Compounds using natural pigments

Abstract

The present application provides a compound which is a high-biomass-degree compound (more preferably a 100% biomass-degree compound) obtained using a natural pigment, and which is excellent in color development and light resistance. A compound which is a compound in which a natural pigment of curcumin is bonded to an organic acid, and which has a number average molecular weight (Mn) of 400 to 4950.

Description

Technical Field

[0001] This invention relates to compounds that utilize natural pigments. Background Technology

[0002] In recent years, there has been a growing call for building a sustainable, circular society that considers the Earth's environment, ecosystems, and socio-economic factors. The printing industry also hopes to move away from petrochemical resources; for example, it is promoting the detoxification of printing inks due to considerations for the Earth's environment, biological systems, and safety. Furthermore, from a carbon-neutral perspective, there is increasing interest in replacing raw materials in printing ink manufacturing with biomass-derived chemicals, and research is actively underway on solvents and resins used in printing inks made from biomass raw materials.

[0003] Although the printing industry is also promoting environmental adaptation in this way, the current situation is limited to the biomassification of solvents and resins, and the biomassification of pigments has not yet been achieved.

[0004] As pigments used as colorants in printing inks, lake pigments, which are obtained by precipitating dyes using metal ions, are widely used due to their excellent color rendering and lightfastness.

[0005] The method of using metal ions to precipitate dyes results in the release of metal ions into the wastewater during manufacturing and refining, thus requiring additional wastewater treatment processes to remove these ions. It is believed that these additional wastewater treatment processes can reduce the environmental impact.

[0006] However, consumers have become more aware of the importance of products that take into account the Earth's environment and ecosystems in recent years. Consequently, in the pigment industry, there is a demand for manufacturing methods that are less likely to have an environmental impact. That is, there is a desire to develop pigments that can effectively prevent the emission of metal ions and are manufactured without using metal ions.

[0007] As for pigments that are not manufactured using metal ions, bio-derived pigments such as pigments that use algae directly have been reported (see Patent Document 1).

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: U.S. Patent Application Publication No. 2015 / 0240093 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, the pigment shown in Patent Document 1 is an environmentally friendly pigment because it contains biologically derived pigments that are not manufactured using metal ions. However, because it is a pigment that directly uses algae, there is a problem of insufficient hue selectivity.

[0013] Furthermore, the pigment shown in Patent Document 1 has poor color development compared to conventional lake pigments that use metal ions to precipitate dyes.

[0014] Furthermore, in order to be used as a colorant for inks, toners, and coatings, it is necessary to meet various properties required by color materials, such as color development and lightfastness. To date, among compounds with high biomass content using natural pigments (such as pigments), there are no compounds that offer excellent color development and lightfastness.

[0015] Therefore, the object of the present invention is to provide an environmentally friendly compound that does not use metals, particularly a compound with excellent color development and lightfastness as a compound with high biomass content (more preferably a compound with 100% biomass content) obtained by utilizing natural pigments.

[0016] Methods for solving problems

[0017] To address the aforementioned issues, the inventors conducted repeated and in-depth research, and discovered that compounds formed by the bonding of specific natural pigments such as curcumin with organic acids can solve these issues, thus completing this invention.

[0018] That is, the present invention includes the following methods.

[0019] [1] A compound which is a natural pigment of curcumin bonded to an organic acid, the number-average molecular weight (Mn) of the compound being 400 to 4950.

[0020] [2] A compound formed by bonding at least one natural pigment selected from alizarin, carmine acid, shellac pigment or shellac acid, capsanthin or capsicum pigment, hydroxysafflower yellow pigment or safflower yellow pigment, perilla pigment or perilla pigment, and kisanthomonasin or monaxanthin pigment with an organic acid.

[0021] [3] According to the compound described in [1] or [2], the organic acid has at least one or more carboxylic acid groups.

[0022] [4] According to the compound described in [3], the carboxylic acid is a naturally derived carboxylic acid.

[0023] [5] The organic acid in any one of [1] to [4] is any one of a carboxylic acid, a hydroxy acid, and a sulfonic acid.

[0024] [6] The compound according to any one of [1] to [5] has an average particle size of 0.01 to 100 μm.

[0025] [7] The compound according to any one of [1] to [6] is used as a colorant for inks, toners or coatings.

[0026] Invention Effects

[0027] According to the present invention, a compound can be provided that is a compound with high biomass content obtained by utilizing natural pigments (more preferably a compound with 100% biomass content), exhibiting excellent color development and lightfastness. Detailed Implementation

[0028] The present invention will now be described in detail. The descriptions of the constituent elements herein are illustrative and the invention is not limited thereto.

[0029] (compound)

[0030] The compounds of this invention are formed by the bonding of natural pigments and organic acids.

[0031] The compounds of the present invention are high biomass compounds obtained using natural pigments (more preferably compounds with 100% biomass), exhibiting excellent color development and lightfastness.

[0032] Biomass density refers to the value that represents the weight ratio of components derived from biomass.

[0033] The compounds of the present invention are preferably natural pigment polymers formed by repeating natural pigments bonded to organic acids.

[0034] Furthermore, the compounds of the present invention are in a particle state when colored, and can be used as pigments, preferably as colorants for inks, toners, and coatings.

[0035] The inventors have conducted repeated and in-depth studies on compounds with high biomass content obtained from natural pigments. As a result, they found that (1) compounds formed by the natural pigment curcumin bonded to organic acids and whose number-average molecular weight (Mn) is within a specific range (hereinafter referred to as "the compounds of the first embodiment"), and (2) compounds formed by the specific natural pigment bonded to organic acids (hereinafter referred to as "the compounds of the second embodiment") are compounds with excellent color development and lightfastness.

[0036] Therefore, the compounds of the present invention are divided into the cases described in the first embodiment and the second embodiment described above. The natural pigments and organic acids used as raw materials for the compounds will be described below.

[0037] <Compound of the First Embodiment>

[0038] The compound of the first embodiment of the present invention is formed by the bonding of the natural pigment of curcumin with an organic acid. Moreover, the number-average molecular weight (Mn) of the compound is 400 to 4950.

[0039] The inventors used curcumin as a natural pigment and studied compounds formed by bonding the natural pigment of curcumin with organic acids. The results showed that as the molecular weight increased, color development (especially chroma) and lightfastness decreased. Furthermore, it was found that compounds exceeding a certain molecular weight could not be practically and effectively used as colorants in inks, toners, or coatings. Therefore, the compounds of this invention, which are formed by bonding the natural pigment of curcumin with organic acids and have a number-average molecular weight within a specific range, exhibit excellent color development and lightfastness. The compounds of this invention can be effectively used as colorants in inks, toners, or coatings.

[0040] Curcumin

[0041] The curcumin used as a raw material in the compound of the first embodiment of the present invention has a diol structure. Curcumin can be bonded to organic acids via ester bonds.

[0042] Organic Acids

[0043] The organic acid used as a raw material for the compound of the first embodiment of the present invention is not particularly limited as long as it can bond with curcumin, which is a natural pigment, to form a polymer of the natural pigment. It can be appropriately selected according to the purpose.

[0044] The organic acid used in this invention is not particularly limited, but is preferably a substance that can easily bond to the OH group of curcumin via an ester bond.

[0045] The organic acid used in this invention is not particularly limited, and examples include carboxylic acids, hydroxy acids, sulfonic acids, etc.

[0046] From the viewpoint that the organic acid used in this invention can bond with curcumin, a natural pigment, to form a polymer of the natural pigment, it is preferable to have at least one carboxylic acid group. Therefore, the organic acid used is preferably a carboxylic acid or a hydroxy acid.

[0047] Examples of the aforementioned carboxylic acids include fatty acids, aromatic carboxylic acids, dicarboxylic acids, tricarboxylic acids, and polycarboxylic acids. Furthermore, examples of the aforementioned hydroxy acids include aliphatic hydroxy acids and aromatic hydroxy acids.

[0048] Examples of the aforementioned fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, acrylic acid, methacrylic acid, oleic acid, linoleic acid, and linolenic acid.

[0049] Examples of aromatic carboxylic acids mentioned above include salicylic acid, gallic acid, and benzoic acid.

[0050] Examples of the aforementioned dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, maleic acid, fumaric acid, citraconic acid, mesocarboxylic acid, mucoconic acid, dimer acid, aspartic acid, aldonic acid, itaconic acid, oxaloacetic acid, and glutamic acid.

[0051] Examples of the aforementioned tricarboxylic acids include aconitic acid, 1,3,5-benzenetricarboxylic acid, and propane-1,2,3-tricarboxylic acid.

[0052] Examples of the aforementioned polycarboxylic acids include acrylic polymers, acrylic-maleic acid copolymers, and acrylic-maleic anhydride copolymers.

[0053] Examples of aliphatic hydroxy acids mentioned above include glycolic acid, lactic acid, malonic acid, glyceric acid, hydroxybutyric acid, tartaric acid, malic acid, citric acid, ricinoleic acid, and shikimic acid.

[0054] Examples of aromatic hydroxy acids mentioned above include vanillic acid, phloroglucinic acid, coumaric acid, caffeic acid, ferulic acid, and sinapic acid.

[0055] The organic acid used in this invention is preferably a carboxylic acid or hydroxy acid having at least one carboxylic acid group, and more preferably an acid having two or more carboxylic acid groups. The more carboxylic acid groups an organic acid has, the more reaction sites it can bind to natural pigments, resulting in compounds with higher stability.

[0056] From the viewpoint of easily obtaining natural pigment polymer compounds with controlled structure and higher crystallinity, organic acids are used to bond organic acids to curcumin, which is a natural pigment, and to use organic acids as linkers to polymerize the natural pigment. As organic acids, acids having two carboxylic acid groups are more preferred, and dicarboxylic acids are particularly preferred.

[0057] When natural pigments and organic acids are polymerized through ester bonds, from the viewpoint of easily obtaining natural pigment polymer compounds with higher crystallinity, the most preferred dicarboxylic acids are those selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, maleic acid, fumaric acid, citralic acid, mesocarboxylic acid, mucocarboxylic acid, and dimer acids.

[0058] If a naturally derived carboxylic acid is used as the organic acid used in this invention, a compound with 100% biomass content can be obtained by bonding with a natural pigment, which is therefore more preferable from the viewpoints of the Earth's environment, biological systems, and safety.

[0059] Examples of naturally occurring carboxylic acids include succinic acid, sebacic acid, glycolic acid, lactic acid, glyceric acid, tartaric acid, malic acid, citric acid, ricinoleic acid, and fumaric acid.

[0060] From the viewpoint of readily obtaining compounds with excellent color development and lightfastness, as described above, it is important that the number-average molecular weight (Mn) of the compound of the first embodiment of the present invention is 400 to 4950. Furthermore, from the viewpoint of hue, chroma, and fastness, it is preferably 600 to 4950, and more preferably 800 to 4000. Additionally, from the viewpoint of readily obtaining compounds with excellent color development and lightfastness, the weight-average molecular weight (Mw) of the compound of the first embodiment of the present invention is preferably 400 to 10000, and more preferably 800 to 9000.

[0061] The molecular weight of the compounds of this invention can be determined as follows.

[0062] <Methods for determining molecular weight>

[0063] In this invention, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the compounds refer to the number-average molecular weight (Mn) and weight-average molecular weight (Mw) converted to polystyrene by gel permeation chromatography (GPC) using chloroform as a solvent. As a solvent, dimethylformamide is used when chloroform cannot be used for determination; tetrahydrofuran is used when even dimethylformamide cannot be used for determination; and hexafluoroisopropanol is used when even dimethylformamide cannot be used for determination.

[0064] <Compound of Embodiment 2>

[0065] The compound of the second embodiment of the present invention is formed by bonding at least one natural pigment selected from alizarin, carmine acid, shellac pigment or shellac acid, capsicum red or capsicum pigment, hydroxysaffron yellow pigment or safflower yellow pigment, perilla pigment or perilla pigment, and flavonoids or red yeast rice pigment with an organic acid.

[0066] The inventors have studied compounds utilizing natural pigments and found that compounds formed by bonding at least one natural pigment selected from the aforementioned specific natural pigments with organic acids exhibit excellent color development and lightfastness. The compounds of this invention, formed by bonding the aforementioned specific natural pigments with organic acids, can be effectively used as colorants in inks, toners, or coatings.

[0067] <<Specific Natural Pigments>>

[0068] The natural pigments used in the raw materials of the compound of the second embodiment of the present invention are selected from alizarin, carmine, shellac pigment or shellac acid, capsicum red or capsicum pigment, hydroxysaffron yellow pigment or saffron yellow pigment, perilla pigment or perilla pigment, and flavonoids or red yeast rice pigment.

[0069] These natural pigments can, for example, bond with organic acids via ester bonds.

[0070] Organic Acids

[0071] The organic acid used as a raw material in the compound of the second embodiment of the present invention is the same as the organic acid used as a raw material in the compound of the first embodiment described above. That is, the same organic acid as the organic acid described in the "Organic Acid" column of the "Compound of the First Embodiment" can be used.

[0072] From the viewpoint of readily obtaining compounds with excellent color development and lightfastness, the number-average molecular weight (Mn) of the compound of the second embodiment of the present invention is preferably 300 to 50,000, more preferably 300 to 30,000, and particularly preferably 300 to 20,000. Furthermore, from the viewpoint of readily obtaining compounds with excellent color development and lightfastness, the weight-average molecular weight (Mw) of the compound of the second embodiment of the present invention is preferably 300 to 100,000, more preferably 300 to 75,000, and particularly preferably 300 to 50,000.

[0073] <Methods for manufacturing compounds>

[0074] The compounds of the present invention (sometimes referred to as "compounds of the present invention" without distinguishing between the compounds of the first embodiment and the second embodiment described above, and where compounds of any embodiment are considered as objects) can be obtained by reacting natural pigments with organic acids and bonding natural pigments with organic acids. By bonding natural pigments with organic acids, compounds composed of polymers of natural pigments formed by repeating natural pigments can be obtained.

[0075] Examples of the aforementioned bonds include, for instance, ester bonds.

[0076] As a preferred embodiment of the method for manufacturing the compound of the present invention, a manufacturing method in which the hydroxyl groups of a natural pigment react with the carboxylic acid groups of an organic acid through an ester condensation reaction, thereby bonding the natural pigment with the organic acid.

[0077] As a more preferred embodiment, a manufacturing method can be described in which a diol compound of a natural pigment reacts with a dicarboxylic acid, which is an organic acid, through an ester condensation reaction, thereby bonding the natural pigment with the organic acid.

[0078] The method for manufacturing the compound of the present invention is achieved, for example, by ester condensation reaction of the above-mentioned diol compound with the above-mentioned dicarboxylic acid. As the dicarboxylic acid used in this process, it is natural that it can be used in the form of free dicarboxylic acid. In addition, it can also be used in the form of dicarboxylic acid ester, dicarboxylic acid anhydride, dicarboxylic acid chloride, and other dicarboxylic acid derivatives.

[0079] As a preferred embodiment of the method for manufacturing the compound of the present invention, a method can be exemplified by using dicarboxylic acid chloride as an organic acid, and obtaining the compound by esterification reaction of the dicarboxylic acid chloride, which is an organic acid, with a diol compound of a natural pigment. In this case, the compound can be manufactured by distilling off the hydrochloric acid generated at low temperature in the presence of a solvent or by neutralizing it with an alkaline compound. The reaction temperature at this time can be appropriately selected according to the purpose, for example, preferably -80 to 100°C, more preferably -80 to 60°C, further preferably -20 to 20°C, and particularly preferably -5 to 10°C.

[0080] When using a solvent, any solvent can be used as long as it does not react with the substrate. This includes halogenated hydrocarbons such as dichloromethane, chloroform, and tetrachloroethane; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as tetrahydrofuran, dioxane, and dimethoxyethane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; and amides such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone.

[0081] As a preferred embodiment of the method for manufacturing the compound of the present invention, when the natural pigment is curcumin, a method for manufacturing a curcumin polymer can be listed, which involves reacting the curcumin pigment shown in formula (i) with at least one dicarboxylic acid dichloride selected from the group consisting of succinic acid dichloride, adipic acid dichloride, sebacic acid dichloride, fumaric acid dichloride, terephthalic acid dichloride and biphenyl dichloride shown in formula (ii).

[0082] [Chemistry 1]

[0083]

[0084] [Chemistry 2]

[0085]

[0086] The mixing ratio of the above-mentioned natural pigments and the above-mentioned organic acids is preferably 1:0.1 to 1:10 by molar ratio, and more preferably 1:0.5 to 1:1.

[0087] Through the ester condensation described above, insoluble lake compounds precipitate out, and thus solid-liquid separation is achieved using known methods, followed by washing as needed. Examples of solid-liquid separation methods include vacuum filtration, pressure filtration, pressurized filter, spray drying, decantation, and centrifugation. Examples of washing solutions include hydrophilic solvents such as water and alcohol.

[0088] When unreacted raw materials remain, they are removed through this washing process. The powder, after solid-liquid separation or washing, is then dried using known methods to obtain an insoluble compound (pigment).

[0089] <Properties of Compounds>

[0090] In addition to exhibiting excellent color development (chroma), the compounds of this invention also exhibit excellent lightfastness.

[0091] For example, as shown in the following examples, the compounds of the present invention, which are composed of curcumin polymers obtained by bonding curcumin with organic acids, exhibit excellent chroma and lightfastness.

[0092] <<The Structure of Compounds>>

[0093] As a preferred embodiment of the compounds of the present invention, compounds having the structures shown in formula (I) or formula (II) below can be listed, for example.

[0094] [Chemistry 3]

[0095]

[0096]

[0097] (In formula (I) or formula (II), A represents the site from which the natural pigment is derived, B represents the site from which the organic acid is derived, and n represents 1 or more.)

[0098] Furthermore, as a preferred embodiment of the compound of the present invention, as a compound having the structure shown in formula (I) above, a compound having the structure shown in formula (Ia) below can be listed; as a compound having the structure shown in formula (II) above, a compound having the structure shown in formula (IIa) below can be listed.

[0099] [Chemistry 4]

[0100]

[0101] [Chemistry 5]

[0102]

[0103] (In formula (Ia) or formula (IIa), A represents the site from which the natural pigment is derived, R represents a hydrocarbon group, and n represents 1 or more.)

[0104] Furthermore, as a preferred embodiment of the compound of the present invention, as a compound having the structure shown in formula (Ia) above, compounds having the structure shown in formula (Ib) below can be listed; as a compound having the structure shown in formula (IIa) above, compounds having the structure shown in formula (IIb) below can be listed.

[0105] [Chemistry 6]

[0106]

[0107] [Chemistry 7]

[0108]

[0109] (In formula (Ib) or formula (IIb), A1 represents the residue after removing the terminal diol portion from the site derived from the natural pigment, R represents a hydrocarbon group, and n represents 1 or more.)

[0110] Furthermore, as a preferred embodiment of the compound of the present invention, when the natural pigment is curcumin, compounds having the structure shown in the following formula (III) can be listed.

[0111] [Chemistry 8]

[0112]

[0113] (In formula (III), Me represents methyl, R represents hydrocarbon group, and n represents 1 or more.)

[0114] R (hydrocarbon group) in the above formulas (Ia), (IIa), (Ib), (IIb), and (III) can be, for example, a straight-chain hydrocarbon group, a branched hydrocarbon group, or a cyclic hydrocarbon group.

[0115] The hydrocarbon group can be either saturated or unsaturated, such as chain-like saturated hydrocarbon groups, chain-like unsaturated hydrocarbon groups, cyclic unsaturated hydrocarbon groups, and saturated hydrocarbon groups.

[0116] The number of carbon atoms in the hydrocarbon group is preferably 2 to 15. Wherein, if the organic acid includes a dimer acid, the number of carbon atoms in the hydrocarbon is preferably 2 to 36.

[0117] As R (hydrocarbon group) in formulas (Ia), (IIa), (Ib), (IIb), (III), at least one group selected from the group consisting of the groups shown in formula (IV) below can be listed.

[0118] [Chemistry 9]

[0119]

[0120] <particle size>

[0121] The average particle size of the compounds of the present invention is not particularly limited, but from the viewpoint of color development and opacity when ink is applied, it is preferably 0.01 to 100 μm, and more preferably 0.05 to 50 μm.

[0122] In addition, the average particle size of the compound is obtained by taking pictures of the particles with a transmission or scanning electron microscope and measuring the major diameter of 20 particles, which is the arithmetic mean.

[0123] As described above, the compounds of the present invention exhibit excellent color development and lightfastness. Furthermore, the compounds of the present invention are high-biomass compounds and are biodegradable in seawater. Therefore, the compounds of the present invention can be used as colorants for inks, toners, or coatings.

[0124] The compounds of the present invention can be combined with other materials to form compositions (e.g., pigment compositions) for use in inks, toners, or coatings.

[0125] Marine biodegradability means that the compound can be decomposed by microorganisms in seawater. Specifically, the compound of the present invention was placed in seawater and stirred at 27°C for 30 days, and the weight of the compound before and after the test was measured. The same operation was also performed on polyhydroxybutyric acid (PHBA) powder. The weight reduction of the compound and PHBA was calculated separately. When the weight reduction of PHBA was set to 100%, a relative weight reduction of 5% or more for the compound was considered to indicate that it possesses biodegradability in seawater, i.e., marine biodegradability. The faster the decomposition rate in seawater, the lower the environmental burden; therefore, a relative weight reduction of 10% or more is preferred, and more preferably 15% or more.

[0126] (Pigment composition)

[0127] The compounds of the present invention can be combined with other materials to prepare pigment compositions.

[0128] <Resin>

[0129] In the above-described pigment compositions, resins can be formulated together with the compounds of the present invention. Examples of resins that can be used in the present invention include thermosetting resins and thermoplastic resins.

[0130] Thermosetting resins are resins that are essentially insoluble and whose insolubility can be varied when cured by means of heating, radiation, catalysts, etc. Examples of thermosetting resins include phenolic resins, urea-formaldehyde resins, melamine resins, benzoguanamine resins, alkyd resins, unsaturated polyester resins, vinyl ester resins, diallyl terephthalate resins, epoxy resins, silicone resins, polyurethane resins, furan resins, ketone resins, xylene resins, thermosetting polyimide resins, benzoxazine resins, reactive ester resins, aniline resins, cyanate ester resins, and styrene-maleic anhydride (SMA) resins. One or more of these thermosetting resins can be used.

[0131] Thermoplastic resins are resins that can be melted and molded by heating. Examples of thermoplastic resins include polyethylene resin, polypropylene resin, polystyrene resin, rubber-modified polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, polymethyl methacrylate resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene terephthalate resin, ethylene vinyl alcohol resin, cellulose acetate resin, ionomer resin, polyacrylonitrile resin, polyamide resin, polyoxymethylene resin, polybutylene terephthalate resin, polylactic acid resin, polyphenylene ether resin, modified polyphenylene ether resin, polycarbonate resin, polysulfone resin, polyphenylene sulfide resin, polyetheramide resin, polyethersulfone resin, polyaryl ester resin, thermoplastic polyimide resin, polyamide amide resin, polyetheretherketone resin, polyketone resin, liquid crystal polyester resin, fluoropolymer resin, syndiotactic polystyrene resin, cyclic polyolefin resin, etc. One or more of these thermoplastic resins can be used.

[0132] The resin of this invention can be used as a molding resin or as a varnish. Furthermore, it is expected to function as a dispersant, surface modifier, surfactant, film-enhancing agent, and other additives.

[0133] When a resin is formulated as a varnish, known resins can be used. Examples of resins formulated as varnishes include phenolic resins, petroleum resins, rosin-modified phenolic resins, petroleum resin-modified phenolic resins, rosin esters, alkyd resins, modified alkyd resins, rosin-modified maleic acid resins, natural bitumen resins, polyurethane resins, and epoxy resins.

[0134] When resins are formulated as dispersants or surface modifiers, known resins can be used. Examples of resins formulated as dispersants or surface modifiers include: cellulose, alkyl cellulose (ethyl cellulose, methyl cellulose, etc.), hydroxyalkyl cellulose (hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, etc.), carboxylalkyl cellulose (carboxymethyl cellulose, carboxyethyl cellulose, etc.), cellulose acetate and other cellulose derivatives, alkyl allyl polyether alcohols, sucrose esters of fatty acids, polyoxyethylene alkyl ethers, polyoxyethylene hydrogenated castor oil, propylene glycol esters of fatty acids, lauryl sulfate, stearates, dehydrated sorbitol esters of fatty acids, polyethylene glycol esters of fatty acids, polyoxyethylene glycerol esters of fatty acids, glycerol esters of fatty acids, polyoxyethylene polyoxypropylene glycol, polyoxyethylene sorbitol esters of fatty acids, polyoxyethylene alkyl allyl ethers, alkyl allyl sulfonates, polyoxyethylene dehydrated sorbitol esters of fatty acids, or mixtures thereof.

[0135] Solvent

[0136] Furthermore, solvents can be incorporated into the aforementioned pigment compositions. These solvents can be used as diluents or, more importantly, as additives for varnishes, wetting agents, and other applications.

[0137] As a solvent, there are no particular limitations; it can be used depending on the application. Examples of solvents include water, aqueous solvents, organic solvents, and liquid organic polymers. A single solvent or multiple solvents can be used in combination.

[0138] Examples of organic solvents include ketones such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK); cyclic ethers such as tetrahydrofuran (THF) and dioxolane; esters such as methyl acetate, ethyl acetate, and butyl acetate; aromatics such as toluene and xylene; paraffinic solvents such as n-pentane, isopentane, n-hexane, 2-methylpentane, n-heptane, n-octane, and trimethylpentane; cyclohexane solvents such as cyclohexane, cyclohexylmethane, octadecylcyclohexane, and methyl isopropylcyclohexane; carbitol; cellosolves; alcohols such as methanol, isopropanol, butanol, and propylene glycol monomethyl ether; mineral oil; and naphtha.

[0139] In addition, as solvents, non-drying oils such as castor oil, peanut oil, and olive oil, semi-drying oils such as soybean oil, cottonseed oil, rapeseed oil, sesame oil, and corn oil, drying oils such as flaxseed oil, perilla seed oil, and tung oil, as well as plant-derived oils such as regenerated vegetable oils and plant esters can also be used.

[0140] <Other coordination compounds>

[0141] The above-mentioned pigment composition may contain, as needed, anti-skinning agents, viscosity modifiers, film-forming enhancers, dispersants, antifouling agents, emulsifiers, antioxidants, and other complexes. Conventionally known substances may be appropriately used as these complexes.

[0142] (Molded body)

[0143] When the above-mentioned pigment composition contains a molding resin, the pigment composition can be molded to form a molded article. The molding method can be any conventionally known method, and can be appropriately selected according to the application. There are no restrictions on the shape of the molded article; it can be a flat plate, sheet, or any shape with curvature or other features corresponding to the purpose, including the entire surface or a portion thereof, of a three-dimensional shape.

[0144] For the molding methods described above, if the product is in sheet or plate shape, extrusion molding is generally used, but planar pressure can also be employed. Other methods include profile extrusion molding, blow molding, compression molding, vacuum forming, and injection molding. Furthermore, if the product is in film shape, in addition to melt extrusion, solution casting can be used. When using melt molding, methods such as blow molding, die molding, extrusion lamination, calendering, sheet molding, fiber molding, blow molding, injection molding, rotational molding, and coating molding can be used. Additionally, when the resin is cured by heat or active energy rays, various curing methods utilizing heat or active energy rays can be used to manufacture the molded product.

[0145] Furthermore, if the resin composition is liquid, it can also be molded by coating. Examples of coating methods include spraying, spin coating, dip coating, roller coating, doctor blade coating, doctor blade roller coating, doctor blade coating, curtain coating, slot coating, screen printing, and inkjet coating.

[0146] (Ink (printing ink))

[0147] The above-described pigment composition can be used in inks. Inks containing the above-described pigment composition contain resins and / or organic solvents in addition to the compounds of the present invention. The compounds of the present invention have excellent color development and lightfastness, and therefore, when used as colorants for inks, they enable vibrant printing.

[0148] By using the above-described pigment composition as ink, printed matter printed with that ink can be obtained. The substrate to which the printing is applied is not particularly limited, and examples include inorganic materials such as paper, wood, plastic, metal, and minerals, as well as their composites. The shape of the substrate is also not limited; it can be any shape corresponding to the purpose, such as a flat plate, sheet, or a three-dimensional shape, with curvature or a portion thereof. Furthermore, there are no limitations on the hardness, thickness, etc., of the substrate.

[0149] Printing inks using the compounds of the present invention can be obtained with known compositions other than those using the compounds of the present invention described above, without particular limitation.

[0150] Because the compounds of the present invention exhibit excellent color development, the printing inks can achieve vibrant printing results. Therefore, printing inks using the compounds of the present invention can be appropriately used in various printing inks used in offset printing, gravure printing, flexographic printing, screen printing, etc. Specifically, they can be appropriately used as offset printing inks for lithographic offset printing, and as liquid printing inks suitable for gravure printing and flexographic printing.

[0151] <Offset Printing Inks>

[0152] Offset printing inks refer to inks used in various printing methods that combine offset printing (offset printing using a damping solution, non-offset printing without a damping solution), letterpress printing, gravure printing, screen printing, and transfer printing (offset printing) methods where the inks adhering to these printing plates are transferred to an intermediate transfer medium such as a rubber blanket before being printed onto the substrate.

[0153] The offset printing ink is manufactured as follows: in addition to the compound of the present invention, it is mixed with printing ink resin varnish, organic solvent, vegetable oil such as soybean oil, vegetable oil esters, drying inhibitor, desiccant, abrasion resistance modifier, etc., and then mixed and dispersed using a roller mill or the like.

[0154] Liquid Printing Inks

[0155] Liquid printing inks used in gravure and flexographic printing are broadly classified into organic solvent-based liquid printing inks, which use organic solvents as the main solvent, and water-based liquid printing inks, which use water as the main solvent. The compounds of this invention are applicable to both organic solvent-based and water-based liquid printing inks.

[0156] <<Organic Solvent-Based Liquid Printing Inks>>

[0157] Organic solvent-based liquid printing inks are obtained by dispersing a mixture of binder resin, organic solvent, dispersant, defoamer, etc., in addition to the compounds of this invention, using a disperser. Resin, organic solvent, and additives such as leveling agents as needed are added to the obtained dispersion, and the mixture is stirred to obtain the organic solvent-based liquid printing ink.

[0158] <<Water-based Liquid Printing Inks>>

[0159] Water-based liquid printing ink is obtained by dispersing a mixture of binder resin, aqueous medium, dispersant, defoamer, etc., in addition to the compound of this invention, using a disperser. Resin, aqueous medium, and additives such as leveling agents as needed are added to the obtained dispersion, and the mixture is stirred to obtain the water-based liquid printing ink.

[0160] The compounds of the present invention can be used appropriately as colorants for inks, toners or coatings.

[0161] Example

[0162] The present invention will be further described in detail below with examples. However, the present invention is not limited to the following examples without departing from its spirit. Unless otherwise stated, the terms "parts," "%," etc., used in the examples refer to mass measurements.

[0163] <Pigment Manufacturing Method 1>

[0164] In a 100 mL two-necked flask, 82.8 parts by weight of natural pigment and 1599 parts by weight of tetrahydrofuran (manufactured by Kanto Chemical Co., Ltd., dehydrated, without stabilizer) were added. The mixture was purged with argon gas and stirred for 5 minutes while cooling to 0°C in an ice bath. Then, 22.7 parts by weight of triethylamine (manufactured by Fujifilm and Koko Pure Chemicals Co., Ltd., premium grade) were added dropwise, and the mixture was stirred further at 0°C for 5 minutes. Next, 17.2 parts by weight of organic acid were slowly added, and after the addition was complete, the mixture was stirred at 0°C for 6 hours. The solvent was then distilled off using an evaporator, and 1780 parts by weight of methanol (manufactured by Kishida Chemical Co., Ltd., grade 1) was added to suspend the solid. After washing, the solid was separated into solid and liquid phases by vacuum filtration using filter paper (manufactured by ADVANTEC, qualitative filter paper No. 1). The filtered solid was dried under vacuum at 50°C to obtain a powder.

[0165] (Example 1)

[0166] Using curcumin (manufactured by Fujifilm and Koko Pure Chemical Industries, Ltd., premium grade) as a natural pigment and fumaric acid chloride (fumaryl chloride, manufactured by Tokyo Chemical Industry Co., Ltd.) as an organic acid, a powder of a polymerized natural pigment compound was obtained by the above-described pigment manufacturing method 1.

[0167] The proportions of the components used in Example 1 are shown in Table 1 below. Furthermore, in Table 1, the proportions are expressed in parts by mass.

[0168] (Examples 2-8)

[0169] The same procedure was followed as in Example 1, except that the amounts of natural pigment (curcumin) and organic acid listed in Table 1 were changed to the amounts listed in Table 1. Otherwise, the natural pigment polymer compound powder was obtained by the same method as in Example 1.

[0170] (Example 9)

[0171] The procedure was the same as in Example 1, except that the natural pigment was replaced with alizarin, and the proportions of the natural pigment (alizarin) and organic acid were changed to those listed in Table 1. Otherwise, the natural pigment polymer compound powder was obtained using the same method as in Example 1. The obtained natural pigment polymer compound powder was pale yellow.

[0172] (Comparative Examples 1-2)

[0173] The same procedure was followed as in Example 1, except that the amounts of natural pigment (curcumin) and organic acid listed in Table 1 were changed to the amounts listed in Table 1. Otherwise, the natural pigment polymer compound powder was obtained by the same method as in Example 1.

[0174] [Table 1]

[0175]

[0176] <Methods for determining the molecular weight of polymer compounds>

[0177] The molecular weight of a polymeric compound sample converted to polystyrene was determined by gel permeation chromatography (GPC) under the following conditions.

[0178] Apparatus Name: LC-20000Plus series manufactured by Nippon Spectroscopy Corporation; Columns: "Shodex GPC KG 4A" as guard column and two connected columns "Shodex GPC K-804L" (all columns are manufactured by Showa Denko Corporation).

[0179] Column oven temperature: 40℃

[0180] Detectors: RI-2031Plus (manufactured by Nippon Spectros Technology Co., Ltd.) and UV-2070Plus (manufactured by Nippon Spectros Technology Co., Ltd.)

[0181] Elution buffer: chloroform

[0182] GPC sample concentration: 1 g / L

[0183] Flow rate: 0.5 mL / min

[0184] Standard sample: Polystyrene standard sample STANDARD SM-105 manufactured by Showa Denko Corporation.

[0185] Preparation of Offset Lithography Printing Inks

[0186] <<Preparation of Resin Varnish for Offset Lithography Inks>>

[0187] Add 44 parts by weight of rosin-modified phenolic resin (weight average molecular weight 45,000) and 15 parts by weight of soybean oil. Heat to 220°C under nitrogen flow and stir for 1.5 hours. Then add 39.7 parts by weight of AF solvent No. 7 (petroleum-based solvent: manufactured by JXTG Energy Co., Ltd.). Stir for 30 minutes and then cool to 140°C.

[0188] After cooling, add 1.0 part by weight of a 50% solution of ethyl aluminum diisopropyl acetoacetate diluted with AF solvent No. 7, heat to 160°C, stir for 1.0 hour, cool to 140°C, add 0.3 parts by weight of BHT (manufactured by Honshu Chemical Co., Ltd.) and stir to obtain a resin varnish for offset printing ink.

[0189] <<Preparation of Offset Lithography Printing Inks>>

[0190] The offset printing ink is obtained by mixing the inks in the following proportions using a 3-roll mill.

[0191] [Quantity of offset printing ink]

[0192] 65 parts of resin varnish for offset printing inks

[0193] 16 parts of natural pigment polymer compounds

[0194] 19 portions of AF Solvent No. 7

[0195] Using the natural pigment polymer compounds listed in Table 1, offset printing inks were prepared by the method described in the above-mentioned <<Preparation of Offset Lithographic Printing Inks>>.

[0196] <Preparation of Printing Ink Colorants>

[0197] After spreading the offset printing ink onto coated paper with a spatula, the paper is dried with a desiccant to obtain the printed material.

[0198] <Determination of Hue of Printing Ink Colorants>

[0199] Using a spectrophotometer (X-rite SpectroEye), the hue (L*, a*, b* values) of printing inks in the CIELAB color space were measured under the conditions of an observation light source of D50 and an observation field of view of 2°.

[0200] In addition, based on the obtained measurements, the chroma C* is calculated using the following formula.

[0201] C*=√((a*)^2+(b*)^2)

[0202] <Lightfastness Test>

[0203] For the printing ink colorants produced, based on the "promoting weather resistance and lightfastness (xenon lamp method)" specified in JIS K 5600:2008, Atlas Weather-Ometer Ci3000 manufactured by Toyo Seiki Co., Ltd. was used at an irradiance of 40 W / m². 2 The lightfastness test was conducted under the conditions of a black panel temperature of 63℃, 50% RH, and an exposure time of 15 hours. For the developing samples before and after the test, the hue was measured using the method described above, and the color difference ΔE value before and after the test (ΔE=√{(ΔL*^2)+(Δa*^2)+(Δb*^2)}^2; it should be noted that here, ΔL, Δa, and Δb represent the differences in L, a, and b values ​​of the developing sample before and after the test) was used to evaluate the lightfastness.

[0204] [Evaluation Criteria]

[0205] A: ΔE value is below 5

[0206] B: ΔE value is greater than 5 but less than 10

[0207] C: ΔE value is greater than 10 and less than 20

[0208] D: ΔE value is greater than 20 but less than 30

[0209] E: ΔE value exceeds 30

[0210] (Example 10)

[0211] For the powders of natural pigment polymer compounds obtained in Examples 2 to 6 and Comparative Examples 1 to 2 above, the number-average molecular weight Mn, weight-average molecular weight Mw, and molecular weight distribution (=Mw / Mn) were determined by the above-described polymer compound molecular weight determination method, and the results are shown in Table 2 below.

[0212] [Table 2]

[0213] Number average molecular weight Mn Weight-average molecular weight Mw Molecular weight distribution Mw / Mn Example 2 1384 1952 1.41 Example 3 1895 2760 1.46 Example 4 2754 3969 1.44 Example 5 3731 5855 1.57 Example 6 4913 8185 1.67 Comparative Example 1 6117 13251 2.17 Comparative Example 2 7702 16749 2.17

[0214] (Example 11)

[0215] The powders of natural pigment polymer compounds obtained in Examples 2-6 and Comparative Examples 1-2 were used as pigments to prepare printing ink developing materials by the methods described in the sections on <Preparation of Offset Printing Ink> and <Preparation of Printing Ink Developing Materials>. Then, the lightfastness was evaluated by the methods described in the sections on <Determination of Hue of Printing Ink Developing Materials> and <Lightfastness Test>.

[0216] The evaluation results of the lightfastness test of offset printing inks of various natural pigment polymer compounds are shown in Table 3 below.

[0217] [Table 3]

[0218]

[0219] Based on the above embodiments, it can be confirmed that the compounds of the present invention, which are composed of natural pigment polymers formed by the repetition of natural pigments bonded with organic acids, are compounds with excellent color development and lightfastness and high biomass content.

[0220] <Evaluation of Marine Biodegradability>

[0221] For 100 parts by weight of seawater (collected from Akahama Port, Narashino City, Chiba Prefecture) after removing foreign matter with a 30 μm mesh sieve, 0.015 parts by weight of a natural pigment polymer compound were added, and the mixture was stirred with a magnetic stirrer for 30 days while maintaining the water temperature at 27°C. The resulting natural pigment polymer compound was filtered through a filter membrane, dried under vacuum at 60°C for 24 hours, and then its weight was measured. The same procedure was performed on polyhydroxybutyric acid powder (manufactured by Sigma-Aldrich), and the weight of the resulting product was measured. The degree of weight loss and the relative degree of weight loss were calculated using the following formulas (1) to (3), and the biodegradability of the marine organisms was evaluated according to the following criteria.

[0222] • Weight reduction of natural pigment polymer compounds = 100 - (sample weight after 30 days / sample weight before test) × 100 (1)

[0223] • Weight reduction of polyhydroxybutyric acid (PHB) = 100 - (Weight of PHB after 30 days / Weight of PHB before the test) × 100 (2)

[0224] • Relative weight reduction = (weight reduction of natural pigment polymer compound / weight reduction of polyhydroxybutyric acid) × 100 (3)

[0225] [Evaluation Criteria]

[0226] A: The relative weight reduction is 15% or more.

[0227] B: Relative weight reduction of 10% or more but less than 15%

[0228] C: Relative weight reduction of 5% or more but less than 10%

[0229] D: Relative weight reduction less than 5%

[0230] (Example 12)

[0231] The natural pigment polymer compounds obtained in Examples 2 and 4 above were evaluated for biodegradability in seawater using the methods described in the <Evaluation of Marine Biodegradability> section above. The results are shown in Table 4 below.

[0232] [Table 4]

[0233] Evaluation results of marine biodegradability Example 2 C Example 4 A

[0234] Based on the above embodiments, it can be confirmed that the compounds of the present invention, which are composed of natural pigment polymers formed by repeating natural pigments bonded to organic acids, are marine biodegradable.

Claims

1. A compound comprising a natural pigment of curcumin bonded to an organic acid, wherein the organic acid is a carboxylic acid having two or more carboxylic acid groups, which is capable of bonding with curcumin to form a polymer of the natural pigment, wherein the number average molecular weight (Mn) of the compound is 400 to 4950, and the compound is a polymer of the natural pigment.

2. The compound according to claim 1, wherein the number-average molecular weight, Mn, is 600-4950.

3. A compound comprising at least one natural pigment selected from alizarin, carmine acid, shellac pigment or shellac acid, capsanthin or capsanthin, hydroxysaffron yellow pigment or safflower yellow pigment, perilla pigment or perilla pigment, and fungicides xanthophyll or red yeast rice pigment bonded to an organic acid, wherein the organic acid is a carboxylic acid having two or more carboxylic acid groups, and is capable of bonding with the natural pigment to form a polymer of the natural pigment, wherein the compound is a polymer of the natural pigment. The number-average molecular weight (Mn) of the compound is 300 to 100,000.

4. The compound according to claim 1 or 3, wherein the organic acid is a naturally sourced dicarboxylic acid.

5. The compound according to claim 1 or 3, wherein the average particle size of the compound is 0.01 to 100 μm.

6. The compound according to claim 1 or 3, used as a colorant for inks, toners or coatings.

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