Process for producing a hydrogenated polymer

Details Process for producing a hydrogenated polymer Process for producing a hydrogenated polymer

2002-03-14

2003-05-06

Lipman, Bernard (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S327900, C525S328800, C525S328900, C525S326600, C525S339000

Reexamination Certificate

active

06559241

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field Of The Invention
The present invention relates to a process for producing a hydrogenated polymer having a hydroxy group and/or a functional group which is convertible into a hydroxy group or into a hydroxymethyl group.
2. Description Of The Background
An olefinic polymer having at least one functional group and olefinic carbon—carbon double bonds, an example of which is polybutadienediol, has property insufficiencies such as low heat resistance and unacceptable weatherability. However, hydrogenation of such an olefinic polymer removes the sites of unsaturation in the polymer thereby improving these properties of the polymer.
The hydrogenation of a polymer can be accomplished using various metal catalysts, such as nickel catalysts, palladium catalysts, platinum catalysts, titanium catalysts and rhodium catalysts. Among the processes for the hydrogenation of a polymer, the technique of using a supported catalyst in which the active metal is supported on a carrier is useful because the catalyst can be easily removed from the reaction mixture after hydrogenation. Useful techniques of hydrogenating such polymers containing carbon—carbon double bonds and a hydroxy group in the presence of a supported catalyst include the following:
[1] U.S. Pat. No. 3,994,868 (hereinafter abbreviated as “document 1”) discloses a process in which a hydroxylated polybutadiene is hydrogenated with ruthenium on carbon or ruthenium on alumina.
[2] Japanese Patent Publication No. Sho 61-36002 (JP-B 86-36002) [hereinafter abbreviated as “document 2”] discloses a process in which a hydroxylated polybutadiene is hydrogenated with a metal catalyst such as ruthenium or palladium on a porous carbon support.
[3] U.S. Pat. No. 5,378,767 (hereinafter abbreviated as “document 3”) discloses a process in which a polybutadienediol having a molecular weight of 2,000 is hydrogenated with a catalyst of palladium on&agr;-alumina.
Document 1 discloses that a ruthenium catalyst can produce a hydrogenated polymer at high hydrogenation ratio without the elimination of the terminal hydroxy group. However, it has now been found that a hydrogenation process using ruthenium on a carrier detrimentally involves elution of ruthenium from the catalyst which reduces the stability of the hydrogenated polymer. The patent also discloses, as “Comparative Examples”, a process in which a hydroxylated polybutadiene is hydrogenated with other metal catalysts such as palladium on carbon, rhodium on carbon, osmium on carbon, platinum on carbon and nickel-kieselguhr. The patent shows that palladium on carbon and rhodium on carbon may cause the elimination of the hydroxy group and that osmium on carbon, platinum on carbon and nickel-kieselguhr cannot achieve sufficient hydrogenation ratios.
Document 2 also discloses that the ruthenium catalyst can produce a hydrogenated polymer having a high hydrogenation ratio without the elimination of the terminal hydroxy group [see Examples 1 and 2]. However, the elution of ruthenium may be involved which reduces the stability of the hydrogenated polymer. On the other hand, the palladium catalyst can achieve a high hydrogenation ratio of 93%, but it results in the elimination of the hydroxy group [see Example 3].
Document 3 stresses that the hydrogenation process disclosed can avoid the difficulties involved with the removal of metal catalyst residues from the hydrogenated polymer. The patent also discloses that the specific catalyst is selective towards the hydrogenation of hydroxylated polydienes such that very little of the hydroxy group content is lost during the hydrogenation process. However, the present inventors have found that the elimination of the hydroxy group is inevitably involved when the method described in the patent is employed for the hydrogenation of polybutadienes having high molecular weights of 10,000 or more.
A functional group such as hydroxy group can impart to a polymer various good properties such as hydrophilicity, print or paint adhesion properties, heat adhesion properties to other polymers and so on. Therefore a polymer having a functional group is useful, depending on the strength of its properties, for a packaging material, a molding material or other kinds of sheets, films, fibers or coatings, or as a component of a polymer alloy or as a polymer blend.
In case of a hydrogenation of a polymer having a functional group, the functional group is preferably retained through the hydrogenation process.
On the other hand, a high hydrogenation ratio is recommended for the hydrogenation of an olefinic polymer having a carbon—carbon double bond in order to substantially improve the heat resistance and weatherability of the olefinic polymer.
In the case of the hydrogenation of an olefinic polymer having a functional group such as hydroxy group, the elution of a metal component of the catalyst during the hydrogenation process tends to reduce the stability of the hydrogenated polymer. This tendency becomes remarkable, if the olefinic polymer has hydroxy group or an analogous group such as an epoxy group or derivatives of a hydroxy group. In addition, this tendency becomes more remarkable, when the content of hydroxy group or analogous groups in the olefinic polymer grow in number. Therefore, it is safe to avoid use of a ruthenium catalyst, which inevitably involves the elution of ruthenium, for the hydrogenation of an olefinic polymer having a hydroxy group or an analogous group and containing carbon—carbon double bonds.
However, no process has been found for the hydrogenation of an olefinic polymer having a hydroxy group or analogous group and carbon—carbon double bonds using a catalyst other than a ruthenium catalyst at high hydrogenation ratios and without the elimination of the hydroxy group or its analog.
Moreover, in view of industrial requirements, hydrogenation should be able to be performed efficiently. It is necessary to achieve not only a high hydrogenation ratio but also a sufficient hydrogenation rate.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an industrially advantageous process for producing a hydrogenated polymer by the hydrogenation of an olefinic polymer having carbon—carbon double bonds and a hydroxy group and/or a group which is analogous to the hydroxy group with high retention of the functional group, high hydrogenation ratios and good hydrogenation rates.
Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by a method of producing a hydrogenated polymer, comprising:
hydrogenating a polymer having carbon—carbon double bonds and a hydroxy group and/or a functional group which is convertible into a hydroxy group or into a hydroxymethyl group in the presence of palladium on a base activated carbon and/or platinum on a base activated carbon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It has now been discovered that the hydrogenation of an olefinic polymer having carbon—carbon double bonds and a hydroxy group in the presence of a supported palladium catalyst or a supported platinum catalyst, can avoid the problem of the elution of the metal component of the catalyst during hydrogenation. Thus, it has been found that, when palladium on a base activated carbon is used as the catalyst, the hydrogenation of an olefinic polymer having carbon—carbon double bonds and a hydroxy group proceeds with much less elimination of the hydroxy group and does not adversely affect the rate of hydrogenation of the polymer compared to the case in which a conventional palladium catalyst is used as a catalyst. Moreover, it has been found that platinum on a base activated carbon can achieve a similar result. The present invention has been made on these findings and additional studies.
The present invention provides a process for producing a hydrogenated polymer from a polymer having carbon—carbon double bonds and a hydroxy group and/or a functional group which is convertib

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