The present invention relates to new basic calcium carboxylate compositions, a method for their preparation and their use as polymer stabilisers, particularly stabilisers for polyvinyl chloride.

Traditionally lead salts have been used to stabilise polyvinyl chloride and it has been proposed to replace these with neutral calcium salts such as calcium oleate and calcium stearate. These salts however have relatively low calcium contents (of the order of 6%) so large amounts are needed to impart the stability.

Basic calcium carboxylates are known in many forms and are commonly used as additives in various lubricant systems and to impart anticorrosion properties to coatings such as temporary and permanent coatings for metals and as polymer stabilisers since they have a higher calcium level as possible in these products to reduce the amount of additive required to provide the desired calcium level. It

1 has however proved difficult to develop a commercial process for the production of high calcium content calcium carboxylates prior to the use of various carboxylic acid mixtures as raw materials as described in our European Patent 0234149.

The process of European Patent 0234149 produces an oil solution of a high calcium content calcium carboxylate which is not useful in applications where the oil will act as a contaminant such as a plastics stabiliser. Furthermore the presence of the oil solvent increases the bulk and thus transportation costs. Other processes use organic solvents which can impart an undesirable odour to the final product.

There is therefore a need for a basic calcium carboxylate which may be incorporated into polymers, particularly as a stabiliser for polyvinyl chloride.

We have now developed new calcium superbase soaps formulations which do not possess the disadvantages of the known formulations, which have a high calcium content of the order of 10% or even higher, and which are compatible with polyvinyl chloride and the other components present therein.

The present invention therefore provides a solution in a plasticiser ester of a calcium superbase soaps in the form of calcium carbonate and calcium carboxylates, the carboxylic acids consisting of a mixture or otherwise of saturated organic carboxylic acids containing from 7 to 13 carbon atoms, having the following characteristics:

a linear acid content of between 0 and 40% by weight,

• a content of acids which are branched on carbon 2 of between 0 and 20% by weight, and

• a content of acids which are mono- or polysubstituted on carbon 3 and/or on the carbons of higher rank, which is equal to or greater than 50% by weight.

The invention further provides a process for the manufacture of such a solution comprising producing the overbased calcium superbase salt using the plasticiser ester as the reaction medium.

The calcium superbase soaps are preferably prepared from saturated Cβ, Cg and Cio organic carboxylic acids which consist of isomeric mixtures and which are generally known as oxo acids. These oxo acids are characterized by a low linear acid content, generally less than or equal to 10% by weight, a low content of acids which are branched on carbon 2, generally less than or equal to 10% by weight, and a high content of acids which are mono- or polysubstituted on carbon 3 and/or carbons of higher rank, which is generally greater than 80% by weight. The oxo acids are obtained by hydroformylation of C7, Cβ and Cg olefins, followed by an oxidation.

Still more preferably, the calcium soaps according to the invention are prepared from the Cβ saturated carboxylic acid (that is containing 8 carbon atoms) marketed under the trademark Cekanoic, this acid consisting of an isomeric mixture of octanoic acids containing at most 10% by weight of n-octanoic acid, at most 10% by weight of Cβ acids which are branched on carbon 2 and at least 80% by weight of Cβ acids which are branched on carbon 3 and/or the carbons of higher rank. In fact, it has surprisingly been found that the use of this acid

makes it possible to obtain calcium soaps with a very high basicity of the order of 500 or higher.

Among the organic carboxylic acids which are also suitable for the present invention there may also be added the derivatives which are mono- or polysubstituted in he 3-position and/or of higher rank of the acids corresponding to heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid and dodecanoic acid. These include, for example, 3-methylhexanoic acid, isooctanoic acid, 4,5-dimethylhexanoic acid, isononanoic acid, 3,5,5- trimethylhexanoic acid, isodecanoic acid, 3-ethyloctanoic acid, isoundecanoic acid, 4-ethylnonanoic acid and isododecanoic acid. The mixture of one or more of the above-mentioned acids, whether mixed or not with their isomers, is also suitable for the present invention, it being understood that the content of linear acids does not exceed 40% and that the content of acids which are substituted on carbon 2 does not exceed 20%. We have found, in fact, that the linear acids and that the acids branched on carbon 2 lead to the formation of a viscous product, or to setting solid or, alternatively, to a precipitate which renders the product practically useless.

Suitable plasticiser ester are those typically used for plasticising polyvinyl chloride such as alkyl phthalates for example dioctyl phthalate, dinonyl phthalate and adipates and trimellitates. The ester should have a flash point above 120 ^° C, and should be compatible with polyvinyl chloride and other additives such as phosphites, UV stabilisers, other metal containing additives particularly zinc stabilisers and other plasticisers traditionally used in PVC.

We have found that solutions of the superbase calcium carboxylate in the ester may be obtained containing as much as 10 wt% calcium, typically between 5 and 10 wt%, although the viscosity tends to be higher than desirable at the higher calcium levels.

The molar ratio of calcium to the organic carboxylic acid employed in the reaction is generally between 0.55 and 2, which corresponds to a basicity of between 1.1 and 4.

It should be recalled that the basicity is equal to the ratio of equivalents of calcium to the equivalents of carboxylic acids which are employed, that is to say, to the

molar ratio of the calcium concentration to that of the carboxylic acids, multiplied by 2.

In the calcium superbase soaps according to the invention, the promoters are used in a proportion of 1 to 25% by weight of final calcium salt, and preferably in a proportion of 5 to 15%.

The present invention will be better understood by reading the following example.

Example 1

Ca(OH)2 is reacted with Cekanoic Cs acid in the presence of injected CO2 with methanol as promoter and Exxsol D40 as reaction diluent in the following proportions.

mass Ca(OH)2 96.7 g mass Exxsol D40 258.7 g mass Methanol 99.8 g mass Cekanoic Cβ 144.0 g

As described in European Patent 0234149, solid calcium salt is prepared by evaporating the solvent just by heating up the liquid sample in a cup exposed to air. Crystals are formed which then are crushed in a crucible. The resulted powder is dissolved in dinonyl phthalate and heated up to 80-120 ^' C to give a solution of 0.49 g solid in 20.07 g DINP. The solution was heated for 1 hour at 120 ^° C and the solution remained clear and yellow with no smell of alcohol showing effective stabilisation.