JPS6335641B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for hydrogenating a conjugated diene polymer using a Pd catalyst with improved catalytic activity. Conventionally, carrier-supported catalysts in which metals from the periodic table group are supported on porous supports such as carbon, silica, and alumina have been commonly used as catalysts for hydrogenating carbon-carbon double bonds in conjugated diene polymers. It is used. By the way, when hydrogenating unsaturated bonds in a polymer, in the case of styrene-butadiene (random or block) copolymers, if the benzene nucleus of the styrene is also hydrogenated, the polymer loses its rubber-like properties. In addition, in the case of acrylonitrile-butadiene (random or alternating) copolymers, reduction of the nitrile group significantly reduces oil resistance, and the inherent properties of the polymer are lost due to hydrogenation. As the temperature decreases, there is no point in modifying the polymer. Therefore, selectively only the double bonds of the conjugated diene moieties in the polymer must be hydrogenated. Catalytic metals with such selectivity include Pt,
Precious metals such as Pd are often used. However, since these noble metals are expensive, it is desirable to be able to selectively hydrogenate them using as little amount as possible. Furthermore, when hydrogenating high molecular weight polymers, the hydrogenation reaction is difficult to proceed due to the high viscosity of the reaction system, and a large amount of catalyst must be used, requiring a highly active and highly selective catalyst. There is. As a result of extensive studies, the present inventors have found that when a conjugated diene polymer is hydrogenated using a catalyst in which Pd and other metals are simultaneously supported on a carrier, In comparison, they discovered that it has extremely high activity and high selectivity, leading to the completion of the present invention. Therefore, an object of the present invention is to provide a Pd-based catalyst that has high activity in the hydrogenation of conjugated diene-based polymers and can selectively hydrogenate carbon-carbon double bonds in polymer chains or side chains. It's about doing. This object of the present invention is to hydrogenate a conjugated diene polymer by adding Pd to a porous powdery and/or granular carrier such as carbon, silica, alumina, etc. as a catalyst, a,
This is achieved by using a catalyst on which at least one metal selected from Group A metals is simultaneously supported. The catalyst used in the present invention is a porous granular and/or powder carrier that is commonly used, such as silica, silica alumina, alumina, diatomaceous earth, activated carbon, or carbon black used for rubber or color. and at least one metal selected from metals of groups a, a, a, a, and a of the periodic table are simultaneously supported on a carrier. Metals of groups a, a, a do not have hydrogenation ability alone. In addition, the metals of groups a and a do not have hydrogenation ability alone, or even if they do have it, the activity is extremely low. The above-mentioned metal can be supported on the carrier by a conventional method and is not limited in any way. ,
Support can be achieved by immersing the carrier in an aqueous solution of salts such as acid chlorides, sulfates, and carbonates. An active catalyst is then obtained by reduction. The amount of Pd supported on the carrier is 0.001 to 30% by weight, preferably 0.01 to 10% by weight. If the amount of supported Pd is too small, the amount of catalyst supported on the carrier used during the reaction will be too large, increasing the viscosity of the system, making stirring difficult, and making the catalyst ineffective. On the other hand, if the amount supported is too large, the dispersion of the metal on the carrier will be poor, the metal particle size will also increase, and the catalytic activity will decrease. The atomic ratio of the element co-supported with Pd to Pd is in the range of 0.001 to 50, preferably 0.005 to 10. The amount of the carrier-supported catalyst used is in the range of 5 to 2000 ppm, preferably 10 to 1000 ppm, based on the amount of Pd per polymer.
Although it is possible to use more than 2000ppm, it is not economical. In the conjugated diene polymer used in the present invention, the conjugated diene monomer is 1,3-butadiene, 2,3
- One or more monomers selected from dimethyl butadiene, isoprene, 1,3-pentadiene, etc. from 10 to 100% by weight of the total monomers, and/or ethylenically unsaturated monomers containing unsaturated nitriles, such as acrylonitrile, methacrylate, etc. monovinylidene aromatic hydrocarbons such as lonitrile, styrene, alkylstyrene (o-, m
-, p-methylstyrene, ethylstyrene, etc.)
such as unsaturated carboxylic acid or its ester,
such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid or methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, etc., vinylpyridine and vinyl esters such as vinyl acetate, etc. One or more monomers selected from 0 to 90% by weight of all monomers
A conjugated diene polymer and/or a conjugated diene copolymer composed of These (co)polymers can be processed by emulsion polymerization, solution polymerization,
It may be produced by any polymerization method such as bulk polymerization, and specifically, polyisoprene, polybutadiene, styrene-butadiene (random or block) copolymer, acrylonitrile-butadiene (random or alternating) copolymer. , butadiene-isoprene copolymer, isoprene-isobutylene copolymer, and the like. Although the hydrogenation reaction can be carried out with the polymer as it is, good results are obtained when the polymer is dissolved in a solvent and carried out in a solution state. The concentration of the polymer solution is between 1 and 70% by weight, preferably between 1 and 40% by weight. The solvent is not particularly limited as long as it does not adversely affect the catalyst and dissolves the polymer to be hydrogenated, but examples include benzene, toluene, xylene, hexane, cyclohexane, tetrahydrofuran, acetone, methyl ethyl ketone, ethyl acetate, cyclohexanone, etc. is commonly used. Polymers produced by solution polymerization can be hydrogenated as polymer cements. The hydrogenation reaction is carried out in an autoclave, and the reaction temperature is between 0 and 300°C, preferably between 20 and 150°C.
It is. A temperature of 150° C. or lower is preferred in order to allow the selective hydrogenation reaction to proceed and to suppress undesirable side reactions.
Although the hydrogen pressure is not particularly limited, it is usually carried out in the range of atmospheric pressure to 300 Kg/cm ² , preferably 5 to 200 Kg/cm ² . 300Kg/cm2 or ^more due to equipment reasons,
Impractical from an operational standpoint. Hydrogenated polymers have excellent weather resistance, ozone resistance, heat resistance, cold resistance, etc.
It can be used in a wide range of fields. The present invention will be specifically explained below using Examples. Example 1 Activated carbon was used as a carrier, and Pd, Pd/Na,
Acrylonitrile-butadiene copolymer was hydrogenated using catalysts supported with Pd/Ca, Pd/Sc, Pd/Ti, and Pd/V. In the case of a combination system, the atomic ratio of each metal and Pd was 1:1. In both cases, the Pd content per carrier is 1% by weight. (Preparation of catalyst) PdCl ₂ , PdCl ₂ /NaCl, PdCl ₂ /CaCl ₂ ,
PdCl ₂ /ScCl ₃ , PdCl ₂ /TiCl ₄ and PdCl ₂ /
Activated carbon was immersed in an aqueous solution of VCl ₄ to sufficiently impregnate the activated carbon with the aqueous solution, reduced with formalin-caustic soda, and used as a carrier-supported catalyst. (Hydrogenation method) 17g of acetone in a 100ml autoclave
3 g of acrylonitrile-butadiene copolymer (bound acrylonitrile amount 41.1% by weight,
ML ₁₊₄₁₀₀ ℃=53, abbreviated as NBR) and 0.075g of the above-mentioned carrier-supported catalyst (equivalent to 2.5 parts by weight per 100 parts by weight of polymer) were charged, and after purging with nitrogen, the mixture was heated to 50 kg/kg with hydrogen. The hydrogenation reaction was carried out at 50° C. for 4 hours under pressure of cm ² . Also, cyclohexane 27
g of polybutadiene (cis 1,4 content 98%,
A solution in which 3 g of ML ₁₊₄₁₀₀ °C = 40 (abbreviated as BR) was dissolved and the same amount of carrier-supported catalyst as above were charged, and after purging with nitrogen, the pressure was increased to 50 Kg/cm ² with hydrogen, and the mixture was heated at 90 °C for 4
The hydrogenation reaction was carried out for an hour. The results are shown in Table 1.
No reduction of the nitrile group was observed from infrared absorption measurements.

[Table] * Determined by iodine value method Example 2 A catalyst was prepared in the same manner as in Example 1 except that Zr was used as the metal supported together with Pd (ZrCl ₄ was used as the Zr source). However, the atomic ratio with Pd was changed to 0.1, 0.5, 1, 2, and 10. The catalyst activity was that used in Example 1.
A hydrogenation reaction was carried out using NBR under the same conditions as in Example 1. The amount of Pd supported is 1% by weight per activated carbon.
It is. In either case, no reduction of the nitrile group was observed.

[Table] *Determined using the iodine value method.
Example 3 Using the catalyst prepared in Example 2 with a Zr/Pd atomic ratio of 0.5 (the amount of Pd supported is 1% by weight of activated carbon), the BR used in Example 1, the styrene-butadiene random copolymer (the amount of bound styrene was 23.5) Weight%, ML ₁₊₄₁₀₀ ℃
= 50, abbreviated as SBR) polyisoprene (cis 1,4 content 97%, ML ₁₊₄₁₀₀ °C = 80, abbreviated as IR) was dissolved in cyclohexane (concentration
10% by weight). The hydrogenation reaction was carried out under the same conditions as in Example 1 except for the reaction temperature of 90°C. Catalyst amount is polymer
It is 2.5 parts by weight per 100 parts by weight. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1 In a method of hydrogenating carbon-carbon double bonds of a conjugated diene polymer, porous powder and/or
Or Pd in a granular carrier, periodic table a, a,
A method for hydrogenating a conjugated diene polymer, which comprises using a catalyst on which at least one metal selected from Groups a, A, and A is simultaneously supported.