JPH0786566B2 - Far infrared selective transmission filter − - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a filter that selectively transmits far infrared rays. More specifically, the present invention relates to a filter that selectively transmits far infrared rays having a wavelength range of about 2 to about 30 μm.

<Prior Art> The wavelength distribution of the radiation from an object is determined according to the temperature of the object, and the radiation from the human body is far-infrared rays in the wavelength range of about 2 to about 30 μm, and the peak is around 10 μm. It is known.

Switches for automatic doors that open and close by detecting the human body operate by detecting the far infrared rays, which are the radiation from the human body, with a sensor, and the light receiving window of the sensor is equipped with a filter for incident light. A filter made of a polyethylene resin containing a specific inorganic pigment is known as a filter made of a synthetic resin containing a compound (Japanese Patent Laid-Open No. 61-
39001 publication).

<Problems to be Solved by the Invention> However, since the filter disclosed in this publication has an insufficient impermeability to visible rays and near infrared rays, the filter is used as a light receiving window material for the above-mentioned sensor to protect the human body. The detection method has a problem of erroneous operation in that it also operates by detecting radiation from an object other than the human body.

The object of the present invention consists of a synthetic resin containing an inorganic compound,
It is to provide a far-infrared selective transmission filter that selectively transmits far-infrared rays having a wavelength range of about 2 to about 30 μm.

<Means for Solving Problems> The inventors of the present invention have conducted extensive studies on a far infrared selective transmitting filter that can be used as a light receiving window material of an excellent sensor that does not cause malfunction. As a result, the inventors have found a filter made of a synthetic resin containing an inorganic compound and selectively transmitting far infrared rays in the wavelength range of about 2 to about 30 μm, and completed the present invention.

That is, the present invention relates to E _{D, T, 1} represented by the following formula (1).
Is 4,000 W / cm ² · deg (solid angle) or more, and
The value of E _{D, T, 2} expressed by the following formula (II) is 300,000 W / cm ² · d
It is a far-infrared selective transmission filter made of a synthetic resin containing an inorganic compound so as to have an eg (solid angle) or less.

(In the formula, J _{λ, T, 1} is the absolute temperature 300 according to Planck's law.
Theoretical intensity of radiation from a black body at ° K, A _{λ, T, 1} is the parallel ray transmittance of the radiation to the filter, E
_{D, T, 1} is the wavelength λ of the radiation transmitted through the filter
Radiation energy in the range of 2.0 to 30.3 μm) (In the formula, J _{λ, T, 2} is the absolute temperature of 285 according to Planck's law.
Theoretical intensity of radiation from a blackbody at ° K, A _{λ, T, 2} is the total light transmittance of the radiation to the filter, E _{D, T, 2}
Of the radiation transmitted through the filter has a wavelength λ of 0.2 to
The energy of radiation in the range of 2.0 μm) As the synthetic resin usable in the present invention, a homopolymer of α-olefin such as polyethylene or polypropylene from the viewpoint of easily transmitting radiation from the human body,
Ethylene-butene copolymers, ethylene-4-methylpeptene-1 copolymers, ethylene-prolene copolymers, ethylene-hexene copolymers, propylene-butene copolymers and other α-olefin copolymers, polyamides, Polyterpenes and the like can be mentioned, these are produced by a known method,
Alternatively, it can be obtained as a commercial product. Density 0.88 ~
0.97 g / cm ² polyethylene, ethylene-butene copolymer and ethylene-4-methylpentene-1 copolymer,
It is particularly preferable from the viewpoint of the transmission of radiation from the human body.

Examples of the inorganic compound that can be used in the present invention include ferrosoferric oxide, carbon black, titanium oxide coated with tin oxide, zirconium oxide and the like, and these can be used alone or in combination of two or more kinds. Of these, triiron tetraoxide with an average particle size of 0.1 to 20 μm and the average particle size
Carbon black of 0.01 to 20 μm is evenly dispersed in the synthetic resin, and the obtained filter has balanced optical characteristics, which is preferable.

Since the optimum mixing ratio of the synthetic resin and the inorganic compound varies depending on the conditions such as the type of the inorganic compound and the thickness of the filter, it may be determined in advance according to the set conditions. For example, when using ferrosoferric oxide as an inorganic compound to obtain a filter with a thickness of 0.2 mm, the compounding ratio is 98.5: 1.
Select from the range of 5 to 95.5: 4.5 (weight ratio).

The synthetic resin and the inorganic compound may be blended by a known method, and examples thereof include a kneading method using a Banbury type kneader.

As a method for molding a filter from a mixture of a synthetic resin and an inorganic compound, a known method such as a method using a pressure molding machine or an injection molding machine can be used.

Since the shape, size, etc. of the filter of the present invention differ depending on its use, it may be determined in advance according to the set use.

When the synthetic resin and the inorganic compound are blended, an additive such as an antistatic agent can be appropriately used as long as the characteristics of the obtained filter are not impaired.

The characteristics of the filter of the present invention and its measuring method are as follows.

As shown in the above formula (I), the characteristic of being transparent to far infrared rays in the wavelength range of about 2 to about 80 μm is that the radiation from a black body at a temperature of 300 ° K, which has almost the same wavelength characteristics as the radiation from a human body. The product of the theoretical intensity J _{λ, T, 1 of the line} and the parallel ray transmittance A _{λ, T, 1} of the radiation to the filter A _{λ, T, 1}
Radiant energy E _{D, T, 1} (W / cm ² obtained by integrating J _{λ, T, 1} in the wavelength range of 2.0 to 30.3 μm
.. (deg.) (Solid angle), and the larger the value of E _{D, T, 1} , the greater the transparency. Here, the value of J _{λ, T, 1} is the theoretical value calculated from the formula of black body radiation according to Planck's law, and the value of A _{λ, T, 1 is} the value of the radiation from the black body that has passed through the filter. It is a measured value obtained by using an infrared spectrophotometer which is designed to measure intensity. Integration wavelength range 2.0 to 30.3
μm is the detection wavelength range of the infrared spectrophotometer used, and this wavelength range is about 2 to 2 which is the wavelength range of radiation from the human body.
It is close to about 30 μm. The value of E _{D, T, 1} is preferably 4,000 W / cm ² · deg (solid angle) or more from the viewpoint of sensitivity when the filter of the present invention is used in a method for detecting a human body.

Next, the characteristic of the filter, which is non-transmissive to radiation outside the wavelength range of about 2 to about 30 μm, is the theoretical intensity I of radiation from a black body at 2854 ° K as expressed by the above formula (II).
_{λ, T, 2} and the total light transmittance A of the radiation to the filter A
_lambda, the product A _lambda with _{T, 2, T, 2 ·} J λ, T, 2 a, wavelength 0.2~2.0μm
Is expressed by the energy E _{D, T, 2} (W / cm ² · deg (solid angle)) of the radiation obtained by integrating in the range of
_The smaller the value of _{D, T, 2,} the greater the impermeability. Where J
The value of _{λ, T, 2} is the theoretical value calculated from the formula of Blackbody radiation according to Planck's law, and the value of A _{λ, T, 2} is the intensity of the radiation from the tungsten lamp passing through the filter, which is visible in the UV. It is a value measured by a near infrared spectrophotometer. The main wavelength range of radiation from a tungsten lamp is 0.2 to 2.0 μ
It is well known that the intensity and wavelength range of this radiation are close to those of the radiation from a black body at 2854 ° K. The values of E _{D, T, D} are, for example, a malfunction when the filter of the present invention is used in a method of detecting a human body,
It is preferably 300,000 W / cm ² · deg (solid angle) or less.

<Effect of the Invention> The filter of the present invention has a wavelength of about 2 which is the radiation from the human body.
It selectively transmits far infrared rays in the range of up to about 30 μm. By using this filter as a light receiving window material of a sensor, for example, it is possible to detect a human body more accurately than before (that is, to suppress malfunction). You can

As shown in Comparative Examples described later, a filter made of polyethylene resin alone (Comparative Example 1) and a filter based on the invention of JP-A-61-39001 described in <Prior Art> (Comparative Example 4 and 5) does not have selective transmittance for the wavelength of the radiation and allows far infrared rays in the wavelength range corresponding to the radiation from the human body to pass through well, but also transmits radiation in the wavelength range shorter than the wavelength range. To do.

On the other hand, the filter of the present invention (Examples 1, 2, and 3)
And 4) have the effect of satisfactorily transmitting far infrared rays in the wavelength range corresponding to the radiation from the human body and significantly suppressing the transmission of radiation in the wavelength range shorter than the wavelength range.

Therefore, the method of detecting the human body using the filter of the present invention as the light receiving window material of the sensor is a cause of malfunction as compared with the method of detecting the human body using the filter obtained in the comparative example as the light receiving window material of the sensor. The signal is small.

A method of detecting a human body by using the filter of the present invention as a light receiving window material of a sensor, for example, is an intrusion alarm device that has been widely spread in recent years.
It is extremely useful as a method for detecting a human body in an automatic door, a visitor alarm, or the like.

<Examples> Examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1 A high-density polyethylene resin manufactured by Sumitomo Chemical Co., Ltd.
Density 0.95g / cm²The Sumikasen Hard 8504 19.6g, east
Western black iron oxide Co., Ltd. with an average particle size of about 1 μm
Knead 4g with heating double roll at 150 ℃ for 5 hours
After that, take out from the same roll as a sheet with a thickness of about 2 mm
It was This sheet was placed on a pressure molding machine set at 180 ° C in advance.
Using pressure 50kg / cm²Press the bottom of the
A rum-shaped filter was obtained. E of this filter_{D, T, 1}
Is 6,100 W / cm²・ It is deg and E_{D, T, 2}Is 34,000 W / cm²・ Deg
Met. The results are summarized in Table 1.

Comparative Example 1 A filter having a thickness of 0.2 mm and made of only high-density polyethylene resin was obtained in the same manner as in Example 1 except that triiron tetraoxide was not used. The characteristics of this filter are shown in Table 1.

Comparative Examples 2 and 3 Example 1 except that the blending ratios of ferrosoferric oxide were 1% by weight (Comparative Example 2) and 5% by weight (Comparative Example 3), respectively.
Filters having thicknesses of 0.2 mm and 0.15 mm were obtained in the same manner as in. The characteristics of these filters are shown in Table 1.

Example 2 19.9 g of the same high-density polyethylene resin as in Example 1 and a cab
The average particle size is 0.015 μm
Black pearl 2000 From 0.1 g, same as in Example 1
A filter having a thickness of 0.15 mm was obtained. This filter
The characteristics of are shown in Table 1.

Example 3 Ethylene-butene-1 copolymer manufactured by Sumitomo Chemical Co., Ltd.
The density is 0.90g / cm²Excellen VL-200 19.94g
Average grain that is carbon black manufactured by Tokai Carbon Co., Ltd.
Seed with a diameter of 0.07 μm Example 1 from S SRF0.06g
A filter having a thickness of 0.15 mm was obtained in the same manner as in. This file
The characteristics of Luther are shown in Table 1.

Example 4 19.0 g of the same high-density polyethylene resin as in Example 1 and titanium oxide coated with tin oxide (Mitsubishi Metals Co., Ltd.)
Made, average particle size 0.2μm, SnO ₂ / TiO ₂ = 1/10 (weight) 1.0g
From the above, a filter having a thickness of 0.25 mm was obtained in the same manner as in Example 1. The filter characteristics are shown in Table 1.

Comparative Examples 4 and 5 The same high density polyethylene resin as in Example 1 was used, and the average particle size was 0.6 μm.
In the same manner as in Example 1 except that 3% by weight (comparative example 4) and 15% by weight (comparative example 5) of titanium oxide (R-550 manufactured by Ishihara Sangyo Co., Ltd.) of m were added, respectively. A 0.2 mm filter was obtained. The characteristics of these filters are shown in Table 1.

Incidentally, these comparative examples are based on the invention disclosed in Japanese Patent Application Laid-Open No. 61-39001 described in <Prior Art>.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Seiichi Shibata, 2-10-1, Tsukahara, Takatsuki City, Osaka Prefecture Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor, Kunimasa Hamaguchi 5-15 Kitahama, Higashi-ku, Osaka, Osaka Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. The value of ED, T, 1 represented by the following formula (I) is 4,000 W.
/ cm ² · deg (solid angle) or more, and the inorganic compound so that the value of ED, T, 2 represented by the following formula (II) is 300,000 W / cm ² · deg (solid angle) or less Far-infrared selective transmission filter made of synthetic resin containing. (In the formula, Jλ, T, 1 is the absolute temperature 300 according to Planck's law.
The theoretical intensity of radiation from a black body at ° K, Aλ, T, 1 is the parallel ray transmittance of the radiation to the filter, ED, T, 1
The wavelength λ of the radiation transmitted through the filter is 2.0 to 3
The energy of radiation in the range of 0.3 μm) (In the formula, Jλ, T, 2 is the absolute temperature of 2854 according to Planck's law.
The logical intensity of radiation from a black body at ° K, Aλ, T, 2 is the parallel ray transmittance of the radiation to the filter, ED, T, 2
Of the radiation transmitted through the filter has a wavelength λ of 0.2 to
The energy of radiation in the range of 2.0 μm)