Process for manufacturing of rubber process oils with extremely low carcinogenic polycyclic aromatics compounds

Abstract

The invention discloses a rubber process oil and a process for manufacturing rubber process oils which are non-carcinogenic in nature. The process comprises of selectively producing Hildebrand solubility components enriched vacuum residue by selective distillation of reduced crude oil (RCO) to obtain minimum of 10 vol % boiling components in the range 490 C. to 50 C., which leads to higher solubility of rubber process oil with an aniline point of less than 70 C. and with extremely low concentration of selective polycyclic aromatics which makes the 15 product non-carcinogenic. The process comprises of selectively enriching higher Hildebrand solubility components in vacuum residue by vacuum distillation of reduced crude oil (RCO), then subjecting the enriched vacuum residue to solvent deasphalting process and subjecting the deasphalted oil to aromatic extraction process and then blending the enriched aromatic extract with Heavy Alkyl 20 Benzene (HAB) or Solvent processed base oil or hydroprocessed base oil or mixture thereof. The rubber process oils manufactured by the invented process have a polycyclic aromatics (PCA) content of less than 10 ppm, specifically benzo(a)pyrene content of less than 1 ppm. They have aniline point less than 70 C. but have high kinematic viscosity of 25 to 75 cSt at 100 C., pour point of 27 C. or less and a flash point minimum of 250 C. or more.

Claims

1. A process for manufacturing of rubber process oils containing extremely low carcinogenic polycyclic aromatic components less than 10 ppm (mass) specifically benzo(a)pyrene content of less than 1 ppm, and aniline point less than 70 C., comprising: a) selectively enriching higher Hildebrand solubility components in vacuum residue produced with a minimum 10% volume recovery in the boiling range of 490 C. to 550 C. from reduced crude oil (RCO) b) subjecting the enriched vacuum residue to solvent deasphalting process to produce the deasphalted oil; c) subjecting the deasphalted oil to aromatic extraction process with N-methyl pyrolidone (NMP) as solvent in counter current extractor with top and bottom temperature of 90 C. and 80 C. and solvent to oil ratio (volume/volume) being maintained at 2.25 to produce Bright Neutral (BN) extract with higher solubility; and d) blending the Bright Neutral (BN) extract with heavy alkyl benzene (HAB) or hydro processed base oil or solvent processed base oil or a mixture thereof to produce the rubber process oils.

2. The process for manufacturing of rubber process oil as claimed in claim 1, wherein vacuum residue is produced with a minimum 10% volume recovery in the boiling range of 490 C. to 550 C.

3. The process for manufacturing of rubber process oils as claimed in claim 1, wherein the deasphalting process has propane as a solvent with operating temperature range lying between 55 C. to 90 C. and propane to feed volume ratio is 4 to 14.

4. The process for manufacturing of rubber process oils as claimed in claim 1, wherein the aromatic extraction has N-Methyl pyrrolidone as a solvent, with water as antisolvent or alternatively alongwith a cosolvent, the cosolvent being selected from formamide, n-methyl formamide and n,n-dimethyl formamide in which the cosolvent content is less than 30 wt %.

5. The process for manufacturing of rubber process oils as claimed in claim 1, wherein the Bright Neutral (BN) extract content of the process oil is in the range of 70 wt % to 99 wt %, the heavy alkyl benzene (HAB) content is in the range of 1 to 10 wt %, and the selective polycyclic aromatics as determined by high pressure liquid chromatography is less than 10 ppm (mass).

6. The process for manufacturing of rubber process oils as claimed in claim 1, wherein the polycyclic aromatics content of the process oil is less than 10 ppm of Benzo(a)anthracene, chrysene, Benzo(j)floranthene, Benzo(e)pyrene, Benzo(b)floranthene, Benzo(K)floranthene, Benzo(a)pyrene, Dibenzo(a,h)anthracene and Benzo(a)pyrene, wherein the Benzo(a)pyrene content is less than 1 ppm.

7. The process for manufacturing of rubber process oils as claimed in claim 1, wherein the solvent processed base oil is blended with Bright Neutral (BN) extract in the range of 1 to 30 wt %, the solvent processed base oil boiling point being in the range of 300 C.-550 C.

8. The process for manufacturing of rubber process oils as claimed in claim 1, wherein hydro processed base oil is blended with Bright Neutral (BN) extract in the range of 1 to 30 wt %, and the hydro processed base oil boiling point being in the range of 300 C.-500 C.

9. The process for manufacturing of rubber process oils as claimed in claim 1, wherein heavy alkyl benzene (HAB) is blended with Bright Neutral (BN) extract in the range of 1 to 30 wt %.

10. The process for manufacturing of rubber process oils as claimed in claim 1, wherein the process oils so produced have an aniline point less than 70 C.

Description

DESCRIPTION OF THE INVENTION

(1) Process oils are the hydrocarbon mixture that boils in the same temperature range as lubricant base oils and are derived from petroleum distillates by solvent extraction. However, unlike lubricant base oils which are rarely employed outside the lubricant field, process oils have a wide range of industrial applications which include using it as rubber process oil (RPO), ink process oil etc. To make it suitable for these applications, the compositions of process oils have to be carefully controlled during refining.

(2) Rubber process oil is employed during rubber processing for reducing the mixing temperature, prevent scorching and to decrease the viscosity of the rubber, thereby facilitating the milling operations and general workability of the rubber compound and to aid the dispersion of fillers and modify the physical properties of rubber compounds.

(3) The rubber process oil should have higher degree of miscibility or solubility with rubber to act as good process oil. Hildebrand solubility parameter of the hydrocarbon oil is employed in the present invention to measure solubility of oil, which is further experimentally measured by aniline point. Lower the aniline point better is the solubility of the hydrocarbon oil.

(4) The Hildebrand solubility parameter can be derived from the heat of vaporization of the component. Further it describes the total cohesive energy density of component.
Solubility parameter ()=(.box-tangle-solidup.HRT)/V.sub.m).sup.0.5
where .box-tangle-solidup.HHeat of vaporization, RGas Constant, TAbsolute temperature in Kelvin and V.sub.mMolar volume.

(5) A component with a higher Hildebrand value will have higher solubility and more particularly in the present invention, higher Hildebrand oil dissolves rubber better. Hereinafter, higher Hildebrand parameter enriched Bright Neutral (BN) extract is called as enriched BN extract

(6) The aniline point is defined as the minimum temperature at which 50:50 (v/v) mixture of oil and aniline forms a homogenous phase. Below that temperature, the aniline/oil phase separation occurs. The aniline point decreases with an increasing Hildebrand value of the component. The rubber process oil should have strong molecular cohesion between oil and rubber component and therefore requires relatively higher Hildebrand value or lesser aniline point.

(7) Typically, rubber process oil is used for processing of natural rubber, butadiene styrene rubber, butadiene nitrile rubber (SCN 18, SCN 26, SCN 40), butyl rubber, neoprene rubber, poly isoprene rubber, epoxy diane resin etc. The typical Hildebrand solubility parameter values of some of the rubber are shown below:

(8) TABLE-US-00001 Hildebrand Solubility Type of rubber Parameter (MPa).sup.0.5 Natural rubber 18.1 Butadiene nitrile rubber a) SCN 18 19.2 b) SCN 26 19.6 c) SCN40 20.2 Butadiene styrene rubber 19.3 Butyl rubber 17.9 Neoprene 19.6 Poly isoprene 18 Epoxy diane resin 21.5

(9) Typically, rubber components have a solubility parameter in the range of 18 to 24 (MPa).sup.0.5. Consequently, a substance with a matching solubility parameter should have better miscibility with the rubber.

(10) The present invention provides a process for manufacture of a process oil, which has relatively higher Hildebrand solubility components to obtain higher solubility with rubber components having their aniline point less than 70 C. and which have extremely low content of harmful carcinogenic compounds without compromising the physical properties of the oil.

(11) In one embodiment of the present invention, the higher Hildebrand value enriched vacuum residue is produced with a minimum 10% volume recovery of the boiling components being in the range between 490 C. to 550 C. to obtain higher solubility of rubber process oil with an aniline point of less than 70 C.

(12) In another embodiment, the invention provides a process for manufacturing a process oil, the process comprises selectively producing enriched hildebrand solubility components in vacuum residue by selective distillation of reduced crude oil (RCO) to obtain higher solubility of rubber process oil with the aniline point less than 70 C. and the enriched vacuum residue containing extremely low carcinogenic polycyclic aromatics. The enriched vacuum residue with low level of selective PCA content is further subjected to propane deasphalting process. The volume ratio of propane solvent to vacuum residue is kept in the range of 6-8 and the operating temperature between 55-65 C.

(13) Further, the above said Hildebrand solubility components enriched deasphalted oil or bright neutral (BN) feedstock is subjected to extraction with a solvent having selective affinity for aromatic hydrocarbon, which can be Furfural or N-Methyl Pyrrolidone (NMP) alongwith a cosolvent and the cosolvent is preferably selected from formamide, n-methyl formamide or n,n-dimethyl formamide in which the cosolvent content is preferably less than 30 wt %.

(14) The solvent to DAO ratio was kept at 1.5-2.5 wt %, preferably at 2.25 wt % and the operating temperature was is in the range of 80-90 C. The said enriched BN extract obtained from the extraction process has a selective polycyclic aromatic content [Benz(a)anthracene+chrysene, Benz(j)floranthene, Benz(e)pyrene, Benz(b)floranthene, Benz(K)floranthene, Benz(a)pyrene) and Dibenz(a,h)anthracene] of less than 10 ppm and specifically, Benz(a)pyrene content less than 1 ppm as measured by high pressure liquid chromatography (HPLC) technique and aniline point 70 C. or less, but the process oil has a high kinematic viscosity and pour point. For reducing the kinematic viscosity and pour point the higher Hildebrand solubility components enriched BN extract is blended with heavy alkyl benzene (HAB) or HAB with solvent processed base oil or HAB with hydro processed base oil or mixture thereof.

(15) According to the present invention, the sum total of the selective polycyclic aromatic content [Benzo(a) anthracene+chrysene, Benzo(j)floranthene, Benzo(e)pyrene, Benzo(b)floranthene, Benzo(K)floranthene, Benzo(a)pyrene) and Dibenzo(a,h)anthracene] of rubber process oil measured by high pressure liquid chromatography (HPLC) technique is less than 10 ppm mass and benz (a) pyrene content less than 1 ppm mass, the aniline point is 70 C. or less and the % C.sub.a value as determined by ring analysis is minimum 25%.

(16) In the present invention, a process for manufacturing the process oil is disclosed, which comprises of: a) selectively enriching higher hildebrand solubility components in vacuum residue by vacuum distillation of reduced crude oil (RCO) to obtain process oil having higher solubility with an aniline point less than 70 C. The vacuum residue is produced with a minimum 10% volume recovery of the boiling components being in the range between 490 C. to 550 C. preferably in the range between 500 C. to 550 C. b) subjecting the enriched vacuum residue to solvent deasphalting process to produce deasphalted oil; In the deasphalting process, propane is a solvent, in which operating temperature range is between 55 C. to 90 C. and propane to feed volume ratio is 4 to 14. c) further subjecting the deasphalted oil produced to aromatic extraction process to produce enriched aromatic extract with higher solubility; d) finally blending the enriched aromatic extract with heavy alkyl benzene (HAB) or hydro processed base oil or solvent processed base oil or mixture thereof to produce the rubber process oils.

(17) The rubber process oils so produced have a polycyclic aromatics (PCA) content of less than 10 ppm, specifically benzo(a)pyrene content of less than 1 ppm. and aniline point less than 70 C. but have a high kinematic viscosity of 25 to 75 cSt at 100 C., pour point of 27 C. or less and has a flash point minimum of 250 C. or more.

(18) According to the present invention, the deasphalted oil is subjected to aromatic extraction, in which N-Methyl pyrrolidone is a solvent, with water as antisolvent or alternatively alongwith a cosolvent and the cosolvent is preferably selected from formamide, n-methyl formamide, n,n-dimethyl formamide in which the cosolvent content is preferably less than 30 wt %.

(19) In this process the aromatic extract content of the process oil is in the range of 70 wt % to 99 wt % and the heavy alkyl benzene (HAB) content is in the range of 1 to 10 wt %. The selective polycyclic aromatics as determined by high pressure liquid chromatography is preferably less than 10 ppm (mass).

(20) The total polycyclic aromatics content of the process oil comprising of Benzo(a)anthracene, chrysene, Benzo(j)floranthene, Benzo(e)pyrene, Benzo(b)floranthene, Benzo(K)floranthene, Benzo(a)pyrene, Dibenzo(a,h)anthracene and Benzo(a)pyrene is less than 10 ppm. The Benzo(a)pyrene content is less than 1 ppm.

(21) The present invention directed to a process for manufacturing a process oil which has low levels of selective polycyclic aromatic content. In one of its embodiments, the present invention provides the process for producing a process oil having low level of selective PCA content from hydrocarbon oil and more particularly selectively producing vacuum residue with negligible amount of PCA compounds by vacuum distillation of reduced crude oil (RCO), the above said vacuum residue is further subjected to propane deasphalting process. The volume ratio of propane solvent to vacuum residue is kept in the range of 6-8 and the operating temperature between 55-65 C.

(22) Further, the above said deasphalted oil (BN) is subjected to extraction with a solvent having selective affinity for aromatic hydrocarbon like Furfural or N-Methyl Pyrrolidone (NMP) alongwith a cosolvent and the cosolvent is preferably selected from formamide, n-methyl formamide, n,n-dimethyl formamide in which the cosolvent content is preferably less than 30 wt %.

(23) The solvent to DAO (BN) ratio was kept at 1.5-2.5 wt % preferably at 2.25 wt % and the operating temperature was is in the range of 80-90 C. The above BN extract obtained from the extraction process has a selective polycyclic aromatic content [Benz(a)anthracene+chrysene, Benz(j)floranthene, Benz(e)pyrene, Benz(b)floranthene, Benz(K)floranthene, Benz(a)pyrene) and Dibenz(a,h)anthracene] of less than 10 ppm and specifically, Benz(a)pyrene content less than 1 ppm as measured by high pressure liquid chromatography (HPLC) technique and aniline point 70 C. or less but the process oil having the high kinematic viscosity and pour point. For reducing the kinematic viscosity and pour point the BN extract is blended with solvent processed base oil or hydro processed base oil or heavy alkyl benzene (HAB) or mixture thereof.

(24) In a preferred embodiment of the present invention, the solvent processed base oil is blended with BN extract. The ratio of solvent processed base oil blended with above said BN extract is in the range of 1 to 30 wt % preferably 1 to 10 wt %. The selected base oil boiling point is in the range of 300-550 C.

(25) In another embodiment of the present invention, hydro processed base oil is blended with BN extract in the range of 1 to 30 wt %, preferably 1 to 10 wt %. The selected hydro processed base oil boiling point is in the range of 300-500 C.

(26) In one more embodiment of the present invention, heavy alkyl benzene (HAB) is blended with BN extract in the range of 1 to 30 wt %, preferably 1 to 10 wt %.

(27) In yet another embodiment of the present invention, the process oil has a selective polycyclic aromatic content [Benzo(a) anthracene+chrysene, Benzo(j)floranthene, Benzo(e)pyrene, Benzob)floranthene, Benzo(K)floranthene, Benzo(a)pyrene) and Dibenzo(a,h)anthracene] of less than 10 ppm mass and Benzo(a)pyrene content less than 1 ppm mass as measured by high pressure liquid chromatography (HPLC) technique. It has the following properties: (a) Aniline point is 70 C. or less (b) The pour point of 30 C. or less (c) C.sub.a content is more than 25 wt % (d) The kinematic viscosity within the range of 25 cSt to 75 cSt (e) The flash point is 250 C. or more

EXAMPLE 1

(28) Vacuum residue is selectively produced with negligible amount of PCA compounds by distilling of reduced crude oil (RCO) under reduced pressure. The vacuum residue is produced with a minimum 10% volume recovery of the boiling components being in the range between 490 C. to 550 C. The vacuum residue is further subjected to propane deasphalting process with eight parts by volume of propane added to one part by volume of vacuum residue with column top and bottom temperatures of 65 C. and 55 C. The deasphalted oil from above process is further subjected to aromatic extraction with NMP solvent in counter current extractor with top and bottom temperature of 90 C. and 80 C. and keeping solvent to oil ratio (volume/volume) at 2.25. The BN extract so produced is of higher pour point and kinematic viscosity. To reduce the kinematic viscosity and pour point, the heavy alkyl benzene (HAB) is blended with BN extract. The BN extract blend has a selective polycyclic aromatic content of less than 10 ppm and is used as rubber process oil 2. The other properties of process oil-A are shown in Table 1.

(29) TABLE-US-00002 TABLE 1 Properties of process oil-C (RPO-3) derived from blending of BN extract with heavy alkyl benzene (HAB). S. No. Property Process Oil A 1 Appearance @ 40 C. Dark liquid 2 Density @15 C. (g/cc) 0.986 3 Kinematic Viscosity@100 C. (cSt) 76.9 4 Refractive Index@20 C. 1.55567 5 Viscosity Gravimetric Constant 0.8947 6 Aniline Point( C.) 65.5 7 Flash Point ( C.) 307 8 Pour Point ( C.) 27 9 Sulphur, wt % 3.4 10 Hydrocarbon Composition, % wt Ca 28.5 Cp 57.9 Cn 13.6 11 Polycyclic aromatic content (ppm) 7.22 Benzo(a)pyrene (ppm) 0.18 12 Distillation data, ASTM D1160 (Vol %) Temperature, C. IBP , C. 359 5% vol recovery 444 10% vol recovery 503 30% vol recovery 555 50% vol recovery 580 70% vol recovery 605 90% vol recovery FBP, C.

EXAMPLE 2

(30) Vacuum residue is selectively produced with negligible amount of PCA compounds by distillation of reduced crude oil (RCO) under reduced pressure. The vacuum residue is produced with a minimum 10% volume recovery of the boiling components being in the range between 490 C. to 550 C. The vacuum residue is further subjected to propane deasphalting process with eight parts by volume of propane added to one part by volume of vacuum residue with column top and bottom temperatures of 65 C. and 55 C. The deasphalted oil from above process is further subjected to aromatic extraction with NMP solvent in counter current extractor with top and bottom temperature of 90 C. and 80 C. and solvent to oil ratio (volume/volume) being kept at 2.25. The BN extract so produced is of higher pour point and kinematic viscosity. The solvent processed base oil is then blended with solvent processed base oil to reduce kinematic viscosity and pour point. The selected solvent processed base oil has the boiling range which lies between 300 C.-550 C. The BN extract blend has a selective polycyclic aromatic content less than 10 ppm mass and is used as rubber process oil-B. The other properties of Process oil-B are shown in Table 2.

(31) TABLE-US-00003 TABLE 2 Properties of process oil-A (RPO-1) derived from blending of BN extract with solvent processed base oil. S. No. Property Process Oil B 1 Appearance @ 40 C. Dark liquid 2 Density @15 C. (g/cc) 0.9785 3 Kinematic Viscosity@100 C. (cSt) 74.6 4 Refractive Index@20 C. 1.55013 5 VGC 0.8849 6 Aniline Point( C.) 69.9 7 Flash Point ( C.) 305 8 Pour Point ( C.) (+)27 9 Sulfur Content (% wt) 3.7 10 Hydrocarbon Composition, % wt Ca 27.41 Cp 60.67 Cn 11.91 11 Polycyclic aromatic content (ppm) 4.79 Benzo(a)pyrene (ppm) 0.4 12 Distillation data, ASTM D1160 (Vol %) IBP 386 5 465 10 528 30 559 50 589 60 610 70 612 90 FBP

EXAMPLE 3

(32) Vacuum residue is selectively produced with negligible amount of PCA compounds by distilling reduced crude oil (RCO) under reduced pressure. The vacuum residue is produced with a minimum 10% volume recovery of the boiling components being in the range between 490 C. to 550 C. The vacuum residue is further subjected to propane deasphalting process with eight parts by volume of propane being added to one part by volume of vacuum residue and with column top and bottom temperatures of 65 C. and 55 C. The deasphalted oil from above process is further subjected to aromatic extraction with NMP solvent in counter current extractor with top and bottom temperature of 90 C. and 80 C. and solvent to oil ratio (volume/volume) being kept at 2.25. The BN extract so produced is of higher pour point and kinematic viscosity. Hydro processed base oil is blended with this BN extract to reduce kinematic viscosity and pour point. The selected hydro processed base oil has a boiling point range lying between 300 C.-500 C. The BN extract blend has a selective polycyclic aromatic content of less than 10 ppm and is used as Process oil-C. The other properties of process oil-C are shown in Table 3.

(33) TABLE-US-00004 TABLE 3 Properties of process oil-B (RPO-2) derived from blending of BN extract with hydro processed base oil. S. No. Property Process Oil C 1 Appearance @ 40 C. Dark liquid 2 Density @15 C. (g/cc) 0.9742 3 Kinematic Viscosity@100 C. (cSt) 67.8 4 Refractive Index@20 C. 1.55356 5 VGC 0.8812 6 Aniline Point( C.) 69.8 7 Flash Point ( C.) 275 8 Pour Point ( C.) (+)27 9 Sulfur Content (% wt) 3.7 10 Hydrocarbon composition, % wt Ca 26.68 Cp 60.1 Cn 13.62 11 Polycyclic aromatic content (ppm) 4.73 Benzo(a)pyrene (ppm) 0.76 12 Distillation data, ASTM D1160 (Vol %) IBP 350 5 430 10 543 30 570 50 593 60 614 70 90 FBP

(34) The invention has been explained in some of its exemplary embodiments. However, there can be other embodiments of the same invention, all of which are deemed covered by this description and the appended claims.