インクジェットインク組成物、及び記録方法

Abstract

貯蔵安定性、発色性、耐転写性、耐擦性、目詰まり回復性及び気泡排出性に優れたインクジェットインク組成物を提供する。【解決手段】生物油由来カーボンブラックである顔料と、バインダー樹脂と、溶媒と、を含み、顔料は、自己分散顔料であり、バインダー樹脂は、自己乳化型樹脂を含み、溶媒は、水を含み、水系インクである、インクジェットインク組成物。

Description

[Technical Field]

[0001] The present invention relates to an inkjet ink composition and a recording method. [Background technology]

[0002] Inkjet recording methods enable the recording of high-resolution images with relatively simple equipment and are undergoing rapid development in various fields. For example, Patent Document 1 aims to provide an aqueous inkjet ink composition that is excellent in environmental compatibility and storage stability, and includes a bio-derived colorant, a bio-derived dispersant, and a bio-derived organic solvent, wherein the organic solvent has a solubility parameter of 24.0 (cal / cm³) based on the Hansen method. 3 ) 1 / 2 Thus, an aqueous inkjet ink composition containing a compound having a hydroxyl group is disclosed. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-128719 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In water-based inkjet inks containing pigments, there is a desire to improve performance in terms of clogging recovery, color development, and transfer suppression. [Means for solving the problem]

[0005] The inkjet ink composition of the present invention contains a pigment which is bio-oil-derived carbon black, a binder resin, and a solvent, wherein the pigment is a self-dispersing pigment, the binder resin is a self-emulsifying resin, and the solvent is water, making it an aqueous ink.

[0006] The recording method of the present invention includes an adhesion step of ejecting ink using the above-mentioned inkjet ink composition from an inkjet head and adhering it to a recording medium. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a recording device used in the recording method of this embodiment. [Figure 2] Table 1 shows the monomer composition of the self-emulsifying resin used in the examples. [Figure 3] Table 2 shows the composition of each composition used in the examples and the evaluation results thereof. [Figure 4] Table 3 shows the composition of each composition used in the examples and the evaluation results thereof. [Figure 5] Table 4 shows the composition of each composition used in the examples and the evaluation results thereof. [Modes for carrying out the invention]

[0008] The present invention will be described in detail below, with reference to the drawings as necessary. However, the present invention is not limited thereto, and various modifications are possible without departing from its essence. In the drawings, the same elements will be denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Moreover, the dimensional ratios in the drawings are not limited to those shown.

[0009] 1. Inkjet ink composition The inkjet ink composition according to this embodiment comprises a pigment which is bio-oil-derived carbon black, a binder resin, and a solvent, wherein the pigment is a self-dispersing pigment, the binder resin is a self-emulsifying resin, and the solvent is water, making it an aqueous ink.

[0010] By using color materials derived from natural products such as carbon black derived from bio-oil (hereinafter also referred to as "bio-oil CB") in ink, efforts are being made to reduce components derived from petroleum and the CO2 emissions caused by components derived from petroleum, with an environmentally considerate ink. "CB" means carbon black.

[0011] In a resin-dispersed pigment in which a pigment such as carbon black is dispersed using a dispersant resin, if the adhesion or adsorption between the dispersant resin and the pigment is insufficient, it may be difficult to obtain dispersion stability. Also, during storage, the dispersant resin may be released from the pigment, or the released dispersant resin may be foreignized. By using a self-dispersing pigment that does not require a dispersant resin, it is possible to prevent a decrease in storage stability and the foreignization of the dispersant resin. However, when using a self-dispersing pigment, the abrasion resistance of the ink on the recording medium may be insufficient, or the ink adhering to another medium may be easily transferred to another.

[0012] Therefore, in the present embodiment, in addition to bio-oil CB which is a self-dispersing pigment, a self-emulsifying resin is used in combination. Since bio-oil CB tends to have a higher content of oxygen atoms contained as unburned components compared to carbon black derived from petroleum, more oxygen-containing functional groups are easily introduced by surface treatment. Therefore, bio-oil CB as a self-dispersing pigment has particularly high dispersion stability and high wettability of the pigment surface, resulting in an ink that is particularly excellent in storage stability, clogging recovery property, and air bubble discharge property. Also, since the reactivity with metal salts such as calcium salts contained in the recording medium is high, it becomes an ink with excellent color development property. Furthermore, the self-emulsifying resin has many hydrophilic functional groups on the surface and has a high affinity with bio-oil CB which is a self-dispersing pigment having many hydrophilic functional groups on the surface as well. Therefore, it becomes an ink with excellent abrasion resistance and is difficult to transfer, that is, excellent in transfer resistance.

[0013] Hereinafter, in the ink composition according to the present embodiment, the components that can be contained and the manufacturing method will be described in detail.

[0014] 1.1. Pigment The ink composition in this embodiment contains a pigment that is a bio-oil CB. By using bio-oil CB derived from natural products, petroleum-derived components can be reduced, CO2 emissions from petroleum-derived components can be reduced, and an environmentally friendly ink can be produced.

[0015] biological oil CB The pigment of this embodiment contains bio-oil CB. Bio-oil CB is CB derived from bio-oil. It is obtained by carbonizing bio-oil. Biological oils are oils derived from living organisms such as plants, animals, and microorganisms, rather than oils derived from underground resources such as petroleum. This includes oils made from living organisms, as well as oils extracted or produced from living organisms. Biological oils are also called biomass oils or biomass-derived oils. Biological oil CB is also called biomass oil-derived CB.

[0016] By using carbon black derived from biomass oil, the amount of petroleum-derived components in the ink can be reduced. This reduces carbon dioxide emissions compared to using petroleum-derived components, resulting in an environmentally friendly ink. Biological oil carbon black (CB) is produced by carbonizing biological oils. Its manufacturing process is similar to that of petroleum-derived carbon black, as it involves burning a liquid to produce carbon black, making it relatively easy to produce. Because impurities can be relatively easily reduced by refining the liquid raw material, the adhesion and retention of impurities in the carbon black can be suppressed, further improving its storage stability.

[0017] While there are no particular limitations on the method for producing biological oil carbon black (CB), known methods such as the furnace method, channel method, and lamp method can be used. Furthermore, in the process of preparing raw materials for biological oil or its modified products, it is possible to control the structure and primary particles of carbon black by adding alkaline agents such as potassium hydroxide or sodium hydroxide, in addition to conditions such as heating temperature and sample amount. Examples of bio-oils used as raw materials for bio-oil CB include animal oils, vegetable oils, and microbial oils. Examples of animal oils, though not limited to them, include beef tallow, horse oil, and fish oil. Examples of microbial oils, though not limited to them, include algal oil.

[0018] Among biological oils (CBs), vegetable oil CBs, which use vegetable oils as raw materials, are preferable because relatively homogeneous vegetable oils are readily available in relatively large quantities, the vegetable oils used as raw materials are easy to handle, and they are easy to store. The raw materials for vegetable oil CB are not particularly limited, but include plant seed oil, tall oil, or wood tar, or modified products such as hydrogenated plant seed oil, tall oil, or wood tar, or their derivatives. A modified product is a vegetable oil modified to the extent that the effects of this embodiment can be obtained.

[0019] The primary particle size of the biological oil CB is preferably 80 nm or less. More preferably, it is 5 to 70 nm, 15 to 55 nm, 20 to 45 nm, or 25 to 35 nm. When the primary particle size is within the above range, storage stability, transfer resistance, color development, clogging recovery, and bubble discharge tend to be improved. The primary particle size of carbon black can be determined by observing the carbon black particles with an electron microscope and calculating the arithmetic mean diameter. Primary particles are the smallest units of carbon black. They are often the smallest particles produced during the carbonization process. Secondary particles are aggregates formed when multiple primary particles come together and aggregate. In ink compositions, carbon black is often dispersed in the form of secondary particles.

[0020] The DBP absorption rate of biological oil CB is preferably 250 mL / 100g or less, or 30 mL / 100g or more. More preferably, it is 50-200 mL / 100g, 80-170 mL / 100g, 80-150 mL / 100g, or 90-130 mL / 100g. When the DBP oil supply is within the above range, storage stability, transfer resistance, color development, clogging recovery, and bubble discharge tend to be improved.

[0021] DBP oil absorption is expressed as the amount of dibutyl phthalate (DBP) absorbed by 100g of carbon black, and can be determined according to the measurement method specified in JIS K6221. Generally, the more developed the secondary particle structure of carbon black, the greater the DBP oil absorption.

[0022] The content of biological oil CB is preferably 0.1 to 15% by mass, 1 to 12% by mass, 2 to 9% by mass, and 3 to 7% by mass, relative to the total amount of the ink composition. When the pigment content is within the above range, storage stability, color development, clogging recovery, and bubble discharge tend to be further improved.

[0023] 1.1.2. Self-dispersing pigments Pigments can be categorized into resin-dispersed pigments, which are dispersed by resins, and self-dispersing pigments, which disperse on their own without the need for a dispersant. The resin used to disperse resin-dispersed pigments also acts as a dispersant. When resin-dispersed pigments are dispersed using a resin dispersant, if the adhesion or adsorption between the dispersant resin and the pigment is insufficient, dispersion stability is difficult to obtain, and there is a possibility that the dispersant resin may detach from the pigment during storage, or that the detached dispersant resin may become a foreign substance. In this embodiment, the ink composition uses a self-dispersing pigment, which prevents a decrease in storage stability and the decomposition of the dispersant resin into a foreign substance. Furthermore, since bio-oil carbon black (CB) tends to have a higher content of oxygen atoms as unburned components compared to petroleum-derived carbon black, more oxygen-containing functional groups are easily introduced through surface treatment. This tendency is particularly strong in vegetable oil CB. Therefore, bio-oil CB, especially vegetable oil CB, used as a self-dispersing pigment, exhibits particularly high dispersion stability and high wettability on the pigment surface, resulting in an ink with excellent storage stability, clogging recovery, and bubble discharge properties. Furthermore, its reactivity with metal salts such as calcium salts contained in the recording medium is particularly high, resulting in an ink with excellent color development.

[0024] The method for producing self-dispersing pigments is not particularly limited, but one example is a method of introducing hydrophilic functional groups to the pigment surface by performing physical and / or chemical surface treatments. Examples of such physical treatments include vacuum plasma treatment. Examples of chemical treatments include oxidation with an oxidizing agent.

[0025] When using bio-oil CB as a self-dispersing pigment, the oxygen atoms contained in the bio-oil CB facilitate the introduction of hydrophilic functional groups into the pigment, which is preferable. Because the oxygen atoms in the bio-oil CB facilitate the introduction of hydrophilic functional groups into the pigment, these are hydrophilic functional groups containing oxygen atoms. The proportion of introduced hydrophilic functional groups may be adjusted by controlling the degree of oxidation treatment. Another method involves introducing hydrophilic functional groups to the pigment surface by chemically bonding a compound having hydrophilic functional groups to the pigment surface. In this case as well, the oxygen atoms contained in the pigment contribute to the chemical reaction with the compound having hydrophilic functional groups, making it preferable for the hydrophilic functional groups to be easily introduced into the pigment. Alternatively, the hydrophilic functional groups introduced into the pigment by the above oxidation treatment may be reacted with a compound having the above-mentioned hydrophilic functional groups by a chemical reaction.

[0026] Examples of hydrophilic functional groups include ionic groups. Ionic groups include acidic groups and basic groups. Such ionic groups are not particularly limited, but examples include carboxyl groups, amino groups, sulfo groups, and phosphorus-containing acid groups. In particular, anionic groups such as carboxyl groups, sulfo groups, and phosphorus-containing acid groups are preferred. Hydroxyl groups can also be cited as hydrophilic functional groups; however, for use as hydrophilic functional groups in self-dispersing pigments, the hydrophilic functional groups other than hydroxyl groups mentioned above are preferable because they allow for stable dispersion of the pigment.

[0027] Among these, self-dispersing pigments that have been surface-treated by oxidation are preferred. Using such self-dispersing pigments tends to improve storage stability, color development, clogging recovery, and bubble discharge. Examples of oxidation treatments include oxidation with hypohalous acid or hypohalite salts, oxidation with ozone, and oxidation with persulfuric acid or persulfates. Specific examples of oxidizing agents are not limited to these, but include sodium hypochlorite.

[0028] Biological oil-based CBs often contain complex impurities due to the raw materials, and their structure can also be complex. This complexity in impurities and structure can sometimes lead to relatively poor storage and dispersion stability. This tendency is particularly pronounced with vegetable oil-based CBs. Even in such cases, using self-dispersing pigments is preferable because it allows for the introduction of more hydrophilic functional groups, resulting in improved storage and dispersion stability. Furthermore, vegetable oil CB is particularly preferable because it contains many oxygen atoms in the pigment, making it easy to introduce hydrophilic functional groups, and thus easily achieves the effects of the present invention.

[0029] The term "structure" refers to the connections and size of carbon black particles, including how they aggregate, what shape and arrangement they take, and, for example, the state of secondary particles formed by the aggregation of primary particles.

[0030] 1.2. Binder Resin The ink composition in this embodiment includes a self-emulsifying resin as a binder resin. Because the self-emulsifying resin is reversible in terms of dissolution and dispersion, it does not become a foreign substance or cause clogging even when the ink dries, thereby improving the storage stability, clogging recovery, and bubble discharge properties of the ink composition. Furthermore, the self-emulsifying resin has many hydrophilic functional groups on its surface and has a high affinity for bio-oil CB, a self-dispersing pigment that also has many hydrophilic functional groups on its surface. Therefore, the resulting ink has excellent abrasion resistance and transfer resistance.

[0031] 1.2.1. Self-emulsifying resin Self-emulsifying resins have a high water concentration in the ink and are dispersed by self-emulsification. However, when water evaporates at the nozzle or other points, the concentration of organic solvent increases, causing the resin to dissolve. Then, when new ink is supplied and the water concentration increases again, the resin can self-emulsify and redisperse.

[0032] The monomers constituting the self-emulsifying resin are not particularly limited, but for example, hydrophobic monomers and hydrophilic monomers can be used. The hydrophobic monomers are not particularly limited, but for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isopropyl Examples include alkyl(meth)acrylates such as my(meth)acrylate, isooctyl(meth)acrylate, isodecyl(meth)acrylate, isododecyl(meth)acrylate, isobornyl(meth)acrylate, isostearyl(meth)acrylate, and dicyclopentanyl(meth)acrylate; and aromatic group-containing monomers such as styrene, α-methylstyrene, 2-methylstyrene, vinyltoluene, divinylbenzene, chlorostyrene, phenyl(meth)acrylate, benzyl(meth)acrylate, and phenoxyethyl(meth)acrylate.

[0033] The hydrophilic monomers are not particularly limited, but include, for example, unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid; unsaturated sulfonic acid monomers such as styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropyl (meth)acrylate; unsaturated phosphate monomers such as vinyl phosphonic acid, vinyl phosphate, bis(methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, and diphenyl-2-methacryloyloxyethyl phosphate; cyclic trimethylolpropaneformal (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and (2-methyl-2-ethyl-1,3-diole Examples of ionic monomers include ether-containing monomers such as xolan-4-yl)methyl acrylate; unsaturated tertiary amine-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, N,N-dimethylarylamine, vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-6-vinylpyridine, and 5-ethyl-2-vinylpyridine; and unsaturated ammonium salt-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate quaternary, N,N-diethylaminoethyl (meth)acrylate quaternary, and N,N-dimethylaminopropyl (meth)acrylate quaternary.

[0034] The self-emulsifying resin may be a homopolymer of the above-mentioned hydrophilic monomer, hydrophobic monomer, etc., or a copolymer. The copolymer may be a random copolymer or a block copolymer, but the self-emulsifying resin in this embodiment is preferably a block copolymer. When the self-emulsifying resin is a block copolymer, by making the hydrophilicity of each block different, the self-emulsifying resin can take on a polymer micelle structure, thereby further improving solubility and redispersibility. Therefore, the storage stability, clogging recovery, and bubble discharge properties of the ink composition tend to be further improved.

[0035] The block copolymer is not particularly limited, but may be a diblock copolymer, a triblock copolymer, or even have more than one block. Furthermore, the block may be composed of a single monomer or of two or more monomers. In the case of a block containing two or more monomers, the two or more monomers may be arranged randomly. A block copolymer is a polymer in which the polymer chain is composed of multiple blocks, but there are two or more types of blocks in the molecular chain. Diblock copolymers consisting of two types of blocks are particularly preferred. When there are two types of blocks, the two types of blocks are also called A block and B block. AB block copolymers, in which the molecular chain consists of one A block and one B block, are preferred. In this case, the storage stability and clogging recovery properties of the ink composition are better and therefore preferred.

[0036] Among these, the self-emulsifying resin is preferably an acrylic block copolymer. Using an acrylic block copolymer tends to further improve storage stability, clogging recovery, and bubble discharge. The acrylic block copolymer is not particularly limited as long as it contains at least an acrylic monomer as a component. The acrylic monomer is a monomer having a (meth)acryloyl group, such as (meth)acrylic acid, (meth)acrylate, and (meth)acrylamide. The composition ratio of acrylic monomer to the constituent components of the acrylic block copolymer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Furthermore, 98% by mass or more is preferred, and it may even be 100% by mass. Since there is a wide variety of acrylic monomers, when the composition ratio of acrylic monomer is above the above range, it is preferable to have a high degree of design freedom, such as being able to easily set the glass transition point and acid value to the desired range.

[0037] The self-emulsifying resin binder is preferably a block copolymer consisting of an A block and a B block with a higher acid value than the A block. Examples of such AB block copolymers include those having a highly hydrophobic A block and a B block with a higher hydrophilicity than the A block. This makes it easier for the self-emulsifying resin binder to adopt a micelle structure in which the hydrophobic block faces the center and the hydrophilic block faces the outside. This makes self-dispersion easier in solvents with a relatively high water content, such as water. On the other hand, in solvents with a high organic solvent content, it does not adopt a micelle structure and dissolves easily in the solvent. In this way, it can easily change its form, such as dissolving and self-dispersing, depending on the environment. The self-emulsifying resin binder is preferably soluble in a composition consisting solely of organic solvents that make up the composition of the organic solvent contained in the ink. Because it has a hydrophilic portion, in environments with relatively high water content solvents, its redispersibility in water is improved, and its clogging recovery and storage stability tend to be further enhanced. Furthermore, because it has a hydrophobic portion, it has excellent solubility in organic solvents, so in environments with high organic solvent content solvents, its solubility is improved, and its clogging recovery and redispersibility tend to be further enhanced. Furthermore, because Block B has a concentration of highly hydrophilic structures, it has a high affinity with bio-oil CB, which has many hydrophilic functional groups. This allows for strong adhesion between Curb Black and the binder resin, enabling the formation of an ink coating film with excellent abrasion resistance and transfer suppression.

[0038] In this embodiment, the acid value can be calculated from the proportion of monomers containing acidic groups among the monomers in the block.

[0039] The monomers constituting block B may include monomers having an acidic group, as well as monomers without an acidic group, if necessary. Similarly, the monomers constituting block A may include monomers having an acidic group, as long as the acid value does not exceed that of block B, in addition to monomers without an acidic group.

[0040] Examples of monomers having an acidic group include unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid, which are among the hydrophilic monomers mentioned above; unsaturated sulfonic acid monomers such as styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropyl (meth)acrylate; and unsaturated phosphoric acid monomers such as vinylphosphonic acid, vinyl phosphate, bis(methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, and diphenyl-2-methacryloyloxyethyl phosphate.

[0041] Furthermore, while there are no particular limitations on monomers that do not have an acidic group, other monomers such as hydrophobic monomers can be mentioned.

[0042] The content of monomers having acidic groups in block B is preferably 1 to 50% by mass, 5 to 40% by mass, 10 to 30% by mass, and 15 to 25% by mass, relative to the total amount of monomers in block B. When the content of monomers having acidic groups in block B is within the above range, the abrasion resistance, clogging recovery, and redispersibility tend to be further improved.

[0043] In this embodiment, the block polymer consisting of block A and block B, which has a higher acid value than block A, is preferably a block polymer A having two or more hydrophobic monomers and a block copolymer B having one or more hydrophobic monomers and one or more hydrophilic monomers. The hydrophobic monomers contained in block A and block B may be the same.

[0044] The glass dislocation point of a self-emulsifying resin binder is preferably 110°C or lower, or preferably 5°C or higher, more preferably 10 to 100°C. Furthermore, it is preferably 30°C or higher, more preferably 50°C or higher, and even more preferably 70°C or higher. Alternatively, it is preferably 80°C or lower, more preferably 60°C or lower, even more preferably 50°C or lower, even more preferably 30°C or lower, and particularly preferably 20°C or lower. When the glass dislocation point is above the above range, storage stability and bubble discharge properties are better, which is preferable. When the glass dislocation point is below the above range, anti-glare properties and clogging recovery properties are better, which is preferable. The glass dislocation point is the glass dislocation point of the entire self-emulsifying resin binder, and in the case of block copolymers, it is the weighted average of each block. The glass dislocation point can be measured by the DSC method.

[0045] Methods for obtaining block copolymers are not particularly limited, but include, for example, free radical polymerization and living radical polymerization. Among these, living radical polymerization is preferred in order to obtain a precise copolymer structure. Living radical polymerization is not particularly limited, but includes, for example, the NMP method using nitroxides, the ATRP method utilizing the redox reaction of metal complexes, the RAFT method using dithiocarboxylic acid esters, methods using cobalt catalysts, the TERP method using tellurium compounds, iodine transfer polymerization using iodine, and the RTCP method using iodide as an initiator and an organic compound as a catalyst.

[0046] The initiator is not particularly limited as long as it is a known initiator used in radical polymerization, but examples include azo compounds such as azobis(isobutyronitrile) and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); and peroxides such as benzoyl peroxide and dicumyl peroxide.

[0047] The content of the self-emulsifying resin is preferably 0.1 to 10% by mass, 0.5 to 5% by mass, and 1 to 3% by mass, relative to the total amount of the ink composition. When the binder resin content is within the above range, storage stability, color development, transfer resistance, abrasion resistance, and bubble discharge tend to be further improved.

[0048] 1.3. solvent The ink composition in this embodiment contains a solvent. The solvent is a liquid component that disperses or dissolves pigments, binder resins, etc. The solvent contains at least water and may also contain organic solvents. When simply referred to as "solvent," it means the solvent itself.

[0049] 1.3.1. Organic Solvents The ink composition in this embodiment may contain an organic solvent as a solvent. Preferably, the organic solvent has an octanol / water partition coefficient logP ow The ink composition contains an organic solvent A with a value of 0 to 1. When the ink composition contains organic solvent A, as the ink dries and the organic component content becomes dominant, the binder resin becomes more easily soluble in the ink, tending to improve storage stability and clogging recovery. Furthermore, during the drying process on the recording medium, the binder resin and the self-dispersing pigment, vegetable oil CB, bond more easily in the organic solvent A, tending to improve abrasion resistance. The ink composition in this embodiment may contain logP as needed. ow It may contain organic solvent B with a value other than 0 to 1. Organic solvent B is an organic solvent other than organic solvent A. Octanol / water partition coefficient logP ow The values ​​can be expressed as the octanol / water partition coefficient or logP ow It is also called a value, etc.

[0050] The octanol / water partition coefficient logP of organic solvent A ow The value is preferably 0.1 to 1, 0.2 to 0.9, 0.3 to 0.8, 0.4 to 0.7, or 0.5 to 0.6. logP ow When the value is 0 or more, the solubility of the binder resin becomes higher. logP ow When the value is 1 or less, the compatibility with water tends to be more excellent. Therefore, logP ow When the value is within the above range, the storage stability, rubbing resistance, and clogging recovery property of the ink composition tend to be further improved.

[0051] In this embodiment, the octanol / water partition coefficient logP ow The value refers to the value defined in OECD Test Guideline 107. The octanol / water partition coefficient is logP ow or logK ow and is expressed as such. logP ow A higher value indicates higher hydrophobicity, and a lower value indicates higher hydrophilicity.

[0052] The logP of the compound ow The value can be determined by various methods. For example, it can be determined by measuring according to the measurement method specified in JIS Z 7260-117. It can also be calculated using Hansen solubility parameter software (HSPIP).

[0053]

[0054] ​Examples of monoalcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, 2-butanol, tert-butanol, isobutanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0055] Polyols are organic solvents that have two or more hydroxyl groups. Examples include glycols, which have two hydroxyl groups, and polyols, which have three or more hydroxyl groups. Glycerin is an example of a polyol with three or more hydroxyl groups. Examples of glycols include alkanediols and condensates of alkanediols in which the hydroxyl groups between molecules are condensed. Alkanediols are alkanes in which two hydroxyl groups are substituted for each other. Examples of condensates of alkanediols in which the hydroxyl groups between molecules are condensed include condensates of diols of alkanes having 2 to 4 carbon atoms in which the hydroxyl groups between molecules are condensed. Alkanediols preferably have 2 or more carbon atoms, 4 or more, and more preferably 5 to 8. 1,2-Alkanediols are also preferred.

[0056] Examples of glycols include ethylene glycol, propylene glycol, alkanediols such as ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol; and condensates of alkanediols such as tetramethylene glycol, hexamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and (poly)tetramethylene glycol, which have a structure in which the hydroxyl groups between molecules are condensed.

[0057] Examples of ethers include alkyl ethers and glycol ethers, although they are not particularly limited. Examples of alkyl ethers include dimethyl ether, methyl ethyl ether, diethyl ether, isopropyl methyl ether, and isopropyl ethyl ether.

[0058] Examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monomethyl ether. Examples include alkylene glycol monoalkyl ethers such as tripropylene glycol monobutyl ether; and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0059] Examples of ketones include acetone, methyl ethyl ketone, and diethyl ketone. Examples of amides include lactam compounds and other amides. Examples of lactam compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-hydroxyethylpyrrolidone (HEP).

[0060] Organic solvent A is one of the organic solvents mentioned above, with an octanol / water partition coefficient logP. ow The value is between 0 and 1. Examples of such organic solvents A include isopropyl methyl ether, diethylene glycol monobutyl ether, triethylene glycol glycol monobutyl ether, 1,2-hexanediol methyl ethyl ketone, isopropyl alcohol, and methyl ethyl ketone.

[0061] The content of organic solvent A is preferably 0.5 to 15% by mass, 3 to 12% by mass, 5 to 10% by mass, and 6 to 8% by mass, relative to the total amount of the ink composition. When the content of organic solvent A is within the above range, storage stability, abrasion resistance, and clogging recovery tend to be improved.

[0062] Organic solvent B may be any of the organic solvents mentioned above, but the octanol / water partition coefficient logP ow Those whose value is less than 0. The content of organic solvent B is preferably 0.5 to 20% by mass, 1 to 15% by mass, 3 to 11% by mass, 5 to 9% by mass, and 6 to 8% by mass, relative to the total amount of the ink composition. When the content of organic solvent B is within the above range, storage stability, abrasion resistance, and clogging recovery tend to be improved.

[0063] When organic solvents A and B are included, the total content of the included organic solvents is preferably 0.5 to 30% by mass, 10 to 20% by mass, 11 to 18% by mass, 12 to 17% by mass, and 13 to 15% by mass, relative to the total amount of the ink composition. Having the organic solvent content within the above range tends to improve storage stability, scratch resistance, and clogging recovery.

[0064] 1.4. Moisturizers The ink composition in this embodiment may contain a humectant. Examples of humectants include liquid humectants and solid humectants. Liquid humectants are compounds that are liquid at room temperature and may be organic solvents, but they should have particularly excellent moisturizing properties. Examples include organic solvents with a standard boiling point above 280°C, and especially polyol organic solvents with a standard boiling point above 280°C. Glycerin is an example. Room temperature is defined as 25°C. Solid humectants are solid at room temperature and are not particularly limited as long as they have a humectant function that is solid at room temperature. Examples include polyols such as mesoerythritol, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol; glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, etc.; sugars such as monosaccharides, disaccharides, oligosaccharides, and polysaccharides; derivatives of these sugars; and betaines such as trimethylglycine, triethylglycine, γ-butyrobetaine, fomarin, trigonelline, carnitine, homoserine betaine, valine betaine, lysine betaine, ornithine betaine, alanine betaine, stachydrine, and glutamate betaine. Moisturizers may be used individually or in combination of two or more types.

[0065] In particular, the ink composition in this embodiment preferably contains betaine as a solid humectant. Betaine has positive and negative charges at non-adjacent positions within the same molecule, and the positively charged atoms do not have dissociable hydrogen atoms bonded to them, allowing them to form an intramolecular salt, and the molecule as a whole is a compound with no charge. By including betaine, flight deviations and non-ejection of the inkjet ink composition caused by drying of the inkjet head nozzles can be further suppressed, and clogging recovery and bubble discharge tend to be further improved.

[0066] The betaine content is preferably 0.1 to 10% by mass, 2 to 8% by mass, 3 to 7% by mass, and 4 to 6% by mass, relative to the total amount of the ink composition. When the betaine content is within the above range, the clogging recovery and bubble discharge properties tend to be further improved.

[0067] The humectant content is preferably 1 to 30% by mass, 10 to 20% by mass, and 13 to 17% by mass, relative to the total amount of the ink composition. When the humectant content is within the above range, the clogging recovery and bubble discharge properties tend to be further improved.

[0068] 1.5. Surfactants The ink composition in this embodiment may contain a surfactant. The surfactant is not particularly limited, but examples include silicone-based surfactants, acetylene glycol-based surfactants, and fluorine-based surfactants. One surfactant may be used alone, or two or more may be used in combination.

[0069] Examples of acetylene glycol-based surfactants include, but are not limited to, 2,4,7,9-tetramethyl-5-decine-4,7-diol and alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decine-4,7-diol. Examples of commercially available acetylene glycol-based surfactants include Orfin E1010, EXP4200, EXP4300, Surfinol SE, Surfinol 440, Surfinol 104, and Surfinol 465 (product names of Nisshin Chemical Industry Co., Ltd.).

[0070] Examples of fluorinated surfactants include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphate esters, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds.

[0071] Examples of silicone-based surfactants are not particularly limited, but include polysiloxane compounds and polyether-modified organosiloxanes. Examples of commercially available silicone-based surfactants include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-UV3500, BYK-UV3510, BYK-UV3530, and BYK-UV3570 (product names of BYK Corporation).

[0072] The surfactant content is preferably 0.1 to 4% by mass, 0.3 to 3% by mass, 0.5 to 2.5% by mass, or 1 to 2% by mass, relative to the total amount of the ink composition. When the surfactant content is within the above range, storage stability, clogging recovery, and bubble discharge tend to be further improved.

[0073] 1.6. pH adjusters The inkjet ink composition in this embodiment may contain a pH adjuster. The pH adjuster is not particularly limited, but examples include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; inorganic bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and ammonia; organic acids such as adipic acid, citric acid, and succinic acid; and organic bases such as triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine, diisopropanolamine, and trishydroxymethylaminomethane. A single pH adjuster may be used, or two or more may be used in combination.

[0074] The pH adjuster content is preferably 0.1 to 3% by mass, 0.3 to 2% by mass, and 0.5 to 1.5% by mass, relative to the total amount of the ink composition. When the pH adjuster content is within the above range, storage stability, scratch resistance, clogging recovery, and bubble discharge tend to be further improved.

[0075] 1.7. Fulvic acid The ink composition in this embodiment preferably contains fulvic acid. Fulvic acid is thought to function as a dispersion aid for carbon black and binder resin, which tends to further improve dispersibility and storage stability of the ink composition. Furthermore, because carbon black is a self-dispersing pigment, it has many hydrophilic functional groups, which improves its affinity for fulvic acid. This makes it easier for fulvic acid to adhere to the carbon black, resulting in improved storage stability and other desirable properties. Furthermore, carbon black derived from biological oils may have reduced storage stability due to the complex composition of impurities or its complex and large structure. However, the present invention is particularly useful because fulvic acid provides excellent storage stability. Among biological oils, vegetable oils are preferable because they tend to generate fulvic acid easily through oxidation treatment. It is believed that fulvic acid functions as a surface coating near the surface of the carbon black, thereby suppressing further aggregation and coarsening of the primary and secondary particles of the carbon black. In addition, it is believed that it can also suppress the adhesion of impurities to the carbon black. Furthermore, by improving the wettability of the carbon black surface, it becomes less likely for fine bubbles to accumulate in the voids of the carbon black, preventing print nozzle clogging and cleaning nozzle clogging, thus tending to improve the bubble discharge performance of the ink composition. Moreover, by further improving the affinity between carbon black and binder resin, the transfer resistance and abrasion resistance of the ink composition tend to improve. In this embodiment, fulvic acid does not fall under the category of resin dispersant.

[0076] Fulvic acid is a general term for a group of acidic substances found in corrosive materials that do not precipitate when exposed to acid. It can be obtained by separating and purifying it from soil using acids and alkalis, and is also available commercially. It is also produced during the oxidation process of carbon black as a self-dispersion treatment. The fulvic acid obtained in this way has high water solubility and low pH dependence, so it can maintain its water solubility over a wide pH range, and is less likely to become a foreign substance even when the pH changes. In other words, it can function as a useful dispersion aid even when changes occur in the state of the ink composition.

[0077] In this embodiment, fulvic acid may be prepared by mixing separately prepared fulvic acid, or fulvic acid separated from the treatment solution produced as a by-product during the oxidation treatment of carbon black may be concentrated or diluted and used. Alternatively, carbon black containing fulvic acid produced during the oxidation treatment process may be used. Among these, it is preferable to use carbon black that has been oxidized and contains fulvic acid, and to further adjust the amount of fulvic acid to a predetermined range by adding fulvic acid separately.

[0078] In excitation fluorescence matrix analysis, fulvic acid is preferably one that has peaks at fluorescence wavelengths (EM) of 380-600 nm and excitation wavelengths (EX) of 180-320 nm. In other words, it is preferable to have peaks in the excitation wavelength (EX) range corresponding to the above fluorescence wavelength (EM) range. Furthermore, in excitation fluorescence matrix analysis, it is preferable to have peaks at fluorescence wavelengths (EM) of 400-600 nm and excitation wavelengths (EX) of 200-300 nm. Fulvic acid having fluorescence and excitation wavelength peaks within the above ranges has a carbon skeleton similar to that of carbon black, and therefore has a higher affinity for carbon black, which tends to improve storage stability, transfer resistance, abrasion resistance, clogging recovery, and bubble discharge.

[0079] In this embodiment, the peak fluorescence wavelength of the fulvic acid in the excitation fluorescence matrix analysis method is preferably 400-550 nm, 400-500 nm, 420-480 nm, and 430-460 nm. When the fluorescence wavelength of the fulvic acid is within the above range, storage stability, transfer resistance, abrasion resistance, clogging recovery, and bubble discharge tend to be further improved.

[0080] In this embodiment, the peak excitation wavelength of fulvic acid in the excitation fluorescence matrix analysis method is preferably 200-320 nm, 200-300 nm, 220-280 nm, and 240-270 nm. When the excitation wavelength of fulvic acid is within the above range, storage stability, transfer resistance, abrasion resistance, clogging recovery, and bubble discharge tend to be further improved. In excitation fluorescence matrix analysis, the number of fluorescence wavelength and excitation wavelength peaks for fulvic acid may be one or more, or two to three, independently of each other. If fulvic acid has multiple peaks, it is preferable that at least one peak satisfies the above wavelength range, and more preferably that all peaks satisfy the above wavelength range.

[0081] The mass ratio of fulvic acid to pigment is preferably 0.0001 to 0.7, 0.001 to 0.5, 0.002 to 0.1, 0.003 to 0.05, or 0.005 to 0.02. When the mass ratio of fulvic acid to pigment is within the above range, storage stability, transfer resistance, abrasion resistance, clogging recovery, and bubble discharge tend to be further improved.

[0082] The fulvic acid content is preferably 0.001 to 5% by mass, 0.01 to 1% by mass, 0.02 to 0.3% by mass, or 0.03 to 0.1% by mass, relative to the total amount of the ink composition. When the fulvic acid content is within the above range, storage stability, transfer resistance, abrasion resistance, clogging recovery, and bubble discharge tend to be further improved.

[0083] 1.6.Water The inkjet ink composition of this embodiment is an aqueous ink containing water as a solvent. An aqueous inkjet ink composition is an inkjet ink composition that contains at least water as the main solvent component of the ink.

[0084] The water content is preferably 40% by mass or more relative to the total amount of the inkjet ink composition. More preferably, it is 40-99% by mass, 45-85% by mass, 50-70% by mass, 55-65% by mass, or 57-63% by mass. By setting the water content within the above range, storage stability, clogging recovery, and bubble discharge tend to be further improved.

[0085] 1.7. Other ingredients The ink composition may contain components other than those described above. Various additives such as solubilizers, viscosity modifiers, antioxidants, preservatives, fungicides, and corrosion inhibitors may be added as appropriate.

[0086] 2. Recording Method The recording method in this embodiment includes an adhesion step in which the inkjet ink composition is ejected from a predetermined inkjet head and adhered to a recording medium using a predetermined inkjet head.

[0087] 3. Recording device The recording device in this embodiment comprises the above-described ink composition and an inkjet head having a nozzle for ejecting the above-described ink composition onto a recording medium. More preferably, the device further comprises a supply channel through which the above-described ink composition flows and is connected to the inkjet head, and a filter unit provided in the supply channel of the inkjet head.

[0088] Figure 1 shows an example of an inkjet recording apparatus that can be used in this embodiment. The inkjet recording apparatus according to this embodiment will be described in more detail with reference to Figure 1. In the XYZ coordinate system shown in Figure 1, the X direction represents the length direction of the recording medium, the Y direction represents the width direction of the recording medium in the transport path within the recording apparatus, and the Z direction represents the height direction of the apparatus.

[0089] As an example, the recording device 10 is a line-type inkjet printer capable of high-speed and high-density printing. The recording device 10 includes a feeding unit 12 for storing a recording medium P such as paper, a transport unit 14, a belt transport unit 16, a recording unit 8, an Fd (face down) ejection unit 20 as an "ejection unit", an Fd (face down) placement unit 22 as a "placement unit", an inversion path unit 24 as an "inversion transport mechanism", a Fu (face up) ejection unit 26, and a Fu (face up) placement unit 28.

[0090] The feeding unit 12 is located at the bottom of the recording device 10. The feeding unit 12 includes a feeding tray 30 for storing recording media P and a feeding roller 32 for sending the recording media P stored in the feeding tray 30 to the transport path 11.

[0091] The recording medium P stored in the feeding tray 30 is fed along the transport path 11 to the transport unit 14 by the feeding roller 32. The transport unit 14 is equipped with a transport drive roller 34 and a transport driven roller 36. The transport drive roller 34 is rotationally driven by a drive source (not shown). In the transport unit 14, the recording medium P is nipped between the transport drive roller 34 and the transport driven roller 36 and transported to the belt transport unit 16 located downstream of the transport path 11.

[0092] The belt conveying unit 16 includes a first roller 38 located upstream in the conveying path 11, a second roller 40 located downstream, an endless belt 42 rotatably mounted on the first roller 38 and the second roller 40, and a support 44 that supports the upper section 42a of the endless belt 42 between the first roller 38 and the second roller 40.

[0093] The endless belt 42 is driven by a first roller 38 or a second roller 40, driven by a drive source (not shown), to move in the upper section 42a from the +X direction to the -X direction. As a result, the recording medium P conveyed from the conveying section 14 is further conveyed downstream of the conveying path 11 in the belt conveying section 16.

[0094] The recording unit 18 comprises a line-type inkjet head 48 and a head holder 46 that holds the inkjet head 48. The recording unit 18 may also be a serial-type unit in which the inkjet head is mounted on a carriage that reciprocates in the Y-axis direction. The inkjet head 48 is positioned to face the upper section 42a of an endless belt 42 supported by a support 44. When the recording medium P is transported along the upper section 42a of the endless belt 42, the inkjet head 48 ejects ink toward the recording medium P and performs recording. While recording is taking place, the recording medium P is transported downstream of the transport path 11 by the belt transport unit 16.

[0095] A first branching section 50 is provided downstream of the transport path 11 of the belt transport section 16. The first branching section 50 is configured to switch between a transport path 11 that transports the recording medium P to the Fd discharge section 20 or the Fu discharge section 26, and an inversion path 52 of an inversion path section 24 that inverts the recording surface of the recording medium P and transports the recording medium P back to the recording section 8. When the recording medium P is transported after being switched to the inversion path 52 by the first branching section 50, the recording surface is inverted during the transport process in the inversion path 52, and it is transported back to the recording section 8 so that the side opposite to the original recording surface faces the inkjet head 48.

[0096] A second branch section 54 is provided downstream of the first branch section 50 along the transport path 11. The second branch section 54 is configured to switch the transport direction of the recording medium P so as to transport the recording medium P toward the Fd discharge section 20 or toward the Fu discharge section 26.

[0097] The recording medium P transported toward the Fd discharge section 20 at the second branching section 54 is discharged from the Fd discharge section 20 and placed on the Fd mounting section 22. At this time, the recording surface of the recording medium P is placed facing the Fd mounting section 22. The recording medium P transported toward the Fu discharge section 26 at the second branching section 54 is discharged from the Fu discharge section 26 and placed on the Fu mounting section 28. At this time, the recording surface of the recording medium P is placed facing away from the Fu mounting section 28.

[0098] 4. Recording media The recording medium used in this embodiment is not particularly limited, but examples include absorbent recording media, low-absorbent recording media, or non-absorbent recording media, and is preferably an absorbent recording medium.

[0099] Examples of absorbent recording media include ordinary paper such as electrophotographic paper with high ink permeability and an ink-absorbing layer composed of silica particles or alumina particles, or inkjet-specific paper equipped with an ink-absorbing layer composed of a hydrophilic polymer such as polyvinyl alcohol or polyvinylpyrrolidone.

[0100] Examples of low-absorption recording media include art paper, coated paper, and cast paper, which are commonly used in offset printing and have relatively low ink permeability.

[0101] Examples of non-absorbent recording media include films and plates of plastics such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, and polyurethane; plates of metals such as iron, silver, copper, and aluminum; or metal plates or plastic films made by vapor deposition of these metals, or alloy plates such as stainless steel and brass; and recording media in which films of plastics such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, and polyurethane are bonded (coated) to a paper substrate.

[0102] 5. Records The recording material of this embodiment is obtained by adhering the above-described ink composition to a recording medium. The recording material of this embodiment using the above-described ink composition can be recorded with an ink that has excellent storage stability, color development, transfer resistance, abrasion resistance, clogging recovery, and bubble discharge properties. [Examples]

[0103] The present invention will be described more specifically below using examples and comparative examples. The present invention is not limited in any way by the following examples.

[0104] Figures 3 to 5 show Tables 2 to 4 illustrating the composition of each ink composition in the examples and comparative examples, as well as their evaluation results.

[0105] 1. Preparation of inkjet ink composition Dispersions were prepared by mixing and stirring to obtain the inkjet ink compositions for each example, as shown in Tables 2-4. If fulvic acid was generated by oxidizing the carbon black, the fulvic acid content was adjusted to match the amounts shown in Tables 2-4, including the amount of fulvic acid contained in the carbon black. Unless otherwise specified, the numerical values ​​for each component in the table represent mass percent. Furthermore, in the table, each value represents the mass percent of the solid content of each component (or the solvent component for solvents).

[0106] The details of the product ingredients used in Tables 2 to 4 are as follows.

[0107] [Pigments] • CB1~CB3, Binchotan charcoal pigment, petroleum CB (see adjustment example below) [Binder resin] • F1-5, resin dispersion (see adjustment example below) [Fulvic acid] • Fulvic acid (see adjustment example below) [Organic solvents] • BDG (Diethylene glycol monobutyl ether, logP ow (Value 0.56) • BTG (Triethylene glycol monobutyl ether, logP ow (Value 0.44) ·12HD(1,2-hexanediol, logP ow (Value 0.57) TEG (Triethylene Glycol, logP) ow (Value -1.75) • PG (Propylene Glycol, logP ow (Value -0.92) ·2P(2-pyrrolidone, logP) ow (Value -0.85) [Moisturizer] Gly: Glycerin TMG: Trimethylglycine [Surfactants] • E1010 (Acetylene glycol-based surfactant, manufactured by Nisshin Chemical Industry Co., Ltd.) ·S104 (trade name: "Surfynol 104", an acetylene glycol-based surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) [pH adjuster] ·TEA (triethanolamine) [Water] ·Ion-exchanged water

[0108] 1.1. Adjustment of pigment [Preparation of CB1] [Washing process] 25 g of carbon black (PRINTEX Nature, manufactured by Orion Engineered Carbons Co., Ltd., vegetable oil carbon black) is stirred and washed with toluene to wash away substances such as unburned components adhering to the surface of the carbon black.

[0109] [Surface treatment process] To the carbon black after the washing process, 5 g of sodium hypochlorite is added in water, and ultrasonic treatment is performed for surface treatment.

[0110] [Dispersion process] The dispersion liquid of carbon black after the surface treatment process is dispersed using a rocking mill with 0.3 mm beads for 1 hour to obtain a slurry. Then, 20% by mass of sodium hypochlorite is added to the carbon black in the slurry, heated to 70 °C, and surface treatment is performed for 30 minutes. The particle size is measured, and if the target particle size is not reached, the above dispersion treatment and surface treatment are performed again. Since a new hydrophobic surface is generated on the carbon black by dispersion, the surface treatment reaction is also carried out in the dispersion process.

[0111] [Neutralization and purification process] Sodium hydroxide is added to the dispersion liquid of carbon black after the dispersion process, and neutralized until the pH suitable for the ink reaches 8 - 9. After the neutralization reaction, the dispersion liquid is cooled to room temperature, and solid-liquid separation is performed using a centrifuge or the like for desalting treatment. Then, the solid matter is recovered and dried at 100 °C. Thereby, CB1, a self-dispersing pigment, is obtained.

[0112] [Preparation of CB2] Carbon black (PRINTEX Nature, manufactured by Orion Engineered Carbons Co., Ltd.) and Joncryl 678 (styrene acrylic resin, manufactured by BASF) as a dispersant are mixed at a mass ratio of 2:1 to obtain CB2.

[0113] <Preparation of CB3> Carbon black (PRINTEX Nature, manufactured by Orion Engineered Carbons Co., Ltd.) and Pearllex NP (sodium lignin sulfonate, trade name of Nippon Paper Industries Co., Ltd.) as a dispersant are mixed at a mass ratio of 2:3 to obtain CB3. <Preparation of Binchotan Pigment> Binchotan (manufactured by Kiriya Chemical Co., Ltd. Carbonized wood. Not bio-oil carbon black.) is treated in the same manner as CB1 to obtain binchotan pigment. <Preparation of Petroleum CB> Petroleum-derived carbon black (trade name "Aqua-Black162", manufactured by Tokai Carbon Co., Ltd.) is treated in the same manner as CB1 to obtain petroleum CB.

[0114] <Preparation Example of Fulvic Acid> 25 g of carbon black (PRINTEX Nature, manufactured by Orion Engineered Carbons Co., Ltd., vegetable oil carbon black) is stirred and washed with toluene to wash away substances such as unburned components adhering to the carbon black surface. 5 g of sodium hypochlorite is added to the washed carbon black in water for oxidation treatment. After the treatment, the carbon black is removed by centrifugation, the waste liquid is recovered, an alkaline aqueous solution is added to the waste liquid to separate the insoluble matter (humus) and the liquid, an acidic aqueous solution is further added to the liquid remaining after removing the insoluble matter to separate the generated insoluble matter, and the remaining liquid is concentrated and purified to obtain fulvic acid.

[0115] <Excitation Fluorescence Matrix Analysis (EEM)> The measurement sample is diluted, and the excitation wavelength (Ex) is measured three-dimensionally under the following conditions by the side reflection method. When the prepared measurement specimen is thick, the surface reflection method can also be selected. · Holder: Liquid holder (side photometry system) or solid holder (surface photometry system) · Cell: Surface-polished quartz cell (10×10 mm square quartz cell, side photometry) or double-surface-polished quartz cell (20×10 mm quartz cell, surface photometry) · Measurement wavelength Excitation (Ex): 200 - 700 nm · Measurement wavelength Fluorescence (Em): 200 - 700 nm · Data interval Excitation (Ex): 5.0 nm · Data interval Fluorescence (Em): 5.0 nm · Scanning speed: 60,000 nm / min · Slit width Excitation (Ex): 5.0 nm · Slit width Fluorescence (Em): 5.0 nm · Sensitivity: Photomultiplier voltage 700 V · Response: 2 ms · Automatic filter control: ON (automatic high-order light cut) When the obtained fulvic acid is measured by the excitation fluorescence matrix analysis method, it has two peaks: a peak at an excitation wavelength of 260 nm and a fluorescence wavelength of 445 nm, and a peak at an excitation wavelength of 265 nm and a fluorescence wavelength of 430 nm.

[0116] 1.2. Preparation of Binder Resin Self-emulsifying resins F1 to F5 are obtained by the following procedure. <Preparation of F1> Into a reaction vessel equipped with a stirrer, thermometer, reflux tube, and nitrogen inlet tube, charge 236.3 parts by weight of diethylene glycol monobutyl ether (BDG) as a solvent, 2.3 parts by weight of 2-iodo-2-cyanopropane (CPI), 3.7 parts by weight of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (trade name "V-70", manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) (V-70) as a polymerization initiator, 0.1 part by weight of N-iodosuccinimide (NIS), 68.7 parts by weight of tetrahydrofurfuryl methacrylate (THFMA) as a monomer, and 68.7 parts by weight of isobornyl methacrylate (IBXMA).

[0117] The raw materials were placed in a reaction vessel and stirred while bubbling nitrogen into the mixture, and polymer (polymer block A) was synthesized by polymerization at 45°C for 4 hours. The solid content measured by sampling a portion of the reaction solution was 37.4%, and the polymerization conversion rate calculated based on the solid content was approximately 100%. The number-average molecular weight (Mn) of polymer block A in terms of polystyrene, measured by GPC with tetrahydrofuran (THF) as the developing solvent, was 10,000, and the degree of dispersion (PDI = weight-average molecular weight (Mw) / number-average molecular weight (Mn)) was 1.2. Hereafter, molecular weight will be measured by this method. The glass transition temperature (Tg) of polymer block A was calculated from the Tg of the monomer homopolymer and the composition ratio, and is 101.5°C. The Tg of the THFMA homopolymer was calculated at 60°C, and the Tg of the IBXMA homopolymer was calculated at 155°C. Hereafter, Tg will be determined by this calculation method.

[0118] After cooling the obtained solution of polymer block A to 40°C, 2.7 parts by weight of V-70, 18.0 parts by weight of THFMA as a monomer, 54.1 parts by weight of IBXMA, and 18.0 parts by weight of methacrylic acid (MAA) are added into the reaction vessel. Polymerize at 40°C for 4 hours to form polymer block B and obtain an AB diblock copolymer. Confirm that the polymerization is almost complete by measuring the solid content and the amount of residual monomer by gas chromatography. The solid content measured by sampling a part of the reaction solution is approximately 50%, and the polymerization conversion rate is approximately 100%. The number average molecular weight (Mn) of the obtained AB diblock copolymer is 17,000 and the PDI is 1.3. The GPC peak of polymer block A has shifted to the high molecular weight side, confirming that it is an AB diblock copolymer. That is, the number average molecular weight (Mn) of polymer block B is 7,000. Also, the acid value of polymer block B is calculated from the content of MAA in the above-mentioned formulation and is 130.3 mgKOH / g. Further, the Tg of polymer block B is 143.3°C. The Tg of the homopolymer of MAA is calculated to be 228°C. A part of the polymer solution is precipitated in methanol, filtered, washed well with methanol, dried to obtain a resin solid, and titrated with an ethanolic 0.1 mol / L potassium hydroxide solution to measure the acid value, which is 51.5 mgKOH / g.

[0119] Next, under room temperature conditions, a mixed solution of 14.0 parts by weight of 28% aqueous ammonia and 458.6 parts by weight of ion-exchanged water is added for neutralization and emulsification to obtain a self-emulsifying resin F1. Hereinafter, the amount of water is adjusted so that the polymer content becomes 25%. The solid content of F1 is 25.1%. Also, after diluting F1 sufficiently with water, the number average particle diameter of the emulsion particles measured using a dynamic light scattering particle size distribution measuring device (particle size measuring device, trade name "nanoSAQRA", manufactured by Otsuka Electronics Co., Ltd.) is 75 nm. Also, the pH is 8.9. Further, when the viscosity is measured with an E-type viscometer, it is 3.6 Pa·s at 25°C.

[0120] <Adjustment of F2 to F5> Self-emulsifying resins F2 to F5 were obtained in the same manner as self-emulsifying resin F1, except that the monomers used were those shown in Table 1. All units are parts by mass. Table 1 also summarizes the Tg of each self-emulsifying resin. For all F1 to F5, polymer block B has a higher acid value than polymer block A. All F1 to F5 are dispersed by self-dispersion in the ink. All F1 to F5 dissolve in an organic solvent composition consisting only of the organic solvents contained in the ink. IBXMA (isobornyl methacrylate) IBXA (isobornyl acrylate) • THFMA (Tetrahydrofurfuryl methacrylate) STA (Stearyl Acrylate) LA (Lauryl acrylate) OA (Octyl Acrylate) • MAA (methacrylic acid)

[0121] <Preparation of resin dispersions> A non-self-emulsifying resin dispersion was obtained as follows: 900 g of deionized water and 3 g of sodium lauryl sulfate were charged into a reaction vessel equipped with a stirrer, reflux condenser, dropper, and thermometer, and the temperature was raised to 70°C while stirring and purging with nitrogen. Maintaining the internal temperature at 70°C, 4 g of potassium persulfate was added as a polymerization initiator. After dissolution, an emulsion prepared by stirring 450 g of deionized water, 3 g of sodium lauryl sulfate, 20 g of acrylamide, 300 g of styrene, 640 g of butyl acrylate, and 30 g of methacrylic acid was continuously added dropwise to the reaction solution over 4 hours. After the dropwise addition was complete, the mixture was allowed to mature for 3 hours. After cooling the obtained aqueous emulsion to room temperature, deionized water and a 5% sodium hydroxide aqueous solution were added to adjust the solid content to 40% by weight and the pH to 8. The glass transition temperature of the resin particles in the obtained aqueous emulsion was -15°C.

[0122] 2. Evaluation Method 2.1. Storage Stability The ink composition is left in a 60°C environment for one week. Then, the percentage change in the average particle size of pigment particles in the ink after the period of exposure compared to the average particle size of pigment particles in the ink before exposure is calculated and evaluated according to the following criteria. The average particle size is measured using dynamic light scattering with an ELSZ-1000 (manufactured by Otsuka Electronics Co., Ltd.) to measure the volume-average particle diameter D50 of the ink. (Evaluation Criteria) A: The percentage change is less than ±5%. B: The percentage change is ±5% or more, and less than ±10%. C: The percentage change is ±10% or more, and less than ±20%. D: Fluctuation rate is ±20% or more.

[0123] 2.2. Color development (OD value) The ink composition was installed in a modified PX-M791FT printer (product name manufactured by Seiko Epson Corporation), and Xerox P paper (copy paper manufactured by Fuji Xerox Corporation, basis weight 64 g / m²) was used. 2 Solid color printing is performed on A4 size paper (88 μm thickness) at a print resolution of 720 x 720 dpi. The OD value of the recorded material is measured and evaluated according to the following evaluation criteria. (Evaluation Criteria) A: OD value is 1.2 or higher. B: OD value is 1.0 or higher and less than 1.2. C:OD value is between 0.8 and less than 1.0. D:OD value is less than 0.8.

[0124] 2.3. Transfer resistance Using a modified LX-10050 printer (a line inkjet printer manufactured by Seiko Epson), Xerox P paper (copy paper manufactured by Fuji Xerox, 64 g / m² basis weight) was used. 2 Solid color printing is performed on paper (88 μm thickness) at a temperature of 25°C and a humidity of 50% with a printing duty cycle of 100%. The resulting transfer marks are evaluated according to the following evaluation criteria. (Evaluation Criteria) A: When observed from a distance of 30 cm, no transfer marks are visible. B: When observed from a distance of 30 cm, the transfer trace is visible, but when observed from a distance of 50 cm, the transfer trace is not visible. C: When observed from a distance of 50 cm, the transfer trace is visible, but when observed from a distance of 80 cm, the transfer trace is not visible. D: When observed from a distance of 80 cm, the transfer marks are visible.

[0125] 2.4.Abrasion resistance A modified PX-M791FT printer (manufactured by Seiko Epson Corporation) was filled with each ink composition, and Xerox P paper (Fuji Xerox copy paper, basis weight 64 g / m²) was used. 2 Twenty-six 20-point size alphabet characters are recorded onto a recording medium on paper with a thickness of 88 μm. Immediately after recording, the recording medium is fixed to a flat surface where it is placed horizontally. Five minutes after recording, the character areas are rubbed with a line marker "OPTEX CARE" (product name manufactured by Zebra Co., Ltd.), and the abrasion resistance is evaluated according to the following evaluation criteria based on the degree of ink bleeding. (Evaluation Criteria) A: No color bleeding occurs even after rubbing it three times. B: No color bleeding occurs after rubbing twice, but color bleeding occurs after rubbing three times. C: No color bleeding occurs after rubbing once, but color bleeding occurs after rubbing twice. D: Color bleeding occurs when rubbed once.

[0126] 2.5. Clogging recovery A modified PX-M791FT printer (product name manufactured by Seiko Epson Corporation) is filled with ink, and after performing a nozzle check to confirm that all nozzles are ejecting ink, the printer is left at 40°C for one week with the print head defapped. After this period, the number of cleaning cycles required for all nozzles to recover is evaluated according to the following evaluation criteria. (Evaluation Criteria) A: Cleaning frequency: 1 time or less. B: Cleaning done 2 to 3 times. C: Cleaning frequency: 4 to 5 times. D: All nozzles did not recover after 5 cleaning cycles.

[0127] 2.6. Bubble release properties A modified, unused PX-M791FT printer (product name manufactured by Seiko Epson Corporation) will be subjected to initial filling and cleaning using each ink composition. The number of cleaning cycles required until all nozzles dispense ink will be evaluated according to the following evaluation criteria. Note that ink compositions with good bubble discharge properties will satisfy the initial filling requirements. (Evaluation Criteria) A: All nozzles will dispense after initial filling and cleaning only. B: Initial filling and cleaning alone may result in nozzle failure; all nozzles will dispense after one or no additional cleaning. C: Initial filling and cleaning alone may result in nozzle failure; all nozzles will dispense after an additional cleaning of up to 3 times. D: Initial filling and cleaning alone may result in nozzle failure, and even with three or fewer additional cleaning attempts, not all nozzles will dispense.

[0128] 3. Evaluation Results Tables 2-4 show that the examples of inkjet ink compositions of this embodiment, which contain a self-dispersing pigment derived from bio-oil CB and a binder resin that is a self-emulsifying resin, all exhibit excellent color development, transfer suppression, and clogging recovery. Furthermore, they tend to have excellent storage stability, abrasion resistance, and bubble discharge properties. In contrast, the comparative examples that are not inkjet ink compositions of this embodiment all exhibit inferiority in either color development, transfer suppression, or clogging recovery. [Explanation of Symbols]

[0129] 10...Recording device, 11...Transport path, 12...Feeding section, 14...Transporting section, 16...Belt transport section, 18...Recording section, 20...Fd discharge section, 22...Fd mounting section, 24...Reversal path section, 26...Fu discharge section, 28...Fu mounting section, 30...Feeding tray, 32...Feeding roller, 34...Transporting drive roller, 36...Transporting driven roller, 38...First roller, 40...Second roller, 42...Endless belt, 42a...Upper section of endless belt, 44...Support, 46...Head holder, 48...Inkjet head, 50...First branching section, 52...Reversal path, 54...Second branching section, 56...Discharge roller pair, 64...Discharge drive roller, 68...Drive shaft, 76...Mounting surface, 78...Convex section, 80...First biasing member, 82...Second biasing member, 84, 86...Support shaft, P...Recording medium.

Claims

1. It contains a pigment that is carbon black derived from biological oil, a binder resin, and a solvent. The aforementioned pigment is a self-dispersing pigment, The binder resin includes a self-emulsifying resin, The solvent includes water. An inkjet ink composition, which is a water-based ink.

2. The DBP oil absorption capacity of the aforementioned pigment is 70 to 180 mL / 100 g. The primary particle size of the aforementioned pigment is 10 to 50 nm. The inkjet ink composition according to claim 1.

3. The aforementioned pigment is surface-treated by oxidation. The inkjet ink composition according to claim 1.

4. Contains fulvic acid, The inkjet ink composition according to claim 1.

5. The fulvic acid, in excitation fluorescence matrix analysis, has peaks at fluorescence wavelengths (EM) of 400 nm to 600 nm and excitation wavelengths (EX) of 200 nm to 300 nm. The inkjet ink composition according to claim 4.

6. The self-emulsifying resin is a block copolymer. The inkjet ink composition according to claim 1.

7. The self-emulsifying resin is a block copolymer made of an acrylic resin. The inkjet ink composition according to claim 6.

8. The solvent includes an organic solvent A having an octanol / water partition coefficient of 0 to 1. The inkjet ink composition according to claim 1.

9. Contains moisturizers The inkjet ink composition according to claim 1.

10. The invention comprises an ink application step of ejecting an inkjet ink composition according to any one of claims 1 to 9 from an inkjet head and adhering it to a recording medium. Recording method.

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