JP2012111071A - Method of cleaning ink-jet elastic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of cleaning ink-jet elastic member which does not cause failure with respect to the printing in ink-jet application.SOLUTION: The method of cleaning an ink-jet elastic member which contains at least one side of fatty acids and fatty acids derivatives includes: a cleaning first step of cleaning the elastic member by using a cleaning liquid 1 constituted of an aqueous solution which contains at least sodium hydroxide or potassium hydroxide and a nonionic or anionic surface active agent and has a pH of 11 or more while heating the cleaning liquid 1 to a temperature of 70°C or more; and a cleaning second step, which is performed after the cleaning first step, of cleaning the elastic member by using the cleaning liquid 2 constituted of an aqueous solution which contains at least a nonionic or anionic surface active agent while heating the cleaning liquid 2.

Description

  The present invention relates to a method for cleaning an elastic member for inkjet, and more particularly to a cleaning method for removing fatty acids and fatty acids contained in the elastic member.

  Examples of the elastic member used in the ink flow path of the ink jet recording head include seal parts, rubber plugs, and the like. Rubber, elastomer, and the like are used as these materials. Ink jet recording heads eject extremely small droplets, and therefore the diameter of the nozzle that ejects ink is small, for example, 10 μm or less. For this reason, when a foreign matter having a size of several μm is discharged from the elastic member constituting the ink flow path, the foreign matter may prevent ink ejection and cause a printing failure. Therefore, the elastic member in contact with the ink used in the ink flow path of the ink jet recording head needs to be made of a material that does not dissolve in the ink and does not generate a discharge as a foreign matter.

Japanese Patent Laid-Open No. 5-39499

  Fatty acids and fatty acids are used for elastic members composed of rubber, elastomers, etc. for additives such as polymer polymerization, lubricants, plasticizers, internal mold release agents, antiblocking agents, and various other applications (Patent Literature). 1). Fatty acids and fatty acids are easy to bleed from the material and are not easily dissolved in water or organic solvents. For this reason, when fatty acids and fatty acids bleed into the ink from the elastic member for ink jet, it may become a foreign substance insoluble in the ink and cause problems in printing. Therefore, it is considered better to avoid the use of fatty acids and fatty acids in the elastic member for ink jet.

  However, fatty acids and fatty acids may have to be used to obtain the necessary physical properties and molded products. In such a case, even if an attempt is made to remove the fatty acid and the fatty acid by washing the molded product, the fatty acid and the fatty acid are difficult to dissolve in water or an organic solvent, so that the removal by washing is difficult. On the other hand, fatty acids and fatty acids present on the surface of the inkjet elastic member can be removed by mechanical cleaning such as ultrasonic cleaning. However, since the ink jet elastic member is used in a state of being in contact with ink for a long period of time, the fatty acids and fatty acids contained in the ink jet elastic member are bleed to become foreign matters again. For this reason, it is necessary to remove the fatty acids and fatty acids present in the elastic member for inkjet by washing.

  As described above, it is necessary to exclude fatty acids and fatty acids from the entire inkjet elastic member, but there has been no effective cleaning method that can sufficiently remove fatty acids and fatty acids from the inkjet elastic member. An object of the present invention is to provide a method for cleaning an elastic member for ink jet that does not cause a problem in printing in the ink jet application.

  The method for cleaning an elastic member for ink jet according to the present invention is a method for cleaning an elastic member for ink jet containing at least one of a fatty acid and a fatty acid, and is at least sodium hydroxide or potassium hydroxide and nonionic or anionic. A cleaning first step of cleaning the elastic member while heating the cleaning liquid 1 to 70 ° C. or higher using a cleaning liquid 1 comprising an aqueous solution having a pH of 11 or higher, and the cleaning A second cleaning step that is performed after the first step and that cleans the elastic member while heating the cleaning solution 2 using the cleaning solution 2 composed of an aqueous solution containing at least a nonionic or anionic surfactant. And including.

  According to the cleaning method of the present invention, it is possible to provide an inkjet elastic member that does not cause a problem in printing in inkjet applications.

It is the schematic which shows the structure of an inkjet recording head provided with the elastic member for inkjets which is the washing | cleaning target of the washing | cleaning method which concerns on this invention. It is the schematic which shows the structure of an inkjet recording head provided with the elastic member for inkjet which is the washing | cleaning object of the washing | cleaning method which concerns on this invention, and an ink tank. It is a flowchart which shows an example of the washing | cleaning method which concerns on this embodiment.

  The cleaning method according to the present invention is a method for cleaning an elastic member for inkjet, which contains at least one of fatty acids and fatty acids. In the present invention, fatty acids refer to fatty acid derivatives that change to fatty acid sodium or fatty acid potassium by the presence of sodium hydroxide or potassium hydroxide. Examples of fatty acids include fatty acid amides, fatty acid esters, and fatty acid metal salts.

  Specific examples of fatty acids and fatty acids include stearic acid, stearic acid amide, calcium stearate, zinc stearate, magnesium stearate, butyl stearate, methyl stearate, hydroxystearic acid, oleic acid, oleic acid amide, calcium oleate , Zinc oleate, magnesium oleate, butyl oleate, methyl oleate, hydroxy oleate, palmitic acid, palmitate amide, calcium palmitate, zinc palmitate, magnesium palmitate, butyl palmitate, methyl palmitate, hydroxypalmitine An acid etc. are mentioned. These may use only 1 type and may use 2 or more types together. In addition, a fatty acid and fatty acids are not restricted to these. The fatty acids in the present invention do not include fatty acid sodium and fatty acid potassium.

  The said fatty acid and fatty acids have a property which is hard to melt | dissolve in water or an organic solvent. Therefore, it cannot be removed by simple washing with water or an organic solvent. Therefore, the present inventors have found that cleaning is possible by using a chemical reaction. That is, washing is performed after changing fatty acids and fatty acids into soaps that are easily soluble in water by a neutralization reaction with alkali. In the present invention, the soap is at least one of fatty acid sodium and fatty acid potassium, and has higher solubility in water than the fatty acids and fatty acids.

  Materials other than fatty acids and fatty acids contained in the inkjet elastic member can include, for example, a crosslinked rubber, a thermoplastic elastomer, or the like as a base polymer. The material may also contain an internal release agent such as stearic acid, stearic acid amide, zinc stearate. Note that it is not preferable that the material contains an ester-based material that is hydrolyzed by washing.

  The ink jet elastic member is not particularly limited as long as it contains at least one of fatty acids and fatty acids, and examples thereof include ink seals and rubber plugs used for ink jet recording heads. As the ink seal, for example, the joint seal 6 of the ink jet recording head shown in FIG. The joint seal 6 is disposed between the flow path plate 7 and the chip plate 5 and is one of components that form an ink flow path. As shown in FIG. 2, the ink supplied from the ink tank 9 through the ink supply port 10 passes through the ink flow path formed by welding the chip tank 8 and the flow path plate 7. Further, the ink passes through the ink flow path provided in the joint seal 6 and the chip plate 5 and is finally discharged by the heat of the heater provided in the chip 2.

  The cleaning method according to the present invention is a cleaning method using alkali sodium hydroxide or potassium hydroxide, and includes at least the following two steps. That is, it includes a first washing step for changing fatty acids and fatty acids to fatty acid sodium or fatty acid potassium and a second washing step for washing fatty acid sodium or fatty acid potassium performed after the first washing step. A washing step or an rinsing step may be separately performed before or after or between the first washing step and the second washing step. However, since the fatty acid sodium and the fatty acid potassium are changed into a sparingly soluble fatty acid when washed with an acidic aqueous solution, washing with an acidic washing liquid after the first washing step is not preferable.

  The cleaning liquid 1 used in the first cleaning step is composed of an aqueous solution containing at least sodium hydroxide or potassium hydroxide and a nonionic or anionic surfactant and having a pH of 11 or more. By setting the pH of the cleaning liquid 1 to 11 or more, fatty acids and fatty acids can be efficiently changed to fatty acid sodium or fatty acid potassium. The pH of the cleaning liquid 1 is preferably 12 or more.

  The cleaning liquid 1 is mixed with a nonionic or anionic surfactant. The ink seals, rubber plugs, and the like mentioned as specific examples of the ink jet elastic member have small holes for forming ink channels. Since the inside of the hole is in contact with the ink flow path, it is necessary to sufficiently wash the inside of the hole by infiltrating the cleaning liquid. In addition, the elastic member for inkjet is often a member that does not use an anti-adhesive agent, a filler, or the like in consideration of liquid contact properties, or a member that suppresses the amount of use. For this reason, a material having a large stickiness is used for the elastic member for ink jet, and the molded products often tend to stick to each other. For this reason, in the cleaning method according to the present invention, a nonionic or anionic surfactant is added to the cleaning liquid 1 in order to allow the cleaning liquid to penetrate into the small holes and to suppress sticking between molded products. Blend.

  The type of the nonionic or anionic surfactant according to the present invention is not particularly limited as long as the above effects are obtained. Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, and polyoxyethylene tridecyl ether. Polyoxyethylene fatty acid esters such as polyoxyethylene cetyl ether and polyoxyethylene stearyl ether, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan oleate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan stearate Oxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, aminopolyoxyethylene, naphthol Chi alkylene oxide adducts, acetylene glycol ethylene oxide adduct, bisphenol A ethylene oxide adduct, oxyethylene oxypropylene block polymer, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid ester and the like. These may use only 1 type and may use 2 or more types together.

  Examples of anionic surfactants include alkyl sulfate salts, alkylbenzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, dialkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, and polyoxyethylene alkyls. Sulfuric acid ester salt, polyoxyethylene alkylaryl sulfuric acid ester salt, alkane sulfonic acid salt, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl phosphoric acid ester, N-methyl-N-oleoyl tauric acid salt, α-olefin sulfonic acid Examples include salts. These may use only 1 type and may use 2 or more types together.

  Among these, the surfactant is preferably a surfactant having an ethylene oxide adduct structure. In particular, it is preferable to use an acetylene glycol ethylene oxide adduct, which has been conventionally known as an ink application, as a surfactant because the elastic member for inkjet is not greatly deteriorated or swollen.

  In the first cleaning step, the inkjet elastic member is cleaned while heating the cleaning liquid 1 to 70 ° C. or higher. In the cleaning method according to the present invention, it is considered that the cleaning can be gradually performed using the penetration of the cleaning liquid into the material of the ink jet elastic member and the bleed of the fatty acid and the fatty acid itself. Since the melting point of fatty acid is around 70 ° C., acceleration of fatty acid bleed can be expected at a temperature equal to or higher than the melting point. Further, since it is considered that the permeability of the cleaning liquid is improved and the neutralization reaction of sodium hydroxide or potassium hydroxide proceeds at a high temperature, heating at 70 ° C. or higher is effective. Furthermore, you may wash | clean using 100T or more high temperature and high pressure using a PCT (pressure cooker tester) apparatus. This condition is preferable because penetration of the cleaning liquid and bleeding of fatty acids are promoted and the cleaning effect is further enhanced. The washing temperature is preferably 120 ° C. or higher.

  Since it is necessary to clean not only the surface but also the inside of the elastic member for inkjet, the cleaning time in the first cleaning step needs to be appropriately set depending on the thickness of the elastic member for inkjet. In addition, the cleaning time in the first cleaning process is set appropriately in consideration of these conditions, because there are some differences in the cleaning effect depending on the type of base polymer constituting the elastic member for inkjet and the types of fatty acids and fatty acids. There is a need to. For these reasons, the cleaning time in the first cleaning process cannot be specified in general. However, for example, in the case of an elastic member for ink jet having a thickness of about 1 mm using a material in which fatty acid amide is blended with SEBS (styrene-ethylene / butylene-styrene block copolymer) as a base polymer, cleaning is performed at 70 ° C. for 60 minutes or more. Preferably it is done.

  The cleaning liquid 1 may contain both sodium hydroxide and potassium hydroxide. Moreover, the cleaning liquid 1 may contain both a nonionic surfactant and an anionic surfactant.

  The second washing step is a step of washing the fatty acid sodium or the fatty acid potassium that was performed after the first washing step and could not be washed in the first washing step.

  The cleaning liquid 2 used in the second cleaning step is composed of an aqueous solution containing at least a nonionic or anionic surfactant. Since the solubility of fatty acid sodium or fatty acid potassium is greatly improved by heating, the elastic member for inkjet is cleaned while heating the cleaning liquid 2. The cleaning temperature for cleaning with the cleaning liquid 2 is preferably 70 ° C. or higher.

  Furthermore, in order to wash | clean fatty acid sodium and fatty acid potassium more efficiently, you may mix | blend the organic solvent with the washing | cleaning liquid 2. FIG. Since fatty acid sodium and fatty acid potassium are more soluble in alcohol than water, it is preferable that the cleaning liquid 2 contains alcohol from the viewpoint of further improving the cleaning effect. As the alcohol, ethanol or isopropyl alcohol having a relatively high boiling point is preferable.

  As the nonionic or anionic surfactant blended in the cleaning liquid 2, the same surfactant as the surfactant blended in the cleaning liquid 1 can be used, and if there is an effect as a surfactant, The type is not particularly limited. The cleaning time can be appropriately set depending on the conditions as in the first cleaning step.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

[Example 1]
As an ink jet elastic member, a joint seal 6 of the ink jet recording head shown in FIG. 1 was used. The thickness of the joint seal 6 was 0.9 mm. As the base polymer of the joint seal 6, SEBS [made by Kuraray Co., Ltd., trade name: Septon 8007] of a styrenic thermoplastic elastomer was used. SEBS consists of polypropylene as a lubricant [manufactured by Nippon Polypro Co., Ltd., trade name: Novatec PP BC05B] and paraffin as a softener [manufactured by Nippon Oil Corporation, trade name: Diana Process Oil PW150]. Used in combination. The blending amount was 30 parts by mass of both polypropylene and paraffin with respect to 100 parts by mass of SEBS. Further, stearamide [manufactured by Nippon Kasei Co., Ltd., trade name: Amide AP-1] was used as an internal mold release agent. The compounding amount of the internal mold release agent was 1 part by mass of the internal mold release agent with respect to 100 parts by mass of the base polymer.

  A cleaning flow in Example 1 is shown in FIG. The joint seal 6 was cleaned in the order of “first cleaning step”, “rinsing”, “second cleaning step”, “rinsing”, “water droplet removal”, and “drying”.

  In the first washing step, an 8 mol / l sodium hydroxide aqueous solution is added to water to adjust the pH to 11, and a nonionic surfactant [trade name, manufactured by Kawasaki Fine Chemical Co., Ltd., so that the concentration becomes 1% by mass. : Acetylenol E100] was used. The amount of the cleaning liquid 1 used was 10 times the mass of the joint seal 6. The cleaning temperature was adjusted by putting the cleaning liquid 1 and the joint seal 6 in a stainless steel container, and adjusting the temperature of the cleaning liquid 1 to 70 ° C. using a water bath. The washing time was 3 hours. A rinsing step was performed after the first washing step. In the rinsing process, water was poured into the stainless steel container, and the work of immersing the joint seal 6 therein was performed several times.

  In the second washing step, an aqueous solution in which a nonionic surfactant [manufactured by Kawasaki Fine Chemical Co., Ltd., trade name: acetylenol E100] was added to water so as to have a concentration of 1% by mass was used as the washing liquid 2. The amount of the cleaning liquid 2 used was 10 times the mass of the joint seal 6. The cleaning temperature was adjusted by putting the cleaning liquid 2 and the joint seal 6 in a stainless steel container and using a water bath so that the temperature of the cleaning liquid 2 was 70 ° C. The washing time was 1 hour. After the second cleaning step, a rinsing step was performed in the same manner as after the first cleaning step. Thereafter, water droplets adhering to the joint seal 6 were removed with air, and then the joint seal 6 was stored in a thermostat set at 100 ° C. for 3 hours and dried.

(Evaluation of cleaning effect)
Evaluation of the cleaning effect was judged by preparing an ink jet recording head using the joint seal 6 cleaned by the cleaning method of the present embodiment, storing it at 60 ° C. for one month, and performing printing evaluation. The evaluation criteria are shown below. The evaluation results are shown in Table 1.
A: Printing failure does not occur within 1 hour of cleaning time in the first cleaning step.
B: The cleaning time of the first cleaning process exceeds 1 hour, and printing defects do not occur within 3 hours.
C: Printing failure also occurs when the cleaning time of the first cleaning process is 3 hours.

[Examples 2 to 15, Comparative Examples 1 to 6]
It carried out similarly to Example 1 except having wash | cleaned the joint seal 6 on the conditions shown in Tables 1-3. The evaluation results are shown in Tables 1-3. In addition, as a base polymer other than SEBS, H-NBR [manufactured by ZEON Corporation, trade name: Zetpol 1000L], Cl-IIR [manufactured by JSR Corporation, trade name: CHLOROBUTYL 1066] of a crosslinked rubber is used. used. H-NBR and Cl-IIR were not blended with polypropylene and paraffin blended with SEBS. As internal mold release agents other than stearic acid amide, stearic acid [manufactured by ADEKA Corporation, trade name: Adeka fatty acid SA-200], zinc stearate [manufactured by NOF Corporation, trade name: zinc stearate GF -200] was used. As an anionic surfactant, Adekacol EC [manufactured by ADEKA Corporation] was used. In Examples 3, 5, 14, and 15, the cleaning temperature was adjusted to 120 ° C. using a PCT (pressure cooker tester) by putting the cleaning liquid 1 and the joint seal 6 in a stainless steel container.

  As shown in Examples 1 to 15, the inkjet recording head using the joint seal 6 cleaned by the cleaning method according to the present invention did not cause printing defects in the evaluation of the cleaning effect. On the other hand, as shown in Comparative Examples 1 to 4, when the first washing step and the second washing step are not performed, or when the alkali component of sodium hydroxide and potassium hydroxide and the surfactant are not used, sufficient It was found that no cleaning effect was obtained. It was also found that a sufficient cleaning effect could not be obtained even when the pH and cleaning temperature were low.

  In contrast to Example 1, in Example 2, the pH of the cleaning liquid was increased, but it was found that increasing the pH increased the cleaning effect. Although Example 1 and Example 3, Example 4 and Example 5 differed in the washing | cleaning temperature, respectively, it turned out that the washing | cleaning effect becomes high by raising washing | cleaning temperature. In Examples 2, 4, 6, 7, and 8, the cleaning conditions were the same, and the combination of the base polymer and the internal mold release agent was different. However, it was found that sufficient cleaning effect was obtained even when the combinations were different. From Examples 9, 10 and 11, it was found that a sufficient cleaning effect could be obtained even when the type and amount of surfactant were changed. Examples 12 and 13 are examples in which isopropyl alcohol and ethanol were added to the cleaning liquid 2 in the second cleaning step, and Examples 14 and 15 were examples in which the cleaning temperature was further increased. When these examples and Example 1 were compared, it turned out that the washing | cleaning effect becomes high by adding alcohol to the washing | cleaning liquid 2. FIG.

  As described above, by using the cleaning method according to the present invention, it is possible to provide an elastic member for inkjet that does not have a printing defect.

1 PWB
2 Chip 3 Screw 4 Macula 5 Chip plate 6 Joint seal 7 Flow path plate 8 Chip plate 9 Ink tank 10 Ink supply port

Claims (5)

  A method for cleaning an elastic member for inkjet, comprising at least one of a fatty acid and a fatty acid, comprising at least sodium hydroxide or potassium hydroxide and a nonionic or anionic surfactant, having a pH of 11 or more A cleaning first step of cleaning the elastic member while heating the cleaning solution 1 to 70 ° C. or higher using a cleaning solution 1 composed of a certain aqueous solution, and at least nonionic after the cleaning first step Or a cleaning second step of cleaning the elastic member while heating the cleaning liquid 2 using the cleaning liquid 2 composed of an aqueous solution containing an anionic surfactant.   The method for cleaning an elastic member for inkjet according to claim 1, wherein in the second cleaning step, the cleaning temperature for cleaning with the cleaning liquid 2 is 70 ° C. or higher.   The method for cleaning an elastic member for inkjet according to claim 1 or 2, wherein at least one of the surfactants contained in the cleaning liquid 1 and the cleaning liquid 2 has an ethylene oxide adduct structure.   The method for cleaning an elastic member for inkjet according to any one of claims 1 to 3, wherein the cleaning liquid 2 is composed of an aqueous solution containing at least an alcohol and a nonionic or anionic surfactant.   The method for cleaning an elastic member for inkjet according to any one of claims 1 to 4, wherein in the first cleaning step, a cleaning temperature for cleaning with the cleaning liquid 1 is 120 ° C or higher.

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