Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D13/00—Making of soap or soap solutions in general; Apparatus therefor
  • C11D13/02—Boiling soap; Refining
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D13/00—Making of soap or soap solutions in general; Apparatus therefor
  • C11D13/02—Boiling soap; Refining
  • C11D13/06—Bleaching of soap or soap solutions

Definitions

• This invention relates to a process for the production of a soap of improved colour and odour which includes the step of treating a soap containing system at any stage during the production of the soap with an alkali metal borohydride at a pH of at least 9.5.
• the soap containing system is preferably treated With anaqueous alakli solution containing 0.01-0.30% sodium borohydide by weight of the fat charge immediately after it leaves the washing unit.
• This invention relates to a process for the preparation of a soap and, in particular, it relates to a process for the preparation of a soap of improved colour and odour.
• Certain reducing agents such as the alkali metal borohydrides, are known to decompose at elevated temperatures in aqueous solution, the rate of decomposition increasing with increasing temperature and decreasing with increasing alkalinity of the solution.
• alkali metal borohydride can rapidly reduce the colour and odour of a viscous medium like molten soap.
• this invention provides a process for the preparation of a soap which includes the step of treating a soap containing system at any stage during the manufacture of the soap with an alkali metal borohydride, at a pH of at least 9.5.
• the colour of the soap obtained from this process is conveniently measured on a 5.84% w./v. aqueous solution of the soap (dry basis) with the aid of a Lovibond Tintometer using a Lovibond 13.3 cms. cell.
• the acceptable standard of colour depends on the purpose to which the soap produced is to be applied.
• the colour is determinable in terms of Lovibond red and yellow unitsthese units being combined to form one value (referred to in this specification as the soap colour) by use of the formula:
• soap colour (yellow reading) +30 X (red reading) ice
• soap charge refers to the material obtained by saponification of a suitable charge of fat and alkali.
• fat may refer to an animal tallow, a vegetable oil such as palm oil, palm kernel oil or coconut oil, a fish oil or to the fatty acids obtained from such materials by a conventional splitting technique. Mixtures of these fats may be used in the process of this invention-a convenient mixture, for example, being based on tallow and up to 20% W./w. of an oil such as coconut oil. These fats are henceforth referred to in the specification as the fat charge.
• the fat charge is of a low grade
• the colour of a bleached low grade tallow may vary from 40 yellow, 0.8 red to 15.0 yellow, 2.5 red (when measured in a 0.635 cm. cell of a Lovibond Tintometer).
• Synthetic fatty acids such as those obtained by the oxidation of paraflinic hydrocarbons, may also be used in the process of this invention alone or in admixture with a fat.
• a soap charge prepared from a toilet grade standard bleached tallow or the soap obtained from such a tallow may also be treated by the process of this invention particularly when it is desired to obtain a product essentially free of odoriferous compounds.
• alkali metal in this specification is to be taken as referring to lithium, potassium, or sodium.
• the sodium derivative is commercially most readily available.
• the alkali metal borohydride may be added in the process of this invention either in solid form, or as an aqueous solution, or as a blend with soap, or it may be formed in situ from other borohydrides. Preferably it is added as a solution in aqueous alkali-suitable alkalies being sodium hydroxide or potassium hydroxide.
• an alkali metal borohydride By in situ formation of an alkali metal borohydride is meant the addition of a borohydride salt, other than an alkali metal salt, to a soap containing system. Due to the large excess of alkali metal ions which are present in such a system, the borohydride salt will be converted to the alkali metal borohydride.
• the alkali metal borohydride is conveniently added either towards the end of the saponification stage of the soap manufacture or after the saponification has been completed, as, at these points, the pH of the saponification system does not vary so widely as during the initial period of saponification.
• Colour and odour removal can also be effected after the completion of saponification as long as the soap is still in a fluid state ot permit adequate mixing with the borohydride and as long as the pH of the soap does not fall below about 9.5, a preferred range of pH being 9544.0.
• the alkali metal borohydride is preferably added immediately after the soap derived from the saponification process has been washed or immediately prior to the stage when the soap is dried. Alternatively it is possible to add the borohydride to the soap immediately after the end of 3 the drying stage or at the milling stage (with accompanying pigment.)
• the temperature of the soap containing system is adequately controlled and that there is sufficient alkali present in the soap-containing system to allow time for the borohydride to disperse completely and to carry out its reducing action before decomposition.
• the pH be at least 12.0-14.0. With continuous or semi-continuous processing where more efiicient inline mixing is employed pH control need not be quite so stringent.
• the amount of alkali metal borohydride to be used for the improvement of the colour and odour of soap preferably lies within the range of 0.005-0.30% by weight of the total fatty acid content of the soap used.
• a particularly preferred amount of borohydride for the treatment of a soap obtained from a toilet grade standard bleached tallow lies within the range 0.02-0.10% by weight of the fat charge. Addition of borohydride in excess of 0.30% by weight of the fat charge is, of course, also effective but is less likely to be economically attractive.
• the foam formation may be controlled by (a) gradual addition of the borohydride to the soap containing system in a vessel having a volume sufiicient to allow for any expansion of the soap containing system or (b) adding the borohydride to the soap immediately prior to the stage when it is to be pumped into a drier unit and to maintain the soap in this drier unit under pressure until it is sprayed onto a further processing unit.
• EXAMPLE 1 A low grade tallow was treated with four different percentage proportions (ranging from 1-6% w./W.) of fullers earth for 5 minutes at 105 1l0 C. followed by 5 minutes at 110-115 C. After filtration from the fullers earth, the tallows obtained from each of the four bleaching level experiments were divided into three aliquots in beakers, each aliquot containing 20 parts by weight of bleached tallow. After melting these samples of tallow on a boiling water bath, 10 parts by volume of a 30% w./v. aqueous sodium hydroxide solution were added to the first sample from each bleaching level experiment. This mixture was maintained on the boiling water bath and stirred until completely saponified. 9 parts by volume of the 30% w./v. aqueous sodium hydroxide solution were added to the remaining two samples from each bleaching level experiment. These mixtures were subsequently similarly saponified.
• Percent bleaching earth 1 2 4 6 Percent sodium borohydride.. 0 0.05 0.1 0 0.05 0 0.05 0 0.05 0.1 Lovibond Yellow 29 27 15 7.4 6.3 4.0 3.2 2.8 1.5 1.5 Lovibond Red 1.0 1.0 0 8 1.6 1.0 0.8 0.6 0.6 0.3 0.2
• a further advantageous feature of the process of this invention lies in the fact that it is so readily incorporated into a normal soap manufacturing process. Flame-proofing of the soap-making machinery may be necessary in view of the possible hazard associated with the evolution of small volumes of hydrogen.
• the amount of adsorbent agent used in the standard bleaching treatment of a low grade fat charge is preferably about 6% by weight of the fat charge.
• Fullers earth is a preferred bleaching agent, but other adsorbent earths or bleaching carbons may be used.
• the colour and odour of the treated soap depends on the amount and type of adsorbent bleaching agent (if any) that is usd in the pre-treatment of the fat charge, the amount of alkali metal borohydride used, the time and temperature of the treatment with the borohydride, the pH of the soap containing mixture during the borohydride treatment and the efficiency of mixing the soap containing mixture.
• a further beneficial effect that is obtained when the borohydride is added during the saponification stage is that the derived glycerine lye is almost water white.
• a fat charge containing 92.5% w./w. tallow (that had been bleached by treatment with 6% W./W. adsorbent earth) having a Lovibond Yellow reading of 11.7 and a Lovibond Red reading of 1.4 in a 5.1 cm. cell and 7.5% w./w. coconut oil was saponified at C. in a conventional soap pan.
• the soap thus prepared was separated from the lye and washed, in a conventional washing unit, with brine containing 1% w./v. sodium hydroxide.
• As the washed soap passed out of the washing unit it was treated with an amount of aqueous 5.0% w./v. sodium hydroxide solution containing 10 w./ w. sodium borohydride-sufiicient to provide 0.1% sodium borohydride based on the weight of the fat charge originally saponified.
• the borohydride treated soap was subsequently fitted, neutralised, heated and dried according to standard practice.
• the soap colour of the soap prepared in the above experiment was 37, while the soap colour of a soap prepared from a similar fat charge which was not treated with borohydride, was 60.
• EXAMPLE 3 A fat charge containing 92.5% w./w. tallow (that had been bleached by treatment with 6% w./w. adsorbent earth) having a Lovibond Yellow reading of 6.0 and a Lovibond Red reading 0.9 (measured in a 5.1 cm. cell), pan. 7.5% w./w. coconut oil was saponified at 95 C. in a conventional soap pan. The soap thus prepared was separated from the lye and subsequently washed with brine containing 1% w./v. sodium hydroxide. Aqueous 5% w./v. sodium hydroxide solution containing w./w.
• sodium borohydride (in an amount sufiicient to provide 0.02% sodium borohydride by weight of the original fat charge) was added to half the soap as it left the washing unit.
• EXAMPLE 4 A 1.5 ton soap charge was prepared by saponification of a fat charge comprising 85% w./w. tallow and w./w. coconut oil. The lye was separated from this soap charge and the soap washed with brine containing 1% w./v. sodium hydroxide, fitted and passed on to the heat exchanger unit prior to drying, milling and plodding.
• EXAMPLE 5 A 250 lb. fat charge comprising 80% w./w. toilet grade standard bleached tallow and w./w. standard bleached coconut oil was saponified. The soap thus obtained was separated from the lye, washed and fitted. The soap thus obtained had a free alkali content of 0.01%.
• a 40 lb. sample of this soap was heated to 90 C. 750 mls. of a 10% w./ w. sodium borohydride solution in aqueous 5% w./v. sodium hydroxide solution was gradually added to the heated soap with stirring (representing an addition of 0.1% sodium borohydride based on the weight of fatty material present in the soap).
• a further 420 mls. aqueous 5% w./v. sodium hydroxide solution (increasing the amounts of free alkali to 0.5% w./v.) was also added to the soap containing system to reduce the amount of foaming.
• the treated soap was fitted, milled and plodded and its odour evaluated by a panel of assistants who were asked to smell the soaps with closed eyes (thus to prevent any influence of colour difference) and to express an opinion as to which soap had the stronger odour. Since the samples were unperfumed the assessment of the panel members was a direct measure of the strength of the undesirable base odour. Each entry was scored +1 for the tablets with the stronger odour, 0 for no difference and -1 for that which had the weaker odour. The scores for each panel member for each soap were added together to arrive at the total score for each soap. A low score indicated little base odour and a high score indicated strong base .odour.
• the experimental designs contained soap bars not relevant to the present invention and the results on these soap bars were extracted.
• the odour scores for any one series did not therefore lie about the zero mean as they would have done in a complete pad comparison analysis.
• EXAMPLE 6 A further 40 lb. sample of the soap prepared in Example 5' was heated to C. 880- mls. of a 10% w./w. potassium borohydride solution in aqueous 5% w./v. sodium hydroxide solution was gradually added to the soap with stirring (representing an addition of 0.08% w./w. potassium borohydride based on the weight of the fat charge). A further 320 mls. aqueous 5% w./v. sodium hydroxide solution (increasing the amount of free alkali to 0.5% w./v.) was added to the soap to reduce the amount of foaming.
• a panel of 10 people was asked to compare the odour of samples of the soaps treated by the process described in this example, with-a sample of untreated soap and to place each sample according to the degree of deodorisation they thought had been achieved.
• the following table shows the number of people who were able to correctly allot the right position for each sample.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Detergent Compositions (AREA)
• Fats And Perfumes (AREA)

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Cited By (3)

Citations (1)

• 0
  • NL NL122389D patent/NL122389C/xx active
• 1967
  • 1967-06-21 GB GB28652/67A patent/GB1212207A/en not_active Expired
• 1968
  • 1968-06-18 US US737806A patent/US3542823A/en not_active Expired - Lifetime
  • 1968-06-19 AT AT587068A patent/AT285778B/de active
  • 1968-06-19 SE SE08375/68A patent/SE347995B/xx unknown
  • 1968-06-20 ES ES355265A patent/ES355265A1/es not_active Expired
  • 1968-06-20 FR FR1575925D patent/FR1575925A/fr not_active Expired
  • 1968-06-20 NO NO2444/68A patent/NO122389B/no unknown
  • 1968-06-20 CH CH930768A patent/CH535828A/de not_active IP Right Cessation
  • 1968-06-20 NL NL6808646A patent/NL6808646A/xx unknown
  • 1968-06-20 DE DE19681767808 patent/DE1767808A1/de active Pending
  • 1968-06-21 BE BE716996D patent/BE716996A/xx unknown

Patent Citations (1)

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