PROCESS FOR THE SELECTIVE HYDRATION OF UNSATURATED POLYMERS The present invention relates to a method for the selective precipitation of unsaturated polymers containing both carbon-carbon double bonds and aromatic rings, and to a hardening complex for carrying out such a process. idrogenac ion. The double bonds of unsaturated polymers are useful, for example, in the process of vulcanization of elastomers, i.-, during which an intermalecular chemical connection is made by means of said double unsaturated bonds and the properties of the elastomers are improve, for example, they become mechanically and chemically more durable and you get products similar to rubber
technically e pleable. On the other hand, unsaturated bonds, especially carbon-carbon double-carbon bonds that remain or are intentionally left in the final product due to the process or to the final product properties also have disadvantages in the polymer product. These disadvantageous properties, such as, for example, a limited resistance to weathering, heat or ozone, can be improved by the selective hydrogenation of the olefinic double bonds of the polymer. The polymers suitable for use in this method are from
Preference is given to conjugated diolefin polymers, especially coatings thereof, which have been prepared from said diolefin and aromatic vinyl hydrocarbons. They can be random or block polymers, or combine ions thereof, wherein the conformation of the polymer can be linear, star-shaped or radial. The polymers especially suitable for the invention are block polymers of buta-ienosine. The hydrogenated ion products of the styrene-butadiene-styrene block polymers (the polymers known as SBS) are r; economically much more valuable than the initial material since the hydrogenated product is thermoplastic and can be reused, which can not be achieved with the SBS rubber that has been laid, that is, vulcanized, with sulfur or peroxide? gone. The catalyst must be what is known as a homogeneous compound and not bound to a solid carrier, so that it has access to all parts of the polymer molecule and to be able to hydrogenate all the carbon-carbon olefinic double bonds present. Conventionally, the catalysts employed in many hydrogenation reactions of diene polymers have been metals of group VIII of the Periodic Table of the Elements, or compounds thereof. These include nickel, cobalt, platinum and palladium compounds. Its use has been limited by the high price of the compounds and / or the catalysis of the polymer decomposition reactions caused by its residues, in such a way that it has been necessary to remove the catalytic residues of the polymer h id ogen. Frequently, a co-ct is used together with the aforementioned compounds to promote or improve in some other way the action of the catalyst itself. Suitable compounds include the aluminum alkyl compounds presented in U.S. Patent Nos. 3,698,088 and 4,107,236. It has been observed that metallite compounds also serve as compounds that hydrogenate polymers. Its action is quite efficient, and therefore it has not always been necessary to remove its residues from the final product, and the quality of the product has not been affected. In this case, also, a ca-catalyst is required, such as, for example, l-alkanoyl compounds, alkyl lithium compounds and Grinard reagents to promote the action of the catalyst compound. The co-catalyst used together with a titanócene compound, which was b isciclopentadieni 1 ti tanium dihalide, was, in accordance with the patent application EP 532 009, alkyl benzoate and, in accordance with EP 471 415, alkali metal compounds, espec ialme > nte Li-alkyl compounds. In accordance with the patent application EP 434 469, a SBS polymer is hydrogenated by means of ironocene and a metal complex catalyst. The preparation of the metal complex, which contains Li and Al compounds, hor, is carried out by means of a very complicated and delayed in situ procedure. The method according to the invention is characterized in that the catalyst used in the hydrogenation reaction is a new meta-1 -cene / co-1-complex complex which is formed from a complex of a metalocene and an alu-oxane. The precursor of the metallocene component employed is preferably circumscribed compounds of the form (Ar) 22rR2, where Ar is a cyclopentadienyl group or a dienyl, which may also be substituted (usually with an alkyl group), and R is a halogen group , alkyl or aryl, preferably chlorine, a lower alkyl group, such as a methyl or benzyl group. The ca-catal izadar employed is an alumo compound? not containing one or more groupings -Al (R) -0-, which has a lower alkyl group, preferably a methyl group. Metholamoxane (MAO) is often obtained in the form of a toluene solution at 10-30 * /., In which case the aluminum content in the solution is about 5-15 * 4. This catalyst complex is homogeneous in such a way that even the carbon-carbon double bonds found in the central part of the polymer molecule, often in a sterically difficult position, can be hydrogenated, not only the double bonds found in terminal positions. The catalyst complex is also selective, and the unsaturated bonds of the 11th or 11th year are not hydrogenated. The hydrogenation of unsaturated polymers by means of the catalyst complex according to the invention is quick and easy, compared to current methods. The hydrogenation reaction is carried out in the following manner: first the polymer is dissolved in a suitable solvent, the operation is carried out in an inert atmosphere throughout the hydrogenation. Suitable solvents include aromatic hydrocarbons, for example, benzene, toluene and xylene, or else aliphatic hydrocarbons, for example, pentane, he: <Year and heptans. Next, hydrogen gas is added to the polymer solution and the hydrogen reduces the olefinic double bonds of the polymer being treated, by hydrogen bonding with them. The hydration temperature can be within a range of 30 to 300 degrees C, preferably between 70 and 120 degrees C. If the temperature is lower than 30 degrees C, the activity of the catalyst is weak and the reaction of hydrogenation is low. It can be done too slowly. If the temperature is above 300 degrees C, secondary reactions and decomposition of the polymer can occur, and even the aromatic ring can begin to be hydrogenated. The hydrogen pressure during hydrogenation can be within the range of 5 to 50 bars. If the pressure is lower, the hydrogenation reaction will be slow, and little to no hydrogenation will be observed. A pressure of that range or pressure can cause secondary reactions and decomposition of the polymer. Preferably the pressure is from 15 to 25 bars. The concentration of the catalyst complex in the reaction solution of the hydrogenation reaction is 0.1-5 * 4 by weight, preferably 0.2-2 * 4 in
_, > weight. When the amount of catalyst is maintained within this range, specifically olefinic double bonds can be selectively hydrogenated, without affecting the aromatic linkages in any way. The following describes exemplary modalities of the
hydrogenation of block polymers of isomeric-butadiene-sty (SBS). Toluene was used therein as a solvent for the polymer and as the medium for the reaction. Most of the double bonds had reacted after a period of about 15 minutes from the beginning 0 of the reaction but to ensure the progress of the reaction until its completion, the reaction proceeded for 40-150 minutes. EXAMPLES 1-4 5.0 g of an SBS polymer (what is known as star block polymer having a molecular weight of about 135,000 g / mol) was placed in a reactor and 100 ml of toluene were added. A catalyst complex was prepared by mixing in an inert atmosphere the amount shown in Table 1 of a catalyst precursor, which was the ironocene compound indicated in Table 1, and a catalyst, which was always i lalu oxano. In the catalyst complex, the relation between Al and Zr was approximately 118 (the precise value appears in table 1). The temperature of the reaction mixture was raised to 90 degrees C, and the reactor was hydrogenated 3 times, and then the hydrogen pressure was raised to 20 bars. The hydrogenation continued for 40 minutes. The product was first washed with a 0.1 N HC1 solution, and then several times with water, said product was isolated
by means of steam distillation, and was dried. The degree of hydrogenation of the product was determined by spectroscopy NMR; the results appear in Table 1. No degree of hydrogenation of the aromatic rings based on the NMR spectra could be observed. The 0 selectivity of the hydrogenation was also determined by the hydrogenation of a sty onomer and by analysis of the samples by means of 6C-MS. It was observed that the aromatic ring did not become hydrogenated in the conditions used. 5 TABLE 1 Zirconocene Example Amount of Ratio Srado of tasting 1 i zador Al / Zr in hrogenogenic-mmol / 100 9 the completion ('/,) of polymer catalyst. 1 Cp2ZrC12 3.08 118 80 2 (Me2Cp) 2ZrC12 2.81 115 73 3 (n-BuCp) 2ZrC12 • ^ * 7 * 7 118 74 4 < Ind) 2ZrC12 2.29 119 56 Cp2ZrC12 = b-cyclopentadienyl dichloride 1-Zr (Me2Cp) 2ZrC12 = bis-dimethyl dichloride l-cyclopentadieni 1-Zr (n ~ BuCp) 2ZrCl 1 = bis-di-n-dichloride bu i lcyclopentadieni 1-Zr (I d) 2ZrC12 = bis-i deni dichloride 1-Zr EXAMPLE 5 By the method described in Example 1, a hydrogenation reaction was performed on a similar polymer. The catalyst complex was formed from bis-indeni 1-Zr-dibenzyl (3.14 mmol / 100 g polymer) and methylaluoxan (3.60 g). The Al / Zr ratio in the complex was therefore 117. The degree of hydrogenation of polymer obtained was 80 * /. EXAMPLES 6-10 In these examples, the effect of the amount of co-catalyst was investigated by using the hydrogenation process and the SBS polymer described in example 1. The catalyst complex was formed by bis-cyclopentadiene dichloride. -Zr and dimet i lalumoxane. The hydrogenation reaction proceeded for approximately
150 minutes The amounts of circanócepo catalyst and 5 of co-catalizador, the relation Al / Zr in the complex, the temperature of hydrogenation and the pressure of hydrogen gas, as well as the degree of hidrogena ion achieved appear in table 2. TABLE 2 l, _. Example 6 7 8 9 10 Amount of catalyst 1.44 3.08 1.37 3.09 1.44 mmol / 100 g of polymer Amount of co-catalytic-0.48 3.58 4.83 7.63 19, 85 dor, g 15 Al / Zr ratio in 12 118 131 246 512 catalyst complex Temperature, degrees C 2 20000 9 900 150 90 100 Pressure, bar 26 20 20 20 Degree of hydrogenation 0 0 8 800 84 83 54 0 (*? ) Based on these examples, Figure 1 was prepared, in which the degree of hydrogenation is shown as a function of the Al / Zr ratio in the catalyst complex. EXAMPLES 11-14 In these examples, the effect of the amount of catalyst, i.e., the zirconocene compound, was investigated when the zirconocene compound was bis-cyclapentadieni dichloride 1-Zr. The hydrogenation reaction was performed using the procedure described in Example 1. Table 3 shows the actual and proportional amounts of the zirconocene compound, the Al / Zr ratio in the complex, and the degree of hydrogenation obtained. TABLE 3 t t "Example Amount of Amount of Relationship Degree of zirconocene, Al / Zr complex in hydrogemmol / l Og of catalyst, polymer comnation% by weight ple o (* /.) 11 0.038 0.22 114 31
12 0.068 0.40 131 84 13 0.154 0.90 118 80 14 0.352 2.00 114 83
0