JPS6232401A - Production of synthetic resin spherical lens - Google Patents

Abstract

PURPOSE:To form transparent spherical gel particles to be used as a base material for a graded index type spherical lens made of a synthetic resin so as to have a specified grain size by dropping the sols formed by a preliminary polymn. of a monomer by each drop and charging the sols in the stage of producing the above-mentioned particles by a suspension polymn. CONSTITUTION:The thoroughly spherical gel particles can be obtd. and the production in a large amt. at one time is possible if the suspension polymn. is adopted as a process for producing the transparent spherical gel particles. The coalescence and detachment of the particles during the suspension polymn. can be largely prevented if the preliminarily polymerized sols are charged in place of the monomer; therefore, the grain size fractions of the resultant gel particles can be substantially diminished. The sols are dropped by each drop in this stage and if the volume of one drop is uniform, the coalescence, detachment, etc. of the particles do not arise at all and the grain size of the resultant transparent gel particles is thoroughly constant. The synthetic resin spherical lenses each having the refractive index in which the refractive indices change in the normal direction from the center of the sphere toward the periphery are thus mass-produced by the subsequent diffusion and heat treatment stages.

Description

[Detailed description of the invention]! -/ Industrial Application Field The present invention relates to a method for manufacturing a synthetic resin ball lens having a refractive index distribution in which the refractive index changes in the normal direction from the center to the periphery of the sphere.

3-2 Description of the Prior Art As a lens having a refractive index distribution, a transparent rod-shaped body having a refractive index distribution that decreases in the radial direction approximately in proportion to the square of the distance from the central axis is known.

This transparent rod-shaped body has a convex lens effect, and its refractive index distribution is approximated by equation (1).

n (r)=n□ (/ //, 2 Ar2
In the formula (1), n (r) represents a refractive index at a point at a distance r from the central axis, n□ represents a refractive index at the central axis, and n represents a positive constant.

A light beam propagates in a meandering manner in such a transparent rod-shaped body, and its periodicity is expressed by equation (2).

L-coπ/V-cho (2) Also (3
) If it has a refractive index distribution that increases approximately in proportion to the square of the distance from the central axis, the transparent rod-like body becomes a light transmitting body having a concave lens effect.

n (r) = no (/+ //2 Br2)
(3) where n (r) and n. is the same as above, and B is a positive constant.

A method for manufacturing a synthetic resin optical transmitter having such a refractive index distribution was developed by Tokkosho! 2-3! ! ; Publication No. 7, JP-A-Sho! ;/
-/639g publication, JP-A-Sho! ;t! -//9939, etc.

3-3 Problems to be solved by the invention As mentioned above,
A cylindrical rod lens having a refractive index distribution in the radial direction is attracting attention as a light condensing and imaging element in the field of optoelectronics. However, if the optical axis of the rod lens is slightly shifted from the optical axis of the optical system, large aberrations occur due to skewed rays, which is currently a problem.

However, in the case of a spherical lens, there is no optical axis of the lens, so there is no skewed ray due to axis misalignment. A ball lens whose refractive index decreases from the center point to the outer periphery in an approximately square law distribution is embedded in a medium with an appropriate refractive index, or a rad with a uniform refractive index is placed around such a ball lens. If you use the attached one as a condensing element, it is possible to condense light with almost no rutting aberration.

However, in the prior art, it is extremely difficult to control the refractive index distribution spherically, and such a spherical lens has not yet been obtained. In order to manufacture a synthetic resin ball lens with a refractive index gradient, it is first necessary to obtain a spherical base material, but if the polymerized base material is used as the base material, monomers with different refractive indexes will be formed later. In the process of diffusing the metal, it is extremely difficult to diffuse it to the center of the base material. Therefore, as a base material,
Partially polymerized spherical transparent gel particles are used, but even if one attempts to obtain spherical transparent gel particles by bulk polymerization, it is difficult to obtain perfect spheres, and a large number of gel particles can be stabilized at once. It is also not suitable for mass production, as it is impossible to obtain it.

Therefore, as a method for producing completely spherical transparent gel particles in large quantities at once, in a patent application filed in 1983, Otsuji Hiroshi described a method for obtaining transparent gel particles by charging monomers and carrying out suspension polymerization. It is being However, in the method disclosed in the above-mentioned publication, the problem remains that the particle size dispersion of gel particles is quite large.

Furthermore, a method of obtaining transparent gel particles by suspension polymerization by charging a prepolymerized sol instead of monomers is also being considered.This method makes it possible to considerably reduce the particle size dispersion of gel particles; still exist, and the particle size cannot be made constant.

3-G Means for solving the conventional problems When producing spherical transparent gel particles, which are the base material of the synthetic basin refractive index gradient sphere 1/ns, by suspension polymerization, the monomers were prepolymerized. Add the sol one drop at a time.

3-5 Effects of the invention If suspension polymerization is adopted as a method for producing spherical transparent gel particles, completely spherical gel particles can be obtained.
Moreover, it can be manufactured in large quantities at once. If a prepolymerized sol is used instead of the monomer, coalescence and separation of particles during suspension polymerization can be greatly suppressed, so the particle size fraction of the resulting gel particles can be significantly reduced. .

If the sol is added drop by drop and the volume of each drop is uniform, no coalescence or separation of the particles will occur, and the diameter of the resulting transparent gel particles will be completely constant.

Note that the maximum particle size is mainly determined by the surface tension and viscosity (ie, conversion rate) of the sol.

Therefore, through the subsequent diffusion and heat treatment process, a synthetic resin ball lens with a refractive index distribution in which the refractive index changes in the normal direction from the center to the periphery, as described above, has a constant performance at once. can be mass produced.

3-6 Examples Hereinafter, the method for manufacturing a synthetic spheroid ball lens according to the present invention will be explained based on examples.

First, a reticular polymer (including copolymer) with a refractive index of Na, Pa
The monomers (including a monomer mixture) to 1a forming the sol are prepolymerized at a predetermined temperature for 102 hours to produce a sol having fluidity prior to gelation. At this time, Sol
A state containing 3 to 30% of methanol-insoluble components (linear polymers) is desirable.

This sol consisting of the monomer Ma is dropped drop by drop into a predetermined container containing a solvent, a dispersant, etc. using a microsyringe, a micropump, etc., and the sol is charged at a predetermined temperature Tl''C1. Suspension polymerization is carried out at time t1 and stirring rotation speed r1 (rpm) to partially polymerize and produce a large amount of spherical transparent gel particles at once.At this time, the gel particles are a component insoluble in the solvent (reticular polymer). The polymerization is left in an uncompleted state containing 20 to 0% by weight of .

Since the spherical transparent gel particles produced as described above are dispersed in the polymerization system in a predetermined container, the polymerization system is suction-filtered to separate the transparent gel particles.

Next, the separated particles are treated with a refractive index N different from that of the Na.
A polymer (including a copolymer) having Pb is added to a melter containing a monomer (including a monomer mixture) Mb, and the sphere is heated at a predetermined temperature T2°C for 1 hour t2. The monomer Mb is diffused and polymerized from the surface of the sphere toward the center, and a refractive index distribution in which the refractive index changes continuously in the normal direction from the center to the periphery of the sphere is formed in the transparent gel particles. do.

Thereafter, in order to separate the transparent gel particles after diffusion from the monomer Mb, suction filtration is performed again. Then, in order to finally complete the polymerization, the temperature is set to T3° in a predetermined container.
The mixture is dispersed in water heated to C and heat-treated at a predetermined time t3 and stirring rotation fl r3 (rpm).

All synthetic resin ball lenses obtained in large quantities in this way have a refractive index distribution that continuously changes in the normal direction from the center to the periphery, and the particle size is constant. Therefore, it is possible to obtain a large amount of ball lenses with a certain level of performance at once.

When compared with ordinary spherical lenses with a uniform refractive index, these lenses correct not only spherical aberration but also comatic aberration.

The monomer Ma to be the raw material of the transparent gel object as the lens base material in the above embodiments 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 compounds Diallyl esters such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diethylene glycol bisallyl carbonate; triallyl trimellidate;
Triallyl esters such as triallyl phosphate and triallyl phosphite; unsaturated acid allyl esters such as allyl methacrylate and allyl acrylate.

(2) Compound R1 and R3 represented by 几1-R2-13 are both vinyl groups and acrylic groups.

A compound that is a vinyl ester group or a methacrylic group;
A compound in which either I'Ll or n3 is one of the three groups vinyl group, acrylic group, methacrylic group, and vinyl ester group, and the other is one of the remaining three groups . Here, R2 can be selected from the covalent groups shown below.
2-(CH2)P-(P-, 3~15) (OI(2)iH -CH2-Q-OH2-(i, j = /~3) (O)
+2 Contains 1 H ■( (3) A mixture of the monomers (1) and (2) above, or at least 7 of monovinyl compounds, hinyl esters, acrylic esters, and methacrylic esters!;@ and the monomer (or mixture thereof) of (1) or (2) above.

Furthermore, examples of the monomer Mb include the following.

(4) CH2-C-C! A compound represented by OOY, where X is a hydrogen atom or a methyl group, -(CH2)
lH (ly~l), 1-propyl group, 1-butyl group,
S-butyl group, t-butyl group.

and -(OH20H20) p 01(20H3(1
) -/-4), or -(
CF'2)a -F'(a-7~Otsu), -0
H2(OF2)bH(b-/~,r).

-0H20H20-OH20F3, - (OH20H
20) C0F20F2H (c= /~II),
-0H20H20・OH2(OF2) aF(a-/-
6) , -0H2(OF2) dO(OF2) l
F (d-/~j.

Represents a group selected from the group consisting of 1-/S-ri and -s 1 (002H,,)3.

(5) A compound represented by OH2=OHOO-R4, where R4 is -(OHM) f OH3(f-0
~2).

Represents a group selected from the details.

(6) A mixture of the monomers (4> 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 explain the gelation state of the above transparent gel object in Section 11,
As mentioned in section (3), the method of adding a monomer having one non-foaming group to the crosslinkable monomer Ma, and 0Br4, 0O
14. A method of adding a chain transfer agent such as mercaptans,
Alternatively, a method of using both together is effective.

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

Test Example 1 First, 5po (benzoyl peroxide) O and Koku were added as an initiator to D-man I (diallyl isophthalate) (Na-/, 369) 109 as a monomer Ma, and then the temperature was set at To-90°C for an hour. A sol having fluidity prior to gelation was prepared by prepolymerizing to-62 molecules.

This sol contains components insoluble in methanol (m-sculpture combination) 20
It consisted of % by weight.

Next, water was used as a solvent, and PVA was used as a dispersant (
The above-mentioned sol was added drop by drop using a microsyringe into a flask equipped with a stirrer containing polyvinyl alcohol), and suspension polymerization was carried out at a temperature of tl-s for a time of tl-s, resulting in partially polymerized spherical transparent particles. Gel particles were produced in large quantities at once. These transparent gel particles contain 75% by weight of methanol-insoluble components (reticular polymer portion and linear polymer portion).
, 23% by weight of methanol-soluble components (monomers and a portion of low molecular weight prepolymer).

Next, the transparent gel particles produced above are filtered by suction to separate them from the polymerization system, and then the separated particles are placed in a container heated to a temperature T2-70°C.
MA (2,2,2-)lifluoroethyl methacrylate) (Nb-8!7210) added to 202, +2-7
Hold for a period of time to allow JP''MA to diffuse into the particles and simultaneously polymerize.

Thereafter, the particles after diffusion are again filtered by suction in order to separate them from jFMA. Finally, pour 0 sip into 200 liters of water in a container that is heated to a temperature of T3 - 90°C.
Rotation% r3 ”” 3! ;Orpm, time t3-
Polymerization was completed in jlJ time to obtain a synthetic snow resin ball lens whose refractive index changed continuously in the normal direction from the center to the periphery of the ball.

The resulting spherical lenses all have the desired diameter/,! ;mm
It was within a range of 0.03 mm.

Shape of the obtained synthetic resin gradient index spherical lens Test Example 2 First, the monomer ~4a had a DAI of 109. After adding 0.7% of Bl'O□ and 0.7% of DI3PO (di-tertiary-butyl peroxide) as an initiator, the mixture was heated to
-qO°C time to -70 minutes The molecular types were combined to obtain a sol.

This sol consists of meta/- crab insoluble component (linear polymer) 20
It consisted of % weightage.

Next, the above-mentioned sol was added drop by drop using a minute meter pump into a flask equipped with a stirrer containing water 2009 as a solvent and PVA (polyvinyl alcohol)/s9 as a dispersant. Suspension molding was carried out at -qo°C and rotational speed r1-100 rpm for times t and l-3 hours. A large amount of spherical gel particles were produced at one time. The transparent particles contain 75% by weight of methanol-insoluble components ('@-shaped aggregate portion and linear polymer portion) and methanol-soluble components (monomer and a portion of low molecular weight prepolymer). -5% by weight.

The transparent gel particles produced above are then suction filtered to separate them from the polymerization system, and the separated particles are then placed in a container heated to a temperature T of 2-70°C. ? FM
Add to A and hold for 60 minutes 1. ,? FMA was diffused into the particles and simultaneously polymerized.

Thereafter, the particles after diffusion were mixed between 3F and 1. To separate it from A, it is filtered again with suction. And finally the temperature T3-taO
It is added to 200ml of water containing PVA O,3 in a container heated to 'C, and the rotational speed is r3"JjOrpI!
Polymerization was completed in 1 hour t3-2t time 3 to obtain a synthetic resin ball lens whose refractive index changed continuously in the normal direction from the center to the periphery of the sphere.

The resulting spherical lenses all have the desired diameter! , '10mm
It was within the range of ±0.02 mm.

The refractive index distribution formed in the obtained synthetic fat-saving gradient refractive index ball lens was approximately a square distribution within 90% of the diameter, and the maximum refractive index difference was 0.05.

Patent applicant: Nippon Sheet Glass Co., Ltd.

Claims (1)

[Claims] 1) (A) Network polymer (including copolymer) with a refractive index of Na
A step of prepolymerizing Ma, a monomer (including a monomer mixture) that forms Pa, to form a sol that has fluidity before gelation. (B) A step of adding the Ma sol one drop at a time into a solvent and carrying out suspension polymerization, and further polymerizing to form spherical transparent gel particles. (C) A polymer having a refractive index Nb different from that of Na (
The spherical transparent gel particles are added to a monomer (including a monomer mixture) Mb that forms Pb (including a copolymer), and the monomer Mb is diffused from the surface of the sphere toward the center and polymerized. . Forming in the transparent gel particles a refractive index distribution in which the refractive index continuously changes from the center to the periphery of the sphere. (D) A method for manufacturing a synthetic resin gradient index ball lens, comprising the steps of fixing the refractive index distribution by completing polymerization by heating or the like. 2) A method for manufacturing a synthetic resin gradient refractive index type spherical lens, in which the sol according to claim 1 contains 3 to 30% of a methanol-insoluble component (linear polymer).