DESCRIPTION
TITLE OF THE INVENTION
PRIMER-TREATING AGENT FOR PRECOATED METAL SHEET, PRIMER-TREATED METAL SHEET COATED THEREWITH, AND PRECOATED METAL SHEET USING THE SAME EXCELLENT IN COATING FILM ADHESION AFTER STAMPING
TECHNICAL FIELD [0001]
The present invention relates to a primer-treating agent for precoated metal sheets not containing potentially toxic chromium, a coated metal sheet which has been coated with the primer-treating agent, and a precoated metal sheet which has been obtained by using the primer-treating agent, and is excellent in the coating film adhesion after the blanking and stamping of the precoated metal sheet.
BACKGROUND ART [0002]
Specifically in the industrial fields of household electric appliances, building materials, automobiles and the like, there has been spreading a technique of manufacturing such a product without using a coating step, but only by stamping a precoated metal sheet, which has preliminarily been coated with a colored organic coating film, in place of the conventional post-coated products which have been coated after the stamping thereof. Precoated metal sheets are primer-treated metal sheets and plated metal sheets, which have been coated with an organic coating film, and have characteristics such that they have stampability and good corrosion resistance, in addition to good appearance thereof. For example. Patent Document 1 discloses a technique of defining the specific structure of a coating film, to thereby obtain a precoated steel sheet which is excellent

- 2 -
in stampability, staining resistance and hardness. Patent Document 2 discloses a precoated steel sheet which uses a specific chromate treating liquid, to thereby improve the edge face-corrosion resistance thereof. [0003]
Due to the combined effect of the chromate treatment and organic coating, these precoated steel sheets have stampability and coating adhesion, in addition to the corrosion resistance, and have an intention of attaining an enhanced productivity and an improved quality, by omitting the coating step to be conducted after the stamping thereof. However, in view of the toxicity problem of hexavalent chromium, which can be eluted from the organic films containing the chromate-coated films and chromium-based antirust pigments, there have been increased the demands for chromium-free antirust treatment and chromium-free organic coating films. As the non-chromium based antirust treatment in stead of the chromate treatment. Patent Document 3 discloses a treatment technique which employs an aqueous solution containing thiourea and tannin or tannic acid. However, when a precoated metal sheet is produced by using this antirust treatment method, the resultant product has a problem that the adhesion of the coating film at the processed portion of the precoated metal sheet is considerably deteriorated, when it is applied to household electric appliances and automobiles, wherein the precoated metal sheet is subjected to a stamping step for providing a severe shape of the precoated metal sheet after the stamping. Patent Document 4 discloses a method of enhancing white rust resistance and coating adhesion, by using a surface treatment with an aqueous solution containing tannic acid and a silane coupling agent, but this method cannot secure the coating film adhesion after the stamping, which is required for the precoated metal sheets. [0004]

- 3 -
Patent Document 5 discloses a primer-treating agent for precoated metal sheets, which simultaneously contains tannin or tannic acid, a silane coupling agent and fine particulate silica. The primer-treating agent is put to practical use as an agent satisfying the coating film adhesion after stamping. This patent document also describes a treating agent containing a polyester resin component, in addition to the above essential components, and also discloses that the addition of the polyester resin contributes to an enhanced coating film adhesion of the precoated metal sheet after stamping thereof.
PRIOR ART DOCUMENTS
PATENT DOCUMENT
[0005]
[Patent Document 1] JP-A (Japanese Unexamined Patent
Publication; KOKAI) No. 8-168723
[Patent Document 2] JP-A No. 3-100180
[Patent Document 3] JP-A No. 53-9238
[Patent Document 4] JP-A No. 59-116381
[Patent Document 5] JP-A No. 2001-89868
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0006]
In order to enhance the coating film adhesion after stamping of a precoated metal sheet, the present inventors put in an actual operation a treating agent containing a polyester resin, in addition to the essential components (tannin or tannic acid, a silane coupling agent and fine particulate silica) described in Patent Document 5 for producing a precoated metal sheet, and encountered a problem such that a precipitate was formed during the treatment in a long-term use thereof in a steady state.
[0007]
When the precipitate is formed in the treating agent

- 4 -
in a steady state, various operational problems are caused. At first, the precipitate which has been deposited in the coating pan is picked up together with the treating agent by a roll coater, and is applied onto a metal sheet, or a treating agent contaminated with the precipitate is applied onto the metal sheet by spraying, a solid is attached to the metal sheet as a foreign substance, to thereby spoil the appearance of the metal sheet (i.e., the commercial value thereof is markedly decreased). In addition, a sticky precipitate may be attached to the surface of the roll coater, to thereby cause clogging of the sprayer, and in this case, it becomes necessary to frequently exchange the roller or provide the maintenance of the sprayer, whereby the productivity is markedly decreased. Further, when the production of the precipitate is noticeable, the ratio of the constituents in the "supernatant" solution (i.e., the actual treating agent) may be greatly deviated from the appropriate ratio thereof, to thereby create a situation in which the treating agent cannot exhibit its proper performance anymore. [0008]
An object of the present invention is to provide a primer-treating agent for a precoated metal sheet which can solve the above problem encountered in the prior art.
Another object of the present invention is to provide a stable primer-treating agent for a precoated metal sheet such that no precipitate is formed in the practical long-term operation for producing a precoated metal sheet in a steady state, even if the agent contains a polyester resin which contributes to an enhanced coating film adhesion of a precoated metal sheet after stamping, in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica.
A further object of the present invention is to provide a coated metal sheet which has been coated with such a treating agent, and a precoated metal sheet using

- 5 -
such a sheet, which has an excellent coating film adhesion after stamping of the precoated metal sheet.
MEANS FOR SOLVING THE PROBLEM
[0009]
As a result of earnest study, the present inventors have found that it is extremely effective in solving the above problem to constitute a treating agent by combining a specific solid and a polyester resin having a specific particle size, a specific glass transition temperature
(Tg) and a specific hydroxyl value in water, and further to set a specific pH range as the treating agent.
[0010]
The present invention is based on the above discovery, and more specifically, a primer-treating agent for a precoated metal sheet, comprising each in terms of a solid content in water: a polyester resin having a particle size of 50 to 150 nm, a glass transition
temperature (Tg) of 0 to 30°C and a hydroxyl value of 5 to 13, in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica; wherein the pH value as the treating agent is 2.0 to 6.5. [0011]
According to the knowledge and investigation of present inventors, the reason for the provision of the above excellent effect in the present invention may be presumed in the following manner. [0012]
More specifically, as stated above, the present inventors put in an actual operation a treating agent containing a polyester resin for contributing to an enhanced coating film adhesion after stamping of the precoated metal sheet, in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica described in Patent Document 5 for the purpose of producing a precoated metal sheet, and encountered a problem such that a precipitate was formed during the

- 6 -
treatment in a long-term use thereof in a steady state. Based on the discovery of such a phenomenon, and as a result of earnest study and investigations, the present inventors have made the following findings. [0013]
When a primer-treating agent is used in a continuous line in the manufacture of a precoated metal sheet, it is a common practice to circulate the treating agent and apply the agent onto a metal sheet by using a roll coater or a sprayer. The treating agent of the prior art as described above (Patent Document 5) is acidic at a pH of about 4. Accordingly, when the treating agent is applied onto a galvanized steel sheet, zinc, for example, may be eluted little by little from the surface of the galvanized metal sheet during the long-term operation, to thereby increase the zinc concentration in the circulating treating agent. In addition, the metal sheet is ordinarily subjected to the steps of degreasing, washing with water and drying with hot air, and immediately thereafter, to the step of applying the primer-treating agent. Accordingly, the temperature of the metal sheet at the time of the entry into the application step is usually high, and the temperature of the treating agent solution is gradually increased. The treating agent is applied onto the metal sheet so as to be consumed at a constant rate, and a fresh treating agent is supplied into the circulation system at an amount which is commensurate with the consumption of the treating agent. When these are balanced, the level of the metal contamination and the temperature of the metal in the treating agent become steady. Also depending on the condition of operation, the temperature at the steady state is generally at a maximum of 40°C, and the level of metal contamination (in the case of zinc) is generally at a maximum of 100 ppm. Based on the above findings, the present inventors have found that, in order to avoid the precipitate formation at the time of using the treating

- 7 -
agent containing a polyester resin, it is extremely important that no precipitation is formed and the treating agent is stable at the level of the metal contamination and at an increased temperature of the degree which is almost equal to those of the steady state mentioned above. [0014]
In addition, during the long-time operation as described above, zinc is dissolved into the treating agent in the form of ions. Hydrogen ions in the treating agent are consumed along with the ionization of zinc, pH of the treating agent tends to be increased gradually together with the increase in the zinc ion concentration. If the pH value exceeds a predetermined value, precipitate may be formed as described hereinafter, which is one of the causes which badly affects the stable operation. Therefore, it is required that pH of the treating agent does not easily vary. Thus, the present inventors have also found that, in order to avoid the precipitate formation while using a polyester resin-containing treating agent, it is important that the pH variation is sufficiently small at the level of metal contamination which is almost equal to that of the steady state as described above. [0015]
The present inventors have assumed that, as the temperature becomes higher in the presence of metal contamination, a component constituting the treating agent such as silane coupling agent and tannic acid, having a coordinating ability may react with metal ions which have been eluted from the metal sheet, and is less liable to remain stably in the treating agent, whereby they may be precipitated together with the polyester resin. However, along with the progress in the research, the present inventors have found that there is a difference in the easiness of the precipitate formation depending on the type of the polyester resin.

- 8 -
[0016]
With respect to the cause for such a difference in the easiness of the precipitate formation depending on the type of the polyester resin, the present inventors assume in the following manner, on the mechanism of the precipitate formation in the treating agent, based on the combination of various findings described above. [0017]
The silane coupling agent and tannic acid are highly reactive compounds, and accordingly, a portion of these compounds may cause a reaction in the treating agent, to thereby form a poorly soluble reaction product, which associates with one another to form an aggregate and then is precipitated. When Zn ions are present in the treating agent, the Zn ions may react with the above reaction product, so as to further promote the reduction in the electric charge of the reaction product, to thereby further reduce the solubility and promote the formation of the precipitate. When a specific polyester resin is present in this system, however, this reaction product is adsorbed to the hydrophobic portion of the polyester resin emulsion due to the hydrophobic interaction, and prevents the reaction products from associating and aggregating with one another, to thereby suppress the precipitate formation. The present inventors assume that the degree of suppressing the precipitate formation by the polyester resin depends on the affinity of the reaction product with the polyester resin (i.e., the easiness of the adsorption due to the hydrophobic interaction), and on the stability of the polyester resin emulsion in the liquid phase. In other words, it may be presumed that, based on such a mechanism, the primer-treating agent for a precoated metal sheet according to the present invention exhibits its excellent effect as described above. [0018]
As a result of further repetition of verification

- 9 -
experiments based on the various discoveries described above by the present inventors, the present inventors have discovered that the polyester resin may preferably have a particle size of 50 to 150 nm, a glass transition temperature (Tg) of 0 to 30°C and a hydroxyl value of 5 to 13, and pH as the treating agent may preferably be 2.0 to 6.5. Based on such a discovery, the primer-treating agent for a precoated metal sheet according to the present invention having the composition as described above has been accomplished. [0019]
The present invention for example can include the following embodiments.
[1] A primer-treating agent for a precoated metal sheet, comprising each in terms of a solid content in water: a polyester resin having a particle size of 50 to 150 nm, a glass transition temperature (Tg) of 0 to 30°C and a hydroxyl value of 5 to 13, in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica;
wherein the pH value as the treating agent is 2.0 to 6.5. [0020]
[2] The primer-treating agent for a precoated metal sheet according to [1], wherein the agent simultaneously satisfies TA:SC=1:40 to 40:1, (TA+SC):SI=1:10 to 20:1 and (TA+SC):PR=1:10 to 10:1, and the concentration (TA+SC+SI+PR) of the total of the components thereof is 10 to 200 g/L], wherein the mass concentration of tannin or tannic acid is represented by TA, that of the silane coupling agent is represented by SC, that of fine particulate silica is represented by SI and that of the polyester resin is represented by PR.
[3] The primer-treating agent for a precoated metal sheet according to [1] or [2], wherein the silane coupling agent has a glycidyl ether group.
[4] The primer-treating agent for a precoated metal

- 10 -
sheet according to any one of [1] to [3], wherein no precipitate is formed when the agent was contaminated with 100 ppm of zinc ions. [0021]
[5] The primer-treating agent for a precoated metal sheet according to any one of [1] to [4], wherein the upward fluctuation in pH is 1.5 or less, when the agent was contaminated with 100 ppm of zinc ions.
[6] A coated metal sheet, wherein the primer-treating agent for a precoated metal sheet according to [1] to [5] has been applied onto the surface of at least one side of a metal sheet and then dried.
[7] A coated metal sheet according to [6], wherein the amount of the primer-treating agent for a precoated metal sheet according to any one of [1] to [5] attached to the metal sheet is 10 to 500 mg/m^ in terms of a solid content. [0022]
[8] A precoated metal sheet, comprising: the coated metal sheet according to [6] or [7], and an upper coating film disposed thereon.
[9] A precoated metal sheet, comprising: the coated metal sheet according to [6] or [7], a lower coating film disposed thereon containing an antirust pigment, and an upper coating film disposed on the lower coating film.
EFFECTS OF THE INVENTION [0023]
According to the present invention, by containing a polyester resin having a particle size of 50 to 150 nm, a Tg of 0 to 30°C and a hydroxyl value of 5 to 13, in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica, there can be provided a stable primer-treating agent for a precoated metal sheet in which no precipitate is formed in the practical long-term operation for producing a precoated metal sheet in a steady state.

- 11 -
[0024]
The primer-treating agent for a precoated metal sheet according to the present invention allows to provide a precoated metal sheet having a primer-treated coating film with a performance which is comparable to the precoated metal sheet which has been primer treated with chromate, by using a combination of tannin or tannic acid, a silane coupling agent and fine particulate silica, and also allows to produce a long-term stable precoated metal sheet by using a specific polyester resin as described above in combination.
MODES FOR CARRYING OUT THE INVENTION [0025]
The primer-treating agent for a precoated metal sheet according to the present invention comprises: as solid in water, a polyester resin having a particle size of 50 to 150 nm, a glass transition temperature (Tg) of 0
to 30°C and a hydroxyl value of 5 to 13, in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica, and has a pH as the treating agent of 2.0 to 6.5. [0026]
The tannin or tannic acid, a silane coupling agent and fine particulate silica to be used in the primer-treating agent for a precoated metal sheet according to the present invention may be any of those which have heretofore been used ordinarily in the field of a primer-treating agent for a precoated metal sheet. [0027]
Tannin or tannic acid may also be a hydrolyzable tannin, a condensed tannin, or a partially decomposed product thereof. Tannin or tannic acid may be, but not limited to, Hamamelitannin, sumac tannin, gallic tannin, myrobalan tannin, divi-divi tannin, algarrobilla tannin, valonia tannin, catechin, etc. From the viewpoint of enhancing the coating film adhesion after stamping.

- 12 -
"Tannic acid: AL" (mfd. by Fuji Chemical Industry Co., Ltd.) may preferably be used.
[0028]
Specific examples of the coupling agents, may include, for example:
y-(2-aminoethyl)aminopropyltrimethoxysilane, y-(2-aminoethyl)aminopropylmethyldimethoxysilane, y-(2-aminoethyl)aminopropyltriethoxysilane, y-(2-aminoethyl)aminopropylmethyldiethoxysilane, y-(2-aminoethyl)aminopropylmethyldimethoxysilane, y-methacryloxypropyltrimethoxysilane, y-methacryloxypropylmethyldimethoxysilane , y-methacryloxypropyltriethoxysilane, y-methacryloxypropylmethyldiethoxysilane, N-p-(N-vinylbenzylaminoethyl) -y-aminopropyltrimethoxysilane, N-p-
(N-vinylbenzylaminoethyl)-y-aminopropylmethyldimethoxysilane, N-p-(N-vinylbenzylaminoethyl)-y-aminopropyltriethoxysilane, N-p-
(N-vinylbenzylaminoethyl)-y-aminopropylmethyldiethoxysilane, y-glycidoxypropyltrimethoxysilane, y-glycidoxypropylmethyldimethoxysilane, y-glycidoxypropyltriethoxysilane, y-glycidoxypropylmethyldiethoxysilane, y-mercaptopropyltrimethoxysilane, y-mercaptopropylmethyldimethoxysilane, y-mercaptopropyltriethoxysilane, y-mercaptopropymethyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, vinyltriacetoxysilane, y-chloropropyltrimethoxysilane, y-chloropropylmethyldimethoxysilane, y-chloropropyltriethoxysilane, y-

- 13 -
chloropropylmethyldiethoxysilane, hexamethyldisilazane, y-anilinopropyltrimethoxysilane, y-anilinopropylmethyldimethoxysilane, y-anilinopropyltriethoxysilane, y-
anilinopropylmethyldiethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride,
octadecyldimethyl[3-(methyldimethoxysilyl)propyl]ammonium chloride, octadecyldimethyl[3-(triethoxysilyl)propyl]ammonium chloride,
octadecyldimethyl[3-(methyldiethoxysilyl)propyl]ammonium chloride, y-chloropropylmethyldimethoxysilane, y-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane and the like. When a silane coupling agent having a glycidylether group, such as y-glycidoxypropyltrimethoxysilane and y-
glycidoxypropyltriethoxysilane having a glycidyl ether group, is used, the coating film adhesion after stamping can particularly be improved. Further, when a silane coupling agent of the triethoxy type is used, the storage stability of the primer-treating agent can be enhanced. This is probably because triethoxysilane is relatively stable in an aqueous solution and its polymerization rate is slow. [0029]
The mass concentration ratio of tannin or tannic acid to a silane coupling agent in the treating agent may preferably be 1:40 to 40:1. If the ratio is outside of this range, whether each of these components is greater or not, the effect of the coating film adhesion after stamping and rust resistance of the coating film may be decreased. The mass concentration ratio of tannin or tannic acid to a silane coupling agent may preferably be 1:35 to 35:1, more preferably 1:30 to 30:1, and most

- 14 -
preferably 1:20 to 20:1. [0030]
In the present invention, the fine particulate silica is a generic term for silica, which has a fine particle size and accordingly can provide a stable dispersion state thereof when dispersed in water. Specific examples of the fine particulate silica may include: commercially available silica gel, such as "SNOWTEX N", "SNOWTEX C", "SNOWTEX UP", "SNOWTEX PS" (all mfd. by Nissan Chemical Industries Co., Ltd.), and "ADELITE AT-20Q" (mfd. by ASAHIDENKA INDUSTRIES, LTD.), and powdered silica, such as AEROSIL #300 (mfd. by Nippon Aerosil Co., Ltd.), and the like. The fine particulate silica can be selected as appropriate, depending on the performance thereof to be desired in the present invention. When the fine particulate silica such as "SNOWTEX C" which can be stably dispersed even at pH of 4 or more is used, the storage stability of the primer-treating agent can be enhanced. This is probably because the pH of the agent solution can be adjusted to 4 or more, and thus the reaction of the silane coupling agent, which is more reactive at a low pH, can be prevented.
According to the present invention, the advantage of using the silica which is stable at pH 4 or more, is the storage stability. Accordingly, the desirable use of such a silica is not inconsistent with the adjustment of pH to 2 to 6.5 for the purpose of the operational stability. [0031]
With respect to the mass concentration of fine particulate silica in the treating agent, the mass concentration of the total of tannin or tannic acid and a silane coupling agent may preferably be 1:10 to 20:1. If it is less than 1:10, the aggregating ability of the primer-treated layer is decreased, to thereby reduce the coating film adhesion after stamping, and if it exceeds 20:1, the coating film adhesion after stamping may be

- 15 -
deteriorated. The ratio of the mass concentration of the total of the tannin or tannic acid and the silane coupling agent, with respect to the mass concentration of the fine particulate silica may more preferably be 2:10 to 15:1, and most preferably be 4:10 to 10:1. [0032]
The polyester resin to be used in the primer-treating agent for a precoated metal sheet according to the present invention should have a particle size of 50 to 150 nm, a glass transition temperature (Tg) of 0 to 30°C and a hydroxyl value of 5 to 13. Due to the presence of such a polyester resin in the primer-treating agent, it is possible that poorly soluble reaction products resulting from the reaction of a highly reactive silane coupling agent with a portion of tannic acid are prevented from associating with one another and from aggregating, to thereby prevent the precipitate formation. It may be presumed that the effect of preventing the precipitate formation, which is due to the specific polyester resin having a particle size of 50 to 150 nm, a glass transition temperature (Tg) of 0 to 30°C and a hydroxyl value of 5 to 13 is caused by a mechanism such that the reaction product of the silane coupling agent and tannic acid is adsorbed to the hydrophobic portion of the polyester resin emulsion by the hydrophobic interaction therebetween, to thereby inhibit the association of reaction products with one another and the aggregation thereof. [0033]
If the Tg of the polyester resin is less than 0°C, a skinning phenomenon may occur and the stability of the polyester resin in the treating agent is decreased, to thereby reduce the above-mentioned effect of preventing the precipitate formation, and precipitate is liable to be formed. [0034]

- 16 -
Here, the skinning phenomenon is explained. At a temperature below the glass transition temperature (Tg) of a polyester resin, the particles of the polyester resin emulsion are in a glassy state, have a hardness and have no fluidity per se. Accordingly, even if the emulsion particles collide with each other, they do not fuse and thus are being stably dispersed. However, if the temperature is higher than Tg, the emulsion particles become in a rubbery state or liquid, and thus if the emulsion particles collide with each other, they aggregate and fuse. Particularly, at the surface of the treating agent in a paint pan whereat evaporation of is moisture is caused, whereby the emulsion is concentrated, aggregated (or fused), and coagulated. As a result, there is created a state such that the polyester resin forms a skin at the liquid level of the treating agent (i.e., a skinning phenomenon occurs). Further, the emulsion particles have electric charges on the surfaces of particles, and the particles are being stably dispersed due to the repulsion toward each other. However, Zn ions in the treating agent neutralize the electric charges and thus weaken the repulsive force, to thereby cause aggregation and fusion of the particles. Accordingly, in such a state, the skinning phenomenon may easily occur. [0035]
If the particle size of the polyester resin is outside of the proper range thereof, the skinning phenomenon may also occur. If the particle size is less than 50 nm, the number of adjacent particles is increased so as to provide a higher viscosity, and the movement of particles per se becomes dull and thus the particles are liable to aggregate, to thereby cause skinning. On the other hand, if the particle size exceeds 150 nm, a large area of particles are exposed to the air layer on the outermost surface of the treating solution so as to promote the moisture evaporation in the region

- 17 -
corresponding to the exposed area, and thus particles can easily aggregate, to thereby cause skinning. As a result, the stability of the polyester resin in the treating agent is similarly decreased, and the above effect of preventing the precipitate formation is lost, whereby the precipitate is liable to be formed. [0036]
If the Tg of the polyester resin is exceeds 30°C, the desired performance after the film formation cannot be obtained (that is, the coating film adhesion after stamping of the precoated metal sheet is decreased, as compared with that in the case of the polyester resin having a Tg which is within the above preferred range). [0037]
Patent Document 5 discloses that a primer-treating agent for a precoated metal sheet containing a polyester resin in addition to tannin or tannic acid, a silane coupling agent and fine particulate silica is effective in enhancing the coating film adhesion after stamping. However, when the present inventors used such a treating agent in practical operations, they encountered a problem of the precipitate formation in the treating agent during a long-term use in a steady state, as described above. At this time, the present inventors used a polyester resin (Finetex ES-650: mfd. by Dainippon Ink & Chemicals, Inc.) as described in the Example of Patent Document 5. [0038]
Then, after the repetition of various experiments and investigations in order to solve the above problem, the present inventors have discovered that the polyester resin to be used in this case should be a specific one having a particle size of 50 to 150 nm, a Tg of 0 to 30°C and a hydroxyl value of 5 to 13. Incidentally, when the polyester resin is subjected to a measurement by using the method as described in the present specification of the subject application, it has been found that the polyester resin (Finetex ES-650: mfd. by Dainippon Ink &

- 18 -
Chemicals, Inc.) described in the Example of Patent Document 5 has a particle size of 300 nm and a glass transition temperature (Tg) of 40 to 50°C. The Example of Patent Document 5 mainly intends to demonstrate the adhesion of the coating film to the primer-treated metal sheet, and accordingly the presence or absence of the precipitate formation in the treating agent during a long-term operation has not been confirmed, although the "storage" stability of the treating agent has been confirmed. This shows that the phenomenon of the precipitate formation in the treating agent during the long-term operation has not been recognized at the time of filing the application relating to Patent Document 5. [0039]
In the present invention, the Tg of the polyester resin may preferably be 1 to 28°C, more preferably 3 to
25°C, and most preferably 15 to 25°C. [0040]
The enhanced "storage" stability of the treating agent described in Patent Document 5 has been attained by using a silane coupling agent of a triethoxysilane type or fine particulate silica which is stable at pH 4 or more. The storage stability of the treating agent depends on the reaction between highly reactive components (i.e., a silane coupling agent, fine particulate silica, and tannic acid) during the storage (i.e., before the treating agent is actually used) of the treating agent. Accordingly, the storage stability of the treating agent represents a characteristic prior to the actual use of the treating agent. In contrast thereto, the problem of the precipitate formation during the long-term operation using the treating agent, which the present invention intended to solve, is encountered during the actual use of the treating agent after the storage, and thus is a completely different problem from the storage stability of the treating agent.

- 19 -
[0041]
In the primer-treating agent for a precoated metal sheet according to the present invention, if the hydroxyl value of the polyester resin is less than 5, the electric charges on the surface of the emulsion particles become insufficient and the stability (dispersibility) in the solution is decreased. Thus, the precipitate may easily be formed, and the effect of preventing the precipitate formation cannot be sufficiently exhibited. If the hydroxyl value of the polyester resin exceeds 13, the hydrophobic interaction cannot easily be obtained, and thus the reaction product cannot have an affinity for
(i.e., cannot be adsorbed to) the polyester resin, to thereby cause the precipitate formation.
[0042]
As the polyester resin to be used in the primer-treating agent for a precoated metal sheet according to the present invention, any polyester resin can be used, as long as the polyester resin can satisfy the above conditions of particle size, Tg and hydroxyl value. When a commercially available product is used, a product which satisfies the conditions can be selected from "Vylonal" series mfd. by TOYOBO Co., Ltd., "Finetex" series mfd. by Dainippon Ink & Chemicals, Inc., "NT" series mfd. by Kao Corporation, and the like.
[0043]
The mass concentration of the polyester resin in the treating agent may preferably be 0.1 to 10 times that of the total of tannin or tannic acid and a silane coupling agent. If the mass concentration is less than 0.1 times, the effect of adding the polyester resin cannot be exhibited, and if it exceeds 10 times, the coating film adhesion after stamping is decreased. It may more preferably be 0.15 to 5 times, and most preferably 0.2 to 2 times.
[0044]
In the primer-treating agent according to the

- 20 -
present invention, the mass concentration of the total of tannin or tannic acid, a silane coupling agent, fine particulate silica and a polyester resin may preferably be 10 to 200 g/L. If the total mass concentration is less than 10 g/L, the desired amount of attachment can hardly be obtained. On the other hand, if it exceeds 200 g/L, the concentration is too high to secure the stability (i.e., storage stability, storage and operational stability) of the primer-treating agent. [0045]
The primer-treating agent according to the present invention may preferably have pH of 2.0 to 6.5, and more preferably 3.0 to 6.0. If the pH is less than 2.0, the elution of Zn tends to be increased, and precipitate tends to be formed due to the increased Zn concentration in the treating solution. On the other hand, in the neutral region with pH higher than 6.5, the stability of fine particulate silica is decreased and thus gelling is liable to occur. [0046]
The upward fluctuation in pH of the primer-treating agent according to the present invention may preferably be 1.5 or less, when the agent is contaminated with 100 ppm of Zn ions. The treating agent showing an upward fluctuation in pH exceeding 1.5, when 100 ppm of Zn ions are homogeneously dissolved therein, has a poor pH buffering ability, and is liable to cause an extreme pH rise locally in the treating agent during operation, whereby the pH rise is liable to badly affect the stability during operation, in most cases. In order to keep the upward fluctuation in pH to 1.5 or less, it is effective to keep the mass concentration of tannin or tannic acid (TA) in the treating agent to 5 g/L or more. It is considered that the reason for such a mass concentration is attributable to the pH buffering effect caused by proton dissociation of tannin or tannic acid. [0047]

- 21 -
The presence or absence of the precipitate formation during Zn contamination as an evaluation of the stability during operation was determined by the following method. To a treating solution, a predetermined amount of zinc powder (particle size: about 0.3 to 1.5 mm; 14 to 50 mesh, ASTM) was added, and dissolved by stirring at 40°C for 3 hours to thereby prepare a 100 ppm zinc solution. To a 500 ml plastic bottle equipped with a cap, 300 ml of
this solution was poured, and allowed to stand in a 40°C incubator for 3 days. Then, the resultant solution was filtered by using a #300 mesh filter to collect the precipitate. After the washing thereof with pure water, the precipitate was sufficiently (for about 2 hours) dried in a 110°C oven, and the temperature was returned to an ambient temperature in a desiccator, and then the mass of the precipitate was measured. When the mass of the resultant precipitate was less than 1 mg, it was determined that there is no precipitate.
[0048]
Then, there are described the methods of measuring the Tg, hydroxyl value and particle size of the polyester resin (an aqueous dispersion type polyester resin emulsion having a solid content of 20%) to be used in the primer-treating agent according to the present invention.
[0049]

A resin has a property such that the specific heat of the resin is changed, as the state of the resin is changed in the vicinity of the Tg (glass transition temperature) thereof. The DSC method uses this property. In this method, the change (i.e., endothermic change in the vicinity of Tg) caused in the specific heat of a sample is measured, when a standard reference material and a sample to be measured are heated at the same condition of temperature increase. In the present invention, Tg was measured by using the DSC method.

- 22 -
[0050]
First, about 1 g of a polyester resin is taken in a Teflon (registered trademark) Petri dish of a diameter of 50 mm. This is placed in an oven having an atmosphere of 50°C for 2 hours, to thereby evaporate the moisture in the resin. Then, it is allowed to stand in a vacuum desiccator for 24 hours to prepare a dry sample. The sample is pulverized, and then about 10 mg of the sample is taken in an aluminum cup to be used for a thermal analyzer. Aluminum powder is used as the standard reference material, and about 10 mg of thereof is similarly taken in an aluminum cup. The aluminum cup is mounted in a thermal analyzer, and cooled to -50°C, and then measurement is started. The temperature increase rate during the measurement was 20°C/min. The endothermic and exothermic data during measurement were collected, and the thus obtained data were analyzed by using an analytical software attached to the measuring instrument, which reads the temperature at which heat change was observed, and Tg (°C) of the resin was determined from the data.
Thermal analyzer used in this measurement: DSC-210 mfd. by Seiko Instruments Inc. [0051]
The hydroxyl value was measured according to Method A described in JIS K1557-1 (Plastics, The Acetylation method — Polyols for the production of polyurethane — Part 1: Determination of hydroxyl value). The sample to be measured was subjected to the evaporation of moisture at 50°C, in a manner similar to that in the measurement of Tg as described above, and the sample was dried in a vacuum desiccator for 24 hours, and then used for the measurement. By use of a potentiometric titration wherein AT420 mfd. by KYOTO ELECTRONICS MANUFACTURING CO., LTD., was used, the endpoint was determined, and the

- 23 -
hydroxyl value was calculated by using the predetermined
equation.
[0052]

A polyester resin is diluted with pure water so as to provide a solid content of 0.1 %. About 500 g of the resultant liquid is poured in a 1 L glass beaker, which was then soaked in an ultrasonic cleansing apparatus (600 W, 40 kHz) for 1 minute, to thereby effect the ultrasonic dispersion. This was carried out as a pretreatment for loosening the particles which had been aggregated as secondary particles. The resultant dispersion was used as the sample to be measured, and the particle size thereof was measured by using an instrument for measuring a particle size distribution. The particle size was determined in terms of the average particle size, which was calculated from an analytical software attached to the instrument.
Instrument used in the measurement: NANOTRACK UPA-EX 150 (mfd. by Nikkiso Co., Ltd.). [0053]
The pH of the treating agent was measured by using a pH meter (pH meter HM-30G, DKK-TOA CORPORATION). [0054]
The upward fluctuation in pH at the time at which a sample was contaminated with 100 ppm of zinc ions, was measured in the following method.
First, the initial pH value of each of the treating agents was measured by using a pH meter. Then, a predetermined amount of zinc powder (particle size: about 0.3 to 1.5 mm; 14 to 50 mesh, ASTM) was added to each of the treating agents, and dissolved therein under stirring for 3 hours at 40°C, to prepare a solution containing 100 ppm of zinc. The pH value of the resultant zinc-containing solution was measured by using a pH meter. The upward fluctuation in pH was obtained by subtracting

- 24 -
the initial pH value obtained earlier, from that of the
zinc-containing solution.
[0055]
The primer-treated coated metal sheet according to the present invention is characterized in that the primer-treating agent for a precoated metal sheet according to the present invention has been applied onto the surface of at least one side of a metal sheet and then dried. [0056]
In order to form a primer-treated layer on a metal sheet by using the primer-treating agent according to the present invention, the primer-treating agent (agent solution) is applied onto a metal sheet, and then heated and dried. The agent solution may contain an acid or alkali so as to adjust the pH thereof, as long as it does not badly affect the performance of the agent solution. The heating temperature may preferably be 50 to 250°C. If the temperature is less than 50°C, the rate of water evaporation is too slow to provide a sufficient film-forming property, and thus the resultant rust resistance
becomes insufficient. If it exceeds 250°C, the allcyl moiety of organic matters such as tannic acid and the silane coupling agent is subjected to thermal decomposition, etc., and is denatured, to thereby reduce the adhesion and corrosion resistance. The heating
temperature may more preferably be 7 0 to 160°C. The methods of heating and drying are not specifically limited. For example, hot air drying may be used, and in this case, drying for 1 second to 5 minutes may be preferred. [0057]
The method of applying the primer-treating agent is not specifically limited, and it is possible to use any of publicly known coating methods such as roll coating, air spraying, airless spraying, immersion and the like.

- 25 -
[0058]
The amount of the primer-treating agent according to the present invention to be attached to the metal sheet may preferably be 10 to 500 mg/m^, in terms of a solid content. If it is less than 10 mg/m^, sufficient coating film adhesion after stamping cannot be secured, whereas if it exceeds 500 mg/m^, the coating film adhesion after stamping is decreased. [0059]
The precoated metal sheet according to the present invention is characterized in that it comprises an upper coating film disposed on a primer-treated coated metal sheet according to the present invention, wherein a primer-treating agent according to the present invention has been applied onto the surface of at least one side of a metal sheet and then dried. [0060]
In the precoated metal sheet according to the present invention, the base resin of the upper coating film to be applied onto the primer-treated layer may be any form such as water-based, solvent-based and powder-based resins. Specific examples of the type of the resin may include: any commercially available resins such as polyacrylic resin, polyolefin resin, polyurethane-based resin, epoxy-based resin, polyester-based resin, polybutyral-based resin, melamine-based resin, etc., s they are or in combination thereof. [0061]
A colored pigment may be added to the upper coating film. Specific examples of the colored pigment may include: any of publicly known colored pigments, for example inorganic pigments such as titanium oxide (Ti02) , zinc oxide (ZnO), zirconium oxide (ZrOa) , calcium carbonate (CaCOs) , barium sulfate (BaS04) , alumina (AI2O3) , kaolin clay, carbon black and iron oxide (Fe203, Fe304) , and organic pigments, and the like. [0062]

- 26 -
To the upper coating film, an antirust pigment may be added as desired, in addition to the above colored pigment. Specific examples of the antirust pigment may include: any of publicly known pigments, for example: (1) phosphate-based antirust pigments such as zinc phosphate, iron phosphate and aluminum phosphate, (2) molybdate-based antirust pigments such as calcium molybdate, aluminum molybdate and barium molybdate, (3) vanadium-based antirust pigments such as vanadium oxide, and (4) fine particulate silica such as water-dispersible silica and fumed silica. Chromate-based antirust pigments such as strontium chromate, zinc chromate, calcium chromate, potassium chromate and barium chromate are environmentally toxic, and thus they should not be used.
[0063]
The thickness of the upper coating film containing a colored pigment and/or antirust pigment may preferably be 1 to 25 \xm. If the thickness is less than 1 \xm, the corrosion resistance of the precoated metal sheet becomes poor, and if it exceeds 25 |jin, the stampability of the coating film becomes poor. However, when the metal sheet is used as a surface-treated metal sheet in which the upper coating film is an organic or inorganic coating film such as lubricant coating film and anti-fingerprint coating film, and is to be used for the purpose of post coating, or for the purpose of application wherein a further coating is not carried out, the kind or film thickness of the upper coating film may be selected as appropriate, depending on the intended use, and thus the film thickness is not limited to 1 to 25 jam.
[0064]
The application of the upper coating film may be carried out by a publicly known application method, such as roll coating, curtain flow coating, air spraying, airless spraying, immersion, bar coating, brushing, etc.
[0065]

- 27 -
In the precoated metal sheet according to the present invention, a coating film containing an antirust pigment may be disposed as a lower coating film between the primer-treated layer and the upper coating film. [0066]
The base resin of the lower coating film may be any form of water-based, solvent-based and powder-based resins. In addition, it may be an adhesive layer. Specific examples of the type of the resin may include: any of commercially available resins such as polyacrylic resin, polyolefinic resin, polyurethane-based resin, epoxy-based resin, polyester-based resin, polybutyral-based resin, melamine-based resin, etc., as they are or in combination thereof. Specific examples of the antirust pigment may include: any type of publicly known pigments, for example, (1) phosphate-based antirust pigments such as zinc phosphate, iron phosphate and aluminum phosphate, (2) molybdate-based antirust pigments such as calcium molybdate, aluminum molybdate and barium molybdate, (3) vanadium-based antirust pigments such as vanadium oxide, (4) fine particulate silica such as water dispersible silica and fumed silica. Chromate-based antirust pigments such as strontium chromate, zinc chromate, calcium chromate, potassium chromate and barium chromate are environmentally toxic, and thus these pigments should not be used. The amount of the antirust pigment to be added may preferably be 1 to 40% by mass. If it is less than 1% by mass, the effect of corrosion resistance is poor, and if it exceeds 40% by mass, the stampability of the coating film is decreased and is unsuitable. [0067]
The thickness of the lower coating film containing an antirust pigment may preferably be 1 to 25 |am. If it is less than 1 |jin, the antirust effect of the coating film becomes poor, and if it exceeds 25 [xia, the

- 28 -
stampability of the coating film becomes poor. The application of the antirust pigment-containing coating film may be carried out by using a publicly known application method, such as roll coating, curtain flow coating, air spraying, airless spraying, immersion, bar coating, brushing, etc. [Examples] [0068]
The present invention will now be explained more specifically below with reference to Examples according to the present invention and Comparative Examples. [0069] 1. Preparation of sheet to be tested
1.1 Sample material
- Electrogalvanized steel sheet (EG)
Sheet thickness 0.6 mm, the amount of zinc attached to the sheet: per one side 20 g/m^ (both sides were plated)
- Hot-dip galvanized steel sheet (GI)
Sheet thickness 0.6 mm, the amount of zinc attached to the sheet: per one side 60 g/m^ (both sides were plated)
- Cold-rolled steel sheet (Cold roll)
Sheet thickness 0.6 mm [0070]
1.2 Pretreatment
The sample material was immersed in a 20 g/L aqueous solution of alkaline degreasing agent CL-N364S (mfd. by Nihon Parkerizing Co., Ltd.) at 60°C for 10 seconds, and was washed with pure water, and then dried. [0071]
1.3 Primer treatment
- Treatment with a primer-treating agent (Examples 1 to
96, Comparative Examples 1 to 61)
A primer-treating agent having a composition (the amount in terms of g/L) as shown in the column of "Primer-treated layer" of Tables 1 to 5 was applied onto

- 29 -
the sample material so as to provide a predetermined thickness by using a roll coater, and dried in a hot air drying furnace so as to provide a reached sheet temperature of 70°C, 150°C or 220°C. Among the solid components of each of primer-treating agents, the tannic acid, a silane coupling agent and silica to be used herein were as follows: [0072]
(a) Tannic acid
Tannic acid AL (mfd. by Fuji Chemical Industry Co., Ltd. )
(b) Silane coupling agent
Silane coupling agent A: y-glycidoxypropyltrimethoxysilane
Silane coupling agent B: y-mercaptopropyltrimethoxysilane
Silane coupling agent C: methyltrichlorosilane
Silane coupling agent D: y-glycidoxypropyltriethoxysilane
(c) Silica
ST-N: SNOWTEX N (mfd. by Nissan Chemical Industries Co., Ltd.)
Aerosil: AEROSIL #300 (mfd. by Nippon Aerosil Co., Ltd. )
ST-C: SNOWTEX C (mfd. by Nissan Chemical Industries Co., Ltd.) [0073]
As the polyester resin, there were used those having the Tg and hydroxyl value as shown in Tables 1 to 5 appearing hereinafter. [0074]
- Application-type chromate treatment (Comparative Examples 36 to 38)
As an application-type chromate-treating agent, ZM-1300AN (mfd. by Nihon Parkerizing Co., Ltd.) was applied onto the sample material by using a roll coater so as to

- 30 -
provide an amount of attached Cr of 4 0 mg/m^, and then dried in a hot air drying furnace so as to provide a reached sheet temperature of 70°C. [0075]
- Electrolytic chromate treatment (Comparative Example
39)
The sample material was subjected to an electrolytic chromate treatment by applying an electric current in a bath containing 50 g/L chromic acid and 0.3 g/L sulfuric acid at a current density of 10 A/dm^ to an electrical quantity so as to provide an amount of attached Cr of 40 mg/m^, then washed with water, and then dried in a hot air drying furnace so as to provide a reached sheet temperature of 80°C.
[0076]
1.4 Lower coating film treatment
A coating material shown below as a primer coating material was applied onto the primer-treated sample material by using a roll coater, so as to provide a predetermined film thickness, then cured and dried in a hot air-blown induction heating furnace so as to provide a reached sheet temperature of 220°C, to thereby form a lower coating film.
[0077]
- Polyester A
P641 primer coating material mfd, by Nippon Paint Co., Ltd.; a zinc phosphite-based antirust pigment was used.
- Polyester B
P641 primer coating material mfd. by Nippon Paint Co., Ltd.; a V/P (vanadic acid/phosphoric acid)-based antirust pigment was used.
- Polyester C
P641 primer coating material mfd. by Nippon Paint Co., Ltd.; a Mo-based antirust pigment was used.
- Polyester D

- 31 -
P641 primer coating material mfd. by Nippon Paint Co., Ltd.; a calcium silicate-based antirust pigment was used.
- Urethane
P108 primer coating material mfd. by Nippon Paint Co., Ltd.; a zinc phosphite-based antirust pigment was used.
- Epoxy
P304 primer coating material mfd. by Nippon Paint Co., Ltd.; a zinc phosphite-based antirust pigment was used. [0078] 1.5 Upper coating film treatment
FLIOOHQ (polyester-based, a white color) mfd. by Nippon Paint Co., Ltd., was applied onto the lower coating film-treated sample material by using a roll coater, so as to provide a predetermined film thickness, and then cured and dried in a hot air-blown induction heating furnace so as to provide a reached sheet temperature of 220°C to thereby form an upper coating film. [0079]
2. Evaluation 2.1 Coating-film adhesion after stamping. Test 1
A 1 mm-grid pattern was formed on the coated side of the sheet after coating, by cutting thereof with a cutter knife, and was subjected to protruding by using an Erichsen cupping tester so as to provide a convex shape of 7 mm on the coated side. Then, the resultant product was subjected to a tape peeling test according to the method described in JIS K5400, Sections 8.2 and 8.5. In this case, the tape peeling test was carried out for two consecutive times on the same portion of the sheet to be tested (hereinafter, such a test is referred to as the "twice peeling test"). The tape peeling was evaluated according to an exemplary figure for evaluation as described in JIS K5400, Sections.5. The thus obtained

- 32 -
results were expressed by a symbol "AA" for a score of
10, a symbol "A" for a score of 8 or more to less than
10, a symbol "B" for a score of 6 or more to less than 8,
and a symbol "C" for a score of less than 6.
[0080]
2.2 Coating-film adhesion after stamping. Test 2
The sheet after coating was subjected to 180° bending (OT stamping in the atmosphere of 20°C) , and the processed portion of the coating film was observed with a loupe of 20 magnifications to examine the presence or absence of cracks in the coating film. In addition, an adhesive tape is attached onto the processed portion, and the tape was then peeled vigorously, and the state of the remaining coating film was visually inspected. In also this test, the tape peeling test was carried out by using twice peeling test. The resultant cracks of the coating film were expressed by "AA" when no cracks were observed in the coating, "A" when 1 to 3 very small cracks were observed in the coating, "B" when very small cracks were observed throughout the entire coating, and "C" when large cracks were observed throughout the entire coating even under visual inspection. In addition, the state of the remaining coating film after the tape peeling was expressed by "AA" when the coating film was not peeled at all and remained on the steel sheet, "A" when the coating film was partly and slightly peeled, "B" when the coating film was partly and heavily peeled, and "C" when the coating film was peeled throughout almost the entire processed portion. Further, the coated steel sheet was subjected to OT stamping, and thereafter it was immersed in boiling water for 1 hour, then was taken out therefrom, and allowed to stand for 24 hours. Then, the coating film was subject to tape peeling test. The state of the remaining coating film was expressed by "AA" when the coating film was not peeled at all and remained on the plated steel sheet, "A" when the coating film was partly and slightly peeled, "B" when the coating film was

- 33 -
partly and heavily peeled, and "C" when the coating film was peeled throughout the entire surface of the bent-processed portion. [0081]
2.3 Corrosion resistance test
The sheet after coating was subjected to a saline spray test in a method described in JIS K5400, Section 9.1. The test time was 240 hours for the electrogalvanized plated steel sheet, and 360 hours for the hot-dip galvanized plated steel sheet. The coating film on the cross-cut section was expressed by "AA" when the maximum blister width on one cross-cut side was less than 1 mm, "A" when the maximum blister width was 2 mm or more to less than 3 mm, "B" when the maximum blister width was 3 mm or more to less than 5 mm, and "C" when the maximum blister width was 5 mm or more.
For the flat sheets, each of which had been produced so that the burrs during cutting were provided on the evaluated side of the coated steel sheet, the above-mentioned saline spray test was carried out. The results were expressed by "AA" when the blister width of the coating film from the edge face was 2 mm or less, "A" when the blister width was 2 mm or more to less than 3 mm, "B" when the blister width was 3 mm or more to less than 5 mm, and "C" when the blister width was 5 mm or more. When the original sheet was a cold-rolled steel sheet, the corrosion resistance test was not carried out. [0082]
2.4 Storage stability test of a primer-treating agent
The primer-treating agent to be used in each of
Examples was stored in a 4 0°C oven for a predetermined time, and then it was used to fabricate each of the coated metal sheets under the condition according to each of the Examples. The resultant coated metal sheet was then subjected to the "coating film adhesion after stamping test 2" described in the above "item 2.2". The thus obtained results were compared with those obtained

- 34 -
in the case of using a fresh primer-treating agent. As a result of the comparison therebetween, the maximum storage time of the primer-treating agent during which no decrease in the coating film adhesion after stamping was observed, was expressed as the storage stability of the primer-treating agent. [0083]
2.5 Operational stability test of a primer-treating agent
(1)
Zinc powder (particle size: about 0.3 to 1.5 mm; 14 to 50 mesh, ASTM) was added to a solution of each of the primer-treating agents of Examples and Comparative Examples, so as to provide a concentration of 100 ppm, and was dissolved therein under stirring at 40°C for 3 hours. Then, 300 ml of the solution was poured into a 500 ml plastic container equipped with a cap, and was allowed to stand in a 40°C incubator for 3 days. The solution was taken out of the incubator and then was filtered with a #300 mesh filter to thereby collect the precipitate. The precipitate was washed with pure water, and then the precipitate was sufficiently dried in a 110°C oven (for about 2 hours). The temperature of the precipitate was returned to an ambient temperature in a desiccator, and the mass of the precipitate was measured. When the mass of the precipitate was less than 1 mg, it was determined that there was no precipitate. The results were expressed by "AA" when no abnormalities were visually observed and no precipitate were observed in the solution which had been allowed to stand in an incubator for 3 days, "A" when slight turbidity was observed but no precipitate was observed in the above solution, "B" when precipitate of less than 100 mg was observed in the above solution, and "C" when precipitate of 100 mg or more was observed in the above solution. [0084]
2.6 Operational stability test of a primer-treating agent

- 35 -
(2)
(This test was conducted on the assumption that an accumulation of the primer-treating agent is caused since the circulation of the primer-treating agent in the piping during operation was insufficient.)
In this test, the step of dissolving zinc powder under stirring at 40°C for 3 hours in the test method in the above item "2.5" was omitted. More specifically, 300 ml of the solution of each of the primer-treating agents in the Examples and Comparative Examples was poured into a 500 ml plastic container equipped with a cap, and zinc powder (particle size: about 0.3 to 1.5 mm; 14 to 50 mesh, ASTM) was added to the solution so as to provide a concentration of 100 ppm. Then, the resultant solution, as such, was allowed to stand in a 40°C incubator for 3 days. The solution was taken out of the incubator and then was filtered with a #300 mesh filter to thereby collect the precipitate. The precipitate was washed with pure water, and then the precipitate was sufficiently dried in a 110°C oven (for about 2 hours). The temperature of the precipitate was returned to an ambient temperature in a desiccator, and the mass of the precipitate was measured. When the mass of the precipitate was less than 1 mg, it was determined that there was no precipitate. The results were expressed by "AA" when no abnormalities were visually observed and no precipitate were observed in the solution which had been allowed to stand in an incubator for 3 days, "A" when slight turbidity was observed but no precipitate was observed in the above solution, "B" when precipitate of less than 100 mg was observed in the above solution, and "C" when precipitate of 100 mg or more was observed in the above solution. [0085]
The results of the above evaluations are shown in the following Tables 6 to 10.

- 36 -[0086]

- 37 -
' I
priiiiiiiiiiiiiiiiiiiiiiiiiiiiii!
° -^ 22Sgfiggg22SSSgSSSSfig22SS2SSSgsi
j C
I Ipl ..............................I
^ itf| llllllllllllllllllllllllllllltl
Ill §°lllii§§lliiil;;fiil§§§°°°°°li
^li_ Hvv I
I-a: I
^ £ ^-
ag,g^|__.______________
11 || ||ii§S§§SSS§8g8...sSSSSSSSSSSsJ
""^ c
4_) "^S oooooooooooooooooooooo'-'^^-'ooo'-''-''-
^ I i
to ^S ooooooooooooooooooooooooooooooSi.
I I _^ s
rH O CO inioioinininLnLnLDinm ininLOLnmiOLDLOLnLninLnLnLnintQ
■a <; ooooooooooo oooooooooooooootn
1^
II §gSggSgS°So§SsgoSooSogoSooSoo3
" 1 ¥¥?¥¥¥?¥??¥¥¥¥?¥¥¥¥?¥¥¥??¥¥¥¥?
•sf-l
4) 2
;^ ^^„^^^^<,<^0;-;cs;r,3.^|^oo2o^c^,.-,.vor^05a;o

- 38 -
i^^iiiiiiiiiiiiiiiiiiiiiiiiiiiiii
^ a- isrsstsiisrsimiriiinnmii
! Ji!i_::::::::::::::::::::::::::::::
.5 rt;a;fl;fl;<<;<<<;<;(U(U(D(l)(U{D(l)O(P(D{l)(U4-)J-J-P-P-P-P-P
p. i^ oooooooooooooooooooooooooooooo
M g ^ m —
iM TH-HS^ inmiDLnLnLninmi iinminLnLnLnmLnLDLnLninLninLnLDLnLn^ir)
'b^h C --
D^ +J
o oJ^iclS (D Q)(i)(ya)(i)(D(i)Qja>a> inLr)^^^^-t^^^^^^^^TH1~ll-^r^I^^-^,-^^.-^
OH EH "^
CJ
4-1 "^S oooooooooooooooooooooooooooooo
^1 _
4_) ^S oooooooooooooooooooooooooooooo
L, m "^ ,
Q) O
>, & U
M o \, ' • •
*"* < oooooooooooooooooooooooooooooo
T3 E-i
0
JJ ,
rtJ JJ
u ^
jj "^ oooooooooooooooooooooooooooooo
1 -p CSlCS|C^rv]CNJCNJCNICNICNICsICNCslCN|CslC>JCNCNrs]CsJCNCNJCNICN]CN(NCS|Cs|CN|CN]CNl
6 C
■r' -^ -H
u T) 'z: — s^
(0 .=
o 211
^ _
-H N oooooooooooooSoSoSo^oooooSof^oo
Qj
■p
c
f^ oooooooooooooooooooooooooooooo
_ ■*=; <^JCgf^l^^lCsJ(^JCNC^IC^IC^JC^]Cs|C-lii>vD>i)>j3ii3',D\D\Dr^r-r-t^r-r-r-r~r-r-cocooocDCOCDOoaooDODcn
o ^
~~^ E-t UUIMCdMtJtdtJpdtdtJtdcJtdtJWtdtjqtdtiqutdtiJtdtdWCdtatdtjL]

- 40 -
)=! iHUwg LOLni/i IT) IT) LD LnLDioLninLnmLnLnLDinLOi/iLOmLnLDLnLDLniOLnLrjiD
T] [U £ C —
m g i^
'J-H i*-! (utytuQ)aia)0(uaj(p(yQ>
,in OC 4Jj-t4-» -P -P -U aJjJ-P-P-P-P-P-P-M-iJaJaJaJ-P-P-P-i-i-P-Ma-tjJj-J-P-P
9i TJtn (uojd) -P-P4-»-P-l->-P-M4-J4JP4-l4->-P-PPP
LJ C"r;n3ri (D(1)CD Q) Q) CD li3lD(D(D(D(D(l)(l>{D(DQ>a)tDiDtl)Q>Q)0(DCl>(DO)(D(D
> id'-^OS .-IMM ^ >H -H •H^M.-H.H'H-H-H-H'HrH.H.H'H'H'H'H'-t'H'H'HrHrHrH
o '^ oooo o ooooooooooooooooooooooooo
^ QJOJOJCLJ CM OiCMOjCLiDjCUCMQjCMDjCMaiaiaiPjGjajCUCMCMCLiCMCLiCMCLi
Sflg OOO O O O OOOOOOOOr-,^00000000000000
?CD0C30000000OOO
cm i ^ .-H.H.-I M rH i E^ U
■"* ^ < oooo o ooo oooooooooooooooooooo
•o ^
tu
^ ^
iJ OJ ooo O O O OOOO^f^iQioOOOOOOOOOOOOOOOO
y 4-1 CNJCNOJ CM CM CNJ CNCMLniD^^^^^^^Ol^CNCNJCNJCNCMCNCgCNICMCNJCNJCNCNJCN
e c "
■H .H ^
0< (1) ? HI -E ~
RtoS"\Lr)ior- '■*} in in mi~-inr-inr-inr-inr-Lnr-inin'^^inLn'<3'^'^^inr-
^ =
>- S^ SSS-" S 3a>^cx=2^aoSaD^S°Sp3°Sie.c,^c.S
O ~ I I I I
Q, __
■^^ 3^S o ° o ogo°o°ogogogS°S^So°oooog
0^
p c
f] ooo o o o oooo^f,, oo^vi INI oooooooooooooo
to S
-H U
__
CO XJ 222 2 2 2 2222222222222222222222 "j;:!";;! C III I I I llllllllllllillllliiii^^
■H HHE-i fr> H H E-<£-'F^EHHHtHE-iFHHE-(E-tE-tHHEHEHHHE-'E-'«a'LnLn^'>3''3'^^'*a'"^'^'3''q''3''!r'*'^'!7''^
m -I g o
Zl g-^^
w o "^ -p
I ^
H C
C-nfj ooo o o o oooo^r,, oo„, „, oooooooooooooo
CU"P CNJCMCM CN] CNJ CN] tNCNJinin''^^^CN]CNJ^^''^CNCN]CNJCNJCNJCSjrs]CN]CNJCNJCNJCN]CNJCN
g ra g
I ^ u
° C S ^ -O^-O-l-D-l
T^ ■'-* m OOO-HrHM-H^-HMMMlHMHMMMI-HMMMMMHMMMMMIHMM
2cii"J [dtdUOOOOOOOOOOCOOeJOCJOOCJCJOOOOOCJOOOO
,—, ^ "^ o
^^ cu iHCMfO^ in C£) ,,,...,,.1—lt-H>Ht—Ir-lr-Hi—IrHiHrHCNJCNJCNJCNCN
00^ c5^cnOl<3^ cji "^XXXXXXXXXjJJJi/'JJJJJJJJJJ
O^ MMM". MWMtJ". UUUUWUUMUUUUUUM
S^ 333 3 3 3 §gg§g§gg§ggggggggggggiig
■—' I I I I I I I ["["["["["["["["["ICJIUIUIU O|U|O|U|U|U OOO O|O

- 41 -
l^irillllllllllllllllllTTlTTTlTTllTTlllTI
■H -TH-HSI. LDinintnLDLnLnLnLnLDLDLOLntninLnLnminLn Lomio m m i i i \ ID m m m ID in ID m
! iifi iiiiiiiiiiiiiiiiiiiitiiti,, . Jiitiiii
III §lill°°i§l§l§°§§§°§ § III § °°i §§§§ li
—_—_ __
j'"!^
i
§1 ii il°°°°°§°°°°ssllli§s g§§ s 5gs gggs gg
o 2 ^ "
4j ^S oooooooooooooooooo'-' o '^ *"* o '-' o
4j ^S oooooooooooooooooo'--' o *"" o*-* o-^j^-J^^
>» g CO inininininLnLnLnLDinmLnLDiniOLOirjLr) LDLD mio LOU^OJOJCD-P
■H ^ < oooooooooooooooooo OO OO OOfOfOfdO)
I S g-c;^-, ~ .2-3 -3 ^
s illl I I 1-:^ a a
o __ . . .
■^1 SggSSSSgSgggggSgSgog g g ° ggg g gg g
S o
rti^ —-—^-7-—7-—
I J^ zl ll ll_^ zl
III ggSgggggggggggggggog ggo ° g°g ggo° go
^■g-H SSS555BS5S55SgaSS[55 5 SS5 5 335 3 3jaE^ [^S3g§'3g
_ ;^ '^'y "• ^_

- 42 -
^ I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I
O ^ H .5 —
n 'ri n g 0)
&» ^ ra
" m
^ o
g >,/, c5
S3 ri M S £
'-' m
iH O
S M 3
^ 8 a "-S" -S
o*^:§iog'-'cdqcD.g3rt<<<<333<<3rf333" 'N ?<; ?S ?S IN ?S ?S ?S PS ?S ?S ?S ?S ?S ?S ?S

- 43 -
J 'H I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I
^ ° I t-^
S -^ a g S
a^" "
e-^-" -^
O
&?t'M5-P,, >1>1>I>.>,>,>,>1>-1>.>1>1>1>I>1>,>1>1>1>1>7>1>1>I>1>1>1>1>1>1
M'^fi'J^^O XJ'O'O'd'O'0T3'0'O'OT3T3'C(T3'O'OTJTJ*t3'C('O'O'd'0'CiTJT3X3'OTJ
4-)"d^9^tO^ tHiHrHtHi-ti-HrHrHiHr-l»HTHfHr-ooCTiOtH(Nro^mvDr-ooo^OrHCNiro^Lf)VDr^coo^o
Q to
— ■—' I |M|U|H|H|M|U|W|M|M|H|W|M|[J|H|H|M|[J|H|W|H|M|IJ|H|MIM|H|M|H|M|M

- 44 -
TT^ I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I
o >■ g C -
Q w
___ .
^ o I „~ aJS Id -^ Id
" M
in O
"'-tjO'JjCP 'd'0'd'dtdid(d(didid2'2'3io)MSS)mmS<"<''<''<'' Id J-) O-W ti XI
to
a
^S -.
u ">
o
o
I- C ^ \ „
S "• aa o.!i 5
]i ■^ 5 3
S w " " ^-g^ „
■a 5 fi "^s -S
04
^ B ^ g ^ ^ •&
m O 5 in U S
' ' 0) ^ I
r-(r)r~oocno
Q ^ iX)i^vx)iDiX)«^y3ii>iDr-r-r~r-r-r-r~r-r-r-ooooooooa3aDoocDCOooa^
Q "* _) _j »-< _i_j
M-gajJ mn*^"^ '^ ^ .HrH m ^ '-'
4-1
m
C I
8 5 "
to
o
o
G ess
g ■^ 3 5
•u^? 'Oc■^^o'i ^f5<
o
o
r- c ^ \ ^
w 5 £ " ri - -o
10 « -p -rH M !i ■;;!
_ I "-g I " a
'—' _■ '-'"-''-''-'"-''-''-''-''-'UOOOUOOOOOOUOOCJ

- 46 -
f ^ I I I I I I I I I I l°J I I I M I I I I I I I I I I I I I I I I I I I I I
__^_1^ U.
^ n o _
° " ^
in I
o
'".nSiXjCIo ai m "> "> "^ "> (UOiDiorotd nj id lO
'-'r^B'SJio SiSiajaiuia)! oi o-d-a-oiTJi i i i-di i i i i i-oi i j-oi i i i
M-ga£! ""inminin ion
-T—^
(1) °
8 5 "
" O " 4J S
o •
in o ^ tun -5,
c Bis
i .';i jj-p —:::
I S fi "d^ -S
jj _—.—
■•^5■m oSSam^moomSuoooumSoupQSSSSS
m
c « o
9 G M OJ
§ 5 "
2 CO o
-H M tl ti
O I 1
I—I rH lOw^r-oocTtoTHCNro^ LD vor-oocrtotHCMcn"^iniX)r-aDO^OTHrsjrO'^ir)V£)r-Qo