JP5120921B2 - Thermoreversible recording medium, thermoreversible recording member, image processing apparatus and image processing method - Google Patents

Description

  The present invention reduces the curling of the medium even when repeated erasing / printing is performed, reduces the curling of the medium even in a low temperature environment or a high temperature environment, and repeatedly performs erasing / printing in each environment. Thermally reversible recording media that can generate a specified number of sheets in a printer stacker with minimal curling, excellent transportability in low to high temperature environments, low transport failures even when batch printing is performed. The present invention also relates to a thermoreversible recording member, an image processing apparatus, and an image processing method using the thermoreversible recording medium.

  In recent years, a reversible thermosensitive recording medium (hereinafter referred to as “thermo-reversible recording medium”, “recording medium”, or “rewritable medium”) that can perform temporary image formation and erase the image when it becomes unnecessary. ) Is attracting attention. A typical example is a developer such as an organic phosphate compound, aliphatic carboxylic acid compound or phenol compound having a long-chain aliphatic hydrocarbon group in the resin, and a color former such as a leuco dye. A thermoreversible recording medium that is dispersed is known (see Patent Documents 1 and 2).

  Many of such thermoreversible recording media have a PET film having a magnetic recording layer as a support, and are mainly used in the market as point cards. On the other hand, a thermoreversible recording layer is provided on a thin support, an adhesive layer is provided on the opposite side of the support, and it is used as a thermoreversible recording medium by laminating various substrates with heat and pressure. Many methods have been proposed (see, for example, Patent Documents 3 to 6).

  However, the above-mentioned base material is a card that is combined with an optical memory, a contact type IC, a non-contact type IC, and magnetic recording, and most of the base material is thick and has a limited size, and its use is limited. Therefore, it is unsuitable for large screens and various displays such as entrance / exit tickets, frozen food containers, industrial products, stickers for various chemical containers, logistics management applications, manufacturing process management applications, etc.

  Therefore, in order to use it for the above-mentioned purposes, a thermoreversible recording medium having a sheet size of A4 or A3 to a Kanban size larger than the card size is required. Here, the kanban size means a size larger than the card size (54 mm × 85 mm) and smaller than the A5 size, and the sheet size means a size larger than A5.

When the thermoreversible recording medium is used as a kanban or a sheet, the size becomes larger than that of a point card or a card of a thick base material, so that it is easy to be charged by contact of the thermoreversible recording mediums or a conveyance roller during printer conveyance. In addition, since the contact area increases, static electricity accumulated in the thermoreversible recording medium increases. As a result, the thermoreversible recording media stick to each other due to static electricity and are difficult to be transported by the printer, which causes a problem of double feeding.
In addition, the thermoreversible recording medium shrinks due to repeated printing and erasure due to heat, and curls occur.However, the curl degree increases and a paper feed failure occurs without entering the conveyance path of the image processing apparatus from the stacker. There is a problem that the curled medium is caught by a roller or the like in the conveyance path of the image processing apparatus and causes a conveyance failure.

Here, the curl is a curl in which the recording medium warps on the recording layer surface side by repeated use, a curl that warps the recording layer surface side by leaving the recording medium in each environment, or a curl that warps the opposite side to the recording layer surface. These curl fluctuations cause a problem that a predetermined number of sheets cannot be set on the stacker and a paper feed from the stacker to the image processing apparatus.
In addition, since these kanbans and sheets are suitably used in combination with RF-ID, durability that can withstand the use of many repeated erasure prints is required. For example, what has been sufficient in the past up to 100 times has been required more times.

  Thus, Patent Document 7 proposes a thermoreversible recording medium provided with a back layer using a needle-like conductive filler. However, there was no particular problem in the environment of 30 ° C to 35 ° C of 85 ° C, which was the initial use environment, but it was new because the use environment was diverse in applications such as logistics management and manufacturing process management. A problem occurred. That is, for product logistics management applications stored in a freezer, for example, a low temperature environment region lower than 5 ° C. may be used, and for product logistics management stored in a warehouse without general air conditioning, for example, a high temperature of 35 ° C. or higher. Some applications are used in the environmental field, and the usage environment has expanded from a low temperature environment to a high temperature environment. For this reason, there is a problem that a curl is greatly generated on the recording layer surface side in a low temperature environment outside the conventional assumed area, and the display content is difficult to see, or the curled part protrudes from a predetermined position, causing a problem in operation. occured. In addition, the erasing print in the low temperature environment region has a new problem that the predetermined amount cannot be accommodated by the printer stacker due to the curl, or a paper feed failure that cannot be transported from the stacker to the transport path due to the curl. .

On the other hand, in a high temperature environment that deviates from the conventional assumed area, a large amount of curling occurs on the back layer surface side, which makes it difficult to see the display content, or a problem that the curled part protrudes from a predetermined position. There are also problems such as defects and poor conveyance.
Further, in distribution management and manufacturing process management applications, there are many applications in which a large number of kanbans and sheets are issued in a lump in a day, so that a plurality of thermoreversible recording media are issued in an overlapping manner. For example, if one kanban or sheet is issued for a product to be produced per day, it will be issued according to the amount. If the amount is 100, it will be 100, if 500, 500 One sheet of thermoreversible recording medium is issued each time.
For this reason, when the curl of the medium used increases, the protrusions of the curled parts are stacked and the specified number of recording media does not fit in the printer stacker. The problem that it cannot be transported occurs.

  Furthermore, since it is a thermoreversible recording medium, when it is used repeatedly, a thermal history is applied during erasing and printing, respectively, but the heat history adds a lot of heat to the surface side of the recording medium. . For example, in the thermoreversible recording medium disclosed in Patent Document 7, there was no problem due to curling particularly in repeated use at a level of 100 times. The degree increases, and this causes a problem that a predetermined number of sheets does not enter the stacker and a problem that paper cannot be fed from the stacker to the image processing apparatus.

  Patent Document 8 has been proposed as a method for preventing curling. In this method, the peak temperatures of the viscoelastic logarithmic decay rates of the front and back recording layer surfaces and the anti-curl surface are defined and the front and back surfaces are equivalent. However, this method has a problem that double feeding occurs due to generation of static electricity in a room temperature environment or a low temperature and low humidity environment. In addition, when the number of repetitions is about 100, the curl is 20 mm or less. However, when the number of repetitions is more than that, the recording layer surface side resin receives the heat of erasing on the recording layer surface side and the history of heat during printing. There is a problem that the curl balance of the front and back is lost due to the shrinkage and the recording layer surface is largely curled. Further, in the low temperature environment region or the high temperature environment region, there is a problem that the curl balance is lost and the curl is caused on one surface.

On the other hand, Patent Document 9 has been proposed as a method for preventing curling and charging other than a thermoreversible recording medium. In this method, an anti-curl layer, an adhesion preventing layer, and an antistatic layer are provided on the side opposite to the heat-sensitive recording surface. However, since the physical strength due to repeated use is not taken into consideration, the second and subsequent uses do not have sufficient strength, and the repeated use causes peeling, and has the effect of preventing double feeding due to antistatics and transportability. There is a problem that the effect cannot be maintained.
Further, since the shrinkage on the recording layer surface side due to repeated thermal history is not considered, there is a problem that curling to the recording layer surface side occurs even if it can be used repeatedly. Furthermore, curling of the medium cannot be suppressed in a low temperature environment region or a high temperature environment region, and a problem that a predetermined number of sheets does not enter the stacker or a problem that paper cannot be fed from the stacker to the image processing apparatus occurs. That is, even if it is developed on a thermoreversible recording medium that is repeatedly used, all the problems cannot be solved simultaneously.

  Therefore, even if repeated erase printing is performed as described above, the curl of the medium is small, and the occurrence of curl of the medium is small even in a low temperature environment or a high temperature environment. There is still no provision of thermoreversible recording media and related technologies that can generate a specified number of sheets in a printer stacker with little occurrence, excellent transportability even in low to high temperature environments, and low occurrence of transport failures even in batch mass printing. The current situation is not.

JP-A-5-124360 Japanese Patent Laid-Open No. 6-210954 JP 2000-94866 A Japanese Patent Laid-Open No. 2000-251042 JP 2001-63228 A JP 2002-103654 A JP 2005-193564 A JP 2002-160453 A JP 2006-82309 A JP 2001-162936 A JP 55-154198 A JP-A-4-224996 JP-A-4-247985 JP-A-4-267190 JP-A-3-169590 JP-A-2-188293 JP-A-2-188294

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, even if repeated erasure printing is performed, the curl of the medium is small, the occurrence of curling of the medium is low even in a low temperature environment or a high temperature environment, and even if repeated erasing printing is performed in each environment, the occurrence of curl is small, A thermoreversible recording medium that is excellent in transportability even in a low temperature environment to a high temperature environment, has few transport failures even in batch mass printing, and can set a specified number of sheets in a printer stacker, and the thermoreversible recording medium An object is to provide a thermoreversible recording member, an image processing apparatus, and an image processing method.

Means for solving the problems are as follows. That is,
(1) A support, a heat-sensitive layer whose color tone reversibly changes depending on temperature on the support, and at least one protective layer provided on the heat-sensitive layer, the heat-sensitive layer of the support being An anti-curl layer composed of at least one layer is provided on the surface opposite to the provided surface, an antistatic layer is provided on the anti-curl layer, and the resin type constituting the heat-sensitive layer and the anti-curl layer, and the protection and a resin species constituting the layer and the antistatic layer, Ri same der each coating Tg of the heat-sensitive layer and the anti-curl layer is at 100 ° C. or higher, the coating Tg curl prevention layer of the heat-sensitive layer coating film Tg It is a thermoreversible recording medium characterized by being higher by 10 ° C.
(2) a heat-sensitive layer composed of two or more supports bonded so that the coated surface becomes the surface, and the color tone reversibly changes depending on the temperature on the coated surface of one of the supports; At least one protective layer is provided on the heat-sensitive layer, an anti-curl layer comprising at least one layer is provided on the coated surface of the other support, an anti-static layer is provided on the anti-curl layer, and the heat-sensitive layer the resin species constituting the anti-curl layer, and the protective layer and the resin species constituting the antistatic layer has a respectively identical der is, the coating Tg of the heat-sensitive layer and the anti-curl layer is 100 ° C. or higher, Carl The thermoreversible recording medium is characterized in that the coating layer Tg of the prevention layer is higher by 10 ° C. or more than the coating layer Tg of the thermosensitive layer .

(3) The thermoreversible recording medium according to (1) or (2), wherein the resin species constituting the thermosensitive layer and the anti-curl layer is a thermosetting resin.
(4) The thermoreversible recording medium according to (3), wherein the thermosetting resin is cured with an isocyanate curing agent.
( 5 ) The heat described in any one of (1) to ( 4 ) above, wherein the resin type constituting the protective layer and the antistatic layer is a thermosetting resin or an ultraviolet curable resin. It is a reversible recording medium.
( 6 ) The thermoreversible recording medium as described in any one of ( 1 ) to ( 5 ) above, wherein the antistatic layer contains an acicular conductive filler.
( 7 ) The thermoreversible as described in ( 6 ) above, wherein the long axis of the acicular conductive filler is 1 μm or more and 10 μm or less and the short axis is a size of 0.1 μm or more and 0.5 μm or less. It is a recording medium.
( 8 ) The thermoreversible recording medium according to ( 6 ) or ( 7 ), wherein the acicular conductive filler is obtained by surface-treating acicular crystals with a conductive agent.
( 9 ) The thermoreversible recording medium according to any one of ( 6) to ( 8 ), wherein the acicular conductive filler is titanium oxide coated with antimony-doped tin oxide.
( 10 ) The thermoreversible recording medium according to any one of (1) to ( 9 ) above, wherein the surface resistance value of the outermost layer on the surface of the antistatic layer is 1 × 10 ¹¹ Ω / □ or less. is there.
( 11 ) A thermoreversible recording member comprising an information storage unit and a reversible display unit, wherein the reversible display unit includes the thermoreversible recording medium according to any one of (1) to ( 10 ). is there.
( 12 ) The thermoreversible recording member according to ( 11 ), wherein the information storage unit and the reversible display unit are integrated.
( 13 ) The thermoreversible recording member according to ( 11 ) or ( 12 ), wherein the information recording unit is selected from a magnetic recording layer, a magnetic stripe, an IC memory, an optical memory, and an RF tag.
( 14 ) The thermoreversible recording member according to any one of ( 11 ) to ( 13) , which has a printable part.

( 15 ) Image forming means for heating a thermoreversible recording medium to form an image on the thermoreversible recording medium, and image erasing means for heating the thermoreversible recording medium to erase the image formed on the thermoreversible recording medium And the thermoreversible recording medium is the thermoreversible recording medium according to any one of (1) to ( 10 ).
( 16 ) The image processing apparatus according to ( 15 ), wherein the image forming unit is either a thermal head or a laser irradiation apparatus.
( 17 ) The image processing according to ( 15 ) or (16), wherein the image erasing unit is any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, a heat bar, and a laser irradiation device. Device.
( 18 ) At least one of heating the thermoreversible recording medium to form an image on the thermoreversible recording medium and heating the thermoreversible recording medium to erase the image formed on the thermoreversible recording medium. And the thermoreversible recording medium is the thermoreversible recording medium according to any one of (1) to ( 10 ).
( 19 ) The image processing method according to ( 18 ), wherein the image formation is performed using either a thermal head or a laser irradiation apparatus.
( 20 ) The erasing of the image is performed using any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, a heat bar, and a laser irradiation device, as described in ( 18) or ( 19 ) above This is an image processing method.
( 21 ) The image processing method according to any one of ( 18 ) to ( 20 ), wherein a new image is formed while erasing the image using a thermal head.

The thermoreversible recording medium of the present invention is provided with a support, a thermosensitive layer whose color tone reversibly changes depending on temperature on the support, and at least one protective layer on the thermosensitive layer, An anti-curl layer comprising at least one layer on the surface opposite to the surface on which the heat-sensitive layer of the support is provided, an anti-static layer provided thereon, and a resin type constituting the heat-sensitive layer and the anti-curl layer; and The protective layer and the resin species constituting the antistatic layer are the same.
In the thermoreversible recording medium, the heat-sensitive layer is heated by a heating element to cause color development or decoloration, and the protective layer and the heat-sensitive layer surface constituting the heat-sensitive layer surface contract due to repeated heat history. In the thermoreversible recording medium according to the present invention, two layers of an anti-curl layer and an antistatic layer are provided on the opposite surface of the substrate to suppress the shrinkage, and a protective layer that requires physical strength and heat resistance strength is further provided. And the resin type of the antistatic layer, and the heat sensitive layer and the resin type of the anti-curl layer are the same, so that a thermoreversible recording medium that does not curl even when used more than 100 times is obtained.

  Furthermore, in order to prevent the occurrence of poor conveyance and curling even in a usage environment from a low temperature environment region to a high temperature environment region that exceeds the conventional assumed range, the above-described expansion and contraction of each layer under the environment is considered. Configuration was adopted. In addition, by providing an antistatic layer in consideration of poor conveyance such as double feeding due to sticking of media due to static electricity in a low-humidity environment, it is possible to transport thermoreversible recording media even when printing using a printer in each environment. It is an excellent medium that does not cause defects.

  Even if repeated erasure printing is performed according to the present invention, the curl of the medium is small, the occurrence of curling of the medium is small even in a low temperature environment or a high temperature environment, and the occurrence of curl is small even if repeated erasure printing is performed in each environment. , A thermoreversible recording medium that is excellent in transportability even in a low temperature environment to a high temperature environment, is less likely to cause a transport failure even in batch large-volume issuance, and can set a specified number of sheets in a printer stacker, and the thermoreversible recording medium It is possible to provide a thermoreversible recording member, an image processing apparatus, and an image processing method.

(Thermal reversible recording medium)
The thermoreversible recording medium of the present invention has at least a support, an anti-curl layer, an antistatic layer, a protective layer, and a heat-sensitive layer (hereinafter sometimes referred to as “recording layer” or “rewrite layer”). In addition, other layers are provided as necessary.
<Support>
The support is not particularly limited in its shape, structure, size, etc., and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape. It may be a single layer structure or a laminated structure, and the size can be appropriately selected according to the size of the thermoreversible recording medium.

Examples of the material for the support include inorganic materials and organic materials. Examples of the inorganic material include glass, quartz, silicon, silicon oxide, aluminum oxide, SiO ₂ and metal. Examples of the organic material include paper, cellulose derivatives such as cellulose triacetate, synthetic paper, polyethylene terephthalate, polycarbonate, polystyrene, polymethyl methacrylate, and the like. These may be used individually by 1 type and may use 2 or more types together.

The support may be surface-modified by corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. for the purpose of improving the adhesion of the coating layer. . Moreover, you may color with a coloring pigment, ink, etc. The support may be whitened by adding a white pigment such as titanium oxide.
There is no restriction | limiting in particular as thickness of the said support body, According to the objective, it can select suitably, 50-2,000 micrometers is preferable, Furthermore, 75-1,000 micrometers is more preferable.

<Anti-curl layer>
The anti-curl layer is not particularly limited as long as it is formed on the surface of the support opposite to the surface on which the heat-sensitive layer is provided, and can be selected according to the purpose, and is formed as one or more layers. May be.
It is desirable that an antistatic layer is provided on the anti-curl layer so that the anti-curl layer is not exposed on the outermost surface. The anti-curl layer is made of at least a binder resin, and may contain other fillers, lubricants, color pigments and other components as necessary.

In the present invention, the anti-curl layer and the heat-sensitive layer need to be on the opposite surfaces via the support, and the binder resin constituting the anti-curl layer and the heat-sensitive layer must be the same. This is because the thermal layer has the function of repeating erasing and printing by heat, so a thermal history is always added at the time of erasing and printing, so it supports expansion and contraction of the thermal layer at the top of the support due to heat. This is because the anti-curl layer under the body needs to be relaxed.
In addition, since the behavior of shrinkage and expansion in low and high temperature environments differs depending on the resin type of the binder, the same type of behavior can be achieved by using the same type. Will not occur.

  Examples of the resin type of the binder include a thermosetting resin, an ultraviolet (UV) curable resin, an electron beam curable resin, a thermoplastic resin, and the like. Among these, a thermosetting resin is particularly preferable. In order to maximize the function of the heat-sensitive layer, a thermosetting resin is preferable. Therefore, it is preferable to use a thermosetting resin for the anti-curl layer in accordance with the heat-sensitive layer.

There is no restriction | limiting in particular as a thermosetting resin, According to the objective, it can select suitably from well-known things. Examples thereof include a resin having a group that reacts with a crosslinking agent such as a hydroxyl group or a carboxyl group, or a resin obtained by copolymerizing a monomer having a hydroxyl group, a carboxyl group, or the like with another monomer.
Examples of such thermosetting resin include phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate resin, cellulose acetate butyrate resin, acrylic polyol resin, polyester polyol resin, polyurethane polyol resin, and the like. Among these, acrylic polyol resin, polyester polyol resin, and polyurethane polyol resin are preferable, and acrylic polyol resin and polyester polyol resin are particularly preferable.

  The acrylic polyol resin uses a (meth) acrylic acid ester monomer, an unsaturated monomer having a carboxylic acid group, an unsaturated monomer having a hydroxyl group, and other ethylenically unsaturated monomers. It can be synthesized according to a known solution polymerization method, suspension polymerization method, emulsion polymerization method and the like.

Examples of the unsaturated monomer having a hydroxyl group include hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), and 2-hydroxybutyl. Monoacrylate (2-HBA), 1,4-hydroxybutyl monoacrylate (1-HBA) and the like are used, but the use of a monomer having a primary hydroxyl group has better crack resistance and durability of the coating film. Therefore, 2-hydroxyethyl methacrylate is preferably used.
The acrylic polyol resin and polyester polyol resin are preferably cross-linked using a cross-linking agent from the viewpoint of improving the repeated durability of printing and erasing images on the heat-sensitive layer.

There is no restriction | limiting in particular as said crosslinking agent, According to the objective, it can select suitably, For example, isocyanate, amino resin, a phenol resin, amines, an epoxy compound, etc. are mentioned. Among these, isocyanates are preferable, and polyisocyanate compounds having a plurality of isocyanate groups are particularly preferable.
Examples of the isocyanates include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), or adduct type, burette type, isocyanurate type, or blocking by trimethylolpropane. Isocyanates and the like.

The amount of the crosslinking agent added to the binder resin is preferably such that the ratio of the functional group of the crosslinking agent to the number of active groups contained in the binder resin is 0.01-2. If it is less than 0.01, the heat strength is insufficient, and if it is added in excess of 2, it adversely affects the color developing / decoloring properties.
Furthermore, you may use the catalyst used for this kind of reaction as a crosslinking accelerator. Examples of the crosslinking accelerator include tertiary amines such as 1,4-diazabicyclo [2,2,2] octane, metal compounds such as organotin compounds, and the like.

The gel fraction of the thermosetting resin when thermally crosslinked is preferably 30% or more, more preferably 50% or more, and still more preferably 70% or more. When the gel fraction is less than 30%, the crosslinked state is not sufficient and the durability may be inferior.
The hydroxyl value of the thermosetting resin is preferably 70 KOHmg / g or more, more preferably 90 KOHmg / g or more. When the hydroxyl value is 70 KOHmg / g or more, durability, coating film hardness, and crack resistance are improved.

  The anti-curl coating layer Tg is desirably 100 ° C. or higher. In the process of repeated erasure printing by heat, if the coating film Tg is less than 100 ° C, the durability of the film is insufficient, and the film peels off due to repeated contact with the transport roller etc. in the transport path of the printer, etc. to prevent curling Problems such as peeling of the film applied on the layer are likely to occur. When the temperature is 100 ° C. or higher, the strength as a film increases, the film does not peel off, and the effect of preventing curling also increases. The coating film Tg is more preferably 120 ° C. or higher. When the coating film Tg is 120 ° C. or higher, the coating film strength is further increased, and the curl prevention effect is further enhanced.

The coating film Tg is defined as the peak temperature of the logarithmic decay rate measured by the free-damping vibration method of a rigid pendulum as disclosed in Patent Document 10. The logarithmic damping factor is a physical property value that represents the viscoelasticity of the paint film.The change in viscosity when the paint film changes from the glass state in the low temperature range to the rubber state in the high temperature range as the temperature is applied. It is obtained by analyzing the amplitude. This is because the temperature at which the logarithmic decay rate exhibits a peak represents the glass transition temperature (Tg) when the coating film transitions from the glass state to the rubber state.

In the present invention, the logarithmic decay rate is measured by, for example, the following method.
Measuring apparatus: Randomized pendulum type physical property tester RPT-3000 manufactured by A & D Co., Ltd.
Rigid pendulum: Combination of round bar type cylinder edge RBP-040 and rigid pendulum FRB-100
Sample: A thermal recording layer having a thickness of 1 μm or more provided on an arbitrary support is cut into a width of 10 mm and a length of about 25 mm.
Measurement procedure and analysis method: A measurement sample is placed on a heating / cooling block, and a cylinder edge RBP-040 is placed on the sample measurement surface.
Next, while the measurement sample is heated from 30 ° C. to 200 ° C. at a rate of temperature increase of 5 ° C./min, the vibration of the pendulum is started, the period of free vibration of the pendulum and the amplitude of vibration are analyzed, and each measurement temperature is measured. The logarithmic decay rate is obtained and a logarithmic decay rate curve is plotted. The temperature at which the logarithmic decay rate curve shows the maximum value is taken as the logarithmic decay rate peak temperature. The logarithmic decay rate at this temperature is Δ1. Further, the value of the logarithmic decay rate when the baseline of the decay rate curve in the lower temperature region than the temperature at which the logarithmic decay rate peak appears is extrapolated to the temperature at which the logarithmic decay rate peak appears is Δ2. When the logarithmic decay rate peak does not appear using these conditions, the measurement conditions can be arbitrarily changed.

  As described above, the logarithmic decay rate curve is measured. When another layer is laminated on the coating surface to be measured, first, such as TEM (transmission electron microscope), SEM (scanning electron microscope), etc. Investigate the layer structure of the thermoreversible recording medium and the film thickness of each layer by cross-sectional observation, and scrape the surface for the film thickness of the other layers until the target paint film surface appears on the surface. Expose and measure. In this method, in order to prevent contamination of other layers on the target paint film surface as much as possible, it is necessary to reduce the film thickness for the other layers and to slightly cut the target paint film surface to prevent the influence on the measured value. is there.

  The coating film Tg of the anti-curl layer is desirably higher than the coating film Tg of the heat sensitive layer. The thermoreversible recording medium performs recording and erasing by applying heat from the recording layer surface side. At this time, the heat distribution is highest at the outermost surface of the recording layer surface closest to the heat supply source, and then is transmitted to the heat sensitive layer and to the support. Further, it is transmitted to the anti-curl layer on the back surface and the other layers, but a large inclination of the heat distribution is generated here. That is, since a temperature difference is generated between the heat applied to the heat-sensitive layer and the anti-curl layer, it is necessary to pay attention to this difference to solve the problem. The binder resin constituting the anti-curl layer and the heat-sensitive layer undergoes thermal shrinkage by repeatedly applying heat for printing and erasing, but the degree of thermal shrinkage varies depending on the applied temperature. Since heat shrinkage tends to shrink as the coating film becomes harder, if attention is paid to the coating film Tg as the hardness of the coating film, the coating film Tg of the anti-curl layer is higher than the coating film Tg of the heat-sensitive layer, so that the heat applied to the medium Even if there is a difference in temperature, the difference in shrinkage can be absorbed, and even if heat for repeated erasing printing is applied, the medium does not curl.

The coating film Tg of the anti-curl layer is preferably higher by 10 ° C. or more, more preferably 15 ° C. or more than the coating film Tg of the thermosensitive layer.
If the difference in the coating film Tg is less than 10 ° C., the effect of absorbing the thermal shrinkage due to the thermal history of the recording layer surface on the curl prevention layer side is insufficient, and the occurrence of curling also increases due to environmental changes. . When the temperature is 10 ° C. or higher, the anti-curl layer surface can absorb the shrinkage of the recording layer surface due to the thermal history of repeated erasure printing. Occurrence can be reduced.

In addition to the binder resin, other components such as a filler, a lubricant, and a coloring pigment can be added to the anti-curl layer as necessary.
There is no restriction | limiting in particular as said other filler, For example, an inorganic filler, an organic filler, etc. are mentioned.
Examples of the inorganic filler include carbonates, silicates, metal oxides, sulfate compounds, and the like. Examples of the organic filler include silicone resin, cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, styrene resin, acrylic resin, polyethylene resin, formaldehyde Resin, polymethyl methacrylate resin, and the like.

The shape of the filler is not particularly limited, but a plate shape or a needle shape is preferable because it not only improves the strength of the anti-curl layer but also tends to be strong against curling.
The content of the other filler is preferably 70% by mass or less, more preferably 50% by mass or less, and further preferably 30% by mass or less.
When the content exceeds 70% by mass, the anti-curl preventing effect of the anti-curl layer may be weakened.

Examples of the lubricant include synthetic waxes, vegetable waxes, animal waxes, higher alcohols, higher fatty acids, higher fatty acid esters, amides, and the like.
Further, the anti-curl layer may be colored. A dye or pigment is preferably used for coloring.

<Antistatic layer>
The antistatic layer is formed on the surface of the support opposite to the surface on which the recording layer is provided and may be formed on the outer side of the anti-curl layer, and may be formed in one or more layers. The exposed outermost surface layer is particularly preferable.
The antistatic layer contains at least an antistatic agent, and may contain other components such as a binder resin and, if necessary, other fillers, lubricants, and coloring pigments.
Examples of the antistatic agent include an electron conductive antistatic agent and an ionic conductive antistatic agent, but it is preferable to use an electron conductive antistatic agent that does not deteriorate its antistatic function even in a low humidity environment.

  Examples of electron conductive antistatic agents include conductive fillers that impart conductivity to sulfides such as zinc sulfide, copper sulfide, cadmium sulfide, nickel sulfide, and palladium sulfide, barium sulfate, tin oxide, zinc oxide, and indium oxide. Alternatively, a metal oxide such as titanium oxide, a conductive filler such as a conductive carbon filler, a silicon organic compound, or a surface metal plating filler can be used.

As the shape of the conductive filler, various shapes such as a spherical shape, an indeterminate shape, a plate shape, a layer shape, and a needle shape can be used.
Among these conductive fillers, it is particularly preferable to use acicular conductive fillers. By including the acicular conductive filler, static electricity generated due to friction with the roller during conveyance or friction between the thermoreversible recording media can be leaked without accumulating in the thermoreversible recording medium. As a result, sticking of the thermoreversible recording medium is suppressed, and there is an effect that dust and dust that cause printing defects during erasure printing are not adsorbed.
Further, by including the acicular conductive filler in the back layer, the acicular conductive fillers are entangled with each other, so that the occurrence of curling due to the thermal history can be suppressed even if repeated erasure printing is performed. Moreover, since it is a needle-like conductive filler, the end of the filler is likely to appear on the surface of the thermoreversible recording medium, and irregularities can be provided on the surface of the thermoreversible recording medium, thereby improving the transportability. Moreover, since it becomes easy to contact fillers by using an acicular conductive filler, it becomes possible to implement | achieve electroconductivity with few addition amounts.

(Acicular conductive filler)
There is no restriction | limiting in particular as said acicular conductive filler, According to the objective, it can select suitably, For example, what carried out the surface treatment of the acicular crystal | crystallization with the electrically conductive agent etc. are suitable.
Examples of the acicular crystals include titanium oxide, potassium titanate, aluminum borate, silicon carbide, and silicon nitride. Among these, titanium oxide is particularly preferable from the viewpoint of easy control of crystal growth and the ability to obtain crystals of a stable size. The titanium oxide is also preferable in that it has a strength that is not destroyed during dispersion when creating a coating liquid, can roughen the surface of the coating film, and maintain the surface strength and hardness.

  There is no restriction | limiting in particular as said electrically conductive agent, According to the objective, it can select suitably, For example, antimony dope tin oxide, tin dope indium oxide, aluminum dope zinc oxide, fluorine dope tin oxide etc. are mentioned. Among these, antimony-doped tin oxide is particularly preferable from the viewpoints of surface electrical resistivity stability, metal electrical conductivity, stability, and cost. By covering the needle-shaped crystal with the antimony-doped tin oxide, the function of leaking static electricity generated in the recording medium can be lost without water, and the antistatic layer has no humidity dependency. It becomes a physical property.

  Specifically, the needle-like conductive filler is particularly preferably titanium oxide whose surface is coated with antimony-doped tin oxide. Since the needle-like conductive filler is made of titanium oxide, the strength of the filler can be increased, so that the influence of heat and pressure by the head during repeated erasure printing, friction with the conveying roller, contact, and thermoreversible recording media rub against each other. Irregularities can be provided on the surface without being affected by friction at the time.

  The needle-like conductive filler has a major axis of 1 μm or more and 10 μm or less and a minor axis of 0.1 μm or more and 0.5 μm from the viewpoint that fillers can be effectively overlapped to improve the static electricity leakage effect. The following is preferred. More preferably, the long axis is 2 μm or more and 8 μm or less, and the short axis is 0.15 μm or more and 0.4 μm or less. Further, the major axis is particularly preferably 3 μm or more and 7 μm or less, and the minor axis is particularly preferably 0.2 μm or more and 0.35 μm or less.

  When the major axis is less than 1 μm, the overlap of fillers may be insufficient and the static electricity leakage effect may be reduced, the filler may not appear on the surface of the coating film, and there will be no static electricity escape. May become smooth and poor conveyance may occur due to adhesion of the thermoreversible recording medium. On the other hand, if the long axis exceeds 10 μm, the surface of the thermoreversible recording medium will be greatly raised, which may hinder the conveyance, or wear the members that are in contact during conveyance, such as the head and the conveyance roller.

Further, if the minor axis is less than 0.1 μm, the strength of the filler becomes insufficient, and wear occurs particularly in the process of repeatedly erasing and printing the portion appearing on the surface, maintaining the effect of the initial state. Can be difficult to do. On the other hand, if it exceeds 0.5 μm, the needle-like conductive filler becomes too thick, so that large irregularities appear on the surface, which may hinder the conveyance, or wear the members that contact the conveyance such as the head and the conveyance roller. .
10-40 mass% is preferable, as for content in the said back layer of the said acicular conductive filler, 15-35 mass% is more preferable, and 17-25 mass% is still more preferable.

When the content is less than 10% by mass, the overlap of the acicular conductive fillers becomes insufficient, the surface resistance value rapidly increases, and as a result, conveyance failure may occur, and when the content exceeds 40% by mass. Many fillers appear on the surface, large irregularities appear on the surface of the thermoreversible recording medium, which deteriorates the transportability of the thermoreversible recording medium and wears the transport roller, thermal head, and other members. There is.

(Binder resin)
There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, a thermosetting resin, an ultraviolet-ray (UV) curable resin, an electron beam curable resin, etc. are mentioned, These Among these, ultraviolet (UV) curable resins and thermosetting resins are preferable, and ultraviolet (UV) curable resins are more preferable.

The UV curable resin can form a very hard film after curing, and an antistatic layer excellent in repeated durability can be obtained. Moreover, although the said thermosetting resin is a little inferior to the said UV curable resin, the surface can be hardened and it is excellent in repeated durability.
The UV curable resin is not particularly limited and can be appropriately selected from known ones according to the purpose. For example, urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, vinyl And monomers such as unsaturated polyester oligomers and various monofunctional and polyfunctional acrylates, methacrylates, vinyl esters, ethylene derivatives, and allyl compounds. By mixing two or more of these monomers or oligomers, the hardness, shrinkage, flexibility, coating strength, etc. of the resin film can be appropriately adjusted.

Examples of the polyfunctional monomer or oligomer include trimethylolpropane triacrylate, pentaerythritol triacrylate, glycerin PO addition triacrylate, trisacryloyloxyethyl phosphate, pentaerythritol tetraacrylate, trimethylolpropane propylene oxide 3 mol addition Triacrylate, glyceryl propoxytriacrylate, dipentaerythritol polyacrylate, polyacrylate of caprolactone adduct of dipentaerythritol, propionic acid / dipentaerythritol triacrylate, hydroxypivalaldehyde-modified dimethylolpropyne triacrylate, propion Acid / dipentaerythritol tetraacrylate, ditrimethylo Propane tetraacrylate, pentaacrylate of dipentaerythritol propionate, trimethylolpropane triacrylate added urethane prepolymer, dipentaerythritol hexaacrylate (DPHA), .epsilon.-caprolactone adduct of DPHA, and the like.
In order to cure the monomer or oligomer using ultraviolet rays, it is necessary to use a photopolymerization initiator and a photopolymerization accelerator.

The photopolymerization initiator can be broadly classified into a radical reaction type and an ion reaction type, and the radical reaction type is classified into a photocleavage type and a hydrogen abstraction type.
Examples of the photopolymerization initiator include isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether benzoin methyl ether, 1-phenyl-1,2-propanedione-2- (o-ethoxycycarbonyl) oxime, 2,2 -Dimethoxy-2-phenylacetophenone benzyl, hydroxycyclohexyl phenyl ketone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone, chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2- Examples thereof include methylthioxanthone and chlorine-substituted benzophenone, and are used alone or in combination of two or more, but are not limited thereto.

As the photopolymerization accelerator, those having an effect of improving the curing rate with respect to hydrogen abstraction type photopolymerization initiators such as benzophenone series and thioxanthone series are preferable. For example, aromatic tertiary amines and aliphatic amines can be used. Specific examples include p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like. These photopolymerization accelerators are used alone or in combination of two or more.
0.1-20 mass% is preferable with respect to the total mass of the resin component of the said back layer, and, as for the addition amount of the said photoinitiator or a photoinitiator, 1-10 mass% is more preferable.
Further, as the thermosetting resin, those similar to the binder resin used in the anti-curl layer can be suitably used.

Furthermore, the thermosetting resin is desirably crosslinked using a crosslinking agent, and the same crosslinking agent as that used in the anti-curl layer can be suitably used.
The binder resin for the antistatic layer is preferably harder than the binder resin for the anticurl layer. This is because the antistatic layer is on the outer side of the anti-curl layer and becomes the outermost surface layer, so physical contact, friction, pressure and thermal history must be added, so it must be strong enough. is there.

The binder resin of the antistatic layer is preferably the same resin type constituting the protective layer.
Similar to the antistatic layer, the protective layer is the outermost surface layer of the recording layer surface, and therefore needs to have physical and thermal strength. When the strength is improved, the curl becomes larger due to the influence of thermal history and environment, and therefore the resin type of the binder of the antistatic layer and the protective layer needs to be the same.
In addition to the conductive filler and the binder resin, other components such as other fillers, lubricants, and color pigments can be added to the antistatic layer as necessary.
Those used for the anti-curl layer are also preferably used.

In the thermoreversible recording medium of the present invention, the surface resistance value of the antistatic layer (exposed outermost surface) is preferably 1 × 10 ¹¹ Ω / □ or less even in all use environments where the thermoreversible recording medium is used. More preferably, it is 1 × 10 ⁹ Ω / □ or less. The surface resistance value is 1 × 10 ¹¹ Ω / □
If it is higher than that, it shows the property of being charged, but it is charged at 1 × 10 ¹¹ Ω / □ or less, but decays quickly, and it is hardly charged at 1 × 10 ⁹ Ω / □ or less.

Further, when a coating film having a surface resistance value of 1 × 10 ¹¹ Ω / □ is measured in a low humidity environment, the resistance value may be 1 × 10 ¹² Ω / □ or more. This is because even if the antistatic agent to be used is not affected by humidity, the effect becomes insufficient by charging the resin as the binder. Therefore, by designing the back layer to have a surface resistance value of 1 × 10 ¹¹ Ω / □ or less in any environment from low temperature and low humidity to high temperature and high humidity, This eliminates the static charge and prevents the conveyance failure.
Here, the surface resistance value can be measured using a known surface resistance measuring device.

  The method for forming the anti-curl layer and anti-static layer is not particularly limited and may be appropriately selected depending on the purpose. The binder resin, various fillers, and other additives are mixed together with a solvent. A coating liquid prepared by uniformly mixing and dispersing the resulting mixture is used.

The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, water, alcohol, ketone, amide, ethers, glycols, glycol ethers, glycol ester acetates, esters, aromatics Aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, sulfoxides, pyrrolidones, and the like. Among these, water, methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, N, N-dimethylformamide, N, N-dimethylacetamide, tetrahydrofuran, 1,4-dioxane, 3, 4-dihydro-2H-pyran, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, methyl acetate, ethyl acetate, butyl acetate, toluene, xylene, hexane, heptane, cyclohexane, dimethyl sulfoxide, etc. are preferred. . Furthermore, water, isopropanol, n-butanol, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, ethyl acetate, butyl acetate, toluene, xylene and the like are particularly suitable.
In addition, the said coating liquid can be prepared using well-known coating liquid dispersion | distribution apparatuses, such as a paint shaker, a ball mill, an attritor, a three roll mill, a keddy mill, a sand mill, a dyno mill, a colloid mill.

  The coating method is not particularly limited and may be appropriately selected depending on the purpose. A support that is continuously cut in a roll shape or a sheet shape is conveyed, and, for example, a blade is provided on the support. Apply by known methods such as coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating, die coating To do. And the apply | coated sheet | seat is continuously conveyed in a ventilation dryer, and is dried for 10 seconds-10 minutes at 30-150 degreeC.

In this case, in particular, in order to perform defect-free coating, the coating solution is natural or synthetic such as a conventional filter paper, a mesh such as stainless mesh, nylon mesh, or a cotton filter, a fiber carbon filter, etc. in advance or during feeding. To avoid foreign matters, avoid mixing of bubbles, and agglomeration of dispersions by passing through membrane filtration such as fiber filters and membrane filters, or applying ultrasonic waves for 1 minute to 200 hours, preferably 10 minutes to 80 hours. it can.
The application is preferably performed in a clean room of class 10,000 or less.

  For the drying, it is preferable to heat an inert gas such as air or nitrogen that has passed through a filter and a dehumidifying device, and spray this from the front surface, the back surface, or both. Among these, filtration by a cotton filter or a membrane filter or ultrasonic irradiation is preferable. The uniformity of the coating layer is improved by appropriately selecting and using the apparatus as described above.

  When the anti-curl layer and anti-static layer are heat-cured, it is preferable to perform curing as necessary after coating and drying. This curing can promote crosslinking in the case of thermal crosslinking. In other cases, the residual solvent can be reduced to stabilize the quality. A thermostatic bath or the like may be used for a relatively short time at a relatively high temperature, or a heat treatment may be performed at a relatively low temperature for a long time. The curing condition is preferably about 1 minute to 200 hours under a temperature condition of about 10 to 130 ° C., more preferably about 2 minutes to 180 hours under a temperature condition of 15 to 100 ° C.

In the production of the anti-curl layer and the anti-static layer, productivity is emphasized, and it is difficult to take time until the crosslinking is sufficiently completed. Therefore, it is preferable to heat for about 2 minutes to 120 hours under a temperature condition of 40 to 100 ° C. The curing may be performed by directly applying warm air to the application surface, or may be left in a thermostatic bath in a state of being cut into a roll shape or a sheet shape. When it is not desired to apply temperature, a vacuum drying method may be used. The physical properties can be controlled and the production process can be made more efficient by increasing or decreasing the temperature stepwise, or by dividing into multiple times such as after application of the upper layer or simply by dividing the time.
The film formation by ultraviolet rays is preferably performed by applying a photopolymerization reaction with an ultraviolet irradiation device after coating and drying. For the ultraviolet curing, a conventionally known irradiation apparatus can be used, and examples of the light source include a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp.

A light source having an emission spectrum corresponding to the ultraviolet absorption wavelength of the photopolymerization initiator or photopolymerization accelerator may be used. Moreover, as said irradiation conditions, what is necessary is just to determine a lamp output and a conveyance speed according to irradiation energy required in order to bridge | crosslink resin. In addition, when performing cross-linking curing with an electron beam, the electron beam irradiation device may be selected from a scanning type and a non-scanning type depending on the purpose of the irradiation area, irradiation dose, etc. What is necessary is just to determine an electric current, irradiation width, and a conveyance speed according to the dose required for bridge | crosslinking.
Although one or more other layers may be provided on the antistatic layer, it is desirable to provide a device for leaking static electricity so that a part of the antistatic layer is exposed to the outermost surface layer.

<Protective layer>
In the thermoreversible recording medium of the present invention, a protective layer is provided on the thermosensitive layer for the purpose of protecting the thermosensitive layer. There is no restriction | limiting in particular in this protective layer, According to the objective, it can select suitably, For example, you may form in one or more layers, and it is preferable to provide in the outermost surface exposed.

The protective layer may contain a binder resin and, if necessary, other components such as a filler, a lubricant, and a coloring pigment.
As the binder resin, a resin that can be cured by heat, ultraviolet rays, electron beams, or the like is preferably used. Among these, thermosetting resins and ultraviolet curable resins are preferable, and ultraviolet curable resins are more preferable.

When the thermosetting resin is used, the same binder resin and crosslinking agent used in the anti-curl layer using an isocyanate compound or the like as a crosslinking agent can be preferably used.
Moreover, when using the said ultraviolet curable resin, the same thing used by the antistatic layer can be used suitably.
Since the protective layer has the purpose of protecting the heat sensitive layer from the heat history at the time of erasure printing and the physical pressure of the heating element, it is desirable that the protective layer has a coating film strength than the heat sensitive layer.

Further, it is desirable to provide the same type of UV curable resin layer or thermosetting resin layer for the protective layer and the antistatic layer. This makes it possible to balance the curl. That is, during repeated erasure printing, the resin is heated by a thermal head, a heat roller, an erase bar, etc., and the resin heated at that time shrinks. However, the UV curable resin has a particularly large shrinkage ratio, and the thermosetting resin. However, the shrinkage ratio is not as high as that of the UV curable resin.
Furthermore, there is a characteristic that the degree of shrinkage changes depending on the thermal history. Therefore, it is possible to balance the curl by providing the same type of UV curable resin layer or thermosetting resin layer in the protective layer and the antistatic layer. On the other hand, if different types of UV curable resin layers or thermosetting resin layers are used for the protective layer and the antistatic layer, charging is easily performed when the thermoreversible recording media are rubbed due to the difference in resin characteristics. The effect of the antistatic filler of the prevention layer cannot be sufficiently exhibited.

In order to improve transportability, a silicone having a polymerizable group, a silicone-grafted polymer, a wax, a release agent such as zinc stearate, and a lubricant such as silicone oil can be added. The amount added is preferably 0.01 to 50% by mass, more preferably 0.1 to 40% by mass, based on the total weight of the resin component of the protective layer. Even if the addition amount is small, the effect is exhibited, but if it is less than 0.01% by mass, the effect due to the addition cannot be obtained, and if it exceeds 50% by mass, there may be a problem in adhesion to the lower layer.
In addition, the protective layer may contain an organic ultraviolet absorber, and the content thereof is preferably in the range of 0.5 to 10% by mass with respect to the total mass of the resin components of the protective layer.

Furthermore, an inorganic filler or an organic filler may be used in order to improve head matching properties and transportability. Examples of the inorganic filler include calcium carbonate, kaolin, silica, aluminum hydroxide, alumina, aluminum silicate, magnesium hydroxide, magnesium carbonate, magnesium oxide, titanium oxide, zinc oxide, barium sulfate, and talc. These may be used individually by 1 type and may use 2 or more types together.

As a particle size of the said inorganic pigment, 0.01-10.0 micrometers is preferable, for example, and 0.05-8.0 micrometers is more preferable. The amount of the inorganic pigment added is preferably 0.001 to 2 parts by mass and more preferably 0.005 to 1 part by mass with respect to 1 part by mass of the heat resistant resin.
Examples of the organic filler include silicone resin, cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, styrene resin, acrylic resin, polyethylene resin, formaldehyde Resin, polymethyl methacrylate resin, and the like.

Furthermore, the protective layer may contain conventionally known surfactants, leveling agents, antistatic agents and the like as additives.
When using an antistatic agent, a conductive filler may be added, or a needle-like conductive filler may be added. From the standpoint of antistatic, if the protective layer on the opposite side of the antistatic layer has an antistatic function, the effect of electrostatic charging is further eliminated, and conveyance such as double feeding and paper jams due to media sticking in a low humidity environment Defects can be further prevented.

10-40 mass% is preferable, as for content in the said protective layer of the said acicular conductive filler, 15-35 mass% is more preferable, and 17-25 mass% is still more preferable.
There is no restriction | limiting in particular as thickness of the said protective layer, According to the objective, it can select suitably, For example, 0.1-10.0 micrometers is preferable. When the thickness of the protective layer is less than 0.1 μm, the protective effect of the heat-sensitive layer may not be sufficient, and when it exceeds 10.0 μm, the thermal sensitivity may decrease.
Solvents used in the coating solution for the antistatic layer, a dispersion device for the coating solution, a coating method for the intermediate layer, a drying / curing method for the intermediate layer, etc. are known methods used in the anti-curl layer and the antistatic layer. Can be used.

  In the thermoreversible recording medium of the present invention, the difference in static friction coefficient between the antistatic layer and the protective layer, between the antistatic layers, and between the protective layers is preferably 0.1 or less. This is so that when the thermoreversible recording medium is set in the printer, the thermoreversible recording medium will not cause a conveyance failure in the printer even if the front and back are set incorrectly. In other words, when a thermoreversible recording medium is set in the printer, the medium is conveyed one by one by a paper feed roller and a separation pad. At this time, if the difference in the friction coefficient becomes larger than 0.1, a frictional force is generated between the thermoreversible recording media. When the sheets are fed one by one, there is a phenomenon in which separation is not possible due to the frictional difference between the thermoreversible recording media when the sheet is separated by the sheet feeding roller and the separation pad. More ideally, the difference between the respective friction coefficients is closer to zero.

The static friction coefficient between the antistatic layer and the protective layer, between the antistatic layers, and between the protective layers is preferably 0.05 to 0.3.
When the coefficient of static friction is less than 0.05, the stacked thermoreversible recording media are slippery and it is difficult to maintain the stacked thermoreversible recording media in a stacked state, which is difficult to handle. Further, since the thermoreversible recording media are easy to move, there is also a problem that the thermoreversible recording media rub against each other before being used and the surface is damaged. When it exceeds 0.3, the frictional force between the thermoreversible recording media increases, so the frictional force between the thermoreversible recording medium surface and the paper feed roller in the paper feed system, the frictional force between the thermoreversible recording medium back surface and the separation pad. The relationship between the frictional force between the separation pad and the back surface and the frictional force between the thermoreversible recording media approaches or reverses, and the thermoreversible recording medium cannot be transported. The design range of the separation pad is limited.

<Thermosensitive layer>
The heat-sensitive layer includes at least a material whose color tone reversibly changes depending on temperature, and includes a binder resin, a crosslinking agent, and other components as necessary.
The “material whose color tone reversibly changes depending on temperature” in the heat-sensitive layer means a phenomenon that causes a visible change reversibly due to a temperature change, and is caused by a difference in heating temperature and cooling rate after heating. It means that a relatively colored state and a decolored state can be formed. In this case, the visible change is divided into a change in color state and a change in shape, but in the present invention, a material that mainly changes the color state is used.
The change in the color state includes a change in transmittance, reflectance, absorption wavelength, scattering degree, and the like, and an actual thermoreversible recording material displays by combining these changes. More specifically, there is no particular limitation as long as the transparency and color tone are reversibly changed by heat, and it can be appropriately selected according to the purpose. For example, a first color state is obtained at a first specific temperature higher than room temperature, and a second color state is obtained by heating at a second specific temperature higher than the first specific temperature and then cooling. And the like. Among these, those in which the color state changes particularly at the first specific temperature and the second specific temperature are preferably used.

As these examples, it becomes transparent at the first specific temperature, becomes cloudy at the second specific temperature (Patent Document 11), develops color at the second specific temperature, and decolorizes at the first specific temperature. (Patent Documents 12, 13, 14, etc.), a cloudy state at the first specific temperature and a transparent state at the second specific temperature (Patent Document 15), black, red, Examples include those that develop blue color or the like and decolor at a second specific temperature (Patent Documents 16 and 17).
Among these, in particular, a system in which an organic low molecular weight substance such as a higher fatty acid is dispersed in a resin matrix, an electron donating color developing compound (color former) described later, and an electron accepting compound (developer) A system using is preferred.

-Electron donating color compound-
There is no restriction | limiting in particular as said electron-donating coloring compound, According to the objective, it can select suitably, For example, a leuco dye etc. are mentioned.
The leuco dye itself is a colorless or light-colored dye precursor and is not particularly limited and can be appropriately selected from conventionally known dyes such as triphenylmethane phthalide, triallyl methane, and fluorane. Phenothiocyan, thioferolane, xanthene, indophthalyl, spiropyran, azaphthalide, chromenopyrazole, methine, rhodamine anilinolactam, rhodamine lactam, quinazoline, diazaxanthene, bislactone Etc. are preferably used. Of these, fluorane-based or phthalide-based leuco dyes are preferred from the viewpoint of color development / decoloration characteristics, color, storage stability, and the like. -Np-toluidino) amino-6-methyl-7-anilinofluorane, 3-di (n-butylamino) -6-methyl-7-anilinofluorane, 3-n-methyl-N-propyl Black color leuco dyes such as amino-6-methyl-7-anilinofluorane; 3-diethylamino-7,8-benzofluorane, 3- (N-ethyl-N-isoamyl) -7,8-benzo Fluorane, 1,3-dimethyl-6-diethylaminofluorane, 1,3-dimethyl-6-di-n-butylaminofluorane, 3-diethylamino-7-methylfluorane, 3,3-bis (1- Red chromogenic leuco dyes such as butyl-2-methylindole-3-yl) phthalide; crystal violet lactone, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole) -1-yl) -4-azaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-indol-3-yl) phthalide and other blue-coloring leuco dyes; 10-diethylamino-2- Ethylbenzo [1,4] thiazino [3,2-b] fluorane, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3-bis (4-diethylamino-2) -Ethoxyphenyl) -4-azaphthalide, 3- [2,2-bis (1-ethyl-2-methyl-3-indolyl) vinyl] -3- (4-diethylamino) Phenyl) phthalide, 3- [1,1-bis (4-diethylamino-phenyl) ethylene-2-yl] -6-dimethylamino phthalide leuco dye having absorption in the infrared region, such as de, and the like. Among these, 2-anilino-3-methyl-6-disubstituted such as 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di (n-butylamino) fluorane Aminofluorane, crystal violet lactone, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-1-yl) -4-azaphthalide has color tone and color-decoloring properties. It is preferable from the point. These may be used alone or mixed, and can be multicolored or full-colored by laminating layers that develop colors of different colors.

-Electron-accepting compound-
The electron-accepting compound is not particularly limited as long as it can reversibly develop and decolorize by using heat as a factor. (1) Color development for developing an electron-donating color-forming compound (color former) Having a function (for example, phenolic hydroxyl group, carboxylic acid group, phosphate group, etc.) and (2) a structure for controlling cohesion between molecules (for example, a structure in which long-chain hydrocarbon groups are linked). A compound having at least one structure in the molecule is preferred.
In addition, the linking part may be through a divalent or higher valent linking group containing a hetero atom, and the long chain hydrocarbon group contains at least one of the same linking group and aromatic group. Also good. Among these, it is particularly preferable to use a phenol compound having an alkyl chain having 8 or more carbon atoms represented by the following general formula (1), but is not limited thereto.

In the general formula (1), n represents an integer of 1 to 3.
R ¹ represents an optionally substituted aliphatic hydrocarbon group having 2 or more carbon atoms, preferably an aliphatic hydrocarbon group having 5 or more carbon atoms, more preferably an aliphatic hydrocarbon group having 10 or more carbon atoms. Group hydrocarbon group. R ² represents an aliphatic hydrocarbon group having 1 to 14 carbon atoms, and R ² has more preferably 8 to 14 carbon atoms. You may use these 1 type or in mixture of 2 or more types.
The aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. Examples of the substituent attached to the hydrocarbon group include a hydroxyl group, a halogen atom, and an alkoxy group.

When the sum of the carbon number of R ¹ and R ² is 7 or less, the stability of color development and the decoloring property are lowered. Therefore, the carbon number is preferably 8 or more, and more preferably 11 or more.
X represents a divalent group containing an N atom or an O atom, preferably an amide group or a urea group, and more preferably a urea group.

  The electron-accepting compound (developer) is used in the process of forming a decolored state by using a compound having at least one -NHCO- group or -OCONH- group in the molecule as a decoloring accelerator. It is preferable because an intermolecular interaction is induced between the decolorization accelerator and the developer, and the color development and decoloring characteristics are improved. There is no restriction | limiting in particular as said decoloring accelerator, According to the objective, it can select suitably, For example, the compound represented by following General formula (2)-(8) etc. are preferable.

In the general formulas (2) to (8), R ¹ , R ² , and R ⁴ represent a linear alkyl group, a branched alkyl group, or an unsaturated alkyl group having 7 to 22 carbon atoms. R ³ represents a divalent functional group having 1 to 10 carbon atoms. R ⁵ represents a trivalent functional group having 4 to 10 carbon atoms.
The mixing ratio of the electron-donating color-forming compound (color former) and the electron-accepting compound (developer) varies in an appropriate range depending on the combination of the compounds to be used, but cannot be generally specified. The ratio of the developer to the color former 1 is preferably from 0.1 to 20, and more preferably from 0.2 to 10. Even if the amount of the developer is less or more than this preferred range, the density of the colored state is lowered, which causes a problem.
Moreover, when adding the said decoloring accelerator, 0.1-300 mass% is preferable with respect to a color developer, and 3-100 mass% is more preferable. The color former and the developer can be used in a microcapsule.

  In the color developing layer, a binder resin and, if necessary, various additives for improving and controlling the coating characteristics and color erasing characteristics of the color developing layer can be used. Examples of these additives include a surfactant, a conductive agent, a filler, an antioxidant, a light stabilizer, a color developing stabilizer, and a decoloring accelerator.

-Binder resin-
The binder resin is not particularly limited as long as the heat-sensitive layer can be bound on the support, and can be appropriately selected depending on the purpose. One or more kinds of conventionally known resins can be selected. Can be mixed and used. Among these, in order to improve durability at the time of repetition, a resin curable by heat, ultraviolet rays, electron beams, or the like is preferably used, and a thermosetting resin using an isocyanate compound or the like as a crosslinking agent is particularly preferable. . As the thermosetting resin, for example, the same resin as the binder resin used in the anti-curl layer can be suitably used.

The mixing ratio (mass ratio) of the color former and the binder resin in the heat sensitive layer is preferably 0.1 to 10 with respect to the color former 1. If the amount of the binder resin is too small, the thermal strength of the heat-sensitive layer may be insufficient. On the other hand, if the amount of the binder resin is too large, the color density may be lowered, causing a problem.
When the heat sensitive layer is crosslinked, the gel fraction of the heat sensitive layer is preferably 30% or more, more preferably 50% or more, and still more preferably 70% or more. When the gel fraction is less than 30%, the crosslinked state is not sufficient and the durability may be inferior.

There is no restriction | limiting in particular as said crosslinking agent, According to the objective, it can select suitably, For example, an isocyanate type hardening | curing agent etc. are suitable. About this isocyanate type hardening | curing agent, the hardening | curing agent used by the said back layer can be used.
As a method for distinguishing whether the binder resin is in a crosslinked state or in a non-crosslinked state, for example, it can be distinguished by immersing the coating film in a highly soluble solvent. That is, the binder resin in the non-crosslinked state is dissolved in the solvent and does not remain in the solute.

  The coating Tg of the heat sensitive layer is desirably 100 ° C. or higher. In the process of repeatedly performing erasure printing by heat, if the coating film Tg is less than 100 ° C., the durability will be insufficient due to the thermal history and stress of erasure printing, resulting in unerased residue and uneven color development. Problems such as peeling off will occur. If the temperature is 100 ° C. or higher, the strength of the film is increased, the color development characteristics and the color erasing characteristics are stabilized, the occurrence of unerased residue is reduced, color development unevenness is eliminated, and the film is not peeled off. The coating film Tg is more preferably 120 ° C. or higher. When the coating film Tg is 120 ° C. or higher, the coating film strength is further increased, and the color development characteristics and decoloring characteristics are further stabilized.

The other components in the heat-sensitive layer are not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include surfactants and plasticizers from the viewpoint of facilitating image formation. The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. It is done.

The plasticizer is not particularly limited and may be appropriately selected depending on the purpose. For example, phosphoric acid ester, fatty acid ester, phthalic acid ester, dibasic acid ester, glycol, polyester plasticizer, epoxy plasticizer Agents, etc.
As the solvent used in the heat-sensitive layer coating liquid, the coating liquid dispersion device, the heat-sensitive layer coating method, the drying / curing method, etc., known methods used in the anti-curl layer can be used.
In the heat-sensitive layer coating solution, each material may be dispersed in a solvent by using the dispersing device, or each material may be separately dispersed in a solvent and mixed. Further, it may be dissolved by heating and precipitated by rapid cooling or slow cooling.

  The method for forming the heat-sensitive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) the resin, the electron-donating color-forming compound, and the electron-accepting compound are contained in a solvent. A method in which a coating solution for a heat-sensitive layer dissolved or dispersed in is coated on a support, and the solvent is evaporated to form a sheet or the like, or at the same time or thereafter, (2) a solvent in which only the resin is dissolved A method in which a coating solution for a heat-sensitive layer in which the electron-donating color-forming compound and the electron-accepting compound are dispersed is applied on a support, and the solvent is evaporated to form a sheet or the like, or at the same time or thereafter, 3) A method in which the resin, the electron-donating coloring compound and the electron-accepting compound are heated and melted and mixed with each other without using a solvent, and the molten mixture is formed into a sheet or the like and cooled and then crosslinked. Etc. That. In these, a sheet-like thermoreversible recording medium can be formed without using the support.

The solvent used in (1) or (2) varies depending on the type of the resin and the electron-donating color-forming compound and the electron-accepting compound, and cannot be defined unconditionally. For example, tetrahydrofuran, methyl ethyl ketone, Examples include methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene, and the like.
The electron-accepting compound is dispersed in the form of particles in the heat-sensitive layer.

Various pigments, antifoaming agents, pigments, dispersants, slip agents, preservatives, cross-linking agents, plasticizers, etc. are added to the coating solution for the heat sensitive layer for the purpose of developing high performance as a coating material. May be.
There is no restriction | limiting in particular as the coating method of the said heat sensitive layer, According to the objective, it can select suitably, Conveys the support body cut | judged by roll shape continuously or in sheet form, and on this support body For example, blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating, die coating, etc. Apply by the method.

There is no restriction | limiting in particular as drying conditions of the said coating liquid for heat sensitive layers, According to the objective, it can select suitably, For example, about 10 minutes-about 1 hour at the temperature of room temperature-140 degreeC etc. are mentioned.
The resin in the heat-sensitive layer can be cured by heating, ultraviolet irradiation, electron beam irradiation, or the like. As a method for curing by these means, specifically, curing is performed by reacting an acrylic copolymer (acrylic resin) with a polyisocyanate compound.

There is no restriction | limiting in particular in the film thickness of the said thermosensitive layer, According to the objective, it can select suitably, For example, 1-20 micrometers is preferable and 3-15 micrometers is more preferable.
If the thickness of the heat-sensitive layer is too thin, the color density will be low and the contrast of the image may be low. On the other hand, if it is too thick, the heat distribution in the layer will be large and the color will not reach the color temperature and will not color May occur, making it impossible to obtain a desired color density.
The solvent used in the heat-sensitive layer coating liquid, the coating liquid dispersion device, the intermediate layer coating method, the intermediate layer drying / curing method, and the like are known methods used in the anti-curl layer and antistatic layer. Can be used.

In addition to the thermosensitive layer, the thermoreversible recording medium of the present invention is further appropriately selected as necessary, such as an intermediate layer, an ultraviolet shielding layer, an under layer, an anchor coat layer, a barrier layer, a photothermal conversion layer, a colored layer, air Other layers such as a layer, a light reflection layer, an adhesive layer, an intermediate layer, a protective layer, an adhesive layer, an adhesive layer, and a binder layer may be included. Each of these layers may have a single layer structure or a laminated structure.
FIG. 1 is a cross-sectional view showing an example of an embodiment of a thermoreversible recording medium according to the present invention. As shown in FIG. 1A, a heat-sensitive layer 12 and a protective layer 11 are provided on a support 10, and an anti-curl layer 14 and a charge are formed on the surface of the support 10 opposite to the surface on which the heat-sensitive layer 12 is provided. A prevention layer 15 is provided.
FIG. 1B is a cross-sectional view showing another example. As shown in FIG.1 (b), the surface in which the heat sensitive layer 12, the intermediate | middle layer 18, and the protective layer 11 were provided through the under layer 17 on the support body 10, and the heat sensitive layer 12 of the support body 10 was provided. An anti-curl layer 14 and an antistatic layer 15 are provided on the opposite surface.
FIG. 1C is a cross-sectional view showing still another example. As shown in FIG. 1C, the two supports 10 and 20 are bonded to each other via the RF tag 1 and the bonding member 21 so that the coated surface becomes the surface.
On the support 10, a heat sensitive layer 12, an intermediate layer 18, and a protective layer 11 are laminated in this order. The other support 20 is provided with an anti-curl layer 14 and an anti-static layer 15.

<Under layer>
The under layer effectively uses the applied heat to increase the sensitivity, or for the purpose of improving the adhesion between the support and the heat sensitive layer or preventing the heat sensitive layer material from penetrating into the support. It is provided between the supports, contains at least hollow particles, and contains a binder resin and, if necessary, other components.
Examples of the hollow particles include single hollow particles in which one hollow portion is present in the particles, and multi-hollow particles in which many hollow portions are present in the particles. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as a material of the said hollow particle, Although it can select suitably according to the objective, For example, a thermoplastic resin etc. are mentioned suitably. The void particles may be appropriately manufactured or may be commercially available products. Examples of the commercially available products include Microsphere R-300 (manufactured by Matsumoto Yushi Co., Ltd.), Ropaque HP1055, Ropaque HP433J (all manufactured by Nippon Zeon Co., Ltd.), SX866 (manufactured by JSR Corporation), and the like.

There is no restriction | limiting in particular in the addition amount in the said under layer of the said hollow particle, According to the objective, it can select suitably, For example, 10-80 mass% is preferable.
As the binder resin, the same resin as the anti-curl layer and the anti-static layer can be used.
The under layer may contain at least one of inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin, and talc, and various organic fillers.
In addition, the under layer may further contain a lubricant, a surfactant, a dispersant, and the like.

There is no restriction | limiting in particular in the film thickness of the said under, and it can select suitably according to the objective, 0.1-50 micrometers is preferable, 2-30 micrometers is more preferable, 3-24 micrometers is still more preferable.
The solvent used in the under layer coating liquid, the coating liquid dispersing device, the intermediate layer coating method, the intermediate layer drying / curing method, and the like are known methods used in the anti-curl layer and antistatic layer. Can be used.

<Intermediate layer>
In the thermoreversible recording medium, an intermediate layer can be provided between the protective layer and the heat-sensitive layer for the purpose of protecting the heat-sensitive layer from the solvent or monomer component of the protective layer forming liquid.
As the material for the intermediate layer, known resin materials mentioned as the material for the binder resin in the anti-curl layer can be used.
The intermediate layer preferably contains an ultraviolet absorber. As the ultraviolet absorber, any of organic and inorganic compounds can be used.

Examples of the organic ultraviolet absorber include benzotriazole-based, benzophenone-based, salicylic acid ester-based, cyanoacrylate-based, and cinnamic acid-based ultraviolet absorbers, with benzotriazole-based being preferred. Among these, those in which a hydroxyl group is protected by an adjacent bulky functional group are particularly preferable, and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2- (2 '-Hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole and the like are preferable. A skeleton having such an ultraviolet absorbing ability may be pendant to a copolymerized polymer such as an acrylic resin or a styrene resin.
As for content of the said organic type ultraviolet absorber, 0.5-10 mass% is preferable with respect to the resin component total mass of the said intermediate | middle layer.

  As the inorganic ultraviolet absorber, a metal compound having an average particle size of 100 nm or less is suitable. For example, zinc oxide, indium oxide, alumina, silica, zirconia, tin oxide, cerium oxide, iron oxide, antimony oxide, Barium oxide, calcium oxide, barium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, manganese oxide, tantalum oxide, niobium oxide, thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite, titanic acid Metal oxides such as barium and potassium titanate or composite oxides thereof, zinc sulfide, metal sulfides or sulfate compounds such as barium sulfate, titanium carbide, silicon carbide, molybdenum carbide, tungsten carbide, tantalum carbide Metal carbides, such as carbide, aluminum nitride, silicon nitride, boron nitride, zirconium nitride, vanadium nitride, titanium nitride, niobium nitride, and metal nitrides such as gallium nitride. Among these, metal oxide ultrafine particles are preferable, and silica, alumina, zinc oxide, titanium oxide, and cerium oxide are more preferable. These can also be treated with silicone, wax, organosilane, silica or the like on the surface.

The content of the inorganic ultraviolet absorber is preferably in the range of 1 to 95% in terms of volume fraction. These organic and inorganic ultraviolet absorbers may be contained in the heat sensitive layer.
The thickness of the intermediate layer is preferably 0.1 to 20 μm, and more preferably 0.5 to 5 μm. The solvent used for the intermediate layer coating solution, the dispersion device for the coating solution, the intermediate layer coating method, the intermediate layer drying / curing method, etc., are known methods used in the anti-curl layer and antistatic layer. Can be used.

The thermoreversible recording medium can be provided with a color printing layer. Examples of the colorant in the color printing layer include various dyes and pigments contained in color inks used in conventional full color printing. Examples of the resin binder include various thermoplastic, thermosetting, ultraviolet curable, and electron beam curable resins. Since the thickness of the color printing layer is appropriately changed with respect to the printing color density, it can be selected according to the desired printing color density.
In order to enable laser recording, a photothermal conversion layer that absorbs laser light and converts light energy into heat energy may be provided between the support and the heat sensitive layer.

  The thermoreversible recording medium of the present invention can be processed into a desired shape according to the application, for example, processed into a card shape, a sheet shape, a roll shape, or the like. In the present invention, it is particularly preferred that the sheet size is larger than the card size and smaller than the A5 size, or from A5 size to A4 or A3 size.

  The thermoreversible recording medium of the present invention may be used in combination with an irreversible thermosensitive layer. In this case, the color tone of each heat sensitive layer may be the same or different. In addition, printing such as offset printing, gravure printing, or inkjet printer, thermal transfer printer, sublimation printer, etc. on a part or the whole surface of the thermosensitive layer of the thermoreversible recording medium of the present invention or a part of the opposite surface. A colored layer with an arbitrary pattern may be provided, and an OP varnish layer mainly composed of a curable resin may be provided on a part or the entire surface of the colored layer. Examples of the arbitrary pattern include characters, patterns, patterns, photographs, information detected by infrared rays, and the like. It is also possible to add a dye or pigment to any one of the simply configured layers for coloring.

  Further, the thermoreversible recording medium of the present invention can be provided with a hologram for security. In addition, a design such as a person image, a company emblem, a symbol mark, or the like can be provided by providing irregularities in a relief shape or an intaglio shape for designability.

Formation and deletion of an image on the thermoreversible recording medium can be performed using a known image processing apparatus.
Suitable examples of the image processing apparatus include an image forming unit for forming an image on the thermoreversible recording medium and an image erasing unit for erasing the image. Specifically, an image processing apparatus that can process an image by using a thermal head and changing the energy applied to the thermal head, or the image forming means is a thermal head or a laser, and the image erasing means is a thermal head. , Ceramic heaters (heating elements with heat-generating resistors screen-printed on an alumina substrate), contact stamping means for bonding heating elements such as hot stamps, heat rollers, heat blocks, heat bars, or hot air, infrared rays, lasers, etc. An image processing device selected from one of the non-contact type means used may be mentioned.
FIG. 2 is a diagram showing an embodiment of the image processing apparatus 40 according to the present invention. As shown in FIG. 2, the image processing apparatus 40 according to this embodiment erases an image formed on the thermoreversible recording medium and an image forming unit 41 for heating the thermoreversible recording medium to form an image. And an image forming unit 42. Further, an RF-ID reader / writer 46, a thermoreversible recording medium 44, and a stacker 45 are provided. Reference numeral 43 denotes a transport path.

-Thermoreversible recording member-
The thermoreversible recording member preferably has the heat-sensitive layer capable of reversible display and the information recording unit, and these are integrated. Part or all of the stored information of the information recording unit can be displayed on the heat sensitive layer, and information on the recording member can be confirmed without a special device. Further, when the contents of the information storage unit are rewritten, the display of the recording unit of the thermoreversible recording medium is rewritten so that the thermoreversible recording medium can be used repeatedly.
The information storage unit is not particularly limited. For example, a magnetic recording layer, a magnetic stripe, an IC memory, an optical memory, an RF tag, or the like is preferably used. In particular, an RF tag that can rewrite information without contact is more preferable.

As shown in FIG. 3, the RF tag 1 includes an IC chip 2 and an antenna 3 connected to the IC chip, and the IC chip 2 and the antenna 3 are provided on a support or the like. The IC chip 2 includes at least a storage unit, a transmission unit, a reception unit, and a power supply rectification unit. The RF tag 1 is classified into an electromagnetic induction method and a radio wave method. In the electromagnetic induction method, a range of 135 kHz or lower and 13.56 MH
The frequency band of z is used, and the UHF band and microwave are used in the electric field method.
Examples of a method for integrating the thermoreversible recording medium and the RF tag include a method in which the RF tag is attached to a part of the thermoreversible recording medium and a method in which the thermoreversible recording medium is incorporated in the thermoreversible recording medium.

When the FR tag is pasted, it may be pasted anywhere as long as it is a part of the thermoreversible recording medium. The method of affixing can be affixed with a general pressure-sensitive adhesive or adhesive.
When the RF tag is incorporated in the inside of the thermal recording medium, the RF tag is sandwiched between a support member made of at least a protective layer and a heat-sensitive layer and at least one support member made of at least an anti-curl layer and an antistatic layer through a member. An indentation configuration is preferred. The bonding member in this case is not particularly limited as long as the supports can be bonded to each other, but a general film or resin may be used, or a general adhesive or adhesive may be used for bonding. A general hot melt agent may be used. When a hot melt agent is used, the RF tag can be sandwiched between the previous supports and processed by applying pressure or heat.

Various forms of thermoreversible recording media, such as card tags that are smaller than that, are used for apparel applications, product tags, etc. Applications for point cards, prepaid cards, and games and games are also included. A Kanban size larger than the card size can be suitably used for process management and physical distribution management, and a sheet size larger than A5 can be used for general documents, process management instructions, and the like. Furthermore, since no dust or dust is generated, it can be used in a clean room or the like.

  FIG. 4 shows an example of how to use an industrial rewritable sheet combining the thermoreversible recording medium (rewritable sheet) of the present invention and an RF-ID tag. First, information such as an article name and quantity is recorded on a sheet and an RF-ID tag with respect to delivered raw materials, and attached to a returnable box or the like for inspection. In the next process, a processing instruction is given to the delivered raw material, information is recorded in the rewritable sheet and the RF-ID tag, and a processing instruction document is obtained, and the process proceeds to the processing process. Next, the processed product is attached with a rewritable sheet on which ordering information is recorded as an ordering instruction and an RF-ID tag. After the product is shipped, the rewritable sheet is collected, the shipping information is read, and used again as an invoice.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example at all. Examples 2, 3, 5, and 6 are missing numbers.
Example 1
-Production of thermoreversible recording media-
(1) Support body A white polyester film having a thickness of 125 μm (manufactured by Teijin DuPont Co., Ltd., Tetron film U2L98W) was used as the support body.
(2) Thermal layer-Preparation of coating solution for thermal layer-
3 parts by weight of a developer represented by the following structural formula, 1 part by weight of a dialkylurea (manufactured by Nippon Kasei Co., Ltd., Haclean SB), a 50% by weight solution of an acrylic polyol (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 69, molecular weight: (30000, glass transition temperature: 80 ° C.) 9 parts by mass and 70 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was about 1 μm.

Next, 1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane and an isocyanate curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate 2094) were added to the dispersion obtained by pulverizing and dispersing the developer. 9 parts by mass was added and stirred well to prepare a thermosensitive layer coating solution.
Next, the obtained heat-sensitive layer coating solution was applied onto the support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 11 μm. A heat sensitive layer was formed.
It was 100 degreeC when the coating film Tg of the obtained heat sensitive layer was measured with the rigid pendulum.

(3) Protective layer-Adjustment of protective layer coating solution-
50 parts by mass of a polymer having an ultraviolet absorbing structure (Nippon Shokubai Co., Ltd., G-100, hydroxyl value: 22) 20 parts by mass, filler (Mizusawa Chemical Co., Ltd., P-526) 4 parts by mass, silicone polymer (Nippon Yushi) 1 part by mass, FS700) and 30 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was 3 to 4 μm.
Next, 2 parts by mass of an isocyanate-based curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate HX) was added to the dispersion and stirred well to prepare a coating solution for a protective layer.
Next, the obtained coating solution for the protective layer was applied onto the heat-sensitive layer using a wire bar, dried at 100 ° C. for 1 minute, and then cured at 60 ° C. for 24 hours to form a protective layer having a thickness of about 3 μm. Formed.

(4) Anti-curl layer-Adjustment of anti-curl layer coating solution-
5 parts by mass of polyester polyol (Dainippon Ink Co., Ltd., Bernock D-161, hydroxyl value: 170) is dissolved in 34 parts by mass of methyl ethyl ketone, and 7 parts by mass of an isocyanate curing agent (Mitsui Takeda Chemical Co., Ltd., D-160N) is added. In addition, the mixture was well stirred to prepare an anti-curl layer coating solution.
Next, the anti-curl layer coating solution obtained on the non-coated side of the support having the heat-sensitive layer and the protective layer coated thereon was applied with a wire bar, dried at 90 ° C. for 1 minute, Curing was carried out at a temperature of 24 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 110 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.

(5) Antistatic layer-Adjustment of antistatic layer coating solution-
Acrylic polyol 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 108, molecular weight: 65000, glass transition temperature: 80 ° C.) 14 parts by mass, filler (Mizusawa Chemical Co., Ltd., P-526) 2 parts by mass, and methyl ethyl ketone 23 parts by mass was pulverized and dispersed using a ball mill so that the average particle size was 3 to 4 μm.

Next, 30 parts by weight of a transparent conductive agent (manufactured by Ishihara Sangyo Co., Ltd., SNS-10M, solid content 30% by mass, 50% particle size = 0.115 ± 0.015 μm, configuration = antimony-doped tin oxide, shape: spherical) In addition, the mixture was well stirred to prepare an antistatic layer coating solution.
Next, an antistatic layer coating solution is applied onto the anti-curl layer with a wire bar, dried at 90 ° C. for 1 minute, and cured at 60 ° C. for 24 hours to form an antistatic layer of about 3 μm. A thermoreversible recording medium was prepared.

( Reference Example 1 )
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
-Preparation of coating solution for heat sensitive layer-
6 parts by weight of the developer used in Example 1, 2 parts by weight of a dialkylurea (manufactured by Nippon Kasei Co., Ltd., Haclean SB), a 50% by weight solution of polyester polyol (manufactured by Dainippon Ink, Inc., Bernock 11-408, hydroxyl value) : 200) 10 parts by mass and 200 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was about 1 μm.

Next, 2 parts by mass of 2-anilino-3-methyl-6dibutylaminofluorane and an isocyanate curing agent (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-160N) were added to the dispersion obtained by pulverizing and dispersing the developer. 8 parts by mass was added and stirred well to prepare a thermosensitive layer coating solution.
Next, the obtained heat-sensitive layer coating solution was applied onto the support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 11 μm. A heat sensitive layer was formed.
It was 130 degreeC when the coating film Tg of the obtained heat sensitive layer was measured with the rigid pendulum.

-Adjustment of coating solution for protective layer-
40 parts by mass of a polymer having an ultraviolet absorption structure (Otsuka Chemical Co., Ltd., PUVA-60MK-40K, hydroxyl value: 60) 23 parts by mass, filler (Mizusawa Chemical Co., Ltd., P-526) 4 parts by mass, silicone polymer 1 part by mass (manufactured by Nippon Oil & Fats Co., Ltd., FS700) and 30 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was 3 to 4 μm.
Next, 2 parts by mass of an isocyanate curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate HX) was added to the dispersion and stirred well to prepare a coating solution for a protective layer.

Next, the obtained coating solution for the protective layer was applied onto the heat-sensitive layer using a wire bar, dried at 100 ° C. for 1 minute, and then cured at 60 ° C. for 24 hours to form a protective layer having a thickness of about 3 μm. Formed.
―Preparation of anti-curl coating solution―
5 parts by mass of polyester polyol (Dainippon Ink Co., Ltd., Bernock D-161, hydroxyl value: 170) is dissolved in 34 parts by mass of methyl ethyl ketone, and 4 parts by mass of an isocyanate curing agent (Nihon Polyurethane Co., Ltd., Coronate 2094) is added. An anti-curl layer coating solution was prepared by stirring.
Next, the anti-curl layer coating solution obtained on the surface of the support on which the heat-sensitive layer and the protective layer have been coated is applied with a wire bar, dried at 90 ° C. for 1 minute, Curing was carried out at a temperature of 24 ° C. for 24 hours to form an anti-curl layer having a thickness of about 7 μm.
It was 95 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.

-Adjustment of antistatic layer coating solution-
A conductive whisker (Otsuka Chemical Co., Ltd.) was dissolved in 50 parts by weight of an acrylic polyol (Mitsubishi Rayon Co., Ltd., hydroxyl value: 108, molecular weight: 65000, glass transition temperature: 80 ° C.) in 14 parts by weight of methyl ethyl ketone. DENTOR WK-200, major axis = 10-20 μm, minor axis = 0.4-0.7 μm, composition: K ₂ O.nTiO ₂ / SnO ₂ Sb ₂ O ₆ ) An antistatic layer coating solution was prepared.
Next, an antistatic layer coating solution is applied onto the anti-curl layer with a wire bar, dried at 90 ° C. for 1 minute, and cured at 60 ° C. for 24 hours to form an antistatic layer of about 3 μm. A thermoreversible recording medium was prepared.

( Reference Example 2 )
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
-Preparation of coating solution for heat sensitive layer-
The developer represented by the following structural formula: 3.5 parts by mass, 1.5 parts by mass of dialkylurea (manufactured by Nippon Kasei Co., Ltd., Haclean SB), 50% by mass solution of acrylic polyol (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 69) , Molecular weight: 30000, glass transition temperature: 80 ° C.) 12 parts by mass and methyl ethyl ketone 150 parts by mass were pulverized and dispersed using a ball mill until the average particle size was about 1 μm.

Next, 1.5 parts by mass of 2-anilino-3-methyl-6dibutylaminofluorane and an isocyanate curing agent (Nihon Polyurethane Co., Ltd., Coronate HX) were added to the dispersion obtained by pulverizing and dispersing the developer. 1.5 parts by mass was added and stirred well to prepare a thermosensitive layer coating solution.
Next, the obtained heat-sensitive layer coating solution was applied onto the support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 12 μm. A heat sensitive layer was formed.
It was 140 degreeC when the coating film Tg of the obtained heat sensitive layer was measured with the rigid pendulum.

-Preparation of coating solution for intermediate layer-
Acrylic polyol resin 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 108, molecular weight: 65000, glass transition temperature: 80 ° C.) 3 parts by mass, zinc oxide fine particle 30 mass% dispersion (Sumitomo Cement Co., Ltd., ZS303 ) 7 parts by mass, 1.5 parts by mass of an isocyanate-based curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) and 7 parts by mass of methyl ethyl ketone were added and stirred well to prepare an intermediate layer coating solution.
Next, the heat-sensitive layer is applied onto the support, and the intermediate layer coating solution is applied with a wire bar, heated and dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 2 hours to obtain a film thickness of about A 2 μm intermediate layer was formed.

-Preparation of coating solution for protective layer-
3 parts by mass of pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), 3 parts by mass of urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-3320HA), acrylic ester of dipentaerythritol caprolactone ( Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 3 parts by mass, silica (Mizusawa Chemical Co., Ltd., P-526) 1 part by mass, photopolymerization initiator (Ciba Geigy Japan, Irgacure 184) 0.5 Part by mass and 11 parts by mass of isopropyl alcohol were added, and the mixture was well stirred by a ball mill and dispersed so that the average particle size was about 3 μm to prepare a coating solution for a protective layer.

Next, the heat-sensitive layer and the intermediate layer are coated on the support, and the coating solution for the protective layer is coated with a wire bar, dried at 90 ° C. for 1 minute, and then crosslinked with an 80 W / cm ultraviolet lamp. As a result, a protective layer having a thickness of about 4 μm was formed.
―Preparation of anti-curl coating solution―
A polyester polyol 70 mass% solution (Dainippon Ink Co., Ltd., Bernock 11-408, hydroxyl value: 200) 8.5 mass parts is melt | dissolved in methyl ethyl ketone 38 mass parts, and isocyanate type hardening | curing agent (Nippon Polyurethane Co., Ltd. coronate 2094). An anti-curl layer coating solution was prepared by adding 5.5 parts by mass and stirring well.
Next, apply the anti-curl layer coating solution obtained on the uncoated side of the support with the heat-sensitive layer, intermediate layer and protective layer applied, and dry at 90 ° C. for 1 minute. Thereafter, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 120 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.

-Adjustment of antistatic layer coating solution-
Pentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., KAYARAD DPHA) 7.5 parts by mass, dipentaerythritol caprolactone acrylic acid ester (Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 2.5 parts by mass, needle-shaped Conductive titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., FT-1000, long axis = 1.68 μm, short axis = 0.13 μm, constitution: titanium oxide coated with antimony-doped tin oxide) 2.5 parts by mass, photopolymerization initiator (Nippon Ciba Geigy Co., Ltd., Irgacure 184) 0.5 parts by mass and 13 parts by mass of isopropyl alcohol were added, and the mixture was well stirred in a ball mill to prepare a coating solution for a back layer.
Next, an antistatic layer coating solution is applied onto the anticurl layer with a wire bar, heated and dried at 90 ° C. for 1 minute, and then crosslinked with an 80 W / cm ultraviolet lamp to form a film having a thickness of about 4 μm. A prevention layer was formed to produce a thermoreversible recording medium.

Example 4
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
-Preparation of coating solution for heat sensitive layer-
3 parts by weight of the developer used in Reference Example 2 , 1 part by weight of a dialkylurea (manufactured by Nippon Kasei Co., Ltd., Haclean SB), a 70% by weight polyester polyol solution (manufactured by Dainippon Ink, 11-408, hydroxyl value: 200) 6 parts by mass and 100 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle diameter was about 1 μm.

Next, 1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane and 3 parts by mass of an isocyanate curing agent (Nihon Polyurethane Co., Ltd., Coronate HX) were added to the dispersion obtained by pulverizing and dispersing the developer. Was added and stirred well to prepare a thermosensitive layer coating solution.
Next, the obtained heat-sensitive layer coating solution was applied onto the support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 12 μm. A heat sensitive layer was formed.
It was 140 degreeC when the coating film Tg of the obtained heat sensitive layer was measured with the rigid pendulum.
Next, in the same manner as in Reference Example 2 , an intermediate layer and a protective layer were provided on the thermosensitive layer.

―Preparation of anti-curl coating solution―
7 parts by mass of a polyester polyol (Nippon Polyurethane, Nipponporan 800, hydroxyl value: 290) is dissolved in 48 parts by mass of methyl ethyl ketone, and 7.2 parts by mass of an isocyanate curing agent (Nihon Polyurethane, Coronate HX) is added and stirred well. Thus, an anti-curl layer coating solution was prepared.
Next, apply the anti-curl layer coating solution obtained on the uncoated side of the support with the heat-sensitive layer, intermediate layer and protective layer applied, and dry at 90 ° C. for 1 minute. Thereafter, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 150 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.
-Adjustment of antistatic layer coating solution-
In Reference Example 2 , the acicular conductive filler of the antistatic layer coating solution is acicular conductive titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., FT-2000, major axis = 2.86 μm, minor axis = 0.21 μm, configuration: antimony An antistatic layer was formed in the same manner with 2.5 parts by mass of titanium oxide coated with doped tin oxide) to prepare a thermoreversible recording medium.

( Reference Example 3 )
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
-Preparation of coating solution for heat sensitive layer-
3.5 parts by weight of the developer used in Reference Example 2 , 1 part by weight of dialkylurea (manufactured by Nippon Kasei Co., Ltd., Haclean SB), 50% by weight solution of acrylic polyol (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 108, 10 parts by mass (molecular weight: 65000, glass transition temperature: 80 ° C.) and 100 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was about 1 μm.

Next, 1.5 parts by mass of 2-anilino-3-methyl-6dibutylaminofluorane and an isocyanate curing agent (Nihon Polyurethane Co., Ltd., Coronate HX) 3 were added to the dispersion obtained by pulverizing and dispersing the developer. A mass part was added and stirred well to prepare a coating solution for the thermosensitive layer.
Next, the obtained heat-sensitive layer coating solution was applied onto the support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 12 μm. A heat sensitive layer was formed.
It was 145 degreeC when the coating film Tg of the obtained heat sensitive layer was measured with the rigid pendulum.
Next, in the same manner as in Reference Example 2 , an intermediate layer and a protective layer were provided on the thermosensitive layer.

―Preparation of anti-curl coating solution―
10 mass parts of acrylic polyol 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 69, molecular weight: 30000, glass transition temperature: 80 ° C.) is dissolved in 10 mass parts of methyl ethyl ketone, and an isocyanate curing agent (Mitsui Takeda Chemical, D -160N) 2.8 parts by mass was added and stirred well to prepare an anti-curl layer coating solution.

Next, apply the anti-curl layer coating solution obtained on the uncoated side of the support with the heat-sensitive layer, intermediate layer and protective layer applied, and dry at 90 ° C. for 1 minute. Thereafter, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 130 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum. -Adjustment of antistatic layer coating solution-
In Reference Example 2 , the acicular conductive filler of the antistatic layer coating solution is acicular conductive titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., FT-3000, major axis = 5.15 μm, minor axis = 0.27 μm, configuration: antimony An antistatic layer was formed in the same manner with 2.5 parts by mass of titanium oxide coated with doped tin oxide) to prepare a thermoreversible recording medium.

( Reference Example 4 )
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
-Preparation of coating solution for heat sensitive layer-
6 parts by weight of the developer used in Reference Example 2 , 2 parts by weight of dialkylurea (manufactured by Nippon Kasei Co., Ltd., Haclean SB), 50% by weight solution of acrylic polyol (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 10 mass parts (109000, glass transition temperature: 35 ° C.) and 100 mass parts of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was about 1 μm.

Next, 2 parts by mass of 2-anilino-3-methyl-6dibutylaminofluorane and 8 parts by mass of an isocyanate curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) were added to the dispersion obtained by pulverizing and dispersing the developer. Was added and stirred well to prepare a thermosensitive layer coating solution.
Next, the obtained heat-sensitive layer coating solution was applied onto the support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 12 μm. A heat sensitive layer was formed.
It was 150 degreeC when the coating film Tg of the obtained heat sensitive layer was measured with the rigid pendulum.
Next, in the same manner as in Reference Example 2 , an intermediate layer and a protective layer were provided on the thermosensitive layer.

―Preparation of anti-curl coating solution―
10 parts by mass of 50% by weight acrylic polyol solution (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 109000, glass transition temperature: 35 ° C.)
It melt | dissolved in the mass part, 8 mass parts of isocyanate type hardening | curing agents (The Nippon Polyurethane company make, Coronate HL) were added, and it was made to stir well, and prepared the anti-curl layer coating liquid.

Next, apply the anti-curl layer coating solution obtained on the uncoated side of the support with the heat-sensitive layer, intermediate layer and protective layer applied, and dry at 90 ° C. for 1 minute. Thereafter, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 150 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.
Next, in the same manner as in Reference Example 3 , an antistatic layer was provided on the anticurl layer to produce a thermoreversible recording medium.

(Example 7)
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
-Production of under layer-
30 parts by mass of a styrene-butadiene copolymer (manufactured by Nippon A & L Co., PA-9159), 12 parts by mass of a polyvinyl alcohol resin (manufactured by Kuraray Co., Ltd., Poval PVA103), hollow particles (manufactured by Matsumoto Yushi Co., Ltd., Microsphere R) -300) 20 parts by mass and 40 parts by mass of water were added and stirred for about 1 hour until a uniform state was obtained to prepare an under layer coating solution.
Next, the obtained under layer coating solution was applied onto the support with a wire bar and dried by heating at 80 ° C. for 2 minutes to form an under layer having a thickness of 20 μm.

Next, the heat-sensitive layer used in Example 3 was provided on the under layer, and an intermediate layer and a protective layer were further provided thereon as in Reference Example 2 .
―Preparation of anti-curl coating solution―
An acrylic polyol 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 109000, glass transition temperature: 35 ° C.) 11 parts by mass is dissolved in 10 parts by mass of methyl ethyl ketone, and an isocyanate curing agent (manufactured by Nippon Polyurethane Co. Coronate HX) 4 parts by mass was added and stirred well to prepare an anti-curl layer coating solution.

Next, the anti-curl layer coating solution obtained on the uncoated side of the support with the under layer, heat-sensitive layer, intermediate layer and protective layer applied was applied with a wire bar at 90 ° C. After drying for 1 minute, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 165 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.
Next, in the same manner as in Reference Example 3 , an antistatic layer was provided on the anticurl layer to produce a thermoreversible recording medium.

(Example 8)
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
In the same manner as in Example 7, an under layer, a recording layer, an intermediate layer, and a protective layer were provided on the support. ―Preparation of anti-curl coating solution―
An acrylic polyol 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 109000, glass transition temperature: 35 ° C.) 10.4 parts by mass is dissolved in 30 parts by mass of methyl ethyl ketone, and an isocyanate curing agent (Nippon Polyurethane). An anti-curl layer coating solution was prepared by adding 8 parts by mass of Coronate L) and stirring well.

Next, the anti-curl layer coating solution obtained on the uncoated side of the support with the under layer, heat-sensitive layer, intermediate layer and protective layer applied was applied with a wire bar at 90 ° C. After drying for 1 minute, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 180 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.
Next, in the same manner as in Reference Example 3 , an antistatic layer was provided on the anticurl layer to produce a thermoreversible recording medium.

Example 9
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
An under layer was provided in the same manner as in Example 7, and a heat-sensitive layer and an intermediate layer similar to those in Reference Example 3 were provided thereon.

-Adjustment of coating solution for protective layer-
Acrylic polyol 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 109000, glass transition temperature: 35 ° C.) 10.4 mass parts, filler (Mizusawa Chemical Co., Ltd., P-526) 4 mass parts, 1 part by mass of silicone polymer (manufactured by NOF Corporation, FS700) and 30 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so as to have an average particle size of 3 to 4 μm.
Next, 8 parts by mass of an isocyanate-based curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate L) was added to the dispersion and stirred well to prepare a coating solution for a protective layer.
Next, the obtained coating solution for the protective layer was applied onto the heat-sensitive layer using a wire bar, dried at 100 ° C. for 1 minute, and then cured at 60 ° C. for 24 hours to form a protective layer having a thickness of about 3 μm. Formed.

―Preparation of anti-curl coating solution―
Polyester polyol 70 mass% solution (Takeda Pharmaceutical Co., Ltd., Takelac U-21, hydroxyl value: 350) 5 mass parts is dissolved in methyl ethyl ketone 34 mass parts, isocyanate type curing agent (Nippon Polyurethane Co., Ltd., Coronate HL) 10 mass An anti-curl layer coating solution was prepared by adding portions and stirring well.
Next, the anti-curl layer coating solution obtained on the uncoated side of the support with the under layer, heat-sensitive layer, intermediate layer and protective layer applied was applied with a wire bar at 90 ° C. After drying for 1 minute, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.

It was 155 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum. -Adjustment of antistatic layer coating solution-
10.4 parts by mass of acrylic polyol 50% by mass solution (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 109000, glass transition temperature: 35 ° C.) is dissolved in 23 parts by mass of methyl ethyl ketone, and acicular conductive titanium oxide (Ishihara Sangyo Co., Ltd., FT-3000, long axis = 5.15 μm, short axis = 0.27 μm, constitution: titanium oxide coated with antimony-doped tin oxide) 4 parts by mass, isocyanate curing agent (manufactured by Nippon Polyurethane, Coronate L) 8 parts by mass was added and stirred well to prepare an antistatic layer coating solution.
Next, an antistatic layer coating solution is applied onto the anti-curl layer with a wire bar, dried at 90 ° C. for 1 minute, and cured at 60 ° C. for 24 hours to form an antistatic layer of about 3 μm. A thermoreversible recording medium was prepared.

(Example 10)
-Production of thermoreversible recording media-
The same support as that used in Example 1 is used.
An under layer, a heat-sensitive layer, an intermediate layer, and a protective layer were provided in the same manner as in Example 7, and an anti-curl layer was provided on the non-coated surface of the support in the same manner as in Example 7.

-Adjustment of antistatic layer coating solution-
Pentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., KAYARAD DPHA) 7.5 parts by mass, dipentaerythritol caprolactone acrylic acid ester (Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 2.5 parts by mass, filler ( 2 parts by mass of P-526) manufactured by Mizusawa Chemical Co., Ltd. and 23 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill so that the average particle size was 3 to 4 μm.

Next, 30 parts by weight of a transparent conductive agent (manufactured by Ishihara Sangyo Co., Ltd., SNS-10M, solid content 30% by mass, 50% particle size = 0.115 ± 0.015 μm, configuration = antimony-doped tin oxide, shape: spherical) In addition, the mixture was well stirred to prepare an antistatic layer coating solution.
Next, an antistatic layer coating solution is applied onto the anticurl layer with a wire bar, heated and dried at 90 ° C. for 1 minute, and then crosslinked with an 80 W / cm ultraviolet lamp to form a film having a thickness of about 3 μm. A prevention layer was formed to produce a thermoreversible recording medium.

(Example 11)
-Production of thermoreversible recording media-
Two white polyester films (Lumirror E20, manufactured by Toray Industries, Inc.) having a thickness of 100 μm were used as the support.
One support was provided with an under layer, a heat-sensitive layer, an intermediate layer, and a protective layer in the same manner as in Example 7.
The other support was provided with an anti-curl layer and an antistatic layer in the same manner as in Example 7.
A hot-melt sheet is stacked between the two unsupported surfaces of the above two supports so that the RF tag is sandwiched from both surfaces, and is laminated by heating at 1 Kg / cm ² , 130 ° C. for 10 seconds, and then thermoreversible recording medium. It was created.

(Example 12)
A thermoreversible recording medium was prepared in the same configuration except that the protective layer having the following configuration was used in Example 7.
-Preparation of coating solution for protective layer-
3 parts by mass of pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), 3 parts by mass of urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-3320HA), acrylic ester of dipentaerythritol caprolactone ( Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 3 parts by mass, photopolymerization initiator (Nippon Ciba Geigy, Irgacure 184) 0.5 parts by mass, acicular conductive titanium oxide (Ishihara Sangyo Co., Ltd., FT -2000, major axis = 2.86 μm, minor axis = 0.21 μm, composition: 2.5 parts by mass of antimony-doped tin oxide-coated titanium oxide) and 11 parts by mass of isopropyl alcohol, and stirred well for protective layer A coating solution was prepared.
Next, the heat-sensitive layer and the intermediate layer are coated on the support, and the coating solution for the protective layer is coated with a wire bar, dried at 90 ° C. for 1 minute, and then crosslinked with an 80 W / cm ultraviolet lamp. Thus, a protective layer having a thickness of about 3 μm was formed.

(Example 13)
A thermoreversible recording medium was prepared in the same configuration except that the anti-curl layer having the following configuration was used in Example 7.
―Preparation of anti-curl coating solution―
11 parts by mass of 50% by mass acrylic polyol solution (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl value: 200, molecular weight: 109000, glass transition temperature: 35 ° C.)
Dissolve in parts by mass, add 4 parts by mass of filler (manufactured by Fuji Talc Kogyo Co., Ltd., LMS-300) and 4 parts by mass of isocyanate curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate HX) and stir well to prepare an anti-curl layer coating solution. Prepared.

Next, the anti-curl layer coating solution obtained on the uncoated side of the support with the under layer, heat-sensitive layer, intermediate layer and protective layer applied was applied with a wire bar at 90 ° C. After drying for 1 minute, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 6 μm.
It was 165 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.

(Comparative Example 1)
In Example 7, an anti-curl layer was not provided, an under layer, a heat-sensitive layer, an intermediate layer, and a protective layer were provided on the support, and an anti-static layer was provided on the uncoated surface of the support. Created.

(Comparative Example 2)
In Example 9, an antistatic layer was not provided, an under layer, a heat-sensitive layer, an intermediate layer, and a protective layer were provided on the support, and an anti-curl layer shown below was provided on the non-coated surface of the support to achieve thermoreversibility. A recording medium was created.
-Anti-curling layer-
Acrylic polyol 50 mass% solution (Mitsubishi Rayon Co., Ltd., hydroxyl value: 108, molecular weight: 65000, glass transition temperature: 80 ° C.) 10 parts by mass, filler (manufactured by Mizusawa Chemical Co., Ltd.,
P-526) 4 parts by mass and 100 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill to an average particle size of 4 to 5 μm.

Next, 3 parts by mass of an isocyanate-based curing agent (manufactured by Nippon Polyurethane Co., Ltd., Coronate HX) was added to the above dispersion and stirred well to prepare a coating solution for an anti-curl layer.
Next, the anti-curl layer coating solution obtained on the uncoated side of the support with the under layer, heat-sensitive layer, intermediate layer and protective layer applied was applied with a wire bar at 90 ° C. After drying for 1 minute, curing was performed at 60 ° C. for 24 hours to form an anti-curl layer having a thickness of about 8 μm.
It was 145 degreeC when the coating film Tg of the obtained anti-curl layer was measured with the rigid pendulum.

(Comparative Example 3)
In Example 7, an antistatic layer was not provided, an under layer, a heat-sensitive layer, an intermediate layer, and a protective layer were provided on the support, and the anti-curl layer used in Comparative Example 2 was provided on the uncoated surface of the support. A thermoreversible recording medium was prepared.

(Comparative Example 4)
In Example 7, the anti-curl layer and the antistatic layer were changed as follows.
-Anti-curling layer-
A curl prevention layer solution is prepared by thoroughly stirring 8.5 parts by mass of acrylic resin (Mitsubishi Rayon, BR80, Tg: 105 ° C.), spherical PMMA filler (manufactured by Soken Chemical Co., Ltd., average particle size 12 μm), and 90 parts by mass of methyl ethyl ketone. Created.

Next, the anti-curl layer coating solution obtained on the uncoated side of the support with the under layer, heat-sensitive layer, intermediate layer and protective layer applied was applied with a wire bar at 90 ° C. An anti-curl layer having a film thickness of about 5 μm was formed by drying for 1 minute.
-Antistatic layer-
An antistatic layer solution was prepared by thoroughly stirring 10 parts by mass of α-ethyl (trimethylammonium) alkanoyl ester (Nippon Pure Chemicals, SAT-5) and 90 parts by mass of methyl ethyl ketone.
Next, it is coated on the anti-curl layer with a wire bar, dried at 90 ° C. for 1 minute, and then 40 ° C.
Was cured for 24 hours to form an antistatic layer of about 2 μm, and a thermoreversible recording medium was prepared.

<Evaluation>
Repeated erasure printing test, curling under low temperature environment and high temperature environment for the thermoreversible recording media of Examples 1, 4, 7 to 13, Reference Examples 1 to 4 and Comparative Examples 1 to 4 thus prepared Test, surface resistance value and sticking test in low temperature and low humidity environment, curl test and stackability test in low temperature environment and high temperature environment.
Repeated erasure printing test using rewritable printer for sheet A rewritable sheet printer (SX-8) manufactured by Toshiba Tec Corporation was used as the printer. The printer includes a paper feed stacker, a paper feed unit, an erasing unit, and a printing unit. The erasing unit includes a heat roller, and the printing unit includes a thermal head. The conveyance speed was 75 mm / sec.

100 sheets of each thermoreversible recording medium were set in a paper feed stacker, conveyed one by one, the recorded image was erased by the erasing unit, and the image was printed by the printing unit. After printing all 100 stacked thermal recording media, the reusable thermoreversible recording media were stacked and erased and printed, and this was repeated 300 times.
Then, it was placed on a horizontal surface in a room temperature environment, and the state in which the four corners of the thermoreversible recording medium were curled was measured with a straight scale, and an average value was obtained. The curl property was determined based on the following evaluation criteria.

〔Evaluation criteria〕
A curl is 3 mm or less.

  ○: The curl is larger than 3 mm and not larger than 5 mm.

  Δ: The curl is larger than 5 mm and not larger than 10 mm.

X: The curl is larger than 10 mm.
Curling test under environment The thermoreversible recording medium printed 10 times with the above printer is put in a large constant temperature and constant temperature and humidity chamber, -10 ° C 40% RH environment, 5 ° C 30% RH environment, 50 ° C 90% RH environment It was left for 24 hours. Thereafter, the sample was placed on a horizontal surface under each environment, and the state in which the four corners of the thermoreversible recording medium were curled was measured with a straight scale, and an average value was obtained. The curl under the environment was determined based on the same evaluation criteria as the repeated durability evaluation.

Transportability test under environment A rewritable printer was set in a large constant temperature, constant temperature and humidity chamber, and a transportability test was conducted in a -10 ° C 40% RH environment and a 40 ° C 90% RH environment. 100 sheets of each thermoreversible recording medium were set in a paper feed stacker, and the durability was repeated 300 times.
The transportability of the thermoreversible recording medium was confirmed during repeated erasure print tests in each environment. The transportability was determined as follows.

“Excellent”: No conveyance failure or double feeding of the thermoreversible recording medium occurred during the test.
“Yes”: No double feed occurs, but the printed image is misaligned.
“Multifeed failure”: A thermoreversible recording medium is stuck, and double feed causes a conveyance failure.
“Paper feed failure”: The thermoreversible recording medium cannot be fed from the stacker to the conveyance path, and clogging occurs.

Stackability test With respect to the number of thermoreversible recording media that have not been erased and printed in a room temperature environment, the number of sheets that can be stacked and set in a stacker is the room temperature environment after 300 times of durability, and −10 The number of sheets when a thermoreversible recording medium is stacked in a 40 ° C. RH environment and a 50 ° C. and 90% RH environment is compared.
The stackability at that time was determined as follows.
“Excellent”: The difference is 5 or less with respect to the initial stack number.
“Yes”: The difference is 10 or less with respect to the initial stack number.
“No”: The difference exceeds 10 on the initial stack.

From the above results, it can be seen that the occurrence of curling in the thermoreversible recording media of Examples 1, 4 , and 7 to 13 in which repeated erasure printing was performed 300 times is significantly reduced. On the other hand, in Comparative Examples 1-4, it turns out that curl is large.
When carrying out large-scale batch feeding of 100 sheets or more, if the curl changes and becomes larger due to repeated erasing printing, the thickness when the thermoreversible recording media are stacked on the printer stacker due to the curl will also be different, This may cause a conveyance failure in the printer. However, Examples 1 to 13 do not have the problem.

From the above results, it can be seen that Examples 1, 4, and 7 to 13 have little curling variation even in an environment of 50 ° C. from curling in a low temperature environment of −10 ° C.
On the other hand, it can be seen that in Comparative Examples 1 to 4, the heat-sensitive layer surface is greatly curled in a low temperature environment of −10 ° C., and the heat-sensitive layer surface is curled in a high temperature environment of 50 ° C.

From the above results, it can be seen that Examples 1 , 4 , and 7 to 13 are excellent in printer transportability from a low temperature and low humidity environment to a high temperature and high humidity environment.
On the other hand, in Comparative Examples 1-4, the conveyance defect and the double feed defect have occurred. The double feed failure in the low temperature and low humidity environment was caused by the fact that the thermoreversible recording medium was charged and static electricity was generated when it was repeated several times, and the medium was stuck due to the influence. Further, the conveyance failure has occurred due to the fact that the curl of the medium cannot be picked up at the time of paper feeding. In high-temperature and high-humidity environments, many conveyance failures occurred due to curling.
In the embodiment, there is no problem described above.

From the above results, it can be seen that in Examples 1 , 4 , and 7 to 13 , after being used repeatedly 300 times, the printer is excellent in stackability in a low-temperature and low-humidity environment and a high-temperature and high-humidity environment.
On the other hand, in Comparative Examples 1 to 4, it can be seen that the stacking property is deteriorated because the number of thermoreversible recording media that can be stacked with respect to the initial time is reduced.

It is sectional drawing which shows one Embodiment of the thermoreversible recording medium based on this invention. It is a figure which shows an example of an image processing apparatus. It is the schematic which shows an example of RF tag. It is the schematic which shows the usage method of a thermoreversible recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Support body 11 Protective layer 12 Heat sensitive layer 14 Anti-curl layer 15 Antistatic layer

Claims (21)

A support, a heat-sensitive layer color depending on the temperature on the support varies reversibly, provided at least one or more protective layers on the heat-sensitive layer, the heat-sensitive layer of the support is only set An anti-curl layer comprising at least one layer is provided on the opposite side of the surface, an anti-static layer is provided on the anti-curl layer, the heat sensitive layer and the resin species constituting the anti-curl layer, and the protective layer; The resin type constituting the antistatic layer is
Same der respectively is, the coating Tg of the heat-sensitive layer and the anti-curl layer is at 100 ° C. or higher, the heat reversible recording the coating Tg curl prevention layer may be higher 10 ° C. or higher than the coating Tg of the heat-sensitive layer Medium. A heat-sensitive layer composed of two or more supports bonded so that the coated surface becomes a surface, and the color tone reversibly changes depending on temperature on the coated surface of one of the supports, and the heat-sensitive layer At least one protective layer is provided on the surface, and an anti-curl layer comprising at least one layer is provided on the coated surface of the other support, and an antistatic layer is provided on the anti-curl layer. resin species constituting the layer, and the resin species constituting the protective layer and the antistatic layer are the same der respectively is, the coating Tg of the heat-sensitive layer and the anti-curl layer is not less 100 ° C. or more, the curl prevention layer A thermoreversible recording medium, wherein the coating film Tg is 10 ° C. or more higher than the coating film Tg of the thermosensitive layer .   The thermoreversible recording medium according to claim 1 or 2, wherein the resin species constituting the thermosensitive layer and the anti-curl layer is a thermosetting resin.   The thermoreversible recording medium according to claim 3, wherein the thermosetting resin is cured with an isocyanate curing agent. The thermoreversible recording medium according to any one of claims 1 to 4 , wherein a resin species constituting the protective layer and the antistatic layer is a thermosetting resin or an ultraviolet curable resin. The thermoreversible recording medium according to any one of claims 1 to 5 , wherein the antistatic layer contains an acicular conductive filler. The thermoreversible recording medium according to claim 6, wherein the acicular conductive filler has a major axis of 1 μm to 10 μm and a minor axis of 0.1 μm to 0.5 μm. The thermoreversible recording medium according to claim 6 or 7, wherein the acicular conductive filler is obtained by surface-treating acicular crystals with a conductive agent. The thermoreversible recording medium according to any one of claims 6 to 8 , wherein the acicular conductive filler is titanium oxide coated with antimony-doped tin oxide. 10. The thermoreversible recording medium according to claim 1, wherein the surface resistance value of the outermost layer on the surface of the antistatic layer is 1 × 10 ¹¹ Ω / □ or less. A thermoreversible recording member comprising an information storage unit and a reversible display unit, wherein the reversible display unit includes the thermoreversible recording medium according to any one of claims 1 to 10 . The thermoreversible recording member according to claim 11 , wherein the information storage unit and the reversible display unit are integrated. The thermoreversible recording member according to claim 11 or 12 , wherein the information recording unit is selected from a magnetic recording layer, a magnetic stripe, an IC memory, an optical memory, and an RF tag. Thermoreversible recording member according to claim 11 having a printable part 13. At least an image forming unit that heats a thermoreversible recording medium to form an image on the thermoreversible recording medium, and an image erasing unit that heats the thermoreversible recording medium to erase an image formed on the thermoreversible recording medium. An image processing apparatus comprising: the thermoreversible recording medium according to any one of claims 1 to 10 . The image processing apparatus according to claim 15 , wherein the image forming unit is either a thermal head or a laser irradiation apparatus. The image processing apparatus according to claim 15 or 16 , wherein the image erasing unit is any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, a heat bar, and a laser irradiation apparatus. At least one of heating the thermoreversible recording medium to form an image on the thermoreversible recording medium and erasing the image formed on the thermoreversible recording medium by heating the thermoreversible recording medium. An image processing method, wherein the thermoreversible recording medium is the thermoreversible recording medium according to any one of claims 1 to 10 . The image processing method according to claim 18 , wherein the image is formed using either a thermal head or a laser irradiation device. The image processing method according to claim 18 or 19 , wherein the image is erased using any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, a heat bar, and a laser irradiation apparatus. The image processing method according to any one of claims 18 20 for forming a new image while erasing the image using the thermal head.