Pressure measuring material and method for producing pressure measuring material

Abstract

A pressure measuring material and a method for producing the pressure measuring material. The pressure measuring material comprises a substrate and a pressure-sensitive layer, wherein the pressure-sensitive layer comprises: a polymer matrix containing a polymer compound with a molecular weight of 1000 or more; microcapsules containing an electron-donating dye precursor and a solvent; and an electron-accepting compound.

Description

[0001] This application is a divisional application of the applicant's previous application numbered 202080009382.8, entitled "Pressure Measuring Material and Method for Manufacturing Pressure Measuring Material." The parent application was filed on January 17, 2020, and has a priority date of January 17, 2019. Technical Field

[0002] The present invention relates to a pressure measuring material and a method for manufacturing the pressure measuring material. Background Art

[0003] Pressure measurement materials (i.e., materials used for pressure measurement) are used in applications such as the bonding process of liquid crystal glass, solder printing on printed circuit boards, and pressure adjustment between rollers. Examples of materials used for pressure measurement include pressure measurement films represented by PRESCALE (trade name; registered trademark) supplied by FUJIFILM Corporation.

[0004] Various studies have been conducted on pressure measurement materials for measuring minute pressures.

[0005] For example, Japanese Patent Application Laid-Open No. 2009-019949 proposes a pressure measurement material having a color density difference ΔD of 0.02 or more before and after pressurization at 0.05 MPa in order to obtain a density that can be visually recognized or read under a minute pressure. Summary of the Invention

[0006] Technical issues to be solved by the invention

[0007] As shown in the aforementioned Japanese Patent Application Publication No. 2009-019949, various studies have been conducted on pressure measuring materials for measuring minute pressures. Meanwhile, pressure measuring materials for measuring pressures in high-pressure regions (preferably in the range of 100 MPa to 10,000 MPa) are required for applications such as compression process management in various manufacturing processes.

[0008] However, the upper limit of the measurable pressure range that can be supported by commercially available pressure measurement membranes, that is, the upper limit of the pressure range in which color development is achieved by pressurization, is essentially around 300 MPa. Therefore, previous pressure measurement materials, especially those for pressures exceeding 300 MPa, are sometimes unable to fully support the measurement.

[0009] Thus, there is a demand for pressure measurement in the high-pressure region, and conventional pressure measurement materials have been able to cope with this to a certain extent, but further improvement is actually desired.

[0010] An object of one embodiment of the present invention is to provide a material for pressure measurement that can achieve color development with excellent gradation in a high-pressure region (preferably a region of 100 MPa to 10,000 MPa).

[0011] Means for solving technical problems

[0012] The present invention includes the following aspects.

[0013] <1> A pressure measuring material comprises a substrate and a pressure-sensitive layer, wherein the pressure-sensitive layer comprises: a polymer matrix containing a polymer compound having a molecular weight of 1000 or more; microcapsules containing an electron-donating dye precursor and a solvent; and an electron-accepting compound.

[0014] <2> according to <1> The pressure measuring material is in sheet form.

[0015] <3> according to <1> or <2> The pressure measuring material has an arithmetic mean roughness Ra of the outermost surface on the side opposite to the substrate of 10.0 μm or less.

[0016] <4> according to <1> to <3> The pressure measuring material according to any one of the preceding claims, wherein the microcapsules and the electron-accepting compound are contained in the polymer matrix.

[0017] <5> according to <4> The pressure measuring material has an arithmetic mean roughness Ra of less than 2.0 μm on the outermost surface opposite to the substrate.

[0018] <6> according to <4> or <5> In the pressure measuring material, the electron-accepting compound contains a metal salt of salicylic acid.

[0019] <7> according to <4> to <6> The pressure measuring material according to any one of the preceding claims has a void volume of 5 mL / m 2 the following.

[0020] <8> according to <4> to <7> The pressure measuring material according to any one of the preceding claims, wherein the content of the microcapsules is 10% to 80% by volume relative to the pressure-sensitive layer.

[0021] <9> according to <3> The pressure measuring material, wherein the pressure sensitive layer comprises: a color developing layer comprising the electron accepting compound and the polymer matrix; and a color developing layer comprising the microcapsules.

[0022] The pressure measuring material includes the substrate, the color development layer, and the color developing layer in this order, and the thickness of the color developing layer is less than or equal to half the thickness of the color development layer.

[0023] <10> according to <9> The pressure measuring material has an arithmetic mean roughness Ra of the outermost surface on the side opposite to the substrate of 2.0 μm to 10.0 μm.

[0024] <11> according to <9> or <10> In the pressure measuring material, the electron-accepting compound contains acidic clay or activated clay.

[0025] <12> according to <11> In the pressure measuring material, the pressure-sensitive layer contains inorganic particles other than the electron-accepting compound.

[0026] <13> according to <9> to <12> The pressure measuring material according to any one of the preceding claims has a void volume of 5 mL / m 2 ~~20mL / m 2 .

[0027] <14> according to <1> to <13> The pressure measuring material according to any one of the preceding claims, wherein a ratio T / p of a thickness T of a layer obtained by subtracting a thickness of the substrate from a thickness of the pressure measuring material to an inner diameter p of the microcapsule is 1.2 or greater.

[0028] <15> according to <14> The pressure measuring material has a ratio T / p of a thickness T of a layer obtained by subtracting a thickness of the substrate from a thickness of the pressure measuring material to an inner diameter p of the microcapsule of 1.2 to 5.0.

[0029] <16> according to <1> to <15> The pressure measuring material according to any one of the preceding claims, wherein the polymer compound having a molecular weight of 1000 or greater is contained in an amount of 10% by mass or more based on the total mass of the pressure-sensitive layer.

[0030] <17> according to <1> to <16> The pressure measuring material according to any one of the preceding claims, wherein the substrate is a polyethylene terephthalate substrate or a polyethylene naphthalate substrate.

[0031] <18> according to <1> to <17> The pressure measuring material according to any one of the preceding claims, further comprising an easily adhesive layer between the substrate and the pressure-sensitive layer.

[0032] <19> according to <1> to <18> The pressure measuring material according to any one of the preceding claims, wherein the wall material of the microcapsule contains at least one selected from polyurethane urea and polyurethane.

[0033] <20> A method for manufacturing a material for pressure measurement, comprising: <4> to <8> and <14> to <19> The method for producing a pressure measuring material according to any one of the preceding claims, comprising: placing a pressure-sensitive layer-forming composition on a substrate;

[0034] The pressure-sensitive layer forming composition comprises: a polymer matrix containing a polymer compound with a molecular weight of 1000 or more; microcapsules containing an electron-donating dye precursor and a solvent; and an electron-accepting compound.

[0035] <21> A method for manufacturing a material for pressure measurement, comprising: <9> to <19> The method for producing a pressure measuring material according to any one of the preceding claims, comprising:

[0036] A step of obtaining a color-forming layer composition, wherein the color-forming layer composition comprises microcapsules and a solvent, wherein the microcapsules contain an electron-donating dye precursor and the solvent;

[0037] a step of obtaining a color-development layer-forming composition comprising an electron-accepting compound and a polymer compound having a molecular weight of 1000 or more;

[0038] A step of disposing the color-developing layer-forming composition on a substrate to form a color-developing layer; and

[0039] a step of disposing the color-forming layer-forming composition on the color-developing layer to form a color-forming layer.

[0040] Effects of the Invention

[0041] According to one embodiment of the present invention, a material for pressure measurement that can achieve color development with excellent gradation in a high-pressure region (preferably a region of 100 MPa to 10,000 MPa) can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a graph showing the relationship between pressure and color development density in the evaluation of color development characteristics in Examples.

[0043] Figure 2 This is a schematic cross-sectional view showing an example of the pressure measuring material of the present invention.

[0044] Figure 3 This is a schematic cross-sectional view showing an example of the pressure measuring material of the present invention. DETAILED DESCRIPTION

[0045] The pressure measuring material of the present invention, including its production method, is described in detail below. The pressure measuring material of the present invention and its production method are not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

[0046] In the present invention, a numerical range expressed by “to” means a range including the numerical values ​​described before and after “to” as the lower limit and the upper limit.

[0047] In the numerical ranges described in stages throughout the present invention, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in the present invention, the upper limit or lower limit described in a certain numerical range may be replaced by the values ​​shown in the Examples.

[0048] In the present invention, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

[0049] In the present invention, a combination of two or more preferred aspects is a more preferred aspect.

[0050] In the present invention, the electron-donating dye precursor is also referred to as a "color-forming agent," and the electron-accepting compound that causes the electron-donating dye precursor to develop color is also referred to as a "color-developing agent."

[0051] <Pressure Measurement Material and Manufacturing Method>

[0052] The pressure measuring material of the present invention comprises a substrate and a pressure-sensitive layer. The pressure-sensitive layer comprises a polymer matrix (hereinafter referred to as the "polymer matrix") containing a polymer compound having a molecular weight of 1000 or greater; microcapsules containing an electron-donating dye precursor and a solvent; and an electron-accepting compound. In addition to the substrate and pressure-sensitive layer, the pressure measuring material of the present invention may further comprise other layers (e.g., a white layer, a protective layer, an adhesion-facilitating layer, etc.) as needed.

[0053] Pressure measuring materials have long been proposed and widely used. However, conventional pressure measuring materials have focused on achieving a concentration that can be visually recognized or read even when subjected to minute pressures. For example, the pressure measuring material described in Japanese Patent Application Laid-Open No. 2009-019949 targets measurements under minute pressures of less than 0.1 MPa.

[0054] However, in pressure measurement materials corresponding to measurements under very small pressures, even if there is a mechanism effective for obtaining a wide concentration level (for example, control of the particle size, wall thickness, constituent materials, etc. of the microcapsules), it is sometimes difficult to design such a mechanism alone to exhibit a wide concentration level when measuring pressure in a high-pressure region.

[0055] In view of the above circumstances, the pressure measuring material of the present invention comprises a substrate and a pressure-sensitive layer, wherein the pressure-sensitive layer is a layer containing a polymer matrix, microcapsules containing an electron-donating dye precursor and a solvent, and an electron-accepting compound.

[0056] Thus, the pressure measuring material of the present invention can achieve color development with excellent gradation in a high-pressure region (preferably in the region of 100 MPa to 10,000 MPa, more preferably in the region of 300 MPa to 3,000 MPa).

[0057] The reason why the pressure-measuring material of the present invention exhibits the above-mentioned effects is not yet certain, but the present inventors speculate that the pressure-sensitive layer comprises a polymer matrix, microcapsules containing an electron-donating dye precursor and a solvent, and an electron-accepting compound. This mitigates the pressure applied to the microcapsules even under high pressure, enabling pressure measurement with excellent color gradation. However, this speculation does not limit the effects of the pressure-measuring material of the present invention.

[0058] In the present invention, the "gradation of color development" refers to a property in which the density of color development increases as the pressure applied to the pressure measuring material increases.

[0059] The pressure-measuring material of the present invention develops color in the pressure-sensitive layer through contact between an electron-donating dye precursor contained in microcapsules and an electron-accepting compound serving as a color developer. This color development reflects the concentration corresponding to the intensity of the external force (externally applied pressure, hereinafter referred to) applied to the pressure-measuring material, i.e., the gradation of the color development. For example, when surface pressure is applied to the pressure-measuring material and the applied surface pressure is uneven across the entire surface, the color development will have a concentration corresponding to the pressure, resulting in an image with gradations in concentration.

[0060] The pressure measuring material of the present invention may also be capable of achieving color gradation in the range of 100 MPa to 10,000 MPa, and may be capable of achieving color gradation even when a pressure less than 100 MPa and / or a pressure exceeding 10,000 MPa is applied.

[0061] [Base material]

[0062] The pressure measuring material of the present invention has a base material.

[0063] The shape of the substrate may be any shape such as a sheet or plate. The shape of the substrate is preferably a sheet. That is, the pressure measuring material of the present invention is preferably a sheet-shaped pressure measuring material having a sheet-shaped substrate and a pressure-sensitive layer. In the present invention, "sheet-shaped" means having two main planes, a thickness of 1 mm or less (preferably 1 μm to 1 mm), and flexibility. In the present invention, sheet-shaped includes film-shaped, and the two are used as synonymous terms. "Plate-shaped" means having two main planes, a thickness of more than 1 mm (preferably more than 1 mm and less than 10 mm).

[0064] The substrate is not particularly limited, and specific examples include paper, synthetic paper, plastic substrates, metal substrates, and composite substrates thereof. From the viewpoint of ease of handling, the substrate is preferably a plastic substrate.

[0065] Specific examples of paper include high-quality paper, medium-quality paper, straw paper, neutral paper, acid paper, recycled paper, coated paper, machine-coated paper, art paper, cast-coated paper, micro-coated paper, and tracing paper.

[0066] Specific examples of the plastic forming the plastic substrate include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), cellulose derivatives such as cellulose triacetate, polyolefins such as polypropylene and polyethylene, and polystyrene.

[0067] Specific examples of synthetic paper include synthetic paper (YUPO, etc.) formed by biaxially stretching polypropylene or polyethylene terephthalate to form multiple micropores, synthetic paper made using synthetic fibers such as polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, and polyamide fibers, and laminates formed by laminating them on part of another synthetic paper, on one side or both sides, etc.

[0068] The substrate is preferably a substrate containing metal. Examples of the substrate in this embodiment include metal substrates and composite substrates of metal and plastic.

[0069] The metal is not particularly limited, but is preferably a metal such as stainless steel (SUS) from the viewpoint of being less likely to deform under the measurement pressure.

[0070] As the plastic substrate, a polyethylene terephthalate substrate or a polyethylene naphthalate substrate is preferable because it can be formed into a substrate with high hardness and flatness and can better achieve both measurement in a high-pressure region and color development density.

[0071] From the perspective of reproducibility of color development density in response to pressure application, a substrate that exhibits minimal deformation due to pressure application, is unaffected by the object being measured, and can suppress pressure dispersion that can cause a decrease in measurement accuracy is preferred. Preferred examples of such substrates include polyethylene naphthalate substrates and metal-containing substrates.

[0072] The hue of the substrate is preferably white because it can increase the contrast between the colored portion and the uncolored portion, further improving visual recognition. The white substrate is preferably a plastic substrate, more preferably a white polyethylene terephthalate substrate. The white polyethylene terephthalate substrate can be a polyethylene terephthalate substrate containing a known white colorant (e.g., white pigment).

[0073] The thickness of the substrate is not particularly limited, but is preferably 10 μm to 500 μm, more preferably 10 μm to 200 μm, from the perspective of ease of handling and the ability to supply the substrate in a roll form.

[0074] [Pressure-sensitive layer]

[0075] The pressure measuring material of the present invention has a pressure-sensitive layer on a substrate.

[0076] The pressure-sensitive layer is a layer containing a polymer matrix, microcapsules containing an electron-donating dye precursor and a solvent, and an electron-accepting compound.

[0077] (Polymer Matrix)

[0078] In the present invention, the term polymer matrix is ​​a constituent element of the pressure-sensitive layer, and is used to indicate a matrix containing a polymer compound having a molecular weight of 1000 or more (hereinafter also referred to as a specific polymer compound).

[0079] The specific polymer compound preferably functions as a binder in the pressure-sensitive layer. The specific polymer compound does not include compounds constituting microcapsules (including the contents of the microcapsules, the wall material, and the dispersant used to form the microcapsules) or electron-accepting compounds.

[0080] By containing the specific polymer compound in the pressure sensitive layer, it can be confirmed that the polymer matrix is ​​a constituent element of the pressure sensitive layer of the pressure measuring material of the present invention.

[0081] From the perspective of further improving the hierarchical properties of the high-pressure region, the specific polymer compound is preferably contained in an amount of 10% by mass or more, more preferably 20% by mass or more, relative to the total mass of the pressure-sensitive layer. When the amount of the specific polymer compound is 10% by mass or more, the external force (pressure) applied to the pressure measuring material is alleviated, making it easier to retain components such as microcapsules and electron-accepting compounds in the pressure-sensitive layer.

[0082] From the viewpoint of color development density, the content of the specific polymer compound forming the polymer matrix is ​​preferably 10 to 70% by mass, more preferably 20 to 50% by mass, relative to the total mass of the pressure-sensitive layer.

[0083] The specific polymer compound is not particularly limited and can be appropriately selected depending on the properties desired for the pressure-sensitive layer that is less likely to deform under measurement pressure.

[0084] The specific polymer compound may be used alone or in combination of two or more.

[0085] Examples of the specific polymer compound include polyvinyl alcohol, polyurethane-based polymers including polyurethane, vinyl chloride-based polymers, vinyl acetate-based polymers, acrylic polymers, styrene-butadiene rubber (SBR), and copolymers thereof.

[0086] Here, the polyurethane polymer, vinyl chloride polymer, vinyl acetate polymer, and acrylic polymer refer to polymers containing a structural unit having a urethane bond, a structural unit derived from vinyl chloride, a structural unit derived from vinyl acetate, and a structural unit derived from (meth)acrylic acid, respectively.

[0087] The specific polymer compound may be contained in the pressure-sensitive layer in the form of a dispersion.

[0088] From the viewpoint of applicability in microcapsule preparation and productivity in aqueous coating, one embodiment suitable for the specific polymer compound is polyvinyl alcohol.

[0089] The polyvinyl alcohol is not particularly limited and can be appropriately selected depending on the properties desired for the pressure-sensitive layer.

[0090] From the viewpoint of maintaining microcapsules and further improving the hierarchical properties in the high-pressure region, the degree of polymerization of the polyvinyl alcohol is preferably 100 to 10,000, more preferably 100 to 3,000.

[0091] From the viewpoint of maintaining microcapsules and further improving the hierarchical nature of the high-pressure region, the molecular weight of the specific polymer compound is 1000 or more, preferably 2,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more. The upper limit of the molecular weight is not particularly limited, and for example, 1,000,000 can be mentioned. From the viewpoint of ease of manufacture, the molecular weight is preferably 2,000 to 100,000, more preferably 5,000 to 100,000, and even more preferably 10,000 to 100,000. Here, the molecular weight of the specific polymer compound represents the number average molecular weight measured by gel permeation chromatography (GPC).

[0092] Specifically, the molecular weight is determined by gel permeation chromatography (GPC) using TSKgel GMHxL, TSKgel G4000HxL, or TSKgel G2000HxL (all trade names, manufactured by Tosoh Corporation) columns, using a THF (tetrahydrofuran) solvent and a differential refractometer, and is converted using polystyrene as a standard substance.

[0093] As the specific polymer compound, a commercially available product can also be used. Examples of commercially available products include PVA-105 (polyvinyl alcohol) and PVA-205 (polyvinyl alcohol) manufactured by KURARAY CO., LTD.; SUPERFLEX 170 (polyurethane polymer), SUPERFLEX 820 (polyurethane polymer), SUPERFLEX 830HS (polyurethane polymer), and SUPERFLEX 870 (polyurethane polymer) manufactured by DKS Co., Ltd.; ViniBran 287 (vinyl chloride / acrylic polymer), ViniBran 900 (vinyl chloride / acrylic polymer), ViniBran 2684 (acrylic polymer), ViniBran 2685 (acrylic polymer), ViniBran 2687 (acrylic polymer), and ViniBran 715S (vinyl chloride polymer) manufactured by Nissin Chemical Industry Co., Ltd.; Sumikaflex 752HQ (ethylene-vinyl acetate copolymer resin emulsion) and Sumikaflex 752HQ (ethylene-vinyl acetate copolymer resin emulsion) manufactured by Sumika Chemtex Company. 808HQ (ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion), Sumikaflex 850HQ (ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion), Sumikaflex 830 (ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion); Nipol LX433C (styrene butadiene rubber), Nipol LX2507H (styrene butadiene rubber), Nipol LX416 (styrene butadiene rubber), Nipol LX814 (acrylic polymer), Nipol LX855EX1 (acrylic polymer) manufactured by Zeon Corporation; Movinyl 742A (acrylic polymer), Movinyl 1711 (acrylic polymer), Movinyl 6520 (acrylic polymer), Movinyl 7980 (acrylic polymer), Movinyl 081F (vinyl acetate-ethylene copolymer), Movinyl 082 (vinyl acetate-ethylene copolymer); Smarttex SN-307R (styrene butadiene latex) manufactured by Nippon A&L Inc., etc.

[0094] One of the preferred physical properties as an indicator of the specific polymer compound forming the polymer matrix is ​​Martens hardness.

[0095] From the viewpoint of achieving both pressure measurement and color density in a high pressure range (preferably 100 MPa to 10,000 MPa, more preferably 300 MPa to 3,000 MPa), the polymer matrix of the present invention preferably has a Martens hardness of 100 N / mm 2 The above polymer compounds.

[0096] Contains Martens hardness 100N / mm through the polymer matrix 2 The above-mentioned polymer compounds are preferred because they suppress deformation of the pressure-sensitive layer even in pressure measurement in a high-pressure region of the pressure-sensitive layer and enable highly precise color development gradation to be obtained.

[0097] The Martens hardness of the polymer compound is preferably 140 N / mm 2 above.

[0098] The upper limit of the Martens hardness of the polymer compound is not particularly limited, but can be 300 N / mm. 2 the following.

[0099] Martens hardness can be determined using the nanoindentation method according to ISO 14577-1 (instrumented indentation hardness) as the value obtained by dividing the maximum test load by the indenter surface area at the maximum indentation depth of the indenter. For example, a microhardness tester such as the "HM2000" manufactured by FISCHER INSTRUMENTS KK can be used for the measurement.

[0100] The specific measurement method will be described in the Examples below.

[0101] (Microcapsules)

[0102] The pressure-sensitive layer contains microcapsules containing electron-donating dye precursors and solvents.

[0103] Microcapsules generally have a core and a capsule wall for enclosing a core material constituting the core (an included substance (also referred to as an included ingredient or inclusion)).

[0104] The microcapsules contain an electron-donating dye precursor and a solvent as core materials (internal components). Since the electron-donating dye precursor is contained in the microcapsules, the electron-donating dye precursor can exist stably until pressure is applied and the microcapsules are destroyed.

[0105] -Wall material of microcapsules-

[0106] As the wall material of the microcapsule, water-insoluble or oil-insoluble polymers used as the wall material of microcapsules containing electron-donating dye precursors of pressure-sensitive recording materials can be used without particular limitation. Among them, as the wall material, polyurethane urea, polyurethane, polyurea, melamine-formaldehyde resin and gelatin are preferred. From the viewpoint of obtaining good color development, polyurethane urea, polyurethane, polyurea and melamine-formaldehyde resin are more preferred, and polyurethane urea and polyurethane containing urethane bonds are particularly preferred.

[0107] The capsule wall of the microcapsule is preferably substantially composed of a resin. Substantially composed of a resin means that the content of the resin is 90% by mass or more, preferably 100% by mass, relative to the total mass of the capsule wall. In other words, the capsule wall of the microcapsule is preferably composed of a resin.

[0108] In addition, polyurethane is a polymer having a plurality of urethane bonds, and is preferably a reaction product formed from raw materials containing polyol and polyisocyanate.

[0109] Furthermore, polyurea is a polymer having multiple urea bonds and is preferably a reaction product formed from raw materials containing polyamines and polyisocyanates. In addition, polyurea can be synthesized using polyisocyanates instead of polyamines by reacting a portion of the polyisocyanates with water to form polyamines.

[0110] Polyurethane urea is a polymer having a polyurethane bond and a urea bond, and is preferably a reaction product formed from raw materials containing a polyol, a polyamine, and a polyisocyanate. In addition, when a polyol and a polyisocyanate are reacted, a portion of the polyisocyanate reacts with water to form a polyamine, resulting in a polyurethane urea.

[0111] Furthermore, the melamine-formaldehyde resin is preferably a reaction product formed by the polycondensation of melamine and formaldehyde.

[0112] The polyisocyanate is a compound having two or more isocyanate groups, and examples thereof include aromatic polyisocyanates and aliphatic polyisocyanates. Examples of the polyisocyanate include adducts of polyols such as trimethylolpropane and bifunctional polyisocyanates.

[0113] Furthermore, the above-mentioned polyols are compounds having two or more hydroxyl groups, for example, low molecular weight polyols (for example, aliphatic polyols, aromatic polyols. In addition, "low molecular weight polyols" refer to polyols with a molecular weight of 400 or less.), polyvinyl alcohol, polyether polyols, polyester polyols, polylactone polyols, castor oil polyols, polyolefin polyols and hydroxyl-containing amine compounds (for example, amino alcohols. As amino alcohols, for example, N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, which is an amino compound such as ethylenediamine and a propylene oxide or ethylene oxide adduct, can be mentioned.).

[0114] Furthermore, the polyamines are compounds having two or more amino groups (primary or secondary), and examples thereof include aliphatic polyamines such as diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, and hexamethylenediamine; epoxy 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.

[0115] The number average wall thickness δ of the microcapsules depends on various conditions such as the type of capsule wall material and the capsule diameter, but is preferably 0.02 μm to 3 μm, more preferably 0.05 μm to 2 μm, from the perspective of color development in a high-pressure region (preferably 100 MPa to 10,000 MPa, more preferably 300 MPa to 3,000 MPa).

[0116] The wall thickness of a microcapsule refers to the thickness (μm) of the resin film (so-called capsule wall) that forms the capsule particles of the microcapsule. The number-average wall thickness refers to the average value obtained by averaging the thickness (μm) of the capsule wall of five microcapsules obtained using a scanning electron microscope (SEM). Specifically, a microcapsule liquid is first applied to an arbitrary support and dried to form a coating film. A cross-sectional slice of the obtained coating film is prepared, and the cross-section is observed using an SEM. After selecting five arbitrary microcapsules, the cross-sections of the selected microcapsules are observed, the capsule wall thickness is determined, and the average value is calculated. The cross-sectional slice can also be made from a material for pressure measurement.

[0117] -Electron-donating dye precursor-

[0118] As an electron-donating dye precursor, any substance that can donate electrons or accept protons (hydrogen ions; H + ) The nature of the color development is not particularly limited, but is preferably colorless. The electron-donating dye precursor can function as a coloring agent.

[0119] In particular, the electron-donating dye precursor is preferably a colorless compound having a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, or amide, which undergoes ring-opening or cleavage when in contact with the electron-accepting compound described below.

[0120] Electron-donating dye precursors can use known substances in the purposes of pressure-sensitive copying paper or thermal recording paper. As electron-donating dye precursors, for example, various compounds such as triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, colorless golden ammonia compounds, rhodamine lactam compounds, triphenylmethane compounds, diphenylmethane compounds, triazine compounds, spiropyran compounds, and fluorene compounds can be enumerated.

[0121] For details of the above compounds, reference can be made to paragraphs

[0029] to

[0034] of Japanese Patent Application Laid-Open No. 5-257272 and International Publication No. 2009 / 8248.

[0122] The electron-donating dye precursor may be used alone or in combination of two or more.

[0123] In one embodiment of the present invention, from the viewpoint of visual recognition, the electron-donating dye precursor preferably has a high molar absorption coefficient (ε). The molar absorption coefficient (ε) of the electron-donating dye precursor is preferably 10,000 mol -1 cm -1 L or more, more preferably 15000 mol -1 cm -1 L or more, more preferably 25000 mol -1 cm -1 L and above.

[0124] The molar absorptivity (ε) can be calculated from the absorbance of an electron-donating leuco dye dissolved in a 95% by mass aqueous acetic acid solution. Specifically, in a 95% by mass aqueous acetic acid solution containing an electron-donating leuco dye whose concentration has been adjusted to an absorbance of 1.0 or less, the molar absorptivity (ε) can be calculated using the following formula, assuming the length of the measurement cell is A cm, the concentration of the electron-donating leuco dye is B mol / L, and the absorbance is C.

[0125] Molar absorptivity (ε) = C / (A×B)

[0126] From the viewpoint of improving the color development property in the pressure range of preferably 100 MPa to 10,000 MPa (more preferably 300 MPa to 3,000 MPa), the content (e.g., coating amount) of the electron-donating dye precursor in the pressure-sensitive layer is preferably 0.1 g / m2 based on the mass after drying. 2 ~5g / m 2 , more preferably 0.1 g / m 2 ~4g / m 2 , more preferably 0.2g / m 2 ~3g / m 2 .

[0127] -Solvents-

[0128] The microcapsules contain at least one solvent, which can function as an oil component for dissolving the electron-donating dye precursor.

[0129] As the solvent, a solvent known in the application of pressure-sensitive copy paper can be used.

[0130] From the viewpoint of stably dissolving the electron-donating dye precursor without precipitation, the solvent preferably contains 50% to 100% by mass of a solvent having a boiling point exceeding 130° C., more preferably 70% to 100% by mass, and even more preferably 90% to 100% by mass. The upper limit of the boiling point is not particularly limited, and for example, 500° C. is mentioned, and is preferably above 130° C. and below 500° C.

[0131] Examples of the solvent include 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; aromatic hydrocarbons such as arylindan compounds; ester compounds such as dibutyl phthalate; aliphatic hydrocarbons such as isoparaffin; natural animal and plant oils such as soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, coconut oil, castor oil, and fish oil; high-boiling-point fractions of natural products such as mineral oil; and the like.

[0132] The solvents may be used alone or in combination of two or more.

[0133] The mass ratio of the solvent to the electron-donating dye precursor contained in the microcapsule (solvent:precursor) is preferably in the range of 98:2 to 30:70, more preferably in the range of 97:3 to 40:60, and even more preferably in the range of 95:5 to 50:50, from the viewpoint of color development.

[0134] -Other ingredients-

[0135] In addition to the electron-donating dye precursor, solvent, and auxiliary solvent described above, the microcapsules may also contain additives as needed. Examples of additives include ultraviolet absorbers, light stabilizers, antioxidants, paraffin wax, and odor suppressants. Furthermore, the microcapsules may contain a solvent with a boiling point of 130°C or less (e.g., ketone compounds such as methyl ethyl ketone, ester compounds such as ethyl acetate, and alcohol compounds such as isopropyl alcohol) used in the manufacture of the microcapsules.

[0136] The content of the microcapsules in the pressure-sensitive layer (the coating amount when applied) is preferably 10 to 80% by mass, more preferably 10 to 60% by mass, and even more preferably 10 to 50% by mass, relative to the total solid mass of the pressure-sensitive layer.

[0137] -Method for producing microcapsules-

[0138] Microcapsules can be produced by any known method, for example, interfacial polymerization, internal polymerization, phase separation, external polymerization, and coacervation.

[0139] For examples of producing microcapsules using polyurethaneurea, polyurethane, and polyurea as capsule wall materials, see paragraphs

[0040] to

[0044] of Japanese Patent Application Laid-Open No. 2009-019949. Specifically, a method can be used in which a compound used to form a microcapsule wall material is mixed with a microcapsule core material and then reacted to form the microcapsules. When forming the microcapsules, a dispersant such as polyvinyl alcohol is preferably used.

[0140] (Electron-accepting compound)

[0141] The pressure-sensitive layer contains at least one electron-accepting compound, which can function as a color developer.

[0142] Examples of the electron-accepting compound include inorganic compounds and organic compounds.

[0143] Specific examples of the inorganic compound include clay substances such as acidic clay, activated clay, attapulgite, zeolite, bentonite, and kaolin.

[0144] Specific examples of the organic compound include metal salts of aromatic carboxylic acids (preferably metal salicylates), phenol formaldehyde resins, and metal salts of carboxylated terpene phenol resins.

[0145] Among them, the electron-accepting compound is preferably acidic clay, activated clay, zeolite, kaolin, metal salts of aromatic carboxylic acids, or metal salts of carboxylated terpene phenolic resins, and more preferably acidic clay, activated clay, kaolin, or metal salts of aromatic carboxylic acids.

[0146] Preferred specific examples of the aromatic carboxylic acid in the metal salt of the aromatic carboxylic acid include 3,5-di-tert-butylsalicylic acid, 3,5-di-tert-octylsalicylic acid, 3,5-di-tert-nonylsalicylic acid, 3,5-di-tert-dodecylsalicylic acid, 3-methyl-5-tert-dodecylsalicylic acid, 3-tert-dodecylsalicylic acid, 5-tert-dodecylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-bis(α,α-dimethylbenzyl)salicylic acid, The aromatic carboxylic acid includes, for example, 3-(α-methylbenzyl)salicylic acid, 3-methyl-5-(α-methylbenzyl)salicylic acid, 3-(α,α-dimethylbenzyl)-5-methylsalicylic acid, 3-(α,α-dimethylbenzyl)-6-methylsalicylic acid, 3-(α-methylbenzyl)-5-(α,α-dimethylbenzyl)salicylic acid, 3-(α,α-dimethylbenzyl)-6-ethylsalicylic acid, and 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid. Furthermore, carboxyl-modified terpene phenolic resins and salicylic acid resins obtained by reacting 3,5-bis(α-methylbenzyl)salicylic acid with benzyl chloride can also be used as aromatic carboxylic acids. Specific examples of metal salts of the metal salts of aromatic carboxylic acids include zinc salts, nickel salts, aluminum salts, and calcium salts.

[0147] The content of the electron-accepting compound in the pressure-sensitive layer (the coating amount when applied) is preferably 0.1 g / m 2 ~30g / m 2 When the electron accepting compound is an inorganic compound, the content thereof is more preferably 3 g / m2 in terms of dry mass. 2 ~20g / m 2 , more preferably 5g / m 2 ~15g / m 2 When the electron accepting compound is an organic compound, the content thereof is more preferably 0.1 g / m2 in terms of dry mass. 2 ~15g / m 2 , more preferably 0.2g / m 2 ~10g / m 2 .

[0148] (Oil-absorbing particles)

[0149] The pressure-sensitive layer preferably contains at least one type of oil-absorbing particles on the outside of the microcapsules.

[0150] Due to the high pressure applied to the pressure measuring material of the present invention, the solvent (oil component) contained in the microcapsules tends to leach out of the pressure-sensitive layer. This oil leaching is undesirable because it causes oil stains. In contrast, the inclusion of microcapsule-containing external oil-absorbing particles in the pressure-sensitive layer effectively suppresses the leaching of the oil component out of the pressure-sensitive layer.

[0151] In the present invention, the "oil-absorbing particles" refer to particles showing that the oil absorption of linseed oil at 25°C is 50% by mass or more of the particle's own weight.

[0152] The oil absorption is measured in accordance with JIS-K5101-13-1:2004.

[0153] Examples of the shape of the particles include spherical, elliptical, and rod-shaped shapes, but other shapes are also possible.

[0154] The particle size of the oil-absorbing particles is preferably 0.5 μm to 20 μm, more preferably 1 μm to 10 μm, and even more preferably 2 μm to 8 μm.

[0155] The particle size of the oil-absorbing particles can be measured by Microtrac MT3300EXII (manufactured by Nikkiso Co., Ltd.).

[0156] Examples of the oil-absorbing particles include inorganic particles such as porous silica particles, calcium carbonate, kaolin, aluminum silicate, calcium silicate, colloidal silica, alumina, and aluminum hydroxide; and polymer particles such as polyolefin, acrylic acid, polystyrene, and polyester. Preferably, the oil-absorbing particles are at least one inorganic particle selected from the group consisting of porous silica particles, calcium carbonate, and kaolin.

[0157] The oil-absorbing particles may be an electron-accepting compound serving as a color developer that has oil-absorbing properties.

[0158] As the oil-absorbing particles, commercially available products can be used, and examples thereof include "Brilliant Series" manufactured by Shiraishi Group ALL RIGHTS RESERVED.

[0159] The content of the oil-absorbing particles in the pressure-sensitive layer can be appropriately set according to the desired oil absorption.

[0160] (Inorganic particles)

[0161] The pressure-sensitive layer preferably contains at least one inorganic particle that is not an electron-accepting compound on the outside of the microcapsule.

[0162] Examples of the inorganic particles include porous silica particles, calcium carbonate, kaolin, aluminum silicate, calcium silicate, colloidal silica, aluminum oxide, and aluminum hydroxide, with silica being preferred. The inorganic particles may be the inorganic particles described above for the oil-absorbing particles.

[0163] As the inorganic particles, commercially available products can be used, and examples thereof include "Mizukasil series" manufactured by Mizusawa Industrial Chemicals, Ltd., and the like.

[0164] The particle size of the inorganic particles is preferably 1 μm to 30 μm, more preferably 5 μm to 20 μm.

[0165] (Other ingredients)

[0166] Examples of other components that may be contained in the pressure-sensitive layer include surfactants, fluorescent whitening agents, defoaming agents, penetrants, ultraviolet absorbers, and preservatives.

[0167] (Thickness t of pressure-sensitive layer)

[0168] The thickness t of the pressure-sensitive layer is not particularly limited and can be selected according to the purpose and the like.

[0169] The thickness t of the pressure-sensitive layer is preferably 1 μm to 250 μm, more preferably 3 μm to 200 μm, further preferably 5 μm to 150 μm, and particularly preferably 5 μm to 50 μm.

[0170] When the pressure sensitive layer includes a color developing layer and a color developing layer as described in the second embodiment below, the thickness of the pressure sensitive layer is the sum of the thickness of the color developing layer and the thickness of the color developing layer.

[0171] The thickness t of the pressure-sensitive layer can be measured by microscopic observation.

[0172] Specifically, the pressure-measuring material to be measured can be cut vertically to produce a cross-sectional slice, which can then be observed using a scanning electron microscope (SEM). The thickness of the pressure-sensitive layer can be determined from the image. An example of a scanning electron microscope is the tabletop microscope "Miniscope TM3030 Plus" (manufactured by Hitachi High-Technologies Corporation).

[0173] In addition, the thickness of the pressure-sensitive layer in the present invention is the arithmetic mean of the thicknesses at 10 randomly selected locations.

[0174] The coefficient of variation (CV value; hereinafter also referred to as CV value) of the particle size distribution of all particles contained in the pressure-sensitive layer is preferably 20% to 150%.

[0175] When the CV value is within the above range, the particle distribution in the pressure-sensitive layer, particularly the relative deviation of the microcapsules, is small, and thus the color development property is excellent.

[0176] The CV value is preferably 20% to 110%, more preferably 25% to 80%.

[0177] The CV value represents the relative variation of particles contained in the pressure-sensitive layer and is a value obtained as follows.

[0178] CV value (%) = standard deviation / arithmetic mean particle size × 100

[0179] The arithmetic mean particle size and standard deviation are values ​​calculated by photographing the surface of the pressure-sensitive layer at 150 times magnification using an optical microscope and measuring the sizes of all microcapsules in a randomly set area of ​​2 cm×2 cm.

[0180] (Layer Structure of Pressure-Sensitive Layer)

[0181] The layer structure of the pressure-sensitive layer of the present invention may be a single-layer structure or a multi-layer structure.

[0182] One embodiment of the layer structure of the pressure-sensitive layer can be an embodiment in which microcapsules and electron-accepting compounds are contained in a polymer matrix. The pressure-sensitive layer adopting this embodiment will be described in detail using the pressure-sensitive layer of the first embodiment described below as an example.

[0183] Another embodiment of the pressure-sensitive layer of the present invention can include a color-developing layer containing an electron-accepting compound and a polymer matrix and a color-producing layer containing microcapsules.

[0184] <First Method>

[0185] A first embodiment of the pressure-sensitive layer of the present invention is a pressure-sensitive layer in which microcapsules and an electron-accepting compound are contained in a polymer matrix.

[0186] The details of the components (specific polymer compound, microcapsule, electron-accepting compound, etc.) used in the pressure-sensitive layer according to the first embodiment are the same as those described above, and the preferred embodiments are also the same.

[0187] In the present invention, a component "contained in a polymer matrix" means that at least a portion of the component is contained in the pressure-sensitive layer in a state of contact with the specific polymer compound. The contained state may be either dispersed or dissolved. In the case of a solid, the contained state may be partially exposed on the surface of the pressure-sensitive layer.

[0188] Specifically, in the case of microcapsules, the present invention encompasses both a state in which the entire microcapsule is contained within the polymer matrix and is present within the pressure-sensitive layer, and a state in which a portion of the capsule wall of the microcapsule is exposed on the surface of the pressure-sensitive layer. Here, the state in which the entire microcapsule is in contact with the specific polymer compound encompasses both a state in which the microcapsule itself, consisting of the contents and the wall material, is in direct contact with the specific polymer compound, and a state in which the microcapsule is in contact with the specific polymer compound via a dispersant.

[0189] Appropriate reference Figure 2 An example of a pressure measuring material having the pressure-sensitive layer according to the first embodiment will be described.

[0190] Figure 2 1 is a schematic cross-sectional view showing an example of a pressure measuring material having a pressure sensitive layer according to the first embodiment. Figure 2 These are diagrams for explaining the first embodiment, and the components shown in the diagram do not correspond to actual sizes and ratios.

[0191] exist Figure 2 In the pressure measuring material 10 shown, a pressure-sensitive layer 14 is provided on a substrate 12. The pressure-sensitive layer 14 comprises microcapsules 18 and an electron-accepting compound 15. Reference numeral 18a denotes the capsule wall of the microcapsule, and reference numeral 18b denotes the contents of the microcapsule (i.e., the core material). Reference numeral 16 denotes a polymer matrix containing a specific polymer compound (not shown).

[0192] The pressure measurement material having the pressure-sensitive layer according to the first aspect is particularly preferably an aspect that can be used within a pressure range of 500 MPa or more.

[0193] From the perspective of excellent layering in the high-pressure region of 500 MPa or higher, the pressure measuring material according to the first embodiment preferably has an arithmetic mean roughness Ra of less than 2.0 μm. In other words, the majority of the microcapsules and electron-accepting compound are preferably located within the polymer matrix, rather than being exposed on the surface of the pressure-sensitive layer.

[0194] In the present invention, the arithmetic mean roughness Ra of the pressure measurement material refers to the arithmetic mean roughness Ra specified in JIS B 0681-6: 2014. A scanning white interferometer utilizing optical interference (specifically, NewView5020 manufactured by Zygo Corporation: Stich mode; objective lens ×50; intermediate lens ×0.5) was used as the measurement apparatus.

[0195] The arithmetic mean roughness Ra corresponds to the arithmetic mean roughness Ra of the surface opposite to the substrate side. The arithmetic mean roughness Ra of the pressure measuring material according to the first embodiment is preferably 0 μm or more and less than 2.0 μm, more preferably 0 μm to 1.0 μm, and even more preferably 0 μm to 0.5 μm.

[0196] Methods for reducing the arithmetic mean roughness Ra to less than 2.0 μm include increasing the amount of the specific polymer compound in the pressure sensitive layer. The specific polymer compound is preferably 20% by mass or more based on the total solid content constituting the pressure sensitive layer.

[0197] From the viewpoint of excellent layering properties in a high-pressure region of 500 MPa or higher, the pressure measuring material having the pressure-sensitive layer according to the first embodiment preferably has a void volume of 5 mL / m 2 When the void volume is low, the microcapsules are difficult to break before being pressurized at 500 MPa or above and are easy to withstand. The void volume is preferably 0 mL / m 2 ~5mL / m 2 , more preferably 0 mL / m 2 ~3mL / m 2 , more preferably 0 mL / m 2 ~1mL / m 2 .

[0198] Here, the void amount is a value obtained by the following formula.

[0199] Measure the mass (m1) of a pressure measuring material cut into 10 cm x 10 cm pieces. Next, allow diethylene glycol to penetrate the surface of the pressure measuring material on the side with the pressure-sensitive layer. After wiping off any remaining diethylene glycol, measure the mass (m2). If X = m2 - m1, the void volume can be calculated using the following formula. The density of diethylene glycol is 1.118.

[0200] Void volume (m1 / m2) = 100 × X ÷ 1.118

[0201] From the viewpoint of reducing void content, the electron accepting compound contained in the pressure-sensitive layer of the first mode preferably contains an organic compound, more preferably contains as a main component, and more preferably has 50 mass % to 100 mass %. As a preferred electron accepting compound, the compound identical with the above-mentioned compound can be cited, preferably containing a metal salt of an aromatic carboxylic acid, wherein, especially preferably containing a metal salt of salicylic acid. In addition, in this specification, "containing as a main component" refers to the component with the highest content in the electron accepting compound.

[0202] From the viewpoint of better layering in the high-pressure region, the content (volume fraction) of the microcapsules relative to the pressure-sensitive layer is preferably 10% to 80% by volume, more preferably 20% to 60% by volume, and even more preferably 30% to 60% by volume.

[0203] The content (volume fraction) of the microcapsules relative to the pressure-sensitive layer can be measured by the following method. Figure 2 Provide explanation.

[0204] A cross-sectional slice of the pressure measurement material 10 was made and observed at 1000 times by a scanning electron microscope (SEM). From the SEM image of the cross section, the inside (inclusions 18b) of the observed microcapsule 18 and the matrix portion containing the capsule wall 18a, the polymer matrix 16 of the specific polymer compound (not shown) and the electron-accepting compound 15 can be distinguished. For all microcapsules 18 present in the observed visual field, the inside (inclusions 18b) of the microcapsule 18 and the matrix portion containing the capsule wall 18a, the polymer matrix 16 of the specific polymer compound and the electron-accepting compound 15 were separated by image analysis, and the area of ​​the microcapsule inside and the area of ​​the above-mentioned matrix portion were calculated respectively. The content A (area %) of the microcapsule inside was obtained according to the ratio. Then, in a direction orthogonal to the above-mentioned cross-sectional slice and orthogonal to the substrate, a cross-sectional slice was further made and the content B (area %) of the microcapsule inside was obtained in the same manner. The average value of the content A (area %) of the microcapsule inside and the content B (area %) of the microcapsule inside was calculated. This operation was performed at two randomly selected locations, and the average of the average values ​​obtained at the two locations was taken as the microcapsule content (volume %).

[0205] -Microcapsule particle size d1-

[0206] In the first embodiment, the "microcapsule particle size d1" refers to the volume-based median diameter.

[0207] The volume-based median diameter of microcapsules refers to the diameter (DSO) at which the volumes of the larger and smaller diameter particles are equal, when the total volume of all microcapsules contained in the pressure-sensitive layer is divided into two using the particle size at which the cumulative volume accounts for 50%.

[0208] The volume-based median diameter of microcapsules is calculated by coating a microcapsule solution on a support, photographing the surface of the dried coating film at 150x magnification using an optical microscope, and measuring the sizes of all microcapsules within a 2 cm x 2 cm area.

[0209] From the viewpoint of color development in a high pressure region (preferably 100 MPa to 10,000 MPa, more preferably 300 MPa to 3,000 MPa), the particle size d1 of the microcapsule is preferably 1 μm to 50 μm, more preferably 5 μm to 30 μm.

[0210] From the viewpoint of achieving both the height of the measured pressure and the color density, the ratio of the thickness t of the pressure-sensitive layer to the particle size d1 of the microcapsules contained in the pressure-sensitive layer preferably satisfies the relationship represented by the following formula 1.

[0211] 1<t / d1<5……Formula 1

[0212] When t / d1<5, more excellent color development properties can be obtained, and when 1<t / d1, fogging can be easily suppressed.

[0213] -Inner diameter of microcapsule p1-

[0214] From the viewpoint of better layering in the high-pressure region and color development in the high-pressure region, the inner diameter p1 of the microcapsule is preferably 0.5 to 50 μm, more preferably 1 to 30 μm, and even more preferably 2 to 20 μm.

[0215] In the first embodiment, the "inner diameter p1 of the microcapsule" is a value obtained by the following method. Figure 2 Provide explanation.

[0216] Make the cross section slice of pressure measurement material 10, observe this cross section with 1000 times by scanning electron microscope (SEM).From the SEM image of cross section, can distinguish the inside (inclusion 18b) of observation microcapsule 18 and the high molecular matrix 16 containing capsule wall 18a, specific high molecular compound and the matrix part containing electron accepting compound 15.In the microcapsule 18 existing in the observed visual field, measure the major diameter (inner diameter) of 10 microcapsules successively from the largest microcapsule, carry out arithmetic average and find average value.Implement this operation in 5 visual fields, find the average of the average value obtained in each position, using the obtained value as the average inner diameter of microcapsule.In addition, major diameter refers to the longest inner diameter when observing microcapsule.

[0217] <Method 2>

[0218] The second embodiment of the pressure-sensitive layer of the present invention is a pressure-sensitive layer comprising a color-developing layer having an electron-accepting compound and a polymer matrix and a color-forming layer having microcapsules, and comprising a substrate, a color-developing layer, and a color-forming layer in this order, wherein the thickness of the color-forming layer is less than half the thickness of the color-developing layer.

[0219] The details of the components (specific polymer compound, microcapsule, electron-accepting compound, etc.) used in the pressure-sensitive layer according to the second embodiment are the same as those described above, and the preferred embodiments are also the same.

[0220] An example of a pressure measuring material having a pressure-sensitive layer according to the second embodiment will be described with reference to the drawings.

[0221] Figure 3 : is a schematic cross-sectional view showing an example of a pressure measuring material having a pressure sensitive layer according to the second embodiment. Figure 3 These are diagrams for explaining the second embodiment, and the components shown in the diagram do not correspond to actual sizes and ratios.

[0222] exist Figure 3 In the pressure measuring material 20 shown, a pressure-sensitive layer 24 is provided on a substrate 22. It is composed of a chromogenic layer 24a and a color-developing layer 24b. The chromogenic layer 24a contains microcapsules 28, while the color-developing layer 24b contains a polymer matrix 26 containing an electron-accepting compound 25 and a specific polymer compound. 28a represents the capsule wall of the microcapsules, and 28b represents the contents of the microcapsules (i.e., the core material). The chromogenic layer 24a preferably contains the specific polymer compound.

[0223] From the perspective of achieving superior layering in high-pressure regions of 100 MPa or higher, the thickness of the chromogenic layer is preferably no more than half the thickness of the color-developing layer, and more preferably no more than one-third. There is no particular lower limit. In one embodiment of the present invention, the thickness of the chromogenic layer is preferably 0.001 to 0.5 times the thickness of the color-developing layer, more preferably 0.001 to 0.4 times, and even more preferably 0.001 to 0.33 times the thickness of the color-developing layer.

[0224] The thickness of the color-forming layer and the color-developing layer can be measured by microscopic observation.

[0225] Specifically, the pressure measurement material to be measured was cut vertically to produce a cross-sectional slice. This cross-sectional slice was observed using a scanning electron microscope (SEM) with a field of view of 800 μm x 600 μm. From this image, the thickness of the color-forming layer and the color-developing layer were measured at 10 locations at 50 μm intervals. The arithmetic mean of these values ​​was calculated as the thickness of the color-forming layer and the color-developing layer. An example of a scanning electron microscope is the tabletop microscope "Miniscope™ 3030 Plus" (manufactured by Hitachi High-Technologies Corporation).

[0226] In addition, if Figure 3 As shown, when there is a position where no microcapsule exists in the color-forming layer, the color-forming layer is counted as 0 μm.

[0227] The second embodiment is particularly preferably usable within a pressure range of 100 MPa to 500 MPa. From the perspective of excellent layering in the high-pressure region of 100 MPa to 500 MPa, the void volume of the pressure measuring material containing the pressure-sensitive layer according to the second embodiment is preferably 5 mL / m 2 ~20mL / m 2 , more preferably more than 8mL / m 2 and 15mL / m 2 The void volume is the value obtained by the above formula.

[0228] From the viewpoint of making the void amount within a specific range, the electron accepting compound in the second embodiment preferably contains inorganic particles, more preferably contains as the main component, and more preferably contains 50% by mass to 100% by mass. As preferred electron accepting compounds, the same compounds as those mentioned above can be cited, preferably containing acidic clay or activated clay. The electron accepting compound in the second embodiment can be mainly inorganic particles, or can contain other electron accepting compounds.

[0229] The pressure sensitive layer in the second embodiment preferably contains inorganic particles other than the electron-accepting compound from the viewpoint of excellent layering properties in the high-pressure region of 100 MPa to 500 MPa. Examples of the inorganic particles other than the electron-accepting compound include the same particles as described above, preferably silicon dioxide.

[0230] From the viewpoint that the hierarchical property of the high-pressure region of 100MPa~500MPa is more excellent, the pressure-sensitive layer (preferably color-developing layer) in the second mode preferably contains inorganic particles as electron-accepting compound, and has inorganic particles that are not electron-accepting compound. By having inorganic particles as electron-accepting compound and inorganic particles that are not electron-accepting compound simultaneously, it is possible to suppress the probability of the electron-donating dye precursor flowing out from microcapsule contacting with the electron-accepting compound under the state that the void volume is maintained in a specific range, therefore it is possible to use as a hierarchical material suitable for the high-pressure region of 100MPa~500MPa.

[0231] From the viewpoint of excellent layering properties in a high-pressure region of 100 MPa to 500 MPa, the pressure measurement material according to the second embodiment preferably has an arithmetic mean roughness Ra of 2.0 μm to 10.0 μm.

[0232] The arithmetic mean roughness Ra corresponds to the arithmetic mean roughness Ra of the surface on the side opposite to the substrate side. The arithmetic mean roughness Ra of the pressure measurement material according to the second embodiment is preferably 2.0 μm to 8.0 μm, and more preferably 2.0 μm to 5.0 μm.

[0233] As a method for adjusting the arithmetic mean roughness Ra to 2.0 μm to 10.0 μm, for example, the methods shown in the following (1) and (2) and a method of combining these methods can be cited.

[0234] (1) Method for thinning the color layer

[0235] Since the microcapsules are not arranged on the entire surface of the pressure-sensitive layer, the presence or absence of microcapsules on the surface of the pressure-sensitive layer can be adjusted, which is a method for adjusting the surface roughness.

[0236] (2) Method of increasing the amount of inorganic particles in the color-developing layer

[0237] This method is a method for adjusting the surface roughness of the color-developing layer by utilizing the difference between the locations where inorganic particles are present and the locations where they are absent.

[0238] In particular, when the amount of inorganic particles (the total amount of inorganic particles serving as the electron-accepting compound and inorganic particles other than the electron-accepting compound) is greater than the total amount of the specific polymer compound in the color-developing layer, particles appear on the surface of the color-developing layer, which can easily become rough. Furthermore, when microcapsules and the specific polymer compound are arranged in a thin layer, the microcapsules can enter the recessed areas of the roughened color-developing layer, resulting in an arithmetic mean roughness Ra of the pressure measurement material that is likely to fall between 2.0 μm and 10.0 μm.

[0239] In the above-mentioned state where the arithmetic mean roughness Ra is 2.0μm to 10.0μm, microcapsules that will not break even under high-pressure conditions exist in the concave portion of the color-developing layer, or areas where no microcapsules exist on the surface are generated. Therefore, it is believed that the second method of pressure measurement material can become a method suitable for high-pressure areas of 100MPa to 500MPa.

[0240] Furthermore, in the second embodiment, the microcapsules are preferably not present on the entire surface of the pressure-sensitive layer opposite to the substrate side, and the proportion of the microcapsules is preferably 95 area % or less, more preferably 90 area % or less.

[0241] The ratio of microcapsules is determined by first observing the surface of the chromogenic layer at any position using a laser microscope (KEYENCE VK-8510, field of view: 100 μm × 150 μm). The total number of microcapsules observed within the field of view is measured. The area corresponding to the number of microcapsules observed within the field of view is then calculated by image analysis and divided by the field of view area to determine the ratio.

[0242] From the perspectives of allowing the microcapsules to easily enter the recessed portions of the color-developing layer and achieving excellent layering in the high-pressure region of 100 MPa to 500 MPa, the total solids content of the color-forming layer composition is preferably less than the total solids content of the color-developing layer composition. Preferably, the total solids content of the color-forming layer composition is 0.001 to 0.45 times, and more preferably 0.005 to 0.25 times, the total solids content of the color-developing layer composition.

[0243] -Microcapsule particle size d2-

[0244] In the second embodiment, "microcapsule particle size d2" refers to an average particle size.

[0245] The average particle size of the microcapsules was determined by analyzing an image captured from the surface of the chromogenic layer containing the microcapsules using an optical microscope (OLYMPUS BX60, field of view: 320 μm x 450 μm). The major diameter (particle diameter) of 30 microcapsules, starting with the largest microcapsule, was measured and the average value was calculated by arithmetic averaging. This procedure was performed at five random locations (five fields of view) on the first layer, and the average of the average values ​​obtained at each location was calculated. The average value obtained was used as the average particle size of the microcapsules. The major diameter refers to the longest diameter of the microcapsules when observed.

[0246] From the viewpoint of color development in a high pressure region (preferably 100 MPa to 10,000 MPa, more preferably 300 MPa to 3,000 MPa), the particle size d2 of the microcapsule is preferably 1 μm to 50 μm, more preferably 5 μm to 30 μm.

[0247] -Inner diameter of microcapsule p2-

[0248] From the viewpoint of better layering in the high-pressure region of 100 MPa to 500 MPa and color development in the high-pressure region, the inner diameter p2 of the microcapsule is preferably 1 μm to 50 μm, more preferably 2 μm to 20 μm, and even more preferably 2 μm to 15 μm.

[0249] In the second embodiment, the "inner diameter p2 of the microcapsule" is a value obtained by the following method.

[0250] First, the wall thickness of the microcapsule is determined. The wall thickness of the microcapsule refers to the thickness (μm) of the capsule wall of the capsule particles that form the microcapsule, and the number-average wall thickness refers to the average value obtained by averaging the thickness (μm) of the capsule wall of 5 microcapsules obtained by scanning electron microscopy (SEM). More specifically, a cross-sectional slice of the microcapsules present in the pressure measurement material is made, and the cross-section is observed at 15,000 times by SEM. After selecting any 5 microcapsules with a long diameter ranging from (the value of the average particle size of the microcapsule) × 0.9 to (the value of the average particle size of the microcapsule) × 1.1, the cross-sections of the selected microcapsules are observed, the thickness of the capsule wall is determined, and the average value is calculated. In addition, the long diameter refers to the longest diameter when observing the microcapsule. Moreover, the value of the average particle size divided by twice the wall thickness of the microcapsule is calculated as the inner diameter of the microcapsule.

[0251] <Formation of Pressure-Sensitive Layer>

[0252] The formation of the pressure-sensitive layer is not particularly limited as long as it is based on the process of forming the pressure-sensitive layer, and the pressure-sensitive layer contains: a polymer matrix, which has a polymer compound (specific polymer compound) with a molecular weight of more than 1000; microcapsules, which contain an electron-donating dye precursor and a solvent; and an electron-accepting compound.

[0253] In the first embodiment, the pressure-sensitive layer can be formed by preparing a pressure-sensitive layer-forming composition, applying (for example, coating) the composition on a substrate, and drying the composition.

[0254] That is, the pressure measuring material having a pressure-sensitive layer of the first mode is preferably obtained by a manufacturing method including a step of arranging a pressure-sensitive layer forming composition on a substrate, wherein the pressure-sensitive layer forming composition contains: a polymer matrix containing a specific polymer compound; microcapsules containing an electron-donating dye precursor and a solvent; and an electron-accepting compound.

[0255] The pressure-sensitive layer forming composition for forming the pressure-sensitive layer of the first mode can be prepared, for example, by preparing a dispersion of microcapsules, mixing the obtained dispersion, a solution (or emulsion) of a specific polymer compound (a polymer compound forming a polymer matrix), an electron-accepting compound and other arbitrary components (for example, oil-absorbing particles, etc.).

[0256] Furthermore, in the second embodiment, the pressure-sensitive layer can be formed, for example, by preparing two compositions consisting of a color-forming layer composition and a color-forming layer composition as the pressure-sensitive layer-forming composition, applying the color-forming layer composition to a substrate (e.g., coating), applying the color-forming layer composition thereon (e.g., coating), and drying. The color-forming layer-forming composition can be prepared, for example, by preparing a dispersion of microcapsules and mixing the obtained dispersion with a solution (or emulsion) of a specific polymer compound and other optional components (e.g., surfactants). The color-forming layer-forming composition can be prepared, for example, by mixing an electron-accepting compound, a solution (or emulsion) of a specific polymer compound, and other optional components (e.g., inorganic particles).

[0257] That is, the pressure measuring material having the second mode of pressure-sensitive layer is preferably obtained by the following manufacturing method, which includes the following steps: a step of obtaining a color-forming composition containing microcapsules containing an electron-donating dye precursor and a solvent (preferably a solvent with a boiling point of 130°C or above) and a solvent (preferably a solvent with a boiling point of 130°C or below); a step of obtaining a color-developing layer forming composition containing an electron-accepting compound and a polymer compound (specific polymer compound) with a molecular weight of 1000 or above; a step of arranging the above-mentioned color-developing layer forming composition on a substrate to form a color-developing layer; and a step of arranging the above-mentioned color-developing layer forming composition on the above-mentioned color-developing layer to form a color-developing layer.

[0258] Furthermore, the color-forming layer-forming composition preferably contains a polymer compound (specific polymer compound) having a molecular weight of 1,000 or more.

[0259] The specific polymer compound contained in the color-developing layer-forming composition and the specific polymer compound preferably contained in the color-forming layer-forming composition may each be a single compound or a combination of two or more compounds. Furthermore, the specific polymer compound contained in the color-developing layer-forming composition and the specific polymer compound preferably contained in the color-forming layer-forming composition may be the same polymer compound or different polymer compounds.

[0260] The specific preparation method, coating amount, drying conditions, etc. of the pressure-sensitive layer-forming composition in forming the pressure-sensitive layer may be appropriately determined depending on the types of components contained in the pressure-sensitive layer-forming composition and the specific form of the target pressure measuring material.

[0261] When the pressure-sensitive layer is formed by coating the pressure-sensitive layer-forming composition on the substrate, the coating can be performed by a known coating method. Examples of the coating method include coating methods using 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, a knife coater, and the like.

[0262] [Other layers]

[0263] The pressure measuring material of the present invention may have other layers besides the pressure-sensitive layer on the base material.

[0264] Examples of the other layers include a protective layer, a white layer, and an easily adhesive layer.

[0265] - Protective layer -

[0266] The pressure measuring material of the present invention may further include a protective layer on the side of the pressure sensitive layer opposite to the side having the substrate. The pressure measuring material of the present invention may include a protective layer as the outermost layer, but is not limited to this embodiment.

[0267] Due to the high pressure applied to the pressure measuring material of the present invention, the solvent (oil component) contained in the microcapsules tends to leach out of the pressure-sensitive layer. This oil leaching is undesirable because it causes oil stains. However, the protective layer in the pressure measuring material effectively suppresses the leaching of the oil component out of the pressure-sensitive layer.

[0268] Therefore, the protective layer is preferably a layer having low permeability to oil components.

[0269] The protective layer can be provided by attaching a protective layer-forming sheet or film to the pressure-sensitive layer.

[0270] When providing the protective layer by laminating a protective layer-forming sheet or film, a desired protective layer-forming sheet or film may be prepared and laminated onto the pressure-sensitive layer by a known method (eg, lamination with an adhesive).

[0271] The thickness of the protective layer is not particularly limited and can be selected according to the purpose and the like.

[0272] The thickness of the protective layer is preferably 0.1 μm to 50 μm, more preferably 0.5 μm to 10 μm.

[0273] -White layer-

[0274] The pressure measuring material of the present invention may further include a white layer between the substrate and the pressure sensitive layer.

[0275] By having a white layer, the contrast between the colored portion and the non-colored portion can be increased, thereby improving visibility.

[0276] The white layer may be a coating layer formed between the substrate and the pressure-sensitive layer using the white layer-forming composition, or may be a layer formed by attaching a white layer-forming sheet or film to the substrate before providing the pressure-sensitive layer.

[0277] The white layer can be provided as a layer containing, for example, a known white coloring material (for example, a white pigment), a resin component, or the like.

[0278] Specific examples of the white colorant include white pigments such as titanium dioxide, zinc oxide, and calcium carbonate.

[0279] The white layer is a layer that does not contain the aforementioned microcapsules and / or electron-accepting compound.

[0280] When forming the white layer by coating the white layer-forming composition, for example, the white layer-forming composition is prepared, applied (eg, coated) to the substrate, and dried.

[0281] When forming the white layer by attaching a white layer forming sheet or film, a desired white layer forming sheet or film may be prepared and attached to the substrate by a known method (eg, attachment with an adhesive).

[0282] - Easy Adhesion Layer -

[0283] In order to improve the adhesion between the substrate and the pressure-sensitive layer, it is preferable to provide an easy-adhesion layer.

[0284] When the pressure measuring material of the present invention has an easily adhesive layer, it is preferable that the material has at least a base material, an easily adhesive layer, and a pressure sensitive layer in this order.

[0285] When the adhesive layer and the white layer are provided, it is preferred to provide a substrate, an adhesive layer, a white layer, and a pressure-sensitive layer in this order.

[0286] The easy-adhesion layer is a layer that does not contain the above-mentioned microcapsules and / or electron-accepting compound.

[0287] From the viewpoint of improving the adhesion between the substrate and the polymer matrix of the pressure-sensitive layer, the easily adhesive layer preferably contains a resin.

[0288] Examples of the resin include acrylic resins, polyurethane resins, styrene resins, and vinyl resins.

[0289] The easily adhesive layer may be a layer containing a polyurethane polymer, blocked isocyanate, or the like.

[0290] The easily adhesive layer can be formed by laminating a substrate and a sheet or film having easy adhesiveness, or by coating an easily adhesive layer forming composition on the substrate.

[0291] The thickness of the easily adhesive layer is not particularly limited and can be selected according to the purpose and the like.

[0292] The thickness of the easily adhesive layer is preferably 0.005 μm to 1.0 μm, more preferably 0.005 μm to 0.5 μm, further preferably 0.005 μm to 0.2 μm, and even more preferably 0.01 μm to 0.1 μm.

[0293] (Thickness of material for pressure measurement)

[0294] The thickness of the pressure measuring material of the present invention is not particularly limited, but is preferably 10 μm to 800 μm, and more preferably 10 μm to 500 μm.

[0295] -Thickness T-

[0296] The thickness T of the layer obtained by subtracting the thickness of the substrate from the thickness of the pressure measuring material is preferably 1 μm to 250 μm, more preferably 3 μm to 200 μm, and even more preferably 5 μm to 150 μm.

[0297] The thickness T can be measured by the same method as the thickness t of the pressure-sensitive layer described above.

[0298] Specifically, the thickness of the pressure measuring material and the thickness of the substrate are measured at 10 randomly selected locations, and the calculated values ​​are arithmetic averaged based on the difference between the thickness of the pressure measuring material and the thickness of the substrate.

[0299] (Arithmetic mean roughness Ra of the material for pressure measurement)

[0300] The arithmetic mean roughness Ra of the pressure measurement material is preferably 10.0 μm or less.

[0301] The preferred ranges of the arithmetic mean roughness Ra of the pressure sensitive layer in the first embodiment and the second embodiment are as described above, respectively.

[0302] The arithmetic mean roughness Ra corresponds to the arithmetic mean roughness Ra of the surface on the side opposite to the substrate side. The method for measuring the arithmetic mean roughness Ra is as described above.

[0303] (Ratio of thickness T to inner diameter p of microcapsule)

[0304] The ratio (T / p) of the thickness T of the pressure measuring material to the inner diameter p of the microcapsule is preferably 1.2 or greater, more preferably 1.3 or greater. When T / p is 1.2 or greater, the layering properties in the high-pressure region of 100 MPa or greater are more excellent. A ratio of 1.2 to 5 is more preferred.

[0305] In the case of the pressure-sensitive layer of the first embodiment, the ratio T / p1 of the thickness T to the inner diameter p1 of the microcapsule is preferably 5 or less, more preferably 1.2 to 5, and even more preferably 1.2 to 3.

[0306] In the case of the second embodiment of the pressure-sensitive layer, the ratio T / p2 of the thickness T to the inner diameter p2 of the microcapsule is preferably 5 or less, more preferably 1.2 to 5, and even more preferably 1.3 to 5.

[0307] <Matters related to pressure measurement>

[0308] Pressure measurement using the pressure measuring material of the present invention can be performed by placing the pressure measuring material at a location where pressure or pressure distribution is to be measured and applying pressure to the pressure measuring material in this state.

[0309] The pressure may be any of point pressure, line pressure, and surface pressure.

[0310] When the pressure measuring material of the present invention develops color, the concentration difference (ΔD) obtained by subtracting the concentration after color development at a pressure of 2000 MPa from the concentration after color development at a pressure of 1000 MPa is preferably 0.6 or more.

[0311] When ΔD exceeds 0.6, the pressure measuring material of the present invention can be a pressure measuring material having a more excellent reproduction of the concentration and concentration level that can be visually recognized or read when color is developed under pressure.

[0312] When the pressure measuring material having the pressure sensitive layer of the first embodiment develops color, the concentration difference (ΔD1) obtained by subtracting the concentration after color development at 1000 MPa from the concentration after color development at 2000 MPa is preferably 0.1 or more, more preferably 0.4 or more.

[0313] When ΔD1 is 0.1 or greater (preferably 0.4 or greater), the pressure measuring material of this embodiment can be a pressure measuring material having better reproduction of concentration and concentration level that can be visually recognized or read when developing color under a pressure of 500 MPa or greater.

[0314] When the pressure measuring material having the second embodiment of the pressure sensitive layer develops color, the concentration difference (ΔD2) obtained by subtracting the concentration after coloring under a pressure of 100 MPa from the concentration after coloring under a pressure of 500 MPa is preferably 0.1 or more, more preferably 0.4 or more.

[0315] When ΔD2 is 0.1 or greater (preferably 0.4 or greater), the pressure measuring material of this embodiment can be a pressure measuring material having better reproduction of concentration and concentration level that can be visually recognized or read when developing color under a pressure of 100 MPa to 500 MPa.

[0316] The color density is a value measured using a reflection densitometer (for example, RD-19I manufactured by GretagMacbeth LLC).

[0317] Furthermore, the pressure measuring material of the present invention preferably exhibits a property in which the color density increases with increasing pressure, ie, color gradation, when a pressure of 100 MPa to 10,000 MPa (more preferably 100 MPa to 3,000 MPa) is applied.

[0318] In the pressure measuring material of the present invention, the preferred gradation of color development is a property in which the color development density increases linearly with increasing pressure (that is, the pressure is proportional to the color development density).

[0319] The pressure measuring material of the present invention can be configured to measure pressures within the above-mentioned range, depending on the intended use. For example, one embodiment of the pressure measuring material of the present invention can be used for measuring pressures in a range exceeding 1000 MPa (e.g., 1000 MPa to 3000 MPa, preferably 1000 MPa to 2000 MPa). Furthermore, another embodiment of the pressure measuring material of the present invention can be used for measuring pressures in a range exceeding 1000 MPa (e.g., 100 MPa to 500 MPa).

[0320] The application of the pressure measuring material of the present invention includes the following application examples in various fields, but is not limited thereto.

[0321] Examples include the manufacture of vehicles such as automobiles or aircraft (for example, confirmation of pressure distribution during the molding of various components, car bodies, etc., or assembly of components), construction (for example, confirmation of pressure distribution during assembly of building materials), manufacture of electronic products (for example, confirmation of pressure distribution during curved surface processing (lamination of curved displays, etc.)), transportation (for example, confirmation of impact force applied to goods during transportation), metal processing (for example, confirmation of mold contact in the manufacture of various metal products), molding of resin products (for example, confirmation of mold contact in the molding of resin products), molding of pharmaceuticals (for example, confirmation of pressure distribution during tablet compression), furniture (for example, confirmation of pressure distribution on furniture surfaces (seats of chairs and sofas, etc.), stationery (for example, confirmation of gripping force applied to writing tools, etc.), and sporting goods (for example, confirmation of impact force applied to objects made of elastic materials (balls, etc.).

[0322] Example

[0323] The present invention will be described in more detail below by way of examples. The present invention is not limited to the following examples unless otherwise specified. In addition, "%" and "parts" are by mass.

[0324] (Example 1)

[0325] <Preparation of Microcapsule Liquid (A) Containing Electron Donating Dye Precursor>

[0326] 10 parts of the following compound (A) as an electron-donating dye precursor was dissolved in 53 parts of linear alkylbenzene (Olefin Grade L, JxEnergy Co., Ltd., boiling point 130° C. or higher) to obtain a solution A.

[0327] Next, 0.4 parts of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (ADEKA CORPORATION, ADEKA POLYETHER EDP-300) dissolved in 14 parts of synthetic isoparaffin (Idemitsu Kosan Co., Ltd., IP SOLVENT 1620, boiling point 130°C or higher) and 1.2 parts of ethyl acetate was added to the stirred solution A to obtain solution B.

[0328] Furthermore, 18 parts of a trimethylolpropane adduct of tolylene diisocyanate (DICCorporation, Bernock D-750) dissolved in 3 parts of ethyl acetate was added to the stirred solution B to obtain a solution C.

[0329] The above solution C was then added to a solution of 8 parts of polyvinyl alcohol (PVA-205, KURARAY CO., LTD., number average molecular weight 25,000, dispersant) dissolved in 110 parts of water for emulsification and dispersion. 340 parts of water were added to the emulsified solution, and the mixture was heated to 70°C while stirring for 1 hour, then cooled.

[0330] Water was further added to the cooled liquid to adjust the concentration, thereby obtaining a microcapsule liquid (A) containing an electron-donating dye precursor having a solid content concentration of 25%.

[0331] [Chemical Formula 1]

[0332]

[0333] The volume-based median diameter (D50) of the obtained microcapsules was 11 μm.

[0334] The volume-based median diameter was measured by Microtrac MT3300EXII (manufactured by Nikkiso Co., Ltd.).

[0335] <Preparation of Pressure Measurement Sheet (A)>

[0336] To 20 parts of the microcapsule liquid (A) obtained above were mixed 11 parts of a 40% dispersion of 3,5-bis(α-methylbenzyl) zinc salicylate as an electron-accepting compound serving as a color developer and 20 parts of a 20% aqueous solution of polyvinyl alcohol (PVA-105, KURARAY CO., LTD., number average molecular weight 22,000) as a specific polymer compound forming a polymer matrix to obtain a pressure-sensitive layer-forming composition (A).

[0337] The obtained pressure-sensitive layer-forming composition (A) was coated on a 75 μm-thick PET substrate (A4300: manufactured by Toyobo Co., Ltd.) using a rod coater in such a manner that the film thickness after drying becomes 15 μm, and dried at 80°C to obtain a pressure measuring sheet (A) (pressure measuring material) having a pressure-sensitive layer on the PET substrate.

[0338] Using a desktop microscope, "Miniscope TM3030 Plus" (manufactured by Hitachi High-Technologies Corporation), vertically cut sections of the pressure-measuring sheet (A) were observed at 10 arbitrary locations. The thickness of the pressure-measuring sheet (A) and the thickness of the PET substrate were measured. The difference between the calculated thickness of the pressure-measuring sheet (A) and the thickness of the PET substrate was arithmetic averaged to determine the thickness (film thickness) of the pressure-sensitive layer. The thickness (film thickness) of the pressure-sensitive layer was confirmed to be 15 μm.

[0339] The ratio of the thickness t of the pressure-sensitive layer to the particle diameter d of the microcapsules (t / d) was 1.36.

[0340] The Martens hardness of polyvinyl alcohol (PVA-105, KURARAY CO., LTD.) forming a polymer matrix was measured using a "Micro Hardness Tester HM2000" manufactured by FISCHER INSTRUMENTS KK. In the measurement, a diamond indenter (Berkovich indenter) was used in a laboratory environment at 23°C and 50% RH. A load ranging from 0 mN to the maximum test load was first applied for 10 seconds. The load was then maintained at the maximum test load for 5 seconds. Finally, the load was unloaded from the maximum test load to 0 mN for 10 seconds. The Martens hardness (N / mm) was calculated as the maximum test load divided by the indenter surface area at the maximum indentation depth. 2 ).

[0341] The Martens hardness of a 5 μm thick polymer matrix (PVA105) film formed on a glass substrate measured at a maximum test load with a maximum indentation depth of 0.5 μm was 165 N / mm. 2 .

[0342] <Hair Color Evaluation A>

[0343] The pressure-measuring sheet (A) of Example 1 obtained above was cut into four samples of 9 cm to 11 cm in size.

[0344] Each sample was pressed at any pressure shown in the pressure column of Table 1 below to confirm that the sample developed color due to the pressurization. The pressurization was performed using a press machine (DSF-C1-A, manufactured by AIDA ENGINEERING, LTD.).

[0345] The color density of the colored sample was measured using a spectrodensitometer (X-Rite 504 manufactured by X-Rite, Inc.). The measurement results are shown in the color density column of Table 1.

[0346] and, Figure 1 The relationship between pressure and color density is shown in the graph.

[0347] [Table 1]

[0348]

[0349] As shown in Table 1 and Figure 1 As shown, it was confirmed that the pressure-measuring sheet of Example 1 can achieve color development with excellent gradation in a high-pressure region exceeding 1000 MPa.

[0350] (Example 2)

[0351] A pressure measuring sheet (pressure measuring material) of Example 2 was prepared in the same manner as in Example 1 except that a portion of PVA-105 in the preparation of the pressure measuring sheet (A) was replaced with a polyol polyalkylene alkyl ether surfactant (Noigen LP-90, manufactured by DKS Co., Ltd.).

[0352] (Examples 3 to 8)

[0353] Except that the composition of each material was changed as shown in Table 2, the same procedure as in Example 2 was carried out to produce pressure measuring pieces of Examples 3 to 8.

[0354] Separately, a microcapsule liquid (B) was prepared as follows.

[0355] <Preparation of Microcapsule Liquid (B) Containing Electron Donating Dye Precursor>

[0356] In 70 parts of Hisol SAS-296 (oil component (solvent) manufactured by Nippon Oil Corporation; a mixture of 1-phenyl-1-xylylethane and 1-phenyl-1-ethylphenylethane) were dissolved 6 parts of 3',6'-bis(diethylamino)-2-(4-nitrophenyl)spiro[isoindol-1,9'-xanthene]-3-one (manufactured by HODOGAYA CHEMICAL CO., LTD., Pink-DCF) and 8 parts of 6'-(diethylamino)-1',3'-dimethylfluoran (manufactured by HODOGAYA CHEMICAL CO., LTD., Orange-DCF), which are electron-donating dye precursors, to obtain solution A2. Next, 0.7 parts of N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (ADEKA CORPORATION, ADEKA POLYETHEREDP-300) dissolved in 19 parts of synthetic isoparaffin (Idemitsu Kosan Co., Ltd., IP SOLVENT 1620) and 2.5 parts of methyl ethyl ketone were added to the stirred solution A2 to obtain solution B2. Furthermore, 77 parts of a trimethylolpropane adduct of toluene diisocyanate (DIC Corporation, Bernock D-750, containing 25% ethyl acetate) dissolved in 6 parts of ethyl acetate were added to the stirred solution B2 to obtain solution C2. Furthermore, this solution C2 was added to a solution of 10 parts of polyvinyl alcohol (KL-318, KURARAY CO., LTD.) dissolved in 140 parts of water to perform emulsification and dispersion. 200 parts of water was added to the emulsified and dispersed emulsion, and the mixture was heated to 70°C while stirring for 1 hour, followed by cooling. Water was added to adjust the concentration to prepare a microcapsule solution (B) containing an electron-donating dye precursor with a solids concentration of 20% by mass. The median particle size of the microcapsules was 8 μm.

[0357] (Comparative Example 1)

[0358] According to Example 1 of Japanese Patent Application Laid-Open No. 2009-019949, a two-sheet pressure measurement sheet consisting of an electron-donating colorless dye sheet and a developer sheet was produced.

[0359] [evaluate]

[0360] The “void content measurement” was performed on the pressure-sensitive layer of each pressure-measuring sheet of Examples 1 to 8.

[0361] Furthermore, the pressure-measuring sheets of Examples 2 to 8 and Comparative Example 1 were subjected to the following evaluations of “concentration level evaluation A” and “color development evaluation B”.

[0362] [Measurement of Void Amount]

[0363] The pressure measurement sheets (PET films with pressure-sensitive layers) from Examples 1 to 8 were cut into 10 cm x 10 cm pieces, and their mass (m1) was measured. Next, diethylene glycol was applied to the surface with the pressure-sensitive layer and allowed to penetrate. Any remaining diethylene glycol was wiped off, and the mass (m2) was measured. The void volume was calculated using the following formula: X = m2 - m1. The density of diethylene glycol is 1.118.

[0364] Void volume (m1 / m2) = 100 × X ÷ 1.118

[0365] The void volume of each pressure measurement sheet obtained in Examples 1 to 8 was 1 mL / m 2 the following.

[0366] [Concentration level evaluation A (1000MPa~2000MPa)]

[0367] The pressure measurement sheets of Examples 1 to 8 and Comparative Example 1 were measured for color density at 1000 MPa and color density at 2000 MPa, and the difference ΔD1 obtained by subtracting the color density at 1000 MPa from the color density at 2000 MPa was determined. Evaluation was performed according to the following evaluation criteria.

[0368] The pressurization method and measuring apparatus are the same as those in the color development evaluation A described above.

[0369] In addition, "A" and "B" are the ranges that are acceptable for practical use, and "A" is the most excellent. The results are shown in Table 2.

[0370] <Evaluation Criteria>

[0371] "A": ΔD1 is 0.4 or more.

[0372] “B”: ΔD1 is 0.1 or more and less than 0.4.

[0373] "C": ΔD1 is less than 0.1.

[0374] [Hair color evaluation B]

[0375] The pressure measurement sheets of Examples 1 to 8 and Comparative Example 1 were evaluated according to the following evaluation criteria based on the measurement results of the color development density at 1000 MPa obtained in the above-mentioned concentration level evaluation A. The results are shown in Table 2.

[0376] <Evaluation Criteria>

[0377] "A": The color density is 0.5 or more.

[0378] "B": The hair color concentration is less than 0.5.

[0379]

[0380] In Table 2, T represents the thickness of the layer obtained by subtracting the thickness of the substrate from the thickness of the pressure measuring material, T / p1 represents the ratio of the thickness T to the inner diameter p1 of the microcapsule, T / d1 represents the ratio of the thickness T to the particle size d1 (median particle size) of the microcapsule, and Ra represents the arithmetic mean roughness of the outermost surface (pressure-sensitive layer surface) on the side opposite to the substrate, all of which are values ​​obtained by the above method.

[0381] In Table 2, “-” indicates that the corresponding component was not contained or the corresponding item was not measured.

[0382] (Example 9)

[0383] -Preparation of color-forming layer composition-

[0384] To 100 parts of activated clay as an electron-accepting compound: Silton F-242 (MIZUSAWA INDUSTRIAL CHEMICALS, LTD.), and 100 parts of amorphous silica (MIZUSAWA INDUSTRIAL CHEMICALS, LTD., Mizukasil P-78A, inorganic particles that are not electron-accepting compounds) were added 10 parts of a 10% by mass sodium hydroxide aqueous solution, 750 parts of water, and 1 part of sodium hexametaphosphate (Nippon Chemical Industrial Co., LTD.), and the mixture was dispersed using a homogenizer. In addition, 140 parts of a modified acrylic acid ester copolymer (Zeon Corporation, Nipol LX814, solid content concentration 47%, a specific polymer compound), 28 parts of an anionic olefin resin (Arakawa Chemical Industries, Ltd., pymeron 482, solid content concentration 25%, a specific polymer compound), 5 parts of a 15% aqueous solution of a linear alkylbenzenesulfonic acid amine salt (DKS Co. Ltd., Neugen T), 35 parts of a 1% aqueous solution of polyoxyethylene polyoxypropylene lauryl ether (DKS Co. Ltd., Noigen LP-70), and 35 parts of a 1% aqueous solution of sodium-bis(3,3,4,4,5,5,6,6,6-nonafluorohexyl)-2-sulfonate (FUJIFILM Corporation, W-AHE) were mixed to prepare a color-forming layer composition containing an electron-accepting compound.

[0385] -Preparation of Color-Forming Layer Composition-

[0386] To 70 parts of the 20% solution (B) of the electron-donating dye precursor-containing microcapsules obtained above were further mixed 0.8 parts of an anionic olefin resin (Arakawa Chemical Industries, Ltd., polymeron 482, 25% solid content concentration, a specific polymer compound), 3.1 parts of a polymer (Rohm and Haas Company, OROTAN 165A, 21% solid content concentration, a specific polymer compound), 0.5 parts of a 15% aqueous solution of a linear alkylbenzenesulfonic acid amine salt (DKS Co., Ltd., Neugen T), 5 parts of a 1% aqueous solution of polyoxyethylene polyoxypropylene lauryl ether (DKS Co., Ltd., Noigen LP-70), and 5 parts of a 1% aqueous solution of sodium bis(3,3,4,4,5,5,6,6,6-nonafluorohexyl)-2-sulfonate (FUJIFILM Corporation, W-AHE) to prepare a coloring layer-forming composition.

[0387] -Production of materials for pressure measurement-

[0388] The color-developing layer-forming composition obtained above was applied to a surface of the substrate by a bar coater at a solid content of 20 g / m 2 The color-developing layer was formed by coating on a polyethylene terephthalate (PET) film (A4300: manufactured by Toyobo Co., Ltd.) having a thickness of 75 μm. Next, a solid content coating amount of 3.5 g / m was applied by a bar coater on the applied color-developing layer. 2 The color-forming layer composition is applied to form a color-forming agent layer.

[0389] In this manner, a single-sheet pressure measuring material was prepared, which had a pressure-sensitive layer formed by laminating two layers, a color developer layer and a color former layer, in this order on a PET film as a base material.

[0390] (Examples 10 to 14)

[0391] A pressure measuring piece was produced in the same manner as in Example 9 except that the composition of each material was changed as shown in Table 3.

[0392] (Comparative Example 2)

[0393] The same two-piece pressure-measuring sheet as that used in Comparative Example 1 was used.

[0394] [evaluate]

[0395] The “void content measurement” was performed on each of the pressure-measuring sheets of Examples 9 to 14.

[0396] Furthermore, the pressure-measuring sheets of Examples 9 to 14 and Comparative Example 2 were subjected to the following evaluations of "density level evaluation B" and "color development evaluation C."

[0397] [Measurement of Void Amount]

[0398] The void content of each pressure-measuring sheet of Examples 9 to 14 was measured in the same manner as in the pressure-measuring sheets of Examples 1 to 8 described above.

[0399] The void volume of each pressure measurement sheet obtained in Examples 9 to 14 was all within 5 mL / m 2 ~20mL / m 2 within the range.

[0400] [Concentration level evaluation B (100MPa~500MPa)]

[0401] The color density at 100 MPa and the color density at 500 MPa were measured for the pressure measurement sheets of Examples 9 to 14 and Comparative Example 2. The difference ΔD2, obtained by subtracting the color density at 100 MPa from the color density at 500 MPa, was determined and evaluated according to the following evaluation criteria.

[0402] The pressurization method and measuring apparatus are the same as those in the color development evaluation A described above.

[0403] In addition, "A" and "B" are the ranges that are acceptable for practical use, and "A" is the most excellent. The results are shown in Table 3.

[0404] <Evaluation Criteria>

[0405] "A": ΔD2 is 0.4 or more.

[0406] “B”: ΔD2 is 0.1 or more and less than 0.4.

[0407] "C": ΔD2 is less than 0.1.

[0408] [Hair color evaluation C]

[0409] The color density at 300 MPa was measured for each pressure measurement sheet of Examples 9 to 14 and Comparative Example 2. The pressurization method and measurement apparatus were the same as those in the color development evaluation A described above.

[0410] Based on the obtained measurement results, evaluation was performed according to the following evaluation criteria. The results are shown in Table 3.

[0411] <Evaluation Criteria>

[0412] "A": The color density is 0.5 or more.

[0413] "B": The hair color concentration is less than 0.5.

[0414]

[0415] In Table 3, T represents the thickness of the layer obtained by subtracting the thickness of the substrate from the thickness of the pressure measuring material, T / p2 represents the ratio of the thickness T to the inner diameter p2 of the microcapsule, T / d2 represents the ratio of the thickness T to the particle size d2 (average particle size) of the microcapsule, and Ra represents the arithmetic average roughness of the outermost surface (pressure-sensitive layer surface) on the side opposite to the substrate, all of which are values ​​obtained by the above method.

[0416] In Table 3, “-” indicates that the corresponding component was not contained or the corresponding item was not measured.

[0417] Explanation of symbols

[0418] 10, 20 - Pressure measurement material, 12, 22 - Substrate, 14, 24 - Pressure-sensitive layer, 24a - Color-forming layer, 24b - Color-developing layer, 15, 25 - Electron-accepting compound, 16, 26 - Polymer matrix, 18, 28 - Microcapsule, 18a, 28a - Capsule wall, 18b, 28b - Microcapsule contents (core material).

[0419] The disclosure of Japanese Patent Application No. 2019-006244 filed on January 17, 2019 is incorporated herein by reference in its entirety.

[0420] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A pressure measuring material comprising a substrate and a pressure-sensitive layer. The pressure-sensitive layer contains: a polymer matrix containing a polymer compound with a molecular weight of 1000 or more; a microcapsule containing an electron-donating dye precursor and a solvent; and an electron-accepting compound. The microcapsules and the electron-accepting compound are contained in the polymer matrix, The void volume of the pressure measuring material is 5 mL / m 2 the following, The arithmetic mean roughness Ra of the outermost surface on the side opposite to the substrate is 1.1 μm or less, The concentration difference ΔD1 obtained by subtracting the concentration after color development under a pressure of 1000 MPa from the concentration after color development under a pressure of 2000 MPa is 0.1 or more. The pressure measuring material according to claim 1 , which is in a sheet form.

3. The pressure measuring material according to claim 1, wherein The electron-accepting compound contains a metal salt of salicylic acid.

4. The pressure measuring material according to claim 1, wherein The content of the microcapsules is 10 volume % to 80 volume % relative to the pressure-sensitive layer.

5. A pressure measuring material comprising a substrate and a pressure-sensitive layer. The pressure-sensitive layer contains: a polymer matrix containing a polymer compound with a molecular weight of 1000 or more; a microcapsule containing an electron-donating dye precursor and a solvent; and an electron-accepting compound. The pressure-sensitive layer comprises: a color-developing layer comprising the electron-accepting compound and the polymer matrix; and a color-producing layer comprising the microcapsules. The pressure measuring material comprises the substrate, the color development layer, and the color developing layer, wherein the thickness of the color developing layer is 1 / 3 or less of the thickness of the color development layer. The arithmetic mean roughness Ra of the outermost surface on the side opposite to the substrate is 1.5 μm to 10.0 μm.

6. The pressure measuring material according to claim 5, wherein The arithmetic mean roughness Ra of the outermost surface on the side opposite to the substrate is 2.0 μm to 10.0 μm. The pressure measuring material according to claim 5 , which is in a sheet form.

8. The pressure measuring material according to claim 5, wherein The electron-accepting compound contains acidic clay or activated clay.

9. The pressure measuring material according to claim 8, wherein The pressure-sensitive layer includes inorganic particles other than the electron-accepting compound.

10. The pressure measuring material according to claim 5, wherein the void volume is 5 mL / m 2 ~20mL / m 2 .

11. The pressure measuring material according to claim 5, wherein The concentration difference ΔD2 obtained by subtracting the concentration after color development under a pressure of 100 MPa from the concentration after color development under a pressure of 500 MPa is 0.1 or more.

12. The pressure measuring material according to any one of claims 1 to 11, wherein The ratio T / p of the thickness T of the layer obtained by subtracting the thickness of the substrate from the thickness of the pressure measuring material to the inner diameter p of the microcapsule is 1.2 or more.

13. The pressure measuring material according to claim 12, wherein The ratio T / p of the thickness T of the layer obtained by subtracting the thickness of the substrate from the thickness of the pressure measuring material to the inner diameter p of the microcapsule is 1.2 to 5.

0.

14. The pressure measuring material according to any one of claims 1 to 11, wherein The polymer compound having a molecular weight of 1000 or greater is contained in an amount of 10% by mass or greater based on the total mass of the pressure-sensitive layer.

15. The pressure measuring material according to any one of claims 1 to 11, wherein The substrate is a polyethylene terephthalate substrate or a polyethylene naphthalate substrate.

16. The pressure measuring material according to any one of claims 1 to 11, wherein An easy-adhesion layer is provided between the substrate and the pressure-sensitive layer.

17. The pressure measuring material according to any one of claims 1 to 11, wherein The wall material of the microcapsule contains at least one selected from polyurethane urea and polyurethane.

18. A method for producing a pressure measuring material, the method for producing a pressure measuring material according to any one of claims 1 to 4 and claims 12 to 17, comprising: a step of placing a pressure-sensitive layer-forming composition on a substrate, The pressure-sensitive layer forming composition comprises: a polymer matrix containing a polymer compound with a molecular weight of 1000 or more; microcapsules containing an electron-donating dye precursor and a solvent; and an electron-accepting compound.

19. A method for producing a pressure-measuring material, the method according to any one of claims 5 to 17, comprising: A step of obtaining a color-forming layer composition, wherein the color-forming layer composition comprises microcapsules and a solvent, wherein the microcapsules contain an electron-donating dye precursor and the solvent; a step of obtaining a color-development layer-forming composition comprising an electron-accepting compound and a polymer compound having a molecular weight of 1000 or more; The process of disposing the color-developing layer-forming composition on a substrate to form a color-developing layer; and The step of disposing the color-forming layer-forming composition on the color-developing layer to form a color-forming layer.

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