NO116730B - - Google Patents

Abstract

A fatty acid ester resin containing free carboxyl groups is obtained by reacting at most 65% of the carboxyl groups of a poly-carboxylic acid or intramolecular anhydride thereof with a hydroxy-containing fatty acid ester of an aromatic compound having a plurality of hydroxyl functions, either as hydroxy groups or as epoxy groups, and no polyester group. Preferred hydroxy-containing fatty acid esters are partial fatty acid esters of styrene-allyl alcohol copolymers, and partial fatty acid esters of epoxy resins, e.g. partial fatty acid esters of polyglycidyl-polyhydroxy - ethers of polyhydric phenols. The polyhydric phenol may be bisphenol A which may be reacted with epichlorohydrin to form the epoxy resin. In the examples, linseed oil fatty acid and coconut oil fatty acid are the fatty acids employed and the polycarboxylic acids or anhydrides employed are phthalic, maleic and trimellitic anhydrides and itaconic and succinic acids. A binding agent, dilutable with water, may be prepared by neutralizing at least 60% of the free carboxyl groups of the fatty acid ester resin, for instance with aqueous solutions of sodium hydroxide, ammonia, 2-amino-1 butanol, tri-ethylamine, triethanol amine or morpholine. To increase the solubility a lyotropically active agent, e.g. butanol, pentanol or butoxyethanol, may be added. The binding compositions may be used as such or mixed with other known binder compositions.

Description

Method for producing a water-dilutable fatty acid ester plastic.

The present invention relates to a method for the production of fatty acid ester plasters, suitable for the production of binders, which can be diluted with water for use in coating preparations, printing inks, glues and impregnation agents.

In the paint, varnish and lacquer industry, water is constantly used instead of organic solvents. Water has several advantages, it is cheap, non-flammable, non-toxic and it is available everywhere.

A major difficulty, however, is finding binders that can be diluted with water, without the use of emulsifiers that interfere with film formation, and that satisfy all the requirements for a good emulsifying binder, such as: stability of the liquid paint, good drying properties, formation of a continuous film with a good gloss, good adhesion, water resistance and resistance to weather and wind, ability to introduce the amount of pigment required for finish coating without affecting detrimental to the gloss of the dried coating, the possibility of being able to produce primer coatings, which contain a significant amount of pigment and fillers, which coatings, despite the large amount of pigment, do not show any brush marks after drying,

and other requirements are also taken into account"

All these requirements cannot be satisfied by binders based on the well-known drying or semi-drying oils, such as linseed oil, soya bean oil or dehydrated castor oil, which have been made dilutable with water by introducing carboxyl groups into the fatty acid chains and by subsequently converting these into salt groups, e.g. with ammonia, as described by E.T.Clocker in US Patents 2,188,882 through 2,188,890.

In order to satisfy the aforementioned requirements, it has been proposed to use chemically modified oils. Even then, however, difficulties arise, because it is not easily possible to produce the known chemically modified oils that are dilutable with water and at the same time ensure that their original properties are maintained, especially since the chemically modified oils have to be further modified on a in such a way that they give extremely highly dispersed clear or at least substantially clear solutions when diluted with water.

It has now been found that a water-dilutable fatty acid ester plastic containing free carboxyl groups can be prepared by reacting 35 to 65% of the carboxyl groups in an anhydride of a dicarboxylic acid with a hydroxy-containing fatty acid ester of an aromatic compound having a plurality of hydroxyl functions , either as hydroxy groups or as epoxy groups, and no polyester groups,— and at least 60% of the free carboxyl groups in the product are neutralized with a volatile nitrogen base.

In this context, the polyester group means the esterified radical of a polycarboxylic acid and a hydroxyl function means a reactive function capable of reacting with the carboxyl group of an anhydride of a carboxylic acid to give an ester function. Well-known hydroxyl functions defined in this way are hydroxyl groups and epoxy groups. For the sake of brevity, the "aromatic" compounds which exhibit a plurality of hydroxyl functions as defined above shall be referred to in the following as "polyalcohols".

Preferred hydroxy-containing fatty acid esters are partial fatty acid esters of a copolymer of styrene and allyl alcohol, and partial fatty acid esters of epoxy resins, e.g. partial fatty acid esters of polyglycidyl polyhydroxy ethers of polyhydric phenols.

A suitable polyhydric phenol is e.g. bis-phenol A, i.e. 2,2-bis-(4-hydroxyphenyl)-propane.

An epoxy resin prepared from bis-phenol A and epichlorohydrin can be represented by the following formula:

where 0 - A - 0 represents the bisphenol group, n means 0, 1, 2, etc.,

ie when n is greater than 0, free hydroxyl groups will also be available for the esterification in addition to the hydroxyl functions which are present as epoxy groups.

The partial fatty acid esters can be prepared by reacting the copolymer of styrene and allyl alcohol or the epoxy resin with less than the equivalent amount of a fatty acid.

It has been shown that with the help of anhydrides of polycarboxylic acids, the hydroxyl groups in the partial fatty acid esters of the aromatic compounds which have a majority of hydroxyl functions can be completely or partially converted into acid ester groups in a simple way without gelatinization. According to the invention, these acid esters can be made soluble in water in a high degree of dispersion by neutralization without the use of disturbing emulsifiers. The application of the binders according to the invention in aqueous highly dispersed solutions on a surface, e.g. by brushing, spraying or electrophoretic precipitation forms after drying or curing films which have essentially the same good properties as the films of the original partial fatty acid esters obtained from organic solutions. Particularly valuable

le properties that are achieved in practice by the partial fatty acid esters of the aromatic polyalcohols include: good adhesion, hard-

heat and elasticity.

Particularly suitable for the method according to the invention are intra-molecular acid anhydrides, such as e.g. phthalic anhydride, maleic anhydride, not only because the anhydrides are more soluble in an organic medium, but especially because a carboxyl group in the anhydride group reacts

reacts particularly easily with the OH groups in the aromatic polyalcohols, particularly esterified with fatty acids. This makes it possible to produce acid esters using anhydrides essentially without the formation of neutral esters. Thus, essentially no carboxyl group that is introduced will . for the formation of the salt, is lost and the viscosity of the binder does not increase to an undesirable degree, as is the case when di-.V or polyesters are formed.

A binder, dilutable with water, can be produced by neutralizing at least 60% of the free carboxyl groups of an ester plastic produced in the above-described manner, e.g. with aqueous solutions of sodium hydroxide, ammonia, 2-amino-l-butanol, tri-ethylamine, triethanolamine or morpholine. Volatile nitrogen bases are preferred, because they evaporate when the films are dried or hardened by heat, which results in an improved water resistance of the film.

To increase the solubility, i.e. the degree of dispersion in water, the acid esters of the partial fatty acid esters can be mixed with a lyotropically active agent before neutralization. The most suitable are lyotropically active solvents such as butanol, pentanol or butoxyethanol, of which 10 to 50% by weight is preferably added, most advantageously before the conversion of the acid groups with the aqueous base into salt groups. The binder compositions which are dilutable with water and which are obtained according to for the new method, can be used as such or, if desired, mixed with other, known binder compositions, which are dilutable with water, such as e.g. emulsions of polyvinyl acetate, styrene-butadiene, etc.

The invention shall be clarified by a number of examples. Parts and percentages are based on weight.

Example I

A polyglycidyl polyether of 2,2-bis(4-hydroxyphenyl)propane with an epoxy equivalence of 500 and an acid equivalent weight of 130 and two hydroxyl groups per molecule, was used as an aromatic polyalcohol.

1000 g of this polyalcohol, which contained two hydroxy groups as such and four hydroxy functions in anhydride form, namely as epoxy groups, was heated under nitrogen to 220°C with good stirring with 566 g of distilled linseed oil fatty acid. After heating for 1 hour at 220°C, the acid number (ie the number of mg of potassium hydroxide required to neutralize 1 g of the heated mixture) was 9.2. The partial fatty acid ester which contained approx. 4 hydroxy groups per molecule, was cooled to 130°C. After adding 279 g of phthalic anhydride (this amount is required to convert one third of the remaining hydroxy groups to acid ester groups), the temperature was increased to 150°C with vigorous stirring in a nitrogen atmosphere. After 20 minutes the acid value was 65, i.e. all the phthalic anhydride was bound as half-esters. 100 g of the reaction product was then diluted with 50 g of 2-butoxyethanol and neutralized at 40 C by the addition of 19.5 g of ammonia, which contained 10% NH2. The resulting product could be diluted with water in all proportions to clear solutions.

After 0.05% Co and 0.05% Mn, based on the non-volatile binder, had been added as drying agents in the form of naphthenates dissolved in 2-butoxyethanol to the aqueous solution, the varnish, applied in a layer of 75 thickness in moist state on a glass plate, which dried to a completely homogeneous clear film. After 1 hour, the condition "dust dry" had already been reached. The hardness, adhesion and elasticity of the hard dry films were very good.

Example II

A partial fatty acid ester was prepared as described in Example I, but using 837 g of phthalic anhydride instead of 279 g to convert all the hydroxy groups still present in the half-ester groups. After heating at 150°C for 20 minutes, the acid number was 141 (theoretical: 129). After the reaction product had been diluted with 40% 2-butoxyethanol, dimethylethanolamine was added (19.3 per 100 g of the non-volatile binder) to neutralize 90% of all acid groups present. The dimethylethanolamine was added as an aqueous solution containing 80% amine. The product was dilutable with water in all conditions; a 50% aqueous solution to which had been added 0.1% Co as a desiccant and applied in a layer of 75 µm thickness in the wet state and dried to give a completely clear film.

In the same way as with known binders diluted with organic solvents, the drying can also be accelerated in this case by using higher temperatures: the amine evaporates faster and the oxidation polymerization is accelerated.

Example III

In this experiment, a resinous copolymer of styrene and allyl alcohol with a molecular weight of 1150 and 0.45 hydroxy equivalents was used as aromatic polyalcohol. 100 g. 1150 g of this aromatic poly-alcohol was heated under nitrogen together with 200 g of coconut fatty acid (with this quantity 20% of the OH groups present can be esterified) for 1 hour at 200°C. The acid number was 8.7. 76 g of phthalic anhydride was added at 130°C to 1000 g of this partial fatty acid ester; the mixture was then heated for 35 minutes at 175°C; the acid number was then 34 in agreement with theory. 50 g of 2-butoxyethanol and 9.6 g of triethanolamine were added to 100 g of the reaction product, i.e. all carboxyl groups were converted into salt groups. It was possible to dilute the resulting product with four times the volume of water without any cloudiness occurring.

80 parts of a solution of 50% concentration of the above product was mixed with 20 parts of "Resloom M 80" (a 50% by weight aqueous solution of a methylol-melamine resin etherified with methanol). The clear mixture, which remained clear even when diluted with water, was applied to a glass plate and stored for 1 hour at 130°C. The result was a strongly adhesive crystal clear film, which was hard and reasonably elastic.

Example IV

222 g of the polyalcohol used in example III was

mixed with 140 g of linseed oil fatty acid at 120°C. After the addition of 0.4 g of NaOH, the temperature was increased to 220°C with vigorous stirring while passing through nitrogen. After 1% hour the acid number had decreased to 6, i.e. half of the originally present OH groups had been esterified with fatty acid., 24.5 g of maleic anhydride was added to the

partial fatty acid esters which had been cooled to 100°C, and the reaction mixture was then held between 110 and 115°C for 20 minutes. The mixture was then heated at between 145 and 150°C for 30 minutes to convert all the maleic anhydride to half-esters. It was possible to dilute the binder, which had an acid value of 45 (theoretical: 43), with water in all proportions after addition of 38% 2-butoxy-ethanol and neutralization with 5.5% ammonia containing 25% NH-j -After 0.05% Co and 0.05% Mn, based on non-volatile binders, had been added as drying agents in the form of adhesives, the 50% diluted varnish was applied to a glass plate in a 75 µm thick layer and dried for 1 hour at 130 o C. The result was a clear, moderately hard, very elastic film.

Claims (1)

Process for the production of a water-dilutable fatty acid ester plastic containing free carboxyl groups, characterized in that 35 to 65% of the carboxyl groups in an anhydride of a dicarboxylic acid are reacted with a hydroxy-containing fatty acid ester of an aromatic compound with a plurality of hydroxyl functions, either as hydroxy groups or as epoxy groups, and no polyester groups, and at least 60% of the free carboxyl groups in the product are neutralized with a volatile nitrogen base.