MXPA99007672A - Composition and procedure for the preparation of thermoplastic polyurethanes (put) based on a soft segment of polibutadi - Google Patents

Abstract

The present invention relates to: A process for preparing a thermoplastic polyurethane material, consisting of the steps of casting an NCO-terminated prepolymer with 1,4-butanediol to form a molding composition, extruding the molding composition to form at least one strand of a polyurethane elastomer, granulation of the at least one strand of said polyurethane elastomer to form at least one pellet and processing of at least one pellet to form a thermoplastic article.

Description

COMPOSITION AND PROCEDURE FOR THE PREPARATION OF POLYURETHANES THERMO PLAS T CO S (PUT) BASED ON A SOFT SEGMENT OF P OL I BUTAD I ENO BACKGROUND OF THE INVENTION Polyurethanes based on soft segments of polybutadiene with a functionality of 2.0 are described by Yokelson et al. (US Patent No. 5,589,543). Yokelson et al. , however, they do not describe the use of polyurethanes as thermoplastics. The hydroxy-terminated commercial polybutadienes are used to formulate various polyurethane-binder molding resins. However, since these polybutadienes have functionalities greater than 2.0, they form thermoset polyurethane materials. Polyurethanes based on these polybutadienes can not be processed as thermoplastics (extrusion or injection molding processes). The hydroxy-terminated polybutadienes having a functionality of 2.0 are described by Chung et al. (U.S. Patent No. 5,247,023), Grubbs et al. (US Patent No. 5,750,815) and? Ubel et al. (U.S. Patent Nos. 5,512,635, 5,559".190, 5,519,101 and 5,403,904) However, these polybutadienes have not been used to make a thermoplastic polyurethane material.The polyurethane elastomers are described. made with polybutadienodiols having a functionality of 2 are manufactured by making a prepolymer of toluene diisocyanate (DIT) of polybutadiene diol, mixing in methylene-bis-ortho-chloroaridine (-MbOCA) and then curing the mixture by compression of the same at high temperature Additionally, said elastomers are described as being made in a single process, by mixing 1,4-butanediol with the polybutadiene diol, adding molten diphenylmethyl diisocyanate (D-IM) and compressing the reaction mixture at elevated temperature and pressure, Frisch et al .. Cell Polym, 1996, 15 (6), 395. However, it has been found that polyurethanes molded from mixtures of DIM, a polybutadienodiol and 1-butanediol by the process of prepolymers have very poor initial mechanical properties. Even after prolonged post-curing at high temperature (18 h, 110 ° C), the polymers are not hard enough to be cut and studied for their mechanical properties. However, we have seen, surprisingly, that the extrusion of the cast materials results in a marked improvement in their mechanical properties.

COMPENDIUM OF THE INVENTION The present invention relates to a process for preparing a thermoplastic polyurethane material, which consists of the steps of emptying a prepolymer finished in NCO with 1,4-butanediol to form a pouring composition; extruding the casting composition to form strands of a polyurethane elastomer; granulating these strands of the polyurethane elastomer to form pellets, and processing these pellets to form polyurethane articles. The present invention also relates to a thermoplastic polyurethane material made by the aforementioned process.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyurethane, consisting of an NCO-terminated prepolymer, consisting of the reaction of a polyisocyanate with a linear non-crosslinked polyolefin functionalized at its end without branched chain pendant groups, where the process for preparing said polyurethane consists of the steps of emptying the NCO-terminated prepolymer with 1,4-butanediol to form a molding composition. The prepolymer can also be flushed with 1,3-propanediol, 1,3-butanediol, 1,6-hexanediol or other diols. The emptying takes place at atmospheric pressure in a mold heated to between 50 and 120 ° C. The molding composition is then extruded to form at least one strand of a polyurethane elastomer. Preferably, the extrusion takes place in an extruder, such as a one or two-screw extruder. More preferably, a double-screw extruder, such as, for example, a Werner &ZSK-V extruder; 53 mm Pfleiderer The threads of the polyurethane elastomer are then granulated in a granulator, such as, for example, any rotary vane granulator or a 6"Cum-berland granulator Finally, the pellets are still processed by injection molding in a Newbury 7 The pellets can also be extruded, molded by blowing air, blown into a film, etc. The polyolefin of the present invention is prepared by reaction of a chain transfer agent with a cyclic olefin in presence of a catalyst, to form the desired polyolefin Specifically, the polyolefin is a hydroxyl-functionalized polybutadiene (PBHF), which is prepared by the method of "Ring Opening Metathesis Polymerization" ("PMAA") (Grubbs et al., US Patent No. 5,750,815) The synthesis of PBHF requires a "chain transfer agent (ATC), which serves to add functionality (gru hydroxyl) to the ends of the polymer chain. The use of ATC depends on the type of catalyst of the P-MAA used. In the present invention, the most preferred chain transfer agent is 1,4-diacetoxy-2-butene. Accordingly, said chain transfer agent is uniquely useful with ruthenium-based metathesis catalysts and has a dramatic influence on the viscosity of the polybutadiene diol. In the present invention, the preferred cyclic olefins are cyclobutenes and cyclooctadienes and the most preferred cyclic olefin is 1,5-cyclooctadiene, which is most likely reacted with 1,4-diacetoxy-2-butene in the presence of a catalyst to form the PBHF present. The PBHF that results from this procedure has the structure: HO- [-CH2-CH = CH (CH2) 2-CH = CH-CH2-] I1-CH2-CH = CH-CH2? H where n is a number average value from 1 to 1,000. The catalysts that can be used in the present invention and their preparation are described in the patent granted to California Institute of Technology, Grubbs et al. (US Patent No. 5,342,909). In a preferred embodiment, the catalyst required in the present invention is a compound based on a ruthenium metal complex and carbene. In a more preferred embodiment, the catalyst is bis (tricyclohexylphosphine) benzylidinuthenium dichloride. The polyolefins of the present invention have unique physical properties due to linearity, unsaturation, functionality of 2.0, absence of crosslinking, low viscosity and low polydispersity and are capable of offering these properties to other polymeric compounds. The polyolefin PBHF of the present invention has a viscosity ranging between 500 and 40,000 mPa-s and, more preferably, between 800 and 16,000 mPa-s. The functionality of said polyolefin varies between 1.8 and 2.0 and, more preferably, is 2.0. The functionality is determined by titration and osmometry in the vapor phase. The number average molecular weight of PBHF ranges from 196 to 200,000 g / mol and, more preferably, from 1,500 to 6,500 g / mol. A low viscosity prepolymer can also be prepared by using this polyolefin. These prepolymers, which can be used as a diisocyanate component according to the present invention, are prepared from monomeric diisocyanates and the polyolefin, PBHF, of the present invention. The prepolymers of the present invention have an average functionality of 1.8 to 2.0 and, more preferably, 2.0. Additionally, the prepolymers have an NCO content ranging from 3 to 20% and, more preferably, from 4 to 15%. Finally, the prepolymers preferably have a viscosity ranging between 500 and 20,000 mP-s @ 25 C and, more preferably, between 1,000 and 10,000 mPa-s @ 25 ° C. Suitable monomeric diisocyanates can be represented by the formula R (NC0) 2 where R represents an organic group. The molecular weight of these diisocyanates is from about 112 to 1,000, preferably from about 140 to 400 and, more preferably, from 174 to 300. Preferred diisocyanates for the process according to the present invention are those in which R represents an aliphatic hydrocarbon group divalent having from 4 to 40, preferably from 4 to 18 carbon atoms; a divalent cycloaliphatic hydrocarbon group having from 5 to 15 carbon atoms; a divalent araliphatic hydrocarbon group having from 7 to 15 carbon atoms; or a divalent aromatic hydrocarbon group having from 6 to 15 carbon atoms. Examples of suitable organic diisocyanates include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,2-dodecamethylene diisocyanate, cyclohexate. -xano-1,3- and -1,4-diisocyanate, l-isocyanato-2-isocyanato ethylcyclopentane, l-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or DIIF), bis (4) -isocyanatocyclohexyl) methane, 2,4'-dicyclohexylmethane diisocyanate, 1,3- and 1,4-bis (isocyanatomethyl) cyclohexane, bis (4-isocyanato-3-methylcyclohexyl) methane, diisocyanate, -1, 3- and / or -1, 4-xylylene, 1-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4- and / or 2,6-hexahydrotoluylene diisocyanate, 1,3-diisocyanate - and / or 1,4-phenylene, 2,4-diisocyanatotoluene (and mixtures thereof with preferably up to 35% by weight, based on the mixture, of 2, β-diisocyanatotoluene), 4,4 'diisocyanate -diphenylmethane (and its mixtures with diisocianat or 2,4'-diphenylmethane and / or 2,2 '-diphenylmethane diisocyanate), 1,4-diisocyanatophthalene and mixtures thereof. Preferred organic diisocyanates include 1,6-hexamethylene diisocyanate, l-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isoforopa diisocyanate or DIIF), bis (4-isocyanatocyclohexyl) methane, 1-isocyanate-1 -methyl-4 (3) -isocyanatomethylcyclohexane, 2,4- and / or 2,6-toluylene diisocyanate and 2,4-diphenylmethane diisocyanate. More preferably, 4,4'-diphenylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate are used.

Of course, the prepolymer of the present invention can include catalysts, plasticizers, light stabilizers, thermal stabilizers, lubricants, antioxidants and other additives. The thermoplastic polyurethane of the present invention can be used to make polyurethanes or polyurethane articles for use, for example, in elastomers, sealants, coatings, encapsulants, blown films, binders and sheets. The invention is further illustrated, although without intending to limit it, by the following examples, in which all parts and percentages are by weight, unless otherwise indicated.

EXAMPLES Example 1 A 7.0% NCO prepolymer was made with commercial material PolyBD R45M (2.501 g) and DIM (997.2 g) and stirred overnight at 87 ° C. The chain of this prepolymer was then extended with 1,4-butanediol (252.5 g) at 90 ° C, poured into a mold and cured overnight at 90 ° C. The resulting R45HT-based polyurethane was placed in a melt indexer at 205 ° C with a weight in the drum that '-'5 had a mass of 10 kg. This polyurethane did not flow, but it was carbonized due to the crosslinking present in the polyurethane.

Example 2 A prepolymer of 7.0% NCO was made with PBHF (317.25 g) and DIM (130.50 g) and stirred overnight at 87 C. The chain of this prepolymer was then extended ( 326.6 g) with 1,4-butanediol (23.4 g) at 90 ° C, it was poured into a mold and cured overnight at 90 ° C. The resulting plates were soft and cheesy. The mechanical properties of this material could not be measured. This polyurethane was placed in a melt indexer at 205 ° C with a weight in the drum having a mass of 10 kg. This polyurethane flowed easily (IFF = 8 g / 10 min) under these conditions.

Example 3 The polyurethane prepared in Example 2 was cooled by placing it on dry ice and then grinding in a mechanical crusher. After mixing with Acrawax C as a processing aid, the material was extruded in a 1.5"single-screw extruder under the following conditions: Table 1. Extrusion conditions After cooling, the strands from the extruder were granulated and the pellets were molded by injection into plates under the following conditions: Table 2. Conditions of injection molding After conditioning at room temperature, the following properties were measured in an injection molded plate.

Table 3. Mechanical properties of the sample The poor physical properties of the molded polyurethane based on PBHF were drastically improved by the extrusion. This improvement is not possible for PolyBD R45 M materials, since the functionality of these materials is greater than 2.0 and, therefore, they form cross-linked polyurethanes that do not flow under heat and pressure. Although the invention has been described in detail in the foregoing for illustrative purposes, it is to be understood that said detail has that sole purpose and that those skilled in the art can make variations therein without departing from the spirit and scope of the invention, except as may be limited by the claims.

Claims (21)

Claims

1. A process for preparing a thermoplastic polyurethane material consisting of the following steps: a) molding a finished prepolymer in NCO with 1,4-butanediol to form a molded composition; b) extruding said molded composition to form at least one strand of a polyurethane elastomer; c) granulating said at least one strand of said polyurethane elastomer to form at least one pellet, and d) processing said at least one pellet to form said thermoplastic polyurethane articles.

2. A process according to Claim 1, wherein said NCO-terminated prepolymer consists of the reaction of a polyisocyanate with a linear non-crosslinked polyolefin, functionalized at the ends, without branched chain groups, prepared by reaction of 1,4-diacetoxy-2 -butene with 1, 5-cyclooctadiene in the presence of a catalyst, consisting of a ruthenium metal complex and carbene, followed by further processing to form hydroxyls, characterized by the fact that the number of functionality of said polyolefin, determined by titration and osmometry in vapor phase, is 2.0 or less and that the viscosity of said polyolefin varies between about 800 and 16,000 mPa • s to a number average molecular weight with a range of 2,600 to 6,500 g / mol.

3. A process according to Claim 2, wherein said catalyst is bis (tricyclohexylphosphine) benzylidinutenium dichloride.

4. A process according to Claim 3, wherein said polyolefin has "a molecular structure of HO- [-CH2-CH = CH (CH2) 2-CH = CH-CH2-] n-CH2-CH = CH-CH2OH where n is a numerical average value from 1 to 1,000.

5. A process according to Claim 4, wherein said prepolymer has a functionality of 2.0 or less, an NCO content ranging between 4 and 15% and a viscosity ranging between about 500 and 20,000 mPa-s @ 25 ° C. .

6. A method according to Claim 1, wherein an extruder is used to extrude said molding composition in order to form at least one strand of a polyurethane elastomer.

7. A process according to Claim 6, wherein said extruder is a single-screw extruder.

8. A process according to Claim 6, wherein said extruder is a double-helix extruder.

9. A method according to Claim 1, wherein said processing is the injection molding of said pellets.

10. A method according to Claim 1, wherein said processing is the extrusion of said pellets.

11. A method according to Claim 1, wherein said processing is the insufflation of film of said pellets.

12. A thermoplastic polyurethane material prepared by a process consisting of: a) molding an NCO-finished prepolymer with a diol to form a molded composition, b) extruding said molded composition to form at least one strand of an elastomer of polyurethane, c) granulating said at least one strand of said polyurethane elastomer to form at least one pellet, and d) processing said at least one pellet to form said thermoplastic polyurethane material.

13. A thermoplastic polyurethane material according to claim 12, wherein said prepolymer finished in NCO -0 consists of the reaction of a polyisocyanate with a linear non-crosslinked polyolefin, functionalized at the ends, without branched chain branching groups, prepared by the reaction of 1,4-diacetoxy-2-butene with 1,5-cyclooctadiene in presence of a catalyst consisting of a ruthenium metal complex and carbene, followed by further processing to form hydroxyls, characterized in that the number of functionality of said polyolefin, determined by titration and vapor phase osmometry, is of 2.0 or less and that the viscosity of said polyolefin varies between about 800 and 16,000 mPa • s to a number average molecular weight in a range of between 2,600 and 6,500 g / mol.

14. A thermoplastic polyurethane material according to claim 13, wherein said polyisocyanate is DIM.

15. A thermoplastic polyurethane material according to claim 13, wherein said catalyst is bis (tricyclohexylphosphine) benzylidinutenium dichloride.

16. A thermoplastic polyurethane material according to claim 12, wherein said diol is 1,4-butanediol.

17. A thermoplastic polyurethane material according to claim 13, wherein said diol is 1,4-butanediol and said polyisocyanate is DIM.

18. A thermoplastic polyurethane material according to claim 13, wherein said polyolefin has a molecular structure of HO- [-CH2-CH = CH (CH2) 2 -CH = CH-CH2-] n-CH2-CH = CH-CH2OH where n it is a numerical average value of up to 1,000.

19. A method according to Claim 12, wherein said processing is the injection molding of said pellets.

20. A method according to Claim 12, wherein said processing is the extrusion of said pellets.

21. A method according to Claim 12, wherein said processing is the insufflation of film of said pellets.