JP5703954B2 - Inkjet recording method - Google Patents

Description

  The present invention relates to an ink jet recording method using an actinic ray curable inkjet ink containing a gelling agent and an actinic ray curable composition.

  Conventionally, actinic ray curable compositions with the property of being cured by active energy rays such as ultraviolet rays and electron beams are used for paints, adhesives, printing inks, printed circuit boards, and electrical insulation related to plastics, paper, woodwork or inorganic materials. Have been put to practical use in various applications.

  Moreover, as an inkjet ink system using these polymerizable compositions, there is an ultraviolet curable inkjet ink that cures with actinic rays, specifically ultraviolet rays. In recent years, it has been attracting attention from the viewpoint that an image having high scratch resistance and adhesion can be formed even on a recording medium having poor ink absorbability.

  However, in an image forming method using an inkjet system using these ultraviolet curable inkjet inks, when performing high-speed recording such as a single-pass recording method using a line recording head or a high-speed serial method with a few passes as an inkjet recording head, The unity of the matching dots cannot be sufficiently suppressed, and the image quality may be deteriorated. In addition, when recording a color image, there is a problem that color mixing occurs between dots of different color materials and the image quality deteriorates.

  Furthermore, in various applications of the inkjet method, it is inconvenient to closely match the gloss of the printed image with the gloss of the non-printed area (unprinted part) of the substrate and reduce the difference in gloss from the unprinted part. This is desirable from the viewpoint of obtaining a small number of images. In particular, in the field of commercial printing, if the gloss of the printed paper surface and the gloss of the printed surface are different, it is felt that the gloss is uncomfortable. Therefore, it is necessary to closely match the gloss of the print area and the gloss of the non-print area depending on the paper type. However, in the above method, since the image has a certain thickness after the ink is cured, it cannot follow the surface shape of the paper type, and the image surface formed by the ink is glossy or matte gloss regardless of the paper type. In other words, the gloss of the print area and the gloss of the non-print area cannot be closely matched, and there is a problem that the gloss is uncomfortable.

  As a method for solving the above-mentioned problem of image quality deterioration, an actinic ray curable inkjet ink containing a gelling agent in an ink and having a solid-liquid phase transition characteristic depending on temperature is used. A technique is disclosed in which solidification prevents ink droplets from coalescing to prevent image quality deterioration.

For example, Patent Document 1 discloses a method of forming an image using an inkjet ink containing a gelling agent and a curable monomer. However, when image recording is performed using a gel ink composed of the types of gelling agents disclosed and the amount of the gelling agent added, it is possible to prevent coalescence of ink droplets by rapid gelation and prevent deterioration of image quality. However, the ink described in Patent Document 1 is an ink jet ink having a very high viscosity of 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ mPa · s at a recording temperature of 50 ° C. or less. Since it has a solidifying power enough to suppress penetration, unless the intermediate transfer method is used, the dot solidifying power is too strong, resulting in an extremely low gloss. Has the problem of producing a matte texture. Therefore, when the inkjet ink disclosed in Patent Document 1 is printed on a highly glossy base material, the problem that the glossiness of the printed portion and the non-printed portion are uncomfortable cannot be solved.

  On the other hand, Patent Document 2 discloses a printing method in which a thixotropic curable gel ink is used and recording is performed so that the difference between the ink temperature during ejection and the temperature of the recording medium is 30 ° C. or more. This proposed method is aimed at improving curability, and there is no description or suggestion about a method of adjusting the gloss of the printed portion to be formed with respect to the gloss of the recording medium. In addition, when the gelation temperature of the actinic radiation curable inkjet ink is high or when the ink after gelation is hard, similarly, a decrease in gloss due to excessively strong dot solidification force is observed in the temperature range. There was a case.

  Patent Document 3 discloses a technique for reducing the difference in gloss between a print area and a non-print area using a curable phase change ink. However, the technique specifically controls the gloss of an image to be formed. Is not described at all.

  Further, in Patent Document 4, after an overcoat liquid containing a gelling agent is landed on a recording medium and before irradiation with ultraviolet rays, it is heated to a temperature substantially equal to or higher than the phase transition temperature, and an image is obtained. Although attempts to increase gloss are described, there is no problem in the case of an overcoat liquid, but when the same operation is performed with a gelling agent-containing ink containing a coloring material that is forming an image, color mixing may occur. It was a problem that led to image quality degradation.

JP 2009-041015 A Special table 2009-510184 gazette JP 2009-132919 A JP 2010-106275 A

  The present invention has been made in view of the above problems, and its purpose is high-definition when recording on a non-absorbent recording medium such as a film or a bonding paper, or a slightly absorbent recording medium such as a coated paper. Another object of the present invention is to provide an ink jet recording method using an actinic ray curable ink jet ink that closely matches the gloss of the printing area and the gloss of the non-printing area of the base material and obtains a uniform and glossy feeling over the entire image. .

  The above object of the present invention is achieved by the following configurations.

1. Inkjet recording for forming an image on a recording medium using an actinic ray curable inkjet ink containing 1.0 to 10% by mass of a coloring material, a photopolymerizable compound and a photopolymerization initiator, and a gelling agent In the method, the actinic ray curable inkjet ink has a viscosity at 30 ° C. of 10 ² mPa · s or more and 10 ⁵ mPa · s or less, a gelation temperature Tgel of 40 ° C. or more and 80 ° C. or less, and a recording medium An image formed at a temperature T1 (gelation temperature Tgel-20 ° C. of the actinic radiation curable ink-jet ink) is G1 with a 60-degree specular gloss, and a temperature T2 of the recording medium (gelation temperature of the actinic radiation curable ink-jet ink). When the 60 ° specular glossiness of an image formed at Tgel-5 ° C. is G2, the 60 ° specular gloss difference (G1−G2) is 35 or more, and An inkjet recording method comprising heating an actinic ray curable inkjet ink to a gelling temperature Tgel + 10 ° C. or higher and a gelling temperature Tgel + 40 ° C. to form an image under the following condition 1 or condition 2.

  Condition 1: A recording medium having a 60 ° specular gloss of 69 or more and 100 or less is used. The surface temperature Ts of the recording medium is set to a gelling temperature Tgel-30 ° C. or higher of the actinic radiation curable inkjet ink, and the gelation temperature Tgel is set. The image is formed by controlling the temperature below -10 ° C.

  Condition 2: Using a recording medium having a 60 ° specular gloss of 10 or more and less than 69, the surface temperature Ts of the recording medium is set to a gelling temperature Tgel of 10 ° C. or higher of the actinic radiation curable inkjet ink, and a gelation temperature Tgel. An image is formed by controlling the temperature range below -5.0 ° C.

  2. 2. The ink jet recording method according to 1 above, wherein the image is formed under a condition satisfying both of the condition 1 and the condition 2.

  3. 3. The ink jet recording method according to 1 or 2, wherein the condition 2 is the following condition 2A and condition 2B, and an image is formed under the condition 1, the condition 2A or the condition 2B.

  Condition 2A: A recording medium having a 60 ° specular gloss of 55 or more and less than 69, the surface temperature Ts of the recording medium is set to a gelling temperature Tgel of 10 ° C. or more of the actinic radiation curable inkjet ink, and a gelation temperature Tgel. An image is formed by controlling the temperature range below -7.5 ° C.

  Condition 2B: Using a recording medium having a 60 ° specular gloss of 10 or more and less than 55, the surface temperature Ts of the recording medium is a gelation temperature Tgel of 7.5 ° C. or more of the actinic ray curable inkjet ink. The image is formed by controlling the temperature within a temperature range of less than Tgel-5.0 ° C.

  4). 4. The ink jet recording method according to any one of 1 to 3, wherein the gelling agent is a fatty acid ester or an aliphatic ketone.

  5. 5. The ink jet recording method according to any one of 1 to 4, wherein the gelling agent is stearyl stearate, batyl stearate, cetyl palmitate, or pentatriacontan-18-one (stearon). .

  6). 6. The inkjet recording method according to any one of 1 to 5, wherein the gelation temperature Tgel of the actinic ray curable inkjet ink is 45 ° C. or more and 65 ° C. or less.

  7). 7. The ink jet recording according to any one of 1 to 6, wherein a content of the gelling agent in the actinic ray curable ink jet ink is 2.0% by mass or more and 7.0% by mass or less. Method.

  8). 8. The ink jet recording method according to any one of 1 to 7, wherein the actinic ray curable ink jet ink is emitted with a viscosity in an ink jet recording head of 3 mPa · s or more and less than 20 mPa · s.

  9. 9. The ink jet recording method according to any one of 1 to 8, wherein the recording medium is a slightly absorbent recording medium having a coating layer.

  10. 10. The inkjet recording method according to any one of 1 to 9, wherein an image is printed by a single pass method.

  According to the present invention, when recording on a non-absorbent recording medium such as a film or a bonding paper, or a fine-absorbing recording medium such as a coated paper, the recording area has high definition and gloss of the printing area and the non-printing area of the substrate. It was possible to provide an ink jet recording method using an actinic ray curable ink jet ink that closely matches the gloss and obtains a uniform and glossy gloss throughout the image.

It is the microscope surface observation photograph of the image printed by changing the temperature of a recording medium. It is a graph which shows an example of the relationship between the printing temperature of the typical ink recording medium, and the glossiness of a formed image. This is a single-pass recording type inkjet recording apparatus. This is a serial recording type inkjet recording apparatus. It is a graph which shows the relationship between the printing temperature of the recording medium of the inks 2-4 used in the Example, and the glossiness of a formed image.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

As a result of intensive studies in view of the above problems, the present inventor has actinic ray curing containing 1.0% by mass or more and 10% by mass or less of a coloring material, a photopolymerizable compound, a photopolymerization initiator, and a gelling agent. In the ink jet recording method of forming an image on a recording medium using an ink jet ink, the actinic ray curable ink jet ink has a viscosity of 10 ² mPa · s to 10 ⁵ mPa · s at 30 ° C. When the temperature Tgel is 40 ° C. or more and 80 ° C. or less, and the image formed at the temperature T1 of the recording medium (gelation temperature Tgel-20 ° C. of the actinic radiation curable inkjet ink) is G1, the 60-degree specular gloss is G1. When the 60 ° specular glossiness of an image formed at a medium temperature T2 (gelation temperature Tgel-5 ° C. of the actinic radiation curable inkjet ink) is G2, a 60 ° mirror The surface gloss difference (G1-G2) is 35 or more, and the actinic radiation curable inkjet ink is heated to a gelling temperature Tgel + 10 ° C. or more and less than a gelling temperature Tgel + 40 ° C. High-definition and glossy printing area when recorded on non-absorbent recording media such as film and pasting paper and fine-absorbing recording media such as coated paper by the inkjet recording method characterized by forming As a result, the present invention has been found to realize an inkjet recording method using an actinic ray curable inkjet ink that closely matches the gloss of the non-printing area of the substrate and obtains a gloss that is homogeneous and uncomfortable over the entire image. It is.

  Hereinafter, the details of the inkjet recording method of the present invention will be described.

  The present invention relates to ink physical properties (viscosity and gel) of actinic ray curable inkjet ink (hereinafter also referred to as actinic ray curable ink or simply ink) containing a colorant, a photopolymerizable compound, a photopolymerization initiator, and a gelling agent. ), The type of recording medium to be applied to printing, and the temperature of the recording medium at the time of printing are controlled within an appropriate range, so that the gloss of the formed image in the printing area to be formed can be arbitrarily controlled, and high image quality can be achieved. This is an ink jet recording method using an innovative actinic ray curable ink jet ink that can achieve a natural image gloss without a sense of incongruity (gloss difference) while maintaining it.

  The actinic ray curable inkjet ink used in the inkjet recording method of the present invention is characterized in that it contains a gelling agent in an amount of 1.0% by mass or more and 10% by mass or less. Has the property of phase transition.

  The sol-gel phase transition referred to in the present invention is a solution state having fluidity at a high temperature, but by cooling to below the gelation temperature, the entire ink liquid is gelled and changed to a state in which the fluidity has been lost. In this state, the fluidity is lost, but when heated to a temperature higher than the solation temperature, it returns to a fluid state with fluidity.

  In the present invention, gelation refers to interactions such as a lamellar structure, a polymer network formed by non-covalent bonds or hydrogen bonds, a polymer network formed by a physical aggregation state, and an aggregate structure of fine particles. This refers to a structure in which substances lose their independent motion due to the interaction of microcrystals, etc., and indicate a solidified, semi-solidified, or thickened state with a sudden increase in viscosity or elasticity. Point to. Moreover, solification means the state which changed into the liquid state with fluidity | liquidity after the interaction formed by the said gelatinization was eliminated. In addition, the solation temperature in the present invention is a temperature at which fluidity is exhibited by solification when the gelled ink is heated, and the gelation temperature is for cooling the ink in the sol state. As it is done, it refers to the temperature at which gelation occurs and fluidity decreases.

  Since the actinic ray curable ink according to the present invention that undergoes a sol-gel phase transition is in a liquid state at a high temperature, it can be stably ejected by an ink jet recording head. When recording using this actinic ray curable ink in a high temperature state, after the ink droplets have landed on the recording medium, the ink is gelated and solidified quickly by natural cooling due to the temperature difference, and as a result, adjacent dots Image quality can be prevented by preventing unification. However, when the solidification force of the ink droplets is strong, the dots are isolated from each other, resulting in unevenness in the image area and extreme reduction in gloss, so that a matte tone image can be formed regardless of the substrate type. When printed on a high-gloss base material, glossy inhomogeneity may occur. As a result of intensive studies by the inventors, the solidification force of the ink droplets, the gelation temperature of the ink, and the glossiness of the recording medium and the temperature of the recording medium are within the scope of the present invention, so that the ink droplets can be combined. It has been found that the image quality can be prevented by preventing the deterioration of the image quality, and further, an image that gives the most natural glossiness can be combined with the gloss of the base material.

  The inventors consider this reason as follows.

  After ink droplets have landed on the recording medium and before the adjacent ink droplets landed, the ink solidifies, resulting in a decrease in gloss and an unnatural sparkle in the image area. On the other hand, if the ink droplets solidify after a while after the adjacent ink droplets land and coalesce, the droplets come close to each other, leading to extreme image quality degradation. As a result of intensive studies by the inventors, it has been found that by controlling the viscosity at the time of ink landing, liquid coalescence can be prevented, and adjacent ink droplets can be appropriately leveled to obtain a natural gloss feeling. .

Furthermore, the ink jet recording method of the present invention is characterized in that the viscosity of the ink droplets after gelation is controlled by controlling the surface temperature of the recording medium. The viscosity upon ink landing depends on the surface temperature of the recording medium, the structure of the gelling agent, and the amount of gelling agent added. That is, by using an ink containing 0.1 to 10% by mass of a gelling agent and having a viscosity at 30 ° C. of 10 ² mPa · s or more and less than 10 ⁵ mPa · s, Viscosity control in the temperature range is possible, which is preferable from the viewpoint of achieving both image quality and natural gloss.

The reason is presumed as follows. If the ink has a viscosity at 30 ° C. of 10 ² mPa · s or more, the ink has a viscosity sufficient to prevent the ink droplets from being coalesced, and image quality deterioration can be prevented in the above temperature range. Further, if the viscosity at 30 ° C. is less than 10 ⁵ mPa · s, the viscosity after gelation is not excessively high, and the increase in viscosity can be largely suppressed during the cooling process, thereby preventing unevenness of dots. It is possible to suppress the occurrence of surface irregularities and to prevent a decrease in gloss. On the other hand, since the ink according to the present invention becomes a viscous gel having an appropriate viscosity after gelation, the dots are united to some extent during the cooling process and are appropriately leveled to achieve both high image quality and high gloss. Yes.

  In the ink jet recording method of the present invention, the actinic radiation curable ink jet ink according to the present invention is heated to a temperature range of a gelling temperature Tgel + 10 ° C. or higher and a gelling temperature Tgel + 40 ° C. or less on the recording medium from the ink jet recording head. Discharging is one of the features. By controlling the temperature of the actinic radiation curable inkjet ink within the range specified above, even an actinic radiation curable inkjet ink containing a gelling agent can be stably ejected.

  A technical feature of the ink jet recording method of the present invention is that an image is formed by controlling the heating temperature of the recording medium in relation to the glossiness of the recording medium to be applied.

  That is, by applying a recording medium having the characteristics specified by the following Condition 1 or Condition 2, the glossiness of the non-printed portion of the recording medium and the glossiness of the ink according to the present invention including the gelling agent to be formed are included. By making these close to each other, it is possible to reduce the gloss difference between the printed portion and the non-printed portion, and to form a natural and uncomfortable image.

  Condition 1: A recording medium having a 60 ° specular gloss of 69 or more and 100 or less is used. The recording medium has a gelation temperature Tgel of −20 ° C. or more and less than a gelation temperature of Tgel−10 ° C. of the actinic radiation curable inkjet ink. The image is formed by heating in the above temperature range.

  Condition 2: A recording medium having a 60-degree specular gloss of 10 or more and less than 69 is used. The recording medium has a gelation temperature Tgel of 10 ° C. or higher and a gelation temperature of Tgel-5.0 of the actinic radiation curable inkjet ink. Image formation is performed by heating to a temperature range of less than ℃.

  That is, the actinic ray curable inkjet ink according to the present invention has G1 as the 60-degree specular gloss of an image formed at a temperature T1 of the recording medium (gelation temperature Tgel-20 ° C. of the actinic ray curable inkjet ink), When the 60 ° specular glossiness of an image formed at the temperature T2 of the recording medium (gelation temperature Tgel-5 ° C. of the actinic radiation curable inkjet ink) is G2, the 60 ° specular gloss difference (G1-G2) is When using a recording medium having a high glossiness, the ink has a characteristic of 35 or more. By setting the heating temperature of the recording medium low and gelling in a short time, a high gloss image Form. On the other hand, when a low-gloss recording medium is used, the recording medium is heated to a higher temperature and slowly gelled to form a low-gloss image. This is a method for forming an image with less image.

  The 60-degree specular gloss referred to in the present invention is a value measured according to the measurement method defined in JIS-Z-8741. Examples of the apparatus that can be used for measuring the 60-degree specular gloss according to the present invention include a precision gloss meter GM-26D, a true gloss GM-26DPRO, and a variable angle gloss meter GM-3D (manufactured by Murakami Color Research Laboratory). ), Variable angle gloss meter VGS-1000DP (manufactured by Nippon Denshoku Industries Co., Ltd.), digital variable angle gloss meter (Suga Test Instruments Co., Ltd.), and the like. In this invention, the value measured using the variable angle gloss meter PG-1M, VGS-1001DP (made by Nippon Denshoku Industries Co., Ltd.) is applied.

  Furthermore, in the present invention, as the condition 2, it is preferable to set more detailed conditions, and it is preferable to use the following conditions 2A and 2B from the viewpoint of setting more appropriate conditions.

  Condition 2A: A recording medium having a 60-degree specular gloss of 55 or more and less than 69 is used. The recording medium has a gelation temperature Tgel of 10 ° C. or higher and a gelation temperature Tgel of 7.5 of the actinic radiation curable inkjet ink. Image formation is performed by heating to a temperature range of less than ℃.

  Condition 2B: A recording medium having a 60 ° specular glossiness of 10 or more and less than 55 is used. The recording medium has a gelling temperature Tgel of 7.5 ° C. or higher and a gelation temperature of Tgel-5 of the actinic ray curable inkjet ink. Image formation is performed by heating to a temperature range of less than 0 ° C.

  In the ink jet recording method of the present invention, the surface shape formed by the ink according to the present invention after gelation is controlled by controlling the surface temperature of the recording medium. It depends on the surface temperature Ts of the medium, the structure of the gelling agent, and the amount of gelling agent added.

  The technical features of the inkjet recording method of the present invention will be further described with reference to the drawings.

  The difference between the gel temperature Tgel of the actinic radiation curable inkjet ink and the surface temperature Ts of the recording medium is the difference in the gelation speed in the cooling process. When the difference between Tgel and Ts is large, the ink containing the gelling agent is recorded. When the ink is landed on the medium, it is rapidly cooled, and conversely, when the difference between Tgel and Ts is small, the ink containing the gelling agent is gradually cooled when landed on the recording medium. In general, when the crystallization rate is high, that is, when the difference between Tgel and Ts is large, microcrystals are formed, and when the difference between Tgel and Ts is small, that is, when the crystallization rate is low, crystal growth occurs and crystals are formed. It is known to become coarse.

  FIG. 1 is an optical micrograph showing an example of the surface state of a formed image depending on the difference between the gelation temperature Tgel and the surface temperature Ts of the recording medium.

  The photograph shown in FIG. 1A is a surface shape of an image formed when the difference between the gelation temperature Tgel and the surface temperature Ts of the recording medium is large, and a smooth and glossy image is formed.

  On the other hand, the photograph shown in FIG. 1B is a surface shape of an image formed when the difference between the gelation temperature Tgel and the surface temperature Ts of the recording medium is small, and rough irregularities generated in the gel formation process occur. A glossy image is formed. From this result, it is clear that the difference in surface shape formed by the gel after gelation changes the gloss of the print area.

  The relationship of the glossiness of the formed image with respect to the temperature of the recording medium of the actinic ray curable inkjet ink containing the gelling agent having such characteristics will be specifically described with reference to the drawings.

  FIG. 2 is a graph showing an example of the relationship between the gloss of the formed image and the temperature of the recording medium using an actinic radiation curable inkjet ink containing a gelling agent.

  In FIG. 2, an actinic ray curable inkjet ink containing stearyl stearate as a gelling agent and having a gelation temperature Tgel of 53 ° C. (specific ink composition is ink 1 described in Example 1 described later). The graph shows the glossiness of a printed image formed by changing the surface temperature of the recording medium from 30 ° C. to 48 ° C., the horizontal axis represents the surface temperature Ts of the recording medium, and the vertical axis represents 60 ° of the printed image formed. Gloss is shown.

  As shown in FIG. 2, the temperature region exceeding 10 ° C. (the region of 30 ° C. or more and less than 43 ° C. in FIG. 2), that is, more rapidly than the gelation temperature Tgel (53 ° C.) of the actinic radiation curable inkjet ink. In a region where an image is formed by cooling, an image having a glossiness of 69 or higher is formed. On the other hand, an image formed on a recording medium having an ink gelling temperature Tgel (53 ° C.) in the range of −5 to −10 ° C. forms an image having a relatively low gloss of less than 69. It turns out that it has a characteristic.

  In the actinic ray curable inkjet ink shown in FIG. 2, the 60 ° specular gloss G1 of the image formed at the temperature T1 of the recording medium (the gelation temperature Tgel of the actinic ray curable inkjet ink −20 ° C.) is 79. Yes, the 60 ° specular glossiness G2 of the image formed at the temperature T2 of the recording medium (gelation temperature Tgel-5 ° C. of the actinic radiation curable ink-jet ink) is 32, and the 60 ° specular gloss difference (Δ glossiness) = G1-G2) is 47.

  In the image formation using the actinic ray curable inkjet ink having the characteristic that the gloss changes in conjunction with the surface temperature Tg of the recording medium as described above, the recording medium to be applied is not printed from the profile shown in FIG. By appropriately setting the surface temperature Tg of the recording medium so as to match the 60 ° gloss value (details will be described later), the gloss of the unprinted portion of the recording medium and the formed image can be approximated. Thus, it is possible to obtain an image having a gloss that is uniform and uncomfortable throughout the image. According to the inkjet recording method of the present invention, it is possible to obtain an image having a uniform glossiness with a small gloss difference on various recording media having a wide range of glossiness using a single actinic ray curable inkjet ink. it can.

  The gloss homogeneity referred to in the present invention means that a state where the gloss of a microscopic part of the image is inhomogeneous is not visually observed, and the entire surface of the image, particularly the gloss of the solid print portion and the non-print area. It may indicate either a state in which the gloss is uniform or a numerical value represented by an absolute gloss value, for example, a 60-degree specular gloss value, indicating that the difference between the print area and the non-print area is small.

  Hereinafter, the detailed configuration of the actinic ray curable inkjet ink used in the present invention will be described.

《Gelling agent》
The ink according to the present invention is characterized in that the gelling agent is contained in an amount of 1.0% by mass to 10% by mass with respect to the total mass of the ink.

  As described above, gelation in the present invention refers to a mutual structure such as a lamellar structure, a polymer network formed by non-covalent bonds or hydrogen bonds, a polymer network formed by a physical aggregation state, and an aggregate structure of fine particles. This refers to a structure in which substances lose their independent motion due to action, interaction of precipitated microcrystals, etc., and solidify, semi-solidify, or increase in viscosity with sudden increase in viscosity and elasticity. That means.

  In general, as a gelling agent, it becomes a fluid solution (sometimes called a sol) by heating and returns to the original gel state when cooled, and once gelled, it is heated afterwards. There is also a heat irreversible gel that does not return to the solution (sol state) again. The gel formed by the gelling agent according to the present invention is preferably the former thermoreversible gel from the viewpoint of preventing clogging in the ink jet recording head.

  In the actinic ray curable ink according to the present invention, one of the characteristics is that the gelation temperature Tgel (phase transition temperature) of the ink is 40 ° C. or more and 80 ° C. or less, preferably 45 ° C. or more and 65 ° C. It is as follows. If the gelation temperature Tgel of the ink is 40 ° C. or higher, stable ejection can be obtained without being affected by the printing environment temperature when ejecting ink droplets from the recording head. If so, it is not necessary to heat the inkjet recording apparatus to an excessively high temperature, and the load on the head of the inkjet recording apparatus and the members of the ink supply system can be reduced.

  The gelation temperature Tgel of the ink as used in the present invention means a temperature at which the viscosity of the ink rapidly changes from a fluid solution state to a gel state, and includes a gel transition temperature, a gel dissolution temperature, It is synonymous with terms called phase transition temperature, sol-gel phase transition temperature, and gel point.

  The gelation temperature Tgel and ink viscosity (complex viscosity) of the actinic radiation curable ink according to the present invention are measured using various rheometers (for example, a stress control type rheometer using a cone plate, Physica MCR series, manufactured by Anton Paar). It can be obtained by measuring the temperature change of the dynamic viscoelasticity of the actinic ray curable ink according to the invention. Since the solation temperature and the gelation temperature have the property of changing depending on the temperature rising / falling rate, data measured under the following conditions are used in the present invention.

The gelation temperature Tgel of the actinic radiation curable ink according to the present invention is a temperature at which the storage elastic modulus G ′ becomes 100 mPa or more when the temperature change of dynamic viscoelasticity is measured, and the viscosity of the ink at 30 ° C. is , Measurement temperature: 30 ° C., temperature increase / decrease rate: 0.1 ° C./s, strain: 5%, angular frequency: complex obtained by measuring temperature change of dynamic viscoelasticity under conditions of 10 radian / s Refers to the viscosity value. The storage elastic moduli G ′ and G ″ were measured for temperature change of dynamic viscoelasticity at a temperature rising / falling rate: 0.1 ° C./s, strain: 5%, angular frequency: 10 radian / s. In the invention, the value obtained by the temperature drop measurement of dynamic viscoelasticity is used as the value of G ′ at T _m , but the value obtained by the temperature rise measurement may be used.

  Specific examples of the gelling agent preferably used in the present invention include, for example, low-molecular oil gelling agents described in JP-A-2005-126507, JP-A-2005-255821 and JP-A-2010-1111790, Amide compounds (available from Ajinomoto Fine Techno) such as N-lauroyl-L-glutamic acid dibutylamide, N-2 ethylhexanoyl-L-glutamic acid dibutylamide, and 1,3: 2,4-bis-O-benzylidene- Dibenzylidene sorbitols such as D-glucitol (trade name: Gelol D, available from Shin Nippon Rika), petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam, candelilla wax, carnauba wax, rice Wax, wax, jojoba oil, jojoba solid Plant waxes such as C, jojoba ester, animal waxes such as beeswax, lanolin and whale wax, mineral waxes such as montan wax and hydrogenated wax, hardened castor oil or hardened castor oil derivatives, and montan wax derivatives , Modified waxes such as paraffin wax derivatives, microcrystalline wax derivatives or polyethylene wax derivatives, higher fatty acids such as behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, erucic acid, and stearyl alcohol Higher alcohols such as alcohol and behenyl alcohol, hydroxystearic acid such as 12-hydroxystearic acid, 12-hydroxystearic acid derivatives, lauric acid amide, stearic acid amide, behenic acid amide, Fatty acid amides such as acid amides, erucic acid amides, ricinoleic acid amides, 12-hydroxystearic acid amides (for example, Nikka Amide series; Nippon Kasei Co., Ltd., ITOWAX series; Ito Oil Co., Ltd., FATTYAMID series; Kao N-substituted fatty acid amides such as N-stearyl stearamide, N-oleyl palmitate, N, N′-ethylenebisstearylamide, N, N′-ethylenebis12-hydroxystearylamide, Special fatty acid amides such as N, N'-xylylene bisstearyl amide, higher amines such as dodecylamine, tetradecylamine or octadecylamine, stearyl stearate, batyl stearate, cetyl palmitate, oleil palmitate, glycerin fatty acid Fatty acid ester compounds such as esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters, polyoxyethylene fatty acid esters (for example, EMALLEX series; manufactured by Nihon Emulsion Co., Ltd., Riquemar series; manufactured by Riken Vitamin Co., Ltd.) And Poem series; manufactured by Riken Vitamin Co., Ltd.), sucrose fatty acid esters such as sucrose stearic acid and sucrose palmitic acid (for example, Ryoto Sugar Ester Series; manufactured by Mitsubishi Chemical Foods), and pentatriacontane-18- Synthetic waxes such as aliphatic ketones (for example, Kao wax T1; manufactured by Kao Corporation), polyethylene wax, α-olefin maleic anhydride copolymer wax, and polymerizable waxes (UNILIN series) Baker-Petrolite Corporation) and a dimer acid, dimer diol (PRIPOR Series; manufactured by CRODA Co., Ltd.). Moreover, said gelling agent may be used independently and may be used in mixture of 2 or more types.

  Among the above compounds, the gelling agent according to the present invention is preferably fatty acid, fatty acid derivative or aliphatic ketone, more preferably stearyl stearate, batyl stearate, cetyl palmitate or pentatriacontan-18-one ( Stearone).

  In the ink according to the present invention, by containing a gelling agent, after being ejected from the ink jet recording head, it immediately enters a gel state upon landing on the recording medium, and mixing of dots or dot coalescence is suppressed, High image quality can be formed during high-speed printing, and then the photocurable compound is cured by irradiation with actinic rays to be fixed on the recording medium to form a firm image film. Also, by adding two or more kinds of gelling agents with different gelation temperatures, the growth of crystals, the size of crystals to be generated can be controlled, and the surface morphology of the gel can be controlled to obtain any gloss. Is possible. The gelling agent content is 1.0% by mass or more and 10% by mass or less of the total mass of the ink, and is 2.0% by mass or more and 7.0% by mass or less. More preferred. By making the content of the gelling agent 1.0% by mass or more, gel formation is sufficient, deterioration of image quality due to dot coalescence can be suppressed, and light is increased by thickening ink droplets due to gel formation. When used in a radical curing system, photocurability due to oxygen inhibition can be reduced, and by setting it to 10% by mass or less, deterioration of the cured film due to uncured components after irradiation with actinic rays, inkjet ejection properties Can be reduced.

<< Photopolymerizable compound >>
The actinic ray curable ink according to the present invention contains a photopolymerizable compound that cures with actinic rays (hereinafter also referred to as an actinic ray curable composition) together with a gelling agent, a coloring material, and a photopolymerization initiator. It is characterized by.

  Hereinafter, the photopolymerizable compound used in the present invention will be described.

  Examples of the actinic rays in the present invention include electron beams, ultraviolet rays, α rays, γ rays, X rays, etc., but they are dangerous to human bodies and easy to handle, and their use is widespread industrially. UV light or electron beam is preferred. In the present invention, ultraviolet rays are particularly preferable.

  In the present invention, the photopolymerizable compound that is crosslinked or polymerized by irradiation with actinic rays can be used without particular limitation, but among them, a cationic polymerizable compound or a radical polymerizable compound is preferably used.

(Cationically polymerizable compound)
As the cationic polymerizable monomer, conventionally known various cationic polymerizable monomers can be used. Representative cationic polymerizable monomers include, for example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-2001. -310937 and JP-A 2001-220526 include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

  In the present invention, for the purpose of suppressing the shrinkage of the recording medium during ink curing, the photopolymerizable compound includes at least one oxetane compound and at least one compound selected from an epoxy compound and a vinyl ether compound. It is preferable to contain.

  First, the epoxy compound will be described.

  A preferable aromatic epoxide is a di- or polyglycidyl ether produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin, such as bisphenol A or an alkylene oxide thereof. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or alkylene oxide adducts thereof, and novolak type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxide, cyclohexene oxide or cyclopentene obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Oxide-containing compounds are preferred.

  Preferred aliphatic epoxides include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or Diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or its alkylene oxide adduct, polyethylene glycol or its alkylene oxide adduct Of polyalkylene glycols such as diglycidyl ether, polypropylene glycol or diglycidyl ether of its alkylene oxide adduct Glycidyl ether, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Among these epoxides, in view of fast curability, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

  Next, the vinyl ether compound will be described.

  Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -o- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

  Among these vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in appropriate combination.

  Next, the oxetane compound will be described.

  The oxetane compound referred to in the present invention is a compound having an oxetane ring, and any known oxetane compound as described in JP-A Nos. 2001-220526 and 2001-310937 can be used.

  In the oxetane compound that can be used in the present invention, when a compound having 5 or more oxetane rings is used, the viscosity of the ink composition increases, which makes it difficult to handle, and the glass transition temperature of the ink composition is high. Therefore, the tackiness of the cured product obtained may not be sufficient. The compound having an oxetane ring used in the present invention is preferably a compound having 1 to 4 oxetane rings.

  Examples of the compound having an oxetane ring that can be preferably used in the present invention include a compound represented by the general formula (1) described in paragraph No. (0089) of JP-A-2005-255821 and a paragraph of the same publication. Compound represented by general formula (2) described in number (0092), compound represented by general formula (7) described in paragraph number (0107), described in paragraph number (0109) A compound represented by the general formula (8), a compound represented by the general formula (9) described in paragraph (0166), and the like.

  Specific examples thereof include the exemplified compounds 1 to 6 described in paragraph numbers (0104) to (0119) and the respective compounds described in paragraph number (0121).

(Radically polymerizable compound)
Next, the radical polymerizable compound will be described.

  As the radical polymerizable compound, conventionally known various radical polymerizable monomers can be used. Representative radical polymerizable monomers include, for example, cationic polymerizable compounds described in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, and JP-A-10-863. Recently, photocationically polymerizable photocurable resins sensitized to a long wavelength region longer than visible light are disclosed in, for example, JP-A-6-43633 and JP-A-8- 324137 and the like.

  The radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and may be any compound as long as it has at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. , Oligomers, polymers and the like having a chemical form. Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties.

  Examples of compounds having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and their salts, esters, urethanes, amides. And radically polymerizable compounds such as various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides and unsaturated urethanes.

  Examples of the radically polymerizable compound applicable to the present invention include all known (meth) acrylate monomers and / or oligomers. The term “and / or” as used in the present invention means that it may be a monomer, an oligomer, or both. The same applies to the items described below.

  As the compound having a (meth) acrylate group, for example, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate 2-acryloyloxyethyl hexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2- Hydroxyethyl acrylic 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate Monofunctional monomers such as acid, lactone-modified flexible acrylate, t-butylcyclohexyl acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, Bifunctional monomers such as methylol-tricyclodecane diacrylate, PO adduct diacrylate of bisphenol A, neopentyl glycol diacrylate hydroxypivalate, polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, penta Trifunctional or more polyfunctional such as erythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxytriacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol ethoxytetraacrylate, caprolactam-modified dipentaerythritol hexaacrylate Monomer. In addition, polymerizable oligomers can be blended in the same manner as the monomer. Examples of the polymerizable oligomer include epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, polyester acrylate, and linear acrylic oligomer.

  More specifically, Yamashita Shinzo, “Cross-linking agent handbook” (1981 Taiseisha); Kato Kiyosumi, “UV / EB curing handbook (raw material)” (185, Polymer publication society); Study Group, “Application and Market of UV / EB Curing Technology”, page 79 (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products or radically polymerizable or crosslinkable monomer oligomers and polymers known in the industry can be used.

  Among the above monomers, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyristyl acrylate are particularly preferred from the viewpoints of sensitization, skin irritation, eye irritation, mutagenicity, toxicity, etc. , Isostearyl acrylate, ethoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, isobornyl acrylate, lactone-modified flexible acrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, dipentaerythritol Hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin Po carboxymethyl triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, caprolactam modified dipentaerythritol hexaacrylate preferred.

  Furthermore, among these, stearyl acrylate, lauryl acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, isobornyl acrylate, tetraethylene glycol diacrylate, glycerin propoxy triacrylate, cowprolactone-modified trimethylolpropane triacrylate, caprolactam-modified dipenta Erythritol hexaacrylate is particularly preferred.

  In the present invention, a vinyl ether monomer and / or oligomer and a (meth) acrylate monomer and / or oligomer may be used in combination as the polymerizable compound. Examples of the vinyl ether monomer include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n- B pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -o- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether. In the case of using a vinyl ether oligomer, a bifunctional vinyl ether compound having a molecular weight of 300 to 1000 and having 2 to 3 ester groups in the molecule is preferable. For example, a compound available as a VEctomer series of ALDRICH, VEctomer 4010, VEctomer 4020, Preferred examples include VEctomer 4040, VEctomer 4060, and VEctomer 5015, but are not limited thereto.

  In the present invention, various vinyl ether compounds and maleimide compounds can be used in combination as the polymerizable compound. Examples of maleimide compounds include N-methylmaleimide, N-propylmaleimide, N-hexylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N, N′-methylenebismaleimide, and polypropylene glycol-bis. (3-maleimidopropyl) ether, tetraethylene glycol-bis (3-maleimidopropyl) ether, bis (2-maleimidoethyl) carbonate, N, N ′-(4,4′-diphenylmethane) bismaleimide, N, N ′ -2,4-tolylene bismaleimide, or a polyfunctional maleimide compound which is an ester compound of maleimide carboxylic acid and various polyols disclosed in JP-A-11-124403. is not

  The addition amount of the cationically polymerizable compound and the radically polymerizable compound is 1.0 to 97% by mass, preferably 30 to 95% by mass with respect to the total mass of the ink.

<Each component of ink>
Next, components of the actinic ray curable ink according to the present invention excluding the above items will be described.

[Color material]
In the actinic ray curable ink according to the present invention, as a coloring material constituting the actinic ray curable ink, a dye or a pigment can be used without limitation, but has good dispersion stability with respect to the ink component, In addition, it is preferable to use a pigment having excellent weather resistance.

(Pigment)
Although it does not necessarily limit as a pigment, For example, the organic or inorganic pigment of the following number described in a color index can be used for this invention.

Examples of the red or magenta pigment include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, and 53. : 1, 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36,
Examples of the blue or cyan pigment include Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17-1, 22, 27, 28, 29, 36. , 60,
Examples of the green pigment include Pigment Green 7, 26, 36, 50,
Examples of the yellow pigment include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, and 137. 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193,
As the black pigment, for example, Pigment Black 7, 28, 26 can be used depending on the purpose.

  Specific product names include, for example, chromo fine yellow 2080, 5900, 5930, AF-1300, 2700L, chromo fine orange 3700L, 6730, chromo fine scarlet 6750, chromo fine magenta 6880, 6886, 6891N, 6790, 6887. , Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Black Fine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400 (B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040, C405 (F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B1476T-7, 1383LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C7 8, A612, cyanine blue 4933M, 4933GN-EP, 4940, 4973 (above, manufactured by Daiichi Seika Kogyo), KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301 , 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (Above, manufactured by Dainippon Ink & Chemicals), Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T 05, Pigment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, 45 105C, USN, Colortex Maroon 601, Colortex Brown B610N, Colortex Violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Colortex Green70, 403 ), Lionol Yellow 1405 , Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (above, manufactured by Toyo Ink), Toner Magenta E02, Permanent RubinF6B, Toner Yellow HG, Permanent Yellow GE-02 ), Novoperm P-HG, Hostaperm Pin E, Hostaperm Blue B2G (manufactured by Clariant), carbon black # 2600, # 2400, # 2350, # 2200, # 1000, # 990, # 980, # 970, # 960, # 950, # 850, MCF88, # 750, # 650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, # 52, # 50, # 47, # 45, # 45L, # 40, # 33, # 32, # 30, # 25, # 20, # 10, # 5, # 44, CF9 ( (Mitsubishi Chemical).

<Dispersion of pigment>
For the dispersion of the pigment, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like can be used.

<Pigment dispersant>
Also, a pigment dispersant can be added when dispersing the pigment. As the pigment dispersant, a polymer dispersant is preferably used. Examples of the polymer dispersant include Avecia's Solsperse series and Ajinomoto Fine-Techno's PB series. Furthermore, the following are mentioned.

  Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, a high molecular weight unsaturated acid ester, Polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl Examples thereof include phenyl ether, stearylamine acetate, and pigment derivatives.

  Specific examples include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-203 / 204 (high molecular weight polycarboxylate)” manufactured by BYK Chemie, “Disperbyk-101 (polyaminoamide phosphate). And acid ester), 107 (hydroxyl group-containing carboxylic acid ester), 110 (copolymer containing an acid group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170 (polymer copolymer) ”,“ 400 ”,“ Bykumen ”(high molecular weight unsaturated acid ester),“ BYK-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) ”,“ P104S, 240S (high molecular weight unsaturated acid polycarboxylic acid and Silicone) ”,“ Lactimon (long chain amine, unsaturated acid polycarboxylic acid and silicon Down) "and the like.

  Also, “Efka CHEMICALS” “Efka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766”, “Efka Polymer 100 (modified polyacrylate), 150 (aliphatic) System modified polymer), 400, 401, 402, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine system) "; Kyoei Chemical Co., Ltd." Floren TG-710 (urethane oligomer) "," “Flonon SH-290, SP-1000”, “Polyflow No. 50E, No. 300 (acrylic copolymer)”; “Disparon KS-860, 873SN, 874 (polymer dispersing agent), # 2150, manufactured by Enomoto Kasei Co., Ltd. (Aliphatic polyvalent carboxylic acid), # 7004 (polyether ester type) " It is.

  Furthermore, “Demol RN, N (Naphthalenesulfonic acid formalin condensate sodium salt), MS, C, SN-B (aromatic sulfonic acid formalin condensate sodium salt), EP”, “Homogenol L-18 (made by Kao Co., Ltd.) Polycarboxylic acid type polymer) "," Emulgen 920, 930, 931, 935, 950, 985 (polyoxyethylene nonylphenyl ether) "," acetamine 24 (coconut amine acetate), 86 (stearyl amine acetate) "; "Solspers 5000 (phthalocyanine ammonium salt type), 13240, 13940 (polyesteramine type), 17000 (fatty acid amine type), 24000, 32000" manufactured by Nikko Chemical Co., Ltd. "Nikkor T106 (polyoxyethylene sorbitan monooleate), MY" -IEX (polyoxyethylene monostearate), Hexagline4-0 (hexaglyceryl ruthenate Huwei rate) ", and the like.

  These pigment dispersants are preferably contained in the ink in the range of 0.1 to 20% by mass. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is used using a solvent or a polymerizable compound. However, the ink according to the present invention is preferably solvent-free because it is reacted and cured after printing. If the solvent remains in the cured image, the solvent resistance deteriorates and the VOC of the remaining solvent arises. Therefore, it is preferable in view of dispersibility that the dispersion medium is not a solvent but a polymerizable compound, and among them, a monomer having the lowest viscosity is selected.

  The pigment is preferably dispersed so that the average particle diameter of the pigment particles is 0.08 to 0.5 μm, and the maximum particle diameter is 0.3 to 10 μm, preferably 0.3 to 3 μm. The selection of the dispersion medium, the dispersion conditions, and the filtration conditions are appropriately set. By controlling the particle size, clogging of the nozzles of the recording head can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

(dye)
In the ink according to the present invention, a conventionally known dye, preferably an oil-soluble dye, can be used as necessary. Specific examples of oil-soluble dyes that can be used in the present invention are given below, but the present invention is not limited to these.

<Magenta dye>
The following specific examples can be given as magenta dyes.

  MS Magenta VP, MS Magenta HM-1450, MS Magenta HSo-147 (manufactured by Mitsui Toatsu Co., Ltd.), AIZENSOT Red-1, AIZEN SOT Red-2, AIZEN SOTRed-3, AIZEN SOT Pink-1, SPERON Red GE SPECIAL (above, manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, MACROLEX ROT5B (above, manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red Japan 802 ), PHLOXIN, ROSE BENGAL, ACID Red (above, manufactured by Daiwa Kasei), HSR-31, DIARE IN Red K (manufactured by Mitsubishi Kasei Co., Ltd.), (manufactured by BASF Japan Co., Ltd.) Oil Red.

<Cyan dye>
The following specific examples can be given as cyan dyes.

  MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, MS Cyan VPG (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, SIRIUS SUTRA TURQ. Blue FB-LL 330% (above, Bayer Japan), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, Light Blue BGL-5 200 (above, Nippon Kayaku Co., Ltd.), DAIWA Blue 7000, Oleosol Fast Blue GL (above, Daiwa Kasei), DIARESIN Blue P (Mitsubishi Kasei), SUDAN Blue 670, NEOPEN Blue 808, ZAPON Blue 806 (above, manufactured by BASF Japan).

<Yellow dye>
The following specific examples can be given as yellow dyes.

  MS Yellow HSm-41, Yellow KX-7, Yellow EX-27 (Mitsui Toatsu), AIZEN SOT Yellow-1, AIZEN SOT YellowW-3, AIZEN SOT Yellow-6 (above, manufactured by Hodogaya Chemical Co., Ltd.), MACROLEX Yellow 6G, MACROLEX FLUOR. Yellow 10GN (above, manufactured by Bayer Japan), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow AG, KAYASET Yellow EG (above, manufactured by Nippon Kayaku), DAIWA YELLOW 330H HSY-68 (manufactured by Mitsubishi Kasei Co., Ltd.), SUDAN Yellow 146, NEOPEN Yellow 075 (above, manufactured by BASF Japan).

<Black dye>
Specific examples of the black dye include the following.

  MS Black VPC (Mitsui Toatsu Co., Ltd.), AIZEN SOT Black-1, AIZEN SOT Black-5 (above, Hodogaya Chemical Co., Ltd.), RESORIN Black GSN 200%, RESOLIN Black BS (above, Bayer Japan Co., Ltd.), KAYASET Black A-N (manufactured by Nippon Kayaku Co., Ltd.), DAIWA Black MSC (manufactured by Daiwa Kasei Co., Ltd.), HSB-202 (manufactured by Mitsubishi Kasei Co., Ltd.), NEPTUNE Black X60, NEOPEN Black X58 (manufactured by BASF Japan) .

  The amount of the pigment or oil-soluble dye added is preferably 0.1 to 20% by mass, more preferably 0.4 to 10% by mass, based on the total mass of the ink. If it is 0.1% by mass or more, good image quality can be obtained, and if it is 20% by mass or less, an appropriate ink viscosity in ink ejection can be obtained. In addition, two or more kinds of colorants can be mixed as appropriate for color adjustment.

(Photopolymerization initiator)
The actinic ray curable ink according to the present invention contains at least one photopolymerization initiator. Photopolymerization initiators applicable to the present invention can be broadly classified into two types: intramolecular bond cleavage type and intramolecular hydrogen abstraction type.

  Examples of the intramolecular bond cleavage type photopolymerization initiator include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2. -Hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4 Acetophenones such as -thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone; benzoins such as benzoin, benzoin methyl ether, benzoin isopropyl ether; 2 , 4,6-Trimethylbenzoindiphenyl Scan fins oxides such acylphosphine oxide of benzil, methyl phenylglyoxylate esters.

  On the other hand, as an intramolecular hydrogen abstraction type photopolymerization initiator, for example, benzophenone, methyl 4-phenylbenzophenone, o-benzoylbenzoate, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl Benzophenones such as diphenyl sulfide, acrylated benzophenone, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone; 2-isopropylthioxanthone, 2 Thioxanthone series such as 1,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone; amino benzophenone series such as Michler-ketone, 4,4'-diethylaminobenzophenone; 10-butyl- - chloro acridone, 2-ethyl anthraquinone, 9,10-phenanthrenequinone, camphorquinone, and the like.

  The blending amount when using the photopolymerization initiator is preferably in the range of 0.01 to 10% by mass with respect to the total mass of the ink.

  Examples of radical polymerization initiators include triazine derivatives described in JP-B-59-1281, JP-B-61-9621, JP-A-60-60104, JP-A-59-1504, and JP-A-59-1504. Organic peroxides described in JP-A-61-243807, JP-B-43-23684, JP-B-44-6413, JP-B-44-6413, JP-B-47-1604, etc., and the United States Diazonium compounds described in Japanese Patent No. 3,567,453, organic azides described in US Pat. Nos. 2,848,328, 2,852,379 and 2,940,853 Compounds, ortho-quinonediazides described in JP-B 36-22062, JP-B 37-13109, JP-B 38-18015, JP-B 45-9610 and the like, Various onium compounds described in JP-A-55-39162, JP-A-59-14023, and the like, and “Macromolecules, Vol. 10, page 1307 (1977); No. 142205, JP-A-1-54440, European Patent No. 109,851, European Patent No. 126,712, etc., “Journal of Imaging Science” (J. Imag. Sci.), Vol. 30, page 174 (1986), (oxo) sulfonium organoboron complexes described in Japanese Patent Nos. 2711491 and 2803454, 61-151197, titanocenes, “Coordination Chemistry Levi (Coordination Chemistry Review), 84, 85-277 (1988) and JP-A-2-182701, transition metal complexes containing transition metals such as ruthenium, JP-A-3-209477 No. 2,4,5-triarylimidazole dimer, carbon tetrabromide, and organic halogen compounds described in JP-A-59-107344. These polymerization initiators are preferably contained in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the compound having an ethylenically unsaturated bond capable of radical polymerization.

  In the ink according to the present invention, a photoacid generator can also be used as a photopolymerization initiator.

  As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192). Examples of compounds suitable for the present invention are listed below.

First, diazonium, ammonium, iodonium, sulfonium, aromatic onium compounds such as phosphonium ^{_{B (C 6 F 5) 4}} -, PF 6 -, AsF 6 -, SbF 6 -, CF 3 SO 3 - and salts be able to.

  Specific examples of the onium compound that can be used in the present invention include compounds described in paragraph No. (0132) of JP-A No. 2005-255821.

  Specific examples of the sulfonated compound that generates sulfonic acid include compounds described in paragraph No. (0136) of JP-A-2005-255821.

  Thirdly, a halide that generates hydrogen halide can also be used, and specific examples thereof include the compounds described in paragraph No. (0138) of JP-A No. 2005-255821. it can.

  Fourthly, an iron allene complex described in paragraph No. (0140) of JP-A-2005-255821 can be mentioned.

[Other additives]
Various additives other than those described above can be used in the actinic ray curable ink according to the present invention. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, and waxes can be added. In addition, any known basic compound can be used for the purpose of improving storage stability. Typical examples include basic organic compounds such as basic alkali metal compounds, basic alkaline earth metal compounds, and amines. Etc.

"recoding media"
The recording medium that can be used in the ink jet recording method of the present invention using the actinic ray curable ink according to the present invention is not particularly limited as long as the recording medium has characteristics satisfying the condition 1 or the condition 2 according to the present invention. No, plain paper used in copying, paper base materials such as art paper, ordinary uncoated paper, coated paper with both sides of the base paper covered with resin, various pasting paper, synthetic paper, etc. In addition, various non-absorbable plastics used for so-called soft packaging and films thereof can be used. Examples of the various plastic films include polyethylene terephthalate (PET), expanded polystyrene (OPS), expanded polypropylene (OPP), Stretched nylon (ONy), polyvinyl chloride (PVC), polyethylene (PE), triacetyl cellulose (TAC) It can be mentioned Lum. As other plastics, polycarbonate (PP), acrylic resin, ABS resin, polyacetal, PVA, rubbers and the like can be used. Moreover, it is applicable also to metals and glass.

  In the inkjet recording method of the present invention, it is particularly preferable to use a slightly absorbent recording medium having a coating layer as the recording medium.

  The fine-absorbent recording medium having a coating layer in the present invention is specifically a coated paper for printing. Coated paper for printing is coated paper often used in printing. Generally, high-quality paper or medium-quality paper is used as the base paper, and after applying a pigment such as clay on the surface of the paper, smoothness is improved. Therefore, it is produced by applying a calendar process. Such processing improves whiteness, smoothness, print ink acceptability, halftone dot reproducibility, print gloss, print opacity, and the like. The paper is classified into art paper, coated paper, lightweight coated paper, etc., depending on the coating amount, and is classified into glossy, dull, matte, etc., depending on the gloss of the paper.

Art paper is a coated paper having a coating amount of about 20 g / m ^{2 on} one side, and is generally produced by applying a pigment to the paper surface and then applying a calendar treatment. There are special art, average art, matte (matte) art, single art (single side coating), double art (double side coating), and more specifically, OK Kanto N, Satin Kanto N, SA Kanou, Ultra Satin Kinto N, OK Ultra Aqua Satin, OK Kanto Single Side, N Art Post, NK Special Side Art, Thunderbird Super Art N, Thunderbird Super Art MN, Thunderbird Art N, Thunderbird Dull Art N, Hi McKinley Art, Hi McKinley Mat, High McKinley Pure Dull Art, Hi McKinley Super Dal, Hi McKinley Mat Elegance, Hi McKinley Deep Mat, etc.

The coated paper is a coated paper having a coating amount of about 10 g / m ^{2 on} one side, and is generally produced by processing with a coating apparatus provided in the middle of the paper machine. The coating amount is less than that of art paper, and the smoothness is slightly reduced, but the advantages are low cost and light weight. There is also a type of coated paper with a smaller coating amount, such as a light-weight coat and a finely coated paper. Specific examples of these coated papers include POD gloss coat, OK top coat +, OK top coat S, aurora coat, mu coat, mu white, thunderbird coat N, utrilo coat, pearl coat, white pearl coat, POD mat coat, New Age, New Age W, OK top coat mat N, OK royal coat, OK top coat dull, Z coat, Silver diamond, Ulite, Neptune, Mu mat, White mu mat, Thunderbird mat coat N, Utrilogros mat, New V mat, white new V mat, etc. are mentioned.

  In the ink jet recording method of the present invention, when an image is formed using an actinic ray curable ink containing a gelling agent, a recording medium satisfying the following condition 1 or 2 is used as a recording medium to be applied. It is characterized by that.

  That is, as condition 1, recording is performed in a temperature range of a gelation temperature Tgel-20 ° C. or higher and lower than Tgel-10 ° C. of an actinic ray curable inkjet ink using a recording medium having a 60 ° specular gloss of 69 or more and 100 or less. This is a method of forming an image by heating the medium. Condition 2 uses a recording medium having a 60-degree specular gloss of 10 or more and less than 69, and the gelation temperature Tgel of the actinic ray curable inkjet ink is 10 ° C. or more, In this method, the recording medium is heated to a temperature range of less than Tgel-5.0 ° C. to form an image. As the condition 2, more preferably, as the condition 2A, a recording medium having a 60 ° specular gloss of 55 or more and less than 69 is used, and the gelation temperature of the actinic radiation curable inkjet ink is Tgel-10 ° C. or more, Tgel-7. This is a method of forming an image by heating a recording medium to a temperature range of less than 5 ° C., and as condition 2B, a gel of actinic ray curable inkjet ink using a recording medium having a 60 ° specular gloss of 10 or more and less than 55 In this method, the recording medium is heated to a temperature range of Tgel-7.5 ° C. or higher and lower than Tgel-5.0 ° C. to form an image.

  Table 1 shows glossiness of typical recording media applicable to the present invention.

  In each recording medium described in Table 1, a recording medium with a glossiness classification of 1 is applied to Condition 1, a recording medium with a glossiness classification of 2A is applied to Condition 2 or Condition 2A, and the glossiness classification is 2B. This recording medium applies to Condition 2 or Condition 2B.

<Inkjet recording method>
Next, the ink jet recording method of the present invention will be described.

[Ink ejection conditions]
In the inkjet recording method of the present invention, the actinic radiation curable ink according to the present invention is heated in the inkjet recording head in a temperature range of the gelation temperature Tgel + 10 ° C. or more and less than the gelation temperature Tgel + 40 ° C. of the actinic radiation curable ink. One of the characteristics is to do. By setting the temperature of the ink in the recording head to the gelation temperature Tgel + 10 ° C. or higher, good ejection properties can be obtained without the ink gelling in the recording head or on the nozzle surface. Further, by setting the temperature of the ink in the recording head to less than the gelation temperature Tgel + 40 ° C., the load on the recording head can be reduced, and it is difficult to cause the performance of the recording head using a piezo element to deteriorate. In addition, it is preferable from the viewpoint of ejection stability that the ink jet recording head is kept warm and the ink viscosity is 3 mPa · s or more and less than 20 mPa · s.

[Temperature control of recording media]
In the ink jet recording method of the present invention, the surface temperature of the recording medium is adjusted to a temperature range defined by Condition 1 or Condition 2.

  As the temperature control means of the recording medium, for example, a method of adjusting the temperature of the recording medium from the back by attaching a cooling device and a heating device in advance to a conveyance base for fixing the recording medium or a fixing drum, cold air or hot air The temperature is controlled by spraying on the recording medium, the temperature is adjusted with a heating roller by attaching a refrigerant or heater to the upper surface of the recording medium fixing position on the device, or the temperature is adjusted without contact by irradiating an IR laser. And a method of adjusting the temperature of the recording medium in advance before ink jet recording, etc., but it is necessary to make the in-plane temperature difference uniform and to improve the robustness against temperature change. A method of adjusting the temperature from the back surface is preferable. As the temperature control method, for example, a method of attaching a Peltier element, a method of attaching a heater, a method of circulating refrigerant / cooling water, or the like is preferably used.

[Total ink film thickness after ink landing]
In the ink jet recording method of the present invention, the total ink film thickness after the ink has landed on the recording medium and cured by irradiation with actinic rays is preferably 2 to 25 μm. Here, “total ink film thickness” means the maximum value of the film thickness of the ink drawn on the recording medium, and even for a single color, other two colors are superimposed (secondary color), three colors are superimposed, four colors are used. Even when recording is performed by the overlapping (white ink base) inkjet recording method, the meaning of the total ink film thickness is the same.

[Ink ejection droplet volume]
Further, in the ink jet recording method of the present invention, the amount of ink droplets ejected from each nozzle of the recording head can be appropriately changed according to the recorded image, but in the case of forming a high-definition image, the range of 1 pl to 10 pl. It is preferable that

[Actinic ray irradiation conditions after image formation]
In the ink jet recording method of the present invention, the active light irradiation condition is preferably irradiation with active light within 10 seconds after the image is formed, more preferably 0.001 to 5 seconds, and further Preferably, it is 0.01 second to 2 seconds. Further, a method in which the irradiation of actinic rays is divided into two stages is preferable because shrinkage of the recording medium that occurs during ink curing can be suppressed.

  As a method of irradiating actinic rays, it is preferable to irradiate actinic rays after all images are drawn. That is, in the case of a line recording type ink jet recording apparatus, it is preferable to attach an actinic ray irradiation device 4 behind all the recording heads 2 as shown in FIG. In the case of a recording type inkjet recording apparatus, it is preferable to irradiate actinic rays after an image is completed in each pass as shown in FIG. When irradiating actinic rays before the image is completed, for example, in the case of a line recording method, a light source is placed between colors, or in the case of a serial recording method, the dots are thinned out and an actinic ray is drawn for each pass. In the case of irradiation, the ink droplets are repelled on the cured film, the image quality is disturbed, and the gloss uniformity is sometimes lowered.

[Electron beam irradiation]
Examples of the irradiation method in the case of using an electron beam as the actinic ray include a scanning method, a curtain beam method, and a broad beam method. The curtain beam method is preferable from the viewpoint of processing capability.

  The acceleration voltage of electron beam irradiation can be set to a range of 30 to 250 kV, and a cured film can be formed. However, it is preferable to set the acceleration voltage to 30 to 100 kV, which can obtain the same curability with a lower irradiation dose. . In addition, when the acceleration voltage of electron beam irradiation is set in the range of 30 to 100 kV, the irradiation dose of the electron beam is set to a value lower than normal, energy saving by high energy efficiency, and production efficiency by increasing printing speed. It is also possible to plan upward and downward. In normal electron beam irradiation with an acceleration voltage of 100 to 250 kV, the electron beam irradiation amount is preferably 30 to 100 kGy, more preferably 30 to 60 kGy.

  Examples of electron beam irradiation means that can be used in the present invention include “Curetron EBC-200-20-30” manufactured by Nissin High Voltage Co., Ltd., “Min-EB” manufactured by AIT Co., Ltd., and the like. Can be mentioned.

[UV irradiation]
When ultraviolet rays are used as the actinic rays, examples of the ultraviolet irradiation light source include fluorescent tubes (low pressure mercury lamps, germicidal lamps), cold cathode tubes, ultraviolet lasers, low pressures having medium operating pressures from several hundred Pa to 1 MPa, medium pressures, A high-pressure mercury lamp, a metal halide lamp, an LED, and the like can be mentioned. From the viewpoint of curability, a light source capable of emitting high-intensity UV light with an illuminance of 100 mW / cm ² or more such as a high-pressure mercury lamp, a metal halide lamp, and an LED is preferable. Among them, an LED with low power consumption is preferable, but not limited thereto.

[Inkjet recording device]
Next, an ink jet recording apparatus that can be used in the ink jet recording method of the present invention will be described using an ultraviolet irradiation apparatus as an example.

  Hereinafter, a recording apparatus that can be used in the present invention will be described with reference to the drawings as appropriate. Note that the recording apparatus shown in the drawings is merely an embodiment of the recording apparatus that can be preferably used in the present invention, and the present invention is not limited to this drawing.

  An image forming method of a single pass recording method in which the configuration of the present invention is more effective will be described.

  FIG. 3 shows an example of the configuration of the main part of the ink jet recording apparatus. FIG. 3A is a side view thereof, and FIG. 3B is a top view thereof.

  The ink jet recording apparatus shown in FIG. 3 is called a single-pass recording method, and a plurality of recording heads 1 for each color ink are fixedly arranged on the head carriage 2 so as to cover the entire width of the recording medium 3. The recording medium is transported under the fixed head carriage to form an image.

  The number of recording heads 2 used for each color with respect to the conveyance direction of the recording medium 3 varies depending on the nozzle density of the heads used and the printing resolution. For example, when it is desired to form an image having a resolution of 1440 dpi using a head having a droplet volume of 2 pl and a nozzle density of 360 dpi, the recording medium can be displaced by using four recording heads in the recording medium conveyance direction. A 1440 × 1440 dpi image can be formed. If you want to form an image with a resolution of 720 x 720 dpi using a head with a droplet volume of 6 pl and a nozzle density of 360 dpi, you can form a 720 dpi image by using two recording heads and shifting them. Become. In the present invention, dpi represents the number of dots per 2.54 cm.

  On the downstream side of the head carriage, an ultraviolet irradiation device 4 such as a metal halide lamp or an LED lamp is arranged so as to cover the entire width of the recording medium, and after the image is formed, the lamp is irradiated with ultraviolet rays and the image is completely fixed. Is done.

  In FIG. 3, for example, an LED lamp (385 nm manufactured by Hamamatsu Photonics) is used.

  Further, a temperature control device 5 is attached to the lower part of the recording medium, and the temperature of the recording medium can be appropriately adjusted to the temperature according to the present invention.

  In the present invention, it is preferable to form an image by ejecting small droplets having a droplet amount of 0.5 to 4.0 pl to form a high-definition image.

  Next, a serial recording type inkjet recording method will be described. FIG. 4 shows an example of the configuration of the main part of the ink jet recording apparatus.

  The ink jet recording apparatus shown in FIG. 4 is called a serial recording method, and a plurality of recording heads 1 of each color ink are fixedly arranged on the head carriage 2, and the head carriage moves to the left and right along the guide 6. The image is recorded while the recording medium 3 is sent in the transport direction for each pass to form the image.

  The number of passes when forming an image is not particularly limited. For example, it is possible to draw by thinning out dots by multipass such as 8 passes and 4 passes. However, when high-speed printing is assumed, a single pass is used. It is preferable to form an image.

  The number of recording heads used for each color varies depending on the nozzle density of the heads used, the printing resolution, and the number of passes during recording. For example, if you want to form an image with a resolution of 1440 dpi using a head with a droplet volume of 2 pl and a nozzle density of 360 dpi, use four recording heads in the recording medium transport direction when recording in a single pass. 1440 × 1440 dpi images can be formed by shifting the positions, and when forming an image with four or more passes, one recording head is used and the pixels are shifted for each pass. By doing so, an image can be formed.

  On the downstream side of the head carriage, an ultraviolet irradiation device 4 such as a metal halide lamp or an LED lamp is arranged so as to cover the entire width of the recording medium 3, and after the image is formed, the lamp is irradiated with ultraviolet rays and the image is completely emitted. To be established.

  In FIG. 4, for example, an LED lamp (385 nm manufactured by Hamamatsu Photonics) is used.

  Further, a temperature control device 5 is attached to the lower part of the recording medium 3 so that the temperature of the recording medium 3 can be appropriately adjusted to the temperature according to the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Preparation of pigment dispersion >>
The following additives were sequentially mixed and dispersed to prepare Pigment Dispersion Liquid 1 containing 21% by mass of a cyan pigment.

  Each of the following compounds was placed in a stainless beaker and dissolved by heating and stirring for 1 hour while heating on a hot plate at 65 ° C.

Pigment dispersant: Ajisper PB824 (manufactured by Ajinomoto Fine Techno) 9 parts Polymerizable compound: APG-200 (tripropylene glycol diacrylate, Shin-Nakamura Chemical Co., Ltd.) 70 parts Polymerization inhibitor: Irgastab UV10 (manufactured by BASF Japan) 0 .02 parts Next, after cooling the above solution to room temperature, 21 parts of the following cyan pigment 1 was added to the solution, sealed in a glass bottle with 200 g of zirconia beads having a diameter of 0.5 mm, and dispersed in a paint shaker for 8 hours. Then, the zirconia beads were removed to prepare Pigment Dispersion Liquid 1.

Cyan Pigment 1: Pigment Blue 15: 4 (manufactured by Dainichi Seika, Chromofine Blue 6332JC)
<Preparation of ink>
[Preparation of Ink 1]
The following additives were sequentially mixed, heated to 80 ° C. and stirred, and then the resulting solution was filtered with a # 3000 metal mesh filter under heating and cooled to prepare ink 1.

Polymerizable compound: SR344 (polyethylene glycol # 400 diacrylate, manufactured by SARTOMER) 34.8 parts Polymerizable compound: Photomer 4172 (5EO modified pentaerythritol tetraacrylate, manufactured by Cognis) 10.0 parts Polymerizable compound: SR454 (3EO modified) Trimethylolpropane triacrylate, manufactured by SARTOMER) 25.0 parts Polymerization inhibitor: Irgastab UV10 (manufactured by BASF Japan) 0.1 part Photopolymerization initiator: TPO (phosphine oxide, DAROCURE TPO, manufactured by BASF Japan) 3 0.0 parts Photopolymerization initiator: Irgacure 369 (α-aminoalkylphenone, manufactured by BASF Japan Ltd.) 3.0 parts Initiator assistant: ITX (isopropylthioxanthone, Speedcur e ITX, manufactured by Lambson) 2.0 parts Initiator auxiliary: EDB (Amine auxiliary, Speedcure EDB, manufactured by Lambson) 3.0 parts Surfactant: KF-352 (polyether modified silicone oil, Shin-Etsu Chemical) (Made by company)
0.05 part Pigment dispersion 1 19.0 parts [Preparation of ink 2]
The following additives were sequentially mixed, heated to 80 ° C. and stirred, and then the resulting solution was filtered with a # 3000 metal mesh filter under heating and cooled to prepare ink 2.

Polymerizable compound: SR344 (polyethylene glycol # 400 diacrylate, manufactured by SARTOMER) 31.8 parts Polymerizable compound: Photomer 4172 (5EO modified pentaerythritol tetraacrylate, manufactured by Cognis) 10.0 parts Polymerizable compound: SR454 (3EO modified) Trimethylolpropane triacrylate (manufactured by SARTOMER) 25.0 parts Polymerization inhibitor: Irgastab UV10 (manufactured by BASF Japan) 0.1 part Polymerization initiator: TPO (phosphine oxide, DAROCURE TPO, BASF Japan) 0 parts Polymerization initiator: Irgacure 369 (α-aminoalkylphenone, manufactured by BASF Japan) 3.0 parts Initiator assistant: ITX (isopropylthioxanthone, Speedcure) TX, manufactured by Lambson) 2.0 parts Initiator auxiliary: EDB (amine auxiliary, Speedcure EDB, manufactured by Lambson) 3.0 parts Surfactant: KF-352 (polyether-modified silicone oil, Shin-Etsu Chemical Co., Ltd.) Made)
0.05 parts Pigment dispersion 1 19.0 parts Gelling agent: 3.0 parts stearyl stearate [Preparation of inks 3 to 6]
Inks 3 to 6 were prepared in the same manner as in the preparation of Ink 2 except that the type and amount of gelling agent were changed as shown in Table 2. In addition, when the addition amount of the gelling agent was increased or decreased from 3.0 parts, the addition amount of SR344, which is a polymerizable compound, was appropriately adjusted so that the total amount was 100 parts.

  The details of each compound described by an abbreviation in Table 2 are as follows.

<Polymerizable compound>
SR344: Sartomer SR344, polyethylene glycol # 400 diacrylate, manufactured by SARTOMER P4172: Photomer 4172, 5EO modified pentaerythritol tetraacrylate, manufactured by Cognis SR454: Sartomer SR454, 3EO modified trimethylolpropane triacrylate, manufactured by SARTOMER <polymerization inhibitor>
UV10: Irgastab UV10, manufactured by BASF Japan Ltd. <Polymerization initiator>
TPO: Phosphine oxide, DAROCURE TPO, manufactured by BASF Japan Ltd. I369: Irgacure 369, α-aminoalkylphenone, manufactured by BASF Japan Ltd. <Initiator aid>
ITX: Isopropylthioxanthone, Speedcure ITX, manufactured by Lambson EDB: Amine assistant, Speedcure EDB, manufactured by Lambson <Surfactant>
KF-352: polyether-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd. <Gelling agent>
GEL1: Stearyl stearate (Exepal SS, manufactured by Kao Corporation)
GEL2: Cetyl palmitate (Amreps PC, manufactured by Higher Alcohol Industry)
GEL3: batyl stearate (Nikkor GM-18SV, manufactured by Nikko Chemicals)
GEL4: Stearon (Pentatriacontane-18-one, Kao Wax T1, manufactured by Kao Corporation)
GEL5: N stearyl stearic acid amide (Nikka Amide S, manufactured by Nippon Kasei Co., Ltd.)
[Measurement of ink properties]
Using the Physica MCR series (manufactured by Anton Paar), which is a stress-controlled rheometer using a cone plate, the ink gel temperature and ink viscosity (complex viscosity) at 30 ° C. for inks 1 to 6 prepared by the above method. Was measured.

  The gelation temperature (Tgel) was measured as the temperature at which the storage elastic modulus G ′ was 100 mPa or more when the temperature change of dynamic viscoelasticity was measured. The storage elastic modulus G ′ was measured under the conditions of a temperature rising / falling rate of 0.1 ° C./s, a strain of 5%, and an angular frequency of 10 radian / s.

  The viscosity of the ink at 30 ° C. was determined by measuring the temperature change of dynamic viscoelasticity at a measurement temperature of 30 ° C., a strain of 5%, and an angular frequency of 10 radian / s, and the obtained complex viscosity was taken as the viscosity of the ink. The obtained results are shown in Table 2.

G1-G2 shown in Table 2 uses coated paper (OK top coat, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 75) as the recording medium, and the temperature T1 of the recording medium. The 60 degree specular glossiness of an image formed at (gelation temperature Tgel-20 ° C. of the actinic radiation curable inkjet ink) is G1, and the temperature T2 of the recording medium (the gelation temperature Tgel− of the actinic radiation curable inkjet ink) When the 60 ° specular glossiness of an image formed at 5 ° C. is G2, the 60 ° specular gloss difference (G1−G2). The 60-degree specular gloss of the recording medium was measured using a variable angle gloss meter PG-1M (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the measurement method defined in JIS-Z-8741.

<< Inkjet image formation >>
Cyan monochromatic image evaluation was performed using the C head carriage of the single-pass recording type (line head type) inkjet recording apparatus provided with the piezo-type inkjet recording head shown in FIG. Inkjet recording heads are loaded with inks 1 to 6, respectively, and the following recording medium is used, and recording methods 1 to 1 are configured by combinations of the inks shown in Table 3, the type of recording medium, and the heating temperature of the recording medium. 14, a density gradation patch image was formed in an area of 2 cm × 2 cm, and the dot rate was changed to 0%, 10%, 20%, 30%, 50%, 70%, and 100%. The dot rate means the pixel density of output data.

(Type of recording medium used and 60 degree specular gloss)
Recording medium 1: Polyethylene terephthalate film (white pet, manufactured by Maru Adhesive Co., Ltd., 60 ° specular gloss: 91)
Recording medium 2: Cascote paper (mirror coat platinum, manufactured by Oji Paper Co., Ltd., basis weight 110 g / m ² , 60 ° specular gloss: 91)
Recording medium 3: Art paper (OK Kanto, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 78)
Recording medium 4: Coated paper (OK top coat, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 75)
Recording medium 5: finely coated paper (OK Evergreen, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 60)
Recording medium 6: finely coated paper (OK Marnos, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 45)
Recording medium 7: Coated paper (matte coated paper, OK top coat mat, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 27)
The 60-degree specular gloss of each recording medium was measured using a variable angle gloss meter PG-1M (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the measurement method defined in JIS-Z-8741.

(Inkjet printer conditions)
The ink supply system is composed of an ink tank, a supply pipe, a front chamber ink tank immediately before the recording head, a pipe with a filter, and a piezo head. The ink is insulated from the front chamber tank to the recording head portion so that each ink has a gel temperature Tgel + 30 ° C. Warmed up. Further, the piezo head was also provided with a heater, and the ink temperature in the recording head was heated to the gelation temperature Tgel + 30 ° C. of the ink. The piezo head has a nozzle diameter of 20 μm, the number of nozzles is 512 nozzles (256 nozzles × 2 rows, staggered arrangement, 1 row nozzle pitch 360 dpi), and the droplet speed is about 2.5 pl under each condition. The light was emitted at 6 m / sec and printed at a recording resolution of 1440 dpi × 1440 dpi. The recording speed was 400 mm / s. Each recording medium was adjusted to the temperatures shown in Tables 3 and 4 by adjusting the temperature of the temperature control device. After the image is formed, an LED lamp (385 nm manufactured by Hamamatsu Photonics, a distance of 2 mm between the recording medium and the lamp, a maximum output of 3800 mW / cm ² (UV integrated light meter manufactured by Hamamatsu Photonics: C9536- The ink was cured by irradiating with ultraviolet rays according to 02). The above image formation was performed in an environment of 23 ° C. and 55% RH. In the present invention, dpi represents the number of dots per 2.54 cm.

<< Evaluation of ink characteristics: Measurement of printing medium temperature and gloss of formed image >>
For each of the inks prepared above, as shown in FIG. 2, coated paper (OK top coat, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 75) was used. A cyan solid image having a thickness of 10 μm was formed from the ink jet printer used for forming the ink jet image while changing the surface temperature of the coated paper in the range of −35 to −5 ° C. with respect to Tgel of each ink.

  Next, the 60-degree specular gloss of the formed cyan solid image was measured using a variable angle gloss meter PG-1M (manufactured by Nippon Denshoku Industries Co., Ltd.). Each graph plotting the surface temperature was created.

  As representative inks in FIG. 5, ink 2 using stearyl stearate as a gelling agent (Tgel = 53 ° C.), ink 3 using cetyl palmitate as a gelling agent (Tgel = 48 ° C.), gelling agent The surface temperature characteristic value of the gloss VS recording medium of ink 4 (Tgel = 48 ° C.) using batyl stearate is shown. The ink 1 containing no gelling agent had a gloss of 84 to 88, regardless of the recording medium temperature. Ink 5 using stearone as a gelling agent (Tgel = 72 ° C.) showed the same profile as ink 2. That is, the ink 2 profile was shifted to the high temperature side by 19 ° C., which is the difference in Tgel. In addition, with ink 6 (Tgel = 92 ° C.) using N stearyl stearate amide as a gelling agent, the glossiness of the formed magenta solid image was in the range of 26 to 28.

As the recording medium, instead of the recording medium 4: coated paper (OK top coat, manufactured by Oji Paper Co., Ltd., basis weight 105 g / m ² , 60 ° specular gloss: 75), the above recording media 1 to 3, 5 to 5 are used. As a result of the same measurement using No. 7, an image having the same glossiness as described above was obtained.

<Evaluation of formed image>
(Evaluation of gloss uniformity)
For the density gradation patch image in which the dot rate is changed to 20%, 50%, 70%, and 100% in the formed 2 cm × 2 cm area by the above method, the formed image portion and the unprinted portion (white background portion) of the recording medium ) And the gloss difference were visually observed, and gloss uniformity was evaluated according to the following criteria.

A: Gloss difference between the density gradation patch image and the unprinted portion of the recording medium is not recognized at all in the dot ratio images. O: The density gradation patch image and the recording medium are all in the dot ratio images. The difference in glossiness from the unprinted area is almost unnoticeable. Δ: In some images of the dot rate, a slight difference in glossiness between the density gradation patch image and the unprinted area of the recording medium is recognized, but practically acceptable. ×: The image of all dot ratios is an image with a sense of incongruity when a difference in gloss between the density gradation patch image and the unprinted portion of the recording medium is recognized. XX: All dot ratios Table 3 shows the evaluation results obtained as described above, in which a strong gloss difference is recognized between the density gradation patch image and the unprinted portion of the recording medium.

  As is apparent from the results in Table 3, various recording media having different gloss from the comparative examples are obtained by forming an image by the ink jet recording method defined in the present invention using the actinic ray curable ink according to the present invention. It can be seen that an image with uniform gloss can be obtained on all recording media even when using.

Example 2
In the first embodiment, the heating temperature of each ink from the front chamber tank to the recording head portion and the piezo head is set to a temperature corresponding to the gelation temperature Tgel of each ink, Tgel + 5 ° C., Tgel + 10 ° C., Tgel + 20 ° C., Tgel + 35 ° C. As a result of evaluating the method described in Example 1 under the conditions of Tgel + 39 ° C., Tgel + 42 ° C., and Tgel + 50 ° C., the ink heating temperature was Tgel + 10 ° C., Tgel + 20 ° C., Tgel + 35 ° C., and Tgel + 39 ° C. Glossiness and excellent emission stability could be obtained.

DESCRIPTION OF SYMBOLS 1 Recording head 2 Head carriage 3 Recording medium 4 Ultraviolet irradiation apparatus 5 Temperature control apparatus

Claims (9)

Inkjet recording for forming an image on a recording medium using an actinic ray curable inkjet ink containing 1.0 to 10% by mass of a coloring material, a photopolymerizable compound and a photopolymerization initiator, and a gelling agent In the method, the actinic ray curable inkjet ink has a viscosity at 30 ° C. of 10 ² mPa · s or more and 10 ⁵ mPa · s or less, a gelation temperature Tgel of 40 ° C. or more and 80 ° C. or less, and a recording medium An image formed at a temperature T1 (gelation temperature Tgel-20 ° C. of the actinic radiation curable ink-jet ink) is G1 with a 60-degree specular gloss, and a temperature T2 of the recording medium (gelation temperature of the actinic radiation curable ink-jet ink). When the 60 ° specular glossiness of an image formed at Tgel-5 ° C. is G2, the 60 ° specular gloss difference (G1−G2) is 35 or more, and An inkjet recording method comprising heating an actinic ray curable inkjet ink to a gelling temperature Tgel + 10 ° C. or higher and a gelling temperature Tgel + 40 ° C. to form an image under the following condition 1 or condition 2.
Condition 1: A recording medium having a 60 ° specular gloss of 69 or more and 100 or less is used. The surface temperature Ts of the recording medium is set to a gelling temperature Tgel-30 ° C. or higher of the actinic radiation curable inkjet ink, and the gelation temperature Tgel is set. The image is formed by controlling the temperature below -10 ° C.
Condition 2: Using a recording medium having a 60 ° specular gloss of 10 or more and less than 69, the surface temperature Ts of the recording medium is set to a gelling temperature Tgel of 10 ° C. or higher of the actinic radiation curable inkjet ink, and a gelation temperature Tgel. An image is formed by controlling the temperature range below -5.0 ° C. 2. The ink jet recording method according to claim 1, wherein the condition 2 is the following condition 2A and condition 2B, and an image is formed under the condition 1, the condition 2A or the condition 2B.
Condition 2A: A recording medium having a 60 ° specular gloss of 55 or more and less than 69, the surface temperature Ts of the recording medium is set to a gelling temperature Tgel of 10 ° C. or more of the actinic radiation curable inkjet ink, and a gelation temperature Tgel. An image is formed by controlling the temperature range below -7.5 ° C.
Condition 2B: Using a recording medium having a 60 ° specular gloss of 10 or more and less than 55, the surface temperature Ts of the recording medium is a gelation temperature Tgel of 7.5 ° C. or more of the actinic ray curable inkjet ink. The image is formed by controlling the temperature within a temperature range of less than Tgel-5.0 ° C. The ink jet recording method according to claim 1 or 2 wherein the gelling agent, characterized in that a fatty acid ester or an aliphatic ketone. The ink-jet recording according to any one of claims 1 to 3 , wherein the gelling agent is stearyl stearate, batyl stearate, cetyl palmitate or pentatriacontan-18-one (stearon). Method. The ink-jet recording method according to any one of claims 1 to 4 , wherein the gelation temperature Tgel of the actinic ray curable ink-jet ink is 45 ° C or higher and 65 ° C or lower. The inkjet according to any one of claims 1 to 5 , wherein a content of the gelling agent in the actinic ray curable inkjet ink is 2.0 mass% or more and 7.0 mass% or less. Recording method. The inkjet recording method according to any one of claims 1 to 6 , wherein the actinic ray curable inkjet ink is emitted with a viscosity in the inkjet recording head of 3 mPa · s or more and less than 20 mPa · s. The recording medium, ink jet recording method according to any one of claims 1 to 7, characterized in that the fine absorbent recording medium having a coating layer. The ink-jet recording method according to any one of claims 1 8, characterized in that an image printed in a single pass method.