WO2012161299A1

WO2012161299A1 - Pigment dispersion paste, and method for producing same

Info

Publication number: WO2012161299A1
Application number: PCT/JP2012/063422
Authority: WO
Inventors: 裕司林
Original assignee: 旭化成ケミカルズ株式会社
Priority date: 2011-05-26
Filing date: 2012-05-25
Publication date: 2012-11-29
Also published as: JP6131185B2; JPWO2012161299A1

Abstract

A pigment dispersion paste containing 5 to 60 mass % of a pigment and 0.1 to 30 mass % of a resin, said pigment dispersion paste also containing, per 100 parts by mass of the pigment, 0.3 to 20 parts by mass of a non-dispersion cellulose having an average polymerization degree of more than 100 and 230 or less.

Description

Pigment dispersion paste and method for producing the same

The present invention relates to a pigment dispersion paste for an electrodeposition paint having high storage stability and excellent salt resistance and water resistance when used in an electrodeposition paint, and an efficient method for producing the pigment dispersion paste.

Conventionally, sedimentation, fixation and separation of water-insoluble matter (mainly pigments) in aqueous dispersions of pigments such as paints and inks have been a problem. Further, from the viewpoint of environmental problems and VOC regulations in recent years, paints are also being made into water-based paints that reduce pollution by changing part or all of organic solvents to water.

However, there is a problem that the stability is poor compared to the solvent type because there is a limit to the stabilizer that can be used in the aqueous type. In order to solve the above problems, it is common to increase the viscosity using a thickener, but in order to achieve both coatability and smoothness, extremely precise viscosity control is required. In addition, there is a problem that this method cannot be used for paints that require low viscosity, such as electrodeposition paints.

On the other hand, a technique using cellulose or a cellulose composite is already known as a pigment having a relatively low viscosity and capable of preventing sedimentation, fixing, and imparting redispersibility of the pigment. For example, Patent Document 1 describes a pigment dispersion paste for electrodeposition paint using a cellulose composite and an electrodeposition paint composition using the same. Patent Document 2 discloses that the standing stability of an inorganic pigment is improved using microcrystalline cellulose. Patent Document 3 discloses an aqueous resin paint that contains atomized cellulose and can be sprayed. Patent Document 4 discloses a technique in which crystalline cellulose is used in an ink composition for the purpose of preventing pigment settling.

JP 2006-111699 A Japanese Patent Laid-Open No. 5-132644 JP-A-5-163445 JP 2006-45248 A

Here, the suspension stability, redispersibility, and storage stability in the present specification will be described. The suspension stability means that a component such as a pigment is stabilized without causing sedimentation or aggregation when the pigment dispersion paste or paint is stored for a long period of time. On the other hand, the redispersibility means that, even when stored for a long period of time, although precipitation of pigments or the like is observed, it can be easily returned to the state before long-term storage by stirring or the like. Storage stability means that pigment pastes and paints are superior in suspension stability, redispersibility, or both, so that they do not cause problems in physical properties even after long-term storage.
It has been disclosed that the storage stability of a pigment can be imparted by using a cellulose composite by the conventional technology. For example, Patent Document 1 shows that pigment dispersion paste using a cellulose composite can impart suspension stability and redispersibility of a pigment in an electrodeposition paint. However, in the case of a cellulose composite, if the compatibility between the added water-soluble polymer and the resin is poor, it is difficult to exert a suspension stabilizing function or a redispersibility imparting function, and pre-dispersion is necessary in advance. If the addition amount of the cellulose composite is increased when storage stability cannot be imparted due to insufficient addition amount, the storage stability is obtained, but the water resistance of the coating film is lowered. Moreover, also in patent document 2, since the cellulose composite was used in the Example and this also contains a water-soluble component, there existed the same faults as patent document 1. Patent Document 3 discloses an aqueous resin coating composition containing atomized cellulose. However, as described in the specification of Patent Document 3, production of micronized cellulose is very troublesome and has a big problem that it is not practical. Also in Patent Document 4, a cellulose composite is used, and the pigment described in Patent Document 4 can be used in applications where water resistance is not a problem as in ink compositions. When the pigment is used for an application that requires high properties, there is still a problem.

As a result of intensive studies to solve the above problems, the present inventor is not surprisingly stable even when the cellulose itself is suspended in water, but it is surprising to use non-dispersible cellulose having a specific average degree of polymerization. In addition, the present inventors have found that a pigment dispersion paste that can be easily produced by a normal pigment dispersion process, has excellent storage stability, and has excellent salt resistance and water resistance when formed into a coating material has been achieved. That is, the present invention uses a non-dispersible specific cellulose having a specific average degree of polymerization, a pigment dispersion paste for electrodeposition paint having high storage stability, excellent salt resistance and water resistance, and a method for producing the same Is to provide.
That is, the present invention is as follows.
(1) A pigment-dispersed paste containing 5 to 60% by weight of pigment and 0.1 to 30% by weight of resin, comprising non-dispersible cellulose having an average degree of polymerization of more than 100 and not more than 230 with respect to 100 parts by weight of pigment. The above pigment dispersion paste containing 0.3 to 20 parts by mass.
(2) The pigment dispersion paste according to (1), wherein the resin is a cationic resin.
(3) The pigment dispersion paste according to (1), wherein the resin is an anionic resin.
(4) Any one of (1) to (3), wherein non-dispersible cellulose having an average degree of polymerization of 100 or more and 230 or less, a pigment, a resin, and water are mixed and pulverized by a bead mill. A method for producing a pigment dispersion paste.
(5) An electrodeposition paint comprising the pigment dispersion paste according to any one of (1) to (3).
(6) An electrodeposition paint containing a pigment-dispersed paste in which a 500 ml graduated cylinder conforming to JIS-R-3505 is charged with an electrodeposition paint up to a scale of 500 ml and the precipitate after being allowed to stand for 200 hours settles at a height of 3 mm or more. Wearing paint.
(7) When a crosscut scratch having a length of 100 mm was put into a depth of 20 μm with a cutter having a blade thickness of 0.38 mm on the coated surface of the coated plate coated with the electrodeposition paint with a thickness of 20 μm, JIS -The electrodeposition coating material according to (6), wherein the maximum width of rust and blisters from a cutter scratch is less than 2 mm when a salt spray test for 1000 hours is conducted according to Z-2371.

According to the present invention, it is possible to provide a pigment dispersion paste having high storage stability and excellent salt resistance and water resistance when used in a paint, and an efficient method for producing the pigment dispersion paste.

Hereinafter, the present invention will be described in detail.
The non-dispersible cellulose used in the present invention is mainly composed of cellulose. For example, cellulose materials such as wood pulp and refined linter are dissolved by acid hydrolysis, alkaline oxidative decomposition, enzymatic decomposition, etc. Cellulose obtained by polymerization treatment is substantially free of a composite component (the definition of the composite component will be described later), has an average degree of polymerization of more than 100 and not more than 230, and a cellulose concentration of 1 When it is dispersed in pure water with a high-speed stirrer, for example, an Excel auto homogenizer (ED-7 type, manufactured by Nippon Seiki Co., Ltd.) for 5 minutes at 15000 rpm, and the resulting dispersion is left for 24 hours. That cause sedimentation (non-dispersibility). The average degree of polymerization here means that measured by the method of confirmation test (3) of crystalline cellulose defined by the 15th revision Japanese Pharmacopoeia. The term “substantially free” as used herein means that the composite component in cellulose is 1% by mass or less. The average degree of polymerization of the cellulose of the present application is more than 100 and 230 or less. By setting the average polymerization degree to more than 100, an increase in water-soluble components can be suppressed, the water resistance is not affected, the aggregation is hardly caused, and the storage stability is excellent. By setting the average degree of polymerization to 230 or less, the effects of the present invention are obtained, and in addition, the occurrence of unevenness in the coating film is less likely to occur. The preferred average degree of polymerization is 110 to 200, more preferably 120 to 170.

The volume average particle size of the non-dispersible cellulose used in the present invention is preferably 1 to 500 μm. The volume average particle size here is dispersed in pure water so that the cellulose concentration is 1% by mass with an Excel auto homogenizer (ED-7 type, manufactured by Nippon Seiki Co., Ltd.) at 15000 rpm for 5 minutes. The value obtained by measuring the volume average particle diameter of the liquid. The analysis of the volume average particle diameter means a value at which the integrated volume is 50% when measured with a laser diffraction scattering apparatus (LA-910, manufactured by Horiba, Ltd.) with a relative refractive index of 1.2 and with ultrasonic waves. In general, the smaller the volume average particle size, the smaller the effect on the coating film when used in an electrodeposition paint, but this is preferable. However, cellulose having a small volume average particle size has a high production cost and the volume average particle size is small. Is generally difficult to obtain or very expensive. The non-dispersible cellulose used in the present invention has an excellent effect that even when the volume average particle size is large, the influence on the coating film when used in an electrodeposition coating is small. In the present invention, a cellulose having a volume average particle size of 10 to 150 μm, which is readily available and inexpensive, is more preferable, and a cellulose having a volume average particle size of 15 to 90 μm is most preferable.

In the past, it was normal to use a cellulose composite with good dispersibility for the paint. A cellulose composite is obtained by mixing cellulose and a hydrophilic polymer within a ratio of cellulose: hydrophilic polymer = 90 to 10:10 to 90 mass ratio, wet-grinding, drying and pulverizing. Usually, the hydrophilic polymer is contained in the cellulose composite in an amount exceeding 10% by mass. Due to the presence of the hydrophilic polymer, cellulose is easily dispersed to the level of fine particles, and exhibits a function of stabilizing the suspension and imparting redispersibility. However, in the case of a cellulose composite, if the compatibility between the added hydrophilic polymer and the resin is poor, it is difficult to exert a suspension stabilizing function or a redispersibility imparting function, and preliminary dispersion or the like is necessary in advance. When the addition amount of the cellulose composite was increased, there was a drawback that the water resistance of the coating film deteriorated. On the other hand, it has been usual that even when cellulose not containing a hydrophilic polymer is added, the suspension stabilizing function and the redispersibility imparting function are hardly exhibited.

However, surprisingly, when a non-dispersible cellulose which does not substantially contain a composite component in cellulose and has an average degree of polymerization of more than 100 and not more than 230 is used in a normal pigment dispersion step, the obtained pigment dispersion It was found that the paste exhibits a suspension stability function and a redispersibility imparting function that exceed those when a cellulose composite is used. For example, the composite component is substantially not included and the average degree of polymerization exceeds 100, as compared with the case where a cellulose complex of sodium carboxymethylcellulose, which is a hydrophilic polymer, and titanium oxide are dispersed in a bead mill in the presence of water. Since the present inventor has found that the suspension stability function and the redispersibility imparting function are surprisingly better when the bead mill dispersion of 230 or less cellulose, sodium carboxymethyl cellulose and titanium oxide is present in the presence of water. is there.

This indicates that, even when the same carboxymethyl cellulose is included, it is easier to produce a pigment dispersion paste if the cellulose is not complexed in advance, and compatibility with the blended resin and water resistance are improved. It also means that there is little need to consider the impact. For example, in an electrodeposition paint using the pigment dispersion paste of the present invention, an X-shape having a length of 100 mm is formed on a coating surface of a coated plate on which the paint is applied with a thickness of 20 μm with a cutter knife having a blade thickness of 0.38 mm. Water resistance with a maximum width of rust and blisters of less than 2 mm from the above-mentioned scratches when a 1000-hour salt spray test is conducted in accordance with JIS-Z-2371 when scratches (cross-cut scratches) are attached. Show salt and salt resistance.

Here, the composite component refers to a component that forms a composite with cellulose and does not volatilize at 100 ° C. Examples of components that can be complex components include carboxymethylcellulose and salts thereof, xanthan gum, caraya gum, carrageenan, gum arabic, glucomannan, gellan gum, alginic acid and salts thereof, and hydrophilic polymers such as propylene glycol alginate. It is done. Since the composite component in the present invention refers to a composite with cellulose, it does not include a simple mixture of components that can be composite components with cellulose. That is, the above-mentioned components that can be complex components are simply mixed with the cellulose powder that can be determined not to be complexed by determining whether the components that can be complexed with cellulose to be described later are complex. Those included in the non-dispersible cellulose as defined in the present invention are substantially free from a composite component and have an average degree of polymerization of more than 100 and 230 or less.

In general, whether a component that can form a complex with cellulose can be determined based on whether it can be a stable aqueous dispersion, and it can be determined by a general dispersion using a high-speed stirrer or homogenizer. It can be judged by operating and measuring the particle size of cellulose. For example, a high-speed stirrer such as an Excel auto homogenizer (Nippon Seiki Co., Ltd.) is added to pure water so that the cellulose composition containing a component that can be a composite component is 1% by mass of cellulose with respect to pure water. This is determined by measuring the volume average particle diameter of cellulose in the liquid after the dispersion operation for 5 minutes at 15000 rpm. In other words, the liquid after the dispersion operation is a value (volume average particle diameter) at which the integrated volume is 50% when measured at a relative refractive index of 1.2 with a laser diffraction scattering apparatus (LA-910, manufactured by Horiba, Ltd.) immediately after the dispersion operation. If it is 10 μm or less, a stable aqueous dispersion can be obtained, so that it can be determined that the component that can be a complex component forms a complex. In this case, since the component that can be a composite contained in the cellulose composition can be said to be a composite component, it is a cellulose composite and is different from the non-dispersible cellulose in the present invention. Here, it should be noted that the non-dispersible cellulose of the present invention does not disperse stably in the dispersing operation, and thus precipitates with time. Therefore, it is necessary to carry out a dispersion operation and to analyze before sedimentation occurs. After the dispersion operation, put it into the laser diffractometer within 10 seconds for analysis, or before putting it in the laser diffractometer, make the liquid after dispersion operation seem to be uniformly dispersed by stirring or shaking. It is necessary to measure.

In the present invention, the content of the non-dispersible cellulose is 0.3 to 20 parts by mass with respect to 100 parts by mass of the pigment. By setting the amount to 0.3 parts by mass or more with respect to the pigment, the suspension stability and the redispersibility imparting function, which are the effects of the present invention, can be sufficiently obtained. Suspension stability and redispersibility imparting function tend to improve as the content of non-dispersible cellulose increases with respect to the pigment, but having a mass of 20 parts by mass or less greatly affects the color of the pigment. Does not affect. The content of non-dispersible cellulose is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass.

The pigment used in the present invention is not particularly limited, and the shape of the pigment is not particularly limited, such as a plate shape, a spherical shape, or a scale shape, and can be used. For example, zinc chromate, lead chromate, red lead, zinc phosphate, vanadium phosphate, calcium phosphate, aluminum phosphomolybdate, calcium molybdate, aluminum tripolyphosphate, bismuth oxide, bismuth hydroxide, basic bismuth carbonate, bismuth nitrate Anti-corrosive pigments such as bismuth silicate, hydrotalcite, zinc dust, mica-like iron oxide, calcium carbonate, barium sulfate, alumina white, silica, diatomaceous earth, kaolin, talc, clay, mica, barita, organic bentonite, white Body pigments such as carbon, titanium dioxide, zinc white, antimony oxide, lithopone, lead white, carbon black, iron black, composite metal oxide black, perylene black, molybdenum red, cadmium red, Bengala, cerium sulfide, yellow lead, cadmium yellow, Color iron oxide, ocher, bismuth yellow, sheena, amber, green clay, mars violet, ultramarine, bitumen, basic lead sulfate, basic lead silicate, zinc sulfide, antimony trioxide, calcium complex, phthalocyanine blue, phthalocyanine green Color pigments such as ocher, metal powder pigments such as aluminum powder, copper powder, brass powder and stainless steel powder, pearlescent pigments such as titanium oxide coated mica, metal oxide coated mica such as iron oxide coated mica, zinc oxide Examples thereof include single or a mixture of two or more special function pigments such as copper, silver particles, anatase-type titanium oxide, iron oxide-based calcined pigment, conductive metal powder, and electromagnetic wave absorbing ferrite. The primary volume average particle diameter of the pigment is preferably 10 μm or less. More preferably, it is 5 μm or less. If it is 10 micrometers or less, there is no possibility that dispersion stability will fall and the smoothness of a coating film may not be impaired. Although there is no restriction | limiting in particular in a minimum, Generally available ultrafine pigment is about 10 nm. Particularly preferred pigments for the paint of the present application include carbon black, titanium white, titanium dioxide, talc, clay, kaolin and the like.

The pigment content in the pigment dispersion paste is 5% by mass to 60% by mass, preferably 10% by mass to 50% by mass. By setting the content to 5% by mass or more, the pigment content is not too low, and it can be used for paints. On the other hand, the viscosity of a paste does not become too high by making content of a pigment 60 mass% or less.

The pigment dispersion paste of the present invention contains at least one kind of resin. In particular, the resin in the present invention is preferably an anionic or cationic resin having a charge. Examples of the resin include an aqueous acrylic resin, a modified acrylic resin, an aqueous urethane resin, an aqueous acrylic urethane resin, an aqueous vinyl chloride resin, an aqueous vinyl acetate resin, an aqueous epoxy resin, an aqueous polyester resin, an aqueous alkyd resin, an aqueous polyamide resin, and an aqueous resin. Cellulosic resins can be used. In particular, an amino group-containing epoxy resin such as a tertiary amine type, or a pigment dispersion resin such as a quaternary ammonium salt type epoxy resin or a quaternary ammonium salt type resin is preferable.

Also, a synthetic polymer emulsion can be used as the resin. Examples of synthetic polymer emulsions include styrene-butadiene copolymer latex, polystyrene polymer latex, polybutadiene polymer latex, acrylonitrile-butadiene copolymer latex, polyurethane polymer latex, polymethyl methacrylate heavy polymer. Polymer latex, methyl methacrylate-butadiene copolymer latex, polyacrylate polymer latex, vinyl chloride polymer latex, vinyl acetate polymer emulsion, vinyl acetate-ethylene copolymer emulsion, polyethylene emulsion, carboxy-modified styrene Examples thereof include butadiene copolymer resin emulsions and acrylic resin emulsions.

Examples of the monomer constituting the resin include aliphatic conjugated dienes such as butadiene, isoprene and 2-chloro-1,3-butadiene, aromatic vinyl compounds such as styrene, α-methylstyrene and vinyltoluene, Methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, alkyl acrylates such as ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, vinyl cyanides such as acrylonitrile and methacrylonitrile Examples of the compound include vinyl acetate, vinyl chloride, vinylidene chloride, urethane, and ethylene. Further, as other copolymerizable monomers, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycyl methacrylate, N-methylol acrylamide, N-butoxymethyl acrylamide, acrylamide, sodium styrene sulfonate, if necessary And ethylenically unsaturated carboxylic acids such as itaconic acid, fumaric acid, acrylic acid, methacrylic acid and crotonic acid.

The content of the resin in the pigment dispersion paste is 0.1 to 30% by mass, preferably 0.12 to 15% by mass. By setting the resin content to 0.1% by mass or more, the suspension stability function of the pigment-dispersed paste using the non-dispersible cellulose according to the present invention is sufficiently exhibited. On the other hand, when the content of the resin is 30% by mass or less, the viscosity of the pigment dispersion paste does not become too high, and the production does not become difficult.

Moreover, the pigment dispersion paste of the present invention may further contain an additive as necessary. Additives include pigment dispersants such as surfactants, polydimethylsiloxane, modified silicone compounds, antifoaming agents such as fatty acid esters, thickeners such as polyacrylic acid polymers, polyamides, and organic clays, dibutyltin laurate, dibutyl Organic tin compounds such as tin oxide, dibutyltin oxide, dioctyltin oxide, dibutyltin dibenzoate, amines such as N-methylmorpholine, curing catalysts such as metal salts such as lead acetate, strontium, copper, cobalt, organic copper, Preservatives such as organic tin, organic halogen, phenol and amine compounds, light resistance improvers / ultraviolet absorbers such as benzophenone, benzothiazole, oxalic anilide, hindered amine compounds, phenolic compounds and thioether compounds, anionic surfactants, cations Surfactants, Antistatic agents such as nonionic surfactants, conductive carbon and conductive metal powders, reaction inhibitors such as amine compounds (amino resin paints), hydroquinones (oxidation polymerization, radical curing paints), lactam compounds, oximes Compounds, blocking agents such as aliphatic alcohols, aromatic alkyl alcohols, ether alcohol compounds, sodium hydroxide, potassium hydroxide, lithium hydroxide, diethanolamine, triethanolamine, N-methylaminoethanol, 2-amino- Neutralizing agents such as 2-methylpropanol, N, N-dimethylaminoethanol, formic acid, acetic acid, and lactic acid, flame retardants such as halogen, organophosphorus, antimony compounds, magnesium hydroxide, fine silica, urea, urethane, acrylic, etc. Matting agent such as polymer beads, polyethylene Anti-scratching / non-adhesive agents such as silicone wax, paraffin wax and fluorine wax, anti-color-coding agents such as silicone oil, surfactants, wetting agents such as alkyl phosphate esters and polyamides, and organic solvents such as alcohols. . When necessary, an appropriate amount is used depending on the intended use / function of an additive comprising one or a combination of two or more selected from these.

More specific examples of the aforementioned organic solvent include one or two selected from hydrocarbons, alcohols, polyhydric alcohols, derivatives of polyhydric alcohols, ketones, esters, ethers and carbonates. The solvent which consists of a combination of a seed | species or more is mentioned.

Examples of hydrocarbons include xylene, toluene, hexane, cyclohexane, mineral spirit, turpentine oil, sorben naphtha, and the like. Examples of alcohols include methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonyl alcohol, n-decanol, n-undecanol, and these Isomers, cyclopentanol, cyclohexanol and the like. Preferred are alcohols having 1 to 6 alkyl carbon atoms.

Polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexane Examples include diol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, glycerin, pentaerythritol and the like.

Polyhydric alcohol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol isobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl Examples include ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and cellosolve acetate.

Examples of ketones include acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, and cyclohexanone.

Esters include methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, lactic acid ester, butyric acid ester, dibutyl phthalate, dioctyl phthalate, and cyclic such as ε-caprolactone and ε-caprolactam Examples include esters.

Examples of ethers include diethyl ether, isopropyl ether, n-butyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane and the like.

Examples of carbonates include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and ethylene carbonate.

The pigment dispersion paste of the present invention can be obtained by pulverizing and mixing a pigment, non-dispersible cellulose having a specific average polymerization degree, a resin, and a dispersion medium (usually water) with a bead mill. The bead mill here is a wet medium agitation mill that refines a slurry in which powder and liquid are mixed, filled with beads (media) in a container, rotated, put a raw slurry, An apparatus that grinds and disperses raw materials. SG mill, ball mill, and the like, which are similar mechanisms, are filled with media and rotated to pulverize and disperse the raw material, and are included in the bead mill referred to in this application.

The pigment dispersion paste of the present invention has high storage stability and does not deteriorate the salt resistance and water resistance even if it is a paint. It can be suitably used for paint. The coating method is not particularly limited, such as electrodeposition coating, spray coating, and brush coating. Among these, since the electrodeposition paint has a low viscosity and tends to precipitate when the stirring is stopped, the pigment dispersion paste of the present invention having good suspension stability can be used very usefully.
When the pigment dispersion paste of the present application is used for an electrodeposition paint, it may be used in the same manner as a pigment paste (F1) of a general electrodeposition paint. That is, it is a general method of use in which the resin dispersion (F2) and F1: F2 = 1: 1 to 1: 8 are mixed to form an electrodeposition paint. The resin dispersion (F2) may be a general one. The resin used for the resin dispersion (F2) is not particularly limited, and a resin used for a normal electrodeposition paint may be used. The most common is a modified epoxy resin.
The electrodeposition paint of the present application is excellent in redispersibility. For example, when the electrodeposition paint using the pigment paste of the present invention is placed in a 500 ml graduated cylinder conforming to JIS-R-3505 up to a scale of 500 ml and allowed to stand for 200 hours, the sediment is soft at a height of 3 mm or more. Since it settles, it can be easily redispersed. Similarly, the pigment dispersion paste of the present invention is most effective in electrodeposition paints, but can be used not only in electrodeposition paints but also in inks in which pigments are dispersed. It is.

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Measurement and evaluation were performed as follows. In addition, the measuring method of an average degree of polymerization and a volume average particle diameter is as above-mentioned.

<Evaluation method of pigment dispersion paste>
・ Suspension stability Weigh 50 g of a prototype of pigment dispersion paste into a glass sample bottle, leave this sample in a thermostatic chamber at 25 ° C. for 7 days, then gently remove the sample bottle and stabilize over time according to the following evaluation criteria. Sex was evaluated.
◎ (excellent): No sedimentation separation is observed, and no change is seen from the initial stage.
○ (good): Sedimentation separation is observed slightly, but almost no change is seen from the initial stage.
Δ (possible): Although the supernatant is confirmed by sedimentation separation, the sedimentation is bulky.
X (impossible): The supernatant was completely confirmed by sedimentation separation, and the sediment was completely settled.

-Redispersibility The state after shaking the sample after being left for 7 days with a swing width of about 10 cm at a speed of 2 times / second was observed.
◎ (Excellent): Immediately (within 10 seconds) returns to the state before storage.
○ (Good): Returns to the state before storage after shaking for 11 to 60 seconds.
Δ (possible): Even if it is shaken for 60 seconds, it can be fixed to the wall surface, but a little aggregate remains.
X (impossible): Even after shaking for 60 seconds, adhesion to the wall surface remains, or agglomerates remain clearly.
・ Storage stability (overall evaluation)
By combining the evaluation results of suspension stability and redispersibility, storage stability was evaluated according to the following criteria.
（(Excellent): Either suspension stability or redispersibility is evaluated as ◎.
○ (good): Either the suspension stability or the redispersibility is evaluated as ○.
Δ (possible): The suspension stability and / or redispersibility is evaluated as Δ.
X (impossible): Suspension stability and redispersibility are evaluations of x.

<Evaluation method of paint using pigment dispersion paste>
・ Suspension stability 1
The paint containing the pigment dispersion paste was placed in a 100 ml Nessler colorimetric tube up to a scale of 100 ml, and the state of sedimentation after standing for 48 hours was evaluated according to the following criteria.
◎ (excellent): No sedimentation separation is observed, and no change is seen from the initial stage.
○ (good): Sedimentation is slightly separated, but the sedimentation amount is 10 ml or less.
Δ (possible): Sedimentation separation occurs, and the sedimentation amount exceeds 10 ml and is less than 20 ml.
X (impossible): The supernatant was completely confirmed by sedimentation separation, and the sediment was 20 ml or more.
・ Suspension stability 2
The paint containing the pigment dispersion paste was placed in a 500 ml graduated cylinder conforming to JIS-R-3505 to a scale of 500 ml, and the state of sedimentation after standing for 200 hours was evaluated according to the following criteria.
(Excellent): The height of the sediment is 3 mm or more.
○ (Good): The height of the sediment is less than 3 mm and 2.5 mm or more.
Δ (possible): The height of the sediment is less than 2.5 mm and 1.5 mm or more.
X (impossible): The height of the sediment is less than 1.5 mm.
-Redispersibility After 1L of paint is left for 48 hours, it is stirred with a propeller stirrer (BL-600, manufactured by Shinto Kagaku Co., Ltd.) at 500 rpm for 2 hours, passed through a sieve with an opening of 38 μm, and the amount of residue on the sieve is measured. It was measured.
(Excellent): The amount of residue is less than 5 mg.
○ (Good): Residue amount is 5 mg or more and less than 10 mg.
Δ (possible): Residue amount is 10 mg or more and less than 30 mg.
X (impossible): Residue amount is 30 mg or more.
・ Storage stability (overall evaluation)
By combining the evaluation results of suspension stability and redispersibility, storage stability was evaluated according to the following criteria.
（(Excellent): Either suspension stability or redispersibility is evaluated as ◎.
○ (good): Either the suspension stability or the redispersibility is evaluated as ○.
Δ (possible): The suspension stability and / or redispersibility is evaluated as Δ.
X (impossible): Suspension stability and redispersibility are evaluations of x.

・ Salt resistance / water resistance A steel plate (size: 0.8 × 70 × 150 mm, plain steel (SPCC), surface treatment; phosphate treatment PB-L3020) is immersed in the electrodeposition paint and applied at room temperature as a cathode. Electrodeposition coating was performed with a film thickness of 20 μm under the condition of a voltage of 250 V, washed with water, and baked at 160 ° C. for 10 minutes to prepare a test coating plate. Apply the cross-cut scratch of 100mm length to the depth of 20μm which is the depth where the base steel plate can be seen with a cutter with a blade thickness of 0.38mm on the coated surface of the previous test coated plate according to JIS-Z-2371 The salt spray test for 1000 hours was conducted, and the state of rust and swelling generated from the cutter scratches was observed and evaluated according to the following criteria.
(Excellent): The maximum width of rust and blisters is less than 2 mm from the cut part.
○ (Good): The maximum width of rust and blisters is 2 mm or more and less than 3 mm from the cut part.
Δ (possible): The maximum width of rust and blisters is 3 mm or more and less than 4 mm from the cut part.
X (impossible): The maximum width of rust and blisters is 4 mm or more from the cut part.
Hereinafter, the present invention will be specifically illustrated by examples and comparative examples.

(Example 1, Comparative Example 1, Comparative Example 2)
40 parts by mass of titanium oxide as a pigment, 0.1 part by mass of sodium carboxymethylcellulose as a water-soluble anionic resin, 1 part by mass of cellulose (Example 1 or Comparative Example 1) or cellulose composite (Comparative Example 2), 39 masses of water The parts were mixed and treated with a bead mill (RMB-400, bead diameter 1 mm, manufactured by Imex Co., Ltd.) for 60 minutes to obtain a pigment dispersion paste. The cellulose of Example 1 has an average degree of polymerization of 167 and a volume average particle size of 19 μm and does not substantially contain a composite component (that is, non-dispersible cellulose), and the cellulose of Comparative Example 1 has an average degree of polymerization of 241 and a volume. An average particle size of 5 μm, substantially free of composite components, and cellulose of Comparative Example 2 are cellulose composites (cellulose / karaya gum / dextrin = 75/10/10 mass ratio, average polymerization degree of cellulose 142, composite components) 20 mass%) (49.9 mass% of the pigment in the paste, 0.12 mass% of the resin, and 100 mass parts of the pigment in Example 1 and Comparative Example 1 were 2.5 mass of cellulose. Part, Comparative Example 2 is 1.875 parts by mass).

The evaluation results are shown in Table 1. Example 1 showed good suspension stability, but Comparative Example 1 was very poor in suspension stability and Comparative Example 2 was also better than Comparative Example 1, but worse than Example 1. In Example 1, since no sedimentation was observed, the redispersibility could not be evaluated. In Comparative Example 1, since the average degree of polymerization of cellulose was large, in Comparative Example 2, the function was poor because cellulose was a cellulose composite.

(Example 2, Comparative Examples 3 to 5)
In Example 2, 120 parts by mass of an epoxy-based quaternary ammonium salt type pigment dispersion resin (cationic resin) of 35% by mass, 100 parts by mass of kaolin, 2 parts by mass of carbon black, 8 parts by mass of dibutyltin oxide, phosphomolybdenum 18 parts by weight of aluminum oxide, 184 parts by weight of deionized water, average degree of polymerization 154, volume average particle size 22 μm, 1 part by weight of cellulose (ie non-dispersible cellulose) substantially free of complex components, and SG for water-soluble components Dispersion and mixing were performed with a mill to obtain pigment dispersion paste A (29.6% by mass of pigment, 9.7% by mass of resin, and 0.78 parts by mass of cellulose with respect to 100 parts by mass of pigment). In Comparative Example 3, a cellulose composite (cellulose / xanthan gum / dextrin = 75/5/20 mass ratio, cellulose average polymerization degree 155, composite component 25 mass%) was used instead of cellulose having the above average polymerization degree 154. Except for the above, the same operation as in Example 2 was carried out to obtain a pigment dispersion paste B (0.585 parts by mass of cellulose with respect to 100 parts by mass of pigment). Comparative Example 4 was the same as Example 2 except that instead of the cellulose of Example 2, an average degree of polymerization of 256, a volume average particle size of 25 μm, and a cellulose substantially containing no composite component (non-dispersible cellulose) were used. The pigment dispersion paste C was obtained. In Comparative Example 5, a pigment dispersion paste D was prepared in the same manner except that cellulose was not added.

Subsequently, an electrodeposition paint using the pigment dispersion paste obtained by the above-described manufacturing method was produced. In a separate container, 145 parts by mass of deionized water and 5 parts by mass of acetic acid were weighed, and at 70 ° C., 320 parts by mass of amine-modified epoxy resin (solid content 75 parts by mass), 190 parts by mass of blocked isocyanate curing agent (solid content 25 parts by mass). Part) was added slowly with vigorous stirring and dispersed uniformly. Further, deionized water was added to obtain an emulsion having a solid content of 36% by mass.

To 278 parts by mass of the emulsion (solid content of 100 parts by mass), 69 parts of pigment dispersion paste A (solid content of 33 parts) and 318 parts of deionized water are added and mixed uniformly to obtain the pigment dispersion paste A of the present invention. An electrodeposition coating material A containing (Example 2) was obtained. In Comparative Example 3, instead of Pigment Dispersion Paste A, Pigment Dispersion Paste B, in Comparative Example 4 Pigment Dispersion Paste C, in Comparative Example 5 Pigment Dispersion Paste D were used in 69 parts by weight, respectively. C and D were obtained. Each of the electrodeposition paints A, B, C, and D was immersed in a steel plate, electrodeposited with a film thickness of 20 μm under the condition of an applied voltage of 250 V at room temperature as a cathode, washed with water, and then washed at 160 ° C. for 10 minutes. Baking was performed. Electrodeposition paints A, B, C and D and their coatings were evaluated. The evaluation results are shown in Table 2.

In Example 2, both the pigment dispersion paste and the electrodeposition paint using the same had good suspension stability and redispersibility, and the coating film had good salt resistance and water resistance. In Comparative Examples 3 and 4, as compared with Comparative Example 5 in which no cellulose was used, both the suspension stability and redispersibility of the pigment dispersion paste and the electrodeposition paint using the same were good. Comparative Example 3 was better than Comparative Example 4, but not as well as Example 2. On the other hand, Comparative Examples 3 and 4 had poor salt resistance and water resistance after coating.

The pigment-dispersed paste of the present invention has good storage stability, and when used as a paint, has high salt resistance and water resistance, and therefore can be suitably used for an electrodeposition paint.

Claims

A pigment-dispersed paste containing 5 to 60% by mass of pigment and 0.1 to 30% by mass of resin, and having an average degree of polymerization of more than 100 and not more than 230 with respect to 100 parts by mass of pigment, is 0.00. The above pigment dispersion paste containing 3 to 20 parts by mass.
The pigment dispersion paste according to claim 1, wherein the resin is a cationic resin.
The pigment dispersion paste according to claim 1, wherein the resin is an anionic resin.
The pigment-dispersed paste according to any one of claims 1 to 3, wherein non-dispersible cellulose having an average degree of polymerization of more than 100 and not more than 230, a pigment, a resin, and water are mixed and pulverized by a bead mill. Manufacturing method.
Electrodeposition paint containing the pigment dispersion paste according to any one of claims 1 to 3.
An electrodeposition paint containing a pigment dispersion paste in which a 500 ml graduated cylinder conforming to JIS-R-3505 is filled with an electrodeposition paint up to a scale of 500 ml, and the sediment after being allowed to stand for 200 hours settles at a height of 3 mm or more.
When a crosscut scratch having a length of 100 mm is put into a depth of 20 μm with a cutter having a blade thickness of 0.38 mm on the coated surface of the coating plate coated with the above-mentioned electrodeposition paint with a thickness of 20 μm, JIS-Z- The electrodeposition paint according to claim 6, wherein the maximum width of rust and blisters from a cutter flaw is less than 2 mm when a salt spray test for 1000 hours is performed according to 2371.