Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
2000-09-29
2003-03-11
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
Reexamination Certificate
active
06531571
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for the removal of excess amounts of water-soluble amines from Mannich condensation products thereby improving the formulation properties of the Mannich product. More particularly, the present invention relates to removing excess amounts of water-soluble amines from Mannich condensation products to levels below about 0.05×10
−3
equivalents of amine per gram of Mannich product (0.05 mEq/g) by filtering the Mannich condensation product with a solid filtering agent having an active surface.
2. Description of the Related Art
Mannich condensation products as fuel and lubricating oil additives are well known in the art and have been widely documented in the patent literature; e.g., U.S. Pat. Nos. 3,368,972; 3,798,247; 4,231,759; 5,399,178; 5,413,614; 5,482,522; and 5,483,523. As fuel additives, Mannich condensation products are particularly effective for the prevention and control of engine deposits, particularly engine intake system deposits, such as intake valve deposits. These additives are based upon the condensation products of a hydroxyaromatic compound, an amine, and an aldehyde.
For example, U.S. Pat. No. 4,231,759 to Udelhofen and Watson discloses reaction products obtained by the Mannich condensation of a high molecular weight alkyl-substituted hydroxyaromatic compound, an amine containing an amino group having at least one active hydrogen atom, and an aldehyde, such as formaldehyde. This patent further teaches that such Mannich condensation products are useful detergent additives in fuels for the control of deposits on carburetor surfaces and intake valves.
The foregoing Mannich condensation products are commonly prepared by the conventional technique of adding the aliphatic aldehyde to a heated mixture of the hydroxyaromatic compound and amine reagents, and then heating the resultant mixture to a temperature between 35° to 180° C. until dehydration is complete. The reaction may be done in the presence or absence of a solvent. Typical solvents include benzene, toluene, xylene, methanol, and other commercially available aromatic or aliphatic solvents. Light mineral oils and base oils such as those used in blending stocks to prepare lubricating oil formulations in which the product is formed as an oil concentrate are also used. The water byproduct is removed by heating the reaction mixture to a temperature sufficiently high, at least during the last part of the process, to drive off the water. The water may come off alone, or as an azeotrope mixture with the solvent, usually with the aid of vacuum or an inert stripping gas like nitrogen.
U.S. Pat. No. 3,798,247 to Piasek and Karll teaches that the reaction under Mannich condensation conditions, like other chemical reactions, does not go to theoretical completion and some portion of the reactants, generally the amine, remains unreacted or only partially reacted as a coproduct. Unpurified products of Mannich processes also commonly contain small amounts of insoluble particle byproducts of the Mannich condensation reaction that appear to be the high molecular weight condensation product of formaldehyde and polyamines. The amine and amine byproducts lead to haze formation during storage and, in diesel lubricating oil formulations, to rapid buildup of diesel engine piston ring groove carbonaceous deposits and skirt varnish. The insoluble or borderline soluble byproducts are substantially incapable of removal by filtration and severely restrict product filtration rate. These drawbacks were overcome by adding long-chain carboxylic acids to reduce the amount of solids formation from the Mannich reaction by rendering the particulate polyamine-formaldehyde condensation product soluble through formation of amide-type links. In particular, oleic acid worked well at 0.1 to 0.3 mole/mole of alkylphenol. The quantity of unconsumed or partially reacted amine was not mentioned in the patent.
U.S. Pat. No. 4,334,085 to Basalay and Udelhofen discloses that Mannich condensation products can undergo transamination, and this is seen as a solution to the problem of byproduct amine-formaldehyde resin formation encountered by Piasek and Karll in U.S. Pat. No. 3,798,247, above, eliminating the need for using a fatty acid. Basalay and Udelhofen defined transamination as the reaction of a Mannich adduct based on a single-nitrogen amine with a polyamine to exchange the polyamine for the single-nitrogen amine. The examples in this patent suggest that the unconsumed amine and partially reacted amine discussed in U.S. Pat. No. 3,798,247 are not merely unconsumed, but must be in chemical equilibrium with the product of the Mannich condensation reaction. In Example 1 of U.S. Pat. No. 4,334,085, a Mannich condensation product is made from 0.5 moles of polyisobutylphenol, 1.0 mole of diethylamine and 1.1 moles of formaldehyde. To 0.05 moles of this product was added 0.05 moles of tetraethylenepentamine (TEPA) and then the mixture was heated to 155° C. while blowing with nitrogen. The TEPA replaced 80 to 95% of the diethylamine in the Mannich product as the nitrogen stripped off the small amount of diethylamine made available by the equilibrium with the Mannich product.
In fuel additive applications, the presence of small amounts of low molecular weight amine in dispersant components such as the Mannich condensation product can lead to formulation incompatibilities (for example, with certain corrosion inhibitors or demulsifiers) and air sensitivity (for example, reaction with carbon dioxide in the air). For example, corrosion inhibitors are typically organic acids. These can react with excess amounts of low molecular weight amines in the Mannich component at room temperature to form insoluble salts and at higher temperatures to form insoluble amides. Incompatibility or air sensitivity is manifested by formation of haze, floc, solids, and or gel in the formulation over time. The incompatibility may occur in the absence of air. Consequently, the manufacturing process for amine dispersant-type fuel additives must include a step to remove low molecular weight amines to low levels. However, in view of the unique chemistry of Mannich condensation products, an effective purification step may not be readily accomplished. In particular, the chemical equilibrium can generate additional low molecular weight amines if the product is heated too much during the purification step. Therefore, there is a need for an economical process to reduce the unconsumed amine and the amine-formaldehyde intermediate to a low level after the Mannich reaction.
There are a number of methods that may be used for removing excess amine after a Mannich condensation reaction. Some possible approaches include washing with water, distillation, and absorption/filtration. However, these techniques must be applied with great care because the chemical equilibrium of the Mannich condensation product has the potential to release more amine during the purification process.
In the area of fuel additives, a typical way of determining the efficiency of the purification step is to measure the low molecular weight amine content of the Mannich product before and after the purification step. The Mannich sample is diluted with solvent and then extracted with water. Analysis of the water extract by gas chromatography or titration yields the amount of water-soluble amine either in weight percent by gas chromatography or milliequivalents of base per gram of Mannich product by titration (mEq/g).
Water washing and simple vacuum distillation are well known techniques for removing water-soluble amines in fuel additive manufacturing processes. Water washing is very complex and relatively costly to implement on a commercial scale. This approach requires multiple washes, and there are recycle streams needed for the solvents that promote phase separation. Fuel additives are good dispersants by nature, and so contacting with water and phase separation become major technical problems.
Simple vacuum distillation is pra
Boykin Terressa M.
Chevron Oronite Company LLC
Lee S. G. K.
LandOfFree
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