JPWO2018164080A1 - Pressure measuring material, pressure measuring material set, pressure measuring method, and pressure measuring liquid set - Google Patents

Abstract

A support, a color former layer containing an electron donating dye precursor, and a developer layer arranged between the support and the color former layer and containing an electron-accepting compound, and having a tip diameter This is a pressure measuring material and its application, in which the color developing portion has a diameter of more than 5 mm but not more than 10 mm when color is developed by pressing at a pressure of 50 MPa with a 5 mm terminal.

Description

  The present disclosure relates to a pressure measurement material, a pressure measurement material set, a pressure measurement method, and a pressure measurement liquid set.

  The material used for pressure measurement is expected to be applied to various applications such as liquid crystal glass laminating process, solder printing on printed circuit boards, pressure adjustment between rollers, and surface pressure adjustment during substrate pasting work. ing. As an example of the material used for the pressure measurement, there is a pressure measurement film represented by, for example, a prescale (trade name; registered trademark) provided by FUJIFILM Corporation.

In the pressure measurement film on the market, for example, the pressure is measured by the following method.
That is, in situations such as adjusting the pressure between rollers, the pressure measurement film is sandwiched between the pressure-applied parts between the rollers, pressure is applied, the pressure measurement film is taken out from the pressure-applied parts, and the pressure is determined based on the degree of color development of the taken-out pressure measurement film. Can be judged visually.

In recent years, for example, as a use application of a pressure measurement film, in addition to the above-mentioned use, there is a tendency to increase the use of adjusting or confirming tightening of a fixing member such as a screw. The fixing member such as a screw plays a role of tightening as a whole. In addition, for example, a bolt that is a member for fastening is generally made of metal, and a portion to be pressed by the bolt is often hidden by the bolt itself and cannot be visually recognized.
Thus, there is a need for a means for grasping the pressure or pressure distribution of the pressurized part when the tightening member itself is in the way and the pressurized part cannot be observed.

As a technique related to the above-described circumstances, for example, in Japanese Patent Application Laid-Open No. 2009-19949, a color density difference ΔD before and after pressurization at 0.05 MPa is 0. A pressure measurement material of 02 or higher has been proposed.
Further, for example, Japanese Patent Application Laid-Open No. 2009-19949 discloses a tightening display body in which a display unit in which particles encapsulated with a color former are sealed between two plain washers is mixed. In addition, it is described that the display portion forms a protruding portion that is visible from the outside so that the tightening of the screw can be visually confirmed.

  As described above, for example, when the pressure measurement film is applied for confirmation of tightening in a fixing member such as a screw, it is necessary to loosen the screw in order to confirm the color development degree of the pressure measurement film after tightening. In this method, not only duplication work occurs in terms of tightening, but also the degree of tightening of the tightened screw or the like cannot be directly confirmed.

In addition, for example, pressure measurement films that have been provided so far have the ability to sharpen color images due to the necessity of precisely grasping the pressure distribution in accordance with the high functionality and high definition of products. There are many. In addition, for example, pressure measurement films that have been provided in the past often have properties such that bleeding at the color development portion hardly occurs so that the pressure distribution can be grasped even in a minute pressure region. For this reason, for example, when a metal member such as a screw is fastened and fixed, the pressure measurement film disposed in the pressed part is hidden by the screw or the like, and the pressure of the pressed part is visually observed through the screw or the like. It is difficult to grasp.
As described above, Japanese Patent Application Laid-Open No. 2009-19949 describes that the tightening of the screw can be visually confirmed by the display portion of the tightening display body, but there is no detail about the display portion, and simply a pressure-sensitive film. It is only described that it may be used. As described above, the color former layer of the conventional pressure measurement film is usually designed so that the color does not bleed. As disclosed in JP 2009-19949 A, for example, the size is simply larger than the bolt. Even if the display portion is provided, color development cannot be expected in the region outside the bolt to which no pressure is directly applied. Therefore, in the tightening display body described in Japanese Patent Application Laid-Open No. 2009-19949, it is impossible to obtain a color density or a hue according to the degree of pressure, and it is also impossible to display a pressure distribution.

  In addition, for example, there is a demand for a pressure measurement film to store a history of tightening pressure when it is tightened with a fixing member such as a screw for a certain period.

The present disclosure has been made in view of the above circumstances.
The problem to be solved by the embodiments of the present invention is that a pressure measurement material, a pressure measurement material set, a pressure measurement method, and a pressure measurement material in which a pressure or a pressure distribution in a usage mode in which a pressed part cannot be visually recognized can be visually recognized, and It is to provide a liquid set for pressure measurement.

Specific means for solving the above problems include the following aspects.
<1> A developer comprising a support, a color former layer containing an electron donating dye precursor, and an electron accepting compound which is disposed between the support and the color former layer and causes the electron donating dye precursor to develop a color. An agent layer,
This is a pressure measuring material in which the diameter of the color developing portion when the color is developed by pressurizing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm is more than 5 mm and not more than 10 mm.
<2> developer layer void volume is a pressure measuring material according to a ^{1ml / m 2 ~10ml / m 2} <1>.
<3> The color former layer includes a microcapsule encapsulating an electron-donating dye precursor, and the content of the microcapsule is 40% by mass or more based on the total solid content of the color former layer and the developer layer. <1> or <2>, the material for pressure measurement.
<4> The developer layer has an electron-accepting compound content of 10% by mass to 50% by mass with respect to the total solid content of the color former layer and the developer layer. 3> The material for pressure measurement according to any one of 3>.
<5> The material for pressure measurement according to any one of <1> to <4>, wherein an average primary particle diameter of the electron-accepting compound is 10 μm or less.

<6> The developer layer is the pressure measurement material according to any one of <1> to <5>, further including a water-soluble polymer compound.
<7> The material for pressure measurement according to <6>, wherein the content of the water-soluble polymer compound is 20% by mass or more based on the total solid content of the developer layer.
<8> The color former layer is the pressure measurement material according to any one of <1> to <7>, further including an oil component having a contact angle with respect to the surface of the developer layer of 30 ° or less. .
<9> a color developing material having a color former layer containing an electron donating dye precursor, and a color developing material having a color developer layer containing an electron accepting compound that causes the electron donating dye precursor to develop color,
This is a pressure measurement material set in which the diameter of the color developing part is greater than 5 mm and equal to or less than 10 mm when color is developed by pressing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm.
<10> the developer layer, the void volume is a pressure measuring material set according to a ^{1ml / m 2 ~10ml / m 2} <9>.
<11> The color former layer includes a microcapsule encapsulating an electron-donating dye precursor, and the content of the microcapsule is 50% by mass or more based on the total solid content of the color former layer and the developer layer. <9> or <10> is the pressure measurement material set.

<12> A step of applying a developer layer liquid containing an electron-accepting compound to one of the pressure-sensitive portions of each of the two materials to form the developer layer, and a step above or on the developer layer. A step of forming a color former layer by applying a liquid for a color former layer containing an electron-donating dye precursor to the other of the pressure sites, and a developer layer and a color former layer formed at the pressure site And applying a pressure to develop a color,
The ratio of the applied amount of the color former layer liquid to the total applied amount of the color former layer liquid and the developer layer liquid in the pressurized portion is more than 0.5 and 0.8 or less on a mass basis. ,
The color developer layer and the color developer layer to be developed are pressure measuring methods in which the diameter of the color-development portion exceeds 5 mm and is 10 mm or less when color is developed by pressing at a pressure of 50 MPa with a terminal having a diameter of 5 mm at the tip. is there.
<13> The material for pressure measurement according to any one of <1> to <8> or the material set for pressure measurement according to any one of <9> to <11> is arranged at a pressed part. The pressure measuring method includes a step of applying a pressure to the developer layer and the color former layer to cause color development.
<14> The pressure measurement method according to <12> or <13>, in which the material of the pressed part is metal or resin.
<15> A liquid for a color former layer containing an electron donating dye precursor and a liquid for a developer layer containing an electron accepting compound that causes the electron donating dye precursor to develop color, and are used for pressure measurement. A pressure measurement liquid set in which the ratio of the amount of the color former layer liquid to the total amount of the color former layer liquid and the developer layer liquid is greater than 0.5 and less than or equal to 0.8 on a mass basis. .

  According to the embodiments of the present invention, a pressure measurement material, a pressure measurement material set, a pressure measurement method, and a pressure measurement liquid in which a pressure or a pressure distribution in a usage mode in which a pressed part cannot be visually recognized can be visually captured. A set is provided.

  Hereinafter, the pressure measurement material, the pressure measurement material set, the pressure measurement method, and the pressure measurement liquid set according to the present disclosure will be described in detail.

  In addition, the notation of "-" described in this specification shows the range which includes the numerical value described before and behind "-" as a minimum value and a maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in a numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.

  The term “process” in the present specification is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. .

  Further, in this specification, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, they exist in the composition unless otherwise specified. It means the total amount of multiple substances.

  In the present specification, an electron donating dye precursor is also referred to as a “color former”, and an electron accepting compound that develops an electron donating dye precursor is also referred to as a “developer”.

<Material for pressure measurement>
The material for pressure measurement according to the present disclosure includes a developer layer containing an electron accepting compound that develops an electron donating dye precursor in order from the support side, and a color former containing an electron donating dye precursor. And a layer. In the pressure measurement material of the present disclosure, the diameter of the color developing portion when the color is developed by pressurizing with a terminal having a diameter of 5 mm at a pressure of 50 MPa is in the range of more than 5 mm and not more than 10 mm.

  The material for pressure measurement of the present disclosure includes an electron-donating dye precursor (color former) and preferably a microcapsule encapsulating a solvent, and an electron-accepting compound (developer) that reacts with the electron-donating dye precursor to cause color development. ) And a so-called mono-sheet type material provided on a single support.

  In the mono sheet type, pressure is measured by sandwiching a pressure measuring material between pressure-sensitive parts where pressure or pressure distribution is desired to be measured.

Materials used for pressure measurement have been proposed and widely used in the past, but they are used for pressure measurement at pressured sites such as pressure distribution during glass bonding or pressure distribution between roll pairs. In many cases, the material is taken out after applying the pressure by placing or passing the material, and the color development state of the taken out material is measured. However, in the case of a fixing member such as a screw or the like, the material cannot be taken out after the pressure is applied unless the work for loosening is once provided after being tightened at a predetermined position, and therefore the color development state cannot be measured.
When checking the tightening of a fixing member such as a screw, loosening the screw to check the degree of pressure after tightening the screw does not only cause the tightening operation to occur again, but the tightened screw etc. It is not possible to confirm directly that it is tightened.

  In the above Japanese Patent Application Laid-Open No. 2009-19949, although tightening can be visually confirmed by protruding the display portion, there is no disclosure regarding specific means for the display portion. As described above, in view of higher functionality and higher definition of a product, a color former layer in a conventional pressure measurement film, for example, is generally designed so that the color does not bleed. In the invention described in the publication, it is difficult to accurately grasp the degree of pressure or the pressure distribution in a region that is hidden by a screw or the like and cannot be visually recognized.

The present disclosure has been made in view of the above, and even in a case where a pressed part made of a metal member such as a screw and tightened by a screw or the like cannot be hidden and visually recognized by the screw or the like itself. It is possible to visually grasp the pressure or pressure distribution during tightening.
Specifically, color development occurs when color is developed by applying pressure to a pressure measurement material (specifically, a color former layer and a developer layer) at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm. Color is developed with the diameter of the part exceeding 5 mm and not exceeding 10 mm. In other words, when color is developed by pressurization, the color developed at the pressurized part oozes out to the surroundings, and the colored part becomes larger than the area of the pressurized part, so that the area away from the pressurized part (for example, the tightening area with bolts) The color density or hue corresponding to the pressure can be captured at the outer peripheral portion of the image. It is also possible to grasp the pressure distribution from the change in the color density or the change in the hue of the color development portion.

  In the pressure measurement material of the present disclosure, pressurization can be performed by applying pressure (point pressure, linear pressure, surface pressure, or the like) with a point, a line, or a surface by any method. The pressure measurement material of the present disclosure is particularly suitable for measuring the degree of pressure or the pressure distribution in a usage mode in which a pressed part cannot be visually recognized due to tightening or the like.

  When the pressure measuring material is pressurized, coloring occurs when the electron-donating dye precursor in the color former layer reacts with the electron-accepting compound in the developer layer. For example, in a color former layer containing a microcapsule encapsulating an electron donating dye precursor, the microcapsule is broken to release an inclusion containing the electron donating dye precursor, and an electron donating property corresponding to the pressure applied. The inclusion containing the dye precursor is released in an amount corresponding to the pressure, so that the reaction amount with the electron accepting compound is adjusted, and a colored or colored gradation is obtained.

In the pressure measurement material of the present disclosure, the diameter of the coloring portion when the color is developed by pressurizing with a terminal having a tip diameter of 5 mm at a pressure of 50 MPa is set to more than 5 mm and not more than 10 mm. This indicates that, when color is developed by being pressed with a terminal having a diameter of 5 mm, the color development at the pressed portion oozes out to the surroundings, and the colored portion is enlarged within an appropriate range with respect to the area of the pressed portion.
Here, the “diameter” of the coloring portion is defined as a concentric circular shape in which the coloring portion radiates and becomes larger with respect to the circular shape having a diameter of 5 mm when the tip shape of the terminal is a circular shape having a diameter of 5 mm. It is assumed that Therefore, the fact that the diameter of the coloring portion when the color is developed by pressurizing with a pressure of 50 MPa by a terminal having a tip diameter of 5 mm is more than 5 mm and not more than 10 mm is that the size (namely, area) of the coloring portion is It means that the size (that is, the area) of the portion to be pressed is more than equal to 4 times and less than 4 times. That is, when the shape of the pressed part is not circular, the coloring portion is formed in the range of more than equal to four times and less than the size (ie, area) of the pressed part.
If the diameter of the color development part exceeds 5 mm, a color development part with a larger area than the pressure-sensitive part can be obtained compared to conventional materials that cannot be expected to expand the area of the color development part. Is suitable for measuring the degree of pressure or the pressure distribution when the pressure cannot be visually recognized. In particular, it is possible to capture a change in color density or hue according to the pressure in a region (for example, the outer peripheral portion of a tightening region by a bolt) that is out of the pressed portion.
In addition, since the diameter of the color developing portion is 10 mm or less, there is little possibility that the measurement object is contaminated by excessively dripping the dye and dripping.
The diameter of the coloring portion when the color is developed by pressurization with the above pressure is preferably 6 mm to 10 mm. Further, the diameter of the coloring portion is more preferably 7.5 mm to 10 mm from the viewpoint of the visibility of the coloring portion, and 7.5 mm to 9 mm from the viewpoint of high visibility of the coloring portion and not impairing the appearance. 0.0 mm is more preferable.

  The diameter of the color-developing part was 50 MPa by using a prescaled pressurizer (FPHL, manufactured by Fuji Film Co., Ltd.) and applying a terminal having a circular tip and a tip diameter of 5 mm to the material for pressure measurement. This is a value obtained by measuring the diameter of the color-developing portion that is colored by pressurizing with a scaler.

  When the color is developed by pressurizing at the above pressure, the diameter of the color developing part is adjusted by adjusting the porosity of the developer layer, the content or particle diameter of the developer in the developer layer, and the microcapsules in the color developer layer. Alternatively, it can be carried out depending on the content of the oil component, the presence or content of the water-soluble polymer compound in the developer layer, the contact angle of the oil component in the color former layer on the surface of the developer layer, and the like.

Next, the color former layer, the developer layer and the support of the pressure measurement material of the present disclosure will be described in detail.
-Color former layer-
The pressure measurement material of the present disclosure has a color former layer on a developer layer formed on a support.
The color former layer contains at least an electron donating dye precursor, and may further contain other components as required.

The electron donating dye precursor contained in the color former layer is preferably contained in the form of a microcapsule enclosing the electron donating dye precursor.
By encapsulating the electron-donating dye precursor in the microcapsule, the amount of the electron-donating dye precursor released from the microcapsule is adjusted in response to the pressure, and the amount of reaction with the electron-accepting compound is changed. As a result, a change in the color density or color distribution of the color development portion can be favorably expressed.

  The microcapsule encapsulates an electron donating dye precursor as a color forming component, preferably encapsulates a solvent, and may further encapsulate an auxiliary solvent, an additive, and the like as necessary.

  The number average wall thickness δ of the microcapsules depends on various conditions such as the type of capsule wall material and the capsule diameter, but from the viewpoint that it can be broken at a minute pressure (for example, a pressure lower than 0.05 MPa), 05 μm to 1.0 μm are preferable, and 0.10 μm to 0.80 μm are more preferable.

  The wall thickness of the microcapsule refers to the thickness (μm) of the resin film (so-called capsule wall) that forms the capsule particles of the microcapsule, and the number average wall thickness refers to the thickness of the individual capsule wall of the five microcapsules. An average value obtained by obtaining (μm) with a scanning electron microscope (SEM) and averaging it. Specifically, the microcapsule solution is first applied on an arbitrary support and dried to form a coating film. A cross section of the obtained coating film is prepared, and the cross section is observed using an SEM. After selecting any five microcapsules, the cross section of each selected microcapsule is observed to determine the thickness of the capsule wall. To calculate an average value.

The average primary particle size of the microcapsules is preferably 1.0 μm to 50.0 μm, more preferably 5.0 μm to 30.0 μm.
The average primary particle diameter of the microcapsule is a value measured by a laser diffraction scattering method with respect to the color former layer liquid for forming the color former layer. For example, a particle size distribution measuring device (Microtrac HRA, Nikkiso Co., Ltd.) ).

Color former layer, the content of the microcapsules in the color former layer after drying a liquid for color former layer was applied (e.g., coated) as the range of ^{3.0g / m 2 ~100.0g / m 2} , dried Can be formed.
The content of the color former layer of the ^{microcapsules,} preferably from ^{5.0g / m 2 ~50.0g / m 2} , 10.0g / m 2 ~40.0g / m 2 is more preferable.
Further, when the color former layer liquid for forming the color former layer is applied to form the color former layer, the application can be performed by a known application method and can be used for the liquid for the developer layer described later. This is the same as the coating method.

The content of the microcapsules (the coating amount in the case of coating) is preferably 40% by mass or more based on the total solid mass of the total of the color former layer and the developer layer. The content of the microcapsule of 40% by mass or more indicates that the amount of oil in the color former layer is large when the microcapsule contains an oil component. By increasing the amount of oil, it is easy to cause bleeding in the color development portion when pressure is applied, and the color development area for color development is more easily expanded.
The content of the microcapsule is more preferably 40% by mass to 80% by mass, and still more preferably 50% by mass to 75% by mass with respect to the total solid mass of the total of the color former layer and the developer layer. When the content of the microcapsules is 80% by mass or less, it is advantageous in terms of coloring ability.

(Electron-donating dye precursor)
The color former layer preferably contains at least one kind of electron donating dye precursor, and preferably contains the electron donating dye precursor in a microcapsule.
As the electron-donating dye precursor, known ones can be used for pressure-sensitive copying paper or heat-sensitive recording paper. Examples of the electron-donating dye precursor include triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide compounds, leucooramine compounds, rhodamine lactam compounds, triphenylmethane compounds. Various compounds such as diphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds can be used.
For details of the above-mentioned compounds, reference can be made to the description in JP-A-5-257272.
You may use an electron-donating dye precursor individually by 1 type or in mixture of 2 or more types.

The electron donating dye precursor increases the color developability in a minute pressure range, and develops a high concentration at a minute pressure, that is, develops a concentration change (concentration gradient) corresponding to a wide pressure range. A high one is preferred. The molar absorption coefficient ε of the electron-donating dye precursor, 10000Mol is preferably ^-1 · ^{cm -1} · L or more, 15000mol ^-1 · ^{cm -1} · more preferably in more than L, more is 25000Mol ^-1 -It is preferable that it is more than cm ^<-1 > * L.

  Preferable examples of the electron donating dye precursor having a molar extinction coefficient ε within the above range include 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl ) -4-azaphthalide (ε = 61000), 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-n-octyl-2-methylindol-3-yl) phthalide (ε = 40000), 3 -[2,2-bis (1-ethyl-2-methylindol-3-yl) vinyl] -3- (4-diethylaminophenyl) -phthalide (ε = 40000), 9- [ethyl (3-methylbutyl) amino ] Spiro [12H-benzo [a] xanthene-12,1 ′ (3′H) isobenzofuran] -3′-one (ε = 34000), 2-anilino-6-dibutylamino-3 -Methylfluorane (ε = 22000), 3-butylamino-6-methyl-7-anilinofluorane (also referred to as ODB2; ε = 50000), 6-diethylamino-3-methyl-2- (2,6- Xylidino) -fluorane (ε = 19000), 2- (2-chloroanilino) -6-dibutylaminofluorane (ε = 21000), 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide ( CVL: also called crystal violet lactone; ε = 16000), 2-anilino-6-diethylamino-3-methylfluorane (ε = 16000), and the like.

When one kind of electron donating dye precursor having a molar extinction coefficient ε in the above range is used alone, or two or more kinds including an electron donating dye precursor having a molar extinction coefficient ε in the above range are mixed. When used, the proportion of the electron-donating dye precursor having a molar extinction coefficient ε of 10,000 mol ⁻¹ · cm ⁻¹ · L or more in the total amount of the electron-donating dye precursor has a color developability in a minute pressure range. From the viewpoint of increasing the concentration change (concentration gradient) over a wide pressure range, the range of 10% by mass to 100% by mass is preferable, the range of 20% by mass to 100% by mass is more preferable, and 30% by mass to 100% by mass. The range of is more preferable.
When two or more types of electron donating dye precursors are used, it is preferable to use two or more types having a molar extinction coefficient ε of 10,000 mol ⁻¹ · cm ⁻¹ · L or more.

The molar extinction coefficient ε can be calculated from the absorbance when an electron donating dye is dissolved in a 95% aqueous acetic acid solution. Specifically, in a 95% acetic acid aqueous solution of an electron donating dye whose concentration is adjusted so that the absorbance is 1.0 or less, the length of the measurement cell is Acm, and the concentration of the electron donating dye is B mol / L. When the absorbance is C, it can be calculated by the following formula.
Molar extinction coefficient ε = C / (A × B)

Content in the color former layer of the electron-donating dye precursor (e.g., coating weight), from the viewpoint of enhancing the color development of a minute pressure range, the mass after drying 0.1g ^/ m ² ~5g / m 2 preferably, more preferably ^{0.1g / m 2 ~4g / m 2} , 0.2g / m 2 ~3g / m 2 is more preferred.

(Oil component)
The color former layer preferably further contains an oil component having a contact angle of 30 ° or less with respect to the surface of the developer layer. The color former layer preferably contains an oil component enclosed in microcapsules.

When the contact angle of the oil component with respect to the surface of the developer layer is 30 ° or less, the oil component supplied from the color former layer tends to wet and spread on the surface of the developer layer. For this reason, it is easy to cause bleeding in the color developing portion when a pressure is applied, and it becomes easier to expand the color developing area.
The contact angle with respect to the surface of the developer layer is preferably as low as possible for the same reason as described above, and more preferably 25 ° or less. The lower limit of the contact angle is preferably 5 ° or more.

  The contact angle with respect to the surface of the developer layer was such that 1 μL of an oil component was dropped on the surface of the developer layer formed on the polyethylene terephthalate film, and a dynamic contact angle measurement device (FIBRO DAT 1100 was reached when 0.1 second had elapsed). , Manufactured by Fibro).

Examples of the oil component include a solvent.
As the solvent, those known for pressure-sensitive copying paper can be used. For example, alkylnaphthalene-based compounds such as diisopropylnaphthalene, 1-phenyl-1-xylylethane, 1-phenyl-1-ethylphenylethane, etc. Aromatic hydrocarbons such as diarylalkane compounds, alkylbiphenyl compounds such as isopropylbiphenyl and diisopropylbiphenyl, triarylmethane compounds, alkylbenzene compounds, benzylnaphthalene compounds, diarylalkylene compounds, arylindane compounds; phthalic acid Examples thereof include aliphatic hydrocarbons such as dibutyl and isoparaffin, soybean oil, corn oil, cottonseed oil, rapeseed oil, natural animal and vegetable oils such as olive oil, coconut oil, castor oil, and fish oil, and high-boiling fractions of natural products such as mineral oil.

The oil component may be contained in a mixture of two or more, in addition to being contained alone.
When the oil component is encapsulated in the microcapsule, the mass ratio of the oil component (preferably solvent) and the electron donating dye precursor (oil component: precursor) encapsulated in the microcapsule is from the viewpoint of color development. 98: 2 to 30:70 is preferable, 97: 3 to 40:60 is more preferable, and 95: 5 to 50:50 is more preferable.

(Co-solvent)
The color former layer may contain an auxiliary solvent encapsulated in microcapsules as necessary.
Examples of the auxiliary solvent include solvents having a boiling point of 50 ° C. or less, and examples include ketone compounds such as methyl ethyl ketone, ester compounds such as ethyl acetate, alcohol compounds such as isopropyl alcohol, and the like.

(Other ingredients)
In addition to the electron donating dye precursor, the oil component and the auxiliary solvent, the color former layer may further contain an additive as necessary. Additives include water-soluble polymer binders, hydrophobic polymer binders, surfactants, inorganic particles (eg silica particles), fluorescent brighteners, antifoaming agents, penetrants, UV absorbers, light Stabilizers, antioxidants, waxes, odor inhibitors, preservatives, and the like can be mentioned.
The additive may be encapsulated in a microcapsule encapsulating an electron donating dye precursor.

As the surfactant, for example, sodium alkylbenzene sulfonate that is an anionic surfactant (for example, Neogen T of Daiichi Kogyo Seiyaku Co., Ltd.) and polyoxyalkylene lauryl ether that is a nonionic surfactant (for example, And Neugen LP70 from Daiichi Kogyo Seiyaku Co., Ltd.).
Examples of the silica particles include gas phase method silica and colloidal silica. As a commercially available product on the market, for example, the Snowtex series (for example, Snowtex (registered trademark) 30) of Nissan Chemical Co., Ltd. can be used.

  There is no restriction | limiting in particular about the preparation methods of a microcapsule, A conventionally well-known method can be applied, For example, the method of Paragraph Nos. 0036-0044 of Unexamined-Japanese-Patent No. 2009-019949 can be referred.

There is no restriction | limiting in particular as thickness of a color former layer, According to the objective etc., it can select.
The thickness of the color former layer (when the microcapsule diameter is larger than the layer thickness, the thickness excluding the microcapsules exposed from the layer surface) is preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm.

-Developer layer-
The pressure measurement material of the present disclosure has a developer layer on a support (that is, between the support and the color former layer).
The developer layer contains at least an electron-accepting compound that is a developer, preferably contains a water-soluble polymer compound, and, if necessary, binders, pigments, and additives other than the water-soluble polymer compound And other components may be included.

Developer layer in the pressure measuring materials of the present disclosure, it is preferred void volume is ^{1ml / m 2 ~10ml / m 2} .
When the void amount of the developer layer is 1 ml / m ² or more, the color of the colored portion does not spread (bleeds) excessively with respect to the pressed part, and the color spreads (bleeds) into an appropriate range with respect to the pressed part. Can be expressed. In addition, when the amount of voids in the developer layer is 10 ml / m ² or less, the color spread (bleeding) of the color developing portion with respect to the pressed portion appears in an appropriate range.
The void volume of the developer ^layer, more preferably ^{2ml / m 2 ~8ml / m 2} , 3ml / m 2 ~6ml / m 2 is more preferable.

The void amount of the developer layer is a value determined by the following formula.
The PET film on which the developer layer is formed is cut into 10 cm × 10 cm, and the mass (m ₁ ) is measured. Subsequently, diethylene glycol is infiltrated into the developer layer on the PET film, and after the diethylene glycol remaining on the surface is wiped off, the mass (m ₂ ) is measured. When X = m ₂ −m ₁ , the void amount is obtained from the following formula. The density of diethylene glycol is 1.118.
Void volume (ml / m ² ) = 100 × X ÷ 1.118

(Electron-accepting compound)
The developer layer contains at least one electron-accepting compound.
Examples of the electron-accepting compound include inorganic compounds and organic compounds.
Specific examples of the inorganic compound include acidic clay, activated clay, attapulgite, zeolite, bentonite, clay material such as kaolin, and the like.
Specific examples of the organic compound include metal salts of aromatic carboxylic acids, phenol formaldehyde resins, metal salts of carboxylated temperphenol resins, and the like.
Among them, acid clay, activated clay, zeolite, kaolin, metal salt of aromatic carboxylic acid, metal salt of carboxylated temperphenol resin are preferable, and acid clay, activated clay, kaolin, metal salt of aromatic carboxylic acid More preferred.

  Preferable specific examples of the metal salt of aromatic carboxylic acid include 3,5-di-t-butylsalicylic acid, 3,5-di-t-octylsalicylic acid, 3,5-di-t-nonylsalicylic acid, 3,5 -Di-t-dodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 3-t-dodecylsalicylic acid, 5-t-dodecylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-bis (α, α-dimethylbenzyl) ) Salicylic acid, 3-methyl-5- (α-methylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) -5-methylsalicylic acid, 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid, 3 -(Α-methylbenzyl) -5- (α, α-dimethylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) -6-ethylsalicylic acid, 3-phenyl-5 Zinc salts, nickel salts, aluminum such as (α, α-dimethylbenzyl) salicylic acid, carboxy-modified terpene phenol resin, salicylic acid resin which is a reaction product of 3,5-bis (α-methylbenzyl) salicylic acid and benzyl chloride Examples thereof include salts and calcium salts.

In the developer layer, the content of the electron-accepting compound is preferably 10% by mass to 50% by mass with respect to the total solid content of the color former layer and the developer layer. When the content of the electron accepting compound is 10% by mass or more, the color developability of the electron donating dye precursor is improved, which is suitable for adjusting the color density or color distribution. Further, when the content of the electron-accepting compound is 50% by mass or less, the porosity is further reduced due to the electron-accepting compound, which is suitable for expanding the color development area.
As content of an electron-accepting compound, 10 mass%-40 mass% are more preferable from the reason similar to the above, and 15 mass%-35 mass% are still more preferable.

Content in the developer layer of the electron-accepting compound (weight case of applying the coating) is preferably ^2g / ^{m 2 ~30g} / m 2 by dry weight. More preferably ^{3g / m 2 ~20g / m 2} , more preferably from ^{5g / m 2 ~15g / m 2} .

The developer layer can be formed by preparing and forming a developer layer liquid for forming the developer layer. The developer layer may be formed, for example, by applying the developer layer liquid on the support by a method such as coating and drying.
The liquid for the developer layer may be a dispersion liquid in which an electron accepting compound is dispersed in water or the like.
When the electron accepting compound is an inorganic compound, the dispersion liquid in which the electron accepting compound is dispersed can be prepared by mechanically dispersing the inorganic compound in water. When the electron-accepting compound is an organic compound, the developer layer liquid can be prepared by mechanically dispersing the organic compound in water or dissolving it in an organic solvent.
For the details of the method for preparing the developer layer liquid, the method described in JP-A-8-207435 can be referred to.

  The dispersion liquid in which the electron accepting compound is dispersed may be used as a developer layer liquid (for example, a coating liquid) for forming a developer layer containing the electron accepting compound as it is.

The particle diameter of the electron-accepting compound is preferably 10 μm or less in terms of average primary particle diameter. When the average primary particle size of the electron-accepting compound is 10 μm or less, the amount of oil absorbed is small, which is advantageous in terms of bleeding.
As an average primary particle diameter of an electron-accepting compound, 9 micrometers or less are more preferable, and 7 micrometers or less are still more preferable.
Further, the lower limit of the average primary particle size of the electron-accepting compound is preferably 0.1 μm or more.
The average primary particle diameter of the electron-accepting compound is a value measured by a laser diffraction scattering method with respect to the developer layer liquid for forming the developer layer. For example, a particle size distribution measuring device (Microtrack HRA) , Manufactured by Nikkiso Co., Ltd.).

(Water-soluble polymer compound)
The developer layer preferably further contains a water-soluble polymer compound. When the developer layer contains the water-soluble polymer compound, the void amount of the developer layer can be further reduced.

As the water-soluble polymer compound, for example, a polyvinyl alcohol resin (polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified resin which is a resin having a hydroxy group as a hydrophilic site) Polyvinyl alcohol, polyvinyl acetal, etc.], cellulosic resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.] , Chitins, chitosans, starch, gelatin, resins having an ether bond [polyethylene oxide (P O), polypropylene oxide (PPO), polyethylene glycol (PEG), polyvinyl ether (PVE), etc.], resins having a carbamoyl group [polyacrylamide (PAAM), polyvinylpyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like. It is done.
Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.

Among these, as the water-soluble polymer compound, a polyvinyl alcohol resin is particularly preferable.
Examples of polyvinyl alcohol include Japanese Patent Publication No. 4-52786, Japanese Patent Publication No. 5-67432, Japanese Patent Publication No. 7-29479, Japanese Patent No. 2537827, Japanese Patent Publication No. 7-57553, Japanese Patent No. 2502998, Japanese Patent No. 3053231, JP 63-176173, JP 2604367, JP 7-276787, JP 9-207425, JP 11-58941, JP 2000-135858, JP 2001-205924, JP 2001-287444, JP-A-62-278080, JP-A-9-39373, JP-A-2750433, JP-A-2000-158801, JP-A-2001-213045, JP-A-2001-328345, JP-A-8- 324105, JP-A-11-348417, etc. And the like.
Examples of water-soluble resins other than polyvinyl alcohol resins include compounds described in paragraphs 0011 to 0014 of JP-A No. 11-165461.

The water-soluble polymer compound may be used alone or in combination of two or more.
The content of the water-soluble polymer compound is preferably 10% by mass or more, and more preferably 20% by mass or more, based on the total solid content of the color former layer and the developer layer. When the content of the water-soluble polymer compound is 10% by mass or more, it is effective in reducing the void amount of the developer layer, and the void amount can be easily adjusted to 10 ml / m ² or less.
The content of the water-soluble polymer compound is preferably 22% by mass to 40% by mass with respect to the total solid content of the color former layer and the developer layer.

(Other ingredients)
The developer layer may contain other components in addition to the electron-accepting compound.
Examples of other components include binders, pigments, and additives such as fluorescent brighteners, antifoaming agents, penetrants, and preservatives.

  Examples of the binder include styrene-butadiene copolymer latex, vinyl acetate latex, acrylic ester latex, polyacrylic acid, maleic anhydride-styrene copolymer, casein, and gum arabic.

  Examples of the pigment include heavy calcium carbonate, light calcium carbonate in various forms (rice grain, square, spindle, iga, spherical, aragonite column, amorphous, etc.), talc, rutile, or anatase And titanium dioxide.

Developer layer, the liquid for a color developer layer Grant (e.g. coating) the content of the electron-accepting compound in the developer layer after drying as a range of 0.1g ^/ m ² ~50g / m 2 It can be formed by drying.

  When the developer layer liquid for forming the developer layer is applied to form the developer layer, the application can be performed by a known application method, and the above-described case where the color former layer is formed. A similar coating method can be applied.

-Support-
The pressure measurement material of the present disclosure has a support.
The support may be any of a sheet shape, a film shape, a plate shape, and the like.
Specific examples of the support include paper, plastic film, and synthetic paper.

Specific examples of paper include high quality paper, medium quality paper, reprint paper, neutral paper, acid paper, recycled paper, coated paper, machine coated paper, art paper, cast coated paper, fine coated paper, tracing paper, Examples include recycled paper.
Specific examples of the plastic film include a polyester film such as a polyethylene terephthalate film, a cellulose derivative film such as cellulose triacetate, a polyolefin film such as polypropylene and polyethylene, and a polystyrene film.
Specific examples of synthetic paper include polypropylene or polyethylene terephthalate biaxially stretched to form a large number of microvoids (Yupo, etc.), polyethylene, polypropylene, polyethylene terephthalate, polyamide, etc. And the like laminated on a part of paper, one side or both sides.
Among these, from the viewpoint of further increasing the color density generated by pressurization, the support is preferably a plastic film or synthetic paper, and more preferably a plastic film.

<Pressure measurement material set>
The pressure measurement material set according to the present disclosure includes a color former having a color former layer containing an electron donating dye precursor, and a developer having a color developer layer containing an electron accepting compound that develops an electron donating dye precursor. Including materials,
The diameter of the color developing part when the color is developed by pressing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm is in the range of more than 5 mm and not more than 10 mm.
The pressure measurement material set of the present disclosure may include other materials as necessary in addition to the color forming material and the color developing material.

  The pressure-measuring material set of the present disclosure includes an electron-donating dye precursor (color former) and preferably a microcapsule encapsulating a solvent, and an electron-accepting compound that develops color by reacting with the electron-donating dye precursor (developed color). Agent) and a so-called two-sheet type material provided on separate substrates.

The color-developing material may have a support and a color-developing layer disposed on the support and containing an electron-donating dye precursor.
Moreover, the aspect which has a support and a color developer layer containing the electron-accepting compound which is arrange | positioned on a support and makes an electron-donating dye precursor color may be sufficient as a color developing material.

The electron donating dye precursor contained in the color former layer of the color forming material is preferably contained in the form of a microcapsule enclosing the electron donating dye precursor.
By encapsulating the electron-donating dye precursor in the microcapsule, the amount of the electron-donating dye precursor released from the microcapsule is adjusted in response to the pressure, and the amount of reaction with the electron-accepting compound is changed. As a result, a change in the color density or color distribution of the color development portion can be favorably expressed.

In the color forming material, the content of the microcapsule in the color former layer (in the case of application) is preferably 40% by mass or more based on the total solid content of the color developing material and the color developing material. The content of the microcapsule of 40% by mass or more indicates that the amount of oil in the color former layer is large when the microcapsule contains an oil component. When the amount of oil in the color former layer is increased, bleeding is likely to occur in the color development portion when pressure is applied, and the color development area for color development can be further increased.
The content of the microcapsules is more preferably 40% by mass to 80% by mass, and still more preferably 50% by mass to 75% by mass with respect to the total solid content mass of the color developing material and the color developing material. When the content of the microcapsules is 80% by mass or less, it is advantageous in terms of color developability.

Developer layer of the developer material is preferably void volume is ^{1ml / m 2 ~10ml / m 2} .
When the void amount of the developer layer is 1 ml / m ² or more, the color of the colored portion does not spread (bleeds) excessively with respect to the pressed part, and the color spreads (bleeds) into an appropriate range with respect to the pressed part. Can be expressed. In addition, when the amount of voids in the developer layer is 10 ml / m ² or less, the color spread (bleeding) of the color developing portion with respect to the pressed portion appears in an appropriate range.
The void volume of the developer ^layer, more preferably ^{2ml / m 2 ~6ml / m 2} , 3ml / m 2 ~6ml / m 2 is more preferable.

The void amount of the developer layer is a value determined by the following formula.
The mass (m ₁ ) of the developer material cut to 10 cm × 10 cm is measured. Next, diethylene glycol is allowed to penetrate into the developer layer of the developer material, and after diethylene glycol remaining on the surface is wiped off, the mass (m ₂ ) is measured. When X = m ₂ −m ₁ , the void amount is obtained from the following formula. The density of diethylene glycol is 1.118.
Void volume (ml / m ² ) = 100 × X ÷ 1.118

  In addition to the above, the details of the color former layer of the color development material, the color developer layer of the color development material, and the support in the pressure measurement material set are the same as in the case of the pressure measurement material described above. The preferred embodiment is also the same.

In the pressure measurement material set according to the present disclosure, the diameter of the color development portion when the color is developed by pressurizing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm exceeds 10 mm and is 10 mm or less. This indicates that, when color is developed by being pressed with a terminal having a diameter of 5 mm, the color development at the pressed portion oozes out to the surroundings, and the colored portion is enlarged within an appropriate range with respect to the area of the pressed portion. This point is as described in the above-described pressure measurement material.
The diameter of the coloring portion when the color is developed by pressurization with the above pressure is preferably 6 mm to 10 mm. Further, the diameter of the coloring portion is more preferably 7.5 mm to 10 mm from the viewpoint of the visibility of the coloring portion, and 7.5 mm to 9.0 mm from the viewpoint of high visibility of the coloring portion and not impairing the appearance. Is more preferable.

  The diameter of the color development part is a prescaled pressurizer (FPHL, manufactured by FUJIFILM Corporation), and a terminal having a circular tip and a tip diameter of 5 mm is developed on the pressed part. This is a value obtained by measuring with a scaler the diameter of the colored portion that is colored by applying a pressure of 50 MPa to the coloring material superimposed on the material.

  In the two-sheet type, a color developing material having a color developing layer and a color developing material having a color developing layer are overlapped by bringing the surface of the color developing material layer of the color developing material and the surface of the color developing layer of the color developing material into contact with each other. In the state where the color forming material and the color developing material are overlapped, the pressure or pressure distribution is sandwiched between the parts to be measured, and measurement is performed.

<Pressure measurement method>
Next, the pressure measurement method of the present disclosure will be described for each aspect.

-First embodiment-
The pressure measurement method according to the first aspect of the present disclosure uses the liquid for a color former layer for forming the color former layer and the liquid for the developer layer for forming the developer layer, as described above. It is a method of measuring.
That is, the pressure measurement method of the first aspect is:
A step of forming a developer layer by applying a liquid for a developer layer containing an electron-accepting compound to one of the pressure-receiving portions of each of the two materials (hereinafter also referred to as a “developer layer forming step”). And a step of forming a color former layer by applying a liquid for a color former layer containing an electron donating dye precursor to the other side of the developer layer or the pressure-sensitive part (hereinafter referred to as “color former layer formation”). And a step of developing a color by applying pressure to the developer layer and the color former layer (hereinafter also referred to as a “color development step”) formed on the pressed part.
The ratio of the applied amount of the color former layer liquid to the total applied amount of the color former layer liquid and the developer layer liquid in the pressure-receiving portion is 0.5 to 0.8 on a mass basis, In addition, the color developer layer and the color developer layer to be developed have a diameter of the color development portion in the range of more than 5 mm and 10 mm or less when the color is developed by pressurizing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm. Yes.

  As described above, “the diameter of the color developing portion when the color is developed by pressurizing with a terminal having a diameter of 5 mm at a pressure of 50 MPa” exceeds 5 mm and is 10 mm or less.

In the pressure measurement method according to the first aspect of the present disclosure, the ratio of the applied amount of the color former layer liquid to the total applied amount of the color former layer liquid and the developer layer liquid in the pressurized portion is expressed as mass. The range is from 0.5 to 0.8.
In this case, the ratio of the application amount of the developer layer liquid to the total application amount of the color developer layer liquid and the developer layer liquid is in the range of 0.2 or more and less than 0.5.
In forming the color former layer and the developer layer, the ratio of the amount of the liquid for the color developer layer out of the total amount of the liquid for the color developer layer and the liquid for the developer layer is determined for the developer layer. By increasing the applied amount of the liquid, the diameter of the color development part when the pressure measurement material or the pressure measurement material set is colored by pressurizing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm, It can be adjusted to a range of more than 5 mm and 10 mm or less.

  Among the above, the ratio of the applied amount of the color former layer liquid to the total applied amount of the color former layer liquid and the developer layer liquid is preferably 0.6 to 0.8 on a mass basis.

In the pressure measurement method according to the first aspect of the present disclosure, it is not necessary to prepare the pressure measurement material or the color development material and the color development material as described above, and the color development agent layer directly on the measurement target pressure site. By applying the liquid for use and the liquid for the developer layer, it is possible to easily measure the pressure at the desired pressure-receiving site.
The material of the pressed part is preferably a metal or a resin. There is no restriction | limiting in particular about the kind of metal and resin, What is necessary is just to select the desired material suitably.

In the pressure measurement method according to the first aspect of the present disclosure, for example, a developer layer liquid is applied (for example, applied) to the surface of a metal material (for example, a metal plate fastened with a screw), and the developer layer is applied. And a color former layer liquid is applied (for example, applied) to the surface of the washer into which a bolt for fastening the metal plate is inserted to form a color former layer. Then, a washer is placed on the developer layer so that the developer layer and the color developer layer are in contact with each other, and when the screws are tightened and pressure is applied to the color developer layer and the developer layer, the color is developed. The degree of pressure and the pressure distribution can be measured at the color-developing portion that has oozed out of the surface.
Also, for example, a developer layer is formed by applying (e.g., applying) a liquid for a developer layer to the surface of a metal material (e.g., a metal plate tightened with a screw), and the formed developer layer Further, a color former layer liquid is applied on top of each other (for example, applied) to laminate the color former layer, and when the pressure is applied to the color former layer and the developer layer by tightening the screws, the color develops on the outside of the bolt. The degree of pressure and the pressure distribution can be measured in the color development portion that has oozed out.

(Developer layer forming process)
In the developer layer forming step, a developer layer liquid containing an electron-accepting compound is applied to one of the pressure-receiving portions of the two materials, thereby forming the developer layer.
One of the pressed parts of the two materials refers to a pressed part of one member of the two materials that are in a positional relationship facing each other and to which the same pressure is applied.

  It is preferable that one of the two pressed portions of the two materials is a pressed portion of a material disposed at a position farther from the viewing direction of the two materials. That is, it is preferable to form a developer layer at a pressure-receiving portion of a material arranged at a position farther from the viewing direction.

The liquid for the developer layer may be a dispersion liquid in which an electron accepting compound is dispersed in water or the like. In addition to the dispersion, the developer layer liquid may contain water-soluble polymer compounds, binders, pigments, and additives such as fluorescent brighteners, antifoaming agents, penetrants, and preservatives.
When the electron-accepting compound is an inorganic compound, the dispersion liquid in which the electron-accepting compound is dispersed can be prepared by mechanically dispersing the inorganic compound in water. In addition, when the electron accepting compound is an organic compound, the developer layer liquid can be prepared by mechanically dispersing the organic compound in water or dissolving it in an organic solvent.
For the details of the method for preparing the developer layer liquid, the method described in JP-A-8-207435 can be referred to.

  The content of the developer in the liquid for the developer layer is preferably 10% by mass to 50% by mass, and preferably 15% by mass to 35% by mass with respect to the total solid content of the color former layer and the developer layer. % Is more preferable.

Application of the developer layer liquid can be performed by a known coating method.
Examples of known coating methods include coating methods using air knife coaters, rod coaters, bar coaters, curtain coaters, gravure coaters, extrusion coaters, die coaters, slide bead coaters, blade coaters, and the like. .

Application amount of the liquid for the developer layer is ^{preferably 2g / m 2 ~30g / m 2} , 3g / m 2 ~ 20g / m 2 is more preferable.

(Coloring agent layer forming step)
In the color former layer forming step, a color former layer is formed by applying a liquid for a color former layer containing an electron donating dye precursor on the developer layer or on the other side of the pressure.
The other of the pressure-sensitive parts of the two materials is the pressure-sensitive part in the other member in which the developer layer is not formed out of the two materials that are in a positional relationship facing each other and are given the same pressure. Point to.

  It is preferable that the other of the pressed parts of the two materials is a pressed part of the material arranged at a position closer to the viewing direction from the two materials. That is, it is preferable to form the color former layer on the pressed portion of the material arranged closer to the viewing direction.

The color former layer may be formed, for example, by applying a color former layer liquid on a support by a method such as coating and drying.
The microcapsules contained in the color former layer may be obtained as a dispersion as described above. The obtained dispersion liquid of microcapsules may be used as a color former layer liquid for forming a color former layer containing an electron donating dye precursor as it is.

  Further, the color former layer liquid is added to the obtained microcapsule dispersion, and further a water-soluble polymer binder (for example, a fine powder of starch or starch derivative, a buffering agent such as cellulose fiber powder, polyvinyl alcohol, or the like). , Hydrophobic polymer binder (for example, vinyl acetate, acrylic, styrene / butadiene copolymer latex, etc.), surfactant, inorganic particles (for example, silica particles), fluorescent whitening agent, antifoaming agent, penetration It may be prepared by adding an agent, an ultraviolet absorber, a preservative and the like.

  The content of the microcapsules is preferably 40% by mass to 80% by mass, and more preferably 50% by mass to 80% by mass with respect to the total solid content of the color former layer and the developer layer.

  The application of the liquid for the color former layer can be performed by a known coating method. The known coating method is the same as the coating method that can be used for applying the developer layer liquid described above.

Application amount of the liquid for the color former layer is ^{preferably 5g / m 2 ~100g / m 2} , 10g / m 2 ~50g / m 2 is more preferable.

(Coloring process)
In the color development step, pressure is applied to the color developer layer and the color developer layer formed on the pressed part to cause color development.
The application of pressure can be performed by applying pressure (point pressure, linear pressure, surface pressure, etc.) by a point, a line, or a surface by any method.
The pressure may be selected in the range of 1.0 MPa to 100 MPa from the viewpoint of visibility and ease of confirmation of the pressure distribution.

-Second aspect-
The pressure measurement method according to the second aspect of the present disclosure is a method of measuring using a pressure measurement material or a pressure measurement material set.
That is, in the pressure measurement method according to the second aspect of the present disclosure, the above-described pressure measurement material or the above-described pressure measurement material set is disposed in the pressed portion, and the developer layer and the color developer layer are arranged. A step of applying pressure to develop a color.

In the pressure measuring method according to the second aspect of the present disclosure, the pressure measuring material, or the coloring material and the developing material as described above are used, and the pressure measuring material, or the coloring material and the developing material are applied to the pressed part. By arranging and applying pressure, the pressure at the site to be pressed can be measured.
There is no restriction | limiting in particular in the material of a to-be-pressed part, A metal or resin may be sufficient. There is no restriction | limiting in particular about the kind of metal and resin, What is necessary is just to select the desired material suitably.

  The details of the pressure measurement material or the pressure measurement material set (the color forming material and the color developing material) are as described above, and the preferred embodiments are also the same.

  The application of pressure can be performed by applying pressure (point pressure, linear pressure, surface pressure, etc.) by a point, a line, or a surface by any method.

<Pressure measurement liquid set>
The liquid set for pressure measurement according to the present disclosure includes a liquid for a color former layer containing an electron donating dye precursor and a liquid for a developer layer containing an electron accepting compound that develops an electron donating dye precursor. The ratio of the solid content of the color former layer liquid to the total solid content of the color former layer liquid and the developer layer liquid used for pressure measurement is more than 0.5 and 0.8 or less on a mass basis It is what.
The pressure measurement liquid set according to the present disclosure includes the color developer layer liquid and the developer layer liquid separately, and is suitable for the pressure measurement method according to the first aspect of the present disclosure described above.

The details of the electron-donating dye precursor and the electron-accepting compound, the color former layer liquid and the developer layer liquid are as described above, and the preferred embodiments are also the same.
Further, “the ratio of the amount of the color former layer liquid to the total amount of the color former layer liquid and the developer layer liquid used for pressure measurement” is also as described above.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Unless otherwise specified, “part” is based on mass.

Example 1
-Preparation of developer-containing liquid-
Activated clay that is an electron accepting compound (developer): Silton F-242 (Mizusawa Chemical Industry Co., Ltd.) 100 parts, 40 parts by weight of sodium hydroxide aqueous solution 5 parts and water 300 parts are added and dispersed with a homogenizer. Further, 50 parts of a 10% by weight sodium salt of casein (binder) and 30 parts of styrene-butadiene latex (Smartex SN-307R, manufactured by Nippon A & L Co., Ltd., solid content = 48% by weight; binder) were added, A coating solution for developer layer (liquid for developer layer) containing an electron-accepting compound was prepared.
It was 5 micrometers when the average primary particle diameter of the electron-accepting compound disperse | distributed in the coating liquid for developer layers was measured using the particle size distribution measuring apparatus (Microtrac HRA, Nikkiso Co., Ltd. product).

-Preparation of electron-donating dye precursor encapsulated microcapsule solution-
Hysol SAS-296 (oil component (solvent) manufactured by Nippon Oil Co., Ltd .; mixture of 1-phenyl-1-xylylethane and 1-phenyl-1-ethylphenylethane) was added to 70 parts as an electron-donating dye precursor. 9 parts of butylamino-6-methyl-7-anilinofluorane (ODB2) was dissolved to obtain a solution A. Next, 0.4 part of an ethylenediamine butylene oxide adduct dissolved in 1 part of methyl ethyl ketone was added to the stirring solution A to obtain a solution B. Further, 2 parts of a trimethylolpropane adduct of tolylene diisocyanate dissolved in 1 part of methyl ethyl ketone was added to the stirring solution B to obtain a solution C. And said solution C was added to the solution which melt | dissolved 6 parts of polyvinyl alcohol (PVA-205, Kuraray Co., Ltd.) in 150 parts of water, and it emulsified and dispersed. 300 parts of water was added to the emulsified liquid after emulsification and dispersion, and the mixture was heated to 70 ° C. with stirring, cooled for 1 hour and then cooled. The concentration was adjusted by adding water to prepare an electron donating dye precursor-encapsulated microcapsule liquid (liquid for color former layer) having a solid concentration of 18% by mass.
Moreover, it was 8.0 micrometers when the average primary particle diameter of the microcapsule was measured using a particle size distribution measuring device (Microtrac HRA, manufactured by Nikkiso Co., Ltd.).

-Production of pressure measurement material-
The developer layer coating solution obtained above was applied onto a 75 μm thick polyethylene terephthalate (PET) film with a bar coater at a solid content of 15 g / m ² to form a developer layer. Next, the electron donor dye precursor-encapsulated microcapsule liquid was applied on the developer layer with a bar coater at a solid content application amount of 35.0 g / m ² to form a color developer layer.
In this way, a monosheet type pressure measurement material was produced in which two layers of a developer layer and a color former layer were sequentially laminated on a PET film.
The coating amount of the developer layer and the color former layer was confirmed by measuring a mass of 20 cm × 20 cm with an upper pan balance before and after coating.

-Contact angle of oil component-
The contact angle on the surface of the developer layer of the oil component (Hysol SAS-296) used for the preparation of the electron-donating dye precursor-encapsulated microcapsule solution was measured as follows.
That is, 1 μL of the oil component was dropped on the surface of the developer layer formed by applying the developer layer coating liquid on the PET film and dried, and then contacted dynamically when 0.1 second had elapsed. It was measured with an angle measuring device (FIBRO DAT 1100, manufactured by Fibro). It measured similarly also in the other Example and comparative example shown below.

-Measurement / Evaluation 1
The following measurements and evaluations were performed using the pressure measurement material. The results of measurement and evaluation are shown in Table 3 below.

[1a. Void amount]
A PET film having a developer layer formed thereon was prepared in the same manner as described above, and the void amount of the developer layer was determined from the following formula.
The PET film on which the developer layer was formed was cut into 10 cm × 10 cm, and the mass (m ₁ ) was measured. Next, diethylene glycol was allowed to permeate on the surface of the developer layer, and after the diethylene glycol remaining on the surface was wiped off, the mass (m ₂ ) was measured. Then, it calculates _{X =} m 2 -m _1, was determined void volume from the following equation. The density of diethylene glycol is 1.118.
Void volume (ml / m ² ) = 100 × X ÷ 1.118

[2a. Colored part diameter]
Using a prescale-only pressurizer (FPHL, manufactured by Fuji Film Co., Ltd.), a terminal having a circular tip and a tip diameter of 5 mm is applied to the surface of the color former layer of the pressure measurement material, The diameter of the colored portion that was colored by pressurizing at a pressure of 50 MPa was measured with a scaler.

[3a. Visibility]
A pressure measurement material molded into a donut shape (inner diameter 8 mm, outer diameter 26 mm) is placed so as to surround a circular hole (diameter 10 mm) provided in a stainless steel plate, and the pressure measurement material is placed on the pressure measurement material. A washer with an outer diameter of 16 mm was placed on top of this, and in this state, a bolt was passed through the hole and tightened with a pressure of 50 MPa. At this time, the pressure measurement material was placed on a stainless steel plate so that the PET film was in contact with the plate.
After the tightening operation, the colored portion of the pressure measurement material (the portion of the pressure measurement material protruding from the washer) was evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: The color-developing part can be sufficiently visually recognized even from a place where the distance exceeds 1 m.
B: The color-developing part can be visually recognized from a distance of 0.3 m or more and less than 1 m.
C: Even if the coloring portion approaches a distance of less than 0.3 m, it cannot be visually recognized.

[4a. Check pressure distribution]
The tightening operation was performed in the same manner as in “3a. Visibility” described above, and the pressure measurement material was colored, and whether or not the pressure distribution could be confirmed was determined for the colored portion according to the following evaluation criteria.
<Evaluation criteria>
Possible: When pressurizing at a pressure of 10 MPa and 50 MPa with a 5 mm diameter terminal, a difference in color development diameter or color development density can be confirmed.
Impossibility: When pressurizing at a pressure of 10 MPa and 50 MPa with a 5 mm diameter terminal, the difference in color development diameter or color development density cannot be confirmed.

[5a. Color stability]
The tightening operation was performed in the same manner as in “3a. Visibility” to develop a color for the pressure measurement material, and the coloration stability in the color development portion was evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: The color development history was confirmed even when the color development part of the pressure measurement material was washed with running water at 25 ° C. for 10 seconds.
B: When the color development portion of the pressure measurement material was washed with running water at 25 ° C. for 10 seconds, the color development history could not be confirmed due to, for example, flowing.

[6a. Dirty measurement part of measurement object]
In the same manner as in “3a. Visibility”, the pressure measurement material is colored by performing the tightening operation, and the degree of contamination at the contact portion between the stainless steel plate and the bolt and the pressure measurement material as the measurement object is determined. Evaluation was performed according to the following evaluation criteria.
<Evaluation criteria>
A: In the measurement object, there is no stain derived from coloring at the contact portion with the pressure measurement material.
B: In the measurement object, a very small amount of color is adhered to the contact portion with the pressure measurement material.
C: In the object to be measured, stains derived from coloration can be clearly confirmed at the contact portion with the material for pressure measurement.

(Examples 2 to 13, 17 and Comparative Example 1)
In Example 1, a pressure measurement material was prepared in the same manner as in Example 1 except that the changes shown in Table 1 and Table 2 were added to the color former layer and the developer layer. Measurements and evaluations similar to those of 1 were performed. The results of measurement and evaluation are shown in Table 3 below.

(Example 14)
In Example 1, a coating solution for developer layer (liquid for developer layer) prepared in the same manner as in Example 1 on a glass substrate (dummy glass substrate, manufactured by ASONE Co., Ltd.) Was applied at 15 g / m ^{2 by} a bar coater to form a developer layer. Thereafter, an electron donating dye precursor-encapsulated microcapsule solution prepared in the same manner as in Example 1 was further applied onto the developer layer by a bar coater with a solid content application amount of 35.0 g / m ² . The color former layer was formed by drying.
As described above, in this embodiment, the developer layer coating solution and the electron donating dye are directly used on the glass substrate without using the pressure measurement material or the pressure measurement material set (coloring material and developer material). The developer layer and the color former layer were attached by applying the precursor-encapsulated microcapsule solution. The developer layer and the color former layer provided on the glass substrate function as a pressure measurement material.

-Measurement / Evaluation 2-
The following measurements and evaluations were performed on a glass substrate provided with a developer layer and a color former layer. The results of measurement and evaluation are shown in Table 3 below.

[1b. Void amount]
A glass substrate provided with only the developer layer was prepared in the same manner as described above, and the void amount of the developer layer was determined from the following formula. The above value was used for the layer thickness of the developer layer, and the void amount was determined by the same method as described above.
Void volume (ml / m ² ) = 100 × X ÷ 1.118

[2b. Colored part diameter]
The measurement was performed in the same manner except that the material for pressure measurement was replaced with a glass substrate provided with a developer layer and a color former layer in “2a. Diameter of color former”.

[3b. Visibility]
In “3a. Visibility”, the measurement was performed in the same manner except that the pressure measurement material and the stainless steel plate were replaced with the glass substrate provided with the developer layer and the color former layer.

[4b. Check pressure distribution]
Whether or not the pressure distribution can be confirmed was determined according to the same evaluation criteria as in the above “4a. Confirmation of pressure distribution” with respect to the colored portion that was colored in the same manner as in “3a. Visibility”.

[5b. Color stability]
In the same manner as in the above “3a. Visibility”, the coloration stability in the colored portion developed was evaluated according to the same evaluation criteria as in the above “5a. Coloration stability”.

[6b. Dirty measurement part to be measured]
In the same manner as in the above “3a. Visibility”, the color is developed, and the degree of contamination at the contact portion between the glass substrate, the color former layer and the developer layer is evaluated in the same manner as in “6a. Evaluation was made according to criteria.

(Example 15)
-Production of developer sheet-
A coating solution for a developer layer (a developer layer liquid) prepared in the same manner as in Example 1 was applied on a polyethylene terephthalate (PET) sheet having a thickness of 75 μm with a solid coating amount of 15 g / m ^2. A developer sheet (developer material) was produced by applying the coating layer and drying to form a developer layer.

-Production of color former sheet-
An electron donating dye precursor-encapsulated microcapsule solution prepared in the same manner as in Example 1 was coated on another 75 μm-thick polyethylene terephthalate (PET) sheet with a solid content of 35.0 g / m ² in a bar coater. A color former sheet (color development material) was prepared by applying and drying to form a color former layer.

As described above, a pressure measurement material set including a developer sheet and a color former sheet was produced.
The coating amount of the developer layer and the color former layer was confirmed by measuring the mass of 20 cm × 20 cm before and after coating with an upper pan balance.

-Measurement / Evaluation 3-
The following measurement and evaluation were performed using the prepared pressure measurement material set. The results of measurement and evaluation are shown in Table 2 below.

[1c. Void amount]
Using the developer material, the void amount of the developer layer was determined from the following formula.
The mass (m ₁ ) of the developer material cut to 10 cm × 10 cm was measured. Next, diethylene glycol was placed on the surface of the developer layer of the developer amount and allowed to permeate, and after diethylene glycol remaining on the surface was wiped off, the mass (m ₂ ) was measured. Then, it calculates _{X =} m 2 -m _1, was determined void volume from the following equation. The density of diethylene glycol is 1.118.
Void volume (ml / m ² ) = 100 × X ÷ 1.118

[2c. Colored part diameter]
Using a prescale-only pressurizer (FPHL, manufactured by Fuji Film Co., Ltd.), the color developer layer and the developer layer are in contact with each other at a terminal having a circular tip and a tip diameter of 5 mm. The diameter of the color-development portion developed by applying pressure at 50 MPa on the PET film surface of the color-development material and the color-development material in the development material was measured with a scaler.

[3c. Visibility]
A coloring material and a developing material formed into a donut shape (inner diameter: 8 mm, outer diameter: 26 mm) so as to surround a circular hole (diameter: 10 mm) provided in a stainless steel plate material are colored with the developing material from the plate material side. The materials were placed one on top of the other in order. The color developing material and the color developing material were stacked so that the color developing layer and the color developer layer were in contact with each other. Then, a washer with an outer diameter of 16 mm was placed on the coloring material, and the bolt was passed through the hole in this state and tightened with a pressure of 50 MPa. After the tightening operation, the color developing portion (the color developing material and the color developing material protruding from the washer) was evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: The color-developing part can be sufficiently visually recognized even from a place where the distance exceeds 1 m.
B: The color-developing part can be visually recognized from a distance of 0.3 m or more and less than 1 m.
C: Even if the coloring portion approaches a distance of less than 0.3 m, it cannot be visually recognized.

[4c. Check pressure distribution]
The tightening operation is performed in the same manner as in “3a. Visibility” to develop a color for the pressure measurement material set, and the colored portion is subjected to pressure distribution according to the same evaluation criteria as in “4a. Confirmation of pressure distribution”. Judgment was made on whether or not confirmation is possible.

[5c. Color stability]
In the same manner as in “3a. Visibility”, the tightening operation is performed to develop a color for the pressure measurement material set, and the coloration stability in the color development portion is evaluated according to the same evaluation criteria as in “5a. Coloration stability”. did.

[6c. Dirty measurement part to be measured]
In the same manner as in “3a. Visibility”, the tightening operation is performed to develop a color for the pressure measurement material set, and the degree of contamination at the contact portion between the stainless steel plate and bolt as the measurement object and the pressure measurement material is determined. Evaluation was performed according to the same evaluation criteria as in “6a.

(Example 16)
In the production of the developer sheet of Example 15, the developer layer coating liquid (developer layer liquid) prepared in the same manner as in Example 1 was used as the developer layer coating liquid (developer) described below. A developer sheet and a color former sheet were prepared in the same manner as in Example 15 except that the liquid was changed to (Liquid for agent layer), and the same measurement and evaluation as in Example 15 were performed. The results of measurement and evaluation are shown in Table 2 below.

-Preparation of coating solution for developer layer-
To 100 parts of Silton F-242 (Mizusawa Chemical Co., Ltd.) which is an electron-accepting compound (developer), 5 parts of a 40% by mass aqueous sodium hydroxide solution and 20% by mass PVA-105 which is a water-soluble polymer compound ( 810 parts of Kuraray Co., Ltd.) and 300 parts of water were added and dispersed with a homogenizer. To the obtained dispersion, 50 parts of a 10% by weight sodium salt of casein (binder) and a styrene-butadiene latex (Smartex SN-307R, manufactured by Nippon A & L Co., Ltd., solid content = 48% by weight; binder) 30 A coating solution for a developer layer (a liquid for a developer layer) containing an electron accepting compound was prepared.
It was 5 micrometers when the average primary particle diameter of the electron-accepting compound disperse | distributed in the coating liquid for developer layers was measured using the particle size distribution measuring apparatus (Microtrac HRA, Nikkiso Co., Ltd. product).

(Comparative Example 2)
Hysol SAS-296 (oil component (solvent) manufactured by Nippon Oil Co., Ltd .; mixture of 1-phenyl-1-xylylethane and 1-phenyl-1-ethylphenylethane) was added to 70 parts as an electron-donating dye precursor. 9 parts of butylamino-6-methyl-7-anilinofluorane (ODB2) and 9 parts of bisphenol A as an electron-accepting compound were dissolved to obtain a solution A. Next, 0.4 part of an ethylenediamine butylene oxide adduct dissolved in 1 part of methyl ethyl ketone was added to the stirring solution A to obtain a solution B. Further, 2 parts of a trimethylolpropane adduct of tolylene diisocyanate dissolved in 1 part of methyl ethyl ketone was added to the stirring solution B to obtain a solution C. And said solution C was added to the solution which melt | dissolved 6 parts of polyvinyl alcohol (PVA-205, Kuraray Co., Ltd.) in 150 parts of water, and it emulsified and dispersed. 300 parts of water was added to the emulsified liquid after emulsification and dispersion, and the mixture was heated to 70 ° C. with stirring, stirred for 1 hour, and then cooled. The concentration was adjusted by adding water to prepare a microcapsule solution having a solid content concentration of 18% by mass in which the electron-donating dye precursor and the electron-accepting compound were encapsulated in the microcapsules.
The prepared microcapsule liquid was applied onto a PET film with a bar coater at a solid content coating amount of 50.0 g / m ² to form a microcapsule layer.
As described above, a pressure measurement material in which a single microcapsule layer was provided on a PET film was produced.

  Measurement and evaluation were performed in the same manner as in Example 1 using the pressure measurement material obtained above. The results of measurement and evaluation are shown in Table 2 below. In “1a. Void amount”, the PET film on which the developer layer was formed was used in place of the pressure measurement material.

In Tables 1 and 2, “microcapsule content”, “developer content”, and “water-soluble polymer content” are all those for the solid content of the color former layer and the developer layer. Means the content of an ingredient.
In Tables 1 and 2, the developer particle diameter means the average primary particle diameter of the developer.
In Table 3, the diameter of the coloring portion refers to the diameter of the coloring portion when pressed at a pressure of 50 Mpa with a terminal of 5 mm.
Details of the components in Tables 1 and 2 are as follows.
ODB2: 3-butylamino-6-methyl-7-anilinofluorane, Yamamoto Kasei Co., Ltd. CVL: Crystal Violet Lactone, Tsuchiya Chemical Co., Ltd. Alkene L: Alkylbenzene, JX Nippon Oil & Energy Corporation, KMC-500 : Diisopropylbiphenyl, Kureha Chemical Industry Co., Ltd., Galeon Earth SH: Activated clay, Mizusawa Chemical Industry Co., Ltd., Galeon Earth NV: Activated clay, Mizusawa Chemical Industry Co., Ltd., BPA: Bisphenol A, Idemitsu Kosan Co., Ltd.

-Iron plate: SECC, plate bending. com, glass substrate: dummy glass substrate, ASONE

As shown in Tables 1 to 3, in the examples, the visibility of the coloring portion was good and the pressure distribution could be easily confirmed.
On the other hand, in Comparative Example 1, since the coloring portion did not bleed out, the amount of voids in the developer layer was too large, the visibility was inferior, and the pressure distribution could not be confirmed. Further, in Comparative Example 2 in which the color former and the developer are included in the same layer, since the bleeding at the color development portion is too much, the visibility is good, but the color density is too high and the pressure distribution is high. Confirmation was not possible, and the adhesion of dirt to the measurement object was recognized.

The disclosure of Japanese Patent Application No. 2017-046757 filed on March 10, 2017 is incorporated herein by reference in its entirety.
All documents, patents, patent applications, and technical standards mentioned in this specification are specifically and individually described as individual documents, patents, patent applications, and technical standards are incorporated by reference. To the same extent, it is incorporated herein by reference.

Claims (15)

A support;
A color former layer comprising an electron donating dye precursor;
A developer layer comprising an electron-accepting compound disposed between the support and the color former layer and causing the electron-donating dye precursor to develop color;
Have
A material for pressure measurement, wherein a diameter of a color developing portion when a color is developed by pressurizing with a terminal having a diameter of 5 mm at a pressure of 50 MPa is more than 5 mm and not more than 10 mm. The developer layer is pressure measurement material according to claim 1 void volume is ^{1ml / m 2 ~10ml / m 2} .   The color former layer includes a microcapsule containing the electron donating dye precursor, and the content of the microcapsule is 40% by mass with respect to the total solid content of the color former layer and the developer layer. The pressure measurement material according to claim 1 or 2, which is as described above.   The content of the electron-accepting compound in the developer layer is 10% by mass to 50% by mass with respect to the total solid content of the color former layer and the developer layer. The pressure measurement material according to claim 3.   The material for pressure measurement according to any one of claims 1 to 4, wherein an average primary particle diameter of the electron-accepting compound is 10 µm or less.   The pressure measuring material according to claim 1, wherein the developer layer further contains a water-soluble polymer compound.   The material for pressure measurement according to claim 6, wherein the content of the water-soluble polymer compound is 20% by mass or more based on the total solid content of the developer layer.   The said color former layer is a pressure measuring material of any one of Claims 1-7 containing the oil component whose contact angle with respect to the surface of the said developer layer is 30 degrees or less further. A color former having a color former layer containing an electron donating dye precursor;
A developer material having a developer layer containing an electron-accepting compound for coloring the electron-donating dye precursor;
Including
A material set for pressure measurement, wherein a diameter of a color developing portion when a color is developed by pressurizing at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm is more than 5 mm and not more than 10 mm. The developer layer is pressure measurement for the material set according to claim 9 void volume is ^{1ml / m 2 ~10ml / m 2} .   The color former layer includes a microcapsule containing the electron donating dye precursor, and the content of the microcapsule is 40% by mass with respect to the total solid content of the color former layer and the developer layer. It is the above, The material set for pressure measurement of Claim 9 or Claim 10. A step of applying a developer layer liquid containing an electron-accepting compound to one of the to-be-pressured portions of the two materials to form a developer layer;
Forming a color former layer by applying a color former layer liquid containing an electron donating dye precursor on the developer layer or on the other side of the pressure-applied portion;
Applying pressure to the color developer layer and the color former layer formed at the pressed portion to cause color development; and
Have
The ratio of the solid content application amount of the color former layer liquid to the total solid content application amount of the color former layer liquid and the developer layer liquid at the pressed portion is 0.5 on a mass basis. And 0.8 or less,
The developer layer and the color developer layer to be developed have a diameter of a color development portion of more than 5 mm and 10 mm or less when color is developed by applying pressure at a pressure of 50 MPa with a terminal having a tip diameter of 5 mm.
Pressure measurement method.   The pressure measurement material according to any one of claims 1 to 8 or the pressure measurement material set according to any one of claims 9 to 11 is arranged at a pressed part, and developed. A pressure measurement method comprising a step of applying pressure to the agent layer and the color former layer to cause color development.   The pressure measurement method according to claim 12 or 13, wherein a material of the pressed part is metal or resin. A color former layer liquid comprising an electron donating dye precursor;
A liquid for a developer layer containing an electron-accepting compound for coloring the electron-donating dye precursor;
The ratio of the solid content of the color former layer liquid to the total solid content of the color former layer liquid and the developer layer liquid used for pressure measurement is 0.5 on a mass basis. The liquid set for pressure measurement which is more than 0.8 and less.