Preservative

Abstract

This invention provides a preservation solution that can be used in the production and transportation processes of inkjet inks, and that is less likely to cause biofilm to be mixed into the ink. [Solution] This is a preservative solution that is pre-filled into a channel through which inkjet ink flows before the ink passes through. This preservative solution is characterized by containing at least a water-soluble quorum sensing inhibitor.

Description

Technical Field

[0001] The present invention relates to a preservation solution.

Background Art

[0002] When biofilms formed by microorganisms are mixed in ink for inkjet, the flow path for ejecting the ink may be blocked, resulting in poor ejection. Therefore, when producing ink for inkjet, a step of decomposing and removing biofilms may be performed during the ink production process. In addition, in order to suppress the growth of microorganisms so that biofilms are not formed by the microorganisms growing in the ink, an antiseptic or antibacterial agent may be contained in the ink (see, for example, Patent Document 1). In addition, in order not to mix microorganisms in the ink, the ink manufacturing apparatus may be heat-sterilized before ink production, or during storage of the ink manufacturing apparatus after the end of ink production, the flow path inside the ink manufacturing apparatus may be filled with a preservation solution containing an antiseptic.

[0003] On the other hand, when transporting a recording head equipped in an inkjet recording apparatus from a production site such as a factory, if the recording head is transported with the flow path inside filled with ink, the ink may deteriorate before reaching the user's hands. Also, if nothing is filled in the flow path inside the recording head and ink is introduced into the flow path inside the recording head after reaching the user's hands, bubbles are likely to occur because the ink is introduced into a dry flow path. In these cases, since good recording may not be possible, the flow path inside the recording head may be filled with a preservation solution in advance, and then the preservation solution inside the recording head may be replaced with ink (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, even with the measures taken to suppress the growth of microorganisms as described above, microorganisms from the air can adhere to areas where water stagnates in the manufacturing line or within the flow paths inside the recording head, forming biofilms that can then be mixed into the ink. Furthermore, microorganisms resistant to preservatives may also form biofilms. Therefore, it is extremely difficult to completely eliminate microorganisms during the production and transportation processes of inkjet inks.

[0006] Therefore, the object of the present invention is to provide a preservation solution that can be used in the production and transportation processes of inkjet inks, and that does not easily cause biofilm to be mixed into the ink. [Means for solving the problem]

[0007] In other words, the present invention provides a preservation solution that is pre-filled in a channel through which inkjet ink flows before the ink flows, and is characterized by containing at least a water-soluble quorum sensing inhibitor. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a preservation solution that can be used in the production and transportation processes of inkjet inks, and that is less likely to cause biofilm to be mixed into the ink. [Modes for carrying out the invention]

[0009] The present invention will be described in more detail below with reference to preferred embodiments. In the present invention, water-based ink for inkjet printing may be simply referred to as "ink." Unless otherwise specified, the physical properties are given at room temperature (25°C), normal pressure (1 atmosphere = 101,325 Pa), and normal humidity (50% relative humidity).

[0010] The inventors of this invention investigated a new method that would prevent biofilm formation altogether, rather than the conventional approach of suppressing biofilm formation by inhibiting microbial growth. As a result, they found that it is effective to include a water-soluble quorum sensing inhibitor in the storage solution used during storage of ink manufacturing equipment after ink production has ended, or in the storage solution that fills the flow path inside the recording head.

[0011] <Preservation solution> Specifically, a preservative solution containing at least a water-soluble quorum sensing inhibitor is used as a preservative solution that is pre-filled into the ink channels in ink manufacturing equipment and recording heads before the ink flows through them. This makes it difficult for biofilms to be mixed into the ink during various processes such as the production and transportation of inkjet inks. The components of the preservative solution will be described in detail below.

[0012] (Quorum sensing inhibitor) The preservation solution of the present invention contains a water-soluble quorum sensing inhibitor. A water-soluble quorum sensing inhibitor is a water-soluble compound that inhibits quorum sensing by microorganisms. A quorum sensing inhibitor is a compound that can suppress the formation of biofilms by microorganisms such as bacteria (see Journal of Environmental Biotechnology, 2010, Vol.10, No.1, pp.15-18).

[0013] Examples of water-soluble quorum sensing inhibitors include aromatic amides, lactones, furanones, phenols, sugar esters, pyrrolidines, piperidines, lactams, rhodanines, thiohydantoins, thiazolidinedions, histidines, and pyrimidines. One or more of these water-soluble quorum sensing inhibitors can be used. In particular, it is preferable that the preservation solution contains at least one water-soluble quorum sensing inhibitor selected from the group consisting of aromatic amides, lactones, furanones, phenols, and sugar esters. These water-soluble quorum sensing inhibitors have a strong inhibitory effect on quorum sensing and have little effect on ink performance even when mixed with ink.

[0014] Examples of water-soluble quorum sensing inhibitors of aromatic amides include benzamide, bromobenzamide, hydroxybenzamide, aminobenzamide (2-aminobenzamide, 3-aminobenzamide, and 4-aminobenzamide), nitrobenzamide, nicotinamide, and pyrazineamide. One or more of these aromatic amides can be used.

[0015] Examples of water-soluble quorum sensing inhibitors of lactones include γ-caprolactone, γ-heptalactone, γ-hexalactone, γ-octaractone, and N-butyrylhomoserine lactone. One or more of these lactones can be used.

[0016] Examples of water-soluble quorum sensing inhibitors of furanones include furanone, methylfuranone (such as 5-methyl-2-furanone and 5-methyl-3-furanone), methoxyfuranone (such as 4-methoxy-2-furanone), dimethylfuranone (such as 2,5-dimethyl-3-furanone, 3,4-dimethyl-2-furanone, and 5,5-dimethyl-2-furanone), and bromofuranone. One or more of these furanones can be used.

[0017] Examples of water-soluble quorum sensing inhibitors of phenols include vanillin, vanillic acid, eugenol, carvacrol, pyrogallol, and pterostilbene. One or more of these phenols can be used.

[0018] Examples of water-soluble quorum sensing inhibitors of sugar esters include sucrose laurate, sucrose myristicate, sucrose palmitate, sucrose stearate, sucrose oleate, sucrose behenylate, and sucrose erucate. One or more of these sugar esters can be used.

[0019] Furthermore, examples of water-soluble quorum sensing inhibitors of pyrrolidines include pyrrolidine and N-(pyrrolidine-3-yl)decanoylamide. Examples of water-soluble quorum sensing inhibitors of piperidines include piperidine. Examples of water-soluble quorum sensing inhibitors of lactams include pterolactam. Examples of water-soluble quorum sensing inhibitors of rhodanins include rhodanin. Examples of water-soluble quorum sensing inhibitors of thiohydantoins include 2-thiohydantoin. Examples of water-soluble quorum sensing inhibitors of thiazolidinediones include thiazolidinediones. Examples of water-soluble quorum sensing inhibitors of histidines include histidine. Examples of water-soluble quorum sensing inhibitors of pyrimidines include pyrimidine.

[0020] Among the water-soluble quorum sensing inhibitors listed above, aromatic amides are more preferable because they have a greater inhibitory effect on quorum sensing and have almost no impact on ink performance even when mixed with ink. Among those aromatic amides, it is even more preferable to use a water-soluble quorum sensing inhibitor containing 2-aminobenzamide.

[0021] The content (mass%) of the water-soluble quorum sensing inhibitor in the preservation solution is preferably 0.1 mass% or more and 10.0 mass% or less, and more preferably 0.5 mass% or more and 5.0 mass% or less, based on the total mass of the preservation solution.

[0022] (Aqueous medium) The preservation solution is preferably an aqueous preservation solution containing at least water as an aqueous medium. As the aqueous medium for the preservation solution, water or a mixed solvent of water and a water-soluble organic solvent can be used. As water, pure water or deionized water (ion-exchanged water) is preferably used. Examples of the water-soluble organic solvent include those that can be used in inkjet inks. For example, alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing compounds, sulfur-containing compounds, and the like can be mentioned. The content (mass%) of water in the preservation solution is preferably 50.0 mass% or more and 99.9 mass% or less, and more preferably 70.0 mass% or more and 99.5 mass% or less, based on the total mass of the preservation solution.

[0023] (Other components) In addition to the water-soluble quorum sensing inhibitor, the preservation solution may contain various additives such as surfactants, pH adjusters, rust inhibitors, preservatives, fungicides, antioxidants, anti-reducing agents, and water-soluble organic solvents as needed. In particular, preservatives and fungicides that suppress the growth of microorganisms and water-soluble organic solvents such as 2-pyrrolidone are preferable.

[0024] The preservative solution is used by pre-filling the channel through which the inkjet ink flows before the ink passes through. The ink that flows through the channel through which the preservative solution is used is preferably an aqueous ink containing at least water as an aqueous medium.

[0025] Examples of channels through which ink flows include channels in ink manufacturing equipment at production sites such as factories, channels within the recording heads of inkjet recording devices, and channels in inkjet recording devices that supply ink to the recording heads. For example, when using a preservative solution in the channels of an ink manufacturing device, the preservative solution can be pre-filled into the channels before the ink flows through them, in other words, before the ink is manufactured in the ink manufacturing device. Also, for example, when using a preservative solution in the channels of an inkjet recording device or recording head, the preservative solution can be pre-filled into the channels through which the ink flows when transporting the inkjet recording device or recording head from a production site such as a factory. Because it is possible to use the preservative solution in this manner, it is possible to make it difficult for biofilm to be mixed into the ink in various situations such as the ink production process and the transport process. [Examples]

[0026] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way by the following examples unless it exceeds the gist of the invention. Unless otherwise specified, amounts of components indicated in "parts" and "%" are based on mass.

[0027] <Sterilization of inkjet ink production equipment> In an ink manufacturing device installed in a factory to produce inkjet ink, components including the ink flow channels were heat-sterilized by passing 80°C water through them. The presence or absence of microorganisms in the liquid accumulated in the flow channels and on the flow channel walls of the ink manufacturing device was checked using a commercially available biochecker (product name "Sanai Biochecker," manufactured by San-ai Obli), and the results were negative. Furthermore, to check for the presence or absence of biofilm, the collected sample was filtered through a 1 μm filter, and the residue on the filter was checked for the presence or absence of peaks derived from polysaccharides, the main component of biofilm, using an infrared spectrophotometer, but no biofilm was detected.

[0028] <Preparation of preservative solution> (preservation solution 1~22) Using each of the water-soluble quorum sensing (QS) inhibitors 1 to 22 listed in Table 1, 2.0 parts of the QS inhibitor and 98.0 parts of pure water were mixed to prepare storage solutions 1 to 22 corresponding to the QS inhibitor numbers. For QS inhibitors 11 to 14, the product "Ryoto Sugar Ester" manufactured by Mitsubishi Chemical Corporation (the brand names listed in Table 1) was used.

[0029] TIFF2026086124000001.tif148170

[0030] (preservation solution 23) A preservative solution 23 was prepared by mixing 2.0 parts of water-soluble quorum sensing (QS) inhibitor 1, 96.0 parts of pure water, and 2.0 parts of a preservative (trade name "Proxel GXL(S)", manufactured by Arch Chemicals).

[0031] (preservation solution 24) Preservative solution 24 was prepared by mixing 2.0 parts of a preservative (product name "Proxel GXL(S)", manufactured by Arch Chemicals) and 98.0 parts of pure water.

[0032] <Storage of ink manufacturing equipment for producing ink for inkjet printers> The prepared preservation solutions 1-24 were filled into the ink flow channels of the ink manufacturing apparatus that had undergone the heat sterilization treatment described above, and left for two weeks. After the period, the preservation solutions 1-24 that had been filled into the flow channels were collected, and the presence or absence of microorganisms and biofilms was checked and evaluated using the same method as described above. The evaluation results are shown in Table 2.

[0033] TIFF2026086124000002.tif173170

[0034] In Examples 1-22, which used preservative solutions 1-22 containing only the QS inhibitor among the QS inhibitor and preservative, a small amount of microorganisms were detected (indicated as "slight" in Table 2), but no biofilm affecting ink ejection performance was detected. On the other hand, in Comparative Example 1, which used preservative solution 24 containing only the preservative among the QS inhibitor and preservative, no microorganisms were detected, but a biofilm affecting ink ejection performance was detected. It is presumed that the contaminating microorganisms were killed by the preservative, but formed a biofilm before death, and that this biofilm remained without being decomposed or removed.

[0035] Furthermore, the disclosure of this embodiment includes the following configuration. (Configuration 1) A storage liquid that is pre-filled in a channel through which inkjet ink flows before the ink flows through, A preservative solution characterized by containing at least a water-soluble quorum sensing inhibitor. (Configuration 2) The preservation solution according to Configuration 1, comprising at least one water-soluble quorum sensing inhibitor selected from the group consisting of aromatic amides, lactones, furanones, phenols, and sugar esters. (Configuration 3) The preservation solution according to Configuration 1 or 2, comprising the water-soluble quorum sensing inhibitor and aromatic amides. (Configuration 4) The preservation solution according to any one of Configurations 1 to 3, wherein the water-soluble quorum sensing inhibitor comprises 2-aminobenzamide.

Claims

1. A preservative liquid that is pre-filled in a channel through which inkjet ink flows before the ink passes through, A preservative solution characterized by containing at least a water-soluble quorum sensing inhibitor.

2. The preservation solution according to claim 1, wherein the water-soluble quorum sensing inhibitor comprises at least one selected from the group consisting of aromatic amides, lactones, furanones, phenols, and sugar esters.

3. The preservation solution according to claim 1 or 2, wherein the water-soluble quorum sensing inhibitor comprises aromatic amides.

4. The preservation solution according to claim 1 or 2, wherein the water-soluble quorum sensing inhibitor comprises 2-aminobenzamide.

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