JP2001002729A - Hydrogenated nitrile rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject rubber highly excellent in storage stability prior to producing rubber parts therefrom and useful for automotive parts and industrial rubber parts by hydrogenating the corresponding raw nitrile rubber so that the ratio for the respective peak areas of specific two peaks resulting from an 1H-NMR analysis of the hydrogenated rubber satisfy a specific requirement. SOLUTION: This hydrogenated rubber is such one as to be <=0.06 in the ratio B/A (A and B are the areas of peaks with the tops near 2.5 ppm and 6.1 ppm, respectively, resulting from an 1H-NMR analysis), being obtained by adding a catalyst to an organic solvent solution of the corresponding raw nitrile rubber followed by contacting the resultant solution with an atomic or gaseous hydrogen under heating in a reaction vessel, wherein it is preferable that the catalyst to be used is a metal such as Pt carried on a porous form and the raw nitrile rubber is a copolymer from 50-95 wt.% of a conjugated diene, 5-50 wt.% of an α,β-unsaturated nitrile compound and, if needed, 0-10 wt.% of a monomer copolymerizable therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention provides a hydrogenated nitrile rubber having excellent storage stability. The hydrogenated nitrile rubber obtained by the present invention is used as a raw material for rubber parts for automobiles and other industrial parts. , Can be widely used.

[0002]

2. Description of the Related Art A hydrogenated nitrile rubber obtained by selectively hydrogenating a carbon-carbon double bond in a molecule of a nitrile rubber has heat resistance and weather resistance while maintaining the excellent oil resistance of the nitrile rubber. Therefore, the use thereof is expanding as a rubber member for automobile parts and the like that require these performances.

Although hydrogenation of nitrile rubber improves heat resistance and weather resistance, it is necessary to leave a double bond for inexpensive vulcanization later. This double bond has a defect that physical properties change and deterioration occur during storage due to reactions such as oxidation. It is generally known that metal catalysts used for hydrogenation often promote rubber deterioration,
If a large amount of the metal catalyst is present in the rubber, there is a problem that the processability of the rubber is deteriorated. For that purpose, the method of removing the used catalyst is described in, for example, JP-A-3-210304,
Although proposed in JP-A-4-290555, it is impossible to completely remove the metal catalyst. Further, for this purpose, a method of adding a stabilizer as described in JP-A-3-153706 has been proposed, but changing the compounding is not preferable because the physical properties of the rubber product change. Therefore, it is desired to improve the stability of the rubber itself.

[0004] Deterioration of rubber by a metal catalyst is general, but regarding the double bond structure of hydrogenated nitrile rubber, 1,4-trans vinyl, 1,4-cis vinyl, 1,1, Although there are many descriptions relating to the 2-vinyl structure, those relating to double bonds in the main chain derived from an acrylonitrile unit represented by the following chemical formula (1) are described in, for example, Rubber Chemistry and Technology in 1989, although they are described. The correlation between the residual amount of the double bond in the main chain derived from the acrylonitrile unit and the rubber properties was not clear.

[0005]

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[0006]

DISCLOSURE OF THE INVENTION The present invention has the drawback that double bonds in conventional hydrogenated nitrile rubber molecules cause physical property changes and deterioration during storage due to reactions such as oxidation and the like. The object of the present invention is to simultaneously solve the drawback that the processability of the rubber is deteriorated when present in the rubber, and the drawback that the physical properties of the rubber product change when the compounding is changed by adding the stabilizer.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to improve the storage stability of the hydrogenated nitrile rubber itself, and as a result, have found a means that is extremely excellent in storage stability. Was.

That is, according to the present invention, the ratio of the peak area (A) having a peak top near 2.5 ppm to the peak area (B) having a peak top near 6.1 ppm in 1H-NMR is B / A ≦ B / A. It relates to a hydrogenated nitrile rubber of 0.06.

The present invention relates to a process for hydrogenating nitrile rubber,
This relates to a double bond in the main chain derived from an acrylic monomer unit represented by the following chemical formula (1) which is presumed to be newly generated by isomerization, and the newly generated double bond is determined by 1H-NMR. It can be identified as a peak area having a peak top near 1 ppm.

[0010]

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The present invention will be described in more detail. The starting nitrile rubber used in the present invention is a copolymer of a conjugated diene and an α, β-unsaturated nitrile compound, and if necessary, a monomer copolymerizable therewith. Examples of the conjugated diene include butadiene, isoprene, 1,3-pentadiene and the like, butadiene is preferred. Examples of the α, β-unsaturated nitrile compound include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and the like, with acrylonitrile being preferred.

Other copolymerizable monomers include α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid;
Or esters of α, β-unsaturated carboxylic acids, non-conjugated divinyl compounds such as divinylbenzene, polyvalent (meth) acrylate compounds such as ethylene glycol dimethacrylate, and vinyl monomers having an anilinophenyl skeleton in the molecule Is mentioned. These other monomers copolymerizable with the conjugated diene and the α, β-unsaturated nitrile compound can be used alone or in combination as necessary.

In the raw nitrile rubber used in the present invention, a conjugated diene, an α, β-unsaturated nitrile compound,
The ratio of the other monomer copolymerizable therewith is not particularly limited, but 50 to 95% by weight of a conjugated diene, 5 to 50% by weight of an α, β-unsaturated nitrile compound, and 0% of another monomer copolymerizable therewith. From 10 to 10% by weight is preferable from the balance of physical properties of the hydrogenated nitrile rubber.

As the polymerization method of the raw material nitrile rubber used in the present invention, a general emulsion polymerization method can be adopted.

In the production of the hydrogenated nitrile rubber in the present invention, a metal such as Pt, Pd, Rh, Ru or the like is supported on a porous material such as silica as a catalyst. For example, a solution prepared by dissolving the raw material nitrile rubber in an organic solvent is used. , And contact it with atomic or gaseous hydrogen under heating in a reactor. Furthermore, it is also possible to hydrogenate the above metal in the form of a metal complex in a homogeneous system.However, although there is an advantage that the amount of catalyst used can be reduced, a catalyst removal / recovery step is required, and as a production process, From the viewpoint of complexity, it is preferable to use a supported catalyst. The hydrogenation rate is an index of hydrogenation based on the heat resistance of the obtained hydrogenated nitrile rubber.
Hydrogenated nitrile rubbers of 0 or less are preferred.

Further, the present inventors have found that in the hydrogenation step using a supported catalyst, a double bond in the main chain derived from an acrylic monomer unit is newly generated depending on the reaction conditions,
I found that the amount changed. Even with the same amount of catalyst and the same hydrogenation rate, it was discovered that if the reaction temperature changes, the amount of double bonds in the main chain derived from the acrylic monomer unit changes, and the amount of double bonds in the main chain derived from the acrylic monomer unit changes. It was found that there was a correlation between the amount of double bond and storage stability.
That is, the ratio of the peak area (A) having a peak top near 2.5 ppm to the peak area (B) having a peak top near 6.1 ppm in 1H-NMR is B
It has been found that a hydrogenated nitrile rubber satisfying /A≦0.06 has extremely excellent storage stability.
Storage stability was insufficient.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]

Production Examples 1-3 Raw material nitrile rubbers having the compositions shown in Table 1 were prepared by emulsion polymerization.

[0020]

Example 1 The raw nitrile rubber obtained in Production Example 1 was dissolved in acetone and hydrogenated under the conditions 1 shown in Table 2.
The catalyst was removed from the suspension solution after hydrogenation by centrifugation, and water was added to precipitate a hydrogenated nitrile rubber, followed by drying.

The obtained hydrogenated nitrile rubber was dissolved in deuterated chloroform (5% by weight), and 1H-NMR was measured. The peak area (A) having a peak top at about 2.5 ppm and the peak area (A) at about 6.1 ppm were obtained. When the ratio to the peak area (B) having a peak top is calculated, B / A = 0.04
Nine. Hydrogenation rate is 64% and iodination is 10%
It was one. Next, in order to examine the storage stability, these rubbers were placed in a gear oven and subjected to an acceleration test at 70 ° C. for 3 days and 6 days. The sample rubbers before the acceleration test, 3 days after the acceleration test, and 6 days after the acceleration test were tested. Mooney viscosity of JIS K6
384. Regarding the storage stability, a rubber having a small change in Mooney viscosity even when an accelerated test is performed is an excellent storage stability rubber. The changes in Mooney viscosity are shown in Table 3.

[0022]

Comparative Example 1 The raw nitrile rubber obtained in Production Example 1 was dissolved in acetone and hydrogenated under the conditions 3 shown in Table 2.
The catalyst was removed from the suspension solution after hydrogenation by centrifugation, and water was added to precipitate a hydrogenated nitrile rubber, followed by drying.

The obtained hydrogenated nitrile rubber was dissolved in deuterated chloroform (5% by weight), and 1H-NMR was measured. The peak area (A) having a peak top at about 2.5 ppm and the peak area (A) at about 6.1 ppm were obtained. When the ratio to the peak area (B) having a peak top is calculated, B / A = 0.10
It was 0. The hydrogenation rate is 66% and the iodination is 10%.
It was 0. The storage stability was evaluated in the same manner as in Example 1. Table 3 shows the results.

[0024]

Examples 2, 3, 4, 5 and Comparative Examples 2 and 3 Nitrile rubber was hydrogenated under the raw materials and hydrogenation conditions shown in Table 3. As in Example 1, the catalyst was removed from the suspension solution after hydrogenation by centrifugation, and water was added to precipitate a hydrogenated nitrile rubber, followed by drying. The obtained hydrogenated nitrile rubber was dissolved in deuterated chloroform (5% by weight), and 1H-
NMR was measured. Table 3 shows the ratio of the peak area (A) having a peak top near 2.5 ppm to the peak area (B) having a peak top near 6.1 ppm, B / A, and the hydrogenation rate. . Further, the storage stability was evaluated in the same manner as in Example 1. Table 3 shows the results.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

EFFECTS OF THE INVENTION The hydrogenated nitrile rubber of the present invention is disadvantageous in that double bonds in the prior art molecules cause changes in physical properties and deterioration during storage due to reactions such as oxidation, and a large amount of metal catalyst is contained in the rubber. Is a nitrile rubber that simultaneously solves the disadvantage of deteriorating the processability of the rubber when present, and the method of adding a stabilizer changes the physical properties of the rubber product if the compounding is changed. It is a vulcanizable rubber that is extremely excellent in stability, and because of its ease of handling, it is suitable and widely applied to automotive parts and industrial rubber parts.

Claims (1)

[Claims] 1. A peak area (A) having a peak top near 2.5 ppm in 1H-NMR and 6.1 pp.
A hydrogenated nitrile rubber excellent in storage stability having a ratio of B / A ≦ 0.06 to a peak area (B) having a peak top near m.