JP2007056190A - Inkjet ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink that causes no nozzle clogging in an inkjet printer even after continuous printing for long terms and suffers from no elution of coloring agents even when soaked with water when used for marking on various kinds of foods, materials brought into contact with foods, packaging materials for foods, or the like and therefore gives no disgusting appearances. <P>SOLUTION: The inkjet ink comprises as a coloring agent a monascus colorant obtained by extraction with ethanol, and is comprised of 1-15 wt.% of the coloring agent, 3-10 wt.% of a shellac resin, 0-3 wt.% of sodium lactate or potassium lactate, 0-3 wt.% of acetic acid or lactic acid, 0-5 wt.% of propylene glycol, 0-10 wt.% of water, and ethanol as the remainder. Foods and food packaging materials are printed with the inkjet ink. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet ink suitable for marking on the surface of fresh foods such as apples, mandarin oranges, watermelons, and vegetables, and various foods such as eggs and food packaging materials that have an opportunity to come into contact with foods.

The foodstuffs including the unprocessed foods are required to display the production area, the producer display, the production history, and the like, and the processed foods are required to display the expiration date. Clarification of production history, harvest date, expiration date, etc. is expected as a method for improving quality, confirming safety, reliability of products, and providing a sense of security.
Such a display is constructed in view of various code systems, search methods, and the like, and more preferably, it is desired that each product is printed individually in the future. Therefore, it is important for raw foods, processed foods and other objects directly, through packaging materials, etc., in materials that come into contact with foods, or in materials that pass through food handling environments. It is a difficult task.

Conventionally, numerical values are printed using a printing press. However, a method using a printing press cannot quickly mark variable information. In addition, the ink used for marking on foods, food-related materials, food packaging materials and the like is preferably an ink based on food from the viewpoint of hygiene.
On the other hand, ink jet printers and thermal transfer printers are conventionally used to record production dates and lot numbers on canned foods and packs. Since these printers can directly record variable information, there is no need to create a printing plate, information can be easily changed by a computer, and various applications have been developed at production sites.

In particular, ink jet printers are used in a very wide range because they can perform printing at high speed and only require a small amount of ink by ejecting the necessary ink. Further, since printing can be performed in a non-contact manner, it is suitable for marking on a curved surface or a soft object.
As an ink used for an ink jet printer, there is one obtained by dissolving a water-soluble dye, which is a food additive colorant, in water, but its water resistance is inferior, and it cannot be used for an object in contact with water.

  On the other hand, as an ink-jet ink excellent in water resistance and suitable for printing on the surface of food, Patent Document 1 (Japanese Patent Laid-Open No. 53-127010) discloses that the binder is shellac and consists of water and ethanol. A green ink composition is disclosed that includes a solvent and sodium iron chlorophyllin or / and copper chlorophyllin sodium as a colorant. However, the colorants such as copper chlorophyllin used are water-soluble pigments that are not sufficiently soluble in alcohol, and use of water is indispensable for increasing the ink concentration. Therefore, this ink is essentially composed mainly of water and is used by mixing a small amount of ethanol. The shellac resin is also of a type that is soluble in water, and in order to stabilize the dissolution, a non-food additive such as morpholine is used as the ink raw material. In addition, in order to maintain the solubility of the resin, a solvent such as methyl cellosolve was also used. These consist of materials that are not permitted in food additives.

  Patent Document 2 (Japanese Patent Laid-Open No. 9-302294) discloses an ink-jet ink containing a bayberry extract, a flavonoid substance, and an organic acid as an edible stabilizer. In Patent Document 2, the edible stabilizer is intended to stabilize the light resistance of the pigment, and the ink is an ink that uses 70 parts by weight or more of water. The pigment and the stabilizer are exclusively water. It is not an ink considering the solubility in ethanol, which is only about 20 parts by weight. Therefore, when the printed matter comes into contact with water, it is recognized as a category of so-called water-based ink in which pigments, resins, and the like are easily dissolved by water.

  Although these inks have been shown to have good light stability, they are inks that contain more water than ethanol, and thus have good drying properties such as using more than 70 parts by weight of alcohol. Ink formulations for alcohol-type continuous printers are not disclosed. Further, the resin used is a water-soluble type resin and is not a water-resistant ink mainly composed of alcohol.

  Sodium lactate is a material that provides solubility and good conductivity in alcohol-based inks, but tends to cause aggregation, sedimentation, etc. in the coexistence with shellac resin and Benikouji dye, and is stable with respect to ink. There was a phenomenon in which the properties deteriorated during production and over time. That is, the solubility of the dye and the resin in ethanol and other stability are reduced. In addition to foods and food additives, it is possible to study various materials to procure materials that do not have problems with such stability, but in materials similar to foods, the materials are limited, This adjustment was difficult.

Japanese Patent Laid-Open No. 53-127010 JP-A-9-302294

The present invention does not cause clogging of the nozzle of an ink jet printer even when continuous printing is performed for a long period of time, and it is colored even if it gets wet with water when marked on various foods, food contact materials, food packaging materials, etc. The purpose of the present invention is to provide ink-jet inks and fresh foods that have been marked so as not to cause elution of the material and to cause an unpleasant appearance.
Another object of the present invention is to quickly mark variable information and improve the form of quality control and distribution management of fresh food.

  The present invention relates to an ink-jet ink using a red yeast rice pigment extracted with ethanol as a colorant, 1 to 15% by weight of a colorant, 3 to 10% by weight of shellac resin, 0 to 3% by weight of sodium lactate or potassium lactate, acetic acid or The present invention relates to an inkjet ink comprising 0 to 3% by weight of lactic acid, 0 to 5% by weight of propylene glycol, 0 to 10% by weight of water, and the remainder of ethanol.

  The present invention also relates to the inkjet ink, wherein the red yeast rice pigment is a pigment that has undergone a step of extraction with 99 degree fermented ethanol.

Further, in the present invention, sodium lactate or potassium lactate, and acetic acid or lactic acid are each greater than 0% by weight, and
The present invention relates to the above ink-jet ink, wherein acetic acid or lactic acid is mixed and dissolved in an aqueous solution of sodium or potassium lactate and then added as a conductivity adjusting agent.

  Moreover, this invention relates to the said inkjet ink which adjusted PH of ink to 5.5-6.8.

  The present invention also relates to the above-described ink jet ink for continuous use, wherein the conductivity of the ink is adjusted to 0.5 to 5.0 mS / cm.

  Moreover, this invention is the said inkjet ink for foodstuffs or food packaging printing.

  The present invention also relates to a food product or a packaging material thereof obtained by printing the ink on the surface of the food body or the packaging material.

The ink-jet ink of the present invention is an alcohol ink having a good drying property that does not impair the taste of fresh foods, and does not bother odor even during marking.
The ink-jet ink of the present invention can form markings with good water resistance, and can print variable information at high speed.
Furthermore, the ink-jet ink of the present invention is composed of those recognized as food additives, displays high quality data from fresh food sensor measurements, and is also effective in quality traceability.

  The ink-jet ink of the present invention essentially uses ethanol as a solvent, and includes water in alcohol, water in a solution of lactate, which is a conductive material, and the like. It is an alcohol ink containing at least 54% by weight or more of water (water is 16% by weight or less of the whole ink). Ethanol that can be used in the present invention is food-grade fermented ethanol or denatured ethanol.

In the present invention, the colorant is ethanol-soluble and is an alcohol-soluble sockeye pigment. Although this pigment | dye is a pigment | dye extracted with the mixed solvent of alcohol and water, in this invention, it is preferable to use the pigment | dye which passed through the process extracted with alcohol further than the dried pigment | dye.
The step of extracting with the alcohol further reduces the amount of contaminants in the pigment and can substantially improve the pigment concentration in the ink. In addition to increasing the viscosity of the ink, the contaminants may cause sedimentation and precipitation over time, and this treatment is effective in increasing the print density and maintaining the stability of the ink. As this treatment, it is efficient to use an alcohol with a small amount of water, and it is preferable to use 300 to 900 parts by weight of 99 degree fermented alcohol with respect to 100 parts by weight of the dry pigment. The thus-treated colorant of the present invention has water resistance and friction resistance with which the marked ink does not elute even when immersed in water or rubbed. The colorant is preferably contained in the range of 1 to 15% by weight of the total ink. When the content is less than 1% by weight, the print density is insufficient, and when the content exceeds 15% by weight, the solubility is insufficient and the continuous ejection stability of the ink tends to deteriorate.

The shellac used in the present invention uses an alcohol-soluble resin. This shellac is compatible with the food additive dye used in the present invention. In addition, it functions to dissolve in alcohol and increase the viscosity of the ink, and also functions as a good binder for the substrate.
In the present invention, shellac is preferably contained in the range of 3 to 10% by weight, preferably 4 to 8% by weight of the total ink. When the content is less than 3% by weight, an appropriate viscosity cannot be obtained. Moreover, it is difficult to obtain sufficient adhesion. On the other hand, if it exceeds 10% by weight, the viscosity of the ink becomes too high and the stability in continuous operation at a low temperature is lowered.

  In the ink-jet ink of the present invention, when used in a continuous type printer, a conductivity adjusting agent is used. As the conductivity adjusting agent, those which give good solubility and conductivity to ethanol and are food additives are preferable. Sodium lactate or potassium lactate is used as such a conductivity adjusting agent. These conductivity adjusting agents are preferably blended in an amount of 0.5 to 3% by weight based on the total ink. If the content is less than 0.5% by weight, sufficient conductivity cannot be obtained, and if the content exceeds 3% by weight, the solubility is insufficient in cleaning such as ink replacement, leading to defects such as precipitation. In the case of using a printer other than the continuous type, a conductivity adjusting agent is not particularly required.

  In the ink-jet ink of the present invention, acetic acid or lactic acid is used together with the conductivity adjusting agent. These improve the above-described conductivity adjusting agent because it makes the compatibility and stability unstable with the dye, and prevents precipitation and precipitation of the dye.

  This also improves the operability of the filtration process and the like during ink production. Acetic acid or lactic acid is suitable for use with these conductivity adjusting agents, and these can be used alone or in combination. As similar organic acids, there are ascorbic acid, citric acid, and the like, but these cause white turbidity and sedimentation when mixed with a conductivity adjusting agent, and an effect such as acetic acid or lactic acid cannot be obtained. Acetic acid and lactic acid function as good regulators, but since lactic acid does not smell, use of lactic acid is preferred to acetic acid in fields where odors in foods are desired. Acetic acid or lactic acid is preferably used at 0 to 3% by weight of the total ink.

  In the ink-jet ink of the present invention, propylene glycol or glycerin can be appropriately used in order to prevent the ink from being dried at the nozzle. These solvents are preferably contained in the range of 0 to 5% by weight of the total ink. The use of propylene glycol causes a decrease in the drying property on the printing medium, but also exhibits an effect in improving adhesion and adjusting moderate solubility of the resin, the dye and the electrolyte. It is effective to use more than 0% by weight to suppress drying at the nozzle, but if it exceeds 5% by weight, drying of the marking surface of the substrate is slowed down, resulting in a decrease in production speed. There is. In addition, it adversely affects the contamination of the transporter during printing.

  Further, in order to adjust the color, the ink-jet ink of the present invention can contain other edible dyes in a range of less than 1% by weight of the total ink. Examples of the edible pigment include norvirxin potassium, norvirxin sodium, anato, chlorophyll, akane, gardenia, paprika, and grape skin pigment.

In the production of the ink-jet ink of the present invention, it is used as an alcohol-extracted dye solution obtained by dissolving a powdered red yeast rice dye with alcohol.
Shellac resin is also used as a solution previously dissolved in alcohol.
In addition, a conductivity adjusting agent is also used by previously mixing an aqueous solution of sodium lactate or potassium lactate with acetic acid or lactic acid. Prepare an alcohol extraction dye solution and a shellac alcohol solution in advance, add a dye solution and a resin solution, a mixture of a conductivity adjusting agent and acetic acid or lactic acid, propylene glycol, water, etc., and mix and stir. It can manufacture by filtering with a -3.0 micrometer membrane filter. Mixing and stirring can be carried out by a high-speed disperser or emulsifier in addition to a stirrer equipped with a normal blade.

  The viscosity of the inkjet ink of the present invention at 25 ° C. is preferably adjusted to a range of 2.5 to 6 mPa · s. If the viscosity is too low, the formation of ink dots on the printing medium will be poor, and the print density will be low. On the other hand, if the viscosity is too high, there will be problems with poor ejection and poor drying.

  Although the surface tension is suitable for a printer, it is preferably adjusted to a range of 22 to 26 mN / m. Moreover, when marking with a continuous type printer, it is preferable to adjust the electrical conductivity of the ink in the range of 0.5 to 5 mS / cm.

When marking to the raw food using the inkjet ink of the present invention on the surface of the raw food, the marking is performed by the inkjet method, and the marked raw food is obtained. Inkjet methods include continuous methods (multi-value deflection, binary deflection), drop-on-demand methods (Bubble Jet (registered trademark) method, piezo method, solenoid valve method, etc.), etc., but marking at high speed For the marking of curved surfaces and flexible surfaces such as fresh foods, the continuous method is suitable.
The nozzle hole diameter of the ink jet printer is preferably 8 to 100 μm.
As raw foods, apples, mandarin oranges, watermelons, lemons, tomatoes and other fruits and vegetables are objects, especially in measuring instruments such as sugar content, which is a quality characteristic, or eggs etc. If marking is performed in conjunction with data such as egg collection information, quality can be presented to consumers, resulting in a high value-added product.

  The ink-jet ink of the present invention can be used for foods, materials that come into direct contact with foods, and food packaging materials. Examples of such packaging materials include surface-treated polypropylene, polyethylene, nylon, plastic materials such as polyethylene terephthalate, nonwoven fabric, and paper.

  The data to be marked can be written together with the production location, harvest date and time, producer, date, special symbols, and the like.

  These notations give reliability to the distribution form of the product as a reliable display method of the route. In marking, due to the characteristics of fresh food, water droplets etc. may also adhere to the surface. In such cases, forced drying of the marking surface with pressurized air (air gun) just before marking or application of warm air The forced removal of water drops is an effective treatment means.

  Examples of fresh foods that are marked with the production area, harvest date, sugar content, and the like include fruits such as mandarin oranges, apples, and watermelon, vegetables, meats, and fresh fish.

  Hereinafter, the present invention will be described in detail with reference to examples. In the examples, parts and% indicate parts by weight and% by weight, respectively.

(Example and Comparative Example 1)
The raw materials shown in Tables 1 and 2 below were mixed and dissolved, and then filtered through a 0.8 μm membrane filter to prepare an inkjet ink. The ethanol used in this example is 99% or more ethanol. (99 degree fermented ethanol)

  The inks obtained in Examples and Comparative Examples were measured for viscosity (mPa · s), surface tension (mN / m) and electrical conductivity (mS / cm) at 25 ° C. The viscosity is measured using a viscometer (“Digital Viscomate” manufactured by YAMAICHI), and the surface tension is measured using a surface tension meter (“Surface Tensiometer” manufactured by KYOWA INTERFACE). Was measured using a conductivity meter ("Conductivity meter" manufactured by HORIBA).

  Moreover, the ink obtained by the Example and the comparative example was put into the ink tank of the commercially available continuous type inkjet printer, and it marked on the egg, and the following evaluation was performed about the obtained marking thing. In addition, a long-term operation was performed for 3 months to evaluate whether nozzle clogging occurred and whether trouble occurred in the ink circulation system. The results are shown in Table 3 and Table 4.

・ Solubility Visually evaluate the presence or absence of precipitates and precipitates when mixing raw materials.
・ Filterability Ink filtration test with 90mmφ 0.8μ membrane filter of mixed solution. 500 ml suction filterability.
・ Dilutability Measured with UPA (particle size distribution meter made by Nikkiso Co., Ltd.) with a mixture of 95% ethanol and 5% water by weight in 75 parts of ink, and measured with or without a peak at 1 μm or more .
-Adhesiveness Ink is applied to various printed materials, whether or not there is peeling with a cellophane tape and whether or not there is peeling by rubbing.
・ Water resistance Water is sprayed on the printing surface to check for dye elution.
・ Change over time The ink is stored in a screw can (glass container), and the presence or absence of sediment on the bottom and aggregate on the wall is evaluated visually.

  The same print was printed on corrugated cardboard and polyester film, and the production symbols and the like could be confirmed well. Also, good printing characteristics were shown in the lot number and content display on the surface of the hard capsule.

Claims (7)

In an inkjet ink using a red yeast rice pigment extracted with ethanol as a colorant, 1 to 15% by weight of a colorant, 3 to 10% by weight of shellac resin, 0 to 3% by weight of sodium lactate or potassium lactate, 0 to 3% of acetic acid or lactate An ink-jet ink comprising: wt%, propylene glycol 0 to 5 wt%, water 0 to 10 wt%, and ethanol remaining. The inkjet ink according to claim 1, wherein the red yeast rice pigment is a pigment that has undergone a step of extraction with 99-degree fermented ethanol. Sodium lactate or potassium lactate and acetic acid or lactic acid are each greater than 0% by weight, and
3. The ink-jet ink according to claim 1, wherein acetic acid or lactic acid is mixed and dissolved in an aqueous solution of sodium or potassium lactate and then added as a conductivity adjusting agent. The inkjet ink according to any one of claims 1 to 3, wherein the pH of the ink is adjusted to 5.5 to 6.8. The inkjet ink for continuous use according to any one of claims 1 to 4, wherein the conductivity of the ink is adjusted to 0.5 to 5.0 mS / cm. The inkjet ink according to any one of claims 1 to 5, which is for food or food packaging printing. A food or a packaging material thereof, wherein the ink according to any one of claims 1 to 6 is printed on the surface of the food body or the packaging material.