Pressure measurement sheet set, pressure measurement sheet, microcapsules, dispersion liquid, method for manufacturing pressure measurement sheet set, method for manufacturing pressure measurement sheet

Abstract

The present invention provides a sheet set for pressure measurement having excellent high temperature compatibility, a sheet for pressure measurement, microcapsules, a dispersion, a method for producing a sheet set for pressure measurement, and a method for producing a sheet for pressure measurement. The sheet set for pressure measurement according to the present invention comprises a first sheet having a first layer that includes microcapsules encapsulating a coloring agent, and a second sheet having a second layer that includes a color developer, wherein the coloring agent includes a compound represented by formula (1) and the thermal decomposition temperature of the capsule walls of the microcapsules is 250°C or higher.

Description

[Technical Field]

[0001] The present invention relates to a sheet set for pressure measurement, a sheet for pressure measurement, microcapsules, a dispersion liquid, a method for manufacturing a sheet set for pressure measurement, and a method for manufacturing a sheet for pressure measurement. [Background technology]

[0002] In recent years, the need to measure pressure distribution has increased due to the increasing functionality and precision of products. For convenience, pressure measurement sheet sets and pressure measurement sheets (hereinafter simply referred to as "pressure measurement sheet sets, etc.") are generally used as methods for measuring pressure distribution. For example, Patent Documents 1 to 3 disclose sheet sets for pressure measurement that utilize microcapsules containing a color former. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2004 / 024809 [Patent Document 2] International Publication No. 2018 / 062017 [Patent Document 3] International Publication No. 2020 / 149410 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for accurate pressure measurement in applications such as high-temperature heat pressing, heat pressing, and bonding. Conventional pressure measurement sheet sets, etc., cannot withstand high-temperature pressures of 180°C or higher, making it impossible to accurately measure pressure. Therefore, measures such as temporarily lowering the temperature to below 150°C are necessary. However, because the measurement target, such as a mold, expands due to heat in a high-temperature environment (especially 180°C or higher), the pressure distribution obtained when measuring in a high-temperature environment (especially 180°C or higher) is strictly different from the pressure distribution obtained when measuring in a low-temperature environment (especially below 150°C), and accurate measurement is often not possible. In other words, data obtained by measuring pressure at a lower temperature may not reflect the pressure distribution in a high-temperature environment, and there was a demand for a pressure measurement sheet set or the like that could accurately measure pressure in a high-temperature environment of 180°C or higher. The inventors have found that when measuring pressure distribution using a conventional pressure measurement sheet set or the like in a high-temperature environment of 180°C or higher, coloring occurs in areas other than the pressurized area, making it difficult to easily recognize the shape of the colored area due to pressure, and therefore making it impossible to accurately measure the pressure distribution. Furthermore, they have newly discovered that when pressure is measured in a high-temperature environment, the color of the colored area varies depending on the pressure application time. If the color of the colored area changes depending on the pressure application time even when the same pressure is applied, accurate pressure measurement becomes impossible, and therefore improvements are desired. Hereinafter, the ability to easily recognize the shape of the colored area under pressure and to suppress color change in the colored area over time under pressure is also referred to as excellent high temperature suitability.

[0005] In the examples described in Patent Document 1, a conventional pressure measurement sheet set is used at a temperature below 150°C, not in a high temperature environment (particularly 180°C or higher). The present inventors also investigated the pressure measurement sheet sets and the like described in Patent Documents 2 and 3 and found that they had poor high-temperature suitability when used in high-temperature environments (particularly 180°C or higher).

[0006] In view of the above circumstances, an object of the present invention is to provide a sheet set for pressure measurement that is excellent in high temperature suitability and a sheet for pressure measurement that is excellent in high temperature suitability. Another object of the present invention is to provide a method for producing a microcapsule, a dispersion liquid, a sheet set for pressure measurement, and a sheet for pressure measurement. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following configuration.

[0008] [1] A first sheet having a first layer including microcapsules encapsulating a color former; a second sheet having a second layer containing a color developer, The color former contains a compound represented by formula (1) described below, A sheet set for pressure measurement, wherein the thermal decomposition temperature of the capsule walls of the microcapsules is 250°C or higher. [2] The sheet set for pressure measurement according to [1], wherein when the first sheet is heated at 220°C for 10 minutes, the thermal shrinkage rate Sa1 in the longitudinal direction of the first sheet and the thermal shrinkage rate Sa2 in the width direction perpendicular to the longitudinal direction of the first sheet are both −0.5 to 3.0%. [3] The sheet set for pressure measurement according to [1] or [2], wherein the capsule walls of the microcapsules contain at least one selected from the group consisting of polyurethane urea having a polymethylene polyphenylene structure and melamine resin. [4] The sheet set for pressure measurement according to any one of [1] to [3], wherein the capsule walls of the microcapsules contain a resin having Structure A or Structure B. Structure A: A structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate. Structure B: A structure formed by reacting melamine with formaldehyde. [5] The sheet set for pressure measurement according to any one of [1] to [4], wherein the thickness of the capsule wall of the microcapsules is 80 to 300 nm. [6] The sheet set for pressure measurement according to any one of [1] to [5], wherein the content of the compound represented by the formula (1) is 70 mass % or more relative to the total mass of the color former. [7] A first layer including microcapsules encapsulating a color former; A pressure measuring sheet having a second layer containing a color developer, The color former contains a compound represented by formula (1) described below, The pressure measurement sheet, wherein the capsule walls of the microcapsules have a thermal decomposition temperature of 250°C or higher. [8] The pressure measurement sheet according to [7], wherein when the pressure measurement sheet is heated at 220°C for 10 minutes, the heat shrinkage rate Sb1 in the longitudinal direction of the pressure measurement sheet and the heat shrinkage rate Sb2 in the width direction perpendicular to the longitudinal direction of the pressure measurement sheet are both −0.5 to 3.0%. [9] The pressure measurement sheet according to [7] or [8], wherein the capsule walls of the microcapsules contain at least one selected from the group consisting of polyurethane urea having a polymethylene polyphenylene structure and melamine resin.

[10] The sheet for pressure measurement according to any one of [7] to [9], wherein the capsule walls of the microcapsules contain a resin having Structure A or Structure B. Structure A: A structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate. Structure B: A structure formed by reacting melamine with formaldehyde.

[11] The pressure measurement sheet according to any one of [7] to

[10] , wherein the thickness of the capsule wall of the microcapsules is 80 to 300 nm.

[12] The pressure measurement sheet according to any one of [7] to

[11] , wherein the content of the compound represented by the formula (1) is 70 mass % or more based on the total mass of the color former.

[13] A microcapsule encapsulating a color former, The color former contains a compound represented by formula (1) described below, The microcapsules have a capsule wall whose thermal decomposition temperature is 250°C or higher.

[14] The microcapsules according to

[13] , wherein the capsule wall of the microcapsule contains at least one selected from the group consisting of polyurethane urea having a polymethylene polyphenylene structure and melamine resin.

[15] The microcapsule according to

[13] or

[14] , wherein the capsule wall of the microcapsule contains a resin having Structure A or Structure B. Structure A: A structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate. Structure B: A structure formed by reacting melamine with formaldehyde.

[16] The microcapsules according to any one of

[13] to

[15] , wherein the thickness of the capsule wall of the microcapsule is 80 to 300 nm.

[17] The microcapsules according to any one of

[13] to

[16] , wherein the content of the compound represented by the formula (1) is 70% by mass or more relative to the total mass of the color former.

[18] A dispersion liquid having the microcapsules according to any one of

[13] to

[17] .

[19] A method for producing a sheet set for pressure measurement according to any one of [1] to [6], comprising a step of forming the first layer using the dispersion liquid according to

[18] .

[20] A method for producing the pressure measurement sheet according to any one of [7] to

[12] , comprising the step of forming the first layer using the dispersion according to

[18] . [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a sheet set for pressure measurement having excellent high-temperature suitability and a sheet for pressure measurement having excellent high-temperature suitability. Furthermore, the present invention can provide a method for producing a microcapsule, a dispersion liquid, a sheet set for pressure measurement, and a sheet for pressure measurement. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of an embodiment of a sheet set for pressure measurement. [Figure 2] 10A and 10B are diagrams illustrating a usage pattern of the pressure measurement sheet set. [Figure 3] FIG. 2 is a cross-sectional view of one embodiment of a pressure measurement sheet. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, in the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In this specification, when the term "substituent" is simply used, examples of the substituent include the groups exemplified by the following substituent T.

[0012] (substituent T) Examples of the substituent T include a halogen atom (such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a hydroxy group, a nitro group, a carboxy group, an alkoxy group, an aryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, an amino group (including an alkylamino group and an anilino group), an acylamino group, an aminocarbonylamino group, an alkoxycarbonylamino group, an aryl ... Examples of groups containing a polymerizable group include a carbonylamino group, a sulfamoylamino group, an alkyl or arylsulfonylamino group, a mercapto group, an alkylthio group, an arylthio group, a heterocyclic thio group, a sulfamoyl group, a sulfo group, an alkyl or arylsulfinyl group, an alkyl or arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl or heterocyclic azo group, an imido group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a silyl group, and a group containing a polymerizable group. Among the above-mentioned substituents, those having a hydrogen atom may have the hydrogen atom portion further substituted with any of the above-mentioned substituents.

[0013] The characteristic features of the pressure measurement sheet set and pressure measurement sheet of the present invention include that the color former contains a compound represented by formula (1) (hereinafter also referred to as the "specific compound"), and that the thermal decomposition temperature of the capsule wall is 250°C or higher. The present inventors have found that when the color former contains a specific compound and the capsule wall has a predetermined thermal decomposition temperature, the high-temperature suitability of the pressure measurement sheet set, etc. is excellent. Specifically, the present inventors speculate that the inclusion of a specific compound with excellent thermal stability prevents color change in the color-developed region even when heated for a long period of time, and that the inclusion of a capsule wall that is resistant to thermal decomposition prevents color development in regions other than the pressurized portion at high temperatures (particularly 180°C or higher), making it easy to identify the range of the region that has developed color under pressure, resulting in excellent high-temperature suitability of the pressure measurement sheet set, etc. Hereinafter, the excellent high temperature suitability of the pressure measurement sheet set or the like is also referred to as the excellent effect of the present invention.

[0014] [First embodiment] FIG. 1 is a cross-sectional view of one embodiment of a sheet set for pressure measurement. The pressure measurement sheet set 10 comprises a first sheet 16 having a first support 12 and a first layer 14 including microcapsules 13 arranged on the first support 12, and a second sheet 22 having a second support 18 and a second layer 20 including a color developer arranged on the second support 18. When using the pressure measurement sheet set 10, the first sheet 16 and the second sheet 22 are laminated together so that the first layer 14 in the first sheet 16 faces the second layer 20 in the second sheet 22, as shown in Fig. 2. By applying pressure 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 resulting laminate, the microcapsules 13 are broken in the pressurized areas, and the color former encapsulated in the microcapsules 13 is released from the microcapsules 13, causing a color-developing reaction between the microcapsules 13 and the color developer in the second layer 20. As a result, color development progresses in the pressurized areas.

[0015] As will be described later, the first sheet 16 only needs to have the first layer 14, and does not necessarily have to have the first support 12. The second sheet 22 only needs to have the second layer 20, and does not necessarily have to have the second support 18. 1, the first support 12 and the first layer 14 are directly laminated to each other, but the present invention is not limited to this embodiment, and as will be described later, another layer (for example, an adhesive layer) may be disposed between the first support 12 and the first layer 14. Furthermore, in FIG. 1, the second support 18 and the second layer 20 are directly laminated to each other, but the present invention is not limited to this embodiment, and as will be described later, another layer (for example, an adhesive layer) may be disposed between the second support 18 and the second layer 20.

[0016] The configurations of the first sheet 16 and the second sheet 22 that make up the pressure measurement sheet set 10 will be described in detail below.

[0017] <<First Sheet>> The first sheet 16 shown in FIG. 1 has a first support 12 and a first layer 14 containing microcapsules 13 that encapsulate a color former.

[0018] When the first sheet is heated at 220°C for 10 minutes, it is preferable that the heat shrinkage rate Sa1 in the longitudinal direction of the first sheet and the heat shrinkage rate Sa2 in the width direction perpendicular to the longitudinal direction of the first sheet are both -0.5 to 3.0%. The methods for measuring the heat shrinkage rates Sa1 and Sa2 of the first sheet are as shown in the Examples section. There are no particular limitations on the method for adjusting the thermal shrinkage rate of the first sheet to the above range, but it is preferable to use a film as the first support whose thermal shrinkage rate in the longitudinal and transverse directions when heated at 220°C for 10 minutes is -0.5 to 3.0, and it is more preferable to use a polyethylene naphthalate film or a polyimide film.

[0019] The longitudinal direction of the first sheet means the long dimension of the first sheet, specifically, if the first sheet 16 is rectangular, it means the direction along the long side. Furthermore, the width direction of the first sheet means the direction perpendicular to the longitudinal direction of the first sheet (short direction), for example, if the first sheet is rectangular, it means the direction along the short side. However, if the first sheet is square, the direction along one of the sides constituting the square is the long axis direction, and the direction along the side perpendicular to the long axis is the width direction. The first sheet may be a single sheet (single sheet) or may be in a long shape. Each component will be described in detail below.

[0020] [First support] The first support is a member for supporting the first layer. Note that if the first layer itself can be handled, the first sheet does not need to have a first support.

[0021] The first support may be in the form of either a sheet or a plate. The first support may be a resin film or synthetic paper. Examples of resin films include polyester films such as polyethylene naphthalate and polyethylene terephthalate films; cellulose derivative films such as cellulose triacetate; polyolefin films such as polypropylene and polyethylene; and polystyrene films. Examples of synthetic paper include synthetic paper (e.g., Yupo) made by biaxially stretching polypropylene or polyethylene terephthalate to form a large number of microvoids, synthetic paper made using synthetic fibers such as polyethylene, polypropylene, polyethylene terephthalate, and polyamide, and synthetic paper made by laminating these on part, one side, or both sides of the paper. Among these, the first support is preferably a resin film or synthetic paper, more preferably a resin film, further preferably a polyester film, and particularly preferably a polyethylene naphthalate film. Commercially available polyethylene naphthalate films include, for example, Teonex (registered trademark) Q51, Q53, Q81 and Q83 (manufactured by Teijin Film Solutions Co., Ltd.). The first support is preferably transparent so that the color development can be visually confirmed even when viewed from the support side.

[0022] The thickness of the first support is preferably 10 to 200 μm.

[0023] [1st layer] The first layer contains microcapsules that encapsulate a specific compound and have capsule walls with a predetermined thermal decomposition temperature. First, the materials constituting the microcapsules will be described in detail below.

[0024] <Microcapsules> A microcapsule has a core portion and a capsule wall for encapsulating a core material (an entity to be encapsulated (hereinafter also referred to as an "encapsulated component")) that forms the core portion. In the present invention, the microcapsules contain a color former containing a specific compound as a core material (encapsulated component). Generally, since the color former is encapsulated in the microcapsules, the color former can remain in the microcapsules until the microcapsules are ruptured by application of pressure.

[0025] The microcapsules have a capsule wall that encapsulates a core material. The thermal decomposition temperature of the capsule wall of the microcapsule is 250° C. or higher, preferably more than 250° C., more preferably 255° C. or higher, and even more preferably 260° C. or higher. The upper limit is not particularly limited, but is often 500° C. or lower. The method for measuring the thermal decomposition temperature of the capsule wall is as follows. Fifty sheets of the first layer (microcapsule layer) measuring 1 cm in length and 1 cm in width are prepared, and all of them are immersed in 10 mL of water and left to stand for 24 hours to obtain an aqueous dispersion of microcapsules. Note that if the first sheet contains a first support, 50 first sheets measuring 1 cm in length and 1 cm in width may be prepared and immersed. The resulting aqueous dispersion of microcapsules is centrifuged at 15,000 rpm for 30 minutes, and the microcapsules are separated. Ethyl acetate (1000 times or more) is added to the separated microcapsules, followed by stirring at 25°C for 24 hours. The resulting solution is then filtered, and the resulting residue is vacuum-dried at 60°C for 48 hours, yielding microcapsules with nothing encapsulated inside (hereinafter simply referred to as "measurement material"). In other words, the capsule wall material of the microcapsules, the thermal decomposition temperature of which is to be measured, is obtained. Next, the thermal decomposition temperature of the obtained measurement material is measured using a thermogravimetric differential thermal analyzer TG-DTA (device name: DTG-60, manufactured by Shimadzu Corporation). The thermal decomposition temperature (°C) is defined as the temperature at which the measurement material is heated from room temperature at a constant heating rate (10°C / min) in a thermogravimetric analysis (TGA) in an atmospheric atmosphere, and the mass of the measurement material before heating is reduced by 5% by mass.

[0026] Examples of the material for the capsule wall (wall material) of the microcapsules include known resins that have conventionally been used as wall materials for microcapsules containing color formers in the applications of pressure-sensitive copying paper and thermosensitive recording paper. The capsule wall of the microcapsule is preferably made substantially of a resin. "Substantially composed of resin" means that the resin content is 90% by mass or more, preferably 100% by mass, of the total mass of the capsule wall of the microcapsule. In other words, the capsule wall of the microcapsule is preferably composed of resin.

[0027] Examples of the resin include polyurethane, polyurea, polyurethane urea, melamine resin, acrylic resin, and gelatin. In particular, in terms of achieving better effects of the present invention, the capsule wall of the microcapsule preferably contains at least one selected from the group consisting of polyurethane, polyurea, polyurethane urea, and melamine resin, more preferably contains at least one selected from the group consisting of polyurethane urea and melamine resin, and even more preferably contains polyurethane urea or melamine resin having a polymethylene polyphenylene structure. The polymethylene polyphenylene structure means a structure represented by formula (Y): In formula (Y), n represents an integer of 1 or more, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5.

[0028] [ka]

[0029] The melamine resin is preferably a reaction product formed from the polycondensation of melamine and formaldehyde. A polyisocyanate is a compound that contains two or more isocyanate groups. Examples of polyisocyanates include aromatic polyisocyanates and aliphatic polyisocyanates, with aromatic polyisocyanates being preferred because they allow the introduction of aromatic ring groups into the capsule walls of the microcapsules. Examples of 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.

[0030] Examples of the aliphatic polyisocyanate include aliphatic diisocyanates, such as trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, isophorone diisocyanate, lysine diisocyanate, and hydrogenated xylylene diisocyanate.

[0031] The polyisocyanate also includes tri- or higher functional polyisocyanates (for example, trifunctional triisocyanates and tetrafunctional tetraisocyanates). Specific examples of the polyisocyanate include biuret compounds or isocyanurate compounds, which are trimers of the above-mentioned bifunctional polyisocyanates, adducts (addition products) of polyols such as trimethylolpropane with bifunctional polyisocyanates, formalin condensates of benzene isocyanate, polyisocyanates having a polymerizable group such as methacryloyloxyethyl isocyanate, and lysine triisocyanate. For information on polyisocyanates, refer to "Polyurethane Resin Handbook" (edited by Iwata Keiji, published by Nikkan Kogyo Shimbun, 1987).

[0032] Among these, one of the preferred embodiments of the polyisocyanate is a tri- or higher functional polyisocyanate. Examples of tri- or higher functional polyisocyanates include tri- or higher functional aromatic polyisocyanates and tri- or higher functional aliphatic polyisocyanates. As the tri- or higher functional polyisocyanate, a tri- or higher functional polyisocyanate that is an adduct (addition product) of an aromatic or alicyclic diisocyanate and a compound having three or more active hydrogen groups in one molecule (for example, a tri- or higher functional polyol, polyamine, or polythiol) (adduct-type tri- or higher functional polyisocyanate) and a trimer (biuret type or isocyanurate type) of an aromatic or alicyclic diisocyanate are also preferred, and the above-mentioned tri- or higher functional polyisocyanate that is an adduct (addition product) is more preferred.

[0033] The tri- or higher functional polyisocyanate that is an adduct is preferably a tri- or higher functional polyisocyanate that is an adduct of an aromatic or alicyclic diisocyanate and a polyol having three or more hydroxy groups in one molecule, and more preferably a tri-functional polyisocyanate that is an adduct of an aromatic or alicyclic diisocyanate and a polyol having three hydroxy groups in one molecule. As the adduct, it is preferable to use an adduct obtained by using an aromatic diisocyanate, in that the effects of the present invention are more excellent. As the polyol, for example, a tri- or higher functional low molecular weight polyol, which will be described later, is preferred, and trimethylolpropane is more preferred.

[0034] Examples of adduct-type tri- or higher functional polyisocyanates 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 Burnock (registered trademark) D-750 (manufactured by DIC Corporation). Among these, as the adduct type tri- or higher functional polyisocyanate, Takenate (registered trademark) D-110N, D-120N, D-140N, D-160N (manufactured by Mitsui Chemicals, Inc.) or Burnock (registered trademark) D-750 manufactured by DIC Corporation is preferred, and Burnock (registered trademark) D-750 manufactured by DIC Corporation is more preferred.

[0035] Examples of isocyanurate-type tri- or higher functional polyisocyanates include Takenate (registered trademark) D-127N, D-170N, D-170HN, D-172N, D-177N, and D-204 (manufactured by Mitsui Chemicals, Inc.), Sumidur N3300, Desmodur (registered trademark) N3600, N3900, and Z4470BA (manufactured by Sumika Bayer Urethane), Coronate (registered trademark) HX and HK (manufactured by Nippon Polyurethane Co., Ltd.), and Duranate (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, and TSE-100 (manufactured by Asahi Kasei Corporation).

[0036] Examples of biuret-type tri- or higher functional polyisocyanates include Takenate (registered trademark) D-165N, NP1100 (manufactured by Mitsui Chemicals, Inc.), Desmodur (registered trademark) N3200 (manufactured by Sumika Bayer Urethane), and Duranate (registered trademark) 24A-100 (manufactured by Asahi Kasei Corporation).

[0037] Furthermore, polymethylene polyphenyl polyisocyanate is also preferred as the polyisocyanate. As the polymethylene polyphenyl polyisocyanate, a compound represented by formula (X) is preferred.

[0038] [ka]

[0039] In formula (X), n represents an integer of 1 or more. n is preferably an integer of 1 to 10, and more preferably an integer of 1 to 5, in order to enable better measurement of pressure distribution at high temperatures.

[0040] Examples of polyisocyanates containing polymethylene polyphenyl polyisocyanates include Millionate MR-100, Millionate MR-200, Millionate MR-400 (manufactured by Tosoh Corporation), Wannate PM-200, Wannate PM-400 (manufactured by Wanka Japan Co., Ltd.), Cosmonate M-50, Cosmonate M-100, Cosmonate M-200, Cosmonate M-300 (manufactured by Mitsui Chemicals, Inc.), and Boranate M-595 (manufactured by The Dow Chemical Company).

[0041] A polyol is a compound that has two or more hydroxy groups. Examples of polyols include low molecular weight polyols (e.g., aliphatic polyols and aromatic polyols), polyvinyl alcohol, polyether-based polyols, polyester-based polyols, polylactone-based polyols, castor oil-based polyols, polyolefin-based polyols, and hydroxy group-containing amine-based compounds. The low molecular weight polyol means a polyol having a molecular weight of 400 or less, and examples thereof include difunctional low molecular weight polyols such as ethylene glycol, diethylene glycol, and propylene glycol; and trifunctional or higher low molecular weight polyols such as glycerin, trimethylolpropane, hexanetriol, pentaerythritol, and sorbitol.

[0042] Examples of hydroxy group-containing amine compounds include oxyalkylated derivatives of amino compounds, with amino alcohols being preferred. Examples of amino alcohols include propylene oxide and ethylene oxide adducts of amino compounds such as ethylenediamine, and specific examples include N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine and N,N,N',N'-tetrakis[2-hydroxyethyl]ethylenediamine.

[0043] A polyamine is a compound having two or more amino groups (primary amino groups or secondary amino groups). Examples of polyamines include aliphatic polyamines such as diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, and hexamethylenediamine; epoxy compound adducts of aliphatic polyamines; alicyclic polyamines such as piperazine; and heterocyclic diamines such as 3,9-bis-aminopropyl-2,4,8,10-tetraoxaspiro-(5,5)undecane.

[0044] A preferred embodiment of the resin contained in the capsule wall of the microcapsules is one having Structure A or Structure B. With Structure A or Structure B, the rigidity can be improved while maintaining a high crosslink density, and the migration of the encapsulated color former out of the capsule can be further suppressed, thereby further improving the effects of the present invention. Structure A is a structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate (preferably a compound represented by formula (X)). Structure B is a structure obtained by reacting melamine with formaldehyde.

[0045] Another preferred embodiment of the resin contained in the capsule wall of the microcapsule is formed using a tri- or higher functional polyisocyanate A (hereinafter simply referred to as "polyisocyanate A"), which is an adduct of an aromatic or alicyclic diisocyanate and a compound having three or more active hydrogen groups in one molecule, and a polyisocyanate B (hereinafter simply referred to as "polyisocyanate B") selected from the group consisting of aromatic diisocyanates and polymethylene polyphenyl polyisocyanates. That is, the capsule wall of the microcapsule preferably contains a resin formed using the polyisocyanate A and polyisocyanate B, in view of the excellent effects of the present invention.

[0046] As the polyisocyanate B, an aromatic diisocyanate may be used alone, or a polymethylene polyphenyl polyisocyanate may be used alone, or both may be used in combination. Among these, the polyisocyanate B is preferably a mixture of an aromatic diisocyanate and a polymethylene polyphenyl polyisocyanate. In the above mixture, the mass ratio of the mass of polymethylene polyphenyl polyisocyanate to the mass of aromatic diisocyanate (mass of polymethylene polyphenyl polyisocyanate / mass of aromatic diisocyanate) is preferably 0.1 to 10, more preferably 0.5 to 2, and even more preferably 0.75 to 1.5.

[0047] The viscosity of polyisocyanate B is preferably 100 to 1000 mPa·s. The above viscosity is measured at 25°C.

[0048] When polyisocyanate A and polyisocyanate B are used in combination, the mass ratio of the mass of polyisocyanate A to the mass of polyisocyanate B (mass of polyisocyanate A / mass of polyisocyanate B) is preferably 20 / 80 to 98 / 2, more preferably 20 / 80 to 90 / 10, and even more preferably 20 / 80 to 70 / 30, in terms of excellent effects of the present invention.

[0049] The volume-based median diameter (D50) of the microcapsules is preferably from 1 to 80 μm, more preferably from 5 to 70 μm, and even more preferably from 10 to 50 μm. The volume-based median diameter of the microcapsules can be controlled by adjusting the manufacturing conditions of the microcapsules. Here, the volume-based median diameter of a microcapsule refers to the diameter at which the total volume of particles on the larger and smaller diameter sides is equal when the entire microcapsule is divided into two parts with a particle diameter that accounts for 50% of the total volume. In other words, the median diameter corresponds to the so-called D50. This value is calculated by photographing the surface of the first layer of a first sheet having a first layer containing microcapsules with an optical microscope at 1000x magnification and measuring the size of all microcapsules within an area of ​​500 μm x 500 μm. The volume-based median diameter of the microcapsules contained in the dispersion may be measured using a laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by HORIBA Corporation).

[0050] The thickness of the capsule wall of the microcapsules (number average wall thickness) is often 0.01 to 2.0 μm, preferably 0.05 to 1.0 μm, more preferably 50 to 500 nm, and further preferably 80 to 300 nm in order to obtain better effects of the present invention. In order to obtain better gradation at high temperatures, the thickness is particularly preferably 80 to 250 nm, and most preferably 100 to 200 nm. The thickness of a microcapsule refers to the thickness of the capsule wall that forms the capsule particle of the microcapsule, and the number-average wall thickness refers to the average value obtained by measuring the individual capsule wall thicknesses of five microcapsules using a scanning electron microscope (SEM). More specifically, a cross-sectional section of a first sheet having a first layer containing microcapsules is prepared, and the cross-section is observed using an SEM at 200x magnification. Five microcapsules having major diameters ranging from [(volume-based median diameter (D50) of the microcapsules) × 0.9] to [(volume-based median diameter (D50) of the microcapsules) × 1.1] are selected, and the cross-sections of the selected individual microcapsules are observed at 15,000x magnification to determine the capsule wall thickness of the microcapsules and calculate the average value. The major diameter refers to the longest diameter observed in the microcapsules.

[0051] The ratio (δ / Dm) of the number average wall thickness δ of the microcapsules to the volume-based median diameter (D50) Dm of the microcapsules is not particularly limited, but is often 0.001 or more. In particular, it is preferable that the relationship of formula (1) is satisfied, in that the effects of the present invention are more excellent. Equation (1) 0.100>δ / Dm>0.001 That is, the ratio (δ / Dm) is preferably greater than 0.001 and less than 0.100. When the relationship of formula (1) is satisfied, the color density gradation according to pressure can be made within a range that is easily recognized.

[0052] The microcapsules may be used alone or in combination of two or more types. The content of the microcapsules in the first layer is preferably 50 to 90% by mass, more preferably 55 to 80% by mass, based on the total mass of the first layer.

[0053] (color former) The microcapsules encapsulate a color former containing a compound represented by formula (1). A color former is a compound that develops color from a colorless state when it comes into contact with a color developer, which will be described later. The color former is preferably an electron-donating dye precursor (a precursor of a color-developing dye). In other words, the color former is preferably an electron-donating colorless dye.

[0054] ((Compound represented by formula (1))

[0055] [ka]

[0056] In formula (1), R 1 represents an alkyl group which may have a substituent. 3 is -NR A R B Represents R A and R B R each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. 2 and R 4 each independently represents a halogen atom; Q represents a benzene ring or a naphthalene ring; X represents -O- or -NR 5 - represents R 5 represents an alkyl group which may have a substituent or an aryl group which may have a substituent. p and q each independently represent an integer of 0 to 4. r represents an integer of 1 to 3. s represents an integer of 0 to 3, provided that p+q is an integer of 0 to 4, and r+s is an integer of 1 to 4.

[0057] R 1 represents an alkyl group which may have a substituent. The alkyl group may be linear, branched, or cyclic, and is preferably linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. Examples of the substituent that the alkyl group may have include the groups exemplified for the substituent T above. Multiple Rs 1 may be the same or different.

[0058] R 3 is -NR A R B Represents. R A and R B each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. The alkyl group may be linear, branched, or cyclic, and is preferably linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms. The aryl group may be either monocyclic or polycyclic. Examples of the substituent that the alkyl group and the aryl group may have include the groups exemplified for the substituent T above. Among them, R A and R B At least one of the groups preferably represents an alkyl group which may have a substituent, and more preferably represents an unsubstituted alkyl group. Multiple Rs 3 may be the same or different.

[0059] R 2 and R 4 each independently represents a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom or a bromine atom being preferred, and a bromine atom being more preferred.

[0060] X is -O- or -NR 5 - represents. Of these, -O- is preferred as X. R 5 represents an alkyl group which may have a substituent or an aryl group which may have a substituent. The alkyl group may be linear, branched, or cyclic, and is preferably linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms. The aryl group may be either monocyclic or polycyclic. Among them, R 5 As the alkyl group, an optionally substituted alkyl group or an optionally substituted aryl group is preferred, and an optionally substituted aryl group is more preferred. Examples of the substituent that the alkyl group and the aryl group may have include the groups exemplified above as the substituent T, and is preferably at least one selected from the group consisting of a halogen atom, a cyano group, a nitro group, and a carboxy group, and more preferably a nitro group.

[0061] p and q each independently represent an integer of 0 to 4. r represents an integer of 1 to 3. s represents an integer of 0 to 3, provided that p+q is an integer of 0 to 4, and r+s is an integer of 1 to 4. p is preferably an integer of 0 to 2. q is preferably an integer of 0 to 1. r is preferably an integer of 1 to 2, more preferably 1. s is preferably an integer of 0 to 1, more preferably 0. When Q represents a naphthalene ring, p and q are preferably 0. p+q is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2. As r+s, an integer of 1 to 3 is preferable, an integer of 1 or 2 is more preferable, and 1 is even more preferable.

[0062] ((Compound represented by formula (2)) The compound represented by formula (1) is preferably a compound represented by formula (2).

[0063] [ka]

[0064] In formula (2), R 6 represents an alkyl group which may have a substituent. 7 represents a halogen atom. A and R B each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. Q represents a benzene ring or a naphthalene ring. t and u each independently represent an integer of 0 to 4, provided that t + u is an integer of 0 to 4.

[0065] R 6 represents an alkyl group which may have a substituent. The alkyl group includes R 1 The same definition and preferred range are also the same.

[0066] R 7 represents a halogen atom. R 7 is R in Eq. (1) 2 The same definition and preferred range are also the same.

[0067] R A and R B each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. Q represents a benzene ring or a naphthalene ring. R in equation (2) A , R B and Q are the R in the above formula (1), A , R B and Q have the same meanings and preferred ranges.

[0068] t and u each independently represent an integer of 0 to 4, provided that t+u is an integer of 0 to 4. t is preferably an integer of 0 to 2. u is preferably an integer of 0 to 1. When Q represents a naphthalene ring, t and u are preferably 0. As t+u, an integer of 0 to 3 is preferable, and an integer of 0 to 2 is more preferable.

[0069] The specific compounds include the following compounds.

[0070] [ka]

[0071] The microcapsules may contain other color formers in addition to the specific compound. The other color formers are not particularly limited as long as they are color formers other than the specific compounds, and include color formers known in the art for use in pressure-sensitive copying paper or thermal recording paper.

[0072] As the other color former, the compound represented by formula (D) is preferred in terms of excellent visibility.

[0073] [ka]

[0074] In formula (D), R D1 and R D3 each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. R D1 and R D3 The alkyl group represented by the formula (I) preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms. Examples of the substituent that the alkyl group and the aryl group may have include the groups exemplified above for the substituent T, and R D1 and R D3 are each independently preferably an alkyl group which may have a substituent or an aryl group which may have a substituent, more preferably an alkyl group which may have a substituent, and still more preferably an unsubstituted alkyl group.

[0075] R D2 and R D4each independently represents an alkyl group which may have a substituent, or an aryl group which may have a substituent. R D2 and R D4 The alkyl group represented by the formula (I) preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. R D2 and R D4 The aryl group represented by the following formula may be either a monocyclic or polycyclic group. The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms. Examples of the substituent that the alkyl group and the aryl group may have include the groups exemplified for the substituent T above. Among them, R D2 and R D4 Each of the alkyl groups is preferably an alkyl group which may have a substituent, and more preferably an unsubstituted alkyl group.

[0076] Among them, R D1 ~R D4 are preferably all unsubstituted alkyl groups, and more preferably the same unsubstituted alkyl groups.

[0077] R D5 is -O- or -NR D6 - represents. Among them, -NR D6 - is preferred. R D6 represents an alkyl group which may have a substituent, or an aryl group which may have a substituent. R D6 The alkyl group represented by the formula (I) preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms. R D6 The aryl group represented by the following formula (I) may have a monocyclic structure or a polycyclic structure. Examples of the substituent that the alkyl group and the aryl group may have include the groups exemplified for the substituent T above. Among them, RD6 As the alkyl group, an aryl group which may have a substituent is preferable, an aryl group substituted with a group selected from the group consisting of a halogen atom, a cyano group, a nitro group, and a carboxyl group is more preferable, and an aryl group substituted with a nitro group is even more preferable.

[0078] The molecular weight of the compound represented by formula (D) is not particularly limited, but is preferably at least 300, more preferably at least 500. The upper limit is not particularly limited, but is preferably at most 2000, more preferably at most 1000.

[0079] Other color formers include, for example, triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, azaindolylphthalide compounds, leucoauramine compounds, rhodamine lactam compounds, triphenylmethane compounds, diphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds. Other color formers include, for example, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-n-octyl-2-methylindol-3-yl)phthalide, 3-[2,2-bis(1-ethyl-2-methylindol-3-yl)vinyl]-3-(4-diethylaminophenyl)-phthalide, 2-anilino-6-dibutylamine, Examples of the compounds include 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide, 2-anilino-6-diethylamino-3-methylfluoran, and 3',6'-bis(diethylamino)-2-(4-nitrophenyl)spiro[isoindole-1,9'-xanthen]-3-one. For details of the compounds mentioned above, see JP-A-5-257272.

[0080] The molecular weight of the color former is often not less than 300. The upper limit is often not more than 1000, and is preferably not more than 600 in terms of achieving better effects of the present invention.

[0081] The color formers may be used alone or in combination of two or more. The content of the color former in the first layer is 0.1 to 10 g / m 2 is preferable, and 0.1 to 4 g / m 2 is more preferred. The content of the specific compound is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, and particularly preferably 70% by mass or more, based on the total mass of the color former, in order to achieve excellent light resistance after color development. The upper limit is preferably 100% by mass or less, based on the total mass of the color former.

[0082] (Other ingredients) The microcapsules may contain other components in addition to the color formers described above. Other components include solvents and additives such as ultraviolet absorbers, light stabilizers, antioxidants, waxes and odor suppressants, with solvents being preferred. As the ultraviolet absorber, a compound having a benzotriazole structure is preferred. The solvent preferably contains an aromatic solvent from the viewpoint of improving the solubility of the color former. Examples of the solvent include aromatic hydrocarbons such as alkylnaphthalene compounds such as diisopropylnaphthalene, diarylalkane compounds such as 1-phenyl-1-xylylethane, alkylbiphenyl compounds such as isopropylbiphenyl, triarylmethane compounds, alkylbenzene compounds, benzylnaphthalene compounds, diarylalkylene compounds, and arylindane compounds; aliphatic hydrocarbons such as dibutyl phthalate and isoparaffin; natural animal and vegetable oils such as soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, palm oil, castor oil, and fish oil; and natural high-boiling fractions such as mineral oil.

[0083] The solvent may be used alone or in combination of two or more. When a solvent is encapsulated in the microcapsules, the mass ratio of the mass of the color former to the mass of the solvent (mass of solvent / mass of color former) is preferably 98 / 2 to 30 / 70, more preferably 97 / 3 to 40 / 60, from the viewpoint of color development.

[0084] <Method of manufacturing 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, with interfacial polymerization being preferred. A preferred interfacial polymerization method includes a step of preparing an emulsion by dispersing an oil phase containing a color former and a capsule wall material (e.g., a raw material containing a polyisocyanate and at least one selected from the group consisting of a polyol and a polyamine. Note that, when a polyamine is produced in situ by reacting a polyisocyanate with water, the polyol and the polyamine do not need to be used) in an aqueous phase containing an emulsifier (emulsification step), and a step of polymerizing the capsule wall material at the interface between the oil phase and the aqueous phase to form a capsule wall and form microcapsules encapsulating the color former (encapsulation step). The mass ratio of the total amount of polyol and polyamine to the amount of polyisocyanate in the raw materials (total amount of polyol and polyamine / amount of polyisocyanate) is not particularly limited, but is preferably 0.1 / 99.9 to 30 / 70, and more preferably 1 / 99 to 25 / 75. As mentioned above, the polyisocyanate may be a combination of the polyisocyanate A and the polyisocyanate B. When both are used in combination, the preferred range of the mixing ratio between them is as mentioned above.

[0085] The type of emulsifier used in the emulsification step is not particularly limited, but examples thereof include dispersants and surfactants. An example of the dispersant is polyvinyl alcohol.

[0086] The first layer may contain other components in addition to the above-mentioned microcapsules. Examples of other components include polymer binders, inorganic fillers (for example, colloidal silica), fluorescent brighteners, antifoaming agents, penetrating agents, ultraviolet absorbers, surfactants, and preservatives. Examples of polymer binders include synthetic polymers and natural polymers such as styrene-butadiene copolymer, polyvinyl acetate, polyacrylic acid ester, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymer, starch, casein, gum arabic, gelatin, carboxymethyl cellulose or a salt thereof, and methyl cellulose. The content of the polymer binder is not particularly limited, but is preferably 0 to 50% by mass relative to the total mass of the first layer. In terms of suitability for a low pressure range of 20 MPa or less, the content is preferably 0.1 to 20% by mass, and more preferably 0.2 to 10% by mass. Examples of surfactants include anionic surfactants, nonionic surfactants, and cationic surfactants, and anionic surfactants or nonionic surfactants are preferred in terms of maintaining the dispersibility of the microcapsules. Examples of surfactants include fluorine-based surfactants, silicone-based surfactants, and hydrocarbon-based surfactants, with hydrocarbon-based surfactants being preferred in terms of maintaining coatability and dispersibility of the microcapsules. The content of the surfactant is not particularly limited, but is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass, relative to the total mass of the first layer.

[0087] The inorganic filler is preferably incorporated so that the first sheet and the second sheet can be easily peeled off after the sheets are stacked and the heating pressure is measured. In order to facilitate peeling of the first sheet and the second sheet, silica particles or alumina particles are preferred as the inorganic filler. The median diameter of the inorganic filler is preferably from 0.001 to 1 μm, more preferably from 0.005 to 0.1 μm, and even more preferably from 0.005 to 0.05 μm. The content of the inorganic filler is preferably from 1 to 50% by mass, more preferably from 3 to 30% by mass, and more preferably from 5 to 20% by mass, relative to the total mass of the first layer.

[0088] The thickness of the first layer is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.02 to 3 μm. Here, the thickness of the first layer refers to the thickness excluding the microcapsules exposed from the layer surface when the average particle size of the microcapsules is greater than the layer thickness. When the thickness of the first layer is within the above range, aggregation of the microcapsules can be suppressed when the first layer-forming composition containing the microcapsules is applied and then dried, and the capsules can be adjusted so that they break at the desired pressure. The thickness of the first layer is preferably 50% or less, and more preferably 25% or less, of the average particle size of the microcapsules. The thinner the thickness of the first layer is relative to the microcapsules, the more easily the microcapsules break, so the thickness can be adjusted according to the pressure range to be measured. Also, the mass per unit area of ​​the first layer (g / m 2 ) is not particularly limited, but is preferably 0.5 to 20 g / m 2 is preferred.

[0089] [First layer formation method] The method for forming the first layer is not particularly limited, and known methods can be used. For example, a method may be used in which a composition for forming the first layer containing microcapsules is applied onto the first support, and then, if necessary, a drying treatment is carried out. The composition for forming the first layer may be a dispersion in which microcapsules are dispersed in water or the like. The dispersion liquid in which the microcapsules are dispersed can be prepared by mechanically dispersing the microcapsules in water or the like. The composition for forming the first layer preferably contains at least microcapsules and a solvent. Note that the microcapsule dispersion obtained by the above-mentioned interfacial polymerization method may also be used as the composition for forming the first layer. The composition for forming the first layer may contain other components that can be contained in the first layer described above.

[0090] The method for applying the composition for forming the first layer is not particularly limited, but examples of coating machines used for application include an air knife coater, a rod coater, a bar coater, a curtain coater, a gravure coater, an extrusion coater, a die coater, a slide bead coater, and a blade coater.

[0091] After the first layer-forming composition is applied to the first support, the coating may be subjected to a drying treatment, such as a heating treatment, if necessary.

[0092] Although the method of forming the first layer on the first support has been described above, the present invention is not limited to the above embodiment. For example, after the first layer is formed on the temporary support, the temporary support may be peeled off to form a first sheet made of the first layer. The temporary support is not particularly limited as long as it is a releasable support.

[0093] <Other materials> The first sheet may have other members in addition to the members described above. The first sheet may have, for example, an adhesive layer between the first support and the first layer to enhance adhesion between them. The adhesive layer is not particularly limited, but is preferably a layer containing a resin. The thickness of the adhesive layer is preferably 0.005 to 5 μm, more preferably 0.01 to 1 μm.

[0094] <<Second Sheet>> The second sheet 22 shown in FIG. 1 has a second support 18 and a second layer 20 including a color developer disposed on the second support 18 . The preferred ranges of the heat shrinkage rates Sc1 and Sc2 of the second sheet are the same as the preferred ranges of the heat shrinkage rates Sa1 and Sa2 of the first sheet, respectively.

[0095] The method for measuring the heat shrinkage rates Sc1 and Sc2 of the second sheet is the same as the method for measuring the heat shrinkage rates Sa1 and Sa2 of the first sheet, except that the second sheet is used instead of the first sheet. The definitions of the longitudinal direction and width direction of the second sheet are the same as those of the first sheet, except that the first sheet is read as the second sheet. The second sheet may be a single sheet (single sheet) or may be in a long shape. Each component will be described in detail below.

[0096] [Second support] The second support is a member for supporting the second layer. The second support member has the same configuration as the first support member described above, and therefore, a description thereof will be omitted.

[0097] [Second layer] The second layer is a layer containing a color developer. The color developer is a compound that does not have a color-forming function by itself, but has the property of causing the color former to develop color when it comes into contact with the color former. As the color developer, an electron-accepting compound is preferred. The color developer may be, for example, an inorganic compound or an organic compound. Examples of inorganic compounds include clay materials such as acid clay, activated clay, attapulgite, zeolite, bentonite, and kaolin. Examples of the organic compound include metal salts of aromatic carboxylic acids, phenol formaldehyde resins, and metal salts of carboxylated terpene phenol resins.

[0098] Examples of 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, and 3-(α,α-dimethylbenzyl)-5-methylsalicylic acid. Preferred are zinc, nickel, aluminum or calcium salts of salicylic 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 terpene phenolic resins or salicylic acid resins which are reaction products of 3,5-bis(α-methylbenzyl)salicylic acid with benzyl chloride.

[0099] Among these, as the color developer, clay substances, metal salts of aromatic carboxylic acids, or metal salts of carboxylated terpene phenol resins are preferred, clay substances or metal salts of aromatic carboxylic acids are more preferred, and clay substances are even more preferred in terms of the excellent effects of the present invention, with acid clay, activated clay, or kaolin being particularly preferred.

[0100] The content of the color developer in the second layer is preferably 20 to 95% by mass, more preferably 30 to 90% by mass, based on the total mass of the second layer, in terms of achieving excellent effects of the present invention.

[0101] The content of the developer in the second layer is 0.1 to 30 g / m 2 is preferred. When the developer is an inorganic compound, the content of the developer in the second layer is 3 to 20 g / m 2 is preferable, and 5 to 15 g / m 2 is more preferred. When the developer is an organic compound, the content of the developer in the second layer is 0.1 to 5 g / m 2is preferable, and 0.2 to 3 g / m 2 is more preferred.

[0102] The second layer may contain other components in addition to the above-mentioned color developer. Examples of other components include polymer binders, pigments, fluorescent whitening agents, antifoaming agents, penetrating agents, ultraviolet absorbers, surfactants, and preservatives. Examples of polymer binders include synthetic polymers and natural polymers such as styrene-butadiene copolymer, polyvinyl acetate, polyacrylic acid ester, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymer, starch, casein, gum arabic, gelatin, carboxymethyl cellulose, and methyl cellulose. Pigments include, for example, ground calcium carbonate, precipitated calcium carbonate, talc, and titanium dioxide.

[0103] The thickness of the second layer is preferably from 1 to 50 μm, more preferably from 2 to 30 μm, in terms of achieving excellent effects of the present invention. Mass per unit area of ​​the second layer (g / m 2 ) is 0.5 to 20 g / m 2 is preferred.

[0104] [Method for forming the second layer] The method for forming the second layer is not particularly limited, and known methods can be used. For example, a method may be used in which a composition for forming the second layer containing a developer is applied onto the second support, and then, if necessary, a drying treatment is carried out. The composition for forming the second layer may be a dispersion in which a developer is dispersed in water or the like. If the developer is an inorganic compound, the dispersion in which the developer is dispersed can be prepared by mechanically dispersing the inorganic compound in water. If the developer is an organic compound, the dispersion 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 can be contained in the second layer described above.

[0105] The method for applying the composition for forming the second layer is not particularly limited, but examples include a method using the coater used for applying the composition for forming the first layer described above.

[0106] After the second layer-forming composition is applied to the second support, the coating may be subjected to a drying treatment, such as a heating treatment, if necessary.

[0107] Although the method of forming the second layer on the second support has been described above, the present invention is not limited to the above embodiment. For example, after the second layer is formed on the temporary support, the temporary support may be peeled off to form a second sheet made of the second layer. The temporary support is not particularly limited as long as it is a releasable support.

[0108] As described above, the first sheet and the second sheet are used by laminating the first sheet and the second sheet so that the first layer of the first sheet faces the second layer of the second sheet to obtain a laminate, and then applying pressure to the laminate. In other words, the first sheet corresponds to a sheet used to measure pressure together with the second sheet. The L of the colored part when the above laminate is subjected to pressure to develop color. * a * b * Although there are no particular restrictions on the chromaticity in the color system, from the viewpoint of ease of visual recognition of the color development, chromaticity a * is preferably more than 30 and not more than 80, and the chromaticity b * is preferably greater than -50 and equal to or less than 50. When measuring the chromaticity, the first sheet and the second sheet of the laminate are peeled off after pressure is applied, and the chromaticity of the color-developing portion of the second sheet is measured using a densitometer RD-19 (manufactured by GretagMacbeth). If the second sheet includes a transparent second support and the chromaticity of the color-developing portion can be measured from the second support side, the chromaticity of the color-developing portion may be measured from the second support side.

[0109] <Other materials> The second sheet may have other members in addition to the members described above. For example, the second sheet may have an adhesive layer between the second support and the second layer to enhance adhesion between them. An example of the adhesive layer is the adhesive layer that the first sheet may have.

[0110] Second Embodiment FIG. 3 is a cross-sectional view of one embodiment of the pressure measurement sheet. The pressure measurement sheet 30 has a support 32, a second layer 20 containing a color developer, and a first layer 14 containing predetermined microcapsules 13 in this order. 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, causing the microcapsules 13 to break in the pressurized area, causing the color former encapsulated in the microcapsules 13 to come out of the microcapsules 13 and causing a color-developing reaction between the microcapsules 13 and the color developer in the second layer 20. As a result, color develops in the pressurized area.

[0111] As will be described later, the pressure measurement sheet 30 only needs to have the first layer 14 and the second layer 20, and does not necessarily have to have the support 32. 3, the support 32 and the second layer 20 are directly laminated together, but the present invention is not limited to this. As will be described later, another layer (for example, an adhesive layer) may be disposed between the support 32 and the second layer 20. 3, the pressure measurement sheet 30 has the support 32, the second layer 20, and the first layer 14 in this order, but is not limited to this. The pressure measurement sheet may have the support 32, the first layer 14, and the second layer 20 in this order.

[0112] When the pressure measurement sheet is heated at 220°C for 10 minutes, it is preferable that the heat shrinkage rate Sb1 in the longitudinal direction of the pressure measurement sheet and the heat shrinkage rate Sb2 in the width direction perpendicular to the longitudinal direction of the pressure measurement sheet 22 are both -0.5 to 3.0%. The method for measuring the thermal shrinkage rates Sb1 and Sb2 of the pressure measurement sheet is the same as the method for measuring the thermal shrinkage rates Sa1 and Sa2 of the first sheet described above, except that the measurement object is changed to a pressure measurement sheet.

[0113] The first layer 14 and the second layer 20 in the pressure measurement sheet 30 are made of the same materials as the first layer 14 and the second layer 20 described in the first embodiment above, and therefore a description thereof will be omitted. The following mainly describes the support 32 in detail.

[0114] [Support] The support is a member for supporting the first layer and the second layer. Note that if the laminate of the first layer and the second layer can be handled by itself, the pressure measurement sheet does not need to have a support. The preferred embodiment of the support is the same as the preferred embodiment of the first support described above, and therefore the explanation will be omitted.

[0115] [Manufacturing method of pressure measurement sheet] The method for producing the pressure measurement sheet is not particularly limited, and known methods can be used. For example, a method may be used in which a composition for forming a second layer containing a developer is applied onto a support, and if necessary, a drying treatment is carried out to form a second layer on the support, and then a composition for forming a first layer containing predetermined microcapsules is applied onto the second layer, and if necessary, a drying treatment is carried out to form a first layer. The method for forming the microcapsules is as described above. 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 as described in the first embodiment.

[0116] <Other materials> The pressure measurement sheet may include other members in addition to the members described above. For example, the pressure measurement sheet may have an adhesive layer between the support and the second layer to enhance adhesion between them. An example of the adhesive layer is the adhesive layer that the first sheet may have.

[0117] [Application] The pressure measurement sheet set of the present invention can be used for various purposes, such as verifying or managing various manufacturing processes that involve high-temperature pressing. More specifically, it can be used to check the pressure distribution in the lamination process in the field of batteries (lithium ion batteries, fuel cells), in the lamination process in the field of printed wiring boards (FPC, BWB), in thermocompression bonding processes such as ACF bonding and lamination of wiring extraction parts, and in checking the pressure distribution in mold clamping parts.

[0118] Third Embodiment A third embodiment includes a dispersion liquid (hereinafter simply referred to as "first dispersion liquid") containing microcapsules encapsulating a color former, which is used to form a layer to be used in combination with a layer containing a color developer (dispersion liquid for forming a pressure measurement layer).

[0119] [First dispersion] The first dispersion is a dispersion of microcapsules containing microcapsules encapsulating a color former containing a specific compound, the microcapsule walls of which have a thermal decomposition temperature of 250° C. or higher. The components contained in the first dispersion have the same meanings as the components contained in the first layer described above, and the preferred ranges are also the same. The first dispersion may be, for example, the above-described composition for forming the first layer. The first dispersion preferably contains a solvent, such as water or an organic solvent. The first dispersion liquid is used to form a layer (corresponding to the first layer described above) used for pressure measurement, similar to the first layer-forming composition.

[0120] [Second dispersion] The first dispersion may be used in combination with a dispersion used to form a layer containing a color developer (hereinafter simply referred to as a "second dispersion"), that is, the first dispersion and the second dispersion may be used as a set (a dispersion set). The second dispersion is a dispersion containing a color developer. The components contained in the second dispersion have the same meanings as the components contained in the second layer described above, and the preferred ranges are also the same. The second dispersion may be, for example, the above-described composition for forming the second layer. The second dispersion preferably contains a solvent, such as water or an organic solvent.

[0121] It is preferable that the first dispersion does not contain coarse particles, in order to prevent clogging when the first dispersion is used by applying it by spraying or the like. From the above viewpoints, the volume-based median diameter (D50) of the microcapsules is preferably from 1 to 80 μm, more preferably from 5 to 70 μm, and even more preferably from 10 to 50 μm. From the above viewpoint, it is preferable that the second dispersion does not contain coarse particles. From the above viewpoints, the color developer contained in the second dispersion is preferably an organic compound. As the organic compound, a metal salt of an aromatic carboxylic acid is preferable, a metal salicylate is more preferable, and a zinc salicylate is even more preferable.

[0122] The first dispersion can be applied to objects for which pressure measurement is difficult using a pressure measurement sheet set or the like. More specifically, pressure measurement is made possible by applying only the required amount of the first dispersion to the area of ​​the object requiring pressure measurement, regardless of the surface shape of the object, and forming a layer containing the microcapsules in that area. This is particularly suitable for measuring pressure on curved surfaces.

[0123] [Fourth embodiment] A fourth embodiment is a dispersion liquid (hereinafter simply referred to as the "third dispersion liquid") containing microcapsules containing a color former and a color developer, which is used to form a layer for pressure measurement (dispersion liquid for forming a pressure measurement layer). The components contained in the third dispersion have the same meanings as the components contained in the first or second layer described above, and the preferred ranges are also the same. The microcapsules contained in the third dispersion may be in the form of the microcapsules contained in the composition for forming the first layer. The developer contained in the third dispersion may be the same as the developer contained in the second layer forming composition. The third dispersion preferably contains a solvent, such as water or an organic solvent. Examples of the third dispersion include a form in which a developer is mixed with the above-mentioned composition for forming the first layer, and a form in which the above-mentioned composition for forming the second layer is mixed with the composition for forming the first layer.

[0124] It is preferable that the third dispersion does not contain coarse particles, in order to prevent clogging when the first dispersion is used by application such as spraying. From the above viewpoint, the volume-based median diameter (D50) of the microcapsules is preferably 1 to 50 μm. From the above viewpoints, the color developer contained in the third dispersion is preferably an organic compound. As the organic compound, a metal salt of an aromatic carboxylic acid is preferable, a metal salicylate is more preferable, and a zinc salicylate is even more preferable.

[0125] The third dispersion liquid contains microcapsules encapsulating a color former and a developer, so that pressure can be measured using only the layer formed by applying the third dispersion liquid. That is, the third dispersion can be applied to objects for which pressure measurement is difficult using sheets such as a pressure measurement sheet set and a pressure measurement sheet, as with the first dispersion and the second dispersion. More specifically, pressure measurement is made possible by applying only the required amount of the third dispersion to an area of ​​the pressure measurement object where pressure measurement is required, and forming a layer in that area, regardless of the surface shape of the pressure measurement object.

[0126] The first dispersion, second dispersion, and third dispersion described above are mainly used for pressure measurement in automobile manufacturing, high-temperature heat pressing, heat pressing, bonding, and the like, but can also be used for various other purposes. For example, in the manufacture of vehicles such as automobiles or aircraft, confirmation of pressure distribution during molding or assembly of various components, bodies, etc., confirmation of pressure distribution during assembly of building materials, confirmation of pressure distribution during processes such as curved surface processing of electronic products, confirmation of impact force applied to cargo during transportation, confirmation of mold contact in the manufacture of metal products, confirmation of mold contact during molding of resin products, confirmation of pressure distribution during tablet compression in pharmaceuticals, confirmation of pressure distribution on furniture surfaces such as sofa seats, confirmation of pressure on stationery such as checking the gripping force applied to writing instruments, confirmation of impact force applied to sports equipment such as balls made of elastic material, and confirmation of the gap (clearance) between upper and lower teeth in dental products. [Example]

[0127] The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below. In the following, "parts" and "%" are based on mass unless otherwise specified.

[0128] Example 1 [Preparation of color former-encapsulated microcapsules] Solution A was obtained by dissolving 3',6'-bis(diethylamino)-2-(4-nitrophenyl)spiro[isoindole-1,9'-xanthene]-3-one (Pink-DCF, Hodogaya Chemical Co., Ltd.) (3 parts by mass) and 6'-(diethylamino)-1',3'-dimethylfluoran (Orange-DCF, Hodogaya Chemical Co., Ltd.) (4 parts by mass) as color formers and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (JF-77-P, Johoku Chemical Co., Ltd.) (3 parts by mass) as an ultraviolet absorber in 50 parts by mass of 1,1-diphenylethane (SAS-296, JXTG Nippon Oil & Energy Corporation). Next, synthetic isoparaffin (IP Solvent 1620, manufactured by Idemitsu Kosan Co., Ltd.) (13 parts by mass) was added to the stirred solution A to obtain solution B. Furthermore, a trimethylolpropane adduct of tolylene diisocyanate (Burnoc D-750, manufactured by DIC Corporation, solids concentration 75% by mass) (1.6 parts by mass) dissolved in ethyl acetate (6 parts by mass) and Millionate MR-200 (manufactured by Tosoh Corporation) (3.7 parts by mass) were added to the stirred solution B to obtain solution C. Millionate MR-200 is a mixture of diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate. Solution C was then added to a solution of polyvinyl alcohol (JP-45, manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) (4 parts by mass) dissolved in water (140 parts by mass) to form an emulsion. Water (200 parts by mass) 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. Further water was added to adjust the concentration, and a liquid of color former-encapsulating microcapsules with a solid content of 25% was obtained. The volume-based median diameter (D50) of the obtained color former-encapsulating microcapsules was 20 μm. The volume-based median diameter (D50) was measured using an optical microscope by the method described above.

[0129] [Preparation of pressure measurement sheet set] <Preparation of the first sheet> A color former-encapsulated microcapsule liquid (solid content concentration 25%) (43 parts by mass), water (15 parts by mass), colloidal silica (Nissan Chemical Industries, Ltd., Snowtex (registered trademark) 30, solid content concentration 30%) (5.7 parts by mass), a 10% by mass aqueous solution of Polymaron 482 (Arakawa Chemical Industries, Ltd.) (1.8 parts by mass), a 10% by mass aqueous solution of carboxymethylcellulose Na (Dai-ichi Kogyo Seiyaku Co., Ltd., Cellogen EP) (24 parts by mass), a 1% by mass aqueous solution of Rapisol A-90 (NOF Corporation) (0.7 parts by mass), and a 1% by mass aqueous solution of Noigen LP-70 (Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyalkylene alkyl ether surfactant) (0.7 parts by mass) were mixed and stirred for 2 hours to obtain a composition for forming a first layer.

[0130] Furthermore, an adhesion layer-forming composition containing styrene butadiene latex was applied to a 75 μm thick polyethylene naphthalate sheet (Teonex (registered trademark) Q53, manufactured by Teijin Film Solutions Co., Ltd.) serving as the first support, and dried to form an adhesion layer having a thickness of 100 nm on the first support, thereby obtaining a first support having an adhesion layer. The above-mentioned first layer forming composition was applied onto the adhesion layer of the first support having the obtained adhesion layer using a bar coater and dried to form a first layer of approximately 500 nm, thereby producing a first sheet.

[0131] <Preparation of the second sheet> A dispersion was prepared by dispersing a mixture of sulfuric acid-treated activated clay (200 parts by mass), sodium hexametaphosphate (1 part by mass), a 10% by mass aqueous solution of sodium hydroxide (30 parts by mass), and water (290 parts by mass) using a sand grinder so that the average particle size of all particles was 2 μm. Next, the obtained dispersion was mixed with 180 parts by mass of a 19% by mass aqueous dispersion of Nippol LX-814 (manufactured by Zeon Corporation), 220 parts by mass of a 3.3% by mass aqueous solution of Polymaron 482 (manufactured by Arakawa Chemical Industries, Ltd.), 80 parts by mass of a 1% by mass aqueous solution of carboxymethylcellulose Na (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Cellogen EP), 4.7 parts by mass of a 15% by mass aqueous solution of sodium alkylbenzene sulfonate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen T), and 70 parts by mass of a 1% by mass aqueous solution of Noigen LP70 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., polyoxyalkylene alkyl ether surfactant), to obtain a composition for forming a second layer. The composition for forming the second layer was applied to a 75 μm-thick polyethylene naphthalate sheet (Teonex (registered trademark) Q53, manufactured by Teijin Film Solutions Co., Ltd.) as the second support in a solid content coating amount of 12.0 g / m 2 The coating was then dried to form a second layer, thereby obtaining a second sheet.

[0132] [Examples 2 to 24, Comparative Examples 1 to 2, Reference Examples 1 to 2] As shown in Table 1, the first and second sheets of each example, comparative example, and reference example were prepared according to the same procedure as in Example 1, except that various conditions such as each material and the content of each material were changed. Comparative Example 1 was based on Comparative Example 1 described in Patent Document 2. Comparative Example 2 was based on Example 13 described in Patent Document 3.

[0133] Comparative Example 3 As in the example described in Patent Document 1, Prescale LLW (manufactured by Fujifilm Corporation) was used as the pressure measurement sheet set.

[0134] [Measurement and Evaluation] [High temperature suitability] The first sheet obtained in the above (Preparation of the First Sheet) and the second sheet obtained in the above (Preparation of the Second Sheet) cut to a size of 5 cm x 5 cm were overlapped with the surface of the color-forming layer of the first sheet facing the surface of the color-developing layer of the second sheet to obtain a laminate. The obtained laminate was placed on a hot plate at 200°C, and a 5 mm wide ring-shaped SUS mold was placed on top of the laminate. A pressure of 2.5 MPa was applied for 5 seconds. The obtained laminate was then removed from the hot plate, and the overlapping first and second sheets were peeled off. The shape of the color-forming region of the second sheet was visually inspected and evaluated according to the following evaluation criteria. In addition, the shape of the color-developed area of ​​the second sheet was visually confirmed in the same manner as above, except that the pressure measurement time was changed to 2 minutes, and evaluated according to the following evaluation criteria. (Evaluation criteria) A: In both cases where the pressure measurement time was 5 seconds and 2 minutes, the shape of the colored area was clearly recognizable as a ring shape similar to that of the SUS mold, and no change was observed in the color of the colored area when the pressure measurement time was 5 seconds and when the pressure measurement time was 2 minutes. B: In both cases where the pressure measurement time was 5 seconds and 2 minutes, the outline of the colored area under pressure was somewhat unclear, but it was recognizable as a ring shape similar to that of the SUS mold, and no change in color was observed between the colored area when the pressure measurement time was 5 seconds and when the pressure measurement time was 2 minutes. C: In both cases where the pressure measurement time was 5 seconds and 2 minutes, the outline of the colored area under pressure was unclear, and although there were some areas where the shape of the colored area was not recognizable as a ring shape similar to that of the SUS mold, in most areas it was recognizable as a link shape similar to that of the SUS mold, and no change was observed in the color of the colored area when the pressure measurement time was 5 seconds and when the pressure measurement time was 2 minutes. D: In both cases where the pressure measurement time was 5 seconds and 2 minutes, it was not possible to recognize that the colored area had the same link shape as the SUS mold, and a change in color was observed between the colored area when the pressure measurement time was 5 seconds and the colored area when the pressure measurement time was 2 minutes.

[0135] [Gradation at high temperatures] The first sheet obtained in the above (Preparation of the first sheet) and a second sheet obtained by cutting the second sheet obtained in the above (Preparation of the second sheet) to a size of 5 cm x 5 cm were overlapped with the surface of the color-forming layer of the first sheet facing the surface of the color-developing layer of the second sheet, and the obtained sheets were pressed using a hot press at a temperature of 200°C and a pressure of 0.5 MPa, 1.5 MPa, or 2.5 MPa to develop color. Next, the overlapping first and second sheets were peeled off, and the density (DA) of the colored portion of the obtained second sheet was measured at each pressure using a densitometer RD-19 (manufactured by GretagMacbeth).

[0136] Separately, the initial density (DB) of an unused second sheet was measured using the same method as above. The initial density (DB) was then subtracted from the density (DA) of the colored area at each pressure to determine the color density ΔD, which was then evaluated according to the following evaluation criteria. A rating of "B" indicates a range that is practically acceptable. (Evaluation criteria) A: ΔD is 0.4 or more at pressures of 0.5 MPa, 1.5 MPa, and 2.5 MPa. B: At two of the pressures of 0.5 MPa, 1.5 MPa, and 2.5 MPa, ΔD is 0.1 or more and less than 0.4 C: At pressures of 0.5 MPa, 1.5 MPa, and 2.5 MPa, ΔD is less than 0.1 for two of them.

[0137] [Lightfastness after color development] The first sheet obtained in the above (Preparation of the First Sheet) and the second sheet obtained in the above (Preparation of the Second Sheet) cut to a size of 5 cm x 5 cm were overlapped with the surface of the color-forming layer of the first sheet facing the surface of the color-developing layer of the second sheet. The resulting sheets were pressed using a hot press at a temperature of 200°C and a pressure of 1.0 MPa to develop color. The overlapping first and second sheets were then removed from the hot plate and peeled away. Images of the colored portion of the second sheet were scanned using an image analysis system FPD-8010J manufactured by FUJIFILM Corporation. The resulting second sheet was then stored at room temperature for one week. Images of the colored portion of the second sheet after storage were then scanned in the same manner, and the image data before and after one week were compared and evaluated according to the following evaluation criteria. (Evaluation criteria) A: The color and density have not changed. B: At least one of the color and density had changed.

[0138] [Thermal decomposition temperature] The thermal decomposition temperature of the capsule wall of the microcapsule was measured by the method described above.

[0139] [Thermal shrinkage measurement] Three samples were prepared by cutting the first sheet produced in each example, comparative example, and reference example so that the length along the longitudinal direction of the first sheet was 150 mm and the length along the width direction was 20 mm. A marked line was marked at position A, approximately 25 mm from the center point (starting point) of one short side of the sample toward the center point of the other short side in a direction parallel to the long side, and at position B, approximately 25 mm from the center point (starting point) of the other short side toward the center point of one short side in a direction parallel to the long side. At this time, the distance between positions A and B (the distance between the marked lines) was 100 mm ± 2 mm. This was used as a sample for measuring the thermal shrinkage rate Sa1 in the longitudinal direction of the first sheet. The obtained measurement sample was heated at 220°C for 10 minutes, and then returned to room temperature (23°C). The distance between the marked lines on the measurement sample was measured, and the thermal shrinkage rate Sa3 was calculated according to the following formula. Heat shrinkage rate Sa3 [%] = 100 × {(distance between gauge lines on measurement sample before heating) - (distance between gauge lines on measurement sample after heating)} / (distance between gauge lines on measurement sample before heating) The arithmetic mean value of the heat shrinkage percentages Sa3 of the three measurement samples was calculated and designated as the heat shrinkage percentage Sa1. The distance between the benchmark lines was measured to the nearest 0.1 mm.

[0140] Furthermore, the first sheet produced in each example was cut into three samples, each measuring 150 mm in the width direction and 20 mm in the longitudinal direction of the first sheet. Marked lines were then drawn on the surface of each sample in the same manner as for the sample for measuring the thermal shrinkage rate Sa1. This was used as a sample for measuring the thermal shrinkage rate Sa2 in the width direction of the first sheet. The obtained measurement sample was heated at 220°C for 10 minutes, and then returned to room temperature (23°C). The distance between the marked lines of the measurement sample was measured, and the thermal shrinkage rate Sa4 was calculated according to the following formula. Heat shrinkage rate Sa4 [%] = 100 × {(distance between gauge lines on measurement sample before heating) - (distance between gauge lines on measurement sample after heating)} / (distance between gauge lines on measurement sample before heating) The arithmetic mean value of the heat shrinkage percentages Sa4 of the three measurement samples was calculated and designated as the heat shrinkage percentage Sa2. The distance between the benchmark lines was measured to the nearest 0.1 mm. In all examples, when the first sheet was heated at 220°C for 10 minutes, the heat shrinkage rate Sa1 in the longitudinal direction of the first sheet and the heat shrinkage rate Sa2 in the width direction of the first sheet perpendicular to the longitudinal direction were both in the range of -0.5 to 3.0.

[0141] In Table 1, each material is as follows. [Various materials] [resin] Polyurethane urea melamine resin

[0142] <Wall material A> D-750: Trimethylolpropane adduct of tolylene diisocyanate (manufactured by DIC Corporation, Burnock D-750, solids concentration 75% by mass), corresponds to Polyisocyanate A. melamine

[0143] <Wall material B> MR-200: Millionate MR-200 (manufactured by Tosoh Corporation), which corresponds to Polyisocyanate B. Formaldehyde

[0144] [Color former] <Specific compound> Orange-DCF: the following compound (6'-(diethylamino)-1',3'-dimethylfluoran, manufactured by Hodogaya Chemical Co., Ltd.) RED500: The following compound RED520: the following compound RED550: the following compound

[0145] [ka]

[0146] <Other color formers> Pink-DCF: the following compound (3',6'-bis(diethylamino)-2-(4-nitrophenyl)spiro[isoindole-1,9'-xanthene]-3-one, manufactured by Hodogaya Chemical Co., Ltd.) Color former A: 3,3-bis(2-methyl-1-octyl-3-indolyl)phthalide Color former B: the following compound

[0147] [ka]

[0148] In Table 1, the column "mass ratio (A) / (B)" indicates the mass ratio of the mass of wall material A to the mass of wall material B (mass of wall material A / mass of wall material B). The compounds listed in the "Specific Compound (a)" column are compounds that fall under the category of compounds represented by formula (1). The compounds listed in the "Other Color Formers (b)" column are color formers that do not fall under the category of compounds represented by formula (1). The column "Mass ratio (a) / (b)" indicates the mass ratio of the mass of the specific compound (a) to the mass of the other color former (b) (mass of the specific compound (a) / mass of the other color former (b)).

[0149] [Table 1]

[0150] As shown in Table 1, it was confirmed that the desired effects were obtained when the pressure measurement sheet set of the present invention was used. From a comparison of Examples 1 to 6, it was confirmed that the effects of the present invention are better when the thermal decomposition temperature of the capsule wall is above 250°C, and that the effects of the present invention are even better when the thermal decomposition temperature of the capsule wall is 260°C or higher. From a comparison of Examples 6 to 10, it was confirmed that when the content of the specific compound was 70% by mass or more relative to the total mass of the color former, the light resistance after color development was excellent. From a comparison between Examples 6 and 12 to 16, it was confirmed that the effect of the present invention is more excellent when the capsule wall thickness of the microcapsules is 80 to 300 nm. Furthermore, similar comparisons confirmed that when the capsule wall thickness of the microcapsules is 80 to 250 nm, the gradation at high temperatures is excellent, and when it is 100 to 200 nm, the gradation at high temperatures is even better. [Explanation of symbols]

[0151] 10 Pressure measurement sheet set 12 First support 14 1st layer 16 Sheet 1 18 Second support 20 2nd layer 22 Second Sheet 30 Pressure measurement sheet 32 Support 20 2nd layer 22 Second Sheet 30 Pressure measurement sheet 32 Support

Claims

1. a first sheet having a first support and a first layer containing microcapsules encapsulating a color former; A sheet set for pressure measurement comprising a second sheet having a second support and a second layer containing a color developer, the thickness of the first support and the thickness of the second support are each 10 to 200 μm; the color former comprises a compound represented by formula (1), The thermal decomposition temperature of the capsule wall of the microcapsule is 250°C or higher, A sheet set for pressure measurement, wherein the capsule walls of the microcapsules contain polyurethane urea having a polymethylene polyphenylene structure. 【Chemistry 1】 In formula (1), R １ represents an alkyl group which may have a substituent. ３ is -NR Ａ R Ｂ Represents R Ａ and R Ｂ R each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. ２ and R ４ each independently represents a halogen atom; Q represents a benzene ring or a naphthalene ring; X represents —O— or —NR ５ - represents. ５ represents an alkyl group which may have a substituent or an aryl group which may have a substituent. p and q each independently represent an integer of 0 to 4. r represents an integer of 1 to 3. s represents an integer of 0 to 3. However, p+q is an integer of 0 to 4, and r+s is an integer of 1 to 4.

2. 2. The pressure measurement sheet set according to claim 1, wherein, when the first sheet is heated at 220°C for 10 minutes, the thermal shrinkage rate Sa1 in the longitudinal direction of the first sheet and the thermal shrinkage rate Sa2 in the width direction perpendicular to the longitudinal direction of the first sheet are both -0.5 to 3.0%.

3. The sheet set for pressure measurement according to claim 1 or 2, wherein the capsule walls of the microcapsules contain a resin having Structure A or Structure B. Structure A: A structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate. Structure B: A structure obtained by reacting melamine with formaldehyde.

4. The sheet set for pressure measurement according to any one of claims 1 to 3, wherein the thickness of the capsule wall of the microcapsules is 80 to 300 nm.

5. The sheet set for pressure measurement according to any one of claims 1 to 4, wherein the content of the compound represented by formula (1) is 70 mass % or more with respect to the total mass of the color former.

6. A pressure measurement sheet having a first layer including microcapsules encapsulating a color former, a second layer including a color developer, and a support having the first layer and the second layer laminated on one side thereof, the color former comprises a compound represented by formula (1), The thermal decomposition temperature of the capsule wall of the microcapsule is 250°C or higher, The pressure measurement sheet, wherein the capsule walls of the microcapsules contain polyurethane urea having a polymethylene polyphenylene structure. 【Chemistry 2】 In formula (1), R １ represents an alkyl group which may have a substituent. ３ is -NR Ａ R Ｂ Represents R Ａ and R Ｂ R each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. ２ and R ４ each independently represents a halogen atom; Q represents a benzene ring or a naphthalene ring; X represents —O— or —NR ５ - represents. ５ represents an alkyl group which may have a substituent or an aryl group which may have a substituent. p and q each independently represent an integer of 0 to 4. r represents an integer of 1 to 3. s represents an integer of 0 to 3. However, p+q is an integer of 0 to 4, and r+s is an integer of 1 to 4.

7. 7. The pressure measurement sheet according to claim 6, wherein, when the pressure measurement sheet is heated at 220°C for 10 minutes, a heat shrinkage rate Sb1 in the longitudinal direction of the pressure measurement sheet and a heat shrinkage rate Sb2 in the width direction perpendicular to the longitudinal direction of the pressure measurement sheet are both −0.5 to 3.0%.

8. 8. The pressure measurement sheet according to claim 6, wherein the capsule walls of the microcapsules contain a resin having Structure A or Structure B. Structure A: A structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate. Structure B: A structure obtained by reacting melamine with formaldehyde.

9. The pressure measurement sheet according to any one of claims 6 to 8, wherein the capsule wall thickness of the microcapsules is 80 to 300 nm.

10. The pressure measurement sheet according to any one of claims 6 to 9, wherein the content of the compound represented by formula (1) is 70 mass % or more with respect to the total mass of the color former.

11. A microcapsule encapsulating a color former, the color former comprises a compound represented by formula (1), The thermal decomposition temperature of the capsule wall of the microcapsule is 250°C or higher, A microcapsule, wherein the capsule wall of the microcapsule comprises a polyurethane urea having a polymethylene polyphenylene structure. 【Transformation 3】 In formula (1), R １ represents an alkyl group which may have a substituent. ３ is -NR Ａ R Ｂ Represents R Ａ and R Ｂ R each independently represents an alkyl group which may have a substituent or an aryl group which may have a substituent. ２ and R ４ each independently represents a halogen atom; Q represents a benzene ring or a naphthalene ring; X represents —O— or —NR ５ - represents. ５ represents an alkyl group which may have a substituent or an aryl group which may have a substituent. p and q each independently represent an integer of 0 to 4. r represents an integer of 1 to 3. s represents an integer of 0 to 3. However, p+q is an integer of 0 to 4, and r+s is an integer of 1 to 4.

12. 12. The microcapsule of claim 11, wherein the capsule wall of the microcapsule comprises a resin having Structure A or Structure B. Structure A: A structure obtained by reacting an aromatic or alicyclic diisocyanate, a compound having three or more active hydrogen groups in one molecule, and polymethylene polyphenyl polyisocyanate. Structure B: A structure obtained by reacting melamine with formaldehyde.

13. The microcapsules according to claim 11 or 12, wherein the thickness of the capsule wall of the microcapsules is 80 to 300 nm.

14. The microcapsule according to any one of claims 11 to 13, wherein the content of the compound represented by formula (1) is 70 mass% or more relative to the total mass of the color former.

15. A dispersion comprising the microcapsules according to any one of claims 11 to 14.

16. A method for producing a sheet set for pressure measurement according to any one of claims 1 to 5, comprising a step of forming the first layer using the dispersion according to claim 15.

17. A method for producing the pressure measurement sheet according to any one of claims 6 to 10, comprising the step of forming the first layer using the dispersion according to claim 15.

Images