Hydrocarbon wax composition, method for the production thereof and use thereof as additive in rubber

Abstract

The invention relates to a hydrocarbon wax composition with superior properties as ozone- and aging-protecting additive in rubber products, the production thereof and the use thereof as ozone- and aging-protecting additive. The hydrocarbon wax composition is characterized by its distribution of hydrocarbon molecules by number of carbon atoms per hydrocarbon molecule and its distribution of branched and linear hydrocarbons.

Claims

1. A hydrocarbon wax composition comprising hydrocarbons with 15 to 110 carbon atoms, wherein 25 to 40% of the hydrocarbons are linear short chain length hydrocarbons having 20 to 30 carbon atoms; 5 to 18% of the hydrocarbons are linear medium chain length hydrocarbons having 31 to 38 carbon atoms; 25 to 40% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms; 5 to 15% of the hydrocarbons are branched short chain length hydrocarbons having 21 to 31 carbon atoms; below 5% of the hydrocarbons are branched medium chain length hydrocarbons having 32 to 39 carbon atoms; and 5 to 15% of the hydrocarbons are branched long chain length hydrocarbons having 40 to 61 carbon atoms; wherein the percentage in each case is relative to the total number of hydrocarbons having 15 to 110 carbon atoms.

2. The hydrocarbon wax composition according to claim 1, wherein 26 to 37% of the hydrocarbons are linear short chain length hydrocarbons having 20 to 30 carbon atoms.

3. The hydrocarbon wax composition according to claim 1, wherein 26 to 37% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms.

4. The hydrocarbon wax composition according to claim 1 wherein 6 to 8% of the hydrocarbons are branched short chain length hydrocarbons having 21 to 31 carbon atoms.

5. The hydrocarbon wax composition according to claim 1, wherein 6 to 12% of the hydrocarbons are branched long chain length hydrocarbons having 40 to 61 carbon atoms.

6. The hydrocarbon wax composition according to claim 1, wherein 10 to 16% of the hydrocarbons are linear medium chain length hydrocarbons having 31 to 38 carbon atoms.

7. The hydrocarbon wax composition according to claim 1, wherein 0.1 to 3.0% of the hydrocarbons are branched medium chain length hydrocarbons having 32 to 39 carbon atoms.

8. The hydrocarbon wax composition according to claim 1, further characterized by one or more of the following definitions the number of ratio of linear short chain length hydrocarbons to the linear long chained hydrocarbons is between 0.5 and 1.5; the number ratio of branched short chain length hydrocarbons to branched long chain length hydrocarbons is between 0.5 and 1.5; the number ratio of linear short chain length hydrocarbons to linear medium chain length hydrocarbons is between 1.5 and 3.5; the number ratio of linear long chain length hydrocarbons to linear medium chain length hydrocarbons is between 2.0 and 4.0; the number ratio of branched short chain length hydrocarbons to branched medium chain length hydrocarbons is between 2.5 and 6.5; the number ratio of branched long chain length hydrocarbons to branched medium chain length hydrocarbons is between 4.0 and 7.0; the number ratio of linear short chain length hydrocarbons to branched short chain hydrocarbons is between 3.0 and 6.0; the number ratio of linear long chain length hydrocarbons to branched long chain length hydrocarbons is between 3.0 and 6.0; the number ratio of linear medium chain length hydrocarbons to branched medium chain length hydrocarbons is between 6.0 and 12.0.

9. The hydrocarbon wax composition according to claim 1, wherein 10 to 30% of the hydrocarbons are branched hydrocarbons.

10. The hydrocarbon wax composition according to claim 1, wherein at least one maximum of the linear hydrocarbon molecules is between 23 to 33 carbon atoms per hydrocarbon molecule and at least one maximum of the linear hydrocarbon molecules is between 37 to 48 carbon atoms per hydrocarbon molecule; at least one maximum of the branched hydrocarbon molecules is between 23 to 33 carbon atoms per hydrocarbon molecule and at least one maximum of the branched hydrocarbon molecules is between 37 to 48 carbon atoms per hydrocarbon molecule; the maximum with the highest number of carbon atoms per hydrocarbon molecule in the range between 23 to 33 carbon atoms per hydrocarbon molecule and the maximum with the lowest number of carbon atoms per hydrocarbon molecule in the range between 37 to 48 carbon atoms per hydrocarbon molecule of linear and branched hydrocarbon molecules differ from each other by at least by 12 carbon atoms per hydrocarbon molecule; the distribution has no maximum for both, the linear and the branched hydrocarbon molecules, in the above range of the at least 12 carbon atoms per hydrocarbon molecule; and the distribution has at least one minimum for both, the linear and the branched hydrocarbon molecules, each at 30 to 36 carbon atoms per hydrocarbon molecule; and wherein in each case the maximum is the highest number of hydrocarbon molecules within a range of +/ two carbon atom per hydrocarbon molecule and the minimum is the lowest number of hydrocarbon molecules within a range of +/ two carbon atom per hydrocarbon molecule.

11. A method for obtaining wax pastilles or a wax powder comprising the following step: providing at least two hydrocarbon wax components, wherein a first hydrocarbon wax component comprises hydrocarbons with 15 to 110 carbon atoms, wherein about 60% of the hydrocarbons are linear short chain length hydrocarbons having 20 to 30 carbon atoms; and a second hydrocarbon wax component comprises hydrocarbons with 15 to 110 carbon atoms, wherein above 45% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms; mixing the hydrocarbon wax components in a molten state with each other to obtain the hydrocarbon wax composition according to claim 1; and solidifying the hydrocarbon wax composition.

12. A method according to claim 11, wherein: the second hydrocarbon wax component comprises hydrocarbons with 15 to 110 carbon atoms, wherein above 60% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms.

13. Wax pastilles or a wax powder obtained by a method according to claim 11.

14. A method of producing a rubber product, comprising: providing a hydrocarbon wax composition comprising hydrocarbons with 15 to 110 carbon atoms, wherein 25 to 40% of the hydrocarbons are linear short chain length hydrocarbons having 20 to 30 carbon atoms; 5 to 18% of the hydrocarbons are linear medium chain length hydrocarbons having 31 to 38 carbon atoms; 25 to 40% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms; 5 to 15% of the hydrocarbons are branched short chain length hydrocarbons having 21 to 31 carbon atoms; below 5% of the hydrocarbons are branched medium chain length hydrocarbons having 32 to 39 carbon atoms; and 5 to 15% of the hydrocarbons are branched long chain length hydrocarbons having 40 to 61 carbon atoms; wherein the percentage in each case is relative to the total number of hydrocarbons having 15 to 110 carbon atoms; mixing the hydrocarbon wax composition with a rubber composition to produce a rubber product.

15. The method of claim 14 wherein the rubber product comprises 0.5 to 10 parts per hundred rubber of the hydrocarbon wax composition.

16. The method of claim 14 wherein the hydrocarbon wax composition has one or more of the following properties: reduces blooming of hydrocarbon wax molecules on the surface of the rubber product; protects the rubber product against ozone depletion; and/or protects the rubber product against ageing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a gas chromatogram showing the molecular distribution of carbon atoms per hydrocarbon molecule and the linear/branched ratio for Sasolwax Blend 7.

DETAILED DESCRIPTION OF THE INVENTION

(2) The hydrocarbon wax composition is according to preferred embodiments further defined independently from each otherin any combination with respect to the hydrocarbon molecules with 15 to 110 carbon atoms defined aboveas follows.

(3) Preferably 26 to 37% of the hydrocarbons of the hydrocarbon wax composition are linear short chain length hydrocarbons having 20 to 30 carbon atoms.

(4) Furthermore 26 to 37% of the hydrocarbons of the hydrocarbon wax composition preferably are linear long chain length hydrocarbons having 39 to 60 carbon atoms.

(5) 6 to 8% of the hydrocarbons of the hydrocarbon wax composition may preferably be branched short chain length hydrocarbons having 21 to 31 carbon atoms.

(6) 6 to 12% of the hydrocarbons of the hydrocarbon wax composition may preferably be branched long chain length hydrocarbons having 40 to 61 carbon atoms.

(7) 10 to 16% of the hydrocarbons of the hydrocarbon wax may preferably be linear medium chain length hydrocarbons having 31 to 38 carbon atoms.

(8) 0.1 to 3.0% of the hydrocarbons of the hydrocarbon wax may preferably be branched medium chain length hydrocarbons having 32 to 39 carbon atoms.

(9) The hydrocarbon wax composition according to the invention is preferably further characterised by one or more of the following definitions the number ratio of linear short chain length hydrocarbons to the linear long chained hydrocarbons is between 0.5 and 1.5, more preferably between 0.6 and 1.2; the number ratio of branched short chain length hydrocarbons to the branched long chain length hydrocarbons is between 0.5 and 1.5, more preferably between 0.6 and 1.2; the number ratio of linear short chain length hydrocarbons to linear medium chain length hydrocarbons is between 1.5 and 3.5, more preferably between 1.6 and 3.2; the number ratio of linear long chain length hydrocarbons to linear medium chain length hydrocarbons is between 2.0 and 4.0, more preferably between 2.2 and 3.2; the number ratio of branched short chain length hydrocarbons to branched medium chain length hydrocarbons is between 2.5 and 6.5, more preferably between 2.8 and 6.0; the number ratio of branched long chain length hydrocarbons to branched medium chain length hydrocarbons is between 4.0 and 7.0, more preferably between 4.5 and 6.5; the number ratio of linear short chain length hydrocarbons to branched short chain hydrocarbons is between 3.0 and 6.0, more preferably between 3.5 and 5.5; the number ratio of linear long chain length hydrocarbons to branched long chain length hydrocarbons is between 3.0 and 6.0, more preferably between 3.2 and 5.0; the number ratio of linear medium chain length hydrocarbons to branched medium chain length hydrocarbons is between 6.0 and 12.0, more preferably between 6.4 and 11.2.

(10) Furthermore 10 to 30%, preferably 15 to 25% of the hydrocarbons of the hydrocarbon wax composition are preferably branched hydrocarbons.

(11) A hydrocarbon wax composition as defined above and in the claims shows improved blooming properties (see examples). It is assumed that this is due to the specific distribution of hydrocarbon molecules by number of carbon atoms per hydrocarbon molecule and its migration and ozone protection properties while not wishing to be bound by a particular theory.

(12) The invention also includes a method for obtaining wax pastilles or a wax powder consisting of the hydrocarbon wax composition according to the invention by selectively blending and/or mixing different hydrocarbon wax components to obtain the desired properties.

(13) This method for obtaining wax pastilles or a wax powder comprises the following steps: Providing at least two hydrocarbon wax components, wherein a first hydrocarbon wax component comprises hydrocarbons with 15 to 110 carbon atoms, wherein above 60% of the hydrocarbons are linear short chain length hydrocarbons having 20 to 30 carbon atoms; and a second hydrocarbon wax component comprises hydrocarbons with 15 to 110 carbon atoms, wherein above 45% or according to a further embodiment above 60% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms; mixing the hydrocarbon wax components in a molten state with each other to obtain the hydrocarbon wax composition according to any of the preceding claims; and solidifying the hydrocarbon wax composition, preferably by spray cooling or pastillation or slabbing.

(14) Also claimed is the use of the hydrocarbon wax composition or the use of the wax pastilles or the wax powder as an additive in a rubber product. In a preferred use such additive reduces blooming of hydrocarbon wax molecules on the surface of the rubber product, protects the rubber product against ozone depletion and/or against ageing.

(15) The rubber product preferably comprises 0.5 to 10 phr, more preferably 1 to 5 phr, and most preferably 1 to 3 phr of the hydrocarbon wax composition. The unit (parts per hundred parts of rubber by weight) is a unit used in the rubber industry and provides a measure relative to 100 parts per weight of the total mass of rubber present.

(16) The invention may additionally or alternatively be described as follows:

(17) A hydrocarbon wax composition comprising linear and branched hydrocarbon molecules, having a distribution of hydrocarbon molecules by number of carbon atoms per hydrocarbon molecule and having at least two maxima between 15 to 110 carbon atoms per hydrocarbon molecule, wherein in each case the maximum is the highest number of hydrocarbon molecules within a range of +/ two carbon atom per hydrocarbon molecule, wherein at least one maximum of the linear hydrocarbon molecules is between 23 to 33 carbon atoms per hydrocarbon molecule and at least one maximum of the linear hydrocarbon molecules is between 37 to 48 carbon atoms per hydrocarbon molecule; at least one maximum of the branched hydrocarbon molecules is between 23 to 33 carbon atoms per hydrocarbon molecule and at least one maximum of the branched hydrocarbon molecules is between 37 to 48 carbon atoms per hydrocarbon molecule; the maximum with the highest number of carbon atoms per hydrocarbon molecule in the range between 23 to 33 carbon atoms per hydrocarbon molecule and the maximum with the lowest number of carbon atoms per hydrocarbon molecule in the range between 37 to 48 carbon atoms per hydrocarbon molecule of linear and branched hydrocarbon molecules differ from each other by at least by 12 carbon atoms per hydrocarbon molecule; the distribution has no maximum for both, the linear and the branched hydrocarbon molecules, in the above range of the at least 12 carbon atoms per hydrocarbon molecule; and the distribution has at least one minimum for both, the linear and the branched hydrocarbon molecules, each at 30 to 36 carbon atoms per hydrocarbon molecule, wherein in each case the minimum is the lowest number of hydrocarbon molecules within a range of +/ two carbon atom per hydrocarbon molecule.

(18) The hydrocarbon wax composition according to the additional or alternative definition preferably has at least one maximum of the distribution for the linear hydrocarbon molecules at 23 to 30 carbon atoms, more preferably at 24 to 29 carbon atoms per hydrocarbon molecule.

(19) The hydrocarbon wax composition according to the additional or alternative definition preferably further has at least one maximum of the distribution for the linear hydrocarbon molecules at 39 to 48 carbon atoms, more preferably at 40 to 43 carbon atoms per hydrocarbon molecule.

(20) Preferably the number of the branched hydrocarbons in the hydrocarbon wax composition according to the additional or alternative definition is between 10 and 30%, more preferably between 15 and 25% of the total number of hydrocarbon molecules.

EXAMPLES

(21) Three hydrocarbon wax compositions: Varazon 6500 (comparative example, from Sasol Wax GmbH, Hamburg, to obtain composition 1), Vararzon 6066 (comparative example, from Sasol Wax GmbH, Hamburg, to obtain composition 2) and Sasolwax Blend 7 (example according to the invention, from Sasol Wax GmbH, Hamburg, to obtain composition 3)
were incorporated into a standard tyre rubber composition according to table 1.

(22) TABLE-US-00001 TABLE 1 Composition Composition Composition Components Unit 1 2 3 Natural rubber TSR phr 40 40 40 Polyisoprene, synthetic phr 10 10 10 Butadiene rubber .sup.a) phr 20 20 20 SBR .sup.b) phr 30 30 30 Carbon black N339 phr 33 33 33 Antiageing agent phr 5 5 5 Further additives .sup.c) phr 14.5 14.5 14.5 Wax phr 2.3 1.5 2.3 Sulfur and sulfenamide phr 3.3 3.3 3.3 accelerator used rubber compositions .sup.a) Butadiene rubber, Nd-catalysed, high-cis BR .sup.b) Styrole-Butadiene-rubber, solvent-polymerised, SBR1500 .sup.c) i.a. zinc oxide, stearic acid, plasticizer

(23) The production of the rubber composition mixture was conducted in a tangential mixer under standard conditions and in two stages. Test blocks were produced by vulcanisation from all mixtures and the typical material properties used in the rubber industry were determined. The following test methods were used for that purpose: Shore-A-hardness (Unit Shore A, abbreviated ShA) at room temperature (RT) according to DIN 53 505 Rebound resilience (abbreviated rebound) at room temperature according to DIN 53 512 Tensile strength at room temperature according to DIN 53 504 Blooming behaviour: Vulcanisates have been stored for three months, protected from humidity and solar irradiation, and visually evaluated afterwards. Class 1: satisfying optical appearance, Class 2: sufficient optical appearance, Class 3: insufficient optical appearance Ozone resistance at room temperature according to conditions similar to DIN 53 509/DIN ISO 1431-1: Ozone concentration 200 pphm+/30 pphm, temperature 25 C.+/3 C., 60%+/5% air humidity and a static strain between 10 and 60%, whereas the evaluation is done according to DIN 53 509/DIN ISO 1431-1, Evaluation: positive (no cracks) or negative (cracks)

(24) The properties of the rubber compositions containing the waxes can be seen in table 2:

(25) TABLE-US-00002 TABLE 2 Properties of the rubber compositions Composi- Composi- tion 1 tion 2 Composi- (compara- (compara- tion 3 Properties Unit tive) tive) (inventive) Tensile strength MPa 13.1 13.1 12.6 at RT Rebound resilience % 49 49 49 at RT Shore Hardness Shore A 51 51 51 at RT Blooming Class 2 3 1 behaviour Ozone positive positive positive resistance

(26) The hydrocarbon wax composition of Sasolwax Blend 7 was measured by gas chromatography according to the Standard Test Method for Analysis of Hydrocarbon Waxes by Gas Chromatography (EWF Method 001/03) of the European Wax Federation (see table 3).

(27) TABLE-US-00003 TABLE 3 Conditions of GC-measurements according to EWF Method 001/03 Sample concentration 20 mg/20 ml solvent Carrier gas Hydrogen; 71 cm/sec Column temperature Start 75 C.; 25 C./min to 100 C.; 8 C./min to 325 C.; 325 C. for 15 min Column dimensions 25 m; 0.32 m i.d.; 0.12 m film thickness Injector type Cool on column Result report Area %

(28) The gas chromatogram is depicted in FIG. 1 and gives the molecular distribution of the number of carbon atoms per hydrocarbon molecule and the n/iso-ratio for Sasolwax Blend 7.

(29) The Sasolwax Blend 7 was obtained by mixing 45 wt.-% of a fully refined paraffin wax with a congealing point according to ASTM D 938 of 52 to 54 C. and 81.3% of linear short chain length hydrocarbons having 20 to 30 carbon atoms (Sasolwax 5203), 45 wt.-% of a Fischer-Tropsch derived paraffin wax with a congealing point of 83 C. and 48.5% of linear long chain length hydrocarbons having 39 to 60 carbon atoms (Sasolwax C80) and 10 wt.-% of a hydrotreated microcrystalline wax with a congealing point of 78 C. and 74.5% of branched hydrocarbons (Sasolwax 3279).

(30) In the hydrocarbon wax composition (Sasolwax Blend 7) according to the invention comprising hydrocarbons with 15 to 110 carbon atoms 26.4% of the hydrocarbons are linear short chain length hydrocarbons having 20 to 30 carbon atoms and 35.4% of the hydrocarbons are linear long chain length hydrocarbons having 39 to 60 carbon atoms.

(31) Furthermore 7.0% of the hydrocarbons of this hydrocarbon wax composition are branched short chain length hydrocarbons having 21 to 31 carbon atoms and and 10.8% of the hydrocarbons are branched long chain length hydrocarbons having 40 to 61 carbon atoms.

(32) 15.2% of the hydrocarbons of this hydrocarbon wax composition are linear medium chain length hydrocarbons having 31 to 38 carbon atoms and 2.3% of the hydrocarbons are branched medium chain length hydrocarbons having 32 to 39 carbon atoms.

(33) 21% of the hydrocarbons of this hydrocarbon wax composition are branched hydrocarbons.

(34) Table 4 shows the distribution of the different hydrocarbon wax compositions used in the experiments as defined in claim 1 also determined by the above GC-method.

(35) TABLE-US-00004 TABLE 4 Hydrocarbon distribution of the different hydrocarbon wax compositions Varazon Varazon % hydrocarbons 6500 6066 Sasolwax according to compara- compara- Blend 7 Feature Claim 1 tive tive inventive C.sub.20-30 (linear) 25 to 40% 29.0 41.4 26.4 C.sub.39-60 (linear) 25 to 40% 15.2 3.4 35.4 C.sub.21-31 (branched) 5 to 15% 2.2 8.7 7.0 C.sub.40-61 (branched) 5 to 15% 10.1 7.0 10.8 C.sub.31-38 (linear) 5 to 18% 35.4 22.2 15.2 C.sub.32-39 (branched) below 5% 7.3 17.3 2.3

(36) As it can be seen from the above results the hydrocarbon wax composition according to the invention shows reduced blooming in rubber compositions produced therewith whilst maintaining the other properties such as ozone resistance, tensile strength, hardness and rebound resilience.