Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
2001-05-30
2002-10-15
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
Reexamination Certificate
active
06465607
ABSTRACT:
This application is based on Japanese Patent Application No. 2000-181264 filed Jun. 16, 2000, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration damping rubber member capable of exhibiting excellent durability and a method of producing the same, and more particularly to a vibration damping rubber member which contributes to reduction of the weight of automotive vehicles when the vibration damping rubber member is used on the automotive vehicles, and a method suitable for producing such a vibration damping rubber member.
2. Discussion of Related Art
As well known, a vibration damping rubber member interposed between two members in a vibration or shock transmitting system so as to exhibit vibration damping or cushioning characteristics has been widely used in various fields. For instance, the vibration damping rubber member is used on automotive vehicles, as engine mounts, body mounts, cab mounts, member mounts, strut mounts, strut bar cushions, suspension bushings, and so on.
The automotive vehicles on which such a vibration damping rubber member is installed are generally required to have a reduced weight in order to improve fuel economy and to achieve high performance. The vibration damping rubber member used on the automotive vehicles is accordingly required to have a reduced weight.
As one technique for reducing the weight of the vibration damping rubber member interposed between two members in the vibration or shock transmitting system, two supporting or mounting members for supporting the vibration damping rubber member which are attached to the respective two members in the vibration system are formed of an aluminum material or a resin material in place of a conventionally used metallic material. As another technique, the vibration damping rubber member is designed to have a reduced size. In the vibration damping rubber member which is made compact to reduce its weight, the volume (amount) of the rubber is inevitably smaller than that in a conventional vibration damping rubber member. Accordingly, the material used for the vibration damping rubber member whose size is reduced needs to exhibit a considerably high degree of durability for withstanding a vibrational load as large as that applied to the conventional vibration damping rubber member.
DISCLOSURE OF THE INVENTION
The present invention is made in view of the background art described above. It is a first object of this invention to provide a vibration damping rubber member which is capable of exhibiting excellent durability without suffering from deterioration of its spring stiffness.
It is a second object of the invention to provide a method suitable for producing such a vibration damping rubber member.
The first object indicated above may be achieved according to a first aspect of the present invention, which provides a vibration damping rubber member having excellent durability, wherein an improvement comprises: the vibration damping rubber member being obtained by vulcanizing a composition in which an unvulcanized natural rubber material and an unvulcanized acrylic rubber material are evenly mixed together in a proportion of 90/10~60/40 by weight; and fine particles of a vulcanized acrylic rubber having a size of 1~100 &mgr;m and obtained by vulcanization of the unvulcanized acrylic rubber material being dispersed in a matrix phase of a vulcanized natural rubber obtained by vulcanization of the unvulcanized natural rubber material.
The vibration damping rubber member constructed according to the first aspect of the present invention is characterized in that a suitable amount of the fine particles of the vulcanized acrylic rubber obtained by vulcanization of the unvulcanized acrylic rubber material are dispersed in a matrix phase of the vulcanized natural rubber obtained by vulcanization of the natural rubber material. In the thus formed vibration damping rubber member, the acrylic rubber dispersed in the form of the fine particles in the matrix phase of the natural rubber permits even distribution of the load applied to the vibration damping member. Accordingly, the present vibration damping rubber member exhibits significantly improved durability without suffering from deterioration of its spring stiffness (dynamic/static ratio of spring constant).
The vibration damping rubber member of the present invention is obtained by vulcanization of the composition in which the unvulcanized natural rubber material and the unvulcanized acrylic rubber material are mixed in a proportion of 90/10~60/40 by weight. In the formed vibration damping rubber member, the fine particles of the vulcanized acrylic rubber having a size of 0.1~100 &mgr;m and obtained by vulcanization of the unvulcanized acrylic rubber material are dispersed in the matrix phase of the vulcanized natural rubber obtained by vulcanization of the unvulcanized natural rubber material. According to this structure, the vibration damping rubber member effectively exhibits improved durability while assuring physical properties required by the vibration damping rubber member.
The second object indicated above may be achieved according to a second aspect of the present invention, which provides a method of producing a vibration damping rubber member, the method comprising the steps of: preparing an unvulcanized rubber composition by evenly mixing together an unvulcanized natural rubber material and an unvulcanized acrylic rubber material in a proportion of 90/10~60/40 by weight, and adding a vulcanizing agent for vulcanizing the unvulcanized natural rubber material and a vulcanizing agent for vulcanizing the unvulcanized acrylic rubber material; forming a thus obtained mixture into a desired shape; and vulcanizing the formed mixture for obtaining the vibration damping rubber member in which fine particles of a vulcanized acrylic rubber having a size of 0.1~100 &mgr;m and obtained by vulcanization of the unvulcanized acrylic rubber material are dispersed in a matrix phase of a vulcanized natural rubber obtained by vulcanization of the unvulcanized natural rubber material.
The present method of producing a vibration damping rubber member permits the vulcanized acrylic rubber obtained by vulcanization of the unvulcanized acrylic rubber material to be evenly dispersed in the form of the fine particles in the matrix phase of the vulcanized natural rubber obtained vulcanization of the unvulcanized natural rubber. Accordingly, the vibration damping rubber member having a high degree of durability can be advantageously produced according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The vibration damping rubber member according to the present invention constructed as described above is constituted by an intimate mixture of a vulcanized natural rubber and a vulcanized acrylic rubber, which is obtained by vulcanization of a natural rubber material and an acrylic rubber material known in the art. The present vibration damping rubber member is characterized in that the fine particles of the vulcanized acrylic rubber having a size of 0.1~100 &mgr;m are dispersed in the matrix phase of the vulcanized natural rubber.
The unvulcanized natural rubber material and the unvulcanized acrylic rubber material used for forming the present vibration damping rubber member are both polymers which are mutually incompatible. In the vibration damping rubber member obtained by vulcanization of the two unvulcanized rubber materials which ate mixed together in a predetermined proportion, the vulcanized natural rubber and the vulcanized acrylic rubber are not mutually compatible. In the present vibration damping rubber member, the vulcanized acrylic rubber is dispersed, in the matrix phase of the vulcanized natural rubber, in the form of fine particles having a size of 0.1~100 &mgr;m. The fine particles of the vulcanized acrylic rubber dispersed in the matrix phase of the vulcanized natural rubber are effective to distribute and reduce the load applied to the
Iio Shinji
Taguchi Takehiko
Yoshikawa Ako
Boykin Terressa M.
Burr & Brown
Tokai Rubber Industries Ltd.
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