JPH06324213A - Composite optical filter - Google Patents

Abstract

PURPOSE:To provide a lightweight composite optical filter efficiently cutting the near-infrared light, excellent in visibility correctavility, having an optical low-pass filter function, reduced in hygroscopicity and excellent in grindability. CONSTITUTION:This composite optical filter consists of a birefringent sheet 4 and a plastic optical filter 3 formed by incorporating a metallic compd. consisting essentially of copper oxide into the synthetic resin obtained by copolymerizing a monomer shown by PO(OH)nR3-n and a monomer copolymerizable with the former monomer. In the formula, R is CH2=CXCOO(C2 H4O)-, X is hydrogen atom or methyl, (m) is an integer of 1 to 5, and (n) is 1 or 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a composite optical filter. More specifically, the present invention relates to a plastic composite optical filter that effectively cuts light in the near-infrared region, has a visibility correction capability, and has an optical low-pass filter function.

[0002]

2. Description of the Related Art Conventionally, a glass filter has been used as a photometric filter and a visibility correction filter for a camera. This glass filter is a special phosphoric acid glass containing copper ions. However, these glass filters have many problems such as heavy weight, high hygroscopicity, easy devitrification over time, and difficult working and polishing. Therefore, the advent of a plastic optical filter that is light, has a low hygroscopic property, is easy to process and polish, and has an optical low-pass filter function has been strongly desired.

[0003]

The present invention has been made based on such a situation as described above, and its purpose is to effectively cut wavelength light in the near-infrared region and to have a visibility correction capability. In addition, the present invention is to provide a composite optical filter made of plastic, which has an optical low-pass filter function, is lightweight, has low hygroscopicity, and is easy to process and polish.

[0004]

The composite optical filter of the present invention comprises a synthetic resin obtained by copolymerizing a monomer represented by the following chemical formula 2 and a monomer copolymerizable therewith with copper. It is characterized by comprising a plastic optical filter containing a metal compound containing a compound as a main component and a birefringent plate.

[0005]

Embedded image PO (OH) _n R _{3 -n} [wherein R is CH ₂ ═CXCOO (C ₂ H ₄ O) _m — (X
Represents a hydrogen atom or a methyl group, and m is an integer of 1 to 5. ) Is shown and n is 1 or 2. ]

The present invention will be described in detail below. The main part of the composite optical filter of the present invention is composed of a plastic material containing a specific amount of copper ions in a copolymer composed of a monomer containing a specific phosphoric acid group represented by Chemical formula 2. is there.

In the copolymer which is the resin component constituting the composite optical filter of the present invention, first, the monomer represented by Chemical formula 2 is used as an essential component. This monomer contains an acrylic group or a methacrylic group as a radically polymerizable functional group, is extremely copolymerizable, and can be copolymerized with various monomers. Furthermore, a phosphate group is bound in this monomer molecule, and the phosphate group is bound to a copper ion, which has a high transmittance in the visible light region and efficiently emits light in the near infrared region. The greatest feature of the present invention is that it becomes an absorbing polymer. In addition, by combining an optical filter made of this polymer and a birefringent plate, a composite optical filter having an effective optical low-pass filtering function can be newly provided.

In the above chemical formula 2, R is an acryl group or a methacryl group to which an ethylene oxide group having a repeating number of m is bonded. X in R is a hydrogen atom or a methyl group, and m is an integer of 1-5. When m exceeds 5 and becomes large, the hardness of the obtained copolymer is significantly lowered, and only a polymer lacking in practicality as a filter can be obtained.
The number n of hydroxyl groups can be either 1 or 2 depending on the purpose of use. When the value of n is 2, the bondability with the copper salt is large and the number of radically polymerizable functional groups is 1
Is a monomer. On the other hand, when the value of n is 1, the number of radically polymerizable functional groups is 2, and the monomer has crosslinkable polymerizability.

Therefore, in order to manufacture the optical filter constituting the composite optical filter of the present invention by injection molding or extrusion molding, which is a general molding method for thermoplastic resins, the monomer n is 2 is used. However, the molding method is not limited to these. As described above, the value of n can be selected according to the performance of the optical filter, the molding method, or the purpose of use. A monomer having an n value of 1 and a monomer having an n value of 2 can be selected. It is preferable to use in combination with and from the viewpoint of enhancing the solubility of copper ions.

As the polymer constituting the main part of the composite optical filter of the present invention, a homopolymer of the monomer shown in Chemical formula 2 is not used, but a copolymer is used. The reason for this is that a homopolymer has a very large amount of moisture absorption, and it is not possible to obtain a molded product which is excellent in flexibility and has excellent shape retention. In the present invention, the ratio of the monomer represented by Chemical Formula 2 to 100 parts by weight of the monomer mixture for copolymer is preferably 3 to 60 parts by weight. If this ratio is less than 3 parts by weight, the preferable light absorption characteristics of the present invention cannot be obtained. On the other hand, if the amount exceeds 60 parts by weight, as described above, only a molded article having flexibility and high hygroscopicity is obtained, which is not preferable.

Next, in the present invention, the monomer copolymerized with the monomer shown in Chemical formula 2 must have the following characteristics. That is, (1) the monomer represented by the chemical formula 2 and the monomers are uniformly dissolved and mixed, and (2) the radical copolymerizability with the monomer of the chemical formula 2 is good, (3) It is necessary to satisfy that the resulting copolymer is optically transparent. There is no particular limitation as long as these properties are satisfied.

Specific examples of these are shown below. Methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, n-propyl acrylate, n-propyl methacrylate,
2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, n-butyl acrylate, n
-Butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, n
-Heptyl acrylate, n-heptyl methacrylate, n-octyl acrylate, n-octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, glycidyl acrylate, glycidyl methacrylate, 2-hydroxy-3-phenoxypyropyr acrylate, 2-hydroxy-3-phenoxypropyl Monofunctional acrylates and methacrylates such as methacrylate, phenoxy polyethylene glycol acrylate, phenoxy polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, methoxy polyethylene glycol methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate (hereinafter referred to as monofunctional ( Meta Also referred to as acrylate.) S.

Ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate , Neopentyl glycol dimethacrylate, 2-hydroxy-1,3-di Taku Lilo carboxymethyl propane, 2,2
-Bis [4- (methacryloxyethoxy) phenyl] propane, 2-hydroxy-1-acryloxy-3-methacryloxypropane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol Polyfunctional acrylates or methacrylates such as tetraacrylate and pentaerythritol tetramethacrylate.

Acrylic acid, methacrylic acid, 2-methacryloyloxyethyl succinic acid, carboxylic acid such as 2-methacryloyloxyethyl phthalic acid, styrene, α-methylstyrene, chlorostyrene, dibromostyrene, methoxystyrene, divinylbenzene, vinylbenzoic acid , Aromatic vinyl compounds such as hydroxymethylstyrene, trivinylbenzene and the like, and these can be used alone or in combination of two or more kinds.

The copolymer used in the main part of the composite optical filter of the present invention can be obtained by radical polymerization of the monomer represented by Chemical formula 2 and the above-mentioned monomer copolymerizable therewith. At this time, it is also possible to dissolve and mix the below-mentioned metal ion, which is an essential constituent of the present invention, in the monomer mixture to carry out radical polymerization. In the present invention, the radical polymerization method is not particularly limited, and using a usual radical polymerization initiator, bulk (cast) polymerization, suspension polymerization,
Known methods such as emulsion polymerization and solution polymerization can be used.

The metal ion contained in the copolymer used in the present invention has an effect of efficiently absorbing light having a wavelength in the near infrared region by the interaction with the phosphate group in the copolymer. This metal ion contains divalent copper ions as a main component and may contain a small amount of other metal ions. However, in order to efficiently absorb light in the near infrared wavelength range, the amount of copper ions is all metal. It must be 80% by weight or more of the amount of ions.

The metal ion containing copper ion as a main component is preferably used in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the copolymer of the present invention. When the amount of this metal ion is less than 0.1 part by weight, it is not possible to efficiently absorb light in the near infrared region. On the other hand, if it exceeds 20 parts by weight, it becomes difficult to disperse it uniformly in the copolymer.

The copper ion in the present invention is supplied from various copper compounds, and examples thereof include copper acetate, copper chloride, copper formate, copper stearate, copper benzoate, copper ethylacetoacetate, copper pyrophosphate, and naphthene. Examples thereof include anhydrides and hydrates such as copper acid and copper citrate. However, it is not limited to these. Further, in the present invention, sodium in the range of less than 20% by weight of the total metal ions,
Metal ions such as potassium, calcium, iron, manganese, cobalt, magnesium, nickel and zinc can be used according to the purpose.

The method of incorporating the metal ion containing copper ions as a main component into the copolymer constituting the present invention is not particularly limited, but the following two methods are preferably used. First, there is a method in which the above-mentioned copper compound is dissolved in a monomer mixture constituting this copolymer and radical polymerization is carried out. In this method, the obtained copolymer contains metal ions containing copper ions as the main component, and the polymer is used as it is or by molding and polishing it into a desired shape (for example, plate shape). It can be used in the composite optical filter of the invention. In another method, the monomer represented by Chemical formula 2 and a monomer copolymerizable therewith are preliminarily polymerized, and a metal ion containing copper ion as a main component is supplied to the obtained copolymer. This is a method of mixing a metal compound.

As a method of adding after the polymerization, a method of melting the copolymer and mixing the metal compound, a method of dissolving or dispersing the copolymer in water or an organic solvent, and adding and mixing the metal compound are used. be able to. A copolymer containing a metal ion containing copper ions as a main component, which constitutes the composite optical filter of the present invention, can be obtained by the method as described above. This copolymer can be molded into a plate shape and polished according to the purpose and application and used in the composite optical filter of the present invention.

Next, in the present invention, a birefringent plate is laminated on the surface of this optical filter in order to impart a low-pass filter function to this plastic optical filter. By using this birefringent plate, the high spatial frequency component of the subject light can be limited, and the color component different from that of the subject due to the generation of the pseudo signal can be removed. Therefore, the composite optical filter of the present invention, by using a specific plastic optical filter and a birefringent plate as main components, is excellent in luminosity correction, has a large absorptance of wavelength light in the near infrared region, and It also has a characteristic of having a low-pass filter function.

In the composite optical filter of the present invention, the birefringent plate to be laminated in order to exert the optical low pass filter function is located on the incident light side (FIG. 1) or the transmitted light side if it is the surface of the plastic optical filter. It may be arranged anywhere. Further, if necessary, by disposing the correction plate on the incident light side of the birefringent plate as shown in FIGS. 2 to 3,
It is possible to make the normal ray and the extraordinary ray of the subject light separated by the birefringent plate equal in intensity, and any of these can be used in the present invention. As this correction plate, a general quarter-wave plate can be used, but it is also effective to use a depolarizing plate for making the light non-polarized. The polarizing plate is not particularly limited, but a quartz plate is usually used.

In the composite optical filter of the present invention, when the plastic optical filter, the birefringent plate, and the correction plate are laminated, an adhesive is not an essential constituent element, but a thermosetting type or a photocuring type is used. An adhesive with excellent transparency,
For example, it is desirable to use an epoxy, urethane, or acrylic adhesive.

[0024]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[Example 1] 32 parts by weight of the specific phosphoric acid group-containing monomer represented by the following chemical formula 3, 13 parts by weight of the specific phosphoric acid group-containing monomer represented by the following chemical formula 4, and methyl methacrylate 34 parts by weight, 20 parts by weight of diethylene glycol dimethacrylate, and 1 part by weight of α-methylstyrene were mixed well, and 32 parts by weight of anhydrous copper benzoate (copper ion amount was 6. 6 parts by weight) was added and mixed by stirring at 80 ° C. to obtain a monomer composition in which the copper benzoate anhydrous was dissolved in the mixed monomer.

[0026]

[Chemical 3]

[0027]

[Chemical 4]

To the monomer composition prepared as described above, 2 parts by weight of t-butylperoxy (2-ethylhexanoate) was added, and the mixture was poured into a glass mold.
The mixture was heated at different temperatures for 16 hours at 70 ° C. for 8 hours, then at 70 ° C. for 2 hours, and then at 100 ° C. for 2 hours to perform casting polymerization to obtain a cross-linked copolymer containing a copper compound.
The obtained crosslinked copolymer was cut into a plate-like body having a thickness of 1 mm,
Benzoic acid, which is a reaction product of a copper compound and a phosphoric acid group, was extracted and removed, and surface polishing was performed to produce an optical filter.

On one side of this optical filter, a commercially available crystal birefringent plate having a thickness of 3.5 mm was adhered using an epoxy adhesive and cured at 60 ° C. The thickness of the adhesive layer was about 10μ. When a composite optical filter (see Fig. 1) in which this birefringent plate made of quartz was laminated was installed in a video camera and a live-action test was conducted, it was confirmed that it had an effective optical low-pass filter function and an appropriate color correction function. It was The measurement result of the spectral transmittance curve of this composite optical filter by a spectrophotometer is shown in FIG. Figure 4
As indicated by the solid line a, the composite optical filter of this example has a high transmittance in the visible region and a near infrared region (700 to 1).
It can be seen that light having a wavelength of 000 nm) is efficiently absorbed.

Example 2 49 parts by weight of the specific phosphoric acid group-containing monomer represented by Chemical formula 3 used in Example 1 and 21 parts by weight of the specific phosphoric acid group-containing monomer represented by Chemical formula 4 , 27 parts by weight of methyl methacrylate, 2 parts by weight of diethylene glycol dimethacrylate, and 1 part by weight of α-methylstyrene were mixed well, and 20 parts by weight of anhydrous copper acetate was added to this mixed monomer (copper ion content was 100% of total monomer). (7.0 parts by weight based on parts by weight) was added, and the mixture was stirred and mixed at 40 ° C. to uniformly dissolve. 3 parts by weight of t-butylperoxypivalate was added to the monomer mixture prepared as described above, and the mixture was poured into a glass mold, and the temperature was 45 ° C. for 16 hours and the temperature was 60 ° C. for 28 hours.
Further, the mixture was heated at 90 ° C. for 3 hours at different temperatures in sequence to perform cast polymerization to obtain a cross-linked copolymer containing a copper compound. The obtained crosslinked copolymer was cut into a plate having a thickness of 1 mm, acetic acid, which is a reaction product of a copper compound and a phosphoric acid group, was extracted and removed, and surface polishing was performed to produce an optical filter.

As shown in FIG. 2, a correction plate and a birefringent plate were bonded to the surface of this optical filter using an epoxy adhesive in the same manner as in Example 1. The correction plate used here is a commercially available quarter-wave plate (thickness: 3.5 mm). When this composite optical filter was installed in a video camera and a live-action test was conducted, an effective optical low-pass filter function was recognized. Further, a spectral transmittance curve measured by a spectrophotometer in the same manner as in Example 1 is shown by a broken line b in FIG.

[0032]

As described above, in the composite optical filter of the present invention, the base material constituting the composite optical filter is a copolymer containing a (meth) acrylate-based monomer containing a phosphoric acid group as an essential component and a copper compound. Is an optical filter made of plastic that is evenly dispersed. It is lightweight, has a low moisture absorption, does not devitrify over time, is easy to process and polish, and is efficient in the near-infrared wavelength light. It can cut well, has excellent visibility correction capability, has an optical low-pass filter function, and has an extremely effective optical function for video cameras and the like.

[0033]

[Brief description of drawings]

1 to

FIG. 3 is a schematic cross-sectional view of a composite optical filter of the present invention.

FIG. 4 is a spectral transmittance curve of the composite optical filters of Example 1 and Example 2.

[Explanation of symbols]

1; incident light, 2; transmitted light, 3; optical filter, 4; birefringent plate, 5; correction plate. a: Spectral transmittance curve of the composite optical filter of Example 1 b; Spectral transmittance curve of the composite optical filter of Example 2

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[Procedure amendment]

[Submission date] March 31, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

Claims (1)

[Claims] 1. A synthetic resin obtained by copolymerizing a monomer represented by the following chemical formula 1 and a monomer copolymerizable therewith, containing a metal compound containing a copper compound as a main component. A composite optical filter comprising a plastic optical filter and a birefringent plate. Embedded image PO (OH) _n R _{3 -n} [wherein R is CH ₂ ═CXCOO (C ₂ H ₄ O) _m — (X
Represents a hydrogen atom or a methyl group, and m is an integer of 1 to 5. ) Is shown and n is 1 or 2. ]