JPH0142283B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for hydrogenating polymers. More specifically, the present invention relates to a method for hydrogenating a polymer having a carbon-carbon double bond using a special carbon black as a carrier and a catalyst on which a metal is supported. Generally, polymers having carbon-carbon double bonds in the molecule, particularly in the main chain, are inferior to polymers without double bonds in terms of heat resistance, weather resistance, ozone resistance, etc. Needless to say, this is because the double bonds possessed have high reactivity, making them susceptible to attack by oxygen, ozone, and the like. Hydrogenation has long been used as a method to improve this weakness. This is a method of chemically stabilizing double bonds by hydrogenating them and turning them into saturated bonds. Various metals or non-metals are used as catalysts for this hydrogenation reaction, but typical examples include metals from group 3 of the periodic table.
Examples include iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. In many cases, these metals are supported on porous carriers such as carbon (activated carbon), alumina, silica alumina, and diatomaceous earth. The gist of the present invention is that when a polymer having carbon-carbon double bonds is hydrogenated using a catalyst in which a catalytic metal is supported on a carrier, the catalyst carrier has a specific surface area of at least
800m ² /g, DBP oil absorption at least 250ml/100
The present invention relates to a method for hydrogenating a polymer, which is characterized by using a special carbon black, which is .g. The present inventors have investigated the hydrogenation reaction of the above-mentioned polymer using various carbon blacks other than activated carbon as a carrier, and found that by using a special carbon black, a catalyst with extremely high hydrogenation reaction activity was developed. The present invention was based on the discovery that . Hydrogenation costs can be reduced by increasing the catalytic activity, and it goes without saying that the economical effect is particularly great when a noble metal catalyst such as palladium or ruthenium is used. The carbon black used in the present invention is a new carbon black having a specific surface area of at least 800 m ² /g determined by low-temperature nitrogen adsorption method and a DBP oil absorption of at least 250 ml/100 g according to JIS K6221. The reason why the specific surface area and DBP oil absorption are so large is thought to be because this special carbon black has a hollow shell structure. Generally, when the structure develops, DBP is retained in the gaps between the particles, so the DBP oil absorption value increases. However, this abnormally large oil absorption value cannot be explained by mere structure development; This is thought to be due to DBP entering the area. It is presumed that the reason for the large specific surface area is the same. There are a wide variety of carbon blacks currently on the market, but they are broadly classified into rubber, color, and battery uses, and depending on the manufacturing method, there are furnace blacks, thermal blacks, channel blacks,
It is classified as acetylene black, etc. These conventional carbon blacks have a specific surface area of 5 to 600 m ² /g and a DBP oil absorption of 30 to 250 ml/100 g.
Therefore, the carbon black of the present invention can be said to be a special carbon black. Generally, in the hydrogenation reaction of low-molecular compounds, it is desirable that the specific surface area of the carrier is large, but the specific surface area and the hydrogenation reaction activity are not necessarily proportional to the large-volume polymeric substances used in the present invention. Generally, when the specific surface area of a carrier increases, many pores with a small radius are generated on the carrier surface. Pores with a small radius cannot easily accept large-volume polymeric substances, resulting in a decrease in hydrogenation reaction activity. If the maximum value of the pore radius distribution is less than 100 Å, the number of pores with low hydrogenation activity for polymeric materials will increase, and the number of pores with large radius that exhibit hydrogenation activity will decrease, so the support will It is known that even if the specific surface area is large, the hydrogenation activity will be low as a result (Japanese Patent Application Laid-open No. 40897-1989). However, although the above-mentioned special carbon black of the present invention has a maximum value of pore radius distribution of 50 Å or less, it does not show extremely high hydrogenation activity for large-volume polymeric substances. This is an unexpected new finding. The reason for such results is presumed to be that the special hollow shell structure of the carbon black used in the present invention plays a major role in the hydrogenation reaction activity of large-volume polymeric substances. The carbon used in the present invention can be the above-mentioned special carbon black alone or mixed with the above-mentioned various types of carbon black, but the carbon has a specific surface area of less than 800 m ² /g,
If the DBP oil absorption is less than 250 ml/100 g, the hydrogenation activity is only comparable to that of activated carbon as a conventional hydrogenation carrier. One of the features of the present invention is that when the carbon black of the present invention is used as a carrier, it is more effective than when activated carbon, which is widely used as a catalyst carrier, is used as a carrier.
Surprisingly, the reaction activity is high. Another feature of the carbon black of the present invention is that its particle size is similar to that of general carbon black, and when it is used as a catalyst carrier for the hydrogenation of a conjugated diene polymer, the catalyst metal remains in the polymer after hydrogenation. If the metal does not affect the oxidative deterioration of the polymer even if it remains, the carbon black of the present invention as a catalyst and carrier is removed from the hydrogenated polymer solution by centrifugation or other suitable separation means after hydrogenation. There is no need for further separation. Therefore, after completion of hydrogenation, the polymer can be coagulated by adding a poor solvent without separating the carrier-supported catalyst from the hydrogenated polymer solution; steam stripping method; direct drying using an extrusion dryer, rotating drum, etc. Since the hydrogenated polymer containing the catalyst supported on a carrier can be separated and recovered by a method or the like, the hydrogenation process can be greatly simplified. It goes without saying that the hydrogenated polymer thus produced has the same properties as the hydrogenated polymer from which the carrier-supported catalyst has been separated and removed. The metal supported on the carrier may be any metal that exhibits hydrogenation activity, and examples thereof include iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. One type of these may be used or two or more types may be used in combination. The amount of metal supported on the carrier is appropriately selected from the range of 0.001 to 30% by weight per carrier, but preferably 0.01% by weight.
~10% by weight. The method of supporting the catalytic metal etc. on the carrier can be carried out by any usual method and is not limited in any way. The carbon black carrier can be supported by immersing it in an aqueous solution of salts such as chlorides and carbonates, an aqueous acid solution, and the like. The conjugated diene polymer used in the present invention includes 1,3-butadiene, 1,3-butadiene and 1,3-butadiene as polymer components.
- Polymers made of conjugated diene monomers such as pentadiene, isoprene, chloroprene, etc. alone or copolymerized, or copolymerized with conjugated diene monomers and other monomers that can be copolymerized with them, from liquid to Even high molecular weight polymers are included. Specifically, polybutadiene, polyisoprene, styrene-butadiene (random and block) copolymers, acrylonitrile-butadiene (random and alternating)
copolymers, isoprene-styrene (random and block) copolymers, isoprene-butadiene copolymers, isoprene-isobutylene copolymers,
Examples include 1,3-pentadiene polymer. These polymers or copolymers may be produced by any polymerization method such as emulsion polymerization, solution polymerization, or bulk polymerization. Good results are usually obtained when the hydrogenation reaction is carried out in a solution state by dissolving the polymer in a solvent. The concentration of the polymer solution is 1-70% by weight, preferably 1-40% by weight.
It is. There are no particular restrictions on the solvent 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, and the like are 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 200°C, preferably between 20 and 150°C.
It is. 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
The above is not practical from the standpoint of equipment and operation. The polymer hydrogenated by the method of the present invention has excellent weather resistance, ozone resistance, heat resistance, cold resistance, etc., and can be used in a wide range of fields. Example 1 KETJENBLACKE.C., a product of AKZO, was used as the carrier of the present invention. MCC, FEC, MPC, and SRF were used as comparative carbon blacks. The characteristics of each are listed in Table 1. The results using activated carbon are also shown as a comparative example. 1% by weight of Pd or Rh was supported on the carrier. These carrier-supported catalysts were prepared by immersing carbon black in an aqueous solution of PdCl ₂ or RhCl ₃ and reducing it with formalin and caustic soda in accordance with a conventional method for preparing activated carbon-supported catalysts. Acrylonitrile-butadiene copolymer (amount of bound acrylonitrile
An acetone solution (concentration 15%) of 39.4% by weight, ML _1+4,100 °C = 53) and 3 parts by weight of the above-mentioned carrier-supported catalyst per 100 parts by weight of the polymer were charged into an autoclave, and the autoclave was purged with nitrogen, and then the hydrogen pressure was 35Kg/cm. ^2. Hydrogenation reaction was carried out at 60°C for 8 hours. The results are shown in Table 1.

【table】

[Table] Example 2 Polybutadiene (cis-1,4 content 98%, ML _1+4,100 ℃ = 40), styrene-butadiene copolymer (bonded styrene content 23.5% by weight,
ML _1+4,100 ℃=50) and polyisoprene (cis-1,4 content 98%, ML _1+4,100 ℃=80),
Each polymer was dissolved in cyclohexane to a concentration of 10% by weight. CF type carbon black used in Example 1 1% by weight of each of the various carbon blacks and activated carbon used as a comparative example
Pd was supported. Hydrogenation was carried out at 90° C. for 8 hours using a carrier-supported catalyst amount of 3 parts by weight/100 parts by weight of polymer and a hydrogen pressure of 45 kg/cm ² . The results are shown in Table 2.

[Table] Example 3 A solution of the acrylonitrile-butadiene copolymer rubber hydrogenated using Pd in Example 1 as a catalyst and KETJENBLACK EC as a carrier was divided into two parts. One was diluted with a large amount of acetone and the carrier-supported catalyst was separated using a centrifugal separator. Steam was then directly blown into the polymer solution to obtain crumbs, which were dried under reduced pressure (Sample No. 1). On the other hand, water vapor was blown into the polymer solution without separating the carrier-supported catalyst, and the hydrogenated polymer was recovered in the same manner as above (Sample No. 2). These two types of hydrogenated rubbers were mixed with various compounding agents on a roll according to the formulations shown in Table 3 to obtain respective rubber compounds. The reinforcing carbon black was added by subtracting the amount of carbon black carrier remaining in the hydrogenated rubber from the total amount of carbon black. A vulcanizate was prepared by press-curing this at 155°C for 20 minutes. Physical properties conformed to JIS K6301. The results are shown in Table 4. Table 3 (Composition) Hydrogenated copolymer rubber 100 (parts by weight) Stearic acid 1 Zinc oxide 5 Sulfur 0.5 FEF carbon black 40 Tetramethylthiuram disulfide
2 Cyclohexylbenzothiazylsulfenamide 1 N-phenyl-N-isopropyl-p-phenylenediamine 1 Alkylated diphenylamine 1

[Table] In the table, sample number 3 is the case where the catalyst supported on the carrier is separated, and sample number 4 is the case where it is not separated.
This result shows that even if the carbon black carrier of the present invention remains in the hydrogenated rubber, it does not affect the vulcanized physical properties.

Claims (1)

[Claims] 1. When hydrogenating using a hydrogenation catalyst in which the carbon-carbon double bond of a conjugated diene polymer is supported on a carrier, the specific surface area of the carrier is at least 800
m ² /g and DBP oil absorption of at least 250ml/100g
A method for hydrogenating a conjugated diene polymer, characterized by using carbon black.