JPS6139001A - Window material for infrared transmission window - Google Patents

Abstract

PURPOSE:To provide a window material which has high transmissivity in the wavelength region necessary for sensing the movement of a human body and non-transmissivity in a visible light region and functions satisfactorily as a casing as well by combining a PE resin which exhibits a high transmittance characteristic in a specific wavelength region of IR rays and an inorg. pigment having no absorption band with IR rays to form the window material. CONSTITUTION:The window material consists of a sheet molding formed by compounding titanium oxide, barium sulfate, iron oxide red, magnesium oxide, etc. and one kind of inorg. pigment of metallic powder consisting of zinc powder, etc. with the PE resin at 1.5-15pts. in total of the combination thereof and kneading the mixture to 0.1-0.5mm. thickness. The transmittance in the visible light region is thus eliminated without decreasing the characteristic to sense the movement of the human body and the substantial strength as the casing is maintained by the above-mentioned thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a window material used for an infrared transmitting window of, for example, an intruder alarm.

[Technical background of the invention and its problems] In general, moving object sensing devices such as intruder alarms collect infrared radiation energy of 9 to 10 microns emitted by the human body using a spherical mirror, and detect it using a pyroelectric infrared sensor. However, if the spherical mirror is exposed to the outside, dust and the like will adhere to the mirror surface, reducing the light collection efficiency, reducing the sensitivity of the sensor unit, and causing malfunctions. For this reason, it is desirable to hold the light condensing section such as a spherical mirror inside the casing to prevent dust and the like from adhering to it from the outside. However, by holding the spherical mirror in the casing, the window material used on the front surface of the spherical mirror absorbs infrared rays, resulting in lower sensitivity and shorter detection distance.

For this reason, window materials have infrared 9~
It is not possible to use a material that absorbs almost 10 μm, so it is common to use some resins of plastics. The infrared transmission properties of plastics can be increased by making the plate thinner, but depending on the type of plastic, effective infrared transmission properties cannot be obtained unless the film thickness is several microns; By doing so, the visible transmission also increases, which has the drawback that the internal mirrors and sensor circuits of the moving object sensing device can be seen from the outside, and the casing does not have sufficient strength and wrinkles may form.
It has the disadvantage that its appearance detracts from its value as a product. For this reason, the 9~
There is a strong demand for an indium material that can effectively transmit infrared rays of 10 μm, prevent internal mirrors, circuits, etc. from being seen through, and has a sufficient function as a casing.

[Object of the Invention] The present invention has been made in view of the above points.
To provide a window material for infrared transmitting windows that has high transmittance in the wavelength range of 10 μm, non-transmittance in the visible light range, and has an appropriate thickness, and can also function as a casing. purpose.

[Summary of the Invention] The present invention aims to obtain an optical property that satisfactorily transmits infrared radiation energy of 9 to 10 μm emitted by the human body and eliminates transmission in the visible range, and a window material that can be used as a casing material. It is characterized by being a window material molded from a combination of a polyethylene resin that exhibits high transmission characteristics in the infrared range of 9 to 10 μm and an inorganic pigment that does not have an absorption band in the infrared range.

As the thickness of the polyethylene resin film increases, the infrared transmittance decreases, so the amplification period must be increased on the sensor circuit side, which can cause malfunctions, so it is not recommended to increase the infrared transmittance to 50% or more. Because it is desirable, the thickness is set to 0.5
m or less. However, on the other hand, if the length is 0.1 m or less, the infrared transmittance is generally good, but the strength is reduced and the casing is insufficient.

In addition, in order to eliminate visible transmittance, when containing inorganic pigments in polyethylene resin, polyethylene resin 100%
If the layer containing inorganic pigment is more than 15 parts per part, the transmittance will decrease due to reflection of infrared rays by the pigment, and the strength will become brittle and cracks will easily occur.
Furthermore, in order to eliminate visible transmission, the lower limit is
1.5 copies or more is required.

The window material used in the present invention includes polyethylene resin, titanium oxide, barium sulfate, brass, magnesium oxide, etc.
A total of 1.5 to 15 parts of an inorganic pigment such as metal powder such as zinc powder or a combination of these is blended and kneaded, and o
, i~0.5m thick sheet-like molded body.

[Examples of the invention (Examples 1 and 2) 100 parts of polyethylene resin is mixed with 3 parts of fine powder of titanium oxide, which is a pigment, pulverized to a particle size of 1 μm or less, mixed uniformly with a heated mixing roll, and heated. At the press,
A 0.2at sheet and a 3m sheet were molded.

The optical properties of these sheets were determined by transmittance measurements using visible and infrared spectrophotometers. The results are shown in the table.

(Examples 3 to 4) 5 parts and 10 parts of titanium oxide were blended with polyethylene resin and molded in the same manner as in Examples 1 to 2 to a thickness of 0.3 mm.
The transmittance measurement results for the sheet are shown in the same table.

(Comparative Examples 1 and 2) The optical properties of 0.3 mm and 1 halo general commercially available window materials without pigments are shown in the same table for comparison with Examples 1 to 4.

The results in the table show that when applied to the window material of an intruder alarm, the detection distance is longer at 10 to 14 m in Examples 1 to 4, while it is 4 m in Comparative Example 2, and the difference in infrared transmission characteristics is clear. Furthermore, the addition of inorganic pigments eliminates visible transmittance, and compared to Comparative Examples 1 and 2, the interior is no longer visible.

[Effects of the Invention] According to the present invention, transmittance in the visible light range can be eliminated by blending and filling an appropriate amount of an inorganic pigment that does not absorb infrared rays of 9 to 10μ. Since the alarm is difficult to detect and internal mirrors and circuits are not visible, the appearance of the product is improved, and the infrared transmittance can be reduced by selecting an appropriate amount of inorganic pigment. Since this method does not cause any damage, the amount of time required for amplification on circuits such as intruder alarms can be reduced, and circuit costs can also be reduced. Furthermore, the detection distance can be increased, making it possible to use it over a wide range of intrusion routes.

Claims (1)

[Claims] It consists of a sheet-like molded product with a thickness of 0.1 to 0.5 mm mainly composed of an inorganic pigment and a polyethylene resin with an inorganic pigment content of 1.5 to 15 parts per 100 parts of polyethylene resin. Window material for infrared transparent windows.