阅读说明：本技术 压力测量用片材组、压力测量用片材 (Pressure measurement sheet set and pressure measurement sheet ) 是由 加藤进也 于 2020-06-25 设计创作，主要内容包括：本发明的课题为提供一种在高温环境下使用时能够测量精确的压力分布的压力测量用片材组及压力测量用片材。本发明的压力测量用片材组具备：第1片材,其具有第1支承体及配置于第1支承体上且包含内含发色剂的微胶囊的第1层；及第2片材,其具有第2支承体及配置于第2支承体上且包含显色剂的第2层,其中,将第1片材及第2片材在220℃下加热10分钟的情况下,第1片材及第2片材的长度方向上的收缩率S1以及第1片材及第2片材的与长度方向正交的宽度方向上的收缩率S2均为-0.5～2.0％。(The invention provides a pressure measurement sheet set and a pressure measurement sheet capable of measuring accurate pressure distribution when used in a high-temperature environment. The pressure measurement sheet set of the present invention includes: a 1 st sheet having a 1 st support and a 1 st layer disposed on the 1 st support and containing microcapsules containing a color former; and a 2 nd sheet having a 2 nd support and a 2 nd layer containing a color developer and disposed on the 2 nd support, wherein, when the 1 st sheet and the 2 nd sheet are heated at 220 ℃ for 10 minutes, the shrinkage rates S1 in the longitudinal direction of the 1 st sheet and the 2 nd sheet and the shrinkage rates S2 in the width direction orthogonal to the longitudinal direction of the 1 st sheet and the 2 nd sheet are both-0.5 to 2.0%.)

1. A pressure measurement sheet set is provided with:

a 1 st sheet having a 1 st support and a 1 st layer disposed on the 1 st support and containing microcapsules containing a color former; and

a 2 nd sheet comprising a 2 nd support and a 2 nd layer containing a color-developer disposed on the 2 nd support,

when the 1 st sheet is heated at 220 ℃ for 10 minutes, the shrinkage rate S1 in the longitudinal direction of the 1 st sheet and the shrinkage rate S2 in the width direction of the 1 st sheet orthogonal to the longitudinal direction are both-0.5% to 2.0%,

when the 2 nd sheet was heated at 220 ℃ for 10 minutes, the shrinkage rate S1 in the longitudinal direction of the 2 nd sheet and the shrinkage rate S2 in the width direction of the 2 nd sheet orthogonal to the longitudinal direction were both-0.5% to 2.0%.

2. The pressure-measuring sheet set according to claim 1,

the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the 1 st sheet and the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 in the 2 nd sheet are both 0% to 0.8%.

3. The pressure-measuring sheet set according to claim 1 or 2,

the color developing agent is a clay substance.

4. The set of pressure-measuring sheets according to any one of claims 1 to 3,

the thickness of the 1 st support and the 2 nd support is 25 to 200 μm.

5. The set of pressure-measuring sheets according to any one of claims 1 to 4,

the 1 st support and the 2 nd support are both polyethylene naphthalate films.

6. The set of pressure-measuring sheets according to any one of claims 1 to 5,

the 1 st sheet has an adhesive layer between the 1 st support and the 1 st layer.

7. The set of pressure-measuring sheets according to any one of claims 1 to 6,

the 2 nd sheet has an adhesive layer between the 2 nd support and the 2 nd layer.

8. The set of pressure-measuring sheets according to claim 6 or 7,

the adhesive layer contains a polymer having an aromatic group.

9. A pressure-measuring sheet comprising:

layer 1, which contains microcapsules containing a color former;

a 2 nd layer disposed on the 1 st layer and containing a color developer; and

a support disposed on one surface side of the 1 st layer opposite to the 2 nd layer or on one surface side of the 2 nd layer opposite to the 1 st layer,

when the pressure-measuring sheet was heated at 220 ℃ for 10 minutes, the shrinkage rate S1 in the longitudinal direction of the pressure-measuring sheet and the shrinkage rate S2 in the width direction orthogonal to the longitudinal direction of the pressure-measuring sheet were both-0.5% to 2.0%.

10. The sheet for pressure measurement according to claim 9,

the absolute value of the difference between the shrinkage rate S1 and the shrinkage rate S2 is 0% to 0.8%.

11. The sheet for pressure measurement according to claim 9 or 10,

the color developing agent is a clay substance.

12. The sheet for pressure measurement according to any one of claims 9 to 11,

the thickness of the support is 25 to 200 μm.

13. The sheet for pressure measurement according to any one of claims 9 to 12,

the support is a polyethylene naphthalate film.

14. The sheet for pressure measurement according to any one of claims 9 to 13,

in the case where the support is provided on the side of the 1 st layer opposite to the 2 nd layer, an adhesive layer is provided between the support and the 1 st layer.

15. The sheet for pressure measurement according to any one of claims 9 to 13,

in the case where the support is provided on the side of the layer 2 opposite to the layer 1, an adhesive layer is provided between the support and the layer 2.

16. The sheet for pressure measurement according to claim 14 or 15,

the adhesive layer contains a polymer having an aromatic group.

Technical Field

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

Background

Pressure measurement sheets (i.e., sheets for measuring pressure) are used in applications such as a bonding process of liquid crystal glass, solder printing on a printed circuit board, and adjustment of pressure between rollers.

For example, patent document 1 discloses a pressure measurement sheet utilizing a color development reaction between a color former and a developer, and the pressure measurement sheet can perform measurement in a pressure range of about 0.1MPa to 20 MPa. Further, patent document 2 discloses a pressure measurement sheet that can satisfactorily develop color in a low-pressure region (particularly, a pressure of 3MPa or less) and can satisfactorily read the density.

Prior art documents

Patent document

Patent document 1: japanese patent publication No. 57-24852

Patent document 2: japanese patent No. 4986749

Disclosure of Invention

Technical problem to be solved by the invention

In recent years, measurement of pressure distribution under actual manufacturing conditions has become important. For example, in a bonding operation in various high-temperature environments such as thermocompression bonding of integrated circuits and wirings on printed boards, it is desirable to measure a precise pressure distribution in order to improve the yield.

The present inventors have conducted measurement of pressure distribution in a high-temperature environment (particularly 180 ℃ or higher) using the pressure measurement sheet described in patent documents 1 and 2, and have found that it is impossible to visually recognize or read an accurate pressure distribution and to measure an accurate pressure distribution.

In view of the above circumstances, an object of the present invention is to provide a pressure measurement sheet set and a pressure measurement sheet that can measure an accurate pressure distribution when used in a high-temperature environment.

Means for solving the technical problem

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

[1] A pressure measurement sheet set is provided with:

a 1 st sheet having a 1 st support and a 1 st layer which is disposed on the 1 st support and contains microcapsules containing a color former; and

a 2 nd sheet comprising a 2 nd support and a 2 nd layer containing a color-developer disposed on the 2 nd support,

when the 1 st sheet is heated at 220 ℃ for 10 minutes, the shrinkage ratio S1 in the longitudinal direction of the 1 st sheet and the shrinkage ratio S2 in the width direction of the 1 st sheet orthogonal to the longitudinal direction are both-0.5 to 2.0%,

when the 2 nd sheet is heated at 220 ℃ for 10 minutes, the shrinkage ratio S1 in the longitudinal direction of the 2 nd sheet and the shrinkage ratio S2 in the width direction of the 2 nd sheet orthogonal to the longitudinal direction are both-0.5 to 2.0%.

[2] The pressure-measuring sheet set according to [1], wherein,

the absolute value of the difference between the shrinkage ratio S1 and the shrinkage ratio S2 in the 1 st sheet and the absolute value of the difference between the shrinkage ratio S1 and the shrinkage ratio S2 in the 2 nd sheet are both 0 to 0.8%.

[3] The pressure-measuring sheet set according to [1] or [2], wherein,

the color developing agent is clay substance.

[4] The pressure-measuring sheet set according to any one of [1] to [3], wherein,

the thickness of the No. 1 support and the No. 2 support is 25 to 200 μm.

[5] The pressure-measuring sheet set according to any one of [1] to [4], wherein,

the first support 1 and the second support 2 are both polyethylene naphthalate films.

[6] The pressure-measuring sheet set according to any one of [1] to [5], wherein,

the 1 st sheet has an adhesive layer between the 1 st support and the 1 st layer.

[7] The pressure-measuring sheet set according to any one of [1] to [6], wherein,

the 2 nd sheet has an adhesive layer between the 2 nd support and the 2 nd layer.

[8] The pressure-measuring sheet set according to [6] or [7], wherein,

the adhesive layer contains a polymer having an aromatic group.

[9] A pressure-measuring sheet comprising:

layer 1, which contains microcapsules containing a color former;

a 2 nd layer disposed on the 1 st layer and containing a color developer; and

a support disposed on one surface side of the 1 st layer opposite to the 2 nd layer or on one surface side of the 2 nd layer opposite to the 1 st layer,

when the pressure-measuring sheet is heated at 220 ℃ for 10 minutes, the shrinkage rate S1 in the longitudinal direction of the pressure-measuring sheet and the shrinkage rate S2 in the width direction of the pressure-measuring sheet, which is orthogonal to the longitudinal direction, are both-0.5 to 2.0%.

[10] The pressure-measuring sheet according to [9], wherein,

the absolute value of the difference between the shrinkage ratio S1 and the shrinkage ratio S2 is 0 to 0.8%.

[11] The pressure-measuring sheet according to [9] or [10], wherein,

the color developing agent is clay substance.

[12] The pressure-measuring sheet according to any one of [9] to [11], wherein,

the thickness of the support is 25 to 200 μm.

[13] The pressure-measuring sheet according to any one of [9] to [12], wherein,

the support is a polyethylene naphthalate film.

[14] The pressure-measuring sheet according to any one of [9] to [13], wherein,

in the case where the support is provided on the side of the 1 st layer opposite to the 2 nd layer, an adhesive layer is provided between the support and the 1 st layer.

[15] The pressure-measuring sheet according to any one of [9] to [13], wherein,

in the case where the support is provided on the side of the 2 nd layer opposite to the 1 st layer, an adhesive layer is provided between the support and the 2 nd layer.

[16] The sheet for pressure measurement according to [14] or [15], wherein,

the adhesive layer contains a polymer having an aromatic group.

Effects of the invention

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

Drawings

Fig. 1 is a sectional view of an embodiment of a pressure measurement sheet set.

Fig. 2 is a diagram for explaining a usage form of the pressure measurement sheet set.

Fig. 3 is a sectional view of an embodiment of a pressure-measuring sheet.

Detailed Description

The present invention will be described in detail below.

In the present specification, the numerical range expressed by the term "to" means a range including numerical values before and after the term "to" as a lower limit value and an upper limit value.

In the numerical ranges described in the present specification in stages, an upper limit or a lower limit described in a certain numerical range may be substituted for an upper limit or a lower limit described in another numerical range described in another stage. In the numerical ranges described in the present specification, the upper limit or the lower limit described in a certain numerical range may be replaced with the values shown in the examples.

The various components described later may be used singly in 1 kind or in combination of 2 or more kinds. For example, the polyisocyanate described later may be used alone in 1 kind or in a mixture of 2 or more kinds.

The pressure-measuring sheet set and the pressure-measuring sheet of the present invention are characterized in that, when the 1 st and 2 nd sheets in the pressure-measuring sheet set and the pressure-measuring sheet are heated at 220 ℃ for 10 minutes, the shrinkage rates S1 in the longitudinal direction of the 1 st, 2 nd and pressure-measuring sheets and the shrinkage rates S2 in the width direction perpendicular to the longitudinal direction of the 1 st, 2 nd and pressure-measuring sheets are all-0.5 to 2.0%.

The present inventors have first found a problem that when a pressure distribution at normal temperature (about 23 ℃) is measured, color unevenness does not occur, and a precise pressure distribution cannot be measured in a high-temperature environment, as a result of measurement of the pressure distribution in a high-temperature environment using a conventional pressure measurement sheet. As a result of examining the cause of the problem, it has been found that the support provided to support the layer containing microcapsules and the layer containing the developer is deformed by heat, and thus stress when pressure is applied is strongly applied to the support, not to the microcapsules, and uneven color development occurs.

As a result, the present inventors have found that by using a support having a small shrinkage rate when heated at a high temperature, color unevenness is less likely to occur even in a high-temperature environment and accurate pressure distribution can be measured.

< 1 st embodiment >

Fig. 1 is a sectional view of an embodiment of a pressure measurement sheet set.

The pressure-measuring sheet set 10 includes a 1 st sheet 16 and a 2 nd sheet 22, the 1 st sheet 16 having a 1 st support body 12 and a 1 st layer 14 containing predetermined microcapsules 13 disposed on the 1 st support body 12, and the 2 nd sheet 22 having a 2 nd support body 18 and a 2 nd layer 20 containing a developer disposed on the 2 nd support body 18.

As shown in fig. 2, when the pressure measurement sheet set 10 is used, the 1 st sheet 16 and the 2 nd sheet 22 are stacked and used such that the 1 st layer 14 of the 1 st sheet 16 faces the 2 nd layer 20 of the 2 nd sheet 22. By applying pressure from at least one of the 1 st support body 12 side of the 1 st sheet 16 and the 2 nd support body 18 side of the 2 nd sheet 22 in the obtained laminate, the microcapsules 13 are ruptured in the pressurized region, the color former contained in the microcapsules 13 comes out of the microcapsules 13, and a color developing reaction between the color developers in the 2 nd layer 20 is performed. As a result, color development proceeds in the pressurized region.

In fig. 1, the 1 st support 12 and the 1 st layer 14 are directly stacked, but the present invention is not limited to this embodiment, and another layer (for example, an adhesive layer) may be disposed between the 1 st support 12 and the 1 st layer 14 as described later. In fig. 1, the 2 nd support 18 and the 2 nd layer 20 are directly laminated, but the present invention is not limited to this embodiment, and another layer (for example, an adhesive layer) may be disposed between the 2 nd support 18 and the 2 nd layer 20 as described later.

The following describes in detail the structures of the 1 st sheet 16 and the 2 nd sheet 22 constituting the pressure-measuring sheet set 10.

< No. 1 sheet >)

The 1 st sheet 16 shown in fig. 1 has a 1 st support 12 and a 1 st layer 14 containing microcapsules 13 containing a color former.

When the 1 st sheet 16 is heated at 220 ℃ for 10 minutes, the shrinkage ratio S1 in the longitudinal direction of the 1 st sheet 16 and the shrinkage ratio S2 in the width direction of the 1 st sheet 16 perpendicular to the longitudinal direction are both-0.5 to 2.0%.

The shrinkage ratio S1 in the 1 st sheet 16 is-0.5 to 2.0%, preferably-0.4 to 1.5%, more preferably-0.3 to 1.2%, and still more preferably-0.2 to 0.8%, from the viewpoint of enabling a more precise pressure distribution to be measured.

The shrinkage ratio S2 in the 1 st sheet 16 is-0.5 to 2.0%, preferably-0.4 to 1.5%, more preferably-0.3 to 1.2%, and still more preferably-0.2 to 0.8%, from the viewpoint of enabling a more precise pressure distribution to be measured.

The shrinkage rates S1 and S2 of the 1 st sheet 16 were measured as described in the first example.

The longitudinal direction of the 1 st sheet 16 is the longitudinal direction of the 1 st sheet 16, and specifically, when the 1 st sheet 16 is rectangular, it is the direction along the long side. The width direction of the 1 st sheet 16 is a direction (short-side direction) orthogonal to the longitudinal direction of the 1 st sheet 16, and for example, when the 1 st sheet 16 is rectangular, it is a direction along the short side. However, when the 1 st sheet 16 is square, a direction along an arbitrarily selected side is defined as a longitudinal direction, and a direction along a side orthogonal thereto is defined as a width direction.

In the 1 st sheet 16, the absolute value (| S1-S2|) of the difference between the shrinkage ratio S1 and the shrinkage ratio S2 is preferably 0 to 0.8%, more preferably 0 to 0.6%, and further preferably 0 to 0.4%, from the viewpoint of enabling more precise pressure distribution to be measured.

The 1 st sheet 16 may be a single sheet (single note) or a long sheet.

Hereinafter, each member will be described in detail.

(the 1 st support)

The 1 st support is a member for supporting the 1 st layer.

The 1 st support may have any one of a sheet shape, a film shape, and a plate shape.

The first support 1 is preferably resistant to shrinkage by heating at a high temperature (preferably 180 ℃ or higher, more preferably 200 to 240 ℃). Specifically, the 1 st support more preferably exhibits the same shrinkage rate as the 1 st sheet when heated at 220 ℃ for 10 minutes.

Examples of the 1 st support include a polyethylene naphthalate (PEN) film, a Polyamide (PA) film, a Polyimide (PI) film, a Polysulfone (PSF) film, and a polyether sulfone (PES) film, and the polyethylene naphthalate film is preferable from the viewpoint of suppressing heat shrinkage of the 1 st sheet and enabling measurement of a more precise pressure distribution.

The thickness of the No. 1 support is preferably 10 to 300 μm. From the viewpoint of further improving the effect of the present invention, the thickness is preferably 25 to 300. mu.m, more preferably 25 to 200. mu.m, still more preferably 25 to 150. mu.m, and particularly preferably 38 to 125. mu.m.

In particular, if the thickness of the 1 st support is 25 μm or more, the 1 st sheet can be suppressed from being deformed during pressure measurement, and therefore, the edge of the member pressed against the laminated body of the 1 st sheet and the 2 nd sheet can be suppressed from being strongly pressed against the laminated body of the 1 st sheet and the 2 nd sheet. Thus, since an appropriate pressure is applied to a position corresponding to the edge of the member, a more precise pressure distribution can be measured.

Further, if the thickness of the 1 st support body is 200 μm or less, the 1 st sheet can be suppressed from being bent at the time of pressure measurement, and therefore the pressure measurement sheet set can easily follow the edge of the member of the laminate pressed to the 1 st sheet and the 2 nd sheet. Thus, since an appropriate pressure is applied to a position corresponding to the edge of the member, a more precise pressure distribution can be measured.

(layer 1)

Layer 1 contains microcapsules containing a color former.

Hereinafter, the material constituting the microcapsule will be described in detail.

Microcapsules generally have a core and a capsule wall for containing a core material (a content (also referred to as a content ingredient)) in the core.

In the present invention, the microcapsule contains a color former as a core material (content component). Since the color former is contained in the microcapsule, the color former can be stably present until the microcapsule is broken by pressurization.

Microcapsules have a capsule wall with a core material.

The capsule wall in the microcapsule preferably contains at least 1 resin (hereinafter, also simply referred to as "specific resin") selected from the group consisting of polyurea, polyurethaneurea, and polyurethane.

The capsule wall of the microcapsule is substantially preferably made of a resin (preferably a specific resin). The substantial composition of the resin means that the content of the resin is 90% by mass or more, preferably 100% by mass, based on the total mass of the capsule wall. That is, the capsule wall of the microcapsule is preferably made of a resin.

Preferably, the polyurethane is a reaction product of a polymer having a plurality of urethane bonds and a raw material containing a polyol and a polyisocyanate.

The polyurea is preferably a reaction product of a polymer having a plurality of urea bonds and a raw material containing a polyamine and a polyisocyanate. In addition, in the case where a part of polyisocyanate reacts with water to form polyamine, polyurea can be synthesized using polyisocyanate instead of polyamine.

Preferably, the polyurethaneurea is a reaction product of a raw material containing a polyol, a polyamine, and a polyisocyanate, the raw material having a urethane bond and a urea bond. When the polyol is reacted with the polyisocyanate, a part of the polyisocyanate reacts with water to form a polyamine, and as a result, a polyurethaneurea can be obtained.

The polyisocyanate is a compound having 2 or more isocyanate groups, and examples thereof include aromatic polyisocyanates and aliphatic polyisocyanates, and aromatic polyisocyanates are preferable from the viewpoint of introducing aromatic ring groups into the capsule wall of the microcapsule.

The aromatic polyisocyanate includes aromatic diisocyanates, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2, 6-tolylene diisocyanate, 2, 4-tolylene diisocyanate, naphthalene-1, 4-diisocyanate, diphenylmethane-4, 4 '-diisocyanate, 3' -dimethoxy-biphenyl diisocyanate, 3 '-dimethyldiphenylmethane-4, 4' -diisocyanate, xylylene-1, 4-diisocyanate, xylylene-1, 3-diisocyanate, 4-chloroxylylene-1, 3-diisocyanate, 2-methylxylylene-1, 3-diisocyanate, and the like, 4,4 '-diphenylpropane diisocyanate and 4, 4' -diphenylhexafluoropropane diisocyanate.

The aliphatic polyisocyanate includes aliphatic diisocyanates, for example, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1, 2-diisocyanate, butylene-1, 2-diisocyanate, cyclohexylene-1, 3-diisocyanate, cyclohexylene-1, 4-diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate, 1, 4-bis (isocyanotomethyl) cyclohexane, 1, 3-bis (isocyanotomethyl) cyclohexane, isophorone diisocyanate, lysine diisocyanate, and hydrogenated xylylene diisocyanate.

Further, 2-functional aromatic polyisocyanates and aliphatic polyisocyanates are exemplified in the above, but 3-or more-functional polyisocyanates (for example, 3-functional tri-isocyanates and 4-functional tetra-isocyanates) may be cited as the polyisocyanates.

More specifically, the polyisocyanate includes a biuret or isocyanurate which is a trimer of the above 2-functional polyisocyanate, an adduct (adduct) of a polyol such as trimethylolpropane and the 2-functional polyisocyanate, a formalin condensate of phenylisocyanate, a polyisocyanate having a polymerizable group such as methacryloxyethyl isocyanate, and lysine triisocyanate.

The polyisocyanate is described in "handbook of polyurethane resins" (edited by Yangtze, NIKKAN KOGYO SHIMBON, published by Ltd. (1987)).

Among them, as one of preferable modes of the polyisocyanate, 3-functional or more polyisocyanate is preferable.

Examples of the 3-or more-functional polyisocyanate include a 3-or more-functional aromatic polyisocyanate and a 3-or more-functional aliphatic polyisocyanate.

The 3-or more-functional polyisocyanate is also preferably an adduct (adduct) of an aromatic or alicyclic diisocyanate and a compound having 3 or more active hydrogen groups in 1 molecule (for example, a 3-or more-functional polyol, polyamine, polythiol, or the like), that is, a 3-or more-functional polyisocyanate (a 3-or more-functional polyisocyanate that is an addition type) and a trimer (biuret type or isocyanurate type) of an aromatic or alicyclic diisocyanate, and more preferably a 3-or more-functional polyisocyanate that is the adduct (adduct).

The 3-or more-functional polyisocyanate as the adduct is preferably an adduct of an aromatic or alicyclic diisocyanate and a polyol having 3 or more hydroxyl groups in 1 molecule, that is, a 3-or more-functional polyisocyanate, and more preferably a 3-functional polyisocyanate which is an adduct of an aromatic or alicyclic diisocyanate and a polyol having 3 hydroxyl groups in 1 molecule.

As the adduct, an adduct obtained by using an aromatic diisocyanate is preferably used from the viewpoint that the measurement of the pressure distribution in a high-temperature environment can be performed more favorably.

The polyol is preferably a low-molecular-weight polyol having 3 or more functions as described later, and more preferably trimethylolpropane.

Examples of the additional 3-or more-functional polyisocyanate include TAKENATE (registered trademark) D-102, D-103H, D-103M2, P49-75S, D-110N, D-120N, D-140N, D-160N (manufactured by Mitsui Chemicals, Inc.), DESMODULE (registered trademark) L75, UL57SP (Sumika Bayer Urethane Co., manufactured by Ltd.), CORONATE (registered trademark) HL, HX, L (Nippon Polyurethane Industry Co., manufactured by Ltd.), P301-75E (manufactured by Asahi Kasei CORPORATION), BURNOCK (registered trademark) D-750 (manufactured by DICCORATION).

Among them, the adduct-type 3-or higher-functional polyisocyanate is preferably 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.

Examples of the isocyanurate type 3-or more-functional polyisocyanate include TAKENATE (registered trademark) D-127N, D-170N, D-170HN, D-172N, D-177N, D-204 (manufactured by Mitsui Chemicals, Inc.), SUMIDUR N3300, DESMODULE (registered trademark) N3600, N3900, Z4470BA (Sumika Bayer Urethane Co., Ltd.), CORONATE (registered trademark) HX, HK (manufactured by Nippon Polyurethane Industry Co., Ltd.), Duranate (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, and TSE-100 (manufactured by Asahi Kasei corporation).

Examples of the biuret type 3-or higher-functional polyisocyanate include TAKENATE (registered trademark) D-165N, NP1100 (manufactured by Mitsui Chemicals, Inc.), DESMODULE (registered trademark) N3200(Sumika Bayer Urethane Co., Ltd.), and Duranate (registered trademark) 24A-100 (manufactured by Asahi Kasei corporation).

Also, as the polyisocyanate, polymethylene polyphenyl polyisocyanate is preferable.

The polymethylene polyphenyl polyisocyanate is preferably a compound represented by the formula (X).

[ chemical formula 1]

In formula (1), n represents the number of repeating units. The number of repeating units is an integer of 1 or more, and n is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, from the viewpoint of enabling measurement of the pressure distribution in a high-temperature environment to be performed more favorably.

Examples of the polyisocyanate containing polymethylene polyphenyl polyisocyanate include MILLIONATE MR-100, MILLIONATE MR-200, MILLIONATE MR-400 (manufactured by TOSOH Corporation), WANNATE PM-200, WANNATE PM-400 (manufactured by Wanhua Chemical (Japan) Co., Ltd.), COSMONATE M-50, COSMONATE M-100, COSMONATE M-200, COSMONATE M-300 (manufactured by Mitsui Chemicals, Inc.) and BORONATE M-595 (manufactured by Dow Chemical Japan).

The polyol is a compound having 2 or more hydroxyl groups, and examples thereof include low-molecular polyols (e.g., aliphatic polyols and aromatic polyols), polyvinyl alcohols, polyether polyols, polyester polyols, polylactone polyols, castor oil polyols, polyolefin polyols, and hydroxyl group-containing amine compounds.

The low-molecular-weight polyol is a polyol having a molecular weight of 400 or less, and examples thereof include 2-functional low-molecular-weight polyols such as ethylene glycol, diethylene glycol, and propylene glycol, and 3-or more-functional low-molecular-weight polyols such as glycerin, trimethylolpropane, hexanetriol, pentaerythritol, and sorbitol.

Examples of the hydroxyl group-containing amine compound include an amino alcohol as an alkoxylated derivative of an amino compound. Examples of the aminoalcohol include N, N '-tetrakis [ 2-hydroxypropyl ] ethylenediamine, N' -tetrakis [ 2-hydroxyethyl ] ethylenediamine and the like which are adducts of propylene oxide or ethylene oxide to an amino compound such as ethylenediamine.

The polyamine means a compound having 2 or more amino groups (primary amino groups or secondary amino groups), and examples thereof include aliphatic polyamines such as diethylenetriamine, triethylenetetramine, 1, 3-propylenediamine, and hexamethylenediamine; epoxy compound adducts of aliphatic polyamines; alicyclic polyamines such as piperazine; heterocyclic diamines such as 3, 9-bis-aminopropyl-2, 4,8, 10-tetraoxospiro- (5,5) undecane.

The resin contained in the capsule wall is preferably formed using an adduct of an aromatic or alicyclic diisocyanate and a compound having 3 or more active hydrogen groups in 1 molecule, that is, a polyisocyanate a having 3 or more functions (hereinafter, also simply referred to as "polyisocyanate a") and a polyisocyanate B selected from the group consisting of aromatic diisocyanates and polymethylene polyphenyl polyisocyanates (hereinafter, also simply referred to as "polyisocyanate B").

That is, the capsule wall is preferably a capsule wall containing the resin (at least 1 resin selected from the group consisting of polyurea, polyurethaneurea, and polyurethane) formed using the polyisocyanate a and the polyisocyanate B.

The use of the polyisocyanate A and the polyisocyanate B provides the present invention with more excellent effects. Further, the temperature dependence of color development is also small. The temperature dependency of color development means a characteristic indicating a difference in the degree of color development based on the temperature when pressure is applied to a pressure measurement sheet set (or a pressure measurement sheet described later). More specifically, when the degree of color development is observed by changing the heating temperature in a range of high temperature conditions (180 ℃ or higher) using a pressure-measuring sheet set (or a pressure-measuring sheet described later), the temperature dependence of color development is said to be large when the difference in the degree of color development is large.

The polyisocyanate B may be an aromatic diisocyanate, a polymethylene polyphenyl polyisocyanate, or a mixture of both. Among these, the polyisocyanate B is preferably a mixture of an aromatic diisocyanate and polymethylene polyphenyl polyisocyanate.

In the above mixture, the mass ratio of the polymethylene polyphenyl polyisocyanate to the aromatic diisocyanate (mass of polymethylene polyphenyl polyisocyanate/mass of aromatic diisocyanate) is not particularly limited, but is preferably 0.1 to 10, more preferably 0.5 to 2, and further preferably 0.75 to 1.5.

The viscosity of the polyisocyanate B is not particularly limited, but is preferably 100 to 1000mPa · s from the viewpoint of enabling the pressure distribution in a high-temperature environment to be measured more favorably.

The viscosity is at 25 ℃.

When the polyisocyanate A and the polyisocyanate B are used together, the mass ratio of the polyisocyanate A to the polyisocyanate B (mass of polyisocyanate A/mass of polyisocyanate B) is not particularly limited, but is preferably 98/2 to 20/80, more preferably 80/20 to 20/80, and still more preferably 80/20 to 45/55.

When the mass ratio is within the above range, the measurement of the pressure distribution in the high-temperature environment can be performed more favorably. Further, the temperature dependence of color development is also small.

Preferably the glass transition temperature of the capsule wall of the microcapsule is 150 ℃ or above or the capsule wall does not exhibit a glass transition temperature. That is, it is preferable that the glass transition temperature of the material constituting the capsule wall of the microcapsule is 150 ℃ or higher or that the material constituting the capsule wall of the microcapsule does not exhibit the glass transition temperature.

When the capsule wall of the microcapsule exhibits a glass transition temperature, the temperature is preferably 180 ℃ or higher, and more preferably 200 ℃ or higher, from the viewpoint of enabling measurement of the pressure distribution in a high-temperature environment to be performed more favorably. When the capsule wall of the microcapsule exhibits a glass transition temperature, the upper limit of the temperature is not particularly limited, and the temperature is usually not higher than the thermal decomposition temperature of the capsule wall of the microcapsule, and usually not higher than 250 ℃.

Among them, from the viewpoint of enabling measurement of the pressure distribution in a high-temperature environment to be performed more favorably, it is preferable that the capsule wall of the microcapsule does not exhibit a glass transition temperature.

The phrase "the capsule wall of the microcapsule does not exhibit a glass transition temperature" means that the capsule wall of the microcapsule (the material constituting the capsule wall of the microcapsule) does not exhibit a glass transition temperature up to a temperature (thermal decomposition temperature-5 ℃) obtained by subtracting 5 ℃ from the thermal decomposition temperature of the capsule wall described later. That is, the glass transition temperature does not appear in the range of "25 ℃ to" (thermal decomposition temperature (. degree. C.) -5 ℃).

The method for making the glass transition temperature of the capsule wall of the microcapsule 150 ℃ or higher or the capsule wall not to exhibit the glass transition temperature is not particularly limited, and can be adjusted by appropriately selecting the raw materials for producing the microcapsule. For example, polyurea has a property of exhibiting a high glass transition temperature, and thus there is a method of constituting a capsule wall with polyurea. Further, there may be mentioned a method of increasing the crosslink density in the material constituting the capsule wall. In addition, a method of introducing an aromatic ring group (e.g., benzene ring group) into a material constituting a capsule wall can be also exemplified.

50 No. 1 sheets of 1cm in length by 1cm in width were prepared, and the whole was immersed in 10ml of water and allowed to stand for 24 hours.

The obtained aqueous dispersion of microcapsules was centrifuged at 15000rpm for 30 minutes to collect the microcapsules. Ethyl acetate was added to the separated microcapsules, and further stirred at 25 ℃ for 24 hours. Thereafter, the obtained solution was filtered, and the obtained residue was vacuum-dried at 60 ℃ for 48 hours, whereby microcapsules (hereinafter, also simply referred to as "measurement material") not containing any inside were obtained. That is, the capsule wall material of the microcapsule to be measured for the glass transition temperature can be obtained.

Next, the thermal decomposition temperature of the obtained measurement material was measured using a thermogravimetric differential thermal analysis apparatus TG-DTA (apparatus name: DTG-60, Shimadzu Corporation). The thermal decomposition temperature refers to a temperature at which the measurement material is heated from room temperature at a constant temperature increase rate (10 ℃/min) in thermogravimetric analysis (TGA) in an atmospheric environment and is reduced by 5 mass% with respect to the mass of the measurement material before heating.

Next, the glass transition temperature of the measurement material was measured using a differential scanning calorimeter DSC (apparatus name: DSC-60a Plus, Shimadzu Corporation), and a closed pan at a temperature rise rate of 5 ℃/min in the range of 25 ℃ to (thermal decomposition temperature-5 ℃). As the glass transition temperature of the capsule wall of the microcapsule, the value at the time of temperature rise at week 2 was used.

The particle diameter of the microcapsule is not particularly limited, but is preferably 1 to 80 μm, more preferably 5 to 70 μm, and still more preferably 10 to 50 μm in terms of the volume-based median particle diameter (D50).

The volume-based median particle diameter of the microcapsules can be controlled by adjusting the production conditions of the microcapsules.

The volume-based median particle diameter of the microcapsules means a diameter at which the total volume of the particles on the major diameter side and the major diameter side becomes equal when the total volume of the microcapsules is divided into 2 by using a particle diameter at which the volume integration becomes 50% as a threshold value. That is, the median diameter corresponds to so-called D50.

The surface of the 1 st layer of the 1 st sheet having the 1 st layer containing microcapsules was photographed at 1000 times by an optical microscope, and all the sizes of the microcapsules in the range of 500 μm × 500 μm were measured to calculate values.

The number average wall thickness of the capsule wall of the microcapsule is not particularly limited, but is preferably 0.01 to 2 μm, more preferably 0.05 to 1 μm.

The thickness of the microcapsule is the thickness (μm) of the capsule wall of the capsule particles forming the microcapsule, and the number average thickness is an average value of the thicknesses (μm) of the capsule walls of 20 microcapsules obtained by Scanning Electron Microscope (SEM). More specifically, a cross-sectional slice of the 1 st sheet having the 1 st layer containing microcapsules was prepared, the cross-section was observed at 15000 times by SEM, and arbitrary 20 microcapsules having a particle diameter in the range of (the value of the median particle diameter on the volume basis of the microcapsules) × 0.9 to (the value of the median particle diameter on the volume basis of the microcapsules) × 1.1 were selected, and then the cross-section of each of the selected microcapsules was observed to determine the thickness of the capsule wall and calculate the average value.

The ratio (δ/Dm) of the number average wall thickness δ of the microcapsule to the volume-based median particle diameter (Dm) of the microcapsule is not particularly limited, and is usually 0.005 or more. Among them, from the viewpoint of enabling measurement of the pressure distribution in a high-temperature environment to be performed more favorably, the relationship satisfying the formula (1) is preferable.

Formula (1) delta/Dm > 0.010

That is, the ratio (δ/Dm) is preferably greater than 0.010. The ratio (δ/Dm) is preferably 0.015 or more. The upper limit is not particularly limited, but is preferably 0.050 or less.

When the microcapsule satisfies the relationship of the above formula (1), the balance between the size of the capsule and the thickness of the capsule wall is good, and there is less concern about leakage of the encapsulated material of the microcapsule in a high-temperature environment.

The color former is contained in the microcapsule.

The color former is a compound that develops color from a colorless state by contacting with a color developer described later. The color former is preferably an electron-donating color precursor (a precursor of a color-forming color). That is, the color former is preferably an electron-donating leuco dye.

As the color former, a color former known for use in pressure-sensitive copying paper or thermal recording paper can be used. Examples of the color former include triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalolide compounds, azaindolylphthalolide compounds, leucoaurothiamine compounds, rhodamine lactam compounds, triphenylmethane compounds, diphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds.

As to the details of the above-mentioned compounds, reference can be made to the description of Japanese patent application laid-open No. 5-257272.

The color former may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The molecular weight of the color former is not particularly limited, but is at most 300 or more. Among these, from the viewpoint of enabling measurement of the pressure distribution in the high-temperature environment to be performed more favorably, 420 or more is preferable, and 550 or more is more preferable. The upper limit is not particularly limited, but is preferably 1000 or less.

The molar absorption coefficient of a dye (dye corresponding to color development) (hereinafter, also simply referred to as "specific dye") obtained by bringing a color former into contact with a color developer described later is not particularly limited, and is preferably 10000mol^-1·cm^-1L or more, more preferably 15000mol^-1·cm^-1L or more, more preferably 25000mol^-1·cm^-1L or more. The upper limit of the molar absorptivity (. epsilon.) is not particularly limited, but it is usually 50000mol^-1·cm^-1L or less.

Preferred examples of the color former include 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide (. epsilon. ═ 61000), 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-n-octyl-2-methylindol-3-yl) phthalide (. epsilon. ═ 40000), 3- [2, 2-bis (1-ethyl-2-methylindol-3-yl) vinyl ] -3- (4-diethylaminophenyl) -phthalide (. epsilon. times.40000), 9- [ ethyl (3-methylbutyl) amino ] spiro [ 12H-benzo [ a ] xanthene-12, 1 ' (3 ' H) isobenzofuran ] -3 ' -one (epsilon. 34000), 2-anilino-6-dibutylamino-3-methylfluoran (epsilon. 22000), 6-diethylamino-3-methyl-2- (2, 6-dimethylanilino) -fluoran (epsilon. 19000), 2- (2-chloroanilino) -6-dibutylaminofluoran (epsilon. 21000), 3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (epsilon. 16000) and 2-anilino-6-diethylamino-3-methylfluoran (epsilon. 16000), 3 ', 6 ' -bis (diethylamino) -2- (4-nitrophenyl) spiro [ isoindole-1 ], 9 '-xanthene ] -3-one, 6' - (diethylamino) -1 ', 3' -dimethylfluorane, 3-bis (2-methyl-1-octyl-3-indolyl) phthalide, and the like.

In addition, the above ∈ represents a molar absorption coefficient after color development of each compound.

The molar absorption coefficient (. epsilon.) can be calculated from the absorbance when the specific dye is dissolved in a 95 mass% acetic acid aqueous solution. Specifically, when the length of the measurement cell is Acm, the concentration of the specific dye is Bmol/L, and the absorbance is C in a 95 mass% acetic acid aqueous solution of the specific dye whose concentration is adjusted so that the absorbance becomes 1.0 or less, the calculation can be performed by the following equation.

Molar absorptivity (epsilon) ═ C/(A × B)

[ other ingredients ]

The microcapsules may contain other components than the above-described color former.

For example, the microcapsule is preferably a solvent contained therein.

The solvent is not particularly limited, and examples thereof include aromatic hydrocarbons such as alkyl naphthalene compounds such as diisopropylnaphthalene, diarylalkane compounds such as 1-phenyl-1-ditolylethane, alkyl biphenyl compounds such as isopropylbiphenyl, triarylmethane compounds, alkylbenzene compounds, benzylnaphthalene compounds, diarylalkylene compounds, and arylindene alkane compounds; and high boiling point fractions of natural oils and vegetable oils such as dibutyl phthalate and isoparaffin, natural animals and vegetable oils such as soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, coconut oil, castor oil and fish oil, and natural oils such as mineral oil.

The solvent may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

When the solvent is contained in the microcapsule, the mass ratio of the solvent to the color former (mass of solvent/mass of color former) is preferably in the range of 98/2 to 30/70, more preferably in the range of 97/3 to 40/60, from the viewpoint of color formation.

The microcapsules may contain 1 or more additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, paraffin, and an odor inhibitor, as necessary, in addition to the above components.

[ Process for producing microcapsules ]

The method for producing the microcapsule containing a color former is not particularly limited, and examples thereof include known methods such as an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, and a coacervation method. Among them, the interfacial polymerization method is preferable.

The interfacial polymerization method is preferably an interfacial polymerization method including a step of preparing an emulsion by dispersing an oil phase containing a color former and a capsule wall material (for example, a raw material containing at least 1 selected from the group consisting of polyisocyanate, polyol and polyamine) in an aqueous phase containing an emulsifier (emulsification step) and a step of forming a microcapsule containing a color former by polymerizing a capsule wall material at the interface between the oil phase and the aqueous phase (encapsulation step) in the case of producing polyamine in a reaction system by reacting polyisocyanate and water.

The mass ratio of the total amount of the polyol and the polyamine to the amount of the polyisocyanate in the raw material (total amount of the polyol and the polyamine/amount of the polyisocyanate) is not particularly limited, but is preferably 0.1/99.9 to 30/70, and more preferably 1/99 to 25/75.

As described above, the polyisocyanate may be used together with the polyisocyanate a and the polyisocyanate B. In the case of using both, the preferable range of the mixing ratio of both is as described above.

The type of the emulsifier used in the emulsification step is not particularly limited, and examples thereof include a dispersant and a surfactant.

Examples of the dispersant include polyvinyl alcohol.

Layer 1 contains the microcapsules described above.

The content of the microcapsules in the 1 st layer is not particularly limited, but is preferably 50 to 90% by mass, more preferably 55 to 85% by mass, and still more preferably 55 to 80% by mass, based on the total mass of the 1 st layer, from the viewpoint of enabling the pressure distribution measurement in a high-temperature environment to be performed more favorably.

The content of the color former in the 1 st layer is not particularly limited, but is preferably 0.1 to 10g/m from the viewpoint of better measurement of the pressure distribution in a high-temperature environment²More preferably 0.1 to 4g/m²。

Layer 1 may contain other ingredients in addition to the microcapsules described above.

Examples of the other components include a polymer binder, an inorganic filler (e.g., colloidal silica), a fluorescent whitening agent, a defoaming agent, a penetrant, an ultraviolet absorber, a surfactant, and a preservative.

Examples of the polymer binder include synthetic polymers and natural polymers such as styrene-butadiene copolymers, polyvinyl acetate, polyacrylates, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymers, starch, casein, gum arabic, gelatin, carboxymethyl cellulose or salts thereof, methyl cellulose, polyolefins, and modified acrylate copolymers. The viscosity of the composition for forming the layer 1 can also be adjusted by adding a polymer binder. The polymer binder may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The content of the polymer binder is not particularly limited, but is preferably 0 to 50% by mass based on the total mass of the layer 1 from the viewpoint of further improving the effect of the present invention. From the viewpoint of being suitable for a low pressure region of 20MPa or less, it is preferably 0.1 to 20% by mass, and more preferably 0.2 to 10% by mass.

Examples of the surfactant include anionic surfactants, nonionic surfactants, and cationic surfactants, but anionic surfactants or nonionic surfactants are preferable from the viewpoint of maintaining the dispersibility of the microcapsules.

The surfactant may be a fluorine-based surfactant, a silicone-based surfactant, a hydrocarbon-based surfactant, or the like, but a hydrocarbon-based surfactant is preferable from the viewpoint of maintaining coatability and dispersibility of the microcapsule.

The content of the surfactant is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of the layer 1, from the viewpoint of further improving the effect of the present invention.

Preferably, after the 1 st sheet and the 2 nd sheet are laminated and the heating pressure is measured, the inorganic filler is introduced so as to easily peel them. In view of easy peeling of the 1 st and 2 nd sheets, silica particles and alumina particles are preferable as the inorganic filler. The median particle diameter of the inorganic filler is preferably 0.001 to 1 μm, more preferably 0.005 to 0.1. mu.m, and still more preferably 0.005 to 0.05. mu.m. The content of the inorganic filler is preferably 1 to 50 mass%, preferably 3 to 30 mass%, and more preferably 5 to 20 mass% with respect to the total mass of the layer 1.

The thickness of the 1 st layer is not particularly limited, but is preferably 0.01 to 5 μm, and preferably 0.02 to 3 μm, from the viewpoint of being suitable for a low pressure region of 20MPa or less. The thickness of the 1 st layer is the thickness excluding microcapsules exposed from the surface of the layer when the diameter of the microcapsules is larger than the thickness of the layer. When the thickness of the 1 st layer is within the above range, aggregation of the microcapsules can be suppressed and the capsules can be broken at a desired pressure when the 1 st layer-forming composition containing the microcapsules is applied and then dried. From the viewpoint of being suitable for a low pressure region of 20MPa or less, the thickness of the 1 st layer is preferably 50% or less, and preferably 25% or less, with respect to the median particle diameter of the microcapsule. The thinner the layer 1 is, the more easily the layer breaks, the smaller the microcapsule thickness, and therefore can be adjusted according to the measured pressure band.

And, the mass per unit area (g/m) of the 1 st layer²) Is not particularly limited, but is preferably 0.5 to 20g/m²。

[ method for Forming layer 1]

The method for forming the layer 1 is not particularly limited, and known methods can be used.

For example, a method in which the composition for forming the layer 1 containing microcapsules is applied to the layer 1 support and, if necessary, dried may be mentioned.

The composition for forming the layer 1 preferably contains at least microcapsules and a solvent. In addition, the microcapsule dispersion obtained by the interfacial polymerization method described above may also be used as the composition for forming the 1 st layer.

The composition for forming the layer 1 may contain other components that may be contained in the layer 1.

The method for coating the composition for forming layer 1 is not particularly limited, and examples of a coater used for coating include an air knife coater, a bar coater, a curtain coater, a gravure coater, a squeeze coater, a die coater, a slide bead coater, and a blade coater.

After the 1 st layer forming composition is applied to the 1 st support, the coating film may be dried as necessary. The drying treatment may be a heating treatment.

(other Components)

The 1 st sheet may have other members than the 1 st support and the 1 st layer described above.

For example, the 1 st sheet may have an adhesive layer between the 1 st support and the 1 st layer for improving adhesion therebetween.

From the viewpoint of adhesion, the adhesive layer preferably contains a resin. The resin may be a layer containing a resin formed of a urethane polymer or a blocked isocyanate, for example. Further, a layer containing gelatin, styrene/butadiene rubber, cellulose analog, polystyrene may be used.

From the viewpoint of heat resistance, the adhesive layer preferably contains a polymer having an aromatic group. From the viewpoint of heat resistance, the polymer is preferably a non-radical polymer, and examples thereof include polyester, polyurethane, polyamide, phenol resin, urea resin, and the like, and more preferably aromatic polyester and aromatic polyurethane.

The content of the polymer having an aromatic group is preferably 30% by mass or more, and more preferably 50% by mass or more, relative to the total mass of the adhesive layer. The upper limit is not particularly limited, but is, for example, 100 mass%.

The thickness of the adhesive layer is not particularly limited, but is preferably 0.005 to 2 μm, and more preferably 0.01 to 1 μm.

< 2 nd sheet >)

The 2 nd sheet 22 shown in fig. 1 has a 2 nd support 18 and a 2 nd layer 20 containing a color developer disposed on the 2 nd support 18.

When the 2 nd sheet 22 is heated at 220 ℃ for 10 minutes, the shrinkage ratio S1 in the longitudinal direction of the 2 nd sheet 22 and the shrinkage ratio S2 in the width direction orthogonal to the longitudinal direction of the 2 nd sheet 22 are both-0.5 to 2.0%.

The preferable ranges of the absolute values of the differences between the shrinkage rates S1, S2, S1 and S2 in the 2 nd sheet 22 are the same as the absolute values of the differences between the shrinkage rates S1, S2, S1 and S2 in the 1 st sheet 16, respectively.

The shrinkage rate S1 and the shrinkage rate S2 of the 2 nd sheet 22 were measured in the same manner as the shrinkage rate S1 and the shrinkage rate S2 of the 1 st sheet 16, except that the 2 nd sheet 22 was used in place of the 1 st sheet 16.

The definitions of the longitudinal direction and the width direction of the 2 nd sheet 22 are the same as those of the 1 st sheet 16 except that the 1 st sheet 16 is replaced with the 2 nd sheet 22.

The 2 nd sheet 22 may be a single sheet (single note) or a long sheet.

Hereinafter, each member will be described in detail.

(No. 2 support)

The 2 nd support is a member for supporting the 2 nd layer.

The mode of the 2 nd support body is the same as that of the 1 st support body described above, and therefore, the description thereof is omitted.

(layer 2)

The 2 nd layer is a layer containing a developer.

The developer is a compound which does not have a color-developing function by itself but has a property of developing a color of a color-developing agent by contacting the color-developing agent. The developer is preferably an electron-accepting compound.

Examples of the color developer include inorganic compounds and organic compounds.

Examples of the inorganic compound include clay materials such as acid clay, activated clay, attapulgite, zeolite, bentonite, and kaolin. In the case where the inorganic compound is introduced into the 2 nd layer, it is preferable to use a dispersant for dispersing the inorganic compound together. The dispersant is appropriately selected according to the surface properties of the inorganic compound, but for example, anionic hexametaphosphoric acid or a salt thereof is used for the acid-treated activated clay.

Examples of the organic compound include metal salts of aromatic carboxylic acids, metal salts of phenol-formaldehyde resins and carboxylated terpene-phenol resins.

As the metal salt of the aromatic carboxylic acid, 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-cyclohexylsalicylic acid, 3, 5-bis (. alpha.,. alpha. -dimethylbenzyl) salicylic acid, 3-methyl-5- (. alpha. -methylbenzyl) salicylic acid, 3- (. alpha.,. alpha. -dimethylbenzyl) -5-methylsalicylic acid, 3- (. alpha.,. alpha. -dimethylbenzyl) -6-methylsalicylic acid, and, 3- (. alpha. -methylbenzyl) -5- (. alpha.,. alpha. -dimethylbenzyl) salicylic acid, 3- (. alpha.,. alpha. -dimethylbenzyl) -6-ethylsalicylic acid, 3-phenyl-5- (. alpha.,. alpha. -dimethylbenzyl) salicylic acid, carboxyl-modified terpene-phenol resin, salicylic acid resin which is a reaction product of 3, 5-bis (. alpha. -methylbenzyl) salicylic acid and benzyl chloride, and the like, zinc salt, nickel salt, aluminum salt, calcium salt, and the like.

Among these, the developer is preferably a clay substance, a metal salt of an aromatic carboxylic acid or a metal salt of a carboxylated terpene-phenol resin, more preferably a clay substance or a metal salt of an aromatic carboxylic acid, still more preferably a clay substance, and particularly preferably an acid clay, an activated clay or kaolin.

In particular, when a clay substance is used as the color developer, the clay substance is hardly discolored during pressure measurement in a high-temperature environment, and therefore the display quality of the pressure distribution in the pressure measurement sheet set is excellent.

The content of the color-developing agent in the 2 nd layer is not particularly limited, but is preferably 20 to 95% by mass, more preferably 30 to 90% by mass, based on the total mass of the 2 nd layer, from the viewpoint of enabling measurement of the pressure distribution in a high-temperature environment to be performed more favorably.

The content of the color-developing agent in the 2 nd layer is not particularly limited, but is preferably 0.1 to 30g/m². When the color developing agent is an inorganic compound, the content of the color developing agent is preferably 3 to 20g/m²More preferably 5 to 15g/m². When the developer is an organic compound, the content of the developer is preferably 0.1 to 5g/m²More preferably 0.2 to 3g/m²。

The 2 nd layer may contain other components than the above-described developer.

Examples of the other components include a polymer binder, a pigment, a fluorescent whitening agent, an antifoaming agent, a penetrant, an ultraviolet absorber, a surfactant, and a preservative.

Examples of the polymer binder include synthetic polymers or natural polymers such as styrene-butadiene copolymer, polyvinyl acetate, polyacrylate, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymer, starch, casein, gum arabic, gelatin, carboxymethyl cellulose, polyolefin, modified acrylate copolymer, and methyl cellulose. The polymer binder may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The content of the polymer binder is not particularly limited, but is preferably 0.1 to 80% by mass, more preferably 1 to 50% by mass, based on the total mass of the 2 nd layer, from the viewpoint of further improving the effect of the present invention.

Examples of the pigment include ground calcium carbonate, light calcium carbonate, talc, and titanium dioxide.

Examples of the surfactant include the same surfactants as those contained in the above-mentioned layer 1, and preferred embodiments are also the same.

The thickness of the 2 nd layer is not particularly limited, but is preferably 1 to 50 μm, and more preferably 2 to 30 μm, from the viewpoint of enabling the pressure distribution measurement in a high-temperature environment to be performed more favorably.

And, the mass per unit area (g/m) of the 2 nd layer²) Is not particularly limited, but is preferably 0.5 to 20g/m²。

[ method for Forming layer 2]

The method for forming the 2 nd layer is not particularly limited, and a known method can be used.

For example, a method may be mentioned in which the layer-forming composition for layer 2 containing a color-developer is applied to the support for layer 2 and, if necessary, dried.

The composition for forming the 2 nd layer may be a dispersion liquid in which a developer is dispersed in water or the like. When the color developer is an inorganic compound, a dispersion liquid in which the color developer is dispersed can be prepared by mechanically dispersing the inorganic compound in water. When the developer is an organic compound, the developer can be prepared by mechanically dispersing the organic compound in water or dissolving the organic compound in an organic solvent.

The composition for forming the layer 2 may contain other components that may be contained in the layer 2.

The method of applying the composition for forming the 2 nd layer is not particularly limited, and a method using a coater used for applying the composition for forming the 1 st layer is exemplified.

After the composition for forming the layer 2 is applied to the support 2, the coating film may be dried as necessary. The drying treatment may be a heating treatment.

In addition, although the method of forming the 2 nd layer on the 2 nd support has been described above, the method is not limited to the above-described method, and for example, the 2 nd layer may be formed on the dummy support and then the dummy support may be peeled off, and the 2 nd sheet composed of the 2 nd layer may be formed.

The dummy support is not particularly limited as long as it is a releasable support.

(other Components)

The 2 nd sheet may have other members than the 2 nd support and the 2 nd layer described above.

For example, the 2 nd sheet may have an adhesive layer between the 2 nd support and the 2 nd layer for improving adhesion therebetween.

Examples of the adhesive layer include those having the adhesive layer of the above-mentioned 1 st sheet.

< 2 nd embodiment >

Fig. 2 is a sectional view of an embodiment of a pressure-measuring sheet.

The pressure-measuring sheet 30 includes a support 32, a 2 nd layer 20 containing a developer, and a 1 st layer 14 containing predetermined microcapsules 13 in this order. That is, the support 32 is disposed on the side of the 2 nd layer 20 opposite to the 1 st layer 14.

When the pressure-measuring sheet 30 is used, the microcapsules 13 are ruptured in the pressurized regions by applying pressure from at least one of the support 32 side and the 1 st layer 14 side, the color former contained in the microcapsules 13 comes out of the microcapsules 13, and a color developing reaction is performed between the color developers in the 2 nd layer 20. As a result, color development proceeds in the pressurized region.

In fig. 3, the support 32 and the 2 nd layer 20 are directly laminated, but the present invention is not limited to this embodiment, and another layer (for example, an adhesive layer) may be disposed between the support 32 and the 2 nd layer 20 as described later.

Further, although the pressure-measuring sheet 30 having the support 32, the 2 nd layer 20, and the 1 st layer 14 in this order is disclosed in fig. 3, the present invention is not limited to this embodiment, and a pressure-measuring sheet having the support 32, the 1 st layer 14, and the 2 nd layer 20 in this order may be used. That is, the support 32 may be disposed on the side of the 1 st layer 14 opposite to the 2 nd layer 20. When the support 32 is disposed on the side of the 1 st layer 14 opposite to the 2 nd layer 20, another layer (for example, an adhesive layer) may be disposed between the support 32 and the 1 st layer 14.

The 1 st layer 14 and the 2 nd layer 20 in the pressure-measuring sheet 30 are the same members as the 1 st layer 14 and the 2 nd layer 20 described in the above-described embodiment 1, and therefore, description thereof is omitted.

When the pressure-measuring sheet 30 is heated at 220 ℃ for 10 minutes, the shrinkage rate S1 in the longitudinal direction of the pressure-measuring sheet 30 and the shrinkage rate S2 in the width direction of the pressure-measuring sheet 30, which is orthogonal to the longitudinal direction, are both-0.5 to 2.0%.

The shrinkage S1 in the pressure-measuring sheet 30 is-0.5 to 2.0%, preferably-0.4 to 1.5%, more preferably-0.3 to 1.2%, and still more preferably-0.2 to 0.8%, from the viewpoint of enabling a more precise pressure distribution to be measured.

The shrinkage S2 in the pressure-measuring sheet 30 is-0.5 to 2.0%, preferably-0.4 to 1.5%, more preferably-0.3 to 1.2%, and still more preferably-0.2 to 0.8%, from the viewpoint of enabling a more precise pressure distribution to be measured.

The measurement methods of the shrinkage rate S1 and the shrinkage rate S2 of the pressure-measuring sheet 30 are the same as those of the shrinkage rate S1 and the shrinkage rate S2 of the 1 st sheet 16, except that the pressure-measuring sheet 30 is used instead of the 1 st sheet 16.

The definitions of the longitudinal direction and the width direction of the pressure measurement sheet 30 are the same as those of the 1 st sheet 16 except that the 1 st sheet 16 is replaced with the pressure measurement sheet 30.

In the pressure-measuring sheet 30, the absolute value (| S1-S2|) of the difference between the shrinkage ratio S1 and the shrinkage ratio S2 is preferably 0 to 0.8%, more preferably 0 to 0.6%, and further preferably 0 to 0.4%, from the viewpoint of enabling more precise pressure distribution to be measured.

The pressure-measuring sheet 30 may be a single sheet (single sheet) or a long sheet.

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

(support body)

The support is a member for supporting the 1 st and 2 nd layers.

A preferred embodiment of the support is the same as that of the above-described 1 st support, and therefore, description thereof is omitted.

(method of producing sheet for pressure measurement)

The method for producing the pressure-measuring sheet is not particularly limited, and known methods can be used.

For example, the following methods may be mentioned: after the layer 2 is formed on the support by applying the layer 2 forming composition containing the developer to the support and performing a drying treatment as necessary, the layer 1 is formed by further applying the layer 1 forming composition containing the microcapsules to the layer 2 and performing a drying treatment as necessary.

The method for forming the 1 st layer using the 1 st layer forming composition is as described in embodiment 1. The method for forming the 2 nd layer using the composition for forming the 2 nd layer is also as described in embodiment 1.

(other Components)

The pressure-measuring sheet may include other members besides the support, the 2 nd layer, and the 1 st layer.

For example, in the case where the support is provided on the side of the 2 nd layer opposite to the 1 st layer, the pressure-measuring sheet may have an adhesive layer between the support and the 2 nd layer for improving adhesion therebetween.

In the case where the first layer 1 has a support on the side opposite to the second layer 2, the pressure-measuring sheet may have an adhesive layer between the support and the first layer 1 for improving adhesion therebetween.

Examples of the adhesive layer include those having the adhesive layer of the above-mentioned 1 st sheet.

Examples

The present invention will be further described with reference to the following examples. The present invention is not limited to the following examples as long as the gist thereof is not deviated.

< example 1 >

(preparation of microcapsules)

The following compound (A) (molecular weight: 623) (7.4 parts by mass) as a color former was dissolved in linear alkylbenzene (ENEOS Corporation, grade olefin L) (56 parts by mass) to obtain a solution A. Next, synthetic isoparaffin (Idemitsu Kosan co., ltd., IP solvent 1620) (15 parts by mass) was added to the stirred solution a to obtain a solution B. Further, trimethylolpropane adduct (DIC CORPORATION, BURNOCKD-750) (7.5 parts by mass) dissolved in toluene diisocyanate of 2-butanone (5.4 parts by mass) and polymethylene polyphenyl polyisocyanate (TOSOH CORPORATION, MILLIONATEMR-200) (1.9 parts by mass) dissolved in 2-butanone (2.4 parts by mass) were added to the stirred solution B to obtain a solution C.

Then, the solution C was added to a solution in which polyvinyl alcohol (PVA-217E, Kuraray co., Ltd.) (8.5 parts by mass) was dissolved in water (140 parts by mass), and emulsified and dispersed. Water (230 parts by mass) was added to the emulsified liquid after emulsification and dispersion, and the mixture was heated to 70 ℃ with stirring and then cooled with stirring for 1 hour. In addition, water was added to adjust the concentration, and a microcapsule liquid containing a color former and having a solid content of 19.6 mass% was obtained.

[ chemical formula 2]

Also, as shown in the following structural formula, the BURNOCKD-750 corresponds to a 3-functional polyisocyanate which is an adduct of an aromatic diisocyanate and trimethylolpropane.

[ chemical formula 3]

The volume-based median particle diameter of the microcapsules containing the color former was 14 μm. The number average wall thickness was 0.20. mu.m. Further, δ/Dm was 0.014. Further, the capsule wall of the microcapsule does not exhibit a glass transition temperature in the range of "25 ℃ to" (thermal decomposition temperature (. degree. C.) -5 ℃).

The median particle diameter (Dm) was calculated by preparing a 1 st sheet having a 1 st layer containing microcapsules as described later, imaging the surface of the 1 st layer at 150 × magnification by an optical microscope, and measuring the sizes of all microcapsules in the range of 500 μm × 500 μm.

As for the number average wall thickness, as will be described later, after the 1 st sheet having the 1 st layer containing microcapsules is produced, a cross-sectional slice of the 1 st sheet having the 1 st layer containing microcapsules is produced, the cross-section thereof is observed by SEM, arbitrary 20 microcapsules having a particle diameter in the range of (the value of the volume-based median particle diameter of the microcapsules) × 0.9 to (the value of the volume-based median particle diameter of the microcapsules) × 1.1 are selected, the cross-section of each of the selected microcapsules is observed, the thickness of the capsule wall is obtained, and the average value is calculated.

Also, the glass transition temperature was measured by the following method.

First, as described later, a 1 st sheet having a 1 st layer containing microcapsules was prepared, cut into 50 pieces of 1cm in the longitudinal direction × 1cm in the transverse direction, and the whole was immersed in 10ml of water and left to stand for 24 hours. The obtained aqueous dispersion of microcapsules was centrifuged at 15000rpm for 30 minutes to collect the microcapsules. Ethyl acetate was added to the separated microcapsules and further stirred at 25 ℃ for 24 hours. Thereafter, the obtained solution was filtered, and the obtained residue was vacuum-dried at 60 ℃ for 48 hours, whereby microcapsules (hereinafter, also simply referred to as "measurement material") not containing any inside were obtained. Next, the thermal decomposition temperature of the obtained measurement material was measured using a thermogravimetric differential thermal analysis apparatus TG-DTA (apparatus name: DTG-60, Shimadzu Corporation). In addition, as the thermal decomposition temperature, a temperature at which the measurement material was heated from room temperature at a constant temperature increase rate (10 ℃/min) and reduced by 5 mass% with respect to the mass of the measurement material before heating was taken as the thermal decomposition temperature (. degree. C.) in thermogravimetric analysis (TGA) of an atmospheric environment. Next, the glass transition temperature of the measurement material was measured using a differential scanning calorimeter DSC (apparatus name: DSC-60a Plus, Shimadzu Corporation), and a closed pot at a temperature rise rate of 5 ℃/min in the range of 25 ℃ to (thermal decomposition temperature-5 ℃). The glass transition temperature of the capsule wall of the microcapsule was measured at the time of temperature rise at week 2.

(preparation of the 1 st sheet)

A microcapsule liquid (43 parts by mass) containing a coloring agent, water (15 parts by mass), colloidal silica (Nissan Chemical Industries, ltd., SNOWTEX (registered trademark) 30) (4.3 parts by mass), a 10 mass% aqueous solution (4.3 parts by mass) of carboxymethyl cellulose Na (DKS co.ltd., SEROGEN 5A), a 1 mass% aqueous solution (10 parts by mass) of carboxymethyl cellulose Na (DKS co.ltd., SEROGEN EP), a 15 mass% aqueous solution (0.3 part by mass) of sodium alkylbenzenesulfonate (DKS co.ltd., NEOGEN T) and a 1 mass% aqueous solution (1.0 part by mass) of NOIGEN LP70(DKS co.ltd.), were mixed and stirred for 2 hours, thereby obtaining a composition for forming the layer 1 st.

The obtained composition for forming the layer 1 was applied to a polyethylene naphthalate sheet (Teijin Film Solutions Limited, TEONEX (registered trademark), Q83) having a thickness of 50 μm as a first support by a bar coater so that the mass after drying became 4.5g/m²Then, the resultant was dried to form a 1 st layer, thereby producing a 1 st sheet.

(preparation of No. 2 sheet)

A dispersion was prepared by dispersing sulfuric acid-treated activated clay (200 parts by mass), sodium hexametaphosphate (1 part by mass), a 10 mass% aqueous solution of sodium hydroxide (30 parts by mass), and water (290 parts by mass) as a color developer using kneaded sand so that the average particle diameter of the total particles became 2 μm.

Next, to the prepared dispersion, a 19 mass% aqueous dispersion (180 parts by mass) of NIPOL LX-814(Zeon Corporation), a 3.3 mass% aqueous solution (220 parts by mass) of POLYMARON 482(ARAKAWA CHEMICAL INDUSTRIES, LTD.), a 1 mass% aqueous solution (80 parts by mass) of carboxymethyl cellulose Na (DKS co.ltd., SEROGEN EP), a 15 mass% aqueous solution (4.7 parts by mass) of sodium alkylbenzenesulfonate (DKS co.ltd., NEOGEN T), and a 1 mass% aqueous solution (70 parts by mass) of NOIGEN LP70(DKS co.ltd.) were mixed to prepare a coating liquid containing a color developer.

A coating liquid containing a developer was applied to a 50 μm thick polyethylene naphthalate sheet (Teijin Film Solutions Limited, TEONEX (registered trademark), Q83) as a No. 2 support body in such an amount that the solid content was 12.0g/m²And allowed to dry to form layer 2, thereby obtaining sheet 2.

< example 2 >

(preparation of microcapsules)

The above compound (A) (molecular weight: 623) (6.8 parts by mass) as a color former was dissolved in linear alkylbenzene (ENEOS Corporation, grade olefin L) (52 parts by mass) to obtain a solution A. Next, synthetic isoparaffin (Idemitsu Kosan co., ltd., IP solvent 1620) (14 parts by mass) was added to the stirred solution a to obtain a solution B. Further, trimethylolpropane adduct (DIC CORPORATION, BURNOCKD-750) (10.8 parts by mass) dissolved in toluene diisocyanate of 2-butanone (7.8 parts by mass) and polymethylene polyphenyl polyisocyanate (TOSOH CORPORATION, MILLIONATEMR-200) (2.7 parts by mass) dissolved in 2-butanone (3.5 parts by mass) were added to the stirred solution B to obtain a solution C.

Then, the solution C was added to a solution in which polyvinyl alcohol (PVA-217E, Kuraray co., Ltd.) (7.8 parts by mass) was dissolved in water (130 parts by mass), and emulsified and dispersed. Water (230 parts by mass) was added to the emulsified liquid after emulsification and dispersion, and the mixture was heated to 70 ℃ with stirring and then cooled with stirring for 1 hour. In addition, water was added to adjust the concentration, and a microcapsule liquid containing a color former and having a solid content of 19.6 mass% was obtained.

The volume-based median particle diameter of the microcapsules containing the color former was 20 μm. The number average wall thickness was 0.44. mu.m. And δ/Dm is 0.022. Further, the capsule wall of the microcapsule does not exhibit a glass transition temperature in the range of "25 ℃ to" (thermal decomposition temperature (. degree. C.) -5 ℃).

Except for using the microcapsule liquid with a color former encapsulated therein obtained as described above, the 1 st sheet and the 2 nd sheet were produced in the same manner as in example 1.

< example 3 >

A dispersion was prepared by dispersing zinc 3, 5-di- α -methylbenzyl salicylate (10 parts by mass), calcium carbonate (100 parts by mass), sodium hexametaphosphate (1 part by mass), and water (200 parts by mass) as a color developer using kneaded sand so that the average particle diameter of the total particles became 2 μm.

Next, a 10% aqueous solution (100 parts by mass) of polyvinyl alcohol (PVA-203, Kuraray co., Ltd.), a styrene-butadiene latex (10 parts by mass as a solid content), and water (450 parts by mass) were added to the prepared dispersion to prepare a coating liquid containing a color developer.

A 1 st sheet and a 2 nd sheet were produced in the same manner as in example 2, except that the coating liquid containing the developer obtained as described above was used.

< examples 4 and 5 >

A first sheet and a second sheet were produced in the same manner as in example 2 except that a polyethylene naphthalate sheet having a thickness of 12 μm or a polyethylene naphthalate sheet having a thickness of 250 μm was used as the first support and the second support in place of the polyethylene naphthalate sheet having a thickness of 50 μm (Teijin Film Solutions Limited, TEONEX (registered trademark), Q83).

< comparative example 1 >

A 1 st sheet and a 2 nd sheet were produced in the same manner as in example 2 except that an adhesive layer-attached polyethylene terephthalate sheet (TOYOBO co., ltd., COSMOSHINE (registered trademark) a4300) having a thickness of 50 μm was used instead of the polyethylene naphthalate sheet (Teijin Film Solutions Limited, tenonex (registered trademark), Q83) having a thickness of 50 μm as the 1 st support and the 2 nd support.

< evaluation >

(measurement of shrinkage percentage)

3 samples were prepared in which the length of the 1 st sheet cut out from the 1 st sheets prepared in the examples and comparative examples in the longitudinal direction was 150mm and the length in the width direction was 20 mm.

The reticle is given to a position a which advances by about 25mm from the center point (starting point) of the short side of one of the samples toward the center point of the other short side and in the direction parallel to the long side, and a position B which advances by about 25mm from the center point (starting point) of the short side of the other of the samples toward the center point of the short side and in the direction parallel to the long side, respectively. At this time, the distance between the position A and the position B (the distance between the marked lines) was 100 mm. + -.2 mm.

This was used as a sample for measurement of the shrinkage rate S1 in the longitudinal direction of the 1 st sheet.

After the obtained measurement sample was heated at 220 ℃ for 10 minutes, the measurement sample was returned to room temperature (23 ℃), and the distance between the marked lines of the measurement sample was measured, and the shrinkage rate S1a was calculated according to the following formula.

Shrinkage rate S1a [% ] { (distance between the scale lines in the measurement sample before heating) - (distance between the scale lines in the measurement sample after heating) }/(distance between the scale lines in the measurement sample before heating)

The arithmetic average of the shrinkage rates S1a of the 3 measurement samples was obtained and used as the shrinkage rate S1. In addition, the distance between the reticles is measured to units of 0.1 mm.

Then, 3 samples were prepared in which the 1 st sheet prepared in each of examples and comparative examples was cut into a length of 150mm in the width direction and 20mm in the length direction of the 1 st sheet. A mark line was provided on the surface of each sample in the same manner as the sample for measurement of the shrinkage rate S1.

This was used as a sample for measurement of the shrinkage rate S2 in the width direction of the 1 st sheet.

After the obtained measurement sample was heated at 220 ℃ for 10 minutes, the measurement sample was returned to room temperature (23 ℃), and the distance between the marked lines of the measurement sample was measured, and the shrinkage rate S2a was calculated according to the following formula.

Shrinkage rate S2a [% ] { (distance between the scale lines in the measurement sample before heating) - (distance between the scale lines in the measurement sample after heating) }/(distance between the scale lines in the measurement sample before heating)

The arithmetic average of the shrinkage rates S2a of the 3 measurement samples was obtained and used as the shrinkage rate S2. In addition, the distance between the reticles is measured to units of 0.1 mm.

The shrinkage rate S1 and the shrinkage rate S2 in the 2 nd sheet were calculated in the same manner as the measurement method of the shrinkage rate S1 and the shrinkage rate S2 in the 1 st sheet, except that the 2 nd sheet prepared in each example and comparative example was used instead of the 1 st sheet prepared in each example and comparative example.

(measurement of pressure distribution)

The 1 st and 2 nd sheets prepared in each of examples and comparative examples were cut into pieces of 5cm × 5cm, and the 1 st and 2 nd sheets were stacked by contacting the 1 st layer surface of the 1 st sheet and the 2 nd layer surface of the 2 nd sheet, to obtain a laminate (sheet set).

Next, a hot press having 2 heating stages arranged above and below was prepared, the heating stages were separated from each other, an endless SUS (Steel Use Stainless) substrate having a width of 5mm was arranged on the lower stage, and a laminate was arranged so as to cover the SUS substrate. Thereafter, the SUS substrate and the laminate were sandwiched between 2 heating stages heated to 220 ℃, and the substrate and the laminate were pressed at 2.0Mpa for 10 minutes. After the pressing was completed, the shape of the color development region of the obtained laminate was observed and evaluated according to the following criteria.

"5": the color-developed region was not dense and dense, and the shape of the color-developed region was recognized as a ring shape similar to that of the SUS substrate.

"4": the color tone density was very small, but the color tone region was recognized to have a ring shape similar to that of the SUS substrate.

"3": although the color is dense, the shape of the color region can be sufficiently recognized as a ring shape.

"2": due to the density of the color, a part having a ring shape in which the color region cannot be recognized is locally present.

"1": the density of the color is very large, and the shape of the color region is hardly recognizable as a ring shape.

The evaluation results are shown in table 1. In table 1, PEN refers to polyethylene naphthalate, and PET refers to polyethylene terephthalate.

[ Table 1]

As shown in table 1, it was confirmed that, compared to the case of using the laminate of the pressure-measuring sheet set in which at least 1 of the shrinkage rates S1 and S2 of the 1 st sheet and the shrinkage rates S1 and S2 of the 2 nd sheet was outside the above range (comparative example 1), the laminate of the pressure-measuring sheet set in which the shrinkage rates S1 and S2 of the 1 st sheet and the shrinkage rates S1 and S2 of the 2 nd sheet were both in the range of-0.5 to 2.0% (examples 1 to 5), accurate pressure distribution could be measured.

Further, from the comparison between examples 2 and 4, it was confirmed that a more accurate pressure distribution could be measured when using the pressure-measuring sheet set (example 2) in which the difference between the absolute values of the shrinkage rates S1 and S2 of the 1 st sheet and the difference between the absolute values of the shrinkage rates S1 and S2 of the 2 nd sheet were both in the range of 0 to 0.8%.

The 2 nd sheet of examples 2 and 3 was heated at 220 ℃ for 10 minutes, and the hue of the 2 nd sheet was visually recognized, whereby the 2 nd sheet of example 2 was white, whereas the 2 nd sheet of example 3 was changed in color to a yellowish hue.

Further, the above-described pressure distribution measurement was performed using a laminate of the pressure-measuring sheet sets of examples 2 and 3 including the heated 2 nd sheet, and the colored region was visually recognized, and the colored region of example 3 exhibited a yellowish hue. As described above, it was confirmed that the pressure-measuring sheet set of example 2 was superior in display quality when exposed to high temperatures, compared to the pressure-measuring sheet set of example 3.

The pressure-measuring sheet sets of examples 1,2, and 4 were evaluated in the same procedure as in the above-described pressure distribution measurement except that the width of the endless SUS substrate was changed to 2 mm.

As a result, it was confirmed that, when the laminate of the pressure-measuring sheet set in which both the 1 st support and the 2 nd support have a thickness of 25 μm or more was used (examples 1 and 2), an unnatural increase in the color development density (that is, uniform color development without color unevenness) was suppressed at a position corresponding to the end of the SUS substrate, as compared with the case of using the laminate of the pressure-measuring sheet set in which both the 1 st support and the 2 nd support have a thickness of less than 25 μm (example 4).

The pressure-measuring sheet sets of examples 1,2, and 5 were evaluated in the same procedure as in the above-described pressure distribution measurement except that the width of the endless SUS substrate was changed to 10 mm.

As a result, it was confirmed that, when the laminate of the pressure-measuring sheet set in which both the 1 st support and the 2 nd support have a thickness of 200 μm or less was used (examples 1 and 2), an unnatural decrease in the color development density (that is, an unnatural color development at the end portion and an afterimage) was suppressed at a position corresponding to the end portion of the SUS substrate, as compared with the case of using the laminate of the pressure-measuring sheet set in which both the 1 st support and the 2 nd support have a thickness of more than 200 μm (example 5).

< example 6 >

The pressure-sensitive adhesive layer-forming composition A described later was applied to the surface of one of polyethylene naphthalate sheets (Teijin Film Solutions Limited, TEONEX (registered trademark), Q83) having a thickness of 50 μm by a bar coater, and dried to form a pressure-sensitive adhesive layer A having a thickness of 0.45 μm. A first sheet was produced in the same manner as in example 1, except that the first support 1 was changed to a polyethylene naphthalate sheet having an adhesive layer a formed thereon. In addition, the 1 st layer is formed on the surface of the adhesive layer. Using the 1 st sheet produced in example 6, the shrinkage rates were measured in the same manner as in example 1, and the shrinkage rates of the 1 st sheet produced in example 6 were 0.5% for S1 and 0.1% for S2.

Composition A for forming adhesive layer

25.9 parts by mass of a styrene/butadiene copolymer latex (styrene: butadiene 67:30, product name: LX-407C5, manufactured by Zeon Corporation, solid content 40 mass%) (styrene: butadiene copolymer latex)

0.3 part by mass of polystyrene particles (product name: UFN1008, manufactured by Zeon Corporation, average particle: 2 μm, solid content: 20% by mass)

1.0 part by mass of a copolymer (59/8/26/5/2% by mass, solid content 25% by mass) of methyl methacrylate/styrene/2-ethoxyhexyl acrylate/2-hydroxyethyl methacrylate/acrylic acid

152.5 parts by mass of an aromatic polyester (PLAS COAT Z-687 (manufactured by go CHEMICAL co., ltd.) and 25% by mass of a solid content)

203.2 parts by mass of carboxymethyl cellulose Na (DKS co.ltd., SEROGEN EP, 1 mass% aqueous solution)

3.8 parts by mass of sodium alkylbenzenesulfonate (DKS co.ltd. system, NEOGEN T, 15 mass% aqueous solution)

67.7 parts by mass of NOIGEN LP70 (1% by mass aqueous solution manufactured by DKS Co. Ltd.)

545.5 parts by mass of distilled water

As a result of performing the pressure distribution measurement in the same manner as in example 1 using the 1 st sheet of example 6 and the 2 nd sheet produced in example 1, it was confirmed very well that the color-developed region had a shape of a ring similar to that of the SUS substrate (that is, "5" as an evaluation criterion of the pressure distribution measurement) without the density of the color development.

< example 7 >

A 1 st sheet and a 2 nd sheet were produced in the same manner as in example 1, except that the 1 st support and the 2 nd support were changed to the polyethylene naphthalate sheet with the adhesive layer a formed, which was produced in example 6. The 1 st and 2 nd layers are formed on the surface of the adhesive layer.

Using the 1 st sheet produced in example 7, the shrinkage rates were measured in the same manner as in example 1, and the shrinkage rates of the 1 st sheet produced in example 7 were 0.5% for S1 and 0.1% for S2.

When the shrinkage percentage of the 2 nd sheet produced in example 7 was measured in the same manner as in example 1, S1% and S2 of the shrinkage percentage of the 2 nd sheet produced in example 7 were 0.5% and 0.1%, respectively.

Using the 1 st and 2 nd sheets in example 7, it was very well confirmed that the color-developed regions were not densely developed and had the same ring shape as the SUS substrate (i.e., "5" as the evaluation criterion of the pressure distribution measurement) as the result of the pressure distribution measurement in the same manner as in example 1.

Description of the symbols

10-set of sheets for pressure measurement, 12-support 1, 13-microcapsules, 14-layer 1, 16-sheet 1, 18-support 2, 20-layer 2, 22-sheet 2, 30-sheet for pressure measurement, 32-support.