The present application relates to compositions for the protection and treatment of metallic substrates, in particular of steel substrates such as strip steel. More particular, the invention relates to such a composition which can function as a preservative during storage, as a lubricant during processing, and as a primer for subsequent application of a coating.

British Patent 1,094,053 describes a method for rolling steel sheet of tin plate gauges in which a film of an epoxidized soyabean oil is applied to the steel sheet"while rolling it tofinal gauge".

It is further described that the soyabean oil"affords the lubrication between the strip and the rolls of the cold rolling mill and remains on the steel sheet when reduced to final gauge. The epoxidized oil film also"does not cause eyeholing or dewetting of the laquer coating or lithographing in/E'-which provides for improved quality of a subsequently applied (decorative) coating-and imparts"a limited degree of corrosion resistance to the product before decorating".

The epoxidized soyabean oil is applied-by any suitable means-as a fine spray or mist of neat epoxidized soyabean oil or of an emulsion thereof in water.

GB 1,094,053 does not describe the use of presence of any cross-linking components in the epoxidized oil or the aqeuous emulsion thereof.

Also, according to GB 1,094,053, the epoxidized oil is applied to the steel sheet"while rolling it to final gauge". This seems to suggest that the oil is applied shortly before or during rolling, so that the epoxidized oil is not used as a preservative for the steel sheet prior to said (final) rolling.

US-A-3,582,368 describes a corrosion inhibiting composition for iron and iron containing alloys comprising casein, an epoxidized oil-and in particular an epoxidized soyabean oil or ricinus oil-and a hexavalent chromium compound.

According to Example 15-as well as to prevent the metal surface from rusting prior to painting-the composition of US-A-3,582,368 can also serve as a primer under latex paint.

US-A-3,582,368 does not mention or suggest the use of the composition described therein as a lubricant during forming processes, nor as a preservative prior to forming. Also, US-A-3,582,368 does not describe the use of a cross-linking component, whereas according to US-A-3,582,368, the presence of both casein and the toxic chromium compound are mandatory. describes a coating composition for inhibiting corrosion in metals containing an oleoresinous material prepared from a fatty oil material selected from the group consisting of drying and semi-drying oils containing long chain fatty acid radicals and a resinous material and a corrosion inhibiting epoxidized oil dervied from a drying or semi-drying oil. For obtaining the desired corrosion resistance, it is suggested to add the epoxidized oil to the final composition in amounts of 0,5%, 1%, 2% and up to 5%. US-A-2,930,708 also mentions that the epoxididized oil can be added-in essentially the same amount-to a red lead primer.

However, the compositions of US-A-2,930,708 have a very low epoxidized oil content, in particular compared to the compositions of the present invention. Also, US-A-2,930,708 does not mention or suggest the use of an epoxidized oil as either a lubricant during forming, or as a preservative prior to forming; nor mentions or suggests the use of a crosslinking component.

US-A-5,318,808 describes a Ut-curable composition for coating aluminium cans comprising 30-90 parts of an epoxidized vegetable oil, 10-70 parts of a low molecular weight epoxy resin, 2-6 parts of a photo-initiator for cationic polymerisation, and 1-5 parts of a wax or mixture of waxes. The coating is applied to the formed cans and UV-cured in order to protect the cans from abrasion and scratching during handling.

US-A-5,318,808 does not disclose or suggest the use of an epoxidized oil as a lubricant during forming, nor as a preservative prior to forming.

J. Rösch and R. Miilhaupt, Polymer Bulletin 31,679-685 (1993) describe crosslinked polyesters, obtained by curing epoxidized soybean oils with dicarboxylic anhydrides in the presence of cure catalysts. The thermosetting polyester resins thus obtained can be used for the manufacture of rubber-like low Tg polymeric articles.

Coating of metallic substrates is neither mentioned or suggested.

Steel is often produced in the form of"strip steel"or"coil", a sheet or band of metal which can be rolled up and as such can easily be stored and/or transported.

Strip steel can also easily be formed, for instance by cold forming processes such as deep drawing, rolling, stretching or bending.

After production, strip steel is usually coated with a preservative composition in order to prevent corrosion during storage. Prior to further processing, this preservative is removed, i. e. by means of degreasing. The metal surface is then treated with a lubricant composition, which facilitates further processing and improves throughput. After forming, this lubricant composition is also removed, i. e. by washing.

Thereafter, a primer composition is applied to the metal, upon which the final coating is applied.

The known methods for processing strip steel therefore involve the use of three different compositions and several processing steps, i. e.: 1. applying the preservative composition; 2. rolling up the strip steel, followed by storage/transportation; 3. removing the preservative composition by means of degreasing; 4. applying a lubricant composition; 5. forming such as by draw processing; 6. removing the lubricant composition by washing; 7. applying the primer composition; 8. applying the final coating.

The object of the invention is to improve the above methods, by reducing the number of processing steps required and/or by reducing the number of different compositions used. More particular, the object of the invention is to provide a composition which can function as a preservative for storage/transportation, as a lubricant for draw processing, and also as a primer for application for the final coating.

Other objects of the invention will become clear from the description hereinbelow.

These objects are solved by the use of a composition which comprises at least an epoxidized oil, more particular of a cross-linkable composition containing at least an

epoxidized oil, and at least one cross linking component. As the compositions of the invention can serve as a preservative, as a lubricant and as a primer, they will be indicated hereinbelow as"Preservation Lubricant Primers"or"PLP-compositions".

Also, as further discussed and illustrated below, the use of a PLP-composition comprising an epoxidized oil and at least one cross-linking component provides significant advantages compared to the use of an epoxidized oil alone according to GB patent specification 1,094,053 discussed above.

In a first aspect, the invention therefore relates to the use of a composition containing at least one epoxidized oil as a preservative for metallic substrates, in particular for steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component.

In a second aspect, the invention relates to the use of a composition containing at least one epoxidized oil as a lubricant for metallic substrates, in particular for steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component.

In a third aspect, the invention relates to the use of a composition containing at least one epoxidized oil as a primer on metallic substrates, in particular on steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component.

In another aspect, the invention relates to the use of a composition containing at least one epoxidized oil both as a preservative and as a lubricant for metallic substrates, in particular of steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component.

In yet another aspect, the invention relates to the use of a composition containing at least one epoxidized oil both as a lubricant for and as a primer on metallic substrates, in particular for/on steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component.

Yet another aspect of the invention relates to the use of a composition

containing at least one epoxidized oil both as a preservative for and as a primer on metallic substrates, in particular for/on steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one epoxidized compound.

A further aspect of the invention relates to use of a composition containing at least one epoxidized oil as a preservative for, as a lubricant for, and as a primer on, metallic substrates, in particular for/on steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component.

The invention also relates to a method for treating and/or processing of metallic substrates, said method comprising applying a composition containing at least one epoxidized oil to the metallic substrate, in which the composition containing the at least one epoxidized oil further comprises at least one cross-linking component; as well as to a composition for the protection and treatment of metallic substrates, in particular of steel substrates such as strip steel, comprising at least one epoxidixed oil and at least one cross-linking component.

In yet another aspect, the invention relates to the use of a composition containing at least one epoxidized oil as a preservative for metallic substrates, in particular for steel substrates such as strip steel, in which the composition containing the at least one epoxidized oil is applied and used as a preservative after the initial rolling of the metallic substrate, and prior to the further rolling and/or forming of the metallic substrate, for instance during storage, handling and/or transportation of the steel prior to forming or rolling to final guage. According to this specific aspect of the invention, the composition may or may not contain the at least one epoxidized oil.

Subsequently, in this aspect of the invention, the composition -i. e. as present on the substrate as a preservative-may then further be used as a lubricant for the further rolling or forming of the substrate and/or may be used as a primer for a subsequently applied topcoat, i. e. essentially as described herein.

Further aspects, embodiments and advantages of the invention will become clear from the description given hereinbelow.

The term"epoxidized oil"as used herein generally refers to an epoxidized derivative of an unsaturated fat or oil. As known to the skilled person, fats and oils generally comprise a glycerol molecule linked by ester bonds to (usually) three fatty acid residues, in which the fatty acid residues comprise long hydrocarbon chains with generally 6-32, usually 9-24, often 16 or 18, carbon atoms. In unsaturated fats and oils, one or more of these hydrocarbon chains further contain (s) generally 3 or less, and usually 2 (conjugated or non-conjugated) or only 1 unsaturated bond (s) per chain. For a further description of unsaturated fats and oils and the unsaturated fatty acids that may be present therein, reference is made to the standard handbooks.

In the epoxidized oils used according to the invention, at least one, preferably two or more, and possibly up to essentially all the unsaturated bonds in the fatty acid triglyceride are replaced by epoxide-bonds. Preferably, the epoxidized oils used in the invention will contain on average at least two epoxy-groups per molecule.

In the invention, any epoxidized derivative of unsaturated fats and oils known per se can be used. Preferably, epoxidized derivatives of natural unsaturared oils such as fatty oils, vegetable oils or animal oils are used, although the invention is not limited thereto. For instance, synthetic epoxidized oils with specifically tailored properties can be used. Such synthetic oils can contain specific functional groups on the epoxidized fatty acid chains, or may contain one or even two different side chain (s) or groups on the glycerol molecule instead of the epoxidized fatty acid residue (s), as long as the final oil can still be crosslinked as described herein.

According to a specific embodiment, epoxidized derivatives of so-called "drying oils"are used, such as soyabean oil, linseed oil and fish oil, as well as epoxidized derivatives of so-called"synthetic"drying oils such as dehydrated castor oil, and/or modifications of such drying oils. Reference is made to Kirk-Othmer, "Encyclopedia of Chemical Technology", 4th Ed., vol. 8, pages 519-531.

The epoxidized oils of the invention will generally have a degree of epoxidation of 50-100 %, more particular 80-100 %, depending upon the oil on which they are based. Preferably, the oils are epoxidized until an"epoxy-equivalent weight"or "EEW" (molecular weight per epoxy group) of at least 100, and prefeably about 200 is

reached, in which the latter corresponds to 20% by weight epoxy groups (based on a Mw of 42 for the epoxy group). Suitable mixtures of two or more epoxidized oils as described herein may also be used.

The epoxidized oils of the invention are commercially available or can be prepared by in a manner known per se, i. e. by chemical synthesis usually involving (ep) oxidation, for which reference is made to standard handbooks.

Examples of suitable commercially available epoxidized oils are epoxidized soya oils or ESO's (Edenol D81, Edenol D82, Estabex 2307, Drapex 6.8 and Reoplast 39), epoxidized linseed oils or ELO's (Edenol B316) and alkyl esters of unsaturated fatty acids, such as epoxidized alkyl esters of oleic acid (Estabex 2386, Drapex 3.2 and Reoplast 38). These epoxidized oils have been used as stabilizers and plastisizers in plastic compositions, in particular for PVC.

In the invention, the epoxidized oils may be used as such, or after suitable modification or derivatization, for instance to provide the epoxidized oils with one or more desired properties. For instance, the epoxidized oils may be modified with a compound that provides for hydrophilic groups of side-chains, such as a Jeffamine, in order to improve their solubility in water, e. g. for use in aqueous systems and in particular in (aqueous) emulsions.

Alternatively, as further described below, the PLP-emulsions may be prepared using one or more separate surfactants, such as DisponilTM 23, Tween 20, Span 20, AtsurfTM 3969 and/or Atsurf 3300B, or a suitable cellulose derivative such as Natrosol or hydroxyethylcellulose (HEC); or a suitable combination thereof.

Known systems for treating metal substrates generally comprise components such as fatty esters, wetting improvers, soaps, viscosity controllers, anti-corrosion agents such as chromium compounds, or a combination thereof. As mentioned above, these known systems do not provide the combined function of a preservative, a lubricant and a primer. For instance, known lubricants can sometimes be highly viscous. Also, they must be removed prior to coating (i. e. after forming) by the use of organic solvents or water-based systems followed by drying, as primers/coatings will generally"spread"poorly over lubricant-treated surfaces. Also, the adhesion of primers

to substrates treated with known lubricants is very poor.

Dutch application 7802712 tries to avoid these washing steps by the use of a lubricant composition that comprises at least a curable liquid component which is hardened after processing and prior to further coating. As the curable liquid component, (meth) acrylates, liquid epoxy resins, alkyd resins or aminoplasts are mentioned, which are cured thermally, by radiation or by free radicals. However, these compositions are not suggested or suitable as preservatives and also can be very toxic and consequently difficult to handle. Furthermore, the unsaturated materials of NL-A-7802712 can show poor stability, particularly when the thus coated coils are subjected to sunlight and outside air during storage. This may also detract from their lubricating properties.

European application 0 283 912 describes a cooling and lubricant composition comprising an aqueous emulsion of a film-forming binder, more particular an emulsion polymerisate or a heat-curable binder. Specific examples given comprise aqueous emulsions of epoxy resins, acrylate resins, phenol-modified polyesters, and of blockpolymers based on such resins, as well as heat-curable resins comprising melamin, urea or phenolics as cross-linkers. However, these compositions are not suggested or suitable as preservatives-probably because they may be insufficiently water-repellant to prevent corrosion-and are sticky when applied, which detracts from their lubricating properties.

Also, solid systems are known, for instance based on acrylate-, epoxy-or polyester resins. However, layers formed of such solid materials generally have poor lubricating properties and are not self-sealing.

In the invention, the use of the epoxidized oils provides for final PLP- compositions that are liquid at room temperature and/or at the temperature at which the PLP is to be applied onto the metal substrate. Compared to solid systems, their advantageous viscosity not only makes the PLP-compositions easier to apply-leading to a more uniform coating-and provides good lubricating properties, but also has the advantage that minor defects to the coating layer (scratches, pitting) as may occur during handling, transportation or processing of the treated substrate can be easily repaired by the coating itself ("self-sealing"), by"touching up"the existing layer or by

applying a further coating layer.

As mentioned above, the PLP-compositions of the invention, and more particular the epoxidized oils used therein, must be cross-linkable (curable), by which is meant that the molecules of the epoxidized oils must be able to form covalent bonds with each other other and/or with the molecules of other suitable cross-linking components of the PLP-composition (if any) to form a crosslinked structure. In principle, any curing technique known per se can be used. However, according to the two preferred embodiments, either UV-curing or thermal curing will be used, as will be further discussed hereinbelow.

The PLP-compositions used in the invention will contain at least one"cross- linking component"as described herein, i. e. a component which is involved in, initiates or facilitates the cross-linking reaction. This may be an initiator for the cross-linking reaction, for instance when UV-curing is used; a component involved in the formation of cross-linkages, such as a cross-linker (for example di-esters of di-acids such as dimethylsebacate) or a catalyst; or a further component of the PLP-composition capable of reacting with the epoxidized oil to form a crosslinked structure, such as the fatty polyacids described below.

Although not preferred, the PLP-compositions of the invention can also contain one or more further components known per se for preservatives, lubricants and/or primers, depending upon the desired properties of the composition and/or the coating and upon the curing technique used. For instance, they can contain adhesion- improvers, surfactants, anti-corrosion additives, viscosity controllers, flow improvers, stabilizers etc, in suitable amounts known per se. They may also contain minor amounts of unsaturated oils, in particular of those oils from which the epoxidized oils have been derived. The PLP-compositions of the invention can further contain a flash rust inhibitor such as SER-AD FA 179 or SER-AD FA 579 (both from Servo) or Alcophor AC (Henkel), in usual amounts.

However, compared to known (top) coatings for metals, they will generally not contain pigments or fillers. Also, although the invention is not limited thereto, the compositions of the invention are usually essentially free of solvent.

The epoxidized oils of the invention and/or the optional other components of the PLP-compositions can also carry or be modified with further functional groups, if required, for instance to confer desired properties and/or to improve cross-linking.

However, these groups are preferably chosen such that the compositions still meet the requirements set out herein.

Generally, the epoxidized oils and the further major components used in the PLP-compositions-such as the fatty acid component-will form a water-repellant coating. However, according to a specific embodiment, the compositions of the invention are in the form of an aqueous emulsion of at least the epoxidized oil. This may be a O/W- (preferred), W/O-, ternary or even quaternary emulsion. Such emulsions may have the advantage of a very low viscosity, which may be desired for certain applications.

The PLP-emulsions can be used in the same manner as non-aqueous PLP- compositions described herein. However, when PLP-emulsions are used, the method of the invention as set out below generally will comprise at least one drying step for removal of the aqueous phase, preferably directly after the emulsion has been applied to the substrate.

With respect to the emulsions of the invention, it has been found that the presence of a stabilizer for the emulsion not only improves the stability/shelf life of the emulsion, as well as its handling properties, but also improves the adhesion of a topcoat that is subsequently applied to the PLP-coated substrates, and these and other advantages will become clear from the Experimental Part hereinbelow. For instance, one or more surfactants may be incorporated, such as those mentioned above.

The PLP-compositions can be prepared in a manner known per se, generally by mixing the components in the amounts indicated herein. The PLP-emulsions can for instance be obtained by emulgating the at least one epoxidized oil and the further components of the PLP-composition in an aqueous medium such as water, optionally using stabilizers and/or emulsifiers, or by emulgating a finished PLP-composition an with aqueous medium, again optionally using stabilizers and/or emulsifiers.

Alternatively, the emulsions can be prepared using the"inversion method", e. g. as

illustrated in the Experimental Part below.

The PLP-compositions of the invention combine the properties of a preservative, a lubricant and a primer. In particular, the PLP-compositions show a good adhesion to metallic substrates without being (too) sticky when applied and/or (fully or partially) cured. In this respect, it has been found that the use of the epoxidized oils provides a suitable balance between the adhesion to the metallic (steel) surface on the one hand and the"fatty"behaviour of the composition on the other.

Also, the PLP-compositions (in uncured, partially cured or fully cured form) can form a suitable (first) primer layer upon which a further primer and/or further coatings can be applied. In this respect, the PLP-compositions are not only compatible with known primers or coatings, but can even chemically bind such further coatings, for instance via residual epoxy-groups, in particular when (further or post-) curing of the PLP-composition occurs during the hardening of the further coating. This may lead to the formation of a two-layered coating system with a diffuse intermediate layer. The good lubrication by the PLP systems may be explained by the higher viscosity of the systems next to efficient wetting of metal substrate (strong interaction of functional groups such as epoxy or carboxyl with the metal surface), although the invention is not limited to any specific explanation.

In particular, the PLP-compositions have been shown to possess the ability of undergoing chemical reactions with commercially available primer resins, such as primers based on epoxy resins or epoxy-functional crosslinkers, primers based on resins or crosslinkers containing carboxyl-functionalities, primers based on resins or crosslinkers containing hydroxyl-functionalities, and amine-functional resins and hardeners. Nevertheless, the applied PLP-compositions are generally relatively inert, even when not or partially cured, which contribrutes to their good preservation and lubricating properties.

Besides those already mentioned, the PLP-compositions of the invention also provide the following advantages: -the PLP-compositions provide for rapid curing, even at low or moderate temperature;

-the PLP-compositions have good chemical and physical stability. They generally have a pot-life of at least several weeks at room temperature; -the PLP-compositions are non-toxic and not (too) damaging to the environment.

Also, they are not expected to release harmful substances such as toxic fumes when the metal substrates on which they have been applied are formed, processed or worked in any other way such as by welding.

-the PLP-compositions provide good wetting of the metal surface and appropriate viscosity; -as a preservative, the PLP-compositions have excellent film-forming properties, providing a uniform, sealed layer that provides good protection against corrosion, for instance as determined by the salt spray test ASTM B 117; -as a lubricant, the PLP-compositions provide tribological and protective properties which are equal or better than those of conventional systems, even when fully or partiallycured; -by appropriate choice of the epoxidized oil (s) and the further components as described above, the intrinsic properties of the PLP-compositions can be fine-tuned to a specific application and/or to meet the demands of applicators and end-users; -the PLP-compositions are economically favourable.

Also, the compositions of the invention show good resistance to oxygen, even when applied to the metallic substrate. This in contrast to coatings based on the corresponding unsaturated oils, in particular drying oils, which are known to polymerise when exposed to outside air.

Furthermore, by the use of an epoxidized oil in combination with at least one crosslinking component, the above properties are even further improved, compared to the use of an epoxidized oil alone, i. e. as described in British Patent 1,094,053.

In addition, it has also been found that the use of a crosslinking component provides the following advantages, again compared to British Patent 1,094,053: -the adhesion of a topcoat to the PLP-coated substrates is further improved; the combination of an epoxidized oil in combination with a crosslinking component allows for the application/use of coating layers with increased thickness, for instance of

more than 5 um. These cannot be achieved succesfully/reliably with an epoxidized oil per se (vide the Experimental Part below).

In addition, it has been found that the invention provides advantages with respect to the welding of the coated metallic substrates. For instance, the PLP-coatings of the invention do not release harmful or toxic chemicals/vapours. These and other advantages will become clear from the Experimental Part given hereinbelow.

As mentioned above, the epoxidized oils of the invention can be cured by any chemical or physical curing mechanism or curing technique known per se, such as via curable functional groups, the presence of amine compounds or the presence of phenol and phenolic derivatives, or a similar chemical reaction. However, research by applicant has shown that either UV-curing of at least one epoxidized oil or thermal curing of a mixture of a mixture of at least one epoxidized oil an at least one fatty acid are preferred.

For UV-curing, the PLP-compositions used preferably contain at least one UV-initiator as the"crosslinking component". Suitable UV-initiators are known per se, and include those which are referred to most frequently in connection with the photoinitiated polymerization of epoxy resins, such as onium salts possessing a non- nucleophilic anion such as PF6-, SbF6-, AsF6-or BF4-.

Examples of suitable commercial photoinitiators are UVI 6990 (Union Carbide), Cyracure UVI-6974, Cyracure LTVI-690 and Rhodorsil Photoinitiator 2074.

The UV-initiator is used in an effective amount, preferably 1-5% by weight of the total composition.

The UV-curable PLP's composition can be cured by irradiation with ultraviolet radiation of a suitable wavelength, generally between 200 and 350 nm, generally at temperatures of between 0°C up to 150°C, preferably room temperature up to 110°C, and using irradiation times of less than 1 minute, usually less than 10 seconds.

In a preferred embodiment, the UV-curable PLP-compositions essentially comprise only the one or more epoxidized oils and an UV-initiator, although other additives (such as those mentioned above) can be present in minor amounts.

The UV-curable PLP-compositions provide the following advantages: -very fast cure times, typically 2-5 sec; -no oxygen-inhibition; -less sensitivity to moisture by the hydrophobic character of the base oil; -the lubrication/coating properties can optionally be fine-tune by adding a fatty polyol or by combining different epoxy compounds; -good chemical stability when not exposed to UV-radiation, which provides for a long pot-life and good stability during preservation.

Also, UV-curing can optionally be combined with a thermal post-cure, for instance by 100°C during 10 min. This post-cure can also take place during the curing of the metal primer/topcoat, to provide even further increased inter-coat adhesion.

Another preferred embodiment of the invention comprises the thermal curing of a combination of epoxidized oils and a cross-linking component capable of reacting with the epoxidized oil to form crosslinked structure.

A particularly preferred class of cross-linking components are the so-called fatty polyacids. In general, these comprise dimers, trimers or higher mers (including "intermediate"mers, such as the"1.5 mers") of unsaturated fatty acids, or mixtures thereof, containing an average at least two functional groups, in particular at least two carboxylgroups, per mer.

Suitable mixtures of dimeric and trimeric fatty acids for use in the invention are commercially available under the name of Pripol 1040 (trimer fatty acid), Pripol 1013 (dimer fatty acid), or can be obtained in manner known per se by dimerisation, trimerisation of oligomerisation of unsaturated fatty acids, optionally followed by isolation/purification of a desired fraction, such as by distillation.

The polyacids used in the invention are preferably based on/obtained from natural unsaturated fatty acids, such as can be obtained from the saponification of natural fats and oils. These unsaturated acids will generally comprise (in monomeric form) 6-32, usually 9-24, often 16 or 18, carbon atoms, and generally 3 or less, and usually 2 (conjugated or non-conjugated) or only 1 unsaturated bond (s) per chain. For a further description of polyacids and their preparation reference is made to the standard

handbooks.

The epoxidized oil and the fatty polyacid are used in a suitable ratio, generally from 1-99% to 99-1%, depending on the relative molecular weights. Usually, the amounts of oil and polyacid are chosen such that the amount of epoxygroups and carboxylgroups is between 10: 1 to 1: 10, preferably about stoichiometric.

The resulting PLP-compositions are generally non-sticky, and can be cured under moderate conditions (20-30 min. at 160-180°C).

Instead of the fatty polyacids, other suitable cross-linking components may be used, such as suitable derivatives of fatty acids, including esters thereof.

Another class of suitable cross-linking components are the amino-resins, for instance based on ureum, melamine or benzoguanidine or derivatives thereof, including urea/formaldehyde and melamine/formaldehyde resin. Of these, the use of one or more resins based on melamine and/or derivatives thereof, such as Cymel 303, is preferred, and may provide for an improved pot life for the final PLP-compositions.

Also, as will be clear to the skilled person, the above crosslinking components may be used by themselves or in a suitable combination. Also, the PLP-compositions containing the aforementioned crosslinking components may again be formulated as emulsions, e. g. as described hereinabove.

Furthermore, one or more catalysts for the reaction between the epoxidized oil and the crosslinking components may be incorporated, e. g. those which promote the reaction between the epoxy-group (s) and one or more functional groups on the crosslinking component, such as a hydroxyl or a carboxyl group. Examples are basic catalysts such as are inorganic alkaline salts (e. g., sodium carbonate), organometallic salts (e. g., lithium stearate, stannous octoate, zirconium octoate), and basic organic compounds (e. g., tertiary amines and phosphines, such as benzyl dimethylamine, tributylamine, triphenyl phosphine), etc.

The PLP-compositions of the invention may be applied to any metallic substrate, but is specifically suited for metal surfaces which are subject to chemical attack or corrosion, such as iron, steel, aluminium, in particular strip steel. The invention is particularly applicable to the field of metalworking.

The invention is in particular suited for metals which are to be stored, transported, formed and/or coated. They are also suitable as preservatives/lubricants for machine tools and steel cables; in such applications, the cured PLP-composition may be the only coating present.

The invention further relates to a method for treating metallic substrates using a PLP-composition as described herein, which method comprises at least the step of : -applying the PLP-composition onto the metallic substrate; and also preferably comprises at least one step of : - (at least partly) curing the PLP-composition, as described hereinabove; and optionally further comprises the steps of : -forming the PLP-carrying metallic substrate; and/or -applying a further primer or coating onto the PLP-carrying metallic substrate.

The least one step in which the PLP-composition is (at least partly) cured can be carried out after the PLP-application has been applied onto the metallic substrate, but prior to storage, transportation and/or forming of the substrate; after the metallic substrate has been formed but prior to application of the final or topcoat; or both. Also, curing, additional curing and/or post-curing of the PLP-coating can take place during curing of the final (top) coat.

For example, in one embodiment of the UV-curing mode, which comprises a short UV-irradiation step (few seconds), possibly followed by a post-curing step at elevated temperature for circa 10 minutes. the post-curing of the PLP can be combined with the curing of the primer applied on the PLP layer after the metal forming has been performed.

In an embodiment of the thermal curing mode typically involving curing around 180°C for circa 20 minutes, the end user may combine the curing of PLP and primer by appropriate choice of the primer (i. e., selection of a primer requiring comparable curing conditions).

The method of the invention preferably does not comprise any step in which the applied PLP-composition is removed.

The PLP-composition can be applied in any manner known per se for

applying a coating, such as spraying, rolling, dipping, brushing, pouring, by doctor blade or doctor roll; and in any suitable thickness which is at least sufficient to cover and protect the metallic surface and to fill up or coat any surface irregularities so as to provide the lubricating action of the coating.

In general, the thickness of the PLP-layer will be 0.1-10 Pm, preferably 1-10 Pm, more preferably 1-2 Pm. This is less than the usual thickness for conventional metallic primer layers, which is in the range of 20-200 hum.

The forming of the metallic substrate carrying the PLP-compositions can be carried out in any manner known per se, including cold forming processes such as drawing, deep drawing, rolling, stretching or bending; and extrusion techniques.

The further, final or top-coat can then be applied in any manner known per se, such as those described above for application of the PLP-composition. The topcoat can also be cured in a manner known per se, which may be the same as of different from the method used for curing the PLP-composition.

The invention further relates to the use of a composition comprising at least one epoxidized oil, more preferably a PLP-composition as described herein, in the treatment of metallic substrates and/or surfaces. More specifically, the invention relates to the use of a composition comprising at least one epoxidized oil, more preferably a PLP-composition as described herein, as a preservative, as a lubricant or as a primer for metallic substrates/surfaces; more preferably as a combination of any two thereof, and most preferably as a combination of all three thereof.

The invention further relates to metallic substrates treated with the (non-cured, partly cured or fully cured) PLP-application. The metallic substrates or surfaces may be formed and may also carry a further coating on the PLP-layer. In a special embodiment, the application relates to semi-finished products such as metal (steel) bars, plates, cable etc. or strip steel treated with the PLP-composition.

The invention will now be illustrated by means of the following non-limiting Examples and the Figures, in which: The invention will now be illustrated by means of the following non-limiting

Examples and the Figures, in which: -Figure 1 shows a graph of viscosity vs temperature for different PLP-compositions of the invention.

-Figure 2 shows the influence of UV irradiation dose on surface energy for a PLP coating based on Edenol B316.

-Figure 3 shows the potlife (measured as the change of viscosity in time at 22°C) of a PLP-mixture of Edenol B316 and Pripol 1040.

-Figure 4 shows the general principle of the TNO-slide/sheet-tribometer.

-Figure 5 shows the results of frictional measurements using the TNO-slide/sheet- tribometer of PLP-compositions and prior art lubricants -Figure 6 shows a schematic representation (in crosssectional side-view) of the deep- drawing process of Example XI -Figure 7 shows the metal cup obtained by the deep-drawing process of Figure 6/Figure 7.

-Figure 8 is a diagram showing gelation time of a stoichiometric mixture of Edenol B316 and Pripol 1040 containing 1 wt% catalyst, both in thin layer and in bulk.

-Figure 9 is a graph showing oil content in aqueous phase for an emulsion of Edenol B316 in water (oil/water=20/80) after 3 days as a function of the amount of Atsurf 3969 surfactant with respect to Edenol B316.

-Figure 10 is a graph showing viscosity at 25°C as a function of shear rate for water and different emulsions containing different Edenol contents, stabilized by 10 wt% Atsurf 3969 (with respect to Edenol) -Figure 11 is a graph showing surface wetting of P-G21032N (PPG) coatings on non- cured Edenol B316 as a function of film thickness -Figure 12 is a graph showing the tacky/non-tacky transition temperatures for Edenol B316/Cymel 303 mixtures of different composition as a function of curing time.

The Cymel contains 1 wt% p-toluene sulphonic acid before addition.

-Figure 13 is a graph showing the Brookfield viscosity at 50°C as a function of time for Edenol B316/Cymel 303, Pripol 1040/Cymel 303 and Edenol B316/Sovermol

Pol 1072 mixtures (10 wt% Cymel, containing 1 wt% p-toluenesulphonic acid).

-Figures 14 and 15 show photographs of MAG welding in presence of 2 different PLP's, with in each Figure from left to right: 1) reference without PLP, 2) rope on metal sheet with thick PLP layer, 3) rope on sheet with thin PLP layer, 4) corner welding on sheet with thin PLP layer.

-Figures 16 and 17 show photographs of TIG welding in presence of 2 different PLP's, with in each Figure from left to right: 1) reference without PLP, 2) rope on metal sheet with thick PLP layer, 3) rope on sheet with thin PLP layer, 4) T- welding on sheet with thin PLP layer.

-Figures 18 and 19 are photographs showing coatings of steel substrates with (Figure 18-invention) and without (Figure 19-comparative) crosslinking component, respectively.

EXAMPLE I: General properties of fatty compounds.

In this Example, for different fatty compounds, general properties are determined which are relevant for PLP applications. Viscosity is an important issue, not only considering the lubricative properties, but from the application point of view as well. Namely, in order to apply thin layers (around 1 Pm), viscosity of the PLP should not be too high. On the other hand, too low viscosities would lead to poor lubrication.

Another important parameter is the surface energy of the PLP, both before and after curing. For good wetting of a PLP-wetted surface by a metal primer, the surface energy of the primer should be lower than that of the PLP. Due to the fatty and apolar character of the PLP's, these compounds are generally expected to possess rather low surface energy values.

Experimental A. Viscosity measurements: A stoichiometric mixture of Edenol B316 and Pripol 1040 was prepared. The viscosity of this mixture was measured with a Brookfield Model DV-II+ Viscometer

(Spindle 4,100 RPM) at three different temperatures, resp. 25,50 and 75°C. Next to this, the viscosity of Edenol B316 was measured using the same procedure.

B. Contact angle measurements: Contact angles of water and diiodomethane on coated substrates were measured using a Kruss G40 contact angle system provided with an automated Kruss G1041 Video Image Analysis System at room temperature (18-20°C). Surface energies were calculated from the contact angles determined.

Results and Discussion C. Viscosity of PLP basestocks.

A graph of viscosity vs temperature for different PLP-compositions is given in Figure 1.

D. Surface energy of PLP's It was attempted to measure the contact angle of water on PLP layers containing fatty acids (Pripol 1040 or 1013) before curing. However, it was observed that within a few seconds, an interference pattern in the outer layer of the drop started to move. Shortly after this, the contact angle of the drop decreased rapidly, and finally the water wetted the PLP surface.

From different PLP materials, the surface energy was calculated via determination of the contact angle of water and diiodomethane. As a reference, the surface energy of Flexine MM (white, Akzo Nobel) was determined as well after curing. In the next Table, results are presented. Table 1: Surface Energies of different PLP systems, Flexine given as a reference TABLE 1 Surface Energies of different PLP systems, Flexine given as a reference

Surface Energy Disp. Part Polar Part (mN/m) (mN/m) (mN/m) WR-61 10/Edenol B316 (10/90) 40.3 38.7 1.6 with 5% Cyracure UVI 6990 Pripol 1040/Pripol 1013 (25/75) 34.2 32.3 1.9 with Edenol B316 Flexine MM white 44.4 43.9 0.5 From Table 1, it can be seen that surface energies of the PLP systems investigated are significantly lower than that of Flexine MM. For good wetting of a wet coating on a substrate, the surface energy of the latter should generally be higher. Thus concerning these results, no good wetting of Flexine MM on these PLP's can be expected without use of wetting improvers. Figure 2 shows the influence of UV irradiation dose on surface energy for a PLP coating based on Edenol B316.

The increase of surface energy with LTV irradiation dose becomes apparent and can be explained by degradation reactions in the coating. Due to such reactions, the polarity of the coating increases. For the initial polar part of the surface energy was relatively low, and increased with UV irradiation time. However, after a certain dose, the polar surface energy remains constant. Upon UV irradiation, the surface of the coating first will be due to degradation reactions and the surface energy will gradually increase. After a certain time, the surface has been completely reacted, and the surface energy will maintain constant. From this moment, only degradation reactions in the bulk coating will proceed.

Excessive UV irradiation might be a method for increasing the polarity of the surface and hence increasing the wetting and adhesion by the primer which will be applied on this PLP. In order to realize this, a dose should be chosen at which the surface is sufficiently attacked, while the bulk coating is not the subject of degradation

reactions.

Based upon the above considerations and measurements, it was expected that the PLP-compositions of the invention would not be particularly suited in the invention. Namely, no good wetting of paints is generally be expected on substrates (in this case the PLP layer) of significant lower surface energy. In practice, however, it was surprisingly found that the PLP-compositions of the invention provide good properties, as demonstrated by the results given below.

Also, it is clear from the above that, even at 70°C, the viscosity of the PLP- compositions of the invention may be too high for some specific methods of application. In those cases, using an (aqueous) emulsion of a PLP-composition as described above may be advantageous.

Example II: Systems based on epoxv-functional compounds and cationic LTV-initiators.

A. Sample preparation: Samples were prepared by weighing determined amounts of epoxide, UV initiator, additives and coreagants in a flask. After vigourously stirring, thin films of defined thickness were prepared on glass or metal plates by means of a doctor blade.

B. UV Irradiation: Samples were lead past a Philips HOK 20/100 UV lamp by means of a conveyor belt. The distance between lamp and sample was kept constant at 14 cm. The radiation dosis amounted to 610-630 mJ/cm2 unless described differently. Due to the intensity of the UV lamp, temperature of the samples increased to circa 60°C upon irradiation. Eventually, samples were preheated prior to LJV irradiation. After UV irradiation, samples were postcured in an aircirculated oven at 100°C.

C. Adhesion test: A cross cut test was performed including evaluation after tape (Scotch) disrupture, standard to NEN 5337, equivalent to ISO 2409 (scale: 0=excellent, 5=poor).

D. MEK rub test: A cotton-endcapped hammer was soaked with methyl ethyl ketone, and double rubs of about 5 cm were performed while keeping the exerted pressure constant at ca. 90 N/m2. The number of double rubs were counted, which were required to reach the substrate.

Results and Discussion It was expected that the cationic curing reaction of epoxidized oils would proceed significantly slower than the curing of aliphatic diepoxides such as UVR-6110 (Union Carbide). In order to investigate this, Edenol B-316 (Henkel) was chosen as epoxidized oil, and curing of this compound was compared to curing of UVR-6110 and a mixture of UVR-6110 and Edenol B-316 (Table 2).

Table 2: Comparison of curing of Edenol B-316 with UVR-6110,3 weight% UVI- 6990 TABLE 2 Comparison of curing of Edenol B-316 with UVR-6110,3 weight% UVI-6990 Composition (weight%) Evaluation UVR-61 10 Edenol B-316 After UV irradiation After postcuring 100 0 tacky nottacky 10 90 not tacky nottacky 0 100 nottacky nottacky No significant difference was observed between curing of UVR-6110 and Edenol B-316 as can be seen from Table 2. Next to UVI-6990, Cata 200 (Rhone- Poulenc) was used as an UV initiator. Also in this case, curing results did not differ significantly. For this reason, curing conditions for Edenol B316 coatings were generally chosen identical to the conditions for Wu6110, as given in technical specifications.

Edenol B316 was cured with different amounts of UVI-6974. Results are summarized in Table 3. Curing of thinner films appeared to proceed slower, which first is indicated by more tacky films after postcuring. Furthermore a lower number of MEK double rubs was necessary for going through the coating, although it must be noted that a film thickness around 9 um is very thin in comparison to the the roughness of the cotton wound around the hammer. For that reason, the results must be interpreted with care. For the thicker films, only small amounts of photoinitiator (ca. 2.5 wght%) were necessary for completely curing the coating. This initiator concentration is comparable to the concentrations necessary for commercial (aliphatic di-) epoxide to be cured.

Table 3: Edenol B316 cured with different amounts of UVI-6974 for different layer thicknesses TABLE 3 Edenol B316 cured with different amounts of UVI-6974 for different layer thicknesses coating thickness Coating evaluation after initiator conc. (wght%) MEK double rubs UV irradiation postcuring 8.6 0.59 tacky tacky- 1.19""30 2.51""30 3.11"lu 50 4.07""25 5.41 nottacky >100 17.2 1.19 tacky slightly tacky 10 2.51"">100 3.11"">100 4.07"">100 5.41"">100 The slower curing of the thinner coatings might be explained by the relatively larger influence of air humidity on thinner layers. Particularly in the case of thin coatings, as would be used in PLP applications (typically 1-2 Pm), special measures

should be taken, e. g., nitrogen atmosphere, in order to avoid curing inhibition in surroundings with increased humidity.

A large number of fatty polyols is commercially available. Addition of polyols to epoxidized oils offers possibilities for tuning coating properties to particular applications. Mixtures of Edenol B316 and Sovermol Pol 1072 were cured in different ratios. As a reference, experiments with mixtures of UVR-6110 and Sovermol Pol 1072 were performed. In Table 4, results are given.

Table 4: Curing experiments of epoxy resins with different amounts of Sovermol Pol 1072 polyol (epoxide/hydroxy ratios given refer to molar amounts of concerning groups, 5 weight% UVI-6974) TABLE 4 Curing experiments of epoxy resins with different amounts of Sovermol Pol 1072 polyol (epoxide/hydroxy ratios given refer to molar amounts of concerning groups, 5 weight% UVI-6974) Coating evaluation after MEK double rubs epoxy resin epoxy/hydroxy UV irradiation post curing | UVR 6110 95/5 not tacky nottacky >100 90/10 tacky tacky <10 80/20 tacky tacky <10 Edenol B316 100/0 not tacky not tacky >100 95/5 nottacky nottacky >100 90/10 slightly tacky slightly tacky 100 80/20 tacky slightly tacky <10

Both UVR 6110 and Edenol B316 do not allow too high amounts of polyol for forming cured films. At polyol percentages higher than 10%, a slower curing reaction can be observed in case of the Edenol B316 resin. For UVR-6110, even a lower amount of polyol is allowed. However, the worse results for UVR-6110 might also be explained by the thinner coating layers (9 pm) in contrast the the thickness of the Edenol B316 layers (ca. 17 pm). From these experiments it becomes apparent, that

presence of hydroxy groups significantly slows down the curing reaction by introducing a different mode of reaction (chain transfer). Only smaller amounts of polyol can be used in order to adjust coating properties.

In practice, adhesion improvers can be required particularly in the case of UV curing resins. The influence of three different adhesion improvers on cationic curing of Edenol B316 was investigated. Selected adhesion improvers were: Silquest A-187, A- 189 and A-1100 (Union Carbide). Table 5 overviewes curing experiments of Edenol B316 in presence of these adhesion promotors.

Table 5: Curing experiments of Edenol B316 with LJVI 6974 in presence of different adhesion improvers (layer thickness 9 Pm, postcuring 15 min. at 150fC) TABLE 5 Curing experiments of Edenol B316 with UVI 6974 in presence of different adhesion improvers (layer thickness 9 µm, postcuring 15 min. at 150°C) Evaluation after adhesion promotor structure MEK double rubs UV radiation post curing --tacky nottacky >100 Silquest A-187 (CHzOCI-n-CHaO (CHx) aSi (OCH,) v">100 Silquest A-189 HS (CH2) Si (OCH3)"25 Silquest A-1l00 H2N (CH2) 3Si (OC2H5) 3 liquid tacicy Presence of Silquest A-1100 leads to severe inhibition of the cationic curing process. This is due to the basic amine groups, which react with the acid formed upon UV irradiation of the photoinitiator. For that reason, Silquest A-1100 is not suitable as adhesion promotor in the cationic curing process.

The basicity of the thiol groups in Silquest A-189 is apparently high enough to

show a significant degree of inhibition as well. Silquest A-187 does not affect the cationic curing reaction, and is additionally compatible with epoxy resins due to its epoxy functionality.

Comparative Example 1: Svstems based on polycarboxylic acids and polyols.

In order to investigate the curing of a mixture of a fatty polyol with a fatty polyacid, stoichiometric amounts of Sovermol Pol 1072 (polyol) and Pripol 1040 (fatty trimer acid) were prepared and cured under different conditions. 2.1 g Pripol 1040 was mixed with 3.9 g Sovermol Pol 1072 and vigourously stirred with a glass bar. Thin films of ca. 80 Pm were cast on glass plates. Curing was performed at different temperatures during different times in an aircirculated oven. Appearance and resistance against MEK double rubs were investigated as a function of curing time. The curing reaction of Sovermol Pol 1072 with Pripol 1040 was also monitored by thin film FT-IR spectroscopy.

The yellow starting formulation was characterised by a fatty non-interacting behaviour which is favourable for lubricant applications. Table 6 shows the results of curing experiments.

TABLE 6 Appearance and MEK double rubs of coatings from stoichiometric amounts of Pripol 1040 and Sovermol Pol 1072 after different times of curing as a function of curing temperature Curing temp. Time Appearance MEK double (°C) (hrs) rubs 0.5 and 1 Yellow liquid film 180 2 Viscous (at RT) hellow-brown film 5 Tacky brown film, viscous at 180°C, solid at RT 30 I Rubbery and tacky yellow-brown film 50 200 2.5 Rubbery and non-tacky brown film >100 16 Flexible dark-brown coloured non-tacky film >100 0.5 Liquid, brown film- 220 1 Rubbery brown film, slightly tacky >100 2 Rubbery and non-tacky brown film >100 16 Hard non-tacky film >100

The curing reaction at 180°C was too slow to apply in commercial processes.

Only after 5 hours, a viscosity increase could be observed. At higher temperatures, the crosslinking proceeded faster. However, the brown discoloration indicated other reactions than esterification (e. g., degradation, oxidation of unsaturated bonds, formation of conjugated unsaturated bonds, etc.). This was further indicated by FT-IR spectra of cured samples. It was found that fatty mixtures of a trimer acid and polyol can only be crosslinked during reasonable times at elevated temperatures (>2000C).

Also, strong brown discolouration of the coatings suggests other reactions to occur next to esterification of hydroxy and acid groups.

Concerning the fatty behaviour of the fatty polyol/trimer acid mixtures, suitable lubricative behaviour can be expected. However, the quite vehement curing conditions are not favourable for practical applications.

Comparative Example II: Systems based on polyols and polydimethvlesters.

Concerning their lubricating behaviour, dimethylester compounds were expected to be suitable candidates as base materials for PLP systems, as illustrated by the large amount of commercial available lubricants which are based on ester compounds. However, no efficient curing reaction could be performed using dimethylester compounds with fatty polyols. Addition of different basic catalysts appeared to be ineffective. Only at very high temperatures (>220°C), a rapid crosslinking could be observed. However, this can probably be ascribed to degradation reactions as illustrated by the strong brown discoloration of the products.

A. Pripol 1040 methyl ester with Pripol 2033: 0.45 g Pripol 2033 was mixed with 0.57 g Pripol 1040 methyl ester. Thm films of the yellow-brown mixture were casted on glass plates. The films were cured in an air-circulated oven at 200°C during different times. The curing reaction was extremely slow. Also, a gradual brown discoloration could be observed.

B. Sovermol Pol 1072 with dimethyl sebacate: Stoichiometric amounts of Sovermol Pol 1072 and dimethyl sebacate were mixed together, e. g., 1.0 g Sovermol with 0.20 g dimethyl sebacate) and eventually 2 wght% catalyst (triethylamine or titanium tetra-isopropoxide). Curing was performed at 180°C in aircirculated ovens during different times.

Without addition of a catalyst, a slow curing reaction could be observed (ca.

12 hrs at 180°C) which is not in the range of those for application in commercial processes. No significant improvement was reached by addition of triethylamine, and curing appeared even to occur slower in presence of triethylamine. Deprotonation of Sovermol Pol 1072 with NaOH as well appeared to be ineffectual.

Finally, titaniumisoproxide was investigated as a catalyst. Amounts of catalyst upto 5 wght% did not show any significant improvement compared to the system without catalyst. At 220°C, a rapid cure was observed resulting in fully cured films within 0.5 hrs. However, severe brown discoloration indicated a crosslinking mechanism different from the transesterification reaction (e. g., partial degradation).

EXAMPLES III-VI: Formulations.

Several permanent liquid PLP-systems based upon epoxidized oils for use on metallic substrates were prepared as follows: III. LTV-curable coating on the basis of an epoxidized oil.

A mixture of Edenol B316 (Henkel) with 3 wt. % UV-6990 (Union Carbide) is applied as a thin layer (about 1 pm) on degreased strip steel using a doctor blade.

The metal plate is then led under an Ut-source (HOK 20/100) at a distance of 14 cm. The speed is such that the UV-dose is 610-630 mJ/cm2. After LJV-radiation a primer (Sigma Moffelprimer 67 EU) is applied at a thickness of a 35 pm. The system is thermally cured in an oven (170°C/15 min.). Both the adhesion between the top coat and the UV-hardened PLP-layer, as well as the adhesion between the UV-hardened PLP-layer and the steel surface were scored as zero. (5 = very bad, 0 =

excellent).

IV. LTV-curable formulation on the basis of epoxidized oils and fatty polyols.

A mixture of Edenol B316 and Sovermol Pol 1072 (both Henkel, ratio epoxy/hydroxy = 95/5) with 5 wt. % UV-I 6990 (Union Carbide) is applied as a thin layer (about 3 Pm) on degreased stripped steel using a doctor blade. The metal plate is led under an Ut-source (HOK 20/100) at a range of 14 cm. The speed is such that the LJV-dose is 610-630 mJ/cm2.

After UV-radiation a primer (Sigma Moffelprimer 67 EU) is applied at a thickness of a 35 Pm. The system is thermally cured in an oven (170°C/15 min.).

Both the adhesion between the top coat and the UV-hardened PLP-layer, as well as the adhesion between the UV-hardened PLP-layer and the steel surface were scored as zero. (5 = very bad, 0 = excellent).

V. Thermal-curable formulation on the basis of epoxidized oils and only fatty acids.

A stoichiometric mixture (ratio epoxy/carboxylated acid is 1/1) of Edenol B316 (Henkel) and Pripol 1040 (Unichema International) is applied as a thin layer (about 2 Pm) on degreased steel. On this liquid layer a primer (Sigma Moffelprimer EU 67) is applied. The combined system is then cured in an oven (180°C/20 minutes). Adhesion between the top layer and the lubricant layer and the adhesion between the steel substrate and the coating were scored as zero. When after applying the PLP layer a (partial) thermal curing is carried out before the primer is applied, the choice of the primer is less critical with a view to defects in the coating.

Also, in this manner, an"overbake"of the primer can be avoided.

VI. UV or thermally curable emulsion on the basis of epoxidized oils.

The viscosity of liquid-permanent PLP systems can be decreased by using emulsions. For this purpose, thermally curable formulations can be dispersed in water. a) For UV-curable emulsions a mixture of Edenol B 316 with 4 wt. % Disponyl 23 (both Henkel) and 3 wt. % UVI 6990 (Union Carbide) can be prepared. To this mixture, under stirring, water is added until the desired viscosity is achieved.

Generally, the PLP/water ratio will be between 10/90 and 25/75. A thin layer of the emulsion (about 10 lam) is applied to a degreased steel plate. The water is then removed in an oven with forced air circulation (10 minutes at 60°C), after which UV-curing is carried out and a primer is applied as described above. b) For thermally curable emulsions a stoichiometric mixture (ratio epoxy/carboxylic acid is 1/1) of Edenol 2316 (Henkel) and Pripol 1040 (Unichema International) is mixed with 10 wt. % surfactant (for example a mixture of Disponyl 23 (Henkel) and Tween 20 (Merck)). Water is added as described above. After drying, the primer is also applied as described above.

EXAMPLE VII: Potlife measurement.

The potlife of an epoxidized oil/fatty acid mixture of the invention (a mixture of Edenol B316 and Pripol 1040) was determined by measuring the change of viscosity in time at 22°C. The results are given in Figure 3.

EXAMPLE VIII: thermal curing of epoxidized oils with fatty polyacids.

The formation of a coating from mixtures of Edenol B316/Pripol 1030 and Pripol 1040) were investigated. The mixture was stoichiometric with respect to epoxy and acid groups, as a top coat, Flexine MM, white, (AKZO Nobel) was applied. The

thickness of the layers was 3-4 Pm for the PLP-layer and 33 um for the top coat. The results are given in Table 7.

TABLE 7 Coating formation mixtures of Edenol B316/pripol 1013/Pripol 1040 Ratio Viscosity at Adhesion test MEK double rub test 1013/1040 24°C (mPas) topcoat-primeri) PLP layer 0/100 3600 1 >100 25/75 2800 1-2 >100 50/50 2200 1-2 t100 75/25 1800 2 +80 100/0 1400 1-2 60

) 0 = excellent, 5 = very bad * Stoichiometric with respect to epoxy and acid groups 'Top coat: Flexine MM, white (Akzo Nobel) Layer thicknesses: PLP 3-4 Pm Top coat 33 Pm EXAMPLE IX: UV-curing of epoxidized oils.

The LJV-curing of epoxidized oils was investigated. The results are given in the next Tables 8-11.

TABLE 8 Coating formation UVR-1610/Edenol B316 (10/90) with Flexine MM topcoat (white) Photoinitiator Adhesion improver Adhesion IJV-coat Adhesion top layer Cata 200 A-187 5 5+ Cata 200 A-189 2 UVI6990A-18701-2

3 wght% photoinitiator, 1 wght% adhesion improver PLP thickness: 3 Pm, topcoat thickness: 30 us Curing schedule: PLP: 5 sec UV irrad. (620 mJ/cm2) PLP and topcoat: 15 min. at 1 50OC

TABLE9 Coating formation Edenol B316 with different topcoats Top coat % photo initiator Adhesion PLP Adhesion topcoat Flexine MM 3 0 2 Flexine MM 5 0 2-3 Sigma 67 EU 3 0 0-1 | Sigma 67 EU 0-1

Adhesion improver: I wght% A-189 Photoinitiator: UVI-6990 Curing schedule: PLP: 5 sec. UV-irradiation PLP and topcoat: 15 min 150°C (Flexine) or 170°C (Sigma) TABLE 10 Coating formation of Edenol B316/UVR-61 10 mixtures with different amounts of Sovermol Pol 1072 polyol Epoxy/hydroxy ratio Adhesion PLP coat Adhesion topcoat 100/0 0 1-2 95/5 0 2 90/10 0 2 75/25 0 3

Ratio B316/UVR-6110 90/10 (wght%) Photo initiator: 3 wght% UVI-6990 Adhesion additive: I wght% A-189 Thickness PLP: 3 um Top coat: Flexine MM (35 um) It can be seen that: Adhesion top coat decreases with increasing amount of polyol Adhesion improves with increasing amount of initiator: vide Table 12.

TABLE 11 Coating formation of Edenol B3 ! 6/UVR-6 ! ! 0 mixtures with different amounts of UV-initiator Wght% UV-initiator Adhesion PLP Adhesion top coat 3 0 1 5 0 0 Epoxy: hydroxy = 95: 5, top coat: Sigma 67 EU, adh. add. A-189 EXAMPLE X: Lubrication measurements.

The tribology of the PLP-compositions of the invention was determined on a TNO-slide sheet-tribological system, the general principle of which is shown in Figure 4.

A ring is slid under defined conditions (speed, force, etc.) over a metal plate.

The friction coefficient is determined as a function of distance. As a limiting value for the friction coefficient 0.2 is taken.

The test conditions were as follows: Sheet: Cold rolled steel MCB Stl4-03, batch 1, lmm App. Roughness l/Ra=1. 22 pm, Ra=1.22 Pm Slider: WN 1.2379, hardened and tempered at 520°C App. Roughness//Ra=0.04 pm, Ra=0.08 Pm 0 44x8 mm, radius 6 mm Parameters: sliding speed V 0.5 m/s Normal force FN 150 N Amount of lubricant 4-6 mL/m2 Track length 1800 mm Temperature (humidity) 25°C (34%)

The results are given in Figure 5. It was found that when the PLP-systems of the invention were used, it took considerably longer for the friction coefficient to increase to the limiting value, compared to both the reference N6130 (Quaker) as well as the non-lubricated reference.

EXAMPLE XI: Deep-drawing experiments Deep drawing involves clamping a metal sheet between a blank holder and a die. Subsequently, a punch is rammed into the sheet, forcing it into the die. The metal sheet adapts to the shape of the die. In Figures 6a and 6b, the process is schematically shown, in which 1 is the punch, 2 is the blank holder and 3 is the blank.

The clamping force on the blank is adjusted since a too high force may result in tearing of the product, while a too low force causes wrinkling of the product. An important parameter in the deep drawing process is the drawing ratio: B = rp)/rp where tpi is the initial radius of the blank (before deep drawing), and rp is the radius of the product after deep drawing, as shown in Figure 7.

For a given punch with particular dimensions, the force necessary for drawing a cup increases with the radius of the initial blank. At a certain critical blank radius, this force exceeds the critical force which causes the cup wall to tear. Hence, a limiting drawing ratio can be expressed as: max-rpl, max/rp The limiting drawing ratio is dependent on material properties, blank thickness and lubrication. For a given blank and tool material, an impression of the efficiency of a particular lubricant can be obtained by determining the limiting drawing ratio.

A metal sheet (St 14-03 MCB, thickness 0.97 mm) was carefully degreased, after which a commercial lubricant or PLP was applied by brush. Excessive lubricant or PLP was removed with a tissue. Deep draw experiments were performed in order to determine the limiting drawing ratio for the different systems (die: 0 = 50.0 mm). The results are given in Table 12.

TABLE 12 Lubrication Degreasing method') Lubricated surfaces of Limiting draw ratio metal sheet No NDF-2.13 No H/IPA 2.05 Quaker N6130 NDF Only die-side 2.23 NDF Both die-and punch side 2. 15 H/IPA Both die-and punch side 2.15 Petro fer S65 NDF Both die-and punch side 2.20 Petro fer S65 H/IPA Both die-and punch side 2.2 EdenolB316/Pripoll040 H/IPAOnly die-side2.35 ll H/IPA Both die-and punch side 2.23 Edenol B316 H/IPA Only die-side 2.28 H/IPA Both die-and punch side 2.25 ') NDF: degreased with Nebol (fluid), H/IPA: degreased in azeotropic vapor of heptane and isopropanol As can be seen from Table 12, limiting draw ratios in case of the PLP's generally are comparable or even higher than that of commercial reference lubricants.

EXAMPLE XIII: Catalvzed curing of Edenol B316/Pripol 1040 mixtures This Example describes experiments in which different catalysts were tested for application in thermally curing PLP's based on epoxidized oils and fatty polyacids.

Preferably, a catalyst is used which is very active at the curing temperature (180°C), but shows no activity at lower temperatures (typical for storage and metal processing).

Basic catalysts of different types were tested: Sodium carbonate and zinc oxide (inorganic alkaline salts), zinc-and magnesium stearate (organometallic salts), and

benzyl dimethylamine and triphenylphosphine (organic basic compounds).

1. Preparation of reaction mixtures: Stoichiometric mixtures of Edenol B316 and Pripol 1040 were freshly prepared before a new experiment was started. For example, 20.6 g Pripol 1040 was added to 12.7 g Edenol B316 and vigorously stirred, resulting in a yellow-brown mixture.

2. Gelpoint determination: 1) In thin layers. 2.0 g of a freshly prepared Edenol/Pripol mixture was added to 0.020 g catalyst in a round aluminium cup with a diameter of circa 4 cm. The mixture was homogenized and placed in an oven at 180°C. at regular times, a needle was drawn through the mixture. The gelation time was taken as the time, at which the mixture was not able anymore to flow into the drawn line.

2) In bulk. 5.0 g freshly prepared Edenol/Pripol mixture was added to 0.050 g catalyst in a test tube (circa 7 mL) and the mixture was homogenized by mechanical stirring. The test tube was sealed and put in an oven at 180°C. The gelation time was defined as the time at which air bubbles were not able to move through the mixture anymore upon turning the test tube.

3. Potlife measurements: 80 g freshly prepared Edenol/Pripol mixture containing 0.40 g catalyst (0.5 wt%) was stored in an oven at 50°C. At regular times, the viscosity of the mixture was measured at 50°C using a Brookfield Model DV-II+ Viscometer (2.5,5 and 10 rpm, Spindle 4) 4. Results and Discussion When mixtures of Edenol B316 and Pripol 1040 with catalysts were prepared, it appeared that not all catalysts did dissolve properly in the mixture. Particularly a large part of zinc oxide remained dispersed, even after a longer time of vigorously stirring.

The turbid mixture containing triphenylphosphine turned transparent upon curing. The gelation time was both determined in thin layers of circa 1 mm thickness, and in bulk.

In Figure 8, the gelation time is shown for different catalysts.

Although gelation of a particular system in the bulk occurred slower than in thin layers, a good resemblance was observed. Indeed, in absence of a catalyst the longest gelation time was observed. The organic basic compounds tested, dimethyl benzylamine and triphenylphosphine only slightly decreased the gelation time.

Inorganic alkaline salts like zinc oxide, magnesium-and zinc stearate were more effective at shortening the gelation time. The shortest gelation time was observed in case of sodium carbonate being used as catalyst. However, curing of the Edenol/Pripol mixture in presence of this compound was accompanied with strong gas formation.

Concerning their activity in different temperature regions, zinc oxide and zinc stearate seem the most suitable catalysts, because they are effective at 180°C in increasing the cure speed but on the other hand cause the smallest increase of the viscosity at lower temperature with proceeding time.

EXAMPLE XIV: Emulsions of Edenol B316 in water stabilised with a surfactant..

1. Emulsions of Edenol B316 stabilized by Atsurf using the inversion method: A determined amount of Atsurf 3969 was added to Edenol B316. The mixture was heated to 50°C and stirred by means of a Dispermat provided with a dissolver blade.

Demineralised water was slowly added until the inversion point was reached. The temperature was gradually decreased to room temperature and further water was added at a slightly higher rate until the desired oil/water ratio was reached.

As an example, typical conditions are given: e. g.: 0.5 g Atsurf 3969 was added to 5 mL epoxidized oil and heated to 50°C. The mixture was stirred at 4000 rpm and 10 mL water was slowly added with 0.250 mL/min. The heating was turned off, and further 35 mL of water was added at a speed of 0.333 mL/min.

2. Viscosity measurements: Measurements were performed at 25°C on a Paar Physica UDS200 using a cone and plate geometry with a truncated cone (Measuring system Z1 DIN (double gap), Device MC200 SN253581).

3. Emulsion stability determination: In first experiments, the stability of an emulsion was determined by measuring the time until precipitation of the oil phase was visible by eye.

Furthermore, samples were taken from the aqueous phase of emulsions which were stored while avoiding movement of the sample. By weighing the sample before and after evaporation of the water in vacuum at 50°C overnight, the oil content in the aqueous at the time of sample taking could be calculated.

4. Results: The influence of the Atsurf 3969 concentration on the stability of Edenol B316 emulsions was investigated. In Figure 9, the results are shown.

Three days after the preparation of the emulsions, the non-volatile content in the water phase was determined. It was observed that at Atsurf concentrations below 10 wt%, less stable emulsions were formed. Improved stability was reached at concentrations higher than 10 wt%, which is therefore preferred.

The viscosity of Edenol emulsions was measured using a rheometer provided with a cone and plate geometry. The viscosity was measured as a function of shear rate varying between 1 and 1000 s-1. Figure 10 shows the results for water and 3 emulsions with different Edenol contents.

The results show that stable emulsions can be obtained which possess viscosities which are comparable to that of water.

EXAMPLE XV: UV-curing of PLP's applied from emulsion.

This Example is directed towards UV curing of epoxidized oil which has been applied from emulsion. Edenol B316 was chosen as the epoxidized compound,

while HEC and Atsurf 3969 were used as the emulsion stabilizers. The emulsions were prepared essentially as described in Example XIV.

UV-curing was carried out as follows: Emulsions were applied on metal sheet by means of a doctor blade with a thickness of circa 35 m. The layers were dried during 10 minutes (unless described differently) under an infrared lamp. The temperature was controlled by thermocouples attached to the metal substrate, and was kept at 60°C. The dried films were lead past a Philips HOK 20/100 W lamp by means of a conveyor belt. The distance between lamp and sample was kept constant at 14 cm. The radiation dose amounted to 610-630 mJ/cm2. Due to the intensity of the lamp, temperature of the samples increased to circa 60°C upon irradiation.

In a first experiment, Edenol B316 epoxidized oil was cured in presence of UVR 6110. Table 13 shows results of this experiment.

TABLE 13 UV-Curing Edenol B316/UVR-6110 (10 wt% in total) from 1% Natrosol 250 MBR/water with different IR drying times at 60°C (Fotoinitiator: UVI-6974,5 wt% with respect to epoxy) Edenol/UVR required IR drying Appearance after UV time (min) 100/0 8 non-tacky/brown spots 90/10 8 non-tacky/glossy 80/20 8 non-tacky/glossy/brown spots 70/30 5 non-tacky/glossy/brown spots In a next experiment, it was investigated how much UV initiator is preferably used for curing the epoxy coating. Again using HEC as stabilizer,

mixtures of Edenol B316 and UVR-6110 were cured using different amounts of UVI- 6974. Results are listed in Table 14. While formulations with 2 or less wt% UV initiator after UV irradiation did result in tacky coatings, 4 wt% or more photo initiator resulted in non-tacky coatings. It must be noted that these results were obtained without further thermal post-curing step. Although post-curing is common for UV-epoxy coatings, for eventual PLP applications it is not expected as an extra step, since post-curing of the PLP coating can occur while curing the top coating which is applied on the PLP layer.

TABLE 14 Curing of mixtures of Edenol B316/UVR-6110 from 0.5% Natrosol/water with different UV initiator (UVI-6974) concentrations (Edenol B316/ UVR-6110=80/20,10 wt% epoxy) wt% initiator appearance after UV irradiation 1.6 tacky 2.1 tacky 3.9 non-tacky 5.9 non-tacky Finally, it was investigated, whether Atsurf 3969 is a suitable emulsion stabilizer that does not disturb the cationic curing reaction. Mixtures of Edenol and UVR were stabilized by 10 wt% Atsurf. Results are given in Table 15.

TABLE 15 Curing of Edenol B316/UVR-6110 from Atsurf 3969/water. (Edenol B316/UVR-6110 = 80/20,10 wt% in water, 10 wt% Atsurf 3969 with respect to epoxy) wt% UVI-6974 IR drying time appearance/ethanol resistance (min) 5.1 10 non-tacky/good 8 non-tacky/good 5 non-tacky/good 3.3 5 tacky/none 2.2 5 tacky/poor 1.3 5 tacky/fair Wetting of the steel plates by emulsions stabilized by Atsurf 3969 was much better than by comparable emulsions stabilized by Natrosol as observed in earlier experiments.

Non-tacky coatings with excellent solvent-resistance were obtained when 5 wt% UV initiator was applied. Although curing proceeds to a significant degree when lower amounts of initiator were used, coatings were tacky and sensitive towards ethanol when 3 wt% or less initiator was applied. It must be noted however, that for PLP applications no complete solvent resistance is required, because the PLP layers are completely covered by a top layer. After the curing, the PLP should have been formed into a solid layer, which can provide good adhesion with the top layer resulting in a mechanically stable coating system.

Thus, it appeared well possible to photocure an epoxidized oil that had been applied from an aqueous emulsion. The preferred concentration of UV-initiator necessary for curing the coating lies around 3 weight%, which is acceptable for commercial applications. Furthermore, even a large amount of surfactant (10

weight%) did not disturb the curing reaction.

Drying of the emulsions by means of infrared lamps proved to be efficient.

This method provides selective heating of the surface of substrates. Furthermore, ventilation is well possible.

EXAMPLE XVI: Adhesion of metal coatings on UV-curing PLP's from emulsions In this Example, film formation of different commercial coatings on PLP's which were applied from aqueous emulsions is described.

1. Preparation of UV-curing PLP mixtures: A cationic UV initiator (UVI-6974, Union Carbide) was added to Edenol B316 (Henkel) epoxidized oil. The initiator content was varied. Concentrations are mentioned in the text. The mixture was homogenized by vigorous stirring. In the case of emulsions, 10 wt% of Atsurf 3969 (ICI) was added to the PLP mixture, and an emulsion was prepared by means of the inversion method as described in the previous chapter.

2. Application of coatings: Generally, steel plates were used as substrate, unless described differently.

Metal substrates were carefully degreased using heptane/hexane vapour. A thin PLP layer was applied by means of a doctor blade (ca. 30 son). PLP's from emulsion were dried under an infra red lamp during 10 minutes at 60°C. Excessive PLP was removed with a tissue. PLP systems were UV irradiated by a Philips HOK 20/100 LTV lamp in nitrogen atmosphere prior before the commercial primer was applied.

The UV dose generally amounted to 610-630 mJ/cm2. Samples were transported along the UV lamp by means of a conveyor belt at a distance of 14 cm of the lamp.

Due the light intensity, temperature of the samples increased to circa 60°C. After UV irradiation, a metal primer was applied. Commercial primers in all cases were applied by a doctor blade. The thickness was varied. The system was thermally cured in an

air-circulated oven at conditions according to technical specifications of the metal primer used: Flexine MM White (Akzo Nobel): 15 min. at 150°C Sigma Primer 67 EU: 15 min. at 170°C P-G21032N (PPG): 10 min. at 205°C 750 Primer (Courtaulds): Flash off 10-15 min., drying 30 min./60-80°C, stoving 30 min./120°C 3. Contact angle measurements: Contact angles of water and diiodomethane on coated substrates were measured using a Kruss G40 contact angle system provided with an automated Kruss G1041 Video Image Analysis System at room temperature (18-20°C).

4. Adhesion tests: A cross cut test was performed including evaluation after tape (Scotch) disrupture, standard to NEN 5337, equivalent to ISO 2409 (scale: 0=excellent, 5=poor).

5. MEK double rub test: A cotton-endcapped hammer was soaked with methyl ethyl ketone, and double rubs of about 5 cm were performed while keeping the exerted pressure constant at ca. 90 N/m2. The number of double rubs was counted, which were required to reach the substrate.

6. Results and Discussion In a preliminary experiment, a P-G21032N coating was applied on steel, UV-cured Edenol B316, and an UV-cured Edenol B316/Atsurf 3969 layer, which had been applied from emulsion. The adhesion of the can coating on the different

substrates was determined using the crosscut test. In Table 16, results are given.

TABLE 16 Adhesion of P-G21032N (PPG) on steel, and steel treated with UV-cured Edenol B316 and UV-cured Edenol B316/Atsurf 3969 from emulsion PLP system adhesion PPG O Edenol B316 0-1 Edenol B316/Atsurf 3969 (from emulsion) 0 The adhesion of the PPG coating on metal appeared to be very good. When Edenol B316 was applied on the metal, the adhesion strength slightly decreased.

However, when the Edenol B316 was applied from emulsion in presence of Atsurf 3969 as emulsion stabilizer, the adhesion of the PPG coating was comparable to the adhesion of this coating in absence of a PLP layer. This experiment indicates that the adhesion of the top layer increases when Atsurf 3969 is added to the PLP. In order to investigate this further, surface energy measurements were performed (Table 16).

TABLE 17 Surface energies of UV-cured Edenol B316 and UV-cured Edenol B316 containing 10 wt% Atsurf 3969 applied at different layer thicknesses system layer overall disperse polar thickness (mN/m) (mN/m) (mN/m) ) Edenol B316 20 38. 4 38. 0 0. 4 2 42.9 42.2 0.6 Edenol B316/Atsurf 20 46.0 43.2 2.8 3969 2 49.1 41.2 7.9

In the case of 2 pm layer thickness, the PLP was initially applied at a thicker layer thickness of circa 30 pm. However, excess PLP was removed by means of aluminium plate which was pulled over the surface while pressing it on the substrate.

Thus, it is assumed that a final layer thickness is obtained which is of the same order of magnitude as the size of the surface deviations of the metal substrate.

For both layer thicknesses, it could be clearly observed, that the overall surface energy increased when Atsurf 3969 was added to the PLP. Relatively seen, the polar surface energy component increased much more than the disperse part. This can be ascribed to the amphiphilic nature of the surfactant. It is likely, that the lipophilic part of the surfactant molecules is in the Edenol layer, while the hydrophilic part of the molecules forms the transition layer at the coating/air surface.

Accordingly, it is assumed that the presence of Atsurf 3969 in a PLP based on epoxidized oil results in a more polar surface. Since the commercial coatings generally possess a rather polar nature as well, presence of surfactant in the PLP leads to improved compatibility between the PLP and top coating. Apparently, the surfactant is able to perform both as emulsion stabilizer and as adhesion improver.

Table 18 shows adhesion experiments for different commercial coatings on PLP's which were applied from emulsion. In order to increase the UV-curing speed of the PLP, Edenol B316 was either mixed with UVR-6110 or UVR-6128.

TABLE 18 Commercial coatings on PLP's. Edenol B316/UVR-xx =80/20,10 wt% Atsurf 3969 with respect to total amount of epoxy compound, 3 wt% UVI-6974 photoinitiator. commercial coating PLP system adhesion P-G21032N-0 (PPG) Edenol B316/UVR-0 6110 Edenol B316/UVR-1 6128 Sigma 67 EU Primer-0-1 (Sigma Coatings) Edenol B316/UVR-0-1 6110 Edenol B316/UVR-1 6128 Flexine MM-1 (Akzo Nobel) Edenol B316/UVR-1 6110 Edenol B316/UVR-1 6128 750 Primer-1 (Courtaulds Coatings) Edenol B316/LTVR-1 6110 Edenol B316/UVR-1 6128

In all cases, adhesion on the PLP layers could be obtained which was as good as direct adhesion of the commercial coatings on the metal plates.

In a next experiment, the influence of the metal substrate on the adhesion of coatings was investigated. Next to a standard steel substrate, two different galvanized steel substrates were used.

TABLE 19 Coating systems on different metal substrates. Commercial coatings on metal, or metal pretreated with PLP layer applied from emulsion with initial O/W=10/90 (ca. 2 pm, Edenol B316/UVR-6110=80/20,10 wt% Atsurf 3969,3 wt% UVI-6974) Sigma 67 P-G21032N Flexine MM 750 Primer EU PPG Akzo Nobel Courtaulds Metal substrate-PLP-PLP-PLP-PLP Steel 0-1 0-1 0 0 1 1 1 1 Z75/75 galv. 1 1 0-1 0 1 1 0 0 steel Z100 galv. steel 1 0 1 1 1 1 0 As can be seen from Table 19, there is hardly any influence of the metal substrate on the adhesion of the coating system. Generally, adhesion during the crosscut test fails at the transition layer between PLP and commercial coating layer, and not between the PLP and the metal surface.

Differences in adhesion strength for that reason only should be explained by the role that the substrate might play concerning UV-curing of the PLP layer. It was shown that the degree of curing of the PLP layer before application of the commercial coating might influence the adhesion between PLP and the top coating.

However, these experiments do not clearly indicate that adhesion between PLP and top coating is affected by the metal substrate.

It can be expected, that curing of the PLP becomes less important, when the PLP layer is thinner. In the case of very thin PLP layers, diffusion of the wet top

coating into the whole PLP layer is better possible. When a good compatibility exists, and components of the top coating are able to migrate and chemically react with the epoxidized compound, improved adhesion of the coating system on the metal substrate can be expected. In an experiment, a commercial coating (P-G21032N, PPG) was applied on a metal sheet which first was treated with Edenol B316. To the Edenol, 10 wt% Atsurf 3969 was added. The experiment was performed with Edenol layer thicknesses varying between 1 um (=order of magnitude of metal roughness) and 54 ujn. The PPG coating was applied on the PLP layer by means of a doctor blade (75 pm). By doing this, the thickness of the PLP layer and the PPG coating together amount to 75 prn. Thus, a thinner PPG layer thickness is obtained for increasing PLP layer thickness. The results are shown in Figure 11.

By performing crosscut tests, it appeared that all top coatings on Edenol B316 showed good adhesion after thermal curing of the system, even when the Edenol layer was rather thick. However, the wetting of the Edenol layer by the PPG coating was very dependent on Edenol layer thickness. Immediately after application of the PPG layer, the surface was completely covered. However, after curing had been performed, particulary in the case of thicker Edenol layers, relatively large areas without PPG coating were present. In these areas, only irregular layers of uncured liquid Edenol could be observed. Figure 11 shows the wetting percentage by the PPG coating in dependence of PLP layer thickness after curing. In the case of the thinnest Edenol layer, excess Edenol was removed after the application in order to obtain a layer, which was of the order of magnitude of the metal roughness. The thickness of this coating was arbitrarily set on 1 tm.

In the case of this thinnest PLP coating, the PPG coating contained no bare patches after curing the system, although some differences in coating thickness could be observed by eye. The percentage wetted surface decreased with increasing Edenol thickness.

Thus, the presence of an emulsion stabiliser in the PLP formulation seems to improve adhesion of commercial coatings on the PLP layer. This was ascribed to the

more polar character of the PLP surface because of the hydrophilic part of the surfactant molecules at the surface being directed to the outside of the layer. This assumption is in agreement with surface energy calculations based on measurements of the contact angle of water and diiodomethane on the PLP layers.

When the thickness of the PLP layer is of the same order of magnitude as the roughness of the steel substrate, no curing of the PLP before application of the commercial coating is required for obtaining good adhesion of the top coating.

However, it appeared that the optical appearance of the top coating is improved when the PLP is cured before the commercial coating is being applied.

EXAMPLE XVII: Thermally curing PLP's using melamine resins as hardener.

1. Preparation of mixtures: A mixture of Cymel 303 containing 1 wt% para-toluene sulphonic acid was prepared. A determined amount of the catalysed mixture was added to a weighed amount of either Edenol B316, Sovermol Pol 1072, Pripol 1013 or Pripol 1040. Ratio and/or amounts are given in the text. The mixture was homogenised by vigorously stirring.

2. Pot life determinations: The viscosity of Edenol B316/Cymel 303, Sovermol Pol 1072/Cymel 303 and Pripol 1013/Cymel 303 was measured at 50°C after different times of storage at 50°C. All mixtures contained 10 wt% Cymel 303 to which 1 wt% para-toluene sulphonic acid had been added. The viscosity of Edenol/Pripol mixtures was measured with a Brookfield Model DV-II+ Viscometer (Spindle 5,100 RPM).

3. Preparation of emulsions of Edenol B316/Cymel 303 in water: To 5 g of a mixture of Edenol B316 and Cymel 303,10 wt% Atsurf 3969 was added. In case of emulsions, no acid catalyst was applied. The mixture was stirred using a dissolver disk (diameter 40 mm) at such a rate that the mixture stayed

homogeneous upon the water addition and no water drops were visible by eye. Water was slowly added (0.05 mL/min) till 20 minutes after the moment, at which the inversion point had been reached. Subsequently, water was added at a rate of 0.3 mL/min until the total amount of water amounted to 25 mL.

4. Application of coatings: Coatings were generally applied by means of a doctor blade. Coating thicknesses were varied as mentioned in the text. In the case of aqueous emulsions, layers were dried under an infrared lamp at 60°C during 10 minutes. The temperature was controlled by means of a thermocouple. In particular cases, excess coating was removed with a tissue after application in order to obtain coatings with thicknesses of order of magnitude of the roughness of the metal substrate.

5. Curing experiments in a gradient oven: Aluminium sheet (lOOOx96xl mm) was carefully cleaned with ethanol, and a coating of circa 30 um was applied. The sample was placed in a gradient oven, which at one side was heated to 180°C and at the end to 300°C. Between the ends of the aluminium plate, the temperature linearly increased. The temperature profile was checked by 10 thermocouples along the plate. When necessary, results were corrected using the thermocouple measurements. The coatings were cured for different times.

After curing, for a particular curing time the transition temperature was determined at which the coating changed from tacky to non-tacky and from liquid to solid.

Subsequently, the plate was placed at one side in methyl-ethyl kettle for one hour, and the curing temperature was determined, at which the coating did not disappear from the aluminium substrate upon the solvent exposure.

6. Results: As can be seen from Figure 12, higher Cymel contents in Edenol mixtures led to lower tacky/non-tacky transition temperatures. The compositions mentioned in Figure 6.6 refer to weight ratios. Edenol/Cymel=4/2 represents 95 g Cymel per mole

Edenol epoxy groups as already shown in Figure 5. Using an Edenol/Cymel ratio of 1/1, non-tacky coatings can be obtained by curing around 235°C for 2 minutes. When 20 wt% Cymel was used (Edenol/Cymel=4/1), mixtures had to be cured at the highest temperatures in order to obtain non-tacky coatings at a particular curing time.

The viscosity of Edenol-, Pripol-and Sovermol-Cymel mixtures was followed in order to get an impression of the pot life. Mixtures were kept and measured at 50°C. Figure 13 shows the Brookfield viscosity as a function of time.

The Edenol/Cymel mixture did not show a viscosity increase during the first two weeks of storage at 50°C.

In another experiment, the same Edenol/Cymel mixture was prepared without acid catalyst. In this case, no inhomogenities and no viscosity increase were observed over a longer period of several months.

The stability of the emulsions was further confirmed by measurement of the non-volatile content of the emulsion as a function of time. Also, the emulsions showed excellent adhesion on both P-G21032N (PPG) and Flexine MM commercial coatings, both with a non-cured and a pre-cured PLP. The adhesion also proved essentially not to be dependant on the Cymel content.

Also, different top coatings were tested on a PLP based on Edenol B316/Cymel 303. Next to steel, two types of galvanised steel were used as substrate.

Excellent adhesion was obtained on essentially all three substrates for all commercial coatings mentioned in Table 18.

EXAMPLE XVIII: Welding of PLP-treated steel plates.

The weldability of metals treated with the PLP's of the invention were investigated, using both Metal Inert Gas (MIG), Metal Active Gas (MAG), and Tungsten Inert Gas (TIG) welding processes.

1. Preparation of PLP's: Two PLP's were prepared: 10 weight% Atsurf 3969 was added to Edenol

B316 (PLP-1) and 10 weight% Atsurf 3969 and 10 weight% Cymel 303 were added to 80 weight% Edenol B316 (PLP-2). The mixtures were heated at 50°C for 15 minutes and heavily stirred, and subsequently cooled down.

2. Application of PLP's: Steel plates were decreased with acetone, and PLP was applied at 50°C by means of a brush. Excessive PLP was removed by coated paper. In this way a thin PLP layer of 2-4 pm was obtained. In other cases, a thicker PLP layer was applied by means of a doctor blade (20 um).

3. Pulse MAG Welding: Shielding gas Ar/C02=92/8 was used and a 1.0 mm electrode (SG2). Both corner welding and drawing a rope on metal sheet (3 mm) were performed, using the following parameters: MAG-rope MAG-corner average current 100 A 143 A peak current 426 A 381 A base current 18.5 A 50 A average charge 21.2 V 22.2 V frequency 50 Hz 50 Hz 4. TIG Welding: TIG welding was both performed in T-geometry and ropes on steel sheet (2 mm). In both cases, the average current amounted to 127 An and the average charge was 12.3 V.

5. Results of MAG welding.

Pictures of MAG welded steel sheets in presence of PLP-1 and PLP-2 are shown in Figures 14 and 15.

Figure 14 shows MAG welding in presence of PLP-1, with from left to

right: 1) reference without PLP, 2) rope on metal sheet with thick PLP layer, 3) rope on sheet with thin PLP layer, 4) corner welding on sheet with thin PLP layer.

Figure 15 shows MAG welding in presence of PLP-2, with from left to right: 1) reference without PLP, 2) rope on metal sheet with thick PLP layer, 3) rope on sheet with thin PLP layer, 4) corner welding on sheet with thin PLP layer.

When the PLP-treated steel sheets are compared with blank sheets, the following can be observed: -The weld pool becomes broader in case of PLP treated sheets, and the arc sometimes is less stable.

-No porosity could visually be determined at the weld, not even when the metal sheets were treated with PLP-1 or PLP-2.

-The cross-section of the weld did not show porosity.

-No significant difference could be observed between PLP-1 and PLP-2.

6. Results of TIG welding.

Pictures of TIG welded steel plates are shown in Figures 16 and 17.

Figure 16 shows TIG welding in presence of PLP-1, with from left to right: 1) reference without PLP, 2) rope on metal sheet with thick PLP layer, 3) rope on sheet with thin PLP layer, 4) T-welding on sheet with thin PLP layer.

Figure 17 shows TIG welding in presence of PLP-2, with from left to right: 1) reference without PLP, 2) rope on metal sheet with thick PLP layer, 3) rope on sheet with thin PLP layer, 4) T-welding on sheet with thin PLP layer.

Concerning the TIG welding, the following observations were made: -The PLP did not influence the weld pool.

-No porosity could be observed in the cross-section of the weld, also not when a PLP had been applied.

-No differences were observed between PLP-1 and PLP-2.

EXAMPLE XIX: Comparison between PLP's with (invention) and without (prior art) a crosslinking component.

Edenol B316 and 10 weight% Atsurf 3969 were mixed. The mixture was divided in two parts. To one part, 5 weight% UVI-6974 photoinitiator was added.

Layers of 20 pm were applied on degreased steel plates. The layer containing the photoinitiator was cured by LTV-irradiation (ca. 620 mJ/cm2). P-G21032N coating (PPG) was applied by means of a doctor blade on both the non-cured and cured PLP layer (10 min/205°C).

The coatings thus obtained are shown in Figure 18 (invention) and 19 (comparative), respectively. Figure 18 shows a P-G21032N coating (PPG) on UV- cured PLP layer: cured film without defects. Figure 19: P-G21032N coating (PPG) on non-cured PLP layer: Although the PPG is crosslinked, the PLP underground still is liquid, and dewetting has occurred.