JP7231732B2 - Sheet set for pressure measurement, sheet for pressure measurement - Google Patents

Description

The present invention relates to a pressure measurement sheet set and a pressure measurement sheet.

Pressure measurement sheets (that is, sheets used to measure pressure) are used in applications such as lamination of liquid crystal glass, solder printing on printed circuit boards, pressure adjustment between rollers, and the like.
For example, Patent Document 1 discloses a sheet for pressure measurement that utilizes a color-developing reaction between a color former and a developer, and is said to be capable of measuring pressures in the range of about 0.1 MPa to 20 MPa. . Further, Patent Document 2 discloses a sheet for pressure measurement that can be well colored in a low pressure range (especially a pressure of 3 MPa or less) and can be satisfactorily read in density.

Japanese Patent Publication No. 57-24852 Patent No. 4986749

In recent years, the measurement of pressure distribution under actual manufacturing conditions has become important. For example, in pressure bonding operations in various high-temperature environments, such as thermocompression bonding of integrated circuits and wiring to printed circuit boards, it is desired to measure precise pressure distributions in order to improve yields.
The present inventor measured the pressure distribution in a high temperature environment (especially 180 ° C. or higher) using a pressure measurement sheet as described in Patent Documents 1 and 2, and visually confirmed the accurate pressure distribution. Otherwise, it was found that the pressure distribution could not be measured accurately.
An object of the present invention is to provide a pressure-measuring sheet set and a pressure-measuring sheet that can precisely measure pressure distribution when used in a high-temperature environment.

As a result of intensive studies on the above problem, the inventors have found that the above problem can be solved by the following configuration.

[1] a first sheet having a first support and a first layer containing microcapsules containing a coloring agent disposed on the first support;
a second sheet having a second support and a second layer comprising a developer disposed on the second support;
A pressure measurement sheet set comprising:
When the first sheet is heated at 220° C. for 10 minutes, both the shrinkage rate S1 in the longitudinal direction of the first sheet and the shrinkage rate S2 in the width direction perpendicular to the longitudinal direction of the first sheet are -0.5 to 2.0%,
When the second sheet is heated at 220° C. for 10 minutes, both the shrinkage rate S1 in the longitudinal direction of the second sheet and the shrinkage rate S2 in the width direction orthogonal to the longitudinal direction of the second sheet are A sheet set for measuring pressure, which is between -0.5 and 2.0%.
[2] The absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the first sheet and the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the second sheet are both The sheet set for pressure measurement according to [1], which is 0 to 0.8%.
[3] The sheet set for pressure measurement according to [1] or [2], wherein the developer is a clay substance.
[4] The sheet set for pressure measurement according to any one of [1] to [3], wherein each of the first support and the second support has a thickness of 25 to 200 μm.
[5] The pressure measurement sheet set according to any one of [1] to [4], wherein both the first support and the second support are polyethylene naphthalate films.
[6] The pressure measurement sheet set according to any one of [1] to [5], wherein the first sheet has an adhesive layer between the first support and the first layer.
[7] The pressure measurement sheet set according to any one of [1] to [6], wherein the second sheet has an adhesive layer between the second support and the second layer.
[8] The pressure measurement sheet set according to [6] or [7], wherein the adhesion layer contains a polymer having an aromatic group.
[9] a first layer containing microcapsules encapsulating a coloring agent;
a second layer comprising a developer disposed on the first layer;
A sheet for pressure measurement, comprising: a support arranged on the side of the first layer opposite to the second layer, or on the side of the second layer opposite to the first layer; hand,
When the pressure measurement sheet is heated at 220° C. for 10 minutes, the contraction rate S1 in the longitudinal direction of the pressure measurement sheet and the contraction rate S2 in the width direction perpendicular to the longitudinal direction of the pressure measurement sheet are reduced. Sheets for pressure measurement, each of which is -0.5 to 2.0%.
[10] The sheet for pressure measurement according to [9], wherein the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 is 0 to 0.8%.
[11] The sheet for pressure measurement according to [9] or [10], wherein the developer is a clay substance.
[12] The sheet for measuring pressure according to any one of [9] to [11], wherein the support has a thickness of 25 to 200 μm.
[13] The pressure measurement sheet according to any one of [9] to [12], wherein the support is a polyethylene naphthalate film.
[14] When the first layer has the support on the side opposite to the second layer, an adhesion layer is provided between the support and the first layer, [9] to [13] Sheet for pressure measurement according to any one of.
[15] When the second layer has the support on the side opposite to the first layer, it has an adhesion layer between the support and the second layer, [9] to [13] Sheet for pressure measurement according to any one of.
[16] The pressure measurement sheet of [14] or [15], wherein the adhesion layer contains a polymer having an aromatic group.

According to the present invention, it is possible to provide a pressure measurement sheet set and a pressure measurement sheet that can precisely measure pressure distribution when used in a high-temperature environment.

1 is a cross-sectional view of one embodiment of a pressure measurement sheet set; FIG. FIG. 4 is a diagram for explaining a usage pattern of the pressure measurement sheet set; 1 is a cross-sectional view of one embodiment of a pressure-measuring sheet; FIG.

The present invention will be described in detail below.
In this specification, the numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.
In addition, in the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of the numerical range described in other steps. good. Moreover, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the values shown in the examples.
Various components described later may be used singly or in combination of two or more. For example, the later-described polyisocyanates may be used singly or in combination of two or more.

As a feature of the pressure measurement sheet set and the pressure measurement sheet of the present invention, when the first sheet and the second sheet in the pressure measurement sheet set and the pressure measurement sheet are heated at 220° C. for 10 minutes, The contraction rate S1 in the longitudinal direction of the first sheet, the second sheet and the pressure measurement sheet, and the contraction rate S2 in the width direction perpendicular to the longitudinal direction of the first sheet, the second sheet and the pressure measurement sheet are all -0.5 to 2.0%.
The present inventor used a conventional pressure measurement sheet to measure the pressure distribution in a high-temperature environment, and found that a For the first time, we have discovered the problem that color unevenness occurs and precise pressure distribution cannot be measured in a high-temperature environment. As a result of examining the cause of this problem, the support provided for supporting the layer containing the microcapsules and the layer containing the developer is deformed by heat, and the stress when pressure is applied is reduced. , it is found that it strongly sticks to the support instead of the microcapsules, resulting in uneven color development.
In order to solve the above problem, the inventors of the present invention found that by using a support having a small shrinkage rate when heated at a high temperature, it is possible to measure a precise pressure distribution without causing uneven coloring even in a high-temperature environment. ing.

<<First Embodiment>>
FIG. 1 is a cross-sectional view of one embodiment of a pressure measurement sheet set.
The pressure measuring sheet set 10 includes a first sheet 16 having a first support 12 and a first layer 14 containing predetermined microcapsules 13 disposed on the first support 12, a second support 18 and a second 2 a second sheet 22 having a second layer 20 comprising a developer disposed on a support 18;
When using the pressure-measuring sheet set 10, as shown in FIG. The sheet 16 and the second sheet 22 are laminated and used. By pressing from at least one of the first support 12 side of the first sheet 16 and the second support 18 side of the second sheet 22 in the obtained laminate, the microcapsules 13 are formed in the pressurized area. When broken, the coloring agent contained in the microcapsules 13 comes out of the microcapsules 13 and undergoes a coloring reaction with the coloring agent in the second layer 20 . As a result, color development progresses in the pressurized area.

Although the first support 12 and the first layer 14 are directly laminated in FIG. may be arranged with another layer (for example, an adhesion layer). In addition, although the second support 18 and the second layer 20 are directly laminated in FIG. Another layer (for example, an adhesion layer) may be arranged therebetween.

The configurations of the first sheet 16 and the second sheet 22 that constitute the pressure measurement sheet set 10 will be described in detail below.

<First sheet>
The first sheet 16 shown in FIG. 1 has a first support 12 and a first layer 14 containing microcapsules 13 encapsulating a coloring agent.

When the first sheet 16 is heated at 220° C. for 10 minutes, both the shrinkage rate S1 in the longitudinal direction of the first sheet 16 and the shrinkage rate S2 in the width direction orthogonal to the longitudinal direction of the first sheet 16 are -0.5 to 2.0%.
The shrinkage ratio S1 of the first sheet 16 is -0.5 to 2.0%, and from the point of being able to measure a more precise pressure distribution, -0.4 to 1.5% is preferable, and -0.3 to -0.3%. 1.2% is more preferred, and -0.2 to 0.8% is even more preferred.
The shrinkage ratio S2 of the first sheet 16 is -0.5 to 2.0%, and is preferably -0.4 to 1.5%, and -0.3 to -0.3 to 1.2% is more preferred, and -0.2 to 0.8% is even more preferred.
The method for measuring the shrinkage rate S1 and the shrinkage rate S2 of the first sheet 16 is as shown in Examples.

The longitudinal direction of the first sheet 16 means the longitudinal direction of the first sheet 16. Specifically, when the first sheet 16 is rectangular, it means the direction along the long sides. Further, the width direction of the first sheet 16 means a direction (transverse direction) orthogonal to the longitudinal direction of the first sheet 16. For example, when the first sheet 16 is rectangular, the width direction is along the short sides. direction. However, when the first sheet 16 is square, the longitudinal direction is the direction along one side selected arbitrarily, and the width direction is the direction along the side perpendicular to the longitudinal direction.

In the first sheet 16, the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 (|S1−S2|) is preferably 0 to 0.8%, and 0 to 0.6% is more preferred, and 0 to 0.4% is even more preferred.

The first sheet 16 may be a sheet (single sheet) or may be elongated.

Below, each member is explained in full detail.

(First support)
The first support is a member for supporting the first layer.
The first support may be sheet-like, film-like, or plate-like.
The first support preferably has a property of being resistant to shrinkage when heated at a high temperature (preferably 180° C. or higher, more preferably 200 to 240° C.). Specifically, the first support more preferably exhibits the same shrinkage rate as the first sheet when heated at 220° C. for 10 minutes.
Examples of the first support include polyethylene naphthalate (PEN) film, polyamide (PA) film, polyimide (PI) film, polysulfone (PSF) film, and polyethersulfone (PES) film. A polyethylene naphthalate film is preferable because it can suppress the heat shrinkage of the film and can measure the pressure distribution more precisely.

The thickness of the first support is preferably 10 to 300 μm. It is preferably 25 to 300 μm, more preferably 25 to 200 μm, still more preferably 25 to 150 μm, and particularly preferably 38 to 125 μm, from the viewpoint that the effects of the present invention are more excellent.
In particular, if the thickness of the first support is 25 μm or more, deformation of the first sheet during pressure measurement can be suppressed. It is possible to suppress being strongly pressed against the laminate of the first sheet and the second sheet. As a result, an appropriate pressure is applied to the position corresponding to the edge of the member, so that a more precise pressure distribution can be measured.
If the thickness of the first support is 200 μm or less, the first sheet can be prevented from bending during pressure measurement. It becomes easier for the sheet set to follow. As a result, an appropriate pressure is applied to the position corresponding to the edge of the member, so that a more precise pressure distribution can be measured.

(first layer)
The first layer contains microcapsules encapsulating a color former.
First, the material constituting the microcapsules will be described in detail below.

A microcapsule generally has a core portion and a capsule wall for enclosing a core material forming the core portion (something to be encapsulated (also referred to as an encapsulation component)).
In the present invention, the microcapsules enclose a coloring agent as a core material (encapsulation component). Since the color former is enclosed in the microcapsules, the color former can exist stably until the microcapsules are destroyed by pressure.

A microcapsule has a capsule wall that encloses a core material.
The capsule wall in the microcapsules preferably contains at least one resin selected from the group consisting of polyurea, polyurethaneurea, and polyurethane (hereinafter also simply referred to as "specific resin").
Preferably, the capsule wall of the microcapsules is substantially composed of a resin (preferably a specific resin). “Substantially composed of the resin” means that the content of the resin is 90% by mass or more, preferably 100% by mass, relative to the total mass of the capsule wall. In other words, the capsule wall of the microcapsules is preferably made of resin.
Note that polyurethane is a polymer having a plurality of urethane bonds, and is preferably a reaction product formed from raw materials containing a polyol and a polyisocyanate.
Polyurea is a polymer having multiple urea bonds, and is preferably a reaction product formed from raw materials containing polyamine and polyisocyanate. It should be noted that polyurea can be synthesized using polyisocyanate without using polyamine by utilizing the fact that a part of polyisocyanate reacts with water to form polyamine.
Polyurethane urea is a polymer having urethane bonds and urea bonds, and is preferably a reaction product formed from raw materials containing polyol, polyamine and polyisocyanate. Incidentally, when the polyol and the polyisocyanate are reacted, part of the polyisocyanate may react with water to form a polyamine, resulting in a polyurethane urea.

The polyisocyanate is a compound having two or more isocyanate groups, and includes aromatic polyisocyanates and aliphatic polyisocyanates, in that aromatic ring groups can be introduced into the capsule walls of the microcapsules. Isocyanates are preferred.
Aromatic polyisocyanates include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4'-diphenylpropane diisocyanate, and 4,4'-diphenylhexafluoropropane diisocyanate.

Aliphatic polyisocyanates include aliphatic diisocyanates such as trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexane sylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone Diisocyanates, lysine diisocyanates, and hydrogenated xylylene diisocyanates.

In the above, bifunctional aromatic polyisocyanate and aliphatic polyisocyanate were exemplified, but as polyisocyanate, trifunctional or higher polyisocyanate (e.g., trifunctional triisocyanate and tetrafunctional tetraisocyanate). mentioned.
More specifically, the polyisocyanate includes a biuret or isocyanurate trimer of the above-mentioned bifunctional polyisocyanate, an adduct (addition polyisocyanate having a polymerizable group such as formalin condensate of benzene isocyanate, methacryloyloxyethyl isocyanate, and lysine triisocyanate.
Polyisocyanate is described in "Polyurethane Resin Handbook" edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987).

Among them, as one of preferred embodiments of the polyisocyanate, tri- or higher functional polyisocyanate is preferred.
Examples of tri- or higher functional polyisocyanates include tri- or higher functional aromatic polyisocyanates and tri- or higher functional aliphatic polyisocyanates.
Trifunctional or higher polyisocyanates include adducts of aromatic or alicyclic diisocyanates and compounds having 3 or more active hydrogen groups in one molecule (e.g., trifunctional or higher polyols, polyamines, polythiols, etc.). Tri- or more functional polyisocyanate (adduct type tri- or more functional polyisocyanate) that is a body (adduct), and trimers of aromatic or alicyclic diisocyanates (biuret type or isocyanurate type) are also preferable, Polyisocyanate having a functionality of 3 or more, which is the above-mentioned adduct (adduct), is more preferable.

As the trifunctional or higher polyisocyanate which is the adduct, a trifunctional or higher polyisocyanate which is an adduct of an aromatic or alicyclic diisocyanate and a polyol having 3 or more hydroxyl groups in one molecule is preferable, and aromatic More preferred is a trifunctional polyisocyanate which is an adduct of a polycyclic or alicyclic diisocyanate and a polyol having three hydroxyl groups in one molecule.
As the adduct, it is preferable to use an adduct obtained by using an aromatic diisocyanate in that the pressure distribution can be measured more satisfactorily in a high-temperature environment.
As the polyol, for example, a trifunctional or higher low-molecular-weight polyol, which will be described later, is preferable, and trimethylolpropane is more preferable.

Examples of the adduct-type trifunctional or higher polyisocyanate include Takenate (registered trademark) D-102, D-103, D-103H, D-103M2, P49-75S, D-110N, D-120N, D- 140N, D-160N (manufactured by Mitsui Chemicals, Inc.), Desmodur (registered trademark) L75, UL57SP (manufactured by Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HL, HX, L (manufactured by Nippon Polyurethane Co., Ltd.), P301-75E (manufactured by Asahi Kasei Corporation) and Barnock (registered trademark) D-750 (manufactured by DIC Corporation) can be mentioned.
Among them, as the adduct type trifunctional or higher polyisocyanate, Takenate (registered trademark) D-110N, D-120N, D-140N, D-160N (manufactured by Mitsui Chemicals, Inc.), or DIC Corporation Barnock® D-750 is preferred.
Examples of the isocyanurate-type trifunctional or higher polyisocyanate include Takenate (registered trademark) D-127N, D-170N, D-170HN, D-172N, D-177N, and D-204 (manufactured by Mitsui Chemicals, Inc.). , Sumidule N3300, Desmodur (registered trademark) N3600, N3900, Z4470BA (Sumika Bayer Urethane), Coronate (registered trademark) HX, HK (manufactured by Nippon Polyurethane Co., Ltd.), Duranate (registered trademark) TPA-100, TKA- 100, TSA-100, TSS-100, TLA-100, TSE-100 (manufactured by Asahi Kasei Corporation).
Examples of biuret-type tri- or more functional polyisocyanates include Takenate (registered trademark) D-165N, NP1100 (manufactured by Mitsui Chemicals, Inc.), Desmodur (registered trademark) N3200 (Sumika Bayer Urethane), and Duranate (registered trademark). ) 24A-100 (manufactured by Asahi Kasei Corporation).

Polymethylene polyphenyl polyisocyanate is also preferred as the polyisocyanate.
Polymethylene polyphenyl polyisocyanate is preferably a compound represented by formula (X).

In formula (1), n represents the number of repeating units. The number of repeating units represents an integer of 1 or more, and n is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, in that the pressure distribution can be better measured in a high temperature environment.

Examples of polyisocyanates containing polymethylene polyphenyl polyisocyanate include Millionate MR-100, Millionate MR-200, Millionate MR-400 (manufactured by Tosoh Corporation), WANNATE PM-200, WANNATE PM-400 (Wanhua Japan Co., Ltd. company), Cosmonate M-50, Cosmonate M-100, Cosmonate M-200, Cosmonate M-300 (manufactured by Mitsui Chemicals, Inc.), and Boranate M-595 (manufactured by Dow Chemical Co., Ltd.). be done.

A polyol is a compound having two or more hydroxyl groups. Examples include oil-based polyols, polyolefin-based polyols, and hydroxyl group-containing amine-based compounds.
In addition, the low-molecular-weight polyol means a polyol having a molecular weight of 400 or less. Tri- or higher functional low-molecular-weight polyols such as erythritol and sorbitol.

Examples of hydroxyl group-containing amine compounds include aminoalcohols such as oxyalkylated derivatives of amino compounds. Examples of amino alcohols include N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine and N,N,N', which are propylene oxide or ethylene oxide adducts of amino compounds such as ethylenediamine. , N′-tetrakis[2-hydroxyethyl]ethylenediamine and the like.

Polyamines are compounds having two or more amino groups (primary amino groups or secondary amino groups), and fatty acids such as diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, and hexamethylenediamine. Epoxy compound adducts of aliphatic polyamines; Alicyclic polyamines such as piperazine; 3,9-bis-aminopropyl-2,4,8,10-tetraoxaspiro-(5, 5) heterocyclic diamines such as undecane;

Among them, the resin contained in the capsule wall is trifunctional or higher polyisocyanate A (hereinafter simply referred to as Also referred to as "polyisocyanate A"), and polyisocyanate B selected from the group consisting of aromatic diisocyanates and polymethylene polyphenyl polyisocyanates (hereinafter also simply referred to as "polyisocyanate B"). preferably.
That is, the capsule wall is a capsule wall containing the resin (at least one resin selected from the group consisting of polyurea, polyurethaneurea, and polyurethane) formed using the polyisocyanate A and the polyisocyanate B. Preferably.
By using the above polyisocyanate A and polyisocyanate B, the effects of the present invention are more excellent. In addition, the temperature dependence of color development is small. The temperature dependence of color development is a characteristic that indicates the degree of color development depending on the temperature when pressure is applied to the pressure measurement sheet set (or the pressure measurement sheet described later). More specifically, when observing the degree of color development by changing the heating temperature in the range of high temperature conditions (180 ° C. or higher) using a pressure measurement sheet set (or a pressure measurement sheet described later), color development When the difference in degree is large, it is said that the temperature dependence of color development is large.
As the polyisocyanate B, an aromatic diisocyanate may be used alone, a polymethylene polyphenyl polyisocyanate may be used alone, or both may be mixed and used. Among them, polyisocyanate B is preferably a mixture of aromatic diisocyanate and polymethylene polyphenyl polyisocyanate.
In the above mixture, the mass ratio of polymethylene polyphenyl polyisocyanate to aromatic diisocyanate (mass of polymethylene polyphenyl polyisocyanate/mass of aromatic diisocyanate) is not particularly limited, but is preferably 0.1 to 10, and 0 0.5 to 2 is more preferred, and 0.75 to 1.5 is even more preferred.

Although the viscosity of polyisocyanate B is not particularly limited, it is preferably 100 to 1000 mPa·s from the viewpoint that the pressure distribution can be better measured in a high temperature environment.
In addition, the said viscosity is a viscosity in 25 degreeC.

When polyisocyanate A and polyisocyanate B are used in combination, the mass ratio of polyisocyanate A to polyisocyanate B (mass of polyisocyanate A/mass of polyisocyanate B) is not particularly limited, but is 98/2 to 20/80. is preferred, 80/20 to 20/80 is more preferred, and 80/20 to 45/55 is even more preferred.
When the mass ratio is within the above range, the pressure distribution can be measured more satisfactorily in a high-temperature environment. In addition, the temperature dependence of color development is small.

The glass transition temperature of the capsule wall of the microcapsules is preferably 150° C. or higher, or the capsule wall does not exhibit the glass transition temperature. That is, it is preferable that the glass transition temperature of the material constituting the capsule wall of the microcapsules is 150° C. or higher, or that the material constituting the capsule walls of the microcapsules does not exhibit a glass transition temperature.
When the capsule wall of the microcapsules exhibits a glass transition temperature, the temperature is preferably 180° C. or higher, more preferably 200° C. or higher, from the viewpoint that the pressure distribution can be better measured in a high-temperature environment. When the capsule wall of the microcapsule exhibits a glass transition temperature, the upper limit of the temperature is not particularly limited, but it is often below the thermal decomposition temperature of the capsule wall of the microcapsule, generally 250 ° C. or less. many.
Above all, it is preferable that the capsule walls of the microcapsules do not exhibit a glass transition temperature in that the measurement of pressure distribution in a high-temperature environment can be performed more satisfactorily.

In addition, the capsule wall of the microcapsule does not exhibit a glass transition temperature means that the capsule wall of the microcapsule reaches a temperature obtained by subtracting 5 ° C. from the thermal decomposition temperature of the capsule wall described later (thermal decomposition temperature -5 ° C.) from 25 ° C. It means that (the material that constitutes the capsule wall of the microcapsules) does not exhibit a glass transition temperature. That is, it means that it does not show a glass transition temperature in the range from "25°C" to "(thermal decomposition temperature (°C) -5°C)".
The glass transition temperature of the capsule wall of the microcapsules is 150 ° C. or higher, or the method for making the capsule walls not exhibit the glass transition temperature is not particularly limited, and the raw materials for producing the microcapsules are appropriately selected. can be adjusted accordingly. For example, since polyurea has the property of exhibiting a high glass transition temperature, there is a method of forming the capsule wall with polyurea. Also included is a method of increasing the crosslink density in the material that constitutes the capsule wall. Furthermore, a method of introducing an aromatic ring group (for example, a benzene ring group) into the material constituting the capsule wall is also included.

Fifty first sheets of 1 cm long×1 cm wide are prepared, all of which are immersed in 10 ml of water and allowed to stand for 24 hours.
The resulting aqueous dispersion of microcapsules is centrifuged at 15000 rpm for 30 minutes to separate the microcapsules. Ethyl acetate is added to the separated microcapsules and further stirred at 25° C. for 24 hours. After that, the obtained solution is filtered, and the obtained residue is vacuum-dried at 60° C. for 48 hours to obtain microcapsules containing nothing inside (hereinafter also simply referred to as “measurement material”). be done. That is, the capsule wall material of the microcapsules whose glass transition temperature is to be measured is obtained.
Next, using a thermogravimetric differential thermal analyzer TG-DTA (apparatus name: DTG-60, Shimadzu Corporation), the thermal decomposition temperature of the obtained measurement material is measured. In addition, the thermal decomposition temperature is the temperature of the measurement material heated from room temperature at a constant heating rate (10 ° C./min) in atmospheric thermogravimetric analysis (TGA), and the mass of the measurement material before heating is The temperature at which the weight is reduced by 5% by mass is defined as the thermal decomposition temperature.
Next, the glass transition temperature of the material to be measured was measured using a differential scanning calorimeter DSC (device name: DSC-60a Plus, Shimadzu Corporation) using a closed pan at a heating rate of 5°C/min to 25°C. °C to (thermal decomposition temperature -5°C). As the glass transition temperature of the capsule wall of the microcapsules, the value at the time of heating in the second cycle is used.

The particle size of the microcapsules is not particularly limited, but the volume-based median diameter (D50) is preferably 1 to 80 μm, more preferably 5 to 70 μm, and even more preferably 10 to 50 μm.
The volume-based median diameter of microcapsules can be controlled by adjusting microcapsule production conditions and the like.
Here, the volume-based median diameter of the microcapsules is the volume of the particles on the large diameter side and the small diameter side when the total volume of the microcapsules is divided into two by the threshold value of the particle diameter at which the total volume is 50%. It means the diameter that the total is equivalent. That is, the median diameter corresponds to so-called D50.
A value calculated by photographing the surface of the first layer of the first sheet having the first layer containing microcapsules at 1000 times with an optical microscope and measuring the size of all microcapsules in the range of 500 μm × 500 μm is.

The number average wall thickness of the capsule wall of the microcapsules is not particularly limited, but is preferably 0.01 to 2 μm, more preferably 0.05 to 1 μm.
Incidentally, the wall thickness of the microcapsule refers to the thickness (μm) of the capsule wall forming the capsule particles of the microcapsules, and the number average wall thickness is the thickness (μm) of the individual capsule walls of the 20 microcapsules. is obtained by scanning electron microscope (SEM) and averaged. More specifically, a cross-sectional slice of the first sheet having the first layer containing microcapsules is prepared, and the cross section is observed with a SEM at a magnification of 15000. After selecting any 20 microcapsules having a particle size in the range of 0.9 to (volume-based median diameter value of microcapsules) × 1.1, the cross section of each selected microcapsule is observed. Then, the thickness of the capsule wall is obtained and the average value is calculated.

The ratio (δ/Dm) of the number average wall thickness δ of the microcapsules to the volume-based median diameter (Dm) of the microcapsules is not particularly limited, and is often 0.005 or more. Among others, it is preferable to satisfy the relationship of formula (1) in that the pressure distribution can be measured more satisfactorily in a high-temperature environment.
Formula (1) δ/Dm>0.010
That is, the ratio (δ/Dm) is preferably greater than 0.010. Moreover, the ratio (δ/Dm) is preferably 0.015 or more. Although the upper limit is not particularly limited, it is preferably 0.050 or less.
When the microcapsules satisfy the relationship of the above formula (1), the capsule size and the thickness of the capsule wall are well balanced, and there is less concern about leakage of the contents of the microcapsules in a high-temperature environment.

A coloring agent is included in the microcapsules.
A color former is a compound that develops color from a colorless state by contact with a color developer described below. As the color former, an electron-donating dye precursor (precursor of a dye that develops color) is preferred. In other words, an electron-donating colorless dye is preferable as the color former.
As the color former, those known in the application of pressure-sensitive copying paper or thermal recording paper can be used. Examples of color formers include triphenylmethanephthalide-based compounds, fluoran-based compounds, phenothiazine-based compounds, indolylphthalide-based compounds, azaindolylphthalide-based compounds, leuco auramine-based compounds, rhodamine lactam-based compounds, and triphenylmethanephthalide-based compounds. Examples include phenylmethane compounds, diphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds.
For details of the above compounds, reference can be made to the description of Japanese Patent Application Laid-Open No. 5-257272.
The coloring agent may be used singly or in combination of two or more.

The molecular weight of the coloring agent is not particularly limited, and is often 300 or more. Among them, 420 or more is preferable, and 550 or more is more preferable, in that the pressure distribution can be measured more satisfactorily in a high-temperature environment. Although the upper limit is not particularly limited, 1000 or less is preferable.

The molar absorption coefficient of the dye obtained by contacting the color former and the developer described later (corresponding to the colored dye) (hereinafter also simply referred to as "specific dye") is not particularly limited, but is 10000 mol ^-1 cm. ⁻¹ ·L or more is preferable, 15000 mol ⁻¹ ·cm ⁻¹ ·L or more is more preferable, and 25000 mol ⁻¹ ·cm ⁻¹ ·L or more is even more preferable. Although the upper limit of the molar extinction coefficient (ε) is not particularly limited, it is often 50000 mol ⁻¹ ·cm ⁻¹ ·L or less.

Preferred examples of color formers 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), 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 (ε=16000) and 2-anilino-6-diethylamino-3-methylfluorane (ε=16000), 3′,6′-bis(diethylamino)-2-(4-nitrophenyl) Spiro[isoindole-1,9′-xanthene]-3-one, 6′-(diethylamino)-1′,3′-dimethylfluorane, 3,3-bis(2-methyl-1-octyl-3- indolyl) phthalide and the like.
The above ε represents the molar extinction coefficient of each compound after color development.

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

[Other ingredients]
The microcapsules may enclose components other than the coloring agent described above.
For example, microcapsules preferably enclose a solvent.
The solvent is not particularly limited, and examples thereof include alkylnaphthalene compounds such as diisopropylnaphthalene, diarylalkane compounds such as 1-phenyl-1-xylylethane, alkylbiphenyl compounds such as isopropylbiphenyl, triarylmethane compounds, and alkylbenzene compounds. , aromatic hydrocarbons such as benzylnaphthalene compounds, diarylalkylene compounds, and arylindane compounds; dibutyl phthalate, and aliphatic hydrocarbons such as isoparaffin, soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, Examples include natural animal and vegetable oils such as coconut oil, castor oil, and fish oil, and natural high-boiling fractions such as mineral oil.
You may use a solvent individually by 1 type or in mixture of 2 or more types.

When the solvent is encapsulated in the microcapsules, the mass ratio of the solvent and the color former (mass of the solvent/mass of the color former) is preferably in the range of 98/2 to 30/70 from the viewpoint of color development. A range of 97/3 to 40/60 is more preferred.

In addition to the components described above, the microcapsules may optionally contain one or more additives such as ultraviolet absorbers, light stabilizers, antioxidants, waxes, and odor inhibitors.

[Method for producing microcapsules]
The method for producing microcapsules encapsulating a color former is not particularly limited, and examples thereof include known methods such as interfacial polymerization, internal polymerization, phase separation, external polymerization, and coacervation. Among them, the interfacial polymerization method is preferable.
As the interfacial polymerization method, a raw material containing a color former and a capsule wall material (for example, polyisocyanate and at least one selected from the group consisting of polyols and polyamines) is used. Polyols and polyamines may not be used when manufacturing in the capsule wall material), dispersing the oil phase containing in an aqueous phase containing an emulsifier to prepare an emulsion (emulsification step) An interfacial polymerization method including a step of polymerizing at the interface between an oil phase and an aqueous phase to form a capsule wall and forming a microcapsule encapsulating a color former (encapsulation step) is preferred.
The mass ratio of the total amount of polyol and polyamine to the amount of polyisocyanate (total amount of polyol and polyamine/amount of polyisocyanate) in the raw material is not particularly limited, but is from 0.1/99.9. 30/70 is preferred, and 1/99 to 25/75 is more preferred.
As described above, the polyisocyanate A and the polyisocyanate B may be used in combination as the polyisocyanate. When both are used together, the preferred range of the mixing ratio of both is as described above.

Also, the type of emulsifier used in the emulsification step is not particularly limited, and examples thereof include dispersants and surfactants.
Dispersants include, for example, polyvinyl alcohol.

The first layer contains microcapsules as described above.
Although the content of the microcapsules in the first layer is not particularly limited, it is preferably 50 to 90% by mass with respect to the total mass of the first layer in that the measurement of pressure distribution in a high temperature environment can be performed better. , more preferably 55 to 85% by mass, even more preferably 55 to 80% by mass.
The content of the coloring agent in the first layer is not particularly limited, but is preferably 0.1 to 10 g/m 2 , and 0.1 g/m ² in terms of better measurement of pressure distribution in a high-temperature environment. ~4 g/ ^m2 is more preferred.

The first layer may contain components other than the microcapsules described above.
Other ingredients include, for example, polymeric binders, inorganic fillers (eg, colloidal silica), optical brighteners, defoamers, penetrants, UV absorbers, surfactants, and preservatives.
Polymer binders include, for example, styrene-butadiene copolymer, polyvinyl acetate, polyacrylate, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymer, starch, casein, gum arabic, gelatin, carboxy Synthetic polymers or natural polymers such as methyl cellulose or salts thereof, methyl cellulose, polyolefins, and modified acrylic acid ester copolymers can be mentioned. The viscosity of the composition for forming the first layer can also be adjusted by adding a polymer binder. A polymer binder may be used individually by 1 type, and may be used in combination of 2 or more types.
Although the content of the polymer binder is not particularly limited, it is preferably 0 to 50% by mass with respect to the total mass of the first layer from the viewpoint that the effect of the present invention is more excellent. 0.1 to 20% by mass is preferable, and 0.2 to 10% by mass is more preferable in that it is suitable for a low pressure range of 20 MPa or less.
Examples of surfactants include anionic surfactants, nonionic surfactants, and cationic surfactants. From the viewpoint of maintaining the dispersibility of microcapsules, anionic surfactants, or Nonionic surfactants are preferred.
Examples of surfactants include fluorine-based surfactants, silicone-based surfactants, and hydrocarbon-based surfactants. Activators are preferred.
Although the content of the surfactant is not particularly limited, it is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of the first layer, in terms of better effects of the present invention. preferable.
The inorganic filler is preferably introduced in order to make it easier to separate the first sheet and the second sheet after heating and pressure measurement. Silica particles and alumina particles are preferable as the inorganic filler in that the first sheet and the second sheet can be easily peeled off. The median diameter of the inorganic filler is preferably 0.001 to 1 μm, more preferably 0.005 to 0.1 μm, even more preferably 0.005 to 0.05 μm. The content of the inorganic filler is preferably 1 to 50% by mass, preferably 3 to 30% by mass, more preferably 5 to 20% by mass, relative to the total mass of the first layer.

Although the thickness of the first layer is not particularly limited, it is preferably 0.01 to 5 μm, more preferably 0.02 to 3 μm, because it is suitable for a low pressure range of 20 MPa or less. Here, the thickness of the first layer means the thickness excluding microcapsules exposed from the layer surface when the microcapsule diameter is larger than the layer thickness. When the thickness of the first layer is within the above range, aggregation of the microcapsules can be suppressed during drying after application of the composition for forming the first layer containing microcapsules, and the capsules can be formed at a desired pressure. Adjustable to break. The thickness of the first layer is preferably 50% or less, more preferably 25% or less, of the median diameter of the microcapsules in terms of being suitable for a low pressure range of 20 MPa or less. As the thickness of the first layer is thinner than the microcapsules, the microcapsules are more likely to be broken, so it can be adjusted according to the pressure zone to be measured.
Also, the mass (g/m ² ) per unit area of the first layer is not particularly limited, but is preferably 0.5 to 20 g/m ² .

[Method of Forming First Layer]
A method for forming the first layer is not particularly limited, and includes known methods.
For example, there is a method of applying a first layer-forming composition containing microcapsules onto a first support and, if necessary, performing a drying treatment.
The composition for forming the first layer preferably contains at least microcapsules and a solvent. The microcapsule dispersion liquid obtained by the interfacial polymerization method described above may be used as the composition for forming the first layer.
The composition for forming the first layer may contain other components that may be contained in the first layer described above.

The method of applying the composition for forming the first layer is not particularly limited, and the coating machine used for application includes, for example, an air knife coater, a rod coater, a bar coater, a curtain coater, a gravure coater, and an extrusion coater. , die coaters, slide bead coaters, and blade coaters.

After applying the composition for forming the first layer onto the first support, the coating film may be subjected to a drying treatment, if necessary. The drying treatment includes heat treatment.

(Other members)
The first sheet may have members other than the above-described first support and first layer.
For example, the first sheet may have an adhesion layer between the first support and the first layer for enhancing adhesion between the two.
The adhesion layer preferably contains a resin from the viewpoint of adhesion. As the resin, for example, a layer containing a resin formed from a urethane polymer or a blocked isocyanate may be used. In addition, layers containing gelatin, styrene/butadiene rubber, cellulose analogues, and polystyrene may be used.
From the viewpoint of heat resistance, the adhesion layer preferably contains a polymer having an aromatic group. Moreover, from the viewpoint of heat resistance, non-radical polymers are preferable, and examples thereof include polyester, polyurethane, polyamide, phenol resin, urea resin, etc., and aromatic polyester and aromatic polyurethane are more preferable.
The content of the polymer having an aromatic group is preferably 30% by mass or more, more preferably 50% by mass or more, relative to the total mass of the adhesion layer. Although the upper limit is not particularly limited, it is, for example, 100% by mass.
The thickness of the adhesion layer is not particularly limited, and is preferably 0.005 to 2 μm, more preferably 0.01 to 1 μm.

<Second sheet>
The second sheet 22 shown in FIG. 1 has a second support 18 and a second layer 20 comprising a developer disposed on the second support 18 .

When the second sheet 22 is heated at 220° C. for 10 minutes, both the shrinkage rate S1 in the longitudinal direction of the second sheet 22 and the shrinkage rate S2 in the width direction orthogonal to the longitudinal direction of the second sheet 22 are -0.5 to 2.0%.
The preferred ranges of the shrinkage rate S1, the shrinkage rate S2, and the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the second sheet 22 are the shrinkage rate S1, the shrinkage rate S2, and the shrinkage rate S2 in the first sheet 16, respectively. It is the same as the absolute value of the difference between the rate S1 and the shrinkage rate S2.

The method of measuring the shrinkage rate S1 and the shrinkage rate S2 of the second sheet 22 is the same as the method of measuring the shrinkage rate S1 and the shrinkage rate S2 of the first sheet 16 except that the second sheet 22 is used instead of the first sheet 16. is.
The definition of the longitudinal direction and the width direction of the second sheet 22 is the same as the definition of the longitudinal direction and the width direction of the first sheet 16 except that the first sheet 16 is read as the second sheet 22 .
The second sheet 22 may be a sheet (single sheet) or may be elongated.
Below, each member is explained in full detail.

(Second support)
The second support is a member for supporting the second layer.
Since the mode of the second support is the same as the mode of the first support described above, the description is omitted.

(Second layer)
The second layer is a layer containing a developer.
A color developer is a compound that does not have a color-developing function by itself, but has the property of causing the color-developing agent to develop color upon contact with the color-developing agent. Electron-accepting compounds are preferred as color developers.
Developers include inorganic and organic compounds.
Examples of inorganic compounds include clay substances such as acid clay, activated clay, attapulgite, zeolite, bentonite, and kaolin. When introducing an inorganic compound into the second layer, it is preferable to use a dispersant for dispersing the inorganic compound. The dispersant is appropriately selected depending on the surface physical properties of the inorganic compound. For example, anionic hexametaphosphoric acid and its salts are used for acid-treated activated clay.
Examples of organic compounds include metal salts of aromatic carboxylic acids, phenol formaldehyde resins, and metal salts of carboxylated terpene phenol resins.

Metal salts of aromatic carboxylic acids 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-(α,α-dimethylbenzyl)salicylic acid, carboxy modified Zinc, nickel, aluminum or calcium salts of terpene phenolic resins, salicylic acid resins which are reaction products of 3,5-bis(α-methylbenzyl)salicylic acid and benzyl chloride are preferred.

Among them, the developer is preferably a clay substance, a metal salt of an aromatic carboxylic acid, or a metal salt of a carboxylated terpene phenolic resin, more preferably a clay substance or a metal salt of an aromatic carboxylic acid. Substances are more preferred, acid clay, activated clay or kaolin being particularly preferred.
In particular, when a clay material is used as a color developer, the clay material is less likely to discolor when pressure is measured in a high-temperature environment, so the pressure distribution sheet set for pressure measurement is excellent in display quality.

The content of the color developer in the second layer is not particularly limited, but from the point of view of better measurement of pressure distribution in a high temperature environment, it is 20 to 95% by mass based on the total mass of the second layer. Preferably, 30 to 90% by mass is more preferable.

Although the content of the developer in the second layer is not particularly limited, it is preferably 0.1 to 30 g/m ² . When the developer is an inorganic compound, the content of the developer is preferably 3 to 20 g/m ² , more preferably 5 to 15 g/m ² . When the developer is an organic compound, the content of the developer is preferably 0.1 to 5 g/m ² , more preferably 0.2 to 3 g/m ² .

The second layer may contain components other than the developer described above.
Other ingredients include, for example, polymeric binders, pigments, optical brighteners, defoamers, penetrants, UV absorbers, surfactants, and preservatives.
Polymer binders include, for example, styrene-butadiene copolymer, polyvinyl acetate, polyacrylate, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymer, starch, casein, gum arabic, gelatin, carboxy Synthetic polymers such as methyl cellulose, polyolefins, modified acrylic acid ester copolymers, and methyl cellulose or natural polymers can be mentioned. A polymer binder may be used individually by 1 type, and may be used in combination of 2 or more types.
Although the content of the polymer binder is not particularly limited, it is preferably 0.1 to 80% by mass, more preferably 1 to 50% by mass, based on the total mass of the second layer, from the viewpoint that the effects of the present invention are more excellent.
Examples of pigments include heavy calcium carbonate, light calcium carbonate, talc, and titanium dioxide.
Examples of the surfactant include the same aspects as the surfactant contained in the first layer described above, and preferred aspects are also the same.

Although the thickness of the second layer is not particularly limited, it is preferably 1 to 50 μm, more preferably 2 to 30 μm, from the viewpoint of better measurement of pressure distribution in a high-temperature environment.
Also, the mass (g/m ² ) per unit area of the second layer is not particularly limited, but is preferably 0.5 to 20 g/m ² .

[Method for Forming Second Layer]
A method for forming the second layer is not particularly limited, and includes known methods.
For example, there is a method in which a composition for forming a second layer containing a color developer is applied onto the second support and, if necessary, a drying treatment is performed.
The composition for forming the second layer may be a dispersion liquid in which a color developer is dispersed in water or the like. When the developer is an inorganic compound, the dispersion containing the developer can be prepared by mechanically dispersing the inorganic compound in water. When the developer is an organic compound, it can be prepared by mechanically dispersing the organic compound in water or dissolving it in an organic solvent.
The composition for forming the second layer may contain other components that may be contained in the second layer described above.

The method of applying the composition for forming the second layer is not particularly limited, and a method using a coating machine used for applying the composition for forming the first layer described above may be used.

After applying the composition for forming the second layer onto the second support, the coating film may be subjected to a drying treatment, if necessary. The drying treatment includes heat treatment.

Although the method for forming the second layer on the second support has been described above, it is not limited to the above-described mode, and for example, after forming the second layer on the temporary support, the temporary support is peeled off. to form a second sheet comprising a second layer.
The temporary support is not particularly limited as long as it is a peelable support.

(Other members)
The second sheet may have members other than the above-described second support and second layer.
For example, the second sheet may have an adhesion layer between the second support and the second layer for enhancing adhesion between the two.
Examples of the form of the adhesion layer include the form of the adhesion layer that the first sheet described above may have.

<<Second Embodiment>>
FIG. 2 is a cross-sectional view of one embodiment of a pressure-measuring sheet.
The pressure measurement sheet 30 comprises a support 32, a second layer 20 containing a developer, and a first layer 14 containing predetermined microcapsules 13 in this order. That is, the support 32 is arranged on the side of the second layer 20 opposite to the first layer 14 .
When the pressure measurement sheet 30 is used, pressure is applied from at least one of the support 32 side and the first layer 14 side, so that the microcapsules 13 are broken in the pressurized area and encapsulated in the microcapsules 13. The color former comes out of the microcapsules 13 and undergoes a color reaction with the color developer in the second layer 20 . As a result, color development progresses in the pressurized area.

In FIG. 3, the support 32 and the second layer 20 are directly laminated, but the present invention is not limited to this embodiment. (for example, an adhesion layer) may be arranged.
In addition, although FIG. 3 discloses the pressure measurement sheet 30 having the support 32, the second layer 20, and the first layer 14 in this order, the support 32 is not limited to this embodiment. , the first layer 14 and the second layer 20 in this order. That is, the support 32 may be arranged on the side of the first layer 14 opposite to the second layer 20 . When the support 32 is arranged on the side of the first layer 14 opposite to the second layer 20, another layer (for example, an adhesion layer) is arranged between the support 32 and the first layer 14. may have been

The first layer 14 and the second layer 20 in the pressure measurement sheet 30 are the same members as the first layer 14 and the second layer 20 described in the above-described first embodiment, so description thereof will be omitted.

When the pressure measurement sheet 30 is heated at 220° C. for 10 minutes, the contraction rate S1 in the longitudinal direction of the pressure measurement sheet 30 and the contraction rate S2 in the width direction orthogonal to the longitudinal direction of the pressure measurement sheet 30 are Both are -0.5 to 2.0%.
The shrinkage ratio S1 of the pressure measurement sheet 30 is -0.5 to 2.0%, and from the point of being able to measure a more precise pressure distribution, it is preferably -0.4 to 1.5%, and -0.3. ~1.2% is more preferred, and -0.2 to 0.8% is even more preferred.
The shrinkage ratio S2 of the pressure measurement sheet 30 is -0.5 to 2.0%, and from the point of being able to measure a more precise pressure distribution, it is preferably -0.4 to 1.5%, and -0.3. ~1.2% is more preferred, and -0.2 to 0.8% is even more preferred.

The method for measuring the shrinkage rate S1 and the shrinkage rate S2 of the pressure measurement sheet 30 is the same as the method for measuring the shrinkage rate S1 and the shrinkage rate S2 of the first sheet 16 except that the pressure measurement sheet 30 is used instead of the first sheet 16. is the same as
The definitions of the longitudinal direction and width direction of the pressure measurement sheet 30 are the same as those of the first sheet 16 except that the first sheet 16 is read as the pressure measurement sheet 30 .

In the pressure measurement sheet 30, the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 (|S1-S2|) is preferably 0 to 0.8%, and 0 ~0.6% is more preferred, and 0 to 0.4% is even more preferred.

The pressure measurement sheet 30 may be a sheet (single sheet) or may be elongated.

Below, mainly the support 32 will be described in detail.

(support)
A support is a member for supporting the first layer and the second layer.
The preferred mode of the support is the same as the preferred mode of the first support described above, so the description is omitted.

(Manufacturing method of sheet for pressure measurement)
The method of manufacturing the pressure measurement sheet is not particularly limited, and known methods can be used.
For example, a composition for forming a second layer containing a color developer is applied onto a support, and if necessary, dried to form a second layer on the support, and then microcapsules are added. A first layer forming composition containing the second layer is applied onto the second layer, and if necessary, a drying treatment is performed to form the first layer.
The method for forming the first layer using the composition for forming the first layer is as described in the first embodiment. The method for forming the second layer using the composition for forming the second layer is also the same as described in the first embodiment.

(Other members)
The pressure measurement sheet may contain members other than the support, the second layer and the first layer.
For example, when the second layer has a support on the side opposite to the first layer, the pressure-measuring sheet has an adhesion layer between the support and the second layer to increase adhesion between the two. may have.
When the first layer has a support on the side opposite to the second layer, the pressure-measuring sheet has an adhesion layer between the support and the first layer to increase the adhesion between the two. may have.
Examples of the form of the adhesion layer include the form of the adhesion layer that the first sheet described above may have.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. The present invention is not limited to the following examples as long as it does not exceed the scope of the present invention.

<Example 1>
(Preparation of microcapsules)
The following compound (A) (molecular weight: 623) (7.4 parts by mass), which is a coloring agent, is dissolved in straight-chain alkylbenzene (JX Nippon Oil & Energy Corporation, grade alkene L) (56 parts by mass), and solution A is prepared. Obtained. Next, synthetic isoparaffin (IP Solvent 1620, Idemitsu Kosan Co., Ltd.) (15 parts by mass) was added to the stirred solution A to obtain a solution B. Furthermore, a trimethylolpropane adduct of tolylene diisocyanate dissolved in 2-butanone (5.4 parts by mass) (DIC Corporation, Barnock D-750) (7.5 parts by mass) and 2-butanone (2.4 parts by mass) Parts by mass) of polymethylene polyphenyl polyisocyanate (Tosoh Corporation, Millionate MR-200) (1.9 parts by mass) was added to the stirred solution B to obtain a solution C.
Then, the above solution C was added to a solution of polyvinyl alcohol (PVA-217E, Kuraray Co., Ltd.) (8.5 parts by mass) dissolved in water (140 parts by mass) for emulsification and dispersion. Water (230 parts by mass) was added to the emulsion after emulsification and dispersion, and the mixture was heated to 70° C. with stirring, stirred for 1 hour, and then cooled. Furthermore, water was added to adjust the concentration to obtain a microcapsule liquid containing a color former with a solid content concentration of 19.6% by mass.

Also, the above Barnock D-750 corresponds to a trifunctional polyisocyanate, which is an adduct of an aromatic diisocyanate and trimethylolpropane, as shown in the structural formula below.

The volume-based median diameter of the color former-encapsulating microcapsules was 14 μm. The number average wall thickness was 0.20 μm. Also, δ/Dm was 0.014. Furthermore, the capsule wall of the microcapsules did not exhibit a glass transition temperature in the range from "25°C" to "(thermal decomposition temperature (°C) -5°C)".

In addition, the median diameter (Dm), as described later, is obtained by producing a first sheet having a first layer containing microcapsules, photographing the surface of the first layer with an optical microscope at a magnification of 150, and measuring 500 μm × 500 μm. The size of all microcapsules in the range was measured and calculated.
As described later, the number average wall thickness is obtained by producing a first sheet having a first layer containing microcapsules, then producing a cross-sectional section of the first sheet having a first layer containing microcapsules, and measuring the cross section. Observed using SEM, (volume-based median diameter value of microcapsules) × 0.9 ~ (volume-based median diameter value of microcapsules) × 1.1 Any 20 having a particle size After selecting individual microcapsules, the cross section of each selected microcapsule was observed to determine the thickness of the capsule wall, and the average value was calculated.
Moreover, the glass transition temperature was measured by the following method.
First, as described later, after producing a first sheet having a first layer containing microcapsules, it was cut into 50 sheets of 1 cm long×1 cm wide, all of which were immersed in 10 ml of water and allowed to stand for 24 hours. The resulting aqueous dispersion of microcapsules was centrifuged at 15000 rpm for 30 minutes to separate the microcapsules. Ethyl acetate was added to the separated microcapsules and further stirred at 25° C. for 24 hours. After that, the obtained solution is filtered, and the obtained residue is vacuum-dried at 60° C. for 48 hours to obtain microcapsules containing nothing inside (hereinafter also simply referred to as “measurement material”). was taken. Next, using a thermogravimetric differential thermal analyzer TG-DTA (apparatus name: DTG-60, Shimadzu Corporation), the thermal decomposition temperature of the obtained measurement material was measured. As the thermal decomposition temperature, in thermogravimetric analysis (TGA) in an air atmosphere, the temperature of the measurement material is increased from room temperature at a constant temperature increase rate (10 ° C./min), and the mass of the measurement material before heating is The temperature at which the weight was reduced by 5% by mass was defined as the thermal decomposition temperature. Next, the glass transition temperature of the material to be measured was measured using a differential scanning calorimeter DSC (device name: DSC-60a Plus, Shimadzu Corporation) using a closed pan at a heating rate of 5°C/min to 25°C. °C to (thermal decomposition temperature -5°C). As the glass transition temperature of the capsule wall of the microcapsules, the value when the temperature was raised in the second cycle was used.

(Preparation of first sheet)
Color former-encapsulating microcapsule liquid (43 parts by mass), water (15 parts by mass), colloidal silica (Nissan Chemical Co., Ltd., Snowtex (registered trademark) 30) (4.3 parts by mass), carboxymethyl cellulose Na (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen 5A) 10% by mass aqueous solution (4.3 parts by mass), 1% by mass aqueous solution of carboxymethyl cellulose Na (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen EP) (10 parts by mass), alkylbenzene sulfone A 15% by mass aqueous solution (0.3 parts by mass) of sodium phosphate (Daiichi Kogyo Seiyaku Co., Ltd., Neogen T), and a 1% by mass aqueous solution (1.0 mass) of Neugen LP70 (Daiichi Kogyo Seiyaku Co., Ltd.) Part) was mixed and stirred for 2 hours to obtain a composition for forming the first layer.

The obtained composition for forming the first layer was placed on a polyethylene naphthalate sheet (Teijin Film Solution Co., Ltd., Teonex (registered trademark), Q83) having a thickness of 50 μm as a first support, and the mass after drying was It was applied by a bar coater so as to be 4.5 g/m ² and dried to form a first layer, thereby producing a first sheet.

(Production of second sheet)
Sulfuric acid-treated activated clay (200 parts by mass), sodium hexametaphosphate (1 part by mass), sodium hydroxide 10% by mass aqueous solution (30 parts by mass), and water (290 parts by mass), which are color developers, were mixed using a sand grinder. A dispersion liquid was prepared by dispersing the particles so that the average particle diameter of all the particles was 2 μm.
Next, to the prepared dispersion, Nippol LX-814 (Nippon Zeon Co., Ltd.) 19% by mass aqueous dispersion (180 parts by mass), Polymaron 482 (Arakawa Chemical Industries, Ltd.) 3.3% by mass aqueous solution ( 220 parts by mass), 1% by mass aqueous solution (80 parts by mass) of carboxymethyl cellulose Na (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen EP), 15 masses of sodium alkylbenzene sulfonate (Daiichi Kogyo Seiyaku Co., Ltd., Neogen T) % aqueous solution (4.7 parts by mass) and a 1% by mass aqueous solution (70 parts by mass) of Noigen LP70 (Daiichi Kogyo Seiyaku Co., Ltd.) were mixed to prepare a coating liquid containing a developer.
A coating liquid containing a developer was applied onto a polyethylene naphthalate sheet (Teijin Film Solution Co., Ltd., Teonex (registered trademark), Q83) having a thickness of 50 μm as a second support so that the solid content coating amount was 12.0 g/. It was applied to a thickness of m ² and dried to form a second layer to obtain a second sheet.

<Example 2>
(Preparation of microcapsules)
A solution A was obtained by dissolving the compound (A) (molecular weight: 623) (6.8 parts by mass), which is a coloring agent, in straight-chain alkylbenzene (JX Nippon Oil & Energy Corporation, grade alkene L) (52 parts by mass). rice field. Next, synthetic isoparaffin (IP Solvent 1620, Idemitsu Kosan Co., Ltd.) (14 parts by mass) was added to the stirred solution A to obtain a solution B. Furthermore, a trimethylolpropane adduct of tolylene diisocyanate dissolved in 2-butanone (7.8 parts by mass) (DIC Corporation, Barnock D-750) (10.8 parts by mass) and 2-butanone (3.5 parts by mass) Parts by mass) of polymethylene polyphenyl polyisocyanate (Tosoh Corporation, Millionate MR-200) (2.7 parts by mass) was added to the stirred solution B to obtain a solution C.
Then, the above solution C was added to a solution of polyvinyl alcohol (PVA-217E, Kuraray Co., Ltd.) (7.8 parts by mass) dissolved in water (130 parts by mass) to emulsify and disperse. Water (230 parts by mass) was added to the emulsion after emulsification and dispersion, and the mixture was heated to 70° C. with stirring, stirred for 1 hour, and then cooled. Furthermore, water was added to adjust the concentration to obtain a microcapsule liquid containing a color former with a solid content concentration of 19.6% by mass.
The volume-based median diameter of the color former-encapsulating microcapsules was 20 μm. The number average wall thickness was 0.44 μm. Also, δ/Dm was 0.022. Furthermore, the capsule wall of the microcapsules did not exhibit a glass transition temperature in the range from "25°C" to "(thermal decomposition temperature (°C) -5°C)".
A first sheet and a second sheet were produced in the same manner as in Example 1, except that the microcapsule liquid containing the coloring agent thus obtained was used.

<Example 3>
Zinc 3,5-di-α-methylbenzylsalicylate (10 parts by mass), calcium carbonate (100 parts by mass), sodium hexametaphosphate (1 part by mass), and water (200 parts by mass), which are color developers, A dispersion liquid was prepared by dispersing using a sand grinder so that the average particle size of all particles was 2 μm.
Next, the prepared dispersion was added with 10% aqueous solution (100 parts by mass) of polyvinyl alcohol (PVA-203, Kuraray Co., Ltd.), styrene-butadiene latex (10 parts by mass as solid content), and water (450 parts by mass). ) was added to prepare a coating solution containing a developer.
A first sheet and a second sheet were prepared in the same manner as in Example 2, except that the thus obtained coating liquid containing the color developer was used.

<Examples 4 and 5>
As the first support and the second support, a polyethylene naphthalate sheet with a thickness of 12 μm or a polyethylene naphthalate sheet with a thickness of 250 μm instead of a polyethylene naphthalate sheet with a thickness of 50 μm (Teijin Film Solution Co., Ltd., Teonex (registered trademark), Q83) A first sheet and a second sheet were produced according to the same procedure as in Example 2, except that the polyethylene naphthalate sheet of No. 2 was used.

<Comparative Example 1>
As the first support and the second support, a polyethylene terephthalate sheet with an adhesion layer having a thickness of 50 μm (Toyobo Co., Ltd.) was used instead of a polyethylene naphthalate sheet having a thickness of 50 μm (Teijin Film Solution Co., Ltd., Teonex (registered trademark), Q83). Co., Ltd., Cosmoshine (registered trademark) A4300) was used to prepare a first sheet and a second sheet according to the same procedure as in Example 2.

<Evaluation>
(shrinkage rate measurement)
The first sheet prepared in each example and comparative example was cut into a sample having a length of 150 mm in the longitudinal direction of the first sheet and a length of 20 mm in the width direction. I prepared 3 sheets.
Position A, about 25mm along the direction parallel to the long side, from the center point (starting point) of one short side of the sample toward the center point of the other short side, and the center point of the other short side of the sample A reference line was attached to each of position B, which is about 25 mm from the (starting point) toward the center point of one of the short sides along the direction parallel to the long side. At this time, the distance between position A and position B (distance between gauge lines) was 100 mm±2 mm.
This was used as a sample for measuring the shrinkage ratio S1 in the longitudinal direction of the first sheet.
After heating the obtained measurement sample at 220° C. for 10 minutes, the measurement sample was returned to room temperature (23° C.), the distance between the marked lines of the measurement sample was measured, and the shrinkage ratio S1a was calculated according to the following formula. Calculated.
Shrinkage rate S1a [%] = 100 × {(distance between marked lines in measurement sample before heating) - (distance between marked lines in measurement sample after heating)}/(standard in measurement sample before heating) distance between lines)
The arithmetic average value of the shrinkage ratios S1a of the three measurement samples was obtained, and this was defined as the shrinkage ratio S1. In addition, the distance between marked lines was measured to the unit of 0.1 mm.

In addition, the first sheet produced in each example and comparative example was cut so that the length in the direction along the width direction of the first sheet was 150 mm and the length in the direction along the longitudinal direction was 20 mm. Three samples were prepared. A marked line was drawn on the surface of each sample in the same manner as the sample for measurement of the shrinkage ratio S1.
This was used as a sample for measuring the shrinkage ratio S2 in the width direction of the first sheet.
After heating the obtained measurement sample at 220° C. for 10 minutes, the measurement sample was returned to room temperature (23° C.), the distance between the marked lines of the measurement sample was measured, and the shrinkage ratio S2a was calculated according to the following formula. Calculated.
Shrinkage rate S2a [%] = 100 × {(distance between marked lines in measurement sample before heating) - (distance between marked lines in measurement sample after heating)}/(standard in measurement sample before heating) distance between lines)
An arithmetic mean value of the shrinkage ratio S2a of the three measurement samples was obtained and used as the shrinkage ratio S2. In addition, the distance between marked lines was measured to the unit of 0.1 mm.

Method for measuring the shrinkage rate S1 and the shrinkage rate S2 of the first sheet, except that the second sheet prepared in each example and comparative example was used instead of the first sheet prepared in each example and comparative example. In the same manner as above, the shrinkage rate S1 and the shrinkage rate S2 of the second sheet were calculated.

(Pressure distribution measurement)
The first sheet and the second sheet produced in each example and comparative example were each cut into a size of 5 cm × 5 cm, and the first sheet and the second sheet were separated from the surface of the first layer of the first sheet and the second sheet. A laminate (sheet set) was obtained by stacking the sheets in contact with the surface of the second layer.
Next, a hot press machine having two heating stages arranged vertically is prepared, the heating stages are separated from each other, and a ring-shaped SUS (Steel Use Stainless) substrate with a width of 5 mm is placed on the lower stage. Then, the laminate was arranged so as to cover the SUS substrate. After that, the pressure was applied at 2.0 MPa for 10 minutes so as to sandwich the SUS substrate and the laminate between two heating stages heated to 220°C. After pressing, the shape of the colored region of the obtained laminate was observed and evaluated according to the following criteria.

"5": There was no unevenness in color development, and it was possible to recognize very well that the shape of the color development area was a ring shape similar to that of the SUS substrate.
"4": Although there was very little unevenness in color development, the shape of the color development region was well recognized as a ring shape similar to that of the SUS substrate.
"3": Although there was variation in color development, the shape of the color development region was fully recognizable as a ring shape.
"2": Due to unevenness and fineness of color development, there were portions where it was not possible to recognize that the shape of the color development region was ring-shaped.
"1": Color development was so uneven and dense that it was almost impossible to recognize that the shape of the color development region was ring-shaped.

Table 1 shows the evaluation results. In Table 1, PEN means polyethylene naphthalate and PET means polyethylene terephthalate.

As shown in Table 1, the shrinkage rate S1 and shrinkage rate S2 of the first sheet and the shrinkage rate S1 and shrinkage rate S2 of the second sheet are both in the range of -0.5 to 2.0%. When the laminate of the measurement sheet set is used (Examples 1 to 5), at least one of the shrinkage rate S1 and shrinkage rate S2 of the first sheet and the shrinkage rate S1 and shrinkage rate S2 of the second sheet It was confirmed that a precise pressure distribution can be measured as compared with the case of using a pressure measurement sheet set laminate having a shrinkage ratio outside the above range (Comparative Example 1).
Further, from the comparison between Examples 2 and 4, the difference in the absolute values of the shrinkage ratios S1 and S2 of the first sheet and the difference in the absolute values of the shrinkage ratios S1 and S2 of the second sheet are both , in the range of 0 to 0.8%.

The second sheets of Examples 2 and 3 were heated at 220° C. for 10 minutes, and the color of the second sheets was visually observed. The second sheet of No. 2 was discolored to a slightly yellowish color.
Furthermore, using the laminates of the pressure measurement sheet sets of Examples 2 and 3 containing the second sheet after heating, the pressure distribution measurement described above was carried out, and when the coloring region was visually observed, the coloring of Example 3 was observed. The area showed a yellowish tint. Thus, it was confirmed that the pressure measurement sheet set of Example 2 is superior to the pressure measurement sheet set of Example 3 in display quality when exposed to high temperatures.

The sheet sets for pressure measurement of Examples 1, 2 and 4 were evaluated in the same procedure as the pressure distribution measurement described above, except that the width of the ring-shaped SUS substrate was changed to 2 mm.
As a result, when using the pressure measurement sheet set laminate (Examples 1 and 2) in which the thickness of each of the first support and the second support is 25 μm or more, the thickness of the first support and the second support Compared to the case of using the pressure measurement sheet set laminate (Example 4) having a thickness of less than 25 μm, an unnatural increase in color density can be suppressed at the position corresponding to the edge of the SUS substrate ( That is, it was confirmed that uniform color development was achieved without color unevenness.

The sheet sets for pressure measurement of Examples 1, 2 and 5 were evaluated in the same procedure as the pressure distribution measurement described above, except that the width of the ring-shaped SUS substrate was changed to 10 mm.
As a result, when using the pressure measurement sheet set laminate (Examples 1 and 2) in which the thickness of each of the first support and the second support is 200 μm or less, the thickness of the first support and the second support Compared to the case of using the pressure measurement sheet set laminate (Example 5) having a thickness of more than 200 μm, at the position corresponding to the edge of the SUS substrate, an unnatural decrease in color density (i.e. , unnatural blurring of color development at the edges) can be suppressed.

<Example 6>
On one surface of a polyethylene naphthalate sheet (Teijin Film Solution Co., Ltd., Teonex (registered trademark), Q83) with a thickness of 50 μm, the adhesion layer forming composition A described later was applied with a bar coater and dried to a thickness of 0. An adhesion layer A having a thickness of 0.45 μm was formed. A first sheet was produced in the same manner as in Example 1, except that the polyethylene naphthalate sheet on which the adhesion layer A was formed was used as the first support. The first layer was formed on the surface of the adhesion layer. When the shrinkage rate of the first sheet prepared in Example 6 was measured in the same manner as in Example 1, the shrinkage rate of the first sheet prepared in Example 6 was 0.5% for S1 and 0 for S2. was 0.1%.

-Adhesion layer-forming composition A-
・ Styrene / butadiene copolymer latex (styrene: butadiene = 67: 30, product name: LX-407C5, Nippon Zeon Co., Ltd., solid content 40% by mass) 25.9 parts by mass ・ Polystyrene particles (product name: UFN1008 , Nippon Zeon Co., Ltd., average particle: 2 μm, solid content 20% by mass) 0.3 parts by mass Methyl methacrylate / styrene / 2-ethoxyhexyl acrylate / 2-hydroxyethyl methacrylate / acrylic acid copolymer ( 59/8/26/5/2 mass %, solid content 25 mass %) 1.0 parts by mass Aromatic polyester (Placoat Z-687 (manufactured by Goo Chemical Industry Co., Ltd.), solid content 25 mass %) 152. 5 parts by mass Carboxymethylcellulose Na (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen EP, 1% by mass aqueous solution) 203.2 parts by mass Sodium alkylbenzene sulfonate (Daiichi Kogyo Seiyaku Co., Ltd., Neogen T, 15% by mass Aqueous solution) 3.8 parts by mass Neugen LP70 (1% by mass aqueous solution of Daiichi Kogyo Seiyaku Co., Ltd.) 67.7 parts by mass Distilled water 545.5 parts by mass

Using the first sheet of Example 6 and the second sheet produced in Example 1, the pressure distribution was measured in the same manner as in Example 1. As a result, there was no unevenness in color development, and the shape of the color development area was similar to that of the SUS substrate. (ie, "5" in the pressure distribution measurement evaluation criteria described above).

<Example 7>
The first sheet and the second sheet were prepared in the same manner as in Example 1, except that the polyethylene naphthalate sheet formed with the adhesion layer A prepared in Example 6 was used as the first support and the second support. made. The first layer and the second layer were formed on the surface of the adhesion layer.
When the shrinkage rate of the first sheet prepared in Example 7 was measured in the same manner as in Example 1, the shrinkage rate of the first sheet prepared in Example 7 was 0.5% for S1 and 0 for S2. was 0.1%.
When the shrinkage rate of the second sheet prepared in Example 7 was measured in the same manner as in Example 1, the shrinkage rate of the second sheet prepared in Example 7 was 0.5% for S1 and 0.5% for S2. was 0.1%.
When the pressure distribution was measured in the same manner as in Example 1 using the first sheet and the second sheet in Example 7, it was found that there was no unevenness in color development, and the shape of the color development region was a ring shape similar to that of the SUS substrate. was very well recognized (ie, "5" in the pressure profile measurement criteria described above).

REFERENCE SIGNS LIST 10 pressure measurement sheet set 12 first support 13 microcapsules 14 first layer 16 first sheet 18 second support 20 second layer 22 second sheet 30 pressure measurement sheet 32 support

Claims (16)

a first sheet having a first support and a first layer containing microcapsules containing a coloring agent disposed on the first support;
a second sheet having a second support and a second layer comprising a developer disposed on said second support;
A pressure measurement sheet set comprising:
When the first sheet is heated at 220° C. for 10 minutes, both the shrinkage rate S1 in the longitudinal direction of the first sheet and the shrinkage rate S2 in the width direction perpendicular to the longitudinal direction of the first sheet are -0.5 to 2.0%,
When the second sheet is heated at 220° C. for 10 minutes, both the shrinkage rate S1 in the longitudinal direction of the second sheet and the shrinkage rate S2 in the width direction perpendicular to the longitudinal direction of the second sheet are -0.5 to 2.0%,
wherein the first support and the second support are selected from the group consisting of polyethylene naphthalate film , polyimide film, polysulfone film, and polyethersulfone film ;
A sheet set for pressure measurement, wherein the capsule walls of the microcapsules contain at least one resin selected from the group consisting of polyurea, polyurethaneurea, and polyurethane. Both the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the first sheet and the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the second sheet are 0 to 0. A pressure measuring sheet set according to claim 1, wherein the pressure measuring sheet set is 0.8%. 3. The sheet set for pressure measurement according to claim 1, wherein the color developer is a clay material. The sheet set for pressure measurement according to any one of claims 1 to 3, wherein each of the first support and the second support has a thickness of 25 to 200 µm. The pressure measurement sheet set according to any one of claims 1 to 4, wherein both the first support and the second support are polyethylene naphthalate films. The pressure measurement sheet set according to any one of claims 1 to 5, wherein the first sheet has an adhesion layer between the first support and the first layer. The pressure measurement sheet set according to any one of claims 1 to 6, wherein the second sheet has an adhesion layer between the second support and the second layer. The sheet set for pressure measurement according to claim 6 or 7, wherein the adhesion layer contains a polymer having an aromatic group. a first layer containing microcapsules encapsulating a color former;
a second layer comprising a developer disposed on the first layer;
A sheet for pressure measurement, comprising: a support arranged on the side of the first layer opposite to the second layer, or on the side of the second layer opposite to the first layer; hand,
When the pressure measurement sheet is heated at 220° C. for 10 minutes, the contraction rate S1 in the longitudinal direction of the pressure measurement sheet and the contraction rate S2 in the width direction orthogonal to the longitudinal direction of the pressure measurement sheet are Both are -0.5 to 2.0%,
the support is selected from the group consisting of polyethylene naphthalate film , polyimide film, polysulfone film, and polyethersulfone film ;
A sheet for pressure measurement, wherein the capsule walls of the microcapsules contain at least one resin selected from the group consisting of polyurea, polyurethaneurea, and polyurethane. 10. The sheet for pressure measurement according to claim 9, wherein the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 is 0 to 0.8%. 11. A pressure measuring sheet according to claim 9 or 10, wherein said color developer is a clay material. The sheet for pressure measurement according to any one of claims 9 to 11, wherein the support has a thickness of 25 to 200 µm. The sheet for pressure measurement according to any one of Claims 9 to 12, wherein the support is a polyethylene naphthalate film. Any one of claims 9 to 13, wherein when the first layer has the support on the side opposite to the second layer, an adhesion layer is provided between the support and the first layer. The pressure measurement sheet described in . 14. Any one of claims 9 to 13, wherein when the second layer has the support on the side opposite to the first layer, an adhesion layer is provided between the support and the second layer. The pressure measurement sheet described in . The sheet for pressure measurement according to claim 14 or 15, wherein the adhesion layer contains a polymer having an aromatic group.

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