JP5962882B2 - Ink set and image recording method - Google Patents

Description

  The present invention relates to an ink set and an image recording method using the ink set.

  Conventionally, it is known that a desired image is formed by attaching ink to a recording medium using various recording methods. The ink used for forming such an image is prepared by adding various components according to its use. For example, Patent Document 1 describes an ultraviolet curable ink composition for overprinting used for protecting a printed layer. Patent Document 2 describes a conductor pattern ink used for forming a wiring pattern using an inkjet method.

  By the way, an image attached to a recording medium may be cracked depending on a component contained in ink, a recording method, or the like. In order to reduce such inconveniences, Patent Document 1 describes that various oligomers and monomers are added to the overcoat ink composition. Further, Patent Document 2 described above describes that a nonionic compound such as polyethylene glycol is added to the conductor pattern ink to reduce cracks in the conductor pattern.

JP 2008-12084 A JP 2007-194175 A

  However, as described in the aforementioned patent document, when a component for reducing image cracking is added to the ink composition, the abrasion resistance of the image may be lowered.

  In order to solve such a problem, for example, a component for improving the abrasion resistance of an image can be further added to the ink composition. However, depending on the component to be added, there are cases where it is not possible to simultaneously satisfy the improvement of the abrasion resistance of the image and the reduction of cracks in the image.

  In addition, when the content ratio of resin or the like in the ink is increased in order to improve the scratch resistance of the image and reduce cracks in the image, the components contained in the ink tend to aggregate, and the ejection stability of the ink jet recording apparatus is improved. In some cases, the sexiness decreased. In particular, in an ink containing a white pigment, there has been a problem that aggregation of the white ink tends to occur when the content ratio of the resin in the ink increases.

  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 first ink containing a white pigment and a first resin;
A second ink containing a color material other than the white pigment and a second resin,
The first resin includes a component (A) that 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 1 , cracks in an image formed by overlapping the first ink and the second ink can be reduced, and the formed image is excellent in abrasion resistance. In addition, when applied to an ink jet recording apparatus, a good image can be formed with excellent ejection stability.

[Application Example 2 ]
Oite in Application Example 1,
The content of the component (A) in the first ink may be 1% by mass or more and less than 7% by mass.

[Application Example 3 ]
Oite to application example 1 or 2,
The ratio (W2 / W1) between the content [W1] of the component (A) in the first ink and the content [W2] of the component (B) in the second ink is 0.25. It can be 1.5 or less.

[Application Example 4 ]
In any one of Application Examples 1 to 3 ,
The polyolefin wax may have an average particle size of 100 nm to 200 nm.

[Application Example 5 ]
In any one of Application Examples 1 to 4 ,
Furthermore, the first resin contains the component (B),
The content of the component (B) in the first ink can be 2% by mass or less.

[Application Example 6 ]
In any one of Application Examples 1 to 5 ,
The content of the first resin in the first ink may be 1% by mass or more and less than 6% by mass.

[Application Example 7 ]
One aspect of the image recording method according to the present invention is:
An image recording method using the ink set according to any one of Application Examples 1 to 6 ,
Discharging the first ink droplets to attach the first ink droplets to a recording medium;
Ejecting the second ink droplets to cause the second ink droplets to adhere onto the first ink droplets adhered to the recording medium.

According to the aspect described in Application Example 7 , it is possible to obtain an image with excellent image abrasion resistance and reduced cracking. In addition, the ink ejection stability is excellent.

  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 first ink and a second ink. Hereinafter, components included in each ink according to the present embodiment will be described in detail.

1.1. First ink The first ink according to this embodiment contains a white pigment and a first resin. The first ink is used as a so-called “white ink”. 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 of view 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 first ink will be described in detail.

1.1.1. White pigment The 1st ink which concerns on this embodiment contains a white pigment. Examples of white pigments include metal oxides, barium sulfate, and calcium carbonate. Examples of the metal oxide include titanium dioxide, zinc oxide, silica, alumina, and magnesium oxide. The white pigment 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 pigment contained in the first ink of the present embodiment, titanium dioxide is preferable from the viewpoint of whiteness and abrasion resistance.

  The content (solid content) of the white pigment is preferably 1% by mass to 20% by mass, and more preferably 5% by mass to 15% by mass with respect to the total mass of the first ink. When the content of the white pigment exceeds the above range, nozzle clogging of the ink jet recording apparatus may occur. On the other hand, when the content of the white pigment 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 pigment is preferably 30 nm or more and 600 nm or less, more preferably 200 nm or more and 400 nm or less. If the average particle diameter of the white pigment exceeds the above range, 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 average particle diameter of the white pigment is less than the above range, the whiteness tends to be insufficient.

  The average particle diameter of the white pigment 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 first ink according to the present embodiment contains a first resin. One function of the first resin is to fix the first ink to the recording medium. The content of the first resin is preferably 1% by mass or more and less than 7% by mass, more preferably 1% by mass or more and less than 6% by mass, and particularly preferably 3% by mass with respect to the total mass of the first ink. % Or more and less than 6% by mass. When the content of the first resin is within the above range, when the first ink is applied to the ink jet recording apparatus, the ejection stability of the first ink is improved. On the other hand, when the content of the first resin exceeds the above range, the white pigment tends to aggregate, and when the first 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 first ink to the recording medium may be insufficient. In addition, content of 1st resin is the quantity by solid content conversion.

  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. Component (A) is prepared by dropping 0.5 g of resin onto a slide glass (for example, MICRO SLIDE GLASS S-7213, manufactured by Matsunami Glass Industry Co., Ltd.) and drying for 10 minutes under conditions of a temperature of 50 ° C. and a humidity of 0% RH. It is a resin that cracks when generated.

  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 first ink to 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-based resin and the styrene acrylic resin can improve the abrasion resistance of the image formed by the first ink. However, particularly when the fluorene-based resin is blended in the first ink, the image resistance is further improved. Rubability can be improved.

  The content (solid content) of the component (A) is preferably 0.1% by mass or more and less than 7% by mass, more preferably 1% by mass or more and less than 7% by mass with respect to the total mass of the first ink. Yes, more preferably 1% by mass or more and less than 6% by mass, and particularly preferably 3% by mass or more and less than 6% by mass. When the content of the component (A) is within the above range, the ejection stability when the first ink is applied to the ink jet recording head is good, and the rub resistance and the fixability of the recorded image are good. Become. 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 ink jet recording head may be lowered. 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 resins may be used in addition to the component (A).

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

  In addition, when the first ink contains the component (B) described in “1.2.2. Second resin” below, the content of the component (B) in the first ink is 2% by mass or less. It is preferable that it is present (“2% by mass or less” includes 0% by mass). The content of the component (B) in the first 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. Is 0.1% by mass or less (including 0% by mass). By including the component (B) exhibiting an effect of preventing cracks and the like in the second ink as much as possible, the ejection stability of the first ink may be improved.

  From the viewpoint of ejection stability, the total amount of the first resin and the white pigment in the first ink is preferably 18% by mass or less, and 16% by mass or less in terms of solid content with respect to the total mass of the first ink. It is more preferable that it is 14 mass% or less.

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

  Examples of alkanediols include 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and the like can be mentioned. Among these, 1,2-alkanediols are excellent in the action of increasing the wettability of the ink with respect to the recording medium and uniformly wetting it, so that an excellent image can be formed on the recording medium. When the alkanediol is 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 first ink.

  Examples of polyhydric alcohols other than alkanediol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and glycerin. Polyhydric alcohols other than alkanediol are preferable from the viewpoint that when the first 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. Can be used. When polyhydric alcohols other than alkanediol are contained, the content thereof is preferably 2% by mass or more and 20% by mass or less with respect to the total mass of the first 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 thereof is preferably 0.1% by mass or more and 25% by mass or less with respect to the total mass of the first ink.

  The first 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. The silicon-based surfactant can be preferably used from the viewpoint of having an action of uniformly spreading the first ink on the 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 first 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 first ink.

  The first ink according to this 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 1st ink which concerns on this embodiment can contain a pH adjuster, antiseptic | preservative, antifungal agent, a rust preventive agent, a chelating agent etc. further. If the first 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 1st ink which concerns on this embodiment can be prepared similarly to the conventional pigment ink using a conventionally well-known apparatus, for example, a ball mill, a sand mill, an attritor, a basket mill, a roll mill etc. In the preparation, it is preferable to remove coarse particles using a membrane filter or a mesh filter.

1.2. Second Ink The second ink according to the present embodiment contains a color material other than the white pigment described above and a second resin. Hereinafter, the components contained in the second ink will be described in detail.

1.2.1. Color Material The second ink according to the present embodiment contains a color material other than the above-described white pigment (hereinafter also simply referred to as “color material”). Examples of the color material include dyes and pigments. The content of the coloring 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 second 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. Second Resin The second ink according to the present embodiment contains a second resin. One of the functions of the second resin is to fix the second ink to the recording medium. The content of the second resin is preferably 1% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 7% by mass or less with respect to the total mass of the second ink. If the content of the second resin exceeds the above range, when the second 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 second ink is often smaller than the particle diameter of the white pigment used for the first ink. For this reason, the second ink is less likely to cause aggregation of the coloring material, and even if it contains a larger amount of resin than the first ink, ejection failure is less likely to occur. In addition, content of 2nd resin is content of solid content conversion.

(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 above-described function of improving the fixability of the second ink. The second resin is a concept including one or more kinds of resins, and “included in the second resin”, “included in the second resin”, “included 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 first ink may be 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 the first ink, cracks may occur in the image. The detailed mechanism of cracking is not clear, but is considered to be due to abrupt shrinkage of the image accompanying the drying process of ink, aggregation of components contained in the first ink and the second ink, and the like.

  In such a case, if the (B) component is contained in the second ink, cracks in the image can be effectively suppressed by the action of the (B) component.

  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 2nd ink which concerns on this embodiment, it can add directly with 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 in the above range, it is possible to reduce the occurrence of cracks in the image formed by the first ink and the second ink and to improve the abrasion resistance. In particular, when a polyolefin wax having an average particle diameter of 100 nm or more and 200 nm or less is used, both the ejection stability of the ink jet recording head and the abrasion resistance of the image formed by the first ink and the second ink are obtained. Can meet high standards. 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 (Mitsui / DuPont Polychemical Co., Ltd.), Sumikaflex 201HQ, 520HQ, 410HQ (Made by Sumitomo Chemical Co., Ltd.), and the like.

  The content (solid content) of the component (B) is preferably 0.5% by mass or more and 8% by mass or less, more preferably 1% by mass or more and 6% by mass or less, with respect to the total mass of the second ink. is there. When the content of the component (B) is within the above range, cracks in an image formed using the first ink and the second ink can be effectively reduced. On the other hand, when the content of the polyolefin wax 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 the occurrence of cracks in an image formed using the first ink and the second ink may not be expected.

  In the ink set according to the present embodiment, the content [W1 (mass%)] of the component (A) in the first ink and the content [W2 (mass%)] of the component (B) in the second ink, The ratio (W2 / W1) is preferably 0.1 or more and 2 or less, more preferably 0.2 or more and 1.5 or less. When the content relationship between the component (A) and the component (B) is within the above range, the occurrence of cracks in the image recorded using the first ink and the second ink is reduced, and the image resistance is reduced. It also has excellent rubability.

(2) Other resins As the second resin, only the component (B) may be used, but other resins may be used in addition to the component (B).

  One of the functions of the other resin is to further improve the function of fixing the second ink to the recording medium and to improve the dispersibility of the white pigment in the first ink. . Examples of other resins include acrylic resins, urethane resins, polyolefin resins, rosin modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate. Known resins such as a copolymer can be used.

1.2.3. Other components The 2nd ink which concerns on this embodiment can contain components other than the above. The components that can be used for the second ink are the same as those described in “1.1.3. Other components”, and thus description thereof is omitted.

1.3. Physical Properties of First Ink and Second Ink When the ink set according to this embodiment is used in an inkjet recording apparatus, the viscosity at 20 ° C. of the first ink and the second ink (hereinafter also simply referred to as “ink”) is It is preferably 2 mPa · s or more and 10 mPa · s or less, and more preferably 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 Recording Method An image recording method according to an embodiment of the present invention is performed using the above-described ink set, and the first ink droplets are ejected and the first ink droplets are recorded on the recording medium. And a step of ejecting a second ink droplet to cause a second ink droplet to adhere to the first ink droplet adhered to the recording medium.

  The image recording method of the present embodiment can be performed using a conventionally known droplet discharge device. Examples of the droplet discharge device include an ink jet printer. Hereinafter, an image recording method using an ink jet printer will be described.

  First, the first ink droplets are ejected from the nozzles of the recording head of the ink jet printer, and the first ink droplets adhere to the recording medium. Since the first ink is a white ink containing a white pigment, the droplets of the first ink attached on the recording medium exhibit a white color. Thereby, the 1st ink functions as a foundation layer, and it can improve the color development nature of the 2nd ink made to adhere on the 1st ink.

  Next, the second ink droplets are ejected from the nozzles of the recording head, and the second ink is adhered onto the first ink droplets deposited on the recording medium. At this time, it is sufficient that at least a part of the first ink droplet and the second ink droplet are in contact with each other on the recording medium.

  By repeating the above operation, a desired image can be formed on the recording medium.

  Each of the first ink and the second ink includes the components described above. Therefore, according to the image recording method according to the present embodiment, the ejection stability is excellent, the crack of the recorded image is small, and the recorded image is excellent in abrasion resistance.

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 white ink and color ink Mixing and stirring colorant, resin, 1,2-hexanediol, 2-pyrrolidone, propylene glycol, polysiloxane surfactant and ion-exchanged water in the blending amounts shown in Tables 1 to 3 Then, the mixture was filtered with a metal filter having a pore diameter of 5 μm and deaerated using a vacuum pump to prepare white ink and color ink used for the following evaluation.

  In addition, all the units of the numerical values described in Tables 1 to 3 are mass%, and the titanium dioxide particles and the resin are values converted into solid contents.

  Specifically, the components shown in Tables 1 to 3 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)
・ 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 ingredients)
・ 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.

  For the cyan pigment, a pigment dispersion dispersed by the following method was used.

  First, after the inside of a 2000 ml separable flask equipped with a stirrer, a reflux tube, a temperature sensor, and a dropping funnel was sufficiently purged with nitrogen, 200.0 parts by mass of diethylene glycol monomethyl ether was placed in the separable flask and stirred. The temperature was raised to ° C. Next, 200.0 parts by mass of diethylene glycol monomethyl ether, 483.0 parts by mass of cyclohexyl acrylate (hereinafter referred to as “CHA”), 66.6 parts by mass of methacrylic acid (hereinafter referred to as “MAA”), acrylic acid in a dropping funnel 50.4 parts by mass (hereinafter referred to as “AA”) and 4.8 parts by mass of t-butylperoxy (2-ethylhexanoate) (hereinafter referred to as “BPEH”) were added, and the mixture was heated at 80 ° C. for 4 hours. And dropped into a separable flask. After completion of dropping, the mixture was held at 80 ° C. for 1 hour, 0.8 parts by mass of BPEH was added, and the reaction was further performed at 80 ° C. for 1 hour. After completing the aging, diethylene glycol monomethyl ether was removed by distillation under reduced pressure. Thereafter, 600.0 parts by mass of methyl ethyl ketone (hereinafter referred to as “MEK”) was added to obtain a polymer composition solution for inkjet ink having a resin solid content of 50%.

  A portion of the thus obtained ink-jet ink polymer composition solution was taken and dried for 1 hour in a high-temperature dryer at 105 ° C., and then the solid acid value of the ink-jet ink polymer composition obtained was It was 130 mgKOH / g, and the mass average molecular weight was 34000.

  Next, 6.0 parts by mass of a 30% aqueous sodium hydroxide solution is added to 120.0 parts by mass of the polymer composition solution for inkjet ink, and the mixture is stirred with a high-speed disper for 5 minutes. I. 480.0 parts by mass of the dispersion containing CI Pigment Blue 15: 3 was added and stirred with a high-speed disper for 1 hour to obtain a pigment dispersion.

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 inks and color inks listed in Tables 1 to 3 were filled in ink cartridges exclusively for inkjet printers (product name “PX-G930” manufactured by Seiko Epson Corporation), respectively, and Examples and Comparative Examples An ink set consisting of white ink and color ink was obtained for each time. 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, the ejection stability of each ink was evaluated by visually observing nozzle omission and flight bending. The evaluation criteria are as follows. If the evaluation is C or higher, it can be determined that the ejection stability has a level that does not cause a problem in practical use. The evaluation of ejection stability is evaluation of ejection stability of white ink.
A: No missing nozzle and no flying curve B: No missing nozzle, but flying curve C: Nozzle missing is recognized in less than 10 nozzles D: Nozzle missing is recognized in 10 nozzles or more Be

3.4. Rubbing resistance evaluation test (1) Preparation of a rubbing resistance evaluation sample Using the above printer, a solid pattern image was printed on an A4 size recording medium (Lumirror (R) S10-100 μm, manufactured by Toray Industries, Inc.). Was printed and dried.

  Specifically, first, a white solid pattern image was formed by depositing only white ink on the recording medium under the conditions of resolution 1440 × 720 dpi and 100% duty. Next, only a color ink was adhered on the white solid pattern image under the conditions of resolution 1440 × 720 dpi and 100% duty to form a cyan solid pattern image. Then, the obtained image was dried by a heater provided in the printer. In this way, a sample for evaluating abrasion resistance was obtained in which a cyan solid pattern image was printed on a white solid pattern image.

  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) 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 using a Gakushin friction fastness tester AB-301 (manufactured by Tester Sangyo Co., Ltd.). , Under a condition where the number of frictions was 10 times, the friction element 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. When the evaluation is C or higher, it can be determined that the film has sufficient abrasion resistance that is practically acceptable.
A: No peeling of image and little transfer of color to white cotton cloth for friction B: No peeling of image, but much transfer of color to white cotton cloth for friction C: Part of image peels off (Less than 10% of printed area)
D: The image is peeled off (more than 10% of the area where the image is printed)

3.5. Crack crack test (1) Preparation of crack crack evaluation sample Using the printer described above, printing and drying of images on an A4-sized recording medium (Lumirror (R) S10-100 μm, manufactured by Toray Industries, Inc.) went.

  Specifically, first, a white solid pattern image was formed by depositing only white ink on the recording medium under the conditions of resolution 1440 × 720 dpi and 100% duty. A color image (cyan image) was formed on the white solid pattern image by attaching only color ink under the conditions of resolution 1440 × 720 dpi and 30% to 100% duty. Next, the obtained image was dried by a heater provided in the printer. In this way, a sample for evaluating abrasion resistance was obtained in which a cyan image was printed for each duty on a white solid pattern image.

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

(2) Crack crack evaluation After the obtained sample for crack crack evaluation was dried for 10 minutes in a thermostatic bath at 50 ° C, the image surface was visually determined. The evaluation criteria are as follows. If the evaluation is C or higher, 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 at 100% duty B: No cracking of the image up to 80% duty C: No cracking of the image up to 50% duty D: Cracking of the image even at 30% duty

3.6. Evaluation results The above evaluation results are also shown in Tables 1 to 3. In the table, W1 represents the total content ratio (% by mass) of the fluorene resin and the styrene acrylic resin in the white ink. W2 represents the total content (% by mass) of the polyethylene waxes A to C and the ethylene vinyl acetate resin in the color ink.

  As shown in the evaluation test results of Tables 1 and 2, according to the ink sets of Examples 1 to 12, images with reduced cracking and excellent abrasion resistance were recorded, and ejection stability was achieved. Was also good.

  On the other hand, in the ink set of Comparative Example 1, the color ink contains neither polyethylene wax nor ethylene vinyl acetate resin. For this reason, as shown in the evaluation test results in Table 3, cracks occurred in the image even under low duty conditions.

  In the ink set of Comparative Example 2, the white ink contains neither a fluorene resin nor a styrene acrylic resin. Therefore, as shown in the evaluation results in Table 3, an image having poor abrasion resistance was recorded.

  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 (7)

A first ink containing a white pigment and a first resin;
A second ink containing a color material other than the white pigment and a second resin,
Wherein the first resin comprises a fluorene-based resins (A) component, and
The second resin is an ink set including a component (B) which is at least one of a polyolefin wax and an ethylene vinyl acetate resin. In claim 1,
The ink set, wherein the content of the component (A) in the first ink is 1% by mass or more and less than 7% by mass. In claim 1 or claim 2,
The ratio (W2 / W1) between the content [W1] of the component (A) in the first ink and the content [W2] of the component (B) in the second ink is 0.25. An ink set that is 1.5 or more. In any one of Claims 1 thru | or 3,
The ink set, wherein the polyolefin wax has an average particle size of 100 nm to 200 nm. In any one of Claims 1 thru | or 4,
Furthermore, the first resin contains the component (B),
The ink set, wherein the content of the component (B) in the first ink is 2% by mass or less. In any one of Claims 1 thru | or 5,
The ink set, wherein the content of the first resin in the first ink is 1% by mass or more and less than 6% by mass. An image recording method using the ink set according to any one of claims 1 to 6,
Discharging the first ink droplets to attach the first ink droplets to a recording medium;
Discharging the second ink droplets, and depositing the second ink droplets on the first ink droplets deposited on the recording medium.