Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-10-18
2004-09-28
Robertson, Jeffrey B. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S031000, C528S032000
Reexamination Certificate
active
06797797
ABSTRACT:
FIELD OF TECHNOLOGY
The present invention relates to a low cross-linking-density gel used as an optical conductor for connecting end faces of optical fibers, and a method for producing such a gel.
TECHNICAL BACKGROUND
An optical fiber connector, a fixed connecting device, a light combining/splitting device or like device has been generally used to connect end faces of optical fibers.
A mechanical contact method is mainly used to connect end faces of optical fibers in an optical fiber connector. According to this mechanical contact method, ferrules are respectively fitted on cores of both optical fibers and are inserted into fitting holes, which are formed in the opposite side surfaces of a connector main body to communicate with each other in linear alignment with each other, from the opposite sides of the connector main body, and the end faces of the two cores having the ferrules fitted therearound are fixed in abutment against each other to be connected with each other.
Besides the above mechanical contact method, for example, there have been proposed the use of a lens as an optical conductor at a joint portion and the use of a matching oil in the optical fiber connector as disclosed in Japanese Unexamined Patent Publications No. 56-110912 and No. 56-81807, respectively.
On the other hand, matching oil, matching grease, epoxy resin or the like is used as an optical conductor for the connection of optical fibers in a fixed connecting device or light combining/splitting device.
It is basically required in the connection of the optical fibers to maximally eliminate the diffusion of light at the joint portion of the two end faces.
However, according to the method for mechanically bringing the end faces of the optical fibers into contact with each other, an air layer is inevitably present between the end faces due to its mechanical construction. Since this air layer and the cores of the optical fibers have different refractive indices, light is diffused due to a difference in refractive index, resulting in a loss of light.
An arrangement of an optical conductor between the end faces has been proposed and put into practice in order to eliminate the air layer and prevent the loss of light.
However, the prior art method using a lens as the optical conductor necessitates a complicated construction and the use of a large-sized apparatus and has a problem in reliability during the attachment and detachment of the optical fibers. Thus, this method has low industrial applicability.
The prior art method using matching oil as the optical conductor has problems of flow-out and oxidation of the oil resulting from increase and decrease of temperature, and a problem of a short life. Particularly, if silicone oil is used as the matching oil, it is difficult to prevent the silicone oil from flowing out due to its creeping characteristic. Thus, the use of the matching oil compels an exchange of oil after a certain period of time and, therefore, has low industrial applicability.
On the other hand, the method using grease as the optical conductor has been proposed in order to avoid the above problems of flow-out and oxidation of oil. Grease can certainly avoid an undesirable event of flow-out due to its high viscosity, but cannot avoid problems of changes in characteristics caused by temperature and a difference in refractive index between a thickening agent and a composition and has a lower light transmittance as compared to the case where the matching oil is used. Further, grease has a fatal problem of being unable to restore (eliminate) air bubbles produced by a displacement of the two end faces at the Joint portion, Therefore, grease also has low industrial applicability.
According to the prior art method using an epoxy resin as the optical conductor, the epoxy resin is cured by heating or air-cured, and displays a satisfactory performance over a long period of time. However, this method has an unavoidable problem of coloring due to oxidation. In view of operability, mixing of B curing agent, removal of air bubbles, curing by heating, etc. are necessary during the manufacturing process. Further, in the case of defective connection of the end faces, the optical fibers have to be thrown away and the whole process has to be resumed from the beginning. This method is used despite its poor yield, but has low industrial applicability.
In view of the problems residing in the prior art, a main object of the present invention is to provide a low cross-linking-density gel which can effectively suppress the diffusion of light when end faces of cores of optical fibers are connected, and a method for producing such a gel.
It is another object of the present invention to provide a low cross-linking-density gel which effectively suppresses the diffusion of light at a joint portion of end faces of cores of optical fibers, and a method for producing such a gel.
It is still another object of the present invention to provide a low cross-linking-density gel which is free from a flow-out problem even if temperature increases or decreases due to a change in working environments, and a method for producing such a gel.
It is further another object of the present invention to provide a low cross-linking-density gel which can stably suppress the diffusion of light by maintaining its working performance over a long period of time, and a method for producing such a gel.
DISCLOSURE OF THE INVENTION
In order to solve the aforementioned problems and accomplish the above objects, an inventive method for producing a low cross-linking-density gel, comprises:
a compounding step for adjusting a flexible silicone gel material to have a specified refractive index, and
a reaction step for causing the flexible silicone gel material adjusted in the compounding step to cross-link in a binding region where cross-linking density is low, thereby producing a low cross-linking-density gel.
In the inventive method, the specified refractive index is set substantially equal to the refractive index of cores of optical fibers to be connected.
In the inventive method, a polyorganosiloxane having vinyl groups at its ends is used as a primary agent of the flexible silicone gel material.
In the inventive method, a cross-linking agent is added in the reaction step.
In the inventive method, the polyorganosiloxane having covalently bound hydrogen atoms is added as the cross-linking agent.
In the inventive method, the compounding step end the reaction step are performed in a clean room.
Another inventive method for producing a low cross-linking-density gel, comprises:
a compounding step for adjusting a flexible silicone gel material to have a specified refractive index,
a combining step for synthesizing a composition by adding a cross-linking agent to the flexible silicone gel material adjusted in the compounding step,
a filling step for filing the composition into a syringe,
a sealing step for sealing the syringe, and
a reaction step for heating the sealed syringe to cause the composition to undergo an addition reaction in a binding region where cross-linking density is low, thereby producing a low cross-linking-density gel in the syringe.
In the inventive method, the syringe is sealed by mounting a cap in the sealing step.
In the inventive method, the syringe is mounted in a dispenser for dispensing a predetermined amount of the low cross-linking-density gel by replacing the cap mounted on the syringe by a nozzle after the low cross-linking-density gel is produced in the syringe,
Further, an inventive low cross-linking-density gel is produced by causing a flexible silicone gel material adjusted to have a specified refractive index to undergo an addition reaction to cross-link in a binding region where cross-linking density is low.
In the inventive gel, the specified refractive index is set substantially equal to the refractive index of cores of optical fibers to be connected.
In the inventive gel, the flexible silicone gel material is a polyorganosiloxane having vinyl groups at its ends.
In the inventive gel, a cross-linking agent is added prior to t
Naomi Sakai
Takeo Inagaki
Inagaki Takeo
Robertson Jeffrey B.
Uren John Russell
Zimmer Marc
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