Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Process of making a soap containing composition by...
Reexamination Certificate
2002-02-04
2004-08-24
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Process of making a soap containing composition by...
C510S459000, C530S208000, C252S367100
Reexamination Certificate
active
06780831
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an improved process for the separation of unsaponifiable substances from crude sulphate soap, crude tall oil or tall oil pitch. Crude sulphate soap (CSS or BLSS) is a by-product of wood pulping and comprises sodium salts of fatty and rosin acids and an unsaponifiable neutral fraction which contains sterols and other neutral components, hereinafter called “valuable substances” or “neutral substances.” Crude tall oil (CTO) is made from this soap by acidulation, and tall oil pitch is the distillation residue of CTO.
The invention especially relates to the separation of the neutral substances by means of high vacuum distillation/evaporation, but it is also directed towards the production of fatty acids and other organic acids from the residues obtained from the high vacuum distillation/evaporation process.
Most processes used today to separate and concentrate neutral substances from either CSS, saponified CTO or saponified pitch use solvents, and these processes take advantage of the solubility differences between the unsaponifiable substances and the soap matrix. At present, when using one solvent alone, it is not possible to obtain a reasonable separation of the unsaponifiables from the fatty acid and rosin acid soaps etc. unless extreme process conditions, such as high temperatures and pressures, are used. Because of this, most processes often find it necessary to use more than one solvent, which complicates any recovery and reuse of the solvents, as well as tremendously increasing the costs of the processes.
Some processes for separating unsaponifiable neutral substances from CSS, saponified CTO, or saponified pitch use a high vacuum distillation/evaporation process. These processes take advantage of the volatility differences of volatile unsaponifiables, fatty acid, rosin acid, and almost any other non-volatile organic acid soap. In the case of separation by distillation, the difference between the boiling points of volatile products, such as unsaponifiable components, and the boiling point of different organic acid soaps is so remarkable that separation is possible at a high level of efficiency. However, a problem connected with this separation technique is the very high melting point required. This temperature is close to the decomposition temperature of sodium or potassium soaps (i.e. the sodium or potassium salts of fatty acids and rosin acids). It should be noted that even when melted, these soaps form extremely viscous liquids, which makes industrial handling difficult. While the soaps have to be kept at a high temperature (about 250° C.) in order to maintain their flowability, they are irreversibly decomposed at this temperature, which compromises the separation output and the quality of the final product.
U.S. Pat. No. 3,887,537 discloses a process for recovering fatty acids and rosin acids from tall oil pitch by saponifying the tall oil pitch with an alkali metal hydroxide (sodium hydroxide) in the presence of an alkyl alcohol (such as butanol) to form soaps and unsaponifiables. This mixture is then fed into a thin film evaporator to evaporate and remove the low-boiling matter, including the light unsaponifiables, water and alcohol. Subsequently, the bottom fraction is fed into a second thin film evaporator for the purpose of removing unsaponified heavy material, including sterols. Finally, the bottom soap fraction obtained from the second evaporator is acidulated with a mineral acid to obtain the final product of fatty acids and rosin acids. It should be noted that one of the difficulties with this process is that the soaps are very viscous, thereby making the handling of the soaps troublesome.
WO 99/16785 discloses a method for separating unsaponifiable material from tall oil pitch by saponifying the pitch with a mixture of sodium hydroxide and potassium hydroxide to form sodium and potassium salts of fatty acids and rosin acids. The method then involves the evaporation of the unsaponifiable material which contains sterols using a thin film evaporator. The remaining unevaporated portion of the pitch which comprises sodium and potassium salts of the saponifiable material is then acidulated to create the rosin and fatty acids. Additionally, it is noted that this method also suffers from the previously discussed problem resulting from the difficulty in handling the sodium and/or potassium soaps.
WO 99/42471 discloses a method of separating sterols from tall oil pitch by saponifying the tall oil pitch with an alkali metal base comprising sodium hydroxide, potassium hydroxide or a mixture thereof, followed by neutralizing the saponified pitch with an acid and heating the neutralized pitch to remove water. The resulting pitch, which contains free sterols, is then evaporated to remove light ends. The remaining bottom fraction is then evaporated using a wiped evaporator to produce a light phase distillate containing free sterols. Subsequently, the light phase distillate is dissolved in a solvent comprising an alcohol, and the free sterols are crystallized from the solution by cooling. A disadvantage of this method is that the yield of the sterols is rather low.
U.S. Pat. No. 4,151,160 discloses a process for the separation of fatty acids from the unsaponfiable constituents contained in a head fraction of tall oil by converting the fatty acids into their zinc or lead soaps, and then removing the unsaponifiable constituents by vacuum distillation. Subsequently, the (remaining) non-volatile metal soaps are acidulated to produce the desired fatty acids. Typical components of the light boiling unsaponifiables are long chain alcohols and rosin degradation products, which have minor commercial value. It should be noted that the content of sterols in the tall oil heads is very low, considerably below 1% by weight, which shows that the tall oil head fraction is not a suitable source from which to produce sterols.
U.S. Pat. No. 4,483,791 discloses a process for the recovery of fatty acids from tall oil heads by converting the fatty acids contained in the tall oil heads into a mixture of magnesium soap and sodium soap, and then vacuum stripping the reaction product. Finally, the soaps are then acidulated to produce the desired fatty acids.
EP 0 952 208 A2 discloses a process for the separation of unsaponifiables from BLSS or CTO by dehydrating the raw material and melting and distilling the dehydrated material in a short path evaporation column. This publication also suggests adding unsaponifiables to the soap or neutralized crude tall oil before the drying step in order to reduce the necessary temperature required to maintain the mixture at a state of adequate fluidity during the drying process. The added unsaponifiables comprise recirculated unsaponifiables from the process and they are low boiling substances. The recirculated unsaponifiables have a favourable effect on the drying step but they are believed to have a disadvantageous effect on the subsequent distillation step as the low boiling unsaponifiables are evaporated with the sterol fraction, resulting in a dilution of the sterol fraction. Because they do not remain in the residue fraction, they cannot facilitate the handling of the residue with a viscosity reducing effect as would be the case if they were present in the residue.
SUMMARY OF THE INVENTION
The new process of the present invention has solved the problems associated with the already known evaporation processes for separating sterols and other valuable substances from crude sulphate soap, crude tall oil or tall oil pitch by incorporating a softener material into the saponified feed either prior to, after, or during the drying step, but prior to the evaporation step.
Thus, the present invention provides a process for separating unsaponifiable neutral substances from crude sulphate soap, crude tall oil or tall oil pitch, comprising the steps of:
(a) providing a feed of at least one of crude sulphate soap, saponified crude tall oil or saponified tall oil pitch,
(b) providing a softener and incorporating said soft
Ogden Necholus
Raisio Benecol Ltd.
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