GB2237019A

GB2237019A - Method for preparing water-diluted modified epoxyaminorubber adduct

Info

Publication number: GB2237019A
Application number: GB8922958A
Authority: GB
Inventors: Miroslava Mikhailovna Babkina; Rimma Andreevna Martynenkova; Lev Abramovich Dobrovinsky; Leonid Alexandrovich Mirkind; Svetlana Mikhailovna Firger; Olga Julianovna Khenven; Leon Velvelevich Nitsberg; Tatyana Vilievna Klimova; Elena Vladimirovna Svistunova; Elena Stepanovna Radukan; Nikolai Alexandrov Konovalenko
Original assignee: RADUKAN ELENA S; SVISTUNOVA ELENA V
Current assignee: RADUKAN ELENA S; SVISTUNOVA ELENA V
Priority date: 1989-10-12
Filing date: 1989-10-12
Publication date: 1991-04-24
Also published as: GB8922958D0; DE3935026A1; CN1051745A; JPH03140381A; IT8941757A1; IT8941757A0; IT1238999B; FR2653773A1

Abstract

A method for preparing a water-diluted modified epoxyaminorubber adduct comprises reacting a diane epoxy resin with a maleinized butadiene rubber having opened anhydride groups and with an acidic component such as resin, and then with secondary amines. The epoxyaminorubber adduct is then modified by reaction with a nitrogen-containing curing agent and polyaminoimidazoline, followed by neutralization to give the desired product. The invention is useful for application of protective coatings on articles of ferrous or non-ferrous metals by cathodic electrodeposition.

Description

f 1 t k METHOD FOR PREPARING WATER-DILUTED MODIFIED EPOXYAMINO RUBBER

ADDUCT The present invention relates to the chemistry of paint-and-varnish materials and, more specifically, to a method for preparing a water-diluted modified epoxyaminorubber adduct and can be useful for application of protective coatings onto articles from steel and non-ferrous metals by way of cathodic electrodeposition.

At the present time water-diluted adducts are wide- ly employed for application of both varnish and pigmented coatings on various metal articles such as car bodies. Among the methods employed for this purpose the most promising is cathodic electrodeposition called otherwise cataphoresis.

The coatings thus obtained enable a considerably extended service life of the articles.

The solutions of adducts employed for application of the above-mentioned coatings by the method of catho- dic electrodeposition are subject to high requirements as to the stability in storage and dispersing power showing the depth of penetrationof the deposited coating into hidden recesses of the metal surface.

The resulting coatings must be of a high strength both upon impact and tension, as well as-of a high corrosion-resistance.

0 X Furthermore, upon de-energizing of the electricdeposition bath the non- cared coating should not be dissolved. The dissolationleven partial, of the non-cared coating in the electrolyte results in the production of an article with a cured coating of an insufficient thickness. Such coating does not satisfy the requirements imposed thereon regarding its physico-mechanical and protecting properties.

Moreover, upon dissolution of a non-cured coating in the electrolyte of the electrodeposition bath the material of the coating is lost.

Known in the art is a method for producing a waterdiluted modified epoxyaminorabber adduct employed for a cathodic electrodeposition (DE, C 2926001)..

According to this process, a diane epoxy resin is first reacted with a polymer of a diene monomer or with a copolymer of a diene and vinyl monomers containing terminal carboxy groups and then successively with amines, and with an isocyanate semiblocked with butanol. To ob- tain the desired product, the resulting reaction mass is neutralized with an organic acid.

The adduct produced by this method forms protective coatings on metal articles with a good appearance and high mechanical- strength properties.

Howeverl solations of these addutts have a relatively low dispersing capacityand applied to substrates k of coatings, in the case of de-energizing (switching-off electric current), they are partly dissolved in the electrolyte of the electrodeposition bath.

Known in the art is a method for the production of a water-diluted modified epoxyaminorubber adduct comprising reacting a diane epoxy resin with a maleinlztd butadiene rubber containing open anhydride groups. an acidic component, secondary amines.and a nitrogen-containing curing agent, followed by neutralization of the adduct to give the desired product (DEp C 3000911).

in this method. the diane epoxy resin is first reacted with maleinized butadiene rubber and secondary amines and then successively with the acidic component and the nitrogencontaining curing agent. As the nitrogencontaining curing agent is used tolaylene diisocyanate partly or fully blocked by 2-hydroxyethylmethacrylate.

Then the adduct is neutralized with an organic acid such as acetic acid to give the desired product.

The adduct-produced by this process also forms both varnish and primer protective coatings with a good appearance on articles from various metals. The impact strength of such coating on steel is 50 kg.cm. Erikseen tensile strength is 8.5 mm. salt-resistance determined in a chamber with mist of a 5% aqueous solution of NaCl 25 is 240 hours.

It Is an object of the present invention to improve f k the dispersing capacity of tile coating material and stability of aqueous working solutions of the film-forming agent according to the present invention In storage.

This object is accomplished by that in a method for preparing a waterdiluted modified epoxyaminorabber adduct by way of reacting a diane apoxy resin with a maleinized butadiene rubber containing opened anhydride groups. an acidic component, and then with secondary amines, followed by modification of the formed adduct with a nitrogen-containing curing agent. neutralization thereof to give the desired product, according to the present invention the diane epoxy resin is reacted with the maleinized butadiene rubber and the acidie component represented by resin and then with secondary amines and the resulting adduct is modified with the nitrogen-containing curing agent and, additionally, with polyaminoimideazoline.

As the nitrogen-containing curing agent it is advisable to use semiblocked tolaylene dilsocyanate and/ or aminoformaldehyde resin.

In the case of using semiblocked toluylene diisocyanate the adduct Is first modified with tolaylene dilsotyanate and then - with polyaminolmidazoline.

In the case of using aminoformaldehyde resin the adduct is first modified with polyaminolmidazo line and then - with aminoformaldehyde resin.

_In the case of using semiblocked tnluylene diisocyanate and aminoformaldehyde resin as the nitrogencontaining curing agent the adduct is successively modified with semiblocked toluylene diisocyanatet poly5 aminoimidazollne and aminoformaldebyde resin.

The method according to the present invention makes it possible to obtain a water-diluted modified epoxyaminorubber adduct giving coatings on steels and non-ferrous metals having a good appearancel an i=reas- ed salt-resistance and high physico-mechanical properties.

Furthermore, 10-12% solutions of the adduct from which protective coatings are applied onto the articles are stable for 40-45 days. while the solutions of the ad- duct produced by the known method (DE, C# 3000911) re- tain their stability for only 20 days.

The dispersing capacity of the varnish coating based on the adduct produced by the method according to thp present invention is equal to 1315.5 om when determined by the Fiat method which is also superior to the dispersing capacity of the adduct produced by thpknown method (DE, C9 3000911) which when measured by the FIAT procedure Is equal to 8 cm.

When electric current is switched-off, In the electrodeposition bath no dissolution of the coating based on the adduct produced by the method of the pre- 1 sent Invention occurs in contrast to the coating based on the adduct produced by the known process (D39 Cy 3000911).

Thus. the thickness of a coating on the basis of the adduct produced by the method of the present inven tion and applied under conventional conditions Isq seconds after switching-off electric current, 20 1m as during the initial a tage.

The thickness of the coating produced on the bas is of the adduct according to the prior art process (DEY C 3000911) 60 seconds after switching-off elect ric current is only 10-12jum at the initiql value of 18-20 jum.

The absence of dissolution of the coating on the basis of the adduct produced by the method accordinp: to the present invention in the bath upon de-energizing thereof results in that upon switching-off electric current there are retainedg in contrast to the coating based on the adduct produced by the prior art process (D39 E 3000911), the salt-resistance and mechanical strength properties of the coating materialq while loss es of the coating material due to its dissolution in the electrodeposition bath are avoided.

The method according to the present invention is carried out in the following manner.

A diane epoxy resin a maleinized butadiene rubber with opened anhydride groups, rosin and an organic sol vent are charged into a reactor. The reaction mass is heated to 80-1500C and maintained until the reaction between the above-mentioned substances is completed.

The acid number in this case should be not more than 0.4 mgKOH/g. Then secondary amines are introduced into the reaction. As the secondary amiaes can be useds for example, dietb;71amine, diethanolamine.

The reaction mass is kept at a temperature with 1-0 in the range of from 70 to 1000C till free seenndary amines therein are absent. The resulting adduct is mo dified with a nitrogen-containing curing agent and po lyaminoimidazoline.

As the nitrogen-containing curing agent it is pos- sible to use semiblocked tolu7leae diisacyanate and/or aminoformaldehyde resin.

In this case it is advisable to introduce poly- aminoimidazoline after semiblocked toluylene diisocy- anate.

When aminoformaldehyde resin is used, it should be introduced after polyaminoimidazoliae.

When the above-mentioned sequence of the step wise performance of the process of synthesis of a wat er-diluted adduct for a cathodic electrodeposition is violated, the possibility of occurrence of side reactions is increased, wherefoke a reliable control of the process is not ensured and gelation of the reaction mass is possible.

Upon the reaction of the diane epoxy resin with secondary aminoalcoholeg reactive primary hydroxy groups are incorporated into the epoxy resin composition, while upon opening of the etbTlen-oxide ring secondary hydroxy groups and tertiary amino groups are formed which are capable of catalyzing polymerization of the epoxy resin. That is why the addition. to the diRne epoxy resin, of secondary amines and then carboxy-containing components at a higher temperature will contribute to the progress of undesirable side processes andy hence, to the preparation of Intermediate products with a higher molecular mass which upon a f urther interaction with the polyfunctional nitrogen-containing curing agent can result In gelation of the reaction mass.

The incorporation of semiblocked toluylene diisocyanate into the reaction mixture Is possible only after the addition of carboxy-containing components and se- condary amines to the diane epoxy resin. I.e. after thp. formation of hydroxy groups capable of reacting with the isncyanate group, in the intermediate product.

It is permissible to react semiblocked toluylene diisocyanate with the epoxyaminorubber adduct after the 2.5 addition of polyaminoimidazoline to the latter, but in this case essential steric U6drances occur associated 1 with a highly-branched character of a molecule of polyaminoimidazoline which impairs compatibility of intermediate products and complicates their interaction.

The introduction, into the reaction mass, of aminoformaldebyde resins after the addition of secondary amines will result in a substantially full exhaustion of the residual epoxy groups (methylol groups rather readily react with epoxy ones)s wherefore polyaminoimidazoline remains in the reaction mass in a free state, thus substantially lowering electrophoretic characteristics of the solution of the adduct and of protective properties of the resulting coating.

The diane epoxy resin employed in the process according to the present invention can have different epo- xy equivalents (200 to 500)- The maleinized butadiene rubber employed in the process according to the present invention and containing opened anhydride groups can have a molecular mass of from 800 to 2,000 and a content of 1.2-units of from 15 to 70%- As the acidic component in the process according to the present invention is used a pine rosin with a melting point of not less than 800C and as the secondary amines - amines and aminoalcohols of the aliphatic series such as dietbyl and diethanolamines.

The semiblocked, by mean's of a-butanoll- tolu,71ene k diisocyanate employedin the process according to the present invention has a content of 2.4-isomer of from to 65% and of 296-fibomer of from 20-35%; polyamino imidazoliae is a product of interaction of methyl ethers of monomeric acids of semidrying vegetable oils with triethylene tetramine 9 its amino number is 315-330 mg KOH/g The aminoformaldehyde resin (melamiao- and/or urea formaldehyde resins) is partly- etherif ied with a medium reactivity and a molecular mass of from 700 to 29500.

For a better understanding of the present inven- tion, some specific examples illustrating its particular embodiments are given hereinbelow.

Example 1

307 g of a-diane epoxy resin with the epoxy equi- valeat of 300, along with 210 g of a malAinized butadieae rubber with opened anhydride groups having the molecular mass of ls300 containing 40% of 1,2-vinyl units are charged into a reactor; 35 9 of rosin and 340g 20 of ethylglycol acetate. The reaction'mass is heated to 0 the temperature of 110 CS kept at thin temperature to an acid numbei? of not more tbA.n 0.4 mg KOH/g. The reaction mass is cooled to SOOC and a mixture of 29 g of diethanolamine and 20 g of diAthylamine is then dropwise added. On completion of this drop-wise addition, the reaction mass is kept at q6oC till a complete absence of free amines and then 246 g of a 76% solution of semiblocked tnluylene diisocyanate in ethylglycol acetate is added thereto; the reaction mass is kept at 900C till completion of the reaction and 61 g of poly.5 amino imidazo line are introduced thereinto. The mass is mal.ntained at 700C till completion of the reaction.The resulting adduct is cooled to 40-450C9 neutralized with formic acid to a pH of 5.5-6.0. The thus-obtained desired product is diluted with distilled water to obtain a working solution of a 10-12% concentration which is tested to determine its properties. The thus-prepared working solution Of the water-diluted adduct is applied, by the method of cathodic electrophoresis at the voltage of 15OV, onto steel plates and dried at 18n0C for 30 minutes. A varnished glossy smooth coating of a 20-25 1m thickness is obtained and tested for its mechanicalstrength properties and salt-resistance. The test results are shown in Table 1 hereinbelow.

Example 2

The process according to the present Invention is effected as described in &ample 1 hereinabove, but use is made of a maleinized polybut.adione rubber with the molecular mass of 1,100, the content of 192-Yinyl bonds of 20%, and as the-nitrogen-containing curing agent use is made of melanino formaldehyde resin; the adduct is at first modified with 61 g of plyaminoimidazoline, the reaction mass is kept at 9000 till completion of the reaction and then 148 g of melaminoformaldehyde resin (50% solution in butanol) is added and th^ reaction mass is kent at 90oC till completion of the reaction.

The resulting adduct is neutralized with formic acid at a temperature of from 45 to 500C to a pR = 6.0-9.0 in a manner similar to that of the foregoing iixample 1. The resulting desired product is diluted with distilled water to give a working solutlon of a 10-12% concentra10 tion, wherefrnm a coating is applied onto a steel substrate; the properties of the working solution and of the obtained coating are tested in a manner similar to that of Example 1 hereinbefore.

The test results are shown in Table 1 hereinbelow.

Example 3

The procedure of Example 1 Is repeated but as the nitrogen-containing modifying agent is used semiblocked toluylene dilsocyanate and ureaformaldehyde resin. In this case, on completion of the reaction of a reaction 2() mass with a mixture of diethanolamine and diethylamine 109.2 s of a 76% solution of semiblocked toluylene diisocyanate in ethyl glycol acetate are introduced into the reaction mass& tile latter is maintained at 900C till completion of tile reactions whereafter 61 g of polyaminoimidazoline are added thereto. The-mass is kept at 900C till completion of the reaction, added to 166 g i k ( 1 Of a 50% solution of urea-formaldehyde resin and the reaction mass is again kept at 900C till the reaction is completed.

The resulting adduct is neutralized with formic acid at a temperature of 45-500C to a pH of 6.0-7.0 In a manner similar to that described in Example 1 hereinbefore. The thus-obtained desired product is diluted with distilled water to give a working solution of a 10-12% concentrations wherefrom coatings are deposited on- to metal subattates and the properties of the working solution and of the obtained coating are tested in a manner similar to that of Example 1. The test results are shown in the following Table 1. Example 4. 255 g of a diane epoxy resin with the epoxy equivalent of 200, 194 g of a maleinizAd butadiene rubber with opened anhydride groups based on polybutadiene with the molecular mass of 1,600 containing 35% of 1.2- vinyl 20 units, 42 g of rosin and 300 9 of ethylglycol acetate are charged into a reactor; the reaction mass Is heated to 11000 and kept at this temperature to an acid number of not more than 0.4 mg KOH/g. Then the reaction mass Is cooled to 8000 and a mixture of 39 9 of diethanolamine and 27 g of diethylamine is drop-wise added thereto. On completion of this drop-wise ddition the reaction mass F is kept at 9000 till a onmplete absence of free amines. Afterwards. 73 9 of polyaminoimiclazoline are charged and the reaction mass is maintained at 900C till a coml.; plete absence of a free amine. Then 70 g of a 50% solution of melaminoformaldehyde resin and 70 g of a 50% solution of ureaformaldehyde resin are added and kePt at 900C till completion of the reaction. The resulting product is neutralized with acetic acid at a temperature of from 45 to 500C to a pH of 6.0-7.0 in a manner l() similar to that described in Example 1 hereinbefore. The resulting desired product Is diluted with distilled water to give a working solution of a 10-12% concentration, wherefrom coatings are deposited onto a steel substrate and the properties of the working solution and of the resulting coating are tested in a manner similar to that of Example 1.

The properties of the water-diluted film-forming agents and of the coatings produced tharefrom by the. cathodic electrodeposition method are shown in the fol20 lowing Table 1.

Example 5

The procedure for the production of the adduct is reDAated as described In Example 1 hereinbefore and from the resulting adduct a pigmented composition in prepared for cataphoresis which composition incorporates the following components,Per cent by mass:

1 1 Table 1 Properties of working solution and varnish coatings based on the adducts produced by the process of the invention and by th^ prior art process

3 Known 3 x a m_p 1 c a - adduct - (DE,Cl 1 2 3 4 3000911) Characteristics pH of the bath (10-12% aqueous solution) 4.5 Stability of the bath in storage, days 20 Dispersing capacity by thp Fiat methody em 8 Thickness of the coat Ing deposited under usual conditions, = 18-20 and lef t in the bath with switched-off electric current, f or 30 " pm for 6Onj PM Impact strength of the coating applied under usual conditi- 14-16 10-12 4 5 6 5.5 6.5 6.0 7.0 45 45 40 13 15.5 14 13 20-22 20-25 20-22 20-25 20-P2 20-P5 1 20-P.2 20-PP 20-22 20-22 20-22 20-22 r --- k - 16 Table 1 (continued) 1 2 3 4 5 ons, kg -cm and left In the bath with switched-off electric current for 30'ns kg.cm 40 for 601% kg.cm 30 Briksaen tensile strength of the coating applied under usual conditions, mm and left in the bath with switched-off electric current$ for 30,19 mm 7 for 600. mm 5 Salt-resistance of the coating of mist 5% so lution of NaCl on steel applied under usual con ditions and left in the bath with switched-off electric current, for 30% h for 60919 h Patent data 50) 50 50 50 50 50 50 50 50 50 50 7 9 8.5 7 9 8.5 7 9 8.5 240) 300 1.80 ' 300 300 9 9 9 280 300 250 280 300 250 280 300 250 1 adduct of this invention ethyl glycol acetate titanium dioxide lead silicochromate carbon black microtalcum china clay formic acid distilled water 1 10 10-5 4.2 2.1 0.2 0.1 0.6 0.5 0.15 81-65- The composition is subjected to dispersing for 30 minutes for a dispersity of 15-20,gm. The final composition is diluted with distilled water to the content of dry solids of 15% and applied onto steel degreased or phosphate-treated plates or non-ferrous plates. The re- sulting primer coating is dried for 30 minutes at a temperature within the range of from 180 to 2000C. The properties of solutions of the pigmented composition and those of the coating produced therefrom are shown in Table 2.

Example 6

The production of an adduct is effected in a manner similar to that described in Example 2 hereinbefore. Likewise in Example 5, from the adduct a pigmented compositioa is Prepared and a coating based thereoni they are tested for their properties. The test results are shown in Table 2 hereinbelow. P 1 k, - 18 Example 7

The adduct is prepared In a manner similar to that described in Example 3 hereinbefore. Likewise in Example. 59 a pigmented composition Is prepared and a coating 5 based thereon and they are tested for their properties. The test results are shown in Table 2 hereinbelow.

Example 8

The adduct is prepared in a manner siTilar to that descriDed in &ample 4 nereinbefore. Likewise in Ex- ample 5, from the adduct a pigmented composition and a primer coating are prepared and their properties are tested. The results of the tests are shown in Table 2 hereinbelow.

Table 2 Primer coatings based on the adducts produced by the process of this invention and by the known process - ---Te s E x a mi p 6 7 8 Characteristics adducts produced by by the the process of the ú12OWn Pro Invention cess (DE, C93000911) 1. 2 3 4 5 6 pH of the bath Stability of the bath in storage, days 5.5 6.3 6.0 6.5 4.5 45 45 40 20 1 1 0 1 - i9 Table 2 (continued) 1 2 3 4 5 6 Dispersing capacity by the Flat methodcm 17 Appearance of the film Thickness of the coating applied under usual conditions. PM and lef t in the bath f or 30 ".pm for 60,19 Jum Impact strength of the coating deposited under usual conditionsgkg.cm and lef t in the bath for 30% kg-cm for 6011, kg.em Tensile strength of the coating by the Brikssen method applied under usual conditions. mm and allowed to stay for 30% mm for 60,19 mm Salt-resistance of the 19.5 18 19.0 10 uniform$ smooth 18-20 18-20 18-20 18-20 18-20 18-20 18-20 18-20 18-20 12-14 18-42-10 18-20 18-20 16-18 10-12 50 50 35 25 6.5 8.5 8.0 8.5 8.5 6.5 8.5 8.0 6.5 8.5 8.0 8.5 6.5 8.5 5.5 - 20 Table 2 (continued) 1 2 4 6 coatings on a phosphatized substrate in a salt-mist chamberapplied under usual conditions, h and lef t in the bath for 30", h for 60,19 h 1.200 l#000 1,200 19000 450 1,200 1,000 1200 ltU00 400 1,200 1,000 19200 19000 320 f 0 1

Claims

WE CLAIM:

1. A method for preparing a water-diluted modified epoxyaminorubber adduct comprising reacting a diane epoxy 5 resin at first with a maleinized butadiene rubber containing opened anhydride groups with an acidic component such as rosin, and thereafterg with secondary amines and the resulting adduct is modified with a nitrogen-containing curing agent and polyamincimidazoline, followed by neutralization of the modified adduct to give the desired product.

2. A method according to Claim 19 wherein the resulting adduct is modified successively with a nitrogencontaining curing agent - semiblockea tolgylene dilso- cyanate and witli-polyaminoimidazoline.

3. A method according to Claim 19 wherein as the nitrogen-containing curing agent use is made of an amino formaldehyde resin with which the adduct is modified aft er its reaction with polyaminoimidazoline.

4. A method according to Claim 19 wherein the re sultinS adduct is successively modified with a nitrogen containing curing aSent semiblocked toluWlene dilsocy anate, polyaminolmidazoline and then additionally with a nitrogen-containing curing agent - an aminoformaldehyde resin.

5. A method for preparing a water-diluted modi- 1 fied epoxyaminorubber adduct according to the foregoing Claims 1 to 49 substantially as described in the Specifications and Examples hereinbefore.

h 1 g Published 1991 atfbe Patent Office. State House. 66/71 High Holbom. London WCIR47P. Further copies maybe obtained from Sales Branch. Urdt.

6. Nine Mile Point. CwmfelinfiLch, Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.