JPH061282B2 - Optical filter material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical filter material that absorbs infrared rays. More specifically, the present invention relates to an optical filter material that absorbs far-red light or near-infrared light having a wavelength of 700 to 1500 nm with almost no loss of transmission of visible light.

(Prior Art) Various applications are conceivable for optical filter materials that selectively absorb far-red light or near-infrared light having a wavelength of 700 to 1500 nm, and there has been a strong demand for them, but until now, they have been suitable. I didn't get anything. The main uses of the conventional optical filter material will be described below with reference to five examples.

Infrared-sensitive safelight filters for photosensitive materials In recent years, many silver halide photosensitive materials (hereinafter referred to as "sensitive materials") have been developed which have sensitivity to far-red light or near-infrared light having a wavelength of 700 nm or more. It is coming. This can be black and white or color, and can be used as a pseudo-color photograph for resource research, etc. by equipping the silver halide photographic material with infrared sensitivity, not only the normal type but also the instant type or the heat development type. Alternatively, there is a device that can be exposed by using a diode that emits light in the infrared region.

For such infrared-sensitive light-sensitive materials, a panchromatic safelight filter has been conventionally used.

Control of plant growth It has long been known that light influences so-called morphogenesis related to plant growth and differentiation such as seed germination, stem elongation, leaf development, flower bud and tuber formation. It is being studied as a morphogenic effect. In this case wavelength 660
It is known that the red light around nm and the red light around 720 to 730 nm act antagonistically with each other, and by changing the ratio of both, the timing of flowering, heading, or the degree of growth, the yield of fruits, etc. are changed. ing. All such work was done with a combination of source lamps and filters and by controlling the spectral energy distribution, making it impossible to test in large greenhouses or farms.

If a plastic film that selectively absorbs light with a wavelength of 700 nm or more can be obtained, it becomes possible to apply the above-mentioned principle to actual production situations, and it will bring great progress and benefits to institutional agriculture. For example, when a crop is covered with a near infrared absorbing film at a specific time, a wavelength of 700n
It is expected to block the light of m or more to delay the heading time and control the growth (see Katsumi Inada, "Chemical Regulation of Plants", Vol. 6, No. 1 (1971)).

Blocking heat rays Of the radiant energy of the sun, near-infrared and infrared light with a wavelength of 800 nm or more is absorbed by an object and converted into heat energy. Moreover, most of the energy distribution is concentrated in the near infrared region having a wavelength of 800 to 2000 nm. Therefore, a film that selectively absorbs near-infrared rays is extremely effective in blocking solar heat, and it is possible to suppress an increase in indoor temperature while sufficiently incorporating visible light. This can be applied to windows of houses, offices, shops, automobiles, airplanes, etc. as well as horticultural greenhouses. In particular, temperature control is very important in greenhouses, if the temperature rises too much, the crop is significantly damaged, and eventually die, using a near-infrared absorbing film, temperature control becomes easy,
It will be possible to develop new technologies such as restrained cultivation in summer.

Conventionally, for blocking heat rays, a plastic film having a very thin metal layer vapor-deposited on the surface thereof, or an inorganic compound such as FeO dispersed in glass has been used.

Infrared Cut Filter Harmful to Human Eye Tissue Infrared rays contained in sunlight or rays contained in rays emitted during welding have a harmful effect on human eye tissue. One of the main applications of infrared cut filters is to use them as eyeglasses to protect the human eye from such harmful infrared rays.
For example, sunglasses and protective glasses for welders.

Infrared cut filter for semiconductor light receiving element Another field in which the development of this kind of infrared absorbing plastic is most strongly demanded is the spectral sensitivity curve of the spectral sensitivity of a semiconductor light receiving element such as a silicon photodiode (hereinafter referred to as SPD). It is a field of application as an infrared cut filter of a photodetection device for approaching to.

Currently, SPD is mainly used as a light receiving element of a photodetector used in an automatic exposure meter such as a camera. FIG. 2 shows a graph of the relative luminous efficiency curve and the relative value (spectral sensitivity) of the output with respect to each wavelength of the SPD.

In order to use the SPD for the light meter, the light in the infrared region that is not felt by human eyes is cut, and the SP shown in FIG.
It is necessary to make the spectral sensitivity curve of D similar to the relative luminous efficiency curve. In particular, for light having a wavelength of 700 to 1100 nm, the output of the SPD is large, and the light in this region is invisible to the eye, which causes a malfunction of the exposure meter. Therefore, if an infrared absorbing plastic film that absorbs little in the visible region and absorbs the entire infrared region of 700 to 1100 nm can be used, the light transmittance in the visible region will be large and the output of the SPD will be large. It is clear that the performance can be improved significantly.

Conventionally, as this type of photodetector, a glass infrared cut filter using an inorganic infrared absorber has been attached to the front surface of the SPD for practical use.

As a filter material for this SPD, a near-infrared absorbing plastic film using a complex having a quaternary ammonium group as an infrared absorbing agent has been proposed (Japanese Patent Laid-open No. Sho 5).
7-21458).

(Problems to be Solved by the Invention) However, conventional general organic dye-based infrared absorbers have little light resistance and heat resistance, and practically none have been satisfactory.

Further, the filter material used for each of the above applications also has the following drawbacks.

First, the conventional panchromatic safelight filter for the above-mentioned application not only partially transmits green light having high visibility but also causes a large amount of infrared light to cause optical fogging, which results in infrared sensitivity. The objective as a safelight for the sensitive material of was not able to be fully achieved.

Further, the plastic film deposited with the metal layer used for the above-mentioned applications or the glass in which FeO is dispersed strongly absorbs not only the infrared part but also the visible part, so that the internal illuminance is lowered, and especially for agriculture. It was unsuitable because it caused an absolute shortage of sunlight. In particular, for controlling the above-mentioned plant growth, the filter material has a wavelength of 700 to 750 nm.
It is necessary to selectively absorb the above-mentioned light, and a metal vapor deposition film or the like is completely unsuitable for this purpose.

Further, the glass infrared cut filter using the inorganic infrared absorbent used for the above-mentioned applications is relatively robust against heat and light, but has a low light transmittance in the visible region, and therefore the SPD of It was dealt with by increasing the sensitivity. Increasing the sensitivity of the SPD leads to an increase in leak current, which causes malfunction of the photodetector, which is a serious problem in terms of reliability. In addition, the fact that the infrared cut filter is made of an inorganic material lacks flexibility from the viewpoint of manufacturing the photodetector, and it is difficult to improve the manufacturing process. Further, the inorganic infrared cut filter has a drawback that the manufacturing cost is high and the cost of the photodetector is significantly increased.

As described above, in the photodetector using the conventional inorganic cut filter, the spectral sensitivity is close to the relative luminous efficiency curve, but the operation performance as the photodetector is deteriorated, the manufacturing cost is increased, and the manufacturing process is improved. Had significant drawbacks.

Furthermore, a near-infrared absorbing plastic film using a complex having a quaternary ammonium group as an infrared absorbing agent, which has been proposed for the above-mentioned applications, has insufficient solubility of the infrared absorbing agent in an organic solvent, which is a thin plastic film. It was a big drawback in creating.

That is, as the above-mentioned application, for example, as a filter for SPD, an extremely thin film having a good infrared absorption efficiency is desired, but for that purpose, a large amount of the infrared absorbent must be dispersed in the resin. However, an infrared absorber having a low solubility in an organic solvent cannot satisfy its purpose.

Further, the near-infrared absorbing plastic film using the above-mentioned complex having a quaternary ammonium group as an infrared absorbing agent has not been satisfactory in terms of heat resistance and light resistance.

Therefore, an object of the present invention is to firstly provide a near-infrared absorber having a high solubility in an organic solvent and good compatibility with a film-forming binder, and secondly, a near-infrared absorber per unit thickness. An object of the present invention is to provide an optical filter material having a large ability to block external light and a high light transmittance in the visible region, which is robust against heat and light. Thirdly, it is to provide a safelight filter material suitable for an infrared-sensitive photosensitive material.

The present inventors have completed the present invention as a result of various studies to achieve the above object.

(Means for Solving the Problems) That is, the present invention provides an optical filter material containing at least one compound represented by the following general formula [I].

(In the formula, [Cat] represents a quaternary phosphonium group, and M
Represents nickel, cobalt, copper, palladium or platinum, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are
It represents a hydrogen atom, a halogen atom or a substituted or unsubstituted alkyl group, which may be the same or different from each other. ) The present invention will be described in more detail.

In the above general formula [I], [Cat] represents a quaternary phosphonium group, and is preferably represented by the following general formula [II].

(In the formula, L ₁ , L ₂ , L ₃ and L ₄ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and these may be the same or different from each other.) To describe [II] in more detail, L ₁ to L ₄ each represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms.

As the substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, for example, methyl group, ethyl group, n-butyl group,
The iso-amyl group, n-dodecyl group, n-octadecyl group, etc. can be mentioned. Examples of the aryl group having 6 to 14 carbon atoms include phenyl group, tolyl group, α
-A naphthyl group and the like can be mentioned.

The alkyl group or aryl group may be a cyano group, an alkyl group having 1 to 20 carbon atoms (eg, methyl group, ethyl group, n-butyl group, n-octyl group, etc.), carbon number 6
To 14 aryl groups (eg, phenyl group, tolyl group, α-naphthyl group, etc.), acyloxy groups having 2 to 12 carbon atoms (eg, acetoxy group, benzoyloxy group, p-methoxybenzoyloxy group, etc.), 1 to 1 carbon atoms. 6 alkoxy group (eg, methoxy group, ethoxy group, propoxy group, butoxy group, etc.), aryloxy group (eg, phenoxy group, triloxy group, etc.), aralkyl group (eg, benzyl group, phenethyl group, anisyl group, etc.), alkoxycarbonyl Group (methoxycarbonyl group, ethoxycarbonyl group, n-
Butoxycarbonyl group etc.), aryloxycarbonyl group (phenoxycarbonyl group, triloxycarbonyl group etc.), acyl group (acetyl group, benzoyl group etc.),
Acylamino group (acetylamino group, benzoylamino group, etc.), carbamoyl group (N-ethylcarbamoyl group, N-phenylcarbamoyl group, etc.), alkylsulfonylamino group (eg, methylsulfonylamino group, phenylsulfonylamino group, etc.), sulfamoyl It may be substituted with a group, (N-ethylsulfamoyl group, N-phenylsulfamoyl group, etc.), sulfonyl group (mesyl group, tosyl group, etc.).

In the compound represented by the general formula [I], R ₁ to R ₈ preferably represent hydrogen, methyl group, chlorine or bromine, and may be the same or different. M is, in order of preference, nickel, cobalt, copper, palladium, platinum.

Preferred examples of the compound represented by the general formula [I] are shown below, but it goes without saying that the present invention is not limited to these exemplified compounds.

In the formula below, ⁿ C _x H _{2X + 1} means a linear alkyl group having x carbon atoms.

The absorption maximum (λmax) and the molar extinction coefficient (εmax, · mol ^-1 · cm ^-1 unit) of these compounds are as follows.

The optical filter material of the present invention is a material obtained by incorporating the compound represented by the general formula [I] into an appropriate binder to form a composition or coating it on an appropriate support. The binder is not particularly limited, and organic or inorganic binders can be used as long as they exhibit an optical filter function. Examples of such a binder include polymeric materials such as plastics and inorganic materials such as glass.

Preferably, a binder that forms a film having excellent transparency and mechanical properties is used as the binder. Examples of such film-forming binders include polyesters represented by polyethylene terephthalate,
Cellulose diacetate, cellulose triacetate,
Cellulose esters such as cellulose acetate butyrate, polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl compounds such as polystyrene, and acrylic addition weight such as polymethylmethacrylate. Known film-forming binders such as coalesce and polycarbonate made of polycarbonate can be mentioned.

As a method of adding and holding the compound of the above-mentioned general formula [I] to the above-mentioned plastic material, there is a method of compounding it in a plastic sheet at the time of film formation. That is, a compound of the formula [I] is mixed with various additives into a polymer powder or pellets, melted and extruded by a T-die method or an inflation method, or formed into a film by a calender method, whereby the compound is uniformly dispersed. A film is obtained. When a film is produced from a polymer solution by the casting method, the compound of the general formula [I] may be contained in the solution.

Second, there is a method of forming an infrared absorbing layer by applying a polymer solution or dispersion containing the compound of the general formula [I] on the surface of various plastic films or glass plates manufactured by a suitable method. is there. The binder polymer used in the coating solution is selected from those which dissolve the compound of the general formula [I] as much as possible and have excellent adhesiveness to the plastic film or glass plate serving as a support. Polymethylmethacrylate, cellulose acetate butyrate, polycarbonate and the like are suitable for this purpose. The support film may be pre-coated with a suitable undercoat in order to improve the adhesion.

The third method is to mix the compound of general formula [I] and the polymerizable monomer in the light-incident window frame of the device to be cut off infrared rays, add a suitable polymerization initiator, and add heat or light. There is a method of polymerizing and forming a filter material on a window frame with the produced polymer. In this method, the entire device can be embedded with plastics produced from the polymerizable monomer.

The fourth method is a method of depositing the compound [I] of the present invention on a suitable support. In this method, a film-forming binder layer suitable as a protective layer may be provided at a position distant from the support.

In the optical filter material of the present invention, in order to further improve the light resistance, the addition of an ultraviolet absorber is effective, and resorcin monobenzoate, substituted or unsubstituted benzoic acid esters such as methyl salicylate, and 2-oxy-3-methoxy. Cinnamates such as butyl cinnamate, 2,4-
Benzophenones such as dioxybenzophenone, α, β-unsaturated ketones such as dibenzalacetone, 5,7-
Coumarins such as dioxycoumarin, carbostyrils such as 1,4-dimethyl-7-oxycarbostyl, 2
-Aryls such as phenylbenzimidazole and 2- (2-hydroxyphenyl) benzotriazole are used.

In the case of a film prepared by coating the optical filter material of the present invention with a coating method, a thin plastic film can be attached to the surface of the coating layer for the purpose of protecting the coating layer, imparting drip property, and the like. For example, 0.
120-by stacking polyvinyl chloride films with a thickness of 05 mm
A laminated film is obtained by thermocompression bonding at 140 ° C.

In the optical filter material of the present invention, the general formula [I]
0.1 to 50 parts by weight, preferably 0.5 to 5 parts by weight per 1000 parts of the support material (binder) is added. It suffices that the optical filter material has a low transmittance in the wavelength range to be cut off due to its function so that the intended purpose can be achieved. In the case of the present invention, 10% or less is preferable at 900 nm near the valley of the transmittance. It is important to adjust the addition amount per binder and the thickness of the filter material so that the transmittance is 2.0% or less, particularly preferably 0.1% or less. Practical thickness is 0.02mm to 0.5m
However, it is possible to design a filter having a thickness outside this range depending on the application.

(Effect of the Invention) According to the present invention, it is possible to obtain an optical filter material in which a near-infrared absorber is dispersed with good compatibility with a binder.

Further, it is possible to obtain an optical filter material having a large ability to block near-infrared light per unit thickness, a high light transmittance in the visible region, and an excellent fastness to heat and light.

Further, it is possible to provide a safelight filter material having good compatibility with infrared sensitive photosensitive materials.

The optical filter material of the present invention, as an infrared absorbing material, the above-mentioned, safelight filter for infrared-sensitive photosensitive material, control of plant growth, heat ray shielding, infrared cut filter harmful to human eye tissue, semi- It can be used for various applications other than the infrared cut filter of the light receiving / receiving element.

(Example) Next, the present invention will be described in more detail based on examples.

Reference Example 1 <Synthesis of Exemplified Compound (3)> 36 g of potassium hydroxide was dissolved in 600 ml of absolute ethanol, and 50 g of toluene-3,4-dithiol was added to this solution.
Was added and stirred at room temperature for 10 minutes. Then, add 36.8 g of nickel chloride hexahydrate to 400 parts of absolute ethanol.
After adding a solution dissolved in ml, the mixture was stirred at room temperature for another 30 minutes. To this solution, a solution prepared by dissolving 111 g of tetra-n-butylphosphonium bromide in 300 ml of absolute ethanol is added at room temperature. After the addition was completed, the mixture was further stirred at room temperature for 2 hours, and the precipitated dark green crystals were filtered, washed with water first, then ethanol, and air-dried. This was recrystallized from hot acetone-ethanol to obtain exemplary compound (3). Yield 50g. Melting point 162-165 ° C. Reference Example 2 <Synthesis of Exemplified Compound (11)> 36 g of potassium hydroxide was dissolved in 600 ml of absolute ethanol, and 50 g of toluene-3,4-dithiol was added to this solution.
Was added and stirred at room temperature for 10 minutes. Then, add 36.8 g of nickel chloride hexahydrate to 400 parts of absolute ethanol.
After adding a solution dissolved in ml, the mixture was stirred at room temperature for another 30 minutes. 230 g of hexadecyltributylphosphonium bromide was added to this solution, and 300 g of anhydrous ethanol at 50 ° C.
Add the solution dissolved in ml. After the addition was completed, the mixture was further stirred at room temperature for 2 hours, and then the precipitated dark green crystals were filtered,
It was first washed with water, then ethanol and air dried. This was recrystallized from hot ethanol to obtain exemplary compound (11). Yield 43g. Melting point 56 to 60 ° C. Reference Example 3 <Synthesis of Exemplified Compound (15)> 36 g of potassium hydroxide was dissolved in 600 ml of absolute ethanol, and 50 g of toluene-3,4-dithiol was added to this solution.
Was added and the mixture was stirred for 10 minutes at room temperature. Next, add 36.8 g of nickel chloride hexahydrate to 400 m of absolute ethanol.
After the solution dissolved in 1 was added, the mixture was stirred at room temperature for another 30 minutes. A solution of 127 g of benzyltributylphosphonium bromide in 360 ml of absolute ethanol is added to this solution at room temperature. After the addition was completed, the mixture was further stirred at room temperature for 2 hours, then the precipitated dark green crystals were filtered, washed with water first, then ethanol, and air dried. This was recrystallized from hot acetone to obtain exemplary compound (15). Yield 6
3 g. Melting point 213 to 215 [deg.] C. Other exemplary compounds used in the present invention could be synthesized in the same manner as in Reference Examples 1 to 3.

Example 1 Three kinds of optical filter materials were prepared using the exemplified compounds synthesized in Reference Examples 1 to 3. That is, the components shown below in parts by weight, and each component are mixed and stirred well, filtered, coated on a metal support by a casting method, and peeled after film formation to obtain the desired optical Filter materials and were obtained respectively. Dry film thickness of 0.05 to 0.3m
Several types of optical filter materials were obtained which were varied between m.

Composition example TAC (cellulose triacetate) 170 parts TPP (triphenyl phosphate) 10 parts Methylene chloride 800 parts Methanol 160 parts Exemplified compound (3) 2 parts Composition example DAC (cellulose diacetate) 170 parts DEP (diethyl phthalate) 10 parts Methylene chloride 800 parts Methanol 160 parts Exemplified compound (11) 2 parts Composition example PC (polycarbonate (Mitsubishi Gas, E-2000)) 170 parts Methylene chloride 800 parts Exemplified compound (15) 2 parts Optical filter material and spectral transmittance Is shown in FIG. The thickness of the filter material tested is 0.1 m
m.

Example 2 In the same manner as in Example 1, an optical filter material containing a UV absorber and having a thickness of 0.19 mm was prepared. The composition of the casting composition is shown below.

TAC (cellulose triacetate) 170 parts TPP (triphenyl phosphate) 10 parts Methylene chloride 800 parts Methanol 160 parts Exemplified compound (3) 2 parts 2- (5-tert-butyl-2-hydroxyphenyl) benzotriazole 0.2 parts Application Example 1 The optical filter material manufactured in Example 1 (thickness 0.05
(mm) was attached to a silicon photodiode as a near-infrared cut filter, and the operation performance of the photodetector was significantly improved. Furthermore, the operational reliability did not change at all even after the forced aging test at 50 ° C.

Application Example 2 The optical filter material having a thickness of 0.19 mm manufactured in Example 1 was used as a safelight in an infrared-sensitive photosensitive manufacturing and processing field. Even after being used for one year under normal conditions, no change was observed in the absorption characteristics before use.

Test Example (i) Solubility Test The solubility of the complex compound of the present invention represented by the general formula [I] in an organic solvent was measured.

Test compound is of formula , Where “Cat” is Test No. 2 in Table 2.
Figure 4 shows the quaternary phosphonium shown on the Cat shelf for even numbered tests of 4 and less. For comparison, a test was conducted using a quaternary ammonium as "Cat". The results are shown in Table 2, test Nos. 1 and 2 and odd numbers.

Acetone or methylene chloride was selected as the organic solvent. As a measuring method of solubility, 20m with a ground stopper
10 ml of the solvent and 1 g of the sample were placed in a 1-volume glass test tube, shaken in a constant temperature bath (15 ° C.) for 24 hours, and allowed to stand still,
After filtering and distilling off the solvent of the filtrate, a gravimetric method of weighing the residue was adopted.

As is clear from the results in the above table, the phosphonium complex of the present invention (even test No.) has higher solubility in organic solvents than the ammonium complex (odd test No.). Therefore, the composition for film formation or coating can be concentrated. Further, the phosphonium complex of the present invention has excellent compatibility with the plastic binder used for film formation and can easily produce a uniform filter.

(ii) Heat resistance test Exemplified compound (3) and the corresponding ammonium complex, comparative compound (A) Was tested for heat resistance.

The test was performed by using both compounds in the same manner as in the composition example of Example 1 to prepare a filter material having a thickness of 0.19 mm and heating the filter material at 100 ° C. for 24 hours to measure the change in transmittance. . The results are shown in Table 3.

As can be seen from the results in the above table, the phosphonium complex of the present invention maintains the light blocking property in the near infrared region after exposure without lowering the light transmittance in the visible region, and is excellent in heat resistance.

(iii) Light resistance test The light resistance was tested for the exemplified compound (3) and the corresponding ammonium complex, the comparative compound (A).

In the test, using both compounds, the same filter material as in the heat resistance test (ii) was prepared, and a xenon lamp (12
It was measured by irradiating (1,000,000 lux) and measuring the change with time of the transmittance (%). The results are shown in Table 4.

When the UV absorber is used in combination with the phosphonium complex of the present invention, the light resistance of the filter material is remarkably improved. The light resistance of such a filter material was determined such that the weight ratio of the exemplary compound (3) to the ultraviolet absorber 2- (5-t-butyl-2-hydroxyphenyl) benzotriazole (compound (U)) was 10: 1. Table 5 shows the change with time of the transmittance of the filter material under light irradiation when used in combination at a ratio.

As can be seen from the above table, when the compound of the present invention and the ultraviolet absorber are used in combination, the light fastness of the optical filter material can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a graph showing the molecular transmittance of the optical filter material of the present invention, and FIG. 2 is a graph showing the relative sensitivity of the human eye and the SPD to the wavelength of light. In FIG. 1, and are the transmittance curves of the optical filter material and the optical filter material obtained in Example 1, respectively.

Claims (1)

[Claims] 1. An optical filter material containing at least one compound represented by the following general formula. (In the formula, [Cat] represents a quaternary phosphonium group, and M
Represents nickel, cobalt, copper, palladium or platinum. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ represent a hydrogen atom, a halogen atom or a substituted or unsubstituted alkyl group, which may be the same or different from each other. . )