JP5456223B2 - Concentrated liquid for preparing surface conditioner, surface conditioner, and surface conditioning method - Google Patents

Description

The present invention relates to a concentrated liquid for preparing a surface conditioning agent, a surface conditioning agent, and a surface conditioning method.

Auto bodies, home appliances, and the like have been commercialized by forming a metal material such as a steel plate, a galvanized steel plate, or an aluminum alloy, and then painting and assembling it. The coating of such a metal molded product is performed through various processes such as degreasing, surface adjustment, chemical conversion treatment, and electrodeposition coating.

Surface conditioning treatment is a treatment that is performed in the next step, phosphate film chemical conversion treatment, to form a film made of phosphate crystals uniformly, rapidly, and at a high density over the entire metal surface. Usually, a crystal nucleus of phosphate is formed on the metal surface by dipping in a surface conditioning tank.

For example, Patent Document 1 discloses a metal from a pre-washing bath containing finely dispersed titanium phosphate or finely dispersed tertiary zinc phosphate and montmorillonite prior to phosphate treatment with a zinc phosphate solution. A method for pretreating a metal surface, characterized by pretreating the surface, is disclosed. The technique disclosed here is a method of maintaining the effect of the pre-washing bath for a long time.

However, the sustaining effect of the pre-washing bath disclosed here is the dispersion stability of the dilute surface conditioning agent used in the surface conditioning (pretreatment) in the processing bath, and is a thick for preparing the surface conditioning agent. The dispersion stability in the liquid (stock solution) is not sufficient. Regarding the surface conditioner, it is usually stored in the form of a concentrated liquid for preparing the surface conditioner, and it is determined by diluting the concentrated liquid for preparing the surface conditioner during use (when actually adjusting the surface). Adjustment to a surface conditioning agent of concentration is performed.

When the dispersion stability of the concentrated liquid for preparing the surface conditioning agent is not excellent, components such as zinc phosphate particles in the liquid may settle and aggregate during storage of the concentrated liquid. When the components in the concentrated liquid have settled, aggregated, etc., when preparing the surface conditioner by diluting the concentrated liquid, it is necessary to first stir the concentrated liquid to uniformly disperse the components in the liquid There is. Further, depending on the degree of sedimentation, aggregation, etc., even if stirred, it may not be uniformly dispersed.

That is, when the dispersion stability of the concentrated liquid for preparing the surface conditioner is not excellent, it is necessary to stir and disperse the concentrated liquid, or the components cannot be uniformly dispersed even after stirring. There may be a problem that the surface adjustment effect cannot be obtained. For this reason, it is desired to develop not only excellent dispersion stability of the surface conditioner but also excellent dispersion stability in the concentrated liquid for preparing the surface conditioner.

Patent Document 2 discloses that at least one selected from phosphates containing at least one divalent or trivalent metal including particles having a particle size of 5 μm or less, and an alkali metal salt or ammonium salt. Or a mixture thereof and anionically charged and dispersed oxide fine particles, an anionic water-soluble organic polymer, a nonionic water-soluble organic polymer, an anionic surfactant and a nonionic surfactant The surface pretreatment liquid for surface adjustment before the phosphate film chemical conversion treatment of the metal containing at least one kind and having a pH adjusted to 4 to 13 is disclosed.

Further, Patent Document 3 contains one or more phosphate particles selected from phosphates containing one or more of divalent and / or trivalent metals, and (1) a monosaccharide, One or more selected from polysaccharides and derivatives thereof, (2) orthophosphoric acid, polyphosphoric acid or organic phosphonic acid compound, a polymer of vinyl acetate or a derivative thereof, a monomer copolymerizable with vinyl acetate, and vinyl acetate One or more of water-soluble polymer compounds comprising the above copolymer, or (3) at least one selected from a specific monomer or an α, β-unsaturated carboxylic acid monomer and the above-mentioned monomer Disclosed is a surface conditioning treatment solution prior to phosphate film chemical conversion treatment, which contains a polymer or copolymer obtained by polymerizing 50% by weight or less of a monomer copolymerizable with the body.

However, the surface conditioning treatment liquid disclosed here is inferior in dispersion stability in the treatment liquid, in particular, dispersion stability in a concentrated liquid of the treatment liquid. Even when an inorganic dispersant is used, when silica is used, the dispersion stability of the concentrated liquid for preparing the surface conditioner is particularly insufficient.

JP 59-226181 A Japanese Patent Laid-Open No. 10-245685 JP 2000-96256 A

In view of the above-mentioned present situation, the present invention provides a concentrated liquid (stock solution) for preparing a surface conditioner having excellent dispersion stability, a surface conditioner (treatment liquid during surface adjustment), and a surface adjustment method using this surface conditioner. It is for the purpose.

The present invention relates to a concentrated solution of the surface modifier for the preparation of pH3~12 containing zinc phosphate particles, the zinc phosphate particles, D ₅₀ is at 3μm or less, thick for the surface modifier prepared The liquid is a concentrated liquid for preparing a surface conditioner (concentrated liquid for preparing a first surface conditioner) characterized in that it contains a layered clay mineral.

In the concentrated liquid for preparing the surface conditioner (the concentrated liquid for preparing the first surface conditioner), the layered clay mineral is preferably natural hectorite and / or synthetic hectorite.

The present invention relates to a concentrated solution of the surface modifier for the preparation of pH3~12 containing zinc phosphate particles, the zinc phosphate particles, D ₅₀ is at 3μm or less, thick for the surface modifier prepared The liquid is bentonite represented by the following formula (I);

(In the formula, R ¹ is a saturated alkyl group having 1 to 22 carbon atoms. R ² is the same or different and is a methyl group, an ethyl group, a propyl group, or a butyl group.) It is also a concentrated liquid for preparing a surface conditioner (concentrated liquid for preparing a second surface conditioner) characterized by containing a surface-treated product with alkoxysilane.

What the present invention is a surface modifier of pH3~12 containing zinc phosphate particles, the zinc phosphate particles, D ₅₀ is at 3μm or less, the surface modifier, containing a layered clay mineral It is also a surface conditioner (first surface conditioner) characterized by being.

In the surface conditioner (first surface conditioner), the layered clay mineral is preferably natural hectorite and / or synthetic hectorite.

The present invention is a surface modifier of pH3~12 containing zinc phosphate particles, the zinc phosphate particles is a D ₅₀ of 3μm or less, the surface modifier, bentonite following formula (I) ;

(In the formula, R ¹ is a saturated alkyl group having 1 to 22 carbon atoms. R ² is the same or different and is a methyl group, an ethyl group, a propyl group, or a butyl group.) It is also a surface conditioner (second surface conditioner) characterized by containing a surface-treated product with alkoxysilane.

The present invention is also a surface conditioning method comprising the step of bringing the surface conditioning agent (first and second surface conditioning agents) into contact with a metal surface.
The present invention is described in detail below.

The concentrated liquids for preparing the first and second surface conditioners of the present invention are concentrated liquids (stock solutions) before being adjusted by diluting the first and second surface conditioners described below. It is a liquid in a state of being stored before use (before surface adjustment). Usually, the first and second surface conditioning agents are prepared by diluting the concentrated liquid for preparing the first and second surface conditioning agents to a predetermined concentration.

The first surface modifier concentrates for the preparation of the present invention (stock solution) contains the following zinc phosphate particles D ₅₀ of 3 [mu] m, and a layered clay mineral is of PH3～12.

The first surface modifier concentrates for the preparation of the present invention, a concentrated solution of the first surface modifier for the preparation of D ₅₀ contains the following zinc phosphate particles 3 [mu] m, further, blended with the layered clay mineral Is. The layered clay mineral is presumed to act as an anti-settling agent in the concentrated liquid. For this reason, not only the precipitation of zinc phosphate particles in the first surface conditioner obtained by diluting the concentrated liquid is prevented, but also the precipitation of zinc phosphate particles in the concentrated liquid is prevented. Long-term dispersion stability can be maintained. By adding a layered clay mineral, an excellent thickening effect can be exhibited, and by adding, a repulsive action of charged particles can also be exhibited. Therefore, the reason why the concentrated liquid for preparing the first surface conditioner can be prevented from being settled is not clear, but due to the synergistic effect of this thickening effect and the repulsive action of the charged particles, extremely excellent precipitation of zinc phosphate particles. As a result, it is presumed that, even as a concentrated liquid, precipitation of zinc phosphate particles can be further prevented, and long-term dispersion stability can be maintained.

The layered clay mineral itself has an electrical repulsion effect. For this reason, when the layered clay mineral adheres around the zinc phosphate particles, the zinc phosphate particles in the concentrated liquid for preparing the first surface conditioner can be stabilized by electrical repulsion. Therefore, in the preparation of the concentrated liquid (stock solution) for preparing the first surface conditioner, the zinc phosphate particles can be further refined when the components such as zinc phosphate particles in the liquid are dispersed. In addition, the dispersion efficiency can be further improved.

The layered clay mineral (clay) is a silicate mineral having a layered structure, etc., and a large number of sheets (tetrahedral sheet composed of silicic acid, octahedral sheet composed further including Al, Mg, etc.) ) Are laminated. By containing the layered clay mineral, excellent dispersion stability can be imparted to the concentrated liquid for preparing the first surface conditioner, and the dispersion efficiency can be improved.

The layered clay mineral is not particularly limited, and examples thereof include smectites such as montmorillonite, beidellite, saponite and hectorite; kaolinites such as kaolinite and halosite; dioctahedral vermiculite and trioctahedral vermiculite. Vermiculite group: Teniolite, tetrasilicic mica, mascobite, illite, sericite, phlogopite, biotite and other mica, etc .; hydrotalcite; pyrophyllolite; A salt etc. can be mentioned. These layered clay minerals may be natural minerals or synthetic minerals by hydrothermal synthesis, melting method, solid phase method or the like.

In addition, intercalation compounds of the above layered clay minerals (pillar crystals, etc.), those subjected to ion exchange treatment, those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) are also used. can do. These layered clay minerals may be used alone or in combination of two or more.

The layered clay mineral preferably has an average particle size (= average value of maximum dimensions) of 5 μm or less, more preferably 1 μm or less. If it exceeds 5 μm, the dispersion stability may decrease. The average aspect ratio (= maximum dimension / minimum dimension average value) of the layered clay mineral is preferably 10 or more, more preferably 20 or more, and still more preferably 40 or more. If it is less than 10, the dispersion stability may be lowered.

The layered clay mineral is preferably natural hectorite and / or synthetic hectorite. Thereby, the more excellent dispersion stability can be provided to the concentrated liquid for preparing the first surface conditioner, and the dispersion efficiency can be further improved.

The natural hectorite is a trioctahedral clay mineral belonging to the montmorillonite group represented by the following formula (II).

As a commercial item of the said natural hectorite, BENTON EW, BENTON AD (made by ELEMENTIS) etc. can be mentioned, for example.

The synthetic hectorite has a crystal three-layer structure, approximates to hectorite belonging to an unlimited layer expansion type trioctahedral having an expansion lattice, and is represented by the following formula (III).

(Wherein, 0 <a ≦ 6, 0 <b ≦ 6, 4 <a + b <8, 0 ≦ c <4, x = 12-2a-b, and M is almost Na) Hectorite is composed of magnesium, silicon, sodium and trace amounts of lithium and fluorine as main components.

The synthetic hectorite has a three-layer structure, and each crystal structure layer in the layered structure is composed of a two-dimensional platelet having a thickness of about 1 nm. Then, some of the magnesium atoms present in the middle layer of the platelet unit are isomorphously substituted with low-valent lithium atoms, and as a result, the platelet unit is negatively charged. In the dry state, this negative charge is balanced with displaceable cations outside the lattice structure of the plate surface, and in the solid phase these particles are bonded together by van der Waals forces to form a flat plate bundle.

When such synthetic hectorite is dispersed in the aqueous phase, the replaceable cation is hydrated to cause the particles to swell, and a stable sol can be obtained when dispersed using a normal disperser such as a high-speed dissolver. Can do. In such a state dispersed in the aqueous phase, the platelets have negative charges on the surface, electrostatically repel each other, and become stable sols subdivided into platelet-like primary particles. However, when the particle concentration is increased or the ion concentration is increased, the repulsive force due to the surface negative charge is reduced, and the other plate edge that is positively charged is electrically connected to the negatively charged platelet surface. It becomes possible to orientate and form a so-called card house structure and to exhibit thickening.

When the above synthetic hectorite is used, excellent thickening can be achieved in this way. Therefore, not only in the first surface conditioner obtained by diluting the concentrated liquid, but also in the concentrated liquid. It is presumed that the precipitation of zinc acid particles can be further prevented, and as a result, the dispersion stability of the concentrated liquid can be maintained for a longer period. In addition, since the zinc phosphate particles in the concentrated liquid for the preparation of the first surface conditioner can be further stabilized, the zinc phosphate particles are made finer when dispersing components such as zinc phosphate particles. It is speculated that the dispersion efficiency can be further improved.

As a commercial item of the said synthetic hectorite, Laporte Industries Ltd. is mentioned, for example. Laponite B, S, RD, RDS, XLG, XLS, etc. can be mentioned by the product name made. It is a white powder and easily forms sol (Laponite S, RDS, XLS) or gel (Laponite B, RD, XLG) when added to water. Another example is Lucentite SWN manufactured by Co-op Chemical. These natural hectorites and synthetic hectorites may be used alone or in combination of two or more.

In the concentrated liquid (stock solution) for preparing the first surface conditioner, the content of the layered clay mineral is preferably 0.1% by mass and the upper limit is 20% by mass. If it is less than 0.1% by mass, the effect of preventing the precipitation of zinc phosphate particles may not be sufficiently obtained. When the amount exceeds 20% by mass, the viscosity increases too much, and it becomes difficult to disperse the stock solution of the concentrated liquid (stock solution) for preparing the first surface conditioner, and it becomes difficult to remove the product from the container. Problems may arise. The lower limit is more preferably 0.3% by mass, and the upper limit is more preferably 10% by mass.

The concentrated liquid (stock solution) for preparing the second surface conditioner of the present invention was obtained by surface-treating zinc phosphate particles having D ₅₀ of 3 μm or less and bentonite with alkyltrialkoxysilane represented by the above formula (I). And has a pH of 3-12. The concentrated liquid (stock solution) for preparing the second surface conditioner has the same effect as that obtained by adding the layered clay mineral in the concentrated liquid for preparing the first surface conditioner described above. It is.

In the alkyltrialkoxysilane represented by the above formula (I), in the above formula (I), R ¹ is a saturated alkyl group having 1 to 22 carbon atoms. R ¹ may be linear or branched. R ² is the same or different and is a methyl group, an ethyl group, a propyl group or a butyl group.

The surface treatment of the above bentonite (montmorillonite) with an alkyltrialkoxysilane is such that in the purified bentonite, the alkyltrialkoxysilane is added to the hydrophilic hydroxyl group on the surface of the bentonite to partially hydrophobize the surface. Thereby, the dispersed particles of the modified bentonite surface-treated in the aqueous dispersion form a plastic structure by association with the hydrophobic group, and the apparent viscosity of the system is remarkably increased.

That is, in the concentrated solution for preparing the second surface conditioner, when bentonite (montmorillonite) is surface-treated with the alkyltrialkoxysilane represented by the above formula (I), It is inferred that excellent thickening can be expressed. As a result, not only in the second surface conditioner obtained by diluting the concentrated liquid, but also precipitation of zinc phosphate particles in the concentrated liquid can be further prevented, and the concentrated liquid is more dispersed over a long period of time. It is inferred that stability can be maintained. In addition, since the zinc phosphate particles in the concentrated liquid for the preparation of the second surface conditioner can be further stabilized, the zinc phosphate particles are made finer when dispersing components such as zinc phosphate particles. It is speculated that the dispersion efficiency can be further improved.

Examples of commercially available products obtained by surface-treating the bentonite (montmorillonite) with the alkyltrialkoxysilane represented by the above formula (I) include Bengel-SH (manufactured by Hojun Co., Ltd.).

Unlike the conventional card house structure formed by montmorillonite in water, the above-mentioned Wenger-SH forms a patchwork structure as shown in FIG. This patchwork structure is a structure in which layered crystal particles of montmorillonite are associated with a flat surface, and therefore can exhibit a much higher viscosity. That is, among the bentonite (montmorillonite) surface-treated with the alkyltrialkoxysilane represented by the above formula (I), those having such a patchwork structure exhibit more effects as described above. Particularly preferred.

The bentonite surface-treated with the alkyltrialkoxysilane represented by the above formula (I) (hereinafter also referred to as “surface-treated bentonite”) preferably has an average particle size (= average value of maximum dimensions) of 5 μm or less. More preferably, it is 1 μm or less. If it exceeds 5 μm, the dispersion stability may decrease. Further, the average aspect ratio (= average value of maximum dimension / minimum dimension) of the surface-treated bentonite is preferably 10 or more, more preferably 20 or more, and still more preferably 40 or more. If it is less than 10, the dispersion stability may be lowered.

In the concentrated liquid (stock solution) for preparing the second surface conditioner, the content of the surface-treated bentonite is preferably a lower limit of 0.1% by mass and an upper limit of 20% by mass. If it is less than 0.1% by mass, the effect of preventing the precipitation of zinc phosphate particles may not be sufficiently obtained. If it exceeds 20% by mass, there will be a problem of handling such as excessive thickening, making it difficult to disperse the concentrated liquid (stock solution) for preparing the second surface conditioner, and making it difficult to remove the product from the container. It may occur. The lower limit is more preferably 0.3% by mass, and the upper limit is more preferably 10% by mass.

In addition to the layered clay mineral and the surface-treated bentonite, the concentrated liquid for preparing the first and second surface conditioners may further contain a dispersant as long as the effects of the present invention are not impaired. it can. It does not specifically limit as said dispersing agent, A conventionally well-known polymer dispersing agent, surfactant, a coupling agent etc. can be mentioned.

The concentrated liquid for preparing the first and second surface conditioners of the present invention contains zinc phosphate particles having a D ₅₀ (volume 50% diameter) of 3 μm or less. By using zinc phosphate having a D ₅₀ of 3 μm or less, a large number of crystal nuclei can be imparted before the phosphate chemical conversion treatment. It can be deposited. In the present specification, the D ₅₀ is an average dispersion diameter and an average particle diameter.

The lower limit of D ₅₀ of the zinc phosphate particles is preferably 0.001 μm and the upper limit is 3 μm. If it is less than 0.001 μm, the particles may aggregate due to the phenomenon of overdispersion. If it exceeds 3 μm, the proportion of fine zinc phosphate particles decreases, which is inappropriate. The lower limit is more preferably 0.005 μm, and the upper limit is more preferably 1 μm.

The concentrated liquids for preparing the first and second surface conditioners preferably contain zinc phosphate particles having a D ₉₀ (volume 90% diameter) of 4 μm or less. In this case, the zinc phosphate particles not only have a D ₅₀ of 3 μm or less, but also a D ₉₀ of 4 μm or less, so that the proportion of coarse particles in the zinc phosphate particles is relatively small. As described above, by using zinc phosphate having an average particle diameter (D ₅₀ ) of 3 μm or less, fine phosphate crystals can be precipitated in a short time chemical conversion treatment, but dispersed to 3 μm or less. Therefore, when using a means such as pulverization, if excessively pulverized, the layered clay mineral accompanying the increase in specific surface area, surface treatment bentonite shortage occurs, overdispersed particles agglomerate, and instead coarse particles are formed. An overdispersion phenomenon that impairs dispersion stability occurs. Also, dispersion of dispersion occurs depending on the blending and dispersion conditions of the concentrated liquid for preparing the first and second surface conditioners, and aggregation and thickening due to close packing of coarse particles and fine particles, and between fine particles It causes a phenomenon such as aggregation. However, when the above-mentioned zinc phosphate has a D ₉₀ (volume 90% diameter) of 4 μm or less, it is possible to further prevent the above-described disadvantages from occurring.

_{D 90} of the zinc phosphate particles is preferably lower limit 0.01 [mu] m, an upper limit 4 [mu] m. If it is less than 0.01 μm, the particles may aggregate due to the phenomenon of overdispersion. If it exceeds 4 μm, the proportion of fine zinc phosphate particles decreases, which is inappropriate. The lower limit is more preferably 0.05 μm, and the upper limit is more preferably 2 μm.

The D ₅₀ (volume 50% diameter) and the D ₉₀ (volume 90% diameter) are calculated based on the particle size distribution in the dispersion, and the cumulative curve is calculated when the total volume of the particles is 100%. The particle sizes are 50% and 90%, respectively. The _{D 50} and the _{D 90} is, for example, a laser Doppler type particle size analyzer (manufactured by Nikkiso Co., Ltd., "Microtrac UPA150") Using the particle size measuring apparatus such _as, to be automatically measure D _{50, D 90} it can.

Said zinc phosphate particles, D ₅₀ is not limited particularly as long as 3μm or less. Further, it may be a mixture of particles satisfying D ₅₀ of 3 μm or less.

In the concentrated liquids (stock solutions) for preparing the first and second surface conditioners, the content of zinc phosphate particles is preferably 3% by mass lower limit and 60% by mass upper limit. When the surface is adjusted with the first and second surface conditioners obtained from the concentrated liquid, the amount of phosphate serving as a crystal nucleus is insufficient, and a sufficient surface adjustment effect is obtained. There is a risk of not. Further, since a large amount of concentrated liquid is required to maintain the necessary amount of zinc phosphate concentration in the surface conditioning bath, workability is poor and there is a possibility that it is not economical. If it exceeds 60% by mass, the dispersion stability of the zinc phosphate particles in the concentrated liquid for preparing the first and second surface conditioners may be lowered and may settle. The lower limit is more preferably 5% by mass, and the upper limit is more preferably 50% by mass.

The concentrated liquid for preparing the first and second surface conditioners preferably contains a divalent or trivalent metal nitrite compound. Surface adjustment is a treatment that is usually performed on a clean metal surface after degreasing and washing with water, so that problems such as oxidation and corrosion of the metal surface in the surface adjustment process may occur. When the metal nitrous acid compound is contained, generation of rust on the metal surface after the surface adjustment can be sufficiently suppressed. Moreover, as a result of suppressing generation | occurrence | production of rust, the chemical conversion property in chemical conversion treatment can also be improved significantly.

The divalent or trivalent metal nitrite compound is not particularly limited as long as it is a nitrite containing a divalent or trivalent metal. For example, zinc nitrite, copper nitrite, nickel nitrite, Examples thereof include alkaline earth metal nitrites such as magnesium nitrate, calcium nitrite, strontium nitrite and barium nitrite. Of these, zinc nitrite is preferable. When zinc nitrite is used for surface conditioning, the formation of a zinc phosphate conversion coating in the chemical conversion treatment process prevents foreign metals from accumulating in the chemical conversion treatment bath. Management becomes easy. Moreover, generation | occurrence | production of the rust of the metal surface after surface adjustment can also be suppressed more. These may be used alone or in combination of two or more.

The concentrated liquid (stock solution) for preparing the first and second surface conditioners preferably has a lower limit of 0.1% by mass and an upper limit of 10% by mass of the divalent or trivalent metal nitrite compound. . If it is less than 0.1% by mass, the rust prevention and metal substitution of the first and second surface conditioners obtained from the concentrated liquid may not be satisfactorily observed. When it exceeds 10 mass%, when a metal nitrite compound is used, the cation component in the metal nitrite compound may inhibit the dispersibility, and it may be not economical. The lower limit is more preferably 0.5% by mass, and the upper limit is more preferably 5% by mass.

The concentrated liquids for preparing the first and second surface conditioners can contain a dispersion medium for dispersing the zinc phosphate particles. Examples of the dispersion medium include an aqueous medium, and various organic solvents can be used as a medium other than water. According to the present invention, a dispersion containing no dispersion medium other than water can be obtained.

The water-soluble organic solvent is not particularly limited, for example, alcohol solvents such as methanol, isopropanol, ethylene glycol, ethylene glycol monopropyl ether, hydrocarbon solvents such as hexane, heptane, xylene, toluene, cyclohexane, naphtha, Ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, isophorone and acetophenone, amide solvents such as dimethylacetamide and methylpyrrolidone, ester solvents such as ethyl acetate, isobutyl acetate, octyl acetate, ethylene glycol monomethyl ether acetate and diethylene glycol monomethyl ether acetate Etc. These may be used alone or in combination of two or more.

In order to further improve the stability of the concentrated liquid for preparing the first and second surface conditioners, a thickener can be added as necessary.
The thickener is not particularly limited, for example, white clay, diatomaceous earth, calcium carbonate, barium sulfate, titanium oxide, alumina white, silica, aluminum hydroxide and other inorganic thickeners, polyacrylic acid ester, polyurethane, Organic thickeners such as polyester, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polysiloxane, thickening polysaccharides, phenol resins, epoxy resins, benzoguanamine resins, or thickeners composed of these polymers Can be mentioned. In addition, if it is a range which does not inhibit the effect of this invention, the said organic type thickener can also be added. These may be used alone or in combination of two or more.

In the concentrated liquids for preparing the first and second surface conditioners, soda ash is used for the purpose of further stabilizing zinc phosphate particles and forming a fine chemical conversion film in the subsequent phosphate film chemical conversion treatment step. Alkali salts such as may be added.

The concentrated liquid for preparing the first and second surface conditioners has a lower limit of 3 and an upper limit of 12. If the pH is less than 3, the zinc phosphate particles are likely to dissolve and become unstable, which may affect the next step. If it exceeds 12, the pH of the chemical bath in the next step may be lowered, and the influence of chemical conversion failure may be observed. The lower limit is preferably 6, and the upper limit is preferably 11.

The first and second surface conditioning agents of the present invention are used for surface conditioning, which is a pretreatment of phosphate film chemical conversion treatment, to attach fine particles of zinc phosphate to the metal surface. In the zinc acid chemical conversion treatment step, the formation of a zinc phosphate film having the fine particles as crystal nuclei is promoted to form a good zinc phosphate film. When the chemical conversion treatment is performed after the surface of the metal material is adjusted using this, fine phosphate crystals can be deposited in a relatively short time to cover the metal surface. For example, it can be obtained by diluting the above-mentioned concentrated liquids for preparing the first and second surface conditioners and adjusting them to a predetermined concentration.

The first surface modifier of the present invention contains the following zinc phosphate particles D ₅₀ of 3 [mu] m, and a layered clay mineral is of PH3～12. Therefore, the first surface conditioner is excellent in dispersion stability. The layered clay mineral contained in the first surface conditioner is the same as the layered clay mineral contained in the concentrated liquid for preparing the first surface conditioner.

The second surface conditioner of the present invention contains zinc phosphate particles having a D ₅₀ of 3 μm or less, and bentonite surface-treated with an alkyltrialkoxysilane represented by the above formula (I), and has a pH of 3 to 3. Twelve. Therefore, the second surface conditioner is excellent in dispersion stability. The surface-treated bentonite contained in the second surface conditioner is the same as the surface-treated bentonite contained in the concentrated liquid for preparing the second surface conditioner.

The zinc phosphate particles contained in the first and second surface conditioners are the same as the zinc phosphate particles contained in the concentrated liquid for preparing the first and second surface conditioners. The first and second surface conditioners are the same divalent or trivalent metal nitrous acid compounds, dispersants, dispersion media, and thickeners as the concentrated liquids for preparing the first and second surface conditioners. May be included.

In the first surface conditioner, the content of the layered clay mineral is preferably a lower limit of 3 ppm and an upper limit of 600 ppm. If it is less than 3 ppm, the effect of preventing the precipitation of zinc phosphate particles in the first surface conditioner may not be sufficiently obtained. If it exceeds 600 ppm, it may be adsorbed on the metal surface and the like, which may affect the subsequent chemical conversion step. The lower limit is more preferably 10 ppm, and the upper limit is more preferably 450 ppm.

In the second surface conditioner, the content of the surface-treated bentonite is preferably a lower limit of 3 ppm and an upper limit of 600 ppm. If it is less than 3 ppm, the effect of preventing precipitation of zinc phosphate particles in the second surface conditioner may not be sufficiently obtained. If it exceeds 600 ppm, it may be adsorbed on the metal surface and the like, which may affect the subsequent chemical conversion step. The lower limit is more preferably 10 ppm, and the upper limit is more preferably 450 ppm.

The first and second surface conditioners preferably have a zinc phosphate particle content of a lower limit of 50 ppm and an upper limit of 20000 ppm. If it is less than 50 ppm, there will be a shortage of phosphate as crystal nuclei, and a sufficient surface conditioning effect may not be obtained. Even if it exceeds 20000 ppm, the effect exceeding the desired effect is not obtained and it is not economical. The lower limit is more preferably 150 ppm, and the upper limit is more preferably 10,000 ppm.

In the first and second surface conditioners, the content of the divalent or trivalent metal nitrite compound is preferably 20 ppm as the lower limit and 1000 ppm as the upper limit. If it is less than 20 ppm, the rust prevention and metal substitution of the first and second surface conditioners may not be satisfactorily observed. There may be a shortage of phosphate serving as a crystal nucleus, and a sufficient surface conditioning effect may not be obtained. If it exceeds 1000 ppm, it is necessary to add a large amount of alkali components such as caustic soda in the first and second surface conditioners, which is not economical. The lower limit is more preferably 40 ppm, and the upper limit is more preferably 300 ppm.

The first and second surface conditioners have a lower limit of 3 and an upper limit of 12. If the pH is less than 3, the zinc phosphate particles are likely to dissolve and become unstable, which may affect the next step. If it exceeds 12, the pH of the chemical bath in the next step may be lowered, and the influence of chemical conversion failure may be observed. The lower limit is preferably 6, and the upper limit is preferably 11.

The concentrated liquid for preparing the first and second surface conditioners and the first and second surface conditioners of the present invention can be produced, for example, by the following method.
The zinc phosphate particles can be obtained using, for example, zinc phosphate used as a raw material. The raw material zinc phosphate is represented by Zn ₃ (PO ₄ ) ₂ .4H ₂ O, and is generally a colorless and crystalline solid, but is commercially available in a white powder state. .

As a method for producing the raw material zinc phosphate, for example, when a dilute solution of zinc sulfate and disodium hydrogen phosphate is mixed and heated at a molar ratio of 3: 2, the tetraphosphate of zinc phosphate becomes a crystalline precipitate. Generate as Alternatively, zinc phosphate tetrahydrate can be obtained by reacting a diluted phosphoric acid aqueous solution with zinc oxide or zinc carbonate. Tetrahydrate crystals are orthorhombic and have three transformations. When heated, it becomes a dihydrate at 100 ° C, a monohydrate at 190 ° C, and an anhydrate at 250 ° C. As the zinc phosphate in the present invention, any of these tetrahydrates, dihydrates, monohydrates, and anhydrous hydrates can be used, but generally available tetrahydrates can be used as they are.

Moreover, as the raw material zinc phosphate, those subjected to various surface treatments may be used. For example, it may be surface-treated with a silane coupling agent, rosin, silicone compound, metal alkoxide such as silicon alkoxide or aluminum alkoxide.

When zinc compound and phosphoric acid are reacted, finely divided zinc phosphate can be obtained by adding silica and polyphosphoric acid (JP-B-49-2005, etc.), and zinc phosphate can be combined with various metal compounds. A part of zinc in zinc phosphate can be replaced with metal such as magnesium, calcium, aluminum, etc. by wet-kneading by mechanical means and completing the reaction mechanochemically (JP-A-4-310511 / JP, etc.) Are known, for example, those in which components other than phosphorus, oxygen, and zinc such as silica, calcium, and aluminum are introduced by such means, and those that are commercially available as silicic acid-modified zinc phosphate Also good. In this case, it is preferable that zinc phosphate is contained in an amount of 25% by mass or more in terms of ZnO and 15% by mass or more in terms of P ₂ O ₅ .

It does not specifically limit as a shape of the said raw material zinc phosphate, The thing of arbitrary shapes can be used. Commercially available products are generally in the form of white powder, but the shape of the powder may be any shape such as fine particles, plates, scales, and the like. The particle size of the raw material zinc phosphate is not particularly limited, but is usually a powder having an average particle size of about several μm. In particular, products that are commercially available as rust preventive pigments, such as products that have a buffering effect enhanced by treatment for imparting basicity, are preferably used. As will be described later, in the present invention, since a stable dispersion liquid in which zinc phosphate particles are finely dispersed can be prepared, the stable surface is not affected by the primary particle size or shape as the raw material zinc phosphate. A processing effect can be obtained.

It is preferable to use the raw material zinc phosphate finely dispersed by preparing it in advance as a dispersion. The preparation method of the aqueous dispersion in which zinc phosphate particles are dispersed in an aqueous medium is not limited, but preferably, the raw material zinc phosphate is blended in the above-described dispersion medium such as water or an organic solvent, and the above-described layered structure is obtained. This can be achieved by performing wet grinding in the presence of clay mineral and surface-treated bentonite. In obtaining the aqueous dispersion of the zinc phosphate particles, it is convenient in the process to wet pulverize by mixing the raw material zinc phosphate in an aqueous medium at the time of preparation of the dispersion. You may prepare by performing solvent substitution after performing in dispersion media other than a medium.

In the preparation of the aqueous dispersion, the blending amount of the raw material zinc phosphate is preferably within a range of 100% by mass of the dispersion, usually a lower limit of 0.5% by mass and an upper limit of 50% by mass. If it is less than 0.5% by mass, the content of zinc phosphate is too small, and the effects of the first and second surface conditioners obtained using the dispersion may not be sufficiently obtained. If it exceeds 50% by mass, it may be difficult to obtain a uniform and fine particle size distribution by wet grinding, and it may be difficult to form a finely dispersed state. The lower limit is more preferably 1% by mass, and the upper limit is more preferably 40% by mass.

In addition, in the preparation of the aqueous dispersion, the amount of the layered clay mineral or the surface-treated bentonite is preferably 0.1% by mass in the lower limit and 30% by mass in the upper limit in 100% by mass of the dispersion. If it is less than 0.1% by mass, the dispersibility may not be sufficient. If it exceeds 30% by mass, dispersibility may deteriorate due to the interaction between surplus layered clay minerals or surface-treated bentonites, and even if the dispersion is sufficient, it is not economically advantageous. The lower limit is more preferably 0.5% by mass, and the upper limit is more preferably 20% by mass.

Method for obtaining a dispersion prepared by dispersing finely the D ₅₀ to 3μm below the zinc phosphate particles is not limited, preferably, a 0.5 to 50 wt% of zinc phosphate of the raw material in a dispersion medium, the layered clay mineral Alternatively, the surface-treated bentonite is present in an amount of 0.1 to 30% by mass and wet pulverized. The wet pulverization method is not particularly limited, and a general wet pulverization means may be used. For example, a bead mill represented by a disk type, a pin type, etc., a high pressure homogenizer, an ultrasonic disperser, etc. A medialess disperser or the like can be used.

In the wet pulverization, by monitoring the D ₉₀ of the zinc phosphate particles, the phenomenon of overdispersion can be prevented, and the phenomenon of aggregation, thickening, and aggregation of fine particles can be prevented. In the present invention, it is preferable to be 4μm or less D _90. In addition, it is desirable to select blending and dispersion conditions that do not cause overdispersion.

By the above-described dispersion preparation method, D ₅₀ of zinc phosphate in an aqueous medium can be adjusted to 3 μm or less, and it has excellent stability and excellent performance as a first and second surface conditioner. An aqueous dispersion can be obtained. D ₅₀ can be adjusted normally to the desired degree in the range of 0.01 to 3 [mu] m.

By preparing an aqueous dispersion by the method for preparing a dispersion described above, even a zinc phosphate exceeding 3 μm can be dispersed in the liquid with a D ₅₀ of 3 μm or less. The same applies to zinc phosphate having a primary particle size of several tens of μm. This also means that the primary particle diameter of the pigment can be reduced by wet pulverization according to the above-described method without using zinc phosphate having a small primary particle diameter. According to the above-described method, the D ₅₀ of the zinc phosphate particles in the aqueous dispersion can be 3 μm or less, further 1 μm or less, and further 0.2 μm or less.

Dispersion obtained as described above can be adjusted to match the D ₅₀ of zinc phosphate particles in a liquid for use with 3μm or less, excellent dispersion stability, first with this, the When the second surface conditioner is prepared, it is an aqueous dispersion capable of exhibiting excellent performance.

Since the ratio of coarse particles shown as particles having a particle size exceeding D ₉₀ can be reduced by the above-mentioned wet pulverization method, D ₉₀ is 4 μm or less, more preferably 2.6 μm or less, and still more preferably 0.8 as the distribution of dispersion diameter. A dispersion having a large dispersion diameter of 3 μm or less and a sharp dispersion with a suppressed dispersion diameter can be obtained. For this reason, it is estimated that zinc phosphate is dispersed with a fine dispersion diameter and the dispersion state is extremely stable. In addition, since the proportion of coarse particles is low, zinc phosphate in the liquid efficiently contributes to the formation of crystal nuclei, and since the distribution of the dispersed diameter is sharp and the particle size is uniform, the surface conditioning treatment step In this case, more uniform crystal nuclei are formed, and the subsequent chemical conversion treatment leads to the formation of uniform zinc phosphate crystals, and the surface properties of the resulting chemical conversion-treated steel sheet become uniform and excellent. It is estimated that the processability with respect to the hardened steel plate such as the bag portion of the member having a simple structure or the black leather plate is improved.

The D ₅₀ and D ₉₀ of zinc phosphate in the dispersion can be determined by measuring the particle size distribution using a laser Doppler particle size analyzer.
In particular, the aqueous dispersion can also obtain a high-concentration aqueous dispersion in which zinc phosphate is blended in an amount of 10 mass% or more, further 20 mass% or more, and further 30 mass% or more. For this reason, the 1st, 2nd surface conditioning agent which exhibits high performance can be prepared easily.

The concentrated liquid for preparing the first and second surface conditioners of the present invention, and the first and second surface conditioners are, for example, the aqueous dispersion obtained as described above and other components (layered). And clay mineral, divalent or trivalent metal nitrite compound, dispersion medium, thickener and the like). The mixing method of the aqueous dispersion and the other components is not particularly limited. For example, other components may be added to the aqueous dispersion and mixed, or other components may be mixed during the preparation of the aqueous dispersion. You may mix | blend.

The surface conditioning method of the present invention comprises a step of bringing the surface conditioning agent (first surface conditioning agent, second surface conditioning agent) into contact with the metal surface. Thereby, the fine particle of zinc phosphate can be made to adhere favorably to metal surfaces, such as iron, zinc, and an aluminum type, and a good chemical conversion film can be formed in a chemical conversion treatment process.

The method of bringing the first and second surface conditioning agents into contact with the metal surface in the surface conditioning method is not particularly limited, and a conventionally known method such as dipping or spraying can be appropriately employed.

It does not specifically limit as a metal material to which the said surface adjustment is performed, Generally, it can apply to the various materials which perform a phosphate chemical conversion treatment, for example, steel, a galvanized steel plate, aluminum or an aluminum alloy, a magnesium alloy etc.

Moreover, it can use for a degreasing | defatting and surface conditioning process using the 1st, 2nd surface conditioning agent of this invention. Thereby, the water washing process after a degreasing process can be skipped. In the degreasing and surface conditioning step, a known inorganic alkali builder, organic builder, surfactant and the like may be added in order to increase the detergency. Moreover, you may add a well-known chelating agent, condensed phosphate, etc. In the said surface adjustment, the contact time of a 1st, 2nd surface conditioning agent and a metal surface and the temperature of a 1st, 2nd surface conditioning agent are not specifically limited, It can carry out on conventionally well-known conditions.

The above surface adjustment is performed, and then a phosphate chemical conversion treatment steel sheet can be manufactured by performing a phosphate chemical conversion treatment.
The phosphate chemical conversion treatment method is not particularly limited, and various known methods such as immersion (dip) treatment, spray treatment, and electrolytic treatment can be applied. A plurality of these may be combined. The phosphate film to be deposited is not particularly limited as long as it is a phosphate, and is not limited at all, such as zinc phosphate, iron phosphate, manganese phosphate, and zinc calcium phosphate. In the phosphate chemical conversion treatment, the contact time between the chemical conversion treatment agent and the metal surface and the temperature of the chemical conversion treatment agent are not particularly limited, and can be performed under conventionally known conditions.

After performing the surface adjustment and the chemical conversion treatment, a coated steel sheet can be produced by further coating. The coating method is generally electrodeposition coating. The paint used for the coating is not particularly limited, and various types generally used for coating the phosphate chemical conversion steel sheet, for example, epoxy melamine paint, cationic electrodeposition paint, polyester-based intermediate coating, and polyester-based top coating Can do. In addition, after a chemical conversion treatment, the well-known method of performing a washing | cleaning process before a coating is employ | adopted.

First concentrates surface modifier for the preparation of the present invention are those of pH3~12 the D ₅₀ contains zinc phosphate particles and the layered clay mineral is 3μm or less. The second concentrates surface modifier for the preparation of the present invention are those of pH3~12 containing bentonite D ₅₀ is obtained by zinc phosphate particles and surface treatment is 3μm or less. Therefore, not only the dispersion stability in the first and second surface conditioning agents obtained by diluting the concentrated solution for preparing the first and second surface conditioning agents, but also in the concentrated solution (stock solution). It also has excellent dispersion stability. Moreover, the zinc phosphate particles can be further refined, and the dispersion efficiency can be further improved. Since it contains zinc phosphate particles having a D ₅₀ of 3 μm or less, the dispersion stability in the bath is also excellent. Therefore, the first and second surface conditioners obtained by diluting the concentrated liquid for preparing the first and second surface conditioners can be suitably used for various metal materials. It is.

Since the concentrated liquid for preparing the first and second surface conditioning agents of the present invention has the above-described configuration, the first liquid obtained by diluting the concentrated liquid for preparing the first and second surface conditioning agents. In addition to the dispersion stability in the second surface conditioner, the dispersion stability in the concentrated liquid (stock solution) is also excellent. Therefore, the first and second surface conditioners obtained from the concentrated liquid can be suitably used for various metal materials.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail, this invention is not limited only to these Examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

Example 1 Manufacture of concentrated liquid (stock solution) and surface conditioner for preparation of surface conditioner To 86 parts by mass of water, 2 parts by mass of natural hectorite "BENTON EW" (manufactured by ELEMENTIS) was added, and disperser was added. Was stirred at 3000 rpm for 30 minutes to obtain a pregel. To the obtained pregel, 2 parts by mass of a dispersant and 10 parts by mass of zinc phosphate particles were added and dispersed to a predetermined viscosity with zirconia beads to obtain a concentrated liquid for preparing a surface conditioner (concentration of zinc phosphate particles). 10 mass%, natural hectorite concentration 2 mass%).

Furthermore, the obtained concentrated liquid was diluted with water and the pH was adjusted to 9.5 with caustic soda to obtain a surface conditioner (zinc phosphate particle concentration 1500 ppm, natural hectorite concentration 300 ppm).

Example 2 Preparation of a surface conditioner In the same manner as in Example 1 except that the addition amount of the concentrated solution (stock solution) for preparing the surface conditioner and the production of the surface conditioner “BENTON EW” was changed to 1 part by mass. A concentrated liquid was obtained (zinc phosphate particle concentration 10% by mass, natural hectorite concentration 1% by mass). Further, a surface conditioner was obtained (zinc phosphate particle concentration 1500 ppm, natural hectorite concentration 150 ppm).

Example 3 Manufacture of concentrated liquid (stock solution) for surface conditioner preparation and surface conditioner “BENTON EW” 3 parts by mass of synthetic hectorite “Laponite RD” ( manufactured by Sakai Kogyo Co., Ltd.) was used instead of 2 parts by mass. Except for the above, a concentrated solution for preparing the surface conditioning agent was obtained in the same manner as in Example 1 (zinc phosphate particle concentration 10% by mass, synthetic hectorite concentration 3% by mass). A surface conditioner was also obtained (zinc phosphate particle concentration 1500 ppm, synthetic hectorite concentration 450 ppm).

Reference Example: Concentrated liquid for preparing surface conditioner (stock solution) and production of surface conditioner “BENTON EW” instead of 2 parts by mass Alkoxyalkoxysilane-modified bentonite “Bengel-SH” (manufactured by Hojun Co.) 3 parts by mass Except that, a concentrated liquid for preparing a surface conditioning agent was obtained in the same manner as in Example 1 (zinc phosphate particle concentration: 10 mass%, alkylalkoxysilane-modified bentonite concentration: 3 mass%). Further, a surface conditioner was obtained (zinc phosphate particle concentration 1500 ppm, alkylalkoxysilane-modified bentonite concentration 450 ppm).

Comparative Example 1 A concentrated liquid for preparing a surface conditioner was obtained in the same manner as in Example 1 except that the concentrated liquid (stock solution) for preparing the surface conditioner and the production of the surface conditioner “BENTON EW” were not added ( Zinc phosphate particle concentration 10 mass%). In addition, a surface conditioner was obtained (zinc phosphate particle concentration 1500 ppm).

Comparative Example 2 Preparation of surface conditioning agent (stock solution) and production of surface conditioning agent “BENTON EW” Instead of 2 parts by mass, Example 1 was used except that 0.5 part by mass of carboxymethylcellulose (CMC) was used. In the same manner, a concentrated solution for preparing the surface conditioner was obtained (zinc phosphate particle concentration 10% by mass, CMC concentration 0.5% by mass). Further, a surface conditioner was obtained (zinc phosphate particle concentration 1500 ppm, CMC concentration 75 ppm).

Comparative Example 3 Preparation of surface conditioner concentrate (stock solution) and surface conditioner "BENTON EW" Instead of 2 parts by mass, the same surface as in Example 1 except that 2 parts by mass of polyacrylic acid was used. A concentrated liquid for preparing a regulator was obtained (zinc phosphate particle concentration 10% by mass, polyacrylic acid concentration 2% by mass). Further, a surface conditioner was obtained (zinc phosphate particle concentration 1500 ppm, polyacrylic acid concentration 300 ppm).

Comparative Example 4 Preparation of surface conditioner concentrate (stock solution) and production of surface conditioner “BENTON EW” 2 parts by mass, except that 3 parts by mass of silica “AEROSIL # 300” (manufactured by Aerosil Japan) was used Obtained a concentrated solution for preparing the surface conditioning agent in the same manner as in Example 1 (zinc phosphate particle concentration: 10 mass%, silica concentration: 3 mass%). Further, a surface conditioner was obtained (zinc phosphate particle concentration 1500 ppm, silica concentration 450 ppm).

〔Evaluation test〕
Evaluation was performed by the following method, and the results are shown in Table 1.

Stability of concentrated liquid for preparing surface conditioner (stock solution) The concentrated liquids for preparing surface conditioner obtained in Examples and Comparative Examples were respectively (1) left at room temperature in the room, (2 The sample was allowed to stand in a refrigerator at 5 ° C. and (3) in a furan vessel at 40 ° C., and the stability after 3 months was visually confirmed according to the following criteria.
○: Uniform appearance.
Δ: Some supernatant liquid is confirmed.
X: Completely divided into two layers. It is sinking. Corrupt.

Stability of surface conditioner (bath stability during surface adjustment)
Ca (NO ₃ ) ₂ .4H ₂ O and Mg (NO ₃ ) ₂ .6H ₂ O were used as Ca and Mg (metal), respectively, in the diluted solutions of the surface conditioning agents obtained in the examples and comparative examples. This was added to 20 ppm and allowed to stand, and then set in a thermostatic bath at 50 ° C., and the stability over time test was performed. Evaluation was made according to the following criteria.
A: Good dispersion state.
X: Zinc phosphate particles are aggregated. Corrupt.

Perform a particle size distribution measured using a measuring beam diffraction type particle size measuring device of the particle size of the zinc phosphate particles ( "LA-500", manufactured by Horiba Ltd.), monitoring and D _{90 (average} diameter of the dispersion) D ₅₀ D ₅₀ and D ₉₀ were measured.

When the surface conditioner of an Example was used, it was excellent in stability of both the concentrated liquid for surface conditioner preparation, and a surface conditioner. In addition, the surface conditioner of the example had a fine particle size (D ₅₀ ) of the zinc phosphate particles as compared with that of Comparative Example 2.

The surface conditioner of the present invention can be suitably used for various metal materials used in automobile bodies, home appliances and the like.

It is a schematic diagram of an alkyltrialkoxysilane-modified bentonite having a patchwork structure.

Claims (2)

A concentrated liquid for preparing a pH 3-12 surface conditioner containing zinc phosphate particles,
The zinc phosphate particles _is a _{D 50} of 3μm or less,
The content of the zinc phosphate particles is 3% by mass or more and 60% by mass or less,
The concentrated liquid for preparing the surface conditioner contains a layered clay mineral of 0.1% by mass or more and 20% by mass or less ,
The layered clay mineral is natural hectorite and / or synthetic hectorite, a concentrated liquid for preparing a surface conditioner. D ₅₀ contains the following zinc phosphate particles 3 [mu] m 3 wt% to 60 wt% or less, a process for the preparation of a concentrated solution of surface conditioner preparation of PH3～12,
Dispersion medium, viewed including the step of wet-pulverizing the zinc phosphate in the presence of the layered clay mineral,
The layered clay mineral is natural hectorite and / or synthetic hectorite .

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