XNUMX. XNUMX.Introduction

　Writing instruments that use thermochromic materials have become commonplace in the world over the past few years.During my research, I occasionally came across inventions that made good use of the characteristics of thermochromic materials, which I found very interesting.Thermochromic materials are used in a variety of fields, but this time, we conducted a trend search to find out what kind of application inventions exist, especially in the field of office supplies.

XNUMX.Characteristics of thermochromic materials

　There are a wide variety of types of thermochromic materials.Among them, the object of this search is a coloring material that has the characteristic of maintaining the color until it reaches a certain temperature once it has changed color.

　Here, we will briefly explain the thermochromic materials that we deal with this time.A typical diagram showing the relationship between color change and temperature is shown below.This figure shows the publication number of the published patent publicationJP 2016-168840I borrowed Figure 2 from

　This is a curve that plots changes in color density due to temperature changes.In this way, the thermochromic material targeted this time has a cycle between certain temperatures.Here, t1 is the complete color development temperature, t2 is the color development start temperature, t3 is the color change start temperature, and t4 is the complete color change temperature. The color developed at a temperature below t1 maintains a constant color development state until it reaches the temperature of t3 even if the temperature rises.Similarly, the color that has been bleached at a temperature of t4 or higher will maintain a constant bleached state until it reaches the temperature of t2 even if the temperature drops.A major feature of this reversible thermochromic material is that it maintains a colored state or a decolored state until it reaches a certain temperature even if the temperature changes.We conducted a trend search on applications that utilize this feature.

XNUMX.range of office supplies

　In this search, the range of office supplies included general so-called stationery, as well as items related to advertisements and displays.In addition, writing instruments were excluded from the target.This is because, in the field of writing instruments, many manufacturers have released various products, so we expected that the amount of data to be handled would be enormous, and we judged that it would be well known in the world.

XNUMX.Concept of search formula

　Since the subject of this search is the use of thermochromic materials scattered over a wide range of office supplies, it is unlikely that there will be a patent classification in line with this theme.Therefore, as heat discoloration (viewpoint 1) and office supplies (viewpoint 2), we widely adopted the patent classification that represents the office supplies (viewpoint 2) itself, and added a keyword representing heat discoloration (viewpoint 1) to 600 I made a population of about.

This is an example of the patent classification adopted.

G09F 3/02F
This classification is FI of "label with characteristic printing layer".This is a classification that includes the viewpoint of labels, which are office supplies (viewpoint 2), and the viewpoint that the printing layer has characteristics.Although it does not refer to thermal discoloration (viewpoint 1) itself, it seems to include labels in which the printed layer among the layers that make up the label is discolored by heat. I thought.

B42D 5/04Z
In the calendar book classification of "B42D 5/04", it is an FI with a separate volume identification symbol "Z" that means "other things".I don't know what kind of patents are included without looking at them, but there is a possibility that patents that don't have an appropriate patent classification are classified here, so they are not suitable for a search like this time. I adopted it because I thought it was.

　In addition, if we adopt a patent classification related to ink that changes color due to heat (viewpoint 1) and search the population with keywords representing office supplies (viewpoint 2), we can reduce the number of omissions considerably. This population is noisy and likely to be large, so we decided not to adopt it in this short report.

XNUMX. search result

XNUMX Number of applications by application

　The chart below shows the number of applications by application.

　From this figure, we can see that applications using thermochromic materials can be broadly divided into visual effects, reuse, security, temperature history, and other uses.

XNUMX Examples of usage

(A) visual effect
　From the viewpoint of using color change, many applications were filed using designs with rich expressions.In addition to designs that consist only of color schemes, the most popular items in this search are those that enjoy the design itself, such as message cards and paintings that incorporate the unexpectedness and richness of design because the colors change depending on the temperature. .Furthermore, media printed with thermochromic ink can be easily changed in color by rubbing it with a friction material such as rubber. It is used.
　In addition, there were also applications for methods of using markings that were used as marks in the manufacturing process to be erased from the product, and that only the design was indicated purely.

(B) Reuse
　I have seen several inventions of paper and display tools that make use of the fact that printing is easy by using ink for printing letters and pictures, and that the printed matter can be easily erased by giving a temperature change. .It can be seen that it is expected to be an invention that has the potential to realize economic and resource saving.

(C) Security
　Several inventions have been seen that make it possible to realize high security that requires concealment and secrecy, as printed matter can easily disappear or appear.For example, the technology can be used to confirm the authenticity of securities, etc., by exposing letters and patterns that cannot be seen in normal use to a certain temperature so that they appear only for a predetermined period of time.
　In addition, since it is difficult to reproduce without going through the same process with abundant designs and the same color materials, it is possible to construct printed matter with extremely high anti-counterfeiting effects, which contributes to security. It seems to be.

(D) Temperature history
　Printed with thermochromic ink has the characteristic of maintaining the color until it reaches a certain temperature. There were some inventions that made good use of the fact that it is not necessary to prepare a thermometer or the like for confirmation.In addition, since indicator labels can be produced simply by printing on paper or sheets, this technology can be applied to food packages and wrapping paper without the need for large-scale changes in the manufacturing process. You can catch a glimpse of something.

XNUMX Examples of extracted applications

　Here are some of the extracted applications.
　* Some contents have been revised and added from the original publication.

Visual Effects > Calendar (Convenience)

[Publication number] JP 2021-003870
[Applicant] Toppan Printing Co., Ltd.
[Application date] June 2019.6.27, XNUMX
[Title of Invention] Calendar information display medium

You can easily customize the calendar display according to your schedule, such as removing the color of the date number of the day you completed the schedule with a friction body.

JP 2021-003870 (J-PlatPat link)

Visual effects> Message cards, paintings (unexpectedness, design)

[Publication number] JP 2001-353950
[Applicant] Sakura Crepas Co., Ltd.
[Application date] June 2001.3.30, XNUMX
[Title of invention] Printed matter

Expresses a visual effect that is full of changes.
When the temperature is low, the thermochromic ink becomes colored and the snow scene of the background XNUMX appears.

JP 2001-353950 (J-PlatPat link)

Visual Effects > Landmarks (Workability)

[Public number] Jitsukaihei 05-017674
[Applicant] Pilot Ink Co., Ltd.
[Application date] June 1991.8.12, XNUMX
[Name of invention] Cloth for notation

It is visible when written, but becomes invisible after the piece of cloth is ironed onto the surface of the article.

Actual Kaihei 05-017674 (J-PlatPat link)

Reuse>Painting set

[Publication number] JP-A-07-241389
[Applicant] Pilot Ink Co., Ltd.
[Application date] June 1994.3.7, XNUMX
[Title of Invention] Thermochromic Imaging Article

Color is developed by tracing the planar thermochromic body XNUMX with the cold-heat color-changing tool XNUMX .

JP07-241389 (J-PlatPat link)

Security>Securities (anti-counterfeiting)

[Publication number] JP 2004-074597
[Applicant] Toppan Forms Co., Ltd.
[Application date] June 2002.8.19, XNUMX
[Title of Invention] Anti-counterfeit sheet

ID information XNUMX is printed on the base layer XNUMX .
The members constituting the ID information XNUMX are the same color as the base layer XNUMX in the normal state, or the same color as the sheet surface in the region of the authenticity determination section XNUMXa when the base layer XNUMX is transparent in the normal state.
Normally, the ID is invisible, but it becomes visible at a certain temperature.

JP 2004-074597 (J-PlatPat link)

Storage temperature history > Indicator label

[Publication number] JP 2001-034172
[Applicant] Toshiba Tec Corporation
[Application date] June 1999.7.16, XNUMX
[Title of Invention] Temperature control member and temperature control label

As long as it is stored at a low temperature, the words "good condition" are visible.

JP 2001-034172 (J-PlatPat link)

Heating time display> Labels, packaging containers

[Publication number] JP-A-07-244460
[Applicant] Sealex Co., Ltd.
[Application date] June 1994.3.7, XNUMX
[Title of Invention] Heating time display device and label or packaging container equipped with the same

A label comprising a first printed layer (11) formed by foaming ink and a second printed layer (12) formed by thermochromic ink.
When the temperature of the foamed ink reaches a certain level or higher, the color of the thermochromic ink formed on its surface changes.

JP07-244460 (J-PlatPat link)

XNUMX Number of applications by company

　The chart below shows the number of applications by company.

　As can be seen from this figure, it seems that, with the exception of companies such as Pilot Ink Co., Ltd. and Pilot Corporation, the development of applications using thermochromic materials is not being actively carried out at present.These two companies have a relationship of simultaneously developing ink and applications within the group, and they are actively working on these technical fields, such as selling writing instruments that use thermochromic ink ahead of others. understand.
　Given the nature of this search's focus on office supplies, it is also characteristic that there were many companies developing products for end users.

XNUMX Changes in the number of applications

　The chart below shows the number of applications in chronological order.

　As you can see from this chart, there doesn't seem to be any age group in which a particularly large number of applications were filed.As you can see from the search results of the number of applications by company introduced earlier, there is currently no ground for active development, but writing instruments have become a hit product and many companies are conducting research and development. In light of this, if one idea is accepted by the world, there is a hidden possibility that development in the field of that technology and peripheral technology will be actively carried out.

XNUMX.Summary

　In this search, we were able to confirm a wide variety of applications, probably because the product can be developed on a relatively small scale because the target was the application as office supplies using the thermochromic material.In addition, for the same reason, there was no noticeable trend in the number of filing companies and the number of applications.In addition, it can be expected that development in an environment that is complete within a single company is possible, suggesting that this is a field in which it is difficult to reach a scale that requires collaboration between companies for development.
　In future searchs, if we focus on technological fields that further use applications using thermochromic materials, we may be able to catch a glimpse of trends and corporate movements that were not seen in this search. yeah.

Research Division Seki