JP2011083977A - Printer and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the density of ink colors according to a change in environment (temperature and humidity) in printing using ink containing hollow resin. <P>SOLUTION: A printer includes an environment value acquiring section for acquiring at least one of temperature and humidity; a jet amount determining section for determining the jet amount of a moisture retaining liquid which is a liquid containing a humectant whose octanol/water partition coefficient is -1.0 or less according to the acquired temperature or humidity at least; and a jetting mechanism for jetting the moisture retaining liquid of the determined jet amount and ink containing hollow resin particles. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to concentration control of ink containing hollow resin particles as a color material.

  2. Description of the Related Art Conventionally, printing apparatuses that perform printing using white ink in addition to color inks such as cyan, magenta, and yellow are known (Patent Document 1). As a white ink, an ink containing hollow resin particles as a color material is known (Patent Document 2).

JP 2002-38063 A U.S. Pat. No. 4,880,465

  In printing using white ink containing hollow resin particles as a color material, there has been a demand for adjusting whiteness (white density) according to changes in the environment (temperature and humidity). For example, even if there is a request to adjust the white on the recording medium to change according to the change in the environment after printing, or even when the environment at the time of printing changes, the white on the recording medium is the same. There was a request to make adjustments. Such a problem is not limited to white ink but is common to inks containing hollow resin particles as a color material.

  An object of the present invention is to adjust the density of an ink color according to changes in the environment (temperature and humidity) in printing using ink containing a hollow resin.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 In a printing apparatus, an environmental value acquisition unit that acquires at least one of temperature and humidity, and an octanol / water partition coefficient of −1.0 according to at least one of the acquired temperature and humidity. An ejection amount determination unit that determines an ejection amount of a moisturizing liquid that is a liquid containing a moisturizing agent, an ejection mechanism that ejects the moisturizing liquid of the determined ejection amount, and ink including hollow resin particles; A printing apparatus.

  Since the printing apparatus of Application Example 1 ejects a moisturizing liquid having an ejection amount determined according to at least one of temperature and humidity acquired by the environmental value acquisition unit and ink containing hollow resin particles, the environment (temperature In addition, the density of the ink color can be adjusted in accordance with the change in the humidity. A humectant having an octanol / water partition coefficient of −1.0 or less has a high affinity with water. Therefore, the amount of moisture permeated into the inside (cavity) of the hollow resin particles can be adjusted by the injection amount of the moisturizing liquid. As a result, the density (for example, whiteness) of the ink color can be adjusted.

  Application Example 2 In the printing apparatus according to Application Example 1, the ejection amount determination unit increases the ejection amount of the moisturizing liquid as the acquired temperature is higher.

  With such a configuration, generally, the higher the temperature, the easier the water contained in the ejected ink and moisturizing liquid tends to evaporate and the ink density tends to increase (transparency decreases), but the moisturizing liquid ejection amount is increased. As a result, the amount of water retained around the ink can be increased, so that an increase in ink density (decrease in transparency) can be suppressed.

  Application Example 3 The printing apparatus according to Application Example 1 or Application Example 2, wherein the ejection amount determination unit reduces the ejection amount of the moisturizing liquid as the acquired humidity is higher.

  With such a configuration, in general, the moisture contained in the ejected ink and moisturizing liquid is less likely to evaporate as the humidity is higher, and the ink concentration tends to decrease (transparency increases), but the amount of moisturizing liquid ejected is reduced. As a result, the amount of water retained around the ink can be reduced, so that a decrease in ink density (an increase in transparency) can be suppressed.

  [Application Example 4] A printing method, in which (a) at least one of temperature and humidity is obtained, and (b) at least one of temperature and humidity obtained in the step (a), octanol / A step of determining an injection amount of a moisturizing liquid which is a liquid containing a moisturizing agent having a water distribution coefficient of −1.0 or less, (c) a moisturizing liquid having an injection amount determined in the step (b), and a hollow resin And a step of ejecting ink containing particles.

  Since the printing method of the application example 4 acquires the temperature and the humidity, and ejects the moisturizing liquid of the ejection amount determined according to at least one of the temperature and the humidity and the ink including the hollow resin particles, the environment (temperature In addition, the density of the ink color can be adjusted in accordance with the change in the humidity. A humectant having an octanol / water partition coefficient of −1.0 or less has a high affinity with water. Therefore, the amount of moisture permeated into the inside (cavity) of the hollow resin particles can be adjusted by the injection amount of the moisturizing liquid. As a result, the density (for example, whiteness) of the ink color can be adjusted.

It is explanatory drawing which shows schematic structure of the printing apparatus as one Embodiment of this invention. 3 is an explanatory diagram schematically illustrating a nozzle formation surface of a print head 31. FIG. It is explanatory drawing which shows typically the cross section of the printing medium at the time of performing surface printing. It is explanatory drawing which shows typically the cross section of the printing medium at the time of performing back printing. It is explanatory drawing which shows the printing apparatus of the 3rd Example. It is explanatory drawing which shows an example of the setting content of the discharge amount table 41 shown in FIG.

Hereinafter, embodiments and examples of the present invention will be described in the following order.
A. Embodiment:
A1. White ink:
A2. Moisturizer:
A3. Printing device:
B. Example:
B1. First embodiment:
B2. Second embodiment:
B3. Third embodiment:
C. Variation:

A. Embodiment:
A1. White ink:
A1-1. Hollow resin particles:
The white ink used in this embodiment contains hollow resin particles. The hollow resin particles preferably have a cavity inside and the outer shell is preferably formed of a resin having liquid permeability. With such a configuration, when hollow resin particles are present in the aqueous ink composition, the internal cavity is filled with the aqueous medium. Since the particles filled with the aqueous medium have a specific gravity almost equal to that of the external aqueous medium, the dispersion stability can be maintained without settling in the aqueous ink composition. Thereby, the storage stability and ejection stability of the white ink can be enhanced.

  In the following description, the hollow resin particles are described as being used as a white color material, but the hollow resin particles in the present invention can also be used as a color material other than white. For example, the hollow resin particles can be used as a coloring material of a colored color by coloring the resin constituting the hollow resin particles to a color other than white.

  When the white ink of this embodiment is ejected onto recording paper or other recording media, the aqueous medium inside the particles is removed by drying, and the inside of the hollow resin particles becomes hollow. When air enters the internal cavities of the particles, a resin layer and an air layer having different refractive indexes are formed in the particles, so that incident light on the particles is scattered and the aqueous ink composition exhibits a white color. .

  Known hollow resin particles can be employed as such hollow resin particles. For example, hollow resin particles described in specifications such as US Pat. No. 4,880,465 and Japanese Patent No. 3,562,754 can be employed.

  The average particle diameter (outer diameter) of the hollow resin particles is preferably 0.2 μm or more and 1.0 μm or less, and more preferably 0.4 μm or more and 0.8 μm or less. As a rule of thumb, if the outer diameter exceeds 1.0 μm, the particles may settle and the dispersion stability may be impaired, and the reliability such as clogging of the ink jet recording head may be impaired. On the other hand, when the outer diameter is less than 0.2 μm, the whiteness tends to be insufficient. The inner diameter is suitably 0.1 μm or more and 0.8 μm or less.

  The average particle diameter (outer diameter) of the hollow resin particles can be measured using a field emission transmission electron microscope (FE-TEM) or a field emission scanning electron microscope (FE-SEM). As the field emission type transmission electron microscope, for example, “TecnaiG2F30” manufactured by FEI can be used. As the field emission scanning electron microscope, for example, “S-4700” manufactured by Hitachi, Ltd. can be used.

  The content of the hollow resin particles is preferably 5% by weight or more and 20% by weight or less, more preferably 8% by weight or more and 15% by weight or less with respect to the total mass of the white ink. is there. When the content (solid content) of the hollow resin particles exceeds 20% by weight, reliability such as clogging of the ink jet recording head may be impaired. On the other hand, if it is less than 5% by weight, the whiteness tends to be insufficient.

  As a method for preparing the hollow resin particles, a known method can be applied. For example, a so-called emulsion polymerization method in which a hollow resin particle emulsion is formed by stirring a vinyl monomer, a surfactant, a polymerization initiator, and an aqueous dispersion medium while heating in a nitrogen atmosphere can be applied.

  Examples of vinyl monomers include nonionic monoethylenically unsaturated monomers such as styrene, vinyl toluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide, (meth) acrylic acid esters, and the like. Can be mentioned. Examples of (meth) acrylic acid esters include methyl acrylate, methyl methacrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl methacrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, and lauryl (meth) ) Acrylate, oleyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like.

  Moreover, a bifunctional vinyl monomer can also be used as a vinyl monomer. Examples of the bifunctional vinyl monomer include divinylbenzene, acrylic methacrylate, ethylene glycol dimethacrylate, 1,3-butane-diol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and the like. By hollowly copolymerizing the above monofunctional vinyl monomer and the above bifunctional vinyl monomer and highly crosslinked, not only light scattering properties but also hollow properties with heat resistance, solvent resistance, solvent dispersibility, etc. Resin particles can be obtained.

  The surfactant is not particularly limited as long as it forms a molecular aggregate such as micelles in water, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Can be mentioned.

  As the polymerization initiator, a known compound soluble in water can be used, and examples thereof include hydrogen peroxide and potassium persulfate.

  Examples of the aqueous dispersion medium include water and water containing a hydrophilic organic solvent.

A1-2. Permeable organic solvent:
The white ink used in the present embodiment preferably contains at least one selected from alkanediols and glycol ethers. Alkanediols and glycol ethers can enhance the wettability of a recording surface such as a recording medium and improve the ink permeability.

  Examples of the alkanediol include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 2-Alkanediol is preferred. Of these, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol having 6 to 8 carbon atoms are more preferred because of their particularly high permeability to recording media.

  The glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol. Mention may be made of lower alkyl ethers of polyhydric alcohols such as monomethyl ether, triethylene glycol monobutyl ether and tripropylene glycol monomethyl ether. Among these, when triethylene glycol monobutyl ether is used, good recording quality can be obtained.

  The content of at least one selected from these alkanediols and glycol ethers is preferably 1% by weight or more and 20% by weight or less, more preferably 1% by weight, based on the total mass of the white ink. % To 10% by weight.

A1-3. Surfactant:
The white ink used in this embodiment preferably contains an acetylene glycol surfactant or a polysiloxane surfactant. Acetylene glycol surfactants or polysiloxane surfactants can increase the wettability of a recording surface such as a recording medium to increase the ink permeability.

  Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3, 5-dimethyl-1-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol and the like can be mentioned. Moreover, a commercial item can also be utilized for acetylene glycol type-surfactant, for example, Orphine E1010, STG, Y (above, Nissin Chemical Co., Ltd.), Surfinol 104, 82, 465, 485, TG (above , Air Products and Chemicals Inc.).

  Commercially available products can be used as the polysiloxane surfactant, and examples thereof include BYK-347, BYK-348 (manufactured by BYK Japan).

  Furthermore, the white ink according to the present embodiment can also contain other surfactants such as an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.

  The content of the surfactant is preferably 0.01% by weight or more and 5% by weight or less, more preferably 0.1% by weight or more and 0.5% by weight with respect to the total weight of the white ink. % By weight or less.

A1-4. Polyhydric alcohol:
The white color used in this embodiment preferably contains a polyhydric alcohol. The polyhydric alcohol can suppress ink drying and prevent ink clogging in the ink jet recording head portion.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, and trimethylolethane. And trimethylolpropane.

  The content of the polyhydric alcohol is preferably 0.1 to 3.0% by weight, more preferably 0.5 to 20% by weight, based on the total weight of the ink composition.

A1-5. Tertiary amine:
The white ink used in this embodiment preferably contains a tertiary amine. The tertiary amine has a function as a pH adjuster and can easily adjust the pH of the white ink. Examples of the tertiary amine include triethanolamine. The content of the tertiary amine is preferably 0.01% by weight or more and 10% by weight or less, more preferably 0.1% by weight or more and 2% by weight with respect to the total weight of the white ink. % Or less.

A1-6. Other ingredients:
The white ink used in this embodiment desirably includes a resin that fixes the color material. Examples of such resins include acrylic resins (for example, Almatex (manufactured by Mitsui Chemicals)) and urethane resins (for example, WBR-022U (manufactured by Taisei Fine Chemical Co., Ltd.)).

  Further, the white ink used in the present embodiment usually contains water as a solvent. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltered water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be suppressed over a long period of time.

  The white ink used in the present embodiment includes a fixing agent such as a water-soluble rosin, an antifungal agent / preservative such as sodium benzoate, an antioxidant / ultraviolet absorber such as an allophanate, a chelating agent, if necessary. Additives such as oxygen absorbers can be included. These additives can be used alone or in combination of two or more.

  The white ink used in the present embodiment can be prepared in the same manner as the conventional pigment ink using a conventionally known apparatus such as a ball mill, a sand mill, an attritor, a basket mill, a roll mill, or the like. In the preparation, it is preferable to remove coarse particles using a membrane filter or a mesh filter.

A2. Moisturizer:
The moisturizing liquid used in the present embodiment is a liquid containing a moisturizing agent for attracting and holding the liquid composition that can penetrate into the hollow of the hollow resin particles around the hollow resin particles on the recording medium after printing. It is. Therefore, the moisturizing liquid of this embodiment is a colorless and transparent or colorless and translucent liquid.

A2-1. Moisturizer:
As the humectant used in the present embodiment, polyhydric alcohol compounds, saccharides, sugar alcohols, hyaluronic acids, and solid wetting agents are preferably used.

  Examples of the polyhydric alcohol compound include glycerin, ethylene glycol, triethylene glycol, propylene glycol, diethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3- Examples include hexanediol, 2-methyl-2,4-pentanediol, dipropylene glycol, tetraethylene glycol, and polyethylene glycol.

  Examples of the saccharide include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, sorbitol, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like.

  Examples of the fixing wetting agent include trimethylolethane, trimethylolpropane, urea, urea derivatives (dimethylurea and the like), and the like.

  Of the humectants described above, some polyhydric alcohol compounds such as glycerin, ethylene glycol, triethylene glycol, and propylene glycol are also used as water-soluble solvents.

A2-2. Surfactant:
The moisturizing liquid used in this embodiment preferably contains an acetylene glycol surfactant or a polysiloxane surfactant. The acetylene glycol surfactant or polysiloxane surfactant can increase the wettability of the moisturizing liquid by increasing the wettability to the recording surface such as a recording medium.

  Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3, 5-dimethyl-1-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol and the like can be mentioned. Moreover, a commercial item can also be utilized for acetylene glycol type-surfactant, for example, Orphine E1010, STG, Y (above, Nissin Chemical Co., Ltd.), Surfinol 104, 82, 465, 485, TG (above , Air Products and Chemicals Inc.).

  Commercially available products can be used as the polysiloxane surfactant, and examples thereof include BYK-347, BYK-348 (manufactured by BYK Japan).

A2-3. Tertiary amine:
The moisturizing liquid used in this embodiment preferably contains a tertiary amine. The tertiary amine has a function as a pH adjusting agent, and can easily adjust the pH of the humectant.

  Examples of the tertiary amine include triethanolamine.

A2-4. Other ingredients:
It is desirable that the moisturizing liquid used in the present embodiment includes a resin that fixes the moisturizing agent. Examples of such resins include acrylic resins (for example, Almatex (manufactured by Mitsui Chemicals)) and urethane resins (for example, WBR-022U (manufactured by Taisei Fine Chemical Co., Ltd.)).

  Moreover, the moisturizing liquid used in the present embodiment usually contains water as a solvent. This water is also used to permeate the cavities of the hollow resin particles. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltered water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be suppressed over a long period of time.

A3. Printing device:
The printing apparatus used in the present embodiment employs an ink jet recording method in which image recording is performed on a recording medium such as paper by ejecting ink containing a hollow resin particle and a moisturizing liquid. As the ink jet recording method, a known method can be employed. For example, a thermal jet ink jet recording method, a piezoelectric ink jet recording method, or the like can be employed.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a printing apparatus according to an embodiment of the present invention. The printing apparatus 10 is an ink jet printer, and includes a paper feed motor 22, a platen 25, a drive belt 23, a pulley 26, a carriage motor 21, a sliding shaft 24, a carriage 30, and a main control unit 40. And an operation unit 50 and a connector 60.

  The paper feed motor 22 rotates the platen 25 and transports the recording paper P in the sub-scanning direction. The drive belt 23 is a so-called endless belt, and is stretched between the carriage motor 21 and the pulley 26. The carriage motor 21 drives the drive belt 23. The slide shaft 24 slidably holds the carriage 30 fixed to the drive belt 23.

  The carriage 30 includes a print head 31 and detachably mounts eight ink cartridges 32 to 39. The first ink cartridge 32 is an ink cartridge for yellow ink (Y). The second ink cartridge 33 is for magenta ink (M), the third ink cartridge 34 is for cyan ink (C), the fourth ink cartridge 35 is for black ink (K), and the fifth ink cartridge 36 is For the white ink (W), the sixth ink cartridge 37 is for red ink (R), the seventh ink cartridge 38 is for blue ink (B), and the eighth ink cartridge 39 is for moisturizing liquid (H). Each is an ink cartridge.

  FIG. 2 is an explanatory diagram schematically showing the nozzle formation surface of the print head 31. The print head 31 includes a nozzle formation surface Sn at a position facing the recording paper P. On the nozzle forming surface Sn, a nozzle row composed of a plurality of nozzles corresponding to each color is formed. Specifically, the nozzle row 32n corresponding to yellow ink, the nozzle row 33n corresponding to magenta ink, the nozzle row 34n corresponding to cyan ink, the nozzle row 35n corresponding to black ink, and the white ink. A nozzle row 36n, a nozzle row 37n corresponding to red ink, a nozzle row 38n corresponding to blue ink, and a nozzle row 39n corresponding to moisturizing liquid are formed. The print head 31 ejects ink supplied from the ink cartridges 32 to 39 toward the recording paper P from the corresponding nozzle rows 32n to 39n. When the driving belt 23 is driven by the carriage motor 21, the carriage 30 reciprocates in the axial direction (main scanning direction) of the platen 25 along the sliding shaft 24.

  The operation unit 50 includes operation buttons used when the user performs various settings, and a display for displaying various menu screens. The connector 60 is used for connecting the printing apparatus 10 and the personal computer 90.

  The main control unit 40 adjusts the amount of ink ejected from the print head 31 according to the print job received from the personal computer 90. For example, in the case of a piezo ink jet recording system, the ink amount can be adjusted by adjusting a drive signal supplied to a piezo element corresponding to each nozzle.

  The print head 31 and the two nozzle rows 36n and 39n correspond to the ejection mechanism in the claims.

B. Example:
B1. First embodiment:
The first embodiment exemplifies a change in whiteness (white density) caused by ejecting a moisturizing liquid in addition to white ink.

B1-1. White ink:
In the first example, white ink was produced with the blending amounts shown in Table 1. In addition, the unit of the numerical value described in Table 1 is weight%. As the hollow resin particles shown in Table 1, “SX8782 (D)” manufactured by JSR Corporation was used. In Table 1, “BYK-348” is a polysiloxane surfactant manufactured by Big Chemie Japan.

B1-2. Moisturizer:
In the first example, moisturizing liquids 1 to 5 were generated with the blending amounts shown in Table 2. The unit of numerical values described in Table 2 is% by weight.

  In Table 2 above, glycerin, tetraethylene glycol, polyethylene glycol, trimethylolpropane, and hexylene glycol all correspond to humectants. Each of the moisturizing liquids 1 to 5 is different from each other in the kind of the moisturizing agent contained, and the other compositions are the same. The aforementioned five humectants have different affinity for water. Table 3 shows octanol / water partition coefficients of glycerin, tetraethylene glycol, polyethylene glycol, trimethylolpropane, and hexylene glycol. The octanol / water partition coefficient is a coefficient generally used as an index of the affinity of a compound with water. The larger the value, the lower the affinity with water, and the smaller the value, the higher the affinity with water.

B1-3. Printing device:
In the first embodiment, the white ink is filled in the ink cartridge for the photo black ink of the ink jet printer “PX-G930” manufactured by Seiko Epson Corporation, and the moisturizing liquid is filled in the ink cartridge for the gloss optimizer. A printing test was conducted. In the printing test, the test was performed on two transparent patterns, which will be described later, with two patterns having different ejection orders of the white ink and the moisturizing liquid. Specifically, the test was performed with a pattern ejected in the order of moisturizing liquid and white ink (front printing) and a pattern ejected in the order of white ink and moisturizing liquid (back printing). In addition, although commercially available ink cartridges are mounted as the other color ink cartridges of the printer, these ink cartridges are used as dummy and are not involved in the evaluation of this embodiment.

  FIG. 3 is an explanatory diagram schematically showing a cross section of a print medium when front printing is performed. By front printing, the moisturizing liquid layer HL is formed on the transparent recording medium M1, and further, the white ink layer WL is formed on the moisturizing liquid layer HL. The front printing is a printing that assumes that the observer observes from the color ink side by ejecting further color ink on the white ink and forming a color ink layer CL indicated by a broken line in FIG. However, in the front printing of the present embodiment, the color ink is not ejected, and only the whiteness is evaluated.

  FIG. 4 is an explanatory diagram schematically showing a cross section of a print medium when back printing is performed. In the back printing in the printing test, the white ink layer WL is formed on the recording medium M1, and the moisturizing liquid layer HL is further formed on the white ink layer WL. In the example of FIG. A color ink layer CL indicated by a broken line is formed between the ink layer WL. The reverse printing assumes that the color ink is first ejected onto the recording medium, and then the white ink and the moisturizing liquid are ejected on the color ink in this order, and the observer observes from the recording medium M1 side. However, in the back printing of this embodiment, color ink is not ejected, and only whiteness is evaluated.

  In the above-described front printing and back printing, printing was performed on the entire recording medium with one liquid (for example, moisturizing liquid), and then printing was performed on the entire recording medium with the other liquid (for example, white ink).

B1-4. Evaluation methods:
In the first example, a printing test was performed by ejecting the white ink described in Table 1 and the moisturizing liquids 1 to 5 described in Table 2 using the printer. The temperature in the printing environment was 27 ° C. and the humidity was 30%. As the recording medium, a dedicated recording paper for an ink jet printer (OHP sheet “VF-1101N” manufactured by KOKYUYO) was used. At this time, the duty value of the white ink and the duty value of the moisturizing liquid were both set to 50% except for some comparative cases. The “duty value” is a value calculated by the following formula (1).

  duty value (%) = number of actual printing dots / (vertical resolution × horizontal resolution) × 100 (1)

  In the above formula (1), “actual print dot number” is the actual print dot number per unit area, and “vertical resolution” and “horizontal resolution” are the number of pixels per unit length, respectively. A duty value of 100% means the maximum ink (liquid) weight of a single color for a pixel.

  The OHP sheet printed as described above was dried for 1 hour and then placed on a standard black paper, and the color (brightness: L *) was measured. In this embodiment, “lightness (L *)” is used as an index of whiteness (white ink density). The measurement of drying and color was performed under a total of two environments: an environment having a temperature of 27 ° C. and a humidity of 30% (measurement environment 1) and an environment having a temperature of 27 ° C. and a humidity of 80% (measurement environment 2). For the measurement of color, “938 Spectrodensitometer” manufactured by X-rite was used. The light source was D50. For front printing, the surface opposite to the printing surface of the recording paper was placed on a standard black paper, and measurement was performed from the printing surface as shown in FIG. For the back printing, the recording printing surface was placed on a standard black color paper, and the measurement was performed from the surface opposite to the printing surface as shown in FIG.

B1-5. Evaluation results:
Table 4 shows the printing test results of the front printing in the first example. Table 5 shows the printing test result of the back printing in the first example. In the first example, for the table printing, three implementation cases and three comparison cases shown in Table 4 were executed. Implementation cases 1 to 3 are cases in which white ink and moisturizing liquids 1 to 3 are ejected. Comparative case 1 is a case in which only white ink is ejected. Comparative case 2 is a case in which white ink and moisturizing liquid 4 are ejected, and comparative case 3 is a case in which white ink and moisturizing liquid 5 are ejected.

  In the first example, one back case and two comparison cases shown in Table 5 were executed for back printing. The implementation case 4 is a case in which the white ink and the moisturizing liquid 1 are ejected. Comparative case 4 is a case in which only white ink is ejected. The comparative case 5 is a case in which the white ink and the moisturizing liquid 4 are ejected. In Tables 4 and 5, the numerical values of the white ink and the moisturizing liquids 1 to 5 indicate the duty value.

In Tables 4 and 5, for each of the cases 1 to 4 and the comparative cases 1 to 5, in addition to the whiteness, the transparency evaluations (A to D) under the two measurement environments 1 and 2 described above are also shown. is doing. The transparency evaluation is an index indicating how low the whiteness (white ink density) is, and is specifically as follows.
<Transparency evaluation>
A: The whiteness at a temperature of 27 ° C. and a humidity of 30% is 65 or more, and the whiteness at a temperature of 27 ° C. and a humidity of 80% is 35 or less.
B: The whiteness at a temperature of 27 ° C. and a humidity of 30% is 65 or more, and the whiteness at a temperature of 27 ° C. and a humidity of 80% is greater than 35 and 45 or less.
C: The whiteness at a temperature of 27 ° C. and a humidity of 30% is 65 or more, and the whiteness at a temperature of 27 ° C. and a humidity of 80% is greater than 45 and 55 or less.
D: The whiteness at a temperature of 27 ° C. and a humidity of 30% is 65 or more, and the whiteness at a temperature of 27 ° C. and a humidity of 80% is greater than 55.

  In both front printing and back printing, the case (practical cases 1 to 4) in which the moisturizing liquid is jetted is compared to the case in which only the white ink is jetted (Comparative Examples 1 and 4). The whiteness is also low. This is considered to be due to the following reasons. Since the moisturizing agent contained in the moisturizing liquid has a high affinity for water, water (ion-exchanged water) contained in the moisturizing liquid and the white ink and water in the atmosphere are attracted. The moisture attracted by the humectant penetrates into the hollow of the hollow resin particles, so that the hollow resin particles become transparent (decrease in whiteness). Therefore, the whiteness is lower than in the case where no moisturizing liquid is used. It is thought that it became low (transparency became high).

  Therefore, since the whiteness can be lowered by ejecting the moisturizing liquid together with the white ink, the whiteness increase rate with respect to the increase in the duty value of the white ink is suppressed as compared with the case where only the white ink is ejected. Therefore, smooth gradation expression can be performed.

  As shown in Tables 4 and 5, in each of the implementation cases 1 to 4 and the comparison cases 1 to 3 and 5, the whiteness in the measurement environment 2 is lower than that in the measurement environment 1. This is because moisture is less likely to evaporate from the recording medium after printing as the humidity is higher, so that the humectant can retain a large amount of moisture and penetrate a large amount of moisture into the hollow of the hollow resin particles of the white ink. it is conceivable that.

  Implementation cases 1 to 3 have very low whiteness in the measurement environment 2 as compared to comparative cases 2 and 3. Similarly, the execution case 4 has a very low whiteness in the measurement environment 2 compared to the comparative case 5. Specifically, for example, in Comparative Case 3, the whiteness in the measurement environment 2 is 72, whereas in the Implementation Case 1, the whiteness in the measurement environment 2 is 30. Accordingly, the transparency evaluation is also D in the comparison cases 2, 3 and 5, whereas it is A or B in the implementation cases 1 to 4, which is greatly different from each other.

  These differences are considered to be due to the difference in the affinity of the moisturizing agent contained in each moisturizing liquid with water. As shown in Table 3, all of the humectants (glycerin, tetraethylene glycol, polyethylene glycol) contained in the humectants 1 to 3 used in the implementation cases 1 to 4 have an octanol / water partition coefficient of -1 or less. Relatively low. Therefore, since the affinity is relatively high, a relatively large amount of water can be attracted. On the other hand, all of the humectants (trimethylolpropane and hexylene glycol) contained in the humectants 4 and 5 used in the comparative cases 2, 3, and 5 have an octanol / water partition coefficient of −0.5 or more. High. Therefore, since the affinity is relatively low, only a relatively small amount of water can be drawn. From the above, it is considered that a difference in whiteness between Examples 1 to 3 and Comparative Cases 2 and 3 and a difference in whiteness between Example 4 and Comparative Case 5 occurred.

  In this way, when a moisturizing liquid containing a moisturizing agent having a relatively high affinity with water (octanol / water partition coefficient of −1 or less) is jetted together with the white ink, a relatively high humidity is obtained after printing. It is possible to reduce the whiteness (increase the degree of transparency) and increase the whiteness (to reduce the degree of transparency) when the humidity is relatively low. That is, the whiteness can be changed according to the environment (humidity) after printing. Therefore, for example, in front printing or back printing using color ink, the whiteness of the white ink behind the color ink can be changed according to the humidity after printing. It becomes possible to change the color of the color ink. Further, for example, in reverse printing, contrary to FIG. 4, by observing from the printing surface side of the recording medium, the whiteness of the white ink layer WL is increased and the color ink layer CL is increased in a relatively low humidity state. In a state where the humidity is relatively high, the whiteness of the white ink layer WL can be lowered and the color ink layer CL can be observed.

B2. Second embodiment:
In the second embodiment, the change in whiteness accompanying the change in the printing environment and the change in the duty value of the moisturizing liquid is exemplified.

B2-1. White ink, moisturizing liquid and printing device:
In the second example, similarly to the first example, a printing test was performed by ejecting white ink and a moisturizing liquid. Specifically, the white ink shown in Table 1 was used as the white ink, and the moisturizing liquid 1 shown in Table 2 was used as the moisturizing liquid. Further, the same printer as in the first example was used as a printing apparatus.

B2-2. Evaluation methods:
The evaluation method in the second example is the same as the evaluation method in the first example. However, it differs from the first embodiment in that the printing environment has four patterns and the duty value of the moisturizing liquid is set to a value other than 50 (10, 25, 30, 45, 60). The four patterns in the printing environment are a pattern with a temperature of 27 ° C. and a humidity of 30%, a pattern with a temperature of 27 ° C. and a humidity of 80%, a pattern with a temperature of 40 ° C. and a humidity of 30%, and a pattern with a temperature of 40 ° C. and a humidity of 80%. It is. Note that the duty value of the white ink in the second embodiment is 50. In the second embodiment, only the front printing is executed to measure the color.

B2-3. Evaluation results:
Tables 6 and 7 show the print test results in the second example. Table 6 shows the test results when the temperature is 27 ° C. in the printing environment, and Table 7 shows the test results when the temperature is 40 ° C. in the printing environment.

  In the second example, ten implementation cases (implementation cases 5 to 14) in which at least one of the printing environment and the duty value of the moisturizing liquid are different from each other were executed. The printing environment in the implementation cases 5 and 6 is a temperature of 27 ° C. and a humidity of 30%, the printing environment in the implementation cases 7 to 10 is a temperature of 27 ° C. and a humidity of 80%, and the printing environment in the implementation cases 11 and 12 is The temperature is 40 ° C. and the humidity is 30%, and the printing environment in the implementation cases 13 and 14 is the temperature 40 ° C. and the humidity 80%.

  In any of the four printing environments, the greater the duty value of the moisturizing liquid, the lower the whiteness in the measurement environment 2 (temperature 27 ° C., humidity 80%), and accordingly, the degree of transparency evaluation is higher. This is because the more moisturizing agent contained in the moisturizing liquid, the more water can be held in the vicinity of the white ink, so that more water can permeate into the cavity of the hollow resin particles of the white ink. This is thought to be possible.

  Further, in the case where the duty value of the moisturizing liquid is the same, the higher the temperature in the printing environment, the higher the whiteness in the measurement environment 2 (temperature 27 ° C., humidity 80%), and accordingly, the transparency evaluation becomes lower. ing. For example, the implementation case 9 and the implementation case 14 both have the same duty value of the moisturizing liquid 1 and the humidity during printing (duty value: 50, humidity: 80%), and the temperatures during printing (27 ° C. and 40 ° C.). ° C) are different from each other. In these cases, the whiteness is “31” in the implementation case 9 (27 ° C.), whereas the whiteness is “32” in the implementation case 14 (40 ° C.). Further, when the humidity during printing is relatively low (humidity: 30%), for example, implementation case 1 (27 ° C.) in the first embodiment shown in Table 1 and implementation case 12 in the second embodiment ( 40 ° C.). In the case 1 (27 ° C.), the whiteness in the measurement environment 2 is “30”, whereas in the case 12 the whiteness in the measurement environment 2 is “39”. As described above, the higher the temperature during printing, the higher the whiteness. The higher the temperature during printing, the easier the moisture evaporates from the printed surface immediately after printing. This is presumably because the amount of water penetrating into the cavity of the hollow resin particles of the white ink is reduced.

  In addition, when the duty value of the moisturizing liquid is the same, the higher the humidity in the printing environment, the lower the whiteness in the measurement environment 2 (temperature 27 ° C., humidity 80%), and accordingly, the degree of transparency evaluation becomes higher. ing. For example, both the implementation case 12 and the implementation case 14 have the same duty value of the moisturizing liquid 1 and the humidity during printing (duty value: 50, temperature: 40 ° C.), and the humidity during printing (30% and 80%). %) Are different from each other. In these cases, the whiteness in the measurement environment 2 is “39” in the implementation case 12 (30%), whereas the whiteness in the measurement environment 2 is “32” in the implementation case 14 (80%). . In this way, the higher the humidity during printing, the lower the whiteness. The higher the humidity during printing, the less moisture is evaporated from the printing surface immediately after printing, so the moisture that can be retained by the moisturizing liquid increases. This is probably because the amount of moisture penetrating into the cavity of the hollow resin of the white ink increases.

  From such experimental results, for example, when the temperature rises, it can be understood that an increase in whiteness (decrease in transparency) can be suppressed by increasing the amount of moisturizing liquid to be injected (duty value). . In addition, when the humidity increases, it can be understood that a decrease in whiteness (an increase in transparency) can be suppressed by reducing the amount (duty value) of the moisturizing liquid to be ejected. That is, in general, whiteness (transparency) is achieved by ejecting moisturizing liquid in addition to ejecting white ink and changing the amount of moisturizing liquid ejected according to changes in at least one of temperature and humidity. Degree) can be suppressed. On the contrary, when the temperature at the time of printing rises, the whiteness can be further increased by reducing the amount (duty value) of the moisturizing liquid to be ejected. Further, when the humidity during printing increases, the whiteness can be further reduced by increasing the amount (duty value) of the moisturizing liquid to be ejected.

B3. Third embodiment:
The third embodiment exemplifies a printing apparatus (printer) that changes the amount of moisturizing liquid to be ejected according to changes in temperature and humidity, and suppresses changes in whiteness regardless of changes in temperature and humidity.

  FIG. 5 is an explanatory diagram illustrating a printing apparatus according to a third embodiment. The printing apparatus 10a according to the third embodiment has printing in the embodiment shown in FIG. 1 in that it includes a temperature sensor 71 and a humidity sensor 72 and in that the main control unit 40a includes a discharge amount table 41. Unlike the apparatus, the other configuration is the same as that of the printing apparatus in the embodiment.

  The temperature sensor 71 and the humidity sensor 72 are connected to the main control unit 40a. The temperature sensor 71 detects the temperature and notifies the main controller 40a. The humidity sensor 72 detects the humidity and notifies the main controller 40a. Based on the notified temperature and humidity, the main control unit 40a refers to the discharge amount table 41 to determine the ejection amount of the white ink and the moisturizing liquid, and ejects the determined amount of the white ink and the moisturizing liquid. The print head 31 is controlled. The main control unit 40a corresponds to an environmental value acquisition unit and an injection amount determination unit in the claims.

  FIG. 6 is an explanatory diagram illustrating an example of setting contents of the discharge amount table 41 illustrated in FIG. In the discharge amount table 41, for each whiteness (L *), a white ink amount (duty value) and a moisturizing liquid amount (duty value) corresponding to the environment (temperature and humidity) are set. In the example of FIG. 6, the entry E1 with a temperature of 27 ° C. and a humidity of 30%, the entry E2 with a temperature of 27 ° C. and a humidity of 80%, and the entry E3 with a temperature of 40 ° C. and a humidity of 30% are shown. Has been described. In addition, each entry of the combination of the other temperature and humidity in whiteness "50", and each entry in other whiteness are abbreviate | omitted.

  When the temperature notified from the temperature sensor 71 is 27 ° C. and 30% notified from the humidity sensor 72, the main control unit 40a searches the discharge amount table 41 based on these values to find the entry E1. It becomes. As a result, the print head 31 ejects the white ink and the moisturizing liquid so that the duty value of the white ink becomes “50” and the duty value of the moisturizing liquid becomes “30”. In this case, as shown in an implementation case 5 of the second embodiment, the whiteness (L *) in the measurement environment 2 is “50”.

  Here, when the temperature remains 27 ° C. and the humidity increases from 30% to 80%, the main control unit 40a finds the entry E2 in the ejection amount table 41, and the print head 31 has the duty value of white ink “ It is sprayed so that the duty value of the moisturizing liquid becomes “10”. In this case, as shown in an implementation case 7 of the second embodiment, the whiteness (L *) in the measurement environment 2 is “50”. Therefore, the whiteness can be suppressed from decreasing to “34” as in the case 8 of implementation. That is, in the printing apparatus 10a of the third embodiment, the change in whiteness can be suppressed even when the humidity increases.

  When the temperature rises from 27 ° C. to 40 ° C. while the humidity remains at 30%, the main control unit 40a finds the entry E3 in the ejection amount table 41, and the print head 31 has a duty value of “50” for the white ink. The white ink and the moisturizing liquid are ejected so that the duty value of the moisturizing liquid becomes “70”. As described above, when the temperature rises, an increase in whiteness can be suppressed by increasing the amount of the moisturizing liquid sprayed. Accordingly, since the discharge amount of the moisturizing liquid increases from “50” to “70”, an increase in whiteness can be suppressed. That is, in the printing apparatus 10a of the third embodiment, the change in whiteness can be suppressed even when the temperature rises.

C. Variation:
In addition, elements other than the elements claimed in the independent claims among the constituent elements in each of the above embodiments are additional elements and can be omitted as appropriate. The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

C1. Modification 1:
In each of the embodiments described above, the moisturizing liquid is ejected in addition to the white ink. Alternatively, the white ink may include a moisturizing agent and only the white ink may be ejected.

  Table 8 shows an example of a white ink containing a humectant. The unit of numerical values described in Table 8 is% by weight.

  The white ink 2 shown in Table 8 contains trimethylolpropane as a humectant. The white ink 3 contains glycerin as a humectant. Each of these two humectants has an octanol / water partition coefficient value of −1 or less, as shown in Table 3 above. In the white inks 2 and 3, the other components except the moisturizing agent are the same as those of the white ink shown in Table 1. A printing test was performed using these white inks 2 and 3. This printing test is different from the first embodiment in that the moisturizing liquid is not jetted, and other test methods and evaluation methods are the same as those in the first embodiment.

  Table 9 shows the print test results using the white inks 2 and 3 shown in Table 8.

  In Table 9, front case printing was performed in the working cases 15 and 16, and back printing was performed in the working cases 17 and 18. Further, the white ink 2 was used in the implementation cases 15 and 17, and the white ink 3 was used in the implementation cases 16 and 18. In any of the implementation cases 15 to 18, the duty value of the white ink was “100”.

  As shown in Table 9, the white color was measured in the measurement environment 2 (27 ° C., 80%) regardless of whether the front printing or the reverse printing was performed or when any of the white inks 2 and 3 was used. Low degree (high transparency). In the comparison cases 1 and 4 shown in Tables 4 and 5 described above, the duty value of white ink, the printing environment, and the measurement environment 2 are all the same as the implementation cases 15 to 18. However, the implementation cases 15 to 18 have lower whiteness in the measurement environment 2 than the comparison cases 1 and 4. This is presumably because the moisturizing agent contained in the white inks 2 and 3 performed the same function as the moisturizing agent contained in the moisturizing liquid in the first embodiment. That is, in general, an ejection mechanism that ejects white ink and a humectant can be employed in the printing apparatus of the present invention.

C2. Modification 2:
In the third embodiment, the main control unit 40a is notified of the temperature and humidity from the temperature sensor 71 and the humidity sensor 72, but the present invention is not limited to this. For example, the temperature and humidity can be notified from the personal computer 90 shown in FIG. In this case, for example, the personal computer 90 can be configured to include a temperature sensor and a humidity sensor, and the user can also input the temperature and humidity to the personal computer 90.

  In the third embodiment, both the temperature and the humidity are detected, and the discharge amount table 41 is searched using both the temperature and the humidity as a key. However, only the temperature or the humidity is detected, and the detected temperature is detected. Alternatively, the discharge amount table 41 can be searched using humidity as a key. In this case, for example, in the discharge amount table 41, assuming that the humidity is constant, the amount of white ink (duty value) and the amount of moisturizing liquid (duty value) corresponding to the temperature change, and the temperature are assumed to be constant. It is preferable to set the amount of white ink and the amount of moisturizing liquid according to the humidity change. That is, in general, an environmental value acquisition unit that acquires at least one of temperature and humidity can be employed in the printing apparatus of the present invention. In addition, an ejection mechanism that ejects white ink and moisturizing liquid according to at least one of temperature and humidity can be employed in the printing apparatus of the present invention.

C3. Modification 3:
In each embodiment, in front printing and back printing, printing is performed on the entire recording medium with one liquid (for example, moisturizing liquid), and then printing is performed on the entire recording medium with the other liquid (for example, white ink). However, the present invention is not limited to this. For example, the nozzle row of each color is divided into an upstream nozzle group and a downstream nozzle group along the paper feeding direction of the recording paper, and white ink is ejected by the upstream nozzle group for white ink in a certain pass. In addition, by spraying the moisturizing liquid in the downstream nozzle group for the moisturizing liquid, transporting the recording paper by the distance of the nozzle group, and repeating the ejection of the white ink preliminarily and the moisturizing liquid in the next pass, Back printing can also be realized. It should be noted that the front printing can be performed in the same manner.

C4. Modification 4:
In the embodiment and each example, the printing apparatus (printer) is a so-called on-carriage type in which the ink cartridge is mounted on the carriage. Instead, the ink cartridge is disposed in a place other than the carriage. A so-called off-carriage type can also be employed.

C5. Modification 5:
In each embodiment, as shown in FIG. 2, the nozzle row 36n that ejects white ink and the nozzle row 39n that ejects the moisturizing liquid use different nozzle rows, but the present invention is not limited to this. Is not to be done. For example, a switching valve for switching the ink to be supplied to the nozzle row is provided in the print head 31 or the main body of the printing apparatus 10 or 10a, and the white ink and the moisturizing liquid are supplied from the same nozzle row by using this switching valve. It is possible to adopt a configuration in which injection is performed by switching between and. Further, with the same configuration, it is possible to adopt a configuration in which white ink and moisturizing liquid are switched and ejected from the same nozzle row. In these configurations, the print head including the nozzle row that ejects the white ink and the moisturizing liquid corresponds to the ejection mechanism in the claims.

C6. Modification 6:
In the second and third embodiments, the whiteness is changed by adjusting the injection amount of the moisturizing liquid according to the temperature and the humidity. The whiteness can also be changed by adjusting the amount of white ink ejected according to the humidity. This is because the amount of white color material (hollow resin particles) decreases and the degree of transparency changes because the amount of white ink ejected relative to the moisturizing liquid changes. That is, generally, an ejection mechanism that ejects white ink and moisturizing liquid according to at least one of temperature and humidity can be employed in the printing apparatus of the present invention.

  DESCRIPTION OF SYMBOLS 10,10a ... Printing apparatus, 21 ... Carriage motor, 22 ... Motor, 23 ... Drive belt, 24 ... Sliding shaft, 25 ... Platen, 26 ... Pulley, 30 ... Carriage, 31 ... Print head, 32 ... First ink cartridge 33 ... Second ink cartridge, 34 ... Third ink cartridge, 35 ... Fourth ink cartridge, 36 ... Fifth ink cartridge, 37 ... Sixth ink cartridge, 38 ... Seventh ink cartridge, 39 ... Eighth ink cartridge, 32n to 39n ... nozzle array, 40, 40a ... main control unit, 50 ... operation unit, 60 ... connector, 71 ... temperature sensor, 72 ... humidity sensor, 90 ... personal computer, P ... recording paper, E1-E3 ... entry, HL ... Moisturizing liquid layer, WL ... White ink layer, CL ... Color ink layer, Sn ... Noz Forming surface

Claims (4)

A printing device,
An environmental value acquisition unit for acquiring at least one of temperature and humidity;
An injection amount determination unit that determines an injection amount of a moisturizing liquid that is a liquid containing a moisturizing agent having an octanol / water partition coefficient of −1.0 or less according to at least one of the acquired temperature and humidity;
An ejection mechanism that ejects the determined amount of the moisturizing liquid and ink containing hollow resin particles;
A printing apparatus comprising: The printing apparatus according to claim 1,
The printing apparatus, wherein the ejection amount determination unit increases the ejection amount of the moisturizing liquid as the acquired temperature is higher. The printing apparatus according to claim 1 or 2,
The ejection amount determination unit is a printing apparatus that reduces the ejection amount of the moisturizing liquid as the acquired humidity is higher. Printing method,
(A) acquiring at least one of temperature and humidity;
(B) In accordance with at least one of the temperature and humidity acquired in the step (a), the injection amount of the moisturizing liquid that is a liquid containing a moisturizing agent having an octanol / water partition coefficient of −1.0 or less is determined. Process,
(C) ejecting the amount of the moisturizing liquid determined in the step (b) and the ink containing the hollow resin particles;
A printing method comprising:

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