Tripentyl esters of trimellitic acid

Abstract

Tripentyl esters of trimellitic acid, especially mixtures of triisopentyl esters of trimellitic acid comprising isomeric pentyl radicals in which more than 5 mol % of the isomeric pentyl radicals incorporated in the ester mixture are branched, have good compatibility with PVC and PVC-containing polymers and simultaneously exhibit a lesser tendency to migrate.

Claims

1. A composition, comprising: trialkyl esters of trimellitic acid; wherein the trialkyl radicals of the trialkyl esters are a mixture of isomeric pentyl radicals, wherein more than 5 mol % of the isomeric pentyl radicals are branched, and at least 50 mol % of the branched isomeric pentyl radicals are 2-methylbutyl radicals.

2. The composition according to claim 1, wherein at least 15 mol %, of the isomeric pentyl radicals of the trialkyl ester groups are branched.

3. The composition according to claim 1, wherein more than 10 mol % and less than 95 mol % of the isomeric pentyl radicals are linear.

4. A process for preparing the composition according to claim 1, comprising: reacting trimellitic acid and/or a trimellitic acid derivative with a mixture of isomeric pentanols; wherein more than 5 mol % of the isomeric pentyl radicals in the mixture of isomeric pentanols are branched isomeric pentyl radicals, and at least 50 mol % of the branched isomeric pentyl radicals are 2-methylbutyl radicals.

5. The process according to claim 4, wherein, during the reacting, the reaction mixture containing the trimellitic acid and/or the trimellitic acid derivative is heated to boiling and, after attaining boiling temperature, adding at least 0.2 molar equivalent of the amount of mixture of isomeric pentanols needed to introduce all the isomeric pentyl radicals incorporated in the ester mixture.

6. The process according to claim 4, wherein at least one isomerically pure tripentyl ester of trimellitic acid and at least one mixture of triisopentyl esters of trimellitic acid comprising isomeric pentyl radicals are mixed with one another, such that more than 5 mol % of the isomeric pentyl radicals are branched, and at least 50 mol % of the branched isomeric pentyl radicals are 2-methylbutyl radicals.

7. A plasticizer, or a plasticizer composition comprising the composition according to claim 1 and at least one further polymer-plasticizing compound.

8. A plasticizer composition comprising the composition according to claim 1 and at least one further polymer-plasticizing compound selected from the group consisting of alkyl benzoates, dialkyl adipates, glycerol esters, trialkyl citrates, acylated trialkyl citrates, glycol dibenzoates, trimellitates having radicals different from the isomeric pentyl radicals of claim 1, dialkyl terephthalates, dialkyl phthalates, esters of furandicarboxylic acid, dialkanoyl esters of dianhydrohexitols, epoxidized fatty acid alkyl esters, polyadipates, and dialkyl esters of cyclohexane-1,2-, -1,3- or -1,4-dicarboxylic acid.

9. A polymer composition comprising the composition according to claim 1 wherein the polymer composition comprises one or more polymers selected from the group consisting of polyvinyl chloride, copolymers of vinyl chloride with vinyl acetate or with butyl acrylate, polyalkyl methacrylate (PAMA), polyvinyl butyral (PVB), chlorosulphonated polyethylene, polyurethane, polysulphides, polylactic acid (PLA), polyhydroxybutyral (PHB) and nitrocellulose.

10. A polyvinyl chloride polymer (PVC) or a PVC copolymer comprising the composition of claim 1.

11. A plasticized product comprising the composition of claim 1, wherein the product is selected from the group consisting of adhesives, sealing compounds, coating materials, paints, inks, plastisols, foams, synthetic leather, floor coverings, roofing membranes, underbody protection, fabric coatings, cables, wire insulation, hoses, extruded articles, films, automotive interior, wall coverings, liquid inks, toys, contact sheets, food packaging or medical articles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 below is intended to serve for comprehension of the determination method elucidated. Of relevance here is the assigned numbering of the carbon atoms of the methyl groups and the methylene groups adjacent to the oxygen atom in an n-pentyl radical (C.sup.14H.sub.3 and C.sup.10H.sub.2), in a 2-methylbutyl radical (C.sup.22H.sub.3, C.sup.23H.sub.3 and C.sup.19H.sub.2) and in a 3-methylbutyl radical (C.sup.18H.sub.3, C.sup.18H.sub.3 and C.sup.15H.sub.2).

(2) The resultant .sup.1H NMR spectra of the mixtures of triisopentyl esters of trimellitic acid have, in the range from 0.5 ppm up to the minimum of the lowest valley in the range from 0.7 to 1.2 ppm, resonance signals which are formed by the signals of the hydrogen atoms of the methyl group(s) of the isomeric pentyl substituents (C.sup.14H.sub.3, C.sup.18H.sub.3, C.sup.18H.sub.3, C.sup.22H.sub.3, C.sup.23H.sub.3). The signals in the range of chemical shifts from 3.60 to 4.55 ppm can be assigned essentially to the hydrogen atoms of the methylene group adjacent to the oxygen in the alcohol radical (C.sup.10H.sub.2, C.sup.15H.sub.2, C.sup.19H.sub.2). In this context, the protons on C19 are subject to a high-field shift because of the adjacent tertiary carbon atom and appear between 3.95 and 4.29 ppm, while the protons on C10 and C15 give signals at lower shifts of 4.29 to 4.55 ppm.

(3) Quantification is effected by comparative determination of the area beneath the respective resonance signals, i.e. the area enclosed by the signal from the baseline. Commercial NMR software has program functions for integration of the signal area. In the present NMR spectroscopy study, the integration was conducted with the aid of the TopSpin software, Version 3.1.

(4) To determine the mean degree of branching of the isomeric pentyl radicals in the mixture according to the invention, the integral value of the signals in the range from 0.68 to 1.18 ppm (I(CH.sub.3)) is first divided by the integral value of the signals in the range from 3.95 to 4.55 ppm (I(OCH.sub.2)). In this way, an intensity ratio which states the ratio of the number of hydrogen atoms present in a methyl group to the number of hydrogen atoms present in a methylene group adjacent to an oxygen is obtained. Since three hydrogen atoms per methyl group and two hydrogen atoms in every methylene group adjacent to an oxygen are present, the intensities have to be divided by 3 and 2 respectively, in order to obtain the ratio of the number of methyl groups to the number of methylene groups adjacent to an oxygen in the pentyl radical. Since a linear n-pentyl radical having only one methyl group and one methylene group adjacent to an oxygen does not contain any branch and accordingly has to have a degree of branching of 0, it is necessary to subtract the quantity of 1 from the ratio.

(5) The mean degree of branching DB can thus be calculated by the formula
DB=2/3*I(CH.sub.3)/I(OCH.sub.2)1
from the intensity ratio measured. In this formula, DB means mean degree of branching, I(CH.sub.3) means area integral assigned to the methyl hydrogen atoms, and I(OCH.sub.2) means area integral of the methylene hydrogen atoms adjacent to the oxygen.

(6) The product may contain 2-methylbutyl radicals and 3-methylbutyl radicals each having a degree of branching of 1, and also n-pentyl radicals having a degree of branching of 0, which means that the maximum mean degree of branching of any triisopentyl ester is always 1. From the deviation of the mean degree of branching from the value of 1, it is therefore possible to determine the molar proportion of n-pentyl radicals (x.sub.pentyl) in the molecule.
x.sub.pentyl=1DB

(7) The proportion of 2-methylbutyl radicals can be calculated with the aid of the integration of the baseline-separated signals in the range from 3.95 to 4.55 ppm. Here too, the signals of the protons on C19 (C.sup.19H.sub.2; multiplet between 3.95 and 4.28 ppm) are separated from the signals of the protons on C10 and C15 (C.sup.10H.sub.2 and C.sup.15H.sub.2; multiplet between 4.29 and 4.55 ppm) in the minimum of the valley cut between the signal groups.

(8) The molar proportion of 2-methylbutyl radicals (x.sub.2-methylbutyl) can be calculated by the formula
x.sub.2-methylbutyl=I(OC.sup.19H.sub.2)/I(OCH.sub.2)
by forming the ratio of the intensity of the signals for the OC.sup.19H.sub.2 protons (I(OC.sup.19H.sub.2)) to the intensity of all OCH.sub.2 protons (I(OCH.sub.2)).

(9) The molar proportion of 3-methylbutyl radicals (x.sub.3-methylbutyl) is thus calculated from the difference between the two previous molar proportions and 1.
x.sub.3-methylbutyl=1x.sub.2-methylbutylx.sub.pentyl

(10) TABLE-US-00001 TABLE 1 Preparation of trimellitates by esterification of trimellitic anhydride Composition: Purity proportion of by radicals in Alcohol A m.sub.1(A) m.sub.2(A) Reaction GC the ester mixture Ex. [molar ratio] [g] [g] time t [h] [%] [molar ratio] 1 n-butanol 416.9 352.1 5 97.8 n-butyl 2 n-pentanol 497.4 497.4 9 99.2 n-pentyl 3 n-hexanol 574.8 574.8 2.5 98.0 n-hexyl 4* 2- 495.8 495.8 8.5 99.3 2-methylbutyl/ methylbutanol/ n-pentyl n-pentanol 0.20:0.80 1:4 5* 2- 396.7 471.0 8 98.8 2-methylbutyl/ methylbutanol/ n-pentyl n-pentanol 0.50:0.50 1:1 6* 2- 495.8 495.8 7 98.9 2-methylbutyl/ methylbutanol/ 3-methylbutyl/ 3- n-pentyl methylbutanol/ 0.33:0.33:0.34 n-pentanol 1:1:1 7* 2- 495.8 495.8 8 99.0 2-methylbutyl/ methylbutanol/ n-pentyl n-pentanol 0.79:0.21 4:1 *inventive

Example 8: Production of Dryblends, Rolled Sheets and Pressed Plaques

(11) The test specimens required for the examples which follow are produced by dry mixing (dryblend production), calendering (rolling) and pressing of the following formulations:

(12) TABLE-US-00002 TABLE 2 Dryblend formulation phr PVC (Solvin S271 PC; from Solvay) 100 Ester or ester mixture from Example 1, 2, 3, 4*, 5*, 6*, 7*, 67 Tri-2-ethylhexyl trimellitate or DINP Co-stabilizer-epoxidized soya bean oil (Drapex 39 ex Galata) 3 Thermal stabilizer based on Ba/Zn (Mark BZ 965 ex Galata) 2 Processing aid-fatty acid salts (Mark CD 41-0137 ex Galata) 0.4 phr: parts per hundred parts resin Tri-2-ethylhexyl trimellitate: trioctyl trimellitate ex Sigma Aldrich, purity 99% DINP: Vestinol 9 ex Evonik Industries, purity >99%

(13) With dry mixtures, which are referred to as dryblends, it is possible, for example, after thermoplastic processing (e.g. calendering or extrusion) to produce cable and wire insulation, hoses or floors and roofing membranes.

(14) The dryblends were produced in a Brabender planetary mixer. A thermostat (Lauda RC6) ensured temperature control of the mixing vessel in the planetary mixer. A PC recorded the data sent by the mixer.

(15) The Winmix software was used to set the following parameters in the Brabender planetary mixer:

(16) TABLE-US-00003 Speed program: active Profile: speed 50 rpm; hold time: 9 min; rise time (of speed): 1 min; speed 100 rpm; hold time: 20 min Temperature: 88 C. Measurement range: 2 Nm Damping: 3

(17) The temperature in the mixing vessel was 88 C. after the one-hour equilibration period. Once the planetary mixer had conducted an internal calibration, the solid constituents (PVC, stabilizer), which had been weighed out beforehand in four times the amount (four times the amount in g based on Table 2 in phr) into a PE cup on a balance (Mettler XS6002S), were fed to the mixing vessel via a solids funnel and the filling stub present in the Brabender mixing vessel. The program was started and the powder mixture was stirred and equilibrated in the mixing vessel for 10 minutes, before the liquid constituents, which had likewise been weighed out in four times the amount in a PE cup on the balance, were fed in via a liquid funnel and the filling stub present in the Brabender mixing vessel. The mixture was stirred in a planetary mixer for a further 20 minutes. After the program had ended, the finished dry mixture (dryblend) was removed.

(18) These dryblends were used to produce rolled sheets. The rolled sheets were produced on a Collin W150 AP calender. The Collin calender has an automatic sample turner and its temperature is controlled by means of an additional oil thermostat (Single STO 1-6-12-DM). Control was effected by means of Collin software.

(19) A five-stage program was used to produce the rolled sheet:

(20) TABLE-US-00004 Gap Temp. Duration width Speed Stage Designation [ C.] [s] [mm] [rpm] 1 Plastification of the 165 60 0.2 5 dryblend 2 Increasing the gap size 165 30 0.5 20 3 Activation of the sample 165 170 0.5 20 turner 4 Rolled sheet optimization 165 30 0.5 25 5 Rolled sheet removal 165 60 0.5 7

(21) On attainment of the roll temperature, the roll gap was calibrated. To start the measurement, the roll gap was adjusted to 0.2 mm. 160 g of each dryblend were weighed in and introduced into the roll gap with the rollers stationary. The program was started. The rollers started with a circumferential speed of 5 rpm and a friction of 20%. After about 1 min, the plastification was complete for the most part, and the roll gap was increased to 0.5 mm. Homogenization was effected 6 times by means of the automatic turning unit in the calender. After about 6 min, the rolled sheet was removed from the roller and cooled.

(22) The pressed plaques were produced with a Collin laboratory press. The prefabricated rolled sheets (see above) were used to produce the pressed plaques. The lateral edges of the rolled sheets were removed with the aid of a cutting machine, then the rolled sheet was cut into pieces of about 14.514.5 cm in size. For pressed plaques of thickness 1 mm, 2 rolled sheet pieces in each case were placed one on top of the other into the stainless steel pressing frame of size 1515 cm.

(23) A three-stage program was used to produce the pressed plaques:

(24) TABLE-US-00005 Stage Designation Temp. [ C.] Pressure [bar] Duration [s] 1 Initial pressing 175 5 60 2 Pressing 175 200 120 3 Cooling 40 200 270

(25) The excess compression lip was removed after the press plaques had been produced.

Example 9: Plasticizer Absorption in the Dryblend

(26) During the production of each dryblend, the rate of plasticizer absorption was determined, which serves as a measure of processability. A short plasticizer absorption time results in practice in low processing temperatures or elevated product throughput in an existing system.

(27) The degree of plasticizer absorption was determined via the torque of the mixer as a function of time in the course of dryblend production.

(28) For this purpose, by means of the hard- and software described in Example 8 for the dryblend production, the torque of the mixer was plotted against time. The torque rose to a maximum value from the addition of plasticizer or the plasticizer composition and dropped again from this, in order finally to attain a constant value or to drop further only minimally from what is called the dry point.

(29) The period of time between the addition of the plasticizer or the plasticizer composition and the dry point is referred to as time t for plasticizer absorption.

(30) TABLE-US-00006 TABLE 3 Dryblend plasticizer absorption Time t Radical(s) in the [min] for trialkyl trimellitate plasticizer (mixture) absorption Ester from Example 3 n-hexyl 4.9 Trioctyl trimellitate ex Sigma 2-ethylhexyl 9.0 Aldrich, purity 99% Ester mixture from 2-methylbutyl/n-pentyl 4.1 Example 4* Molar ratio 0.20:0.80 Ester mixture from 2-methylbutyl/n-pentyl 4.4 Example 5* Molar ratio 0.50:0.50 Ester mixture from 2-methylbutyl/3-methylbutyl/ 4.5 Example 6* n-pentyl Molar ratio 0.33:0.33:0.34 Ester mixture from 2-methylbutyl/n-pentyl 4.6 Example 7* Molar ratio 0.79:0.21 Vestinol 9 ex Evonik Comparative substance: 5.4 Industries, purity >99% diisononyl phthalate (DINP) *inventive

(31) In the case of the inventive mixtures of triisopentyl esters of trimellitic acid from Examples 4*, 5*, 6* and 7*, homogeneous dryblends were formed within a shorter time than in the case of diisononyl phthalate, the tri-n-hexyl ester of trimellitic acid (from Example 3) and the tri-2-ethylhexyl ester of trimellitic acid. It can be concluded directly from this that mixtures according to the invention have better processability with PVC than DINP, than the tri-n-hexyl ester of trimellitic acid and than the tri-2-ethylhexyl ester of trimellitic acid. Moreover, it can be inferred from the values in Table 3 that processability with PVC in mixtures according to the invention rises with the proportion of linear pentyl radicals in the pentyl radicals incorporated in the ester mixture.

(32) The tri-2-ethylhexyl ester of trimellitic acid has a particularly high plasticizer absorption time and is therefore unsuitable as a plasticizer for numerous PVC applications, which is the reason why the migration properties thereof were not determined hereinafter.

Example 10: Determination of Migration Properties

(33) The test for determination of the migration properties of a test specimen comprising a plasticizer or a plasticizer composition allows conclusions as to how plasticizer-containing formulations behave in application on direct contact with other materialsfor example on contact between a plasticized PVC layer and a rigid PVC layer (called multilayer systems). If, for example, plasticizer migrates within an article from a plasticized polymer-containing component to a non-plasticized polymer-containing component, this can lead to unwanted embrittlement of the plasticized component and softening of the non-plasticized component, which can lead to leaks, declining stability and reduced service life of the article. Accordingly, a low migration tendency is an important property for a plasticizer usable in numerous applications or a corresponding component of a plasticizer composition.

(34) The migration tendency of the inventive mixtures of triisopentyl esters of trimellitic acid and the comparative substances DINP, tri-n-butyl trimellitate, tri-n-pentyl trimellitate and tri-n-hexyl trimellitate was determined as follows:

(35) The press plaques of thickness 1 mm produced in Example 8 were cut into blanks of 100 mm.Math.100 mm and stored at 23 C. for 24 hours before their mass was determined.

(36) In accordance with the method DIN EN ISO 177 (published 1999), the blanks were positioned between two contact sheets (Example 10.1: high-impact polystyrene (HIPS) (manufacturer: VINK Kunststoffe; 1001002 mm plaques); Example 10.2: non-plasticized PVC (rPVC) (manufacturer: VINK Kunststoffe; 1001002 mm plaques)) which had the same dimensions as the blanks apart from a thickness of 2 mm, and two of the layer constructions that arise in this way were stacked one on top of the other. These stacks each comprising blanks of the same plasticizer, weighted down with a weight of 2 kg, were stored in an oven (70(+/1) C.) for 28 days.

(37) After 14 days and after 28 days, the loss of weight of each blank was determined (percent weight loss based on the original weight). After the first measurement, the stacks were reassembled again as before.

(38) Table 4 shows the averaged values of the weight loss of the test specimens.

(39) TABLE-US-00007 TABLE 4 Migration into high-impact polystyrene (HIPS) after 14 and 28 days Difference Difference in in weight weight Radical(s) in the after after trialkyl trimellitate 14 days 28 days Blank contains . . . (mixture) in % in % Ester from Example 1 n-butyl 5.8 8.0 Ester from Example 2 n-pentyl 5.1 6.9 Ester from Example 3 n-hexyl 3.7 5.6 Ester mixture from 2-methylbutyl/n- 3.6 5.5 Example 4* pentyl Molar ratio 0.20:0.80 Ester mixture from 2-methylbutyl/n- 2.0 3.2 Example 5* pentyl Molar ratio 0.50:0.50 Ester mixture from 2-methylbutyl/ 2.5 3.7 Example 6* 3-methylbutyl/ n-pentyl Molar ratio 0.33:0.33:0.34 Ester mixture from 2-methylbutyl/n- 1.6 2.7 Example 7* pentyl Molar ratio 0.79:0.21 Vestinol 9 ex Evonik Comparative substance: 11.2 14.6 Industries, purity diisononyl phthalate >99% (DINP) *inventive

(40) TABLE-US-00008 TABLE 5 Migration into rigid PVC (rPVC) after 14 and 28 days Difference Difference in in weight weight Radical(s) in the after after trialkyl trimellitate 14 days 28 days Blank contains . . . (mixture) in % in % Ester from Example 1 n-butyl 9.3 11.7 Ester from Example 2 n-pentyl 9.0 11.3 Ester from Example 3 n-hexyl 8.0 10.1 Ester mixture from 2-methylbutyl/n- 6.2 8.3 Example 4* pentyl Molar ratio 0.20:0.80 Ester mixture from 2-methylbutyl/n- 5.9 7.9 Example 5* pentyl Molar ratio 0.50:0.50 Ester mixture from 2-methylbutyl/ 7.4 9.4 Example 6* 3-methylbutyl/ n-pentyl Molar ratio 0.33:0.33:0.34 Ester mixture from 2-methylbutyl/n- 5.6 7.5 Example 7* pentyl Molar ratio 0.79:0.21 Vestinol 9 ex Evonik Comparative substance: 7.7 9.7 Industries, purity diisononyl phthalate >99% (DINP) *inventive

(41) It is apparent from Tables 4 and 5 that the inventive mixtures of triisopentyl esters of trimellitic acid consistently have a lower tendency to migrate than DINP and n-butyl, n-pentyl and n-hexyl triesters of trimellitic acid. In addition, it can be inferred from a comparison of the measurements for the blanks comprising the inventive ester mixtures from Examples 5, 6 and 8 that the migration tendency of the mixtures according to the invention decreases with rising proportion of the branched pentyl radicals in the pentyl radicals incorporated in the ester mixture. As the comparison of the measurements for the blanks comprising inventive ester mixtures from Examples 5 to 7 shows, a high proportion of 2-methylbutyl radicals in the branched isomeric pentyl radicals incorporated in the ester mixture has a positive effect on a low migration tendency.

(42) European patent application 15187128.2 filed Sep. 28, 2015, is incorporated herein by reference.

(43) Numerous modifications and variations on the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.