JP5820244B2 - Ink solvent manufacturing method, ink jet recording ink manufacturing method, ink cartridge manufacturing method - Google Patents

Description

  The present invention relates to a method for producing an ink solvent for an ink jet recording ink, a method for producing an ink for ink jet recording containing the ink solvent, and a method for producing an ink cartridge for storing the ink for ink jet recording. In particular, a method for producing an ink solvent for ink jet recording using a vinyl chloride vinyl acetate copolymer resin produced by suspension polymerization, a method for producing an ink for ink jet recording containing the ink solvent, and an ink for the ink jet recording The present invention relates to a method for manufacturing an ink cartridge to be stored.

  Ink jet recording inks required for uses such as outdoor postings place importance on light resistance and weather resistance. In addition, a high printing speed and quick drying of printed matter are required. As such an ink for ink jet recording, a pigment ink jet recording ink using a pigment as a coloring material is used. Usually, ink for inkjet recording is supplied in a state of being stored in an ink cartridge.

  Also, since the recording medium is placed outdoors, light resistance and weather resistance are regarded as important, and a polyvinyl chloride resin base material (hereinafter referred to as a PVC base material) is widely used. Ink jet recording inks for recording on such recording media are known in which glycol monoacetates and glycol ethers are used as main solvents.

  In addition, as a binder resin for ink jet recording ink, a vinyl chloride vinyl acetate copolymer resin (hereinafter referred to as a vinyl acetate resin) having excellent adhesion to a PVC substrate is often used. There are several production methods for vinyl chloride resin such as solution polymerization, emulsion polymerization, suspension polymerization and the like.

  The vinyl chloride resin produced by solution polymerization has voids in the resin particles and easily penetrates the organic solvent inside the resin, so that it dissolves so that it does not leave gel-like undissolved components easily even with relatively weak heating and stirring. Since it can be completely dissolved, it has been widely used as a binder resin.

  However, in recent years, from the viewpoint of the global environment, the production method of vinyl chloride resin has shifted from solution polymerization using an organic solvent to suspension polymerization using water. Sometimes it becomes. Therefore, the necessity to use a vinyl acetate resin produced by suspension polymerization as a binder resin has increased.

  However, the resin particles of vinyl chloride resin produced by suspension polymerization have few voids as seen in the resin particles of vinyl chloride resin produced by solution polymerization and dissolve gradually from the resin surface. There is a problem that the solvent cannot penetrate into the resin, the solubility in the organic solvent is low, the solution is not completely dissolved by ordinary stirring, and the gel-like undissolved component remains.

  In addition, a water-soluble dispersant is generally used when producing a vinyl chloride resin by suspension polymerization, which causes a decrease in the solubility of the vinyl chloride resin in an organic solvent. Examples of water-soluble dispersants include water-soluble cellulose ethers such as hydroxyalkylalkyl cellulose, water-soluble cellulose esters such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose, water-soluble water such as partially saponified polyvinyl alcohol, acrylic acid polymer, and gelatin. Generally, a water-soluble resin such as a conductive polymer is used. Such a dispersant is difficult to dissolve in a specific organic solvent, and depending on the amount added, it may remain and hinder the dissolution of the vinyl chloride resin in the organic solvent.

  If the dissolution of the vinyl chloride resin is insufficient, a part of the vinyl chloride resin becomes a gel-like undissolved component. If the ink for inkjet recording contains a lot of gel-like undissolved components, it becomes difficult to maintain stable ejection performance of ink droplets ejected from the recording head. Further, when ink droplets are ejected from the recording head at a high frequency of 10.5 kHz or higher, the problem becomes more prominent. In addition, the gel-like undissolved component adheres to the vicinity of the nozzle opening of the recording head, the landing deviation caused by the ink droplet being bent and discharged, and the ink is not discharged due to the nozzle opening clogging. It will cause the quality to deteriorate. In addition, the gel-like undissolved component is clogged in the recording head, which may cause the ink to not be supplied normally. Furthermore, the gel-like undissolved component is physically bonded to the pigment in the ink for ink jet recording, and the dispersibility of the pigment may be impaired, which may cause an adverse effect on the storage stability of the ink.

  Since the gel-like undissolved component is softly deformed and split, it is extremely difficult to sufficiently remove it by filtration. Even when the ink is filtered, the gel-like undissolved component remains in the ink. Therefore, the gel-like undissolved component needs to be sufficiently dissolved.

  For example, Patent Document 1 discloses an inkjet recording ink using a vinyl acetate resin as a binder resin and using an organic solvent having a specific structure in combination with a lactone compound.

JP 2007-23265 A

  However, although the vinyl chloride resin is used as the binder resin in the ink jet recording ink of Patent Document 1, details of the step of dissolving the binder resin and the gel-like undissolved component are not described. When a vinyl acetate resin produced by turbid polymerization is used, it is considered that a gel-like undissolved component may remain in the ink. The vinyl chloride resin used in Patent Document 1 is produced by solution polymerization, and can be easily dissolved without leaving a gel-like undissolved component. In addition, if a vinyl acetate resin produced by suspension polymerization is used, it may be possible to increase the amount of a highly soluble lactone compound in order to sufficiently dissolve the vinyl acetate resin. If a large amount is used, the surface of the PVC base material is excessively dissolved, resulting in a problem that the gloss of the printed surface is impaired.

  Moreover, even if it mixes and stirs the solvent and the vinyl chloride resin manufactured by suspension polymerization, a vinyl chloride resin will become a lumpy shape. A dama is an aggregate of resin particles. If the surface of the dam is damped before the addition of the solvent, if the resin particles whose surfaces have been softened with the solvent after the addition of the solvent coalesce, the resin particles whose surface has been softened with the solvent after the addition of the solvent and the solvent will soak. In the case where the resin particles that are not combined are combined, and the lumps are combined and become larger, there are combinations thereof. The inside of these lumps present in the solvent contains dry resin particles and air, and is low in transparency and white. When the resin particles are small, there are many lumps in the state before the addition. A gel-like substance is an undissolved component of a resin that cannot be completely dissolved in a solvent, and is resin particles and lumps that have been made transparent by penetration of the solvent into the interior. These gel-like substances are soft and elastic because the solvent penetrates to the inside. If these lumps or gel-like substances are contained in the ink, it causes ejection failure of the inkjet head.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and for example, glycol monoacetates, glycol ethers and the like are dissolved in a vinyl acetate resin produced by suspension polymerization. Use low-solubility solvent as the main solvent, suppress the use of high-solubility solvent, and use vinyl chloride resin produced by suspension polymerization as binder resin, so that the gel-like undissolved components do not cause ejection failure Thus, it is possible to easily obtain the ink solvent of the ink jet recording ink thus dissolved, and to provide a production method thereof. In addition, the ink solvent is not used to dissolve the surface of the PVC substrate excessively, the glossiness of the printed matter is not impaired, the adhesiveness is excellent, and undissolved components cause ejection failure. Ink jet recording ink capable of stably ejecting ink from a recording head is provided, and a manufacturing method thereof is provided. In addition, an ink cartridge storing the ink for ink jet recording and a manufacturing method thereof are provided.

In order to achieve the above object, a method for producing an ink solvent according to the present invention includes a glycol monoacetate, a glycol ether, or the glycol monoacetate as an ink binder resin containing a vinyl acetate resin produced by suspension polymerization. A method for producing a solvent for ink in which a mixed liquid of alcohol and the glycol ether is dissolved in a solvent containing a main solvent, and the vinyl chloride resin is charged into a mixing tank of a mixer equipped with a blade The vinyl chloride resin in the mixture of the vinyl chloride resin and the solvent is 30 wt% or more and 70 wt% or less while rotating the blade in the mixing tank into which the vinyl chloride resin is charged. A solvent charging step in which a predetermined amount of the solvent is dropped or sprayed; and after the predetermined amount of the solvent is charged, the blade is rotated to A mixing step of mixing the resin and the solvent so as to form a viscous material, and the solvent is instilled or sprayed into the mixing tank containing the mixture while rotating the blade. A solution, and a dilution step of diluting the vinyl chloride resin in the solution to be 10 wt% or more and 15 wt% or less, stirring the diluted solution at a predetermined temperature, and stirring the gel-like salt the vinyl acetate resin have a, a melting step to sufficiently soluble in said solvent, said solvent adding step and the mixing step, the temperature of said mixture and said to Rukoto and 10 ° C. or higher 50 ° C. or less.

Further, the method for producing an ink for inkjet recording of the present invention comprises a step of producing an ink solvent by the above-described method for producing an ink solvent , and mixing the ink solvent with a pigment dispersion using the ink solvent as an ink solvent. And
The ink cartridge manufacturing method of the present invention includes the steps of manufacturing an ink jet recording ink by the above ink jet recording ink manufacturing method, storing the ink jet recording ink in a pouch, and storing the pouch in a case. It is characterized by including.

  The present invention uses a vinyl chloride resin produced by suspension polymerization, uses an organic solvent having low solubility as a main solvent, and is sufficiently dissolved so as not to cause ejection failure due to a gel-like undissolved component. An ink solvent for the ink can be provided. Ink-jet recording ink containing the ink solvent does not impair the gloss of the printed material with respect to the PVC substrate, and has excellent adhesion and stable ejection when the recording head is driven in a high-frequency region. Has performance. In addition, the present invention can easily discharge gel-less undissolved components in a simple and short time process using a low-solubility solvent without problems even if an inkjet head is used in a high-frequency region. It can be dissolved sufficiently.

FIG. 1 is a process diagram of the present invention. FIG. 2 is an exploded perspective view of an ink cartridge according to a preferred embodiment of the present invention.

Embodiments of the present invention will be specifically described below.
Ink for ink jet recording needs to contain a binder resin, an organic solvent, a pigment, and a pigment dispersant.

  Ink jet recording ink contains a binder resin in order to provide adhesion to the PVC substrate. It is preferable that the binder resin contains a vinyl acetate resin because adhesion with the base material of the recording medium is improved. Furthermore, other resins such as a polyester resin, an acrylic resin, and a urethane resin can be included as a binder resin according to the intended use of the ink. It is necessary that a vinyl acetate resin is included in the adhesion to polyvinyl chloride used as a PVC base material used for outdoor postings and the like.

  There are several production methods for vinyl chloride resin such as solution polymerization, emulsion polymerization, suspension polymerization and the like. Specific examples of the vinyl acetate resin produced by solution polymerization include Yuker Solution vinyl resins VYHD, VYHH, VMCA and the like manufactured by Dow Chemicals. Specific examples of the vinyl chloride resin produced by suspension polymerization include Solvein CL, CNL, C5R, TA3, TA5R manufactured by Nissin Chemical Industry Co., Ltd., and Vinol H14 / 36, H15 / 45 manufactured by Wacker Chemie.

  The molecular weight A of the vinyl acetate resin produced by suspension polymerization used as the binder resin is preferably in the range of 20000 ≦ A ≦ 30000. When the molecular weight A is less than 20,000, the adhesion to the PVC base material is lowered, and thus the chemical resistance and physical resistance of the printed matter are impaired, which is not preferable. When the molecular weight A exceeds 30000, the stable ejection performance by the recording head is impaired, which is not preferable.

  Further, as the binder resin, other types of resins can be used in combination with the vinyl acetate resin produced by suspension polymerization. For example, acrylic resins including styrene-acrylic resins, epoxy resins, phenol resins, novolac resins, rosin-modified phenol resins, amino resins such as melamine and benzoguanamine, polyamide resins, cellulose diacetate, cellulose triacetate, nitrocellulose, cellulose nitrate Cellulose ester resins such as cellulose propionate and cellulose acetate butyrate, and cellulose ether resins such as methylcellulose, ethylcellulose, benzylcellulose, tritylcellulose, cyanethylcellulose, carboxymethylcellulose, carboxyethylcellulose, and aminoethylcellulose It is preferably used in combination with a modified acrylic copolymer.

  The content B of the vinyl acetate resin produced by suspension polymerization in the ink for inkjet recording is preferably in the range of 1% by weight ≦ B ≦ 20% by weight. When the content of the vinyl acetate resin produced by suspension polymerization in the ink for ink jet recording is less than 1% by weight, the adhesiveness with the PVC substrate may be insufficient, and when the content is more than 20% by weight. Is not preferable because the viscosity of the ink for inkjet recording becomes high and stable discharge performance cannot be maintained. Further, the content B of the vinyl acetate resin produced by suspension polymerization in the ink for inkjet recording is particularly preferably in the range of 3 wt% ≦ B ≦ 10 wt%. If it is this range, even if the discharge frequency of a recording head is a high frequency area | region, it can discharge favorably.

  The organic solvent that dissolves the binder resin uses one or a mixture of glycol monoacetates and glycol ethers as a main solvent that accounts for 50% by weight or more in the solvent.

  For example, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, Ethylene glycol monomethyl ether propionate, ethylene glycol monoethyl ether propionate, ethylene glycol monobutyl ether propionate, diethyl diglycol, diethylene glycol dialkyl ether, tetraethylene glycol dialkyl ether, Ethylene glycol monomethyl ether propionate, diethylene glycol monoethyl ether propionate, diethylene glycol monobutyl ether propionate, propylene glycol monomethyl ether propionate, dipropylene glycol monomethyl ether propionate, ethylene glycol monomethyl ether butyrate, ethylene glycol mono Ethyl ether butyrate, ethylene glycol monobutyl ether butyrate, diethylene glycol monomethyl ether butyrate, diethylene glycol monoethyl ether butyrate, diethylene glycol monobutyl ether butyrate, propylene glycol monomethyl ether butyrate, dipropylene glycol monomethyl ether butyrate Which glycol monoacetates, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl methyl ether, diethylene glycol Dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene Glycol monoethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether, ethylene glycol monomethyl acetate, ethylene glycol monoethyl acetate, ethylene glycol monobutyl acetate, diethylene glycol monomethyl acetate, ethylene glycol monomethyl Ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl Seteto, triethylene glycol monobutyl ether, glycol ethers such as tetraethylene glycol dimethyl ether, and the like.

The proportion of the auxiliary solvent in the solvent is desirably 10% by weight or less, and more preferably, the lactone type or other highly soluble solvent is less than 1% by weight. It is for suppressing the solubility with respect to a base material.
As the pigment used in the ink for ink jet recording, various pigments used in printing ink, paint, and the like can be used.

  For example, Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, Pigment Orange 16, 36, 38, 43, 51, 55, 59, 61, 64, 65, 71, Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 149, 168, 177, 178, 179, 206, 207, 209, 242, 254, 255, Pigment Violet 19, 23, 29, 30, 37, 40, 50, Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 30, 64, 80, Pigment Green 7 (chlorinated Russia Nin green), 36 (a brominated phthalocyanine green), Pigment Brown 23, 25, 26, Pigment Black 7 (carbon black), 26, 27, 28, etc., and the like. Specific examples of the pigment include LIONOL BLUE FG-7400G (phthalocyanine pigment manufactured by Toyo Ink Manufacturing Co., Ltd.), YELLOW PIGMENT E4GN (nickel complex azo pigment manufactured by Bayer Co., Ltd.), Chromophthal Pink PT (quinacridone pigment manufactured by BASF), ELFTEX 415 (Cavotdon pigment). Carbon black), Fastogen Super Magenta RG (quinacridone pigment made by DIC), YELLOW PIGMENT E4GN (nickel complex azo pigment made by LANXESS), Monarch 1000 (carbon black made by Cabot), Irgarite Blue 8700 (phthalocyanine made by BASF) Pigment), E4GN-GT (a nickel complex azo pigment manufactured by LANXESS), and the like.

  The blending amount of the pigment can be arbitrarily determined depending on the kind of the pigment to be used, but the content in the ink is usually 0.1 to 15% by weight, preferably 0.5 to 10% by weight. The average particle diameter of the pigment is preferably 50 to 400 nm, more preferably 80 to 300 nm. The average particle diameter is obtained by measuring the average particle diameter (d50) using a laser diffraction particle size distribution analyzer.

  The pigment dispersant used in the ink for inkjet recording is polyamide resin, hydroxyl group-containing carboxylic acid ester, salt of long chain polyaminoamide and high molecular weight acid ester, salt of high molecular weight polycarboxylic acid, long chain polyaminoamide and polar acid ester Salt, high molecular weight unsaturated acid ester, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester Polyoxyethylene nonylphenyl ether, stearylamine acetate and the like can be used.

  Specific examples of the pigment dispersant include Solsperz 5000 (phthalocyanine ammonium salt type), 13940 (polyesteramine type), 17000 (fatty acid amine type), 24000 (apolyalkyleneimine type), 32000 (polyester polyamide type) manufactured by Lubrizol. ), Ajinomoto Fine Techno Co., Ltd., Ajisper PB821, PB822 (basic dispersant), and the like.

As the additive used for the ink for ink jet recording, a plasticizer, a surface conditioner, an ultraviolet light inhibitor, a light stabilizer, an antioxidant, and the like can be used.
The ink solvent is free from lumps and large gel substances, and the gel substances need to be sufficiently dissolved.
The method for producing the ink solvent will be described below. FIG. 1 is a process diagram for producing an ink solvent. Each step for producing the ink solvent will be described.

  The resin charging process is a process of charging the vinyl acetate resin produced by suspension polymerization of the granular material into the mixing tank of the mixer (step S1). When the resin is put into the mixing tank of the mixer, it is thrown in while removing the resin that has been stagnant from the beginning. This is because it dissolves efficiently in the subsequent steps. To get rid of lumps when adding resin, it is better to add it while applying physical force. Specifically, there are a method in which the dropping energy of the resin is used to pass through a coarse wire mesh and a method in which a funnel having a projection on the side wall is passed through.

When all the desired resins are charged, the process proceeds to the solvent charging step of Step S2, which is the next step.
The solvent charging step is a step of charging the solvent into the mixing tank of the mixer charged with the resin (step S2).

  It is necessary to add the solvent little by little so that the solvent uniformly permeates the surface of the resin particles. This is because if the charged solvent does not soak into the resin particles uniformly, the resin particles soaked with the solvent and the resin particles not soaked are combined to become lumps. As a method for introducing the solvent while uniformly impregnating the surface of the resin particles with the solvent, there is a method for introducing the solvent by spraying or instillation.

  Furthermore, it is necessary to add the solvent while rotating the blade in the mixing tank. By introducing the solvent while rotating the blade, the resin introduced in step S1 can be convected in the mixing tank, and the solvent can be uniformly infiltrated into the surface of the resin particles.

  Moreover, spraying is a manual method of pouring the solvent in the form of a mist. When the solvent is sprayed in a state containing air, the resin particles may be danced by the wind pressure of the air, so airless spraying is preferable. In addition, the drip injection is a method in which the solvent is dropped into a droplet having a diameter of 10.0 mm or less. In this way, the resin surface can be uniformly impregnated by intermittently adding small amounts instead of continuously.

  Furthermore, it is preferable that the temperature of a solvent and resin is 50 degrees C or less. This is because when a solvent exceeding 50 ° C. is instilled or when a solvent is instilled into a resin exceeding 50 ° C., the resin particles instantly absorb the solvent and the surface becomes soft, and the resin particles are bonded together. Because it becomes. If the temperature of a solvent and resin is 50 degrees C or less, it can suppress that the surface of a resin particle absorbs a solvent instantaneously. When the rotation speed of the blade is high, heat is generated by shearing force, and therefore it is necessary to maintain the rotation speed that can be maintained at 50 ° C. or less. Alternatively, the temperature is controlled to be kept at room temperature, for example, 20 ° C. to 50 ° C. or less by using a cooling device capable of controlling the temperature of the mixing tank. Moreover, although it is not necessary to control cooling too much, it is preferable to control so that it may become 10 degreeC or more.

  The kind of mixer that can be used in the present invention can obtain a strong shearing force even at a high viscosity of about 1000 Pa · s. For example, a kneader or a planetary (planetary) mixer can be selected and used.

  For example, a kneader equipped with a Banbury type blade exhibits excellent performance in mixing high-viscosity materials and ultrahigh-viscosity materials. This type of kneader can obtain strong shear forces that occur between the blades and between the blades and the mixing layer. Due to this shearing force, the resin particles are torn and the solvent is added little by little, so that the resin surface can be uniformly infiltrated.

  The planetary mixer also has a plurality of blade shafts, and the blades provided on the shafts are planetarily moved in the mixing tank to mix the powder and liquid to create a viscous material. Powerful stirring and kneading. Furthermore, since the solvent is added little by little, the resin surface can be uniformly infiltrated. The mixing tank preferably has a cylindrical shape with a flat bottom, and the blade used is preferably a frame-type blade. Furthermore, it is preferable that the tip of the frame-shaped blade has a rod shape, the longitudinal direction thereof is horizontal with respect to the bottom surface of the mixing tank, and the horizontally disposed tip rotates along the bottom surface.

Furthermore, a scraper that scrapes off the resin adhering to the wall surface of the mixing tank can be mounted.
When all the desired solvents have been added, the process proceeds to the mixing process of step S3, which is the next process. The mixing process is a process of making a viscous material by injecting the solvent into the resin particles and bonding the resin particles to each other by the strong shearing force that occurs between the blades and between the blades and the mixing tank after adding the solvent in step S2. Yes (step S3).

  In the mixing step, the amount of solvent permeation into the resin particles differs in the initial, middle and final stages of mixing. Immediately after the completion of the addition of the solvent, which is the start of the mixing process, the solvent is infiltrated uniformly into the surface of the resin particles, and the solvent hardly penetrates into the resin particles. Therefore, the resin particles are not bonded to each other and the whole is not a viscous body, and the resin is simply wet. The middle stage of the mixing process is a state in which the solvent gradually permeates toward the inside of the resin particles, and the surface of the resin particles becomes soft. for that reason. The softened resin particles are bonded to each other to partially become a viscous material. In the middle of the mixing process, the solvent does not penetrate into the resin particles. At the end of mixing, the solvent sufficiently penetrates into the interior of the resin particles, and the whole becomes a viscous body in a state where the resin particles are bonded to each other and no lumps are present. However, the mixture in which air is taken in during mixing is white and it is difficult to visually confirm the presence or absence of lumps. As a method for confirmation, there is a method in which the mixture is heated to remove the air taken in by lowering the viscosity and visually confirmed. After the entrapped air is removed, the appearance of the mixture is highly transparent if no lumps are present. The concentration of the vinyl chloride resin in the mixture during mixing is preferably 30% by weight or more and 70% by weight or less. When the concentration of the vinyl chloride resin exceeds 70% by weight, the amount of the solvent is small and it does not penetrate sufficiently to the center of the resin particles, which is not preferable. Furthermore, when it is less than 30% by weight, the viscosity is low, and the shearing force of the mixer cannot be sufficiently obtained, which is not preferable. A concentration of around 50% by weight, that is, a concentration of 45% by weight or more and 55% by weight or less can be suitably mixed and is particularly preferable.

  Furthermore, the temperature of the mixture during mixing is preferably 20 ° C. to 50 ° C. at room temperature. What is necessary is just 10 degreeC or more. This is because there is no need to cool excessively, and when mixing is performed at a temperature exceeding 50 ° C., the resin particles instantaneously absorb the solvent and the surface becomes soft. The softened resin particles combine with unabsorbed resin particles to become lumps. If the temperature of a solvent is 50 degrees C or less, it can suppress that the surface of a resin particle absorbs a solvent instantaneously.

  Further, the mixing time depends on the resin concentration. For example, when the resin concentration is 50% by weight, mixing is preferably performed for 30 minutes or more, and particularly preferably mixing for 60 minutes or more. When the mixing time is less than 30 minutes, the solvent does not penetrate to the center of the resin particles, which is not preferable.

  When a planetary mixer is used as the mixer, the rotation speed of the blade is preferably 20 to 80 rpm, particularly preferably 30 to 60 rpm. At this time, mixing can be suitably performed. Further, the revolution speed of the blade can be determined by the ratio of the revolution speed / revolution speed of the blade. The ratio C of rotation speed / revolution speed of the blade is preferably 1.0 ≦ C ≦ 3.0. If the rotational speed is less than 20 revolutions per minute, the resin in the mixing tank is not sufficiently stirred, and the resin particles cannot be uniformly impregnated with the solvent. Further, if the rotational speed is used at a rotational speed exceeding 80, the amount of heat generation becomes excessive and it becomes difficult to maintain a desired temperature. If the rotation speed / revolution speed ratio C is less than 1.0, or if the rotation speed / revolution speed ratio exceeds 3.0, the mixing of the resin in the mixing tank becomes insufficient and the solvent is uniformly distributed in the resin particles. It cannot be soaked. If the temperature does not exceed the desired temperature, the blade rotation speed can be increased even during mixing.

  If a desired mixture is obtained, it will transfer to the dilution mixing process by the mixer of step S4 which is the next process. The dilution mixing process by the mixer is a process in which a solvent is further added to the mixture obtained in step S3, and the mixture is diluted so that the vinyl acetate resin concentration in the mixture becomes 10 wt% or more and 15 wt% or less while mixing ( Step S4). The mixer continues to be used from step S3. The solvent is dropped or sprayed while rotating the blade. After the completion of the addition of the solvent, the blade may be further rotated and stirred.

  If the solvent is continuously added quickly, the viscosity will drop abruptly in part, so the mixer will not be able to give a uniform shearing force to the whole, and the mixture obtained in step S3 will break up, in the solvent and in the mixing tank This is not preferable because it remains as a large gel substance on the wall surface.

  Furthermore, it is preferable that the temperature at the time of dilution by a mixer is 50 degreeC or more. This is because the application of heat energy improves the dilution mixing efficiency. However, from the viewpoint of safety, it is preferable to heat the solvent within a range not exceeding the flash point of the solvent. It is preferable to set it at 70 degrees C or less.

  After dilution mixing to a desired concentration, the process proceeds to a finishing process using a disperser. The finishing process by the disperser is a process of dispersing and dissolving the small fragments that have not been soaked into the solvent in the process of step S4 to a problem-free level (step S5).

  If the steps up to step 4 are not carried out, that is, if the gel-like residue is dissolved without leaving a residue only in step S5, in order to dissolve in a state where a lot of lumps and gel-like substances remain, 5 to 10 It takes about twice as long. Or in some cases, it cannot be dissolved. By performing the steps up to step 4, the resin can be efficiently dissolved in a short time.

  The fission remaining in step 4 is a very soft gel in which the solvent is sufficiently permeated, so that it disperses and dissolves easily when given an appropriate spring force. However, it is preferable that the disperser efficiently gives a shearing force at 5 Pa · s or less. For example, a homomixer, a thin film swirl method high-speed stirrer, a bead mill, an ultrasonic disperser, a pressure homogenizer, a continuous ultrasonic homogenizer, and the like.

  The treatment temperature is more effective for dissolution as the organic solvent temperature is higher. However, the temperature of the organic solvent is preferably dissolved below the flash point from the viewpoint of safety. Furthermore, from the viewpoint of the binder performance of the vinyl chloride resin, the temperature is preferably equal to or lower than the temperature at which the chlorine atom of the vinyl acetate resin is desorbed.

  Whether the resin is dissolved or not can be determined by the viscosity of the ink solvent and the number of gel-like undissolved components in the ink solvent. Become. If the concentration of the suspension polymerization vinyl chloride resin in the mixture of the suspension polymerization vinyl chloride resin and the solvent is 10% by weight, the viscosity is preferably dissolved to less than 0.0250 Pa · s. In any case, it is possible to stably discharge with an ink jet recording head when the ink is made into an ink for ink jet recording, so that the viscosity of the system is as low as possible and the gel-like undissolved component is minimized. It is preferable for obtaining performance.

  The number of gel-like undissolved components in the ink solvent can be determined by gravity filtration of the ink solvent. In the case of an ink solvent having a concentration of 10% by weight of the suspension polymerization PVC resin in a mixture of the suspension polymerization PVC resin and the solvent, 200 ml of the ink solvent is passed through a circular 8 μm mesh having a diameter of 35 mm by gravity filtration. Then, the number of gel-like undissolved components captured by the filter is confirmed. The number of gels per 200 ml of ink solvent is preferably less than 10 and more preferably less than 5. When 10 or more are captured, it is not preferable because stable ejection performance cannot be obtained. When the number of gels is less than 10, stable ejection can be performed, which is substantially the same as having no gel. When discharging at high frequency, less than 5 is preferable.

  The above is the manufacturing process of the ink solvent. Next, the manufacturing process of the ink for inkjet recording will be described. An ink solvent and a solvent are added to a pigment dispersion prepared in advance by mixing a pigment, a pigment dispersant, and a solvent to obtain an ink for inkjet recording. At this time, additives are added as necessary.

  The process for producing the ink for ink jet recording can use a stirrer to mix the solvent for ink with the pigment dispersion, magnetic stirrer, three-one motor, homomixer, nanomizer, resolver, disper, high speed impeller. Disperser etc. are mentioned. Examples of media dispersion include a ball mill, an attritor, a basket mill, a signed mill, a sand blinder, a dyno mill, a disperse mat, an SC mill, a spike mill, an agitator mill, and a glen mill.

  In addition, trace amounts of water-soluble dispersants such as water-soluble cellulose ether, water-soluble cellulose ester, and water-soluble resin remain in the vinyl acetate resin produced by suspension polymerization used in ink jet recording ink. For example, the residual amount varies slightly depending on the manufacturing process, but remains in a weight ratio of about 50 ppm to 10000 ppm. Therefore, a small amount of these is also contained in the manufactured inkjet recording ink. This residue will use an amount of PVC resin that does not affect the solvent for ink and its production, ink for inkjet and its production.

Further, the ink for ink jet recording is used in a state of being stored in an ink cartridge in an ink jet recording apparatus. The ink cartridge will be described with reference to FIG.
FIG. 2 is an exploded perspective view of an ink cartridge according to a preferred embodiment of the present invention.

  The ink cartridge 1 includes a flexible pouch (ink bag) 2 in which ink for ink jet recording is accommodated, and an upper case 3 and a lower case 4 in which the pouch 2 is accommodated. In the pouch 2, ink for ink jet recording is stored. The upper case 3 and the lower case 4 are fitted together, and the pouch 2 is stored inside. Pouch 2 has two layers of aluminum foil to improve gas barrier properties, for example, two aluminum laminate films sandwiched between nylon film on the outside and polyethylene film on the inside, and the periphery is joined by thermal welding or the like Is made up of. One end of the pouch 2 is provided with an ink outlet 5 for discharging the ink contained therein to the outside. In order to supply the ink in the pouch 2 to the outside, the lower case 4 is provided with a hole through which the ink outlet 5 is exposed. The ink cartridge 1 is manufactured by a process including a process of filling the pouch 2 with ink for ink jet recording and storing it, and a process of storing the pouch 2 in the upper case 3 and the lower case 4. Further, the ink filling preferably includes a step of putting ink in an opening of the pouch 2 in a vacuum chamber, degassing, and sealing the opening. The ink cartridge 1 shown in FIG. 2 that accommodates ink for inkjet recording is a preferred embodiment of the ink cartridge of the present invention, but the ink cartridge of the present invention is not limited to this form of ink cartridge.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not particularly limited to the examples. In the examples, “part” represents “part by weight”.

  The ink for inkjet recording is prepared by preparing a pigment dispersion in advance by mixing a pigment, a pigment dispersant, and a solvent, and adding an ink solvent, an organic solvent, and other additives. In the ink-jet recording ink production process, an ink solvent and an organic solvent were added to a pigment dispersion in which a pigment had been dispersed in advance, and the mixture was stirred at a rotation speed of 1200 rpm for 4 hours using a stirrer while heating to 60 ° C. For the ink for inkjet recording, a binder resin, an organic solvent, a pigment, a pigment dispersant, and a pigment dispersion solvent were prepared so that the total amount was 100 parts. The composition of the ink for inkjet recording is summarized in Table 1.

Example 1
The ink solvent is prepared according to steps S1 to S5 of the ink solvent manufacturing method described above.
In step S1, the cooling part of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade is cooled by passing cooling water at 10 ° C., and the vinyl chloride produced by suspension polymerization is supplied to the mixing tank. 715 g of resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In Step S2, 715 g of ethylene glycol monobutyl ether acetate was infused over 18 minutes while rotating the Banbury blade blade at 40 rpm.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 25 ° C.
In Step S4, 1144 g of the mixture in the mixing tank was removed, the cooling unit was heated to 70 ° C., and 1144 g of ethylene glycol monobutyl ether acetate was infused over 30 minutes while rotating the blade at 40 rpm, for 30 minutes. The blade was rotated.
In step S5, 1000 g of the mixture obtained in step S4 was collected in a beaker with a capacity of 2 liters, and heated at 70 ° C. for 10 minutes using a homomixer while heating the mixture to 70 ° C. using a hot plate, and the mixture was used for ink. A solvent was obtained. The viscosity of the ink solvent decreased to 0.0235 Pa · s, and the number of gel-like residues in 200 ml was less than 5. The ink solvent manufacturing process is thus completed. Using this ink solvent, an ink for inkjet recording is prepared so that the composition is the same as in Table 1. The viscosity of the ink for ink jet recording was 0.0105 Pa · s.

(Example 2)
Steps S1 to S3 were performed in the same manner as in Example 1.
In step S4, it carried out like Example 1 except having changed the cooling part of the mixing tank into 50 degreeC.
In Step S5, 1000 g of the mixture obtained in Step S4 was collected in a mixing tank of a batch type medialess disperser DESPA MILL MD-3 (manufactured by Asada Tekko Co., Ltd.). The cooling part was heated to 50 ° C. and rotated at a speed of 15000 rpm (circumferential speed 40 m / s) for 5 minutes to obtain an ink solvent. The viscosity of the ink solvent was reduced to 0.0230 Pa · s, and the amount of gel-like residue was less than 5 per 200 ml. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Example 3)
In step S1, it carried out like Example 1 except having changed the cooling part of the mixing tank to 25 degreeC.
Steps S2 and S3 were performed in the same manner as in Example 1. The maximum temperature of the Step 3 mixture was 50 ° C.
Steps S4 and S5 were performed in the same manner as in Example 1. The viscosity of the ink solvent obtained in step S5 decreased to 0.0238 Pa · s, and the number of gel-like residues in 200 ml was less than 5. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

Example 4
In step S1, the cooling part of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade is cooled by passing cooling water at 10 ° C., and the vinyl chloride produced by suspension polymerization is supplied to the mixing tank. 429 g of resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In step S2, 1001 g of ethylene glycol monobutyl ether acetate was infused over 50 minutes while rotating the Banbury blade blade at 40 rpm.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 25 ° C.
In step S4, the cooling part of the mixing tank was heated to 70 ° C., and 1430 g of ethylene glycol monobutyl ether acetate was added dropwise over 20 minutes, and then the blade was rotated for 30 minutes.
In Step S5, 1000 g of the mixture obtained in Step S4 was collected in a mixing tank of a batch type medialess disperser DESPA MILL MD-3 (manufactured by Asada Tekko Co., Ltd.). The cooling section was heated to 70 ° C. and rotated at a speed of 15000 rpm (circumferential speed 40 m / s) for 5 minutes to obtain an ink solvent. In order to evaluate the solvent for ink, it was diluted to 10% by weight, the viscosity was lowered to 0.0230 Pa · s, and there were less than 5 gel-like residues per 200 ml. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Example 5)
In step S1, the cooling part of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade is cooled by passing cooling water at 10 ° C., and the vinyl chloride produced by suspension polymerization is supplied to the mixing tank. 1001 g of resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In Step S2, 429 g of ethylene glycol monobutyl ether acetate was infused over 20 minutes while rotating the Banbury blade at 40 rpm.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 50 ° C.
In step S4, 1144 g of the mixture in the mixing tank was removed, the cooling part was heated to 70 ° C., 1254 g of ethylene glycol monobutyl ether acetate was added dropwise over 30 minutes, and then the blade was rotated for 30 minutes.
In Step S5, 1000 g of the mixture obtained in Step S4 was collected in a mixing tank of a batch type medialess disperser DESPA MILL MD-3 (manufactured by Asada Tekko Co., Ltd.). The cooling section was heated to 70 ° C. and rotated at a speed of 15000 rpm (circumferential speed 40 m / s) for 5 minutes to obtain an ink solvent. In order to evaluate the solvent for ink, it was diluted to 10% by weight, the viscosity was lowered to 0.0233 Pa · s, and less than 5 gel-like residues per 200 ml. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Example 6)
Steps S1 to S3 were performed in the same manner as in Example 1.
In Step S4, 1144 g of the mixture in the mixing tank was removed, the cooling unit was heated to 70 ° C., and 1144 g of ethylene glycol monobutyl ether acetate was added dropwise over 95 minutes, and then the blade was rotated for 30 minutes.
In step S5, using a continuous ultrasonic disperser ULTRASONIC GENERATOR GSD1200AT (manufactured by Ginsen Co., Ltd.), an irradiation unit holder is attached to the tip of an ultrasonic irradiation unit having a tip diameter of 50 mm, and 1 l of the mixture obtained in step S4 is added. Put into the storage tank, circulate the ultrasonic generator and storage tank for 1 minute at a flow rate of 1 L / min, and irradiate the ultrasonic wave with ultrasonic frequency of 19.5 kHz and amplitude of 30 μm to obtain the solvent for ink It was. The viscosity of the ink solvent decreased to 0.0227 Pa · s, and the number of gel-like residues in 200 ml was less than 5. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Example 7)
In step S1, the T.F. equipped with a flat blade and a twist blade are mounted. K. The cooling part of the mixing tank of Hibismix 2P-03 (manufactured by Primics) was cooled by passing cooling water at 10 ° C., and the vinyl chloride resin (Nisshin Chemical Industry Co., Ltd.) produced by suspension polymerization in the mixing tank 71.5 g of Solvain CL (molecular weight: 25000) was added to the mixing tank.
In step S2, 71.5 g of ethylene glycol monobutyl ether acetate was sprayed in over 30 minutes while rotating the flat blade and the twisting blade at 50 rotations per revolution and 20 rotations per revolution.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 25 ° C.
In step S4, the cooling part of the mixing tank was heated to 70 ° C., and 572 g of ethylene glycol monobutyl ether acetate was added dropwise over 30 minutes, and then the blade was rotated for 30 minutes.
In step S5, 700 g of the mixture obtained in step S4 was collected in a beaker with a capacity of 2 liters, and heated at 70 ° C. for 10 minutes using a homomixer while heating the mixture to 70 ° C. with a hot plate, and the mixture was used for ink. A solvent was obtained. The viscosity of the ink solvent decreased to 0.0235 Pa · s, and the number of gel-like residues in 200 ml was less than 5. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 1)
In step S1, the cooling part of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade is cooled by passing cooling water at 10 ° C., and the vinyl chloride produced by suspension polymerization is supplied to the mixing tank. 1073 g of resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In Step S2, 357 g of ethylene glycol monobutyl ether acetate was instilled over 20 minutes while rotating the Banbury blade blade at 40 rpm.
In step S3, mixing was performed for 150 minutes. The maximum temperature of the mixture was 50 ° C.
In step S4, 1144 g of the mixture in the mixing tank was removed, the cooling unit was heated to 70 ° C., 1859 g of ethylene glycol monobutyl ether acetate was added dropwise over 60 minutes, and then the blade was rotated for 30 minutes.
Step S5 was performed in the same manner as in Example 1. The viscosity of the ink solvent was reduced to 0.0258 Pa · s, and the number of gel-like residues per 200 ml was 10 or more.
An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 2)
In step S1, the cooling part of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade is cooled by passing cooling water at 10 ° C., and the vinyl chloride produced by suspension polymerization is supplied to the mixing tank. 357 g of resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In Step S2, 1073 g of ethylene glycol monobutyl ether acetate was infused over 60 minutes while rotating the Banbury blade blade at 40 rpm.
In step S3, mixing was performed for 150 minutes. The maximum temperature of the mixture was 50 ° C.
In step S4, 715 g of the mixture in the mixing tank was removed, the cooling part was heated to 70 ° C., and 1070 g of ethylene glycol monobutyl ether acetate was added dropwise over 20 minutes, and then the blade was rotated for 30 minutes.
Step S5 was performed in the same manner as in Example 1. The viscosity of the ink solvent decreased to 0.0260 Pa · s, and the number of gel-like residues in 200 ml was 10 or more.
An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 3)
In step S1, the cooling section of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade was cooled by passing cooling water at 30 ° C. 715 g of resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In Step S2, 715 g of ethylene glycol monobutyl ether acetate was infused over 18 minutes while rotating the Banbury blade blade at 40 rpm.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 55 ° C.
Steps S4 and S5 were performed in the same manner as in Example 1. The viscosity of the ink solvent obtained in step S5 was lowered to 0.0260 Pa · s, and the number of gel-like residues in 200 ml was 10 or more.
An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 4)
Step S1 was performed in the same manner as in Example 1.
In Step S2, 715 g of ethylene glycol monobutyl ether acetate was charged all at once while rotating the Banbury blade blade at 40 rpm.
Steps S3 to S5 were performed in the same manner as in Example 1. The maximum temperature of the mixture in step S3 was 30 ° C. The viscosity of the ink solvent obtained in step S5 was reduced to 0.0305 Pa · s, and the number of gel-like residues per 200 ml was 10 or more. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 5)
In step S1, the cooling part of the mixing tank of the pressure kneader DS1 (manufactured by Moriyama Co., Ltd.) equipped with a Banbury blade was cooled by passing cooling water at 10 ° C., and 715 g of ethylene glycol monobutyl ether acetate instead of resin was added to the mixing tank. I put it in.
In Step 2, 715 g of vinyl acetate resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) produced by suspension polymerization instead of solvent was charged over 10 minutes while rotating the Banbury blade blade at 40 rpm. did.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 25 ° C.
In Step S4, 1144 g of the mixture in the mixing tank was removed, the cooling unit was heated to 70 ° C., and 1144 g of ethylene glycol monobutyl ether acetate was added dropwise over 30 minutes, and then the blade was rotated for 30 minutes.
In Step S5, 1000 g of the mixture obtained in Step S4 was collected in a beaker in a mixing tank of a batch-type medialess disperser DESPA MILL MD-3 (manufactured by Asada Tekko). The cooling section was heated to 70 ° C. and rotated at a speed of 15000 rpm (circumferential speed 40 m / s) for 5 minutes to obtain an ink solvent. The viscosity of the ink solvent was reduced to 0.0292 Pa · s, and the number of gel-like residues per 200 ml was 10 or more. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 6)
Steps S1 to S4 were performed in the same manner as in Example 1.
Step S5 was not performed. The viscosity of the ink solvent was reduced to 0.0355 Pa · s, and the number of gel-like residues per 200 ml was 10 or more. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 7)
Steps S1 to S4 were performed in the same manner as in Example 1.
In Step 5, 1000 g of the mixture obtained in Step S4 was collected in a 2 liter beaker, and the mixture was rotated at 3000 rpm for 20 minutes using a disper while heating the mixture to 70 ° C. with a hot plate, and the solvent for ink was removed. Obtained. The viscosity of the ink solvent was reduced to 0.0296 Pa · s, and the number of gel-like residues per 200 ml was 10 or more. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

(Comparative Example 8)
In step S1, the cooling part of the mixing tank of ACM-2LVT (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with a spiral hook is cooled by passing cooling water at 10 ° C., and the salt produced by suspension polymerization in the mixing tank 71.5 g of vinyl acetate resin (Solvine CL molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.) was charged into the mixing tank.
In step S2, 71.5 g of ethylene glycol monobutyl ether acetate was sprayed in over 30 minutes while rotating the spiral hook at a rotational speed of 50 revolutions per revolution and 20 revolutions per revolution.
In step S3, mixing was performed for 120 minutes. The maximum temperature of the mixture was 25 ° C.
In step S4, the cooling part of the mixing tank was heated to 70 ° C., and 572 g of ethylene glycol monobutyl ether acetate was added dropwise over 30 minutes, and then the blade was rotated for 30 minutes.
In step S5, 700 g of the mixture obtained in step S4 was collected in a beaker with a capacity of 2 liters, and heated at 70 ° C. for 10 minutes using a homomixer while heating the mixture to 70 ° C. with a hot plate, and the mixture was used for ink. A solvent was obtained. The viscosity of the ink solvent decreased to 0.0235 Pa · s, and the number of gel-like residues in 200 ml was less than 5. An ink for ink jet recording was prepared using the ink solvent so that the composition was the same as in Table 1.

  The ink solvents and ink jet recording inks of Examples 1 to 7 and Comparative Examples 1 to 8 were evaluated according to the following criteria. The evaluation results are as shown in Table 2.

<Number of gel-like undissolved components in ink solvent>
The number of gel-like undissolved components in 200 ml of the ink solvent trapped by gravity filtering a circular 8 μm mesh metal filter having a diameter of 35 mm was evaluated. The results are classified as follows and shown in the table.
○: Less than 5 gel-like undissolved components.
Δ: The number of gel-like undissolved components was 5 or more and less than 10.
X: There were 10 or more gel-like undissolved components.

<Storage stability test of ink for inkjet recording>
The ink for inkjet recording was stored at 60 ° C. for 1 week, and the change rate was measured by measuring the viscosity before and after storage and the particle diameter of the pigment. The viscosity of the ink for inkjet recording was measured with a viscometer VISCOMETER TV-33 manufactured by Toki Sangyo Co., Ltd. The average particle diameter (d50) of the particle diameter of the pigment of the ink for inkjet recording was measured using a laser diffraction particle size distribution analyzer FPAR-1000K manufactured by Otsuka Electronics. The results are classified as follows and shown in the table.
A: The rate of change in both viscosity and particle size was less than ± 10%.
Δ: Change rate of at least one of viscosity and particle size was ± 10% or more.
X: Change rate of both viscosity and particle diameter was ± 10% or more.

<Continuous ejection performance test of ink for inkjet recording>
The continuous ejection performance was evaluated with a gray scale head for recording manufactured by SII Printec. The time for continuous ejection of the ink for ink jet recording at 2 drops at an ejection frequency of 18.5 kHz was measured. The results are classified as follows and shown in the table.
○: Continuous discharge was possible for 20 seconds or more.
Δ: Continuous discharge was normally performed for 10 seconds or more and less than 20 seconds.
X: Continuous discharge was normally performed for less than 10 seconds.

Here, an Example and a comparative example are compared.
In Comparative Example 1, since the resin concentration in the mixing process exceeded 70% by weight, 10 or more gel-like undissolved components were present in the ink solvent, and the viscosity increased. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.
In Comparative Example 2, since the resin concentration in the mixing step was less than 30% by weight, 10 or more gel-like undissolved components were present in the ink solvent, and the viscosity increased. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.
Since the temperature at the time of mixing exceeded 50 degreeC in the comparative example 3, 10 or more gel-like undissolved components existed in the solvent for ink, and the viscosity became high. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.
In Comparative Example 4, since the solvent was charged all at once in the solvent charging process of Step 2, there were 10 or more gel-like undissolved components in the ink solvent, and the viscosity increased. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.

In Comparative Example 5, the order of Step 1 and Step 2 was not followed, and the resin was added to the solvent. Therefore, 10 or more gel-like undissolved components were present in the ink solvent, and the viscosity increased. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.
Since Comparative Example 6 did not perform a dilution process using a dedicated mixer or a dispersion and dissolution process using a disperser, 10 or more gel-like undissolved components were present in the ink solvent, and the viscosity increased. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.
In Comparative Example 7, since a dilution-only mixer having a strong shearing force was not used in the dilution process using the dilution-only mixer, 10 or more gel-like undissolved components were present in the ink solvent, and the viscosity increased. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.
Comparative Example 8 uses a planetary mixer, but does not use a frame-type blade, so that there are 10 or more gel-like undissolved components in the ink solvent and the viscosity is high. Therefore, it turns out that the continuous discharge performance of the ink for inkjet recording is unsatisfactory.

In Example 1, the resin concentration in the mixing step is 50% by weight, and the maximum temperature of the mixture during mixing is 50 ° C. or less. Furthermore, a homomixer having a strong shearing force is used in the dilution process using a dedicated mixer for dilution. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.
In Example 2, the resin concentration in the mixing step is 50% by weight, and the maximum temperature of the mixture during mixing is 50 ° C. or less. Furthermore, a desperm with a strong shearing force is used in the dilution process using a dedicated mixer. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.
In Example 3, the resin concentration in the mixing step is 50% by weight, and the maximum temperature of the mixture during mixing is 50 ° C. or less. Furthermore, a homomixer having a strong shearing force is used in the dilution process using a dedicated mixer for dilution. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.
In Example 4, the resin concentration in the mixing step is 30% by weight, and the maximum temperature of the mixture during mixing is 50 ° C. or less. Furthermore, a desperm with a strong shearing force is used in the dilution process using a dedicated mixer. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.

In Example 5, the resin concentration in the mixing step is 70% by weight, and the maximum temperature of the mixture during mixing is 50 ° C. or less. Furthermore, a homomixer having a strong shearing force is used in the dilution process using a dedicated mixer for dilution. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.
In Example 6, the resin concentration in the mixing step is 50% by weight, and the maximum temperature of the mixture during mixing is 50 ° C. or lower. Furthermore, an ultrasonic homogenizer is used in a dispersion dissolution process using a disperser. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.
In Example 7, the resin concentration in the mixing step is 50% by weight, and a planetary mixer equipped with a flat blade and a twist blade is used. Furthermore, the maximum temperature of the mixture during mixing is 50 ° C. or less. Furthermore, a homomixer having a strong shearing force is used in the dilution process using a dedicated mixer for dilution. Ink-jet recording ink was prepared using a solvent for ink in which gel-like undissolved components were sufficiently dissolved in the mixing process and the dilution process using a dedicated dilution mixer, so stable continuous ejection performance and storage stability tests Sufficient stability could be obtained.

From the above, by following the process diagram shown in FIG. 1, it is possible to sufficiently dissolve the vinyl acetate resin produced by suspension polymerization efficiently in an organic solvent.
By comparing the results shown in Table 2, by using a vinyl acetate resin produced by suspension polymerization, an ink solvent in which a gel-like undissolved component is sufficiently dissolved and an ink for ink jet recording containing the ink solvent It can be seen that there is a manufacturing method for efficiently manufacturing the.

  The ink for ink jet recording of the present invention can be suitably applied to a large ink jet printer used for outdoor signboards such as a sign display using a large format.

1 Ink cartridge 2 Pouch 3 Upper case 4 Lower case 5 Ink outlet

Claims (7)

The binder resin of the ink containing the vinyl chloride resin produced by suspension polymerization is used as a solvent whose main solvent is one of glycol monoacetates, glycol ethers, or a mixture of the glycol monoacetates and the glycol ethers. A method for producing a dissolved ink solvent, comprising:
A charging step of charging the vinyl chloride resin into a mixing tank of a mixer equipped with a blade;
The predetermined content in which the vinyl chloride resin in the mixture of the vinyl chloride resin and the solvent is 30 wt% or more and 70 wt% or less while rotating the blade in the mixing tank in which the vinyl chloride resin is charged. A solvent charging step of instilling or spraying an amount of the solvent;
A mixing step of rotating the blade after mixing the predetermined amount of the solvent and mixing the vinyl chloride resin and the solvent so as to form a viscous material;
The solvent is instilled or sprayed into the mixing tank containing the mixture while rotating the blade to make the mixture into a solution, and the vinyl chloride resin in the solution is 10 wt% to 15 wt%. A dilution step of diluting to be:
Stirring the diluted solution at a predetermined temperature, and dissolving the gel-like vinyl acetate resin sufficiently in the solvent; and
I have a,
The solvent adding step and the mixing step, the manufacturing method of the ink solvent, wherein the temperature to Rukoto and 10 ° C. or higher 50 ° C. or less of the mixture.   The solution after the dissolving step is a gel-like undissolved component in 200 ml of the solution that is captured by gravity filtering an 8 μm mesh metal filter when the vinyl chloride resin in the solution is 10% by weight. The method for producing a solvent for ink according to claim 1, wherein the number is less than 10.   The method for producing a solvent for ink according to claim 1, wherein the vinyl chloride resin contains a water-soluble resin in a weight ratio of 50 ppm or more and 10,000 ppm or less. 5. The method for producing an ink solvent according to claim 1, wherein the predetermined temperature is 50 ° C. or more and 70 ° C. or less. 6. The method for producing a solvent for ink according to claim 1, wherein the vinyl acetate resin has a molecular weight of 20000 or more and 30000 or less. An ink solvent is produced by the method for producing an ink solvent according to any one of claims 1 to 6, the ink solvent, a pigment dispersion having at least a pigment and a pigment dispersant, and glycol monoester. A method for producing an ink for ink jet recording, comprising a step of mixing any solvent of acetates, glycol ethers, or a mixture of glycol monoacetates and glycol ethers. Producing an ink for ink jet recording by the method for producing ink for ink jet recording according to claim 7, and storing the ink for ink jet recording in a pouch;
And a step of storing the pouch in a case.

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