GB2151641A - Hydrophilic film-forming coating compositions - Google Patents

Abstract

A hydrophilic film forming coating composition comprises a resin binder, an aqueous or non-aqueous liquid diluent, and an ion exchange resin powder dispersed therein. An article provided with a film coating of such composition has good hydrophilic and non-fogging properties due to the presence of the ion exchange resin and if the article has first been provided with an undercoat treatment, the corrosion resistance of the article is improved. One particular application of the hydrophilic coating composition is in the coating of corrugated fins of heat exchangers to prevent atmospheric moisture condensing thereon.

Description

SPECIFICATION Hydrophilic-film-forming preparations This invention relates to hydrophilic-film-forming preparations which form hydrophilic films on surfaces of materials such as metal, glass, plastics, etc.; to articles having such hydrophilic films; and to a method offorming a hydrophilicfilm especially having corrosion resistance.

The term "article" as herein used means that made of an appropriate industrial material such as metal, glass, plastics etc. in an appropriate shape, for example, a section sich as a short-length plate material, a continuous-length plate material (e.g. a rolled product such as foil, sheet, plate), a circular material such as rod, bar, tubular product, a press blank material, an extruded section etc. orworkpieces obtained by processing the above into desired final shapes, which have been provided with a film, and in the case of a section, said shape also includes that adaptableforplasticworking processes such as forging, deep-forming, bending, punching, etc.

Hydrophilic-film-forming preparations are used for imparting hydrophilicfilms on material surfaces so as to preventtheformation of condensed water droplets on the material surfaces and also for antistatic and defogging purposes.

For example, in heat exchangers equipped with plate or with corrugated fins, with the progress in the tendency to higher performance and to compactness, the inter-fin distance has been made smallerfor improving the heattransfer capacity. Heat exchange with the atmosphere is made via the fin surface and atmospheric moisture condenses on thefin surface, but if the inter-fin distance has been made smallerto e.g. 3-4 mm or less, the condensed water forms a bridge between the fins and hence increases the airflow resistance, thus resulting in noise generation and a reduction in energy consumption efficiency, and therefore, there has been the practice to prevent the bridge formation by imparting hydrophilic properties to the fin surface.For imparting such hydrophilic properties, an appropriate means is employed according to the metal material used, and, for example, it is known to coat resin paints containing a silica powder ora surface active agentasan agentfor imparting hydrophilic properties. However, various problems were encountered;; for example, the silica powder came off on press molding resulting in reduced uniformity of the film, and in orderto avoid this, if the silica powder was added in a large amount, it in turn reduced the thickness ofthe inorganic film and reduced the corrosion resistance ofthe film. Whereas, if the hexavalentchrominum ion concentration was increased in order to offset this the effect of silica, then the hexavalent ions dissolved outfrom the formed film and caused die abrasion when die molding was conductedafterthefilmformation,orthe surface active agent gradually dissolved out with time to decrease the hydrophilic properties, and in some use atmosphere, the increase in hydrophilic properties caused a decrease in the corrosion resistance ofthe metal material.

The present inventors have discovered that since ion exchange resins are inherently insoluble in water, have hydrophilic exchange groups and a strong nature to absorb water from the atmosphere, by dispersing an ion exchange resin powder in a resin paint, an excellent hydrophilic-film-forming preparation may be obtained. Furthermore, by providing an appropriate undercoat treatment, the corrosion resistance is also improved, and from continuing with a further intensive study, they have thereby having accomplished this invention.

Accordingly, it is a main object ofthis invention to provide film-forming preparations having excellent hydrophilic properties.

Another object ofthis invention is to provide articles having a hydrophilicfilm on at least one surface thereof.

It is yet another object of this invention to provide a method of forming a hydrophilicfilm on at least one surfaceofa material.

The gist of thins invention resides in a hydrophilic film-forming preparation which comprises a resin paint comprising a coating binder component-for example, a natural resin such as an alkyd resin and a synthetic resin such as an acrylic resin - and a coating auxiliaryelementwith an ion exchange resin powder dispersed therein; an article having a film formed with said film-forming preparation on at least one surface thereof; and a method offorming a film having corrosion resistance as well as hydrophilic properties.

Examples ofthe material forthe article include metal, glass, plastics and their composites. More specifically, examples ofthe metal materials include iron, steel, aluminum, copper and other generally employed metals, and alloys thereof. Examples of the plastics include commercially available general-purpose thermoplastic synthetic resins, thermosetting synthetic resins, reinforced plastics, etc. These materials may be provided with an undercoat treatment, if desired, as described below in addition to surface cleaning such asdegreasing etc. before forming a hydrophilicfilm.

Thefilm-forming preparation which forms such a hydrophilicfilm is that having the components described below.

As the coating binder component, those conveniently used in resin paints may suitably be selected from among thermoplastic synthetic resins and thermosetting synthetic resins, but taking into consideration the use conditions of the product to which the hydrophilicfilm isto be applied, the stability of the ion exchange resin, etc., a resin having a softening temperature of 80 C or higher is preferred in the case of a thermoplastic resin. In the case of a thermosetting resin, if one having a setting temperature of higher than 1 50 C is used, the stoving time for the fil m is preferably 10 minutes or longer, whereas if a resin having a setting temperature of lower than 150 C. is used, the stoving heating time is preferably up to 1 minute.

As the resin in the coating binder component satisfying the above conditions, alkyd resins, acrylic resins, polyvinyl alcohol resins, vinyl acetate resins, epoxy resins, phenolic resins, polyester resins, silicone resins, fluorocarbon resins, urethane resins etc.

may be used but these examples are merely illustra tive and not limitative.

Further, the presentfilm-forming preparation may contain, as a coating auxiliary element in orderto obtain flowability on coating, eitherwater, in the case ofawater-based paint, ora hydrocarbon, an alcohol, an ester, a ketone, an ether or the like in the case of an organic solvent-based paint depending on the characteristics ofthe resin used, as with the case of conventional paints.

Theamountofthe solventadded may be freely selected in an appropriate range in orderto obtain flowability according to the coating means as with the case of conventional paints, and also may be selected in an appropriate range depending on the desired hydrophilic level.

As the ion exchange resin, in general, those obtained by attaching a hydrophilicatomicgroup, such as a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a phosphinic acid group, a quaternary ammonium group or a primary or secondary amine group to a condensation type resin such as a phenolsulfonic acid type, an ethyleneimine- epichlorohydrin type, an epoxy resin etc., orto an addition polymeric resin obtained bycopolymerizing styrene or methacrylic acid with divinylbenzene as a crosslinking agent, are frequently used as cation exchange resins and anion exchange resins.Further, amphoteric ion exchange resins obtained by polymerizing acrylic acid to strongly basic anion exchange resins, fluorocarbon resins into which hydrophilic atomic groups have been introduced, etc.

are commercially available and are also usable. From a viewpoint ofthe impartation of hydrophilic prop erties, ion exchange resins having an exchange capacity per gram ofthe dry ion exchange resin of 0.5 [meg.lg-Dry Ri or more, preferably 1.0 [meg./g-Dry R] or more are employed in this invention. Those having less than 0.5 cannot provide the required wettability.

Furthermore, even that based on a phenolic resin may also be applied as an ion exchange resin if it is insoluble and possesses surface active agent-like characteristics.

Ofthese ion exchange resins, cation exchange resins (also including alkali metal substituted salt types) are suitably employed in the respectthatthey are rich in hydrophilic properties and inter alia a su Ifonic acid type strongly acidic cation exchange resin is most suitable.

Further, depending on the desired hydrophilic level, it is also possible to use a mixed system of two or more obtained by mixing a strongly acidic cation exchange resin and a weakly acidic cation exchange resin, a highly basic ion exchange resin and a weakly basic ion exchange resin, or a cation exchange resin, and also possible to use a scrap ion exchange resin with or without a virgin speck.

The commercially available ion exchange resins are usually particles of 10-50 mesh and therefore used after grinding according to the desired film thickness.

In general, a film thickness of about 0.5-50 pm is practical. If it is less than 0.5 pm, a film having desired characteristics cannot be stably obtained, whereas if it exceeds 50 clam, improvement in the characteristics level according to the film thickness is not manifested but merely results in an increase in cost. Therefore, considering such a film thickness, uniformity etc., it is general to grind to an average particle diameter of 1 pm or less, for example, to effect grinding treatment by a vibrating ball mill etc. before use. For example, in the case of fins for heat exchangers, an average particle diameter of 0.5-1 pm is preferred.Further, if that ground for an analytical grade for special purposes orfora ultrapure grade is available, it is needlessto saythat it may be used as such.

Furthermore, it is also possible to apply a means for adjusting to a desired final particle diameter by auxiliary utilizing a step of kneading with a resin paint.

While the amount of the ion exchange resin added relative to the coating binder component in the presentfilm-forming preparation can be appropriately selected depending on the exchange capacity of the particular ion exchange resin used and the hydrophilic level desired for the formed film, it is necessary that the proportion of the ion exchange resin to the total weight of the coating binder and ion exchange resin powder be 0.1 or more on the dry weight basis (hereinafter, the aforesaid proportion is referred to as the "exchange resin ratio"). Ifthe exchange resin ratio is less than 0.1, it is difficultto stably obtain the desired hydrophilic level. The exchange resin ratio is suitably in the range of 0.3-0.7. If it exceeds 0.7, the adhesion to the substrate is poor.

For example, where the presentfilm-forming preparation is espacially used for antistatic purposes requiring only hydrophilic properties, the exchange resin ratio is preferably 0.5 or more, but where both hydrophilic properties and die moldability are particularly required, it is preferred thatthe exchange resin ratio be 0.3 or more. Further, where applied to defogging of plastic materials, the exchange resin ratio can be as low as about 0.2.

The solventforthe coating auxiliary element may be added to the presentfilm-forming preparation in a mode where it is added to a mixed stock solution of the coating binder component and the ion exchange resin in use, in a mode where these three members are integrally added and mixed atthe start, etc.

Further, it is also possible to add to the present film-forming preparation various additives which impart various properties to the paint. More specifically, a dispersant, a mildewproofing agent, an antiskinning agent, a slip agent, an antifoaming agent etc.

may be added in amounts of about 1-2% by weight respectively if desired. Furthermore, as an agentfor improving the initial hydrophilic properties, a surface active agent such as oc-olefinsulfonates etc. may be added in an amount of 0.5-10% by weight.

The use embodiments of the presentfilm-forming preparation are now described. Any conventional coating means in the paint art may be used,for emample, roll coating, spraying dipping, brushing, spin coating etc., and the coating weight in this case is suitably 1-3 gIm2 (dry basis). If paint is an air drying type, then it is coated and thereafter air dried as such to fix the film, or if the paint is a thermosetting type, stoving is conducted under proper heating conditions which do not adversely affectthe characteristics of the ion exchange resin.In the next place, as pre-treatment for the film-forming treatment, it is also an effective means to applyundercoattreatmentdescribed hereinbelowforthe purpose of improving the corrosion resistance ofthe material surface and the fixing of the film.

As the undercoattreatment, a method offorming an oxidized film ora method offorming an anti-corrosive metal film using aluminum, zinc, copper, chrominum etc., and the like, may be used orthesetwo methods may be used in combination.

As the method offorming an oxidized film, any of conventional methods, e.g. a chemically oxidized film method, an anodized film method etc. can be used, but the chemically oxidized film method is preferred because a film of a relatively thin thickness having excellent corrosion resistance can be continuously and inexpensively obtained.

Examples of the chemically oxidized film method include, according to the bath component, the so- called alkali chromate methods such as MBV method, EW method, Pylumin method and Alrock method and the so-called acidic chromate methods such as Bonderite method, and Alodine method, as well as Boehmitetreating method, a phosphate salt method etc.In general, there is employed a chromate film treating method which comprises using chromic acid fluoride as a main bath component and treating art a bath temperature of 20-40 Cfor 5 seconds to 5 minutes, a chromium phosphate film treating method which comprises using chromic acid, hydrofluoric acid and phosphoric acid as main bath components and treating at 26-60"C for 30 seconds to 7 minutes, a phosphate saltfilm method which comprises using a phosphate salt such as zinc phosphate, manganese phosphate etc. as a main bath component and treating at a bath temperature of 60-1 00,C for about 5 minutes, ora Boehmitefilm method which comprises treating with hot water-saturated steam, triethanolamine etc., and the like.

These methods may be effected by dipping, spraying, roll coating, steam gun method etc. Bythese methods, a chemically oxidized film of 0.005 pom or more in thickness isformed, and with less than 0.005 pm,the characteristics as the anti-corrosive undercoat are insufficient. For example, in the case offins for heat exchangers, about 0.01-0.511m is preferred, and where there is no need for molding after the film formation, or where the heat conductivity of the film is not important, a film thickness of pm or more can also be used.

Examples ofthe method offorming an anticorrosive metal film include electroplating, deposition,flame spraying, cladding etc. using a metal such as aluminum, zinc, copper, chromium etc. and an appropriate method is selected therefrom according to the nature ofthe metal material and the use.

In otherwords, for example, in the case of zinc coating, a zinofilm maybeformedbya methodwhich comprises electroplating in a bath containing 150-240 g/l ofzincoxide, 500-550 g/l of sodium hydroxide and 5-10 g/l of sodium cyanide as main components, an acidic zinc electroplating bath method using zinc sulfate,zinc chloride and zinc borofluoride, a zincate electroplating bath method using zinc oxide and sodium hydroxide as main components, a neutral zinc electroplating bath method in which the bath contains a chelating agent such as an oxy acid in addition to zinc chloride, a pyrophosphoric acid bath method etc., ora molten zinc plating method which comprisesflux pre-treating with ammonium chloride and ammonium zinc chloride and subsequently dipping in a molten metalliczinc bath, zincflame spraying, cladding, orthe like. Asthe method of coating aluminum, there may be used molten aluminum plating which comprises dipping in a flux bath comprising a chloride system of potassium chloride and sodium chloride or a fluoride system ofcryoliteand aluminum fluoride and subsequently dipping in a molten aluminum bath, plasma flame spraying, vacuum deposition, cladding etc.

By these methods, an anti-corrosive metal film of 3 pm or more in film thickness is formed, and ifthe thickness is less than 3 calm, the characteristics as the anti-corrosive undercoat are insufficient. The film thickness varies depending on the use purpose, and, for example, in the case of fins for heat exchangers.

about 5-10 pm is preferred, but where there is no need for molding after the film formation orwherethe heat conductivity ofthefilm is not important, an appropri atethicknessofmorethan 10Xum maybe used.

Ofthese methods, as the undercoattreating method of improving the corrosion resistance, the chromate treating method is most preferred in practice and this can exertthe best effects including economy.

Thehydrophilicfilm according tothis invention has been described above, and the film formed with the present preparation has such features as extremely low deterioration with time in use and very small die abrasion when a material to be treated is die molded afterthe film formation. Therefore, it is not only suitable as a hydrophilic-film-forming preparation for fin members for heat exchangers equipped with high density fins but it also can form a film rich in the power to retain hydrophilic properties which is not achievable with the conventional preparations and thus may be used for e.g. antistatic defogging purposes etc., and, in addition, by providing desired undercoat treatment, excellent corrosion resistance is manifested.

This invention is more particularly described by the following examples.

EXAMPLE 1 A commercially available sulfonic acid type polystyrene-based cation exchange resin: 4.5 (meg/g-DRY R) (Amberlite lR-1 20 produced by Rohm & Haas Co.) was ground in a vibrating ball mill for about 30 minutes and dried by an infrared lamp to obtain a fine powder of an average particle diameter of 15 pm and a water content of 12%. Thereafter, 200 g of this fine powder, 650 g of an epoxy ester-based water soluble paint (Watersol S-352 produced by Dainippon Ink and Chemical, Inc., solids content 46%), 100 g of butyl cellosolve and 400 g of water were added to a pot mill and kneaded for about 6 hoursto achieve uniform dispersion. As a result, the secondary particle diameter ofthe ion exchange resin became 0.5-1 pm.

The resultantfilm-forming preparation was coated using a bar coater (#12) on a previously cleaned aluminum panel as a material and dried at 230 Cfor30 seconds to fix.

COMPARATIVE EXAMPLES In a case where the epoxy ester-based paint used in Example 1 was directly coated (Comparative Example 1) and a case where a commercially available thermosetting acrylic resin paint containing a wet type surface active agent (solids content 18%) was coated (Comparative Example 2), treatment was conducted using coating and drying conditionssimilartothosein Example 1. The products ofthese examples and comparative examples were subjected to various tests. The results are shown in the following Table 1.

In the table, the initial wettability shows the wetted conditions of a sample 30 seconds after picking up said sample dipped in deionized water, and is expressed relative to the case where the entire surface has been wetted taken as 100%.

Table 1

Water Wettability Die Brine Molda- Spraying Initial Wetting bility Test Wettabi- Test (after 100 hrs) lity 100% even Corrosion Example 1 100% after 1000 Good within 5% hrs Comparative Example 1 0 O Good -do Comparative 50% after Example 2 100% 30 hrs Good -do Remarks Wetting Test: The samplewas left in an atmosphere of a temperature of 50 C and a humidity of 100%.

Die Moldability: Evaluated bythe die abraded Conditions.

From these results, it can be seen that where the resin paint of Comparative Example 2 is used, although the die moldability afterthefilm formation is good, the deterioration ofthe hydrophilic properties (in this case, expressed by the water wettabil- ity) is less with the case ofthis invention and better results are obtnd by this invention.

EXAMPLE 2 8 g of a 5% solution of cobalt naphthenatewas added as a drierto the composition of Example 1, and a similar kneading operation was conducted. The resultant paint was coated on a previouslydegreased aluminium fin plate material for heat exchangers, forcedly dried and left at room temperature for 3 days to fixthe film.

Thereafter, a testsimilarto that in Example 1 was conducted to obtain almost similar results, and, in particular, itwasfound thattherewas remarkable enhancement ofthe durability againstxylene,thus indicating improved corrosion resistance. This is believed due to thatthe cobalt naphthenate acts as a catalyst.

EXAMPLE 3 Afine powdered sulfonicacid type polystyrenebased cation exchange resin obtained by the process described in Example 1:4.5 (meq./g-DRY R) (Amberlite IR-I 20) was mixed with an air drying acrylic resin paint (Acrydic A-1 65 produced by Dainippon Ink and Chemical, Inc.; solids content 45%) atan exchange resin ratio of 0.70 alsotogetherwith 0.5% based on the resin paint total weight of a wetting dispersant (BM 1000 produced by Bayerische Motoren Werke AG, West Germany) for improving the dispersibility ofthe ion exchange resin, and thereafter kneading was similarly conducted in a pot mill for 5 hours.

The resultantfilm-forming agent was coated on a transparent plastic plate of 1 .Omm in thickness to a dry film thickness of 0.5 calm and left at room temperature to dry and fix.

The coated surface obtained was subjected to an exposure test under conditions of an atmosphere of a temperature of 40"C and a relative humidity of 90 + 5"C and an outertemperature of 27"C. As a result, the plate having a film formed according to this invention kept transparent and did not show cloudiness, whereas a naked plastic plate without coating showed cloudiness on the entire surface.

EXAMPLE 4 250 g of a dried fine powder (average particle diameter 1.0 pm, water content 5%) of a weakly acidic cation exchange resin; 10 (meq./g-DRY R) (Amberlite IRC-50 produced by Rohm & Haas Co.), 700 g of a modified alkyd resin paint (P-86-50 produced by Dainippon Ink and Chemical, Inc.), 300 cc of xylene, 30 g of a dispersant (BM1 000 produced by Bayerische Motoren Werke AG, West Germany) and 7 g of a leveling agent (BM1800A produced by Bayerische Motoren Werke AG, West Germany) were added to and mixed in a high speed mixerfor30 minutes. The solids content ofthe alkyd resin paintwas 50%, and the exchange resin ratio ofthe resultantfilm-forming preparation was 0.38.

Thisfilm-forming preparation was coated by brushing on a zinc plated steel plate, and heated at 200"C to form afilm.

The wettability ofthe film was measured under conditions similar to those in Example 1 to obtain a wetting test result of 97% after 48 hours, which indicated that the deterioration ofthe hydrophilic properties was extremely low.

EXAMPLE 5 A hydrophiiic-film-forming preparation produced similarly as in Example 1 (exceptthatthe average particle diameter ofthe ion exchange resin ground in the vibrating ball mill was 1.0 pm and the water content after drying by an infrared lamp was 5% ) was continuously coated buy a roll coated on a previously degreased rolled fin material for aluminum heat exchangers as a material, and dried in a hotairdrying oven at230'Cfor30 seconds to fix.

Atest sample was prepared from the resultant fin material, this sample was dipped in deionized water, picked up and the waterwettability 30 seconds later was measured to give 100%, and when a wetting test (conducted in an atmosphere of a temperature of 50and a humidity of 100%) was carried out, the waterwettability was found 100% even after 1000 hours. Further, the brine spraying test result showed a corrosion rate after 100 hours of swithin 5%.

Thereafter, the film-formed fin material as an article was punched into fin members of a desired shape by press molding and the fin membersurfaceswere provided with louver processing.

In the press molding, neither abrasion ofthe molding die nor damage of the film was observed as was observed with silica-containing hydrophilic films, and thus good working had been effected.

Further, when the resultantfinmemberswereused by assembling into an automobile condenser, the intended continuous operation was possible even when there was a change in humidity in the atmosphere.

EXAMPLE 6 A coiled aluminum fin material (made of AA 3105 alloy, plate thickness 0.12 mm) degreased with a weakly alkaline cleaner (trade name: FC 315 produced by Nihon Parkerizing Co., Ltd.) was coated with a phosphoric acid-chromate type treating agent having a concentration of 1.3% by weight (trade name: Alodine 401-45 produced by Nippon Paint Co., Ltd.) by spraying by heating at 35"C to form an undercoat of about 70 A on the surface.

Thereafter, a sulfonic acid type ion exchange resin (trade name: R-120B produced by Japan Organo Co., Ltd.) of an average particle diameter of 0.5-1 pm was added to a catalytically curing epoxy ester-based water paint (trade name: Watersol S346 produced by Dainippon Ink and Chemical Co.) so asto give a dry solids content of 40% by weight, and thoroughly mixed to prepare a hydrophilicfilm-forming agent, which was then coated on the above undercoat to give a coating weight of 1.5 g/m2 (dry basis) and heated at 230"C in a hot air drying oven for 30 seconds to effect stoving heating treatment.

The coiled material obtained by the above filmforming treatment was subjected to punching and wiping to prepare cross members,whichwere evaluated by tests for hydrophilic properties and corrosion resistance.

More specifically, the long-term stability ofthe hydrophilic properties was evaluated by the percentags area wetted when leftin an atmosphere of a relative humidity of 95% and a temperature of 50"C for 500 hours, and this was 100%, thus confirming good hydrophilic properties.

On the other hand, the corrosion resistance was evaluated by a 500 hour brine spraying test according to JIS Z 2371(1955), and it was found that corrosion had been generated neither in the unprocessed part nor in the wiped part, thus confirming also excellent corrosion resistance, and therefore, it was confirmed that bythis invention, a film excellent in both hydrophilic properties and corrosion resistance may be obtained and that machinability afterthefllm formation is also excellent.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that variations and modifications can be made therein without departing from the spirit or scope ofthe invention thereof.

For example, it is possible that a hydrophilic film-forming agent is formed immediately on an article surface by means of mixing components which comprises a step offorming a resin paintfilm on the article surface and a step of spraying an ion exchange resin powder on said resin paint film.

Claims (34)

1. A hydrophilic-film-forming preparation which comprises a resin paint comprising a coating binder component and a coating auxiliary elementwith an ion exchange resin powder dispersed therein.

2. Thefilm-forming preparation according to Claim 1 wherein the proportion of the ion exchange resin in the total weight of said coating binder component and ion exchange resin powder on the dry weight basis is 0.1 or more.

3. The film-forming preparation according to Claim 1 wherein said coating binder component is a thermoplastic synthetic resin having a softening point of 80"C or higher.

4. Thefilm-forming preparation according to Claim 1 wherein said coating binder component is at least one resin selected from an alkyd resin, an acrylic resin, a polyvinyl alcohol resin, a vinyl acetate resin, an epoxy resin, a phenolic resin, a polyester resin, a silicone resin, a fluorocarbon resin and a urethane resin.

5. Thefilm-forming preparation according to Claim 1 wherein said coating auxiliary element is water or one member selected from the group consisting of a hydrocarbon, an alcohol, an ester, a ketone and an ether.

6. The fil m-forming preparation according to Claim 1 wherein said ion exchange resin powder is such that its total exchange capacity is 0.5 (meglg DRY R) or more.

7. The film-forming preparation according to Claim 1 wherein said ion exchange resin powder is such that its total exchange capacity is 1.0 (meg/g DRY R) or more.

8. Thefilm-forming preparation according to Claim 1 wherein said ion exchange resin powder is ground to an average particle diameter of 1 pom or less.

9. Thefilm-forming preparation according to Claim 1 or2 wherein said preparation further contains 1-2% by weight of at least one member selected from the group consisting of a dispersant, a mildewproofing agent, an anti-skinning agent, a slip agent and a defoaming agent.

10. The film-forming preparation according to Claim 1 or2wherein said preparation further contains 0.5-10% by weight of a surface active agent.

11. An article having a film formed with a hydrophilic-film-forming preparation according to Claim 1 on at least one surface of the material.

12. An article having a film formed with a hydrophilic-film-forming preparation according to Claim 1 on at least one surface of the material provided with undercoat treatment.

13. The article according to Claim 11 or12 wherein the thickness ofthe film formed with said hydrophilic-film-forming preparation is 0.5-5011m.

14. A method offorming a hydrophilicfilm which comprises a step of forming an anti-corrosive undercoat on at least one surface of a material and a step of providing a film formed with the hydrophilic-filmforming preparation according to Claim 1 on said undercoat.

15. The method according to Claim 14 wherein said undercoat forming step comprises an oxidized film forming step or an anti-corrosive metal film forming step.

16. The method according to Claim 15 wherein said oxidized film isformed by a chemically oxidized film method or an anodized film method.

17. The method accordingto Claim l5wherein said anti-corrosive metal film is formed by electro plating, deposition, flame spraying or cladding.

18. An article having a hydrophilicfilm in which the film having an ion exchange resin powder dispersed therein has been formed on at least one surfaceofthe material.

19. ThearticleaccordingtoClaim 18which has been further provided with undercoat treatment on at least one surface ofthe material.

20. The article according to Claim 18 or 19 wherein the thickness of said film is in the range of 0.5-50 pm.

21. The article according to Claim 18wherein said material is at least one material selected from the group consisting of a metal, glass and a plastics.

22. The article according to Claim 21 wherein said metal material is iron, steel, aluminum or copper.

23. The article according to Claim 21 wherein said plastics is athermoplastic synthetic resin, a thermosetting synthetic resin or a reinforced plastics.

24. The articleaccordingto Claim 18 or 19 wherein said hydrophilicfilm is formed on at least one surface ofthe material by roll coating, spraying, dipping, brushing or spin coating.

25. A method offorming a hydrophilicfilm which comprises a step offorming an anti-corrosive undercoat on a material and a step of forming a hydrophilic film having an ion exchange resin powder dispersed therein on said undercoat.

26. The method according to Claim 25 wherein said undercoatforming step comprises an oxidized film forming step or an anti-corrosive metal film forming step.

27. The method according to Claim 25 wherein said oxidized film forming step is conducted by a chemically oxidized film method or an anodized film method.

28. The method according to Claim 27 wherein said chemically oxidized film method is an alkaki chromate method, an oxidized chromate method, Boehmite method or a phosphate salt method.

29. The method according to Claim 27 wherein said chemically oxidized film isformed dipping, spraying, roll coating ora steam gun method.

30. The method according to Claim 26 wherein the thickness of said chemically oxidized film is 0.005 pm or more.

31. The method according to Claim 26 wherein said anti-corrosive metal film is formed by electroplating, deposition, flame spraying orcladding.

32. The method according to Claim 26 wherein the thickness of said anti-corrosive metal film is pm or more.

33. The method according to Claim 25 wherein said hydrophilicfilm is formed by roll coating, spraying, dipping, brushing or spin coating.

34. The method according to Claim 25 wherein the thickness of said hydrophilicfilm is 0.5-5 pm.