JPH0621885B2 - Diffusion processing device for synthetic resin objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a monomer gas generated by a monomer gas generating means is brought into contact with a synthetic resin object in a diffusion chamber of a diffusing means so that the synthetic resin object has the above-mentioned unit amount. The present invention relates to a synthetic resin object diffusion processing device adapted to diffuse a body.

The transparent rod whose refractive index distribution is represented by the following formula (A) exhibits a convex lens action, and the light flux traveling in this transparent rod is meandering along the central axis. The period L is expressed by the following equation (B). Here, n ₀ is the refractive index on the central axis, n (r) is the refractive index at a point r from the central axis, and A is a positive constant (refractive index distribution constant).

When the refractive index distribution is expressed by the following equation (C), it exhibits a concave lens action. Where B is a positive constant (refractive index distribution constant)
Is.

Japanese Patent Publication No. 52-5857 (hereinafter referred to as Patent Application 1) and Japanese Patent Laid-Open No. 51-16394 (hereinafter referred to as Patent Application 2).
JP-B-56-37521 (hereinafter referred to as Patent Application 3) and JP-A-57-182702 (hereinafter referred to as Patent Application 4), a crosslinking monomer Ma is partially polymerized. The transparent gel object of the reticulated polymer thus obtained, the monomer Mb forming a polymer having a refractive index different from that of the reticulated polymer is diffused from the transparent gel object surface in a liquid phase or a gas phase. A method for producing a synthetic resin optical transmission medium in which the refractive index continuously changes from the surface toward the inside by performing polymerization after or simultaneously with diffusion is disclosed.

In the methods of the above patent applications 1 and 2, the transparent gel object is dipped in the liquid monomer Mb and the monomer Mb is directly contacted with the surface of the transparent gel object. The method is as follows. There are some drawbacks.

That is, since the polymerization initiator contained in the transparent gel body is eluted into the monomer Mb phase with the lapse of immersion time, the polymerization gradually occurs also in the monomer Mb phase. And the outer peripheral surface of the transparent gel body taken out from the monomer Mb phase after finishing the immersion, when the immersion temperature is high, a layer of the monomer Mb which became viscous by partial polymerization adheres Therefore, it is difficult to remove the layer of the monomer Mb without damaging the transparent gel object. Therefore, during the subsequent heat treatment step performed for polymerization, the monomer Mb diffuses inside the transparent gel object, which causes an undesired distortion of the refractive index distribution in the vicinity of the outer periphery of the light guide. Becomes When the immersion temperature is low, the monomer Mb diffused in the transparent gel object is evaporated from the outer peripheral surface of the transparent gel object during the heat treatment step, and this is the refractive index distribution near the outer peripheral portion of the light transmission body. This causes an increase in undesired distortion of.

Further, in the method of the above patent application 3, the transparent gel object is a monomer.
The above disadvantages are eliminated because the Mb vapor is only exposed to the vapor, but the vapor pressure of the monomer Mb decreases, so that it becomes difficult to manufacture an optical transmission body.

The following methods have been proposed by the present inventors as a method for continuously producing the synthetic resin light transmitter. That is, as shown in FIG. 1, first, a viscous fluid (prepolymer fluid) obtained by prepolymerizing the crosslinkable monomer Ma until just before gelation is put into the extruder (1). Next, the prepolymer fluid is fed from the extruder (1) through the circular tube (2) into the polytetrafluoroethylene tube (4) penetrating the center of the molding tool (3). Since the molding tool (3) has a temperature gradient such that the temperature gradually increases from the bottom to the top, the prepolymer fluid moves upward in the polytetrafluoroethylene tube (4). As a result of progressive polymerization during this, a transparent gel object (5) emerges from the upper end of the molding tool (3). Next, this transparent gel object (5) is introduced into the diffusion tube (6), in the diffusion chamber (7), a monomer that forms a polymer having a refractive index different from that of the transparent gel object (5). The body Mb is diffused inside the transparent gel object (5). Next, the transparent gel object (5) that has completed the diffusion is guided by the heater (8) into the heat treatment tube (9) heated to a predetermined temperature. Polymerization of the transparent gel object (5) is completed while being transferred upward in the heat treatment tube (9), and is taken out, and the refractive index is continuously changed from the surface toward the inside through the mouth (10). The resin light transmitter (11) is continuously obtained. The synthetic resin optical transmission body (11) is transferred upward by the pulling motors (12) and (13) provided above the take-out port (10).
This is done by rotating the pulleys (14) and (15) directly connected to the shaft of (13).

The method of diffusing the monomer Mb in the vapor phase state into the transparent gel object as described above has the following advantages.

That is, first, since the monomer Mb can be diffused at a high temperature in the gas phase, the monomer Mb is polymerized and immobilized while diffusing inside the transparent gel object. Therefore, the monomer Mb diffused inside the transparent gel object,
Evaporation from the outer peripheral surface of the transparent gel body does not occur during the subsequent heat treatment step performed for polymerization. Therefore, the distortion of the refractive index distribution near the outer peripheral portion of the obtained optical transmission body becomes small, and the range having the desired refractive index distribution can be expanded to the vicinity of the outer peripheral portion. Secondly, the monomer Mb not only comes into contact with the transparent gel object in a gas phase state, but since it is not necessary to add a polymerization inhibitor if the supply rate of the monomer Mb is adjusted, The monomer Mb can be repeatedly used, and the recovery rate of the monomer Mb can be increased.

As a diffusion treatment device for diffusing the monomer Mb in the vapor phase inside the transparent gel object, a diffusion tube as shown in FIG.
(6) (see FIG. 1) has been proposed by the present inventors. In this diffusion tube (6), the heater provided on the outer circumference
The liquid monomer Mb (18) is stored in the storage chamber (17) which is heated to a predetermined temperature by energizing (16). The monomer Mb (18) is introduced into the storage chamber (17) through the inlet (19), and the surplus is discharged outside through the outlet (20). The gas generation of the monomer Mb is caused by the above-mentioned monomer Mb.
This is performed by vaporizing the monomer Mb (18) by feeding nitrogen gas supplied from one end (21a) of the nozzle (21) into (18). The generated monomer Mb gas is introduced into the diffusion chamber (22) as shown by arrow A, and the rod-shaped transparent gel object is being transferred in the diffusion tube (6) in the direction of arrow B.
By bringing the gas of the monomer Mb into contact with the surface of (5), the monomer Mb is allowed to diffuse inside the transparent gel body (5).

In addition, hot water (25) that enters from the inlet (23) and exits from the outlet (24) is flown around the outer periphery of the diffusion pipe (6), and the diffusion chamber (2
2) can be maintained at a predetermined temperature. The diffusion chamber (22) is also evacuated from the outlet (26) by an external vacuum pump (not shown).
Further, a molding tool (3) is attached below the diffusion tube (6), and molded from the upper end of the polytetrafluoroethylene tube (4) penetrating the center of this molding tool (3) into a rod shape. The transparent gel object (5) that has been pressed is pushed out.

The diffusion tube (6) has the following drawbacks. That is, first, by introducing nitrogen gas into the monomer Mb (18) from the nozzle (21) in a state where the monomer Mb (18) stored in the storage chamber (17) is heated. Then, since the monomer Mb (18) is vaporized, when the gas of the monomer Mb is heavier than the nitrogen gas, the concentration of the gas of the monomer Mb in the lower part of the diffusion chamber (22). Becomes higher, and as a result, the monomer Mb is deposited on the upper end of the polytetrafluoroethylene tube (4). The deposited monomer Mb is polymerized with the passage of time, which causes the roundness of the transparent gel object to be reduced. Therefore, the axial symmetry of the refractive index distribution of the synthetic resin optical transmission body manufactured continuously is adversely affected. Secondly, when the amount of the monomer Mb deposited on the upper end of the polytetrafluoroethylene tube (4) is further increased, the transparent gel object (5) contains not only liquid monomer Mb but also liquid. Since the monomer Mb also diffuses from the phase-state monomer Mb, the amount of the monomer Mb diffused inside the transparent gel object (5) varies with the passage of time. Therefore, it becomes difficult to continuously manufacture a synthetic resin optical transmission body having uniform optical performance. Third, since the location where the monomer Mb is vaporized and the location where it is diffused are substantially the same, it is difficult to measure the gas concentration of the monomer Mb precisely, and the diffusion conditions must be accurate. It is difficult to grasp.

An object of the present invention is to provide a diffusion treatment device for a synthetic resin object such as a transparent gel object from which the above-mentioned drawbacks have been eliminated.

That is, the synthetic resin object diffusion processing apparatus according to the present invention is configured such that the monomer gas generated by the monomer gas generating means is brought into contact with the synthetic resin object in the diffusion chamber of the diffusing means. In the diffusion treatment device of the synthetic resin object to diffuse the monomer, the monomer gas generating means and the diffusion means are configured separately from each other, the monomer gas generating means, A first container capable of maintaining and storing the monomer liquid at a low temperature, a second container capable of maintaining and storing the monomer liquid at a high temperature, the first container and the second container Circulation means for circulating the liquid of the monomer between them, and inert gas supply means for supplying an inert gas into the liquid of the monomer in the second container to generate the monomer gas And are respectively provided in the second container of the monomer gas generating means. The monomer gas is acceptable to provide the introducing means for introducing into the diffusion chamber of the diffusion means. By doing so, the monomer can be uniformly and continuously diffused into the synthetic resin body.

An embodiment in which the synthetic resin object diffusion processing apparatus according to the present invention is applied to the synthetic resin optical transmitter manufacturing apparatus shown in FIG. 1 will be described below with reference to the drawings.

As shown in FIG. 3, the diffusion treatment device (31) comprises a diffusion pipe (32) as a diffusion means and a monomer gas generator (33) as a monomer gas generation means. The diffusion treatment device (31) can be attached to the synthetic resin optical transmitter manufacturing apparatus by attaching the diffusion pipe (32) instead of the diffusion pipe (6) shown in FIG. I'm running. Further, the transparent gel object (34) to be diffused is transferred in the direction of arrow C on the central axis of the diffusion tube (32), and the diffusion tube (32) is introduced from the inlet (35) at the lower end of the diffusion tube (32). ) Enter the diffusion tube (32)
It's like going out through the exit (36) at the top of the.

A molding tool (37) is attached below the diffusion tube (32), and is molded into a rod shape from the upper end of a polytetrafluoroethylene tube (38) penetrating the center of the molding tool (37). The transparent gel object (34) is extruded. An outlet (39) is provided at the bottom of the diffusion pipe (32), and a vacuum pump (41) is provided at the other end of the exhaust pipe (40) attached to the outlet (39). There is. A cold trap (42) is attached in the middle of the exhaust pipe (40). The diffusion chamber (43) is evacuated by the vacuum pump (41) through the exhaust pipe (40) and the gap (44). The outer periphery of the diffusion chamber (43) is the entrance
The diffusion chamber (43) can be maintained at a predetermined temperature by being warmed by hot water (47) entering from the (45) and exiting from the outlet (46).

Further, conduits (48) (49) are attached to the upper part of the diffusion pipe (32). In the middle of this conduit (48) is a valve (50)
Is installed and the conduit (50) is open.
Nitrogen gas supplied from one end of (48) can be introduced into the upper chamber (52) through the conduit (48) and the gap (51). By thus introducing the nitrogen gas into the upper chamber (52), it is possible to prevent oxygen gas or the like from entering the diffusion chamber (43). Also, a valve (5
3) is provided, the monomer gas supplied from the monomer gas generator (33) connected to the other end of the conduit (49) with the valve (53) opened is It can be introduced into the diffusion chamber (43) through the (49), the introduction port (54) and the gap (55). In addition, a thermometer (76) is provided above and below the diffusion tube (32).
(77) and (78) are attached respectively so that the temperature of each part can be measured.

On the other hand, a supply pipe (56) for supplying the monomer Mb to be diffused is attached to the upper part of the monomer gas generator (33), and is provided in the middle of this supply pipe (56). Valve
With the (57) open, the supply port (56a) at the top of the supply pipe (56)
Therefore, the monomer Mb can be supplied into the storage chamber (58). A cooling pipe (59) is provided on the outer periphery of the storage chamber (58), and the storage chamber (58) is kept at a temperature of, for example, 10 [° C.] by the cooling water flowing through the cooling pipe (59). ] It has become possible to cool to a degree. There is also a pipe (60) at the bottom of the storage chamber (58).
Of the monomer Mb in the storage chamber (58) with the valve (61) provided in the middle of the pipe (60) open.
Can be supplied from the tip (60a) of the pipe (60) into the storage container (62) as the first container. This storage container
The cooling water (62) is maintained in the cooling pipe (63) provided on the outer periphery of the cooling pipe (62) at, for example, about 10 ° C.

Further, this storage container (62) is provided with conduits (64) (65) (66).
It is connected to a storage container (67) as a second container. A pump (68) is provided in the middle of the conduit (65), and by this pump (68), for example, the liquid of the monomer Mb in the storage container (67) is transferred into the storage container (62). I am getting to get it. Further, the storage container (67) can be heated to about 30 to 100 ° C. by energizing the heater (69) provided on the outer circumference. When polyfluoromethyl methacrylate (3FMA) is used as the monomer Mb, the storage container (67) may be heated to 70 to 80 ° C. Furthermore, the tip of the monomer is
A bubble generator (71) as an inert gas supply means located in the Mb (70) is provided, and this valve generator (7
One end (7) of the pipe (73) connected to the (1) via the valve (72).
The nitrogen gas supplied from 3a) can be introduced into the monomer Mb (70) from a large number of pores provided in the bubble generator (71). Further, the gas of the monomer Mb generated in the storage container (67) is also supplied to the diffusion chamber (43) of the diffusion pipe (32) from the outlet (74) through the conduit (49). I'm running.
In addition, a flow meter is installed in the conduit (49) adjacent to the storage container (67).
(75) is attached so that the flow rate of gas flowing through this conduit (49) can be measured.

Next, a method for diffusing the monomer Mb in the rod-shaped transparent gel object (34) using the diffusion processing device (31) configured as described above will be described.

In Fig. 3, first, the supply pipe with the valve (57) opened
After injecting a predetermined amount of liquid monomer Mb from the upper end (56a) of (56), the valve (57) is closed. Valve at this point (61)
Is closed and the liquid of the injected monomer Mb is stored in the storage chamber (58). After cooling the liquid of the monomer Mb to about 10 [° C.] in the storage chamber (58), open the valve (61) to open the pipe.
The liquid of the monomer Mb is introduced into the storage container (62) from the tip (60a) of the (60). The liquid of the monomer Mb gradually accumulates in the storage container (62), and when the liquid level becomes approximately the same as the height of the conduit (64), the inside of the storage container (67) passes through the conduit (64). The liquid of the monomer Mb begins to flow into the storage container (62) after a while.
The liquid level of the liquid of the monomer Mb in (67) is almost the same.
At this point, close the valve (61) slightly and let the tip (60) of the tube (60)
The state where the solution of the monomer Mb is dripped little by little from a). In addition, the storage container (62) is set to about 10 ° C in advance, and
Keep (67) at about 80 ° C.

Then, by starting the pump (68), the storage container (6
The liquid of the monomer Mb in 7) begins to be transferred into the storage container (62) via the conduit (65). When the pump (68) is started, the height of the liquid level of the liquid of the monomer Mb in the storage container (67) becomes low, and the liquid of the liquid of the monomer Mb in the storage container (62) becomes low. Although the height of the surface becomes higher, part of the liquid of the monomer Mb in the storage container (62) is a conduit.
Since it flows again into the storage container (67) through the (64), there is not much difference in the liquid level of the liquid of the monomer Mb in the storage containers (62) and (67). In steady state, the tip (60a) of the tube (60)
While the liquid of the monomer Mb is being dropped from the storage container
(62) While maintaining the liquid level of the monomer Mb liquid in (67) substantially the same, circulate the monomer Mb liquid between these storage containers (62) (67). be able to. Since the upper portions of the storage containers (62) (67) are connected to each other by a conduit (66), a space not filled with the liquid of the monomer Mb in these storage containers (62) (67). The pressure difference between (62a) and (67a) prevents a difference in the liquid level of the liquid of the monomer Mb in the storage containers (62) and (67). In this way, the storage container (62) (6
By circulating the liquid of monomer Mb between 7),
The liquid of the monomer Mb is prevented from polymerizing in the storage container (67) maintained at a high temperature of about [° C.]. The amount of the monomer Mb dropped from the tip (60a) of the tube (60) is
The selection is made so as to supplement the monomer Mb that is consumed by vaporization in the storage container (67), but is actually performed as follows. That is, if the diameter of the pipe (60) is selected to be appropriately small, the liquid level of the liquid of the monomer Mb in the storage container (62) will decrease and
When it is about to separate from the tip (60a) of (60), this tip (60a)
Since air enters into the pipe (60) from the pipe, the liquid of the monomer Mb is automatically supplied from the pipe (60) into the storage container (62).

Next, when the liquid level of the liquid of the monomer Mb in the storage container (62) (67) and the liquid temperature become stable, the pipe (73) with the valve (72) opened.
Introduce nitrogen gas from one end ((73a) of bubble generator
This nitrogen gas is sent into the monomer Mb (70) from (71). As a result, the monomer Mb is vaporized, and the storage container (67) is filled with the mixed gas of the monomer Mb gas and the nitrogen gas. This mixed gas flows from the outlet 74 through the conduit (49) to the diffusion pipe (32).
To the inside of the diffusion chamber (43) through the inlet (54) and the gap (55). The mixed gas thus supplied into the diffusion chamber (43) flows downward in the space (43b) between the side wall (43a) of the diffusion chamber (43) and the transparent gel object (34). The air is exhausted by the vacuum pump (41) through the gap (44), the outlet (39) and the exhaust pipe (40). While the mixed gas flows downward in the space (43b), the gas of the monomer Mb contained in the mixed gas is transferred in the direction of arrow C to the transparent gel body (34). By contacting the surface, the monomer Mb diffuses inside the transparent gel body (34). The diffusion chamber (43) is filled with warm water (47) to form a storage container.
It is maintained at the same or higher temperature than the heating temperature in (67). This temperature is, for example, the above-mentioned 3 as the monomer Mb.
When FMA is used, the temperature may be about 80 ° C. During diffusion, nitrogen gas is supplied from one end (48a) of the conduit (48) as described above, and the upper chamber (52) is passed through this conduit (48).
Nitrogen gas is introduced into the pipe, but the flow rate of this nitrogen gas is
The flow rate of the mixed gas flowing through (49) is kept about 10 times.

In the above embodiment, the monomer gas generator (33) and the diffusion pipe (32) are separated from each other, and these monomer gas generators (3
3) and the diffusion pipe (32) are connected to each other by a conduit (49). Therefore, by appropriately selecting the flow rate of the nitrogen gas supplied to the bubble generator (71) and the temperature of the storage container (67), the concentration of the gas of the monomer Mb generated in the storage container (67) is set. After adjusting to a predetermined concentration, the gas of the monomer Mb can be sent to the diffusion pipe (32). Therefore, in the diffusion chamber (43), it is possible to diffuse into the transparent gel object (34) under a gas atmosphere of the monomer Mb having a predetermined concentration. Also Reservoir (67)
Separately, a storage container (62) that can be maintained at a low temperature is provided, these storage containers (62) (67) are connected to each other by conduits (64) (65), and a pump (65) is provided in the middle of the conduit (65). By providing 68), since the liquid of the monomer Mb in these storage containers (62) (67) is circulated, as described above, the storage container (6
Of course, the polymerization of the monomer Mb in 7) can be prevented, and the tube (60)
The amount of monomer Mb supplied from the tip (60a) of the
6) Monomer Mb consumed by vaporization in
If it is selected to supplement the monomer in the storage container (62) (67),
The height of the liquid surface of the Mb liquid can be kept constant. Therefore, since the amount of the gas of the monomer Mb generated in the storage container (67) can be kept constant over time, the transparent gel object (34)
Even in the case of continuously diffusing the monomer Mb into the, it is possible to always supply a constant amount of the gas of the monomer Mb into the diffusion chamber (43), and as a result, the length of the transparent gel object (34). Uniform diffusion can be performed along the direction. Therefore, it is possible to continuously manufacture the synthetic resin optical transmission body having uniform optical performance along the length direction.

Further, since the inside of the diffusion pipe (32) is exhausted by the vacuum pump (41), the monomer Mb does not deposit on the upper end of the polytetrafluoroethylene tube (38). Therefore, as described above, the roundness of the transparent gel object (34) does not decrease, and the diffusion does not occur unevenly along the length direction of the transparent gel object (34).

Furthermore, of the gas of the monomer Mb introduced into the diffusion tube (32), the portion that was not used for diffusion to the transparent gel object (34) was stored in the diffusion tube (32) by the vacuum pump (41). Since it is trapped by the cold trap (42) while being exhausted to the outside, the monomer Mb can be repeatedly used by recovering the trapped monomer Mb.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made based on the technical idea of the present invention. For example, in the above-described embodiment, the storage containers (62) and (67) have the same volume, but the storage container (62) may have a larger volume than the storage container (67). Further, the number of conduits connecting the storage containers (62) (67) to each other may be three or more.
Further, in the above-described embodiment, the liquid of the monomer Mb was transferred from the storage container (67) to the storage container (62) by the pump (47), but it may be transferred in the opposite direction as necessary. May be.
The gas generated from the bubble generator (71) does not have to be nitrogen gas, but may be another inert gas such as argon or helium. In the above examples, the case of diffusing the monomer Mb into the transparent gel object has been described.
It is obvious that the synthetic resin object diffusion processing apparatus according to the present invention can be used for other synthetic resin objects.

As described above, according to the diffusion processing apparatus for a synthetic resin object according to the present invention, a predetermined amount of monomer gas is temporally stabilized in the monomer gas generation means provided separately from the diffusion means. Since the generated monomer gas can be introduced into the diffusing means quantitatively through the introducing means, the monomer is uniformly and continuously distributed along the length direction of the synthetic resin object. Can be diffused.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a synthetic resin optical transmission device manufacturing apparatus to which a synthetic resin object diffusion processing apparatus according to the present invention is applied, FIG. 2 is a vertical sectional view of a conventional diffusion processing apparatus, and FIG. It is sectional drawing of the diffusion processing apparatus of the synthetic resin object which concerns on invention. In the symbols used in the drawings, (5) (34) …… Transparent gel object (6) …… Diffusion tube (7) (22) (43) …… Diffusion chamber (18) (70) …… Monomer Mb (31) …… Diffusion treatment device (32) …… Diffusion tube (diffusion means) (33) …… Monomer gas generator (monomer gas generation means) (49) …… Conduit (introduction means) ( 62) …… Storage container (first container) (64) (65) …… Conduit (67) …… Storage container (second container) (68) …… Pump (71) …… Bubble generator Active gas supply means).

Claims (2)

[Claims] 1. A method for diffusing the monomer into the synthetic resin body by bringing the monomer gas generated by the monomer gas generating means into contact with the synthetic resin body in the diffusion chamber of the diffusing means. In the diffusion processing device for synthetic resin objects,
The monomer gas generating means and the diffusing means are configured to be separated from each other, and the monomer gas generating means includes a first container capable of keeping the liquid of the monomer at a low temperature and storing it. A second container capable of storing the liquid of the quantity and maintaining it at a high temperature;
Means for circulating the liquid of the monomer between the container and the second container, and a monomer by supplying an inert gas into the liquid of the monomer in the second container. An inert gas supply means for generating a gas, respectively, for introducing the monomer gas generated in the second container of the monomer gas generation means into the diffusion chamber of the diffusion means. An apparatus for diffusing synthetic resin objects, characterized in that introduction means is provided. 2. The diffusion treatment apparatus for synthetic resin objects according to claim 1, wherein the volume of the first container is not smaller than the volume of the second container.