JPH0545502A - Process for production of synthetic resin optical element having graded index and precursor polymer used for this method - Google Patents

Abstract

PURPOSE:To provide the process for efficiently producing the synthetic resin optical element having graded index which is sufficient and uniform in an equal refractive index distribution surface with high accuracy. CONSTITUTION:This process for production of the synthetic resin optical element consists in injecting a monomer compsn. 2 contg. >=2 kinds of monomers varying in the refractive index and monomer reactivity ratio when made into a polymer into the space formed by installing two sheets of planar bodies 8 consisting of a precursor polymer contg. an undissolved polymn. initiator and constituting the outside surface part of the optical element apart a spacing or by installing the planar body 8 and another forming mold 9 apart a spacing or into the internal space of a pipe-shaped body 1 of the precursor polymer, then by heating the compsn. from the outer side of the precursor polymer or irradiating the same with light to initiate and progress the polymn. from the boundary between the precursor polymer and the monomer compsn.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a synthetic resin optical element having a refractive index distribution and a precursor polymer used in the method.

[0002]

2. Description of the Related Art As a synthetic resin optical element having a refractive index distribution, for example, a synthetic resin lens having a refractive index distribution in the optical axis direction for correcting aberration of a spherical lens is known. As a method for producing a material having a refractive index distribution, JP-A-60-149414 discloses a monomer containing at least two kinds of monomers having different refractive indexes and monomer reactivity ratios when they are made into a polymer. Holding the mixture of monomers in a container, allowing the polymerization reaction to proceed ubiquitously in said mixture, allowing the precipitated polymer to settle using gravity and / or inertial forces,
A method has been proposed in which the entire monomer mixture is made into a gel state and this is finally heated to complete the polymerization. However, in this method, the polymerization reaction proceeds ubiquitously,
In order to cause the precipitated polymer to settle due to gravity or inertial force, the polymerization reaction must proceed extremely slowly over a long period of several tens of days, and even if the material has a sufficiently uniform refractive index distribution surface. Therefore, improvement in accuracy is required.

Further, in JP-A-60-162611, light or an electron beam is irradiated from a direction perpendicular to one surface of a container containing a monomer mixture, and a polymerization reaction starts from the vicinity of the inner wall of the container. There is proposed a method of initiating the reaction, precipitating the produced copolymer on the inner wall of the reaction mixture, turning the entire monomer mixture into a gel state, and finally heating this to complete the polymerization. However, even with this method, it is required to make the uniform refractive index distribution surface more uniform and improve the accuracy.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently producing a synthetic resin optical element having a uniform refractive index distribution surface and a highly accurate refractive index distribution.

[0005]

The present invention achieves the above object by locally limiting the polymerization initiation reaction so that the location where the reaction occurs with the progress of the polymerization reaction moves with the increase of the polymerization conversion rate. .. That is, the above-mentioned object is achieved by forming the outer surface portion of the optical element to be manufactured with a precursor polymer, and further initiating and advancing the polymerization reaction from the surface portion of the precursor polymer.

The precursor polymer of the present invention is characterized in that it contains an undecomposed polymerization initiator and constitutes the outer surface portion of the optical element. Further, in the method for producing a synthetic resin optical element having a refractive index distribution of the present invention, two plate-like bodies of the above-mentioned precursor polymer are placed at intervals or the plate-like body and another molding die are installed. Two or more kinds of monomers having different refractive indices and monomer reactivity ratios when they become a polymer in a space installed at intervals or in an internal space of a pipe-shaped body of the above precursor polymer. Injecting a monomer composition containing, and starting the polymerization from the interface between the precursor polymer and the monomer composition by heating or irradiating light from the outside of the precursor polymer, to proceed. It is characterized by

The monomer which can be used in the present invention is preferably one which forms a transparent polymer, but even a homopolymer which tends to become opaque becomes transparent when copolymerized. Anything can be used. Examples of such a monomer include compounds having one or more polymerizable double bonds such as vinyl group, acryl group, methacryl group and allyl group, for example, vinyl chloride, vinyl fluoride, vinylidene chloride, fluorinated. Vinyl compounds such as vinylidene, vinyl acetate, vinyl phenylacetate, vinyl benzoate, vinyl naphthalene, vinyl α-naphthoate and vinyl β-naphthoate, styrene, α-methylstyrene,
Styrene derivatives such as p-chlorostyrene, methyl acrylate, ethyl acrylate, 2,2,2-trifluoroethyl acrylate, benzyl acrylate, phenyl acrylate, acrylates such as naphthyl acrylate, methyl methacrylate, Ethyl methacrylate, 2,2,2-trifluoroethyl methacrylate, benzyl methacrylate, phenyl methacrylate, methacrylic acid esters such as naphthyl methacrylate, acrylonitrile, methacrylonitrile, allyl benzoate, allyl compounds such as phenyl allyl ether. , Butadiene, 1,5-hexadiene, vinyl acrylate, vinyl methacrylate, divinyl phthalate, divinyl isophthalate, divinylbenzene, diallyl phthalate, diallyl isophthalate, allyl acrylate, meta Allyl acrylic acid, methacrylic acid β- methacrylate, methacrylic anhydride, diethylene glycol bis allyl ether, diethylene glycol bis allyl carbonate, tetraethylene glycol dimethacrylate, bisphenol A dimethacrylate, trimellitic acid triallyl, triallyl phosphate, triallyl phosphite,
Examples thereof include compounds having two or more polymerizable double bonds such as diphenyldiallylsilane and diphenyldivinylsilane.

In the present invention, among the above-mentioned monomers, two or more kinds of monomers having different refractive indexes and monomer reactivity ratios when formed into a polymer are used as the target refraction agents. It may be selected so as to form a rate distribution.

When two types of monomers are copolymerized, the following four types of growth reactions occur competitively. M ₁ ^. + M ₁ → M ₁ ^. (Reaction rate constant k ₁₁ ) M ₁ ^. + M ₂ → M ₂ ^. (Reaction rate constant _k 12) _M ^2. + M ₁ → M ₁ ^. (Reaction rate constant _k 21) _M ^2. + M ₂ → N ₂ ^. (Reaction rate constant k ₂₂ ) At this time, the monomer reactivity ratio γ is defined by the following formula. γ ₁ = k ₁₁ / k ₁₂ γ ₂ = k ₂₂ / k ₂₁

For example, when the reactivity ratios are selected such that γ ₁ > 1, γ ₂ <1, the monomer M ₁ is M ₁ ^. For M ₂ ^. Is also more reactive than the monomer M ₂ . That is, it means that the monomer M ₁ is preferentially polymerized at the beginning of the polymerization reaction, and when the amount of the monomer M ₁ is reduced as the reaction progresses, the amount of the monomer M ₂ is gradually increased. Therefore, if the starting place of the polymerization reaction is limited by using monomers having different refractive indexes when it becomes a polymer and the progress of the reaction is controlled, a refractive index distribution due to the monomer composition change is formed. ..

The precursor polymer may be itself a part of an optical element to be finally formed, or may be simply a starting point of polymerization. In the case of the former, two or more kinds of monomers are appropriately selected from the viewpoints of the refractive index and the monomer reactivity ratio when it becomes a polymer, and at least one of those monomers is selected. It is used to produce a precursor polymer that constitutes the outer surface of the optical element to be produced.

In any case, in the present invention, together with one or more kinds of monomers necessary for producing the precursor polymer, a polymerization initiator necessary for polymerization of the monomers (low temperature polymerization initiator) , A photopolymerization initiator) and a polymerization initiator to be left undecomposed in the precursor polymer. Conventional additives such as a polymerization modifier and a sensitizer can be added to this composition.

The polymerization initiator to be contained in the monomer composition for producing the precursor polymer is one which initiates the polymerization of the monomer and which is not involved in the polymerization at this time, And a polymerization initiator necessary for initiating the polymerization at the interface of the precursor polymer are used. For example, a combination of two kinds of thermal decomposition polymerization initiators having different thermal decomposition temperatures, a thermal decomposition polymerization initiator and a photopolymerization initiator, an organic peroxide having a copolymerizability with the thermal decomposition polymerization initiator, and the like can be used. ..
Some specific examples of the polymerization initiator that can be used in the present invention are shown below, but it may be appropriately selected from these.

As the thermal decomposition polymerization initiator, there are organic peroxides and azo compounds. In any case, two or more kinds having different thermal decomposition temperatures are used, and the polymerization initiator having the lower thermal decomposition temperature is used. Is involved in the production of the precursor polymer, and one having a higher thermal decomposition temperature remains in the precursor polymer and should be selected so as to help start the polymerization at the interface of the precursor polymer thereafter.

As the organic peroxide type polymerization initiator that can be used, isobutyl peroxide, diisopropyl peroxydicarbonate, dimyristyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, di (2- Ethylhexyl) peroxydicarbonate, t-butyl peroxyneodecanate, 2,
4-dichlorobenzoyl peroxide, t-butylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, t-butylperoxy (2-ethylhexanoate), benzoyl peroxide, t -Butyl peroxyisobutyrate, 1,1-
Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, cyclohexanone peroxide, t
-Butyl peroxy acetate, t-butyl peroxy benzoate, etc. are mentioned.

As the azo compound-based polymerization initiator which can be used, 2,2, -azobis (4-methoxy-2,2
4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis [2-
(2-Imidazolin-2-yl) propane], 1,1 ′
-Azobis (cyclohexane-1-carbonitrile) and the like.

As the photopolymerization initiator which can be used,
4-phenoxydichloroacetophenone, diethoxyacetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone and the like can be mentioned.

Further, an organic peroxide having a copolymerizability may be used, and examples thereof include t-butylperoxyallyl carbonate and the like.

The polymerization initiator required for the polymerization of the monomer to form the precursor polymer of the present invention is usually added to the monomer composition in an amount of 0.01 to 5% by weight. The amount of the polymerization initiator to be left in the precursor polymer is usually 0.05
It is set to 10 to 10% by weight, preferably 0.1 to 5% by weight. If this amount is less than 0.05% by weight, the effect of the residual polymerization initiator will not be exhibited, and it will be incomplete to locally limit the polymerization initiation reaction, and if it exceeds 10% by weight, copolymerization will occur. The polymerization initiation reaction and the growth reaction in (3) are likely to occur rapidly, making it difficult to control the desired refractive index distribution.

In order to produce the precursor polymer of the present invention, the above monomer composition may be heated to a relatively low temperature to initiate the polymerization, and the polymerization reaction may be gradually advanced. ..
As a method for producing this precursor polymer, generally, first, a monomer composition containing a monomer, a low-temperature polymerization initiator, a polymerization initiator to be left in the polymer and a polymerization modifier is heated. The polymerization may be carried out. Further, a monomer composition containing a monomer, a low temperature polymerization initiator and a polymerization regulator is preliminarily preliminarily polymerized for about 1 hour to give a viscous liquid mixture. A method of adding a polymerization initiator to be left undecomposed in a precursor polymer such as a polymerization initiator or a polymerization initiator having a copolymerizability, and further polymerizing the resulting mixture and molding are also preferable. ..

The polymerization temperature can be appropriately determined depending on the type of monomer used and the type of polymerization initiator, but should be selected so that the polymerization reaction does not proceed rapidly but gradually. Further, the polymerization time may be such that a polymerization product having a self-shape retaining property is obtained although the polymerization reaction is not completed.
It is usually 10 to 30 hours.

When producing a precursor polymer containing a photopolymerization initiator, it is necessary to carry out the polymerization reaction in a dark place in order to prevent decomposition of the photopolymerization initiator.

Similarly, the polymerization of the monomers constituting the precursor polymer may be carried out using a photopolymerization initiator to obtain a precursor polymer in which the thermally decomposable polymerization initiator remains.

The precursor polymer of the present invention is formed into a plate or pipe. The molding method is not particularly limited, a casting method depending on the shape of the precursor polymer to be produced,
A centrifugal polymerization molding method or the like can be applied. Centrifugal polymerization molding is suitable for forming into a pipe.
In addition, the thickness of the precursor polymer can be appropriately designed according to the size and refractive index distribution of the optical element to be manufactured.

When an optical element having a refractive index distribution is produced using the thus obtained precursor polymer of the present invention, two plate-like bodies of the above precursor polymer are placed at intervals. Or, in the space where the plate-shaped body and another molding die are installed with a space, or inside the pipe-shaped body of the precursor polymer, the refractive index and the monomer when it becomes a polymer. By injecting a monomer composition containing two or more kinds of monomers having different reactivity ratios and heating or irradiating with light from the outside of the precursor polymer, the precursor polymer and the monomer composition Polymerization proceeds from the interface with the product.

When the monomer composition is injected by the method of the present invention, the inner wall surface of the precursor polymer swells slightly, and upon heating or irradiation of light, polymerization remaining in the precursor polymer. The initiator acts on the monomer composition, causes a polymerization reaction at the interface between the precursor polymer and the monomer composition, and gradually moves to the place of the polymerization reaction. At this time, the polymerization of the precursor polymer is also completed. Thus, according to the present invention, the polymerization initiation site can be geometrically limited by the production of the precursor polymer as the first step, and the interface between the precursor polymer and the monomer composition as the second step. Since it can be limited to a part, the uniform refractive index surface is formed.

In the above-mentioned method, when a copolymerizable organic peroxide is used as the remaining polymerization initiator when the precursor polymer is produced, this peroxide mainly constitutes the precursor polymer. As a copolymerization component with the monomer to be present, it is fixed and present in the polymer as it is without being decomposed. Therefore, when the monomer composition is polymerized using the precursor polymer,
There is no diffusion of residual polymerization initiator due to slight swelling of the inner wall,
The place where the polymerization of the second stage is initiated is more precisely limited.

The monomer composition to be injected may contain a polymerization regulator, a polymerization initiator, a sensitizer, etc., if necessary.

Further, the polymerization temperature and the polymerization time can be appropriately selected according to the kind of the monomer and the polymerization initiator used. Furthermore, when a photopolymerization initiator is used,
After photopolymerization, it is preferable to further heat to fix the composition distribution formed by photopolymerization.

Next, an embodiment of a method for manufacturing an optical element according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a manufacturing process of a cylindrical optical element material of the present invention by heat polymerization. The bottom plug 3 is attached to the lower end of the pipe-shaped precursor polymer 1, the monomer composition 2 is injected into the internal space, and the heating device 4
To heat and start the polymerization reaction. The heating device 4 needs to have a configuration capable of uniformly heating the outer surface of the pipe-shaped precursor polymer 1. In this embodiment, the pipe-shaped precursor polymer 1 swells at the contact portion with the monomer composition 2, and a part of the high-temperature heat-decomposable polymerization initiator remaining in the polymer is a single amount. It becomes a state in which it easily acts on the monomer by being dissolved in the body composition 2. Then, when heated by the heating device 4, the polymerization reaction will start at the interface 1A between the pipe-shaped precursor polymer 1 and the monomer composition 2, and the location will move as the polymerization reaction proceeds. A distribution of the monomer composition is generated according to the reactivity ratio of the monomers, and an optical element material having a refractive index distribution is obtained.

FIG. 2 is a cross-sectional view showing the manufacturing process of the cylindrical optical element material of the present invention by photopolymerization. In FIG. 2, the monomer composition 2 injected into the internal space of the pipe-shaped precursor polymer 1 is irradiated with light from the light source 5,
In order to uniformly proceed the polymerization, it is necessary to irradiate light with the same intensity on the same thickness, so that the parallel light 7 is vertically irradiated onto the surface of the pipe-shaped precursor polymer 1, so that the optical system is 6 is preferably installed. In this embodiment, the photopolymerization initiator contained in the pipe-shaped precursor polymer 1 in an undecomposed state is the interface 1A of the swollen precursor polymer.
At the interface 1A, the polymerization reaction is initiated by irradiation with light, and the location of the polymerization reaction is moved to the central portion. As the light source, for example, a high pressure mercury lamp, an ultra high pressure mercury lamp or the like can be used.

FIG. 3 is a cross-sectional view showing the manufacturing process of the plate-shaped optical element material of the present invention by thermal polymerization. In FIG.
The monomer composition 2 is injected between the plate-shaped precursor polymer 8 and the glass plate 9, and the spacer 10 is plugged. Monomer composition 2
Is a heating device 1 installed below the plate-like precursor polymer 8.
Heated by 1. In this case, the polymerization reaction starts at the interface 8A by the action of the high-temperature pyrolyzable polymerization initiator contained in the precursor polymer, and gradually moves toward the glass plate.

[0033]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto.

EXAMPLE 1 t-Butylperoxyneodecanate (10-hour half-life temperature 46.
(5 ° C) and 0.5% by weight of n-butyl mercaptan as a polymerization regulator were added, and prepolymerization was performed at 60 ° C for 1 hour to obtain a viscous syrup.

As a high-temperature polymerization initiator, 1,
0.5% by weight of 1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane (10-hour half-life temperature 90 ° C.) was added, and the mixture was poured into a nitrogen-substituted glass tube having an inner diameter of 10 mm and centrifuged. After the polymerization reaction was carried out at 60 ° C. for 20 hours by the polymerization molding method, the glass tube was taken out and the outer diameter was 10
mm, a pipe-shaped precursor polymer having an inner diameter of 5 mm was obtained.

Next, in a mixture of 80 parts by weight of methyl methacrylate and 20 parts by weight of vinyl benzoate, 0.2% by weight of n-butyl mercaptan and 1,1-bis (t-butylperoxy) 3,3,5-. Trimethylcyclohexane 0.0
The monomer composition added with 5% by weight was injected into the internal space of the pipe-shaped precursor polymer and heated from the periphery at 80 ° C. for 20 hours and then at 100 ° C. for 10 hours to obtain a columnar polymer. It was

The obtained polymer had a refractive index distribution in which the refractive index gradually decreased from the central axis to the periphery, and was effective as an optical element material. The refractive index distribution of the obtained optical element material is shown in FIG.

Example 2 0.5% by weight of benzoyl peroxide (10-hour half-life temperature: 74 ° C.) as a thermal decomposition polymerization initiator and 0.2% of n-butyl mercaptan as a polymerization regulator were added to methyl methacrylate.
% By weight and prepolymerized at 70 ° C. for 1 hour to obtain a viscous syrup.

To this syrup was added 0.5% by weight of benzyl dimethyl ketal as an ultraviolet polymerization initiator, and the mixture was poured into a nitrogen-substituted glass tube having an inner diameter of 5 mm and polymerized at 70 ° C. for 20 hours in a dark place by a centrifugal polymerization molding method. After the reaction, it was taken out from the glass tube to obtain a pipe-shaped precursor polymer having an outer diameter of 5 mm and an inner diameter of 3 mm.

Next, a monomer composition prepared by adding 0.01% by weight of benzyl dimethyl ketal to a mixture of 80 parts by weight of methyl methacrylate and 20 parts by weight of vinyl benzoate was injected into the internal space of the pipe-shaped polymer. A resin having a refractive index distribution was formed by uniformly irradiating ultraviolet rays from the periphery with an ultra-high pressure mercury lamp. Then again 90
The composition distribution formed by photopolymerization was fixed by heating at 0 ° C. for 10 hours.

The obtained polymer had a refractive index distribution in which the refractive index gradually decreased from the central axis to the periphery, and was effective as an optical element material.

Example 3 A mixture of 95 parts by weight of methyl methacrylate and 5 parts by weight of t-butylperoxyallylcarbonate was added to 0.5% by weight of t-butylperoxyneodecanate as a polymerization initiator and n-as a polymerization regulator. 0.2 wt% of butyl mercaptan was added and prepolymerized at 60 ° C. for 1 hour to obtain a viscous syrup.

This syrup was replaced with nitrogen to have an inner diameter of 10 m.
m into a glass tube and subjected to a polymerization reaction at 60 ° C. for 20 hours by a centrifugal polymerization molding method, and then taken out from the glass tube to obtain a pipe-shaped precursor polymer having an outer diameter of 10 mm and an inner diameter of 5 mm.

Next, in a mixture of 80 parts by weight of methyl methacrylate and 20 parts by weight of vinyl benzoate, 0.2% by weight of n-butyl mercaptan and 1,1-bis (t-butylperoxy) 3,3,5- Trimethylcyclohexane 0.0
The monomer composition added with 5% by weight was injected into the internal space of the pipe-shaped precursor polymer and heated from the periphery at 80 ° C. for 20 hours and then at 100 ° C. for 10 hours to obtain a columnar polymer. It was

The obtained polymer had a refractive index distribution in which the refractive index gradually decreased from the central axis to the periphery, and was effective as an optical element material.

Example 4 0.5% by weight of t-butylperoxyneodecanate as a low temperature polymerization initiator in methyl methacrylate and 1,1-bis (t-butylperoxy) 3 as a high temperature polymerization initiator
0.05% by weight of 3,5-trimethylcyclohexane,
0.2% by weight of n-butyl mercaptan was added as a polymerization regulator, and the resulting mixture was poured into a reaction vessel composed of two glass plates and a gasket, reacted at a temperature of 50 ° C. for 20 hours, and then heated to a high temperature inside. 3mm thickness where the polymerization initiator remains
A plate-shaped precursor polymer of was obtained.

The obtained polymer and a glass plate were placed at a distance of 3 mm (see FIG. 3), and a mixture of 80 parts by weight of methyl methacrylate and 20 parts by weight of vinyl benzoate was added to the inside thereof to prepare n-butyl mercaptan. 0.2% by weight and 1,1
-Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane 0.05% by weight of the monomer composition was added and injected at 70 ° C for 20 hours and then at 100 ° C for 10 hours.
After heating for a time, the mold was released to obtain a plate-like polymer having a refractive index distribution.

Example 5 Methyl methacrylate was obtained by adding 0.5% by weight of benzyl dimethyl ketal as an ultraviolet polymerization initiator and 0.5% by weight of tert-butyl peroxyneodecanate as a thermal decomposition polymerization initiator. The mixture was poured into a reaction vessel composed of two quartz plates and a gasket, and ultraviolet rays were irradiated from both sides to obtain a plate-shaped precursor polymer having a thickness of 2 mm, in which a thermal decomposition polymerization initiator remained.

The obtained polymer and a glass plate were placed at a distance of 3 mm, and methyl methacrylate 80 was placed inside the polymer.
A monomer composition prepared by adding 0.2% by weight of n-butyl mercaptan and 0.05% by weight of tert-butyl peroxyneodecanate to a mixture of 20 parts by weight of vinyl benzoate and 60 parts by weight of tert-butyl peroxyneodecanate was added. After heating for 20 hours and then at 90 ° C. for 10 hours, the mold was released to obtain a plate-like polymer having a refractive index distribution.

[0050]

According to the present invention, by using a precursor polymer containing an undecomposed polymerization initiator, a synthetic resin optical element having a refractive index distribution can be easily and efficiently manufactured. Further, the time required for its production has been conventionally 20 to 60 hours, while it was conventionally several tens of days, which is remarkably shortened. Furthermore, the obtained optical element has a highly uniform surface of equal refractive index and has high accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a cylindrical optical element by thermal polymerization according to the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of a cylindrical optical element by photopolymerization according to the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of a plate-shaped optical element by thermal polymerization according to the present invention.

FIG. 4 is a graph showing the refractive index distribution of the cylindrical optical element obtained in Example 1 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipe-shaped precursor polymer 1A Interface 2 Monomer composition 4 Heating device 5 Light source 6 Optical system 7 Parallel light 8 Plate precursor polymer 8A Interface 9 Glass plate 10 Spacer 11 Heating device

Claims (10)

[Claims] 1. A precursor polymer containing an undecomposed polymerization initiator and constituting an outer surface portion of an optical element. 2. The precursor polymer according to claim 1, wherein the undecomposed polymerization initiator is a thermal decomposition polymerization initiator which acts at a higher temperature than the polymerization initiator used for forming the precursor polymer. 3. The precursor polymer according to claim 1, wherein the undegraded polymerization initiator is a photopolymerization initiator. 4. The precursor polymer according to claim 1, wherein the undecomposed polymerization initiator is a polymerization initiator having copolymerizability. 5. The precursor polymer according to claim 1, wherein the undecomposed polymerization initiator is a thermal decomposition polymerization initiator, and a photopolymerization initiator is used for forming the precursor polymer. 6. The precursor polymer according to any one of claims 1 to 5, which has a plate-like or pipe-like shape. 7. The plate-like body 2 of the precursor polymer according to claim 1.
Different in refractive index and monomer reactivity ratio when becoming a polymer in the space where the sheets are placed at intervals or the plate and another mold are placed at intervals. Polymerization from the interface between the precursor polymer and the monomer composition by injecting a monomer composition containing one or more kinds of monomers and heating or irradiating with light from the outside of the precursor polymer. 1. A method for producing a synthetic resin optical element having a refractive index distribution, which comprises: 8. At least one of the two or more monomers is the same as the monomer constituting the precursor polymer.
A method for producing the synthetic resin optical element described. 9. The internal space of the pipe-shaped body of the precursor polymer according to claim 1, containing two or more kinds of monomers having different refractive indexes and monomer reactivity ratios when converted into a polymer. By injecting the monomer composition and heating or irradiating light from the outside of the precursor polymer, the polymerization is started from the interface between the precursor polymer and the monomer composition and allowed to proceed. A method for manufacturing a synthetic resin optical element having a characteristic refractive index distribution. 10. At least one of two or more monomers
The method for producing a synthetic resin optical element according to claim 9, wherein the seed is the same as the monomer constituting the precursor polymer.