SUCCINIC ACID ALKYL ESTER MIXTURES USED AS PLASTICIZERS. The present invention relates to novel succinic acid(cas:110-15-6) alkyl ester mixtures and to the use there as plasticizers for plastic materials. The claimed mixtures are characterised by having good plasticizing effects which lead the products produced with the mixtures to have improved application properties.

There is therefore a requirement for phthalate-free plasticizers for plastics. Interest here is focused on plasticizers based on renewable raw materials, as a result of issues relating to climate, sustainability, and restricted availability of fossil-derived feedstocks. Plasticizers based on succinic acid(cas:110-15-6) could meet these requirements.

Relatively recent developments in the field of “green” technologies have provided an inexpensive and effective route to biobased succinic acid, and it has therefore become possible to use biobased succinic acid(cas:110-15-6) on an industrial scale for the production of plasticizers. In this connection, succinic acid(cas:110-15-6) has been identified as one of 12 highest-value sugar-based building blocks for syntheses (cf. for example T. Werpy and G. Petersen et al. in Top Value Added Chemicals From Biomass, Volume I: Results of Screening for Potential Candidates from Sugars and Synthesis Gas, page 1)

Particular materials that are of great interest with respect to sustainability and use of chemicals derived from renewable materials are the esters of succinic acid(cas:110-15-6) with fatty alcohols, non-restrictive examples being 1-octanol, 1-decanol and 1-dodecanol, since these alcohols are also accessible by the biological route, e.g. through hydrogenation of fatty acids derived from vegetable oils.

The use of esters of succinic acid(cas:110-15-6) as plasticizers for PVC is described by LeCaptain et al. in Polym. Bull. (2010) 65:589-598 in the paper “Poly(vinyl chloride) plasticized with succinate esters: synthesis and characterization”. That document describes dioctyl succinate (DOS), dihexyl succinates (DHS), dibutyl succinates (DBS), and diethyl succinates (DES). Infrared (IR)-, differential scanning calorimetry (DSC)-, and dynamic-mechanical analysis (DMA) are used to determine the compatibility of the esters in PVC and their potential as replacement for phthalates in qualitative terms. Nothing is said about performance tests or about issues such as migration out of, and susceptibility to evaporation from, the plasticized polymer, or about its long-term service properties.

Investigations have revealed that di-n-octyl succinate (CAS No 14491-66-8) has good plasticizer effectiveness in relation to hardness reduction. However, the volatility of this chemical is higher than that of the corresponding adipic ester; this can be explained via the lower molecular weight of the succinate. Di-n-decyl succinate (CAS No. 10595-82-1) does not have good plasticizing action; this is possibly the cause of the melting point of >20° C. and of the crystallization of the solid plasticizer in the final product. At room temperature, di-n-dodecyl succinate (CAS No 5980-15-5) is a solid with poor processibility.

The succinic esters mentioned, known from the prior art, do not meet all of the aspects of the desired requirements placed upon a good plasticizer, in particular in relation to plasticizer effectiveness and long service life of the final products, and in this regard they remain unsatisfactory.