GB2181137A

GB2181137A - Epoxy resinous varnish its preparation and coating composition containing the same

Info

Publication number: GB2181137A
Application number: GB08624244A
Authority: GB
Inventors: Haruhiko Satoh; Hisaki Tanabe; Hirotoshi Umemoto
Original assignee: Nippon Paint Co Ltd
Current assignee: Nippon Paint Co Ltd
Priority date: 1983-10-17
Filing date: 1986-10-09
Publication date: 1987-04-15
Also published as: GB2181137B; GB8624244D0

Abstract

An epoxy resin varnish for primer coating use comprising polybasic acid modified epoxy resin or a mixture of such modified epoxy resin and unmodified epoxy resin, the said polybasic acid having a titration midpoint potential of more than -300mV in non-aqueous potentiometric titration, under state capable of developing resinous acid value, and the resinous acid value based on said polybasic acid in the final resin being 0.1 SIMILAR 50.

Description

SPECIFICATION Epoxy resinous varnish its preparation and coating composition containing the same The present invention relates to an epoxy resinous varnish and preparation thereof. The invention also concerns a heat curing type coating composition which is based on said resinous varnish and useful as a primer coating with excellent corrosion resistance on various metallic materials.

As a method for coating metallic materials as iron plate, galvanized steel, aluminum plate and the like, the so-called 2 coat-2 bake system has generally been used, in which the metallic material, after being subjected to a chemical treatment, is first coated with primer and then with a top-coat. The thus prepared precoat metals have been widely used in various areas, including construction materials, and therefore, are required to have higher order of weathering resistance, corrosion resistance, processability, water resistance or the like. Especially, the abovesaid primer coating should have excellent adherence to both substrate and top-coat, as well as improved processability, corrosion resistance, water resistance, chemical resistance and the like.

Heretofore, as a primer paint, use has generally been made of a heat curing type composition comprising as principal components an expoxy resin of the formula:

(wherein n is O or an integer of 1 to 14) and amino resin and/or blocked isocyanate compound.

Such composition can provide a tough coating with improved corrosion resistance and chemical resistance, and however, has a drawback of poor processability. For the purpose of increasing the processability, attempts have been made to use a high molecular weight epoxy resin or to use polyhydroxy-polyether-polyester obtained by the reaction of relatively lower molecular weight epoxy resin with dicarboxylic acid. However, in the former, indeed corrosion resistance and processability are improved, but additional problems are caused to occur as poor solubility in solvents and poor compatibility with other components of the coating composition. In the latter case, there are certain limitations in the selection of the hardners, because of its relatively poor compatibility with blocked isocyanate compound, and hence cannot exhibit film peformance in full in such combination.Furthermore, in the reaction of epoxy resin with dicarboxylic acid, there often occur, besides the addition reaction of glycidyl groups and carboxyl groups, side reactions, i.e. dehydrating condensation of said carboxyl groups and hydroxyl groups originally presented in the epoxy resin or newly generated by the reaction of said glycidyl groups and carboxyl groups thereby resulting the product with many branched chains.

The resinous varnish thus obtained can hardly give the desired processability and in extreme case, the varnish itself, will be gelated thoroughly.

By the adoption of decreased reaction temperature, such phenomena may be avoided, but in that case a prolonged reaction time is required, which is untolerable in commercial production of the intended product. It is, of course, possible to use a catalyst-as tertiary amine, potassium hydroxide, sodium hydroxide, quaternary ammonium salt and the like to shorten the reaction time, and however, in this time, the catalyst used may remain in the produced resin and cause the problems in water resistance and chemical resistance of the coating.

When the following type epoxy resin:

is used in place of the abovesaid resin (A), the hydroxyl groups contained in the resin and the groups newly generated by the reaction with dicarboxylic acid are all of tertiary nature.and hence, there hardly occur the dehydrating condensation of carboxyl groups and hydroxyl groups.

Therefore, the desired polyhydroxy-polyether-polyester may be comparatively stably prepared.

However the tertiary nature of the hydroxyl groups in the final resin will also give a difficult question of inferior reactivity with the functional groups of amino resin and/or blocked isocyanate compound, and therefore, a higher temperature baking is essential for the thorough crosslinking and, which is undesired from an economical and operational point of views.

Heretofore, has also been reported a.heat curing type epoxy resin for primer use (Japanese Patent Application Kokai No. 30717/82).

This resin is prepared by the interaction of (1) the reaction product of epi-bis type epoxy resin (A) and/or (B), dicarboxylic acid and secondary amine with primary hydroxyl group, and (2) the reaction product of polyisocyanate compound and isocyanate blocking agent.

The abovesaid secondary amine may act as a catalyst for the addition reaction of glycidyl group of the epoxy resin and carboxyl group of the dicarboxylic acid, thereby enabling the reaction to proceed at a lower temperature and at a higher speed, and also have the role of introducing primary hydroxyl groups in the resin, thereby facilitating the progression of crosslinking reaction when compounded with hardener.

Therefore, the coating composition based on such resin, may give combination of excellent as adherence, processability, corrosion resistance, water resistance, and chemical resistance, and is quite useful for metallic materials.

However, with the diversification of needs, the appearance of primer paint capable of showing far improved adherance, bending property and especially corrosion resistance at processed portions has been longed for.

In a series of studies of having improved epoxy type primer coat, especially with respect tocorrosion resistance, the inventors have found that in the heat curing type epoxy resin obtained by the interaction of the reaction product of epoxy resin, dicarboxylic acid and primary hydroxy bearing secondary amine, and the reaction product of polyisocyanate compound and isocyanate blocking agent, adherence, bending property and corrosion resistance of the coating are greatly improved by the use of epoxy resin with resorcin structure as a part of said epoxy resin or by combining the abovesaid heat curing type epoxy resin with polymer resin with resorcin structure, and in a conventional type epoxy resin, corrosion resistance of the coating can be greatly improved by the inclusion of particular acid in said epoxy resin in a state capable of developing particular resinous acid value or by converting the epoxy resin to an amphoteric type through the reaction with polybasic acid and particular alkyleneimine compound. On the basis of these findings, the invention has been made.

According to the first invention, is provided a primary coating composition comprising as essential components, 5O95 parts by weight of a heat curing epoxy resin [C], prepared by the interaction of product [A] obtained by the reaction of epoxy resin component (a1) which is a mixture of 50 100% by weight of the resin: :

(wherein R is H or CH3, -A- represents > C(CH3)2, -CH2-, -O- or -S-, and n is O or an integer of 1 14) and 50~0% by weight of other epoxy resin, dicarboxylic acid (a2) and secondary amine having at least one primary hydroxy alkyl group (a3), and product [B] prepared by the reaction of polyisocyanate compound (b1) and isocyanate blocking agent (b2), the ratio of isocyanate groups in (b1) to active hydrogen atoms in (b2) being 5/15/4 and the ratio of primary hydroxyl groups contained in product [A] to free isocyanate groups contained in product [B] being 10/1 11, 50~5 parts by weight of polyether resin [D] having the repeating units of the formula::

wherein R' is

and n' is O or an integer of 1 14, and 1 30 parts by weight of crosslinking agent.

In the second invention, is provided an epoxy resin varnish for primer coating use which is prepared by the reaction of product (Al obtained by the reaction of epoxy resin component (a1) comprising 0~95% by weight of the resin represented by the formula::

(wherein R is H or CH3, -A- represents > C(CH3)2, -CH2-, -O-, -S- or -SO2-, and n is O or an integer of 1~14) and 100~5% by weight of the resin

wherein R' is

and n' is O or an integer of 1 14, dicarboxylic acid (a2) and secondary amine bearing at least one primary hydroxylalkyl group (a3), and the product [B] obtained by the reaction polyisocyanate compound (b,) and isocyanate blocking agent (b2), the ratio of isocyanate groups in (b1) to active hydrogen atoms in (b2) being 5/1~5/4, and the ratio of primary hydroxyl groups in product [A] to free isocyanate groups in product [B] being 10/1~1.1.

The invention also provides a resinous composition comprising polybasic acid modified epoxy resin or a mixture of such modified epoxy resin and unmodified epoxy resin, the said polybasic acid showing a midpoint potential of more than -300mV in non-aqueous potentiometric titration, under state capable of developing resinous acid value, and the resinous acid value based on said polybasic acid in final resin being 0.1~50.

The invention further provides a resinous composition containing at least part of resinous components an amphoterized epoxy resin obtained by reacting an epoxy resin with a polybasic acid and then an alkylene mine compound having at least one C2~3 alkylene mine ring, the amount of said alkylene imine compound being equivalent to a resinous acid value of 0.1 20 and the resinous acid value being 0.1 30.

In the first invention, the heat curing epoxy resin stated in Japanese Patent Application Kokai No. 3071/82 is used as it is. That is, the said epoxy resin can be prepared by the interaction of product [A] which is obtained by the reaction of (a1) epoxy resin component which is a mixture of 50~100% by weight of epoxy resin represented by the formula

(wherein R is H or CH3, -A- represents > C(CH3)2, -OH2, -O-, -S- or -SO2-, and n is O or an integer of 1 14), and 50~0% by weight of other epoxy resin, (a2) dicarboxylic acid and (a3) secondary amine having at least one primary hydroxyalkyl group, and product [B] which is obtained by the reaction of (b1) polyisocyanate compound and (b2) isocyanate blocking agent, the ratio of isocyanate groups in (b1) to active hydrogen atoms in (b2) being 5/1 5/4, and the ratio of primary hydroxyl groups in product [A] to free isocyanate groups in product [B] being 10/1~1/1.

As the epoxy resin component (a1), the resin of the aforesaid formula may be used alone.

Examples of such epoxy resins are commercialized Epotohto YD-017, YD-014, YD-01 1, YD-128 (Trade Mark, manufactured by Toto Kasei K.K.), Epicron 4050 (Trade Mark, manufactured by Dainippon Ink Chem. Ind. Ltd.) and the like. The said resin component (a1) may further include other epoxy resin (e.g. polyalkyleneglycoldiglycidylether and the like) in an amount of less than 50% by weight of the total epoxy resin. If the amount of said additional resin exceeds over 50% by weight of the epoxy resin component (a,), there shows a tendency to decrease in the desired properties as corrosion resistance, water resistance, adherence chemical resistance, hardening property and the like.

Examples of said dicarboxylic acid component (a2) are polymethylenedicarboxylic acids (e.g.

adipic acid, azelaic acid, sebacic acid and the like), aromatic dicarboxylic acids (e.g. phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid and the like), dimer acid, polybutadiene dicarboxylic acids, polyester dicarboxylic acids and the like.

One or combination of two and more of these acids may be used as component (a2), and however, special preference is given to polymethylene dicarboxylic acids and especially azelaic acid because of resulting resinous material with excellent processability, solubility and compatibility and the like.

Trivalent carboxylic acids may be caused with the said a2 component, if desired.

In the present invention, the abovementioned seconary amine (a3) has the role of catalyst which proceeds with the reaction between a, and a2 components, i.e. addition reaction between glycidyl group and carboxyl group, at a lower temperature and at a higher speed.

Furthermore, primary hydroxyl group can be introduced into the resin through the reaction ofi the -NH moiety with glycidyl group, which is very important for the crosslinking reaction of the coating. Also, the nitrogen incorporated into the resinous structure may act as an effective catalyst for the curing reaction.

Examples of such secondary amines are dialkanolamines (e.g. diethanolamine, dipropanolamine, dibutanolamine and the like), and alkylalkanolamines (e.g. ethylethanolamine and the like). These amines are used singularly or combination of two and more. Particularly preferable amines are' dialkanolamines and especially ethanolamine.

The product [A] may be obtained by the reaction of the abovesaid epoxy resin component (a,) with dicarboxylic acid (a2) and secondary amine (a3). The reaction rates of the respective components are, usually selected so that the rate of [gram equivalent of glycidyl group in (a1)- gram equivalent of carboxyl group in (a,)] to [total weight (g) of (a,)+(a2)+(a3)] is less than 7 x 10-4 gram equivalent/gram, preferable 4x 10- 40.3x 104 gram equivalent/gram, and the rate of [gram equivalent of carboxyl group in (a2)+gram equivalent of amino group in (a3)]/[gram equivalent of glycidyl group in (a1)1 is 4/5--6/5, preferable 9/10~23/20.

If the former rate exceeds over 7x 10 4 gram equivalent/gram, there is a trend that a sufficient processability cannot be obtained. If the latter rate is lower than the lowest limit of 4/5, there is a trend that a sufficient heat curing cannot be obtained and furthermore if it exceeds over the upper limit of 6/5, unreacted dicarboxylic acid or secondary amine will be remained in the product, thereby causing inferior water resistance and chemical resistance of the coating.

In carrying out the reactions of al~a3 components, it is generally recommended that a, component is first melted or dissovled in an appropriate inert solvent, and a2 and a3 components are added and the mixture is reacted under nitrogen gas stream at 80--200"C for 1 15 hours.

At this time, the secondary amine (a3) can exhibit the role of esterification catalyst for the reaction between a, and a2 components, and therefore, preference is given to the reactions under the condition that the abovesaid three components are co-existing with each other.

The product [B] used in the present invention can be obtained by the reaction of polyisocyanate compound (bl) and isocyanate blocking agent (b2) in the ratio of isocyanate groups in (b,) to active hydrogen atoms in (b2) of 5/15/4. This reaction is usually carried out, with or without using solvent, at a room temperature --150"C, and however, it is generally preferred for the control of product quality and reaction rate that (b,) component is first disolved in an inert solvent and the solution is heated to 50--100"C and then added dropwise with (b2) component or its solution to proceed with the reaction.

As the abovesaid polyisocyanate compound (b,), mention is made of aliphatic or alicyclic diisocyanate compounds (e.g. hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate and the like), aromatic diisocyanate compounds (e.g. tolylenediisocyanate, diphenylmethane-4-4'-diisocyanate and the like), and triisocyanate compounds are aliphatic or alicyclic diisocyanate compounds because of resulting excellent solubility, compatibility and processability.

The abovesaid isocyanate blocking agent (b2) must be the member capable of reacting with isocyanate group of b, component to give the product which is stable at a room temperature, but will decompose at an elevated temperature of 140-250"C, thereby regenerating free isocyanate group.

Examples of such protective agents (b2) are lactam series agents (e.g. e-caprolactam, ybutyrolactam and the like), oxim series agents (e.g. methyl ethyl ketoxin, cyclohexanone oxim and the like), alcoholic agents (e.g. methanol, ethanol, isobutyl alcohol and the like), phenolic agents (e.g. phenol, p-t-butyphenol, cresol and the like).

The product [B] to be obtained by the reaction of b1 and b2 components may be the mixture of completely blocked polyisocyanate compound, partly blocked polyisocyanate compound and unblocked polyisocyanate compound. Among them, the completely blocked polyisocyanate compound may act as a crosslinking agent at the time. of film forming stage of the present heat curing type resin.

The polyisocyanate compound having one free isocyanate and one and more of blocked isocyanate groups may undergo addition to the product [A] and can exhibit the role of crosslinking functional groups at the film-forming stage.

The polyisocyanate compound having 2 and more free isocyanate and 1 and more blocked isocyanate groups may act the role of growing chain of the product [A] and also of adding crosslinking functional group. The unblocked polyisocyanate compound can act the role of growing chain of the product [A], thereby increasing the molecular weight and introducing the main chain urethane bondings.

In the present invention, the abovesaid product [A] and product [B] are reacted to give the desired heat curing epoxy resin. At this time, the reactants are selected so that the rate of primary hydroxyl groups contained in product [A] to free isocyanate groups contained in product [B] is in a range of 10/1--1/1, preferable 5/1--5/4.

The abovesaid reaction is usually carried out under nitrogen gas-at a temperature of 50 1 500C until the isocyanate groups are substantially disappeared. If desired, the reaction may be stopped at the stage where a certain amounts of isocyanates are still remained but the desired molecular weight has been attained, by, for example, adding primary alcohol to the reaction system.

With the abovesaid urethane modified epoxy resin, the invention is characterized by using polyhydroxy-polyether resin having the repeating unit of the formula:

wherein n' has the meaning as previously defined.

The said resin may be easily prepared by reacting resorcin or mixture of resorcin and bisphenol A with epihalohydrine in the presence of catalyst or reacting diepoxide, derived from resorcin or bisphenol A and epihalodydrine, with resorcin in the presence of catalyst (see-Japanese Patent Application No. 179934/80) or easily available in the market, as, for example, ESRP-250, ESAR-004, ESAR-007, ESRA-004 and the like (Trade Marks, manufactured by Sumitomo Chem.

Co., Ltd.).

In the present invention, 50--95 parts by weight of the abovesaid urethane modified epoxy resin are combined with 50--5 parts by weight of the said polyhydroxy-polyether resin. If the latter is less than 5 parts by weight, it is unable to attain the improvements in adherence at the processed portions and bending property. Furthermore, no satisfactory corrosion resistance at the processed portions can be attained.

The crosslinking agents used in the invention are of conventional type having functional groups capable of reacting with hydroxyl groups in said epoxy and polyether resins.

Examples of the crosslinking agents are melamine-formaldehyde resin, phenol-formaldehyde resin, urea-formaldehyde resin, polyisocyanate, blocked polyisocyanate and the like. Such agents are generally used in an amount of 1 30 parts by weight, and however, may vary in considerably wider range, depending on the curing degree desired.

In formulating a coating composition, the abovesaid components are merely mixed together in each defined rate, and no particular operations are required therefor.

In the second aspect of the invention, is provided a heat curing type epoxy resin varnish, being useful as resinous binder in a primer coating composition with improved corrosion resistance, which is prepared by the reaction of product [A'] obtained by the reaction of (a1) epoxy resin component composed of 0~95% by weight of epoxy resin of the formula:

wherein R is H or CH3, -A- represents > C(CH3)2, -O-, -S- or -SO2-, and n is 0 and 100~5% by weight of epoxy resin of the formula::

wherein R' is

and n' is O or an integer of 1 14, (a2) dicarboxylic acid, and (a3) secondary amine having at least one primary hydroxyalkyl group, and product [B]' obtained by the reaction of (b,) polyisocyanate compound and (b2) isocyanate blocking agent, the ratio of isocyanate groups in (b,) to active hydrogen atoms in (b2) being 5/1 5/4 and the ratio of primary hydroxyl groups in product [A1 to free isocyanate groups in product [B]' being 10/1 1/1.

In the first invention, resorcin type of bisphenol A-resorcin alternating co-condensation type unit structure is incorporated into the coating composition in the form of separate polyether resin to be blended with the epoxy resin.

However, in the second invention, such characteristic unit structure is incorporated into a part of the epoxy resin itself. Thus, in the second invention, the epoxy resinous component (a,) is composed of 0~95% by weight of epoxy resin of the formula (epibis-type epoxy resin).

and 100 5% by weight of epoxy resin of the formula (resorcin type or resorcin-epibis alternating type epoxy resin)

As to the epibis-type epoxy resin, dicarboxylic acid (a2), secondary amine (a3), polyisocyanate compound (b,) and isocyanate blocking agent (b2) components, the very similar members as stated previously in connection with the first invention are satisfactorily used.

Examples of the resorcin type or resorcin-bisphenol A alternating type epoxy resins, are ESAR004, ESAR-007, ESRA-004, ESR-004, ELR-130 (Trade Marks, manufactured by Sumitomo Chem.

Co., Ltd).

The invention has been made on the basis of the finding that the very similar improvement in correction resistance of the heat curing type epoxy resin varnish can be attained even when the resorcin structure is incorporated into the epoxy resin itself, in place of polyether resin to be blended with said epoxy resin.

The final object of the invention is, already stated, to provide a primer coating composition capable of showing extremely improved corrosion resistance and especially corrosion resistance at the processed portions.

In the first and the second inventions, the said object has been attained by providing heat curing type epoxy resin and incorporating into the resinous varnish the resorcin structure in the form of separate polyether resin and in the form of particular epoxy resin.

The inventors have further continued studies and have surprisingly found that the same object could be attained without the necessity of making a particular heat curing type epoxy resin anew and by merely modifying the conventional epoxy resin with a particular acid or converting the same to amphoteric type resin.Thus, in the third aspect of the invention, is provided an epoxy resinous varnish being useful as a resinous vehicle for primer coating composition with improved corrosion resistance, which comprises polybasic acid modified epoxy resin or a mixture of such modified epoxy resin and unmodified epoxy resin, the said polybasic acid showing a titration midpoint potential of more than300mV in non-aqueous potentiometric titration, under state capable of developing resinous acid value, and the resinous acid value based on said polybasic acid in the final resin being 0.1 50.

In the fourth aspect of the invention, is provided an epoxy resinous varnish being useful as a resinous vehicle for primer coating composition with improved corrosion resistance, which comprises, as at least part of resinous components, an amphoterized epoxy resin obtained by reacting an epoxy resin with a polybasic acid and then with an alkyleneimine compound having at least one C2~C3 alkyleneimine ring, the amount of said alkyleneimine compound being equivalent to a resinous acid value of 0.1 20, and the resinous acid value being 0.1 30.

In the present specification and claims, the term "under the state capable of developing resinous acid value" denotes a polybasic acid under the state being incorporated into the resin.

The term "non-aqueous potentiometric titration" means "potentiometric titration wherein the test resin is dissolved in non-aqueous solvent and n-tetra-butylammonium hydroxide (TBAH) is used as titration reagent." The term "epoxy resin" shall mean "epoxy resin obtained by the reaction of compound having phenolic hydroxyl group and epihalohydrine, and modified epoxy resins obtained by the reactions of said epoxy resin with polybasic acid, polyhydric alcohol, amine, isocyanate compound and the like.". As is well known, epoxy resin has both epoxy groups and hydroxyl groups being of great polarity- and distributed at a defined distance throughout the molecular chain. Therefore, when reacted with acid or acid anhydride, the said acid component may be incorporated into the resin through the reaction with said epoxy and hydroxyl groups.If a polybasic acid is used as the said acid, free carboxyl groups derived from said polybasic acid may be introduced in the resin and resinous acid value wouid be developed therefrom.

In the present invention, as the polybasic acid to be reacted with epoxy resin, use is made of such member as having a titration midpoint potential of more than -300 mV in a non-aqueous potentiometric titration under the state capable of developing resinous acid value.

When a potential -TBAH titer curve of a polybasic acid is made from the results of its nonaqueous potentiometric titration, there shows a plural number of inflection points depending on the typeof the acid used. However, at the state when the acid is incorporated into a resin by ester bonding, since there remains at last one free carbonyl group, the said inflection points will naturally lose in member, accordingiy.

In this invention, the polybasic acid to be used and incorporated into a resin must be of such acidity that the titration midpoint potential in non-aqueous potentiometric titration is. more than -300 mV, under the state of being incorporated into the resin.

Examples of such polybasic acids are phthalic anhydride, isophthalic acid, pyromellitic acid, pyromellitic anhydride, trimellitic acid, trimellitic anhydride, tetrachlorophthalic anhydride, tetrabromophthacid acid, Het acid, Het anhydride and the like.

The inventors have found that if the abovesaid epoxy resin modified with a particular acid is included as at least part of the epoxy resinous component and if the resinous acid value based on the carboxyl groups of the abovesaid particular polybasic acid incorporated into the resin is in a range of 0.1--50, preferable 0.1--20, and most preferably 0.1--10, in a whole resinous composition, corrosion resistance of the cured epoxy coating can be markedly improved.

The invention has been made on the basis of this finding. That is, in a resinous composition containing as the sole epoxy resin component the abovesaid acid modified resin, the amount of said polybasic acid to be incorporated into the resin should be as much as being sufficient to give the resinous acid value of 0.15O. Whereas, in a resinous composition containing a mixture of unmodified and modified epoxy resins, the amount of said polybasic acid for modification use is substantially larger than the level required for giving the resinous acid value of 0.1--50 and in this invention, it is essential that as the whole resinous components, the resinous acid value based on the carboxyl group of said particular polybasic acid should be in range of 0.1 50. If the said resinous acid value is deficient to the lowest limit of 0.1, there is no substantial improvement in the corrosion resistance, whereas at an excessively larger level of more than 50, there is a trend that undesirable effects will come out on water resistance, chemical resistance or the like.

In the fourth invention, an epoxy resin is converted to amphoteric type resin by the reaction with polybasic acid and then with alkyleneimine compound having at least one Cz~C3 alkyleneimine ring.

However, in this case, the content of alkylene imine compound should be in a level corresponding to resinous acid value of 0.120 and the resinous acid value of the composition should be in a range of 0.1 30.

If the alkyleneimine content is less than the level being equivalent to resinous acid value of 0.1, the object of the invention, i.e. improvement in corrosion resistance, cannot be attained, whereas, if it exceeds over the level being equivalent to resinous acid value of 20 and/or if the resinous acid value exceeds over the upper limit of 30, undesirable effects are appeared on weather resistance, water resistance and the like and improvement in corrosion resistance cannot be attained.

The present resinous varnishes as defined, in the second to the fourth inventions are usually combined with aminoplast or isocyanate compound to formulate the coating compositions, which are especially useful as primer coating with improved corrosion resistance.

The invention shall be now more fully explained in the following examples. Unless otherwise being stated, parts and percentages are all by weight.

Synthetic Example 1 784 Parts (parts by weight hereinafter the same) of Epotohto YD-017 (Trade mark epoxy resin manufactured by Toto Kasei K K., epoxy equivalent 1960) were dissolved in a mixture of 78.4 parts of xylene and 196 parts of Cellosolve acetate and the mixture was added with 25.1 parts of azelaic acid and 13.3 parts of diethanolamine and reacted at 140"C under nitrogen atmosphere for 4.5 hours. At the stage when the acid value of the resin reached to 1.2 KOH mg/g 314 parts of xylene and 245 parts of methylethyl ketone were added and the mixture was allowed to cool to obtain product A;1.

In a separate vessel were placed 375 parts of Cellosolve acetate, 224 parts of hexamethylene diisocyanate and 151 parts of e-caprolactam, and the mixture was reacted at 100 C for 3 hours to obtain product B-l having an isocyanate equivalent of 562 9.

Next, to the product A-1, 75.0 parts of the product B-1 and 263 parts of xylene were added and the mixture was reacted under nitrogen gas stream at 100"C for 3 hours. At this stage it was found that isocyanate absorption was disappeared in an infrared absorption analysis, and therefore the mixture was added with 194 parts of methylethyl ketone and allowed to cool to obtain a heat curing type resinous solution.

Synthetic Example 2 475 parts of Epotohto YD-014 (Trade Mark, epoxy resin manufactured by Toto Kasei K.K., epoxy equivalent 950) were dissolved in a mixture of 95 parts of xylene and 119 parts of Cellosolve acetate and the mixture was added with 39.2 parts of azelaic acid and 8.3 parts of diethanolamine and reacted at 145"C for 6 hours. At the stage when the resinous acid value reached to 1.1 KOH mg/g, 209 parts of xylene and 130 parts of methyl ethyl ketone were added and the mixture was allowed to cool to' obtain product A-2.

In a separate vessel, were added 222 parts of isophoron diisocyanate and 222 parts of Cellosolve acetate and the mixture was heated to 80"C. Thereafter, a solution of 113 parts of caprolactam and 113 parts of Cellosolve acetate was dropped in over 1 hour. After completion of said addition, the reaction was continued at 80"C for additional 3 hours to obtain product B-2 whose isocyanate equivalent was 670 9.

Next, to the product A-2, 55.9 parts of the product B-2 and 118 parts of Cellosolve acetate were added and the mixture was reacted at 100"C for 3 hours. Then 127 parts of isopropyl alcohol were added and the mixture was allowed to cool to obtain a heat curing type resinous solution.

Synthetic Examples 3 to 6 The same procedures as stated in Synthetic Examples 1 to 2 were repeated excepting using the materials shown in the following Table 1. Heat curing type resinous solutions (non-volatile content 40%) were obtained.

Examples 1 to 6 To each 200 parts of the heat curing type resinous solutions stated in Synthetic Examples 1 to 6, were added 100 parts of ESRP-250 (polyether resin solution, solid content 20wt%. Trade mark, manufactured by Sumitomo Chemical Co. Ltd.). To them each 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate were added and the mxitures were kneaded well with three rolls mill. Finally, 10 parts of Cymel 303 (methoxy methylated melamine, manufactured by ACC) were added to obtain primer coating compositions.

Comparative Examples 1 to 2 and Examples 7 to 8 Using the materials shown in Table 1, the same procedures as stated in Example 1 were repeated to obtain primer coating composition respectively.

Example 9 To heat curing type resinous solution of Synthetic Example 1, ESRP-250 was added. Then rutile type titanium dioxide and strontium chromate were added and the mixture was kneaded well with three rolls mill. Finally, urea-formaldehyde resin (Beckamine G-1850, manufactured by Dainippon Ink K.K., non-volatile content 60%) were added to obtain a primer coating composition.

Example 10 To 200 parts of heat curing type resinous solution obtained in Synthetic Example 1, were added 100 parts of ESRP-250 and then 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate and the mixture was kneaded well in three rolls mill. 10 Parts of isophorone diisocyanate blocked with e-caprolactam were added thereto to obtain a primer coating composition.

Examples 11 to 12 The same procedures as stated in Example 10 were repeated excepting using methoxymethylated melamine in each amount indicated in Table 1 to obtain primer coating compositions.

Test results The primer coating compositions stated in Examples 1 to 12 and Comparative Examples 1 to 2 each was applied under conditions mentioned below and thus obtained coatings were evaluated as follow: Substrate: Zinc phosphate pre-treated galvanized steel plate Primer baking condition: 210"cox45 sec.

Primer thickness: 8 microns Top coat baking condition: 210"cox60 sec.

Top coat thickness: 15 microns For the said top coat, commercially available coil coating composition was used and for the evaluation of corrosion resistance at the processed portions, was used a method wherein 4T bended sample was salt sprayed for 200 hours and then subjected to tape peeling test. The results are shown in Table 1. In that Table.

Note 1: Epotohto YD-01 1 and YD-128 are epoxy resins manufactured by Toto Kasei K.K., epoxy equivalent 476 and 188 respectively Note 2: Dimer acid (carboxyl equivalent 289) Note 3: Pencil scratching test by a standardized JIS-K5400 method Note 4: Cross-cut test by a standardized JIS-5400 method

10U/100 - 95/100 94/lox - 80/10U 79/100 - 60/100 59/100 - 0/100 Note 5: Tape peeling test at the bended portion

no peeling at all slight peeling almost one half peeling almost complete peeling Note 6: Test piece was cutted-in to the substrate and subjected to salt spraying by using salt sprayer (JlS-Z-237 1) for 500 hours. Thereafter, tape peeling test was carried out at the cut-in portion.

width of peeling

O - 1.0 mm 1.1 - 2.0 mm 2.1 - 3.0 mm more than 3.1 mm Note 7: 4T bended test piece was salt sprayed by JlS-Z-237 1 for 200 hours and then subjected to tape peeling test

no peeling slight peeling almost one half peeling almost complete peeling Table I

Exaiple 1 2 3 heat curing resin (Synth. Example No) 1 2 3 Resinous conposition Epotobto YD-017 784 (5) 784 (5) ibid -014 475 (5) ibid -011 *1 ibid -128 dibasic acid azelaic acid azelaic acid sebacic acid its anount 25.1 (3.34) 39.2 (4.17) 27.0 (3.34) diethanolanine 13.4-(I.6 ) 8.3 (0.8) 13.4 (1.6) (B-I) 75.O.(1.66) 75.0 (1.66) (B-2) 55.9 (0.83) coating coiposition heat curing resin. sal. 200 209 200 hydroxypolyether res. sal. 100 100 100 solid ratio of heat cur. resin /hydroxy 80/20 80/20 80/20 polyether resin crosslinking agent Cy.el-303 Cyiel-303 Cyael-303 cross-cut tape peeling *4 0 bend, tape peeling *5 IT 0 0 0 2T 0 0 0 salt spray test 500 brs tape peeling at cross-cut portion *7 0 0 0 200 hrs tape peeling at bend. portion *8 0 0 0 all figures are parts by weight. ( ) shovs euqivalent ratio Table 1 (continued)

Exanple 4 5 6 heat curing resin (Synth. Example No) 4 5 6 Resinous coiposition Epotohto VD-017 ibid -014 29e5 (5) ibid - 011 *1 476 (5) ibid -128 245 (5) dibasic acid azelaic acid azelaic acid diner acid*2 its anount 1 86 (4.57) 117 (4.77) 75 (4.18) dietbanolanine 8.3 (0.30) 6 (0.22) 5.2 (0.80) (8-1) 66.2 (0.45) (8-2) 44.7 (0.26) 39 (0.94) coating coiposition heat curing resin. sol. 200 200 200 bydroxypolyether res. sol. 100 100 100 solid ratio of heat cur. resin /hydroxy 80/20 80/20 80/20 polyether resin crosslinkinr aeent Crel - 303 Cyel - 303 Cyrel - 303 itJ aount 10 10 10 total resin/crosslink. aent 100/10 iooilo 100/10 Test results pencil hardneJa $3 26 20 26 pencil h3rdness * 3 2 H 2 H 2 H cross-cut tape peeling *4 0 bend. tape peeling *5 1T O 0 0 2T 0 0 0 salt spray test 500 hrs tape peeling at cross-cut portion *7 0 0 0 200 hrs tape peeling at bend. portion * 0 0 0 all figures are parts by weight. ( ) shows euqivalent ratio Table 1 (continued)

Example Co.p.Ex. I 7 8 heat curing resin (Synth. Example No) 1 1 1 Resinous coiposition Epotohto YD-017 784 784 784 ibid -014 ibid -011 *1 ibid -128 dibasic acid azelaic acid azelaic acid azelaic acid its amount 25.1 25.1 25.1 diethanolaiine 13.4 13.4 13.4 (B - 1) 75.0 75.0 75.0 (5- 2) coating composition heat curing resin. sol. 240 230 140 hydroxypolyether res. sol. 20 40 220 solid ratio of heat cur. resin /hydroxy 96/ 4 92/ 8 56/44 polyether resin crosslinking agent Cyiel-303 Cyiel-303 Cyael - 303 its aiount 10 10 10 tbtal resin/crosalink. aent 100/10 100/10 100/r0 Test results pencil hardness $3 38 38 28 cross-cut tape peeling *4 bend. tape peeling *5 1T A 0 0 2T 0 0 0 salt spray test 500 hrs tape peeling at cross-cut portion *7 O 0 0 200 hrs tape peeling at bend. portion * x O 0 all figures are parts by weight. ( ) shows euqivalent ratio Table 1 (continued)

Example Conp.Ex. 2 9 10 heat curing resin (Syntk. Example No) 1 1 1 Resinous coiposition Epotohto VD-017 784 784 784 ibid - 014 ibid -011 *1 ibid -128 dibasic acid azelaic acid azelaic acid azelaic acid its amount 25.1 25.1 25.1 diethanolaeine 13.4 13.4 13.4 (8-1) 75.0 75.0 75.0 (8-2) coating coiposition heat curing resin. sol. 105 200 200 hydroxypolyether res. sol. 290 100 100 solid ratio of heat cur. resin /hydroxy 42/58 80/20 80/20 polyether resin crosslinking agent Cyiel-303 Becka.ine * Blocked NCO its aount 10 16.7 10 total resin/crosslink. arrent 100/10 100/10 100/10 Test result 1 pencil hsrdness 43 28 38 38 cross-cut tape peeling *4 0 bend. tape peeling *5 11 O 0 0 2T 0 0 0 salt spray test 500 hrs tape peeling at cross-cut portion *7 X O 0 200 hrs tape peeling at bend. portion * 8 0 0 all figures are parts by weight. ( ) shows euqivalent ratio * Beckamine G - 1850 Table 1 (continued)

h Exaiple 11 12 heat curing resin (Synth.~Exanplo No) 1 1 Resinous corPosition Epotohto VD-017 784 784 ibid -014 ibid -011 *1 -ibid -128 dibasic acid azelaic acid azelaic acid its amount 25.1 25.1 diethanolasine 13.4 13.4 (B - 1) 75.0 75.0 (B 2) coating coeposition heat curing resin. sol. 200 200 hydroxypolyether res. sol. ~1 100 100 so-lid ratio of heat cur. resin /hydroxy 80/20 80/20 polyether resin crosslinking agent Cyiel-303 Cyiel-303 its amount 5 25 total resin/crosslink. agent 100/ 5 100/25 Test results pencil hardness *3 3 H 2 11 cross-cut tape peeling *4 0 0 bend. tape peeling *5 lr o o 0 2r 0 0 salt spray test 500 hrs tape peeling at cross-cut portion *7 0 0 200 hrs tape peeling at bend. portion *8 0 0 all figures are parts by weight. ( ) shows euqivalent ratio Example 13 475 Parts of ESAR-004 (epoxy resin having an epoxy equivalent of 950, Trade Mark, manufactured by Sumitomo Chem. Co. Ltd.) were dissolved in a mixture of 95 parts of xylene and 119 parts of Cellosolve acetate and to this, were added 39.2 parts of azelaic acid and 8.3 parts of diethanolamine. The mixture was reacted, under nitrogen gas stream, at 1450C for 6 hours.

At the stage when the resinous acid value reached to 1.1 KOH mg/g, the mixture was added with 130 parts of methyl ethyl ketone and allowed to cool to obtain product A'- 1.

In a separate vessel, 222 parts of isophorone diisocyanate were dissolved in 222 parts of Cellosolve acetate and after heating to 80"C, a solution of 113 parts of e-caprolactam and 113 parts of Cellosolve acetate was dropwise added to the said solution over 1 hour. After compietion of said addition, the mixture was maintained at 800C and reacted for 3 hours to obtain product B'-1 having an isocyanate equivalent of 670 g.

To the said product A'-1, 55.9 parts of the product B'-1 and 118 parts of Cellosolve acetate were added and the mixture was reacted at 100 C for 3 hours. Thereafter, 127 parts of isopropyl alcohol were added and the mixture was allowed to cool to obtain a heat curing type resinous solution.

The material used for the synthesis of this resin and varnish characteristics are shown in the following Table 2.

Example 14 648 Parts of ESAR-007 (epoxy resin having an epoxy equivalent of 1620, Trade mark, manufactured by Sumitomo Chem. Co., Itd.) were dissolved in a mixture of 55.6 parts of xylee and 139 parts of Cellosolve acetate and to this was added 25.1 parts of azelaic acid and 13.3 parts of diethanolamine and the mixture was reacted under nitrogen gas atmosphere at 145"C for 8 hours. At the stage when the resinous acid value reached to 1.2 KOH mg/g, the mixture was added with 222.8 parts of xylene and 173.8 parts of methyl ethyl ketone and allowed to cool to obtain product A'-2.

Separately, to 375 parts of Cellosolve acetate, were added 224 parts of hexamethylene diisocyanate and 151 parts of e-caprolactam and the mixture was reacted at 100 C for 3 hours to obtain product B'-2 having an isocyanate euqivalent of 562-2 g.

Next, to the product A'-2, 75 parts of the product B'-2 and 263 parts of xylene were added and the mixture was reacted under nitrogen gas stream at 1000C for 3 hours. After confirming that no isocyanate absorption was detected by infra-red absorpotion analysis, the reaction mixture was added with 194 parts of methyl ethyl ketone to obtain a heat curing type resinous solution.

The materials used for the synthesis of this resin and varnish characteristics are shown in the following Table 2.

Examples 15 to 19 and Comparative Examples 3 to 5 The same procedures as stated in Example 13 were repeated excepting using the materials shown in Table 2 and various varnishes were obtained, whose characteristics are also given in said Table.

Example 20 250 Parts of heat curing type resinous solution obtained in Example 13 were added and kneaded well with 30 parts of rutiie type titanium dioxide and 25 parts of strontium charomate in a three roll mill to obtain a primer coating composition.

Example 21 300 Parts of the primer coating composition of Example 20 were added with 10 parts of isophorone diisocyanate blocked with e-caprolactam to obtain a primer coating composition.

Examples 22 to 28 and Comparative Examples 6 to 8 To each 250 parts of the heat curing type resinous solutions obtained in Examples 13 to 19 and Comparative Examples 3 to 5, 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate were added and kneaded well in a three roll mill. To each of the mixture, were added 10 parts of Cymel-303 (methoxymethylated melamine, Trade Mark, manufactured by ACC) to obtain primer coating compositions.

Thus obtained compositions were applied and evaluated as previously stated in Test 1 and the results are shown in table 2.

In said Table 2, ESRA-004, ESR-004 and ELR-130 are epoxy resins having epoxy equivalent of 950, 1000 and 130, all manufactured by Sumitomo Chemicai Co. Ltd. (Trade marks), and Epotohto YD-014, -017 and -128 are epoxy resins having epoxy equivalent of 950, 1960 and 188, all manufactured by Toto Kasei K.K., (Trade Marks). Notes 2 to 7 have the same meanings as previously stated.

Table 2

Example | 13 1 13 | 13 coating cosposition Exanple 20 21 22 Resinous couposition ESAR -004 475 (1.0) 475 475 ESAR -007 ESRA -004 ESR - 004 ELR -130 Epotohto VD-014 ibid -017 ibid -128 dibasic acid azelaic acid azelaic acid sebacic acid its amount ' 39.2 (0.83) 39.2 39.2 diethanolaaine 8.3 (0.16) 8.3 8.3 (B' - 1) 55.9 (0.17) 55.9 55.9 (B' - 2) Varnish characteristics non-volatile content % 40 40 40 varnish viscosity 22 Zz Z2 resinous (solid) acid value KOR ng/g 1.07 1.07 1.07 Test results pencil hardness *3 2 11 2 II 3 II cross-cut tape peeling *4 0 0 0 bend. tape peeling *5 1T O 0 0 2T 0 0 0 salt spray test 500 hrs tape peeling at cross-cut portion *7 I 0 O- 0 200 hrs tape peeling at bend. portion *8 0 0 0 all figures are parts by weight. ( ) shows euqivalent ratio Table 2 (continued)

14 15 Example 14 15 16 coating cosposition Example 1 23 24 25 Resinous coiposition ESAR -004 295(1.0) ESAR -007 648(1.0) 648 ESRA -004 ESR - 004 ELR -130 Epotohto YD-014 ibid --017 ibid --128 dibesic acid atelaic acid rcbacic acid diar acid t 2 1 its amount 25.1 (0.63) 27.0(0.63) 75 (0.84) diethanolaine 13.4 (0.32) 13.4(0.32) 5.2(0.16) 1 39,0(0. 19) e.-n) 75.0 (0.33) 15.0 (0.33) Varnish characteristics non --volatile cantent % 40 40 40 non - volatile content % 40 40 40 varnish viscosity Z2 Zl Z resinous (solid) acid value BOH ne/s 1.18 1.18 1.07 Test results pencil hardness *3 3 II 2 H 2 II cross-cut tape peeling *4 0 0 0 bend. tape peeling *5 1T O 0 0 21 0 0 0 salt spray test 500 hrs tape peeling at cross-cut portion *7 0 0 0 200 hrs tape peeling at bend. portion *8 0 0 0 all figures are parts by weight. ( ' ) shows euqivalent ratio Table 2 (continued)

Example 17 18 19 coating coeposition Example 26 27 28 Resinous coiposition ESAR -004 ESAR -007 ESRA -004 237.5(0.5) ESR - 004 40 (0.08) ELR 130 130 (1.0) Epotohto VD-014 237.5(0.5) 414 (0.92) ibid -017 ibid -128 dibasic acid azelaic acid azelaic acid azelaic acid its amount 39.2 (0.83) 39.2 (0.83) 89.8 (0.95) diethanolasine 8.3 (0.16) 8.3(0.16) 4.6 (0.04) ('B'-1) 26.8 (0.17) 41.4 (0.19) 6.8 (0.01) (B' - 2) Varnish characteristics non-volatile content % 40 40 40 varnish viscosity Zl Y Y - Z resinous (solid) acid value KOH ng/p 1.07 1.07 1.18 Test results pencil hardness *3 3 II 3 11 2 II cross-cut tape peeling *4 0 0 0 bend. tape peeling *5 1T 0 0 0 2T 0 0 0 salt spray test 500 hrs tape peeling at cross-cut portion * 7 0 0 200 hrs tape peeling at bend. portion *8 0 0 0 all figures are parts by weight. ( ) shows euqivalent ratio Table 2 (continued)

Coiparative Example 3 4 5 coating coiposi tion coiparatiwe Example No. 6 7 8 Resinous coiposition ESAR -004 19(0.04) ESAR -007 ESRA -004 ESR - 004 ELR- -130 Epotohto 70-014 456 (0.96) ibid -017 784 (1.0) ibid -128 188 (1;;0) dibasic acid azelaic acid azelaic acid azelaic acid its amount 39.2 (0.83) 25.1(0.63) 89.8(0.95) diethanolanine 8.3 (0.16) 13.4(0.32) 4.6(0.04) (B' - i) 55.9 (0.17) 6.8(0.01) (S' - 2) 75.0 (0.33) /Varnish characteristics I non--valatile content % ' 40 40 40 vernish viscositu X t X--Y resinous (solid) acid value 809 /g 1.07 1.18 1.18 Test results pencil hardness $3 3 3 H 3 H 2 H cross-cut tape peeling *4 0 O 0 bend. tape peeling *5 IT O A A 2T 0 0 O salt spray test 500 hrs tape peeling at cross-cut portion * 0 0 A 200 hrs tape peeling at bend. portion *8 X X X all figures are parts by weight. ( ) shows euqivalent ratio Example 29 1960 Parts of Epotohto YD-017 (Trade Mark epoxy resin having an epoxy equivalent of 1960 manufactured by Toto Kasei K.K.) were dissolved in a mixture of 816 parts of xylene and 670 parts Cellosolve acetate and the mixture was added with 270 parts of phthalic anhydride and reacted under nitrogen gas stream at 1 400C for 1 hour.At the stage when resinous acid value reached to 46 KOH mg/g, 300 parts of xylene and 445 parts of methyl ethyl ketone were added and the mixture was allowed to cool to obtain a polybasic acid modified resin solution A"- 1.

Example 30 784 Parts of Epotohto YD-017 were dissolved in a mixture of 457 parts of xylene and 375 parts of Cellosolve acetate and the mixture was added with 25.1 parts of azelaic acid and -13.3 parts of diethanolamine and reacted under nitrogen gas stream at 140"C for 5 hours. At the stage when resinous acid value reached to 1.2 KOH mg/g, the mixture was added with 10 parts of phthalic anhydride and reacted at 140"C for additional one hour to the resinous acid value of 5.5 KOH mg/g. 167 Parts of xylene and 250 parts of methyl ethyl ketone were added and the mixture was allowed to cool to obtain a polybasic acid modified epoxy resin solution A"-2.

Example 31 140 Parts of Epotohto YD-O1 1 (Trade Mark, epoxy resin having an epoxy equivalent of 450, manufactured by Toto Kasei K.K.) were dissolved in a mixture of 50 parts of xylene and 150 parts of Cellosolve acetate and the mixture was added with 75 parts of dimer acid (carboxyl equivalent 289) and 5.2 parts of diethanolamine and reacted under nitrogen gas stream at 145"C for 6 hours. -At the stage when resinous acid value reached to 1.1 KOH mg/g, 11.8 parts of tetrachlorphthalic anhydride were added and the mixture was-further reacted at 140"C for 1 hour to the resinous acid value of 12 KOH mg/g. Then, 124 parts of xylene and 70 parts of methyl ethyl ketone were added and the mixture was allowed to cool to obtain a polybasic acid modified epoxy resin solution A"-3.

Examples 32 to 34 The same procedures as stated in Examples 30 to 31, various polybasic acid modified epoxy resin solutions (solid 40%, A"-4 to A"-6) were prepared.

Comparative Example 9 475 Parts of Epotohto YD-014 (Trade Mark, epoxy resin having an epoxy equivalent of 950, manufactured by Toto Kase K.K.) were dissolved in a mixture of 113 parts of xylene and 235 parts of Cellosolve acetate and the mixture was added with 37.6 parts of azelaic acid and 10.5 parts of diethanolamine and reacted under nitrogen gas stream at 1450C for 6 hours. At the stage when resinous acid value reached to 1.1 KOH- mg/g, 280 parts of xylene and 157 parts of methyl ethyl ketone were added and the mixture was allowed to cool to obtain a modified epoxy resin solution B"- 1.

Comparative Example 10 980 Parts of Epotohto YD-017 were dissolved in a mixture of 430 parts of xylene and 352 parts of Cellosolve acetate and the mixture was added with 192 parts of trimellitic anhydride and reacted under nitrogen gas stream at 140"C for 2 hours. At the stage when resinous acid value reached to 96 KOH mg/g 156 parts of xylene and 234 parts of methyl ethyl ketone were added and the mxixture was allowed to cool to obtain a polybasic acid modified epoxy resin solution B"-2.

Example 35 225 Parts of modified epoxy resin solution B"-2 obtained in Comparative Example 9 were mixed with 25 parts of polybasic acid modified epoxy resin solution of Example 34 and kneaded well to obtain a resinous composition C"-l. The characteristics of thus obtained resinous varnish are shown in Table 3.

Example 36 E37.5 Parts of modified resin solution (B"-1) of Comparative Example 9 were mixed with 10 parts of polybasic acid modified epoxy resin solution (B"-2) of Comparative Example 10 and kneaded well to obtain a resinous composition C"-2. The characteristics of thus obtained resinous varnish are shown in Table 3.

Comparative Example 11 To 100 parts of modified epoxy resin solution B"- 1 of Comparative Example 9, 120 parts of polybasic acid modified epoxy resin solution B"-2 of Comparative Example 10 were added and kneaded well to obtain a resinous composition. The characteristics of thus obtained varnish are shown in Table 3.

Examples 37 to 42 To each polybasic aid modified epoxy resin solution obtained in Examples 29 to 34 (the used quantity being shown in Table 4), 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate were added and the mixture was kneaded well in three roll mill. Thereafter 10 parts of Cymel-303 (Trade mark, methoxy methylated malamine, manufactured by ACC) were added to obtain primer coating composition, respectively.

Comparative Example 12 To 250 parts of modified epoxy resin solution B"-1 obtained in Comparative Example 9, 30 parts of rutile type titanium dioxide and 25 parts of stontium chromate were added and the mixture was kneaded well in three roll mill. Thereafter, 10 parts of Cymel-303 were added to obtain a primer coating composition for comparison sake.

Comparative Example 13 To 200 parts of polybasic acid modified epoxy resin solution B"-2 of Comparative Example 10, 30 parts of rutile type titanium dioxide and 250 parts of strontium chromate were added and kneaded well. Thereafter, 10 parts of Cymel-303 were added to obtain a primer coating.

composition.

Example 43 225 Parts of modified epoxy resin solution B"-1 of Comparative Example 9 and 25 parts of, polybasic acid modified epoxy resin solution A"-6 of Example 34 were mixed well. To thus obtained resinous composition C"- 1, 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate were added and kneaded well in three roll mill. Next, 10 parts of Cymel-303 were added to obtain a primer coating composition.

Example 44 To the resinous composition comprising 235.7 parts of modified epoxy resin solution B"-l of Comparative Example 9 and 10 parts of polybasic acid modified epoxy resin solution B"-2 of Comparative Example 10, 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate were added and the mixture was kneaded well in three roll mill.

Next, 10 parts of Cymel-303 were added to obtain a primer coating composition.

Comparative Example 14 Using the resinous composition comprising 100 parts of B"-1 and 120 parts of B"-2, the same procedures as stated in Example 44 were repeated to obtain a primer coating composition.

Example 45 As shown in Table 4, 250 parts of polybasic acid modified epoxy resin solution of Example 30, 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate were mixed and kneaded well in three roll mill. To this, were added 16.7 parts of Beckamine G-1850 (ureaformaldehyde resin, manufactured by Dainippon Ink K.K., non-volatile content 60%) to obtain a primer coating composition.

Examples 46-48 Using the same procedures as stated in Example 45 but substituting Beckamine G-1850 for 10 parts of isophoron diisocyanate blocked with e-caprolactam, 5 parts of Cymel-303 and 25 parts of Cymel-303, primer coating compositions were prepared, respectively.

Test-3 The thus obtained coating compositions of Examples 37 to 48 and Comparative Examples 12 to 14 was applied on zinc phosphate treated galvanized steel plate, coated with top-coat and evaluated as in Tests 1 and 2. The results are shown in Table 4.

Table 3

Example 29 30 31 Name of resinous composition | A"-1 | A"-2 | A"-3 Resinous coiposition Epotohto YD-017 1960 (1) 784 (1) YD-014 YD-011 140(1) ESAR -007 * 1 ESAR -004 * 1 ESR -004 * 1 dibasic acid azelaic acid diner acid its amount *2 25.1 (0.67) 75 (0.83) diethanolamine 13.3 (0.32) 5.2 (0.16) polybasic acid phthal. anhyd. phthal. anhyd. tetrachloro- phthal. anhyd.

its amount 270 (3.64) 10 (0.34) 11.8 (0.25) Varnish characteristics non-volatile content % 50 40 40 varnish viscosity Z ZI Z resinous (solid) acid value KOH mg/g 46 5.5 12 all figures are parts by weight. ( ) shows euqivalent ratio * 1 ...ESAR-007, ibid-004 and ESR-004, epoxy resins having epoxy equivalents 1640, 950 and 1000, respectively.

Trade Marks, manufactured by Sumitomo Chemical Co. Ltd.

* 2 ...carboxyl equivalnet 289 * 3 ...measured by Gardner's viscometer (25 C) Table 3 (continued)

Example ~ 32 33 34 Name of resinous composition A"-4 A"-5 A"-6 Resinous composition Epotohto YD-017 YD-014 437 (0.92) YD-011 ESAR - 007 *1 648 (1.0) ESAR -004 * 1 475 (1) ESR -004 40 (0.08) dibasic acid sebacic acid azelaic acid azelaic acid its a amount * 2 27 (0.63) 37.6 (0.8 ) 37.6 (0.8 ) diethanolamine 13.3(0.32) 10.5 (0.2 ) 10.5 (0.2 ) polybasic acid phthal. anhyd. phthal. anhyd. phthal. anhyd.

its amount 20 (0.68) 5 (0.14) 5 (0.14) Varnish characteristics non-volatile content % 40 40 40 varnish viscosity Z2 Z1 Z2 resinous (solid) acid value KOH mg/g | 11 | 3.6 | 3.6 all figures are parts by weight. ( ) shows euqivalent ratio *1 ...ESAR-007, ibid-004 and ESR-004 , epoxy resins having epoxy equivalents 1640, 950 and 1000, respectively.

Trade Marks, anufactured by Sumitomo Cheiical Co. Ltd.

Example Comp. Ex. 9 Comp. Ex. 10 35 Name of resinous composition B"-1 B"-2 C"-1 Resinous composition Epotohto VD-017 980 (1) YD - 014 475 (1) 25 parts of YD-011 | | | A"-6 ESAR - 007 * 1 and ESAR - 004 * 1 225 parts ESR -004 * 1 | | | of B"-1 dibasic acid azelaic acid its amount *2 37.6(0.8 ) diethanolamine | 10.5(0.2) polybasic acid trinellitic ; anhydride its anount 192 (6) Varnish characteristics non-volatile content % 40 50 40 varnish viscosity Y Z1 Z resinous (solid) acid value KOH g/g 1.1 92 1.50 all figures are parts by weight. ( ) shows euqivalent ratio * 1 ...ESAR-007, ibid-004 and ESR-004, epoxy resins having epoxy equivalents 1640, 950 and 1000, respectively.

Trade Marks, nanufactured by Sumitomo Chenical Co. Ltd.

Example 36 Comp. Ex. 11 Name of resinous composition C"-2 C"-3 Resinous composition Epotohto YD-017 237.5 parts 100 parts YD-014 of B"-1 of B--i YD-011 | and | and ESAR - 007 * 1 10 parts 120 parts ESAR -004 * 1 of B"-2 of B"-2 ESR -004 * 1 dibasic acid its amount * 2 diethanolamine polybasic acid its amount Varnish characteristics non-volatile content % 40.4 45.5 varnish viscosity Y Z resinous (solid) acid value KOH mg/g 5.6 55.6 all figures are parts by weight. ( ) shows euqivalent ratio * 1 ...ESAR-007, ibid-004 and ESR-004, epoxy resins having epoxy equivalents 1640, 950 and 1000, respectively.

Trade Marks, ianufactured by Sullitollo Chemical Co. Ltd.

* 2 ...carboxyl equivalnet 289 * 3 ...measured by Gardner's viscometer (25 C) Table 4

Example 37 38 39 foreulation of coating coiposition polybasic acid modified epoxy resin solution ~L bn-l A*-2 A"-3 its aiount 200 250 250 amount of 8"--1 solid ratio of polybasic acid modified epoxy resin / B"-1 resinous acid value based on the polybasic acid 46 5.5 12 crosslinking agent Cyeel 303 Cyiel 303 Cynel 303 its aiount 10 10 10 solid ratio of resinous coip./crosslink.agen 100/10 100/10 100/10 Test results pencil hardness * 1 3 11 2 H 2 11 cross-cut tape peeling *2 0 0 0 bend. tape peeling *3 2? X O 0 4T A 0 0 salt spray test *4 700 hrs tape peeling at cross-cut portion 0 O 0 *1.. JIS-K-5400 standard pencil scratch test * 2..JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree #.. no peeling 0.. slight peeling A about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 4 (continued)

Exaiple 40 41 42 fornulation of coating cosposition polybasic acid modified epoxy resin solution A"-4 A"-5 A"-6 its amount 250 250 250 amount of B"-1 solid ratio of polybasic acid modified epoxy resin / 8"-1 resinous acid value based on the polybasic acid 11 3.6 3.6 crosslinking agent Cyiel 303 Cysel 303 Cyiel 303 its. amount . 10 10 10 solid ratio of resinous conp./crosslink.agen 100/10 100/10 100/10 Test results pencil hardness * 1 2 H 2 II 2 11 cross-cut tape peeling *2 0 0 0 bend. tape peeling *3 2T 0 0 0 4T 0 0 0 salt spray test *4 700 hrs tape peeling at cross-cut portion ~~ 0 O O *1.. JIS-K-5400 standard pencil scratch test * 2..JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #..79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree #.. no peeling 0.. slight peeling #..about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours 0.. (peeled width) 0 - 1.0 mm #...1.1 - 2.0 ii #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 4 (continued)

Example Coax. Ex.12 Coax. Ex. 13 43 foraulation of coating coiposition polybasic acid modified epoxy resin solution B"-2 A"-6 its amount 200 25 amount of 8"--1 250 225 solid ratio of polybasic acid modified epoxy resin / B"-1 0/100 10/90 resinous acid value based on the polybasic acid O 92 0.36 cross linking agent Cyiel 303 Cyael 303 Cynel 303 its aiount 10 1 10 10 solid ratio of resinous coip./crosslink.agen 100/10- 100/10 100/10 Test results pencil hardness * 1 H 3 H 2 H cross-cut tape peeling *2 O x O bend. tape peeling *3 2T O X O 47 O X O salt spray test * 4 700 hrs tape peeling at cross-cut-portion X x X * 1.. JIS-K-5400 standard pencil scratch test *2.. JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree #.. no peeling 0.. slight peeling #..about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 4 (continued)

Example 44 Coax. Ex. 14 45 foriulation of coating coiposition polybasic acid modified epoxy resin solution B"-2 8"-2 A!P-2 its amount 10 120 250 amount of 8"-1 235.7 100 solid ratio of polybasic acid modified epoxy resin / B"-1 5/ 95 60/40 resinous acid value based on the polybasic acid 4.6 55.2 12 crosslinking agent Cyiel 303 Cyiel 303 Beckseine G-1850 its amount 10 10 16.7 solid ratio of resinous corp./crosslink.agent 100/10 100/10 100/10 Test results pencil hardness *1 2H 3 H 2 H cross-cut tape peeling *2 0 X O bend. tape peeling *3 2T O X O 4T 0 A 0 salt spray test *4 700 hrs tape peeling at cross-cut portion 0 X O * 1..JIS-K-5400 standard pencil scratch test *2.. JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #..79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree #.. no peeling 0.. slight peeling #..about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 4 (continued)

Example 46 47 48 fornulation of coating composition polybasic acid modified epoxy resin solution A"-2 A"-2 A"-2 its amount 250 250 250 amount of B"-i solid ratio of polybasic acid modified epoxy resin / B"-1 resinous acid value based on the polybasic acid 12 12 12 crosslinking agent Blocked NCO Cynel 303 Cynel 303 its amount 10 5 25 so lid ratio of resinous conp./crosslink.agent 100/10 100/ 5 100/25 Test results pencil hardness * 1 2 H 3 H 2 H cross-cut tape peeling * 0 0- 0 bend. tape peeling *3 2T 0 0 0 4T 0 0 0 salt spray test *4 700 hrs tape peeling at cross-cut portion 0 0 9 * 1.. JIS-K-5400 standard pencil scratch test * 2..JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 X..59/100 - 10/100 *3.. tape peeled degree #.. no peeling 0.. slight peeling A about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours 0.. (peeled width) 0 - 1.0 In #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Example 49 784 Parts of Epotohto YD-017 (Trade Mark epoxy resin having an epoxy equivalent of 1960 manufactured by Toto Kasei K.K.) were dissolved in a mixture of 308 parts of xylene and 250 parts of Cellosolve acetate and the mxiture was added with 36 parts of phthalic anhydride and reacted under nitrogen gas stream at 140"C for 1 hours. At the stage when the resinous acid value reached to 16.6 KOH mg/g, the mixture was allowed to cool.Next, 16.4 parts of N-(2hydroxyethyl) ethyleneimine (HEEI trade mark of Sogo Yakko K.K.) were added and the mixture was reacted at 80"C for 1 hour and then diluted with 100 parts of xylene and 167 parts of methyl ethyl ketone and allowed to cool to obtain an amphoterized epoxy resin solution A""1.

Example 50 722 Parts of Epotohto YD-014 (Trade Mark epoxy resin having an epoxy equivalent of 950 manufactured by Toto Kasei K.K.) were dissolved in a mixture of 242 parts of xylene and 298 parts of Cellosolve acetate and the mixture was added with 71.5 parts of azelaic acid and 13.3 parts of diethanolamine and reacted at 140"C for 4 hours. At the stage when the resinous acid value reached to 5.7 KOH mg/g the mixture was allowed to cool added with 4.2 parts of HEEI reacted at 80" for 1 hour, diluted with 254 parts of xylene and 198 parts of methyl ethyl ketone and allowed to cool to obtain an amphorterized epoxy resin solution A"'-2.

Examples 51 to 53 Using the materials shown in Table 5, the same procedures as stated in Example 49 were repeated to obtain amphoterized epoxy resin solutions A"'-3 to A"'-5. The characteristics of thus obtained varnishes are shown in Table 5.

Comparative Example 15 475 Parts of Epotohto YD-014 were dissolved in a mixture of 114 parts of xylene and 235 parts of Cellosolve acetate and the mixture was added with 37.6 parts of azelaic acid and 10.5 parts of diethanolamine, and reacted at 1400C for 6 hours.

At the stage when the resinous acid value reached to 1.1 KOH mg/g, 278 parts of xylene and 157 parts of methyl ethyl ketone were added and the mixture was allowed to cool to obtain a modified epoxy resin solution B"'-1.

Comparative Example 16 784 Parts of Epotohto YD-017 were dissolved in a mixture of 320 parts of xylene and 261 parts of Cellosolve acetate and the mixture was added with 54 parts of phthalic anhydride and reacted at 140"C for 1 hour. At the stage when the resinous acid value-reached to 24.4 KOH mg/g, the mixture was allowed to cool, added with 32.4 parts of HEEI, reacted at 80"C for 1 hour, diluted with 115 parts of xylene and 174 parts of methyl ethyle ketone and allowed to cool to obtain an amphoterized epoxy resin solution B"2.

Comparative Example 17 980 Parts of Epotohto YD-017 were dissolved in a mixture of 451 parts of xylene and 368 parts of Cellosolve acetate and the mixture was added with 192 parts of trimellitic anhydride, reacted at 140"C for 1 hour, allowed to cool when the resinous acid value reached to 96.0 KOH mg/g, added with 57.2 parts of HEEI, reacted at 80 C for 1 hours, diluted with 164 parts of xylene and 246 parts of methyl ethyl ketone and allowed to cool to obtain an amphoterized epoxy resin solution B"'-3.

Example 54 237.5 Parts of modified epoxy resin solution B"'-1 of Comparative Example 15 and 10 parts of amphoterized epoxy resin solution A" '-1 of Example 49 were mixed together and kneaded well to obtain a resinous composition C"1. The characteristics of thus obtained varnish are shown in Table 5.

Example 55 175 Parts of modified epoxy resin solution B"'-1 of Comparative Example 15 and 60 parts of amphoterized epoxy resin solution B"'-3 of Comparative Example 17 were mixed together and kneaded well to obtain an amphoterized epoxy resin composition C"'-2. The characteristics of thus obtained varnish are shown in Table 5.

Examples 56 to 60 Based on Table 6, each of the amphoterized epoxy resin solutions of Examples 49 to 53 was added with 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate and the mixture was kneaded well in three roll mill. The mixture was then added with 10 parts of Cymel-303 (Trade mark, methoxymethylated malamine, manufactured by ACC) to obtain a primer coating composition, in each case.

Comparative Example 18 250 Parts of modified epoxy resin solution B"'-1 of Comparative Example 15 were added with 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate and the mixture was kneaded well and added with 10 parts of Cymel-303 to obtain a primer coating composition.

Comparative Example 19 To 200 parts of amphoterized epoxy resin solution B"'-2 of Comparative Example 16, were added 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate, and the mixture was kneaded well and added with 10 parts of Cymel 303 to obtain a primer coating composition.

Comparative Example 20 To 200 parts of amphoterized epoxy resin solution B" '-3 of Comparative Example 17, were added 30 parts of rutile type titanium dioxide and 25 parts of strontium chromate and the mixture was kneaded well and added with 10 parts of Cymel 303 to obtain a primer coating composition.

Examples 61 to 66 Using the material shown in Table 6 and various primer coating compositions were prepared.

The crosslinking agents used were also shown in Table 6 as well as the ratio of resinous composition to crosslinking agent.

Test-4 The thus obtained coating compositions were evaluated as in Test 3 and the results were also shown in Table 6.

Table 5

Example 49 50 51 Name of amphoterized epoxy resin composition A"'-1 A"'-2 A"'-3 Composition of resin Epotohto YD-017 784 Epotohto YD-014 722 (1) Epotohto YD-011 * 1 450 (1) ESAR-004 * 2 ESR-004 * 2 dibasic acid * 3 azelaic acid dimer acid its amount 71.5 (1) 289 (1) diethanolamine | | 13.3 (0.17) | 17.5 (0.17) polybasic acid phthal. anhyd.

its amount 36 amount of alkyleneimine 16.4 4.2 9.5 Characteristics of varnish non-volatile content % 50 45 45 varnish viscosity * 4 X Z X resinous(solid)acid value KOH g/g 7.5 2.2 6.8 each figure is by weight part ; ( ) shows euqivalent ratio *1.. Epotohto YD-011 ..Trade nark, epoxy resin having an epoxy equivalent of 450, xanufactured by Toto Kasei K.K.

*2.. ESAR-004 and ESR-004..Trade narks, epoxy resins having epoxy equivalents 950 and 1000, respectively, manufactured by Sumitomo Chemical Co. Ltd.

*3.. Diier acid has a carboxyl equivalent of 289 * 4.. measured by Gardner's viscometer (25 C) Table 5 (continued)

Example 52 53 Na.e of amphoterized epoxy resin composition A"'-4 Composition of resin Epototho YD-017 Epotohto YD-014 437 (0.92) Epotohto YD-011 * 1 ESAR-004 * 2 380 (1) ESR-004 *2 40 (0.08) dibasic acid *3 sebacic acid azzelaic acid its amount 27.0 (0.67) 37.6 (0.8) diethanolamine 13.3 (0.33) 10.5 (0.2) polybasic acid phthal. anhyd. phthal. anhyd.

its amount | 18 | 5 (0.14) amount of alkyleneimine 7.2 3.0 Characteristics of varnish non-volatile content % 45 40 varnish viscosity *4 Z1 Z2 resinous(solid)acid value KOH mg/g 8.1 1.1 each figure is by weight part ; ( ) shows euqivalent ratio *1.. Epotohto YD-011 ..Trade Mark, epoxy resin having an epoxy equivalent of 450, manufactured by Toto Kasei K.K.

* 2.. ESAR-004 and ESR-004..Trade Marks, epoxy resins having epoxy equivalents 950 and 1000, respectively. manufactured by Sumitomo Chemical Co. Ltd.

*3.. Dimer acid has a carboxyl equivalent of 289 * 4.. measured by Gardner's viscometer (25 C) Table 5 (continued)

Comparative Example 15 16 17 Nazis of amphoterized epoxy resin composition B"'-1 B"'-2 B"'-3 Composition of resin Epotohto YD-017 784 980 Epotohto YD-014 475 (1) Epotohto YD-011 * 1 ESAR-004 * 2 ESR-004 * 2 dibasic acid * 3 azelaic acid its amount 37.6 (0.8) diethanolanine 10.5 (0.2 atrimellitic polybasic acid phthal. anhyd. anhydride' its amount 54 192 amount of alkyleneimine | | 32.4 | 57.2 Characteristics of varnish @ non-volatile content % 40 50 50 varnish viscosity * 4 7 Y Z resinous(solid)acid value KOH mg/g | 1.1 | 6.7 | 69.5 each figure is by weight part ; ( ) shows euqivalent ratio *1.. Epotohto YD-011 ..Trade Mark, epoxy resin having an epoxy equivalent of 450, ianufactured by Toto Kasei K.K.

*2.. ESAR-004 and ESR-004..Trade narks, epoxy resins having epoxy equivalents 950 and 1000, respectively, oanufactured by Sumitomo Chemical Co. Ltd.

Example 54 55 Naio of amphoterized epoxy resin coiposition C"' - 1 C"' - 2 Coiposition of resin Epotohto YD-017 237.5 parts 175 parts Epotohto YD-014 of B"'-1 of B"'-1 Epotohto YD-011 * 1 and and ESAR-004 * 2 10 parts of 60 parts of ESR-004 * 2 A"'-1 B"'-3 diabasic acid * 3 its amount diethanolamine polybasic acid its amount amount of alhrleneiwine Characteristics of varnish non--volatile content % 40.4 42.6 varnish viscosity * 4 Y Y - Z resinous(solid)acid value KOH mg/g | 1.4 | 21.6 each figure is by weight part ; ( ) shows euqivalent ratio * 1.. Epotohto YD-011 ..Trade Mark, epoxy resin having an epoxy equivalent of 450, anufactured by Toto Kasei K.K.

* 2.. ESAR-004 and ESR-004 ..Trade Marks, epoxy resins having epoxy equivalents 950 and 1000, respectively, xanufactured by Sumitomo Chemical Co. Ltd.

*3.. Diner acid has a carboxyl equivalent of 289 * 4.. measured by Gardner's viscometer (25 C) Table 6

Example 56 57 58 foriulation of coating coiposition Naive of aiphoterized epoxy resin solution A"'-1 A"'-2 A"' -3 its amount 200 -222 222 amount of B"' - 1 aiphoterized epoxy resin / B"' - 1 (solid ratio) aiount of alkyleneiiine (equivalent resinous acid value, KOH ig/g) 12.6 5 8 resinous acid value KOH 6/6 7.5 2.20 6.8 crosslinking agent Cyiel 303 Cynel 303 Cy.el 303 its amounts 10 10 10 solid ratio of resinous conp./crosslinh.a6ent 100/10 100/10 100/10 Test results pencil hardness * 1 3 H 2 H H cross-cut tape peeling *2 0 0 0 bend. tape peeling *3 2T -X O 0 4T A 0 0 salt spray test *4 700 hrs tape peeling at cross-cut portion 0 0 O * 1.. JIS-K-5400 standard pencil scratch test * 2..JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 X..59/100 - 10/100 *3.. tape peeled degree O.. no peeling 0.. slight peeling A about 1/2 peeling X.. almost all peeling * 4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 6 (continued)

Example 59 60 foriulation of coating coiposition Naive of aiphoterized epoxy resin solution A"' -4 A"' -5 its amount 222 250 amount of B aiphoterized epoxy resin / B"'-1 (solid ratio) amount of alkyleneiiine (equivalent resinous acid value, 808 118/8) 10.4 3.6 resinous acid velue 808 ng/ 8.1 L.1 cross1inkin agent Cyel 303 Crial 303 its- amounts solid ratio of resinous coip./crosslink.agen 100/10 100/10 Test results pencil hardness * 1 2 H 2 H cross-cut tape peeling *2 0 0 bend. tape peeling *3 2T 0 0 4T 0 0 salt spray test * 4 700 hrs tape peeling at cross-cut portion 0 O * 1.. JIS-K-5400 standard pencil scratch test * 2..JIS-K-5400 standard cross-cut method #..100/100 -95/100 O. .94/100 - 80/100 #.. 79/100 -60/100 x..59-100 - 10/100 *3.. tape peeled degree #.. no peeling #.. slight peeling A about 1/2 peeling X.. almost all peeling *4.. test piece-cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 6

18 1 19 Coparative Exapls 20 forulation of coatin coposition epoxy resin solution its amount 200 200 amount of 3"' - 1 250 aiphoterized epoxy resin / B"'-1 (solid ratio) 0 / 100 amount of alkyleneiiine (equivalent resinous acid value, KOH iglg) 0 24.0 30.0 resinous acid value KOH ig/g 1.1 6.7 69.5 crosslinking agent Cyiel 303 Cy.el 303 Cyael 303 its amounts 10 10 10 solid ratio of resinous conp./crosslink.agen 100/10 100/10 100/10 Test results pencil hardness * 1 H 3 H 2 H cross-cut tape peeling *2 0 O x bend. tape peeling *3 2r O x x 4r O A x salt spray test *4 700 hrs tape peeling at cross-cut portion X i xx * 1.. JIS-K-5400 standard pencil scratch test * 2.. JIS-K-5400 standard cross-cut ethod #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree #.. no peeling 0.. slight peeling #..about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 6 (continued)

Example 61 62 63 fornulation of coating coeposition Nance of aiphoterized epoxy resin solution A"'-1 B"' -3 A"' -2 its amount 10 60 222 amount of 8"' -1 237.5 175 aiphoterized epoxy resin / B"'-1 (solid ratio) 5 / 95 30 / 70 amount of alkyleneieine (equivalent resinous acid value, KOH ng/g) 0.5 9 5 resinous acid value KOH Ig/s 1.5 21.60 ~ 2.20 crosslinking agent Cynel 303 Cyiel 303 Beckaiine-* its amounts 10 10 16.7 solid ratio of resinous co.p./crosslink.agent 100/10 100/10 100/10 Test results pencil hardness * 1 2 H H 2 II cross-cut tape peeling *2 0 0 O bend. tape peeling *3 2r 0 A 0 4T 0 0 0 salt spray test * 4 700 hrs tape peeling at cross-cut portion O 0 0 * 1.. JIS-K-5400 standard pencil scratch test * Beckamine G - 1850 * 2..JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree O.. no peeling 0.. slight peeling #..about 1/2 peeling x..almost all peeling * 4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm Table 6 (continued)

1 64 65 66 Exapie forulation of coatinl collpoaition Nee of aphoterized its amount 222 222 222 amount of 8"' - 1 aiphoterized epoxy resin / 6"'-1 (solid ratio) amount of alkyleneiiine (equivalent resinous acid value, KOH ec/6) 5 5 5 resinous acid value KOH ig/g 2.20 2.20 2.20 crosslinking agent Blocked NCO Cyiel 303 Cysel 303 its anounts 10 5 25 solid ratio of resinous cop./crbsslink.aent 100/10 r00/ 5 100/25 Test results pencil hardness $1 2 H 3 H 2 H cross-cut tape peeling *2 0 bend. tape peeling *3 21 O 0 0 4T 0 0 0 salt spray test * 4 700 hrs tape peeling at cross-cut portion 0 0 0 * 1.. JIS-K-5400 standard pencil scratch test 92.. JIS-K-5400 standard cross-cut method #..100/100 -95/100 #..94/100 - 80/100 #.. 79/100 -60/100 x..59/100 - 10/100 *3.. tape peeled degree O.. no peeling 0.. slight peeling A about 1/2 peeling X.. almost all peeling *4.. test piece cutted to the substrate, subjected to JIS-Z-2371 salt spray test for 700 hours #..(peeled width) 0 - 1.0 mm #...1.1 - 2.0 mm #.. 2.1 - 3.0 mm x...more than 3.1 mm

Claims

1. An epoxy resin varnish for primer coating use comprising polybasic acid modified epoxy resin or a mixture of such modified epoxy resin and unmodified epoxy resin, the said polybasic acid having a titration midpoint potential of more than -300 mV in non-aqueous potentiometric titration, under state capable of developing resinous acid value, and the resinous acid value based on said polybasic acid in the final resin being 0.1 50.

2. An epoxy resin varnish according to claim 1, substantially as herein described in any of the foregoing Examples.