JPH03251747A - Detecting film of substance - Google Patents

Abstract

PURPOSE:To form a sensor which can detect a gaseous substance, by constructing a detecting film of an organic film which is provided with an acid-color-developing dyestuff, an acidic developer and a film-forming macromolecular substance and of which the light absorption spectrum changes due to absorption and desorption of a substance to be inspected. CONSTITUTION:A detecting film is constructed of an organic film which is formed of at least one kind of dyestuff selected from acid-color-developing dyestuffs of triphenylmethane phthalide, fluoran, indolyl phthalide, spiropyran and rhodamine lactam, an acid developer and a film-forming macromolecular substance and of which the light absorption spectrum changes due to absorption and desorption of a substance to be inspected. The substance detecting film thus constructed utilizes a dye being made to take a color-developing structure by a stimulus of an acid or the like, a color former, in particular, as a sensitive part of recognizing the substance. The organic film containing the specified acid-color-developing dyestuff and the acidic developer operates as a functional film which makes absorption and desorption of various substances and of which the absorption spectrum changes in a large degree on the occasion.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a substance detection film, and more particularly to a functional film for optically detecting various substances, especially gaseous substances.

(B) Conventional technology Regarding gas sensors, various detection methods that utilize various physicochemical properties of gases to be detected have been put into practical use. For example, the widely used SnO
, , WO5 and other oxide semiconductors utilize the property that the conductivity changes depending on the adsorbed molecules. However, this requires the gas sensitive part to be heated to a high temperature. In addition, optical interferometer type gas sensors that use light have also been put into practical use. This measures the movement of interference fringes due to the difference in the refractive index of light due to gas. However, such an optical interferometer type gas sensor has the disadvantage that the sensor itself is complicated.

(c) Problems to be Solved by the Invention The present invention was made under such circumstances, and is particularly concerned with a substance that can constitute a sensor that has a simple structure and can easily detect various substances, especially gaseous substances. The aim is to provide a sensing membrane.

(d) Means for Solving the Problems Thus, according to the present invention, (a) acid-chromic pigments selected from triphenylmethane phthalide series, fluoran series, indolylphthalide series, spiropyran series and rhodamine lactam series; Substance detection consisting of an organic film consisting of at least one type of dye, (b) an acidic color developer, and (c) a film-forming polymeric substance, whose light absorption spectrum changes upon adsorption and desorption of the test substance. A membrane is provided.

The substance detection membrane of the present invention utilizes a color former, which is a dye that takes on a color-forming structure when stimulated by an acid or the like, as a sensitive site for substance recognition. In particular, the organic film containing the above-mentioned specific acid color-forming dye (a) and acid color developer (b) acts as a functional film that adsorbs and desorbs various substances and changes the absorption spectrum significantly at that time. This was based on the discovery that

The chromogenic dye (a) used in the present invention is known as a dye used in pressure-sensitive copying machines, and includes crystal violet lactone, fluoran color former, indolylphthalide color former, It is available under the names of spiropyran color former, rhodamine lactam color former, etc.

Among these, preferable chromogenic dyes include the following formulas (1) to
Includes compounds represented by (■).

(The following is a blank space) As the acidic color developer (b) used in the present invention, various acidic color developers that can develop color by cleaving the lactone ring, laflamme ring, spiro ring, etc. of the color-forming dye (a) can be used. Preferred examples include bisphenol A1 bisphenol S1 bisphenol F1 p-benzyl hydroxybenzoate.

On the other hand, as the film-forming polymer substance, the above-mentioned chromogenic dye (a)
Any polymer that is compatible with and acidic color developer (b) and chemically stable may be used, such as polyvinyl acetate, polyvinyl chloride, polyacrylic acid or its ester, polymethacrylic acid or its ester, cellulose acetate. etc. These film-forming polymeric substances contain the above dye (a
) is useful for preventing changes in the optical properties over time and improving the chemical stability of the substance detection film. These polymers may contain various additives that do not inhibit the effects achieved by the present invention (for example, plasticizers such as DOP and TCP, and antioxidants such as phenyl salicylate and 2-hydroxy-4-methoxybenzophenone). etc.) may be included.

The substance detection membrane of the present invention may further contain an alcoholic hydroxyl group-containing compound (d) that is solid at room temperature. The alcoholic hydroxyl group-containing compound (d) is preferably an aliphatic alcohol having 12 or more carbon atoms, such as cetyl alcohol, stearyl alcohol, or aracyl alcohol, or an aromatic alcohol, such as naphthalene methanol or naphthalene ethanol. Such an alcoholic hydroxyl group-containing compound (d) further improves the detection sensitivity of the substance detection membrane of the present invention to the gas to be detected and enables the detection of low concentration gases, and is a preferred embodiment of the present invention. be.

The substance detection membrane of the present invention can basically be composed of a homogeneous mixture of the above three or four components. Here, the dye (a) and the color developer (
Although the content ratio with b) is not particularly limited, a molar ratio of 1:1.5 to 1:10 is usually suitable. In addition, the content ratio of the appropriate form of the alcoholic hydroxyl group-containing compound (d) (
Weight) is usually 10 to 30% (in the substance detection membrane), and the content ratio of the film-forming polymeric substance is 30 to 70% (in the substance detection membrane).

Such a substance detection film can be easily formed by applying an organic solvent solution in which the three or four components mentioned above are dissolved and dispersed onto a substrate using a spinner method, a dipping method, etc., and drying it. Here, as the substrate, a transparent substrate such as a glass plate, a transparent substrate such as a translucent plastic (for example, polymethacrylate or polycarbonate, etc.), or a light reflecting plate made of silver, aluminum, etc. is suitable.

Detection of a substance using the substance detection film formed in this way is performed with the substance detection film interposed between the light emitting part and the light receiving part when the substrate is a transparent substrate. In the case of a reflective plate, the detection is performed with a light emitting part and a light receiving part disposed in the substance detection film.

Then, it is performed by detecting a change in the absorption spectrum of the substance detection film when a gaseous sample containing the test substance is brought into contact with the substance detection film.

Note that the change in the absorption spectrum is usually 400 to 700 nm.
It is suitable to detect within the range of m. Based on such optical methods, ketones such as acetone, lower alcohols such as methanol, ethanol, propatool, butanol, ethers such as diethyl ether, ethyl acetate, methyl cyanide, tetrahydrofuran, 1.4-
Various gasifiable substances and gaseous substances such as dioxane, dimethylformamide, butanone, pyridine, and ammonia can be detected.

(e) Function When the substance detection film of the present invention adsorbs various substances, its absorption spectrum changes based on the interaction between the acid color-forming dye and the acid color developer. Therefore, it becomes possible to easily detect the analyte based on the change in this absorption spectrum.

(f) Example The present invention will be explained in detail below.

Example 1 Crystal violet lactone 51 represented by formula (I)
g, bisphenol A45x9, polyvinyl chloride 50M
After dissolving 9 in tetrahydrofuran (THF), this solution was spin-coded onto a glass substrate,
A substance sensing film (thickness 0.3μ@) of the present invention was formed. FIG. 1 shows the spectrum change of this film in response to ethanol. As described above, the absorbance of the peak near 610 nm is reduced by about 15% for 1.2% ethanol gas, and the absorption peak is no longer visible at 3%. In addition, the peak absorbance of this film decreased for methyl cyanide gas, and the peak became almost invisible at high concentrations.

Example 2 Crystal violet lactone (1) 5 mg, bisphenol fi, 4519, cellulose acetate 20m9
After dissolving in dimethylformamide (DMF), a film was formed by spin-coding on a glass substrate. FIG. 2 shows the spectrum change with respect to acetone gas at this time. It can thus be seen that the absorbance of the peak near 610 nm decreases by 35% with 3% acetone gas.

Example 3 Color former 5ytg shown by formula (II), bisphenol A45yg, polyvinyl chloride 5019, T
After dissolving in HF, a film was formed by spin coding on a glass substrate. FIG. 3 shows the spectrum change of this film in response to acetone gas.

The absorbance of the peak between 520 and 560 na is reduced by acetone gas.

Example 4 Color former 5xy represented by formula (m), bisphenol A 45g9, and polyvinyl chloride 50Rg were added to THF.
A film was formed by spin-coding on a glass substrate. This membrane is 440-470rl1
It has absorption peaks around 11 and 610 nm,
It was found that the absorbance of both peaks was reduced by about 23% by 3% ethanol gas.

Example 5 A film was formed by dissolving 12Mg of indolyl-based coloring dye represented by formula (■), bisphenol A 38 H, and polyvinyl chloride 5019 in tetrahydrofuran (THF) and then performing spin coding.

The spectrum change of this film in response to ethanol gas is
It is shown in Figure 4. In this way, the absorbance of the peak near 535rv+ decreases by 40% with 2.4% ethanol gas.

Example 6 5 mg each of coloring dyes represented by formulas (1) to (■)
, bisphenol A 451g, polyvinyl chloride 50Mg
Eight types of films were formed by dissolving in THF and spin-coding at a ratio of .

The color of this film becomes lighter due to the gases of acetone, methanol, ethanol, n~propertool, 1so-propertool, butanol, diethyl ether, ethyl acetate, methyl cyanide, butanone, and ammonia.
It was found to have gas sensitivity.

Example 7 Each coloring dye produced in Example 6 was exposed to 1.6% ethanol gas. At that time, the rate of change in absorbance at the maximum absorption wavelength was measured. As shown in Table 1, the absorbance decreased in both cases, although there were differences in the proportions.

table! Implementation PI 8 A film was formed by dissolving 10% of crystal violet lactone (1), 40Mg of bisphenol A, 5019 polyvinyl chloride, and 25JI9 of naphthalene ethanol in THF, and then performing spin coding.

FIG. 5 shows the change in absorbance with respect to the ethanol gas concentration for the samples with and without naphthalene ethanol. It can be seen that the membrane containing naphthaleneethanol can detect ethanol gas at a lower concentration.

(G) Effects of the Invention The substance detection film of the present invention changes its absorption spectrum through the adsorption phenomenon of various substances, particularly gaseous substances, thereby making it possible to optically detect the analyte. .

Therefore, by using the substance detection film of the present invention, a substance detection element having a simple structure can be constructed, and various substances, especially gaseous substances, can be easily detected.

[Brief explanation of drawings]

FIGS. 1 to 4 are graphs illustrating changes in absorption spectra when various substances are adsorbed to the substance detection membrane of the present invention, respectively;
FIG. 5 is a graph showing the effect of adding an alcoholic hydroxyl group-containing compound. Suitable length (nm) Groove 21!1 Five tables (n m) Fast fruit (nm)

Claims (1)

[Scope of Claims] 1. (a) at least one type of dye selected from triphenylmethane phthalide-based, fluoran-based, indolyl phthalide-based, spiropyran-based, and rhodamine lactam-based acid coloring dyes; (b) A substance detection film comprising an acidic color developer; and (c) an organic film made of a film-forming polymeric substance and whose light absorption spectrum changes upon adsorption and desorption of a test substance. 2. The substance detection membrane according to claim 1, further comprising an alcoholic hydroxyl group-containing compound that is solid at room temperature.