WO1995020491A1 - Support d'enregistrement thermosensible reversible et procede de formation et d'effacement d'image - Google Patents
Support d'enregistrement thermosensible reversible et procede de formation et d'effacement d'image Download PDFInfo
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- WO1995020491A1 WO1995020491A1 PCT/JP1995/000103 JP9500103W WO9520491A1 WO 1995020491 A1 WO1995020491 A1 WO 1995020491A1 JP 9500103 W JP9500103 W JP 9500103W WO 9520491 A1 WO9520491 A1 WO 9520491A1
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- recording material
- reversible thermosensitive
- thermosensitive recording
- layer
- heat
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M5/00—Duplicating or marking methods; Sheet materials for use therein
- B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
- B41M5/36—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties
- B41M5/363—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties using materials comprising a polymeric matrix containing a low molecular weight organic compound such as a fatty acid, e.g. for reversible recording
Definitions
- the present invention relates to a reversible thermosensitive recording material and an image forming / erasing method capable of repeatedly forming and erasing an image by utilizing a reversible change in transparency of the thermosensitive layer depending on the temperature.
- thermosensitive recording materials that can temporarily form an image and erase the image when it is no longer needed have attracted attention.
- a typical example is a dispersion of a low-molecular organic substance such as a higher fatty acid in a resin base material such as a vinyl chloride monobutyl acetate copolymer.
- a reversible thermosensitive recording material provided with a heat-sensitive layer is known (JP-A-54-1193777, JP-A-55-154198, etc.). It has the drawback that the temperature range showing light and transparency is as narrow as 2 to 4 ° C, and it is difficult to control the temperature when forming images using light transmission, transparency, shading, and cloudiness. Was.
- the temperature range showing transparency is expanded by using a mixture of higher fatty acids and fatty acid esters as organic low-molecular substances in JP-A-63-39378. Suggests what you can do.
- these recording materials have a transparent temperature range of around 10 ° C, and the image can be erased (transparent) by heating for a relatively long time such as a reheat roller or hot plate. Although clearing was sufficiently possible, erasing (clearing) the image by short-time heating with a thermal head or the like was insufficient.
- the present inventors have made transparent by using a mixture of higher fatty acids and aliphatic saturated dicarboxylic acids in Japanese Patent Application Laid-Open Nos. 2-13663 and 3-20989.
- the temperature range has been extended to around 20 ° C, and the image can be erased (cleared) to some extent by heating with the thermal head, but it is sufficient if the heating time with the thermal head is still short. It was not.
- the present inventors have disclosed that the transparent temperature range is 30 ° C. by using a combination of three or more organic low-molecular substances having different melting points in JP-A-5-294066. Spreading back and forth, the erasure (transparency) was possible even with short-time application of thermal energy with a thermal head, but there was not enough.
- the present inventors disclosed in Japanese Patent Application Laid-Open No. 5-169980 that the resin matrix of the heat-sensitive layer had a degree of polymerization of 100 or more, and a unit of vinyl chloride / vinyl acetate. By using a unit whose weight ratio is specified as 90 Z 10 to 60/40, it has become possible to improve the erasing property over time during long-term storage after formation of a cloudy image.
- Japanese Patent Application Laid-Open No. 5-155107 discloses a method of correcting an erasing energy based on the elapsed time after forming a cloudy image and erasing an image.
- a recording device has been proposed, as described above, when the storage environment temperature is constant, the erasure characteristics are stabilized by erasure energy correction, but when the environmental temperature changes to low or high temperature, the erasure energy deviation is not constant, so the correction is made. If the amount is also energy correction amount with respect to the elapsed time c for this which must be changed are fixed, there is drawback that Li image erasability by the difference in environmental temperature becomes incomplete. Accordingly, an object of the present invention is to provide a reversible thermosensitive recording material which improves high-speed erasing characteristics, prevents changes in erasability over time, and has good repetition durability.
- Another object of the present invention is to provide an image forming and / or erasing method capable of high-speed image forming and Z or image erasing without fine control of a thermal head in image forming and / or image erasing by a thermal head.
- a heat-sensitive layer having a resin base material and an organic low-molecular substance dispersed in the resin base material as main components and having a transparency that reversibly changes depending on temperature is provided on a support.
- the reversible thermosensitive recording material is characterized in that the reversible thermosensitive recording material and the image formation / erasing method have a transparency change temperature change rate of 13% or less.
- thermosensitive layer whose main component is an organic low-molecular substance and whose transparency reversibly changes depending on temperature
- the degree of transparency change of the thermosensitive layer is 50% or more. It is characterized by.
- the present invention provides a heat-sensitive layer having, as a main component, a resin base material and an organic low-molecular substance dispersed in the resin base material, and a transparency that reversibly changes depending on a temperature on a support.
- the rate of change in the thickness of the thermosensitive layer is 2% or more.
- the present invention provides a heat-sensitive layer having a resin base material and an organic low-molecular substance dispersed in the resin base material as main components on a support, and having a transparency that reversibly changes depending on temperature.
- the provided method for forming and erasing an image on a reversible thermosensitive recording material having a rate of change of transparentization start temperature of 13% or less is characterized by forming a cloudy image and erasing a Z or cloudy image by heating.
- a heat-sensitive layer whose main component is a resin base material and an organic low-molecular substance dispersed in the resin base material and whose transparency reversibly changes depending on temperature is provided on the support.
- a method for forming and erasing an image on a reversible thermosensitive recording material having a transparency change rate of 50% or more is characterized by forming a cloudy image and heating or erasing the image by heating.
- a heat-sensitive layer having a resin base material and an organic low-molecular substance dispersed in the resin base material as main components on a support and having a transparency that reversibly changes depending on temperature is provided.
- a method for forming and erasing an image on a reversible thermosensitive recording material in which the rate of change in the thickness of the thermosensitive layer is 2% or more it is characterized in that a cloudy image is formed and / or a cloudy image is erased by heating.
- FIG. 1 is a diagram showing a change in transparency due to heat of a heat-sensitive layer according to the present invention.
- FIG. 2 is a schematic view of a transparency change rate measuring device.
- FIG. 3 is an enlarged perspective view of the ITO / A ⁇ substrate.
- FIG. 4 is a schematic device diagram for measuring the transparency of the thermosensitive layer film.
- FIG. 5 shows a hot stamp type air desktop TC film erasing device tester (made by Unique Machinery) as a heat and pressure applying device, (a) is a schematic front view of the device, and (b) is a front view of the device. (C) is a schematic view of a temperature control section of the apparatus.
- FIG. 6 is a print head of the apparatus shown in FIG. 5, wherein (a) is a front view and (b) is a side view.
- Fig. 7 shows the sample support when the thermal pressure applying device shown in Fig. 5 is used.
- FIG. 8 is an enlarged view of a portion to which a heat pressure is applied by the heat pressure application device shown in FIG.
- FIG. 9 is a schematic perspective view of a protective layer cutting device.
- FIG. 10 are diagrams showing the influence of a reversible thermosensitive recording material by a heating element in a conventional image display.
- FIG. 11 are diagrams showing various specific examples of an image erasing means in the thermographic image display device.
- FIG. 12 shows an example in which an image is formed and erased on a reversible thermosensitive recording material using a thermal head, a pressurizing means provided after the thermal head, and a guide roller.
- FIG. 14 (a) is a diagram showing the transmitted light intensity waveform output by the digital oscilloscope printer of the thermosensitive layer film obtained in Example 1 c .
- FIG. 14 (b) 6 is a diagram showing a transmitted light intensity waveform output by a digital oscilloscope printer of the heat-sensitive layer film obtained in Comparative Example 1.
- FIG. FIG. 15 is a graph showing the relationship between the erase density and the erase energy.
- thermosensitive recording material of the present invention The mechanism for changing the cloudiness and transparency of the reversible thermosensitive recording material of the present invention is presumed as follows.
- thermosensitive layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material Is, for example, T. At the following room temperature, it is cloudy and opaque.
- the temperature-transparency change curve shown in FIG. 1 is only a typical example, and when the material is changed, the transparency of each state may change depending on the material.
- the softening point of the resin and the deformation behavior at or above the softening point are important for the change in the transparency.
- the temperature ranges from ⁇ 2 to ⁇ 3 in FIG. Increase the transparency temperature range and soften It is considered necessary to increase the deformation speed above the point.
- the start of transparency is triggered by the softening of the resin.
- the clearing start temperature decreases, and when the heating time decreases, the starting temperature increases. It changes depending on the heating time. In other words, if the heating time is long, it is easy to soften, but if it is short, it is difficult to soften. Conversely, if the clearing start temperature does not change even if the heating time changes, the heating time Indicates that it is easy to soften even if it is short.
- the rate of change in the temperature at which the transparency starts is preferably 13% or less, preferably 10% or less, and more preferably 6% or less.
- the rate of change in temperature at which clarification starts is measured by the following method.
- a thermal gradient tester HG-100 manufactured by Toyo Seiki Seisaku-sho, Ltd. is used as a measuring device for the temperature at which the transparency starts.
- the printing timer of the thermal gradient tester is set to 60 seconds, and then the applied pressure is set so that the pressure gauge becomes 1 kgcm 2 .
- the heating temperature was changed in advance from 50 ° C to 1 ° C on a reversible thermosensitive recording medium that was in a cloudy state in advance, heated for 60 seconds at each heating temperature, and then cooled to room temperature.
- the reflection density is measured with a Macbeth reflection thermometer (RD-914). At this time, the reflection density is The lowest heating temperature when the value exceeds the value of 0.2 (OD) is defined as the transparency start temperature (T 60s ) at an application time of 60 seconds.
- the transparency start temperature under this condition is defined as the transparency start temperature (T ls ) at the application time of 1 second.
- the above-mentioned background density is obtained by using a thermostat at an arbitrary heating temperature so as to be in a state of maximum transparency, then measuring the reflection density of the reversible thermosensitive recording material at 10 points, and using the average value.
- the rate of change in the temperature at which the transparentization starts is determined by the following equation using the transparentization start temperatures T60s and Tls .
- Transparent initiation temperature change rate (%) [(IT ls -T 60 s I) / T 60s] X 100 T ls: applying time 1 second transparent initiation temperature (° C)
- the pressure and the temperature can be changed.
- the measurement of the transparency start temperature can be applied to both of the above-mentioned reversible thermosensitive recording materials, 1) those having only a recording layer (thermosensitive layer) and 2) those having a protective layer.
- the change of the reversible thermosensitive recording material of the present invention from cloudy to transparent is caused by a decrease in voids due to softening and shrinkage of the resin.
- clearing by heating in a short time of the order of several milliseconds indicates that the resin softens rapidly, that is, the deformation speed of the resin is low.
- the transparency change rate is preferably 50% or more, preferably 60% or more, and more preferably 70% or more.
- the transparency ratio is measured by the following method.
- the transparency change rate measuring device As the transparency change rate measuring device, the device shown in FIG. 2 is used.
- the transparency change rate measuring device is composed of an optical microscope 100 (Nikon Corp. PTI PHOT2-POL) having a light source unit and a transmitted light concentrating unit, and a transmitted light detecting unit.
- the I ⁇ substrate 101 has a heating element 101-3 consisting of an ITO film (about 2500 A film thickness) on a heat-resistant glass 101-1, as shown in Fig. 3.
- the electrode is formed by sputtering, and furthermore, the electrode 101-2 made of A ⁇ (film thickness: about 1.2 ⁇ m) is further provided by vacuum evaporation.
- a DC halogen lamp is used as the light source 102, and a current is supplied to the halogen lamp from a DC power supply (not shown).
- the digital oscilloscope 106 has a built-in printer, so that the change in transparency can be checked on the display and output can be made by the printer.
- the measurement conditions for measuring the rate of change in transparency are as follows: first, a heat-sensitive layer is formed at an arbitrary thickness on the support, and the heat-sensitive layer is formed using this reversible thermosensitive recording material. Heat and cool to the maximum opaque state and the maximum transparent state, and then peel off the film from the support to prepare two types of heat-sensitive layer films, a turbid state and a transparent state. Then, while setting the magnification of the objective lens of the optical microscope 100 in FIG. 2 to 4 ⁇ and checking the heating element portion (area l mm 2 ) 101-3 in FIG. Adjust the position so that it is at the center of the field of view, and then increase the magnification of the objective lens to 10 times so that only the heating element unit enters the field of view. In this way, the position of the ITO./A ⁇ substrate is adjusted.
- thermosensitive layer film 200 is placed on the I I ⁇ substrate 101, a slide glass 201 is placed thereon, and a weight 202 is further placed thereon. Put on. After setting the heat-sensitive layer in this manner, the transparency is measured as follows.
- the amount of transmitted light is adjusted by the dimming knob 110 in Fig. 2, and at the same time, the transmitted light is adjusted by the photomultimeter 104, the amplifier 105, and the digital oscilloscope 106. Adjust the detector so that a waveform representing the transmitted light intensity appears slightly below the center of the digital oscilloscope and display, and read the y-coordinate value where this waveform appears and read it again. This is defined as the static transparent transmitted light intensity (V ST ).
- the X coordinate of the digital oscilloscope is time (msec)
- the y coordinate is voltage (mV).
- the heat-sensitive layer film in the transparent state placed on the I TOZA ⁇ substrate was changed to the heat-sensitive layer film in the cloudy state described above, and the y-coordinate value was read under the same conditions except for the above.
- V sw static opacity transmitted light intensity
- switch on the switch box 107 shown in Fig. 2 and set the voltage of the DC power supply 108, and then set the pulse width of the personal computer 109 to 2 msec.
- ⁇ ⁇ / ⁇ Heats the heat-generating elements of the ⁇ -substrate 101 with a pulse width of 2 msec. Synchronized with the heat generated by the heating element, the transmitted light intensity when the white opaque state changes to the transparent state is taken into the digital oscilloscope, output to the display, and output to the printer.
- the transmitted light intensity in the cloudy state and the transmitted light intensity in the transparent state are read from these output waveforms, and then the position of the thermosensitive layer film is changed, and the voltage is changed. In the same way, it was confirmed that the difference between the transmitted light intensity in the cloudy state and the transmitted light intensity in the transparent state was the largest, and that the heating part was visually observed in the transparent state.
- the intensities are referred to as dynamic opacity transmitted light intensity (v DW ) and dynamic transparent transmitted light intensity (V DT ).
- the transmissivity change rate can be obtained by the following equation based on the transmitted light intensities v sw , V ST , V DW , and V DT .
- V sw Static turbid transmitted light intensity (mV)
- V ST Static transparent transmitted light intensity (mV)
- V DW Dynamic cloudy transmitted light intensity (mV)
- V DT Dynamic transparent transmitted light intensity (mV)
- This transparency measurement was performed for the reversible thermosensitive recording material described above, by 1) recording layer And 2) those with a protective layer.
- the above-mentioned support is a transparent support, the measurement can be performed without peeling off the heat-sensitive layer film.
- the change of the reversible thermosensitive recording material of the present invention from white turbidity to transparency is caused by a decrease in voids due to softening and shrinkage of the resin. Therefore, when changing from cloudy to transparent, the volume will be reduced by the amount of the gap.
- this change in volume does not appear largely in the direction parallel to the surface of the support but changes in the thickness direction.
- a large change in transmittance from white turbidity to transparent by short-time heating on the order of msec indicates a rapid change in the thickness of the heat-sensitive layer, that is, the deformation speed of the resin is high, In other words, the voids are reduced, resulting in faster transparency and shorter erasing time.
- the thickness change rate is preferably 20% or more, preferably 3% or more, and more preferably 4% or more.
- the rate of change in film thickness is measured by the following method.
- thermosensitive recording material used in the above-described transparency change rate measurement is used.
- the heat-sensitive layer is heated and cooled using a thermostat so that the thermosensitive layer is maximally opaque, thereby creating a medium with maximum opacity.
- thermosensitive layer in the cloudy state Rw
- thermosensitive layer is heated and cooled using a thermostat so that the thermosensitive layer becomes the maximum transparent state, the film thickness is measured in the same manner as described above, and an average value is calculated.
- Li film thickness change ratio by the R T and the transparency change rate CT (%) is calculated following formula Nyori.
- Thickness variation rate (%) [(RW- RT) (CT / 1 0 0) / Rw] X 1 0 0 R w: thermosensitive layer opaque state thickness (m)
- a non-contact type laser displacement meter can be used for the film thickness measurement.
- the measurement of the rate of change in film thickness can be applied to both of the above-mentioned reversible thermosensitive recording materials, 1) those having only a recording layer and 2) those having a protective layer.
- the heat-pressure step amount and the heat-pressure step change rate of the heat-sensitive layer as the image display portion in the reversible thermosensitive recording material are defined as follows.
- the thermal pressure difference is a physical property representing the hardness of the coating film when heated, and a smaller value indicates that the coating film is harder.
- the thermal pressure step amount is 40% or less, the improvement in durability against repeated image formation and erasure by a thermal head or the like becomes remarkable.
- the reason is considered to be that the ability to suppress the agglomeration and expansion of particles due to contact between organic low-molecular substance particles suddenly increases, and as a result, even when heat and pressure are applied by a thermal head or the like, the heat-sensitive layer It seems that the deformation is reduced.
- the thermal pressure step is measured by the following method.
- FIG. 5 (a) is viewed thermal pressure applying device from the front
- Fig. 5 (b) is a schematic diagram viewed from the side
- Fig. 5 (c) is a schematic diagram of a temperature control unit of the heat and pressure applying apparatus.
- the thermal pressure application device is an air regulator 303 as a pressure adjustment unit, a print timer 305 as a time adjustment unit, a temperature controller 312 as a temperature adjustment unit, And a print head section 301 as a heat and pressure applying section, and a sample support table 302 for supporting a recording material.
- the printing head 301 used for the measurement of the thermal pressure step is used, and the printing head shown in FIG. 6 is used.
- a ⁇ is used as the material of the print head, and the surface roughness of the part of the protrusion X in Fig. 6 that comes into contact with the surface of the heat-sensitive layer is as shown in the figure, and the surface roughness (Ry) is 0.8 ⁇ m.
- the area of the protrusion is 0.225 cm 2 .
- a 1 mm-thick fluorine film is placed on the ⁇ plate (302-1) as shown in FIG. 7 to prevent the pressure from being dispersed when applying heat and pressure to the sample support 302.
- a two-dimensional roughness analyzer surfcoder AY-41, recorder RA-60E and surfcoder SE30K manufactured by Kosaka Laboratory Co., Ltd. were used. ); 2000, lateral magnification (H); set to 20, then set the surf coder AY-41 to the reference length (L); 5 mm, re-transmission speed (D s); 0.1 mm / Set to sec, record the measurement result in RA-60E, and read the thermal pressure step value (Dx) of the thermal pressure applying unit using the recorded chart.
- H lateral magnification
- L reference length
- D s re-transmission speed
- Dx thermal pressure step value
- Measurements of Naoko changes the position at 2mm intervals for the width direction of the heat pressure applying portion (30 1 1) of the as represented in Figure 8, was measured for five points D 1 to D 5, the average value Heat pressure step average value (Dm).
- This heat pressure level difference average (Dm) and the heat-sensitive recording layer thickness (D B) Li heat pressure level difference by the (D) is calculated following formula Nyo Li.
- D m average value of thermal pressure step (/ zm)
- D B Thermal recording layer thickness
- the thermal pressure step change rate is a physical property representing the degree of change of the hardness of the coating film during heating with time. The smaller the numerical value, the more stable the coating film.
- the rate of change in the thermal pressure step is 70% or less, the effect of the present invention is remarkably exhibited.
- the stability of the erasability characteristic over time is remarkably exhibited because the coating film starts from this value.
- stability c thermal pressure step change rate is considered to particularly improve the thermal properties of is determined by the following equation.
- the initial thermal pressure step amount (D,) is a value measured first time after the image display section is formed, and does not have to be a value immediately after the formation. Then the Any time heat pressure level difference (DD) The initial and c they are the samples forming an image display unit in the same time the value measured after standing for 24 hours under 5 0 ° C environment It is needless to say that the values are measured and calculated according to the thermal pressure step measurement method described above.
- the thermal pressure step change ratio when the above condition (2. 5 k gZc m 2, 1 3 0 ° C) can not step pressure, it is possible to raise the temperature.
- the measurement of the thermal pressure step amount was performed in the above-described reversible thermosensitive recording medium, 1) only the recording layer, and 2) the protective layer. Applicable to both.
- the layer structure of the reversible thermosensitive recording material of the present invention is, as described in Japanese Utility Model Application Laid-Open No. 2-38776, a thermosensitive recording layer and a magnetic recording layer mainly composed of a magnetic material on a support. And a layer configuration in which at least a portion directly below the heat-sensitive recording layer or a portion of the support corresponding to the heat-sensitive recording layer is colored.
- a magnetic recording layer is provided on a support, a light reflection layer is provided thereon, and a heat-sensitive layer is provided thereon.
- the magnetic recording layer may be provided on the back surface of the support or provided between the support and the heat-sensitive layer. There is no problem.
- thermosensitive recording material Even with the layer structure of the reversible thermosensitive recording material as described above, there is no hindrance to the measurement of the thermal pressure difference, and even in such a structure, the heat and pressure can be applied to the surface of the thermosensitive layer by reheating. The measurement of the pressure step amount can be performed.
- the thicknesses of the reversible thermosensitive layer and the protective layer are checked by cross-sectional observation using TEM, SEM, etc. as described above, and then the thickness of the protective layer may be removed.
- the method for removing this protective layer is as follows: the recording material 401 having the above structure is fixed on a stainless steel plate support 402 with a thickness of 2 mm with the protective layer facing up.
- a surface cutting member 400 in which sandpaper (roughness 800) is wound around a 3.5 cm-diameter cylinder made of Machiyu, is placed on the protective layer described above so that the cylinder does not rotate. While supporting the object, translate it in a fixed direction (404). At this time from the normal direction
- the pressure for pressurizing is 1. 0 1. a 5 k gZcm 2, the mobile number, the first recording material 4 0 1 surface cutting thickness before advance determined by the electron micrometer (film thickness meter), the surface The thickness may be measured while cutting, and the surface may be cut repeatedly until the thickness of the protective layer is removed.
- the surface becomes rough after cutting the protective layer, but even in this case, it is possible to specify the heat-pressure applied part, so the heat-pressure step difference is not affected by the surface roughness. Measurement is possible.
- the protective layer is laminated on the recording layer as described above, an intermediate layer provided between the protective layer and the recording layer, or a printed layer provided on the protective layer, or a heat-resistant film on the recording layer Even in a configuration in which a layer or the like is attached, the surface of the recording layer can be exposed using the above-described method, and the measurement of the thermal pressure step can be performed.
- the gel fraction change rate of the resin forming the heat-sensitive layer in the reversible thermosensitive recording material of the present invention is a physical property representing the change degree of the cross-linking degree of the resin coating film constituting the heat-sensitive layer over time.
- the smaller the value the more stable the degree of crosslinking of the coating film.
- the gel fraction change rate is 110% or less, the hardness of the coating film and the stability of thermal physical properties are particularly remarkably improved. As a result, various properties such as the repetition durability of the recording medium and the erasing property over time are obtained. It is considered that the characteristics become stable.
- the gel fraction change rate is calculated by the following equation.
- G c (%) [I (Gx-G D ) / G l I] X 100
- the initial gel fraction value (G i) is the value measured first after the thermosensitive layer is crosslinked, and does not have to be the value immediately after crosslinking.
- the gel fraction value of the resin in the thermosensitive layer is preferably 30% or more, more preferably 50%, with respect to the effect of improving image durability and heat resistance by applying excess energy. It is more preferably at least 70%, particularly preferably at least 80%.
- a heat-sensitive layer is formed at an arbitrary thickness on a support, and after irradiating with an electron beam, the film is separated from the support and the initial weight of the film is measured.
- the membrane was sandwiched between a wire mesh of 400 mesh, immersed in a solvent in which the resin before crosslinking was soluble for 24 hours, dried in vacuum, and the weight after drying was measured.
- the gel fraction is calculated by the following equation.
- the weight ratio of the organic low-molecular substance is calculated by calculating the area ratio occupying a unit area and the specific gravity of the resin and the organic low-molecular substance.
- the gel fraction value may be calculated.
- thermosensitive layer when a reversible thermosensitive layer is provided on a support, and the above-mentioned other layer is laminated thereon, or as described above between the support and the thermosensitive layer
- the film thickness of the reversible thermosensitive layer and other layers is checked by observing the cross-section of the above-mentioned TEM, SEM, etc., and other layers are obtained by using the above-described method.
- the surface of the reversible thermosensitive layer may be exposed by shaving the surface for the thickness of the layer, and the reversible thermosensitive layer may be peeled off, and the gel fraction may be measured in the same manner as the above-mentioned measuring method.
- the calculation may be performed excluding the weight of the organic low-molecular substance as described above.
- the film thickness is measured. If the resin matrix surrounding the organic low-molecular substance is completely cross-linked, the film thickness will not change even after immersion in the solvent. No need to consider.
- the first method when measuring a layer in which another layer is provided on the reversible thermosensitive layer as described above by these methods, the first method may be the same as the above-described measurement method. Since the second and third methods are based on film thickness measurement, only the layer laminated on the reversible thermosensitive layer needs to be measured.
- the present inventors analyzed and examined the mechanism of why the image density / contrast etc. caused by the repeated use of image formation and erasing on a reversible thermosensitive recording material would be reduced. did.
- a heating element such as a printer for a thermal destruction type thermal recording material on a thermal destruction type thermal recording material
- the following phenomenon was observed in the c- resin.
- a reversible thermosensitive recording material that has a recording layer in which organic low-molecular substance particles are dispersed in a base material, record when energy is not applied or when the number of repetitions is small when forming and erasing images with a heating element.
- the recording layer of the present invention maintains the uniform dispersion state of the organic low-molecular substance particles even by repeated recording and erasing.
- the image forming means such as a heating element
- stress is applied to the inside of the recording layer.
- this stress is the main cause
- Fig. 10 (b) As shown in (1), distortion occurs in the recording layer in the direction of energy application, and the organic low-molecular substance particles are deformed.
- the inventors of the present invention set the thermal pressure step amount of the heat-sensitive layer of the reversible thermosensitive recording material to 40% or less and the thermal pressure step change rate to 70% or less. It has been found that the objects of the present invention are more preferably achieved.
- the preferred embodiment in this case is as follows.
- thermosensitive layer in the reversible thermosensitive recording material When the thermal pressure step of the thermosensitive layer in the reversible thermosensitive recording material is set to 40% or less, it tends to particularly contribute to the improvement of the above-mentioned repetition durability.
- the recording material of the present invention has a very small thermal pressure step difference in the heat-sensitive layer as compared with the conventional recording material, that is, the heat-sensitive layer has extremely excellent heat resistance and mechanical strength.
- the heat-sensitive layer has extremely excellent heat resistance and mechanical strength.
- the thermal pressure step amount is preferably 40% or less, and more preferably 30%. less than / o, more preferably less than 25%, particularly preferred Or less than 20%.
- the rate of change in the thermal pressure step of the heat-sensitive layer is set to 70% or less, it tends to contribute to stabilization of the erasing characteristics particularly with time.
- the recording material of the present invention has a very small rate of change in the thermal pressure difference of the heat-sensitive layer, that is, it is considered that the physical properties of the heat-sensitive layer do not change between the initial time and the time. It is presumed that there is no change in the erasing characteristics and the erasing characteristics become stable.
- the rate of change in the thermal pressure step is preferably 70% or less, preferably 50% or less, more preferably 45% or less, and particularly preferably 4% or less. 0% or less.
- the resin used in the reversible thermosensitive recording layer is important for reducing the thermal pressure difference to 40% or less. When this resin is heated to a high temperature, it must maintain a certain degree of hardness.
- Specific examples include using a resin having a high softening temperature, using a resin having a high softening temperature in the main chain, using a resin having a low softening temperature in the side chain, or crosslinking the resin. In particular, it is preferable to crosslink the resin.
- the resin contained in the reversible thermosensitive layer of the reversible thermosensitive recording material is crosslinked, and the gel fraction change rate of the resin is set to 110% or less.
- the object of the present invention is achieved.
- the gel fraction value of the resin is set to 30% or more, more preferably, a crosslinking agent is added for crosslinking, and further preferably, crosslinking is performed by irradiation with an electron beam or ultraviolet rays.
- the gel fraction change rate is very small, that is, the above-mentioned change with time in the degree of curing is very small. This is presumed to stabilize the erasing characteristics described above.
- the gel fraction change rate is preferably 110% or less, preferably 90% or less, more preferably 70% or less, and particularly preferably 50% or less. is there.
- the gel fraction value when the resin is crosslinked is high, it is considered that the heat resistance and the mechanical strength of the image display portion described above are further improved. It is presumed that the durability against repetition, the print marks on the image display area, and the crack resistance will be further improved.
- the gel fraction value is preferably 30% or more, preferably 50% or less, and more preferably 70% or less.
- the method of cross-linking the resin contained in the reversible thermosensitive layer can be performed by heating, ultraviolet irradiation (UV irradiation), or electron beam irradiation (EB irradiation). It is electron beam irradiation, more preferably electron beam irradiation.
- UV irradiation ultraviolet irradiation
- EB irradiation electron beam irradiation
- UV curing requires a photopolymerization initiator and photosensitizer, and UV is limited to those that are almost transparent.
- the radical reaction rapidly progressed due to the high radical concentration, and the polymerization was completed instantaneously.
- energy was larger than that in UV.
- the cured film thickness can be increased.
- the UV curing requires a photopolymerization initiator and a photosensitizer, and since these additives remain in the recording layer after the crosslinking reaction, image formation, erasing, and repetition of the recording layer are performed.
- the present invention has been made based on these findings.
- the softening point of the resin By setting the softening point of the resin to a lower temperature side, there is an effect of increasing the transparency temperature range. Therefore, the softening point is preferably 70 ° C. or less, more preferably 65 ° C. or less, and particularly preferably 60 ° C. or less. In this case, the lower limit is preferably higher than the crystallization temperature of the organic low-molecular substance at the time of cloudiness.
- thermomechanical analyzer TMA
- dynamic viscoelasticity measuring apparatus without peeling the recording layer formed as described above.
- the resin having a low softening point examples include a resin having a long side chain and a resin obtained by copolymerizing a resin having a low softening point.
- the side chain of the resin having a long side chain preferably has 3 or more carbon atoms in terms of an alkyl group. Further, there may be an ether bond ester bond or the like in the side chain. Further, a carboxyl group ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ hydroxyl group may be present at the terminal of the side chain.
- Examples of such a vinyl chloride-butyl ester copolymer include the following.
- butyl chloride-indene sulfonic acid copolymer Vinyl chloride-vinylperoxylate copolymer
- the structure of the above-mentioned bullet ester may be such that a linear normal form is branched.
- the vinyl chloride-ethylene copolymer used in the present invention preferably has an ethylene content of 1% or more, more preferably 2% or more, from low ethylene grade to high-tech ethylene grade. And particularly preferably 4%. As the ethylene content increases, the softening temperature shifts to a lower temperature, so that a higher ethylene content is preferred.
- examples of the resin having a low softening point include a chlorobirubier ether copolymer represented by the following general formula (I).
- the alkyl group of the butyl alkyl ether preferably has 3 or more carbon atoms.
- resins may be used alone or in combination of two or more. Further, these resins may be used in combination with the following resins.
- Polyvinyl chloride vinyl chloride such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-butyl acetate-butyl alcohol copolymer, vinyl chloride-butyl acetate-maleic acid copolymer, and vinyl chloride-acrylate copolymer Copolymers; polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, fat, vinylidene chloride-based copolymers such as vinylidene chloride-acrylonitrile copolymer Copolymer; Polyester; Polyamide; Polyacrylate or polymethacrylate or atalylate, methacrylate copolymer; Silicone tree, polyethylene, polypropylene, polystyrene, polyacrylamide, polybutylpyrroli Don, natural rubber, polyvinyl alcohol, polyacrolein, polycarbonate and the like.
- the organic low-molecular substance may be in the form of particles in the recording layer, and generally has a melting point of about 30 to 200 ° C, preferably about 50 to 150 ° C.
- organic low molecular weight substances include alkinol; alkanediol; halogenalkinol or halogenalkanediol; alkylamine; alkin; alkene; alkyne; halogenalkanoin; halogenanoleken; Cycloanolecan; cycloanoleken; cycloalkyne; saturated or unsaturated mono- or dicarboxylic acids or their esters, amides or ammonium salts; saturated or unsaturated halogen-fatty acids or their esters, amides or ammonium salts Arylcarboxylic acids or their esters, amides or ammonium salts; halogenarylcarboxylic acids or their esters, amides or ammonium salts; thioal
- the Anmoyuumu salts; the c these which include carboxylic acid esters of Chio alcohol is used alone, or two or more. These compounds have a carbon number of 10 to 60, preferably 10 to 38, particularly preferably 10 to 30.
- the alcohol group in the c- ester may be saturated or not saturated. And may be halogen-substituted.
- the organic low molecular weight substance contains at least one of oxygen, nitrogen, sulfur and halogen in the molecule, e.g.
- a compound containing —OH, —COOH, —CONH—, —COOR, —NH—, —NH 2 , —S—, —S—S—, —O—, halogen, or the like is preferable.
- the transparency temperature range can be further expanded.
- the difference between the melting points of the low-melting point organic low-molecular substance and the high-melting point organic low-molecular substance is preferably 20 ° C. or more, more preferably 30 ° C. or more, and particularly preferably 40 ° C. or more.
- the low-melting organic low-molecular substance those having a melting point of 40 ° C. or more and less than 100 ° C. are preferable, and those having a melting point of 50 ° C. to 80 ° C. are more preferable.
- the high-melting organic low-molecular substance preferably has a melting point of 100 ° C. or higher, more preferably 110 ° C.
- the low melting point organic low molecular weight substance used in the present invention the following fatty acid esters, dibasic acid esters, and polyhydric alcohol difatty acid esters are preferable. A mixture of two or more is used.
- the fatty acid ester used in the present invention has a characteristic that the melting point of fatty acids having the same carbon number (in a state of being associated with two molecules) is low, and conversely, the fatty acids having the same melting point have more carbon atoms than fatty acids having the same melting point.
- Deterioration due to repeated printing and erasing of images with the thermal head is considered to be caused by a change in the dispersion state of the organic low-molecular substance particles due to compatibility between the resin base material and the organic low-molecular substance during heating.
- the compatibility between materials and organic low-molecular-weight substances decreases as the number of carbon atoms in the organic low-molecular-weight substances increases, and the deterioration of image print-erasure decreases. It is thought that there is not. Furthermore, the cloudiness tends to increase in proportion to the carbon number.
- thermosensitive recording materials with the same clearing temperature (near the melting point)
- the use of fatty acid esters as organic low-molecular substances dispersed in the resin matrix compared to the case of using fatty acids. It is thought that the opacity is high, that is, the contrast is high, and the durability is improved repeatedly.
- the transparency temperature range can be widened, and the erasing performance with a thermal head is high. Even if the erasing characteristics fluctuate slightly, erasing is possible, and the durability can be repeatedly improved due to the characteristics of the material itself.
- the fatty acid ester used in the present invention is represented, for example, by the following general formula (II).
- R 2 represents an alkyl group having 10 or more carbon atoms.
- the fatty acid ester preferably has 20 or more carbon atoms, more preferably 25 or more carbon atoms, and particularly preferably 30 or more carbon atoms. As the number of carbons increases, the degree of turbidity increases and the durability is improved repeatedly.
- the fatty acid ester preferably has a melting point of 40 ° C. or higher.
- the dibasic acid ester may be either a monoester or a diester, and is represented by the following general formula (III).
- R and R ′ represent a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, and R and R ′ may be the same or different. Exclude.
- n an integer of 0 to 40.
- the alkyl group of R and R ′ preferably has 1 to 22 carbon atoms, and n has preferably 1 to 30 and more preferably 2 to 20. .
- the melting point is preferably 40 ° C. or higher.
- succinic acid ester adipic acid ester, sebacic acid ester, 1-18-octacamethylene dicarboxylic acid ester and the like.
- Examples of the polyhydric alcohol difatty acid ester of the organic low molecular weight substance used in the present invention include those represented by the following general formula (IV). CH 3 (CH 2 ) m- 2 C00 (CH 2 ) nOOC (CH 2 ) m- 2 CH 3 (IV) (wherein n is 2 to 40, preferably 3 to 30, more preferably 4 to Is an integer of 22. m is an integer of 2 to 40, preferably 3 to 30, and more preferably 4 to 22.)
- Polyhydric alcohol difatty acid esters have the characteristic of having a lower melting point than fatty acids when compared at the same carbon number, and conversely having a higher carbon number than fatty acids when compared at the same melting point.
- the repetitive durability of printing with the thermal head is considered to be due to the compatibility of the resin and the organic low-molecular substance during heating.
- the compatibility of the resin and the organic low-molecular substance is the carbon of the organic low-molecular substance. It is thought that the higher the number, the lower the turbidity is in proportion to the carbon number and tends to increase. Therefore, by using polyhydric alcohol difatty acid ester, the same clearing temperature (around the melting point) It is thought that the durability of the reversible thermosensitive recording material is repeatedly improved as compared with the fatty acid.
- polyhydric alcohol difatty acid esters have low melting points, and have properties similar to those of high melting point fatty acids in terms of turbidity and repeated durability.
- the transparency temperature range can be extended while maintaining the same degree of white turbidity and repeated durability as when fatty acids are used.
- Thermal head Can improve image erasure (transparency) by heating in a short period of time, and even if the image erasure energy fluctuates over time due to an increase in the margin for image erasure, the Erasing with the thermal head is also possible without any problem.
- examples of the high-melting organic low-molecular substance used in the present invention include an aliphatic saturated dicarboxylic acid, a ketone having a higher alkyl group, a semicarbazone derived from the ketone, and an ⁇ -phosphono fatty acid. These are preferred, but not limited thereto.
- organic low-molecular substances having a melting point of 100 ° C. or higher are shown below.
- aliphatic dicarboxylic acid having a melting point of about 100 to 135 ° C. include, for example, succinic acid, daltaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacine.
- Acid pendecanedioic acid, dodecandioic acid, tetradecandioic acid, pentadecandioic acid, hexadecandioic acid, heptadecanoic acid, octadecandioic acid, nonadecandioic acid, eicosandioic acid, heneicosandioic acid, docosanedioic acid, etc.
- the ketone used in the present invention contains a ketone group and a higher alkyl group as essential constituent groups, and may further contain an unsubstituted or substituted aromatic ring or a substituted ring.
- the total carbon number of the ketone is preferably 16 or more, and more preferably 21 or more.
- the semicarbazone used in the present invention is derived from the above ketone.
- Ketones and semicarbazones used in the present invention include, for example, those shown below. 3—Octadecanone
- the ⁇ -phosphono fatty acid used in the present invention may be, for example, Hell-V according to the method of EV Kaurer et al., J. Ak. Oi 1 Chekist's Soc, 41, 205 (1964).
- a -brominated acid bromide by bromination by the olhard-Zelinskin reaction, followed by addition of ethanol to obtain an ⁇ -promofatty acid ester, followed by heating and reaction with triethylphosphite to form an ⁇ -phosphonofatty acid ester, and hydrolyzing with concentrated hydrochloric acid It can be obtained by performing decomposition and recrystallizing the product from toluene.
- the mixing weight ratio of these low-melting point organic low-molecular substances and high-melting point organic low-molecular substances is preferably 95: 5 to 5:95, and more preferably 90:10 to: L 0:90. And preferably 80:20 to 20:80.
- other organic low molecular weight substances described above may be mixed and used.
- These compounds include higher fatty acids such as lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, araginic acid and oleic acid;
- ethers such as CH ; and thioethers.
- higher fatty acids having 16 or more carbon atoms such as higher fatty acids such as palmitic acid, pentadecanoic acid, nonadecanoic acid, araquinic acid, stearic acid, behenic acid, and lignoceric acid are preferable in the present invention, and higher fatty acids having 16 to 24 carbon atoms are preferable. Fatty acids are more preferred.
- the organic low-molecular substance described in this specification may be appropriately combined, or such an organic low-molecular substance may be combined with another material having a different melting point.
- These are disclosed in, for example, JP-A-63-39378, JP-A-63-130380, Japanese Patent Application No. 63-147475, Japanese Patent Application No. It is disclosed in the specification such as 3-209, but is not limited thereto.
- the ratio between the organic low-molecular substance and the resin (the resin having a cross-linked structure) in the recording layer is preferably about 2: 1 to 1:16, more preferably 1: 2 to 1: 8 by weight.
- the ratio of the resin is less than this, it becomes difficult to form the organic low-molecular-weight substance in a film holding the resin, and if it exceeds this ratio, the opacity becomes difficult because the amount of the organic low-molecular-weight substance is small. Become.
- thermosensitive recording material used in the present invention generally, (1) a solution in which two components of a resin matrix and an organic low-molecular substance are dissolved, or (2) a solution of a resin matrix (an organic solvent is used as a solvent). Apply a dispersion of organic low-molecular substances dispersed in fine particles on a support such as a plastic film, a glass plate, or a metal plate, and dry and laminate.
- the heat-sensitive layer may be formed.
- the solvent for preparing the heat-sensitive layer or the heat-sensitive recording material can be variously selected depending on the type of the resin base material and the organic low molecular weight substance. , Toluene, benzene and the like. Not only when a dispersion is used, but also when a solution is used, in the heat-sensitive layer obtained, the organic low-molecular-weight substance is precipitated as fine particles and exists in a dispersed state. ⁇ 30 m, preferably 2-20 ⁇ m New If the recording layer is too thick, heat distribution will occur in the layer, making it difficult to achieve uniform transparency. On the other hand, if the recording layer is too thin, the turbidity decreases and the contrast decreases. Further, the turbidity can be increased by increasing the amount of the organic low molecular weight substance in the thermosensitive layer.
- additives such as a surfactant and a plasticizer can be added to the recording layer in order to facilitate formation of a transparent image.
- additives such as a surfactant and a plasticizer.
- plasticizer examples include a phosphoric acid ester, a fatty acid ester, a phthalic acid ester, a dibasic acid ester, a glycol, a polyester-based plasticizer, and an epoxy-based plasticizer.
- surfactants and other additives Polyhydric alcohol higher fatty acid ester; polyhydric alcohol higher alkyl ester; polyhydric alcohol higher fatty acid ester, higher alcohol, higher alkyl phenol, higher fatty acid higher alkylamine, higher fatty acid amide, oil or polypropylene Xide adduct Acetylene glycol; Na, Ca, Ba, or Mg salt of higher alkylbenzene sulfonic acid; aromatic carboxylic acid, higher fatty acid sulfonic acid, aromatic sulfonate, sulfuric acid monoester or monophosphate or phosphoric acid Di-ester Ca, Ba or Mg salt; low-sulfated oil; poly long-chain alkyl acrylate; acryl-based oligomer; poly long-chain alkyl methacrylate; long-chain alkyl methacrylate monoamine-containing monomer copolymer; Styrene-maleic anhydride copolymer; Etc. In maleic anhydride copoly
- heating can be performed, or ultraviolet irradiation or electron beam irradiation can be used.
- the method for crosslinking is specifically as follows. (I) a method using a crosslinkable resin, (ii) a method by adding a crosslinking agent, (iii) a method of crosslinking by irradiation of ultraviolet rays or electron beams, and Uv) an ultraviolet ray in the presence of a crosslinking agent. Or a method of crosslinking by irradiation with an electron beam.
- crosslinking agent examples include non-functional monomers and functional monomers, and specific examples thereof include the following.
- TPMA Trimethylolpropane trimethacrylate
- EMA 2-Ethoxytyl methacrylate
- crosslinking agents are used alone or in combination of two or more.
- the addition amount of these crosslinking agents is preferably 0.00000 parts by weight, more preferably 0.01 to 0.5 parts by weight, per 1 part by weight of the resin. Attachment If the added amount is less than 0.01 part by weight, the crosslinking efficiency will be poor, and if it is more than 1.0 part by weight, the turbidity will be reduced and the contrast will be reduced.
- a non-functional monomer is preferably a polyfunctional monomer, and more preferably a monofunctional monomer.
- crosslinking agents such as the following when using ultraviolet radiation as a means of crosslinking the resin in the heat-sensitive layer in the multi-functional monomer is preferably c the next invention, the photoinitiator may be used photopolymerization accelerator. Specific examples include the following, but are not limited thereto.
- the cross-linking agent can be broadly classified into a photopolymerizable polypolymer and a photopolymerizable monomer.
- the photopolymerizable monomer is a monofunctional monomer or a polyfunctional monomer mentioned above as the cross-linking agent used in electron beam irradiation. The same can be mentioned.
- examples of the photopolymerizable polypolymer include polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligoacrylate, alkyd acrylate, and polyol acrylate.
- crosslinking agents are used alone or in combination of two or more.
- the addition amount of these crosslinking agents is preferably from 0.01 to 1.0 part by weight, more preferably from 0.01 to 0.5 part by weight, based on 1 part by weight of the resin. If the added amount is less than 0.001 part by weight, the crosslinking efficiency will be poor, while if it is more than 1.0 part by weight, the turbidity will be reduced and the contrast will be reduced.
- photopolymerization initiators can be roughly classified into radical reaction type and ion reaction type. Further, the radical reaction type is classified into a photocleavage type and a hydrogen abstraction type. Specific examples include the following.
- benzoin ethers include isobutyl benzoin ether, isopropynole benzoin ether, benzoin ethinole ether, benzoin methyl ether, and the like.
- benzyl ketals such as 2,2-propanedione-1- (0-ethoxycarbonyl) oxime, 2,2-dimethoxy-12-pheninoleacetophenone, benzinole, and hydroxycyclohexylphenol
- acetophenone derivatives include ethoxy acetophenone, 2-hydroxy-12-methyl-11-phenylpropane-11-one
- ketones (ketone-amines) include benzophenone and Thioxanthone, 2-cloth thioxanthone, isopropylpropylthio Xanthone, 2-methyl thioxanthone, these photoinitiators c such as chlorine-substituted base Nzofuenon may be used alone or in combination.
- the effect of improving the curing rate is higher than that of hydrogen-abstraction type photopolymerization initiators such as benzophenone and thioxanthone, and aromatic tertiary amines and aliphatic amines.
- hydrogen-abstraction type photopolymerization initiators such as benzophenone and thioxanthone, and aromatic tertiary amines and aliphatic amines.
- photopolymerization accelerators are used alone or in combination of two or more.
- the addition amount is preferably from 0.1 to 5 parts by weight, more preferably from 0.3 to 3 parts by weight, based on 1 part by weight of the photopolymerization initiator.
- the ultraviolet irradiation device used in the present invention includes a light source, a lamp, a power supply, a cooling device, and a transfer device.
- the light source includes a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp, and a light source having an emission spectrum corresponding to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator described above. Should be used.
- the lamp output and the transport speed may be determined according to the irradiation energy required for crosslinking the resin.
- the electron beam irradiation method particularly effective for crosslinking the resin of the thermosensitive layer of the reversible thermosensitive recording material is as follows.
- EB irradiators can be broadly classified into two types: scanning type (scan beam) and non-scanning type (area beam).
- the EB irradiator can be determined according to the purpose such as irradiation area and irradiation dose.
- the EB irradiation conditions are determined from the following formula in consideration of the electron flow, irradiation width, and transport speed, according to the dose required for crosslinking the resin.
- the electron flow rating is selected to be 20 to 30 mA for experimental devices, 50 to 100 mA for pilot machines, and 100 to 500 mA for production machines.
- the dose required to crosslink the resin depends on the type and degree of polymerization of the resin, the type and amount of the crosslinking agent, the type and amount of the plasticizer, etc. Since the gel fraction of the reversible thermosensitive recording material is not constant, the recording layer is formed by determining the constituent factors of the thermosensitive layer of these reversible thermosensitive recording materials, the gel fraction target value is determined, and the dose corresponding to the gel fraction is determined. You can decide.
- the irradiation dose prevents the support or the resin from being deformed or thermally decomposed by the heat generated by the irradiation. For this reason, it is preferable to divide the irradiation into a plurality of irradiations to prevent a high heat from being applied by one irradiation.
- the organic low-molecular substance contained in the recording layer is heated to a temperature higher than a melting temperature, and then cross-linking is performed. It is preferable to crosslink after heating to a temperature higher than or equal to a predetermined temperature.
- thermosensitive layer constituent factors The relationship between the respective thermosensitive layer constituent factors and the gel fraction is as described above.
- the above-mentioned resins can be selected as the type of resin, but the degree of polymerization of these resins increases as the average degree of polymerization (P) increases.
- the type and amount of the crosslinking agent are the same as described above, and the type of the plasticizer is preferably a fatty acid ester, a polyester-based plasticizer, an epoxy-based plasticizer, or the like among the above-described plasticizers.
- epoxy plasticizers are optimal in view of irradiation discoloration and crosslinking efficiency.
- the amount of the plasticizer added tends to increase the gel fraction with an increase in the amount of the plasticizer, and is preferably from 0.01 to 1.0 part by weight, more preferably from 0.1 to 1.0 part by weight, per part by weight of the resin. It is 0.5 to 0.5 parts by weight.
- thermomechanical analyzer TMA
- dynamic viscoelasticity measuring device TMA
- the measurement can be performed by a rigid pendulum method dynamic viscoelasticity measuring apparatus without peeling the recording layer formed as described above.
- the smaller the variation over time the smaller the variation of the erasing characteristic over time.
- the penetration measurement method is as follows: using the recording layer formed on the support, using the TMA used for measuring the softening temperature, and placing a probe (needle probe) with a small tip cross-sectional area on the recording layer. A load can be applied, heated as needed, and the displacement can be measured.
- the method for measuring the residual amount includes the following method.
- the ATR measurement attachment attached to the Fourier transform infrared spectrophotometer was used as the measurement device, and the thermosensitive layer coating film used for the gel fraction measurement was used as the measurement sample.
- the strength of the absorption band is proportional to the residual amount of the cross-linking agent. If the residual amount is reduced, the strength is also reduced, so that the residual amount can be known.
- the residual amount is preferably not more than 0.2 part by weight, preferably not more than 0.1 part by weight, more preferably not more than 0.05 part by weight based on 1 part by weight of the resin in the heat-sensitive layer. Particularly preferably, it is 0.01 part by weight or less.
- the remaining amount of the photopolymerization initiator, photosensitizer used in UV curing, and the catalyst used in heat curing can also be known.
- the analysis it is possible to determine which of the EB curing, the UV curing, and the thermal curing was used for the crosslinking of the resin in the heat-sensitive layer.
- the lower the residual component the better the durability.
- this measurement method can obtain knowledge only of a thin layer on the order of several m on the surface of the coating film, it is possible to directly measure the heat-sensitive layer formed on the support.
- the image density in the cloudy state is improved, This has the effect of improving the contrast.
- the effect is more remarkable when the size of the air gap is 1/10 or more of the wavelength of light used to detect the opaque state.
- thermosensitive recording material of the present invention When an image formed on the reversible thermosensitive recording material of the present invention is used as a reflection image, it is desirable to provide a light reflecting layer on the back surface of the recording layer. Also, if a reflective layer is provided, the thickness of the recording layer can be reduced and the contrast can be greatly increased. Specific examples include vapor deposition of A 1, Ni, Sn and the like (described in JP-A-64-17979).
- the recording layer may be provided with a protective layer for protecting the recording layer.
- a protective layer for protecting the recording layer.
- materials for the protective layer include silicone rubber, silicone resin (Japanese Patent Application Laid-Open No. Sho 63-221807), polysiloxane graft polymer (Japanese Patent Application (See Japanese Patent Application Laid-Open No. 63-31,738) and UV curable resin or electron beam curable resin (described in Japanese Patent Application No. 2-5666).
- a solvent is used at the time of coating, but it is preferable that the solvent does not easily dissolve the resin of the recording layer and the organic low molecular weight substance.
- alcohol solvents are desirable from the viewpoint of cost.
- These protective layers can be cured at the same time as crosslinking the resin of the recording layer.
- a protective layer is applied and dried, and thereafter, electron beam irradiation is performed using the EB irradiation apparatus and irradiation conditions described above. Should be cured.
- an intermediate layer can be provided between the protective layer and the recording layer in order to protect the recording layer from a solvent, a monomer component, and the like of the protective layer forming solution (Japanese Patent Application Laid-Open No. 1-133787). Gazette).
- the following thermosetting resins and thermoplastic resins can be used in addition to those listed as the material of the resin base material in the recording layer. That is, polyethylene, polypropylene, polystyrene, polybutyl alcohol, polybutyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide and the like can be mentioned.
- the thickness of the intermediate layer is preferably 0.
- the layer structure of the reversible thermosensitive recording material according to the present invention includes a thermosensitive recording layer and a magnetic recording layer mainly composed of a magnetic material on a support as described in Japanese Utility Model Application Laid-Open No. 2-38776. And a layer structure in which at least a portion corresponding to the heat-sensitive recording layer immediately below the heat-sensitive recording layer or on the support is colored.
- the magnetic recording layer may be provided on the back surface of the support or provided between the support and the heat-sensitive layer. Even with these other layer configurations, there is no change.
- a colored layer may be provided between the support and the recording layer to improve visibility.
- the coloring layer is formed by applying a solution or dispersion containing a coloring agent and a resin binder as main components to the target surface and drying, or simply laminating a coloring sheet.
- the colorant only needs to be able to recognize the change in transparency and white turbidity of the upper recording layer as a reflection image, and a dye having a color such as red, yellow, blue, dark blue, purple, black, brown, gray, orange, green, etc. Pigments and the like are used.
- Various thermoplastic, thermosetting or ultraviolet curable resins are used as the resin binder.
- an air layer which is a non-contact portion having air
- the refractive index of the organic polymer material used as the main component of the recording layer is about 1.4 to 1.6, and the difference between the refractive index of air and the refractive index of air is large.
- Light is reflected at the interface between the side film and the non-contact portion, and when the recording layer is in a cloudy state, the degree of white turbidity is amplified and visibility is improved. Therefore, it is desirable to use this non-contact portion as a display portion.
- the non-adhesive part Since the non-adhesive part has air inside the non-adhesive part, the non-adhesive part becomes a heat insulating layer, and the heat sensitivity is improved. Furthermore, the non-adhered portion also does not serve as a cushion, and the pressure actually applied to the heat-sensitive member is low even if the thermal head is pressed down and pressed down. There is no expansion of molecular substance particles, and durability is repeatedly improved.
- an adhesive layer or a pressure-sensitive adhesive layer on the back surface of the support and use it as a reversible thermosensitive recording label.
- This label sheet is attached to the adherend, but as the adherend, for example, a credit card Examples include, but are not limited to, PVC cards, IC cards, ID cards, paper, film, synthetic paper, boarding buses, commuter passes, and the like.
- the support is made of a material having poor adhesion to a resin, such as an A1 vapor deposition layer, an adhesive layer may be provided between the support and the heat-sensitive layer (see JP-A-3-73777). No.).
- the image forming means and the image erasing means for forming and erasing an image on the reversible thermosensitive recording material use the same heating element, for example, a thermal head, and change the energy applied to the thermal head.
- Image forming and erasing methods that can perform image processing, or the image forming means is a thermal head, and the image erasing means adheres a heating element such as a thermal head, hot stamp, heat roller, or heat block.
- FIGS. 11 (a), (b), (c) and (d) can be mentioned.
- FIG. 11 (a) is a schematic diagram of a contact-press type heating apparatus for performing transparency by pressing a hot stamp 502 against a stationary reversible thermosensitive recording material 501.
- FIG. 11 (b) is an outline of a contact-type heating device which makes the heat transparent by a heat roller 504.
- FIG. 11 (c) is a schematic diagram of a non-contact type heating device which makes the transparency by hot air from a dryer 506, and in the figure, 507 denotes a feed roller.
- FIG. 11 (d) is a schematic diagram of a contact-pressing type heating device which performs transparency by a heat block 508.
- 507 indicates a re-roller.
- a thermal head can be used as an image erasing device.
- FIG. 12 shows an example in which the image forming means for performing image formation / erasing on the reversible thermosensitive recording material and the image erasing means are thermal heads.
- thermosensitive recording medium on which the surface image of 61-1-1 is formed is sent to the right by the platen roll 601 in the figure.
- Medium The image is erased by applying energy at the thermal head for image erasure of 609 (Simultaneous displacement stress occurs at the contact surface between the recording material and the thermal head, but the resin of the recording layer is crosslinked. If so, the extent is extremely small.)
- the energy of the thermal head for image formation was not applied, and only the platen roll 611 in the figure was driven, and then the guide roll 612 in the figure and the guide roll 612 in the figure were used. It is transported to the stopper.
- Fig. 12 (b) the reversibility of the image of 601-2 in the figure has been erased.
- the heat-sensitive recording material is sent to the left by the guide rolls 6 and 12 in the figure, and is further sent to the left by the platen rolls 6 and 11 in the figure.
- energy is applied by the thermal head for image formation shown by reference numeral 610 in the figure, and a new image is formed.
- a shift stress is generated on the contact surface between the recording material and the thermal head. Peri, the extent is extremely small).
- the energy of the image erasing thermal head 9 in the figure is not applied, and only the platen roll 611 in the figure is driven and further conveyed to the left.
- an image can be displayed using a reversible thermosensitive recording material.
- thermo head 609 and 610 it is also possible to use the same thermal head for the thermal heads 609 and 610. It is also possible to change to a contact pressing type erasing device such as a heat roller or a heat block, or a non-contact type erasing device using warm air or infrared rays. Further, in this apparatus, it is defined that a thermal head 609 for erasing an image and a thermal head 610 for forming an image are provided. No. Second, the image forming means and the image erasing means for forming and erasing an image on the reversible thermosensitive recording material are the same thermal head, and the pressing means is provided behind the thermal head.
- Fig. 13 shows an example of using a guide roll as an example.
- the reversible thermosensitive recording material 600 1-11 on which an image is formed is sent rightward by a platen roll 6 11
- image formation—erasing summary head 614 the old image is erased and a new image is formed.
- the reversible recording material 600-1-3, on which a new image is formed is further sent rightward by the platen roll 611.
- the gap between the guide rolls 612, 612 in the figure is Move right after passing.
- image formation and erasing can be performed without contact.
- image formation and erasing means such as 1) heating in a non-contact manner above the image forming temperature, and 2) heating while applying pressure above the image forming temperature can be adopted.
- the recording layer when the recording layer has a cross-linked structure as a whole, the recording layer including the organic low-molecular substance particles does not cause distortion, and good erasure of recording can always be performed. .
- Unitide C 7-164, 49% butyl acetate solution 10 parts Toluene 4 parts A solution consisting of 4 parts was applied with a wire bar, dried by heating, and then irradiated with an ultraviolet ray of 8 OW / cm for 5 seconds for about 1. A 5 / m thick smooth layer was provided. A1 was vacuum-deposited on top of it to a thickness of about 40 OA, and a light reflection layer was provided.
- T.H.F tetrahydrofuran
- Octadecyl stearate (M96 76, manufactured by NOF Corporation) 5 parts Eicosane diacid (SL-20-20-99, manufactured by Okamura Oil Company) 5 parts Diisodecyl phthalate 3 parts
- thermosensitive layer reversible thermosensitive recording layer
- the recording layer prepared as described above was irradiated with an electron beam in the following manner.
- An electron beam irradiator EBC-200-AA2 manufactured by Nissin High Voltage Co., Ltd. was used as the electron beam irradiator, and electron beam irradiation was performed twice so that the total irradiation dose was 30 Mrad.
- a transparent PET having a thickness of about 188 ⁇ m was used as a support, and a heat-sensitive layer was formed thereon by the same method as described above. Irradiation was performed, and then the heat-sensitive layer film was separated from the support to form a heat-sensitive layer film.
- a reversible thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Example 1 except that the composition was changed to 40% acid bur.
- Example 7 a reversible thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Example 1.
- a reversible thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Example 6 except that the above procedure was repeated.
- a reversible thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Example 6 except that the above procedure was repeated.
- Example 1 a reversible thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Example 1 except that no electron beam irradiation was performed, except for trimethylolpropane triatalylate in the thermosensitive layer.
- Example 1 2 Except for trimethylolpropane triatalylate in the heat-sensitive layer, a reversible heat-sensitive recording material and a heat-sensitive layer film were prepared in the same manner as in Example 6 except that electron beam irradiation was not performed.
- Example 1 2 Except for trimethylolpropane triatalylate in the heat-sensitive layer, a reversible heat-sensitive recording material and a heat-sensitive layer film were prepared in the same manner as in Example 6 except that electron beam irradiation was not performed.
- Example 1 2
- Example 1 the resin base material of the heat-sensitive layer was prepared by using a vinyl chloride-butyl butyrate copolymer (manufactured by Kaneka Chemical Co., Ltd., average degree of polymerization: 500, vinyl chloride: 80%, vinyl butyrate: 20%, Work), except that the reversible thermosensitive recording material and the thermosensitive layer film were prepared in the same manner as in Example 1.
- a vinyl chloride-butyl butyrate copolymer manufactured by Kaneka Chemical Co., Ltd., average degree of polymerization: 500, vinyl chloride: 80%, vinyl butyrate: 20%, Work
- thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Example 12 except that electron beam irradiation was not performed except for trimethylolpropane triacrylate in the thermosensitive layer.
- Vinyl acetate 20% prototype
- thermosensitive recording material and a thermosensitive layer film were prepared in the same manner as in Comparative Example 1 except that electron beam irradiation was not performed except for trimethylolpropane triacrylate in the thermosensitive layer.
- thermosensitive recording materials and the thermosensitive layer films of the examples and comparative examples obtained in this way were measured, and the results are shown in Tables 1 to 5.
- the heating temperature of the transparency start temperature measurement was extended to a higher temperature than the respective transparency start temperatures, and the reflection density was measured with a Macbeth reflection densitometer in the same manner as described above. 2 (O.D)
- the heating temperature when the temperature was low was determined as the clearing end temperature, and the measurement was performed for each of the application times of 60 seconds and 1 second, and each was measured as T 6 . L and T 1 L.
- the heat-sensitive layer film is heated and cooled so that the heat-sensitive layer film becomes a maximum cloudy state and a maximum transparent state.
- a membrane was prepared.
- V ST static transparent transmitted light intensity
- V sw static cloudy transmitted light intensity
- V DW dynamic opacity transmitted light intensity
- V DT dynamic transparent transmitted light intensity
- FIG. 14 shows the transmitted light intensity waveform output by the printer of the digital oscilloscope in the dynamic transmitted light intensity measurement obtained by the above measurement for Example 1 and Comparative Example 1.
- thermosensitive layer film was heated and cooled using a thermostat so as to be in the maximum transparent state, the film thickness was measured in the same manner as described above, the average value was calculated, and the thermosensitive layer transparent state film thickness (RT) was obtained.
- RT thermosensitive layer transparent state film thickness
- the rate of change in film thickness was calculated from the film thickness Rw and RT of the heat-sensitive layer and the measured rate of change in transparency C T (%). Table 4 shows the results.
- thermosensitive recording materials of Examples and Comparative Examples obtained as described above were subjected to the image formation, erasure and repetition durability tests as follows. Table 5 shows the results.
- thermal recording device using a printing tester manufactured by Yashiro Electric Co., Ltd., a Kyocera KBD-40-8 MGK 1 thermal head was used as the thermal head, and the pulse width was 2.
- a cloudy image is formed under the conditions of 0 msec and an applied voltage of 12.5 V, and the density at that time is defined as the cloudy image density. The smaller the value, the whiter. Erasability>
- a cloudy image was formed under the same conditions as for the cloudy image density. Immediately after that, the applied voltage was appropriately changed to make it transparent, and the relationship between the erase density and the erase energy was graphed as shown in Fig. 15.
- the erasable energy width is calculated by using the formula, and the density of the part that has become the most transparent is the maximum transparent density, and the thermal head between the maximum transparent density and the background is the initial erasability.
- the difference between the density and the background at the same site as the initial erasability was defined as the erasure over time.
- the formation of the cloudy image and the clearing were each repeated to measure the density of the 40th cloudy image, and the difference from the initial cloudy image density was repeatedly determined as the durability.
- the reversible thermosensitive recording material of the present invention has a clearing start temperature change rate of 13% or less, and a clearing temperature range of 50 ° C or more. Also, since the rate of change in transparency of the heat-sensitive layer is 50% or more, and the rate of change in film thickness of the heat-sensitive layer is 2% or more, high-speed erasing characteristics can be improved, and in particular, image erasability by a thermal head can be improved. In addition, the erasability over time can be improved, and the erasability over time due to a difference in environmental temperature can be improved.
- the effect is further improved, and furthermore, the effect is further improved by using a specific organic low-molecular substance constituting the heat-sensitive layer, and the heat-sensitive layer of these recording materials is further crosslinked. This has the effect of improving the repetition durability.
- the image forming and erasing method of the present invention performs high-speed image formation and Z or image erasing without the need for fine control of a thermal head by combining with the reversible thermosensitive recording material of the present invention. be able to.
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Thermal Transfer Or Thermal Recording In General (AREA)
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP95906534A EP0692389B1 (en) | 1994-01-28 | 1995-01-27 | Reversible heat-sensitive recording medium, and image forming and erasing method |
Applications Claiming Priority (2)
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JP2617794 | 1994-01-28 | ||
JP6/26177 | 1994-01-28 |
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WO1995020491A1 true WO1995020491A1 (fr) | 1995-08-03 |
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PCT/JP1995/000103 WO1995020491A1 (fr) | 1994-01-28 | 1995-01-27 | Support d'enregistrement thermosensible reversible et procede de formation et d'effacement d'image |
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EP (1) | EP0692389B1 (ja) |
WO (1) | WO1995020491A1 (ja) |
Families Citing this family (2)
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EP1110746B8 (en) * | 1997-07-18 | 2005-06-08 | Ricoh Company, Ltd. | Reversible thermosensitive recording medium, method of producing the medium, information recording devices using the medium, and image formation and erasing method using the medium |
JP3871295B2 (ja) * | 1998-11-06 | 2007-01-24 | 株式会社リコー | 熱可逆記録媒体、ラベル、カード、ディスク、ディスクカートリッジ及びテープカセットと画像処理方法 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS55154198A (en) * | 1979-02-24 | 1980-12-01 | Dabisch Tipp Ex Tech | Light shielding body with temperature dependence and recording material utilizing said body |
JPS6339378A (ja) * | 1986-08-05 | 1988-02-19 | Ricoh Co Ltd | 可逆性感熱記録材料 |
JPH02220889A (ja) * | 1989-02-23 | 1990-09-04 | Ricoh Co Ltd | 可逆性感熱記録材料 |
JPH04358878A (ja) * | 1991-06-05 | 1992-12-11 | Mitsubishi Plastics Ind Ltd | 可逆性感熱記録材料 |
JPH05193258A (ja) * | 1991-09-26 | 1993-08-03 | Ricoh Co Ltd | 可逆性感熱記録材料、その製造方法及びそれを使用した画像表示方法 |
JPH05318917A (ja) * | 1992-03-18 | 1993-12-03 | Ricoh Co Ltd | 画像記録方法 |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3044590B2 (ja) * | 1991-07-08 | 2000-05-22 | 株式会社リコー | 可逆性感熱記録材料の製造方法 |
US5278129A (en) * | 1991-11-20 | 1994-01-11 | Toppan Printing Co., Ltd. | Rewritable thermosensitive recording medium |
-
1995
- 1995-01-27 EP EP95906534A patent/EP0692389B1/en not_active Expired - Lifetime
- 1995-01-27 WO PCT/JP1995/000103 patent/WO1995020491A1/ja active IP Right Grant
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS55154198A (en) * | 1979-02-24 | 1980-12-01 | Dabisch Tipp Ex Tech | Light shielding body with temperature dependence and recording material utilizing said body |
JPS6339378A (ja) * | 1986-08-05 | 1988-02-19 | Ricoh Co Ltd | 可逆性感熱記録材料 |
JPH02220889A (ja) * | 1989-02-23 | 1990-09-04 | Ricoh Co Ltd | 可逆性感熱記録材料 |
JPH04358878A (ja) * | 1991-06-05 | 1992-12-11 | Mitsubishi Plastics Ind Ltd | 可逆性感熱記録材料 |
JPH05193258A (ja) * | 1991-09-26 | 1993-08-03 | Ricoh Co Ltd | 可逆性感熱記録材料、その製造方法及びそれを使用した画像表示方法 |
JPH05318917A (ja) * | 1992-03-18 | 1993-12-03 | Ricoh Co Ltd | 画像記録方法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP0692389A4 * |
Also Published As
Publication number | Publication date |
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EP0692389A4 (en) | 1996-02-28 |
EP0692389B1 (en) | 1999-09-01 |
EP0692389A1 (en) | 1996-01-17 |
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