JP5999235B2 - Ink set - Google Patents

Description

  The present invention relates to an ink set.

  Conventionally, a desired image is formed by attaching ink to a recording medium using various recording methods. The formed image is required to have properties such as, for example, good abrasion resistance and resistance to cracking (cracking) depending on the application. Therefore, for the purpose of improving the properties of the image, it is widely performed to add various components to the ink used for forming the image. For example, Patent Document 1 describes that various oligomers and monomers are added to the ink composition in order to prevent cracking. Patent Document 2 describes that a nonionic compound such as polyethylene glycol is added to the ink in order to prevent cracking.

  In addition, an image formed on a recording medium may be required to have excellent color developability. In such a case, first, a base layer is formed with a white ink containing a white color material as a color material, and then a desired image is formed with a color ink containing a color color material. It is possible to form an image with good color developability with little influence of the inherent color.

JP 2008-12084 A JP 2007-194175 A

  However, when an image made of color ink is formed on an image made of white ink, the image may be cracked or the image may be deteriorated in abrasion resistance.

  In order to reduce such a problem, it is conceivable to add a component for improving the scratch resistance of an image and a component for reducing cracks in the image to the white ink. However, depending on the component to be added, there are cases where the improvement of the scratch resistance of the image and the reduction of cracking of the image cannot be satisfied at the same time. In addition, when the content ratio of the resin component in the white ink is increased in order to improve the scratch resistance of the image and reduce cracks in the image, the white color material and the like are likely to aggregate, and the ink jet recording apparatus discharges. Stability may be reduced.

  In order to solve the above problems, it is also conceivable to add a component for improving the abrasion resistance of an image and a component for reducing cracks in the image to the color ink. However, since an ink set usually has a plurality of color inks (for example, black ink, cyan ink, magenta ink, yellow ink, etc.), it is very difficult to add the above components to all color inks. Complicated work.

  One of the objects according to some embodiments of the present invention is to provide an ink set that can reduce the occurrence of cracking and can record an image having excellent abrasion resistance and also has excellent ejection stability. There is to do.

  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 aspects or application examples.

[Application Example 1]
One aspect of the ink set according to the present invention is:
A white ink containing a white color material and a first resin;
A color ink containing a color material other than the white color material;
A clear ink not containing a color material and containing a second resin,
The first resin includes a component (A) in which cracks are generated when 0.5 g is dropped on a slide glass and dried for 10 minutes under conditions of a temperature of 50 ° C. and a humidity of 0% RH,
The second resin includes a component (B) that is at least one of a polyolefin wax and an ethylene vinyl acetate resin.

  According to the aspect described in Application Example 1, cracks in the formed image can be reduced, and the formed image is excellent in abrasion resistance. In addition, when applied to an ink jet recording apparatus, the ink ejection stability is excellent.

[Application Example 2]
One aspect of the ink set according to the present invention is:
A white ink containing a white color material and a first resin;
A color ink containing a color material other than the white color material;
A clear ink not containing a color material and containing a second resin,
The first resin includes a component (A) which is at least one of a fluorene resin and a styrene acrylic resin,
The second resin includes a component (B) that is at least one of a polyolefin wax and an ethylene vinyl acetate resin.

  According to the aspect described in Application Example 2, cracks in the formed image can be reduced, and the formed image is excellent in abrasion resistance. In addition, when applied to an ink jet recording apparatus, the ink ejection stability is excellent.

[Application Example 3]
In application example 1,
The component (A) can be at least one of a fluorene resin and a styrene acrylic resin.

[Application Example 4]
In any one of Application Examples 1 to 3,
The content of the first resin in the white ink may be 1% by mass or more and 5% by mass or less.

[Application Example 5]
In any one of Application Examples 1 to 4,
The content of the second resin in the clear ink may be 3% by mass or more and 10% by mass or less.

[Application Example 6]
In any one of Application Examples 1 to 5,
Provided in the droplet discharge device,
After the white ink droplet and the clear ink droplet are ejected at substantially the same time, the white ink droplet and the clear ink droplet are brought into contact with each other on the recording medium and adhered. The color ink droplets can be ejected and used in an image forming method in which the color ink droplets are deposited on the white ink droplets and the clear ink droplets adhered to the recording medium.

[Application Example 7]
In any one of Application Examples 1 to 5,
Provided in the droplet discharge device,
After discharging the white ink droplets and attaching the white ink droplets to the recording medium, the clear ink droplets and the color ink droplets are discharged at substantially the same time. The clear ink droplet and the color ink droplet can be used in an image forming method in which the droplets are brought into contact with and adhered to the white ink droplets adhered to the recording medium.

[Application Example 8]
In Application Example 6 or Application Example 7,
The ratio (T _WB / T _WA ) between the total amount (T _WA ) of the component (A) on the recording medium and the total amount (T _WB ) of the component (B) on the recording medium is 0 .2 or more and 1.7 or less.

[Application Example 9]
In any one of Application Examples 1 to 8,
The polyolefin wax may have an average particle size of 100 nm to 200 nm.

  Hereinafter, preferred embodiments of the present invention will be described. The embodiment described below describes an example of the present invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

1. Ink Set An ink set according to an embodiment of the present invention includes a white ink, a color ink, and a clear ink. Hereinafter, components included in each ink according to the present embodiment will be described in detail.

1.1. White ink The white ink according to the present embodiment contains a white color material and a first resin. In the present invention, the term “white ink” refers to the lightness (L ^* ) and chromaticity (a ^* , b ^* ) of ink ejected on Epson genuine photographic paper <Glossy> (manufactured by Seiko Epson) at a duty of 100% or more. Using a spectrophotometer Spectrolino (trade name, manufactured by GretagMacbeth), the measurement conditions are set to D50 light source, the observation field is 2 °, the density is DIN NB, the white reference is Abs, the filter is No, and the measurement mode is Reflection. When measured in this manner, it indicates a range of 70 ≦ L ^* ≦ 100, −4.5 ≦ a ^* ≦ 2, −6 ≦ b ^* ≦ 2.5.

  In the present specification, the “duty value” is a value calculated by the following equation.

duty (%) = number of actual ejection dots / (vertical resolution × horizontal resolution) × 100
(In the formula, “number of actual ejection dots” is the number of actual ejection dots per unit area, and “vertical resolution” and “horizontal resolution” are resolutions per unit area.)
Next, components contained in the white ink will be described in detail.

1.1.1. White color material The white ink according to the present embodiment contains a white color material. Examples of the white color material include metal oxide, barium sulfate, and calcium carbonate. Examples of the metal oxide include titanium dioxide, zinc oxide, silica, alumina, and magnesium oxide. The white color material includes particles having a hollow structure, and the particles having a hollow structure are not particularly limited, and known ones can be used. As the particles having a hollow structure, for example, particles described in specifications such as US Pat. No. 4,880,465 can be preferably used. Among these, as the white color material contained in the white ink of the present embodiment, titanium dioxide is preferable from the viewpoints of whiteness and abrasion resistance.

  The content (solid content) of the white color material is preferably 1% or more and 20% or less, and more preferably 5% or more and 15% or less, with respect to the total mass of the white ink. When the content of the white color material exceeds the above range, nozzle clogging or the like of the ink jet recording apparatus may occur. On the other hand, when the content of the white color material is less than the above range, the color density such as whiteness tends to be insufficient.

  The volume-based average particle size (hereinafter referred to as “average particle size”) of the white color material is preferably 30 nm or more and 600 nm or less, and more preferably 200 nm or more and 400 nm or less. If the average particle diameter of the white color material exceeds the above range, the particles may settle and the dispersion stability may be impaired, or nozzle clogging may occur when applied to an ink jet recording apparatus. On the other hand, when the average particle diameter of the white color material is less than the above range, the whiteness tends to be insufficient.

  The average particle diameter of the white color material can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. Examples of the particle size distribution measuring apparatus include a particle size distribution meter (for example, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle.

1.1.2. First resin The white ink according to the present embodiment contains a first resin. One of the functions of the first resin is to fix white ink on a recording medium. The content (solid content) of the first resin is preferably 1% by mass to 7% by mass and more preferably 2% by mass to 4% by mass with respect to the total mass of the white ink. When the content of the first resin is within the above range, the discharge stability of the white ink is good when the white ink is applied to the ink jet recording apparatus. On the other hand, when the content of the first resin exceeds the above range, the white color material tends to aggregate, and when white ink is applied to the ink jet recording apparatus, nozzle clogging or the like occurs, resulting in a decrease in ejection stability. There is a case. Further, if the content of the first resin is less than the above range, the fixability of the white ink to the recording medium may be insufficient.

  Hereinafter, the components contained in the first resin will be described. The first resin is a concept including one or more kinds of resins, and “included in the first resin”, “includes the first resin”, “includes the first resin”. Etc. does not mean that it is included in the resin structure, but means that it is a resin corresponding to the first resin.

(1) (A) component 1st resin contains (A) component. The component (A) was dropped on a slide glass (for example, MICRO SLIDE GLASS S-7213, manufactured by Matsunami Glass Industrial Co., Ltd.) and dried for 10 minutes under conditions of a temperature of 50 ° C. and a humidity of 0% RH. It is a resin that sometimes cracks.

  Specific examples of the component (A) include at least one of a fluorene resin and a styrene acrylic resin. The component (A) not only has a function of fixing the white ink on the recording medium, but also has a function of remarkably improving the abrasion resistance of the image formed on the recording medium.

  The component (A) may generate cracks when dried. (A) Component cracking is, for example, by dropping 0.5 g of component (A) on a slide glass (MICRO SLIDE GLASS S-7213, manufactured by Matsunami Glass Industry Co., Ltd.), temperature 50 ° C., humidity 0% RH. It can be judged by the presence or absence of cracks in the dried product of component (A) when dried for 10 minutes under the above conditions. In addition, drying of (A) component can be performed using a well-known constant temperature / humidity tank etc., for example.

The fluorene resin used as the component (A) is not particularly limited as long as it has a fluorene skeleton, and can be obtained, for example, by copolymerizing the following monomer units (a) to (d). .
(A) Isophorone diisocyanate (CAS No. 4098-71-9)
(B) 4,4 ′-(9-fluorenylidene) bis [2- (phenoxy) ethanol] (CAS No. 117344-32-8)
(C) 3-hydroxy-2- (hydroxymethyl) -2-methylpropionic acid (CAS No. 4767-03-7)
(D) Triethylamine (CAS No. 121-44-8)
The fluorene resin used as the component (A) has a fluorene skeleton as shown by 4,4 ′-(9-fluorenylidene) bis [2- (phenoxy) ethanol] (CAS No. 117344-32-8). If it is resin containing a monomer, it will not restrict | limit in particular.

  Examples of the styrene acrylic resin used as the component (A) include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, and styrene-α-. Examples thereof include a methylstyrene-acrylic acid copolymer and a styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer. In addition, as a form of a copolymer, any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer can be used.

  In addition, as styrene acrylic resin, you may utilize what is marketed. Specific examples of commercially available styrene acrylic resins include Joncrill 62J (manufactured by BASF Japan Ltd.).

  Both the fluorene resin and the styrene acrylic resin can improve the abrasion resistance of the image formed with the white ink. However, when the fluorene resin is blended with the white ink, the image is more resistant to abrasion. Can be improved.

  The content (solid content) of the component (A) is preferably 1% by mass or more and 6% by mass or less, and more preferably 2% by mass or more and 4% by mass or less with respect to the total mass of the white ink. When the content of the component (A) is within the above range, the ejection stability when white ink is applied to an ink jet recording head is good, and the rub resistance and fixability of the recorded image are good. . On the other hand, when the content of the component (A) exceeds the above range, the recorded image may be cracked or the ejection stability of the nozzle may be lowered when applied to an ink jet recording apparatus. On the other hand, if it is less than the above range, the rub resistance of the recorded image may be lowered.

(2) Other resins As the first resin, only the component (A) may be used, but other resin components may be used in combination with the component (A).

  One of the functions of the other resin components is to fix the white ink on the recording medium and to improve the dispersibility of the white color material in the white ink. Examples of other resin components include acrylic resins, urethane resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-acetic acid. Known resins such as vinyl copolymers and ethylene vinyl acetate resins, component (B) described later, and the like can be mentioned.

  When the component (A) and the other resin component are used in combination as the first resin, the total content of the component (A) and the other resin component is preferably 1% by mass with respect to the total mass of the white ink. It is 6 mass% or less, More preferably, it is 2 mass% or more and 4 mass% or less. When the total content of the component (A) and other resin components exceeds the above range, when white ink is applied to an ink jet recording apparatus, nozzle clogging or the like may occur, resulting in a decrease in ejection stability. is there.

  In addition, when the component (B) described in “1.3.1. (1)” described later is included in the white ink, the content of the component (B) is preferably 2% by mass or less (“ “2% by mass or less” includes 0% by mass). The content of the component (B) in the white ink is more preferably 1% by mass or less (including 0% by mass), further preferably 0.5% by mass or less (including 0% by mass), and more preferably. 0.1% by mass or less (including 0% by mass). By including the component (B) that exhibits an effect of preventing cracks in other inks as much as possible, the discharge stability of the white ink may be improved.

1.1.3. Other Components The white ink according to the present embodiment can contain an organic solvent. The white ink may contain a plurality of types of organic solvents. Examples of the organic solvent used in the white ink include 1,2-alkanediols, polyhydric alcohols, and pyrrolidone derivatives.

  Examples of 1,2-alkanediols include 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, and the like. . Since 1,2-alkanediols are excellent in the action of increasing the wettability of the ink to the recording medium and uniformly wetting it, an excellent image can be formed on the recording medium. When 1,2-alkanediols are contained, the content thereof is preferably 1% by mass or more and 20% by mass or less with respect to the total mass of the white ink.

  Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and glycerin. Etc. Polyhydric alcohols can be preferably used from the viewpoint that when white ink is used in an ink jet recording apparatus, clogging or ejection failure can be reduced by suppressing drying and solidification of the ink on the nozzle surface of the head. When polyhydric alcohols are contained, the content is preferably 2% by mass or more and 20% by mass or less with respect to the total mass of the white ink.

  Examples of pyrrolidone derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, 5-methyl-2-pyrrolidone, etc. Is mentioned. The pyrrolidone derivative can act as a good solubilizer for the resin. When the pyrrolidone derivative is contained, the content is preferably 0.1% by mass or more and 25% by mass or less with respect to the total mass of the white ink.

  The white ink can contain a surfactant. Examples of the surfactant include a silicon-based surfactant and an acetylene glycol-based surfactant.

  As the silicon-based surfactant, a polysiloxane compound or the like is preferably used, and examples thereof include polyether-modified organosiloxane. More specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (above trade names, manufactured by Big Chemie Japan Co., Ltd.), KF-351A, KF- 352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF- 6012, KF-6015, KF-6017 (above trade names, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. A silicon-based surfactant can be preferably used from the viewpoint of having a function of uniformly spreading white ink on a recording medium so as not to cause density unevenness or bleeding. When a silicon surfactant is contained, the content thereof is preferably 0.1% by mass or more and 1.5% by mass or less with respect to the total mass of the white ink.

  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, and 3,5. -Dimethyl-1-hexyne-3ol, 2,4-dimethyl-5-hexyn-3-ol and the like. Also, commercially available acetylene glycol surfactants can be used. For example, Surfynol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, DF110D, CT111, CT121, CT131, CT136, TG, GA (all are trade names, manufactured by Air Products and Chemicals. Inc.), Orphine B, Y, P, A STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all trade names, Kawaken Fine Chemical Co., Ltd.). The acetylene glycol-based surfactant is superior to other surfactants in that it has an excellent ability to maintain surface tension and interfacial tension, and has almost no foaming property. When the acetylene-based surfactant is contained, the content thereof is preferably 0.1% by mass or more and 1.0% by mass or less with respect to the total mass of the white ink.

  The white ink according to the present embodiment may be a so-called aqueous ink containing 50% or more of water. Water-based inks are used in recording heads as compared to non-aqueous (solvent-based) inks (for example, inks described in US Patent Application Publication No. 2007/0044684 for ink used for recorded matter). Since the reactivity to the piezo element and the organic binder contained in the recording medium is weak, it may be possible to reduce melting or corrosion of these elements. In addition, the water-based ink may be able to form an image having excellent drying properties as compared with a non-water-based ink containing a large amount of a solvent having a high boiling point and a low viscosity. Furthermore, the water-based ink has an advantage that the odor is suppressed as compared with the solvent-based ink, and more than 50% of the composition is water, which is good for the environment.

  The white ink according to the present embodiment can further contain a pH adjuster, an antiseptic / antifungal agent, a rust inhibitor, a chelating agent, and the like. When the white ink according to the present embodiment contains these compounds, the characteristics may be further improved.

  Examples of the pH adjuster include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate, Examples thereof include sodium hydrogen carbonate.

  Examples of antiseptics and fungicides include sodium benzoate, sodium pentachlorophenol, 2-pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazoline-3-one Etc. Examples of commercially available products include Proxel XL2, Proxel GXL (above trade name, manufactured by Avicia), Denside CSA, NS-500W (above trade name, manufactured by Nagase ChemteX Corporation), and the like.

  Examples of the rust inhibitor include benzotriazole.

  Examples of the chelating agent include ethylenediaminetetraacetic acid and salts thereof (such as ethylenediaminetetraacetic acid dihydrogen disodium salt).

  The white ink according to 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.

1.2. Color ink The color ink according to the present embodiment contains a color material other than the white color material described above. The ink set according to the present embodiment can include a plurality of color inks having different hues. Hereinafter, components contained in the color ink will be described in detail.

1.2.1. Color Material The color ink according to the present embodiment contains a color material other than the above-described white color material (hereinafter also simply referred to as “color material”). Examples of the color material include dyes and pigments. The content of the color material is preferably 1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 15% by mass or less with respect to the total mass of the color ink.

(1) Pigment The pigment that can be used in the present embodiment is not particularly limited, and examples thereof include inorganic pigments and organic pigments.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone. Polycyclic pigments such as pigments, dye chelates (for example, basic dye type chelates, acidic dye type chelates), dyeing lakes (basic dye type lakes, acid dye type lakes), nitro pigments, nitroso pigments, aniline black, A daylight fluorescent pigment is mentioned. The said pigment may be used individually by 1 type, and may use 2 or more types together.

  More specifically, examples of the inorganic pigment used for black include the following carbon blacks, for example, No. manufactured by Mitsubishi Chemical. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia-made Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Color Black FW2, Clk Black FW2C, Decksa's Color Black FW2 FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, and Special Black 5S.

  Examples of yellow organic pigments include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, 180, 185, 213 and the like.

  Examples of magenta organic pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, 254, 264 or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50 and the like.

  Examples of cyan organic pigments include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15:34, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat Blue 4, 60 and the like.

  Examples of organic pigments other than magenta, cyan and yellow include C.I. I. Pigment green 7, 10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I. Pigment orange 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, and the like.

(2) Dyes As dyes, various dyes used for normal inkjet recording such as direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes, vat dyes, soluble vat dyes, reactive disperse dyes, etc. Can be used.

  Examples of yellow dyes include C.I. I. Acid Yellow 1, 3, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 59, 61, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 127, 131, 135, 142, 162, 164, 165, C.I. I. Direct Yellow 1, 8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 110, 132, 142, 144, C.I. I. Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42, C.I. I. Food Yellow 3, 4, C.I. I. Solvent yellow 15, 19, 21, 30, 109 etc. are mentioned.

  Examples of magenta dyes include C.I. I. Acid Red 1, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 75, 77, 80, 82, 85, 87, 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 186, 194, 198, 209, 211, 215, 219, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322, C.I. I. Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, C.I. I. Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63, 64, C.I. I. Sorbize red 1, C.I. I. Food red 7, 9, 14 etc. are mentioned.

  Examples of cyan dyes include C.I. I. Acid Blue 1, 7, 9, 15, 22, 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 199, 203, 204, 205, 229, 234, 236, 249, C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249, C.I. I. Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33 , 34, 37, 38, 39, 40, 41, 43, 44, 46, C.I. I. Solvize Bat Blue 1, 5, 41, C.I. I. Bat Blue 4, 29, 60, C.I. I. Food Blue 1, 2, C.I. I. Basic blue 9, 25, 28, 29, 44 etc. are mentioned.

  Examples of dyes other than magenta, cyan and yellow include C.I. I. Acid Green 7, 12, 25, 27, 35, 36, 40, 43, 44, 65, 79, C.I. I. Direct Green 1, 6, 8, 26, 28, 30, 31, 37, 59, 63, 64, C.I. I. Reactive Green 6, 7, C.I. I. Acid Violet 15, 43, 66, 78, 106, C.I. I. Direct violet 2, 48, 63, 90, C.I. I. Reactive violet 1, 5, 9, 10, C.I. I. Direct black 154 etc. are mentioned.

1.2.2. Resin The color ink according to the present embodiment can contain a resin. Examples of the function of the resin include fixing the color ink on the recording medium and improving the dispersibility of the color material in the color ink. The resin content is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less with respect to the total mass of the color ink. If the resin content exceeds the above range, when the color ink is applied to the ink jet recording apparatus, nozzle clogging or the like may occur, resulting in a decrease in ejection stability. The particle diameter of the color material used for the color ink is often smaller than the particle diameter of the white color material used for the white ink. For this reason, the color ink is less likely to cause aggregation of the color material, and even if it contains a larger amount of the resin component than the white ink, ejection failure is less likely to occur.

  Examples of resins that can be used when a resin is added to the color ink include acrylic resins, urethane resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, and epoxy resins. And known resins such as vinyl chloride resins and vinyl chloride-vinyl acetate copolymers, and the component (B) described later.

  When the component (B) described in “1.3.1. (1)” described later is contained in the color ink, the content of the component (B) is preferably 2% by mass or less (“2% by mass”). % Or less "includes 0 mass%). The content of the component (B) in the color ink is more preferably 1% by mass or less (including 0% by mass), further preferably 0.5% by mass or less (including 0% by mass), and more preferably. 0.1% by mass or less (including 0% by mass). By including the component (B), which exhibits an effect of preventing cracks, in other inks as much as possible, the discharge stability of the color ink may be improved.

1.2.3. Other Components The color ink according to the present embodiment can contain components other than those described above. The components that can be used in the color ink are the same as those described in “1.1.3. Other components”, and thus the description thereof is omitted.

1.3. Clear ink The clear ink according to this embodiment contains substantially no color material and contains the second resin. Since the clear ink according to the present embodiment does not substantially contain a color material, it is a colorless transparent or colorless translucent liquid. Note that “substantially no colorant” means, for example, that the content of the colorant in the ink is less than 0.5% by mass, more preferably less than 0.1% by mass, Preferably it is less than 0.01% by mass, and most preferably less than 0.005% by mass. Hereinafter, components included in the clear ink according to the present embodiment will be described.

1.3.1. Second Resin The clear ink according to the present embodiment contains a second resin. One of the functions of the second resin is to fix the clear ink to the recording medium. The content of the second resin is preferably 3% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 8% by mass or less, with respect to the total mass of the clear ink. When the content of the second resin exceeds the above range, when the clear ink is applied to the ink jet recording apparatus, nozzle clogging or the like may occur, and the ejection stability may decrease.

(1) (B) component 2nd resin contains (B) component. The component (B) is a resin composed of at least one of a polyolefin wax and an ethylene vinyl acetate resin. One of the functions of the component (B) is to reduce the occurrence of cracks in the image in addition to the function of improving the fixability of the clear ink described above. The second resin is a concept including one or more kinds of resins, and “includes in the second resin”, “includes in the second resin”, “includes in the second resin”. Etc. does not mean that it is included in the resin structure, but means that it is a resin corresponding to the second resin.

  Here, the ink set according to the present embodiment may be used for recording an image on a recording medium (for example, plastic or metal) that is not necessarily white. In such a case, the white ink is sometimes used for forming a base layer of a color image in order to erase the color of the recording medium or reduce the transparency of the color image. At this time, if a color image is recorded on the base layer made of white ink, cracks may occur in the image. The detailed mechanism of cracking is not clear, but is thought to be due to abrupt image shrinkage during the ink drying process, aggregation of components contained in the white ink and the color ink, and the like. In such a case, when the clear ink containing the component (B) is used for image formation, cracking of the image is effectively suppressed and the image has excellent abrasion resistance. If the clear ink contains the component (B) and the white ink and the clear ink are used in combination as necessary, it is not necessary to include the component (B) for each color ink that is usually prepared in a plurality of colors. The amount of component B) can be greatly reduced.

  On the other hand, when the component (B) is contained in the white ink or the component (B) is contained in the color ink, cracking of the image can be suppressed, but the ink ejection stability tends to be lowered.

  The polyolefin wax used as the component (B) is not particularly limited. For example, a wax produced from an olefin such as ethylene, propylene, butylene or a derivative thereof and a copolymer thereof, specifically, a polyethylene wax, Examples thereof include polypropylene wax and polybutylene wax. Among these, polyethylene wax is preferable from the viewpoint that the occurrence of cracks in the image can be more effectively reduced. Polyolefin waxes can be used singly or in combination of two or more.

  Examples of commercially available polyolefin waxes include “CHEMIPARL W4005” (manufactured by Mitsui Chemicals, Inc., polyethylene wax, particle size 200-800 nm, ring and ball method softening point 110 ° C., penetration method hardness 3, solid content 40%), etc. The Chemipearl series is listed. In addition, AQUACER 513 (polyethylene wax, particle size 100 to 200 nm, melting point 130 ° C., solid content 30%), AQUACER 507, AQUACER 515, AQUACER 840 (above, manufactured by Big Chemie Japan Co., Ltd.), Hitech E-7025P, Hitech series such as Hitech E-2213, Hitech E-9460, Hitech E-9015, Hitech E-4A, Hitech E-5403P, Hitech E-8237 (manufactured by Toho Chemical Co., Ltd.), Nopcoat PEM-17 (San Nopco) Manufactured, polyethylene emulsion, particle size 40 nm) and the like. These are commercially available in the form of an aqueous emulsion in which polyolefin wax is dispersed in water by a conventional method. In the clear ink according to this embodiment, it can be added directly in the form of an aqueous emulsion.

  The average particle size of the polyolefin wax is preferably 10 nm or more and 800 nm or less, more preferably 40 nm or more and 600 nm or less, and particularly preferably 100 nm or more and 200 nm or less. When the average particle diameter of the polyolefin wax is within the above range, cracks in the image generated by overlapping the white ink and the color ink can be reduced, and the abrasion resistance of the image can be improved. In particular, when a polyolefin wax having an average particle size of 100 nm or more and 200 nm or less is used as the component (B), both the ejection stability of the ink jet recording head and the abrasion resistance of the formed image are based on high standards. It will be prepared. On the other hand, when the average particle diameter of the polyolefin wax is less than the above range, the effect of improving the abrasion resistance of the recorded image tends to be lowered. In addition, when the average particle diameter of the polyolefin wax exceeds the above range, the ink ejection stability tends to decrease.

  The average particle diameter of the polyolefin wax can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. As the particle size distribution measuring device, for example, a particle size distribution meter (for example, “Microtrack UPA” manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle can be used.

  The ethylene vinyl acetate resin is not limited to a copolymer of ethylene and vinyl acetate, but may be a copolymer containing other monomers. Other monomers are not particularly limited, and known monomers can be used.

  As the ethylene vinyl acetate resin, either an emulsion type dispersed in a solvent in a solvent form or a solution type existing in a dissolved state in a solvent may be used. A dispersed emulsion type is preferred. Further, the emulsion type can be classified into a forced emulsification type and a self-emulsification type depending on the emulsification method, but any type can be used in the present invention.

  As commercially available products of ethylene vinyl acetate resin, EVAFLEX EV45X, EV40W · X, EV45LX, EV40LX, V5772ET, V5773W, EV150, EV205W, EV210, EV210ET, EV220, EV220ET, EV250, EV260, EV310, EV360, 410, EV757 EV420, EV450, EV460, EV550, EV560, P1207 (manufactured by Mitsui DuPont Polychemical Co., Ltd.), Sumikaflex, 201HQ, 520HQ, 410HQ (manufactured by Sumitomo Chemical Co., Ltd.), and the like.

  The content (solid content) of the component (B) is preferably 3% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 5% by mass or less with respect to the total mass of the clear ink. When the content of the component (B) is within the above range, cracks in an image formed by overlaying white ink and color ink can be effectively reduced. On the other hand, when the content of the component (B) exceeds the above range, nozzle clogging or the like of the ink jet recording apparatus may occur, and the ejection stability may decrease. Further, if it is less than the above range, there may be a case where an effect of reducing cracks in an image formed by overlaying white ink and color ink cannot be expected.

(2) Other resin components In addition to the component (B), other resin components may be used for the second resin in order to further improve image fixability.

  Examples of other resin components include acrylic resins, urethane resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-acetic acid. A known resin such as a vinyl copolymer may be used.

  When the component (B) and the other resin component are used in combination as the second resin, the total content of the component (B) and the other resin component is preferably 3% by mass or more based on the total mass of the clear ink. It is 10 mass% or less, More preferably, it is 3 mass% or more and 5 mass% or less. When the total content of component (B) and other resin components exceeds the above range, when clear ink is applied to an ink jet recording apparatus, nozzle clogging or the like may occur, resulting in reduced ejection stability. is there.

1.3.2. Other Components The clear ink according to this embodiment can contain components other than those described above. The components that can be used for the clear ink are the same as those described in “1.1.3. Other components”, and thus the description thereof is omitted.

1.4. Ink Physical Properties When the ink set according to this embodiment is used in an ink jet recording apparatus, the viscosity at 20 ° C. of white ink, color ink, and clear ink (hereinafter also simply referred to as “ink”) is 2 mPa · s or more and 10 mPa. -It is preferable that it is s or less, and it is more preferable that it is 3 mPa * s or more and 6 mPa * s or less. If the viscosity at 20 ° C. is within the above range, the ink can be suitably used for an ink jet recording apparatus because it can be discharged in an appropriate amount from the nozzle and can further reduce the occurrence of flight bending or scattering. The viscosity of the ink can be measured by keeping the temperature of the ink at 20 ° C. using a vibration viscometer VM-100AL (manufactured by Yamaichi Electronics Co., Ltd.).

2. Image Forming Method The ink set according to the present invention is provided in a droplet discharge device and can be used for image formation. As the droplet discharge device, a conventionally known device can be used, and examples thereof include an ink jet printer. Hereinafter, as an aspect of an image forming method using the ink set according to the present invention, a first image forming method, a second image forming method, and a third image forming method will be described.

2.1. First Image Forming Method In the first image forming method, a white ink droplet and a clear ink droplet are ejected at substantially the same time so that the white ink droplet and the clear ink droplet are covered. A step of contacting and adhering on the recording medium (hereinafter, also referred to as “step (1-1)”), and a droplet of white ink deposited on the recording medium by discharging a color ink droplet; And a step of depositing on the clear ink droplet (hereinafter also referred to as “step (1-2)”).

  In the present invention, “ejection at substantially the same time” means that ink droplets of one ink and the other ink are ejected at a timing at which they can be mixed with each other. As a result, an image in which the inks are mixed is recorded. For example, in a serial printer, there are cases where clear ink and white ink or color ink are landed at the same location in the same scanning.

  In step (1-1), at least a part of both the white ink and the clear ink are mixed. The contact of the white ink droplet and the clear ink droplet in the step (1-1) is the liquid that adheres to the recording medium later on the liquid droplet that adheres to the recording medium. The droplets may be in contact with each other, or these droplets may be attached to the recording medium at the same time. In either case, it is sufficient that at least a part of both inks are mixed and an image in which both inks are mixed is recorded.

  The step (1-2) is performed after the step (1-1), and the color ink droplets are attached onto the white ink and clear ink droplets ejected onto the recording medium. Thereby, since the white ink functions as a base layer, an image formed with the color ink has excellent color developability.

  By repeating the above steps (1-1) and (1-2), an image using color ink is formed on the image formed with white ink and clear ink.

2.2. Second Image Forming Method In the second image forming method, a step of ejecting white ink droplets to adhere to a recording medium (hereinafter also referred to as “step (2-1)”) and a clear ink are performed. And the color ink droplets are ejected at substantially the same time, and the clear ink droplets and the color ink droplets are brought into contact with the white ink droplets attached to the recording medium. (Hereinafter, also referred to as “step (2-2)”).

  The white ink droplets deposited on the recording medium in the step (2-1) function as a base layer of the color ink.

  In the step (2-2), at least a part of both the clear ink and the color ink is mixed. In the step (2-2), the clear ink droplet and the color ink droplet contact each other among the droplets previously attached to the white ink droplet, and then the white ink droplet. The droplets attached to the ink may come into contact with each other, or may be attached to and contact the white ink droplets at the same time. In either case, it is sufficient that at least a part of both inks are mixed and an image in which both inks are mixed is recorded.

  By repeating the above steps (2-1) and (2-2), an image made of clear ink and color ink is formed on the image formed with white ink.

2.3. Third Image Forming Method In the third image forming method, a step of ejecting white ink droplets to adhere to a recording medium (hereinafter also referred to as “step (3-1)”), and clear ink are used. , And a step of depositing on the white ink droplet deposited on the recording medium (hereinafter also referred to as “step (3-2)”), and a droplet of color ink are ejected. And a step of adhering onto the clear ink droplet (hereinafter also referred to as “step (3-3)”).

  In the third image forming method, an image in which a white image, a clear image, and a color image are stacked in this order on a recording medium can be obtained. In the third image forming method, since each ink is not ejected at substantially the same time, an image in which each ink is not mixed is formed.

2.4. Others The white ink and the clear ink each have the components described above. Therefore, according to the image recording method using the ink set according to the present invention, it is possible to form an image with few cracks and excellent abrasion resistance.

  Further, although the detailed mechanism has not been clarified, when the ink set according to the present invention is used in the first image forming method and the second image forming method, compared with the case where it is used in the third image forming method. Thus, cracks in the formed image can be reduced more effectively. Furthermore, when the ink set of the present invention is applied to the first image forming method, cracks in the formed image can be reduced more effectively than when applied to the second image forming method.

When an image is formed on a recording medium using the ink set according to the present invention, the total amount (T _WA ) of the component (A) on the recording medium and the component (B) on the recording medium The ratio (T _WB / T _WA ) to the total amount (T _WB ) is preferably 0.2 or more and 2 or less, more preferably 0.2 or more and 1.7 or less, and particularly preferably 0.3 or more. 0.7 or less. When the ratio (T _WB / T _WA ) is within the above range, an image with less blur can be obtained.

T _WA and T _WB are, for example, white ink, color ink, duty value of clear ink, content ratio of component (A) contained in white ink, content ratio of component (B) contained in clear ink, etc. Can be set as appropriate.

  Further, the degree of cracking of the image may vary depending on the type of color material added to the color ink. In such a case, an excellent image with few cracks can be recorded regardless of the type of color material by changing the duty value of the clear ink for each type of color material added to the color ink.

3. EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

3.1. Preparation of ink In the blending amounts shown in Tables 1 to 4, the colorant, resin component, 1,2-hexanediol, 2-pyrrolidone, propylene glycol, polysiloxane surfactant and ion-exchanged water were mixed and stirred, and the pore size The white ink, the clear ink, and the color ink used for the following evaluation were prepared by filtering with a metal filter of 5 μm and deaeration using a vacuum pump.

  In addition, as for the unit of the numerical value described in Table 1-Table 4, all are the mass%, and all are the values converted into solid content about the titanium dioxide pigment and the resin component.

Specifically, the components listed in Tables 1 to 4 were as follows.
(Color material)
・ Titanium dioxide pigment (Shi Kasei Co., Ltd., trade name “NanoTek® Slurry”, slurry containing titanium dioxide particles having an average particle diameter of 300 nm at a solid content concentration of 15%)
・ Cyan pigment (CI Pigment Blue 15: 3)
(Resin component)
・ Fluorene resin ・ Styrene acrylic resin (BASF Japan Ltd., trade name “Johncrill 62J”)
・ Polyethylene wax A (manufactured by Big Chemie Japan, trade name “AQUACER513”, average particle size 150 nm)
・ Polyethylene-based wax B (Mitsui Chemicals, trade name “CHEMIPARL W4005”, average particle size 600 nm)
・ Polyethylene wax C (manufactured by San Nopco, trade name “Nopcoat PEM-17”, average particle size 40 nm)
・ Ethylene vinyl acetate resin (Mitsui DuPont Polychemical Co., Ltd., “Evaflex EV210”, average particle size 200 nm)
・ Urethane resin (Mitsui Chemicals, trade name “W635”, average particle size 150 nm) (other components)
・ Surfactant (BIC Chemie Japan Co., Ltd., trade name “BYK-348”, silicone surfactant)
・ 1,2-hexanediol ・ 2-pyrrolidone ・ propylene glycol ・ ion-exchanged water

  The above fluorene-based resin is obtained by synthesis as follows. The fluorene resin is composed of 30 parts by mass of isophorone diisocyanate, 50 parts by mass of 4,4 ′-(9-fluorenylidene) bis [2- (phenoxy) ethanol], 3-hydroxy-2- (hydroxymethyl) -2-methylpropionic acid. 100 parts by mass and 30 parts by mass of triethylamine were weighed and mixed well, and then synthesized by stirring at 120 ° C. for 5 hours in the presence of a catalyst. The obtained fluorene-based resin was a resin having a molecular weight of 3300, containing 4,4 '-(9-fluorenylidene) bis [2- (phenoxy) ethanol] having a monomer composition ratio of about 50% by mass.

  The styrene acrylic resin and fluorene resin used were both dropped 0.5 g onto a slide glass (MICRO SLIDE GLASS S-7213, manufactured by Matsunami Glass Industrial Co., Ltd.) at a temperature of 50 ° C. and a humidity of 0. When it was dried for 10 minutes under the condition of% RH, cracks occurred.

  Further, the amount of propylene glycol added in the examples and comparative examples was changed in order to adjust the viscosity of each ink.

3.2. Inkjet printer For the following evaluation tests, a heater that can change the temperature is attached to the paper guide section of an inkjet printer PX-G930 (trade name, manufactured by Seiko Epson Corporation, nozzle resolution: 180 dpi) as a printer of an inkjet recording system. What was done was used.

  Next, the white ink, the clear ink, and the color ink described in Tables 1 to 4 were filled in ink cartridges dedicated to an inkjet printer (product name “PX-G930” manufactured by Seiko Epson Corporation), respectively. In addition, an ink set composed of a white ink, a clear ink, and a color ink was obtained for each comparative example. Each of the ink sets thus obtained was mounted on the modified printer.

3.3. Evaluation test of ejection stability (1) Continuous printing of solid pattern image Using the printer described above, droplets are ejected from the nozzles for each ink under the conditions of resolution 1440 × 720 dpi and duty 100%, and A4 size recording is performed. A single-color solid pattern image was continuously printed on 10 sheets of media (Lumirror (R) S10-100 μm, manufactured by Toray Industries, Inc.).

(2) Evaluation of ejection stability After continuous printing of the solid pattern image, a nozzle check pattern was printed for each ink. At this time, by visually observing missing nozzles or flying bends, the ejection stability of each ink was evaluated, and the ink with the worst ejection stability was evaluated. The evaluation criteria are as follows. If the evaluation is B or more, it can be determined that the ejection stability is of a level that does not cause a problem in practical use.
A: No missing nozzle and no flying curve B: No missing nozzle, but curved flight C: No nozzle missing

3.4. Rubbing resistance evaluation test 3.4.1. Preparation of samples for evaluation of abrasion resistance (1) Examples 1 to 10
Using the printer described above, images were printed and dried on an A4 size recording medium (Lumirror (R) S10-100 μm, manufactured by Toray Industries, Inc.).

  Specifically, first, white ink (printing condition: resolution 1440 × 720 dpi, 100% duty) and clear ink (printing condition: resolution 1440 × 720 dpi, 20% to 60% duty) are substantially the same. The ink droplets were ejected, the droplets of both inks were contacted (mixed) on the recording medium, and adhered to form a clear image and a white solid pattern image.

  Then, only a color ink (printing condition: resolution 1440 × 720 dpi, 100% duty) was attached on the white ink and the clear ink attached to the recording medium to form a cyan solid pattern image. Thereafter, the obtained image was dried by a heater provided in the printer. In this way, samples (Examples 1 to 10) for evaluating abrasion resistance in which a cyan solid pattern image was printed on a white solid pattern image and a clear image were obtained.

  The heater temperature of the printer was set to 45 ° C. Further, when the surface temperature of the recording medium in the vicinity of the printer head was measured during image recording, the surface temperature of the recording medium was substantially the same as the heater set temperature of the printer.

(2) Example 11
Using the printer described above, images were printed and dried on an A4 size recording medium (Lumirror (R) S10-100 μm, manufactured by Toray Industries, Inc.).

  Specifically, first, only white ink (printing conditions: resolution 1440 × 720 dpi, 100% duty) was deposited on the recording medium to form a white solid pattern image.

  Next, clear ink (printing condition: resolution 1440 × 720 dpi, 20% duty) and color ink (printing condition: resolution 1440 × 720 dpi, 100% duty) are ejected on the white solid pattern image at substantially the same time. Then, both ink droplets were brought into contact with each other on the recording medium and mixed to form a clear ink image and a cyan solid pattern image. Thereafter, the obtained image was dried by a heater provided in the printer. In this way, a sample (Example 11) for evaluating abrasion resistance in which a clear image and a cyan solid pattern image were printed on a white solid pattern image was obtained.

  The heater temperature of the printer was set to 45 ° C. Further, when the surface temperature of the recording medium in the vicinity of the printer head was measured during image recording, the surface temperature of the recording medium was substantially the same as the heater set temperature of the printer.

(3) Comparative Example 1 and Comparative Example 2
Using the printer described above, images were printed and dried on an A4 size recording medium (Lumirror (R) S10-100 μm, manufactured by Toray Industries, Inc.).

  Specifically, first, only a white ink (printing condition: resolution 1440 × 720 dpi, 100% duty) was adhered on the recording medium to form a white solid pattern image. Next, only a color ink (printing condition: resolution 1440 × 720 dpi, 100% duty) was attached on the white solid pattern image to form a cyan solid pattern image. Then, the obtained image was dried by a heater provided in the printer. In this way, samples (Comparative Example 1 and Comparative Example 2) for evaluating abrasion resistance in which a cyan solid pattern image was printed on a white solid pattern image were obtained.

  The heater temperature of the printer was set to 45 ° C. Further, when the surface temperature of the recording medium in the vicinity of the printer head was measured during image recording, the surface temperature of the recording medium was substantially the same as the heater set temperature of the printer.

3.4.2. Evaluation of abrasion resistance The obtained abrasion resistance evaluation sample was dried in a thermostatic bath at 50 ° C. for 10 minutes, and then subjected to a load of 200 g and the number of friction using a Gakushin type friction fastness tester AB-301 (manufactured by Tester Sangyo Co., Ltd.). Under the conditions of 10 times, the friction piece attached with the white cotton cloth for friction (Kanakin No. 3) and the recorded material were rubbed together, and the surface state of the image was visually observed. The evaluation criteria are as follows. If the evaluation is B or higher, it can be determined that the film has sufficient abrasion resistance that is not problematic for practical use.
A: Transfer of color color to white cotton cloth for friction, but no peeling of the white image of the base B: Peeling is observed on the white image of the base [0% <(area of the peeled white image) ≦ 50% ]
C: Remarkable peeling is recognized in the white image of the ground [50% <(area of peeled white image) ≦ 100%]

3.5. Cracking test 3.5.1. Preparation of crack crack evaluation sample (1) Examples 1 to 10
Samples for evaluation of cracks in Examples 1 to 10 were prepared in the same manner as in “3.4.1. (1)” except that the duty of the color ink was changed from 15% to 100% in each example. did.

(2) Example 11
A sample for evaluation of cracks in Example 11 was prepared in the same manner as in “3.4.1.1. (2)” except that the duty of the color ink was changed from 15% to 100%.

(3) Comparative Examples 1 to 2
Samples for evaluation of cracks in Comparative Examples 1 and 2 were prepared in the same manner as in “3.4.1. (3)” except that the duty of the color ink was changed from 15% to 100% for each Comparative Example. did.

3.5.2. Crack crack evaluation The obtained crack crack evaluation sample was dried in a thermostatic bath at 50 ° C for 10 minutes, and then the image surface was visually determined. The evaluation criteria are as follows. If the evaluation is B or more, it can be determined that cracking can be prevented to the extent that there is no problem in practical use.
A: No cracking of the image even when the duty of the color ink is 100% B: No cracking of the image if the duty of the color ink is up to 80% C: No cracking of the image if the duty of the color ink is up to 50% D: Even if the duty of the color ink is 30% Cracks

3.6. Bleeding test 3.6.1. Preparation of bleeding evaluation sample (1) Examples 1 to 10
The bleeding evaluation samples in Examples 1 to 10 were printed so that the duty of the color ink was set to 15% to 100% in each example, and the boundary between the white image and the color ink image was understood. Other than the above, it was created in the same manner as the above “3.4.1. (1)”.

(2) Example 11
In the sample for bleeding evaluation in Example 11, the duty of the color ink is set to 15% to 100%, and the color ink is discharged so that the boundary portion between the white image and the color image can be seen. 1.1 (2) ".

(3) Comparative Examples 1 to 2
In the samples for evaluating bleeding in Comparative Examples 1 and 2, the duty of the color ink is set to 15% to 100% for each Comparative Example, and the color ink is discharged so that the boundary between the white image and the color image can be seen. Except for the above, it was created in the same manner as the above “3.4.1. (3)”.

3.6.2. Bleeding Evaluation The obtained bleeding evaluation sample was dried in a thermostatic bath at 50 ° C. for 10 minutes, and then the bleeding at the boundary between the white image and the color image was visually observed. The evaluation criteria are as follows. When the evaluation is C or higher, it can be determined that bleeding can be prevented to the extent that there is no problem in practical use.
A: No bleeding is observed even when the color ink has a duty of 100% B: No bleeding is observed if the color ink has a duty of 80% C: No bleeding is observed if the color ink has a duty of 50% D: Even if the duty of the color ink is 30% Is accepted

3.7. Evaluation results The above evaluation results are also shown in Tables 1 to 4. In Tables 1 to 4, T _WA represents the total amount of component (A) on the recording medium, and T _WB represents the total amount of component (B) on the recording medium.

  As shown in the evaluation test results of Tables 1 to 3, according to the ink sets of Examples 1 to 10, images with reduced cracking and bleeding and excellent abrasion resistance were recorded. Ink ejection stability was also excellent.

  In Example 1 and Example 11, the same ink set is used, and the image forming method is different. From the evaluation results of cracks, it was shown that the first image forming method (Example 3) was superior to the second image forming method (Example 11).

  On the other hand, the ink sets of Comparative Example 1 and Comparative Example 2 do not include clear ink. Therefore, as shown in the evaluation results of Table 4, the recorded images were not excellent in abrasion resistance.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (6)

A white ink containing a white color material and a first resin;
A color ink containing a color material other than the white color material;
A clear ink containing substantially no color material and containing a second resin,
Wherein the first resin comprises a fluorene-based resins,
The second resin comprises at least hand of polyolefin wax and ethylene vinyl acetate resin, ink set. Oite to claim 1,
The ink set, wherein the content of the first resin in the white ink is 1% by mass or more and 7% by mass or less in terms of solid content. In claim 1 or 2 ,
The ink set in which the content of the second resin in the clear ink is 3% by mass or more and 10% by mass or less in terms of solid content. In any one of Claims 1 thru | or 3 ,
Provided in the droplet discharge device,
The white ink droplet and the clear ink droplet are ejected at substantially the same time, and the white ink droplet and the clear ink droplet are contacted and attached on the recording medium, An ink set for use in an image forming method in which droplets of the color ink are ejected and adhered onto the droplets of the white ink and the clear ink adhered to the recording medium. In any one of Claims 1 thru | or 3 ,
Provided in the droplet discharge device,
After ejecting the white ink droplets and attaching the white ink droplets to the recording medium, the droplets of the clear ink and the color ink are ejected at substantially the same time, An ink set for use in an image forming method in which the clear ink droplet and the color ink droplet are brought into contact with and adhered to the white ink droplet adhered to the recording medium. In any one of Claims 1 thru | or 5 ,
The ink set, wherein the polyolefin wax has an average particle size of 100 nm to 200 nm.