JP5146350B2 - Image processing method and image processing apparatus - Google Patents

Description

  The present invention can reduce damage caused by repeated image recording and image erasure to prevent deterioration of a thermoreversible recording medium, and can perform image recording in a short time and an image that can be suitably used for the image processing method. The present invention relates to a processing apparatus.

To date, image recording and image erasing on a thermoreversible recording medium (hereinafter sometimes simply referred to as “recording medium” or “medium”) is 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 erasure.
In such a contact 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 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 recording device, it is possible to record and erase images by irradiating a thermoreversible recording medium with laser light, the medium absorbs the light and converts it into heat, and the phase changes with the heat. It is.
This recording apparatus performs recording by irradiating the recording unit with laser light by changing the irradiation direction of the laser light by changing the scanning mirror angle by the operation of the motor and performing scanning. In a normal recording apparatus, it is ideal to set the conditions so that at least one of the irradiation power of the laser beam and the scanning speed is constant, and irradiate the laser beam so that the temperature is the same in the recording area. .

  The laser light source mounted on the laser marker is considered on the premise that the beam shape is irradiated with a laser beam having a circular shape, and the laser beam scanning is normally controlled so as to have a constant speed on the thermoreversible recording medium. Thus, it is set to give a certain energy to the thermoreversible recording medium. However, the laser light emitted from the laser light source mounted on the laser marker is rarely a perfect circle due to variations, and the optical system also shifts with respect to the optical axis. The shape is distorted, and the shape is lost. When the scanning speed on the thermoreversible recording medium is constant and the beam shape is not circular, that is, when the laser beam shape is long in one direction, energy is applied to a narrow area when scanned in one direction. While excessive energy is locally applied, scanning in a direction perpendicular to one direction applies energy to a wide area. As a result, scanning in one direction causes damage to the thermoreversible recording medium. In some cases, printing rubbing may occur when scanning in the direction perpendicular to the direction. In general, since the energy to be applied is set high so as not to cause printing rubbing, excessive energy is locally added in scanning in one direction, and in conventional irreversible thermal recording media, even if excessive energy is applied, it is large. Although it was not a problem, in thermoreversible recording media that repeatedly perform image recording and image erasing, damage accumulation due to excessive energy being applied to the same location, high density uniform image recording and uniform image There is a big problem that the erasing cannot be performed sufficiently. Further, in order to obtain an image that does not cause image blurring, it is necessary to reduce the scanning speed by setting the energy high, and the processing time of the image is required to be long.

For the purpose of solving these problems, for example, in Patent Document 3, the laser irradiation energy is controlled for each drawing point, and when recording is performed so that the recording dots are overlapped or when the recording is performed by folding, it is given to that portion. In addition, it is described that local energy damage is reduced and deterioration of the thermoreversible recording medium is prevented by reducing the energy to be reduced and reducing the energy at predetermined intervals when performing linear recording.
In Patent Document 4, the irradiation energy is multiplied by the following expression, | cos0.5R | ^k (0.3 <k <4), according to the angle R of the turning point at the time of laser drawing. I am trying to reduce energy. As a result, it is possible to prevent excessive energy from being applied to the overlapping part of the line drawing when recording with a laser, to reduce deterioration of the thermoreversible recording medium, or to maintain the contrast without reducing the energy excessively. Become.
Further, in Patent Document 5, when performing predetermined drawing by irradiating a laser beam converged on a non-contact type rewrite thermal label, the optical scanning device is continuously driven without oscillating the laser beam, and laser beam is emitted. Non-contact type rewrite thermal that scans and draws laser light only when the laser beam trajectory (virtual laser beam) is assumed to be moving at substantially constant speed. Label recording methods have been proposed.

  These prior art recording methods are devised so that excessive thermal energy is not applied to the thermoreversible recording medium due to overlap during laser recording. However, if high-density laser and uniform image erasure are repeatedly performed using a high-power laser, not only the start point, end point, and bend of the drawing line, but also the central part of the straight line is excessively heated, resulting in thermoreversibility. The deformation trace of the recording medium and the generation of bubbles are observed, and the material itself responsible for the color development and decoloring characteristics undergoes thermal decomposition, making it impossible to exhibit sufficient ability. As a result, it is not possible to sufficiently perform high-density uniform image recording and uniform image erasure on the entire drawing line including the start point, end point, bent portion, and straight line portion constituting the image, and repeated record erasure is performed. Even if it is performed, it is insufficient as an image processing method with little deterioration, and further improvement and development are desired at present.

  An object of the present invention is to solve the conventional problems and achieve the following objects. In other words, the present invention can perform high-density uniform image recording and uniform image erasing for the entire drawing lines in all scanning directions, reduce damage caused by repeated image recording and image erasing, and a thermoreversible recording medium. It is an object of the present invention to provide an image processing method capable of preventing image deterioration and capable of recording an image in a short time, and an image processing apparatus that can be suitably used for the image processing method.

  In order to avoid the problem that if the beam shape of the laser beam is non-circular and the beam is scanned in the direction of a long beam diameter, excessive energy is locally applied to the thermoreversible recording medium and damaged. As a result of intensive studies by the present inventors, in the image recording process, when the beam shape of the irradiation laser light on the thermoreversible recording medium is non-circular, P / By performing image recording by changing V (where V represents the scanning speed of the laser beam and P represents the irradiation power of the laser beam), the laser beam irradiation energy in the laser beam scanning in the direction of the longer beam diameter. It has been found that the above problem can be effectively solved by decreasing the density P / V and increasing P / V in the short direction.

The present invention is based on the above findings by the present inventors, and means for solving the above 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 the image recording step, when the beam shape of the laser beam on the thermoreversible recording medium is non-circular, P / V (where V is the scanning speed of the laser beam) according to the scanning direction of the laser beam. , P represents an irradiation power of laser light), and image recording is performed by changing the image.
<2> The image processing method according to <1>, wherein image recording is performed by changing only V in P / V according to a scanning direction of laser light.
<3> The image processing method according to <1>, wherein image recording is performed by changing only P in P / V according to a scanning direction of laser light.
<4> 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 <3>, wherein either the transparency or the color tone reversibly changes depending on the temperature.
<5> The thermoreversible recording medium has at least a thermoreversible recording layer on a support, and the thermoreversible recording layer contains a resin and an organic low molecular weight substance, and any one of <1> to <4> The image processing method described in the above.
<6> The thermoreversible recording medium has at least a thermoreversible recording layer on a support, and the thermoreversible recording layer contains a leuco dye and a reversible developer. The image processing method according to any one of the above.
<7> 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 <1> to <6>, wherein the light irradiation intensity I _{2 on the} surface satisfies the following formula: 0.40 ≦ I ₁ / I ₂ ≦ 2.00.
<8> Used in the image processing method according to any one of <1> to <7>, disposed on a laser beam emitting unit, a laser beam emitting surface of the laser beam emitting unit, and irradiated with a laser beam An image processing apparatus comprising at least light irradiation intensity adjusting means for changing intensity.
<9> The image processing apparatus according to <8>, wherein the light irradiation intensity adjustment unit is at least one of a lens, a filter, a mask, a fiber coupling, and a mirror.

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 the image recording step, when the beam shape of the laser beam on the thermoreversible recording medium is non-circular, P / V (where V is the scanning speed of the laser beam) according to the scanning direction of the laser beam. , P represents the irradiation power of laser light), and image recording is performed.
In the image processing method of the present invention, when the beam shape of the laser light on the thermoreversible recording medium is non-circular in the image recording step, P / V ( However, by changing the scanning speed of the laser beam and P indicating the irradiation power of the laser beam), the energy applied to the recording unit on the thermoreversible recording medium becomes constant, and the image is It is possible to prevent excessive energy from being applied depending on the direction of the drawing lines constituting the image, and it is possible to perform high-density uniform image recording and uniform image erasing for all the drawing lines constituting the image. Damage due to repeated erasing can be reduced and deterioration of the thermoreversible recording medium can be prevented.

The image processing apparatus according to the present invention is used in the image processing method according to the present invention, and is disposed on a laser beam emitting means and a laser beam emitting surface of the laser beam emitting means, and changes light irradiation intensity of the laser beam. And at least irradiation intensity adjusting means.
In the image processing apparatus of the present invention, the laser light emitting means emits laser light. 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, deterioration of the thermoreversible recording medium due to repeated recording and erasing of the image is effectively suppressed.

  According to the present invention, the conventional problems can be solved, high density uniform image recording and uniform image erasing can be performed on the entire drawing lines in all scanning directions, and image recording and image erasing are repeated. Thus, it is possible to provide an image processing method capable of reducing the damage caused by the above and preventing deterioration of the thermoreversible recording medium and capable of recording an image in a short time, and an image processing apparatus that can be suitably used for the image processing method.

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

(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.
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, and laser light may be used as a heat source. 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. In addition, when the foamed polystyrene box is equipped with the thermoreversible recording medium as a transport container for use in the distribution line, the foamed polystyrene box itself melts when heated, so that the thermoreversible recording is performed by irradiating a laser beam. It is preferable to erase by locally heating only the 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 process after the image is recorded by the image recording process.

Here, as shown in FIG. 1A, the beam shape of the irradiation laser beam on the thermoreversible recording medium is not circular but has a shape close to an ellipse. This is a phenomenon caused by the deviation of the optical axis of the light source of the laser light and the optical system lens. The magnitude of the deviation (distortion) from the circle is inherent to the laser marker device.
When the beam shape of the laser beam is non-circular (when it is not circular), as shown in FIG. 1A, the ratio of the major axis a to the minor axis b (major axis a / minor axis b) is 1. It means 1 or more.

In this way, when the beam shape of the laser beam is non-circular, if the beam is scanned in the long direction, excessive energy is locally applied to the thermoreversible recording medium and damaged.
Therefore, in the image processing method of the present invention, in the image recording step, when the beam shape of the irradiation laser light on the thermoreversible recording medium is not circular, the scanning speed of the laser light is V, and the irradiation power P of the laser light. In this case, image recording is performed by changing P / V according to the scanning direction of the laser beam. In this case, in the laser beam scanning in the direction in which the beam diameter is long, it is effective to decrease the irradiation energy density P / V of the laser beam and increase P / V in the direction in which the beam diameter is short.
The change amount of P / V is preferably changed in proportion to the reciprocal of the length of the beam diameter with respect to the scanning direction. In other words, as shown in FIG. 1B, when the beam diameter in the scanning direction of the laser beam is R, the laser beam is irradiated to the R / V temporal thermoreversible recording medium, and the energy is R * P / V. In order to apply uniform energy onto the thermoreversible recording medium, it is preferable that (R * P / V) be constant regardless of the scanning direction. The variation amount of (R * P / V) is preferably 15% or less, more preferably 10% or less, regardless of the scanning direction.
The change of P / V may control at least one of the scanning speed (V) and irradiation power (P) of the laser beam.

As a method of changing the irradiation energy density P / V in the laser beam scanning direction, it may be difficult to control both the scanning speed (V) and irradiation power (P) of the laser beam depending on the image processing apparatus used. Therefore, it is also possible to change P / V by controlling either the scanning speed (V) or irradiation power (P) of the laser beam.
Specifically, in order to reduce P / V in scanning in the direction of a long beam diameter, it is achieved by increasing the scanning speed (V) of the laser beam, decreasing the irradiation power (P), or a combination thereof. can do.

  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.

The scanning speed (V) of the laser beam is not particularly limited and can be appropriately selected according to the purpose. However, when the scanning speed is low, it becomes difficult to control the scanning speed and the irradiation power. s or more is preferable, 200 mm / s or more is more preferable, and 300 mm / s or more is still more preferable.
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, 10,000 mm / s or less is preferable, 7,000 mm / s or less is more preferable, 4 More preferably, it is 1,000 mm / s or less. If the scanning speed exceeds 10,000 mm / s, it may be difficult to record a uniform image.
The spot diameter of the laser beam is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.02 mm or more, more preferably 0.1 mm or more, and further preferably 0.2 mm or more. 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 2.0 mm or less, and 1.0 mm or less. Further preferred.
The spot diameter is proportional to the line width to be developed. When the spot diameter is small, the line width is narrow, the contrast is reduced and the visibility is lowered, and when the spot diameter is increased, the line width is increased and the adjacent line width is increased. The overlapping lines overlap, making it impossible to print small characters.

  There is no restriction | limiting in particular as irradiation power (P) of the said laser beam, Although it can select suitably according to the objective, 0.70 times-1.30 times with respect to an optimal condition value are preferable, 0.85 Double to 1.15 times are more preferable. The optimum condition value indicates the central value of the irradiation energy range at the time of recording in which both recording quality and erasing quality can be achieved. is there.

  In addition, the beam shape of the laser beam is measured in advance, and at least one of the laser beam scanning speed and irradiation power data is image-processed in advance so that the value of (P / V) can be adjusted according to the scanning direction of the laser beam By storing in the apparatus and recording based on the data, it is possible to record extremely efficiently.

In the image processing method of the present invention, in the intensity distribution of the laser beam 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 beam, and the irradiation laser It is preferable that the light irradiation intensity I ₂ at the 80% plane of the total irradiation energy of light satisfies the following formula, 0.40 ≦ I ₁ / I ₂ ≦ 2.00.

In at least one of the image recording step and the image erasing step, in the light intensity distribution of the laser beam, the light irradiation intensity I _{1 at} the center position of the irradiated laser beam and 80% of the total irradiation energy of the irradiated laser beam. The thermoreversible recording medium is preferably irradiated with the laser light so that the light irradiation intensity I _{2 on the} surface 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 light irradiation was extremely higher than that at the periphery. When irradiating the thermoreversible recording medium with this Gaussian distribution laser light, the temperature is excessively increased in the central portion, and when the recording and erasing of the image are repeated, the portion deteriorates, and the number of repetitions decreases. Further, if the laser irradiation energy is lowered so as not to raise the temperature of the central portion to a temperature that deteriorates, there is a problem that the size of the image is reduced, and the image contrast is lowered and the image recording 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 light irradiation intensity of the image, it is possible to repeatedly maintain the image contrast without reducing the size of the image while suppressing deterioration of the thermoreversible recording medium due to repeated recording and erasing of the image. 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 I ₁ / I ₂ 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.
When the light intensity ratio I ₁ / I ₂ exceeds 2.00, the light intensity at the center position becomes strong, excessive energy is applied to the thermoreversible recording medium, and the thermoreversible recording medium is subjected to repeated image recording. The disappearance may occur due to deterioration of the material. On the other hand, when the light intensity ratio I ₁ / I ₂ is less than 0.40, energy is not applied to the central portion 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 2 When the irradiation energy is increased to cause color development in the center of the line, the light intensity at the periphery becomes too strong and excessive energy is applied to the thermoreversible recording medium, and repeated recording and erasing may occur. In some cases, the disappearance of the thermoreversible recording medium may occur in the periphery of the line.
Furthermore, if the light intensity 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 stronger than the light irradiation intensity at the peripheral portion, so that recording and erasing of images is possible. The thickness of the drawing line can be changed without changing the irradiation distance by adjusting the irradiation power while suppressing deterioration of the thermoreversible recording medium due to repetition.

Examples of light intensity distribution curves when the intensity distribution of laser light is changed are shown in FIGS. 2B to 2E.
FIG. 2B 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 (in the case of a Gaussian distribution, the light intensity ratio I ₁ / I ₂ = 2. 3). Further, in the light intensity distribution in which the light irradiation intensity at the center position is weaker than the light intensity distribution in FIG. 2B as in FIG. 2C, the light intensity ratio I ₁ / I ₂ is smaller than the light intensity distribution in FIG. 2B. In the light intensity distribution close to the top hat shape as shown in FIG. 2D, the light intensity ratio I ₁ / I ₂ is further smaller than the light intensity distribution in FIG. 2C. In the light intensity distribution where the light irradiation intensity at the center position is weak and the light irradiation intensity at the peripheral part is strong as in FIG. 2E, the light intensity ratio I ₁ / I ₂ is further smaller than the light intensity distribution in FIG. 2D. Therefore, the light intensity ratio I ₁ / I ₂ represents the shape of the light irradiation intensity distribution of the laser light.
When the light intensity 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% plane of the total irradiation energy of the irradiation laser beam refers to the light intensity at the plane when it becomes 80% of the total irradiation energy of the irradiation laser beam. 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 of 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. 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. 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 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.
As a laser that emits the laser beam is not particularly limited and may be suitably selected from those known in the art, CO ₂ laser, YAG laser, fiber laser, and the like semiconductor lasers (LD).
The present invention is effective regardless of the type of irradiation laser, and can be effective for any of the above-described CO ₂ laser, semiconductor laser, YAG laser, and the like.

  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. When the output of the laser beam exceeds 200 W, there is a risk of increasing the size of the laser device.

  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 still 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) cloudy state, the particles of the low molecular weight organic substance are formed of fine crystals of the low molecular weight organic substance, and are formed at the interface of the crystal or the interface of 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. 3A shows an example of a temperature-transparency change curve of a thermoreversible recording medium having a thermoreversible recording layer in which the low molecular weight organic substance is dispersed in the resin.
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. 3A, 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. 3B 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. 3B, one long-chain low-molecular particle and the 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. 4A shows an example of a temperature-color density change curve of a thermoreversible recording medium having a thermoreversible recording layer containing the leuco dye and the developer in the resin, and FIG. 4B shows a transparent state. And a color development / decoloration mechanism of the thermoreversible recording medium in which the color development state changes reversibly with heat.
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, if continue to warm again 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.
In addition, as shown in FIG. 4A, the decolorization due to slow cooling from the melted state and the decoloration due to temperature rising from the colored state both change the aggregation structure at T ₂ , resulting in phase separation and crystallization of the developer. ing.
As described above, when the developer is melted and heated to the 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 the organic low molecular weight substance is crystallized after melting 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 is erased means that, for example, the image density of a linear image including the intersection is continuously measured using a Macbeth densitometer (RD 914), and the transparency of the thermoreversible recording medium is reversible. In the changing mode, the image density is 1.2 or more, and in the mode in which the color tone of the thermoreversible recording medium is changed reversibly, it means that the image density is 0.5 or less. In the aspect in which the transparency of the thermoreversible recording medium reversibly changes, 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 perform measurement 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 thermoreversible recording layer on the support, and further includes a protective layer and an ultraviolet ray appropriately selected as necessary. It has other layers such as an absorption layer, an oxygen barrier layer, an intermediate layer, an undercoat layer, a back layer, a photothermal 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 its 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 may 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.

-Thermoreversible recording layer-
The thermoreversible recording layer (hereinafter, sometimes simply referred to as “recording layer”) includes at least a material in which either transparency or color tone reversibly changes depending on temperature. Comprising ingredients.
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 a temperature change, and the heating temperature and the cooling after the heating. Due to 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 a resin base material and becoming transparent at a first specific temperature and becoming cloudy at a 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. In general, 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, 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. 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 cohesive force 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 number of carbon atoms 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 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. In addition, 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 parts 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.

  In the case where the organic low-molecular substance is composed of the leuco dye and the reversible developer, the thermoreversible 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 a resin, a polyester polyol resin, and a polyurethane polyol resin. 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, you may use the catalyst used for this kind of reaction as a crosslinking accelerator.
Examples of the crosslinking accelerator include tertiary amines such as 1,4-diazabicyclo [2,2,2] octane, and metal compounds such as organotin compounds.
The gel fraction of the thermosetting resin when thermally crosslinked is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more. When the gel fraction is less than 30%, the crosslinked state is not sufficient and the durability may be inferior.

  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 after that, or 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, it is also possible to form a sheet-like thermoreversible recording medium 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.

There is no restriction | limiting in particular as a solvent used in (1) or (2) in the preparation methods of the said recording layer, Although it can select suitably according to the objective, The said binder resin, the said leuco dye, and the said reversible appearance Although it differs depending on the type of the colorant and cannot be generally specified, examples thereof include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene and the like.
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 method for coating the recording layer is not particularly limited and may be appropriately selected depending on the purpose. The recording body is conveyed in the form of a roll, continuously, or cut into a sheet, on the support. 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 of these.
There is no restriction | limiting in particular as drying conditions of the said coating liquid for recording layers, According to the objective, it can select suitably, For example, about 10 second-about 10 minutes at the temperature of room temperature-140 degreeC etc. are mentioned.
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, so the contrast of the image may be low. In some cases, a portion that does not occur is generated, and a desired color density cannot 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. Etc.
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 the 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, the lamp output, the conveyance speed, etc. can be appropriately determined according to the 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 mold 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.
Further, the protective layer may contain an organic ultraviolet absorber, and the content thereof is preferably 0.5% by mass 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. Therefore, 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 necessary.
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.

<Ultraviolet absorbing layer>
In the present invention, for the purpose of preventing the leuco dye in the recording layer from being colored by ultraviolet rays and disappearing due to photodegradation, ultraviolet absorption is performed on the opposite side to the support of the thermoreversible recording layer located on the opposite side of the support. A layer is preferably provided, whereby the light resistance of the recording medium can be improved. In particular, the light resistance is greatly improved by appropriately selecting the ultraviolet absorber and the thickness so that the ultraviolet absorbing layer absorbs ultraviolet rays of 390 nm or less.
The ultraviolet absorbing layer contains at least a binder resin and an ultraviolet absorber, 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 said binder resin, According to the objective, it can select suitably, Resin components, such as binder resin of the said recording layer, a thermoplastic resin, and a thermosetting resin, can be used. Examples of the resin component include polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide, and the like.
As the ultraviolet absorber, any of organic and inorganic compounds can be used.
Further, it is preferable to use a polymer having an ultraviolet absorbing structure (hereinafter sometimes referred to as “ultraviolet absorbing polymer”).
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, a benzophenone structure, and the like. A benzotriazole structure and a benzophenone structure are particularly preferable.

The ultraviolet absorbing polymer is preferably crosslinked. Accordingly, as the ultraviolet absorbing polymer, it is preferable to use a polymer having a group that reacts with a curing agent such as a hydroxyl group, an amino group, or a carboxyl group, and a polymer having a hydroxyl group is particularly preferable. In order to improve the strength of the polymer-containing layer having the ultraviolet absorbing structure, a sufficient coating strength can be obtained by using a polymer having a hydroxyl value of 10 mgKOH / g or more, more preferably 30 mgKOH / g or more. More preferably, it is 40 mgKOH / g or more. By providing a sufficient coating strength, deterioration of the recording medium can be suppressed even if repeated erasure printing is performed.
The thickness of the ultraviolet absorbing layer is preferably 0.1 μm to 30 μm, and more preferably 0.5 μm to 20 μm. For the solvent used in the coating solution of the UV absorbing layer, the dispersion device of the coating solution, the coating method of the UV absorbing layer, the drying / curing method of the UV absorbing layer, etc., use the known methods used in the recording layer. Can do.

<Oxygen barrier layer>
In the present invention, for the purpose of preventing photodegradation of the leuco dye in the thermoreversible recording layer by preventing oxygen from entering the thermoreversible recording layer, it is opposite to the side having the support in the thermoreversible recording layer. The oxygen barrier layer is preferably provided at at least one of the position on the side and the position between the support and the thermoreversible recording layer, and it is particularly preferable to provide the oxygen barrier layer at both positions. Further, in order to prevent photodegradation of the leuco dye in the thermoreversible recording layer, the ultraviolet absorbing layer and the oxygen barrier layer may be provided on the opposite side of the thermoreversible recording layer from the side having the support. In addition, an oxygen barrier layer may be provided on the ultraviolet absorption layer, and an ultraviolet absorption layer may be provided on the oxygen barrier layer.

  Examples of the oxygen barrier layer include a resin or a polymer film having a large visible portion transmittance and a low oxygen permeability. These oxygen barrier layers are selected depending on their use, oxygen permeability, transparency, ease of coating, adhesion, and the like. Specific examples of these oxygen barrier layers include polyacrylic acid alkyl ester, polymethacrylic acid alkyl ester, polymethacrylonitrile, polyalkyl vinyl ester, polyalkyl vinyl ether, polyfluorinated vinyl, polystyrene, vinyl acetate copolymer, Cellulose acetate, polyvinyl alcohol, polyvinylidene chloride, acetonitrile copolymer, vinylidene chloride copolymer, poly (chlorotrifluoroethylene), ethylene-vinyl alcohol copolymer, polyacrylonitrile, acrylonitrile copolymer, polyethylene terephthalate, nylon- 6. Silica vapor-deposited film in which inorganic oxide is vapor-deposited on polymer film such as polyacetal or polyethylene terephthalate or nylon, alumina vapor-deposited film, silica / alcohol Such as Na vapor-deposited film, and the like. Among these, a film obtained by depositing an inorganic oxide on a polymer film is preferable.

As the permeability of the oxygen barrier layer ^is preferably not more than 20ml / m 2 / day / MPa , 5ml / m 2 / day / MPa more preferably ^{less, 1ml / m 2 / day /} MPa or less are particularly preferred.
The oxygen barrier layer may be provided such that the recording layer is sandwiched between the oxygen barrier layers, such as the lower side of the recording layer or the back surface of the support. Thereby, oxygen intrusion to the recording layer can be more effectively prevented, and photodegradation of the leuco dye can be further reduced.
There is no restriction | limiting in particular as a formation method of the said oxygen barrier layer, A normal melt extrusion method, a coating method, a lamination method, etc. can be mentioned.
The thickness of the oxygen barrier layer varies depending on the oxygen permeability of the resin or polymer film, but is preferably 0.1 μm to 100 μm. If it is thinner than this, the oxygen barrier is incomplete, and if it is thicker, the transparency is lowered.

  An adhesive layer may be provided between the oxygen barrier layer and the lower layer. The method for forming the adhesive layer is not particularly limited, and examples thereof include ordinary coating methods and laminating methods. The thickness of the adhesive layer is not particularly limited, but is preferably 0.1 μm to 20 μm. The adhesive layer may be cured with a crosslinking agent.

-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 intermediate 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 particles, and multi-hollow particles in which many hollow portions are present in the particles. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular as a material of the said hollow particle, Although it can select suitably according to the objective, For example, a thermoplastic resin etc. are mentioned suitably.
The 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 that for the recording layer or the layer containing a polymer having an ultraviolet absorbing structure can be used.
The under layer may contain at least one of inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin, and talc, and various organic fillers.
In addition, the under layer may further contain a lubricant, a surfactant, a dispersant, and the like.
There is no restriction | limiting in particular as thickness of the said under layer, Although it can select suitably according to the objective, 0.1 micrometers-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 with 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, and Cr, 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 dyes 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 binder resin. The binder resin used in 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 thermosetting resin or the like is preferable, and the same binder resin as that used in the recording layer can be suitably used. Among these, in order to improve durability at the time of repetition, a resin that can be cured by heat, ultraviolet rays, electron beams, or the like is preferably used, and a thermal crosslinking resin using an isocyanate compound or the like as a crosslinking agent is particularly preferable. In the binder resin, the hydroxyl value is preferably 100 mgKOH / g to 300 mgKOH / g.

The mixing ratio (mass ratio) of the light-to-heat conversion material and the binder resin in the light-to-heat conversion layer is such that the background is not colored by the light-to-heat conversion material, recording sensitivity is good, and sufficient coating strength is obtained. Moreover, 0.1-100 are preferable with respect to the photothermal conversion material 0.1. If the amount of the binder resin is too small, the heat intensity of the light-to-heat conversion layer may be insufficient. On the other hand, if the amount of the binder resin is too large, the recording sensitivity may be deteriorated.
There is no restriction | limiting in particular in the thickness of the said photothermal conversion layer, According to the objective, it can select suitably, It is preferable that they are 0.1 micrometer-20 micrometers.

-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 manner, 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.
Further, a part of the same surface or the entire surface of the thermoreversible recording layer of the thermoreversible recording medium, or a part of the opposite surface may be arbitrarily printed by offset printing, gravure printing, or an ink jet printer, a thermal transfer printer, a sublimation printer, or the like. A colored layer on which the above pattern or the like is formed may be provided, and an OP varnish layer mainly composed of a curable resin may be provided on a part or the entire surface of the colored layer.
Examples of the 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 form 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 includes the thermoreversible recording layer (recording layer) capable of reversible display and an information storage unit provided in (integrated with) the same card or tag, and a part of information stored in the information storage unit Is displayed on the recording layer, information can be confirmed simply by looking at a card or tag without a special device, which is excellent in convenience. Further, 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 thermoreversible recording layer capable of reversible display and an information storage unit. A suitable example of the information storage unit is an RF-ID tag.
FIG. 5 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 generates electromotive force by electromagnetic induction by a resonance action and a radio wave method 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 in combination with 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 equipped 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 transmission of electromagnetic waves. Is provided with a reader / writer for reading and rewriting the 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 light emitted from the CO ₂ laser is 10.6 μm in the far infrared region, and the thermoreversible recording medium absorbs the laser light. 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 wavelengths of the laser beams emitted from the YAG laser, the fiber laser, and the LD are in the visible to near infrared region (several hundred μm to 1.2 μm). Therefore, it is necessary to add a photothermal conversion material for absorbing laser light and converting it into heat. However, since the wavelength is short, there is an advantage that high-definition images 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 means 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 using a filter, a mask, or the like, the light irradiation intensity can be adjusted by 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.

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. 6A, two aspherical lenses are disposed on the optical path of the laser light emitted from the laser light emitting means. To do. Then, with the first aspheric lens L1, the ratio I ₁ / I ₂ is reduced with respect to the Gaussian distribution at the target position (distance 1) (in FIG. 6A, the flat top shape). 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. 6B, 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 conversely, 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. 6B, 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. 7 shows an example of the image processing apparatus of the present invention.
The image processing apparatus shown in FIG. 7 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 Co., Ltd.) 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. The laser light output from the laser oscillator 10 is scanned on the thermoreversible recording medium 7 by high-speed rotational scanning of two galvanometer mirrors 4A in the X-axis direction and the Y-axis direction attached to the galvanometer 4. 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. The cardboard with the label 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.

-First thermoreversible 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-

-Discoloration 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 phenolic antioxidant (Ciba Specialty Chemicals, IRGANOX565) and 5 parts by mass of isocyanate (Nihon Polyurethane Co., Ltd., Coronate HL) and stir well to apply for thermoreversible recording layer. A liquid was prepared.

  Next, the obtained coating liquid for thermoreversible recording layer was coated on a support using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a thickness of 6 μm. The first thermoreversible recording layer was formed.

-Photothermal conversion layer-
2.0 parts by mass of a 1% by mass solution of a phthalocyanine-based photothermal conversion material (manufactured by Nippon Shokubai Co., Ltd., IR-14), 3.6 parts by mass of an acrylic polyol 40% by mass solution (hydroxyl value = 200 mgKOH / g), and methyl ethyl ketone 6 .9 parts by mass and 1.7 parts by mass of isocyanate (trade name Coronate HL, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent were thoroughly stirred to prepare a photothermal conversion layer coating solution.
The obtained coating solution for photothermal conversion layer was applied on the first thermoreversible recording layer using a wire bar, heated and dried, and then cured at 60 ° C. for 24 hours to obtain a thickness of 4 μm. The photothermal conversion layer of was formed.

-Second thermoreversible recording layer-
The same composition for a thermoreversible recording layer as the first thermoreversible recording layer is applied onto the photothermal conversion layer using a wire bar, dried at 100 ° C. for 2 minutes, and then at 60 ° C. for 24 hours. Curing was performed to form a second thermoreversible recording layer having a thickness of 6 μm.

-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, the intermediate layer coating solution is applied onto the second thermoreversible recording layer with a wire bar, heated and dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 2 hours to obtain a thickness. A 2 μm intermediate layer was formed.

-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, the protective layer coating solution is applied onto the intermediate layer with a wire bar, heated and dried at 90 ° C. for 1 minute, and then crosslinked with an 80 W / cm ultraviolet lamp to provide a protective layer having a thickness of 4 μm. A layer was formed.

-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 liquid is applied to the surface of the support on which the thermoreversible recording layer or the like is not formed with a wire bar, heated and dried at 90 ° C. for 1 minute, and then 80 W / cm. A back layer having a thickness of 4 μm was formed by crosslinking with an ultraviolet lamp. 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 the support, a transparent PET film having a thickness of 175 μm (Lumirror 175-T12 manufactured by Toray Industries, Inc.) was used.

-Thermoreversible 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, 0.07 part by mass of a light-to-heat conversion material (Nippon Shokubai Co., Ltd., eXcolor IR-14) and 4 parts by mass of an isocyanate compound (Nihon Polyurethane Co., Ltd., Coronate 2298-90T) were added to the obtained dispersion. Was added to prepare a coating solution for a thermoreversible recording layer.
Next, the obtained coating solution for the thermoreversible recording layer is applied onto the support, heated and dried, and then stored in a 65 ° C. environment for 24 hours to crosslink the resin, and the thermoreversible having a thickness of 10 μm. A recording layer was formed.

-Protective layer-
A coating solution for a protective layer comprising 10 parts by mass of a 75% by mass butyl acetate solution of a urethane acrylate-based ultraviolet curable resin (Dainippon Ink Chemical Co., Ltd., Unidic C7-157) and 10 parts by mass of isopropyl alcohol is used. The film was applied on the thermoreversible recording layer with a bar, heated and dried, and then 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, a thermoreversible recording medium of Production Example 3 was produced in the same manner as Production Example 1, except that the photothermal conversion layer was not formed when producing the thermoreversible recording medium.

(Production Example 4)
-Production of thermoreversible recording media-
In Production Example 2, the thermoreversible recording medium of Production Example 4 was prepared in the same manner as Production Example 2 except that no photothermal conversion material was added to the coating liquid for the thermoreversible recording layer when the thermoreversible recording medium was produced. Was made.

(Production Example 5)
-Production of thermoreversible recording media-
In Production Example 1, a first oxygen barrier layer was formed between the support and the first thermoreversible recording layer, and a second oxygen barrier layer was formed between the second thermoreversible recording layer and the intermediate layer. Except for this, the thermoreversible recording medium of Production Example 5 was produced in the same manner as in Production Example 1.
-Formation of first and second oxygen barrier layers-
Add 5 parts by mass of urethane adhesive (TM-567 manufactured by Toyo Morton Co., Ltd.), 0.5 parts by mass of isocyanate (CAT-RT-37 manufactured by Toyo Morton Co., Ltd.), and 5 parts by mass of ethyl acetate, and stir well. Thus, an oxygen barrier layer coating solution was prepared.
Next, the oxygen barrier layer coating solution is applied with a wire bar onto a silica-deposited PET film (Mitsubishi Resin Co., Ltd., Tech Barrier HX, oxygen permeability: 0.5 ml / m ² / day / MPa). , Heated at 80 ° C. for 1 minute and dried, then laminated on the second thermoreversible recording layer and the support, heated at 50 ° C. for 24 hours, and 12 μm thick first and second oxygen. A barrier layer was formed.

(Production Example 6)
-Production of thermoreversible recording media-
In Production Example 1, a thermoreversible recording medium of Production Example 6 was produced in the same manner as in Production Example 1 except that RFID was placed on the surface of the support on which the thermoreversible recording layer or the like was not formed.

Example 1
Using the thermoreversible recording medium of Production Example 1, image processing was performed as follows and repeated durability was evaluated. The results are shown in Table 1.

-Image recording process-
As a laser, a 25 W fiber coupled high power semiconductor laser device (manufactured by LIMO, LIMO025-F100-DL808, equipped with a condensing optical system fθ lens (focal length: 150 mm), center wavelength: 808 nm, optical fiber core diameter: 100μm, NA: 0.11), and by changing the collimator lens optical axis that makes the laser light emitted from the fiber parallel light, an elliptical laser light that is long in the X-axis direction and short in the Y-axis direction is realized The ratio a / b of the major axis a to the minor axis b is 1.17, the laser output is adjusted to 10 W (X-axis direction, Y-axis direction), and the irradiation distance is 150 mm. Scanning is performed with respect to the thermoreversible recording medium of Production Example 1 at a scanning speed of 1,300 mm / s in the X-axis direction and 1,100 mm / s in the Y-axis direction. A line image was recorded in the Y-axis direction.
At this time, when the light intensity distribution in the laser beam was measured, the I ₁ / I ₂ value was 1.65.

-Image erasing process-
Subsequently, the laser device was used to adjust the laser output to 20 W, the irradiation distance of 195 mm, the spot diameter of 3 mm, and the scan speed of 1,000 mm / s, and the laser beam was scanned linearly at intervals of 0.59 mm. The image has been erased. At this time, the I ₁ / I ₂ value in the light intensity distribution in the laser light was 1.70.

<Evaluation of repeated durability>
The image recording step and the image erasing step are repeated, and finally the erasing step is performed, and an image of the reflection density of the erased portion printed on the thermoreversible recording medium in the overlapping portion of “X” and the other straight portion Evaluation was performed. The reflection density was measured by taking a gray scale (manufactured by Kodak) with a scanner (Canon, Canon Scan 4400), and measuring the obtained digital gradation value with a reflection densitometer (Macbeth, RD-914). The digital gradation value obtained by capturing 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.
The image recording process and the image erasing process are repeated, and the density of the erasure part is measured every 10 times.

<Laser beam intensity distribution measurement>
The laser beam shape and intensity distribution were measured according to the following procedure.
When a semiconductor laser device is used as the laser, first, a laser beam analyzer (Scorpion SCOR-0SCM, manufactured by Point Gray Research) is installed so that the irradiation distance is the same position as when recording on a thermoreversible recording medium. The beam was attenuated using a beam splitter (BEAMSTAR-FX-BEAM SPLITTER, manufactured by OPHIR) so that the output was 3 × 10 ^−6, and the laser beam intensity was measured with a laser beam analyzer. Next, the obtained laser beam intensity was converted 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) to measure the laser light intensity.

(Example 2)
In Example 1, a line image was recorded and erased in the same manner as in Example 1 except that the thermoreversible recording medium of Production Example 2 was used instead of the thermoreversible recording medium of Production Example 1. Similar to Example 1, repeated durability was evaluated. The results are shown in Table 1.

(Example 3)
In the same manner as in Example 1, the scanning power in the X-axis direction and the Y-axis direction is 1,200 mm / s, the irradiation power in the X-axis direction is 9.3 W, and the irradiation power in the Y-axis direction is 11 W. Line images were recorded and erased in the X-axis direction and the Y-axis direction on the thermoreversible recording medium, and the durability was repeatedly evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4
In the same manner as in Example 1, with an X-axis scanning speed of 1,250 mm / s and a Y-axis scanning speed of 1,150 mm / s, the X-axis irradiation power is 9.8 W, and the Y-axis irradiation power. The image was recorded and erased in the X-axis direction and the Y-axis direction on the thermoreversible recording medium of Production Example 1 at 10.5 W, and repeated durability was evaluated in the same manner as in Example 1. . The results are shown in Table 1.

(Example 5)
In the image recording process of Example 1, the focal length is changed to 160 mm and the laser output is 11 W (X-axis direction, Y-axis direction), and the I ₁ / I ₂ value is 2.00 in the light intensity distribution of the laser light. became. Other conditions were the same as in Example 1, and repeated durability was evaluated. The results are shown in Table 1.

(Example 6)
In the image recording process of Example 1, the focal length is changed to 144 mm and the laser output is 13 W (X-axis direction and Y-axis direction), and the I ₁ / I ₂ value is 0.40 in the light intensity distribution of the laser light. became. Other conditions were the same as in Example 1, and repeated durability was evaluated. The results are shown in Table 1.

(Example 7)
In the image recording step of Example 2, the focal length 163 mm, the laser output 11W (X-axis direction, Y axis direction) by changing, in the light intensity distribution of laser light, _I 1 / _{I 2} value of the image recording step is 2.05. Other conditions were the same as in Example 2, and repeated durability was evaluated. The results are shown in Table 1.

(Example 8)
In the image recording process of Example 2, the focal length is changed to 143 mm and the laser output is 14 W (X-axis direction, Y-axis direction), and the I ₁ / I ₂ value of the image recording process is changed in the light intensity distribution of the laser beam. It became 0.34. Other conditions were the same as in Example 2, and repeated durability was evaluated. The results are shown in Table 1.

Example 9
<Image recording process>
Using a laser marker (manufactured by Sunkus Co., Ltd., LP-440) equipped with a CO ₂ laser with an output of 40 W, an aspheric lens is incorporated in the optical path of the laser light, and the optical path is shifted from the optical axis of the aspheric lens. By adjusting the ratio, the I ₁ / I ₂ value in the light intensity distribution of the laser beam is 1.60, an elliptical shape that is long in the X-axis direction and short in the Y-axis direction (r / a) Was 1.19.
Next, the laser marker is used to adjust the irradiation distance to 198 mm, the laser output to 11 W (X-axis direction and Y-axis direction), and the irradiation distance to 150 mm, and the laser beam is scanned with a galvanometer mirror to scan in the X-axis direction. Line images were recorded in the X-axis direction and the Y-axis direction on the thermoreversible recording medium of Production Example 3 at 1,300 mm / s and a scanning speed of 1,100 mm / s in the Y-axis direction.
<Image erasing process>
Subsequently, the aspherical lens was removed from the optical path of the laser marker, and the laser output was adjusted to 22 W, the irradiation distance was 155 mm, the spot diameter was 2 mm, and the scan speed was 3,000 mm / s. Then, the image recorded on the thermoreversible recording medium was erased.
Next, repeated durability was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 10)
In the same manner as in Example 9, the scanning power in the X-axis direction and the Y-axis direction was 1,200 mm / s, the irradiation power in the X-axis direction was 10.2 W, and the irradiation power in the Y-axis direction was 12 W. Line images were recorded and erased in the X-axis direction and the Y-axis direction on the thermoreversible recording medium, and the durability was evaluated repeatedly in the same manner as in Example 9. The results are shown in Table 1.

(Example 11)
In the same manner as in Example 9, with an X-axis scanning speed of 1,250 mm / s and a Y-axis scanning speed of 1,150 mm / s, the X-axis irradiation power is 10.7 W, and the Y-axis irradiation power. A linear image was recorded and erased in the X-axis direction and the Y-axis direction on the thermoreversible recording medium of Production Example 3 at 11.5 W, and repeated durability was evaluated in the same manner as in Example 9. . The results are shown in Table 1.

(Example 12)
In Example 9, image recording and image erasing were performed in the same manner as in Example 9 except that the thermoreversible recording medium of Production Example 4 was used instead of the thermoreversible recording medium of Production Example 3. Similarly, repeated durability was evaluated. The results are shown in Table 1.

(Example 13)
In the same manner as in Example 1, the scanning power in the X-axis direction is 1,300 mm / s, the scanning speed in the Y-axis direction is 1,100 mm / s, and the irradiation power in the X-axis direction and the Y-axis direction is 12 W. Manufacturing Example 5 A linear image was recorded and erased in the X-axis direction and the Y-axis direction on the thermoreversible recording medium, and the durability was repeatedly evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 14)
In the same manner as in Example 1, the X-axis direction scanning speed is 1,300 mm / s, the Y-axis direction scanning speed is 1,100 mm / s, and the irradiation power in the X-axis direction and the Y-axis direction is 10 W. Production Example 6 A linear image was recorded and erased in the X-axis direction and the Y-axis direction on the thermoreversible recording medium, and the durability was repeatedly evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, except that recording was performed on the thermoreversible recording medium of Production Example 1 at a scanning speed of 1,100 mm / s in both the X-axis direction and the Y-axis direction, the same as in Example 1, Image recording and image erasure were performed, and the durability was evaluated repeatedly in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
In Example 2, except that recording was performed on the thermoreversible recording medium of Production Example 2 at a scanning speed of 1,100 mm / s in both the X-axis direction and the Y-axis direction, the same as in Example 2, Image recording and image erasure were performed, and the durability was repeatedly evaluated in the same manner as in Example 2. The results are shown in Table 1.

(Comparative Example 3)
In Example 9, except that recording was performed on the thermoreversible recording medium of Production Example 3 at a scanning speed of 1,100 mm / s in both the X-axis direction and the Y-axis direction, Image recording and image erasure were performed, and the durability was evaluated repeatedly in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
In Example 12, except that recording was performed on the thermoreversible recording medium of Production Example 4 at a scanning speed of 1,100 mm / s in both the X-axis direction and the Y-axis direction, Image recording and image erasure were performed, and the durability was evaluated repeatedly in the same manner as in Example 12. The results are shown in Table 1.

  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.

2 beam expander 4 galvanometer 4A galvanometer mirror 5 scanning unit 6 fθ lens 7 thermoreversible recording medium 10 laser oscillator 11, 12 drawing line 81 IC chip 82 antenna 85 RF-ID tag T bending portion

JP 2004-265247 A JP 2004-265249 A JP 2003-127446 A JP 2004-345273 A JP 2006-306063 A

Claims (9)

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 the image recording step, when the beam shape of the laser beam on the thermoreversible recording medium is non-circular, P / V (where V is the scanning speed of the laser beam) according to the scanning direction of the laser beam. , P represents the irradiation power of laser light), and image recording is performed.   The image processing method according to claim 1, wherein image recording is performed by changing only V in P / V according to a scanning direction of laser light.   The image processing method according to claim 1, wherein image recording is performed by changing only P in P / V according to a scanning direction of laser light.   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 processing method according to any one of claims 1 to 4, wherein the thermoreversible recording medium has at least a thermoreversible recording layer on a support, and the thermoreversible recording layer contains a resin and an organic low molecular weight substance. .   The image according to any one of claims 1 to 4, wherein the thermoreversible recording medium comprises at least a thermoreversible recording layer on a support, and the thermoreversible recording layer contains a leuco dye and a reversible developer. 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 80% of the total irradiation energy of the irradiated laser light. The image processing method according to claim ₁ , wherein the light irradiation intensity I ₂ satisfies the following formula: 0.40 ≦ I ₁ / I ₂ ≦ 2.00.   Light irradiation that is used in the image processing method according to any one of claims 1 to 7, and is arranged on a laser light emitting means and a laser light emitting surface of the laser light emitting means and changes a light irradiation intensity of the laser light. An image processing apparatus comprising at least intensity adjusting means.   The image processing apparatus according to claim 8, wherein the light irradiation intensity adjusting means is at least one of a lens, a filter, a mask, a fiber coupling, and a mirror.