JP2003071374A - How to prevent nozzle clogging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing nozzle clogging of coating machine, printing machine and printer, etc. SOLUTION: This method for preventing nozzle clogging comprises a process that the surrounding of nozzle opening part is kept in a humidified state when a water emulsion composition exists in a nozzle and a process that the composition contains specified hetero-phase structural particles obtained by a multistage emulsion polymerization method and a wetting agent of which the vaporization rate is calculated to be <30 when the vaporizing rate of butyl acetate is 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing nozzle clogging, and more specifically, to a nozzle of a coating machine, a printing machine, a printer, etc., which is used for coating, printing or printing by discharging an aqueous emulsion composition from the nozzle. A method for preventing clogging.

[0002]

2. Description of the Related Art In recent years, volatile organic compounds (hereinafter referred to as VOCs)
Say. ) And environmental regulations for reducing toxicity, etc., and from the perspective of resource conservation, the paint industry is changing from solvent-based paints that use organic solvents as solvents to water-based paints that use water. is there. As a typical paint thereof, there is an aqueous emulsion paint using a resin in an aqueous emulsion as a binder.

However, the resin in the aqueous emulsion has an inherent minimum film-forming temperature (hereinafter referred to as MFT), and therefore, even if the temperature of the surface to be coated is MFT or less, film formation is possible. It was necessary to add an organic solvent to the emulsion as a film forming aid.

Further, in the aqueous emulsion paint,
Since the time until the resin hardens is too short, the workability may be poor, or nozzle clogging may occur when used as ink. That is, there is a problem that the workability is poor and the work operation becomes impossible because the resin is hardened by the early drying in the nozzle.

[0005]

The present invention has been made against the background of the problems of the prior art as described above, and uses a VOC such as a film-forming auxiliary which becomes a source of environmental pollution and odor. Even without, even if used, with a small amount of addition, it is possible to lengthen the drying time, also the aqueous emulsion composition that can be freely adjusted the length of the drying time,
Provided is a method for preventing clogging of a nozzle of a coating machine, a printing machine, a printer or the like used for ejecting a water-based coating composition such as a water-based paint or a water-based ink composition such as a printing ink from a nozzle for coating, printing or printing. The purpose is to do.

[0006]

Means for Solving the Problems The present invention has been made as a result of extensive studies to achieve the above object, and as a result, an aqueous emulsion composition containing specific heterophase structure particles and a specific wetting agent obtained by a multistage emulsion polymerization method. The inventors have found that the above object can be achieved by maintaining the surroundings of the nozzle opening in a humidified state by using, and have reached the present invention.

That is, the method for preventing nozzle clogging of the present invention is to maintain a humidified state around the nozzle opening in the state where the aqueous emulsion composition is present in the nozzle.
The aqueous emulsion composition has a different phase structure particle obtained by a multi-stage emulsion polymerization method and an evaporation rate of butyl acetate of 100.
And a wetting agent having an evaporation rate of 30 or less. (1) The particles having a different phase structure have an ethylene oxide chain and / or a propylene oxide chain in which the average number of added moles in one molecule is 15 moles or more in total. 0.5 to 20 parts by weight of reactive nonionic emulsifier having 1 and ethylenically unsaturated monomer 1
(2) The polymer forming the heterophasic structure particles comprises 20 parts by weight of a monomer unit consisting of all ethylenically unsaturated monomers, which is obtained by multistage emulsion polymerization of an aqueous emulsion containing 100 parts by weight. % Of styrene or its derivative is contained, and (3) the glass transition temperature of the polymer forming the outermost phase of the different phase structure particles is -50 to
15 ° C., (4) the glass transition temperature of the polymer forming at least one phase inside the outermost phase of the heterophase structure particles is 50 to 150 ° C., (5) the minimum of the particles in the aqueous emulsion. The film forming temperature is characterized by being 30 ° C. or lower.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The aqueous emulsion composition in the present invention,
A heterophasic structure particle (hereinafter referred to as heterophasic structure emulsion particle) obtained by multistage emulsion polymerization of an aqueous emulsion containing the above-mentioned specific reactive nonionic emulsifier and an ethylenically unsaturated monomer, and a specific wetting agent. It is contained.

In the multistage emulsion polymerization method, an aqueous emulsion containing an ethylenically unsaturated monomer is used, and a conventionally known emulsion polymerization method is usually repeated in 2 to 5 steps to give a heterophase structure, that is, characteristics. Is an emulsion polymerization method in which particles composed of an outermost phase different from each other and one or more internal phases are formed. As a typical example of the multi-stage emulsion polymerization method, an aqueous emulsion containing an ethylenically unsaturated monomer is used, and an emulsifier and a polymerization initiator, and if necessary, a chain transfer agent and an emulsion stabilizer are present. And usually 60
An emulsion polymerization method in which emulsion polymerization is performed under heating at up to 90 ° C and this step is repeated a plurality of times is carried out.

In the production of heterophase emulsion particles, styrene and / or methylstyrene, chlorostyrene, methoxystyrene, etc. are used as essential ethylenically unsaturated monomers in order to improve the water resistance of the coating film formed. Is used in an amount of 20% by mass or more, preferably 25 to 80% by mass, based on the total ethylenically unsaturated monomer.

In the production of heterophase emulsion particles, in addition to styrene and / or styrene derivatives, various ethylenically unsaturated monomers conventionally used in the production of acrylic resins can be used in combination. The ethylenically unsaturated monomer used is not particularly limited.

Examples of the comonomer which is an ethylenically unsaturated monomer other than styrene include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate and isopropyl (meth) acrylate. , N-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, α-chloroethyl (Meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate,
(Meth) such as ethoxypropyl (meth) acrylate
Acrylate-based monomer; (meth) acrylic acid, carboxyl group-containing monomer such as crotonic acid, itaconic acid, itaconic acid half ester, maleic acid, maleic acid half ester; 2-hydroxyethyl (meth) acrylate, Hydroxyl group-containing monomers such as 2 (3) -hydroxypropyl (meth) acrylate and 4-hydroxybutyl acrylate; Amide group-containing monomers such as (meth) acrylamide and maleinamide; 2-Aminoethyl (meth) acrylate And amino group-containing monomers such as dimethylaminoethyl (meth) acrylate, 3-aminopropyl (meth) acrylate, 2-butylaminoethyl (meth) acrylate and vinylpyridine; glycidyl (meth) acrylate and allyl glycidyl ether ,
Epoxy group-containing monomers and oligomers obtained by reacting an epoxy compound having two or more glycidyl groups with an ethylenically unsaturated monomer having an active hydrogen atom; Other N-methylol acrylamide having N-methylol group 4- (meth) -acryloyloxy-2,2;
6,6-Tetramethylpiperidine, 4- (meth) -acryloylamino-2,2,2,6,6-tetramethylpiperidine, 4- (meth) -acryloyloxy-1,2,
UV stable monomers such as 2,6,6-pentamethylpiperidine; 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzotriazole and 2- [2'-hydroxy. UV absorbing monomer such as -5 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole; vinyl acetate, vinyl chloride, ethylene, butadiene, acrylonitrile, dialkyl fumarate, etc. as typical ones. Can be mentioned.

As described above, these comonomers have a glass transition temperature (hereinafter referred to as Tg) of the polymer forming the outermost phase of the heterophasic structure emulsion particles of −50 to 15 ° C. It may be used in an appropriate combination so that the Tg of the polymer forming at least one phase of the internal phase becomes 50 to 150 ° C. and the MFT of the aqueous emulsion composition becomes 30 ° C. or less.

In the heterophase emulsion particles, it is preferable that the polymer forming at least one phase inside the outermost phase has an internal crosslinked structure. The polymer having an internal crosslinked structure is a molecule such as divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate as a part of the ethylenically unsaturated monomer. Emulsion polymerization using a monomer having two or more polymerizable unsaturated double bonds therein; a combination of monomers having functional groups that react with each other at the temperature during the emulsion polymerization reaction, for example, carboxyl Of emulsion polymerization using a monomer mixture containing selectively an ethylenically unsaturated monomer having a functional group such as a group and a glycidyl group or a combination of a hydroxyl group and an isocyanate group; hydrolysis condensation reaction occurs ( (Meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltriethoxysilane, (meth) acryloxypropyiene It can be prepared by methods such as; a method of emulsion polymerization using a monomer mixture which contains a silyl group-containing ethylenically unsaturated monomers such as methyl dimethoxy silane.

In the heterophase emulsion particles, the outermost phase thereof contains 1 to 25% by mass of monomer units composed of an ethylenically unsaturated monomer having a carbonyl group based on all ethylenically unsaturated monomers. It is preferably a reaction product of a polymer with a compound having two or more hydrazide groups in the molecule. This polymer having a carbonyl group can be produced by emulsion-polymerizing an ethylenically unsaturated monomer having a carbonyl group and another ethylenically unsaturated monomer.

Examples of the ethylenically unsaturated monomer having a carbonyl group include acrolein, diacetone (meth) acrylamide, (meth) acryloxyalkylpropanal, diacetone (meth) acrylate,
Acetonyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate-acetylacetate and butanediol-1,4-acrylate-acetylacrylate, vinyl ethyl ketone, vinyl isobutyl ketone and the like can be mentioned. it can. Among these, acrolein, diacetone acrylamide, and vinyl ethyl ketone are particularly preferable.

In the heterophasic structure emulsion particles, the monomer unit consisting of the ethylenically unsaturated monomer having a carbonyl group is a monomer unit consisting of all the ethylenically unsaturated monomers forming the outermost phase of the heterophasic structure emulsion particle. It is desirable to occupy 1 to 25 mass%, preferably 2 to 20 mass%. When the amount is less than 1% by mass, crosslinking between particles tends to be insufficient, while when it exceeds 25% by mass, water resistance and the like tend to deteriorate.

Examples of the compound containing two or more hydrazide groups in the molecule include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide and dodecane didecane. Examples thereof include acid dihydrazide, isophthalic acid dihydrazide, citric acid trihydrazide, 1,2,4-benzene trihydrazide and thiocarbodihydrazide. Among these, carbohydrazide, adipic acid dihydrazide, and succinic acid dihydrazide are preferable from the viewpoint of the balance of dispersibility in emulsion and water resistance.

The amount of the hydrazide group-containing compound to be added when the polymer having a carbonyl group and the hydrazide group-containing compound are reacted with respect to the outermost phase of the emulsion particles having a heterophasic structure is such that the carbonyl group in the polymer having a carbonyl group is 1 It is suitable that the amount is 0.1 to 2.0 equivalents, preferably 0.3 to 1.2 equivalents of hydrazide group, based on the equivalents. When the amount of the hydrazide group-containing compound is less than the above range, the reaction with the carbonyl group in the emulsion particles of different phase structure becomes insufficient and the coating film hardness is not improved so much. On the other hand, when the amount is excessive, unreacted hydrazide group-containing compound remains, and the water resistance tends to deteriorate.

In the production of the heterophasic structure emulsion particles, as the emulsifier, the reactive nonion having an average addition mole number in one molecule of 15 moles or more in total, preferably 20 to 50 moles of ethylene oxide chain and / or propylene oxide chain. Use an emulsifier. The reactive nonionic emulsifier is a compound having a polymerizable unsaturated group, a hydrophilic group and a hydrophobic group, which is copolymerizable with the ethylenically unsaturated monomer described later.

Examples of commercially available reactive nonionic emulsifiers satisfying the above requirements are, for example, "Adecaria Soap N".
"E-20", "Adeka Rear Soap NE-30", "Adeka Rear Soap NE-40" [above Asahi Denka Kogyo Co., Ltd.], "Aqualon RN-20", "Aquaron RN-30", " Aqualon RN-50 "[above, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.] and the like.

By using a reactive nonionic emulsifier satisfying the above requirements, even if the powder of the base material to be coated is mixed in the paint, the paint does not thicken and the stability is maintained. In addition, since the reactive nonionic emulsifier is incorporated into the polymer skeleton and uniformly distributed in the coating film, it becomes possible to form a coating film having excellent water resistance and the like. For that purpose, the reactive nonionic emulsifier is added in an amount of 0.1% by weight per 100 parts by mass of the ethylenically unsaturated monomer described later.
It is necessary to mix 5 to 20 parts by mass, preferably 2 to 15 parts by mass. The amount of the reactive nonionic emulsifier blended was 0.
If it is less than 5 parts by mass, the stability of the coating composition tends to deteriorate, and if it exceeds 20 parts by mass, the water resistance of the coating film tends to deteriorate, such being undesirable.

In the production of the heterophasic structure emulsion particles, as the emulsifier, a reactive nonionic emulsifier satisfying the above requirements is used together with another emulsifier such as a reactive nonionic emulsifier not satisfying the above requirements or an anionic emulsifier. It is also possible. Examples of such anionic emulsifiers include fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfate ester salts, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfate, polyoxynonyl phenyl ether. Examples thereof include ammonium sulfonate, polyoxyethylene-polyoxypropylene glycol ether sulfate, and so-called reactive emulsifiers having a sulfonic acid group or a sulfate ester group and a polymerizable unsaturated group in the molecule.

As the above-mentioned polymerization initiator, those generally used in the conventional radical polymerization can be used, and among them, water-soluble ones are preferable. For example, persulfates such as potassium persulfate and ammonium persulfate; 2,
Azo such as 2'-azobis (2-aminodipropane) hydrochloride, 4,4'-azobis-cyanovaleric acid, and 2,2'-azobis (2-methylbutanamide oxime) dihydrochloride tetrahydrate Examples of compounds include hydrogen peroxide solution and peroxides such as t-butyl hydroperoxide.
Further, a redox system in which a reducing agent such as L-ascorbic acid or sodium thiosulfate is combined with ferrous sulfate can also be used.

As the above-mentioned chain transfer agent, for example, n-
Long chain alkyl mercaptans such as dodecyl mercaptan, aromatic mercaptans, halogenated hydrocarbons and the like can be mentioned. As the emulsion stabilizer described above,
Examples thereof include polyvinyl alcohol, hydroxyethyl cellulose, polyvinylpyrrolidone and the like.

As the above-mentioned emulsion polymerization method, a monomer batch charging method of charging monomers in a batch, a monomer dropping method of continuously dropping monomers, a monomer, water and an emulsifier Examples of the method include a pre-emulsion method in which and are mixed and emulsified in advance and then added dropwise, or a method in which these are combined.

In producing the emulsion particles of different phase structure by the above-mentioned method, the theoretical Tg determined from the formula of FOX of the polymer forming the outermost phase of the emulsion particles of different phase structure is -50 to 15 ° C, preferably -30 to 30 ° C. 10 ° C
Therefore, it is necessary to appropriately select the combination of the ethylenically unsaturated monomers added in the final stage of the multistage emulsion polymerization. The theoretical Tg of the polymer forming at least one of the internal phases is 50 to 150 ° C, preferably 55 to 100 ° C.
The combination of ethylenically unsaturated monomers needs to be appropriately selected so that the temperature becomes ° C.

When the Tg of the polymer forming the outermost phase of the heterophase emulsion particles is less than -50 ° C, the resulting coating film tends to have poor stain resistance and hot water resistance. When it exceeds the above range, the film-forming property tends to deteriorate at low temperature, which is not preferable. If the Tg of the polymer forming the internal phase is less than 50 ° C., the resulting coating film tends to have poor blocking resistance and physical properties.
On the contrary, if the temperature exceeds 150 ° C, the curing reaction does not proceed, which is not preferable.

In the present invention, the MFT of the particles in the aqueous emulsion is 30 ° C. or less, preferably -10 to 20 ° C.
Therefore, it is necessary to appropriately select the combination of ethylenically unsaturated monomers. If the MFT of the particles in the aqueous emulsion composition exceeds 30 ° C., the film-forming property deteriorates unless a large amount of film-forming auxiliary is used, which is not preferable.

When the aqueous emulsion composition of the present invention satisfies the above-mentioned characteristics and conditions, it can be formed into a film without using VOC such as a film-forming auxiliary agent, or even if it is used in a small amount. In addition, it is possible to form a coating film having excellent properties such as high water resistance.

The aqueous emulsion composition of the present invention is adjusted to pH 6 to 10 with ammonia or amines such as triethylamine, trimethylamine and dimethylethanolamine in order to improve freeze-thaw stability and storage stability. Preferably.

Glycerin, glycols such as ethylene glycol, and the like; molybdenum, ethyl, and the like used in the aqueous emulsion composition of the present invention as a wetting agent having an evaporation rate of 30 or less when calculated with the evaporation rate of butyl acetate being 100. Carbitols such as carbitol acetate; pyrrolidones such as N-methyl-2-pyrrolidone and 2-pyrrolidone; water-soluble wetting agents such as DMSO (dimethyl sulfoxide) can be mentioned, and the kind thereof is not particularly limited. . In the aqueous emulsion composition, the emulsion particles of different phase structure, the wetting agent and the water are the emulsion particles of different phase structure / wetting agent / water = 1.
It is preferable to mix them in a ratio of about 20 / 0.01 to 50/30 to 99 (mass%).

The aqueous emulsion composition according to the present invention contains a wetting agent having an evaporation rate of 30 or less when the evaporation rate of heterophase emulsion particles obtained by the above multistage emulsion polymerization method and butyl acetate is calculated as 100. This aqueous emulsion composition can be used as it is as a clear paint or clear ink. In addition, in order to impart various functions as a paint or ink, as necessary, an antifoaming agent, an antiseptic agent,
Antifungal agents, thickeners, freeze stabilizers, wetting agents, UV absorbers, light stabilizers, pigments, dyes and the like known additives can be blended. When blending pigments and dyes, It is preferable to add known additives such as a dispersant and an anti-settling agent.

The aqueous emulsion composition thus obtained is an inorganic type, a metal type, a wood type, a plastic type,
It can be applied to various base materials such as paper. In particular, it is suitable as a base treatment agent for ink, paint, etc., an overcoat agent for printing / painting, and a surface treatment agent. By naturally drying or forced drying, the drying time can be extended and the drying time can be freely set. It is possible to adjust.

In the method for preventing nozzle clogging of the present invention, it is essential to maintain a humidified state around the nozzle opening, preferably a humidity of 90% or more, in the state where the aqueous emulsion composition is present in the nozzle. is there. In the present invention, the state in which the aqueous emulsion composition is present in the nozzle is a state in which the aqueous emulsion composition is present in the nozzle but not discharged from the nozzle,
Alternatively, it is both a state where the nozzle is not discharging and a state where the nozzle is discharging. In the present invention, it is essential to maintain a humidified state around the nozzle opening when the aqueous emulsion composition is present in the nozzle but is not discharged from the nozzle.

In the method of preventing clogging of the nozzle of the present invention, the method and means for maintaining the periphery of the nozzle opening in a humidified state are not particularly limited. For example, a cap is provided at the tip of the nozzle when the nozzle is not discharging. There may be mentioned a method of maintaining a humidified state inside the cap, a method of intermittently supplying humidified air around the nozzle opening, and the like.

[0037]

[Examples] The present invention will be described in more detail below with reference to production examples of aqueous emulsions containing heterophasic structure emulsion particles, examples of the present invention and comparative examples, but the present invention is not limited thereto. . In addition, "part" in a manufacture example, an Example, and a comparative example is shown on a mass basis.

<Production of Aqueous Emulsions A, B and C Containing Emulsion Particles of Different Phase Structure> In a reactor equipped with a stirring device, a thermometer, a cooling pipe and a dropping device, ion-exchanged water 40
0 part, sodium hydrogencarbonate (pH adjuster) 1 part, reactive nonionic emulsifier "Adecaria Soap NE-20" (manufactured by Asahi Denka Co., Ltd.) [α- (1- (allyloxy) methyl-2- (nonyl) Phenoxy) ethyl) 80% aqueous solution of ω-hydroxypolyoxyethylene; ethylene oxide average addition mole number 20 moles] 5 parts, reactive anion emulsifier "Adekaria Soap SE-10N" (manufactured by Asahi Denka Kogyo KK) [α- Sulfo-ω- (1- (nonylphenoxy) methyl-2- (2-propenyloxy) ethoxy-
Ammonium salt of polyoxy-1,2-ethanediyl); average number of moles of ethylene oxide added: 10 moles] 2
Each part was charged, and the inside of the reactor was replaced with nitrogen, and the temperature was raised to 80 ° C.

Then, potassium persulfate (polymerization initiator) 1
Then, an emulsion (A) having the composition shown in Table 1 (numerals indicate the number of parts), which had been stirred and mixed in a separate container in advance, was added.
Was continuously added dropwise over 2 hours. The reaction temperature was lowered to 75 ° C. in 1 hour after the completion of the dropping in the first step. Then 1
The emulsion (B) having the composition shown in Table 1 (numerals indicate the number of parts), which had been stirred and mixed in advance as in the first step, was continuously added dropwise over 2 hours. After the dropwise addition was completed, the mixture was aged at 75 ° C. for 2 hours with continuous stirring, cooled to 40 ° C., and 50% dimethylethanolamine was added to adjust the pH to 9.0. Further, a hydrazide group-containing compound shown in Table 1 (numbers indicate the number of parts) was added, and aqueous emulsions A and B in which emulsion particles having a heterophasic structure each consisting of two phases were dispersed
And C. However, the Tg of the polymer forming the outermost phase of the emulsion particles of different phase structure in the aqueous emulsion C was 26 ° C. (higher than the upper limit of the range specified in the present invention).

<Production of Emulsion Particle-Containing Aqueous Emulsion D> In a reactor equipped with a stirrer, a thermometer, a cooling pipe, and a dropping device, 200 parts of ion-exchanged water, 1 part of sodium hydrogen carbonate, and a reactive nonionic emulsifier were used. 5 parts of "ADEKA REASOAP NE-20" and 2 parts of "ADEKA REASOAP SE-10N" as a reactive anion emulsifier were charged, respectively, and the temperature was raised to 80 ° C while replacing the inside of the reactor with nitrogen.

Then, potassium persulfate (polymerization initiator) 1
Then, an emulsion (A) having the composition shown in Table 1 (numerals indicate the number of parts), which had been stirred and mixed in a separate container in advance, was added.
Was continuously added dropwise over 4 hours. After dropping is completed, 8
The mixture was aged at 0 ° C. for 2 hours with stirring, cooled to 40 ° C., and then 50% dimethylethanolamine was added to p.
It was adjusted to H9.0. Further, a hydrazide group-containing compound shown in Table 1 (numbers indicate the number of parts) was added to obtain an aqueous emulsion D in which emulsion particles were dispersed. In this case, the obtained emulsion particles did not have a heterophasic structure.

The abbreviations of the respective raw materials shown in Table 1 have the following meanings, and the temperature in parentheses after the respective raw materials is the homopolymer of each monomer used in the calculation of Tg. The Tg of is shown. <Ethylenically unsaturated monomer> ST: Styrene (100 ° C) MMA: Methyl methacrylate (105 ° C) BA: Butyl acrylate (-54 ° C) MAA: Methacrylic acid (185 ° C) 2EHA: Acrylic acid-2 -Ethylhexyl (-50
AA: Acrylic acid (106 ° C.) DVB: Divinylbenzene (116 ° C.) GMA: Glycidyl methacrylate (41 ° C.) DAAM: Diacetone acrylamide (65 ° C.) AAEM: Acetoacetoxyethyl methacrylate (1)
1 ° C.) <hydrazide group-containing compound> ADH: adipic acid dihydrazide CH: carbohydrazide

[Tg (total,
C.) "is the" Tg of the polymer obtained when the mixture of the emulsion (A) and the emulsion (B) is emulsion polymerized in one stage ", and" Tg (core / shell, ° C. ) ”Is“ T of the polymer which is the internal phase obtained when the emulsion A is polymerized alone.
g / Tg of polymer as an external phase obtained by polymerizing Emulsion B alone.

[0044]

[Table 1]

Any of the aqueous emulsions A to D shown in Table 1 obtained as described above and a wetting agent shown in Table 2 were blended so as to have a composition (part) shown in Table 2 and then aqueous. Emulsion compositions were prepared and nozzle clogging tests were conducted on those aqueous emulsion compositions. The results are shown in Table 2.

The test method and evaluation were carried out as follows. Epson printer: PM-770C was used and left for 7 days after the completion of printing, and then reprinted to visually check for nozzle clogging. <Evaluation Criteria> A: No nozzle clogging occurred, and continuous use was possible. C: Nozzle clogging occurred, and continuous use was difficult.

[0047]

[Table 2]

As is clear from the evaluation results shown in Table 2,
The aqueous emulsion composition used in the present invention was excellent in nozzle clogging. On the other hand, Tg of the outermost shell
Nozzle clogging occurred when the emulsion C containing the emulsion particles having a high heterogeneous structure was used and when the emulsion D containing the single phase particles was used.

Example 1 An aqueous emulsion composition comprising 6 parts of the aqueous emulsion A obtained as described above, 20 parts of glycerin and 74 parts of water, and a printer manufactured by Epson Corporation: PM-770C were used. Provide a cap on the tip,
The humidity inside the cap was maintained at 95%. Room temperature is 20 ° C
Met. While maintaining this state, printing was performed every 10 days and the clogging of the nozzle was visually confirmed. No nozzle clogging occurred even after 30 days, and continuous use was possible.

Comparative Example 1 An aqueous emulsion composition consisting of 6 parts of the aqueous emulsion A obtained as described above, 20 parts of glycerin and 74 parts of water, and a printer manufactured by Epson Corporation: PM-770C were used. Without leaving a cap on the tip, it was left as it was in the atmosphere. Room temperature was 20 ° C. After maintaining this state, printing was performed 10 days later, and clogging of the nozzle was visually confirmed. After 10 days, the nozzle was clogged, and continuous use was difficult.

[0051]

EFFECT OF THE INVENTION By adopting the method for preventing nozzle clogging of the present invention, it is possible to prolong the time until the aqueous emulsion composition is dried and solidified at the nozzle tip. For example, an aqueous coating composition such as an aqueous paint, It is possible to prevent clogging of a nozzle of a coating machine, a printing machine, a printer or the like used for coating, printing or printing by discharging a water-based ink composition such as a printing ink from a nozzle.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuneo Shirota             Bell, 1-18-3 Nakazato, Minami-ku, Yokohama-shi, Kanagawa             Che 31 No. 102 (72) Inventor Masaaki Kunimatsu             Kanagawa Prefecture Yokohama City Totsuka-ku 3-3, 10 F-term (reference) 2C056 EA17 FC01 JA25                 4D075 BB56Y BB56Z BB65Y BB65Z                       BB79Y BB79Z CA50 EA13

Claims (5)

[Claims] 1. A method for maintaining a humidified state around a nozzle opening in a state where an aqueous emulsion composition is present in a nozzle, wherein the aqueous emulsion composition is a heterophase structure particle obtained by a multistage emulsion polymerization method, And a wetting agent having an evaporation rate of 30 or less calculated with the evaporation rate of butyl acetate being 100. (1) The heterostructure particles have a total average number of addition moles in one molecule of ethylene oxide of 15 moles or more. Nonionic emulsifier having a chain and / or a propylene oxide chain 0.
It is obtained by multistage emulsion polymerization of an aqueous emulsion containing 5 to 20 parts by weight and 100 parts by weight of an ethylenically unsaturated monomer, and (2) the polymer forming the heterophase structure particles is all ethylene. Containing 20% by weight or more of the monomer unit composed of a polyunsaturated monomer, a monomer unit composed of styrene or a derivative thereof, and (3) the glass transition temperature of the polymer forming the outermost phase of the heterophase structured particles is -50 to 15 ° C., and (4) the glass transition temperature of the polymer forming at least one phase inside the outermost phase of the heterophase structure particles is 50 to 15
0 ° C., and (5) the minimum film forming temperature of the particles in the aqueous emulsion is 3
A method for preventing nozzle clogging, which is 0 ° C. or less. 2. The method for preventing nozzle clogging according to claim 1, wherein the hetero-phase structure particles are such that a polymer forming at least one phase inside the outermost phase has an internal cross-linking structure. 3. Outer phase of heterophase structured particles contains 1 to 25% by mass of monomer units composed of ethylenically unsaturated monomers having a carbonyl group, based on all monomer units composed of ethylenically unsaturated monomers. The method for preventing nozzle clogging according to claim 1 or 2, which is a reaction product of the polymer to be reacted with a compound having two or more hydrazide groups in the molecule. 4. Whether the state in which the aqueous emulsion composition is present in the nozzle is non-expelling from the nozzle,
Alternatively, the method for preventing nozzle clogging according to claim 1, 2 or 3, both during non-ejection from the nozzle and during ejection. 5. The method for preventing nozzle clogging according to claim 1, 2, 3 or 4, wherein the humidified state is a humidity of 90% or more.