JPH0755606A - Pressure measuring sheet - Google Patents

Abstract

PURPOSE:To easily and quickly measure pressure or pressure distribution without using a measuring equipment by constituting a pressure measuring sheet by mixing plural kinds of microcapsules different in intensity and tone of coloring. CONSTITUTION:A microcapsule layer 13 is applied to the surface of a sheet base 12. The microcapsule layer 13 is formed by mixing a capsule 13Y of yellow, a capsule 13M of magenta, and a capsule 13C of cyanogen. When an external force is added, sealed coloring bodies 14Y, 14M, 14C flows to the outside of the capsules 13Y, 13M, 13C. Since the diameters of the capsules 13Y, 13M, 13C are minimized in the order of yellow, magenta, and cyanogen, their intensities are increased in this order. When an image receiving paper which is a general paper is put on the microcapsule layer 13 of such a pressure measuring sheet, and a pressure is added in a position to be measured, the coloring of the image formed on the image receiving paper is changed depending on the magnitude of the pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure measuring sheet capable of measuring pressure such as surface pressure and linear pressure and pressure distribution.

[0002]

2. Description of the Related Art Conventionally, pressure measuring sheets using microcapsules have been disclosed in Japanese Patent Publication Nos. 58-10693 and 59-1.
6654, JP-A-54-41177, JP-A-54-
No. 78186 and JP-A-55-103437. This pressure measurement sheet is one in which microcapsules containing a colorless color-forming material and a color-developing agent for developing the color-forming material are applied to the same sheet-shaped base material or separate sheet-shaped base materials. is there.

When this pressure measuring sheet is sandwiched between pressures or regions where pressure distribution is to be measured and pressure is applied, pressure is applied to the microcapsules. This pressure destroys the microcapsules and releases the color-forming material, or penetrates the outer wall of the microcapsule and releases the color-forming material. In this case, the higher the pressure is, the larger the amount of the color-developing substance released, that is, the amount of the color-developing substance that reacts with the color developer is increased.

Then, the pressure or the pressure distribution can be known from the shade of the color of the pressure measuring sheet.
According to this method, it is possible to measure the pressure of a portion where a measuring device capable of directly measuring the pressure cannot be installed, like the measurement of the pressure applied between the pair of rollers.

[0005]

However, since the conventional pressure measuring sheet as described above has a monochromatic color such as red, it is difficult for human eyes to compare the densities when the color density exceeds a certain level. Therefore, it was necessary to measure the color density by a density evaluator and convert it into a pressing force. Moreover, since the concentration evaluator is not a general measuring instrument, it is very expensive and cannot always be installed permanently at the measurement site, so that the pressure or pressure distribution can be measured quickly at the actual measurement site. could not.

The present invention has been made in order to solve the above-mentioned problems, and pressure and pressure distribution can be simply and quickly measured without using a measuring device such as a special concentration evaluator. The purpose is to provide a measurement sheet.

[0007]

In order to achieve this object, the pressure measuring sheet of the present invention comprises:
A microcapsule containing a color-forming body is coated, and the microcapsule to be coated is a mixture of two or more types of microcapsules having different strengths and different color tones of the color-forming body. It is composed by.

More specifically, a microcapsule A containing a first color-forming material and a microcapsule B containing a second color-forming material different from the first color-forming material are mixed to form a sheet-like base material. Microcapsule A that has been coated
Is designed to have a lower strength than the microcapsule B.

Regarding the strength of the microcapsules, it is already known that the smaller the diameter of the particles and the thicker the wall material, the higher the strength (Color Materials Association magazine Vol. 55, 1982).

Therefore, the above-mentioned microcapsule A
Is designed to be weaker in strength than the microcapsule B because the diameter thereof is larger than that of the microcapsule B or the wall material is thin.

[0011]

In the pressure measuring sheet of the present invention having the above-mentioned structure, when the measured pressure is relatively low, only the microcapsules A having weak strength are destroyed.
The color of the chromophore is obtained. Then, the higher the pressure is, the more the microcapsules B are destroyed.
It is possible to obtain a color mixture with the color developing material. That is, depending on the pressure,
Not only the color density but also the color tone of the color changes.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram schematically showing a cross section of a pressure measuring sheet 1 of the present invention, in which a surface of a sheet-like base material 12 made of PET (polyethylene terephthalate) or the like,
The microcapsule layer 13 is applied. The microcapsule layer 13 includes a yellow capsule 13Y, a magenta capsule 13M, and a cyan capsule 13C.
Depending on the location, certain capsules are mixed so that they are not ubiquitous. And the yellow capsule 13
Y has a diameter in the range of 15 μm to 25 μm, and the yellow color former 14Y is included therein. The magenta capsule 13M has a diameter of 10 μm to 15 μm.
It is in the range of m, and a magenta coloring material 14M
Is included. The cyan capsule 13C has a diameter in the range of 5 μm to 10 μm.
C is included.

In these microcapsules, a coloring material capable of forming at least a color image is usually enclosed by wall materials 15Y, 15M and 15C such as resin, but when an external force is applied, the coloring material 14Y, 14M,
14C can flow out of the microcapsule.

As such a color former, various known pigments or dyes can be used. Also,
The color developing material may be mixed with various oils in order to adjust the fluidity of the color developing material.

The microcapsules can be produced by the coacervation method disclosed in US Pat. Nos. 2,800,457, 280,458 and the like, and US Pat. No. 328.
7154, British Patent 990443, and Japanese Examined Patent Publication Nos. 38-19574, 42-446, 42-
The interfacial polymerization method disclosed in Japanese Patent No. 771.
No. 9168 and JP-A No. 51-9079, there are in-situ polymerization methods by polymerization of monomers.

In the present embodiment, although not limited to the above method, the strength of the microcapsules (the pressure required for the inclusions to flow out from the microcapsules) is adjusted by the difference in particle diameter. As described above, it is desirable that the yellow, magenta, and cyan capsules have the wall film formed of the same material.

Further, controlling the diameter of each color capsule as described above is known by adjusting the concentration of the emulsifier used when emulsifying the inclusion in water, the number of revolutions of the emulsifying device, the temperature, etc. It is possible by the technology of.

As the emulsifier, water-soluble anionic polymer, nonionic polymer, amphoteric polymer and the like are used. Examples of the anionic polymer emulsifier include natural gum arabic alginate, pectin, synthetic maleic anhydride-based polymers and copolymers, acrylic acid-based polymers and copolymers, vinylbenzenesulfonic acid-based polymers. And copolymers, and the nonionic polymer emulsifiers include polyvinyl alcohol, hydroxypropyl cellulose, methyl cellulose and the like. Examples of amphoteric polymer emulsifiers include gelatin.

2A to 2C show the relationship between the amount of released color of the yellow capsules, magenta capsules, and cyan capsules thus obtained and the pressure.

Since the diameter of the microcapsule decreases in the order of yellow, magenta, and cyan, the strength increases in this order. When an image receiving paper, which is a plain paper, is superposed on the microcapsule layer of such a pressure measuring sheet and pressure is applied at the measurement site, the color development of the image formed on the image receiving paper changes depending on the magnitude of the pressure.

For example, in FIG. 2, when the magnitude of the pressure applied to the microcapsule layer corresponds to (1), only a slight amount of the color-developing substance corresponding to Y1 is released from the yellow capsule, and magenta and The cyan chromophore is not released. Therefore, a light yellow image is formed on the image receiving paper.

Further, when the pressure is (2), the amount of yellow emission increases to Y2, so that the color of yellow becomes darker. In the case of (3), the emission amount of yellow is Y3 and Y
Although not significantly different from 2, since magenta is emitted in an amount corresponding to M3, the image becomes orange due to the subtractive color mixture of the yellow colorant of Y3 and the magenta colorant of M3. In the case of (4), the amounts of yellow and magenta corresponding to Y4 and M4, respectively, are obtained, and thus red color is obtained by subtractive color mixing by the yellow and magenta color formers.

Further, when the pressure is high (5), since the coloring material of the amount of cyan C5 is emitted in addition to the yellow Y5 and the magenta M5, the image becomes purple. In the case of (6), three colors, such as Y6, M6, and C6, are emitted in substantially the same amount, so the image becomes black due to the subtractive color mixture.

In this way, the hue of the image formed on the image receiving paper changes depending on the magnitude of the pressure applied to the microcapsule layer.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, the strength of the microcapsules may be controlled by the thickness of the wall material. Such microcapsules having different wall material thicknesses can be produced by the in-situ polymerization method among the above-mentioned capsule manufacturing methods.
It is obtained by forming a wall material made of a melamine formalin resin or a urea formalin resin. According to this method, the thicker the wall material is, the larger the amount of the prepolymer of melamine formalin or urea formalin, which is the raw material of the wall material, is used.

Further, the color-developing material used in the present invention is not a dye or pigment which is itself colored, but is a color-developing material which is not colored by itself but is colored by contact with other components. Is also good. Examples of such color formers include triarylmethane-based, diphenylmethane-based, xanthene-based, thiazine-based, and spiropyran-based compounds.

Since these color formers develop color by contacting with a so-called color developer, the color developer is applied to the pressure measuring sheet together with the capsule, or the color developer is applied to the image receiving paper for use. To be Examples of such a developer include a phenol compound, an organic acid or a metal salt thereof, an oxybenzoic acid ester, and acid clay.

[0030]

As is apparent from the above detailed description, according to the pressure measuring sheet of the present invention, once the relationship between the hue of color development and the pressure is measured, it is possible to use a human By the feeling of, you can know the approximate pressure. That is, the pressure or the pressure distribution can be simply and quickly measured without using a measuring device such as a special concentration evaluator.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a cross section of a cross section of a pressure measurement sheet of the present invention.

FIG. 2 is a diagram for explaining the operation of the pressure measuring sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure measurement sheet 12 Sheet-shaped base material 13 Microcapsule layer 14 Color body 15 Wall material

Claims (1)

[Claims] 1. A pressure measurement sheet comprising a sheet-like substrate coated with microcapsules containing a color-forming material, wherein the coated microcapsules have strength and color-developing properties. A pressure measuring sheet comprising a mixture of two or more types of microcapsules having different color tones.