Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-11-13
2002-12-24
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S079000, C526S087000, C525S192000, C525S233000, C525S234000, C524S555000, C524S565000, C524S566000
Reexamination Certificate
active
06498223
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an unsaturated nitrile-conjugated diene-typed rubber whose content of an unsaturated nitrile monomer unit is high, a rubber composition containing such rubber and process for the productions of the same. A vulcanized rubber obtained by processing the rubber composition can widely be employed in any application requiring good resistance to oils or the like, including hoses such as oil hoses, fuel hoses, gas hoses, brake hoses and the like, covers of such hoses, as well as industrial parts such as packings, gaskets, O-rings, belts, oil seals and the like, parts of aircrafts, ships, automobiles and the like, tire parts or the like such as tire tubes, inner liners and the like, and other components or the like of paper coatings and adhesives.
DESCRIPTION OF THE RELATED ART
An unsaturated nitrile-conjugated diene-typed rubber such as acrylonitrile-butadiene rubber has an excellent oil resistance or the like and has widely been employed as an industrial material such as building materials, automobile parts and the like. Such unsaturated nitrile-conjugated diene-typed rubber, when blended with a styrene-butadiene rubber, an ethylene-&agr;-olefin-based rubber or a polyvinyl chloride or the like, also gives a composition which can be used to give a rubber or resin product whose oil resistance or the like has been improved.
However, a highly polar unsaturated nitrile-conjugated diene-typed rubber, when blended with a polymer whose polarity is small, tends to undergo a reduction in its mechanical strength or the like. While the content of an unsaturated nitrile-conjugated diene-typed rubber required for obtaining a composition having a desired physical property is determined based mainly on the content of the unsaturated nitrile monomer unit, an ordinary product has the unsaturated nitrile monomer unit whose content is not more than about 50 wt % in view of the difference or the like in the reactivity between an unsaturated nitrile and a conjugated diene. Accordingly, a sufficient improvement in the oil resistance or the like of various rubber products or resin products requires a use of a rubber composition containing a large amount of an unsaturated nitrile-conjugated diene-typed rubber, which leads to a problematic reduction in the weather resistance although a resultant product has an improved oil resistance or the like.
As described above, a problematic limitation to the blending ratio between an unsaturated nitrile-conjugated diene-typed rubber and a polymer having especially small polarity is encountered in an attempt to obtain a product having a desirable physical property. An unsaturated nitrile-conjugated diene-typed rubber capable of giving a vulcanized rubber which is well-balanced in terms of various physical characteristics such as the mechanical strength, the oil resistance, the weather resistance, the gas barrier performance and the like, has not been provided yet.
SUMMARY OF THE INVENTION
The present invention is intended to solve the problems described above and thus its objective is to provide an unsaturated nitrile-conjugated diene-typed rubber capable of giving a vulcanized rubber which is well-balanced in terms of the mechanical strength, the oil resistance, the weather resistance, the gas barrier performance and the like, as well as a process for the production of the same, and a rubber composition comprising such unsaturated nitrile-conjugated diene-typed rubber capable of giving a vulcanized rubber which exhibits an excellent processability and preserves the excellent physical characteristics and also has a sufficient flexibility, as well as a process for the production of the same.
The invention is described below.
1. An unsaturated nitrile-conjugated diene-based rubber comprising 55 to 80 wt % of (A) an olefinically unsaturated nitrile monomer unit as a repeating unit and 20 to 45 wt % of (B) a conjugated diene monomer unit as a repeating unit based on 100 wt % of total of the above-mentioned monomer unit (A) and the above-mentioned monomer unit (B), and whose glass transition temperature of the above-mentioned unsaturated nitrile-conjugated diene-based rubber is −15 to 30° C.
2. The unsaturated nitrile-conjugated diene-based rubber according to 1 above wherein weight-average molecular weight of the above-mentioned unsaturated nitrile-conjugated diene-based rubber is 30,000 or more.
3. The unsaturated nitrile-conjugated diene-based rubber according to 1 above wherein the content of the above-mentioned monomer unit (A) is exceeding 60 wt %.
4. A process for the production of an unsaturated nitrile-conjugated diene-based rubber which is constituted of 55 to 80 wt % of (A) an olefinically unsaturated nitrile monomer unit as a repeating unit and 20 to 45 wt % of (B) a conjugated diene monomer unit as a repeating unit based on 100 wt % of total of the above-mentioned monomer unit (A) and the above-mentioned monomer unit (B), and whose glass transition temperature of the above-mentioned unsaturated nitrile-conjugated diene-based rubber is −15 to 30° C., comprising:
a first step for polymerizing using (a) an olefinically unsaturated nitrile monomer in an amount of 60 to 85 wt % and (b) a conjugated diene monomer in an amount of 3 to 10 wt % based on 100 wt % of total of the above-mentioned monomer (a) and the above-mentioned monomer (b) to be supplied,
a second step for continuing polymerization by supplying continuously the above-mentioned monomer (b) in an amount of 50 wt % or more and the above-mentioned monomer (a) in an amount of 50 wt % or less based on 100 wt % of total of remainder of monomers.
5. A process for the production of an unsaturated nitrile-conjugated diene-based rubber which is constituted of 55 to 80 wt % of (A) an olefinically unsaturated nitrile monomer unit as a repeating unit and 20 to 45 wt % of (B) a conjugated diene monomer unit as a repeating unit based on 100 wt % of total of the above-mentioned monomer unit (A) and the above-mentioned monomer unit (B), and whose glass transition temperature of the above-mentioned unsaturated nitrile-conjugated diene-based rubber is −15 to 30° C., comprising:
a first step for polymerizing using (a) an olefinically unsaturated nitrile monomer in an amount of 60 to 85 wt % and (b) a conjugated diene monomer in an amount of 3 to 10 wt % based on 100 wt % of total of the above-mentioned monomer (a) and the above-mentioned monomer (b) to be supplied,
a second step for continuing polymerization by supplying total of remainder of monomers stepwise by the above-mentioned monomer (b) in an amount of 50 wt % or more and the above-mentioned monomer (a) in an amount of 50 wt % or less based on 100 wt % of monomers to be supplied in each step.
6. A rubber composition comprising two kinds of unsaturated nitrile-conjugated diene-based rubbers which are constituted of 55 to 80 wt % of (A) an olefinically unsaturated nitrile monomer unit as a repeating unit and 20 to 45 wt % of (B) a conjugated diene monomer unit as a repeating unit based on 100 wt % of total of the above-mentioned monomer unit (A) and the above-mentioned monomer unit (B), whose glass transition temperature of the above-mentioned unsaturated nitrile-conjugated diene-based rubbers are −15 to 30° C., and one of which is a high molecular weight rubber whose weight-average molecular weight is 30,000 or more and the other of which is a low molecular weight rubber whose weight-average molecular weight is less than 30,000.
7. The rubber composition according to 6 above further comprising at least one of reinforcing agents selected from the group consisting of silica, aluminium hydroxide and carbon black.
8. The rubber composition according to 6 above wherein the above-mentioned high molecular weight rubber is in an amount of 40 to 95 wt % and the above-mentioned low molecular weight rubber is in an amount of 5 to 60 wt % based on 100 wt % of the total of the above-mentioned high molecular weight rubber and the above-mentioned low molecular weight rubber.
9. The rubber composition ac
Ishikawa Osamu
Sakata Katsuhiko
JSR Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Teskin Fred
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