JP2008179132A - Image processing method, and image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing method and an image processing apparatus which can shorten the periods of time for an image recording and erasing, and can expand the recording region and erasing region. <P>SOLUTION: This image processing method includes at least either one of an image recording process and an image erasing process. In this case, in the image recording process, an image is recorded on a heat reversible recording medium by heating the heat reversible recording medium by the irradiation with a laser beam. In this case, either one of the transparency and the color tone of the heat reversible recording medium reversibly changes depending on a temperature. In the image erasing process, the image which has been recorded on the heat reversible recording medium is erased by heating the heat reversible recording medium. In at least either one of the image recording process and the image erasing process, the heat reversible recording medium is arranged at a position being farther than the focal position of the laser beam, and at least either one of the image recording and the image erasing is performed by the image processing method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention can shorten the recording and erasing time and can expand the recording area and the erasing area, and is particularly suitable for a large area thermoreversible recording medium, a moving body, a physical distribution / distribution system, and the like. The present invention relates to an image processing method and an image processing apparatus that can be suitably used for the image processing method.

To date, image recording and image erasing on a thermoreversible recording medium (hereinafter sometimes simply referred to as “recording medium” or “medium”) are performed by contacting a heating source with the recording medium to heat the medium. Has been done in the formula. As the heat source, a thermal head is usually used for image recording, and a heat roller, a ceramic heater, or the like is used for image erasing.
In such a contact-type recording method, when the thermoreversible recording medium is a flexible material such as a film or paper, uniform image recording and recording can be performed by pressing the recording medium uniformly against a heating source with a platen or the like. There is an advantage that image erasing can be performed and an image recording apparatus and an image erasing apparatus can be manufactured at low cost by diverting components of a conventional thermal paper printer.
However, when the thermoreversible recording medium incorporates an RF-ID tag or the like as described in Patent Document 1 and Patent Document 2, the thickness of the thermoreversible recording medium increases and flexibility decreases. Therefore, a high pressure is required to uniformly press the heating source. Further, when irregularities occur on the surface of the thermoreversible recording medium, it becomes difficult to record and erase images using a thermal head or the like. Furthermore, while reading and rewriting of stored information is performed from where the RF-ID tag is separated without contact, there is a demand for rewriting the image from a distant position on the thermoreversible recording medium.
Therefore, a recording method using a non-contact type laser has been proposed as a method for recording and erasing an image on a recording medium when the surface of the thermoreversible recording medium has irregularities or from a distance. .

As a recording method using such a laser, a laser recording device (laser marker) capable of irradiating a thermoreversible recording medium with a high-power laser beam and controlling its position is provided. Using this laser marker, it is possible to perform recording and erasing by irradiating a thermoreversible recording medium with laser light, the medium absorbing the light and converting it into heat, and changing the phase with the heat.
When performing image recording using the laser marker, the laser beam is usually condensed and recorded at a focal position where the energy density is the highest, but the spot diameter of the laser beam is the smallest at the focal position, and the focal point is recorded. When a character is recorded at a position, it is constituted by a thin line, so visibility may be insufficient. In addition, when erasing an image with laser light, the spot diameter of the laser light is small at the focal position, so if there is a position shift, unerased residue may occur. When scanning with light, there is a problem that it takes time to erase an image.

In order to solve the above problem, for example, in Patent Documents 3 and 4, the spot diameter of the laser beam is enlarged using a mirror. Moreover, in patent document 5, the spot diameter of a laser beam is expanded by adjusting the distance between a concave lens and a convex lens. However, since these devices are equipped with spot diameter changing means in the laser recording apparatus, the laser recording apparatus becomes large and expensive. Patent Documents 4 and 5 are laser markers that directly record a lot number, a model number, or the like on a workpiece such as metal or plastic.
In Patent Document 3, when the laser beam is scanned using a scanning mirror, the spot diameter is enlarged by disposing the thermoreversible recording medium closer to the focal position. When performing recording and erasing, the scanning distance of the scanning mirror becomes longer than when performing recording and erasing at the focal position, and recording and erasing take time. In addition, when the thermoreversible recording medium is arranged closer to the focal position, there is a problem that the recording area and the erasing area are narrowed.

JP 2004-265247 A JP 2004-265249 A JP 2002-347272 A JP 2003-161907 A JP 2000-71088 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention can perform high-density uniform image recording and uniform image erasure on the entire drawing line including the start point, end point, overlap portion, and straight line portion constituting the image. An object of the present invention is to provide an image processing method that can reduce damage caused by repeated erasing and prevent deterioration of the thermoreversible recording medium and has a high heat dissipation effect, and an image processing apparatus that can be suitably used for the image processing method.

Means for solving the problems are as follows. That is,
<1> Image recording step of recording an image on the thermoreversible recording medium by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature. And at least one of an image erasing step of erasing an image recorded on the thermoreversible recording medium by heating the thermoreversible recording medium,
In at least one of the image recording step and the image erasing step, the thermoreversible recording medium is disposed at a position far from the focal position of the laser beam, and at least one of image recording and image erasing is performed. This is an image processing method.
<2> The image processing method according to <1>, wherein the image erasing step is performed by irradiating and heating the thermoreversible recording medium with a laser beam.
<3> Where the distance from the condenser lens to the focal position is X, and the distance from the condenser lens to the thermoreversible recording medium is Y, the following expression Y / X = 1.02 to 2.0 is satisfied: The image processing method according to any one of <1> to <2>.
<4> When the spot diameter of the laser beam at the focal position is A and the spot diameter of the laser beam on the thermoreversible recording medium is B, the above formula <1> satisfying the following formula, B / A = 1.5 to 76: > To <3>.
<5> The image processing method according to any one of <1> to <4>, which is used for image recording and image erasure of a moving body.
<6> The thermoreversible recording medium has at least a thermoreversible recording layer on a support, and the thermoreversible recording layer has a first specific temperature and a second specific temperature higher than the first specific temperature. The image processing method according to any one of <1> to <5>, wherein either the transparency or the color tone reversibly changes depending on the temperature.
<7> The thermoreversible recording medium has at least a reversible thermosensitive recording layer on a support, and the reversible thermosensitive recording layer contains a resin and a low molecular weight organic substance. The image processing method according to any one of the above.
<8> The thermoreversible recording medium has at least a reversible thermosensitive recording layer on a support, and the reversible thermosensitive recording layer contains a leuco dye and a reversible developer. > The image processing method according to any one of the above.
<9> In at least one of the image recording process and the image erasing process, in the intensity distribution of the irradiated laser light, the light irradiation intensity I _{1 at} the center position of the irradiated laser light and 80% of the total irradiation energy of the irradiated laser light The image processing method according to any one of <2> to <8>, wherein the light irradiation intensity I _{2 on the} surface satisfies the following formula: 0.40 ≦ I ₁ / I ₂ ≦ 2.00.
<10> Used in the image processing method according to any one of <1> to <9>,
Laser beam emitting means;
An image processing apparatus comprising at least light irradiation intensity adjusting means arranged on a laser light emitting surface of the laser light emitting means and changing the light irradiation intensity of the laser light.
<11> The image processing apparatus according to <10>, wherein the light irradiation intensity adjustment unit is at least one of a lens, a filter, a mask, a mirror, and a fiber coupling.

In the image processing method of the present invention, an image is formed on the thermoreversible recording medium by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature. Including at least one of an image recording step of recording, and an image erasing step of erasing an image recorded on the thermoreversible recording medium by heating the thermoreversible recording medium,
In at least one of the image recording step and the image erasing step, the thermoreversible recording medium is disposed at a position far from the focal position of the laser beam, and at least one of image recording and image erasing is performed. By disposing the thermoreversible recording medium at a position farther from the focal position of the laser beam and performing at least one of image recording and image erasing, recording and erasing is performed closer to the focal distance or at the focal position. Also, the scanning distance of the scanning mirror can be shortened, and the recording and erasing time can be shortened. Further, since the thermoreversible recording medium is disposed farther from the focal position, the recording area and the erasing area are enlarged.

The image processing apparatus of the present invention is used in the image processing method of the present invention, and is a laser beam emitting means, light disposed on the laser beam emitting surface of the laser beam emitting means, and light that changes the light irradiation intensity of the laser beam. And at least irradiation intensity adjusting means.
In the image processing apparatus, the laser beam emitting means emits a laser beam. The light irradiation intensity adjusting means changes the light irradiation intensity of the laser light emitted from the laser light emitting means. As a result, when an image is recorded on the thermoreversible recording medium, the recording and erasing time can be shortened, and the recording area and the erasing area can be enlarged.

  According to the present invention, the conventional problem can be solved, and the focal length is achieved by disposing the thermoreversible recording medium at a position far from the focal position of the laser beam and performing at least one of image recording and image erasing. An image processing method in which the scanning distance of the scanning mirror is shorter than when recording and erasing is performed closer or at a focal position, recording and erasing time can be shortened, and the recording area and erasing area can be enlarged. And an image processing apparatus that can be suitably used in the image processing method.

(Image processing method)
The image processing method of the present invention includes at least one of an image recording step and an image erasing step, and further includes other steps appropriately selected as necessary.
The image processing method of the present invention includes both an aspect in which both image recording and image erasing are performed, an aspect in which only image recording is performed, and an aspect in which only image erasing is performed.

<Image recording process and image erasing process>
In the image processing method of the present invention, the image recording step is performed by irradiating and heating a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature, This is a step of recording an image on a thermoreversible recording medium.
The image erasing step in the image processing method of the present invention is a step of erasing an image recorded on the thermoreversible recording medium by heating the thermoreversible recording medium.
By irradiating the thermoreversible recording medium with the laser beam and heating it, it is possible to record and erase images in a non-contact state with the thermoreversible recording medium.
In the image processing method of the present invention, the image is normally updated (the image erasing step) for the first time when the thermoreversible recording medium is reused, and then the image is recorded by the image recording step. The order of recording and erasing is not limited to this, and the image may be erased by the image erasing step after the image is recorded by the image recording step.
In the image processing method of the present invention, as will be described later, in at least one of the image forming step and the image erasing step, the thermoreversible recording medium is disposed at a position far from the focal position of the laser beam. It is sufficient that at least one of image recording and image erasing is performed, and in the image forming step, the thermoreversible recording medium is disposed at a position far from the focal position of the laser beam, and image recording is performed. In the image erasing step, the thermoreversible recording medium may not be disposed at a position far from the focal position of the laser beam, and a heat source other than the laser beam may be used. Among the heat sources, when heating by irradiating laser light, it takes time to scan and irradiate the entire predetermined area with one laser light. It is preferable to erase by heating using a heat roller, hot stamp, dryer or the like. Further, when the thermoreversible recording medium is mounted on a foamed polystyrene box as a transport container for use in a distribution line, the foamed polystyrene box itself melts when heated, so that the thermoreversible recording medium is irradiated with a laser beam. It is preferable to erase only by locally heating only.
In the image erasing step, the thermoreversible recording medium is disposed at a position far from the focal position of the laser beam, and when erasing the image, the thermoreversible recording medium is moved to the laser beam in the image forming step. For example, a heat source other than a laser beam such as a thermal head may be used as the heat source.

Here, as shown in FIG. 1, the laser beam 103 emitted from the laser device 100 is condensed by the lens 105 and has the maximum energy density at the focal position 101. Therefore, when characters are recorded at the focal position 101, they are composed of thin lines, so that visibility may be insufficient. In addition, when erasing an image with laser light, the spot diameter of the laser light is small at the focal position, so if there is a misalignment, unerased residue may occur. When scanning, there is a problem that it takes time to erase.
FIG. 2 shows a case where the laser beam irradiated from the laser apparatus 100 is scanned with a scanning mirror within a predetermined recording range. In FIG. 2, a thermoreversible recording medium is disposed at a position 104 near the focal position 101, and when image recording and image erasing are performed at this position, scanning of the scanning mirror is performed more than when recording and erasing is performed at the focal position 101. The distance becomes long, and it takes time to record and erase. In addition, when the thermoreversible recording medium is arranged closer to the focal position, there is a problem that the recording area and the erasing area are narrowed.

  Therefore, in the image processing method of the present invention, in at least one of the image recording step and the image erasing step, the thermoreversible recording medium is disposed at a position farther from the focal position of the laser beam, and image recording and image Perform at least one of erasure. A thermoreversible recording medium may be disposed at a position farther than the focal position of the laser beam for only one of the image recording step and the image erasing step, but both the image recording step and the image erasing step are both It is preferable to dispose the thermoreversible recording medium at a position far from the focal position of the laser beam. As a result, the scanning distance of the scanning mirror becomes shorter than when recording and erasing is performed nearer to the focal distance and at the focal position, recording and erasing time can be shortened, and the recording area and erasing area can be enlarged. Can do.

Specifically, assuming that the distance from the condenser lens to the focal position is X and the distance from the condenser lens to the thermoreversible recording medium is Y, the following equation is satisfied: Y / X = 1.02-2.0 It is preferable that Y / X = 1.025 to 1.5. If Y / X is less than 1.02, the lines may become thin when characters are recorded, and the visibility may be insufficient. If it exceeds 2.0, it is necessary for heating to a certain temperature. If the scanning speed is slowed down to increase the laser output, increase the size of the apparatus, or heat to a certain temperature without increasing the laser output, it may take time for recording and erasing.
Regarding Y / X in the image recording step, it is preferable to satisfy Y / X = 1.02 to 1.2, and in the erasing step, it is preferable to satisfy Y / X = 1.05 to 2.0.
The distance Y from the laser light source to the thermoreversible recording medium is not particularly limited and can be appropriately selected according to the purpose, but is preferably 51 mm to 600 mm, and more preferably 52 mm to 450 mm.

In the present invention, if the spot diameter of the laser beam at the focal position is A and the spot diameter of the laser beam on the thermoreversible recording medium is B, the following formula, B / A = 1.5 to 76, It is preferable to satisfy, and B / A = 3.0 to 38 is more preferable. If the B / A is less than 1.5, the line may become thin when characters are recorded and the visibility may be insufficient. If the B / A exceeds 76, the laser output necessary for heating to a certain temperature may be required. When the scanning speed is slowed down to increase the size of the apparatus and to heat up to a certain temperature without increasing the laser output, it may take time to record and erase.
Further, the B / A in the image recording step preferably satisfies B / A = 1.5 to 20, and the erasing step preferably satisfies B / A = 3.0 to 76.
The spot diameter B of the laser beam on the thermoreversible recording medium is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.02 mm to 14.0 mm, and 0.06 mm to 7.0 mm. Is more preferable.
Here, in general, in the Gaussian distribution, which is the light intensity distribution of laser light, the diameter that is 1 / e ² of the center intensity is called the spot diameter (or spot size, beam diameter, etc.), In the present invention, the spot diameter is not the diameter that becomes 1 / e ² of the central intensity but the diameter that contains 86.5% of the total light quantity.

The method of disposing the thermoreversible recording medium at a position far from the focal position of the laser beam is not particularly limited and can be appropriately selected according to the purpose. For example, (1) the laser apparatus is fixed. Means for changing the position of the thermoreversible recording medium, (2) means for changing the position of the laser device while fixing the position of the thermoreversible recording medium, and (3) a combination of (1) and (2) above. (4) A method of extending the optical path of the laser beam by using an optical path extending mirror.
Examples of the means (1) for changing the position of the thermoreversible recording medium include a method of attaching the thermoreversible recording medium to the stage and moving the stage.
Examples of the means (2) for changing the position of the laser apparatus include a method of moving the stage by installing the laser apparatus on a stage.

  According to the image processing method of the present invention, the recording and erasing time can be shortened, and the recording area and the erasing area can be enlarged, so that a large area thermoreversible recording medium, a large bar code, a moving It can be used particularly suitably for body, distribution / delivery system and the like. For example, it is possible to record and erase images on the thermoreversible recording medium (thermoreversible recording label) while moving the cardboard placed on the belt conveyor, and it is not necessary to stop the line. Can be achieved. Further, the cardboard to which the thermoreversible recording label is attached can be reused as it is without peeling off the thermoreversible recording label, and the image can be erased and recorded again.

In the image processing method, in the light intensity distribution of the laser light irradiated in at least one of the image recording step and the image erasing step, the light irradiation intensity I _{1 at} the center position of the irradiation laser light and the irradiation laser light It is preferable that the light irradiation intensity I ₂ at the 80% plane of the total irradiation energy satisfies the following formula, 0.40 ≦ I ₁ / I ₂ ≦ 2.00.
Here, the center position of the irradiation laser light is a position that can be obtained by dividing the light irradiation intensity at each position and the sum of the products of the position coordinates by the total light irradiation intensity at each position, It can be shown by the following formula.
Σ (r _i × I _i ) / ΣI _i
However, r _i represents each position coordinate, I _i represents the light irradiation intensity at each position, and ΣI _i represents the total light irradiation intensity.
The total irradiation energy refers to the total energy of laser light irradiated on the thermoreversible recording medium.
Conventionally, when a pattern is formed using a laser, the light intensity distribution of the cross section orthogonal to the traveling direction (hereinafter referred to as “traveling direction”) in which the laser beam is scanned on the thermoreversible recording medium is a Gaussian distribution. Thus, the light irradiation intensity at the center of the light irradiation was extremely higher than that at the periphery. When the thermoreversible recording medium is irradiated with this Gaussian laser beam, the temperature in the central portion is excessively high, and when image formation and erasing are repeated, the portion deteriorates, and the number of repetitions decreases. When the laser irradiation energy is lowered so as not to raise the temperature of the part to a temperature that deteriorates, there is a problem that the size of the image is reduced, and the image contrast is lowered and image formation takes time.
Therefore, in the image processing method of the present invention, in the light intensity distribution of the cross section orthogonal to the traveling direction of the laser light irradiated in the image recording step, the light irradiation intensity at the central portion is higher than the peripheral portion as compared with the Gaussian distribution. By reducing the intensity of the light, the deterioration of the thermoreversible recording medium due to repeated image formation and erasure is suppressed, and the image contrast is repeated without reducing the image size. Improved durability.

Here, when the light intensity distribution of the irradiation laser light is divided so that it occupies 20% of the total energy in the horizontal plane orthogonal to the traveling direction and includes the maximum value of the light intensity, the light intensity in the horizontal plane is represented by I _2. Assuming that the light intensity at the center of the light intensity with respect to the irradiation laser light is I ₁ , the light intensity ratio I ₁ / I ₂ is 2.30 in the Gaussian distribution (normal distribution). Become.
The light intensity ratio I ₁ / I ₂ is preferably 0.40 or more, more preferably 0.50 or more, still more preferably 0.60 or more, and particularly preferably 0.70 or more. The light intensity ratio is preferably 2.00 or less, more preferably 1.90 or less, still more preferably 1.80 or less, and particularly preferably 1.70 or less.
In the present invention, the lower limit of the ratio I ₁ / I ₂ is preferably 0.40, more preferably 0.50, still more preferably 0.60, and particularly preferably 0.70. In the present invention, the upper limit of the ratio is preferably 2.00, more preferably 1.90, still more preferably 1.80, and particularly preferably 1.70.
When the ratio I ₁ / I ₂ exceeds 2.00, the light intensity at the center position becomes strong, excessive energy is added to the thermoreversible recording medium, and the thermoreversible recording medium deteriorates when repeated image recording is performed. Disappearance may occur. On the other hand, when the ratio I ₁ / I ₂ is less than 0.40, energy is not applied to the center position with respect to the peripheral portion, and when the image is recorded, the central portion of the line is not colored and the line is split into two. If the irradiation energy is increased so as to develop color at the center of the line, the light intensity at the peripheral part becomes too strong, and excessive energy is applied to the thermoreversible recording medium. The disappearance may occur in the peripheral portion due to deterioration of the thermoreversible recording medium.
Further, if the ratio I ₁ / I ₂ is greater than 1.59, the light irradiation intensity at the center position becomes a light intensity distribution that is strong with respect to the light irradiation intensity at the peripheral portion. The thickness of the drawing line can be changed without changing the irradiation distance by adjusting the irradiation power while suppressing the deterioration of the thermoreversible recording medium.

Examples of light intensity distribution curves when the intensity distribution of the laser light is changed are shown in FIGS. 3B to 3E. FIG. 3B shows a Gaussian distribution. In such a light intensity distribution with a strong light irradiation intensity at the center position, the I ₁ / I ₂ value becomes large (ratio I ₁ / I ₂ = 2.3 in the case of Gaussian distribution). . 3C, the ratio I ₁ / I ₂ is smaller than the light intensity distribution in FIG. 3B. In the light intensity distribution close to the top hat shape as shown in FIG. 3D, the ratio I ₁ / I ₂ is further smaller than the light intensity distribution in FIG. 3C. In the light intensity distribution in which the light irradiation intensity at the center position is weak and the light irradiation intensity in the peripheral part is strong as in FIG. 3E, the ratio I ₁ / I ₂ is further smaller than the light intensity distribution in FIG. 3D. Therefore, the ratio I ₁ / I ₂ represents the shape of the light irradiation intensity distribution of the laser light.
When the ratio I ₁ / I ₂ is 1.59 or less, the top hat shape or the light irradiation intensity at the center part has a weak intensity distribution with respect to the light irradiation intensity at the peripheral part.

  Here, the 80% surface of the total irradiation energy of the irradiation laser light indicates the light intensity at the surface when it becomes 80% of the total irradiation energy of the irradiation laser light. For example, as shown in FIG. Is measured with a high-power beam analyzer using a high-sensitivity pyroelectric camera, and the obtained light irradiation intensity is converted into a three-dimensional graph, and a plane parallel to the plane where Z = 0 is obtained. The horizontal plane when the light intensity distribution is divided so that 80% of the total irradiation energy surrounded by the plane of Z = 0 is included.

As a method for measuring the light intensity distribution of the laser beam, for example, when the laser beam is emitted from a semiconductor laser, a YAG laser or the like and has a wavelength in the near infrared region, a laser beam using a CCD or the like is used. This can be done using a profiler. In addition, for example, when the laser beam is emitted from a CO ₂ laser and has a wavelength in the far infrared region, the CCD cannot be used. Therefore, a combination of a beam splitter and a power meter, a highly sensitive pyroelectric camera It can be performed using a high power beam analyzer or the like.

The light intensity distribution of the laser light is determined from the Gaussian distribution by the light irradiation intensity I _{1 at} the center position of the irradiation laser light and the light irradiation intensity I ₂ at the 80% plane of the total irradiation energy of the irradiation laser light. There is no particular limitation on the method for changing the formula to satisfy 0.40 ≦ I ₁ / I ₂ ≦ 2.00, and it can be appropriately selected according to the purpose, but the light irradiation intensity adjusting means is preferably used. Can be used.
Suitable examples of the light irradiation intensity adjusting means include, but are not limited to, a lens, a filter, a mask, a mirror, and a fiber coupling. Among them, a lens with low energy loss is preferable, and as a lens, a kaleidoscope, an integrator, a beam homogenizer, an aspheric beam shaper (a combination of an intensity conversion lens and a phase correction lens), an aspheric element lens, a diffractive optical element, etc. are suitable. In particular, an aspheric element lens and a diffractive optical element are preferable.
When a filter, a mask, or the like is used, the light irradiation intensity can be adjusted by physically cutting the central portion of the laser beam. In the case of using a mirror, the light irradiation intensity can be adjusted by using a deformable mirror whose shape is mechanically changed in conjunction with a computer, a mirror having partially different reflectivity or surface irregularities, and the like.
In the case of a laser having an oscillation wavelength of near infrared or visible light, it is preferable to adjust the light irradiation intensity by fiber coupling. Examples of lasers having near-infrared and visible light oscillation wavelengths include semiconductor lasers and solid-state lasers.
The method for adjusting the light irradiation intensity by the light irradiation intensity adjusting means will be described in detail in the description of the image processing apparatus of the present invention to be described later.

There is no restriction | limiting in particular as an output of the laser beam irradiated in the said image recording process, Although it can select suitably according to the objective, 1W or more are preferable, 3W or more are more preferable, and 5W or more are still more preferable. If the output of the laser beam is less than 1 W, it takes time to record an image, and if an attempt is made to shorten the image recording time, the output is insufficient and a high-density image cannot be obtained. Moreover, there is no restriction | limiting in particular as an upper limit of the output of the said laser beam, Although it can select suitably according to the objective, 200W or less is preferable, 150W or less is more preferable, and 100W or less is still more preferable. If the output of the laser beam exceeds 200 W, the laser device may be increased in size.
There is no restriction | limiting in particular as scanning speed of the laser beam irradiated in the said image recording process, Although it can select suitably according to the objective, 300 mm / s or more is preferable, 500 mm / s or more is more preferable, 700 mm / s More preferably, s or more. If the scanning speed is less than 300 mm / s, it takes time to record an image. The upper limit of the scanning speed of the laser beam is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 15,000 mm / s or less, more preferably 10,000 mm / s or less, and 8 More preferably, it is 1,000 mm / s or less. If the scanning speed exceeds 15,000 mm / s, it is difficult to record a uniform image.
The spot diameter of the laser beam irradiated in the image recording step is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.02 mm or more, more preferably 0.1 mm or more, and 0.15 mm. The above is more preferable. The upper limit of the laser beam spot diameter is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 3.0 mm or less, more preferably 2.5 mm or less, and 2.0 mm or less. Further preferred.
If the spot diameter is small, the line width of the image becomes narrow, the contrast becomes small, and the visibility is lowered. Further, when the spot diameter is increased, the line width of the image is increased, adjacent lines are overlapped, and it is impossible to print small characters.
Further, the output of the laser beam irradiated in the image erasing step of erasing the image by irradiating the thermoreversible recording medium with laser light is not particularly limited and is appropriately selected according to the purpose. However, 5W or more is preferable, 7W or more is more preferable, and 10W or more is more preferable. If the output of the laser beam is less than 5 W, it takes a long time to erase the image. If an attempt is made to shorten the image erasing time, the output is insufficient and an image erasing failure occurs. Moreover, there is no restriction | limiting in particular as an upper limit of the output of the said laser beam, Although it can select suitably according to the objective, 200W or less is preferable, 150W or less is more preferable, and 100W or less is still more preferable. When the output of the laser beam exceeds 200 W, there is a risk of increasing the size of the laser device.
The scanning speed of the laser light irradiated in the image erasing process for erasing the image by irradiating the thermoreversible recording medium with laser light and heating is not particularly limited and may be appropriately selected according to the purpose. However, 100 mm / s or more is preferable, 200 mm / s or more is more preferable, and 300 mm / s or more is still more preferable. When the scanning speed is less than 100 mm / s, it takes time to erase the image. Moreover, there is no restriction | limiting in particular as an upper limit of the scanning speed of the said laser beam, Although it can select suitably according to the objective, 20,000 mm / s or less is preferable, 15,000 mm / s or less is more preferable, 10 More preferably, it is 1,000 mm / s or less. If the scanning speed exceeds 20,000 mm / s, it may be difficult to erase a uniform image.
The spot diameter of the laser light irradiated in the image erasing process for erasing the image by irradiating the thermoreversible recording medium with laser light and heating is not particularly limited and may be appropriately selected according to the purpose. However, 0.5 mm or more is preferable, 1.0 mm or more is more preferable, and 2.0 mm or more is more preferable. Moreover, there is no restriction | limiting in particular as an upper limit of the spot diameter of the said laser beam, Although it can select suitably according to the objective, 14.0 mm or less is preferable, 10.0 mm or less is more preferable, and 7.0 mm or less is preferable. Further preferred.
When the spot diameter is small, it takes time to erase the image. Further, when the spot diameter is increased, the output may be insufficient and an image erasing failure may occur.

<Image recording and erasing mechanism>
The image recording and image erasing mechanisms include an aspect in which the transparency changes reversibly depending on the temperature and an aspect in which the color tone changes reversibly depending on the temperature.
In the aspect in which the transparency changes reversibly, the organic low molecule in the thermoreversible recording medium is dispersed in particles in the resin, and the transparency is reversible by heat between a transparent state and a cloudy state. To change.
The visual recognition of the change in transparency results from the following phenomenon. That is, (1) in the transparent state, the organic low-molecular substance particles dispersed in the resin matrix and the resin matrix are in close contact with each other without any gap, and there are voids inside the particles. Therefore, the light incident from one side is transmitted to the opposite side without being scattered and looks transparent. On the other hand, in the case of (2) white turbidity, the particles of the low molecular weight organic substance are formed of fine crystals of the low molecular weight organic substance, and the interface between the crystal or the particle and the resin base material. A gap (gap) is generated, and light incident from one side is refracted and scattered at the interface between the gap and the crystal, or the interface between the gap and the resin, and thus appears white.

First, FIG. 4A shows a temperature-transparency of a thermoreversible recording medium having a reversible thermosensitive recording layer (hereinafter sometimes referred to as “recording layer”) in which the organic low molecular weight substance is dispersed in the resin. An example of a change curve is shown.
For example, the recording layer is in a cloudy opaque state (A) at room temperature of T ₀ or less. As you heat it, it begins to slowly clear from the temperature T _1, temperature T ₂ when heated to through T ₃ transparent (B), and the even again returned to the normal temperature of T ₀ or less in this state transparent (D ). This is because the resin shrinks, reduces interfacial, or voids within the particles of the resin and the organic low-molecular material particle as the resin from the vicinity of the temperature T ₁ is started to soften, softening proceeds, gradually At temperatures T _{2 to} T ₃ , the organic low molecular weight material is in a semi-molten state, and the remaining voids become transparent by filling the organic low molecular weight material, and the seed crystal remains cooled. Since the resin is still in a softened state at that time, the resin follows the change in particle deposition accompanying crystallization, the voids do not occur, and the transparent state is maintained. It is believed that there is.
Further heating to a temperature of T ₄ or higher results in a translucent state (C) intermediate between maximum transparency and maximum opacity. Next, when this temperature is lowered, the first white turbid opaque state (A) is restored without becoming transparent again. This is because after the organic low molecular weight substance is completely melted at a temperature T ₄ or higher, it becomes supercooled and crystallizes at a temperature slightly higher than T _{0. At} that time, the resin follows the volume change accompanying the crystallization. It is thought that this is because voids cannot be generated.
However, in the temperature-transparency change curve shown in FIG. 4A, when the type of the resin, the organic low-molecular substance, or the like is changed, the transparency of each state may change depending on the type.

Further, FIG. 4B shows a transparency changing mechanism of the thermoreversible recording medium in which the transparent state and the cloudy state are reversibly changed by heat.
In FIG. 4B, one long-chain low-molecular particle and its surrounding polymer are taken out, and the generation and disappearance change of voids accompanying heating and cooling are illustrated. In the cloudy state (A), voids are generated between the polymer and the low molecular particles (or inside the particles), and the light scattering state is obtained. When this is heated and exceeds the softening point (Ts) of the polymer, voids decrease and transparency increases. When further heated to near the melting point (Tm) of the low molecular particle, a part of the low molecular particle is melted, and due to the volume expansion of the melted low molecular particle, the void is filled with the low molecular particle. Disappears and becomes transparent (B). When cooled from here, the low-molecular particles crystallize immediately below the melting point, no voids are generated, and the transparent state (D) is maintained even at room temperature.
Next, when heated to the melting point of the low molecular particle or higher, the refractive index between the molten low molecular particle and the surrounding polymer is shifted, and a translucent state (C) is obtained. When cooled to room temperature from this point, the low molecular particles undergo a supercooling phenomenon and crystallize below the softening point of the polymer. At this time, the polymer is in a glass state, so the volume associated with the crystallization of the low molecular particles The surrounding polymer cannot follow the decrease, and voids are generated to return to the original cloudy state (A).
As described above, even if the organic low molecular weight substance is heated to an image erasing temperature before it is crystallized, the organic low molecular weight substance is in a molten state and thus is supercooled, and the resin is crystallized from the organic low molecular weight substance. It is considered that a cloudy state occurs because it cannot follow the volume change due to crystallization and voids are generated.

Next, in an aspect in which the color tone reversibly changes depending on the temperature, the organic low-molecular substance before melting is a leuco dye and a reversible developer (hereinafter sometimes referred to as “developer”). The low molecular weight organic substance after being melted and before crystallization is the leuco dye and the developer, and the color tone is reversibly changed by heat into a transparent state and a colored state. Change.
FIG. 5A shows an example of a temperature-color density change curve for a thermoreversible recording medium having a reversible thermosensitive recording layer containing the leuco dye and the developer in the resin, and FIG. The color development / decoloration mechanism of the thermoreversible recording medium in which the state and the color development state are reversibly changed by heat will be described.
First, when gradually heated the recording layer in First decolored state (A), at the melting temperature T _1, and the leuco dye and the color developer are mixed melt, molten color developed state caused color development ( B). When rapidly cooled from the melt color state (B), the color state can be lowered to room temperature, and the color state is stabilized and becomes a fixed color state (C). Whether or not this color development state has been obtained depends on the rate of temperature decrease from the melted state. In slow cooling, the color disappears in the process of temperature decrease, and the same color disappearance state (A) as the initial state or the color development state by rapid cooling ( The density is relatively lower than in C). On the other hand, when gradually raising the temperature again from the colored state (C), the color is erased at a lower temperature T ₂ than the coloring temperature (E from D), when the temperature is lowered from this state, the initial same decolorized state (A Return to).
The colored state (C) obtained by quenching from the molten state is a state in which the leuco dye and the developer are mixed in a state in which molecules can contact each other and form a solid state. There are many cases. In this state, the molten mixture of the leuco dye and the developer (the color mixture) crystallizes and maintains color development, and it is considered that the color development is stabilized by the formation of this structure. On the other hand, the decolored state is a state in which both phases are separated. This state is a state in which molecules of at least one compound aggregate to form a domain or crystallize, and the leuco dye and the developer are separated and stabilized by aggregation or crystallization. It is considered to be a state. In many cases, the color developer is crystallized as a result of phase separation between the two, thereby causing more complete color erasure.
Incidentally, it is shown in Figure 5A, decoloring by slow cooling from the molten state, and aggregate structure also T ₂ both decoloring change after heating from the colored state, the crystallization of the phase separation and the color developer is caused ing.
As described above, when the developer is melted and heated to an image erasing temperature before the formed color mixture formed with the leuco dye is crystallized, separation of the leuco dye and the developer is hindered. As a result, it is considered that the colored state is maintained.

The method for confirming that the organic low molecular weight substance is melted and in a state before crystallization, and the method for measuring the time until crystallization after the organic low molecular weight substance is melted are particularly limited. However, after recording a linear image, the linear image is recorded so as to overlap the linear image in a vertical direction after a predetermined time, and these intersections are erased. It can be done by judging whether or not. When the intersection is erased, it is recognized that the organic low molecular weight substance is crystallized.
The fact that the intersection portion is erased means that, for example, the image density of a linear image including the intersection portion is continuously measured using a Macbeth densitometer (RD914), and the transparency of the thermoreversible recording medium is reversible. In the changing aspect, the image density is 1.2 or more, and in the aspect in which the color tone of the thermoreversible recording medium is reversibly changed, the image density is 0.5 or less. In the aspect where the transparency of the thermoreversible recording medium reversibly changes, the measurement is performed with black paper (OD value = 2.0) on the back.
It is also possible to confirm whether the thermoreversible recording medium is crystallized by X-ray analysis. When the organic low molecular weight substance is crystallized, a unique crystal structure is shown according to the kind of the organic low molecular weight substance, and a scattering peak corresponding to the crystal structure can be detected by X-ray analysis. The scattering peak position can be easily confirmed by performing X-ray analysis of the organic low molecular weight substance alone. In addition, since it is possible to measure while changing the temperature depending on the X-ray analysis apparatus, it is possible to confirm the crystallization process of the organic low-molecular substance after heating and melting the organic low-molecular substance. it can.

[Thermal reversible recording medium]
The thermoreversible recording medium used in the image processing method of the present invention comprises at least a support and a reversible thermosensitive recording layer, and further appropriately selected as necessary, a protective layer, an intermediate layer, an under layer. It has other layers such as a coat layer, a back layer, a light-to-heat conversion layer, an adhesive layer, an adhesive layer, a colored layer, an air layer, and a light reflection layer. Each of these layers may have a single layer structure or a laminated structure.

-Support-
The support is not particularly limited in shape, structure, size and the like, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, May have 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.
The said inorganic material and the said organic material may be used individually by 1 type, and may use 2 or more types together. Among these, organic materials are preferable, films of polyethylene terephthalate, polycarbonate, polymethyl methacrylate, and the like are preferable, and polyethylene terephthalate is particularly preferable.

For the purpose of improving the adhesion of the coating layer, the support is subjected to surface modification by performing corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. Is preferred.
Moreover, it is preferable to make it white by adding a white pigment such as titanium oxide to the support.
There is no restriction | limiting in particular as thickness of the said support body, Although it can select suitably according to the objective, 10 micrometers-2,000 micrometers are preferable, and 50 micrometers-1,000 micrometers are more preferable.

-Reversible thermosensitive recording layer-
The reversible thermosensitive recording layer (hereinafter, sometimes simply referred to as “recording layer”) includes at least a material whose transparency and color tone reversibly change depending on temperature, and, if necessary, other Comprising the ingredients of:
The material whose transparency and color tone reversibly change depending on the temperature is a material capable of exhibiting a phenomenon in which a visible change is reversibly caused by the temperature change. The heating temperature and the cooling after the heating are possible. Depending on the difference in speed, it can be changed between a relatively colored state and a decolored state. In this case, the visible change is divided into a color state change and a shape change. The change in the color state is caused by, for example, changes in transmittance, reflectance, absorption wavelength, scattering degree, etc., and the thermoreversible recording medium actually changes in color state due to a combination of these changes. To do.

The material whose transparency and color tone reversibly change depending on the temperature is not particularly limited and can be appropriately selected from known materials. However, the temperature can be easily controlled and high contrast can be obtained. In particular, it is particularly preferable that either the transparency or the color tone reversibly change between the first specific temperature and the second specific temperature.
Specifically, it becomes transparent at the first specific temperature and becomes cloudy at the second specific temperature (see JP-A-55-154198), and develops color at the second specific temperature. Decolored at a specific temperature (see Japanese Patent Laid-Open Nos. 4-224996, 4-247985, 4-267190, etc.), become cloudy at the first specific temperature, and the second specific temperature In a transparent state (see Japanese Patent Laid-Open No. 3-169590), which develops black, red, blue, etc. at a first specific temperature and decolorizes at a second specific temperature (Japanese Patent Laid-Open No. 2-188293) Gazette, JP-A-2-188294, etc.).
Among these, a thermoreversible recording medium comprising a resin base material and an organic low molecular weight substance such as a higher fatty acid dispersed in the resin base material has a relatively low second specific temperature and first specific temperature, This is advantageous in that erasure recording with low energy is possible. Moreover, since the color development / decoloration mechanism is a physical change depending on the solidification of the resin and the crystallization of the organic low molecular weight substance, it has a strong characteristic against environmental resistance.
In addition, a thermoreversible recording medium that uses a leuco dye and a reversible developer, which will be described later, to develop color at a second specific temperature and to erase at the first specific temperature is reversible between a transparent state and a colored state. In the colored state, black, blue and other colors are shown, so that a high-contrast image can be obtained.

As the organic low molecular weight substance (dispersed in the resin base material, becoming transparent at the first specific temperature and becoming cloudy at the second specific temperature) in the thermoreversible recording medium, As long as it changes from a polycrystal to a single crystal by heat, there is no particular limitation, and it can be appropriately selected according to the purpose. Generally, a material having a melting point of about 30 ° C. to 200 ° C. can be used. Those having a melting point of 50 ° C to 150 ° C are preferred.
Such an organic low molecular weight substance is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alkanol; alkanediol; halogen alkanol or halogen alkanediol; alkylamine; alkane; alkene; alkyne; Alkanes; halogen alkenes; halogen alkynes; cycloalkanes; cycloalkenes; cycloalkynes; saturated or unsaturated mono- or dicarboxylic acids and their esters, amides or ammonium salts; saturated or unsaturated halogen fatty acids and their esters, amides or ammonium salts Aryl carboxylic acids and their esters, amides or ammonium salts; halogen allyl carboxylic acids and their esters, amides or ammonium salts; thioalcohols; thiocarboxylic acids and their Ester, amine or ammonium salts; carboxylic acid esters of thioalcohol; and the like. These may be used individually by 1 type and may use 2 or more types together.

As carbon number of these compounds, 10-60 are preferable, 10-38 are more preferable, and 10-30 are especially preferable. The alcohol group part in the ester may be saturated or not saturated, and may be halogen-substituted.
Further, the organic low molecular weight substance contains at least one selected from oxygen, nitrogen, sulfur and halogen, for example, —OH, —COOH, —CONH—, —COOR, —NH—, —NH, in the molecule. ₂ , -S-, -SS-, -O-, a halogen atom and the like are preferable.
More specifically, these compounds include, for example, higher fatty acids such as lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, alginic acid, and oleic acid; stearic acid Examples include esters of higher fatty acids such as methyl, tetradecyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate, and dodecyl behenate. Among these, as the organic low molecular weight substance used in the third aspect of the image processing method, higher fatty acids are preferable, and higher fatty acids having 16 or more carbon atoms such as palmitic acid, stearic acid, behenic acid, and lignoceric acid are more preferable. A higher fatty acid having 16 to 24 carbon atoms is more preferable.

  In order to widen the temperature range in which the thermoreversible recording medium can be made transparent, the above-mentioned various organic low molecular substances may be used in appropriate combination, or the organic low molecular substances may have different melting points. These materials may be used in combination. These are disclosed in, for example, JP-A-63-39378, JP-A-63-130380, and Japanese Patent No. 2615200, but are not limited thereto.

The resin base material forms a layer in which the organic low molecular weight substance is uniformly dispersed and held, and affects the transparency at the time of maximum transparency. For this reason, the resin base material is preferably a resin having high transparency, mechanical stability, and good film forming properties.
There is no restriction | limiting in particular as such resin, According to the objective, it can select suitably, For example, polyvinyl chloride; Vinyl chloride-vinyl acetate copolymer, Vinyl chloride-vinyl acetate-vinyl alcohol copolymer, Vinyl chloride copolymers such as vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer; polyvinylidene chloride; vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, etc. Examples thereof include vinylidene chloride copolymers; polyesters; polyamides; polyacrylates or polymethacrylates or acrylate-methacrylate copolymers; silicone resins. These may be used alone or in combination of two or more.

The ratio of the organic low molecular weight substance and the resin (resin base material) in the recording layer is preferably about 2: 1 to 1:16, more preferably 1: 2 to 1: 8 in terms of mass ratio.
When the ratio of the resin is smaller than 2: 1, it may be difficult to form a film in which the organic low molecular weight substance is held in the resin base material. When the ratio is larger than 1:16, Since the amount of the organic low-molecular substance is small, it may be difficult to make the recording layer opaque.

  In addition to the organic low molecular weight substance and the resin, other components such as a high boiling point solvent and a surfactant can be added to the recording layer in order to facilitate recording of a transparent image.

The method for producing the recording layer is not particularly limited and may be appropriately selected depending on the purpose. For example, a solution in which two components of the resin base material and the organic low molecular weight substance are dissolved, or the resin base For example, a dispersion liquid in which the organic low molecular weight substance is dispersed in the form of fine particles in a material solution (the solvent is insoluble in at least one selected from the organic low molecular weight substances) is applied onto the support, for example. And drying.
The solvent for preparing the recording layer is not particularly limited and can be appropriately selected according to the kind of the resin base material and the organic low molecular weight substance. For example, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, four Examples include carbon chloride, ethanol, toluene, and benzene. In addition, when using the said dispersion liquid, also when using the said solution, in the obtained recording layer, the said organic low molecular weight substance precipitates as a fine particle, and exists in a dispersed state.

  The organic low molecular weight substance in the thermoreversible recording medium may be composed of the leuco dye and the reversible developer, which develops color at a second specific temperature and decolors at a first specific temperature. . The leuco dye is itself a colorless or light dye precursor. The leuco dye is not particularly limited and may be appropriately selected from known ones. For example, triphenylmethane phthalide, triallyl methane, fluoran, phenothiazine, thioferolane, xanthene Preferable examples include leuco compounds such as phthalocyanine, indophthalyl, spiropyran, azaphthalide, chromenopyrazole, methine, rhodamine anilinolactam, rhodamine lactam, quinazoline, diazaxanthene, and bislactone. Among these, a fluoran-based or phthalide-based leuco dye is particularly preferable in terms of excellent color development / decoloring properties, color, storage stability, and the like. These may be used individually by 1 type, may use 2 or more types together, and can also respond | correspond to multi-color and full color by laminating | stacking the layer which color-emits a different color tone.

The reversible developer is not particularly limited as long as it can reversibly develop and decolorize by using heat as a factor, and can be appropriately selected according to the purpose. For example, (1) A structure having a color developing ability for developing the leuco dye (for example, phenolic hydroxyl group, carboxylic acid group, phosphoric acid group, etc.) and (2) a structure for controlling cohesion between molecules (for example, long-chain hydrocarbon) Preferred examples include compounds having one or more structures selected from the group wherein the groups are linked to each other in the molecule. The linking moiety may be connected to a divalent or higher valent linking group containing a heteroatom, and the long-chain hydrocarbon group also contains at least one of the same linking group and aromatic group. May be.
Phenol is particularly preferred as the structure having the ability to develop (1) the color of the leuco dye.
The (2) structure for controlling the cohesion between molecules is preferably a long-chain hydrocarbon group having 8 or more carbon atoms, more preferably 11 or more, and the upper limit of the carbon number is 40 or less. Preferably, 30 or less is more preferable.

  Among the reversible developers, a phenol compound represented by the following general formula (1) is preferable, and a phenol compound represented by the following general formula (2) is more preferable.

In the general formulas (1) and (2), R ¹ represents a single bond or an aliphatic hydrocarbon group having 1 to 24 carbon atoms. R ² represents an aliphatic hydrocarbon group having 2 or more carbon atoms which may have a substituent, and the carbon number is preferably 5 or more, and more preferably 10 or more. R ³ represents an aliphatic hydrocarbon group of 1 to 35 carbon atoms, and carbon number, preferably 6 to 35, 8 to 35 is more preferable. These aliphatic hydrocarbon groups may be used alone or in combination of two or more.
The sum of the carbon numbers of R ¹ , R ² , and R ³ is not particularly limited and may be appropriately selected depending on the intended purpose. However, the lower limit is preferably 8 or more, more preferably 11 or more. Preferably, the upper limit is preferably 40 or less, and more preferably 35 or less.
If the sum of the carbon numbers is less than 8, the color development stability and decoloring property may be lowered.
The aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond, but is preferably linear. Examples of the substituent bonded to the hydrocarbon group include a hydroxyl group, a halogen atom, and an alkoxy group.
X and Y may be the same or different and each represents a divalent group containing an N atom or an O atom. Specific examples include an oxygen atom, an amide group, a urea group, and a diacylhydrazine. Group, oxalic acid diamide group, acylurea group and the like. Among these, an amide group and a urea group are preferable.
n shows the integer of 0-1.

  The reversible developer is preferably used in combination with a compound having at least one —NHCO— group and —OCONH— group in the molecule as a decoloring accelerator. In this case, in the process of forming the decolored state, an intermolecular interaction is induced between the decoloring accelerator and the reversible developer, and the color development / decoloring characteristics are improved.

As a mixing ratio of the leuco dye and the reversible developer, an appropriate range varies depending on the combination of the compounds to be used and cannot be specified unconditionally, but the molar ratio is about the leuco dye 1. The reversible developer is preferably from 0.1 to 20, and more preferably from 0.2 to 10.
When the reversible developer is less than 0.1 or more than 20, the density of the colored state may be lowered.
Moreover, when adding the said decoloring accelerator, the addition amount is preferably 0.1 part by mass to 300 parts by mass with respect to 100 parts by mass of the reversible developer, and more preferably 3 parts by mass to 100 parts by mass. preferable.
In addition, the leuco dye and the reversible developer can be used in a microcapsule.

  When the organic low-molecular substance is composed of the leuco dye and the reversible developer, the reversible thermosensitive recording layer contains a binder resin, a crosslinking agent, etc. in addition to these components, and further if necessary. And other ingredients.

The binder resin is not particularly limited as long as the recording layer can be bound on the support, and at least one resin appropriately selected from known resins can be mixed and used.
As the binder resin, a resin that can be cured by heat, ultraviolet rays, electron beams, or the like is preferable in order to improve durability during repetition, and a thermosetting resin using an isocyanate compound or the like as a crosslinking agent is particularly preferable. .
Examples of the thermosetting resin 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. Can be mentioned.
There is no restriction | limiting in particular as such a thermosetting resin, According to the objective, it can select suitably, For example, a phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate resin, cellulose acetate butyrate resin, acrylic polyol Examples thereof include resins, polyester polyol resins, polyurethane polyol resins, and the like. These may be used alone or in combination of two or more. Among these, acrylic polyol resin, polyester polyol resin, and polyurethane polyol resin are particularly preferable.

  The mixing ratio (mass ratio) of the leuco dye and the binder resin in the recording layer is preferably 0.1 to 10 with respect to the leuco dye 1. If the binder resin is less than 0.1, the thermal strength of the recording layer may be insufficient, and if it exceeds 10, the color density may decrease.

  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.

  The amount of the crosslinking agent added to the binder resin is preferably 0.01 to 2 in terms of the ratio of the functional group of the crosslinking agent to the number of active groups contained in the binder resin. If the ratio of the functional groups is less than 0.01, the heat strength may be insufficient, and if it exceeds 2, the color development and decoloring characteristics may be adversely affected.

Furthermore, a catalyst used for this kind of reaction may be used as a crosslinking accelerator.
Examples of the crosslinking accelerator include tertiary amines such as 1,4-diazabicyclo [2,2,2] octane, and metal compounds such as organotin compounds.
The gel fraction of the thermosetting resin in the case of the thermal crosslinking is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. When the gel fraction is less than 30%, the crosslinked state is not sufficient and the durability may be inferior.

  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.

  Examples of other components in the recording layer include various additives for improving and controlling coating characteristics, color development and decoloring characteristics. Examples of these additives include surfactants, plasticizers, conductive agents, fillers, antioxidants, light stabilizers, color development stabilizers, and decolorization accelerators.

A method for producing the recording layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) the binder resin, the leuco dye, and the reversible developer are contained in a solvent. A method of coating the recording layer coating solution dissolved or dispersed in the support on the support and evaporating the solvent to form a sheet or the like, or thereafter crosslinking, (2) only the binder resin At the same time as coating the recording layer coating liquid in which the leuco dye and the reversible developer are dispersed in a solvent in which the solvent is dissolved, and by evaporating the solvent to form a sheet or the like, Or (3) without using a solvent, the binder resin, the leuco dye and the reversible developer are heated and melted and mixed together, and the molten mixture is formed into a sheet or the like. One that crosslinks after cooling , And the like.
In these, a sheet-like thermoreversible recording medium can be formed without using the support. In addition, the recording layer coating liquid may be prepared by dispersing each material in a solvent using a dispersing device, or may be individually dispersed in a solvent and mixed together. The material may be deposited by cooling.

In the method for producing the recording layer, the solvent used in (1) or (2) is not particularly limited and may be appropriately selected depending on the intended purpose. Although it differs depending on the type of the colorant and cannot be generally specified, for example, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene and the like can be mentioned.
The reversible developer is dispersed in the form of particles in the recording layer.

Various pigments, antifoaming agents, pigments, dispersants, slip agents, preservatives, crosslinking agents, plasticizers, and the like are added to the recording layer coating solution for the purpose of developing high performance as a coating material. May be.
The recording layer coating method is not particularly limited and may be appropriately selected depending on the intended purpose. The recording medium is transported on the support in a roll form, continuously, or cut into a sheet form. 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. It can carry out using the well-known method.
The drying conditions for the recording layer coating liquid are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a temperature of room temperature to 140 ° C. for about 10 seconds to 10 minutes.
There is no restriction | limiting in particular as thickness of the said recording layer, Although it can select suitably according to the objective, For example, 1 micrometer-20 micrometers are preferable, and 3 micrometers-15 micrometers are more preferable. If the thickness of the recording layer is less than 1 μm, the color density may be low, and the contrast of the image may be low. Part may be generated, and a desired color density may not be obtained.

-Protective layer-
The protective layer is preferably provided on the recording layer for the purpose of protecting the recording layer.
There is no restriction | limiting in particular as said protective layer, According to the objective, it can select suitably, For example, although you may form in multiple layers, it is preferable to provide in the outermost surface of the layer exposed.
The protective layer contains at least a binder resin, and further contains other components such as a filler, a lubricant, and a coloring pigment as necessary.

The binder resin for the protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an ultraviolet (UV) curable resin, a thermosetting resin, an electron beam curable resin, and the like are preferable. Among these, ultraviolet (UV) curable resins and thermosetting resins are particularly preferable.
The UV curable resin can form a very hard film after curing, and can suppress damage due to physical contact with the surface and deformation of the medium due to laser heating, so that thermoreversible recording with excellent repeated durability A medium can be obtained.
In addition, although the thermosetting resin is slightly inferior to the UV curable resin, the surface can be similarly hardened, and a thermoreversible recording medium excellent in repeated durability can be obtained.

  The UV curable resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, vinyl And unsaturated polyester oligomers; monomers such as various monofunctional or polyfunctional acrylates, methacrylates, vinyl esters, ethylene derivatives, and allyl compounds; Among these, tetrafunctional or higher polyfunctional monomers or oligomers are particularly preferable. 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.

In order to cure the monomer or oligomer using ultraviolet rays, it is preferable to use a photopolymerization initiator or a photopolymerization accelerator.
There is no restriction | limiting in particular as addition amount of the said photoinitiator and the said photoinitiator, Although it can select suitably according to the objective, 0.1 mass with respect to the total mass of the resin component of the said protective layer. % To 20% by mass is preferable, and 1% to 10% by mass is more preferable.

Irradiation of ultraviolet rays for curing the ultraviolet curable resin can be performed using a known ultraviolet irradiation device, and examples of the ultraviolet irradiation device include a light source, a lamp, a power source, a cooling device, a conveyance device, and the like. And so on.
Examples of the light source include a mercury lamp, a metal halide lamp, a potassium lamp, a mercury xenon lamp, and a flash lamp.
The wavelength of the light emitted from the light source is not particularly limited and can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and photopolymerization accelerator contained in the recording layer.
The irradiation conditions of the ultraviolet rays are not particularly limited and can be appropriately selected according to the purpose.For example, lamp output, conveyance speed, etc. can be appropriately determined according to irradiation energy necessary for crosslinking the resin. That's fine.

For the purpose of ensuring good transportability, a silicone having a polymerizable group, a silicone grafted polymer, a wax, a release agent such as zinc stearate, a lubricant such as silicone oil, and the like can be added.
The amount of these added is preferably 0.01% by mass to 50% by mass and more preferably 0.1% by mass to 40% by mass with respect to the total mass of the resin component of the protective layer.
Even if the addition amount is small, the effect can be expressed, but if it is less than 0.01% by mass, it may be difficult to obtain the effect by addition, and if it exceeds 50% by mass, the adhesion to the lower layer may be obtained. May cause problems.
In addition, the protective layer may contain an organic ultraviolet absorber, and the content thereof is preferably 0.5 to 10% by mass with respect to the total mass of the resin component of the protective layer.

Furthermore, in order to improve transportability, an inorganic filler, an organic filler, or the like may be added. 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.
Moreover, it is preferable to use a conductive filler as a countermeasure against static electricity, and it is more preferable to use a needle-like filler as the conductive filler.
As the conductive filler, titanium oxide whose surface is coated with antimony-doped tin oxide is particularly preferable.
As a particle size of the said inorganic filler, 0.01 micrometer-10.0 micrometers are preferable, for example, and 0.05 micrometer-8.0 micrometers are more preferable.
The amount of the inorganic filler added is preferably 0.001 to 2 parts by mass, more preferably 0.005 to 1 part by mass with respect to 1 part by mass of the binder resin in the protective layer.

  There is no restriction | limiting in particular as said organic filler, According to the objective, it can select suitably, For example, a silicone resin, a cellulose resin, an epoxy resin, a nylon resin, a phenol resin, a polyurethane resin, a urea resin, a melamine resin, polyester Examples thereof include resins, polycarbonate resins, styrene resins, acrylic resins, polyethylene resins, formaldehyde resins, polymethyl methacrylate resins, and the like.

The thermosetting resin is preferably cross-linked. Accordingly, as the thermosetting resin, for example, those having a group that reacts with a curing agent such as a hydroxyl group, an amino group, and a carboxyl group are preferable, and a polymer having a hydroxyl group is particularly preferable.
In order to improve the strength of the protective layer, the hydroxyl value of the thermosetting resin is preferably 10 mgKOH / g or more, more preferably 30 mgKOH / g or more, and 40 mgKOH / g in that sufficient coating strength can be obtained. g or more is more preferable. By imparting sufficient coating strength, deterioration of the thermoreversible recording medium can be suppressed even when repeated erasing and recording are performed. As the curing agent, for example, the same curing agent as that used in the recording layer can be preferably used.

A conventionally known surfactant, leveling agent, antistatic agent, etc. may be added to the protective layer as required.
Further, a polymer having an ultraviolet absorbing structure (hereinafter, sometimes referred to as “ultraviolet absorbing polymer”) may be used.
Here, the polymer having an ultraviolet absorbing structure means a polymer having an ultraviolet absorbing structure (for example, an ultraviolet absorbing group) in the molecule.
Examples of the ultraviolet absorbing structure include a salicylate structure, a cyanoacrylate structure, a benzotriazole structure, and a benzophenone structure. Among these, a bezotriazole structure and a benzophenone structure are particularly preferable in terms of good light resistance.
There is no restriction | limiting in particular as a polymer which has the said ultraviolet absorption structure, According to the objective, it can select suitably, For example, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole and A copolymer of 2-hydroxyethyl methacrylate and styrene, a copolymer of 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2-hydroxypropyl methacrylate, and methyl methacrylate, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-hydroxyethyl methacrylate, methyl methacrylate and t-butyl methacrylate, 2 , 2,4,4-Tetrahydroxybenzophenone, 2-hydroxypropyl methacrylate and styrene And a copolymer of methyl methacrylate and propyl methacrylate. These may be used individually by 1 type and may use 2 or more types together.

  As the solvent, the coating liquid dispersing device, the protective layer coating method, the drying method and the like used in the protective layer coating solution, the known methods described in the preparation of the recording layer can be used. In addition, when using the said ultraviolet curing resin, after apply | coating and drying, the hardening process by ultraviolet irradiation is required, but an ultraviolet irradiation device, a light source, irradiation conditions, etc. are as above-mentioned.

  There is no restriction | limiting in particular as thickness of the said protective layer, Although it can select suitably according to the objective, 0.1 micrometer-20 micrometers are preferable, 0.5 micrometer-10 micrometers are more preferable, 1.5 micrometers-6 micrometers are still more preferable. . When the thickness is less than 0.1 μm, the function as a protective layer of the thermoreversible recording medium cannot be sufficiently exerted, and it is deteriorated immediately due to repeated history due to heat and can be used repeatedly. If the thickness exceeds 20 μm, sufficient heat cannot be transmitted to the recording layer below the protective layer, and image recording and erasure due to heat may not be sufficiently performed.

-Intermediate layer-
The intermediate layer improves adhesion between the recording layer and the protective layer, prevents alteration of the recording layer by application of the protective layer, prevents migration of additives in the protective layer to the recording layer, etc. For the purpose, it is preferably provided between the two. In this case, the storage stability of the color image can be improved.
The protective layer contains at least a binder resin, and further contains other components such as a filler, a lubricant, and a coloring pigment as necessary.

There is no restriction | limiting in particular as binder resin of the said intermediate | middle layer, According to the objective, it can select suitably, Resin components, such as binder resin in the said recording layer, a thermoplastic resin, and a thermosetting resin, can be used.
Examples of the binder resin include polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl butyral resin, polyurethane resin, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenol resin, polycarbonate resin, and polyamide resin. Can be mentioned.

The intermediate layer preferably contains an ultraviolet absorber. There is no restriction | limiting in particular as this ultraviolet absorber, According to the objective, it can select suitably, For example, both an organic compound and an inorganic compound can be used.
The organic and inorganic ultraviolet absorbers may be contained in the recording layer.
Further, an ultraviolet absorbing polymer may be used, and it may be cured with a crosslinking agent. These are preferably the same as those used in the protective layer.

There is no restriction | limiting in particular as thickness of the said intermediate | middle layer, Although it can select suitably according to the objective, 0.1 micrometer-20 micrometers are preferable, and 0.5 micrometer-5 micrometers are more preferable.
As the solvent used in the intermediate layer coating liquid, the coating liquid dispersion device, the intermediate layer coating method, the intermediate layer drying method, and the curing method, the known methods described in the preparation of the recording layer may be used. it can.

-Under layer-
In order to effectively utilize the applied heat to increase the sensitivity, or to improve the adhesion between the support and the recording layer and to prevent the recording layer material from penetrating into the support, the recording layer and the recording layer An under layer may be provided between the support and the support.
The under layer 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 particle, and multi-hollow particles in which many hollow portions are present in the particle. 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 hollow particles may be appropriately manufactured or commercially available.
There is no restriction | limiting in particular as the addition amount in the said under layer of the said hollow particle, Although it can select suitably according to the objective, For example, 10 mass%-80 mass% are preferable.

As the binder resin for the under layer, the same resin as the recording layer or the layer containing a polymer having an ultraviolet absorbing structure can be used.
The under layer can 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 as thickness of the said under layer, Although it can select suitably according to the objective, 0.1 micrometer-50 micrometers are preferable, 2 micrometers-30 micrometers are more preferable, and 12 micrometers-24 micrometers are still more preferable.

-Back layer-
A back layer may be provided on the side of the support opposite to the surface on which the recording layer is provided in order to prevent curling, antistatic and transportability of the thermoreversible recording medium.
The back layer contains at least a binder resin, and further contains other components such as a filler, a conductive filler, a lubricant, and a coloring pigment as necessary.

There is no restriction | limiting in particular as binder resin of the said back layer, 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. . Among these, ultraviolet (UV) curable resins and thermosetting resins are particularly preferable.
About the said ultraviolet curable resin and the said thermosetting resin, the thing similar to what is used by the said recording layer, the said protective layer, and the said intermediate | middle layer can be used conveniently. The same applies to the filler, the conductive filler, and the lubricant.

-Photothermal conversion layer-
The photothermal conversion layer is a layer having a function of absorbing laser light and generating heat, and contains at least a photothermal conversion material having a role of absorbing laser light and generating heat.
The photothermal conversion material can be roughly classified into an inorganic material and an organic material.
Examples of the inorganic material include carbon black, metals such as Ge, Bi, In, Te, Se, Cr, and semimetals and alloys containing them, and these include vacuum deposition methods and particulate materials. A layer is formed by bonding with a resin or the like.
As the organic material, various dyes can be appropriately used according to the light wavelength to be absorbed. When a semiconductor laser is used as the light source, a near infrared having an absorption peak in the vicinity of 700 nm to 1,500 nm. Absorbing dyes are used. Specific examples include cyanine dyes, quinone dyes, quinoline derivatives of indonaphthol, phenylenediamine nickel complexes, phthalocyanine dyes, naphthalocyanine dyes, and the like. In order to repeat image recording and erasing, it is preferable to select a photothermal conversion material having excellent heat resistance.
The near-infrared absorbing dye may be used alone or in combination of two or more, and may be mixed in the recording layer. In this case, the recording layer also serves as the photothermal conversion layer.
When the photothermal conversion layer is provided, the photothermal conversion material is usually used in combination with a resin. The resin used for the light-to-heat conversion layer is not particularly limited and can be appropriately selected from known ones as long as it can hold the inorganic material and the organic material. A curable resin or the like is preferable.

-Adhesive layer and adhesive layer-
The thermoreversible recording medium can be obtained in the form of a thermoreversible recording label by providing an adhesive layer or an adhesive layer on the surface opposite to the recording layer forming surface of the support.
There is no restriction | limiting in particular as a material of the said contact bonding layer and the said adhesion layer, According to the objective, it can select suitably from what is generally used.

The material of the adhesive layer and the adhesive layer may be a hot melt type. Moreover, a release paper may be used and a non-release paper type may be used. By providing the adhesive layer or the pressure-sensitive adhesive layer in this way, the recording layer can be applied to the entire surface or a part of a thick substrate such as a magnetic stripe-added PVC card that is difficult to apply the recording layer. This improves the convenience of the thermoreversible recording medium, such as being able to display part of the information stored in the magnetism.
A thermoreversible recording label provided with such an adhesive layer or adhesive layer is also suitable for thick cards such as IC cards and optical cards.

-Colored layer-
The thermoreversible recording medium may be provided with a colored layer between the support and the recording layer for the purpose of improving visibility.
The colored layer can be formed by applying a solution or dispersion containing a colorant and a resin binder to a target surface and drying, or simply bonding a colored sheet.

The colored layer can be a color print 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 resins, thermosetting resins, ultraviolet curable resins, and electron beam curable resins.
There is no restriction | limiting in particular as thickness of the said color printing layer, Since it changes suitably with respect to printing color density, it can select according to desired printing color density.

The thermoreversible recording medium may be used in combination with an irreversible recording layer. In this case, the color tone of each recording layer may be the same or different.
In addition, a part of the same surface as the recording layer of the thermoreversible recording medium or a part of the opposite surface, or a part of the opposite surface, printing such as offset printing, gravure printing, or any picture by an ink jet printer, a thermal transfer printer, a sublimation printer, etc. In addition, 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 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 can be provided with a hologram for security. In addition, in order to impart design properties, it is possible to provide a relief image, an intaglio shape, or a design such as a person image, a company emblem, or a symbol mark.

-Shape and application of thermoreversible recording medium-
The thermoreversible recording medium can be processed into a desired shape according to the application, for example, a card shape, a tag shape, a label shape, a sheet shape, a roll shape, or the like.
Moreover, what was processed into the card shape can be applied to a prepaid card, a point card, and further a credit card.
Furthermore, a tag-shaped size smaller than the card size can be used for a price tag or the like, and a tag-shaped size larger than the card size can be used for process management, a shipping instruction, a ticket, or the like.
Since the label can be affixed, it is processed into various sizes and can be affixed to carts, containers, boxes, containers, etc. that are repeatedly used and used for process management, article management, and the like. In addition, since the recording range is wide at a sheet size larger than the card size, it can be used for general documents, process management instructions, and the like.

-Example of combination with thermoreversible recording member RF-ID-
The thermoreversible recording member is provided with the reversible thermosensitive recording layer (recording layer) capable of reversible display and an information storage unit (integrated) on the same card or tag, and stores information stored in the information storage unit. By displaying the part on the recording layer, it is possible to check the information only by looking at the card or tag without a special device, which is excellent in convenience. In addition, when the contents of the information storage unit are rewritten, the thermoreversible recording medium can be used repeatedly many times by rewriting the display of the thermoreversible recording unit.
The information storage unit is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a magnetic recording layer, a magnetic stripe, an IC memory, an optical memory, and an RF-ID tag. . When used for process management, article management, etc., an RF-ID tag can be particularly preferably used.
The RF-ID tag includes an IC chip and an antenna connected to the IC chip.

The thermoreversible recording member includes the recording layer capable of reversible display and an information storage unit, and a suitable example of the information storage unit is an RF-ID tag.
FIG. 6 shows an example of a schematic diagram of an RF-ID tag. The RF-ID tag 85 includes an IC chip 81 and an antenna 82 connected to the IC chip 81. The IC chip 81 is divided into four parts: a storage unit, a power supply adjustment unit, a transmission unit, and a reception unit, and each performs communication by sharing the function. In the communication, the RF-ID tag 85 and the antenna of the reader / writer communicate with each other by radio waves to exchange data. Specifically, there are two types, an electromagnetic induction method in which an RF-ID85 antenna receives a radio wave from a reader / writer and an electromotive force is generated by electromagnetic induction by a resonance action, and a radio wave method that is activated by a radiated electromagnetic field. In both cases, the IC chip 81 in the RF-ID tag 85 is activated by an external electromagnetic field, converts the information in the chip into a signal, and then transmits a signal from the RF-ID tag 85. This information is received by the antenna on the reader / writer side and recognized by the data processing device, and data processing is performed on the software side.

The RF-ID tag is processed into a label shape or a card shape, and the RF-ID tag can be attached to the thermoreversible recording medium. The RF-ID tag can be attached to the recording layer surface or the back layer surface, but is preferably attached to the back layer surface.
In order to bond the RF-ID tag and the thermoreversible recording medium, a known adhesive or pressure-sensitive adhesive can be used.
The thermoreversible recording medium and the RF-ID tag may be integrated into a card shape or tag shape by laminating or the like.

An example of how to use the thermoreversible recording member that combines the thermoreversible recording medium and the RF-ID tag in process management will be described.
The process line in which the containers containing the delivered raw materials are transported is provided with means for writing a visible image in a non-contact manner on the display part while being transported, and means for non-contact erasing and further transmitting electromagnetic waves. Is provided with a reader / writer for reading and rewriting RF-ID information provided in the container in a non-contact manner. In addition, the process line is provided with a control means for automatically branching, weighing, managing, etc. on the physical distribution line using the individual information read and written without contact while the container is being conveyed. ing.
Information such as the article name and quantity is recorded on the thermoreversible recording medium and the RF-ID tag for the RF-ID thermoreversible recording medium attached to the container, and inspection is performed. In the next step, a processing instruction is given to the delivered raw material, information is recorded on the thermoreversible recording medium and the RF-ID tag, and a processing instruction is made and the processing proceeds. Next, order information is recorded in the thermoreversible recording medium and the RF-ID tag as an ordering instruction for the processed product, the shipping information is read from the container collected after the product is shipped, and the delivery container and the RF are again read. -Used as a thermoreversible recording medium with ID.
At this time, since it is non-contact recording to the thermoreversible recording medium using a laser, information can be erased and recorded without peeling the thermoreversible recording medium from a container or the like. Since information can be recorded in a non-contact manner, the process can be managed in real time, and information in the RF-ID tag can be simultaneously displayed on the thermoreversible recording medium.

(Image processing device)
The image processing apparatus of the present invention is used in the image processing method of the present invention, and includes at least a laser beam emitting unit and a light irradiation intensity adjusting unit, and further includes other members appropriately selected as necessary. Have.

-Laser light emitting means-
The laser light is emitted from a laser oscillator which is the laser light emitting means. The laser beam emitting means is not particularly limited as long as the laser beam can be irradiated, and can be appropriately selected according to the purpose. For example, a CO ₂ laser, a YAG laser, a fiber laser, a semiconductor laser (LD), etc. Examples of commonly used lasers are listed below.
The laser oscillator is necessary for obtaining laser light having high light intensity and high directivity. For example, mirrors are arranged on both sides of the laser medium, the laser medium is pumped (energy supply), and excited. The stimulated emission is caused by increasing the number of atoms in the state and forming an inversion distribution. Then, only the light in the optical axis direction is selectively amplified, so that the directivity of the light is enhanced and the laser light is emitted from the output mirror.
The wavelength of the laser light emitted from the laser light emitting means is not particularly limited and can be appropriately selected according to the purpose, but is preferably from the visible region to the infrared region, and the image contrast is improved. The near infrared region to the far infrared region are more preferable.
In the visible region, for the purpose of image recording and image erasure on the thermoreversible recording medium, the additive may be colored to absorb the laser light and generate heat, so that the contrast may be lowered.

The wavelength of the laser beam emitted from the CO ₂ laser is 10.6 μm in the far infrared region, and the thermoreversible recording medium absorbs the laser beam, so that recording and erasing of images on the thermoreversible recording medium are performed. Therefore, it becomes unnecessary to add an additive for absorbing the laser beam and generating heat. Further, even if a laser beam having a wavelength in the near infrared region is used, the additive may absorb visible light, but the CO ₂ laser that does not require the additive is There is an advantage that a decrease in image contrast can be prevented.

The wavelength of the laser light emitted from the YAG laser, the fiber laser, and the LD is in the visible to near infrared region (several hundred μm to 1.2 μm). Therefore, it is necessary to add a photothermal conversion material that absorbs the laser beam and converts it into heat. However, since the wavelength is short, there is an advantage that a high-definition image can be recorded.
Further, since the YAG laser and the fiber laser have high output, there is an advantage that it is possible to increase the speed of image recording and erasing. Since the LD itself is small, there is an advantage that the apparatus can be downsized and the cost can be reduced.

-Light irradiation intensity adjustment means-
The light irradiation intensity adjusting unit has a function of changing the light irradiation intensity of the laser light.
The arrangement of the light irradiation intensity adjusting means is not particularly limited as long as the light irradiation intensity adjusting means is arranged on the optical path of the laser light emitted from the laser light emitting means. Although it can be selected as appropriate, it is preferably disposed between the laser beam emitting means and a galvanometer mirror described later, and more preferably disposed between a beam expander described later and the galvanometer mirror.

The light irradiation intensity adjusting means reduces the light intensity distribution of the laser light from the Gaussian distribution by decreasing the light intensity at the center position with respect to the light intensity around the center, and the light irradiation intensity at the center position of the irradiated laser light. and I _1, a light irradiation intensity _{I 2} at the 80% plane of the total irradiation energy of the irradiated laser beam, preferably has a function of changing such that _{0.40 ≦ I 1 / I 2 ≦} 2.00 . Thereby, deterioration of the thermoreversible recording medium due to repeated image recording and image erasure can be suppressed, and repeated durability can be improved while maintaining image contrast.

There is no restriction | limiting in particular as said light irradiation intensity | strength adjustment means, Although it can select suitably according to the objective, For example, a lens, a filter, a mask, a mirror, a fiber coupling etc. are mentioned suitably. Among these, a lens with low energy loss is preferable, and the lens includes a kaleidoscope, an integrator, a beam homogenizer, an aspheric beam shaper (a combination of an intensity conversion lens and a phase correction lens), an aspheric element lens, and a diffractive optical element. An element etc. can be used conveniently, and an aspherical element lens and a diffractive optical element are particularly preferable.
When a filter, a mask, or the like is used, the light irradiation intensity can be adjusted by cutting the central portion of the laser light. In the case of using a mirror, the light irradiation intensity can be adjusted by using a deformable mirror whose shape is mechanically changed in conjunction with a computer, a mirror having partially different reflectivity or surface irregularities, and the like.
In the case of a laser having an oscillation wavelength of near infrared or visible light, it is preferable to adjust the light irradiation intensity by fiber coupling. Examples of lasers having near-infrared and visible light oscillation wavelengths include semiconductor lasers and solid-state lasers.
The method for adjusting the light irradiation intensity by the light irradiation intensity adjusting means will be described in detail in the description of the image processing apparatus of the present invention to be described later.

An example of a method for adjusting the light irradiation intensity using an aspherical beam shaper as the light irradiation intensity adjusting means will be described below.
For example, when a combination of an intensity conversion lens and a phase correction lens is used, as shown in FIG. 7A, two aspheric lenses are arranged on the optical path of the laser light emitted from the laser light emitting means. To do. Then, the ratio I ₁ / I ₂ is reduced with respect to the Gaussian distribution at the target position (distance 1) by the first aspheric lens L1 (flat top shape in FIG. 7A). Adjust and convert intensity. Thereafter, in order to propagate the intensity-converted beam (laser light) in parallel, the phase is corrected by the second aspheric lens L2. As a result, the light intensity distribution of the Gaussian distribution can be changed.
As shown in FIG. 7B, only the intensity conversion lens L may be disposed on the optical path of the laser light emitted from the laser light emitting means. In this case, with respect to an incident beam (laser light) distributed in a Gaussian manner, a portion having a high intensity (inside) diffuses the beam as indicated by X1, and a portion having a low intensity (outside) is indicated by X2. By converging the beam, the ratio I ₁ / I ₂ can be reduced (in FIG. 7B, a flat top shape).
Furthermore, an example of a method for adjusting the light irradiation intensity using a combination of a fiber-coupled semiconductor laser and a lens as the light irradiation intensity adjusting means will be described below.
In a fiber-coupled semiconductor laser, laser light propagates through the fiber while being repeatedly reflected. Therefore, the light intensity distribution of the laser light emitted from the fiber end is different from the Gaussian distribution, and the Gaussian distribution and the flatness are different. The light intensity distribution corresponds to the middle of the top shape. A combination of a plurality of convex lenses and / or concave lenses as a condensing optical system is attached to the fiber end so that such a light intensity distribution becomes the flat top shape.

Here, FIG. 8 shows an example of the image processing apparatus of the present invention.
The image processing apparatus shown in FIG. 8 includes, for example, a central portion of laser light as the light irradiation intensity adjusting means in the optical path of a laser marker (LP-440, manufactured by Sunkus Corporation) having a CO ₂ laser with an output of 40 W. A mask to be cut (not shown) is incorporated, and the light intensity distribution in the cross section orthogonal to the traveling direction of the laser light can be adjusted so that the light irradiation intensity at the center changes with respect to the light irradiation intensity at the peripheral part.

  The specifications of the image recording / erasing head portion in the laser beam emitting means are: possible laser output range: 0.1 to 40 W, irradiation distance movable range: no particular limitation, spot diameter range: 0.18 to 10 mm, scan speed range : Max 12,000 mm / s, irradiation distance range: 110 mm × 110 mm, focal length: 185 mm.

  The image processing apparatus may include an optical unit, a power supply control unit, and a program unit in addition to having at least the laser beam emitting unit and the light intensity adjusting unit.

The optical unit includes a laser oscillator 10 which is a laser beam emitting means, a beam expander 2, a scanning unit 5, an fθ lens 6, and the like.
The beam expander 2 is an optical member having a plurality of lenses arranged in parallel, and is disposed between a laser oscillator 10 as the laser beam emitting means and a galvanometer mirror described later, and is emitted from the laser oscillator. The light is expanded in the radial direction to be almost parallel light. The magnification of the laser beam is preferably in the range of 1.5 to 50 times, and the beam diameter of the laser beam at that time is preferably 3 to 50 mm.
The scanning unit 5 includes a galvanometer 4 and a galvanometer mirror 4A attached to the galvanometer. Then, the laser light output from the laser oscillator 10 is scanned at high speed 4A by two galvanometer mirrors in the X-axis direction and the Y-axis direction attached to the galvanometer 4, whereby the thermoreversible recording medium 7 In addition, image recording or image erasing can be performed. Galvano mirror scanning is preferable to enable high-speed optical scanning. The size of the galvanometer mirror depends on the beam diameter of the parallel light expanded by the beam expander, preferably in the range of 3 mm to 60 mm, and more preferably in the range of 6 mm to 40 mm.
If the beam diameter of the parallel light is too small, the spot diameter after being condensed by the fθ lens may not be able to be reduced. On the other hand, if the beam diameter of the parallel light is made too large, the size of the galvanometer mirror may become large and high-speed optical scanning may not be possible.
The fθ lens 6 is a lens that causes the laser light rotationally scanned at a constant angular velocity by the galvanometer mirror 4A attached to the galvanometer 4 to move at a constant velocity on the plane of the thermoreversible recording medium 7.
The power supply control unit includes a discharge power supply (in the case of a CO ₂ laser) or a drive power supply for a light source that excites a laser medium (such as a YAG laser), a galvanometer drive power supply, a cooling power supply such as a Peltier element, and the entire image processing apparatus. It is composed of a control unit that performs control.
The program unit is a unit for inputting conditions such as laser light intensity and laser scanning speed and creating and editing characters to be recorded for recording or erasing images by touch panel input or keyboard input. .

The image processing method and the image processing apparatus of the present invention are capable of repeatedly recording and erasing a high-contrast image at high speed on a thermoreversible recording medium such as a label attached to a container such as cardboard in a non-contact manner. In addition, deterioration of the thermoreversible recording medium due to repetition can be suppressed. For this reason, it can be particularly suitably used in a distribution / delivery system. In this case, for example, an image can be recorded and erased on the label while moving the cardboard placed on a belt conveyor, and the shipping time can be shortened because the line does not need to be stopped. Further, the cardboard to which the label is attached can be reused as it is without peeling off the label, and the image can be erased and recorded again.
In addition, since the image processing apparatus includes the light irradiation intensity adjusting unit that changes the light irradiation intensity of the laser light, the deterioration of the thermoreversible recording medium due to repeated recording and erasing of images is effectively suppressed. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Production Example 1)
<Preparation of thermoreversible recording medium>
A thermoreversible recording medium in which the color tone reversibly changes depending on temperature (transparent state-colored state) was produced as follows.

-Support-
As a support, a 125 μm thick white turbid polyester film (manufactured by Teijin DuPont Co., Ltd., Tetron film U2L98W) was used.

-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 heated and dried at 80 ° C. for 2 minutes to form an under layer having a thickness of 20 μm.

-Reversible thermosensitive recording layer (recording layer)-
5 parts by mass of a reversible developer represented by the following structural formula (1) and 0.5 parts by mass of two types of decoloring accelerators represented by the following structural formulas (2) and (3) 10 parts by mass of a polyol 50% by mass solution (hydroxyl value: 200 mg KOH / g) and 80 parts by mass of methyl ethyl ketone were pulverized and dispersed using a ball mill until the average particle size was about 1 μm.

(Reversible developer)

(Discoloring accelerator)

  Next, 1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane as the leuco dye is represented by the following structural formula (4) in a dispersion obtained by pulverizing and dispersing the reversible developer. Add 0.2 parts by mass of a phenolic antioxidant (Ciba Specialty Chemicals, IRGANOX565) and 5 parts by mass of isocyanate (Nihon Polyurethane Co., Ltd., Coronate HL). Prepared.

  Next, the obtained recording layer coating solution was applied onto the support on which the under layer had been formed using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours. And a recording layer having a thickness of 11 μm was formed.

-Intermediate layer-
Acrylic polyol resin 50 mass% solution (Mitsubishi Rayon Co., Ltd., LR327) 3 mass parts, Zinc oxide fine particle 30 mass% dispersion (Sumitomo Cement Co., Ltd., ZS303) 7 mass parts, Isocyanate (Nihon Polyurethane Co., Ltd., Coronate HL) 1.5 parts by mass and 7 parts by mass of methyl ethyl ketone were added and stirred well to prepare an intermediate layer coating solution.
Next, on the support on which the under layer and the recording layer are formed, the intermediate layer coating solution is applied with a wire bar, heated and dried at 90 ° C. for 1 minute, and then at 60 ° C. Heating was performed for 2 hours to form an intermediate layer having a thickness of 2 μm.

-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 (Nippon Ciba Geigy Co., Ltd., Irgacure 184) 0.5 Mass parts and 11 parts by mass of isopropyl alcohol were added, and the mixture was well stirred by a ball mill and dispersed until the average particle size became about 3 μm to prepare a coating solution for a protective layer.
Next, on the support on which the under layer, the recording layer, and the intermediate layer are formed, the protective layer coating solution is applied with a wire bar, heated and dried at 90 ° C. for 1 minute, The protective layer having a thickness of 4 μm was formed by crosslinking with an 80 W / cm ultraviolet lamp.

-Back layer-
Pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) 7.5 parts by mass, urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-3320HA) 2.5 parts by mass, acicular conductive titanium oxide ( FT-3000 manufactured by Ishihara Sangyo Co., Ltd., long axis = 5.15 μm, short axis = 0.27 μm, composition: 2.5 parts by mass of titanium oxide coated with antimony-doped tin oxide, photopolymerization initiator (Nippon Ciba-Geigy Corporation) Manufactured, Irgacure 184) and 0.5 parts by mass of isopropyl alcohol and 13 parts by mass of isopropyl alcohol were added, and the mixture was thoroughly stirred with a ball mill to prepare a coating solution for a back layer.
Next, the back layer coating solution is applied with a wire bar onto the surface of the support on which the recording layer, the intermediate layer, and the protective layer are formed, on the side where these layers are not formed. After heating and drying at 90 ° C. for 1 minute, crosslinking was performed with an 80 W / cm ultraviolet lamp to form a back layer having a thickness of 4 μm. Thus, the thermoreversible recording medium of Production Example 1 was produced.

(Production Example 2)
<Preparation of thermoreversible recording medium>
A thermoreversible recording medium in which the transparency changes reversibly (transparent state-white turbid state) depending on the temperature was produced as follows.

-Support-
As a support, a transparent PET film having a thickness of 175 μm (Lumirror 175-T12 manufactured by Toray Industries, Inc.) was used.

-Reversible thermosensitive recording layer (recording layer)-
3 masses of a low molecular weight organic substance represented by the following structural formula (5) in a resin solution obtained by dissolving 26 mass parts of a vinyl chloride copolymer (manufactured by Zeon Corporation, M110) in 210 mass parts of methyl ethyl ketone. And 7 parts by mass of docosyl behenate were added, ceramic beads having a diameter of 2 mm were put in a glass bottle, and dispersed for 48 hours using a paint shaker (manufactured by Asada Tekko Co., Ltd.) to prepare a uniform dispersion.

Next, 4 parts by mass of an isocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., Coronate 2298-90T) was added to the obtained dispersion to prepare a thermosensitive recording layer solution.
Next, the obtained heat-sensitive recording layer solution is applied onto the support (adhesive layer of a PET film having a magnetic recording layer), heated and dried, and then stored in a 65 ° C. environment for 24 hours. And a thermosensitive recording layer having a thickness of 10 μm was provided.

-Protective layer-
A heat-sensitive solution comprising 10 parts by mass of a 75% by weight butyl acetate solution of urethane acrylate UV curable resin (Unidic C7-157, manufactured by Dainippon Ink & Chemicals, Inc.) and 10 parts by mass of isopropyl alcohol is heated with a wire bar. After coating on the recording layer, heating and drying, it was cured by irradiating with an ultraviolet ray with an 80 W / cm high pressure mercury lamp to form a protective layer having a thickness of 3 μm. Thus, the thermoreversible recording medium of Production Example 2 was produced.

(Production Example 3)
-Production of thermoreversible recording media-
In Production Example 1, the same procedure as in Production Example 1 was carried out except that 0.03 parts by mass of a photothermal conversion material (Nippon Shokubai Co., Ltd., e-excolor IR-14) was added during the production of the thermoreversible recording medium. Thus, a thermoreversible recording medium of Production Example 3 was produced.

(Production Example 4)
-Production of thermoreversible recording media-
In Production Example 2, the same procedure as in Production Example 2 was carried out except that 0.07 parts by mass of a photothermal conversion material (Nippon Shokubai Co., Ltd., e-color IR-14) was added during the production of the thermoreversible recording medium. Thus, a thermoreversible recording medium of Production Example 4 was produced.

(Evaluation methods)
<Laser beam intensity distribution measurement>
The intensity distribution of the laser beam was measured according to the following procedure.
When a semiconductor laser device is used as a laser, a laser beam analyzer (manufactured by Point Gray Research, Scorpion SCOR-20SCM) is first installed so that the irradiation distance is the same position as when recording on a thermoreversible recording medium. The beam intensity was reduced using a beam splitter (BEAMSTAR-FX-BEAM SPLITTER, manufactured by OPHIR) so that the output was 3 × 10 ^−6, and the laser light intensity was measured with a laser beam analyzer. . Next, the obtained laser beam intensity was made into a three-dimensional graph to obtain an intensity distribution of the laser beam.
When a CO ₂ laser device is used as the laser, a high power laser beam analyzer (manufactured by Spiricon, LPK-CO ₂ -16) is used, and the Zn-Se wedge is adjusted so that the laser output becomes 0.05%. The light intensity was measured by using a CaF ₂ filter (manufactured by Spiricon, LBS-100-IR-W) and a CaF ₂ filter (manufactured by Spiricon, LBS-100-IR-F), and the laser light intensity was measured.

<Reflectance density measurement>
The reflection density is measured by using a gray scale (manufactured by Kodak) with a scanner (Canon, Canon Scan 4400), and the obtained digital gradation value and the density value measured with a reflection densitometer (Macbeth, RD-914). The digital gradation value obtained by capturing the recorded image and the erased erased portion with the scanner was converted into a density value to obtain a reflection density value.
In the present invention, in the thermoreversible recording medium in which the thermoreversible recording layer contains a resin and an organic low molecular weight substance, the density of the erasure part is 1.5 or more, and the thermoreversible recording layer has a leuco dye and a reversible manifestation. In the thermoreversible recording medium containing the colorant, the image can be erased when the density is 0.15 or less. In the thermoreversible recording medium in which the thermoreversible recording layer contains a resin and an organic low molecular weight substance, the measurement was performed with black paper (OD value = 1.7) on the back.

(Example 1)
-Image recording process-
Using a laser marker equipped with a CO ₂ laser with an output of 40 W (manufactured by Sunkus Corporation, LP-440), the thermoreversible recording medium of Production Example 1 is placed at a position 5 mm away from the focal length, and the laser output is 11.0 W and the irradiation distance Characters from “A” to “Z” having a character size of 5 × 5 mm with respect to the thermoreversible recording medium of Production Example 1 adjusted to 190 mm, a spot diameter of 0.56 mm, and a scanning speed of 2,000 mm / s. Was recorded twice. The recording time was 0.73 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 2.30.
The position of the thermoreversible recording medium was Y / X = 1.027, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, if the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 3 .1.

-Image erasing process-
Subsequently, the image was erased by heating at 140 ° C. for 1 second under a pressure of 1 kgf / cm ² using a thermal tilt tester (TYPE HG-100, manufactured by Toyo Seiki Co., Ltd.).

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

(Example 2)
-Image recording process-
Using a laser marker (LP-440, manufactured by Sunkus Corporation) equipped with a CO ₂ laser with an output of 40 W, the thermoreversible recording medium of Production Example 1 is placed at a position 9 mm away from the focal length, and the laser output is 15.0 W and the irradiation distance Characters from “A” to “Z” having a character size of 5 × 5 mm with respect to the thermoreversible recording medium of Production Example 1, adjusted to be 194 mm, a spot diameter of 0.87 mm, and a scanning speed of 2,000 mm / s. Was recorded twice. The recording time was 0.71 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 2.30.
The position of the thermoreversible recording medium was Y / X = 1.05, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, assuming that the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 4 .83.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

(Example 3)
-Image recording process-
Using a laser marker equipped with a CO ₂ laser with an output of 40 W (manufactured by Sunkus Corporation, LP-440), the thermoreversible recording medium of Production Example 1 is placed at a position 46 mm away from the focal length, and the laser output is 39.0 W and the irradiation distance. Characters from “A” to “Z” having a character size of 5 × 5 mm with respect to the thermoreversible recording medium of Production Example 1 adjusted to 210 mm, a spot diameter of 2.0 mm, and a scanning speed of 2,000 mm / s. Was recorded twice. The recording time was 0.65 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 2.30.
The position of the thermoreversible recording medium is Y / X = 1.14, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, assuming that the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 11 .1.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice. Furthermore, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveying speed of 10 m / min, and “A” to “A” having a character size of 5 × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.66 seconds, and all the characters from “A” to “Z” could be recorded twice.

Example 4
-Image recording process-
A laser marker (LP-440, manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W was used, and a mask having a 6 mm hole in the center was incorporated in the optical path of the laser beam.
Next, using the laser marker, the thermoreversible recording medium of Production Example 1 adjusted to have a laser output of 20.0 W, an irradiation distance of 205.0 mm, a spot diameter of 0.70 mm, and a scan speed of 2,000 mm / s. The characters “A” to “Z” having a character size of 5 mm × 5 mm were recorded twice. The recording time was 0.68 seconds. At this time, the I ₁ / I ₂ value was 1.97 in the intensity distribution of the laser beam.
The position of the thermoreversible recording medium was Y / X = 1.11 where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, assuming that the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 3 .89.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

(Example 5)
-Image recording process-
Using a laser marker (LP-440 manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W, a mask for cutting the central portion of the laser beam was incorporated in the optical path of the laser beam.
Next, the laser marker was used to adjust the laser output of 28.0 W, the irradiation distance of 198 mm, the spot diameter of 0.65 mm, and the scan speed of 2,000 mm / s. Characters “A” to “Z” having a size of 5 mm × 5 mm were recorded twice. The recording time was 0.70 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 1.60.
The position of the thermoreversible recording medium was Y / X = 1.07, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, if the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 3 .61.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and the characters from “A” to “Z” could be recorded twice.

(Example 6)
-Image recording process-
Using a laser marker (LP-440 manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W, a mask for cutting the central portion of the laser beam was incorporated in the optical path of the laser beam.
Next, using the laser marker, the thermoreversible recording medium of Production Example 1 adjusted to have a laser output of 36.0 W, an irradiation distance of 200.5 mm, a spot diameter of 0.95 mm, and a scanning speed of 2,000 mm / s. The characters “A” to “Z” having a character size of 5 mm × 5 mm were recorded twice. The recording time was 0.70 seconds. At this time, in the intensity distribution of the laser light, the I ₁ / I ₂ value was 0.56.
The position of the thermoreversible recording medium was Y / X = 1.08 where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
The spot diameter at the focal position is 0.18 mm. If the spot diameter of the laser light at the focal position is A and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 5 .28.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

(Example 7)
-Image recording process-
Using a laser marker (LP-440 manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W, a mask for cutting the central portion of the laser beam was incorporated in the optical path of the laser beam.
Next, using the laser marker, the thermoreversible recording medium of Production Example 1 adjusted to have a laser output of 36.0 W, an irradiation distance of 202.0 mm, a spot diameter of 1.0 mm, and a scanning speed of 2,000 mm / s. The characters “A” to “Z” having a character size of 5 × 5 mm were recorded twice. The recording time was 0.69 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 0.40.
The position of the thermoreversible recording medium was Y / X = 1.09, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
The spot diameter at the focal position is 0.18 mm. If the spot diameter of the laser light at the focal position is A and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 5 .56.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

(Example 8)
-Image recording process-
A laser marker (LP-440, manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W was used, and a mask having a 6 mm hole in the center was incorporated in the optical path of the laser beam.
Next, using the laser marker, the thermoreversible recording medium of Production Example 1 adjusted to have a laser output of 20.0 W, an irradiation distance of 203.5 mm, a spot diameter of 0.65 mm, and a scan speed of 2,000 mm / s. The characters “A” to “Z” having a character size of 5 × 5 mm were recorded twice. The recording time was 0.69 seconds. At this time, the I ₁ / I ₂ value in the intensity distribution of the laser beam was 2.08.
The position of the thermoreversible recording medium was Y / X = 1.10, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, if the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 3 .61.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

Example 9
-Image recording process-
Using a laser marker (LP-440 manufactured by Sunkus Co., Ltd.) equipped with a CO ₂ laser with an output of 40 W, a mask for cutting the central portion of the laser beam was incorporated in the optical path of the laser beam.
Next, using the laser marker, the thermoreversible recording medium of Production Example 1 adjusted to have a laser output of 38.0 W, an irradiation distance of 205.0 mm, a spot diameter of 1.1 mm, and a scanning speed of 2,000 mm / s. The characters “A” to “Z” having a character size of 5 mm × 5 mm were recorded twice. The recording time was 0.68 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 0.35.
The position of the thermoreversible recording medium was Y / X = 1.11 where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
Further, if the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 6 .11.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.
Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.

(Example 10)
-Image recording process-
Images were recorded as in Example 5.

-Image erasing process-
Subsequently, using the laser apparatus of Example 1, the laser output is 32 W, the irradiation distance is 200 mm, the spot diameter is 1.3 mm, the scan speed is 11,000 mm / s, and the irradiation is performed in a range of 10 mm × 50 mm, The image recorded on the thermoreversible recording medium was erased. The erase time was 0.63 seconds.
The arrangement position of the thermoreversible recording medium at this time is Y / X = 1.08 where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium. there were.
Further, if the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 7 .2.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor, and moved at a conveyance speed of 9 m / min. As a result, the moving time of the thermoreversible recording medium was 0.74 seconds, and an image in the range of 10 mm × 50 mm could be completely erased.

(Example 11)
-Image recording process-
Images were recorded as in Example 5.

-Image erasing process-
Subsequently, the same procedure as in Example 10 was performed, except that the laser apparatus of Example 1 was used, and the laser output was 32 W, the irradiation distance was 277.5 mm, the spot diameter was 6.9 mm, and the scan speed was 1,000 mm / s. Deleted the image. The erase time was 0.71 seconds.
Note that the arrangement position of the thermoreversible recording medium at this time is Y / X = 1.5, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium. there were.
Further, assuming that the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 38 0.0.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor, and moved at a conveyance speed of 9 m / min. As a result, the image in the range of 10 mm × 50 mm could be completely erased.

(Example 12)
-Image recording process-
Images were recorded as in Example 5.

-Image erasing process-
Subsequently, an image was obtained in the same manner as in Example 10 except that the laser apparatus of Example 1 was used to adjust the laser output to 32 W, the irradiation distance of 388 mm, the spot diameter of 15.0 mm, and the scan speed of 250 mm / s. Erased. The erase time was 1.5 seconds.
Note that the arrangement position of the thermoreversible recording medium at this time is Y / X = 2.1 where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium. there were.
Further, if the spot diameter at the focal position is 0.18 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 83 .3.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor, and moved at a conveyance speed of 9 m / min. As a result, the image in the range of 10 mm × 50 mm could not be completely erased.

(Example 13)
In Example 11, the thermoreversible recording medium of Production Example 2 was used instead of the thermoreversible recording medium of Production Example 1, and the laser output during image recording was 16.8 W and the laser output during image erasure was 22.4 W. Except for the above, image recording and image erasing were performed in the same manner as in Example 11. The image recording time was 0.70 seconds, and the image erasing time was 0.71 seconds.
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.
Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.
Furthermore, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and the image is erased under the erasing conditions in the image erasing step. When erased, an image in the range of 10 mm × 50 mm could be completely erased.

(Example 14)
-Image recording process-
As a laser, a 25 W fiber-coupled high-power semiconductor laser device (manufactured by LIMO, LIMO25-F100-DL808, equipped with a condensing optical system fθ lens (focal length: 150 mm), center wavelength: 808 nm, optical fiber core diameter: 100 μm, NA: 0.11), and a mask for cutting the central portion of the laser beam was incorporated in the optical path of the laser beam.
Next, the laser output is adjusted to 22 W, the irradiation distance is 158 mm, and the spot diameter is about 1.2 mm, and the optical scanning with the galvanometer mirror is performed at a speed of 2,000 mm / s. Characters “A” to “Z” having a size of 5 × 5 mm were recorded twice. The recording time was 0.71 seconds.
At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 1.85.
Note that the arrangement position of the thermoreversible recording medium at this time is Y / X = 1.05 where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium. there were.
Further, assuming that the spot diameter at the focal position is 0.74 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 1. .62.

-Image erasing process-
Subsequently, a mask for cutting the central portion of the laser beam is removed from the laser beam path, and adjusted so that the laser output is 20 W, the irradiation distance is 195 mm, the spot diameter is 3 mm, and the scan speed is 1000 mm / s. The area was irradiated to erase the image recorded on the thermoreversible recording medium. The erase time was 0.70 seconds.
At this time, in the light intensity distribution of the laser beam, the I ₁ / I ₂ value was 1.70.
Note that the arrangement position of the thermoreversible recording medium at this time is Y / X = 1.3, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium. there were.
Further, if the spot diameter at the focal position is 0.74 mm, the spot diameter of the laser light at the focal position is A, and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 4 .05.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 mm × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.
Furthermore, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and the image is erased under the erasing conditions in the image erasing step. When erased, an image in the range of 5 mm × 50 mm could be completely erased.

(Example 15)
In Example 14, the thermoreversible recording medium of Production Example 4 was used instead of the thermoreversible recording medium of Production Example 3, and the laser output during image recording was 15.5 W and the laser output during image erasure was 14.0 W. Except for the above, image recording and image erasing were performed in the same manner as in Example 14. The image recording time was 0.71 seconds, and the image erasing time was 0.70 seconds.
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.
Next, the thermoreversible recording medium is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and “A” to “A” having a character size of 5 × 5 mm under the recording conditions in the image recording process. When the characters up to “Z” were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” could be recorded twice.
Furthermore, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and the image is erased under the erasing conditions in the image erasing step. When erased, an image in the range of 5 mm × 50 mm could be completely erased.

(Comparative Example 1)
-Image recording process-
Using the laser apparatus of Example 1, the thermoreversible recording medium of Production Example 1 was placed and adjusted so that the laser output was 7.1 W, the irradiation distance was 185 mm, the spot diameter was 0.18 mm, and the scan speed was 2,000 mm / s. On the thermoreversible recording medium of Production Example 1, characters “A” to “Z” having a character size of 5 mm × 5 mm were recorded twice. The recording time was 0.75 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 2.30.
Note that the arrangement position of the thermoreversible recording medium is Y / X = 1.0, where X is the distance from the laser light source to the focal position, and Y is the distance from the laser light source to the thermoreversible recording medium. When the spot diameter of the laser beam at the position is A and the spot diameter of the laser beam on the thermoreversible recording medium is B, B / A = 1.0.

-Image erasing process-
Subsequently, the image was erased in the same manner as in Example 1.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

  Next, the thermoreversible recording medium on which the image is recorded in the image recording step is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and characters are recorded under the recording conditions in the image recording step. When the characters “A” to “Z” having a size of 5 × 5 mm were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” were recorded. It was not possible to record twice.

(Comparative Example 2)
-Image recording process-
Using a laser marker equipped with a CO ₂ laser with an output of 40 W (manufactured by Sunkus Corporation, LP-440), the thermoreversible recording medium of Production Example 1 is placed at a position near 11 mm from the focal length, and the laser output is 26.0 W and the irradiation distance. Characters from “A” to “Z” having a character size of 5 mm × 5 mm with respect to the thermoreversible recording medium of Production Example 1 adjusted to be 174 mm, a spot diameter of 1.0 mm, and a scanning speed of 2,000 mm / s. Was recorded twice. The recording time was 0.79 seconds. At this time, in the intensity distribution of the laser beam, the I ₁ / I ₂ value was 2.30.
The position of the thermoreversible recording medium was Y / X = 0.94, where X is the distance from the laser light source to the focal position and Y is the distance from the laser light source to the thermoreversible recording medium.
The spot diameter at the focal position is 0.18. If the spot diameter of the laser light at the focal position is A and the spot diameter of the laser light on the thermoreversible recording medium is B, B / A = 5 .6.

-Image erasing process-
Subsequently, an image was obtained in the same manner as in Example 10 except that the laser device was used and the laser output was 22.0 W, the irradiation distance was 155 mm, the spot diameter was 2.0 mm, and the scan speed was 3,000 mm / s. Deleted. Further, the image erasing time at this time was 0.90 seconds.

-Evaluation of repeated durability-
The image recording step and the image erasing step are repeated, and the reflection density of the erasure part of the thermoreversible recording medium is measured every 10 times.

Next, the thermoreversible recording medium on which the image is recorded in the image recording step is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and characters are recorded under the recording conditions in the image recording step. When the characters from “A” to “Z” of size 5 mm × 5 mm were recorded twice, the movement time of the thermoreversible recording medium was 0.74 seconds, and all the characters from “A” to “Z” It was not possible to record twice.
Furthermore, the thermoreversible recording medium on which the image has been recorded in the image recording step is attached to a plastic box, placed on a conveyor and moved at a conveyance speed of 9 m / min, and the image is erased under the erasing conditions in the image erasing step. When erased, the movement time of the thermoreversible recording medium was 0.74 seconds, and an image in the range of 10 mm × 50 mm could not be completely erased.

  The image processing method and the image processing apparatus of the present invention are capable of repeatedly recording and erasing a high-contrast image at a high speed in a non-contact manner with respect to a thermoreversible recording medium, and the degradation of the thermoreversible recording medium due to repetition. For example, it can be widely used for entrance and exit tickets, frozen food containers, industrial products, stickers for various chemical containers, logistics management applications, manufacturing process management applications, and various displays. In particular, it is suitable for use in logistics / delivery systems and process management systems in factories.

FIG. 1 is a schematic diagram illustrating an example of a laser irradiation apparatus. FIG. 2 is a schematic view showing another example of a laser irradiation apparatus. FIG. 3A is a schematic explanatory diagram illustrating an example of an intensity distribution of irradiation laser light used in the present invention. FIG. 3B is a schematic explanatory diagram showing a light intensity distribution (Gaussian distribution) of normal laser light. FIG. 3C is a schematic explanatory diagram illustrating an example of the light intensity distribution when the light intensity distribution of the laser light is changed. FIG. 3D is a schematic explanatory diagram illustrating an example of the light intensity distribution when the light intensity distribution of the laser light is changed. FIG. 3E is a schematic explanatory diagram illustrating an example of the light intensity distribution when the light intensity distribution of the laser light is changed. FIG. 4A is a graph showing the transparency-white turbidity characteristics of the thermoreversible recording medium. FIG. 4B is a schematic explanatory diagram showing a mechanism of a change in transparency-white turbidity of a thermoreversible recording medium. FIG. 5A is a graph showing the color-decoloring characteristics of the thermoreversible recording medium. FIG. 5B is a schematic explanatory diagram showing the mechanism of color development / decoloration change of the thermoreversible recording medium. FIG. 6 is a schematic explanatory diagram illustrating an example of an RF-ID tag. FIG. 7A is a schematic explanatory diagram illustrating an example of light irradiation intensity adjusting means in the image processing apparatus of the present invention. FIG. 7B is a schematic explanatory diagram illustrating an example of light irradiation intensity adjusting means in the image processing apparatus of the present invention. FIG. 8 is a schematic explanatory view showing an example of the image processing apparatus of the present invention.

Explanation of symbols

2 beam expander 4 galvanometer 4A galvanometer mirror 5 scanning unit 6 fθ lens 7 thermoreversible recording medium 10 laser oscillator 81 IC chip 82 antenna 85 RF-ID tag 100 laser device 101 focal position 103 laser beam 105 lens

Claims (11)

An image recording step for recording an image on the thermoreversible recording medium by irradiating and heating a laser beam to a thermoreversible recording medium in which either transparency or color tone reversibly changes depending on temperature, and Including at least one of image erasing steps of erasing an image recorded on the thermoreversible recording medium by heating the thermoreversible recording medium,
In at least one of the image recording step and the image erasing step, the thermoreversible recording medium is disposed at a position far from the focal position of the laser beam, and at least one of image recording and image erasing is performed. Image processing method.   The image processing method according to claim 1, wherein the image erasing step is performed by irradiating and heating the thermoreversible recording medium with laser light.   The following equation is satisfied, where X is the distance from the condenser lens to the focal position, and Y is the distance from the condenser lens to the thermoreversible recording medium: An image processing method according to any one of the above.   The laser beam spot diameter at the focal position is A, and the laser beam spot diameter on the thermoreversible recording medium is B. 4 / A = 1.5 to 76 The image processing method according to any one of the above.   5. The image processing method according to claim 1, wherein the image processing method is used for image recording and image erasing of a moving body.   The thermoreversible recording medium has at least a thermoreversible recording layer on a support, and the thermoreversible recording layer has a first specific temperature and a second specific temperature higher than the first specific temperature. The image processing method according to claim 1, wherein either the transparency or the color tone changes reversibly.   The image according to any one of claims 1 to 6, wherein the thermoreversible recording medium has at least a reversible thermosensitive recording layer on a support, and the reversible thermosensitive recording layer contains a resin and an organic low molecular weight substance. Processing method.   The thermoreversible recording medium has at least a reversible thermosensitive recording layer on a support, and the reversible thermosensitive recording layer contains a leuco dye and a reversible developer. Image processing method. In at least one of the image recording process and the image erasing process, the intensity distribution of the irradiated laser light is determined by the light irradiation intensity I _{1 at} the center position of the irradiated laser light and the 80% plane of the total irradiation energy of the irradiated laser light. The image processing method according to claim ₂ , wherein the light irradiation intensity I ₂ satisfies the following formula: 0.40 ≦ I ₁ / I ₂ ≦ 2.00. It is used for the image processing method according to any one of claims 1 to 9,
Laser beam emitting means;
An image processing apparatus comprising at least light irradiation intensity adjusting means arranged on a laser light emitting surface of the laser light emitting means and changing the light irradiation intensity of the laser light.   The image processing apparatus according to claim 10, wherein the light irradiation intensity adjusting unit is at least one of a lens, a filter, a mask, a mirror, and a fiber coupling.