JPS61267704A - Production of optical transmission body made of synthetic resin - Google Patents

Abstract

PURPOSE:To produce the titled body having a good stability for long periods by sealing a gap formed between a molding base material and an inner wall of the molding means in the outlet of the molding means with a liquid sealing layer, thereby preventing an additive from invading into the molding means. CONSTITUTION:The prepolymer fluid having a stickiness and usable to the starting material of the optical transmission body made of the synthetic resin is fed in an extruder 1 cooled with a cooling water. The prepolymer fluid is prepolymerized just before gelling a monomer Ma, thereby maintaining a fluidity. And an extruding means (not shown in the figure) is provided in the extruder 1. The prepolymer 10 is extruded by the extruding means followed by continuously feeding to a forming pipe 3 which is passing through a heating jacket 2 composed of a bronze block etc. after extruding the prepolymer. And then, the stainless pipe is drawn up by a pulling up means at the same rate to the extruding rate. The prepolymer 10 attendent on the stainless pipe is continuously formed to the optical transmission body while passing the all producing steps.

Description

[Detailed Description of the Invention] 3.l Industrial Application Field The present invention relates to a method for manufacturing a synthetic resin light transmitting body having a refractive index distribution, and more specifically, a method that enables continuous production of a synthetic resin light transmitting body. Regarding the technology to

3.2 Explanation of Prior Art 0 (1. A transparent rod-like body whose refractive index distribution is represented by the set shown below exhibits a convex lens action, and the index of refraction, n(
r) is the refractive index at a point located at a distance of r from the central axis, and A is a positive constant (refractive index distribution constant).

n(r)-n□ (/-t/21 r2) ...(
1) L-2π/zor (2) When the refractive index distribution is expressed by the following equation (3), a concave lens effect is exhibited. Here, B is a positive constant (refractive index distribution constant).

n(r)=no (/+//2Br2)”...
(3) Tokuko Akira! 2-! Za No. 57 (hereinafter referred to as patent application l), JP-A-Sho! ;/-#J94! Publication No. (hereinafter referred to as Patent Application 2), Tokukosho! ;t-3732/publication (
(hereinafter referred to as Patent Application 3) and JP-A-37-1-270
Publication No. 2 (hereinafter referred to as Patent Application 1) discloses that a transparent gel body of a network polymer obtained by partially polymerizing a crosslinkable monomer Ma is brought into contact with the network polymer in the state of refraction droplets, and the internal A method for manufacturing a synthetic resin light transmitting body in which the refractive index changes continuously from the surface toward the inside by polymerizing after diffusing or simultaneously with the diffusion is disclosed.

Further, Japanese Patent Application No. 5G-70/1989 (hereinafter referred to as Patent Application S) describes a method for continuously manufacturing an organic base material in order to continuously manufacture a synthetic resin optical transmission body. The method described in this application includes, in forming the base material,
General formula expressing plastic flow by prepolymerizing monomer Ma: % formula % (4) (In the formula, D is shear rate, σ is shear stress, K is the reciprocal of the gravity viscosity, and n is a constant. ) The above-mentioned base material is obtained by supplying the reamer to a long and narrow passage and heating and polymerizing it while advancing the passage. The reasons for using the prepolymer under the above conditions are as follows.

When an object similar to a tool-ton fluid, such as a monomer or a low-viscosity prepolymer, is introduced into a long, thin tube and polymerized by heating while passing through the tube, the heat is applied from the outside of the tube, so Polymerization proceeds from the nearby peripheral region, and the viscosity increases accordingly. The fluid flowing inside the pipe originally has a velocity distribution in which the flow velocity is maximum at the center and decreases parabolically toward the periphery, but as polymerization progresses, the velocity distribution between the peripheral region and the center region The speed difference becomes even larger. In the end, the fluid in the peripheral region gels first and accumulates in the tube, while the fluid in the central region flows out of the tube without polymerizing.

In order to correct this, it is necessary to make the velocity distribution of the fluid within the pipe as constant as possible. That is, it is sufficient to bring the fluid in the pipe closer to Bingham fluid. Bingham fluid is a case of n-■ in the above equation (4), and the flow rate of the fluid in the pipe is constant. As n becomes smaller and approaches l,
The fluid approaches Nieton's fluid. In addition, the flow velocity of the fluid near the inner wall of the pipe does not change much depending on the value of n; in fact, the larger n is, the greater the flow velocity is.
The closer it gets to the point, the higher the flow velocity near the center becomes, and as a result, the difference in flow velocity between the peripheral region and the center region becomes larger, and the parabola of the velocity distribution becomes sharper.

From this perspective, we filed the above patent application! As described above, the monomer Ma is prepolymerized to form a viscous fluid in which the value of n is /, 10 or more, and then fed into the forming tube. That is, if the value of n is less than 1.10, if the vicinity of the periphery is first gelled, the monomer Ha near the center will be
flows out from the pipe without being polymerized, making it impossible to form a good base material.

In this case, if the flow rate is extremely reduced, the base metal will not be formed, but productivity will be poor and this is not practical.

Preferably, the value of n is at most 850. This is because if the value of n is too large, it becomes difficult to push into the pipe or the base material becomes non-uniform, causing problems.

Furthermore, Japanese Patent Application No. 5G-702 (hereinafter referred to as Patent Application 6)
discloses a method of continuously producing a synthetic resin optical transmission body by continuously drawing out an organic base material by the production method of the above-mentioned patent application J and following the production method of the above-mentioned patent application /-1.

In this method, after forming an organic matrix into a continuous state, it is introduced into a diffusion chamber heated to a constant temperature, and the monomer Mb in a liquid, gas, or mist state is absorbed. After being diffused, it is heated to complete the polymerization. By continuously passing the organic base material through the above steps, a synthetic resin light transmitting body is continuously manufactured.

3.3 Problems to be Solved by the Invention The conventional method described above has the following drawbacks.

The organic base material is molded by supplying the prepolymer into a long and slender molding tube and heating and polymerizing it as it advances through the tube, but before the molding base material comes out of the tube, the organic base material and the molding tube are separated. There is a problem that monomeric Mb enters into the gaps.

When Mb enters the molded tube in this way, the monomer Mb diffuses from the surroundings into the prepolymer that is being molded into the organic base material with a predetermined cross-sectional shape, and at this time, the monomer Mb If the polymerization rate of monomer Mb and the copolymerization rate of monomer Ma in the prepolymer is higher than the polymerization rate of monomer Ma, the peripheral area where monomer Mb diffuses will not be in the central area. As the polymerization progresses further, the velocity distribution of the prepolymer, which was originally kept close to the Bingham fluid in order to keep the velocity distribution in the molding tube as constant as possible, changes.

In other words, the flow velocity in the peripheral region decreases and the velocity difference with the central region increases, and as a result, the prepolymer in the peripheral region remains on the inner wall of the passage, resulting in the base material becoming thinner and unevenness appearing on the surface, resulting in poor manufacturing conditions. Not only does it become stable, but it also has a negative effect on optical performance. Furthermore, in the end, the prepolymer in the peripheral region gels first and stays in the passage, and as the flow area decreases, the prepolymer in the central region flows at a high velocity. As a result, the organic base material, which had been connected in a continuous manner, was cut off as it flowed out of the passage without being polymerized, resulting in the phenomenon that it became impossible to continuously manufacture synthetic resin light transmitters. .

3. tI Means for solving conventional problems At the outlet of the molding means, the gap between the molding base material and the inner wall of the molding means is filled with, for example, a chemically inert liquid or the same monomer as the base material. It is sealed with a sealing layer made of a liquid that does not substantially have an adverse effect on the base material, such as the polymer.

7.3 Effects of the Invention The liquid seal layer described above prevents the diffusion substance in the diffusion means from entering the molding means.

This eliminates the phenomenon that the prepolymer in the peripheral region gels first in the molding means and stays in the passageway, making it possible to stably and continuously manufacture the optical transmission body over a long period of time.

36th Example Hereinafter, an example of the method for manufacturing a synthetic resin optical transmission body according to the present invention will be described with reference to the drawings.

In FIG. 1, an extruder (1) cooled by cooling water contains a viscous fluid (hereinafter referred to as prepolymer fluid) used as a raw material for a synthetic resin light transmitting body. This prepolymer fluid maintains fluidity by prepolymerizing the monomer Ma until immediately before gelation. Further, the extruder (1) has an extrusion tool (not shown), and the prepolymer (10) is extruded by this extrusion tool. After being extruded, the prepolymer (10) satisfying the above conditions is continuously introduced into a molded tube (3) made of a Teflon tube, for example, passing through a heating jacket (2) made of a brass block or the like. be done.

This formed tube (3) has a circular cross section and a diameter of /-20mm.
It may be of. Here, if the lower end of the stainless steel tube is inserted into the molded tube (3) from above in advance, the tip of the prepolymer (lO) will gel while in contact with the lower end of the stainless steel tube. The lower end of the stainless steel tube and the tip of the prepolymer (10) are integrally joined. After this, if the stainless steel tube is pulled up with a pulling device at the same speed as the extrusion speed, the prepolymer that accompanies it will become a light transmitting body continuously during the entire manufacturing process? It is generated and comes out without being stagnant in the device. The heating jacket (2) is supplied with relatively high temperature water (16) at its upper part and lower temperature water (17) at its lower part, so that the temperature gradually increases from the lower part to the upper part. The forming tube (3) is heated with a temperature gradient. There, while passing through the molded tube (3), the prepolymer (10)
is polymerized and gelled by heating, and this gelled prepolymer becomes a continuous cylindrical base material (11). The heating rate during this heating polymerization is preferably 0./-10"C/min. When heating is performed under the temperature gradient as described above, the polymerization of the prepolymer (10) and its Since the accompanying increase in viscosity progresses gradually, it is possible to flow the prepolymer (10) while maintaining a fluid state similar to that of a Pingam fluid.As a result, the base material has a uniform composition in the radial direction. (11) can be formed continuously. Note that the Teflon chain (3) is particularly useful here because it has low friction with the prepolymer (10) and the base material (11). However, other resin or metal chips may be used.

In this way, the formed tube (3) inside the heating jacket (2)
), a gel-like base material (11) is produced which loses its fluidity and has self-retaining properties. This base material (1
1) Preferably the component insoluble in acetone, that is, the part of the network polymer! ~deO weight de, more preferably 1
0-! ; Contains 0% by weight. If this component is too small, the fluidity becomes high, and if it is too large, the diffusion rate of the monomer Mb becomes too slow in the subsequent diffusion step, which is not preferable.

Subsequently, the base material (11) is fed into a vapor phase diffusion device (4). The above monomer Mb is placed at the bottom end of the gas phase diffusion device (4).
A liquid sealing device (15) is attached to prevent liquid from entering the forming tube (3).

As shown in detail in FIG. 2, this liquid sealing device (15) is provided between the outlet of the forming tube (3) and the diffusion device (4), and has a hollow liquid reservoir chamber (15a). The sealing liquid (14) is continuously fed into the chamber (15a) through the opening (16) and is discharged to the outside through the outlet (17). The base material (11) that has exited the molded tube (3) is then transferred to the liquid reservoir chamber (1).
5a) after passing through the sealing liquid (14) in the diffusion chamber (4).
)to go into.

Thereafter, the organic matrix (11) is placed on the peripheral surface of the organic matrix in a diffusion chamber (4) which is filled with the monomer Mb in any of the liquid phase, gaseous phase and atomized state. As a result, a concentration gradient is formed in the organic matrix in which the concentration of monomer Mb gradually increases from the central axis toward the peripheral surface in a square approximation. The refractive index distribution shown by formula 1) or formula (3) is formed, but monomer Mb, which is in any of the liquid phase, gas phase, or mist state, is in any state. Since the gap between the forming tube (3) and the base material (11) is airtightly sealed with the sealing liquid (14), the liquid enters through the gap between the organic base material and the forming tube and is being formed into the organic base material. It does not diffuse into the prepolymer.

Therefore, the velocity distribution in the prepolymer is not adversely affected by the diffusion of the monomer Mb, and the organic base material does not have surface irregularities and there is no fear of cutting, and the organic base material with a good surface condition is continuously extruded. It's coming.

The sealing liquid (14) can simply be held stationary without flowing, but if it is allowed to flow continuously at a constant speed as in the example, it will seep out (diffuse) from the organic matrix. The concentration of monomer Ma in the liquid is always constant, and the manufacturing conditions can be maintained constant.
It is desirable that the polymerization of

As the sealing liquid (14) used in the present invention, it is possible to use the same monomer as the monomer Ma constituting the base material or another monomer MO different from Ma and the diffusion monomer Mb. can.

When using a monomer MC liquid as described above, if the monomer reactivity ratio of MO is equal to the reactivity ratio of the rC1 base material monomer and satisfies the condition rc≦ra, the refractive index can be high or low.

In addition, the sealing liquid (14) of the present invention is a chemically inert liquid having a molecular volume larger than that of the monomer Ma so as not to chemically react with the base material and unable to diffuse into the base material; For example, silicone oil, polyethylene glycol, water, etc. can be used.

However, when the monomer Wb is to be diffused into the base material in a liquid phase, it is necessary to use a monomer that has a higher specific gravity than Mb and is incompatible with Mb, or a chemically inert liquid. The diffusion device (4) includes an outer tube (4a) surrounding a diffusion chamber (4b).
), and this outer tube (4a) has an inlet (
Warm water (1 day) is flowing from the outlet (21) to the outlet (22).

By heating the inside of the diffusion chamber (4b) with this hot water (18), a part of the monomer 1ifb diffuses and polymerizes alone or with the prepolymer etc. in the base material (11), resulting in the above concentration gradient. is becoming defined.

The atmosphere in the diffusion chamber is formed after air is evacuated or replaced with nitrogen to avoid inhibition of polymerization by oxygen.

Also, the temperature, as in the case of known methods, for example!
; -90″C. The higher this temperature is, the higher the diffusion rate of the monomer Mb becomes, but this is not preferable because the polymerization rate of the base material itself also increases.
The time (diffusion time) for which the base material is allowed to stay in an atmosphere containing the liquid phase of the monomer Mb or the vapor or mist droplets of Mb and the above-mentioned diffusion temperature depend on the refractive index gradient of the optical transmission body to be obtained, that is, the It is determined by the concentration gradient of the mercury Mb.

However, if this diffusion time is extremely long or the diffusion temperature is too high, the concentration gradient of the monomer Mb may become flat, or the concentration gradient may suddenly become large near the outer periphery of the base material. refractive index gradient cannot be obtained. After diffusing the monomer Mb, the base material (11) is guided from the diffusion device to the heat treatment tube (5)K. This heat treatment tube (5) is heated by a heater (13);
A temperature gradient may be formed by increasing the temperature in step 13) from the bottom to the top of the device. The inside of this heat treatment tube (5) is also purged with nitrogen. Here, the base material (11) is further heated to complete polymerization. As will be described later, the refractive index of the optical transmission body thus obtained increases continuously in the radial direction in proportion to the square of the distance from the central axis, or It has a decreasing refractive index gradient. This refractive index does not change in the length direction of the optical transmission body and remains constant.

The monomer Ha to be the raw material of the transparent gel body as the organic matrix in the above examples is a monomer having two or more types of groups among allyl group, acrylic acid group, methacrylic acid group, or vinyl group. You can use your body. Next, specific examples of monomer Ma will be given.

(1) Allyl compound 7 Diallyl esters such as diallyl talate, diallyl isophthalate, diallyl terephthalate, diethylene glycol bisallyl carbonate; triallyl trimelide;
Triallyl esters such as triallyl phosphate and triallyl phosphite; unsaturated acid allyl esters such as allyl methacrylate and allyl acrylate.

(2), compounds R1 and R represented by R1-R2-13
A compound in which 3 is a vinyl group, an acrylic group, a vinyl ester group, or a methacrylic group; one of R1 and R3 is a vinyl group, an acrylic group, a methacrylic group, or a vinyl ester group; and the other is any of the remaining three groups. Here, R2 can be selected from the divalent groups shown below.

(iH3-(0H20H:=O) m-CH2CH2-(m-
0-20)\0H2-OH,'-((3H2)p-(1)-J~/j)(OH2)jH (3), a mixture of the monomers of (1) and (2) above, or A mixture of at least one of the five types of monovinyl compounds, vinyl esters, acrylic esters, and methacrylic esters and the monomer (1) or (2) (or a mixture thereof).

Furthermore, examples of the monomer Wb include the following.

(4) A compound represented by 0H2-(3-000Y, where X is a hydrogen atom or a methyl group, and CH2
a group selected from the group consisting of -CH2CH3 (p-/~6) under CH2O, or -(CF2)a-F (a=/-4
), -0Ig(CFg)bH(b-'-5), -0H2
,CR20・CH2clt'3, (CH20H20)O
0F20F2H (0-/-1I), -0H2CH20・
0H2(OF2)aF(a-/ ~t), -〇Hz
((3Fg)do (CFg MF (d -/-2
represents a group selected from the group consisting of )J-/~g) and -3I(OCigH5)3.

(5), a compound represented by (Jg-C7HOG-R4, where R4 is -((R2)f-CH3(f-0-2
), -(CH2)gH(g-t~3), -(CH2)8
Represents a group selected from group 0.

(6), a mixture of monomers of (5) and (5).

Any of the above (1) to (3) as the monomer Ma and (4) to (6) as the monomer Mb can be combined.

In addition, in order to adjust the gelation state of the transparent gel object, (
3) A method of adding a monomer having one unsaturated group to the crosslinkable monomer Ma, and CBr4, CCl4
, a method of adding a chain transfer agent such as mercaptans, or a method of using both in combination is effective.

Next, test examples of the present invention will be explained.

Test Example 1 Diethylene glycol bisaryl carbonate (CO) in which 3.0% by weight of benzoyl peroxide (BPO) was dissolved
A prepolymer is prepared by prepolymerizing R-J9> by heating at 73"C for 35 minutes.

The viscosity of this prepolymer at 40°C is / O / j Op
The values of K and n in the above equation (4) are x and 5yxto c!, respectively. /1dyne sac
and 821. This prepolymer (10) is put into the extruder (1) of the apparatus shown in Fig. 1, and inside the Teflon tube (3) (diameter J mm and length J (70 mm)) passing through the heating jacket (2). to L x/0-2
It was fed continuously at a constant flow rate of m1/mm. The heating jacket (2) has l0℃ hot water (16) at the top and ≦ at the bottom.
A temperature gradient was created by flowing hot water (17) at f°C in each case. The prepolymer (10) gelled while passing through the Teflon tip for about 33.5 minutes, and was molded into a base material (11) with a diameter of 3 mm.

This base material (11) contains a component insoluble in acetone (reticular polymer portion) - 5% by weight, a component soluble in acetone but insoluble in methanol (linear polymer portion) 5% by weight, and soluble in both acetone and methanol. It consisted of 70% by weight of soluble components (monomers and a portion of low molecular weight prepolymer).

Next, the base material (11) is pulled up to 3.2 mm by a pulling device.
It is fed into the vapor phase diffuser (4) at a constant rate of 7 minutes.

At the bottom of this gas phase diffusion device (4), 30 OR-49
A liquid seal device (1
5), the matrix (11) passes through the OR-390 liquid phase and is then led into the diffusion chamber (4b) in the vapor phase diffusion device (4). As a result, monomer Mb, which is filled in the diffusion chamber (4b) as before, enters through the gap between the base material (11) and the Teflon tube and diffuses into the prepolymer that is being molded into the base material (11). The prepolymer was no longer damaged and the surface condition was not degraded and the prepolymer was no longer cut.

Thereafter, the organic base material sent into the diffusion chamber (4b) was methacrylic acid-2,2,2-)lifluoroethyl (3FMA).
) for about 170 minutes, the jFMA is diffused and partially polymerized. JFMA is vaporized in the steam generator (14) and then passed through the inlet (19).
) into the diffusion chamber (4b). Also JFMA
When the vapor was collected from the outlet (20) by the pump (15) and liquefied in the trap, this JFMA was hardly polymerized and could be used repeatedly. In addition,
In the diffusion chamber (4b), before introducing jFMA,
Nitrogen gas was introduced at a flow rate of 1 ml to replace the air in the prefecture with nitrogen.

Outside 9! (4a) is divided into three parts, and hot water at 71.10 and 11°C flows from the bottom.

The base material (11) that has passed through the diffusion device (4) is then heated to a nitrogen content (°C).
, l to "Cz/30"C to form a temperature gradient. The base material was heat treated in this heat treatment tube (5) for 6 hours to complete polymerization.

In this way, a synthetic resin optical transmission body with a diameter of J mm was obtained stably for a long period of time with a good surface condition. The numerical aperture HA of this optical transmitter was o, 3g.
4), flowing at a flow rate of 30 CC/hr,
When a synthetic resin optical transmission body was continuously produced in the same manner as Test Example 1, it was stably produced continuously for a long period of time while maintaining a good surface condition as in Test Example 1. The numerical aperture NA of this optical transmission body was 0.39.

Test Example 3 Polyethylene glycol (molecular weight 100>) was added to the sealing liquid (
14) Used as 1. When a synthetic resin optical transmitter was continuously manufactured in the same manner as Test Example 1 by flowing at a flow rate of t Occ/hr, it was found that the same as in Test Example 1, it was possible to stably and continuously manufacture the material for a long period of time with good surface condition. Ta. The numerical aperture HA of this optical transmission body was O, J#.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing the entire optical transmission body continuous manufacturing apparatus, and FIG. 2 is a cross-sectional view showing the main part of the apparatus shown in FIG. 1. (1)...Extruder (2)...φ-heating jacket (3)...Forming tube (4)...Vapor phase diffusion device (5)... Heat-treated tube (10), eφ, prepolymer (11), base material (12), synthetic resin light transmitter (14), e-sealing liquid (15), etc. ...Liquid sealing device (16)...Sealing liquid inlet (17)...Sealing liquid outlet Fig. 1 View of Fig. 2

Claims (6)

[Claims] (1) The organic base material that has been molded by the molding means and is in a state where the additive can be diffused into the molding means is continuously drawn out from the molding means, and the organic base material that is being continuously drawn is heated by the diffusion means and the heating means. At this time, the additive is diffused into the organic base material by the diffusion means, and the organic base material is heated by the heating means to remove the additive in the organic base material. In the method for manufacturing a synthetic resin light transmitting body in which the distribution is defined, the gap between the molding base material and the inner wall of the molding means is sealed at the exit portion of the molding means with a liquid sealing layer, thereby molding the additive. A method for manufacturing a synthetic resin light transmitting body, characterized in that it prevents intrusion into the means. (2) A method for manufacturing a synthetic resin optical transmission body according to claim 1, in which the liquid seal layer uses the same monomer as the base material. (3) A method for manufacturing a synthetic resin light transmitting body according to claim 1, in which a monomer having a monomer reactivity ratio lower than that of the monomer of the base material is used as the liquid sealing layer. (4) A method for manufacturing a synthetic resin optical transmission body according to claim 1, in which a chemically inert liquid is used as the liquid sealing layer. (5) A method for producing a synthetic resin light transmitting body according to claim 4, using a chemically inert liquid having a molecular volume larger than that of the monomer constituting the base material as the liquid seal layer. (6) In claim 1, the liquid seal layer is a synthetic resin optical transmission body formed by continuously flowing a predetermined liquid in a direction transverse to the progress of the base material near the exit of a molding means. manufacturing method.