JP2009234156A - Method for irradiating uv-curing ink with ultraviolet rays, apparatus for creating irradiation data, image formation system, uv-curing inkjet printer, ultraviolet irradiation apparatus, and printing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for irradiating UV-curing ink with ultraviolet rays under the optimal conditions, and to provide a device for creating irradiation data, an image formation system, an UV-curing inkjet printer, an ultraviolet irradiation apparatus and a printing apparatus. <P>SOLUTION: In a method for irradiating ultraviolet rays, an integrated amount of light and an irradiation intensity are set as conditions for irradiating UV-ink with ultraviolet rays. The amount of reaction heat and the reaction time are measured for the UV-ink with a constant integrated amount of light while changing the irradiation intensity and irradiation time. Subsequently, a first approximation indicating variation in the amount of reaction heat for the irradiation intensity, and a second approximation indicating variation in the 90% reaction time for the irradiation intensity are calculated. A determination is made whether the first approximation has a maximal value and the second approximation has a minimal value or not. When the UV-ink is irradiated with an integrated amount of light satisfying the conditions, a coating of UV-ink can be hardened well in a short time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultraviolet irradiation method of an ultraviolet curable ink that is cured by irradiating ultraviolet rays, an irradiation data creation apparatus, an image forming system, an ultraviolet curable ink jet printer, an ultraviolet irradiation apparatus, and a printing apparatus.

  2. Description of the Related Art Conventionally, an ink jet printer using an ultraviolet curable ink that is cured by irradiating ultraviolet rays is known (for example, see Patent Document 1). In this ink jet printer, a photo cationic polymerization type ultraviolet curable ink is ejected onto a recording medium by an ink jet head having a plurality of nozzles. Then, ultraviolet rays are irradiated from the ultraviolet irradiation means to the ink coating film ejected onto the recording medium, and the ink is cured by causing a photopolymerization reaction. Thereby, the ink can be fixed on the recording medium.

  In such an ink jet printer, the physical properties of the ink after curing differ depending on the irradiation condition of the ultraviolet rays. For example, if the irradiation conditions do not match the ink used, the ink may not be sufficiently cured. In this case, the ink is not satisfactorily fixed on the recording medium, and the surface of the coated ink film becomes sticky. Further, if the irradiation intensity of ultraviolet rays is increased, the ink cures rapidly, but this is not preferable because the power consumption of the ultraviolet irradiation means increases. Accordingly, it is necessary to set an optimum irradiation condition for each type of ink to be used.

Generally, the irradiation condition of ultraviolet rays is determined by the irradiation intensity and the integrated light amount. The integrated light amount is the total energy of irradiation, and is obtained by multiplying the irradiation intensity by the irradiation time. The irradiation intensity has an optimum value depending on the type of polymerization initiator contained in the ink. By irradiating with the optimum value, the time until the ink is cured is shortened, so that the integrated light quantity can be minimized and the power consumption can be suppressed. In order to set such optimum irradiation conditions, for example, a printed matter or a coating film is formed with the ink to be used, and after curing under various irradiation conditions, the hardness of the obtained printed matter or coating film is determined. The optimum irradiation conditions were obtained by measuring.
JP 2004-136579 A

  However, in the above-described conventional method, the ink must be cured under various irradiation conditions, and the hardness of the printed matter and the coating film obtained by further curing must be measured one by one. There was a problem of being troublesome.

  The present invention has been made to solve the above-described problems, and an ultraviolet irradiation method of an ultraviolet curable ink, an irradiation data creation device, an image forming system, and an ultraviolet ray that can irradiate ultraviolet rays under an irradiation condition optimum for the ultraviolet curable ink. It is an object of the present invention to provide a curable ink jet printer, an ultraviolet irradiation device, and a printing device.

  In order to achieve the above object, the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 1 is an ultraviolet irradiation method of the ultraviolet curable ink, and changes the irradiation intensity and the irradiation time with a constant integrated light amount. In addition, the ultraviolet curable ink is irradiated with ultraviolet rays, and the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured are set for each of a plurality of preset integrated light amounts. From the measurement process to be measured and the measurement result in the measurement process, a first approximate expression of a first approximate curve indicating a change in the reaction heat amount with respect to the change in the irradiation intensity, and a change in the reaction time with respect to the change in the irradiation intensity In the approximate expression calculating step for calculating the second approximate expression of the second approximate curve showing, and in the first approximate expression and the second approximate expression calculated in the approximate expression calculating step, the irradiation intensity is changed. A maximum value / minimum value determining step for determining whether the first approximate expression has a maximum value and the second approximate expression has a minimum value within the predetermined range, and the maximum value / minimum value An integrated light quantity setting step for setting the integrated light quantity under the condition that it is determined that the first approximate expression has a maximum value and the second approximate expression has a minimum value in a value determination step; and the integrated light quantity setting step And an irradiation step of irradiating the ultraviolet curable ink with ultraviolet rays with the integrated light quantity set in (1).

  In addition to the configuration of the invention according to claim 1, the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 2 includes the maximum / minimum value determining step in the integrated light quantity setting step, and the maximum value in the integrated light amount setting step. When there are a plurality of the integrated light amounts under the condition where it is determined that there is a value and the minimum value, the integrated light amount with the shortest reaction time is set.

  In addition to the configuration of the invention according to claim 1 or 2, the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 3 adds the maximum of the first approximate curve after the integrated light quantity setting step. The irradiation intensity under the integrated light quantity set in the integrated light quantity setting step is set between the first irradiation intensity corresponding to the value and the second irradiation intensity corresponding to the minimum value of the second approximate curve. An irradiation intensity setting step is provided.

  In addition to the configuration of the invention according to any one of claims 1 to 3, the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 4 includes the reaction time until the ultraviolet curable ink is cured. The reaction time is 90% corresponding to 90% of the time.

  Further, the irradiation data creation device of the invention according to claim 5 is the irradiation data for creating the irradiation data used in the ultraviolet irradiation device of the printing apparatus that discharges the ultraviolet curable ink onto the printing medium and irradiates the ultraviolet ray to cure. Irradiation intensity for each of a plurality of integrated light amounts set in advance by a calorimeter measuring means for measuring a reaction heat amount of the UV curable ink and a reaction time until the UV curable ink is cured. A first approximation indicating a change in the reaction heat amount with respect to a change in the irradiation intensity based on the reaction heat amount and the reaction time measured when the ultraviolet curable ink is irradiated with ultraviolet light while changing the irradiation time. An approximate expression calculating means for calculating a first approximate expression of a curve and a second approximate expression of a second approximate curve indicating a change in the reaction time with respect to a change in the irradiation intensity; In the first approximate expression and the second approximate expression calculated by the approximate expression calculating means, the first approximate expression has a maximum value within a predetermined range in which the irradiation intensity is changed, and the second approximate expression The local maximum / minimum value determining means for determining whether or not the system has a local minimum value and the local maximum / minimum value determining means have a local maximum value in the first approximate expression and the local minimum in the second approximate expression. Data setting means for setting, as the irradiation data, an integrated light amount under a condition determined to have a value.

  Further, in addition to the configuration of the invention according to claim 5, the irradiation data creation device of the invention according to claim 6 is configured such that the data setting unit has a plurality of the integrated light amounts set by the integrated light amount setting process. The integrated light quantity is set under the condition that the reaction time is the shortest.

  Moreover, in addition to the structure of the invention in any one of Claim 5 or 6, the irradiation data creation apparatus of the invention which concerns on Claim 7 respond | corresponds to the said local maximum value of the said 1st approximated curve in addition to the structure of the invention in any one of Claim 5 or 6. Between the first irradiation intensity and the second irradiation intensity corresponding to the minimum value of the second approximate curve, the irradiation intensity when irradiating the ultraviolet curable ink is set as the irradiation data, To do.

  According to an eighth aspect of the present invention, in addition to the configuration of the fifth aspect of the invention, the reaction time is 90 times of the time until the ultraviolet curable ink is cured. 90% reaction time corresponding to%.

  An image forming system according to a ninth aspect includes the irradiation data creating apparatus according to any one of the fifth to eighth aspects and the printing apparatus.

  An image forming system according to a tenth aspect of the invention includes the calorific value measuring means in addition to the configuration of the invention according to the ninth aspect.

  The ultraviolet curable ink jet printer of the invention according to claim 11 is equipped with an ultraviolet curable ink equipped with an ultraviolet curable ink and an ultraviolet irradiation device capable of irradiating ultraviolet rays by an optimum ultraviolet irradiation method specific to the ultraviolet curable ink. In the inkjet printer, the ultraviolet irradiation device irradiates the ultraviolet curable ink with ultraviolet rays by the ultraviolet irradiation method according to any one of claims 1 to 3.

  An ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 12 is an ultraviolet irradiation method of irradiating ultraviolet rays with a constant integrated light amount to the ultraviolet curable ink, wherein the integrated light amount is constant, the irradiation intensity is When measuring the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured while irradiating the ultraviolet curable ink with ultraviolet rays while changing the irradiation time, In the first approximate expression of the first approximate curve showing the change of the reaction heat amount with respect to the change of the irradiation intensity, it has a maximum value within the range in which the irradiation intensity is changed, and the change of the reaction time with respect to the change of the irradiation intensity Irradiating the ultraviolet curable ink with ultraviolet rays with an integrated light amount having a minimum value within a range in which the irradiation intensity is changed And features.

  An ultraviolet irradiation device according to a thirteenth aspect of the invention is an ultraviolet irradiation device that irradiates ultraviolet curable ink with ultraviolet light at a constant integrated light amount, and changes the irradiation intensity and irradiation time with the constant integrated light amount. When the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured are respectively measured while irradiating the ultraviolet curable ink with ultraviolet rays, the change in the irradiation intensity is measured. In a first approximate expression of a first approximate curve indicating a change in the reaction heat amount, a second approximation having a maximum value within a range in which the irradiation intensity is changed and indicating a change in the reaction time with respect to the change in the irradiation intensity. In the second approximate expression of the curve, the ultraviolet curable ink is irradiated with ultraviolet rays with an integrated light amount having a minimum value within a range in which the irradiation intensity is changed.

  According to a fourteenth aspect of the present invention, there is provided a printing apparatus for ejecting ultraviolet curable ink onto a printing medium and irradiating and curing ultraviolet light with a constant integrated light quantity, wherein the integrated light quantity is determined by the irradiation intensity. When measuring the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured while irradiating the ultraviolet curable ink with ultraviolet rays while changing the irradiation time, In the first approximate expression of the first approximate curve showing the change of the reaction heat amount with respect to the change of the irradiation intensity, it has a maximum value within the range in which the irradiation intensity is changed, and the change of the reaction time with respect to the change of the irradiation intensity In the second approximate expression of the second approximate curve representing the above, the integrated light quantity has a minimum value within the range in which the irradiation intensity is changed.

  In the ultraviolet irradiating method of the ultraviolet curable ink according to the first aspect of the invention, first, in the measuring step, a plurality of integrated light quantities are set first. Then, the irradiation intensity and the irradiation time are changed under the condition of each integrated light quantity, and the ultraviolet curable ink is irradiated with ultraviolet rays. Then, since the ultraviolet curable ink is cured by a polymerization reaction, the amount of reaction heat and the reaction time at that time are measured for each integrated light amount. Next, in the approximate expression calculation step, from the measurement result in the measurement step, the first approximate expression of the first approximate curve indicating the change in reaction heat amount with respect to the change in irradiation intensity, and the first approximate expression indicating the change in reaction time with respect to the change in irradiation intensity. A second approximate expression of two approximate curves is created for each integrated light quantity. Subsequently, in the local maximum / minimum value determining step, the first approximate expression has a maximum value within a predetermined range in which the irradiation intensity is changed in both the first approximate expression and the second approximate expression, and the second approximate expression is determined. It is determined whether or not the approximate expression has a minimum value.

  Next, when it is determined in the integrated light quantity setting step that the above condition is satisfied, an integrated light quantity that satisfies the condition is set. In the irradiation step, the ultraviolet curable ink is irradiated with ultraviolet rays with the integrated light amount set in the integrated light amount setting step. By irradiating with the integrated light quantity under these conditions, the reaction heat amount of the ultraviolet curable ink can be increased, and the reaction time can be shortened. That is, the optimum integrated light amount of the ultraviolet curable ink can be found by a simple method, and the ultraviolet curable ink can be irradiated with the integrated light amount. Then, the ultraviolet curable ink can be rapidly cured, and a coating film of the ultraviolet curable ink having a good hardness can be formed.

  Further, in the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 2, in addition to the effect of the invention of claim 1, when there are a plurality of integrated light quantities of the conditions determined in the maximum / minimum value determining step In the integrated light quantity setting step, the integrated light quantity of the irradiation condition with the shortest reaction time is set from the plurality of integrated light quantities. Thereby, since the irradiation time can be shortened, the ultraviolet curable ink can be cured quickly, and the power consumption for irradiation can be saved.

  In addition, in the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 3, in addition to the effect of the invention of claim 1 or 2, the irradiation intensity setting step after the integrated light amount setting step and before the measurement step Execute. In the irradiation intensity setting step, the integration set in the integrated light amount setting step between the first irradiation intensity corresponding to the maximum value of the first approximate curve and the second irradiation intensity corresponding to the minimum value of the second approximate curve. Set the irradiation intensity under light intensity. Thereby, it is possible to irradiate ultraviolet rays with an appropriate integrated light quantity and irradiation intensity to the ultraviolet curable ink.

  Further, in the ultraviolet irradiation method of the ultraviolet curable ink of the invention according to claim 4, in addition to the effect of the invention according to any one of claims 1 to 3, it is difficult to obtain a measurement error with 100% reaction time. By obtaining the% reaction time, it is possible to obtain data with a small measurement error and high reliability.

  In the irradiation data creation device of the invention according to claim 5, for each of a plurality of preset integrated light amounts, an approximation is made by using the reaction heat amount and reaction time of the ultraviolet curable ink measured by the calorie measurement means. The formula calculation means calculates a first approximate expression of a first approximate curve indicating a change in reaction heat amount and a second approximate expression of a second approximate curve indicating a change in reaction time, respectively. Next, the maximum / minimum value determining means has a maximum value in the first approximate expression within a predetermined range in which the irradiation intensity is changed for both the first approximate expression and the second approximate expression, and It is determined whether or not the two approximate expressions have a minimum value. Here, when it is determined that the first approximate expression has a maximum value and the second approximate expression has a minimum value, the data setting means determines that the first approximate expression has a maximum value and the second approximate expression has a minimum value. The integrated light quantity of the condition is set as irradiation data. Therefore, irradiation data optimum for the ultraviolet curable ink can be easily created.

  In addition, in the irradiation data creation device of the invention according to claim 6, in addition to the effect of the invention of claim 5, when there are a plurality of integrated light quantities determined by the maximum / minimum value determination means, the data setting means Sets the integrated light amount of the irradiation condition with the shortest reaction time from among the plurality of integrated light amounts. Thereby, since the irradiation time can be shortened, the ultraviolet curable ink can be cured quickly, and the power consumption for irradiation can be saved.

  In addition, in the irradiation data creation device of the invention according to claim 7, in addition to the effect of the invention of claim 5 or 6, when the integrated light quantity is set by the data setting means, the irradiation intensity setting means has the first approximate curve. The irradiation intensity at the time of irradiating the ultraviolet curable ink is set as irradiation data between the first irradiation intensity corresponding to the local maximum value and the second irradiation intensity corresponding to the local minimum value of the second approximate curve. Thereby, the integrated light quantity and the irradiation intensity can be set as the irradiation data optimal for the ultraviolet curable ink.

  In addition, in the irradiation data creation device of the invention according to claim 8, in addition to the effect of the invention according to any one of claims 5 to 7, it is difficult to obtain a measurement error with 100% reaction time, but 90% reaction time is obtained. As a result, data with a small measurement error and high reliability can be obtained.

  In the image forming system according to the ninth aspect of the present invention, the irradiation data creation device creates irradiation data optimum for the ultraviolet curable ink from the measurement data of the reaction heat amount and the reaction time of the ultraviolet curable ink. Based on the condition of the irradiation data, ultraviolet rays are irradiated from the ultraviolet irradiation device of the printing apparatus. Thereby, the ultraviolet curable ink can be cured quickly and satisfactorily. Therefore, the ink image can be satisfactorily fixed on the print medium. Further, since the ultraviolet curable ink is cured well, the surface of the ink coating film is not sticky.

  Further, in the image forming system according to the tenth aspect, in addition to the effect of the ninth aspect, the heat of reaction and the reaction time of the ultraviolet curable ink can be measured by using the calorimeter. Thereby, the irradiation data creation device can create irradiation data optimum for the ultraviolet curable ink.

  In the ultraviolet curable ink jet printer of the invention according to claim 11, the ultraviolet irradiation device irradiates the ultraviolet curable ink with ultraviolet rays by the ultraviolet irradiation method according to any one of claims 1 to 3. Ultraviolet rays can be irradiated by an optimum ultraviolet irradiation method specific to the type ink. Therefore, the ink image formed with the ultraviolet curable ink can be cured well.

  In the ultraviolet irradiating method of the ultraviolet curable ink according to the twelfth aspect of the invention, the ultraviolet curable ink is irradiated with ultraviolet rays with a constant integrated light amount. Then, this integrated light quantity is obtained by changing the irradiation intensity and the irradiation time, and irradiating the ultraviolet curable ink with ultraviolet rays, and measuring the reaction heat amount and reaction time of the ultraviolet curable ink at that time, respectively. In the first approximate expression of the first approximate curve showing the change of the irradiation intensity, in the second approximate expression of the second approximate curve having the maximum value within the range in which the irradiation intensity is changed and indicating the change in the reaction time, the irradiation intensity is The integrated light quantity has a minimum value within the changed range. Here, the integrated light amount having the maximum value and the minimum value means an integrated light amount that can quickly increase the reaction heat amount of the ultraviolet curable ink and shorten the reaction time. That is, since the ultraviolet light is irradiated with such a constant integrated light amount, the polymerization reaction of the ultraviolet curable ink can proceed sufficiently and quickly. Therefore, the ultraviolet curable ink can be cured satisfactorily.

  In the ultraviolet irradiation device according to the thirteenth aspect of the present invention, ultraviolet light is irradiated to the ultraviolet curable ink with a constant integrated light amount. Then, this integrated light quantity is obtained by changing the irradiation intensity and the irradiation time, and irradiating the ultraviolet curable ink with ultraviolet rays, and measuring the reaction heat amount and reaction time of the ultraviolet curable ink at that time, respectively. In the first approximate expression of the first approximate curve showing the change of the irradiation intensity, in the second approximate expression of the second approximate curve having the maximum value within the range in which the irradiation intensity is changed and indicating the change in the reaction time, the irradiation intensity is The integrated light quantity has a minimum value within the changed range. Here, the integrated light amount having the maximum value and the minimum value means an integrated light amount that can quickly increase the reaction heat amount of the ultraviolet curable ink and shorten the reaction time. That is, since the ultraviolet light is irradiated with such a constant integrated light amount, the polymerization reaction of the ultraviolet curable ink can proceed sufficiently and quickly. Therefore, the ultraviolet curable ink can be cured satisfactorily.

  In the printing apparatus according to the fourteenth aspect of the present invention, ultraviolet curable ink is ejected onto a printing medium, and the ink image ejected onto the printing medium is irradiated with ultraviolet rays at a constant integrated light quantity. As a result, the ink image on the print medium is cured and fixed. Here, the cumulative amount of light when irradiating ultraviolet rays is measured by irradiating the ultraviolet curable ink with ultraviolet rays by changing the irradiation intensity and irradiation time, and measuring the reaction heat amount and reaction time of the ultraviolet curable ink at that time, respectively. In this case, in the first approximate expression of the first approximate curve indicating the change in the reaction heat amount, the second approximation of the second approximate curve having the maximum value within the range in which the irradiation intensity is changed and indicating the change in the reaction time. In the equation, the integrated light amount has a minimum value within a range in which the irradiation intensity is changed. Here, the integrated light amount having the maximum value and the minimum value means an integrated light amount that can quickly increase the reaction heat amount of the ultraviolet curable ink and shorten the reaction time. That is, since the ultraviolet light is irradiated with such a constant integrated light amount, the polymerization reaction of the ultraviolet curable ink can proceed sufficiently and quickly. Therefore, the ink image formed with the ultraviolet curable ink can be cured well on the printing medium.

  Hereinafter, an ultraviolet irradiation method of an ultraviolet curable ink, an irradiation data creation device 10, a UV inkjet printer 20, and an image forming system 100 according to an embodiment of the present invention will be described with reference to the drawings.

  First, the ultraviolet curable ink will be described. Ultraviolet curable ink (hereinafter referred to as UV ink) is a type of functional ink that cures when irradiated with ultraviolet rays. In the UV ink, at least one of a polymerizable monomer and an oligomer, a photopolymerization initiator, and a color material (pigment or dye) are blended. UV inks are roughly classified into radical polymerization inks using radicals as active species and cationic polymerization inks using protonic acids as active species. Any of these two types of ink can be applied as the ink used in the present embodiment. Furthermore, a hybrid ink in which a radical polymerization ink and a cation polymerization ink are combined can be applied as an ink used in this embodiment.

  In the present embodiment, it is preferable to use a cationic polymerization ink that has a small inhibitory effect on the polymerization reaction by oxygen and is excellent in curability. The cationic polymerization ink is a mixture containing at least one of a cationically polymerizable monomer and oligomer such as an oxetane compound, an epoxy compound, and a vinyl ether compound, a photocationic initiator (for example, an aromatic onium salt), and a coloring material. It is. Photodegradation of the photopolymerization initiator occurs by irradiating the UV ink as described above with ultraviolet rays. The protonic acid generated at this time polymerizes the polymerizable monomer and oligomer to cure the UV ink.

  Next, ultraviolet irradiation conditions for curing the UV ink will be described. As described above, the UV ink is cured by polymerizing monomers and oligomers by an acid generated by the photopolymerization initiator being decomposed by ultraviolet rays. Therefore, depending on the irradiation conditions of ultraviolet rays, the decomposition reaction of the photopolymerization initiator does not proceed, and the polymerization reaction of monomers and oligomers does not proceed, so that the UV ink may not be cured sufficiently. In other words, the ultraviolet irradiation conditions have a great influence on the properties of the UV ink after ultraviolet irradiation. The chemical basis is presumed as follows.

  For example, when the irradiation intensity of ultraviolet rays is low, the reaction rate of the photopolymerization initiator is low, and the activated photopolymerization initiator is immediately digested. Furthermore, since the steric hindrance is small, the reaction proceeds over time. However, if the polymerization terminal is inactivated, the photopolymerization initiator has already been digested and the reaction cannot be performed. In this case, the 90% reaction time is long and the heat of reaction is low. On the other hand, in the case of high irradiation intensity, the decomposition rate of the photopolymerization initiator is high, and the activated photopolymerization initiator exists for a long time. Therefore, even after the polymerization terminal is inactivated, the activated photopolymerization initiator reacts, so that the polymerization is started again to form a polymer. In this case, the 90% reaction time is shortened and the amount of reaction heat is increased.

  However, if the irradiation intensity is too high, even if there is an activated polymerization initiator after the polymerization terminal is inactivated, the steric hindrance becomes a harmful effect and the polymerization cannot be easily performed. become unable. In this case, the 90% reaction time becomes longer and the heat of reaction becomes lower.

  Further, when the irradiation intensity is low, a polymer having a large molecular weight is obtained. This is because the reaction initiation rate of the photopolymerization initiator is low and the number of growing molecules is small, resulting in an increase in molecular weight. On the other hand, when the irradiation intensity is high, a polymer having a small molecular weight is obtained. This is because the photopolymerization initiator has a high reaction initiation rate and increases the number of molecules to grow, resulting in a small molecular weight. A coating film having a large molecular weight is generally a hard coating film, whereas a coating film having a low molecular weight is generally a soft coating film. Further, if the ultraviolet irradiation time is too long, the power consumption of the UV lamp is increased, which is not preferable in terms of energy efficiency.

  Thus, in order to allow the reaction to proceed sufficiently and quickly and to obtain a good UV ink coating film, the balance between the life of the activated photopolymerization initiator and the state free from steric hindrance is good. It is important to be kept For this purpose, it is necessary to obtain ultraviolet irradiation conditions suitable for the UV ink before curing and to irradiate under the irradiation conditions.

Therefore, in this embodiment, the irradiation intensity (mW / cm ² ) and the integrated light amount (mJ / cm ² ) are set as the ultraviolet irradiation conditions. The integrated light amount is calculated by multiplying the irradiation intensity by the irradiation time (seconds). Then, by using the ultraviolet irradiation method of the present invention described later, it is possible to easily find the optimal irradiation conditions for the UV ink, and it is possible to irradiate ultraviolet rays under the irradiation conditions.

  Next, the ultraviolet irradiation process which is the feature of the present invention will be described with reference to FIG. FIG. 1 is a flowchart showing the flow of the ultraviolet irradiation process. The ultraviolet irradiation treatment process of the present invention is to irradiate the UV ink with ultraviolet light while changing the irradiation intensity and irradiation time under a predetermined cumulative amount of ultraviolet light, and each of the reaction heat amount and 90% reaction time with respect to the irradiation time. “Measurement step” (S10) to be measured, a reaction curve (first approximate curve described later) showing a change in reaction heat generated by plotting the measurement data measured in the measurement step on a graph, and a 90% reaction time An approximate expression calculation step (S11) for calculating the first approximate expression and the second approximate expression from a reaction curve (a second approximate curve described later) indicating the change of the above, and each calculated in the approximate expression calculation step Regarding the approximate expression, “maximum value / minimum value determination step” for determining whether the first approximate expression has a maximum value and the second approximate expression has a minimum value within a predetermined range in which the irradiation intensity is changed (S12). And the maximum / minimum value judgment Thus, the “integrated light amount setting step” (S13) for setting the integrated light amount under the condition that the first approximate expression has the maximum value and the second approximate expression has the minimum value, and the integrated light amount setting step are set. It consists of an “irradiation step” (S14) of irradiating ultraviolet rays with a constant integrated light quantity.

Hereinafter, an embodiment in which ultraviolet rays are irradiated to UV ink using the ultraviolet irradiation process of the present invention will be described with reference to FIGS. FIG. 2 is a table showing the measurement results of integrated light quantity = 200 (mJ / cm ² ). FIG. 3 is a table showing the measurement results when the integrated light quantity = 300 (mJ / cm ² ). FIG. 4 is a table showing the measurement result of accumulated light quantity = 350 (mJ / cm ² ). FIG. 5 is a table showing the measurement results when the integrated light quantity = 600 (mJ / cm ² ). FIG. 6 is a graph plotting measurement data of accumulated light quantity = 200 (mJ / cm ² ). FIG. 7 is a graph plotting measurement data of accumulated light quantity = 300 (mJ / cm ² ). FIG. 8 is a graph plotting measurement data of accumulated light quantity = 350 (mJ / cm ² ). FIG. 9 is a graph plotting measurement data of accumulated light quantity = 600 (mJ / cm ² ). In this example, a cationic curable black jet ink (manufactured by Toa Gosei Co., Ltd.) was used.

First, a measurement process (S10) is performed. In the measurement process, a differential scanning calorimeter ("DSC": manufactured by TA Instruments Inc.) that can perform thermal analysis when heated is applied to a light irradiation device ("PCA") that can irradiate light with varying irradiation intensity and time. ": Calorimetric analyzer combined with TA Instruments Inc.) was used. With this calorimetric analyzer, it is possible to analyze the change in the amount of heat with respect to the irradiation time when the sample sample (UV ink) is irradiated with ultraviolet rays. In this embodiment, four types (200, 300, 350, 600 mJ / cm ² ) of the integrated amount of ultraviolet light irradiated to the sample sample were set. Then, four test sections corresponding to these four types of integrated light quantities are provided, and the change in reaction heat amount and 90% reaction time are measured while changing the irradiation intensity and irradiation time at a constant integrated light quantity in each test section. .

  The 90% reaction time was calculated by the following method. First, the change in the amount of reaction heat is measured by a calorimeter. The amount of reaction heat shows a mountainous change from the start of the reaction to the end of the reaction. In the calorimeter, the data at which the peak of reaction heat is integrated with 0% at the start of the reaction and 100% at the end of the reaction can be obtained. The time at 90% of this data is calculated as 90% reaction time. The 90% reaction time has the advantages of less measurement error and higher reliability than the 100% reaction time.

In addition, the test plots are A test plot (integrated light quantity = 200 mJ / cm ² ), B test plot (integrated light quantity = 300 mJ / cm ² ), C test plot (integrated light quantity = 350 mJ / cm ² ), D test plot ( Integrated light quantity = 600 mJ / cm ² ). Furthermore, in each of these test sections, a plurality of irradiation conditions with different irradiation intensities and irradiation times are set based on the integrated light quantity set in each test section, and sample samples are prepared for examining these conditions. did. Specifically, in the test area A, specimen samples A-1 to A-4 (see FIG. 2) were prepared in order to examine four irradiation conditions. In the B test section, specimen samples B-1 to 5 (see FIG. 3) were prepared in order to examine five irradiation conditions. In the C test section, sample samples (see FIG. 4) of C-1 to 5 were prepared in order to examine five irradiation conditions. In the D test section, sample samples (see FIG. 5) of D-1 to 7 were prepared in order to examine seven irradiation conditions.

  Thus, according to each irradiation condition in which the irradiation intensity and the irradiation time were changed with the integrated light quantity set in each test section, the reaction heat amount change and the 90% reaction time were measured, respectively, and the measurements shown in FIGS. The result was obtained.

  Next, an approximate expression calculation step (S11) is performed. In the measurement process, measurement data (see FIGS. 2 to 5) when irradiated under four integrated light quantities were obtained. In this approximate expression calculation step, first, measurement data of reaction heat and measurement data of 90% reaction time are plotted from the measurement data obtained for each integrated light quantity with respect to the axis indicating the change in irradiation intensity. To do. And the 1st approximate expression of the 1st approximated curve which approximated from the plot of the measurement data of reaction calorie | heat amount is calculated. On the other hand, a second approximate expression of a second approximate curve obtained by approximation from the plot of the measurement data of 90% reaction time is calculated. The results are as follows.

As shown in FIGS. 2 and 6, when the integrated light quantity is 200 (mJ / cm ² ), the first approximate expression of the first approximate curve indicating the change in the reaction heat amount and the second approximation indicating the change in the 90% reaction time. The second approximate expression of the curve is as follows.
First approximate expression: y = 0.006x ² −0.2831x + 126.32 (1)
R ² = 0.7655
Second approximate expression: y = −0.0003x ² + 0.1658x + 99.274 (2)
R ² = 0.9091

As shown in FIGS. 3 and 7, when the integrated light quantity is 300 (mJ / cm ² ), the first approximate expression of the first approximate curve indicating the change in the reaction heat amount and the second approximation indicating the change in the 90% reaction time. The second approximate expression of the curve is as follows.
First approximate expression: y = −0.0007x ² + 0.3679x + 136.82 (3)
R ² = 0.9221
Second approximate expression: y = 0.0005x ² −0.3371x + 135.96 (4)
R ² = 0.8503

As shown in FIGS. 4 and 8, when the integrated light quantity is 350 (mJ / cm ² ), the first approximate expression of the first approximate curve indicating the change in the reaction heat amount and the second approximation indicating the change in the 90% reaction time. The second approximate expression of the curve is as follows.
First approximate expression: y = −8E−05x ² −0.0054x + 164.29 (5)
R ² = 0.9039
Second approximate expression: y = 8E−05x ² + 0.0485x + 11.51 (6)
R ² = 0.9612

As shown in FIGS. 5 and 9, when the integrated light quantity is 600 (mJ / cm ² ), the first approximate expression of the first approximate curve indicating the change in the reaction heat amount and the second approximation indicating the change in the 90% reaction time. The second approximate expression of the curve is as follows.
First approximate expression: y = 1E−05x ² −0.0127x + 203.65 (7)
R ² = 0.9677
Second approximate expression: y = 0.0008x ² −0.5026x + 151.6 (8)
R ² = 0.69

  Next, the maximum / minimum value determining step (S12) will be described. In the maximum / minimum value determining step, the first approximate equation and the second approximate equation for each integrated light quantity calculated in the approximate equation calculating step are set to the maximum value in the first approximate equation within the range in which the irradiation intensity is changed. And whether the second approximate expression has a minimum value is determined. The reason is as follows. First, the first approximate expression is an expression showing a change in the amount of reaction heat with respect to the irradiation intensity. Therefore, the higher the amount of heat of reaction, the more the polymerization reaction is progressing, and it can be cured more reliably. That is, if there is a maximum value of the reaction heat amount within a predetermined range in which the irradiation intensity is changed, it is appropriate as an irradiation condition for curing the UV ink.

  On the other hand, the second approximate expression is an expression indicating a change in 90% reaction time with respect to the irradiation intensity. Therefore, the shorter the 90% reaction time is, the shorter the time required for curing is, and the power consumption of the UV lamp can be saved. Moreover, since 90% reaction time is short, since the reaction rate to superpose | polymerize is high, it can be hardened more reliably. That is, if there is a minimum value of 90% reaction time within a range in which the irradiation intensity is changed, it is appropriate as an irradiation condition for curing the UV ink. Therefore, within the predetermined range in which the irradiation intensity is changed, the integrated light quantity under the condition that the first approximate expression has the maximum value and the second approximate expression has the minimum value is the optimal integrated light quantity.

Here, a method for obtaining the maximum value and the minimum value from the approximate curve will be described. For example, having an extreme value is y ′ = 0 when an equation obtained by differentiating the quadratic function y = ax ² + bx + c of the approximate curve of the obtained data is y ′ = dx ′ + e. The maximum value or the minimum value is obtained at x ′ = α that is sometimes obtained. That is, if α is within the range of the measured irradiation intensity, it has a maximum value or a minimum value. In order to determine whether the extreme value is the maximum or the minimum, the value of y ′ obtained by substituting the value of α−1 into the differentiated expression y ′ = dx ′ + e is negative, and the value of α + 1 When the y ′ value obtained by substituting is positive, it can be understood that it is a minimum value. In the opposite case, it is understood that the value is a maximum value. From such a method, it was determined whether or not there is a maximum value or a minimum value in each integrated light quantity. The determination result of the maximum value and the minimum value in each integrated light quantity is as follows.

First, when the integrated light quantity is 200 (mJ / cm ² ), the first approximate expression (1) and the expression ( ² ) are within the range of 84 to 336 (mW / cm ² ) in which the irradiation intensity is changed. No maximum or minimum value was obtained for the second approximate expression.

In addition, when the integrated light quantity is 300 (mJ / cm ² ), the first approximate expression that is the expression (3) and the expression (4) within the range of 84 to 504 (mW / cm ² ) in which the irradiation intensity is changed. The following maximum value and minimum value were obtained for the second approximate expression.
First approximate expression: irradiation intensity = 262.8, reaction heat = 185.2
Second approximate expression: irradiation intensity = 280.9, reaction time = 88.6

Moreover, in the range of 98 to 588 (mW / cm ² ) in which the irradiation intensity is changed when the integrated light quantity = 350 (mJ / cm ² ), the following minimum value is obtained for the second approximate expression (6). However, for the first approximate expression (5), a maximum value was obtained outside the range of irradiation intensity.
First approximate expression: irradiation intensity = 33.75, reaction heat = 155.3 (outside the range of irradiation intensity)
Second approximate expression: irradiation intensity = 303.1, reaction time = 103.2

In addition, when the integrated light quantity is 600 (mJ / cm ² ), the following minimum value is obtained for the second approximate expression (8) within the range of 36 to 504 (mW / cm ² ) where the irradiation intensity is changed. However, the maximum value was not obtained for the first approximate expression (7).
Second approximation formula: irradiation intensity = 314.1, reaction time = 72.8

From the above results, the integrated light quantity under the condition that the first approximate expression has the maximum value and the second approximate expression has the minimum value within the range in which the irradiation intensity is changed is only 300 (mJ / cm ² ). Met.

Next, an integrated light quantity setting step (S13) is performed. As described above, in the local maximum / minimum value determining step, the integrated light amount under the condition that the first approximate expression has the maximum value and the second approximate expression has the minimum value is within the range in which the irradiation intensity is changed. , 300 (mJ / cm ² ). Here, when there are a plurality of integrated light quantities that satisfy these conditions, for example, it is preferable to select the one with a shorter 90% reaction time. For example, it is known that stickiness (tackiness) on the coating film surface decreases as the time at which the reaction converges after irradiation with ultraviolet rays (the shorter the 90% reaction time). Furthermore, in order to shorten the irradiation time and increase the productivity even in a good integrated light quantity, it is desirable to shorten the reaction time as much as possible. For these reasons, the one with a shorter 90% reaction time is selected.

Further, the irradiation intensity is determined between the irradiation intensity corresponding to the maximum value and the irradiation intensity corresponding to the minimum value. Here, the irradiation intensity corresponding to the maximum value of the first approximate expression is 262.8 (mW / cm ² ), and the irradiation intensity corresponding to the minimum value of the second approximate expression is 280.9 (mW / cm 2). ² ). Therefore, it is preferable to set the irradiation intensity within the range of 262.8 to 280.9 (mW / cm ² ) as the ultraviolet irradiation condition.

Next, an irradiation process (S14) is performed. In the irradiation step, ultraviolet rays are irradiated within the irradiation conditions set in the integrated light amount setting step, that is, the integrated light amount = 300 (mJ / cm ² ) and the irradiation intensity = 262.8 to 280.9 (mW / cm ² ). Irradiate towards the UV ink coating. Thereby, the coating film of UV ink can be hardened favorably in a short time.

Next, a strength test for evaluating the coating strength of the UV ink irradiated with ultraviolet rays in the ultraviolet irradiation treatment step was performed. Here, as a comparative example, the integrated light quantity is 200 (mJ / cm ² ), the two samples (No. 1 and No. 2) irradiated with ultraviolet rays with the irradiation intensity changed in two patterns, and the integrated light quantity is 300 as this embodiment. Three samples (Nos. 3 to 5) irradiated with ultraviolet rays by changing the irradiation intensity by 3 patterns at (mJ / cm ² ) were prepared.

Specifically, sample No1 is a coating film irradiated under irradiation conditions of integrated light quantity = 200 (mJ / cm ² ) and irradiation intensity = 90 (mW / cm ² ), and sample No2 has integrated light quantity = 200 ( mJ / cm ² ) and irradiation intensity = 165 (mW / cm ² ), and the film No. 3 has an integrated light amount = 300 (mJ / cm ² ) and irradiation intensity = 165 (mW / cm ² ). ² ) is a coating film irradiated under the irradiation conditions, and sample No. 4 is a coating film irradiated under irradiation conditions of integrated light quantity = 300 (mJ / cm ² ) and irradiation intensity = 265 (mW / cm ² ). No5 is a coating film irradiated under irradiation conditions of integrated light quantity = 300 (mJ / cm ² ) and irradiation intensity = 405 (mW / cm ² ). A coating strength test was conducted on these five samples. The strength test is performed in accordance with JIS K5600-5-4 (ISO / DIN 15184). The pencil hardness is HB or more and the coating film is resistant, and “O” is not recognized. Each was evaluated as “x”.

Next, the result of the hardness test will be described with reference to FIG. FIG. 10 is a table showing the results of a UV ink coating strength test. First, in Samples Nos. 1 and ² in which the integrated light quantity = 200 (mJ / cm ² ), the coating film strength was “x”. This is presumed that the integrated light quantity is too low, the decomposition rate of the photopolymerization initiator is slow, and the polymerization of the monomer and oligomer did not proceed. On the other hand, Sample Nos. 3 and 4 where the integrated light amount = 300 (mJ / cm ² ) had a coating film strength of “◯”. Here, since the irradiation intensity of sample No. 4 was within the range of 262.8 to 280.9 (mW / cm ² ) which is the irradiation intensity range, there was no problem with the coating film intensity. The irradiation intensity of sample No. 3 is out of the range of 262.8 to 280.9 (mW / cm ² ), which is the irradiation intensity range set in the integrated light quantity setting step, but there is a problem with the coating film intensity. There wasn't.

However, in sample No. 5, the integrated light intensity was 300 (mJ / cm ² ), but the coating film strength was “x”. This is presumably because the irradiation intensity was too high at 405 (mW / cm ² ), so that the reaction initiation rate of the photopolymerization initiator was high and the number of growing molecules increased, resulting in a decrease in molecular weight. . A coating film having a low molecular weight generally becomes a soft coating film, so that it seems that the coating film strength was not obtained. Therefore, it was proved that the coating film of UV ink irradiated with ultraviolet rays by the ultraviolet irradiation treatment process can obtain good coating strength. That is, according to the ultraviolet irradiation processing step of the present invention, it is possible to easily find an appropriate integrated light amount according to the type of UV ink and to irradiate ultraviolet light with the integrated light amount. Can be cured. Therefore, good coating quality of UV ink can be easily obtained.

  As described above, according to the ultraviolet irradiation method of the present embodiment, the integrated light amount and the irradiation intensity are set as the irradiation conditions for irradiating the UV ink with ultraviolet rays. Then, with respect to the UV ink to be used, the reaction heat amount and 90% reaction time of the UV ink are measured while changing the irradiation intensity and the irradiation time with a constant integrated light amount. Next, a first approximate expression indicating a change in reaction heat amount with respect to the irradiation intensity and a second approximate expression indicating a change in 90% reaction time with respect to the irradiation intensity are calculated. Here, it is determined whether or not the first approximate expression has a maximum value and the second approximate expression has a minimum value. When both of these conditions are satisfied, the polymerization reaction in the UV ink can proceed sufficiently and quickly within the range in which the irradiation intensity is changed. Therefore, the UV ink coating can be cured well in a short time.

  Next, an image forming system 100 that uses the above-described ultraviolet irradiation processing method and that can irradiate ultraviolet rays under an optimal irradiation condition for an ink image discharged onto a printing medium by a UV inkjet printer will be described with reference to FIG. FIG. 11 is a block diagram showing an electrical configuration of the image forming system 100.

  As shown in FIG. 11, the image forming system 100 measures the amount of reaction heat for each integrated light amount in order to obtain the optimum irradiation condition of the UV ink jet printer 20 and the UV ink used in the UV ink jet printer 20. The calorific analyzer 5 and the measurement data of the calorimeter 5 are used to determine the optimum irradiation conditions for the UV ink, create irradiation data relating to the irradiation conditions, and output the irradiation data to the UV inkjet printer 20 And a creation device 10. The calorimeter 5 is the same as the calorimeter used in the ultraviolet irradiation process described above, and a description thereof will be omitted.

  First, the UV inkjet printer 20 will be described. As shown in FIG. 11, the UV inkjet printer 20 is provided with a CPU 21 that controls the entire UV inkjet printer 20. The CPU 21 includes a ROM 22, a RAM 23, a flash memory 24, a UV drive circuit 30 for driving the UV lamp 40, a head drive circuit 31 for driving the inkjet head 41, and a transport mechanism for driving a transport mechanism 42 for transporting a print medium. A drive circuit 32 is connected via a bus 45. Further, a USB interface 35 is connected to the bus 45, and the irradiation data creation device 10 is connected to the USB interface 35.

  The ROM 22 has a program storage area for storing a control program for controlling the operation of the UV inkjet printer 20, a print execution program for executing a printing process, and settings and initial values necessary for executing the program. A program-related information storage area for storing information such as data, and various other storage areas are provided. Further, the RAM 62 is provided with an irradiation data storage area for storing irradiation data received from the irradiation data creation device 10 and other various storage areas. The flash memory 24 stores image data created based on an input image from the outside.

  Next, the irradiation data creation device 10 will be described. FIG. 12 is a block diagram showing an electrical configuration of the irradiation data creation device 10. The irradiation data creation device 10 is connected to the calorimetric analysis device 5 and the UV inkjet printer 20 via a communication cable based on a standard such as USB, for example. Then, the irradiation data creation device 10 creates irradiation data optimum for the UV ink based on the measurement data output from the calorific analyzer 5. Further, this irradiation data is transmitted to the UV inkjet printer 20, and ultraviolet irradiation by the UV lamp 40 is performed based on the irradiation data.

  As shown in FIG. 12, the irradiation data creation apparatus 10 is provided with a CPU 110 that controls the irradiation data. A ROM 111, a RAM 112, a CD-ROM drive 115, a hard disk 116 (hereinafter abbreviated as HDD 116), a display control unit 126, an input detection unit 127, and USB interfaces 129 and 130 are connected to the CPU 110 via the bus 114. Has been.

  The ROM 111 stores a program such as a BIOS executed by the CPU 110. A CD-ROM 131 that is a recording medium is inserted into the CD-ROM drive 115, and data recorded on the CD-ROM 131 is read by the CD-ROM drive 115. The CD-ROM 131 stores an irradiation data creation program according to the present invention and data used when the program is executed. Data read by the CD-ROM drive 115 is stored in various storage areas provided in the HDD 116.

  Further, the display control unit 126 is connected to a monitor 133 for displaying an operation screen, and controls the display of the monitor 133. The input detection unit 127 is connected to a keyboard 135 and a mouse 136 for a user to input an operation, and detects these inputs. The USB interface 129 is connected to the UV inkjet printer 20 which is an external device, and data can be transmitted and received. Furthermore, the USB interface 130 is connected to the irradiation data creation apparatus 10 that is an external device, and data can be transmitted and received.

  Next, the operation of the UV inkjet printer 20 will be schematically described. As shown in FIG. 11, in the UV inkjet printer 20, the CPU 21 reads image data stored in the flash memory 24 and controls the drive of the inkjet head 41. As a result, UV ink is ejected onto the print medium, and an ink image corresponding to the image data is formed. The print medium is transported from the inkjet head 41 along the transport path by the transport mechanism 42, and the ink image is fixed on the print medium by being irradiated with ultraviolet rays from the UV lamp 40. The driving of the transport mechanism 42 and the UV lamp 40 is controlled by the CPU 21. The irradiation conditions (irradiation time and irradiation intensity) of the UV lamp 40 are controlled based on the irradiation data received from the irradiation data creation device 10 described later.

  Next, irradiation data creation processing by the CPU 110 will be described with reference to FIG. FIG. 13 is a flowchart of irradiation data creation processing by the CPU 110. In this irradiation data creation process, the CPU 110 processes a part of the above-described ultraviolet irradiation process, and the created irradiation data is transmitted to the UV inkjet printer 20. Therefore, in the following description, the above description is used for the step of processing the same content as each step of the ultraviolet irradiation process.

  First, a plurality of UV ink samples before curing are set in the calorimeter 5. Then, by pressing the measurement switch, the measurement of the reaction heat amount and the reaction time is started in order for each of a plurality of preset integrated light amounts. The measurement data for each integrated light quantity is stored in a storage means provided in the calorimeter 5 as needed. Then, by turning on an output button (not shown), all measurement data stored in the storage means is output toward the irradiation data creation device 10. Note that the measurement data measured by the calorimeter 5 may be output to the irradiation data creation device 10 at any time without an output instruction.

  On the other hand, the CPU 110 of the irradiation data creation device 10 determines whether or not measurement data for each integrated light quantity has been received from the calorific value analysis device 5 (S21). If measurement data is not received (S21: NO), the process returns to S21 and monitoring is continued until measurement data is received. When measurement data is received from the calorimeter 5 via the USB interface 130 (S21: YES), the measurement data is stored in a measurement data storage area (not shown) of the RAM 112 (S22). Since the reaction time of the measurement data stored in the measurement data storage area is 100% reaction time, the 90% reaction time is calculated here and newly stored.

  Next, an approximate expression calculation process is performed (S23). In this approximate expression calculation process, the approximate data calculation process (see S11 shown in FIG. 1) of the ultraviolet irradiation process described above is performed using the measurement data (reaction heat amount, 90% reaction time) stored in the measurement data storage area of the RAM 112. ) Is executed. That is, the first approximate expression and the second approximate expression are respectively calculated from the first approximate curve of the reaction curve indicating the change in the reaction heat amount and the second approximate curve of the reaction curve indicating the change in the 90% reaction time. The first approximate expression and the second approximate expression are stored in an approximate expression storage area (not shown) of the RAM 112.

  Next, local maximum / minimum value determination processing is performed (S24). In the local maximum / minimum value determination process, the local maximum / minimum value determination process (see S12 shown in FIG. 1) of the above-described ultraviolet irradiation process is performed for the first approximate expression and the second approximate expression calculated in the approximate expression calculation process. ) Is executed. That is, within a predetermined range in which the irradiation intensity is changed, whether or not there is a maximum value in the first approximate expression and a minimum value in the second approximate expression is determined for each integrated light amount.

  Next, irradiation data setting processing is performed (S25). In this irradiation data setting process, the integrated light quantity is selected under the condition that the local maximum / minimum value determination process determines that the first approximate expression has a maximum value and the second approximate expression has a minimum value, and the integrated light quantity is irradiated. The data is stored in the HDD 116 as data (S26). When there are a plurality of integrated light amounts that satisfy the predetermined condition in the maximum / minimum value determination process, for example, the shorter 90% reaction time is selected in the integrated light amount setting process. The irradiation intensity is automatically determined between the irradiation intensity corresponding to the maximum value and the irradiation intensity corresponding to the minimum value. Next, the irradiation data stored in the HDD 116 is output toward the UV inkjet printer 20 via the USB interface 129 (S26). In this way, a series of flow of irradiation data creation processing is completed.

  The irradiation data output from the irradiation data creation device 10 is stored in the flash memory 24 via the bus 45 from the USB interface 35 of the UV inkjet printer 20. Then, the CPU 21 of the UV inkjet printer 20 sets the irradiation conditions (irradiation time and irradiation intensity) of the UV lamp 40 based on the irradiation data stored in the flash memory 24. Therefore, the UV ink ejected on the printing medium can be irradiated with ultraviolet rays under the optimal irradiation conditions, so that the polymerization reaction in the UV ink can proceed sufficiently and quickly. The ink image formed on the print medium can be fixed more reliably in a short time.

  In the above description, the UV ink jet printer 20 shown in FIG. 11 corresponds to the “printing apparatus” and “ultraviolet ray curable ink jet printer” of the present invention, and the calorimeter 5 corresponds to the “calorie measuring means” of the present invention. To do. Further, the CPU 110 that executes the process of S23 shown in FIG. 13 corresponds to the “approximate expression calculating means” of the present invention, and the CPU 110 that executes the process of S24 corresponds to the “maximum / minimum value determining means” of the present invention. The CPU 110 that executes the processes of S25 and S26 corresponds to the “data setting means” of the present invention.

  As described above, the image forming system 100 according to the present embodiment includes the UV inkjet printer 20 that discharges UV ink onto a print medium and cures it by irradiating ultraviolet rays. In this system, the calorific value analyzer 5 measures the amount of reaction heat for each accumulated amount of UV ink, and the measurement data is input to the irradiation data creation device 10. In the irradiation data creation device 10, first, using the received measurement data, from the first approximate curve of the reaction curve showing the change in the reaction heat amount and the second approximate curve of the reaction curve showing the change in the 90% reaction time, A first approximate expression and a second approximate expression are respectively calculated (S23). Next, with regard to the first approximate expression and the second approximate expression calculated in the approximate expression calculation process, whether the first approximate expression has a maximum value and the second approximate expression has a minimum value within a predetermined range in which the irradiation intensity is changed. No is determined for each integrated light quantity (S24).

  Further, in the local maximum / minimum value determination process, the integrated light amount under the condition determined to have the local maximum value in the first approximate expression and the local minimum value in the second approximate expression is selected, and the integrated light amount is determined as irradiation data ( S25) and stored in the HDD 116 (S26). The irradiation data stored in the HDD 116 is output toward the UV inkjet printer 20 (S27). In the UV inkjet printer 20, the irradiation data received from the irradiation data creation device 10 is stored in the flash memory 24, and the irradiation conditions (irradiation time and irradiation intensity) of the UV lamp 40 are set based on the irradiation data. Therefore, the UV ink ejected on the printing medium can be irradiated with ultraviolet rays under the optimal irradiation conditions, so that the polymerization reaction in the UV ink can proceed sufficiently and quickly. The ink image formed on the print medium can be fixed more reliably in a short time.

  Needless to say, the ultraviolet irradiation method, the irradiation data creation apparatus, and the image forming system 100 according to the present invention are not limited to the above-described embodiment, and various modifications are possible. In the above embodiment, the irradiation data creation device 10 uses the measurement data of the calorimetric analyzer 5 to determine the optimal irradiation conditions for the UV ink used in the UV inkjet printer 20. The irradiation data creation process may be performed.

  In the above-described embodiment, the UV inkjet printer 20 including the UV lamp 40 and the UV drive circuit 30 has been described as an example. However, for example, a UV irradiation device that includes these UV irradiation mechanisms and irradiates ultraviolet rays may be used. Is possible. In this case, the ultraviolet irradiation device can irradiate ultraviolet rays with a UV lamp based on the irradiation data received from the irradiation data creation device 10.

  Furthermore, although the image forming system 100 described in the above embodiment includes the calorific value analysis device 5, it may be an image forming system including an irradiation data creation device 10 and a UV inkjet printer 20.

  The ultraviolet irradiation method of the present invention is not limited to a printing apparatus, and can be applied to any apparatus that cures UV ink by irradiating it with ultraviolet light.

It is a flowchart which shows the flow of an ultraviolet irradiation process process. Is a table showing the measurement results of the integrated light amount ^{= 200 (mJ / cm 2)} . It is a table | surface which shows the measurement result of integrated light quantity = 300 (mJ / cm < ² >). It is a table | surface which shows the measurement result of integrated light quantity = 350 (mJ / cm < ² >). It is a table | surface which shows the measurement result of integrated light quantity = 600 (mJ / cm < ² >). Measurement data of the integrated amount of light = 200 (mJ / cm ²⁾ is a graph plotting. It is the graph which plotted the measurement data of integrated light quantity = 300 (mJ / cm < ² >). It is the graph which plotted the measurement data of integrated light quantity = 350 (mJ / cm < ² >). It is the graph which plotted the measurement data of integrated light quantity = 600 (mJ / cm < ² >). It is a table | surface which shows the result of the intensity | strength test of the coating film of UV ink. 1 is a block diagram showing an electrical configuration of an image forming system 100. FIG. 2 is a block diagram showing an electrical configuration of an irradiation data creation device 10. FIG. It is a flowchart which shows the flow of the irradiation data creation process by CPU110.

Explanation of symbols

5 Calorimetric Analysis Device 10 Irradiation Data Creation Device 20 UV Inkjet Printer 30 UV Drive Circuit 31 Head Drive Circuit 32 Transport Drive Circuit 40 UV Lamp 41 Inkjet Head 100 Image Forming System 110 CPU
111 ROM
112 RAM

Claims (14)

An ultraviolet irradiation method for ultraviolet curable ink,
While irradiating the ultraviolet curable ink with ultraviolet rays by changing the irradiation intensity and the irradiation time with a constant integrated light amount, the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured Measuring step for each of a plurality of the integrated light quantity set in advance,
From the measurement result in the measurement step, a first approximate expression of a first approximate curve indicating a change in the reaction heat amount with respect to a change in the irradiation intensity, and a second approximate curve indicating a change in the reaction time with respect to the change in the irradiation intensity. An approximate expression calculating step for calculating the second approximate expression of
In the first approximate expression and the second approximate expression calculated in the approximate expression calculating step, the first approximate expression has a maximum value within a predetermined range in which the irradiation intensity is changed, and the second approximation A maximum / minimum value determining step for determining whether or not the expression has a minimum value;
An integrated light quantity setting step for setting the integrated light quantity under the condition that the local maximum value / minimum value determining step has a local maximum value in the first approximate expression and the local approximate value is determined in the second approximate expression;
An ultraviolet irradiation method for ultraviolet curable ink, comprising: an irradiation step of irradiating the ultraviolet curable ink with ultraviolet light with the integrated light amount set in the integrated light amount setting step.   In the integrated light amount setting step, when there are a plurality of integrated light amounts that are determined to have the maximum value and the minimum value in the maximum value / minimum value determination step, the integration of the condition with the shortest reaction time is performed. 2. The method of irradiating ultraviolet rays of an ultraviolet curable ink according to claim 1, wherein the amount of light is set.   After the integrated light quantity setting step, the integrated between the first irradiation intensity corresponding to the maximum value of the first approximate curve and the second irradiation intensity corresponding to the minimum value of the second approximate curve. The ultraviolet irradiation method of the ultraviolet curable ink according to claim 1, further comprising an irradiation intensity setting step of setting an irradiation intensity under the integrated light amount set in the light amount setting step.   The ultraviolet ray of the ultraviolet curable ink according to any one of claims 1 to 3, wherein the reaction time is a 90% reaction time corresponding to 90% of a time until the ultraviolet curable ink is cured. Irradiation method. An irradiation data creation device for creating irradiation data used in an ultraviolet irradiation device of a printing apparatus that discharges ultraviolet curing ink onto a print medium and cures by irradiating with ultraviolet rays,
The heat intensity measurement means for measuring the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured changes the irradiation intensity and the irradiation time for each of a plurality of preset integrated light amounts. A first approximate expression of a first approximate curve indicating a change in the reaction heat amount with respect to a change in the irradiation intensity based on the reaction heat amount and the reaction time measured when the ultraviolet curable ink is irradiated with ultraviolet rays. And an approximate expression calculating means for calculating a second approximate expression of a second approximate curve indicating a change in the reaction time with respect to a change in the irradiation intensity,
In the first approximate expression and the second approximate expression calculated by the approximate expression calculation means, the first approximate expression has a maximum value within a predetermined range in which the irradiation intensity is changed, and the second approximation Local maximum / minimum value judging means for judging whether or not the formula has a local minimum;
Data setting for setting, as the irradiation data, the integrated light quantity under the condition that the maximum value / minimum value determining means has a maximum value in the first approximate expression and the minimum value is determined in the second approximate expression. Irradiation data creation apparatus characterized by comprising: means.   6. The irradiation data according to claim 5, wherein the data setting means sets the integrated light amount under the condition that the reaction time is the shortest when there are a plurality of the integrated light amounts set by the integrated light amount setting process. Creation device. The data setting means includes
Irradiation when irradiating the ultraviolet curable ink between a first irradiation intensity corresponding to the local maximum value of the first approximate curve and a second irradiation intensity corresponding to the local minimum value of the second approximate curve. The irradiation data creating apparatus according to claim 5 or 6, wherein intensity is set as the irradiation data.   8. The irradiation data creation device according to claim 5, wherein the reaction time is a 90% reaction time corresponding to 90% of a time until the ultraviolet curable ink is cured. The irradiation data creation device according to any one of claims 5 to 8,
An image forming system comprising the printing apparatus.   The image forming system according to claim 9, further comprising the calorific value measuring unit. An ultraviolet curable inkjet printer equipped with an ultraviolet curable ink and an ultraviolet irradiation device capable of irradiating ultraviolet rays by an optimum ultraviolet irradiation method unique to the ultraviolet curable ink,
The ultraviolet irradiating apparatus irradiates the ultraviolet curable ink with ultraviolet rays by the ultraviolet irradiating method according to any one of claims 1 to 3. An ultraviolet irradiation method for irradiating ultraviolet curable ink with a constant integrated light amount,
The amount of reaction heat of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured while irradiating the ultraviolet curable ink with ultraviolet rays while changing the irradiation intensity and the irradiation time with a constant integrated light amount When measuring each
In the first approximate expression of the first approximate curve showing the change of the reaction heat amount with respect to the change of the irradiation intensity, it has a maximum value within the range in which the irradiation intensity is changed,
In the second approximate expression of the second approximate curve indicating the change in the reaction time with respect to the change in the irradiation intensity, the ultraviolet curable ink is irradiated with ultraviolet rays with an integrated light amount having a minimum value within the range in which the irradiation intensity is changed. An ultraviolet irradiation method for an ultraviolet curable ink characterized by irradiating. An ultraviolet irradiation device for irradiating ultraviolet rays with a constant integrated light quantity to ultraviolet curable ink,
The amount of reaction heat of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured while irradiating the ultraviolet curable ink with ultraviolet rays while changing the irradiation intensity and the irradiation time with a constant integrated light amount When measuring each
In the first approximate expression of the first approximate curve showing the change of the reaction heat amount with respect to the change of the irradiation intensity, it has a maximum value within the range in which the irradiation intensity is changed,
In the second approximate expression of the second approximate curve indicating the change in the reaction time with respect to the change in the irradiation intensity, the ultraviolet curable ink is irradiated with ultraviolet rays with an integrated light amount having a minimum value within the range in which the irradiation intensity is changed. An ultraviolet irradiation device characterized by irradiating. A printing apparatus that discharges ultraviolet curable ink onto a printing medium and cures by irradiating ultraviolet rays with a constant integrated light amount,
The accumulated light amount is
When measuring the reaction heat amount of the ultraviolet curable ink and the reaction time until the ultraviolet curable ink is cured while irradiating the ultraviolet curable ink with ultraviolet rays while changing the irradiation intensity and the irradiation time. In addition,
In the first approximate expression of the first approximate curve showing the change of the reaction heat amount with respect to the change of the irradiation intensity, it has a maximum value within the range in which the irradiation intensity is changed,
In the second approximate expression of the second approximate curve showing the change in the reaction time with respect to the change in the irradiation intensity, the printing apparatus is an integrated light amount having a minimum value within a range in which the irradiation intensity is changed.

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