WO2015034070A1

WO2015034070A1 - Pressure-sensing material, method for producing same, and pressure-sensing paint

Info

Publication number: WO2015034070A1
Application number: PCT/JP2014/073588
Authority: WO
Inventors: 川俣　純; 康孝鈴木; 松尾　英明; 富永　亮; 亮綱島
Original assignee: 国立大学法人山口大学; 日産化学工業株式会社
Priority date: 2013-09-06
Filing date: 2014-09-05
Publication date: 2015-03-12
Also published as: JPWO2015034070A1; JP6341545B2

Abstract

The purpose of the present invention is to provide a pressure-sensing material capable of directly measuring the pressure (stress) acting on a structure, a method for producing the same, and a pressure-sensing paint. The present invention involves: preparing an aqueous solution by dissolving a fluorescent compound in a solvent which mixes with water; preparing a clay-water dispersion by dispersing clay compound particles in water; obtaining a dispersion in which the fluorescent compound adheres to the surface of the clay compound particles; and mixing this heated dispersion with a polymer compound, condensing the product thereof, and obtaining a gel-like pressure-sensing material. The gel-like pressure-sensing material may be used to coat the surface of a structure. When the surface of the structure warps due to stress, the pressure-sensing material emits fluorescent light, and this fluorescent light is retained for a long period of time.

Description

Pressure sensitive material, method for producing the same, and pressure sensitive paint

The present invention relates to a pressure sensing material that emits fluorescence upon sensing pressure, a manufacturing method thereof, and a pressure sensing paint.

Demand to easily measure the stress applied to structures is from a wide range of industrial fields including automobiles and aircraft. For example, by measuring the stress applied to the structure, it is possible to prevent damage to the structure due to external or internal loads, and to develop new materials that can withstand such loads, and to design without waste. Become. In particular, the stress applied to the structure can be determined by identifying the fragile parts of aircraft wings, car engines, etc., identifying deteriorated parts of concrete structures, identifying aging parts of bridge girders, wind turbine blades, etc. There are a wide range of required functions and applications, such as preventive measurement of breakage accidents, preventive measurement of deteriorated parts of power plant turbines, and use for sports tools such as golf heads.

Conventionally, pressure-sensitive materials that emit fluorescence by receiving stress from the outside are known as sensors that detect pressure. Conventionally, the pressure (stress) applied to the surface of the structure has been measured using a surface pressure measuring device or the like. The pressure applied to the surface of the structure can be measured using a pressure sensitive material. The pressure sensitive material is applied to the surface of the structure and measured. When the surface is distorted by stress or the like, the pressure-sensitive material applied to the surface emits fluorescence or the fluorescence wavelength changes. This fluorescence is very convenient for the user because it is visible or can be imaged and analyzed with an imaging device.

Furthermore, since the pressure on the surface of the structure can be measured simply by applying a pressure sensitive material to the structure, there is an advantage that an expensive surface pressure measuring device is not required. Fluorescent materials used for such pressure-sensitive materials include many materials in which a high molecular compound is the main component and the fluorescent compound is chemically bonded to the high molecular compound, or a material in which the fluorescent compound is simply dispersed in the high molecular compound. . This is based on the principle of changing the color tone when a mechanical force is applied to the material from the outside.

Also, in the process of preparing the composition and concentration of a solution in which a fluorescent compound is dispersed in a polymer compound, and in the process of applying the resulting material to a structure, specialized knowledge and skill are required. The polymer-doped type pressure-sensitive material utilizes a phenomenon in which the distance between molecules of the fluorescent compound is changed by pulling. As pressure-sensitive paints, there are those that detect pressure using a fluorescent material such as platinum porphyrin, ruthenium bipyridine complex, and pyrene derivative. The principle of detection is detecting quenching of the fluorescent material by oxygen. Such sensing based on oxygen concentration is mainly used for aircraft stress sensing.

For example, in order to enable stable pressure measurement in a low-oxygen environment such as a low-temperature wind tunnel, a low-oxygen containing a pressure-sensitive dye having luminescence characteristics corresponding to the oxygen pressure and polytrimethylsilylpropyne (PTMSP) as a binder Pressure-sensitive paint for pressure is known and used for wind tunnel tests and the like (Patent Document 1). In addition, the creation of mechanochromic materials whose emission color changes when mechanically stimulated, such as rubbing the surface, has been performed.

For example, a mechanochromic material containing an organic gold complex (C ₆ F ₅ Au) ₂ (μ-1,4-diisocyanobenzene) emits blue light when irradiated with ultraviolet light, and turns yellow when mechanically stimulated. To do. A mechanochromic material in which a flexible triethylene glycol monomethyl ether chain or diethylene glycol monomethyl ether chain is introduced into an organic gold complex (C ₆ F ₅ Au) ₂ (μ-1,4-diisocyanobenzene) When a stimulus such as writing with a soldering iron set at a high temperature is given, the color develops in yellow, and when left for a while, the color changes from yellow to green and becomes almost invisible (Patent Document 2).

Polymer materials that optically detect pressure changes by combining an elastomer selected from polyurethane, polyacrylate, and silicon with a photochemical system are known (see Non-Patent Document 1 and Patent Document 3). This elastomer synthesis and photochemical system forms an excited charge transfer complex when the pressure increases, and reduces the formation of the charge transfer complex when the pressure decreases. In other words, there is an effect that it can respond to the pressing force in addition to the pulling. Further, a polymer binder type pressure-sensitive paint is known (see Non-Patent Document 2). This material uses PtTFPP, which is a kind of porphyrin, as a pressure sensitive dye, and a silicon-based polymer GP197 and glass polymer Poly (TMSP) as a binder.

JP-A-2005-105160 JP 2012-158678 A Special table 2006-508205 gazette

However, since the conventional pressure-sensitive paint senses through the partial pressure of oxygen or the like, the pressure applied to the structure is indirectly measured. There is a need for a pressure sensitive material that can directly measure the pressure applied to the structure. The pressure-sensitive materials or pressure-sensitive paints described above are highly temperature dependent, and improvements are required.

Also, a pressure-sensitive material that can directly measure the pressure applied to the structure has been developed in principle as described above, but has not reached a level that can be used as a paint. Further, even if the pressure-sensitive paint described above is applied to a structure and the pressure applied to the structure is measured, the location where the stress is applied cannot be stored and retained for a long time. In addition, it is difficult to sense the pressing force on the surface, and the accuracy has not reached a practically usable level.

The present invention has been made based on the technical background as described above, and achieves the following objects.
The objective of this invention provides the pressure sensing material which can directly measure the pressure concerning a structure, and a stress, its manufacturing method, and a pressure sensing coating material.
An object of the present invention is to provide a pressure-sensitive material that can be easily adjusted and is easy to use, a manufacturing method thereof, and a pressure-sensitive paint.

In order to achieve the above object, the present invention 1 employs the following means.
The pressure sensing material of the present invention comprises:
A layered compound consisting of a fine particle layer of a compound derived from a clay mineral;
One or more fluorescent compounds sandwiched between a plurality of the layers;
A pressure sensing material filled between the layers and comprising a binder having a molecular size larger than that of the fine particles,
The fluorescent compound emits fluorescence when the layer is deformed by a mechanical force applied from the outside.

The present invention 2 is the pressure sensing material of the present invention 1, wherein the fluorescent compound is an organic fluorescent compound having a biphenylene structure.
Invention 3 is characterized in that, in the pressure sensing material of Invention 1 or 2, the size of the fluorescent compound particles is smaller than that of the fine particles.

The present invention 4 is the pressure sensing material of the present invention 1 or 2, wherein the pressure sensing material comprises one or more compounds selected from a colorant, a filler, a temperature sensitive agent, a temperature sensitive dye, and a plasticizer. It is characterized by having.
The pressure sensitive paint of the present invention 5 contains the pressure sensitive material described in the pressure sensitive material of the present invention 1 to 4.

The manufacturing method of the pressure sensing material of the present invention 6 comprises:
One or more fluorescent compounds;
A layered compound consisting of a fine particle layer of a compound derived from a clay mineral;
A method for producing a pressure sensing material comprising a binder filled between the layers and having a molecular size larger than that of the fine particles,
Obtaining a solution of the fluorescent compound;
A step of dispersing the fine particles in water to obtain a clay water dispersion;
Mixing the solution of the fluorescent compound obtained in the step, the clay aqueous dispersion, and the binder to obtain a mixed solution; and
And concentrating the liquid mixture to obtain the pressure sensitive material.

The pressure sensing material manufacturing method of the present invention 7 is characterized in that in the pressure sensing material manufacturing method of the present invention 6, the binder is a polymer compound.
The pressure sensing material manufacturing method of the present invention 8 is characterized in that, in the pressure sensing material manufacturing method of the present invention 6 or 7, the fluorescent compound is an organic molecule having a biphenylene structure.

The pressure sensing material manufacturing method of the present invention 9 is the pressure sensing material manufacturing method of the present invention 6 to 8, wherein the fluorescent compound has a rod-like shape with a size of 0.5 to 5 nm, The fine particles have a size of 20 to 100 nm.
The pressure sensing material manufacturing method of the present invention 10 is characterized in that, in the pressure sensing material manufacturing method of the present invention 9, the pressure sensing material is a gel-like material and is applied to the surface of a structure. To do.

The method for producing a pressure sensing material of the present invention 11 includes the step of heating before mixing the fluorescent compound solution, the clay aqueous dispersion and the binder in the pressure sensing material production method of the present invention 6 or 7. It is characterized by having.

According to the present invention, the following effects can be obtained.
The pressure-sensitive material and pressure-sensitive paint of the present invention do not require a high degree of expertise when used, and are easier to use than before.
In addition, according to the present invention, the pressure-sensitive paint of the present invention can be used simply by being applied to the structure, and the pressure applied to the structure can be directly measured.

Furthermore, when the pressure sensitive paint of the present invention is applied to a structure and subjected to stress, the fluorescent color changes and long-term fluorescence can be maintained.
Furthermore, the pressure-sensitive material and pressure-sensitive paint of the present invention have made it possible to sense the pressing force, which has been difficult in the past, and to store the location where the stress is applied.

FIG. 1 is a conceptual diagram showing a process for manufacturing the pressure sensitive paint of the present invention. FIG. 2 is a flowchart showing an example of use of the pressure sensitive paint of the present invention. FIG. 3 is a conceptual diagram illustrating a mechanism in which the pressure sensing material of the present invention emits fluorescence. FIG. 4 is a photograph showing a state in which a portion where the substrate coated with the pressure sensitive paint of the present invention is gripped with tweezers emits fluorescence. FIG. 5 is a photograph showing a state in which a character is drawn by cutting with a cutter on a substrate coated with the pressure sensitive paint of the present invention. FIG. 6 is a graph showing the results of an experiment in which the pressure sensitive paint of the present invention is heated and returned to its original state. FIG. 7 shows the measurement results when a rigid molecule is used as the fluorescent compound.

Hereinafter, embodiments of the present invention will be described. The pressure sensing material of the present embodiment is obtained by inserting a solution in which a fluorescent compound and a polymer compound are heated and dissolved between layers of a layered compound derived from clay mineral, and then allowing to cool and solidifying. When mechanical pressure (stress) is applied from the outside and the layered compound is deformed such that the layer of the layered compound is bent or broken, the fluorescent compound in the layer emits fluorescence. That is, when mechanical pressure is applied from the outside, the layer of the layered compound bends, the molecular structure of the polymer compound changes and rearranges, and the layers of the layered compound change, and the structure of the fluorescent compound therein Is considered to change the fluorescent color. Even when the layer of the layered compound is destroyed, it is considered that the structure of the fluorescent compound is changed and the fluorescent color is similarly changed.

〔Structural component〕
The pressure sensing material of the present embodiment basically comprises a layered compound, a binder such as a polymer compound, and a fluorescent compound. This layered compound is fine particles of the order of several tens of nm derived from clay minerals, and the fine particles are adjacent to each other to form a layer. The pressure-sensitive material is composed of a plurality of layered compounds, and a fluorescent compound is sandwiched between these layers. The layered compound and the fluorescent compound are dispersed in a binder.

Since the layered compound is derived from a clay mineral, it can be called a clay compound. In other words, for example, a polymer compound is filled between the layers of the clay compound, and serves as a binder between the layers of the layered compound derived from the clay mineral. As the binder, a polymer compound is preferably used. As the binder, any high molecular compound can be used as long as it is a water-soluble polymer. As the binder, a thermoplastic polymer compound is more preferable, for example, a water-soluble polymer or a polymer having high solubility in a polar solvent compatible with water such as dimethylformamide (DMF) is particularly preferable. The layered compound is dispersed in the coating medium while maintaining the structure and composition of the binder and the fluorescent compound.

〔Manufacturing process〕
FIG. 1 is a conceptual diagram showing a process for manufacturing the pressure sensitive paint of the present invention. A process of manufacturing the pressure sensitive material or pressure sensitive paint of the present invention will be described with reference to FIG. First, a fluorescent compound and a layered clay compound are prepared. A fluorescent compound such as a fluorescent dye is dissolved in a solvent miscible with water to obtain an aqueous solution (first step). And the particle | grains of a clay compound are disperse | distributed to water and a clay water dispersion liquid is obtained (2nd process). The first step and the second step can be performed in parallel or in reverse order.

Next, an aqueous solution of the fluorescent compound is added to the clay aqueous dispersion to obtain a clay compound dispersion in which the fluorescent compound is adsorbed on the surface (third step). At this time, the ratio of the fluorescent compound to the clay aqueous dispersion is 0.1 to 1% by weight. Thereafter, the dispersion is heated at a temperature of 70 to 90 ° C. (fourth step). The polymer compound (polymer polymer) is heated at the same temperature as in the fourth step (fifth step). The fourth step and the fifth step can be performed in parallel, or the order of the steps can be reversed. As the heating means at the time of heating, any known heating means such as a water bath, an oil bath, a sand bath, an oven or the like is used.

When stirring, the solution is heated uniformly when stirred. The heated dispersion and the polymer compound are mixed (sixth step). At this time, the mixing ratio of the clay compound and the polymer compound is about 5: 2 by weight. When mixing the clay compound and the polymer compound, the mixture is sufficiently stirred to be uniform. The solution mixed in the sixth step is concentrated to obtain a clay gel (hereinafter referred to as clay gel) (seventh step). The environment for concentration is normal temperature and normal pressure. In order to concentrate this solution quickly, a method of concentrating the concentrated environment under reduced pressure and high temperature may be used.

FIG. 2 is a flowchart showing an example of using the obtained clay gel, and an example of using the clay gel will be described with reference to this flowchart. First, the obtained clay gel is applied to the surface of an object such as a substrate or a structure such as a structure (also referred to as an “object to be applied”) (reference number 1). After this application, the structure to which the clay gel is applied is dried (reference number 2). This drying environment can be performed at normal temperature and normal pressure, but when it is in a high temperature environment, it dries quickly. Thus, the adjustment and manufacture of the components of the pressure sensitive paint of the present invention are simple.

Specifically, the pressure-sensitive paint of the present invention is a semi-solid gel substance and can be used regardless of the shape of the surface of the object to be coated. In other words, the pressure sensitive paint of the present invention can be applied to a surface of any shape. Of course, it can also be used as a general paint. Furthermore, the pressure-sensitive material of the present invention is not limited to the fluorescent compounds used in the examples described in detail below, and the color tone can be adjusted by using various fluorescent compounds. Stress is applied to the dried structure by applying a pressing force or bending it (reference number 3). At this time, the pressure sensing material on the surface of the structure emits fluorescence (reference number 4).

Or, the color or tone of the fluorescence emitted from the pressure sensing material on the surface of the structure changes (reference number 4). The pressure-sensitive material of the present invention maintains the color tone for a long period of time, for example, close to January, after the stress or pressure load once applied is released (reference number 5). In other words, changes in color tone due to pressure can be stored. Similar conventional sensing paints are used for visual inspection of fragile parts such as aircraft wings / turbine fans, automobile engines, wind power generation fans, etc., but memorize changes in color due to pressure (stress) The period is not as long as that of the present invention.

Also, after removing the stress or pressure applied to the structure and pressure sensing material, the fluorescent color returns to its original state when heated (reference numbers 6 and 7). At this time, the period until the original color tone is restored depends on the heating period, the heating temperature and the like. When the heating temperature is 70 to 90 ° C., the original color tone is quickly restored. For example, when hot air of 70 to 90 ° C. is blown to the surface of the pressure sensing material and heated with a hot air machine, the fluorescent color returns to the original state.

〔paint〕
The pressure-sensitive material of the present invention produced as described above can be applied to the surface of an object and used as a paint. Moreover, a temperature sensitive material etc. can be mixed with the pressure sensing material of this invention, and it can be used also as a coating material with a temperature / pressure sensor function. Furthermore, by mixing the pressure sensing material of the present invention with a moisture sensitive paint, it can also be used as a paint having a humidity / pressure sensor function. Furthermore, by combining the pressure sensing material of the present invention with a temperature sensitive paint and a moisture sensitive paint, it is also possible to provide a combined function of a temperature sensor, a humidity sensor, and a pressure sensor.

[Fluorescence mechanism]
The polymer compound and the clay mineral constituting the pressure sensing material of the present invention are bonded to each other, and the polymer compound serves as a binder for increasing the strength of the pressure sensing paint of the present invention. The layered compound of the pressure sensing material of this embodiment forms a space containing a fluorescent compound, and is a clay mineral. In general, the main component of clay mineral is a kind of inorganic layered compound composed of oxides of silicon and aluminum. The clay mineral has a negative charge on the surface, and has a cation such as sodium or calcium between the layers of the clay mineral in order to compensate for the negative charge.

Since this cation can be easily exchanged with other cationic molecules, the cationic molecules are adsorbed on the surface thereof. Molecules thus incorporated are forced into a planar structure between layers of clay minerals.
In the case of the present invention, the fluorescent compound has a cationic property, and this cation is adsorbed on the clay mineral. Therefore, it is considered that the fluorescent compound is adsorbed on the clay mineral layer, and the fluorescent compound has a planar structure along the clay mineral layer. When the three-dimensional structure between this layer of clay minerals changes, the fluorescent compound in it fluoresces.

Fluorescent compounds exhibit different characteristics depending on the degree to which this three-dimensional structure changes. By utilizing this fact, the pressure sensing material of the present invention changes the fluorescent color depending on the degree of external pressure (stress). Also, in order to ensure uniformity when a paint having a clay compound layer and a fluorescent compound is applied to the surface of the structure, the clay compound and the fluorescent compound are dispersed in a polymer compound to improve workability. I am trying.

The inventors of the present invention have succeeded for the first time in creating a system in which a clay mineral adsorbed with a fluorescent compound, a water-soluble compound and water are uniformly mixed. In other words, the inventors of the present invention have succeeded for the first time in producing or producing a pressure-sensitive material that responds to pressure using a clay mineral, a polymer compound, and a fluorescent compound. Moreover, by concentrating such a system, it succeeded in making it a gel-like substance. This gel material could be uniformly applied to the surface of the object.

The pressure-sensitive paint of the present invention may contain an alkali metal ion originally contained in the clay mineral, a counter anion of the fluorescent compound, a counter anion possessed by the polymer compound, etc. as subcomponents contained in the main component. . The counter anion of the fluorescent compound is not limited to this component, but examples thereof include iodine ions. Although the counter anion which a high molecular compound has is not limited to this, a sodium ion etc. can be illustrated. In the case of a polymer compound type material, the pressure sensitive paint can respond to pressing force, and its heat return is smaller than that of a conventional polymer type material.

FIG. 3 is a conceptual diagram illustrating the mechanism by which the pressure sensing material of the present invention emits fluorescence. FIG. 3 shows a plate-like clay mineral, a fluorescent compound in which two thin hexagonal columns are connected, and a long-line polymer compound. Clay minerals are minute clay particles of the order of nm, and these clay particles are thought to have a flat plate-like structure, clogging adjacent to each other without any gaps. The pressure sensing material of the present invention is composed of a plurality of plate-like layers made of plate-like clay minerals. FIG. 3 shows only two examples.

In the state immediately after the pressure sensitive paint is produced, the polymer compound and the fluorescent compound are uniformly dispersed between the clay mineral layers. The layers of clay mineral are parallel to each other. The two hexagonal column parts of the molecular structure of the fluorescent compound are coplanar and parallel to the clay mineral layer. The length of the polymer compound is usually very long, such as several hundred nm to several mm, and is much longer than the particle size of the clay mineral, so it is considered to exist between the layers of the plurality of clay minerals. When pressure (stress) is applied to such a structure from the outside, the polymer compound is deflected by mechanical stress.

The deflection of the polymer compound works to increase the thickness of the clay mineral layer or to change the parallel plane between layers. When the state of the clay mineral layer changes in this way, the molecular structure between them, in particular, the two hexagonal columnar parts disappear from the plane, so that the hexagonal column part exhibits fluorescence different from the coplanar state. Become. Like the fluorescent compound of Example 1 of the present invention, the compound having a biphenyl moiety changes the dihedral angle of the biphenyl moiety by changing the size of the gap between the clay layers, and the size of the π electron system. Changes the fluorescent color.

As the fluorescent compound, any fluorescent compound can be used as long as it is an organic compound having a biphenyl moiety. The following formula 1 is an example of an organic molecule having a biphenylene structure. As can be seen from Formula 1, the fluorescent compound has a structure in which a plurality of phenyl groups are adjacent to each other, and the adjacent phenyl groups can rotate. As long as the fluorescent compound has a biphenyl moiety, the fluorescent compound can be used in a rod shape or a plate shape. With such a rod-like or plate-like shape, the biphenyl moiety of the fluorescent compound is arranged in a plane.

Due to external mechanical stress, this biphenyl moiety rotates and is no longer flat. This is considered to cause a change in the fluorescent color. As a biphenyl compound used by this invention, it is a biphenyl compound of the following (Formula 1) and the following (Formula 2).

(Action, effect)
The pressure sensitive material of the present invention has the following advantages over the conventional material. The pressure sensing material of the present invention can be used simply by applying it to a structure or the like that is an object to be measured. Therefore, it is not necessary to have special expertise and advanced skills when preparing the paint having the pressure sensing material of the present invention, and it is easier to use than the conventional pressure sensing paint. Became high. Furthermore, even if the pressure change is temporarily applied to the pressure sensitive paint having the pressure sensitive material of the present invention, the fluorescent color change is maintained for a long time of several days to several weeks even if the pressure (stress) is released and cannot be applied. Is done.

In the pressure sensing material of the present invention, the cross-sectional area of the layered clay compound is very small, for example, about 100 molecules of the fluorescent compound, so that the structure and composition of the polymer compound and the fluorescent compound are maintained in the coating medium. Can be distributed. In the case of a polymer compound type material, the pressure-sensitive paint can respond to pressing force. The heat return is smaller than that of the conventional compound type material. As described above, even if the force acting on the place where the load is applied due to stress such as tension, compression, bending, and shear, and scratches is eliminated, the applied force can be stored in the pressure sensitive paint. There is a remarkable effect that the place where the stress is applied can be confirmed later.

The pressure sensing material of the present invention is characterized in that a change in dihedral angle of biphenyl is used for stress sensing in the mechanism of pressure sensitivity. The pressure-sensitive paint of the present invention contains a clay mineral, a polymer compound, and biphenyl molecules, which are thinly applied to the surface of the structure and dried. Thus, a thin film is obtained on the surface of the structure. This thin film produces fluorescence derived from biphenyl molecules.

The characteristic of this thin film compared to a thin film that is only doped with normal fluorescent molecules is that the fluorescent color changes only at the part where pressure and scratches are present. Although not illustrated by the figure, it was confirmed that a fluorescent color change occurs when the thin film coated with the pressure sensitive paint of the present invention is folded. For this reason, the pressure-sensitive paint of the present invention can be used as a sensor paint for pressure and scratches that can be visually observed due to the difference in fluorescent color emitted from the part that is under load when applied to a structure such as a machine. Is possible.

〔size〕
As the fluorescent compound, an elongated rod-shaped one is used. The size of the fluorescent compound is preferably shorter than the size of the clay mineral. For example, when the size of the clay mineral particles is about 40 nm, the size of the fluorescent compound is practically preferably 10 nm or less. If the size of the fluorescent compound is too small, it does not generate fluorescence with visible light, and therefore, it is practically preferable that the size is 0.5 nm or more in the major axis direction.

Fluorescent compounds are susceptible to mechanical damage due to twisting and the like when the size is too large. A fluorescent compound that has been mechanically damaged may cease to emit fluorescence. In addition, the fluorescent color cannot be returned to the original state by heating, which is one of the characteristics of the present invention. Therefore, the size of the fluorescent compound is preferably 5 nm or less in the major axis direction. The particles of the clay compound are fine plate-like particles having a size of 20 to 100 nm in the major axis direction and a thickness of 0.5 to 10 nm. The layered clay compound is a laminate of many clay compound particles, and its cross-sectional area is much larger than that of the fluorescent compound particles, for example, 500 to 5000.

[Use]
Quality control of precision equipment transportation, investigation of vulnerable parts of airplane wings and car engines, prevention of accidental fall of concrete structures, prevention of aging bridge girders, prevention of breakage of wind power generators, power generation It is considered to be used for maintenance of the turbine in the office, use for sports practice tools, correction of walking, diagnosis of tooth meshing, children's toy graffiti board, taking a foot shape without being noticed by the criminal It is done. As a tool for sports, for example, it can be used for investigating contact points between a hit ball such as baseball and golf and a bat or club. In this way, as a sporting tool, it can be used when investigating both the side receiving the hit and the side giving the hit. Furthermore, it can be used for a wide range of applications such as transport management of play equipment and precision equipment.

[Preparation of pressure-sensitive paint of the present invention]
Next, Example 1 for producing the pressure sensitive paint of the present invention will be described. In Example 1, a fluorescent organic molecule biphenyl derivative BP was used as the fluorescent compound. Sodium polyacrylate (hereinafter referred to as SPA) was used as the polymer compound. As the clay compound, Sumecton ST (hereinafter referred to as SST), which is a synthetic inorganic material manufactured by Kunimine Industry Co., Ltd. (head office: Chiyoda-ku, Tokyo, Japan), was used.

A method for producing a polymer hybrid membrane is described in detail in Japanese Patent No. 3855004. First, the fluorescent compound was dissolved in a solvent miscible with water at a concentration of 2 × 10 ⁻⁵ M (2 × 10 ⁻⁵ mol / dm ³ ) to obtain 7 ml of an aqueous solution of the fluorescent compound. Next, the clay compound was dispersed in water at a concentration of 10 g / l or less to obtain 5 ml of a clay water dispersion. An aqueous solution of a fluorescent compound was added to the clay aqueous dispersion to obtain a clay dispersion in which the fluorescent compound was adsorbed on the surface. The doping amount of biphenyl derivative BP to SST, in other words, the weight ratio of biphenyl derivative BP to SST was set to 0.1%.

The dispersion was heated to 80 ° C. To this heated dispersion, 11 ml of a 2 g / l water-soluble polymer compound heated to 80 ° C. was added. SST and SPA were 7: 3 by weight. The clay compound was 50 mg and the polymer compound was 22 mg. In this way, a mixture of all the solutions was dried at 80 ° C. for 30 minutes in a reduced pressure of about 200 torr (about 0.0267 MPa) to obtain a clay gel. The gel was applied to the surface of the substrate, and dried for 24 hours in an environment of 70 ° C. under normal pressure, whereby a surface coating of a pressure sensing material composed of a fluorescent compound, a clay compound, and a polymer compound was completed.

As the substrate, a polypropylene film was used in this example. This surface coating was transparent to some extent with respect to visible light. Although the above-mentioned drying was performed under an environment of normal pressure of 70 ° C., it can be performed at normal temperature and normal pressure. The reduced pressure of about 200 torr (about 0.0267 MPa) and the temperature of 80 ° C. are for drying the surface coating quickly. In the present example, the fluorescent compound used was an elongated rod. The size of the fluorescent compound was 0.4 nm in the minor axis direction and about 2 nm in the major axis direction. The size of the clay mineral used was about 1 nm in thickness and about 40 nm in length from end to end of the flat plate.

[Response of fluorescence behavior to pressure and scratches]
The substrate coated with the pressure sensitive paint of the present invention has a fluorescent color change in the bent part, the part gripped by tweezers, the part cut by the cutter, and the part where pressure (pressing force) is applied by the tip of the ballpoint pen. It has been confirmed that the occurrence is so visible. For example, FIG. 4 is a photograph showing a state in which a portion where the substrate is held with tweezers emits fluorescence. FIG. 5A is a photograph showing a state in which a character is drawn by making a cut on the substrate with a cutter.

Fig. 5 (b) is an enlarged photograph of a part of Fig. 5 (a). In addition, the structural change of the substrate was such that the fluorescence did not return to the original state even after a period of one and a half months (45 days), and the fluorescence was generated to the extent that it can be visually observed. It was confirmed that such a change in the fluorescent color returned to the original state when the changed portion was heated. In this experiment, in the experiment, when the hot air of 80 ° C. was sent to the substrate coated with the pressure sensitive paint by the dryer and heated, the fluorescent color could be restored to the original state.

FIG. 6 is a graph showing how the pressure sensitive paint of the present invention that emits fluorescence is heated and returned to its original state. The vertical axis of the graph in FIG. 6 indicates the fluorescence intensity as a relative value, and the horizontal axis indicates the wavelength of the fluorescence. In FIG. 6, the graph showing the fluorescence spectrum when the pressure sensitive paint of the present invention is applied is a circle (◯), the fluorescence spectrum when stress is applied is a square (□), and when cooled after heating. Is indicated by a triangle (Δ).

The substrate that is fluorescent by applying the pressure sensitive paint of the present invention and applying stress was peeled and heated in an oven set at 100 ° C. for 1 day after peeling. As can be seen from FIG. 6, it can be seen that the shoulder of the fluorescence spectrum decreases during heating and when allowed to cool. In the fluorescence spectrum, the graph when the pressure-sensitive paint of the present invention is applied and the graph when allowed to cool after heating substantially overlap, and it is demonstrated that the fluorescence color is restored to the original by heating.

[Comparative example]
FIG. 7 shows the measurement results when a rigid molecule is used as the fluorescent compound. As can be seen from this figure, when a molecule with a rigid skeleton is used, mechanochronism in which the fluorescence color changes due to refraction or tension does not occur. The production process is exactly the same as that of the biphenyl molecule described in Example 1 above. Next, detailed conditions of this manufacturing process will be described. First, the fluorescent compound was dissolved in a solvent mixed with water at a concentration of 2 × 10 ⁻⁵ M to obtain 7 ml of a fluorescent compound solution. Next, clay was dispersed in water at a concentration of 10 g / l or less to obtain 5 ml of a clay water dispersion.

A solution of the fluorescent compound was added to the clay aqueous dispersion to obtain a clay dispersion in which the fluorescent compound was adsorbed on the surface. The fluorescent compound was a fluorene compound of the following formula 3, which is a rigid skeleton molecule. This dispersion was heated to 80 ° C., and 11 ml of a 2 g / l water-soluble polymer compound heated to 80 ° C. was added to the dispersion. A mixture of all the solutions was dried in a reduced pressure of about 200 torr (about 0.0267 MPa) at 80 ° C. for 30 minutes to obtain a clay gel. This gel was applied to the surface of an object and dried in an environment of 70 ° C. and normal pressure for 24 hours. Then, when mechanical stress was applied to the surface of this object in the same manner as in Example 1, the fluorescence color did not change. The following formula 3 is a chemical formula showing a molecular structure as a comparative example. When this Formula 3 is compared with Formula 1 and Formula 2, there is no phenyl group which can rotate.

FIG. 7 is a graph showing the fluorescence spectrum of the comparative example. The vertical axis of the graph in FIG. 7 indicates the fluorescence intensity as a relative value, and the horizontal axis indicates the wavelength of the fluorescence. In FIG. 7, the graph showing the fluorescence spectrum when the gel of the comparative example is applied is a circle (◯), and the fluorescence spectrum when stress is applied to the circle is shown by a square (□). These two graphs are almost overlapped, and it can be seen that there is almost no change in the fluorescent color.

The present invention may be used in the field of measuring pressure (stress) on the surface of a structure. For example, it may be used for destructive inspection, durability inspection, and the like of structures such as building structures, aircraft bodies, automobile bodies, and civil engineering machinery bodies. Moreover, it is good to use for the sport equipment which receives a hit | damage or gives a hit like a golf head, a baseball bat, etc.

Claims

A layered compound consisting of a fine particle layer of a compound derived from a clay mineral;
One or more fluorescent compounds sandwiched between a plurality of the layers;
A pressure sensing material filled between the layers and comprising a binder having a molecular size larger than that of the fine particles,
The pressure-sensitive material, wherein the fluorescent compound emits fluorescence when the layer is deformed by a mechanical force applied from outside.
The pressure sensitive material of claim 1, wherein
The pressure-sensitive material, wherein the fluorescent compound is an organic fluorescent compound having a biphenylene structure.
The pressure sensitive material according to claim 1 or 2,
The pressure sensing material, wherein the fluorescent compound has a particle size smaller than that of the fine particle.
The pressure sensitive material according to claim 1 or 2,
The pressure sensitive material is
A pressure-sensitive material comprising one or more compounds selected from a colorant, a filler, a temperature-sensitive agent, a temperature-sensitive dye, and a plasticizer.
A pressure-sensitive paint containing the pressure-sensitive material according to claim 1 selected from claims 1 to 4.
One or more fluorescent compounds;
A layered compound consisting of a fine particle layer of a compound derived from a clay mineral;
A method for producing a pressure sensing material comprising a binder filled between the layers and having a molecular size larger than that of the fine particles,
Obtaining a solution of the fluorescent compound;
A step of dispersing the fine particles in water to obtain a clay water dispersion;
Mixing the solution of the fluorescent compound obtained in the step, the clay aqueous dispersion, and the binder to obtain a mixed solution; and
And a step of concentrating the liquid mixture to obtain the pressure sensing material.
In the manufacturing method of the pressure sensing material according to claim 6,
The method for producing a pressure sensing material, wherein the binder is a polymer compound.
In the manufacturing method of the pressure sensing material according to claim 6 or 7,
The method for producing a pressure sensing material, wherein the fluorescent compound is an organic molecule having a biphenylene structure.
A method for producing a pressure sensitive material according to claim 1 selected from among claims 6 to 8.
The fluorescent compound has a rod-like shape with a size of 0.5 to 5 nm,
The method for producing a pressure-sensitive material, wherein the fine particles of the layered compound have a size of 20 to 100 nm.
In the manufacturing method of the pressure sensing material according to claim 9,
The method for producing a pressure sensing material, wherein the pressure sensing material is a gel-like material and applied to the surface of a structure.
In the manufacturing method of the pressure sensing material according to claim 6 or 7,
A method for producing a pressure-sensitive material, comprising the step of heating before mixing the solution of the fluorescent compound, the clay aqueous dispersion, and the binder.