FI64622C - SAETT ATT FRAMSTAELLA ETT VATTENLOESLIGT OCH LUFTTORKANDE LACKBINDEMEDEL AV ALKYDTYP - Google Patents

Description

U.W7I rRl rt1. NOTICE OF PUBLICATION,. , 0 - ™ ^ UTLÄGGNINGSSKRIFT 64622 c (4S) '::: lc:;: 3 rtr11' löe'σ '09 ^ d 3/64 (SI) // c 08 G 63/46 FINLAND - FINLAND (21) P * tenttlh »kemu * - Piteminseknlng 791305 (22) H» keml * pl! vi - AnsBknlngsdag 23-01.79 '(23) AlkupUvt —- Giltlghetsdag 23-01-79 (41) Become Public - Bllvlt offentllg 27.10.79

National Board of Patents and Registration (44) Date of publication of the notice of issue. - οι 08 83

Patent and registration authorities Ankdkan utlagd ocb utl-skriften publlc «r» d (32) (33) (31) Pyydetty etuoikeus — Begird prlorltet 26.01. j8

Sweden-Sverige (SE) 780l795 ~ 8 (71) Bergviks Hartsprodukter Aktiebolag, Box 27, S-820 22 Sandarne, Sweden-Sverige (SE) (72) Ragnar Ivermark, Sandarne, Bo Fallatröm, Mannaverken,

Lars Björk, Sandarne, Sweden-Sverige (SE) (7l) Oy Kolster Ab (5l) A method of producing a water-soluble and air-drying alkyd-type lacquer binder - Sätt att framställa ett vattenlösligt och luft-torkande lackbindemedel av alkydtyp

Conventional air-drying varnishes, which give a decorative and dirt- and abrasion-resistant, preferably glossy, surface, are known to consist of three main ingredients, namely a lacquer binder which, when dried, forms a layer firmly adhered to the substrate and binds or encapsulates other main ingredients. remains dispersed in a relatively low-viscosity solution of the binder in the third major component, namely in a more or less volatile organic solvent which is regularly hazardous to health in the working environment.

It is also well known that long efforts have been made to replace the latter organic solvent with water, which should probably be advantageous for both health and cost reasons. Both the older "sludge paint" and emulsion paint types and the current so - called plastic dispersion dyes are based on these principles, but in particular 2,64622 the latter dyes differ from the lacquer dyes dissolved in the solvents substantially in their film-forming properties in that the binder is not in the form of a fine (colloidal) solution but forms a dispersion of the same size as the pigment. A detrimental consequence of this is, for example, the great difficulty in producing these types of paints which would give an as smooth surface as conventional solvents dissolved in solvents. These paints are also characterized by limited dirt resistance and reduced washability, which is why they are less useful than ordinary varnishes when painting interior furniture, kitchens, bathrooms, etc. The color layers formed by these paint types can be summarized as too porous to obtain good properties.

Better results have been obtained by replacing conventional organic solvents with water in varnishes that dry in an oven or otherwise cure, but not primarily in air. These products form a direct application of Hohnels' well-known patent (1948, British Patent No. 665,195), according to which a polyester containing free carboxyl groups, of the type now known as alkyd, is made soluble in water and diluted with water by neutralization with ammonia. or alkylamines, for example, to (alkyl) ammonium soaps which, in the combustion of the lacquer, react in the same way with urea or melamine resins dissolved in water. In recent years, these types of varnishes have achieved relatively widespread use in industrial varnishing, especially the so-called (Rust protection) -pöhjustusmaaleina.

In said use, the water-soluble (alkyl) ammonium salts regularly decompose virtually completely, releasing ammonia or free amine which escapes with the ventilation air from the drying furnace equipment. It is widely believed and often found in the professional literature that this complete decomposition of soaps is a necessary condition for making the color layer water-resistant. In the journal "Pigment and Resin Technology", May 1977, pages 13-14, in the article "Formulation of water thinnable paints" it is mentioned as soaps about water-dissolved alkyds that "the neutralizing agent must completely evaporate from the lacquer film, otherwise water resistance will be impaired".

One consequence of this notion has apparently been that those skilled in the art of coloring and varnishing consider that air-drying varnishes can hardly be prepared from alkyd soaps dissolved in water without very poor water resistance because the soaps cannot be expected to disperse completely. If, on the other hand, soaps could be produced which decompose completely during drying, it has apparently been assumed that this decomposition occurs with the formation of ammonia or free amine in amounts which, for occupational hygienic reasons, are considered to exceed the given hygienic limits. In "Farbe und Lack" »Volume 83, No. 7, 1977, page 595, the article" Einige Aspekte der Säure / Base-Wechselwirkung "by Charles M. Hansen, summarizes that" amines can be released from oleic acid films relatively quickly by evaporation ".

It is only recently that it has become clear that these notions of events in the air drying of alkyd soaps are false. In the article "Vattenlösta färger - en sund tanke?" (Färg och Lack 24 (1978) No. 5) it has been shown that ammonium- or alkylammonium-saponified alkyds of the above-mentioned type can be air-dried without the release of ammonia or amines in harmful amounts and that the air-dried lacquer film formed contains a considerable amount of of the alkyd soap contained in the beginning (its nitrogen content) permanently bound and thus substantially affects the properties of the film. Surprisingly, it turned out that the films obtained in this case have very good water resistance, gloss, etc., especially when compared with films formed from well-known plastic dispersion dyes.

At the end of said article, it is further mentioned that the corresponding alkali metal saponified alkyd products, on the other hand, are not water-resistant at all and can be easily removed by washing even after the film has dried.

According to the present invention, it has been found that the aforementioned difference between different alkyd soaps can be exploited in a surprising and particularly advantageous manner.

Namely, the process according to the invention comprises that the alkyds containing free carboxylic acids are first only partially neutralized (i.e. not completely or sufficiently to make the product completely water-soluble). The neutralization is carried out with ammonia or an amine (or other nitrogen base), the amount of 64622 (alkyl) ammonium salt (soap) being formed being limited so that no or almost no free ammonia (amine) is removed later on drying of the film. Instead, a limited amount of ammonium soap remains in the dry film and gives it the desired water resistance.

In the first step, the only partially neutralized alkyd is subjected to a second neutralization step with a water-soluble alkali, preferably an alkaline-reactive salt of an inorganic or organic acid, until the pH of the solution is between 6 and 8, preferably about 7. The alkali metal soap formed makes the alkyd product clearly water-soluble. but allows the film to dry after application of the paint to a film with normal properties with only a negligible reduction in water resistance.

Preferably, an alkyd resin is used whose carboxyl groups give an alkyd acid number of 20 to 70 mg KOH / g, i.e. 0.36 to 1.25 meq / g.

The invention is presented in more detail by means of the following embodiment.

Five different clear lacquers (unpigmented colors), denoted by the numbers 1-5, were prepared according to the following table, which, in addition to the ingredients, also shows the order of their addition and the specified essential properties of the respective lacquers.

64622

Table

Varnish number 12345 from 90.9% alkyd solution 44.0 44.0 44.0 44.0 44.0

Triethylamine, 100% 2.9 to 1.6 1.6

Borax solution, 10% - 42.0 - 20.0 22.0

Triethylamine, 100% 1.6

Ethyl glycol 12.0 12.0 12.0 12.0 12.0

Dry sieve solution 1.9 1.9 1.9 1.9 1.9

Methyl ethyl ketoxime

Water (distilled) _25.0 to 25.0 7.0 5.5

The sum of the ingredients 85.9 100.0 84.6 86.7 87.1

The pH of the varnish (aqueous solution) is 7.2 6.8 5.9 7.0 7.0

Water resistance of the lacquer film on a glass plate after drying for 20 hours, tested according to SIS 18 41 61 (petrimal), exposure time in minutes for loss of gloss on the wet surface of the film approx. 80 1 approx. 80 50 2

Pendulum hardness (König, pendulum) determined according to SIS 18 41 86 on a glass plate after drying for 20 hours, seconds 7 9 5 10 9

Pendulum hardness after 44 hours, seconds 12 14 8 24 20

The difference between the compositions of the varnishes concerns, as can be seen, mainly the quality and quantity of the neutralizing agent (soap former). Only clear lacquer No. 4 was prepared according to the invention. As can be seen, it was first partially neutralized by the addition of triethylamine in an amount which in Varnish No. 3 proved insufficient for complete neutralization and did not give a clear aqueous solution with acceptable painting properties. The neutralization was then completed to a pH of about 7 by the addition of sodium tetraborate (borax) in aqueous solution. The pH was determined using a glass-kälomel combination electrode.

Other varnishes show the effect of neutralization when carried out in a manner different from the method according to the invention.

In all cases, the same alkyd resin containing 6,646,2 free carboxyl groups (acid number 50) was used. It corresponds in structure to a product known as "Component II" in British Patent No. 665,195, which is further defined in claims 7 to 9 of said patent.

Each of Varnishes Nos. 1-5 was prepared from 40 parts by weight of alkyd resin calculated as 100%. For the neutralization treatment, this resin was dissolved in 2 parts by weight of ethyl diglycol and 2 parts by weight of ethyl glycol and then used as a solution having a dry matter content of 90.9% by weight and a viscosity of 2.2 Pa.s at 50 ° C.

The added desiccant solution corresponded to the formula 0.05 Co + 0.3 Ba + 0.15 Zn calculated as a percentage of the amount of solid, unneutralized alkyd as metals. Methyl ethyl ketoxime was used as an anti-peel agent.

The table further shows that Varnish No. 3 contains the same ingredients as Varnish No. 1, but was only partially neutralized so that it did not give a clear aqueous solution and did not form a detectable amount of ammonia or amine during application and drying. However, as can be seen, the water resistance of both varnishes is approximately the same when examined after a drying time of 20 hours.

Varnish No. 2, on the other hand, which was neutralized with a solution of sodium tetraborate (borax), practically did not withstand water at all after the same time. The sodium soaps formed are apparently relatively soluble in water. A lacquer film with a normal appearance is clearly unusable due to its lack of water resistance.

In the preparation of Varnish No. 4, according to the invention, the alkyd in question was first neutralized with the same amount of triethylamine used in Varnish No. 3 and then further neutralized by adding a borax solution such as Varnish No. 2, but only the amount required to finally complete a clear aqueous solution. The pH would be 7.0. As can be seen, the water resistance of Varnish No. 4 was slightly worse than that of Varnish No. 1, which was neutralized with triethylamine alone, but at the same time its hardness was superior to other varnishes.

When applying varnishes Nos. 3 and 4 to 20 cm diameter hardboard placed in a desiccator with an air volume of about 3 liters, no measurable amount of triethylamine could be detected by the Dräger tube 7 64622 during the drying phase, even if the drum pump according to the instructions doubled. It should be added that the gas content in ventilated apartments in painting work is likely to be even lower. In contrast, when applying varnish No. 1, which was completely neutralized with triethylamine alone, triethylamine could be detected in the desiccator air - about 5-10 ppm using a five-pump stroke.

A comparison between Varnish No. 4 and Varnishes 1-3 shows that the purpose of the procedure according to the invention could be achieved by partial saponification with triethylamine and then complete saponification with borax.

In the experiment with lacquer no. 5, in which the order of the neutralization steps was reversed, first neutralizing with sodium tetraborate and then with triethylamine (in both cases in approximately the same amounts as in lacquer no. 4), a lacquer film with practically the same water resistance was obtained. bad than varnish No. 2, which was neutralized with borax alone.

The example thus clearly shows that the order of the neutralization steps is decisive for the properties of the color layer.

It should also be added that when varnish No. 5 was applied to the hardboard, the amount observed in the desiccator evaporated when the triethylamine was measured in the desiccator air using a drager tube (such as varnish No. 1).

The procedure is not limited to the circumstances set out in the example, but can, of course, be applied to various similar cases within the scope of the invention, as set out in the following claims.

Claims (3)

8 64622 A process for preparing a water-soluble and water-thinnable, air-drying alkyd-type lacquer binder, wherein the free carboxyl groups contained in the alkyd resin are neutralized with a nitrogen-based component such as ammonia or an amine to form a water-soluble ammonium compound. the required amount of said component so as to form a limited amount of water-soluble ammonium compound, and in a second step a sufficient amount of a water-soluble alkali, preferably an alkali-reactive salt in an aqueous solution of an organic or inorganic acid, is added for complete neutralization. Process according to Claim 1, characterized in that an alkyd resin is used, the carboxyl groups of which give the alkyd an acid number of 20 to 70 mg KOH / g, i.e. 0.36 to 1.25 meq / g. Process according to Claim 1 or 2, characterized in that the amount of alkali to be added in the second neutralization step is adjusted so that the pH of the aqueous binder solution is 6 to 8, preferably about 7.