JPH0546522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a synthetic resin optical transmission body having a refractive index distribution.

A transparent rod-shaped body having a refractive index distribution that decreases in proportion to the square of the distance from the central axis is known as a light transmission body. This transparent rod-shaped body has a convex lens effect, and its refractive index distribution is approximated by equation (1).

n(r)=n ₀ (1-1/2Ar ² ) ...(1) (In the formula, n(r) is the refractive index at the point of distance r from the central axis, n ₀ is the refractive index at the central axis, (A represents a positive constant.) The light beam propagates in a meandering manner in such a transparent rod-shaped body, and its period L is expressed by equation (2).

L=2π/√...(2) Also, as approximated by equation (3), if the transparent rod-shaped body has a refractive index distribution that increases in proportion to the square of the distance from the central axis, It becomes an optical transmission body with a concave lens effect.

n(r)=n ₀ (1+1/2Br ² )...(3) (In the formula, n(r) and n ₀ are the same as above, and B
is a positive constant. ) A method of manufacturing a synthetic resin optical transmitter having such a refractive index distribution is described in Japanese Patent Publication No. 52-5857 and Japanese Patent Application Laid-Open No.
It is described in JP-A No. 51-16394, Japanese Patent Application Laid-open No. 119939-1980, etc. In the method described in Japanese Patent Publication No. 52-5857 and Japanese Patent Application Laid-open No. 51-16394,
First, the crosslinkable monomer Ma that produces the network polymer Pa
A transparent gel-like matrix is formed by initial polymerization from a liquid state to a gel state that has lost fluidity.
Next, this base material is treated with a monomer different from the monomer Ma.
A monomer that is immersed in a liquid phase consisting of Mb so that the base material gradually decreases from the surface to the inside.
Diffuse monomeric Mb so that there is a concentration gradient of Mb. At this time, as the monomer Mb, a monomer that produces a polymer Pb having a refractive index different from the refractive index of the network polymer Pa is used. The monomer Mb is polymerized simultaneously with the diffusion and/or during the heat treatment step after the diffusion, and the polymerization of the monomer Ma is also completed at this time. Japanese Patent Publication No. 5857/1983 and Japanese Patent Application Publication No. 51/1983
In the method described in Japanese Patent No. 16394, a synthetic resin optical transmission body having a refractive index distribution is thus obtained.

However, in the above method, the base material is immersed in the liquid monomer Mb, and the base material surface and the liquid monomer Mb are immersed.
Direct contact with Mb had several disadvantages. For example, when diffusion and polymerization of the monomer Mb are carried out simultaneously, the dipping temperature must be relatively high, and the polymerization initiator normally contained in the base material will liquefy as the dipping time passes. Since it is eluted into the phase, monomer Mb gradually polymerizes even in the liquid phase and becomes viscous. As a result, when the base material is removed from the liquid phase after diffusion, the viscous layer thus formed remains attached to the surface of the base material. During the heat treatment process, the monomer Mb leaches out of this viscous layer and diffuses into the base material, causing an increase in undesirable distortion in the refractive index near the outer periphery of the resulting light transmitting body. In order to eliminate such drawbacks, it may be possible to add a polymerization inhibitor that suppresses the polymerization of monomer Mb in the liquid phase, but in this case, this polymerization inhibitor may
A new drawback arises in that Mb diffuses simultaneously into the base material and inhibits the completion of polymerization in the heat treatment process.

In addition, if the monomer Mb is polymerized after being diffused, a relatively low immersion temperature is required, but in this case, the diffused monomer Mb evaporates from the outer periphery of the base material during the heat treatment process. This causes an increase in undesirable distortion in the refractive index distribution near the outer periphery.

The method described in JP-A-54-119939 is an improvement on the above-mentioned method to avoid distortion of the refractive index distribution near the outer periphery. According to this method, monomeric Mb is diffused in the gas phase. That is, the base material is placed in a vapor atmosphere of monomer Mb for a predetermined period of time to diffuse the monomer Mb into the base material, and at the same time as this diffusion, part of the monomer Mb is polymerized, and finally, by heat treatment. to complete the polymerization. In this method, the base material is monomer in liquid phase.
Because the contact is not with Mb but with monomer Mb in the gas phase, there are the following advantages.

(1) Excess monomer Mb does not adhere to the surface of the base material. Therefore, monomeric Mb deposited during the heat treatment process
does not diffuse into the interior from the surface of the base material.
Furthermore, since the diffusion is carried out at a high temperature, the monomer Mb is polymerized and fixed while diffusing inside the base material. Therefore, the monomer Mb does not evaporate from the outer periphery of the base material during the heat treatment process. Therefore, it is possible to obtain an optical transmission body with little distortion of the refractive index at the outer circumferential portion and having an initial refractive index distribution over a wide range.

(2) Polymerization of monomer Mb in the liquid phase can be prevented by adding a polymerization inhibitor to liquid monomer Mb, which is a source of vapor of monomer Mb.
At that time, if a polymerization inhibitor with low vapor pressure is used,
Since it hardly evaporates, it does not diffuse into the base material, and therefore, polymerization is not inhibited during the heat treatment process. Furthermore, by adjusting the supply rate of monomer Mb, there is no need to add a polymerization inhibitor, making it possible to use monomer Mb many times and increasing its recovery rate.

However, this method has the following drawbacks. In other words, when monomeric Mb is diffused from the gas phase into the base material, the monomeric Mb concentration in the gas phase depends on the vapor pressure at the gas phase temperature. The types of monomers suitable for proceeding are limited to specific monomers with high vapor pressures. For example, 1,1,
3-trihydroperfluoropropyl (monomer
The combination with Mb) could not be applied to the method of JP-A-54-119939 because the latter has a low vapor pressure and is difficult to diffuse into a base material with a diameter of 4 mm or more.

The present invention overcomes the drawbacks of these prior art technologies while taking advantage of their respective strengths. We then developed a method for manufacturing synthetic resin optical transmission bodies that can form desired refractive index distributions over a wide range of the base material from the center to the outer periphery for various combinations of monomer Ma and monomer Mb. This is what we provide.

That is, this invention performs incomplete polymerization of a monomer Ma that produces a network polymer Pa with a refractive index of Na to form a self-shape-retaining base material, and has a refractive index of Na.
A refraction method that produces a polymer Pb having a refractive index different from that of Nb, and in which a monomer Mb in a liquid state is brought into contact with the surface of the base material and diffused into the interior thereof, and is further heated and polymerized. In the method for manufacturing a synthetic resin light transmission body having a rate distribution, a molding fluid obtained using the monomer Ma is fed into a molding tube to continuously form the self-shape-retaining base material in the molding tube. Then, in the self-shape-retaining base material continuously coming out of the molded tube, a liquid phase diffusion chamber containing the liquid monomer Mb, a monomer that is the same as or different from the monomer Mb.
Refraction that satisfies any one of the conditions (a) to (c) that is Mc and (a) Nc=Nb (b) Nc<Na and Nb<Na (c) Nc>Na and Nb>Na A monomer in the form of gas or droplets that forms a polymer Pc with a ratio Nc and is heated and controlled to a constant temperature.
The present invention relates to a method for manufacturing a synthetic resin optical transmission body, characterized in that the material is sequentially passed through a vapor chamber containing Mc.

According to the manufacturing method of the present invention configured as described above, formation of a base material having self-shape retention, internal diffusion of monomer Mb into this base material, and heating polymerization of the base material by monomer Mc are performed. Since the process can be carried out sequentially and continuously, it is possible to mass-produce graded index synthetic resin optical transmitters having uniform characteristics and constant quality through a simple manufacturing process. In addition, monomer Mb, which accounts for most of the monomers diffused into the base material, is not limited to those with high vapor pressure, and monomer Mc also has
Since it is only necessary to suppress the evaporation of the monomer Mb from the outer periphery of the base material, it is not necessary to have a particularly high vapor pressure. In addition, heat treatment can be applied to monomer Mc (monomer Mb
Since the process is carried out in an atmosphere containing vapor (which may be the same as the above) (in the form of gas or droplets), distortion of the refractive index distribution near the outer periphery of the base material can be removed or avoided.

Next, an embodiment of the method for manufacturing a synthetic resin optical transmission body according to the present invention will be described using the apparatus shown in the drawings.

First, the monomer Ma is prepolymerized to produce a viscous fluid (prepolymer) that maintains fluidity just before gelation. This prepolymer 1 is put into an extruder 2, and while being cooled once with cooling water,
Extrude continuously.

Here, the prepolymer has the following general formula: D=Kσ ⁿ ...(4) (In the formula, D is the shear rate, σ is the shear stress, K is the reciprocal of the plastic viscosity, and n is the constant.) It is desirable to exhibit plastic flow in which the value of n at 20°C in the Newtonian fluid general equation (Ostwald's power law) is 1.10 or more. The reason is explained below.

When a fluid similar to a Newtonian fluid, such as a monomer or a low-viscosity prepolymer, is introduced into a long and thin tube and is heated and polymerized while passing through the tube, the heat is applied from the outside of the tube, so Polymerization proceeds from the peripheral region, and the viscosity increases accordingly. The fluid flowing inside the tube 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 increases. The speed difference becomes even larger. In the end, the fluid in the peripheral region gels first and stays 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. In the case of Bingham fluid, n=∞ in the above equation (4), and the flow rate of the fluid in the pipe is constant.
As n becomes smaller and approaches 1, the fluid approaches a Newtonian fluid. In addition, the flow velocity of the fluid near the periphery 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, but as n approaches 1, the flow velocity near the center increases. As a result, the difference in flow velocity between the peripheral region and the central region becomes large, and the parabola of the velocity distribution becomes sharp.

From this point of view, as mentioned above, monomers
It is preferable to prepolymerize Ma to form a viscous fluid with an n value of 1.10 or more before feeding it into the pipe. That is, if the value of n is less than 1.10, if the vicinity of the periphery is first gelled, the monomer Ma in the vicinity of the center will not be polymerized and will flow out of the tube, 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. Further, more preferably, the value of n is at most 1.50. This is because if the value of n is too large, it becomes difficult to push the material into the pipe, and the base material becomes non-uniform, causing problems.

Note that the value of K and the value of n in the above equation (4) can be determined using a viscometer (for example, a rotational viscometer). That is, after changing the rotational speed of the viscometer (which determines D) and measuring each σ, this is plotted on a graph to determine the values of K and n.

The extruded prepolymer 1 is then continuously introduced into a Teflon tube 4 passing through a heating jacket 3, such as a brass block. This Teflon tube 4 has a circular cross section with a diameter of 1 to 20 mm.
It may be mm. Here, if the lower end of the stainless steel tube is inserted into the Teflon tube 4 from above in advance, the tip of the prepolymer 1 will gel while in contact with the lower end of the stainless steel tube. and the tip of prepolymer 1 are integrally bonded. When the stainless steel tube is pulled up by a pulling device at the same speed as this push-out speed, the prepolymer accompanying it becomes a light transmitting body and is produced continuously and without stagnation in the device during the entire manufacturing process. It comes out. The heating jacket 3 is supplied with relatively high-temperature hot water 5 at the top and hot water 6 at a lower temperature at the bottom. Tube 4 is being heated. Then, while passing through the Teflon tube 4, the prepolymer 1 is polymerized and gelled by heating, and this gelled prepolymer becomes the base material 7. The heating rate during this thermal polymerization is 0.1
Preferably it is ~10°C/min. When heated under the temperature gradient described above, both the polymerization of prepolymer 1 and the accompanying increase in viscosity proceed gradually. It becomes possible to make it flow. As a result, it becomes possible to continuously form the base material 7 having a uniform composition in the radial direction. In addition, here, the Teflon tube 4 is
This tube is particularly useful because it has low friction with the prepolymer 1 and the base material 7, but tubes made of other resins or metals are also acceptable.

In this way, the Teflon tube 4 in the heating jacket 3 produces a gel-like base material 7 that has almost lost its fluidity and has self-shape retention. The base material 7 preferably contains an acetone-insoluble component, ie, a network polymer portion, in an amount of 5 to 90% by weight, more preferably 10 to 50% by weight.
If this component is too small, the fluidity becomes high, and if it is too large, the diffusion rate of monomer Mb becomes too slow in the subsequent diffusion step, which is not preferable.

Subsequently, the base material 7 is fed into a diffusion device 8.
The lower part of this diffusion device 8 is a liquid phase diffusion chamber 9, and liquid monomer Mb is supplied to this liquid phase diffusion chamber 9 from an injection port 10. This monomer Mb is stored in the liquid phase diffusion chamber 9, and the surplus is stored at the discharge port 11.
is discharged from. While staying in the liquid phase diffusion chamber 9,
In the base material 7, monomer Mb diffuses to the center, and a concentration gradient of monomer Mb is formed in the base material 7, which increases continuously in approximately proportion to the square of the distance from the central axis. be done. Further, a bubbler 12 is disposed in the monomer Mb of the liquid phase diffusion chamber 9, and vapor of the monomer Mb is generated by generating nitrogen gas bubbles from the bubbler 12. In this way, the vapor of the monomer Mb in the form of gas or droplets rises to the gas phase chamber 13 following the liquid phase diffusion chamber 9, fills this gas phase chamber 13, and enters the gas phase chamber 13. An atmosphere containing monomeric Mb vapor is formed. Monomer Mb is recovered from the exhaust port 17 by a vacuum pump (not shown). Liquid phase diffusion chamber 9
is substituted with nitrogen in advance to prevent inhibition of polymerization by oxygen.

The base material 7 in which the monomer Mb has been diffused is thus introduced into the gas phase chamber 13 filled with an atmosphere containing the monomer Mb vapor. The gas phase chamber 13 is heated by hot water flowing through an outer tube 14 surrounding it. While remaining in this gas phase chamber 13, a part of the diffused monomer Mb polymerizes alone or with the monomer Ma or prepolymer remaining in the base material 7, and as a result, the monomer Mb The concentration gradient of body Mb is fixed in the base material 7. At this time, since the base material 7 is surrounded by an atmosphere containing the vapor of the monomer Mb, the monomer Mb flows from the outer periphery of the base material 7 into the gas phase.
evaporation is suppressed. As a result, it is possible to produce an optical transmission body in which distortion in the refractive index near the outer periphery is almost absent or exists only in a narrow range. It is preferable that the monomeric Mb is contained in the gas phase in an amount of at least 20% or more of its saturation concentration. By doing so, the concentration (vapor pressure) of the monomer Mb becomes approximately equal to or higher than the concentration (vapor pressure) of the monomer Mb diffused into the outer peripheral portion of the base material 7. If the concentration of monomer Mb is higher in the gas phase than at the outer periphery of the base material, the monomer Mb
At the same time as the heating polymerization of Mb, the monomer Mb diffuses from the gas phase into the base material.

The temperature of the monomer Mb in the liquid phase diffusion chamber 9 is particularly high when vapor is generated from the monomer Mb.
Monomer Mb has a relatively high vapor pressure and must be maintained at a value that allows it to diffuse into the matrix, for example 5
Set to ~90℃. As this temperature increases, the diffusion rate of the monomer Mb increases, but the polymerization rate of the base material itself also increases, and the monomer Mb also increases.
This is not preferred because Mb polymerizes in the liquid phase and becomes viscous. In addition, the time for which the base material is retained in the diffusion chamber 8 (diffusion time) and the above-mentioned diffusion temperature are determined by the refractive index gradient of the optical transmission body to be obtained, that is, the monomer Mb
is determined by the above concentration gradient of . However, if this diffusion time is extremely long or the diffusion temperature is too high, the concentration gradient of the monomer Mb may flatten or suddenly increase near the outer periphery of the base material. refractive index gradient cannot be obtained.

In this embodiment, the monomer Mb in the liquid phase diffusion chamber 9 is used to form the atmosphere in the gas phase chamber 13. In other words, the case where monomer Mc is the same as monomer Mb is shown, but monomer Mc may be different from monomer Mb or a mixture thereof, and monomer Mb and this It may also be a mixture with other monomers. When a gaseous or atomized monomer Mc that is completely different from the monomer Mb is contained in the gas phase, the gas phase chamber 13 and the liquid phase diffusion chamber 9 are partitioned, and the liquid phase diffusion chamber 9 is monomeric Mb is used only for liquid phase diffusion without bubbling. Then, a gaseous or mist-like monomer Mc is introduced into the gas phase chamber 13 from a steam generator or the like. In addition, when the vapor of monomer Mb is filled in the gas phase chamber in the same manner as in the example, and the vapor of another monomer Mc is introduced into the gas phase chamber, the vapor of monomer Mb is inside the gas phase chamber. The system is a mixture of the monomer Mc and the monomer Mc vapor. In such a case, even if the monomer Mc is a compound that is a gas at room temperature, it can be used. However, in any case, the monomer
When the refractive index of homopolymers Pa, Pb, and Pc of Ma, Mb, and Mc are Na, Nb, and Nc, respectively,
If Nb is larger than Na, Nc is also larger than Na, and conversely, if Nb is smaller than Na, Nc is also larger than Na.
Unless a combination is selected in which Na is smaller than Na, the desired refractive index distribution cannot be obtained.

After heating and polymerizing in the gas phase chamber 13, the base material 7 is further led to a heat treatment tube 15 that is purged with nitrogen, and the heating and polymerization is completed. This heat treatment tube 15 is the heater 1
However, a temperature gradient may be formed by increasing the temperature of the heater 16 stepwise from the bottom to the top of the device. Also, this heat treatment tube 15 also contains a monomer.
Mb vapor may be introduced.

As will be described later, the refractive index of the light transmitting body 18 obtained in this way varies continuously in the radial direction approximately in proportion to the square of the distance from the central axis due to the combination of monomer Ma and monomer Mb. It has a refractive index gradient that increases or decreases. This refractive index does not change in the length direction of the optical transmission body and remains constant.

In the embodiments described above, the step of forming the base material,
Since the step of diffusing monomer Mb and the heat treatment step are all carried out continuously, it is possible to manufacture an optical transmission body with uniform characteristics and constant quality.

In the method of this invention, a monomer that can be polymerized to produce a transparent network polymer Pa having a refractive index of Na is used as the monomer Ma, and this monomer is a single monomer. It may be a monomer or a mixture of a plurality of monomers. Such a monomer Ma
As the monomer, monomers each having two or more double bond-containing groups such as an allyl group, an acrylic acid group, a methacrylic acid group, and a vinyl group, or having two or more of these groups at the same time, are preferable. . Next, a specific example of monomer Ma will be given.

(1) Allyl compounds and mixtures thereof.

Diallyl esters such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, and diethylene glycol bisallyl carbonate; triallyl esters such as triallyl trimellitate, triallyl phosphate, and triallyl phosphite; unsaturated materials such as allyl methacrylate and allyl acrylate Acid allyl ester.

(2) A compound represented by R ₁ −R ₂ −R ₃ and a mixture thereof.

A compound in which R ₁ and R ₃ are both a vinyl group, an acrylic acid group, a vinyl ester group, or a methacrylic acid group; either one of R ₁ and R ₃ is a vinyl group, an acrylic acid group, a methacrylic acid group, or a vinyl ester A compound in which the other is any of the remaining three groups. Here, R ₂ can be selected from the divalent groups shown below.

_R2 : (p- or m-isomer) (p- or m-isomer) −(CH ₂ CH ₂ O) _n --CH ₂ CH ₂ −(m=0 to 20) −(CH ₂ ) _p − (p=3 to 15) (i,j=1~3) (k=0-20) (3) A mixture of the monomers (1) and (2) above, or at least one of the five monovinyl compounds, vinyl esters, acrylic esters, and methacrylic esters. A mixture of a species and the monomer (1) or (2) above (or a mixture thereof).

In this invention, the monomer Mb is selected from a monomer which forms a transparent polymer Pb having a refractive index Nb greater than or less than the above-mentioned refractive index Na when it is polymerized. This monomer Mb may be a single monomer or a mixture of multiple types of monomers. The polymer Pb may be either a reticular polymer or a linear polymer. When the refractive index Nb is smaller than the refractive index Na, the resulting optical transmission body has a convex lens action with a refractive index distribution as expressed by the above equation (1). vice versa,
When the refractive index Nb is larger than the refractive index Na, an optical transmission body having a concave lens effect can be obtained with the refractive index distribution expressed by the above equation (3). The difference between these refractive indexes (|Na−Nb|) is preferably 0.005 or more, and if this difference is too small, a desired refractive index gradient cannot be obtained. In addition, the monomer Mb preferably has a relatively high vapor pressure, especially when diffused in a gas phase, for example, 5 mmHg at the diffusion temperature.
It is preferred to have a saturated vapor pressure higher than . Examples of such monomers Mb include styrene, methacrylates, acrylates, vinyl acetate, vinyl chloride, acrylonitrile, butadiene and mixtures thereof.

Preferred examples of the combinations of the network polymer Pa and the monomer Mb of the present invention include those suitable for producing a light transmitting body with low chromatic aberration as described below, as well as the following combinations. First, in the case of Na > Nb, diallyl phthalate polymer - methyl methacrylate, diallyl phthalate polymer - mixture of methyl acrylate and methyl methacrylate, diallyl isophthalate polymer - methyl methacrylate, diallyl phthalate polymer Copolymer with styrene - methacrylic acid ester, copolymer with diallyl isophthalate and styrene - acrylic acid ester, copolymer with divinyl phthalate and divinyl benzoate - methacrylic acid ester, divinyl isophthalate and vinyl benzoate - Copolymer of methacrylic acid ester, vinyl benzoate and diallyl isophthalate -
Such as methacrylic acid ester. Also, Na<
Examples of Nb include diethylene glycol bisallyl carbonate polymer-styrene, diethylene glycol bisallyl carbonate polymer-diallyl isophthalate, and the like.

In addition, the following combinations of monomer Ma and monomer Mb are particularly suitable for producing a synthetic resin optical transmission body with low chromatic aberration.

(a) Diethylene glycol bisallyl carbonate as Ma, or a mixture thereof with diallyl phthalate, diallyl isophthalate, vinyl benzoate or styrene (provided that the amount of diethylene glycol bisallyl carbonate in this mixture is not less than 50% by weight) (more preferably 70% by weight or more).
Compound (A) as Mb: [Wherein, X is a hydrogen atom or a methyl group, Y is a phenyl group, a methylphenyl group, a vinyl group, i
-propyl group, i-butyl group, s-butyl group,
t-butyl group, (x=0~2), Represents a group selected from the group consisting of (y=0-2) and (-CH ₂ CH ₂ O) _z CH ₃ (z=1-3). ] A compound represented by or a mixture thereof.

(b) Diethylene glycol bisallyl carbonate as Ma, or a mixture thereof with methyl acrylate, ethyl acrylate, n-butyl methacrylate or t-butyl methacrylate (however, the amount of diethylene glycol bisallyl carbonate in this mixture is 10 % by weight or more). Compound (B) as Mb [In the formula, X is a hydrogen atom or a methyl group, and Y is -(CF ₂ ) _i F (i = 1 to 6), -CH ₂
(CF ₂ ) _j H (j = 1 to 8), -CH ₂ CH ₂ OCH ₂ CF ₃ , -(CH ₂ CH ₂ O) _k CF ₂ CF ₂ H (k = 1 to 4), -(CH ₂ CH ₂ OCH ₂ (CF ₂ ) _l F (l = 1 to 6), -CH ₂ (CF ₂ ) _n O (CF ₂ ) _o F (m = 1 to 2, n = 1
~4) represents a group selected from the group consisting of ] Fluorine-containing alcohol ester of methacrylic acid or acrylic acid, or the above general formula (B)
A compound (C) _in which Y is -Si( _OC2H5 ) ₃ .

(c) A mixture of diethylene glycol bisallyl carbonate as the monomer Ma and the above compound (B) or (C) (however, the amount of diethylene glycol bisallyl carbonate in this mixture is preferably 10% by weight or more). The above compound (A) as monomer Mb.

The monomer Mc of this invention is a polymer Pc which is the same or different from the monomer Mb and has a refractive index Nc.
is generated. This monomer Mc may be either a single monomer or a mixture of multiple types of monomers, and any of the above compounds exemplified as monomer Mb can be used as monomer Mc. It is. In particular, those with high vapor pressure are suitable.

Next, a specific example of this invention will be shown.

Specific example 1 Diethylene glycol bisallyl carbonate (CR-39) in which 3.0% by weight of benzoyl peroxide (BPO) was dissolved as a polymerization initiator was heated at 75℃ for 65 minutes.
The mixture was prepolymerized by heating for a minute to obtain a prepolymer that maintained fluidity just before gelation. The viscosity of this prepolymer is 1015 cp at 20°C, and the values of K and n in the above equation (4) are each 2.57 × 10 ^-2 cm ²
dyne ^-1 sec ^-1 and 1.21. This prepolymer 1 is put into an extruder 2 of the apparatus shown in FIG.
6.3×10 ^-2 into the Teflon tube 4 (diameter 4 mm, length 200 mm) passing through the heating jacket 3.
It was fed continuously at a constant flow rate of ml/min. Heating jacket 3 has 78℃ hot water 5 on the top and 58℃ on the bottom.
A temperature gradient was created by flowing hot water 6 at a temperature of .degree. While passing through Teflon tube 4 for 40 minutes, prepolymer 1 gels and becomes 4 mm thick.
It was molded into a base material 7 of φ. This base material 7 consists of 25% by weight of a component insoluble in acetone (reticular polymer portion), 5% by weight of a component soluble in acetone but insoluble in methanol (linear polymer portion), and a component soluble in both acetone and methanol. It consisted of 70% by weight (monomers and low molecular weight prepolymer parts).

Next, the base material 7 is pulled up to 0.25
It was introduced into the diffuser 8 at a constant speed of cm/min. The liquid phase diffusion chamber 9 contains 1.0% of 1,1,3-trihydroperfluoropropyl methacrylate (4FMA).
A constant flow rate of ml/min was applied. This 4FMA was used without adding a polymerization inhibitor. Also, this
The vapor of 4FMA was generated by bubbling nitrogen into the 4FMA at a flow rate of 200 ml/min, and the gas phase chamber 13 was filled with the vapor of 4FMA. Liquid phase diffusion chamber 9
The temperature was 70°C, and the gas phase chamber 13 was heated by flowing hot water at 80°C through the outer tube.
The 4FMA vapor was collected by a vacuum pump at a flow rate of 800 ml/min and liquefied in the trap. Liquefied 4FMA and liquid phase diffusion chamber 19 flowed out.
4FMA was hardly polymerized and could be used repeatedly as is. In addition, the gas phase chamber 13 is filled with 1000
Nitrogen gas was introduced at a flow rate of ml/min for nitrogen replacement.

The base material 7 is placed in the liquid phase diffusion chamber 9 for about 5 minutes, and then placed in the gas phase chamber 13.
While staying for about 30 minutes, 4FMA is diffused,
A part of it was polymerized by heating.

The base material 7 that had passed through the diffusion device 8 was then fed into a heat treatment tube 14 that was purged with nitrogen. This heat treatment tube 14
are heated to 90℃ and 110℃ sequentially from the bottom by heater 6.
℃, 120℃, and 130℃ to form a temperature gradient. The base material was heat treated in this heat treatment tube 14 for 6 hours to complete polymerization.

From the rod-shaped bodies having a diameter of 4 mm that were continuously produced in this manner, a rod-shaped convex lens having uniform optical performance, that is, a desired light transmission body was obtained. This rod-shaped body is an optical transmission body in which the value of A in the above equation (1) is 2.22×10 ^-2 mm ^-2 , and the period L of the light flux that meanders through this rod-shaped body (equation (2) ) was 42.5mm. Also,
Since this rod-shaped body had a refractive index distribution expressed by equation (1) almost up to the outer periphery, there was no need to shave off the periphery. Furthermore, the evaluation value as a convex lens, the numerical aperture NA, was large at 0.45.

Specific Example 2 Ethylene glycol dimethacrylate (EDMA) in which 0.10% by weight of BPO and 0.50% by weight of carbon tetrabromide (CBr ₄ ) were dissolved was heated at 45°C under a nitrogen atmosphere for 50 minutes.
Viscosity at 20℃ after heating for 930cp, K=3.23
A prepolymer with x10 ^-2 cm ² dyne ^-1 sec ^-1 and n=1.19 was obtained.

The obtained prepolymer 1 was placed in an extruder 2 in the same manner as in Example 1, and a Teflon tube was inserted through a heating jacket 3 in which hot water 5 at 60°C was poured into the upper part and hot water 6 at 30°C was poured into the lower part. It was continuously fed into a tube (inner diameter 4 mm, length 96 mm) 4 at a constant flow rate of 6.0 x 10 ^-2 ml/min. While passing through this Teflon tube 4, the prepolymer 1 was gelled and formed into a transparent cylindrical base material 7 with a diameter of 4 mm. This matrix 7 contains 15.5% by weight of a component insoluble in acetone (reticular polymer portion), 0.3% by weight of a component soluble in acetone and insoluble in methanol (linear polymer portion), and soluble in both acetone and methanol. Components (monomers and low molecular weight prepolymers)
It consisted of 84.2% by weight.

This base material 7 was then fed into a liquid phase diffusion chamber 9 into which 4FMA was injected at a constant flow rate of 1.0 ml/min. The temperature of this liquid phase diffusion chamber 9 was 60°C. While staying in this liquid phase diffusion chamber 9 for about 5 minutes, 4FMA was diffused into the base material 7. Also, in 4FMA (depth
24mm) at a flow rate of 200ml/min to evaporate 4FMA and fill the gas phase chamber 13.
Filled with 4FMA steam. Furthermore, this 4FMA vapor was collected at a flow rate of 800 ml/min. Gas phase chamber 13
was heated with 65°C hot water flowing through an outer tube (72 mm long). The base material 7 was allowed to stay in this gas phase chamber 13 for about 15 minutes.

After 4FMA was diffused and partially polymerized, the base material 7 was introduced into the heat treatment tube 14 to complete the heat polymerization. This heat-treated tube was heated to 65°C and 70°C by the heater 16.
A temperature gradient was created by heating to 100°C, 85°C and 100°C. In this way, desired rod-shaped light transmitters could be continuously manufactured. In this optical transmission body, the radius of the part with refractive index distribution is 1.68 mm (69% of the whole), A = 3.03 × 10 ^-2 mm ^-2 , L =
It was 36.1mm. The central portion with a diameter of 2.7 mm was a rod-shaped convex lens with a numerical aperture NA of 0.36.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a manufacturing apparatus that can be used to carry out the manufacturing method of the present invention, and FIG. 2 is a partially enlarged view of the manufacturing apparatus shown in FIG. 1. In addition, in the symbols used in the drawings, 1...prepolymer, 2...extruder, 3...heating jacket, 4...
Teflon tube, 7... Base material, 8... Diffusion device, 9
...liquid phase diffusion chamber, 13...vapor phase chamber, 14...heat treatment tube,
18... Optical transmission body.

Claims (1)

[Claims] 1. Monomer that produces a network polymer Pa having a refractive index of Na
A polymer that undergoes incomplete polymerization of Ma to form a matrix with self-shape retention, and has a refractive index of Nb different from the refractive index of Na.
A synthetic resin optical transmission body having a refractive index distribution, in which the monomer Mb that generates Pb and is in a liquid state is brought into contact with the surface of the base material and diffused into the interior thereof, and is further heated and polymerized. In the manufacturing method, the molding fluid obtained using the monomer Ma is fed into a molding tube to continuously form the self-shape-retaining base material in the molding tube, and then the self-shape-retaining base material is continuously formed from the molding tube. a liquid phase diffusion chamber containing the liquid monomer Mb; a monomer that is the same as or different from the monomer Mb;
Refraction that satisfies any one of the conditions (a) to (c) that is Mc and (a) Nc=Nb (b) Nc<Na and Nb<Na (c) Nc>Na and Nb>Na A monomer in the form of gas or droplets that forms a polymer Pc with a ratio Nc and is heated and controlled to a constant temperature.
A method for manufacturing a synthetic resin optical transmission body, characterized in that the material is sequentially passed through a vapor phase chamber containing Mc. 2. The synthetic resin optical transmission according to claim 1, wherein the gas phase chamber contains the monomer Mc in an amount corresponding to at least 20% of its saturation concentration. How the body is manufactured. 3. The method for manufacturing a synthetic resin optical transmission body according to claim 1, wherein the monomer Mc is the same as the monomer Mb.