU may optionally contain no more than 25% by weight of units of a high molecular weight diol based on the total weight of the rigid thermoplastic polyurethane. The term "high molecular weight diol" is used herein to refer to a diol having a molecular weight of not less than 500 amu. The preferred high molecular weight diols are polyester and polyether glycols. Preferably, the molecular weight of the high molecular weight diol is not less than 600 and not more than 8000 amu. The high molecular weight diol units constitute a sufficiently low fraction of the RTP U, so that the Tg of the RTPU is at least 50 ° C. Preferably, the high molecular weight diol units constitute not more than 10, preferably not more than 5, preferably not more than 1.9, still preferably not more than 1.5, and preferably not more than 1% by weight. weight of the RTPU, at 0% by weight of the RTP U. An optically clear RTP U can be prepared by excluding high molecular weight diols from the RTPU, or by including a high molecular weight diol or a combination of high molecular weight diols that form an individual phase with the BDO and PEG units. in the RTPU, provided that the concentration of units of the high molecular weight diol is low enough to maintain a Tg of not less than 50 ° C. Examples of high molecular weight diles that can be used to form optically clear RTPUs include polyether glycols, such as polypropylene glycol, polyethylene glycol and polytetramethylene glycol; and polyester glycols, such as polycaprolactone glycol, as well as compounds that can be prepared from the condensation reaction of a diacid, diester or di (acid) aliphatic chloride with a linear, branched or cyclic diol, C2-C8, or ether containing diol, or mixtures thereof. Highly preferred high molecular weight polyester glycols useful for forming optically clear RTPUs include polycaprolactone glycol, polyethylene adipate glycol, and polybutylene glycol adipate. The preferred molecular weight scale of the high molecular weight polyether glycol is from 500 to 1000 amu. The preferred molecular weight scale of the high molecular weight polyester glycol is not less than 600, preferably not less than 800, and most preferably not less than 1000, not more than 2000, preferably not more than 1800, and most preferably no more than 1600 amu. The isocyanate to OH ratio of the reactants ranges from 0.95: 1, preferably from 0.975: 1, and most preferably from 0.985: 1, to 1.05: 1, preferably to 1.025: 1, and most preferably to 1.015: 1. The RTPU of the present invention is advantageously prepared in the presence of a suitable catalyst, such as those described in the US patent. reissued 37,671, column 5, line 46 to column 6, line 5. Preferred catalysts include stannous octoate, stannous oleate, dibutyltin dioctoate, and dibutyltin dilaurate. The amount of catalyst used is sufficient to increase the reactivity of an isocyanate group with an OH group without undesirably affecting the properties of the final product, and is preferably in the range of 0.02 to 2.0% by weight, based on the total weight of the reactants . The RTPUs of the present invention can be suitably prepared through intermittent or continuous procedures, such as those known in the art. A preferred continuous mixing process is reagent extrusion, such as the twin screw extrusion process described in the U.S.A. patent. 3, 642, 964. Optically transparent RTPUs can be prepared from the materials described herein. These materials can be processed, for example, through extrusion or injection molding, to form amorphous, resistant transparent articles, such as toothbrush handles, water or fuel filtration components, windows and connectors for intravenous delivery systems. . The present invention can be practiced suitably in any of the materials not specifically described herein. The following example is only for the purpose of illustrating r and is not intended to limit the scope of the invention.

EXAMPLE 1 Preparation of Optically Clear RTPUs Using TEG v BDQ In two separate 1000 liter containers, the PEG (obtained from The Dow Chemical Company) and the BDO (obtained from E. I. DuPont de Nemours &Co., Inc.) were charged. Both reagents were distilled at a vacuum of 100 kPa at 105 ° C for 4 hours to reduce the moisture content to less than 150 ppm. After completing the distillation, the containers were filled with dry nitrogen. MDl (4,4'-diisocyanatodiphenylmethane, greater than 98% para-para) was stored under nitrogen filling in a vessel maintained at 63 ° C. The exact amounts of reagents loaded into the containers were not critical, since a sufficient amount of each reagent was available for the appropriate experiment. The PEG, BDO and MDl, together with the catalyst FOM REZ ™ U L-22 (trademark of Witco Corporation) and the stabilizer lrganox ™ 1010 (trademark of Ciba-Geigy Corporation) were dosed to the feed port of an extruder of Werner double screw & Pfleiderer ZSK equipped with self-cleaning and self-aligning screws. The speeds of TEG, BDO and MDl were controlled so that the molar ratio of the NCO groups to the OH groups was on the scale from 1.0075 to 1.0125. The rotational speed of the extruder screws was kept constant throughout the operation. The following table shows the feed rates of the reactants, catalyst and stabilizer for the various molar ratios of BDO and TEG. Approximately 40 kg of materials were prepared in each operation.

Light adjustments were made to barrel and die temperatures during the course of the operation in order to optimize web handling and distribution of control pressure within the extruder. The temperature fixing points were on the scale from 200 ° C to 235 ° C. The RTPU s exited the extruder through a die, which extends in a band of 1 5 cm x 0.3 cm on a metal band coated with polytetrafluoroethylene, cold. After one to two minutes of cooling, the band was cut, and the resulting pellets were packed in bags lined with metal foil, with a weather barrier.

The RTPU pellets were placed in the hopper of a deshumedification dryer, in which hot air with a condensation point of about -34 ° C was passed over the pellets. The pellets were dried for 12 hours, then transferred to the hopper of an Arburg 221 E / 150 injection machine to produce type I tension rods in accordance with ASTM D638. To the hopper of the molding machine was placed a blanket with dry nitrogen to avoid moisture absorption of the RTPUs during molding. The barrel temperatures were set so that each RTPU completely filled the mold using a packing pressure on the 4800 5500 kPa scale. The injection speed was slow, less than 40% of the capacity of the machine (knob setting of 2 or less). The tensile specimens collected visibly were free of contamination, chamfer, flow lines and were optically transparent. These specimens had glass transition temperatures on the scale of 80 ° C (1 00% TEG) to 1 1 8 ° C (100% BDO), as determined through a differential scanning calorimetry operation. Mettier l Model 30 in a heating mode at a speed of 20 ° C / m inuto. After a conditioning period of 24 hours at 23 ° C and 50% relative humidity, tens of tensile specimens of each RTPU were pulled at a transverse head speed of 5 cm / min, utilizing an I n stron 1 1 20. The initial grip displacement was 1 1.4 cm and the elongation at rupture was determined using strain gauges over a 5-cm caliber length of the specimen. Figure 1 is a tensile elongation plot (determined according to ASTM D-638) against the molar fraction of TEG in the TEG / BDO mixture. The RTPUs prepared by the process described were optically transparent, that is, they had an individual glass transition temperature.

Claims (1)

1 - . 1 - A rigid thermoplastic polyurethane comprising: a) units of a diisocyanate; b) units of a polyethylene glycol having the structure HO- (CH2CH2O) p-H, wherein n is an integer from 2 to 6; c) 1,4-butanediol units; and d) not more than 25% by weight of units of a high molecular weight diol having a molecular weight of not less than 500 amu based on the total weight of the rigid thermoplastic polyurethane, the rigid thermoplastic polyurethane being further characterized by having a Tg of at least 50 ° C, provided that when the polyethylene glycol is triethylene glycol, at least one of the following limitations apply: a) the mol to mol ratio of the triethylene glycol units to the butanediol units is 25: 75 to 90: 10; b) the rigid thermoplastic polyurethane comprises no more than 0.9% by weight of high molecular weight diol units; or c) the thermoplastic polyurethane is optically transparent. 2. The rigid thermoplastic polyurethane according to claim 1, wherein the polyethylene glycol comprises triethylene glycol, and the ratio of the triethylene glycol units to the butanediol units is from 35:65 to 75:25. 3. The rigid thermoplastic polyurethane according to claim 1, wherein the polyethylene glycol comprises diethylene glycol, and the ratio of mol to mol of the diethylene glycol units to the butanediol units is from 25:75 to 65:35. . 4. - The rigid thermoplastic polyurethane according to claim 1, wherein the polyethylene glycol comprises hexaethylene glycol, wherein the ratio of mol to mol of the units of the glycol hexaethylene to the units of the butanediol is from 25:75 to 60:40. 5. The rigid thermoplastic polyurethane according to any of claims 1 to 4, wherein the thermoplastic polyurethane is optically transparent. 6. The rigid thermoplastic polyurethane according to any of claims 1 to 5, characterized in that it comprises not more than 1% by weight of high molecular weight defiol units. 7 - The rigid thermoplastic polyurethane according to any of claims 1 to 6, characterized in that it comprises 0% units of the high molecular weight diol. 8. The rigid thermoplastic polyurethane according to any of claims 1 to 6, wherein the units of the high molecular weight diol comprise units of a polyethylene glycol adipate or polybutylene glycol adipate having a molecular weight in the scale of 600 to 1800 amu, or units of a polyether glycol having a molecular weight on the scale of 600 to 1000 amu. 9. The rigid thermoplastic polyurethane according to any of claims 1 to 8, wherein the diisocyanate comprises 4,4'-diisocyanatophenylmethane, p-phenylene diisocyanate, 1,3-bis (isocyanatomethyl) -cyclohexane, 1,4 -diisocyanatocyclihexane, hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenyl, 4,4'-diisocyanatodicyclohexyl methane, or 2,4-toluene diisocyanate, or mixtures thereof. 10. The rigid thermoplastic polyurethane according to claim 9, wherein the diisocyanate comprises 4,4'-diisocyanatodifenylmethane.