JP7578653B2 - Phosphine detector - Google Patents

Description

The present invention relates to a phosphine detector.

Fumigation with phosphine _PH3 is widely carried out in warehouses, on ships, and inside equipment to eliminate pests. For example, fumigation on a cargo ship usually involves exposing the cargo to a prescribed amount of phosphine for several days or more with the cargo holds closed.

However, because phosphine is harmful to humans, it is necessary to detect phosphine in the environment. Traditionally, detection of phosphine in the environment has been carried out using gas measurement devices equipped with gas detection mechanisms such as electrically powered sensors, and gas detector tubes. When using gas detector tubes, detection is carried out using gas samples that are intermittently drawn in from the environment either manually or electrically.

Patent Document 1 discloses a gas measurement device that uses detection paper carrying a reagent that reacts with multiple types of measurement gases, such as phosphine, to produce a reaction mark that changes in optical density. This gas measurement device can measure the types and concentrations of multiple types of measurement gases.

JP 2015-232532 A

In recent years, it has become desirable to know the level of past phosphine exposure for each item that has been subjected to fumigation. In order to detect the level of past phosphine exposure, it is preferable to be able to constantly detect the phosphine exposure concentration for each item. Furthermore, in order to constantly detect the phosphine exposure concentration for many items loaded onto cargo ships, etc., a detector that does not require human intervention is required.

However, the gas measuring device of Patent Document 1 requires electricity. For this reason, it is difficult for the gas measuring device of Patent Document 1 to constantly detect the phosphine exposure concentration of small individual items, and there is also the problem that the cost of constant detection is high. In addition, gas detection tubes intermittently aspirate and detect gas samples, so there is a problem that they cannot constantly detect the phosphine exposure concentration.

The present invention has been made in consideration of the problems inherent in the conventional technology. The object of the present invention is to provide a highly responsive phosphine detector that can continuously detect phosphine without power consumption.

The phosphine detector according to this embodiment of the present invention comprises a support and a phosphine detector supported on the surface of the support and including a plurality of basic copper carbonate particles, a plurality of cellulose fibers, and a binder that binds the plurality of basic copper carbonate particles and the plurality of cellulose fibers. The average particle diameter of the basic copper carbonate particles is 0.01 μm or more and 1 μm or less. The average length of the cellulose fibers is 5 μm or more and 30 μm or less. The average particle diameter of the binder is 80 nm or more and 1 μm or less. The average fiber diameter of the cellulose fibers is larger than the average particle diameter of the binder.

The present invention provides a highly responsive phosphine detector that can continuously detect phosphine without power consumption.

FIG. 1 is a schematic plan view showing an example of a phosphine detection element according to an embodiment of the present invention. 2 is a schematic cross-sectional view of the phosphine detector according to the present embodiment taken along line II-II in FIG. 1. This shows the results of evaluating the response to phosphine exposure due to differences in binder types. This shows the results of evaluating the responsiveness to phosphine exposure depending on the film thickness of the phosphine detection part. This shows the results of evaluating the response to phosphine exposure due to differences in the composition of the phosphine detection part.

The phosphine detector according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[Phosphine detector]
Fig. 1 is a plan view of a phosphine detection element 1 according to this embodiment. Fig. 2 is a cross-sectional view of the phosphine detection element 1 according to this embodiment taken along line II-II in Fig. 1. As shown in Figs. 1 and 2, the phosphine detection element 1 comprises a support 10 and a phosphine detection section 20 supported on the surface of the support 10.

(Support)
The support 10 supports the phosphine detection unit 20. The material of the support 10 is not particularly limited, and may include, for example, at least one material selected from the group consisting of paper, plastic, metal, ceramics, and wood. The support 10 may be capable of supporting the phosphine detection unit 20 at least on the surface of the support 10. For this reason, the phosphine detection unit 20 may be formed inside the support 10 in addition to on the surface of the support 10 by impregnating the inside of the support 10 with a detection ink described below.

The support 10 may be, for example, paper. Paper is carbon neutral and can reduce carbon dioxide emissions into the atmosphere. In addition, paper is inexpensive and flammable, so it can be easily disposed of together with other constituent materials.

The support 10 may be, for example, a label sticker. By simply printing the phosphine detection unit 20 on the label sticker, it can be easily used as an indicator that can be attached to an object.

The shape of the support 10 is not particularly limited as long as it can support the phosphine detection unit 20. Examples of the shape of the support 10 include a flat plate, a curved plate, and a polygonal prism such as a cube or a rectangular parallelepiped.

When the support 10 is a flat plate, the thickness of the support 10 may be 0.1 mm or more and 5 mm or less. When the thickness of the support 10 is within the above range, it is easy to handle as a phosphine detector 1. The thickness of the support 10 may be 0.2 mm or more. In addition, the thickness of the support 10 may be 2 mm or less, 1 mm or less, or 0.5 mm or less.

(Phosphine detection unit)
The phosphine detection unit 20 includes a plurality of basic copper carbonate particles, a plurality of cellulose fibers, and a binder. In the phosphine detection unit 20, gaps may be formed between the cellulose fibers by each of the plurality of cellulose fibers. Furthermore, each of the plurality of basic copper carbonate particles may be disposed between each of the plurality of cellulose fibers.

<Basic copper carbonate particles>
Basic copper carbonate is reactive to phosphine and is chemically stable when exposed to substances other than phosphine. Specifically, basic copper carbonate is less likely to discolor due to temperature and humidity compared to copper acetate. Also, basic copper carbonate is not excessively reactive compared to silver acetate. More specifically, silver acetate can detect phosphine at a low concentration such as 1 ppm, but is prone to discoloration due to temperature, humidity and light, making it difficult to determine whether it is exposed to a concentration such as 100 ppm. On the other hand, basic copper carbonate has different reactivity depending on the exposure concentration and exposure time of phosphine. Therefore, by using basic copper carbonate, a phosphine detection unit 20 can be formed in which the reactivity to the exposure concentration and exposure time of phosphine is controlled.

The basic copper carbonate may contain Cu(OH) _{2.CuCO 3} , also known as malachite. Cu(OH) _{2.CuCO 3} has the property of being green before exposure to phosphine, and turning black when reduced by exposure to phosphine. It is presumed that the color of Cu(OH) _{2.CuCO 3} changes to black due to Cu, which is a reaction product of Cu(OH) _{2.CuCO 3} and phosphine, as shown in the following reaction formula (1). Note that the by-product of the following reaction formula (1) contains, for example, a solid derived from phosphoric acid.

2Cu(OH) _{2.CuCO 3} +PH ₃ →Cu+byproduct (1)

In addition, copper phosphate and copper oxide (Cu ₂ O) produced due to the reaction of 2Cu(OH) _{2.CuCO 3} with phosphine also react with phosphine to produce black reaction products.

Gaps may exist between the multiple basic copper carbonate particles contained in the phosphine detection unit 20. The average particle diameter of the basic copper carbonate particles is not particularly limited, but may be smaller than the average fiber diameter of the cellulose fibers. In such a case, the cellulose fibers can form appropriate gaps, so that the reactivity of the phosphine detection unit 20 can be maintained at a good level.

Specifically, the average particle diameter of the multiple basic copper carbonate particles is 0.01 μm or more and 1 μm or less. When the average particle diameter is 0.01 μm or more, the basic copper carbonate particles fill the gaps between the fibers, and the internal basic copper carbonate particles can be prevented from being less exposed to phosphine. When the average particle diameter is 1 μm or less, the specific surface area of the basic copper carbonate particles increases, and the reactivity increases. In addition, since the cellulose fibers can form appropriate gaps, the reactivity of the phosphine detection unit 20 can be maintained at a good level. The average particle diameter of the basic copper carbonate particles may be 0.05 μm or more, or may be 0.1 μm or more. The average particle diameter of the basic copper carbonate particles may be 0.5 μm or less, or may be 0.2 μm or less. In this specification, unless otherwise specified, the value of "average particle size" is the value calculated as the average particle size of particles observed in several to several tens of fields of view using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

The content of the multiple basic copper carbonate particles is preferably 30% by mass or more and 50% by mass or less with respect to the phosphine detection unit 20. By making the content of the basic copper carbonate particles 30% by mass or more, the responsiveness of the phosphine detection unit 20 becomes higher. Furthermore, by making the content of the basic copper carbonate particles 50% by mass or less, it is possible to suppress the occurrence of cracks in the phosphine detection unit 20. The content of the basic copper carbonate particles may be 35% by mass or more. Furthermore, the content of the basic copper carbonate particles may be 45% by mass or less, or may be 40% by mass or less.

The shape of the basic copper carbonate particles is not particularly limited, and may be at least one shape selected from the group consisting of needle-like, angular, dendritic, fibrous, flaky, irregular, teardrop-like, and spherical.

The specific surface area of the basic copper carbonate particles is not particularly limited. The larger the specific surface area, the higher the reaction responsiveness tends to be.

<Cellulose fiber>
The cellulose fibers are entangled to form gaps between the cellulose fibers. The gaps improve the air permeability, so that when the phosphine detection unit 20 is exposed to phosphine, the phosphine easily comes into contact with the basic copper carbonate particles. The cellulose fibers can also support the basic copper carbonate particles.

Cellulose fibers can reduce carbon dioxide emissions into the atmosphere from the perspective of carbon neutrality. In addition, cellulose fibers are industrially produced in various sizes, so they can be obtained cheaply, and can be selected according to the purpose, such as controlling the reactivity due to voids, making them easy to form into films and mold. Cellulose fibers are also safer than carbon nanofibers and ceramic fibers, and there is no need to worry about their effects on the respiratory system, so they can be handled safely during production and use. Cellulose fibers are also flammable and easy to dispose of, and basic copper carbonate is also easily disposed of together with copper oxide (II), carbon dioxide, and water at 220°C. Furthermore, cellulose fibers are less likely to have a negative effect on reactivity.

The average length of the multiple cellulose fibers is 5 μm or more and 30 μm or less. When the average length of the cellulose fibers is 5 μm or more, appropriate gaps are formed, and the reactivity of the phosphine detection unit 20 is increased. Furthermore, when the average length of the cellulose fibers is 30 μm or less, problems are less likely to occur when printing the detection ink by screen printing. The average length of the cellulose fibers may be 6 μm or more. Furthermore, the average length of the cellulose fibers may be 20 μm or less, or 10 μm or less.

The average fiber diameter of the multiple cellulose fibers is larger than the average particle diameter of the binder. This configuration creates appropriate voids within the phosphine detection unit 20, making it easier for the basic copper carbonate particles to react with phosphine when the phosphine detection body 1 is exposed to phosphine.

The average fiber diameter of the multiple cellulose fibers may be 5 μm or more and 30 μm or less. When the average fiber diameter of the cellulose fibers is 5 μm or more, appropriate gaps are formed, and the reactivity of the phosphine detection unit 20 is increased. Furthermore, when the average fiber diameter of the cellulose fibers is 30 μm or less, problems are less likely to occur when printing the detection ink by screen printing. The average fiber diameter of the cellulose fibers may be 6 μm or more. Furthermore, the average fiber diameter of the cellulose fibers may be 20 μm or less, or 10 μm or less.

The average length relative to the average fiber diameter of the cellulose fibers (aspect ratio) may be 1 or more and 1.5 or less. When the aspect ratio is 1 or more, appropriate voids are formed, and the reactivity of the phosphine detection unit 20 is increased. Furthermore, when the aspect ratio is 1.5 or less, problems are less likely to occur when the detection ink is printed by screen printing. The aspect ratio may be 1.3 or less, or may be 1.1 or less.

Unless otherwise specified, the average length and average fiber diameter of multiple cellulose fibers are calculated as the average length or diameter of cellulose fibers observed in several to several tens of fields of view using an observation method such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

The cellulose fiber content may be 20% by mass or more and 40% by mass or less with respect to the phosphine detection unit 20. By making the cellulose fiber content 20% by mass or more, it is possible to suppress the occurrence of cracks in the phosphine detection unit 20. Furthermore, by making the cellulose fiber content 40% by mass or less, the responsiveness of the phosphine detection unit 20 is increased. The cellulose fiber content may be 30% by mass or more. Furthermore, the cellulose fiber content may be 35% by mass or less.

<Binder>
The binder binds a plurality of basic copper carbonate particles and a plurality of cellulose fibers. The binder is a plurality of particles. The material of the binder is not particularly limited, but an organic binder may be used. The binder may contain, for example, at least one of a resin and a cellulose nanofiber. The resin used in the binder may contain at least one selected from the group consisting of an acrylic resin, an epoxy resin, a vinyl resin, and a cellulose resin. Examples of the cellulose resin include hydroxyethyl cellulose.

The average particle diameter of the binder is 80 nm or more. By having the average particle diameter of the binder be 80 nm or more, the gaps formed by the cellulose fibers are prevented from being filled, the breathability of the phosphine detection unit 20 is maintained, and good reactivity can be obtained when the phosphine detection body 1 is exposed to phosphine. The average particle diameter of the binder may be smaller than the average particle diameter of the basic copper carbonate particles. The average particle diameter of the binder is 1 μm or less. When the average particle diameter is 1 μm or less, the cellulose fibers can form appropriate gaps, so that the reactivity of the phosphine detection unit 20 can be maintained at a good level. The average particle diameter of the binder may be 90 nm or more. In addition, the average particle diameter of the binder may be 500 nm or less, 200 nm or less, 150 nm or less, or 120 nm or less. In this specification, unless otherwise specified, the value of "average particle size" is the value calculated as the average particle size of particles observed in several to several tens of fields of view using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

The shape of the binder is not particularly limited, and may be at least one shape selected from the group consisting of needle-like, angular, dendritic, fibrous, flake-like, irregular, teardrop-like, and spherical.

The binder content may be 25% by mass or more and 40% by mass or less with respect to the phosphine detection unit 20. By setting the binder content within the above range, the responsiveness of the phosphine detection unit 20 can be improved. The binder content may be 27 parts by mass or more. In addition, the binder content may be 38% by mass or less, 33% by mass or less, or 30% by mass or less.

As shown in Figures 1 and 2, the phosphine detection unit 20 of the phosphine detection body 1 has a trapezoidal cross-sectional shape. However, the phosphine detection unit 20 of this embodiment may have a cross-sectional shape other than a trapezoid, for example, a rectangular shape. The phosphine detection unit 20 may also be shaped like a barcode or a QR code (registered trademark).

The thickness of the phosphine detection unit 20 may be 20 μm or more and 200 μm or less. When the thickness of the phosphine detection unit 20 is 20 μm or more, the coloring of the phosphine detection unit can be clearly confirmed. Furthermore, when the thickness of the phosphine detection unit 20 is 200 μm or less, cracks are less likely to occur on the surface of the phosphine detection unit 20, and unevenness in the reaction of the phosphine detection unit 20 can be suppressed. The thickness of the phosphine detection unit 20 may be 50 μm or more. Furthermore, the thickness of the phosphine detection unit 20 may be 120 μm or less, or 80 μm or less.

The phosphine detector 1 is placed on the surface of or within the object to be measured, which is to be the subject of measurement of phosphine exposure. When placing the phosphine detector 1 on the surface of or within the object to be measured, it may simply be placed on the object, or it may be attached using an adhesive, adhesive tape, etc.

Next, the action of the phosphine detector 1 will be described. The phosphine detector 20 of the phosphine detector 1 changes color before and after exposure to a predetermined amount of phosphine. For example, basic copper carbonate Cu(OH) _2.CuCO3 contained in the phosphine detector ₂₀ has the property of being green before exposure to phosphine and changing color to black when reduced by exposure to phosphine.

The discoloration of the phosphine detection unit 20 maintains the color after discoloration once it has changed color. Therefore, the phosphine detection body 1 can detect the level of the phosphine exposure concentration in the past. The discoloration of the phosphine detection unit 20 can be detected visually or by machine to determine the degree of discoloration. Furthermore, since the discoloration is based on the reduction of basic copper carbonate by phosphine, it occurs without electricity. Furthermore, since the above action occurs without electricity, phosphine exposure can be detected at all times. Furthermore, since the discoloration occurs only in the phosphine detection body 1, the phosphine detection body 1 can be made smaller within the range in which the discoloration can be detected.

The phosphine detector 1 of this embodiment includes a support 10 and a phosphine detector unit 20 supported on the surface of the support 10 and including a plurality of basic copper carbonate particles, a plurality of cellulose fibers, and a binder that binds the plurality of basic copper carbonate particles and the plurality of cellulose fibers. The average particle diameter of the basic copper carbonate particles is 0.01 μm or more and 1 μm or less. The average length of the cellulose fibers is 5 μm or more and 30 μm or less. The average particle diameter of the binder is 80 nm or more and 1 μm or less. The average fiber diameter of the cellulose fibers is larger than the average particle diameter of the binder.

According to the phosphine detector 1, the color of the phosphine detector 20 changes before and after exposure to a predetermined amount of phosphine. Therefore, the phosphine detector 1 is small, does not require electricity, and can constantly detect phosphine.

In addition, the multiple basic copper carbonate particles, multiple cellulose fibers, and binder in the phosphine detection unit 20 have a predetermined size. Therefore, appropriate gaps are formed between the cellulose fibers, maintaining the breathability of the phosphine detection unit 20, and good reactivity can be obtained when the phosphine detection body 1 is exposed to phosphine.

Note that basic copper carbonate is an insulator, and when it reacts with phosphine, copper, which is a conductor, is produced from basic copper carbonate. Therefore, it may be possible to electrically detect copper. For example, by incorporating the phosphine detector 1 into an RFID (radio frequency identifier), it may be possible to detect it remotely.

[Method of manufacturing phosphine detector]
Next, a method for producing the phosphine detection element 1 according to this embodiment will be described. The phosphine detection element 1 can be obtained by forming a phosphine detection unit 20 on the surface of a support 10. Specifically, the phosphine detection element 1 according to this embodiment may include a step of preparing a detection ink, a step of applying the detection ink to the support 10, and a step of removing the dispersion liquid.

In the step of preparing the detection ink, a detection ink containing basic copper carbonate particles, cellulose fibers, and a binder is prepared. The detection ink can be obtained by mixing the basic copper carbonate particles, cellulose fibers, and the binder by stirring or the like. The basic copper carbonate particles, cellulose fibers, and binder can be those described above.

The detection ink may be prepared using a binder liquid dispersed in a dispersion liquid. The binder liquid has fluidity in the detection ink, and when the phosphine detection unit 20 is formed, the binder contained in the phosphine detection unit 20 binds the basic copper carbonate particles and the cellulose fibers. The binder liquid containing the binder may be a slurry or an emulsion. The dispersion liquid contained in the binder liquid may be, for example, an inorganic solvent such as water, or an organic solvent such as alcohol.

If necessary, the detection ink may contain a dispersion liquid that adjusts the fluidity of the detection ink. However, if the detection ink has the desired fluidity with the dispersion liquid contained in the binder liquid, additional dispersion liquid does not need to be added to the detection ink. For example, an inorganic solvent such as water or an organic solvent such as alcohol is used as the dispersion liquid. The dispersion liquid contained in the binder liquid and the dispersion liquid additionally added to the detection ink may be the same type or different types. Of these, it is preferable to use water as the dispersion liquid from the viewpoint of environmental consideration.

In the step of applying the detection ink to the support 10, the ink prepared in the step of preparing the detection ink is applied to the support 10. The method of applying the detection ink to the support 10 is not particularly limited, and the detection ink can be applied, for example, by dripping, coating, spraying, printing, or a combination of these. Examples of dripping include dripping onto the support 10 using a dropper or pipette. Examples of coating include coating using a bar coater. Examples of printing include screen printing, toner printing, inkjet printing, letterpress printing, intaglio printing, or a combination of these. Among these, it is preferable to apply the detection ink to the support 10 by screen printing, from the viewpoint of being able to make the film thickness uniform.

In the step of removing the dispersion liquid, the dispersion liquid is removed from the detection ink applied to the support 10. By removing the dispersion liquid from the detection ink, a phosphine detection unit 20 is formed, which includes a plurality of basic copper carbonate particles, a plurality of cellulose fibers, and a binder that binds the plurality of basic copper carbonate particles and the plurality of cellulose fibers together. Methods for removing the dispersion liquid include filtration such as suction filtration, natural drying at room temperature, drying by heating, and combinations of these.

According to the method described above, it is possible to manufacture a phosphine detector 1 having the above-mentioned support 10 and phosphine detector 20.

The present embodiment will be described in more detail below with reference to examples and comparative examples, but the present embodiment is not limited to these examples.

The following materials were prepared as raw materials for the detection inks of the Examples and Comparative Examples.
(1) Basic copper carbonate particles Cu(OH) _2.CuCO3 (Kanto Chemical Co., Ltd., copper(II) carbonate (basic), 2N5), average particle size 1 _μm
(2) Cellulose fiber NP Fiber W-06MG (Nippon Paper Industries Co., Ltd.), fiber diameter 6 μm, fiber length 6 μm
(3) Binder (3-1) Binder A
Saibinol (registered trademark) EC-2020 (Saiden Chemical Co., Ltd.) Acrylic resin emulsion, concentration 42 wt%, viscosity 1,040 mPa·s, particle size 100 nm, Tg 11°C
(3-2) Binder S
BiNFi-s WFo-10002 (Sugino Machine Co., Ltd.), cellulose nanofiber-containing aqueous slurry, concentration 2% by mass, viscosity 6,000 mPa·s, fiber diameter 10 nm to 50 nm, fiber length several to several tens of μm,
(3-3) Binder N
Cellenpia (registered trademark) TEMPO oxidized CNF (1% standard product) (Nippon Paper Industries Co., Ltd.), cellulose nanofiber-containing aqueous slurry, concentration 1% by mass, viscosity 4,500 mPa·s, fiber diameter 4 nm, maximum fiber length approximately 1 μm (3-4) Binder C
Hydroxyethyl cellulose (reagent: H0392) (Tokyo Chemical Industry Co., Ltd.), water-soluble cellulose powder, viscosity 5,500 mPa·s (when dissolved in 2% water), fiber diameter 0.4 nm, fiber length up to 3 μm
(4) Water: Ion-exchanged water (electrical conductivity 0.1 μS/cm)

[Example 1]
First, basic copper carbonate particles were pulverized to an average particle size of about 0.1 μm. Next, 0.2 g (8.6 mass%) of the pulverized basic copper carbonate particles, 0.2 g (8.6 mass%) of cellulose fiber, 0.408 g (7.4 mass%) of binder, and 1,520 μL (75.5 mass%) of water were mixed and stirred for 3 hours to prepare a detection ink. Binder A was used as the binder.

Next, the measured amount of detection ink was applied to a support (label sticker, A-one (registered trademark) 72244, 3M) with a bar coater to a coating thickness of 100 μm, and then dried and cured at 25°C for about 1 hour. A phosphine detection element was then produced, which contained 35% by mass of basic copper carbonate particles, 35% by mass of cellulose fiber, and 30% by mass of binder, and had a phosphine detection portion with a film thickness of approximately 30 μm formed on the support.

[Comparative Example 1]
First, basic copper carbonate particles were pulverized to an average particle diameter of about 0.1 μm. Next, 0.2 g (2.7% by mass) of the pulverized basic copper carbonate particles, 0.2 g (2.7% by mass) of cellulose fiber, 3.529 g of binder (0.9% by mass of binder component), and 3530 μL (93.7% by mass) of water were mixed, and then stirred for 3 hours to prepare a detection ink. Binder S was used as the binder.

Next, the measured amount of detection ink was applied to a support (label sticker, A-one (registered trademark) 72244, 3M) with a bar coater to a coating thickness of 100 μm, and then dried and cured at 25°C for about 1 hour. A phosphine detection element was then produced, which contained 42.5% by mass of basic copper carbonate particles, 42.5% by mass of cellulose fiber, and 15% by mass of binder, and had a phosphine detection portion with a film thickness of approximately 30 μm formed on the support.

[Comparative Example 2]
First, basic copper carbonate particles were pulverized to an average particle diameter of about 0.1 μm. Next, 0.2 g (2.7% by mass) of the pulverized basic copper carbonate particles, 0.2 g (2.7% by mass) of cellulose fiber, 7.058 g of binder (0.9% by mass of binder component), and 0 μL (93.7% by mass) of water were mixed and stirred for 3 hours to prepare a detection ink. Binder N was used as the binder.

Next, the measured amount of detection ink was applied to a support (label sticker, A-one (registered trademark) 72244, 3M) with a bar coater to a coating thickness of 100 μm, and then dried and cured at 25°C for about 1 hour. A phosphine detection element was then produced, which contained 42.5% by mass of basic copper carbonate particles, 42.5% by mass of cellulose fiber, and 15% by mass of binder, and had a phosphine detection portion with a film thickness of approximately 30 μm formed on the support.

[Comparative Example 3]
First, basic copper carbonate particles were pulverized to an average particle diameter of about 0.1 μm. Next, 0.2 g (2.7% by mass) of the pulverized basic copper carbonate particles, 0.2 g (2.7% by mass) of cellulose fiber, 3.529 g of binder (0.9% by mass of binder component), and 3530 μL (93.7% by mass) of water were mixed and stirred for 3 hours to prepare a detection ink. Binder C was used as the binder.

Next, the measured amount of detection ink was applied to a support (label sticker, A-one (registered trademark) 72244, 3M) with a bar coater to a coating thickness of 100 μm, and then dried and cured at 25°C for about 1 hour. A phosphine detection element was then produced, which contained 42.5% by mass of basic copper carbonate particles, 42.5% by mass of cellulose fiber, and 15% by mass of binder, and had a phosphine detection portion with a film thickness of approximately 30 μm formed on the support.

[Comparative Example 4]
First, basic copper carbonate particles were pulverized to an average particle size of about 0.1 μm. Next, 0.5 g (10.5% by mass) of the pulverized basic copper carbonate particles, 0.5 g (10.5% by mass) of cellulose fiber, 0 g of binder (0% by mass of binder component), and 3750 μL (78.9% by mass) of water were mixed and stirred for 3 hours to prepare a detection ink.

Next, the quantitatively collected detection ink was applied to a support (label sticker, A-one (registered trademark) 72244, 3M) with a bar coater to a coating thickness of 100 μm, and then dried and cured at 25°C for about 1 hour. A phosphine detection element was then produced that contained 50% by mass of basic copper carbonate particles and 50% by mass of cellulose fibers, and had a phosphine detection portion with a film thickness of approximately 30 μm formed on the support.

[evaluation]
(Fumigation test)
First, a 100 L acrylic chamber was prepared in a laboratory set at about 25° C. Next, the phosphine detector obtained as described above was placed in the 100 L acrylic chamber. Next, while checking the concentration with a gas detector tube, phosphine standard gas was continuously injected into the acrylic chamber so that the phosphine concentration in the acrylic chamber was 100 ppm. Then, photographs of the phosphine detector were taken at predetermined time intervals. The results are shown in FIG. 3.

As shown in Figure 3, the phosphine detector of Example 1 changed color from green to black after 22 hours of exposure to phosphine, and was able to detect phosphine. On the other hand, the phosphine detectors of Comparative Examples 1 to 4 did not achieve the same sensitivity as Example 1, even after 22 hours of exposure to phosphine. It was also confirmed that the color change in the phosphine detection area increased as the binder diameter increased.

Next, we confirmed the effect of differences in film thickness on the response to phosphine exposure.

[Example 2]
First, basic copper carbonate particles were pulverized to an average particle size of about 0.1 μm. Next, 4 g (14% by mass) of the pulverized basic copper carbonate particles, 4 g (14% by mass) of cellulose fiber, 8.1633 g of binder (12% by mass of binder component), and 12,480 μL (60% by mass) of water were mixed and stirred for 3 hours to prepare a detection ink. Binder A was used as the binder.

Next, the measured amount of detection ink was applied to a support (label sticker, A-one (registered trademark) 64201, 3M) using a screen printer to a thickness of 100 μm, and then dried and cured at 25°C for about 1 hour. A phosphine detection element was then produced, which contained 35% by mass of basic copper carbonate particles, 35% by mass of cellulose fiber, and 30% by mass of binder, and had a phosphine detection section with a film thickness of 30 μm formed on the support.

[Example 3]
A phosphine detector was prepared in the same manner as in Example 2, except that the film thickness of the phosphine detector was 70 μm.

[Example 4]
A phosphine detector was prepared in the same manner as in Example 2, except that the film thickness of the phosphine detector was 100 μm.

[evaluation]
(Fumigation test)
A fumigation test was carried out in the same manner as described above, and the results are shown in Figure 4.

As shown in Figure 4, in all examples, a change in color of the phosphine detection part from green to black due to exposure to phosphine was confirmed. In particular, a clear color change due to exposure to phosphine was confirmed in Example 3, in which the film thickness was 70 μm, and Example 4, in which the film thickness was 100 μm.

Next, we confirmed the effect of different detection ink formulations on response to phosphine exposure.

[Examples 5 to 10]
A phosphine detector was produced in the same manner as in Example 4, except that the detection ink was prepared so that the phosphine detection part had the composition shown in Figure 5.

[evaluation]
(Fumigation test)
A fumigation test was carried out in the same manner as described above, and the results are shown in Figure 5.

As shown in Figure 5, in all examples, a change in color of the phosphine detection section from green to black due to exposure to phosphine was observed. In particular, when the binder amount was 30 mass%, it was confirmed that the responsiveness of the phosphine detection body was superior to when the binder amount was 35 mass%. It was also confirmed that the responsiveness of the phosphine detection body was superior as the content of basic copper carbonate particles was increased. However, although not shown in the figure, if the amount of basic copper carbonate particles was increased too much, there is a risk of an increase in cracks.

These results confirm that it is possible to continuously detect phosphine without power consumption, and that it is possible to provide a highly responsive phosphine detector.

Although the present embodiment has been described above, the present embodiment is not limited to these, and various modifications are possible within the scope of the gist of the present embodiment.

1 Phosphine detector 10 Support 20 Phosphine detector

Claims (7)

A support;
a phosphine detection unit supported on a surface of the support and including a plurality of basic copper carbonate particles, a plurality of cellulose fibers, and a binder that binds the plurality of basic copper carbonate particles and the plurality of cellulose fibers, respectively;
Equipped with
The binder includes a resin,
The average particle size of the plurality of basic copper carbonate particles is 0.01 μm or more and 1 μm or less,
The average length of the plurality of cellulose fibers is 5 μm or more and 30 μm or less,
The average particle size of the binder is 80 nm or more and 120 nm or less,
A phosphine detection element, wherein an average fiber diameter of the plurality of cellulose fibers is larger than an average particle diameter of the binder. The phosphine detector according to claim 1, wherein the binder content is 25% by mass or more and 33% by mass or less relative to the phosphine detector. The phosphine detector according to claim 1 or 2, wherein the content of the multiple basic copper carbonate particles is 30% by mass or more and 50% by mass or less relative to the phosphine detector. The phosphine detector according to claim 1 or 2, wherein the thickness of the phosphine detector is 50 μm or more and 200 μm or less. The phosphine detector according to claim 1 or 2, wherein the average fiber diameter of the cellulose fibers is 5 μm or more and 30 μm or less. 3. The phosphine detector according to claim 1, wherein the binder resin contains an acrylic resin. 3. The phosphine detector according to claim 1, wherein the average particle size of the binder is 80 nm or more and 100 nm or less.

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