JP6376375B2 - Cleaning liquid for active energy ray-curable inkjet ink - Google Patents

Description

  The present invention relates to a cleaning liquid for an active energy ray-curable inkjet ink.

  Inkjet printer printing is a system that ejects ink from nozzles and adheres to the recording material. Unlike conventional printing methods, it uses a printing system that does not use a plate. This printing method is expected to be used in a wide range of applications. In particular, in recent years, as a recording material, many studies have been made on printing on a non-absorbing substrate such as plastic from printing on a conventional absorbing substrate such as paper.

  As an ink used in this inkjet recording apparatus, an ink that is cured and dried with an active energy ray such as an ultraviolet ray has a short drying time on a non-absorbing material, and has excellent adhesion and durability of a printed image. Many have been proposed.

By the way, since an ink jet printer discharges ink from a small-diameter discharge port formed in the head, the ink adheres to the head, the periphery of the discharge port, and other parts of the ink jet printer, or the ink is cured at the discharge port. As a result, the discharge port is blocked.
When such a discharge port blockage occurs, the discharge performance deteriorates, and various measures are taken to deal with such a situation.

Among the various countermeasures, as the simplest method, a method of cleaning the nozzle with an appropriate cleaning liquid is known. For example, Patent Document 1 discloses a cleaning liquid for cleaning an inkjet printer head on which printing is performed by supplying ink containing at least two polymerizable compounds having different viscosities, a photopolymerization initiator, and a pigment, Among the polymerizable compounds used in ink, an inkjet printer head cleaning liquid containing 50 parts by weight or more of a polymerizable compound having the lowest viscosity or an acid polymerizable compound having a viscosity of 30 mPa · sec or less is known. . Further, in Patent Document 2, an ink cleaning liquid of a photocurable ink containing a pigment dispersant is known. (For example, see Patent Documents 1 and 2)
However, all of the cleaning liquids described in the above-mentioned patent documents are adjusted only from the viewpoint of detergency, and are not adjusted from the viewpoint of the working environment such as odor and skin irritation.

JP 2006-35467 A JP 2007-254550 A

  An object of the present invention is to provide an ink cleaning liquid for an ink jet printer having a low odor, excellent work environment, and high cleaning performance.

  The present inventors solved the above-mentioned problems by using a polymerizable compound having a (meth) acryloyl group and a vinyl ether group as essential components.

  That is, this invention provides the cleaning liquid for active energy ray hardening-type inkjet inks containing the polymeric compound represented by General formula (1).

（１）

(1)

(In formula (1), R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an organic residue having 2 to 20 carbon atoms, and R ₃ represents a hydrogen atom or an organic residue having 1 to 11 carbon atoms. Represents.)

  According to the present invention, it is possible to provide an ink cleaning liquid for an ink jet printer having a low odor, excellent work environment, and high cleaning performance.

(Polymerizable compound represented by general formula (1))
In the general formula (1), R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an organic residue having 2 to 20 carbon atoms, and R ₃ represents a hydrogen atom or an organic residue having 1 to 11 carbon atoms. Represents a group.
Specifically, R ₂ is a linear, branched or cyclic alkylene group having 2 to 20 carbon atoms, and having 2 to 20 carbon atoms having an oxygen atom by an ether bond and / or an ester bond in the structure. An alkylene group, an aromatic group having 6 to 11 carbon atoms which may be substituted is represented. Among these, an alkylene group having 2 to 6 carbon atoms and an alkylene group having 2 to 9 carbon atoms having an oxygen atom by an ether bond in the structure are preferable.
Specific examples of the organic residue having 1 to 11 carbon atoms represented by R ₃ include a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and substitution having 6 to 11 carbon atoms. Represents an aromatic group or the like. Of these, an alkyl group having 1 to 2 carbon atoms and an aromatic group having 6 to 8 carbon atoms are preferable.

  Among them, it is preferable to use 2- (2-vinyloxyethoxy) ethyl (meth) acrylate. Examples of commercially available (meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl include VEEA and VEEM manufactured by Nippon Shokubai Co., Ltd.

(Other polymerizable compounds)
In the present invention, the above (meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl is used, but the above-mentioned known polymerizable compound is used in combination as long as the effects of the present invention are not impaired. It may be preferable.
Examples of polymerizable compounds with low odor and less irritation include diallyl phthalate, lauryl (meth) acrylate, 2-methyl-2-ethyl (meth) acrylate, (1,3-dioxolan-4-yl) methyl (meth) ) Acrylate, ethoxyethyl cyano (meth) acrylate, ethoxy modified phenyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethoxy modified cresol (meth) acrylate, and the like. Among these, diallyl phthalate is more preferable because it can maximize the effects of the present invention.
As the diallyl phthalate, diallyl orthophthalate and diallyl isophthalate are preferable, and as these, the monomer “Daisodap Monomer” and “Daisodup 100 Monomer” from Daiso Corporation can be preferably used.

  When diallyl phthalate is used in combination, it is preferably used in a proportion of 0 to 80 parts by weight with respect to 100 parts by weight of the polymerizable compound represented by the general formula (1). It is still more preferable to add in.

  On the other hand, since the effect of the present invention may be impaired, the classification standard of “serious eye damage or eye irritation” in the GHS classification guidance for government (revised in 2013) is classified into “Category”. It is preferable not to use anything other than “outside”. Examples of polymerizable compounds other than “not classified” include, for example, trimethylolpropane triacrylate and dipropylene glycol diacrylate.

  The composition of the active energy ray-polymerizable compound has a viscosity of about 1 to 100 mPa.s after blending each monomer, depending on the ink jet apparatus used. It is preferable to design so that it may become s.

(Polymerization inhibitor)
A polymerization inhibitor may be preferably added to the cleaning liquid of the present invention in order to increase storage stability and prevent unexpected gelation during cleaning. The polymerization inhibitor is not particularly limited, and one or several known polymerization inhibitors can be used in combination.
Among these, hindered phenol compounds, phenothiazine compounds, hindered amine compounds, and phosphorus compounds are particularly preferably used. Among them, it is preferable to use a hindered phenol compound and a compound selected from at least one of phenothiazine, hindered amine, or phosphorus, preferably selected from a hindered phenol compound, phenothiazine, or hindered amine. It is still more preferable to use the compound to be combined with a phosphorus compound.

  As hindered phenol compounds, “IRGANOX 1010, 1010FF, 1035, 1035FF, 1076, 1076FD, 1076DWJ, 1098, 1135, 1330, 245, 245FF, 245DWJ, 259, 3114, 565, 565DD, 295” manufactured by BASF, Seiko Chemical Co., Ltd. “BHT Swanox” “Nonflex Aruba, MBP, EBP, CBP, BB” “TBH”, ADEKA “AO-20, 30, 50, 50F, 70, 80, 330”, Honshu Chemical H-BHT ”and API Corporation“ Yoshinox BB, 425, 930 ”.

  Examples of the phenothiazine-based compound include “phenothiazine” manufactured by Seiko Chemical Co., Ltd., “phenothiazine” “2-methoxyphenothiazine”, and “2-cyanophenothiazine” manufactured by Sakai Chemical Industry.

  As hindered amine compounds, “IRGANOX 5067” “TINUVIN 144, 765, 770DF, 622LD” manufactured by BASF Corporation, Seiko Chemical Co., Ltd. “Nonflex H, F, OD-3, DCD, LAS-P” “Stearer STAR” “Diphenylamine” “4-aminodiphenylamine”, “4-oxydiphenylamine”, “HO-TEMPO” manufactured by Evonik Degussa, Hitachi Chemical “Funkryl 711MM, 712HM”, and LA-82 manufactured by ADEKA.

  Examples of phosphorus compounds include “Triphenylphosphine” “IRGAFOS 168, 168FF” manufactured by BASF and Seiko Chemical Co., Ltd. “Nonflex TNP”.

  In addition, as a polymerization inhibitor that can be preferably used, “IRGASTAB UV-10, 22” manufactured by BASF, “Hydroquinone”, “Metquinone”, “Toluquinone”, “MH”, “PBQ”, “TBQ”, “2,5-” manufactured by Seiko Chemical Co., Ltd. Diphenyl-p-benzoquinone ”,“ Wako Pure Chemical Industries, Ltd. ”“ Q-1300, 1301 ”, and“ GENORAD 16, 18, 20 ”manufactured by RAHN.

About the compounding quantity of a polymerization inhibitor, a normal usage-amount may be sufficient. For example, the proportion of the compound selected from at least one of phenothiazine, hindered amine, and phosphorus with respect to the amount of the hindered phenol compound is preferably 5% or more and 25% or less. % To 20% is particularly preferable.
In addition, when a hindered phenol compound, a compound selected from phenothiazine or hindered amine, and a phosphorus compound are used in combination, the compounding of the phosphorus compound with respect to the compounding amount of the compound selected from the phenothiazine or hindered amine The proportion of the amount is preferably 5% or more and 100% or less, and particularly preferably 10% or more and 50% or less. Within these ranges, the interaction between the polymerization inhibitors can be used effectively, and as a result, the balance between stability over time and curability is good.

(Other)
Other components can also be added to the ink cleaning liquid of the present invention.
Examples of other components include N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, tetramethylurea, dimethylimidazolidinone, and the like. .

  The amount of other components added is preferably 0 to 40% by weight, more preferably 0 to 30% by weight, and still more preferably 0 to 20% by weight of the entire cleaning liquid. It is preferable for the amount added to be in the above-mentioned range since member modification is suppressed and the cleaning effect expected in the present invention can be maintained.

Moreover, you may add surfactant and an antifoamer. The surface energy of the cleaning liquid can be adjusted by adding a surfactant to the cleaning liquid, and when the cleaning liquid is applied to the ink jet printer, the wettability of the cleaning liquid with respect to the ink jet printer can be improved. Further, it is preferable to add an antifoaming agent to the cleaning liquid because it is possible to prevent generation of bubbles in the cleaning liquid.

(How to use cleaning solution)
The ink cleaning liquid of the present invention can be used as a cleaning liquid for cleaning an inkjet printer of a known active energy ray-curable inkjet ink. Next, an example of a specific aspect of the ink jet printer cleaning method will be described.

  Examples of the method for cleaning the ink jet printer or some parts using the ink cleaning liquid of the present invention include, for example, a method of wiping the ink jet printer or its parts with a cloth or a cleaning blade wetted with the ink cleaning liquid of the present invention, and the ink of the present invention. A method of immersing an ink jet printer or its parts in a cleaning liquid, a method of applying an ink cleaning liquid of the present invention to an ink jet printer or its parts, and then contacting the absorbent with the ink jet printer or its parts, and sucking the cleaning liquid with the absorbent, There is a method of removing the cleaning liquid by applying air suction or air supply to the ink jet printer or its parts after applying the ink cleaning liquid to the ink jet printer or its parts.

  Further, when the ink jet printer is provided with a cleaning mechanism for cleaning the head of the ink jet printer with the cleaning liquid, the head is cleaned by the cleaning mechanism when the ink cleaning liquid of the present invention is supplied to the cleaning mechanism. Further, when the ejection port of the head is covered with a cap, a cap coated with the ink cleaning liquid of the present invention may be used.

Furthermore, by filling the ink cleaning liquid of the present invention into the head of the ink jet printer and discharging it from the nozzle, it is possible to clean the inside of the head and the vicinity of the nozzle by discharging the ink from the nozzle. In this case, it is preferable to apply a pressure of about 1 kPa to 100 kPa. Specifically, the cleaning liquid is fed into the head from the ink supply path connected to the head. At that time, adjusting the pressure to discharge the cleaning liquid from the nozzle, or forcibly suctioning the filled cleaning liquid with a rubber tube or the like so as not to damage the nozzle surface from the nozzle surface is included. In some cases, it is possible to drive the printer head and perform the same operation as the ink discharge to discharge the ink cleaning liquid.
On the other hand, a method of cleaning the inside of the printer (nozzle, head, tube, pump, etc.) by circulating the ink cleaning liquid can also be exemplified.
Alternatively, the cleaning liquid may be discharged or collected after filling the head with the cleaning liquid and applying external vibration by ultrasonic waves to promote the solubility of the solids in the head.

In the present invention, as the method of using the ink jet recording apparatus, when the ink jet recording apparatus is not used for several hours, the method of using the ink jet recording apparatus in which the ink cleaning liquid of the present invention is filled in the head of the ink jet printer is preferable. Thus, it is preferable to fill the head with the ink cleaning liquid of the present invention because the active energy ray-curable inkjet ink can be prevented from being cured and clogging of the head can be suppressed.
In addition, it is preferable that the head is automatically cleaned with an ink cleaning liquid when ejection is not performed for a certain period of time (preferably 12 to 168 hours, more preferably 24 to 36 hours). More preferably, it is filled with a cleaning liquid. In use, the active energy ray-curable inkjet ink can be discharged by discharging or collecting the filled ink cleaning liquid.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to the following Example at all. In addition, hereinafter, the part in an Example represents a mass part.

(Reference example) Preparation example of high concentration pigment dispersion (yellow mill base) (Production example of mill base (1))
Eva Screen Yellow G01 10 parts Clanx Corporation C.I. I. Pigment Yellow 150
Solspers 33000 6 parts Lubrizol polymer pigment dispersant Miramar M222 84 parts MIWON dipropylene glycol diacrylate was stirred and mixed with a stirrer for 1 hour, and then treated with a bead mill for 2 hours to prepare a mill base (1).

(Reference example Preparation example of high concentration pigment dispersion (magenta mill base))
(Example of mill base (2) production)
Fastgen Super Magenta RTSP 10 parts DIC Quinacridone Magenta Pigment C.I. I. Pigment Red 122
Solspers 32000 6 parts Lubrizol polymer pigment dispersant Light acrylate PO-A 24 parts Kyoeisha Chemical Co., Ltd. Phenoxyethyl acrylate Miramar M222 60 parts MIWON dipropylene glycol diacrylate was stirred and mixed with a stirrer for 1 hour, then 2 in a bead mill. The mill base (2) was produced by time treatment.

(Reference example Preparation example of high-concentration pigment dispersion (cyan mill base))
(Production example of mill base (3))
Fast Gen Blue TGR-J 10 parts DIC phthalocyanine pigment C.I. I. Pigment Blue 15: 4
Solspers 32000 4.5 parts Lubrizol polymer pigment dispersant Light acrylate PO-A 18 parts Kyoeisha Chemical Phenoxyethyl acrylate Miramar M222 67.5 parts MIWON dipropylene glycol diacrylate after stirring for 1 hour with a stirrer Then, it was treated with a bead mill for 2 hours to prepare a mill base (3).

(Reference example Preparation example of high concentration pigment dispersion (black mill base))
(Production example of mill base (4))
# 960 10 parts Mitsubishi Chemical Corporation carbon black Solspers 32000 4.5 parts Lubrizol polymer pigment dispersant Light acrylate PO-A 18 parts Kyoeisha Chemicals Phenoxyethyl acrylate Miramar M222 84 parts MIWON dipropylene glycol di The acrylate was stirred and mixed with a stirrer for 1 hour and then treated with a bead mill for 2 hours to produce a mill base (3).

(Reference example: Yellow ink, magenta ink, cyan ink, black ink adjustment example)
For each color of yellow ink, magenta ink, cyan ink, and black ink, dipropylene glycol diacrylate (MIWON) and die sodup monomer (Daiso) are used as the polyfunctional monomers using the above mill bases (1) to (4), respectively. 10 parts of ethyl carbitol acrylate (Osaka Organic Chemical Co., Ltd.), 4 parts of Irgacure 819 (BASF) as a photopolymerization initiator, 2 parts of Irgacure 2959 (BASF), Darocur 1173 ( 4 parts of BASF), 1 part of Lucillin TPO (BASF), 0.1 parts BYK-UV3500 (silicone oil from BYK) as a surface tension regulator, KF-351A (silicone oil from Shin-Etsu Silicone) 0.2 part, non-flexible as a polymerization inhibitor 0.05 parts of Luba (manufactured by Seiko Chemical Co., Ltd.) was added and the mixture was heated and stirred at 60 ° C. for 30 minutes, and then the mill base (5) of Preparation Example 1 was added, and sufficiently stirred and mixed to obtain each ink.

(Example 1 Method for producing cleaning liquid for active energy ray-curable inkjet ink)
According to the composition of Table 1, a cleaning liquid for active energy ray-curable inkjet ink was produced. Specifically, 48 parts of VEEA (2- (2-vinyloxyethoxy) ethyl acrylate manufactured by Nippon Shokubai Co., Ltd.) as a bifunctional monomer and 52 parts of Daiso Dup 100 monomer from Daiso as a diaryl phthalate were added, Stir and mix thoroughly.
Subsequently, it filtered using a 1.2 micrometer membrane filter, and obtained the cleaning liquid (1) for active energy ray hardening-type inkjet inks.

(Examples 2 to 5: Manufacturing method of cleaning liquid for active energy ray-curable inkjet ink)
Except that the compounding amount of the polymerizable compound was as shown in Table 1, the washing liquids (2) to (5) for active energy ray-curable inkjet inks were obtained in the same manner as in Example 1.

(Comparative Examples 1-5 Method for Producing Cleaning Liquid for Active Energy Ray Curing Inkjet Ink)
Comparative Examples 1 to 5 for cleaning liquids for active energy ray-curable inkjet inks for comparative examples were obtained in the same manner as in Example 1 by changing the combination and mixing ratio of the monomer species.

(Physical property measurement method)
The surface tension and viscosity were measured as a cleaning liquid for an active energy ray-curable inkjet ink. The measurement method is shown.

[surface tension]
The surface tension was measured using a well-helmy surface tension measuring instrument manufactured by Kyowa Interface Science Co., Ltd .: CBUP-A3. The ink contained in the plastic container was immersed in a constant temperature water tank, and the surface tension at 25 ° C. was measured by adjusting the temperature to 25 ° C. in advance.

[viscosity]
Viscosity measuring device manufactured by Toki Sangyo Co., Ltd .: Viscosity at 25 ° C. was measured with TVE-20L. The measurement rotation speed was 50 rpm / mim. In addition, in order to print stably with the inkjet printing evaluation apparatus used in the Example of this invention, the viscosity of the ink was adjusted between 3-10 mPa * sec.

The composition ratio and physical properties are shown in Table 1. Numerical values represent parts.

In Table 1, “M300” is trimethylolpropane triacrylate manufactured by MIWON, “VEEA” is 2- (2-vinyloxyethoxy) ethyl acrylate manufactured by Nippon Shokubai Co., Ltd., and “M222” is MIWON Disodium glycol diacrylate manufactured by Daiso Corporation, Daiso Dup 100 monomer is a diallyl isophthalate monomer manufactured by Daiso Corporation, Daiso Dup monomer is a diallyl orthophthalate monomer manufactured by Daiso Corporation, and “PO-A” is phenoxyethyl manufactured by Kyoei Co., Ltd. Acrylate. Nonflex Alba is a polymerization inhibitor manufactured by Seiko Chemical Co., Ltd., AO-80 is a phenolic polymerization inhibitor manufactured by Adeka, TPP is Hokudoh Chemical's triphenylphosphine, and Adeka Stub LA-82 is a hindered amine polymerization inhibitor manufactured by Adeka. It is.

(Evaluation of cleaning solution)
The cleaning characteristics and odor evaluations of Examples 1 to 5 and Comparative Examples 1 to 3 of the cleaning liquid for active energy ray-curable inkjet ink were performed as follows.

[Cleaning characteristics]
After 10 μl of ink is dropped on a stainless steel plate, the plate is tilted 45 degrees. Ten seconds after tilting, 100 μl of the cleaning solution was dropped from above the ink, and the degree to which the ink color faded was visually evaluated in three stages.
○: Almost no color △: Slight color can be confirmed ×: Color can be clearly confirmed

[Odor evaluation]
A sensory evaluation of smelling the odor of the cleaning liquid was performed by three men and two women, and the average score was calculated. A five-step evaluation from strong to weak odor was made, with strong odor “5” → low odor “1”.

[Evaluation of acupuncture]
A sensory evaluation of smelling the odor of the cleaning liquid was performed by three men and two women, and the average score was calculated. The evaluation was made on a five-point scale from strong to weak, with a strong odor of “5” → low odor of “1”.
The results are shown in Table 2.

  From the evaluation results of Examples 1 to 6 and Comparative Examples 1 to 3, the active energy ray-curable inkjet cleaning liquid containing 2- (2-vinyloxyethoxy) ethyl acrylate is excellent in cleanability and low irritation. On the other hand, in Comparative Examples 1 and 2, GHS Classification Guidance for Government (revised in 2013) “Severe eye damage or eye irritation” classification JIS classification standard is not “Not classified” However, the comparative example 3 was inferior in both irritation and cleansing properties.

Claims (7)

A cleaning liquid for an active energy ray-curable inkjet ink, comprising a polymerizable compound represented by the general formula (1) and diallyl phthalate.

(1)

(In formula (1), R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an organic residue having 2 to 20 carbon atoms, and R ₃ represents a hydrogen atom or an organic residue having 1 to 11 carbon atoms. Represents.) The cleaning solution for an active energy ray-curable inkjet ink according to claim 1, wherein the diallyl phthalate is diallyl isophthalate or diallyl orthophthalate. The cleaning liquid for an active energy ray-curable inkjet ink according to claim 1 or 2, comprising a hindered phenol compound, a hindered amine compound, a phosphorus compound, or a phenothiazine compound as a polymerization inhibitor. The cleaning liquid for an active energy ray-curable inkjet ink according to claim 3, wherein a hindered phenol compound, a compound selected from phenothiazine compounds, a hindered amine compound, and a phosphorus compound are used in combination as the polymerization inhibitor. The activity according to any one of claims 1 to 4, wherein a ratio of the mass of the diallyl phthalate to the mass of the polymerizable compound represented by the general formula (1) is in a range of 52/48 to 70/30. Cleaning solution for energy ray curable inkjet ink. The cleaning liquid for active energy ray-curable inkjet ink according to any one of claims 1 to 5, which is used for cleaning an active energy ray-curable inkjet ink not containing the polymerizable compound represented by the general formula (1). A cleaning method for a head, wherein the cleaning liquid for an active energy ray-curable inkjet ink according to any one of claims 1 to 6 is filled in a head of an inkjet printer and discharged from a nozzle.