JP7133166B2 - Manufacturing method of optical material - Google Patents

Description

The present invention relates to a method for producing an optical material containing an olefin polymer.

Olefin polymers are industrially manufactured by various methods due to their high industrial utility value, and the annual production is said to exceed 100 million tons. Since olefin polymers are mainly composed of carbon and hydrogen, they are also characterized by being stable and inexpensive materials. On the other hand, the structure having no functional group in the olefin polymer has poor affinity with polar materials, and also has properties such as colorability and adhesiveness that are difficult to modify.

As a method of modifying an olefin polymer (method of introducing a functional group), a method of grafting maleic anhydride using a radical generator is known. There is a limit to the amount of functional groups introduced. As a solution to this problem, there is an example of a modification method using a solid-phase reaction. (For example, Patent Document 1)

On the other hand, cyclic olefin polymers are used for optical articles such as lenses, taking advantage of their properties such as high transparency and heat resistance (high glass transition temperature). Examples of the lens include a DVD pickup lens. For lens applications, it may be necessary to form various films on the surface. In this case, it is also known that, from the viewpoint of adhesion to the film, introduction of a functional group into the olefin polymer constituting the lens substrate may be required.

International Publication No. 2015/166939 pamphlet

However, it seems that the current situation is that the problem such as the decrease in the molecular weight of the olefin polymer cannot be sufficiently solved. A decrease in molecular weight may lead to various negative factors such as a decrease in strength as a material. For example, when the shape of the optical material is a film, it may lead to a decrease in durability as well as strength. In addition, it is conceivable that the narrower molecular weight distribution reduces moldability, making it difficult to apply to complicated shapes.

On the other hand, depending on the application of the olefin polymer, there are cases in which it is sufficient, for example, to partially modify the olefin polymer molded article. The lens described above is a typical example, and if functional groups can be introduced only on the surface after molding, it is advantageous for stably forming a surface layer such as an antireflection layer or an anti-scratch film. It can also be expected to suppress the influence on the optical characteristics of .

The present inventors have found that if only the surface of an optical material containing an olefin polymer can be modified, or only at specific locations, it will be possible to increase the modification effect while suppressing the deterioration of the strength and optical properties. I thought I could expect it.

An object of the present invention is to provide a method for efficiently producing an optical material containing an olefin polymer, preferably modified mainly at a specific site.

In order to solve the above problems, the inventors of the present invention have conducted research, and as a result, it has become possible to efficiently denature, preferably mainly a specific portion of an optical material, by means shown below. It has become possible to provide a superior optical material. That is, the present invention is as follows.

[1]
Atoms (α) of elements selected from group 15 elements and group 16 elements and atoms (β) of group 17 elements in one molecule are atom (α): atom (β) = 1: 1 ~ Including step 1 of irradiating light to the radicals contained in a ratio of 4: 1,
A method for producing an optical material by modifying an optical material base material containing an olefin polymer having a melting point and/or a glass transition temperature of 70° C. or more and 300° C. or less.

[2]
The step 1 is
In an environment where the optical material base and the radicals coexist,
The method for producing an optical material according to [1] above, wherein the step of modifying the optical material substrate by irradiating the radical with light.

[3]
The method for producing an optical material according to [2], wherein the step 1 is a step of irradiating the optical material substrate and the radicals with light.

[4]
The method for producing an optical material according to any one of [1] to [3], wherein part of the optical material is in an undenatured state.

[5]
The method for producing an optical material according to any one of [1] to [4], wherein the optical material has a thickness of 200 μm to 20 cm.

[6]
The method for producing an optical material according to any one of [1] to [5], wherein the radical is a chlorine dioxide radical.

[7]
The method for producing an optical material according to any one of [1] to [6], wherein the olefin polymer is a cyclic olefin polymer.

[8]
The method for producing an optical material according to any one of [1] to [7], wherein the optical material is a base material for lenses.

[9]
The method for producing an optical material according to [8], wherein the lens is a lens for an in-vehicle sensor.

According to the production method of the present invention, it is expected that mainly only the surface or a specific portion of an optical material containing an olefin polymer can be efficiently modified. Therefore, it is possible to suppress the decrease in the molecular weight of the olefin polymer that mainly forms the optical material, and to provide an optical material excellent in surface modification properties while maintaining the strength and optical properties inherent in the optical material. it is conceivable that.

FIG. 1 is a schematic diagram for explaining the operation of the embodiment.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the invention is not limited by the following description.
The method for producing an optical material according to the present invention comprises
Atoms (α) of elements selected from group 15 elements and group 16 elements and atoms (β) of group 17 elements in one molecule are atom (α): atom (β) = 1: 1 ~ Including step 1 of irradiating light to the radicals contained in a ratio of 4: 1,
A method for producing an optical material by modifying an optical material base material containing an olefin polymer having a melting point and/or a glass transition temperature of 70° C. or more and 300° C. or less.

In the present invention, for the sake of convenience, the optical material before modification is referred to as "optical material substrate", and the optical material after modification is referred to as "optical material".
The step 1 is preferably a step of modifying the optical material substrate by irradiating the radicals with light in an environment where the optical material substrate and the radicals coexist.

In step 1, preferably, the optical material substrate and the radicals are irradiated with light. The phrase "the optical material substrate and the radicals are irradiated with light" does not mean that the optical material substrate and the radicals are irradiated with light independently. means that the optical material substrate and the radicals are irradiated with the light of . Further, it is preferable that the optical material substrate and the radicals are irradiated with light at the same time.

As will be described later, not only the portion of the optical material substrate irradiated with light is denatured, but the peripheral portion and deep layer portion thereof may also be denatured.
As the production method of the present invention, there is also a mode in which after the system containing the radical is irradiated with light, the system and the optical material substrate are brought into contact to modify the optical material substrate.

The radicals contain atoms (α) of elements selected from group 15 and group 16 elements and atoms (β) of group 17 elements in a specific composition ratio.
The radical may contain two or more Group 15 element atoms, may contain two or more Group 16 element atoms, and may contain one or more Group 15 element and Group 16 element atoms. It may contain two or more Group 17 element atoms. However, in these cases, the atomic number ratio is the ratio between the total number of atoms of group 15 and group 16 elements and the total number of atoms of group 17 elements.

Elements selected from group 15 elements and group 16 elements are preferably nitrogen, oxygen and sulfur, and particularly preferably oxygen.
The Group 17 element preferably includes chlorine, bromine and iodine, more preferably chlorine and bromine. Chlorine-containing radicals are more preferred, partly because they are readily available or easily generated. When radicals containing chlorine are used, the light to be irradiated in step 1 is preferably light containing ultraviolet rays, and when radicals containing bromine or iodine are used, it is believed that even light with a longer wavelength than ultraviolet rays can cause the reaction to proceed. . Therefore, bromine and iodine are preferable depending on the degree of freedom of light selection and the possibility of photodegradation of the olefin polymer constituting the optical material substrate.

The atomic number ratio (atom (α):atom (β)) in the radical is preferably 1:1 to 2:1, more preferably 1:2.
From the above point of view, chlorine dioxide radicals are preferable as the radicals. It is considered that chlorine radicals (Cl.) and oxygen molecules (O ₂ ) are generated by irradiating chlorine dioxide radicals (ClO ₂ .) with light.

In the production method of the present invention, known olefin polymers can be used without limitation as long as they have a melting point and/or a glass transition temperature of 70° C. or higher and 300° C. or lower as the olefin polymer constituting the optical material substrate. A preferred lower limit for the melting point and/or glass transition temperature is 80°C. On the other hand, the preferred upper limit of the melting point and/or glass transition temperature is 250°C, more preferably 200°C.

The melting points and glass transition temperatures mentioned above are those measured using a differential scanning calorimeter (DSC apparatus) by the following method or an equivalent method.
Using an EXSTAR DSC6220 differential scanning calorimeter manufactured by SII Nano Technology Co., Ltd. (currently Hitachi High-Tech Science Co., Ltd.), a sample of about 5.0 mg was heated from 30 ° C. to 320 ° C. at a heating rate of 10 ° C./min in a nitrogen atmosphere. Warm and hold at temperature for 10 minutes. (However, in the case of a polymer that decomposes in the temperature range of 250° C. or higher and 320° C. or lower, the temperature to be maintained may be appropriately adjusted to a lower temperature as usual.) Furthermore, the temperature is lowered to 30° C. at a rate of 10° C./min. After cooling and holding at that temperature for 5 minutes, the temperature is raised to 320°C at a heating rate of 10°C/min. The endothermic peak observed during the second temperature rise is defined as the melting peak, and the temperature at which the melting peak appears is determined as the melting point (Tm). When the melting peaks are multimodal, the temperature at which the highest melting peak appears is taken as the melting point.

Further, the glass transition temperature (Tg) is sensed in the form that the DSC curve bends due to the change in the specific heat during the second temperature rise and the baseline shifts in parallel. The temperature at the intersection of the tangent line of the baseline at a temperature lower than the bend and the tangent line of the point where the inclination is maximum at the bend is defined as the glass transition temperature (Tg).

Other differential scanning calorimeters may be used provided they have been shown to give results equivalent to the apparatus described above.
Specific examples of the olefin polymer include copolymers of cyclic olefins such as norbornene and tetracyclododecene and α-olefins selected from ethylene, propylene, butene and the like. Other examples include, of course, ring-opening olefin metathesis polymers obtained by metathesis-polymerizing the aforementioned cyclic olefins and hydrogenated products thereof. Commercially available products of these polymers include Zeonex®, Arton®, Topas®, APEL®, and the like.

The intrinsic viscosity [η] of these polymers in decalin at 135° C. is in the range of 0.5 to 20 dl/g, more preferably 0.8 to 18 dl/g, and still more preferably 1 to 15 dl/g. preferable. In addition, the melt flow rate of the olefin polymer measured according to the ASTM 1238 standard varies depending on the melting point of the resin used, as will be described later, but the preferred range of the melt flow rate is from 0.1 to 200 g/10 minutes. A preferred lower limit is 1 g/10 minutes, more preferably 3 g/10 minutes, and even more preferably 5 g/10 minutes. On the other hand, the upper limit is preferably 150 g/10 minutes, more preferably 100 g/10 minutes.

Preferred measurement conditions for the melt flow rate (ASTM1238 standard) are as follows. 190°C, 2.16 kg load for ethylene polymer, 230°C, 2.16 kg load for propylene polymer, 260°C, 5 kg load for 4-methyl-1-pentene polymer In the case of a cyclic olefin polymer, 260° C. and a load of 2.16 kg are preferred.

When the optical material substrate used in the present invention and the optical material obtained by modifying the optical material substrate by light irradiation are in the form of a film, the thickness thereof is 1 to 500 μm, more preferably 5 to 200 μm. , more preferably 10 to 150 μm. On the other hand, when a lens or light guide plate needs to be thick, the thickness is preferably 500 μm to 20 cm, more preferably 800 μm to 15 cm, still more preferably 1 mm to 12 cm. Although the thickness of the optical material is determined depending on its use, the thickness within the above range is advantageous for improving functions such as surface properties while maintaining a balance between optical properties and mechanical properties. Although it depends on the wavelength of the light used and the light absorption properties of the olefin polymer, it is obvious that if the molded article is too thick, it is disadvantageous from the viewpoint of optical properties.

There are many reports on means for obtaining such olefin polymers, and they can be employed without restriction. For example, it is disclosed in Japanese Unexamined Patent Application Publication No. 2010-235719.
In the production method of the present invention, for example, aromatic vinyl compounds such as styrene, (meth)acrylic acid (esters), and the like are used together with the cyclic olefins or α-olefins as olefins in the raw material of the olefin polymer. good too.

The optical material substrate can be produced by a known method. Representative examples of the method for producing the optical material substrate include extrusion molding (such as T-die molding), injection molding, and cast molding. Moreover, when the optical material substrate is a film, it is also possible to stretch the film after molding the film by these methods. For thicker shapes, known methods such as injection molding and cast molding are preferred.

When an optical material is produced from such a cyclic olefin polymer, its excellent optical properties may be impaired if a large amount of shear is applied during molding. Therefore, the present invention in which an optical material is produced by selectively and efficiently modifying the surface of a molded body (i.e., optical material substrate) of a cyclic olefin polymer or the like as in the present invention, It can be said that this is the preferred technique.

The olefin polymer constituting the optical material obtained by the production method of the present invention typically includes a hydroxy group, a carboxyl group, an aldehyde group, a carbonyl group, an ether bond, an ester bond, -C(=O)OOH, and At least one functional group selected from the group consisting of -O-O- is introduced.

The light irradiation is performed on the radicals existing in the aqueous phase, the organic phase, or the gas phase. When emphasizing the reduction of the load on the environment and the influence on the human body, it is preferable to carry out the above-mentioned radicals existing in the water phase or the gas phase. Step 1, in one embodiment, may be in an environment in which two or more phases of aqueous, organic and gaseous phases are present. Further, for example, when the radicals exist in the liquid phase, the optical material base may also exist in the liquid phase, but may exist in other phases such as the gas phase.

Although the concentration of radicals containing atoms (α) and atoms (β) in the aqueous phase and/or organic phase is not particularly limited, it is, for example, 0.0001 mol/L or more and 1 mol/L or less.

When the optical material substrate is immersed in an aqueous phase or an organic phase, the amount of the optical material substrate used in the aqueous phase or the organic phase is not particularly limited. /L or more, or 10 g/L or less.

The aqueous phase is not particularly limited as long as it contains water.
The organic phase is not particularly limited as long as it contains an organic solvent.
Further, the organic solvent may be used alone or in combination of multiple types. Examples of the organic solvent include hydrocarbon solvents and halogenated solvents.

Examples of the hydrocarbon solvent include, but are not limited to, n-hexane, cyclohexane, benzene, toluene, o-xylene, m-xylene, and p-xylene.

Examples of the halogenated solvent include, but are not limited to, methylene chloride, chloroform, carbon tetrachloride, carbon tetrabromide, and fluorous solvents.
The fluorous solvent refers to a solvent in which all or most of the hydrogen atoms of a hydrocarbon are substituted with fluorine atoms. The fluorous solvent may be, for example, a solvent in which 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the hydrogen atoms in the hydrocarbon are substituted with fluorine atoms.

Examples of the fluorous solvent include CF ₃ —(CF ₂ ) _n —CF ₃ (n is 4 to 7), N—((CF ₂ ) _n CF ₃ ) ₃ (n is 1 or 4), hexa fluorobenzene, 1-(trifluoromethyl)undecafluorocyclohexane, 1-(trifluoromethyl)pentafluorobenzene, octadecafluorodecahydronaphthalene, among which for example CF ₃ (CF ₂ ) ₄ CF ₃ is preferred.

A fluorous solvent has the advantage of suppressing or preventing side reactions, for example, because the solvent itself has low reactivity. Examples of the side reaction include oxidation reaction of the solvent, hydrogen abstraction reaction and chlorination reaction of the solvent by radicals, and reaction between radicals derived from the olefin polymer constituting the optical material substrate and the solvent. .

Moreover, the aqueous phase and/or the organic phase may or may not contain components other than the radicals. Examples of the other component include, but are not particularly limited to, the radical generating source, Bronsted acid, Lewis acid, and oxygen (O ₂ ).

Each of these may be used alone or in combination of two or more.
Said other ingredients may be dissolved in the aqueous phase and/or the organic phase, but they do not have to be dissolved.
In addition, one substance may serve as both the Lewis acid and the Bronsted acid. The term "Lewis acid" refers to a substance that acts as a Lewis acid against the above radical generation source.

The source of the radical is not particularly limited, but when the radical is a chlorine dioxide radical, for example, chlorous acid (HClO ₂ ) or a salt thereof may be used. Salts of chlorous acid include, but are not limited to, metal salts, for example. Examples of the metal salts include alkali metal salts, alkaline earth metal salts, rare earth salts and the like.

More specifically, the chlorine dioxide radical generation source includes, for example, sodium chlorite (NaClO ₂ ), lithium chlorite (LiClO ₂ ), potassium chlorite (KClO ₂ ), magnesium chlorite ( Mg(ClO ₂ ) ₂ ) and calcium chlorite (Ca(ClO ₂ ) ₂ ). These chlorous acids and salts thereof may be used alone or in combination of multiple types. Among these, sodium chlorite is preferable from the viewpoint of cost, ease of handling, and the like.

The concentration of the radical generation source in the aqueous phase and/or organic phase is not particularly limited, but is, for example, 0.0001 mol/L or more and 1 mol/L or less.

The Lewis acid may be, for example, an organic substance or an inorganic substance.
Examples of the organic substances include ammonium ions and organic acids (eg, carboxylic acids).

The inorganic substance may contain one or both of metal ions and non-metal ions. The metal ions may contain one or both of typical metal ions and transition metal ions.

Examples of the inorganic substance include alkaline earth metal ions (e.g., Ca ²⁺ ), rare earth ions, Mg ²⁺ , Sc ³⁺ , Li ⁺ , Fe ²⁺ , Fe ³⁺ , Al ³⁺ , silicate ions, and borate ions.

The alkaline earth metal ions include, for example, calcium, strontium, barium, or radium ions, and more specifically, for example, Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , and Ra ²⁺ . mentioned.

The rare earth element is a general term for a total of 17 elements including two elements, scandium ₂₁ Sc and yttrium ₃₉ Y, and 15 elements (lanthanoids) from lanthanum ₅₇ La to lutetium ₇₁ Lu. Rare earth ions include, for example, trivalent cations for each of the 17 elements.

In addition, when the Lewis acid is an ion, the Lewis acid may be a substance having a counter ion of the ion. Examples of the counter ion include trifluoromethanesulfonate ion ⁽ CF ₃ SO ₃ or OTf ⁻ ), trifluoroacetate ion (CF ₃ COO ⁻ ), acetate ion, fluoride ion, chloride ion, bromide ion, iodide ion, sulfate ion, hydrogen sulfate ion, sulfite ion, nitrate ion, Examples include nitrite ions, phosphate ions, and phosphite ions. The Lewis acid may be, for example, scandium triflate (Sc(OTf) ₃ ).

Also, the Lewis acid (including the counterion) is selected from the group consisting of, for example, AlCl3, AlMeCl2, _AlMe2Cl , _{BF3 , BPh3 , BMe3} , _TiCl4 , _SiF4 , and _SiCl4 . It may be at least one. However, "Ph" represents a phenyl group and "Me" represents a methyl group.

The Lewis acidity of the Lewis acid is, for example, 0.4 eV or more, but is not limited thereto. Although the upper limit of the Lewis acidity is not particularly limited, it is, for example, 20 eV or less. The Lewis acidity is described, for example, in Ohkubo, K.; Fukuzumi, S. Chem. Eur. J., 2000, 6, 4532, J. AM. CHEM. SOC. Org. Chem. 2003, 68, 4720-4726.

The Bronsted acid is not particularly limited, but may be, for example, an inorganic acid or an organic acid. Hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, phosphoric acid, phosphorous acid and the like.

The acid dissociation constant pK _a of the Bronsted acid is, for example, 10 or less. Although the lower limit of the pK _a is not particularly limited, it is -10 or more, for example.
The concentration of at least one of the Lewis acid and Bronsted acid in the aqueous phase and/or organic phase is not particularly limited and can be set as appropriate. /L or less.

Regarding the oxygen (O ₂ ), for example, air or oxygen is added to at least one of water and an organic phase before or after adding the radical generation source, the Lewis acid, the Bronsted acid, the optical material base material, and the like. Oxygen may be dissolved by blowing gas. At this time, for example, the water may be saturated with oxygen (O ₂ ). When at least one of the aqueous phase and the organic phase contains the oxygen (O ₂ ), for example, the oxidation reaction of the olefin polymer constituting the optical material substrate can be further promoted.

<Radical generation step>
The production method of the present invention may include the step of generating the radicals (radical generation step), specifically, the step of generating the radicals from the radical generation source.

The radical generation step is not particularly limited, but for example, the radical generation source (e.g., chlorous acid or a salt thereof) is dissolved in water and allowed to stand, and the radicals are naturally generated from the radical generation source. be able to. At this time, for example, the presence of at least one of the Lewis acid and Bronsted acid in the water further promotes the generation of the radicals. Further, for example, the radicals may be generated by irradiating an aqueous phase in which the radical generating source is dissolved in water. This light irradiation may be the light irradiation in the step 1, that is, the light irradiation in the step 1 may be performed on the radicals while the radicals are being generated.

For example, the mechanism of generation of chlorine dioxide radicals from chlorite ions is presumed as shown in Scheme 1 below. However, Scheme 1 below is an example of a presumed mechanism and does not limit the present invention in any way.

The first (upper) reaction formula in Scheme 1 below shows the disproportionation reaction of chlorite ion (ClO ₂ ⁻ ), and at least one of Lewis acid and Bronsted acid is present in this reaction system. , the equilibrium tends to shift to the right.

The second (middle) reaction formula in Scheme 1 below shows a dimerization reaction, in which hypochlorite ions (ClO ⁻ ) generated in the disproportionation reaction react with chlorite ions to form dioxide. Chlorine (Cl ₂ O ₂ ) is produced. This reaction is thought to proceed more easily as the amount of protons H ⁺ in the water increases, that is, as the water becomes more acidic.

The third (lower) reaction scheme in Scheme 1 below represents radical generation. In this reaction, dichlorine dioxide generated in the second reaction formula reacts with chlorite ions to generate chlorine dioxide radicals.

In step 1, the wavelength of the irradiation light may be appropriately selected so that the optical material substrate can be modified according to the radicals used. Specifically, it is possible to select a wide range from the infrared region to the ultraviolet region, and for example, it may be 200 nm or more and may be 800 nm or less. The light irradiation time is not particularly limited, but may be, for example, 1 minute or longer and may be 1000 hours or shorter.

The temperature at which step 1 is performed is not particularly limited, but may be, for example, 0° C. or higher and 100° C. or lower.
The atmospheric pressure in performing step 1 is not particularly limited, but may be, for example, 0.1 MPa or higher and 100 MPa or lower.

The step 1 may be carried out at normal temperature (eg, 5 to 35° C.) and normal pressure (atmospheric pressure) without any heating, pressurization, pressure reduction, etc., as shown in Examples below. It is possible. In addition, in the production method of the present invention, for example, as shown in Examples described later, it is possible to carry out Step 1 or all the steps including Step 1 in the atmosphere without performing inert gas replacement or the like. is.

In the light irradiation, the light source is not particularly limited, but examples thereof include visible light contained in natural light such as sunlight. Further, for example, instead of or in addition to the natural light, a light source such as a xenon lamp, a halogen lamp, a fluorescent lamp, or a mercury lamp may or may not be used as appropriate. Furthermore, a filter that cuts wavelengths other than the required wavelength may or may not be used as appropriate.

In addition, in the present invention, the optical material substrate contains an olefin polymer, and the olefin polymer has a structure having a carbon-hydrogen single bond like ethane or the like. It can be inferred that the reaction proceeds by a mechanism similar to the mechanism by which ethanol is produced by the oxidation reaction of ethane. Moreover, since the reaction used in the present invention proceeds via light, the area exposed to light in the presence of the radicals, i.e., the area mainly in contact with the phase containing the radicals, of the surface of the optical material substrate mainly is expected to react. If this property is used, even if the olefin polymer molecules constituting the optical material base material are cut or crosslinked by the modification reaction, they will remain near the surface of the optical material, and the strength and other performance of the optical material will be affected. Since there is a possibility that the impact on the performance inside the optical material concerned can be minimized, it is advantageous in terms of maintaining the strength of the optical material.

The surface of the optical material refers to a region from the surface to a depth of 1/10 or less, more preferably 1/20 or less of the thickness of the base material. The depth of this denatured portion can be confirmed by, for example, the XPS method.

In addition, by using a photomask, it is possible to modify only specific regions of the optical material substrate, and it is expected that the ratio of the modified region and the unmodified region in the optical material can be controlled freely. be done.

For example, assuming that the entire surface of the optical material of the present invention through which light is transmitted is 100%, the area of the modified portion may be appropriately selected according to the desired application of the resulting optical material. The preferred lower limit of the area ratio is 1%, 5%, 10%, 20%, 30% and 50% in that order, and the preferred upper limit is 100%, more preferably 90%. A denatured region can be identified by a known method such as the XPS method.

It is considered that the modification progresses with radicals of the group 17 element generated when the radicals are exposed to light as a starting point. Therefore, it is thought that modification occurs at the portion where the radical comes into contact with the optical material substrate to be modified. Therefore, in the case of the above method, the area of the optical material substrate to be modified, which is irradiated with light, and the modified area may be considered to be substantially equivalent.
Although the peripheral portion irradiated with light and the deep layer portion of the pore where the light does not reach may be denatured, the ratio is considered to be small.

In the present invention, irradiating the optical material substrate with light may not directly involve the modification reaction of the optical material substrate. However, considering the general lifetime of radicals and the case of modifying a specific site of an optical material substrate, it is a preferable method to substantially irradiate the optical material substrate with light.

Further, if the production method of the present invention is used, the hydroxyl group, carboxyl group, aldehyde group, carbonyl group, ether bond, ester bond, -C (=O) OOH, -O-O- and the like are not limited, and 17 A group element, typically chlorine, may also be simultaneously introduced into the olefin polymer constituting the optical material substrate. Of course, by changing the type of radical used, it is possible to introduce not only chlorine but also bromine and iodine. When a low-molecular-weight hydrocarbon compound such as an alkane is used as a substrate, it has been reported that the introduction of chlorine is suppressed by the method using chlorine dioxide radicals as in the present invention. is used, atoms (β) of group 17 elements such as chlorine can sometimes be introduced together with atoms (α) of elements selected from group 15 and 16 elements such as oxygen. This is because the existence density of carbon-hydrogen bonds in olefin polymers tends to be higher than in the case of using low-molecular-weight substances such as methane and ethane as substrates, and the interaction with polymers The present inventors believe that one of the reasons for this is the possibility of stabilizing the radicals. However, this speculation does not limit the present invention.

The ratio of the total amount [Cα] of atoms (α) to the total amount [Cβ] of atoms (β) introduced into the optical material substrate (i.e., [Cα]/[Cβ]) is a preferred lower limit The value is greater than zero, more preferably 0.01, more preferably 0.1, particularly preferably 0.5;

The above [Cα] and [Cβ] values are values specified by the XPS method. In the present invention, measurement is carried out by a conventional method using a product name AXIS-Nova (manufactured by KRATOS) or an equivalent device.

Furthermore, after step 1 of light irradiation, the optical material may be washed several times and then dried, if necessary.
According to the present invention, for example, chlorine atom radicals Cl. and oxygen molecules _O2 are generated by a very simple method of irradiating an aqueous solution of chlorine dioxide radicals with light to oxidize an olefin polymer constituting an optical material substrate. reaction can be carried out. In addition, by such a simple method, it is possible to produce an optical material by efficiently modifying an optical material substrate containing an olefin polymer even under very mild conditions such as normal temperature and normal pressure. .

Furthermore, according to the present invention, for example, the olefin polymer constituting the optical material base is oxidized without using a radical generator such as a peroxide or an azo compound, which may be unstable at the handling temperature. can also According to this, as described above, the reaction can be performed under extremely mild conditions such as normal temperature and normal pressure, and in addition, it is possible to efficiently obtain a modified optical material base material, that is, an optical material, in a highly safe environment. is also possible.

The introduced functional group such as the oxygen-containing substituent can also be reacted with other components to enhance the function of the optical material or change its properties. For example, it is advantageous to form various surface layers on optical materials using the functional groups as scaffolds. Specifically, the formation of a hard coat layer, which often uses an acrylic material, an anti-fog layer (such as Nostra (registered trademark) manufactured by Mitsui Chemicals, Inc. is used), an anti-reflection layer, and a blue light cut layer It is expected that it will be advantageous in terms of formation of etc. It is also expected to be advantageous in forming an inorganic layer (formed by a vapor deposition method or a sol-gel method) for the purpose of improving gas permeability.

It is expected that the optical material produced by the method of the present invention can be preferably applied to various uses. For example, the lens described above is a typical example. Various sensors are being developed for autonomous driving of automobiles, and there is a possibility that the materials for the lenses of these sensors will shift from glass to polymers in the future. For this reason, sensor lenses are also an important application.

In the optical material produced by the method of the present invention, the molecular weight of the olefin polymer is less reduced during the modification reaction (that is, when the optical material base material is modified). It is small, has little effect on optical properties, and can be expected to improve in terms of excellent durability. In addition, since a relatively large number of functional groups can be introduced, it can be expected that the deterioration rate of the reforming performance over time is small.

Examples of the present invention will be described below. However, the present invention is not limited to the following examples.
[Example 1]
(Manufacture of optical materials)
Put 10 g of sodium chlorite (manufactured by Sigma-Aldrich) and 500 mL of ultrapure water in a plastic container. ) was added, and this solution was placed in a shallow vat having a size of about 32 cm x 23 cm x 2 cm. It was previously confirmed by the ESR method that chlorine dioxide radicals were generated under these conditions. On the other hand, the following formula was added to the bottom of the inside of a glass vat having a size of about 33 cm x 24 cm x 3 cm:

で表される２種の構造単位を有するシクロオレフィンコポリマー片（三井化学（株）製ＡＰＥＬ（登録商標）（光学材料用途に好適な樹脂）、サイズ：約６５ｍｍ×３５ｍｍ×３ｍｍ）を３枚、等間隔で貼り付け、シクロオレフィンコポリマー片が貼り付けてある面を下にして、前記浅型バット上に重ねるように置いた。今回用いたＡＰＥＬ（登録商標）のガラス転移温度は１３５℃、ＡＳＴＭ１２３８規格、２６０℃、２．１６ｋｇ荷重の条件で測定したメルトフローレートは３６ｇ／１０分であった。このバットを重ねた系に対して、ガラス製バット上部からパイフォトニクス（株）製ホロライト・カク ＤＣ１２Ｖで１０分間５０～７０ｍＷ／ｃｍ²の波長３６５ｎｍ光を照射した。その後、ガラス製バットからシクロオレフィンコポリマー片を剥がし、表面を超純水で洗浄した。次いで、シクロオレフィンコポリマー片を減圧乾燥し、コポリマー片（以下「酸化シクロオレフィンコポリマー片」とも記載する。）からなる光学材料を得た。

3 pieces of cycloolefin copolymer pieces (manufactured by Mitsui Chemicals, Inc. APEL (registered trademark) (resin suitable for optical material applications), size: about 65 mm × 35 mm × 3 mm) having two types of structural units represented by The cycloolefin copolymer pieces were attached at regular intervals and placed on top of the shallow vat with the side to which the cycloolefin copolymer pieces were attached facing down. The APEL (registered trademark) used this time had a glass transition temperature of 135° C. and a melt flow rate of 36 g/10 minutes measured under the conditions of ASTM 1238 standard, 260° C., and a load of 2.16 kg. The system in which the batts were stacked was irradiated with 50 to 70 mW/cm ² of light having a wavelength of 365 nm for 10 minutes from the upper part of the glass bat with Horolite Kaku (manufactured by Piphotonics Co., Ltd.) DC12V. After that, the cycloolefin copolymer piece was peeled off from the glass vat, and the surface was washed with ultrapure water. Next, the cycloolefin copolymer pieces were dried under reduced pressure to obtain an optical material composed of copolymer pieces (hereinafter also referred to as "oxidized cycloolefin copolymer pieces").

(Evaluation of Adhesiveness of Optical Material)
Ultraviolet curable coating agent "Orester (registered trademark) RA6800" (manufactured by Mitsui Chemicals, Inc.) 5.00 g, Irgacure 1173 (manufactured by BASF) 0.11 g as a photoinitiator, 1-methoxy-2-propanol as a solvent (manufactured by Junsei Chemical Co., Ltd.) was mixed to obtain a coating liquid. This coating liquid is applied to each of the cycloolefin copolymer piece and the oxidized cycloolefin copolymer piece (the side facing the chlorous acid liquid side in the previous step) with a bar coater #20, and dried in a hot air dryer at 80°C for 2 minutes. The mixture was heated and the solvent was removed to form a coating film. Each polymer piece with a coating film formed thereon is passed through a UV conveyor (lamp system: F600V/light source: electrodeless lamp H bulb/manufactured by Heraeus) at a conveyor speed of 8 m/min (UVA cumulative light intensity of 400 mJ/cm ² ). Allowed to pass through to cure the coating. Adhesion of the coating film was evaluated in accordance with JIS K5400-8.5 for each copolymer piece after curing of the coating film.

Specifically, 11 cuts were made on the surface of the coating film with a cutter knife at intervals of 1 mm to reach the copolymer piece, and then the copolymer piece was rotated 90° and 11 similar cuts were made to make 100 grids. created a square of After that, cellophane adhesive tape CT405AP-24 manufactured by Nichiban Co., Ltd. was attached to the grid squares, and the edge of the tape was held and held at right angles to the coating film surface, and the tape was instantaneously peeled off. After peeling off, the number of 100 squares remaining on one surface without being peeled off was counted. Adhesion evaluation was performed twice for each optical material (copolymer piece). Table 1 shows the results.

Claims (8)

Atoms (α) of elements selected from group 15 elements and group 16 elements and atoms (β) of group 17 elements in one molecule are atom (α): atom (β) = 1: 1 ~ including a step 1 of irradiating the radicals in a ratio of 4:1 with light;
the element selected from the group 15 elements and group 16 elements is oxygen,
The Group 17 element is chlorine, bromine or iodine,
The step 1 is
In an environment where an optical material base containing an olefin polymer having a melting point and/or a glass transition temperature of 70° C. or higher and 300° C. or lower and the radicals coexist,
A method for producing an optical material, comprising the step of irradiating the radicals with light to modify the optical material substrate . 2. The method for producing an optical material according to claim 1 , wherein said step 1 is a step of irradiating said optical material substrate and said radicals with light. 3. The method for producing an optical material according to claim 1, wherein a part of said optical material is in an undenatured state. The method for producing an optical material according to any one of claims 1 to 3 , wherein the optical material has a thickness of 200 µm to 20 cm. The method for producing an optical material according to any one of claims 1 to 4 , wherein the radicals are chlorine dioxide radicals. The method for producing an optical material according to any one of claims 1 to 5 , wherein the olefin polymer is a cyclic olefin polymer. The method for producing an optical material according to any one of claims 1 to 6 , wherein the optical material is a base material for lenses. 8. The method for producing an optical material according to claim 7 , wherein the lens is a lens for an in-vehicle sensor.

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