Abrading – Flexible-member tool – per se – Laminate
Reexamination Certificate
2000-06-14
2002-09-03
Rachuba, M. (Department: 3723)
Abrading
Flexible-member tool, per se
Laminate
C451S539000, C051S308000
Reexamination Certificate
active
06443827
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polishing member, such as a polishing sheet or a polishing disk, for polishing an end face of an optical fiber connector ferrule, and a process for producing the polishing member.
2. Description of the Prior Art
End faces of optical connector ferrules in which, for example, optical fibers have been inserted and secured have heretofore been polished by utilizing polishing members or polishing slurries. In such cases, since different materials are polished at the end face of the optical fiber connector ferrule, satisfactory polishing results cannot always be obtained in the aspect of optical transfer loss at the end face, or the like.
Specifically, the end face of the optical fiber connector ferrule contains different materials including various kinds of ceramics, such as a glass material, alumina, and zirconia. In order for the optical transfer loss to be prevented, the different materials must be polished uniformly. Particularly, heretofore, it has not always been possible to perform the polishing such that the surface smoothness of the ferrule surface and the optical fiber surface may be kept high, such that a difference in level between the ferrule surface and the optical fiber surface may not occur, and such that the high return loss characteristics may thereby be obtained.
An example of a polishing member has been proposed in, for example, Japanese Unexamined Patent Publication No. 8(1996)-336758. The proposed polishing member comprises a substrate and a polishing layer overlaid on the substrate by applying a coating composition, which comprises a binder and colloidal silica particles dispersed in the binder, the colloidal silica particles having a mean particle size falling within the range of 0.1 &mgr;m to 0.1 &mgr;m.
The polishing member as described above is produced with a coating composition dispersing apparatus, a coating apparatus, a calendering apparatus which may be employed when necessary, a heat treatment apparatus, a slitting apparatus, a wind-up apparatus, and the like.
With the conventional polishing member described above, the colloidal silica particles having a mean particle size falling within the range of 0.01 &mgr;m to 0.1 &mgr;m are dispersed in the polishing layer. Non-colloidal silica particles (un-agglomerated silica particles) having the fine particle size described above have the problems in that they cannot be easily dispersed in the binder and a solvent and, therefore, the coating composition for forming the polishing layer cannot be prepared. Therefore, in the conventional polishing member described above, the colloidal silica particles are utilized. However, the use of the colloidal silica particles is disadvantageous from the view points of the productivity, the cost, and the like.
In cases where fine polishing particles of alumina, or the like, other than silica are utilized, if they have a high Mohs hardness, there is the risk that scratches will occur on the end face of the optical fiber, and a difference in level will occur between the end face of the optical fiber and the end face of the ferrule. In cases where fine polishing particles of alumina, or the like, other than silica, which have a low Mohs hardness are utilized, there is the risk that a high polishing power cannot be obtained, the surface cannot be polished smoothly, and the return loss will become large. In cases where polishing particles having a small mean particle size are utilized, the problems occur in that a high polishing power cannot be obtained, and a long time will be required to perform the polishing. In cases where polishing particles having a large mean particle size are utilized, the problems occur in that flaws (scratches) occur on the polished surface, the surface will become rough and will have a low flatness, and finish polishing with good quality cannot be achieved.
As for techniques for polishing with a polishing slurry, an alkaline polishing slurry has heretofore been utilized. The technique for utilizing the alkaline polishing slurry is effective for lowering the viscosity, but has the problems in that neutralization, and the like, must be performed at the time of waste liquid treatment.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a polishing member, in which dispersibility of fine silica particles is enhanced and which is suitable for polishing an end face of an optical fiber connector ferrule.
Another object of the present invention is to provide a process for producing the polishing member.
The present invention provides a polishing member for use in polishing of an end face of an optical fiber connector ferrule, the polishing member comprising a substrate and a polishing layer, which is overlaid on the substrate and which comprises a binder and fine polishing particles dispersed in the binder,
wherein agglomerated fine silica particles having a mean particle size falling within the range of 0.1 &mgr;m to 4 &mgr;m are utilized as the fine polishing particles contained in the polishing layer, and a thickness of the substrate falls within the range of 25 &mgr;m to 150 &mgr;m.
In the polishing member in accordance with the present invention, the agglomerated fine silica particles, in which fine silica particles have been agglomerated, are utilized directly as the fine polishing particles contained in the polishing layer. The agglomerated fine silica particles have a mean particle size falling within the range of 0.1 &mgr;m to 4 &mgr;m. The agglomerated fine silica particles should preferably have a mean particle size falling within the range of 0.5 &mgr;m to 4 &mgr;m, and should more preferably have a mean particle size falling within the range of 0.9 &mgr;m to 4 &mgr;m. Colloidal silica particles are not utilized as the fine polishing particles contained in the polishing layer.
From the view points of lubrication effects and cooling effects, the polishing with the polishing member in accordance with the present invention should preferably be performed while a polishing liquid, which is constituted of water or a silica slurry, is being supplied onto a surface of the polishing layer. In such cases, the polishing liquid should preferably be free from a base or an acid. In cases where the polishing liquid is constituted of the silica slurry, the silica material contained in the silica slurry should preferably be identical with the silica material of the agglomerated fine silica particles, which are contained in the polishing layer.
In the polishing member in accordance with the present invention, a dry thickness of the polishing layer should preferably fall within the range of 5 &mgr;m to 15 &mgr;m. Also, in the polishing layer, the proportion of the binder per 100 parts by weight of the agglomerated fine silica particles should preferably fall within the range of 30 to 100 parts by weight.
The present invention also provides a process for producing a polishing member for use in polishing of an end face of an optical fiber connector ferrule, the process comprising the steps of:
i) preparing a coating composition for forming a polishing layer, the coating composition comprising agglomerated fine silica particles having a mean particle size falling within the range of 0.1 &mgr;m to 4 &mgr;m, a binder, and an organic solvent,
ii) applying the coating composition onto a substrate having a thickness falling within the range of 25 &mgr;m to 150 &mgr;m, and
iii) drying the applied coating composition to form the polishing layer.
In the process for producing a polishing member in accordance with the present invention, the agglomerated fine silica particles, in which fine silica particles have been agglomerated, are utilized directly as the fine polishing particles contained in the polishing layer. The agglomerated fine silica particles have a mean particle size falling within the range of
0
.
1
&mgr;m to 4 &mgr;m. The agglomerated fine silica particles should preferably have a mean particle size falling within the range of 0.5 &mgr;m to 4 &mgr
Ishiguro Tadashi
Ryoke Katsumi
Fuji Photo Film Co. , Ltd.
Rachuba M.
LandOfFree
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