HK1178561B - Fabric softener active composition - Google Patents

Description

Fabric softener active compositions

The present invention relates to fabric softener active compositions having low levels of flammable solvents, low melt viscosities, and high stability in the molten state.

Quaternary ammonium salts with two hydrophobic long chain hydrocarbon moieties have found widespread use as fabric softener actives. Quaternary ammonium salts of alkanolamines (commonly referred to as quaternary ammonium esters), which are partially esterified with an average of two fatty acids per molecule, have largely replaced the earlier alkyl quaternary ammonium compounds because of their biodegradability.

The bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid diesters which have been used commercially are difficult to handle in the pure state, since the solid state readily cakes, whereas the melt has a high viscosity at low melting temperatures and unsatisfactory stability at higher melting temperatures. Thus, bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid diester is typically shipped as a molten composition containing 13 wt.% ethanol or 2-propanol having a viscosity at a temperature of 65 to 75 ℃ that is sufficiently low to be pumpable. However, such compositions have a low flash point below 30 ℃, and are therefore regulated and require additional safety handling measures.

WO 2007/026314 proposes replacing the flammable solvent in such compositions with 2-40% by weight of a diluent selected from alkyl esters or polyesters, alkyl amides or polyamides, fatty acids, non-ionic surfactants or combinations thereof, and specifically discloses hydrogenated tallow fat, hydrogenated tallow fatty acid, hydrogenated coconut oil, hydrogenated palm stearin, hydrogenated soybean oil, ethylene glycol distearate hard soybean sucrose ester (ethylene glycol stearate hard soy sucrose ester), cetyl palmitate and pentaerythritol tetracaprylate/tetracaprate as suitable diluents. WO 2007/026314 also proposes the use of an additional coupling agent selected from polyols, partial esters of polyol nonionic surfactants, in an amount of 0.1 to 15% by weight. However, the compositions taught by WO 2007/026314 suffer from the disadvantage of low melt stability in the dealkylation of quaternary ammonium salts, resulting in an increase in the content of free esteramines during transport and handling in the melt.

Thus, there remains a need for fabric softener active compositions having low melt viscosity and high stability in the molten state and at the same time low flammability.

It has been found that fabric softener active compositions based on bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid esters made from fatty acids having a specific chain length and a specific degree of unsaturation, and having a specific molar ratio of fatty acid moieties to amine moieties, which compositions comprise a specific amount of fatty acid triglycerides having a specific lower chain length of fatty acid moieties, and a specific amount of an alcohol selected from ethanol, 1-propanol and 2-propanol, exhibit an unexpectedly low combination of low melt viscosity, high stability to dealkylation in the molten state and low flammability.

Accordingly, the present invention relates to a fabric softener active composition comprising:

a) 65-95% by weight of a bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester having a molar ratio of fatty acid moieties to amine moieties of 1.80-1.96, the fatty acid moieties having an average chain length of 16-18 carbon atoms and an iodine value, calculated as free fatty acid, of 0-50;

b) 2-8% by weight of fatty acid triglycerides having an average chain length of the fatty acid moieties of 10-14 carbon atoms and an iodine value, calculated as free fatty acids, of 0-15; and

c) 3-12% by weight of an alcohol selected from the group consisting of ethanol, 1-propanol and 2-propanol.

The invention also relates to a process for preparing such a composition, comprising the steps of:

a) reacting a mixture comprising 78-95 wt.% of a bis- (2-hydroxyethyl) -methylamine fatty acid ester, 2-9 wt.% of a fatty acid triglyceride having an average chain length of 16-18 carbon molecules and an iodine value calculated as free fatty acid of 0-50, and 3-13 wt.% of an alcohol selected from ethanol, 1-propanol and 2-propanol with an excess of methyl chloride at a temperature of 60-120 ℃ to provide a reaction mixture, the molar ratio of the fatty acid moiety to the amine moiety of the bis- (2-hydroxyethyl) -methylamine fatty acid ester being 1.80-1.96, the average chain length of the fatty acid moiety being 16-18 carbon molecules and the iodine value calculated as free fatty acid being 0-50, the average chain length of the fatty acid moiety of the fatty acid triglyceride being 10-14 carbon atoms and the iodine value calculated as free fatty acid being 0-15; and

b) separating unreacted methyl chloride from the reaction mixture of step a) by distilling off a mixture of methyl chloride and the alcohol, condensing alcohol from the mixture of methyl chloride and alcohol, and returning the condensed alcohol to the reaction mixture to provide an alcohol content of 3-12 wt.%.

The present invention also relates to an alternative process for preparing such a composition, comprising the steps of:

a) reacting a mixture comprising 88-98 wt.% of a bis- (2-hydroxyethyl) -methylamine fatty acid ester, 2-9 wt.% of a fatty acid triglyceride having an average chain length of 10-14 carbon atoms and an iodine value of 0-15 calculated as free fatty acid, and 0-3 wt.% of an alcohol selected from ethanol, 1-propanol, and 2-propanol, with an excess of methyl chloride at a temperature of 60-120 ℃ to provide a reaction mixture, the molar ratio of the fatty acid moiety to the amine moiety of the bis- (2-hydroxyethyl) -methylamine fatty acid ester being 1.80-1.96, the average chain length of the fatty acid moiety being 16-18 carbon molecules and the iodine value calculated as free fatty acid being 0-50; and

b) adding more of the alcohol to the reaction mixture of step a) to provide an alcohol content of 3-12 wt%; and

c) separating unreacted methyl chloride from the mixture of step b) by distilling off a mixture of methyl chloride and the alcohol, condensing alcohol from the mixture of methyl chloride and alcohol, and returning the condensed alcohol to the reaction mixture to provide an alcohol content of 3-12 wt.%.

The fabric softener active composition of the invention comprises 65 to 95 weight percent of bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester. The composition preferably comprises 80-90 wt% of the ester.

The fatty acid ester of bis- (2-hydroxyethyl) dimethylammonium chloride comprises at least one compound of formula (CH)₃)₂N⁺(CH₂CH₂OC(=O)R)₂Cl^-And at least one diester of the formula (CH)₃)₂N⁺(CH₂CH₂OH)(CH₂CH₂OC(=O)R)Cl^-Wherein R is the hydrocarbyl group of the fatty acid moiety RCOO. The molar ratio of fatty acid moieties to amine moieties of the bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester is 1.80-1.96, preferably 1.85-1.94. The specific molar ratios provide high softening performance in a rinse cycle fabric softener.

The fatty acid portion of the bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester can be derived from a mixture of pure fatty acids or fatty acids of the formula RCOOH, where R is a hydrocarbyl group. The hydrocarbon radical may be branched or unbranched, preferably unbranched.

The fatty acid moiety has an average chain length of 16 to 18 carbon atoms and an iodine value, calculated as free fatty acid, of 0 to 50. The average chain length is preferably from 16.5 to 17.8 carbon atoms. Preferably, the fatty acid moiety has an iodine value of from 1.0 to 50, more preferably from 2 to 50, more preferably from 5 to 40 and most preferably from 15 to 35. In the mixture of fatty acids, the average chain length is calculated on the basis of the weight proportion of the individual fatty acids. For branched chain fatty acids, chain length refers to the longest continuous chain of carbon atoms. The iodine value is the number of grams of iodine consumed by the reaction of the double bond of 100g of fatty acid determined by the method of ISO 3961. To provide the desired average chain length and iodine value, the fatty acid moiety can be derived from a fatty acid mixture comprising saturated fatty acids and unsaturated fatty acids. The unsaturated fatty acid is preferably a monounsaturated fatty acid. The bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester preferably comprises less than 6 wt.% polyunsaturated fatty acid moieties. Examples of suitable saturated fatty acids are palmitic acid and stearic acid. Examples of suitable monounsaturated fatty acids are oleic acid and elaidic acid. The cis-trans ratio of the double bonds of the unsaturated fatty acid moieties is preferably higher than 55:45, and more preferably higher than 65: 35. The proportion of polyunsaturated fatty acid moieties can be reduced by selective contact hydrogenation, wherein the hydrogenation selectively hydrogenates-CH = CH-CH₂-CH = one double bond in the CH-substructure, but without hydrogenating the double bond of the monounsaturated hydrocarbon radical. For the simultaneous realization of said combinationsHigh softening properties and low melting points of the compounds, specific average chain lengths and iodine values are necessary. If the average chain length is less than 16 carbon atoms or the iodine value is above 50, the softening properties may be undesirable, whereas if the average chain length exceeds 18 carbon atoms, the melting point of the composition may be too high.

The fatty acid moiety may be derived from fatty acids of natural or synthetic origin, preferably from fatty acids of natural origin, most preferably from tallow fatty acids. The desired iodine value can be provided by using a naturally derived fatty acid mixture (e.g., tallow fatty acid) which already has such an iodine value. Alternatively, the desired iodine value may be provided by partially hydrogenating a mixture of fatty acids or triglycerides having a higher iodine value. In a further preferred embodiment, the desired iodine value is provided by mixing a fatty acid mixture having a higher iodine value with a saturated fatty acid mixture. The mixture of saturated fatty acids can be obtained by hydrogenating a fatty acid mixture containing unsaturated fatty acids or from a hydrogenated triglyceride mixture, such as hydrogenated vegetable oil.

The fabric softener active composition according to the invention further comprises 2-8 wt.%, preferably 3-6 wt.% of fatty acid triglycerides having fatty acid moieties with an average chain length of 10-14 carbon atoms and an iodine value of 0-15 calculated as free fatty acids. The average chain length of the fatty acid moieties is preferably from 12 to 13.8 carbon atoms. The fatty acid triglyceride is preferably coconut oil or hydrogenated coconut oil, most preferably refined coconut oil. The amount of specific fatty acid triglycerides and the average chain length of the fatty acid moieties are necessary to achieve both a low melting point and low flammability of the fabric softener active composition. Surprisingly, the specific amount of fatty acid triglyceride also improves the softening efficiency of rinse cycle softeners prepared from the fabric softener active compositions of the present invention.

The fabric softener active composition of the present invention further comprises 3 to 12 wt.%, preferably 6 to 10 wt.% of an alcohol selected from the group consisting of ethanol, 1-propanol and 2-propanol. The alcohol is preferably ethanol or 2-propanol, most preferably 2-propanol. The specific amount of alcohol is necessary to achieve both low flammability of the fabric softener active composition and high stability of the composition in the molten state to dealkylation of bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid esters. The improvement in stability that can be achieved by a specific amount of alcohol appears to be for the chloride salt, which is not recognized in the prior art.

The combined amount of fatty acid triglyceride and alcohol is preferably 10-15% by weight.

The fabric softener active compositions of the present invention exhibit a combination of high stability to dealkylation in the molten state, low melt viscosity and low flammability. The fabric softener composition comprising 86 wt.% of bis- (2-hydroxyethyl) dimethylammonium chloride tallow fatty acid ester, 3 wt.% of coconut oil and 9 wt.% of 2-propanol has a flash point of 38 ℃ determined according to DIN 53213.

The fabric softener active composition of the invention can be prepared by mixing the fatty acid ester of bis- (2-hydroxyethyl) dimethylammonium chloride, the fatty acid triglyceride and the alcohol in specific amounts. However, the fabric softener active composition is preferably prepared by one of the two methods of the present invention, which are common in that bis- (2-hydroxyethyl) methylamine fatty acid esters are quaternized with excess methyl chloride in the presence of fatty acid triglycerides, followed by separation of excess methyl chloride in the presence of alcohol.

The first method of the present invention comprises two steps.

In a first step a mixture comprising 78-95 wt.% of bis- (2-hydroxyethyl) methylamine fatty acid ester, 2-9 wt.% of fatty acid triglycerides and 3-13 wt.% of an alcohol (selected from ethanol, 1-propanol, 2-propanol) is reacted with an excess of methyl chloride at a temperature of 60-120 ℃, preferably 90-110 ℃. The molar amount of methyl chloride is greater than the molar amount of the bis- (2-hydroxyethyl) methylamine fatty acid ester, and the molar ratio of methyl chloride to bis- (2-hydroxyethyl) methylamine fatty acid ester is preferably 1.1 to 1.5. The molar ratio of fatty acid moieties to amine moieties of the bis- (2-hydroxyethyl) methylamine fatty acid ester is from 1.80 to 1.96, preferably from 1.82 to 1.92, the fatty acid moieties have an average chain length of from 16 to 18 carbon atoms, preferably from 16.5 to 17.8 carbon atoms, and an iodine value, calculated as free fatty acid, of from 0 to 50, preferably from 1.0 to 50, more preferably from 2 to 50, even more preferably from 5 to 40, and most preferably from 15 to 35. The fatty acid triglyceride preferably has an average chain length of the fatty acid moieties of 10-14 carbon atoms, preferably 12-13.8 carbon atoms, an iodine value calculated as free fatty acids of 0-15, and is coconut oil or hydrogenated coconut oil. The reaction is preferably carried out in a pressure vessel at a total pressure of 1 to 10bar, preferably 3 to 8 bar. Methyl chloride is preferably added to the mixture of bis- (2-hydroxyethyl) methylamine fatty acid ester, fatty acid triglyceride and alcohol at a rate that avoids a pressure increase above a certain upper limit. The reaction is preferably carried out until more than 80%, preferably more than 85% of the bis- (2-hydroxyethyl) methylamine fatty acid ester has reacted. Suitable reaction times are in the range from 2 to 8h, depending on the reaction temperature and pressure.

In a second step, unreacted methyl chloride is separated from the reaction mixture of step a) by distilling off a mixture of methyl chloride and the alcohol, the alcohol is condensed from the mixture of methyl chloride and alcohol, and the condensed alcohol is returned to the reaction mixture to provide an alcohol content of 3-12% by weight. The mixture of methyl chloride and alcohol is preferably distilled off at a total pressure of 0.2 to 1 bar. The alcohol is preferably condensed from the mixture of methyl chloride and alcohol in a partial condenser (partial condenser) at a temperature between the boiling points of methyl chloride and alcohol under the pressure used for distillation. All or part of the condensed alcohol may be returned to the reaction mixture, depending on the desired alcohol content of the obtained mixture.

The second process of the invention comprises three steps which differ from the first process of the invention in that the starting mixture in the first step comprises 88-98 wt.% of the fatty acid ester of bis- (2-hydroxyethyl) methylamine and 0-3 wt.% of the alcohol, and that in an additional step more alcohol is added to the reaction mixture of the first step to provide an alcohol content of 3-12 wt.% before the step of separating unreacted methyl chloride from the mixture is carried out.

Both methods of the present invention have the advantage of providing fabric softener active compositions with low levels of non-quaternized bis- (2-hydroxyethyl) methylamine fatty acid esters in short reaction times. The second process of the present invention has the additional advantage that the formation of by-products from the alkylation of alcohols is low and the alkylation reaction time is further reduced.

The invention is illustrated by the following examples, which are not intended to limit the scope of the invention in any way.

Examples

Fabric softener active compositions were prepared from coconut oil, 2-propanol and bis- (2-hydroxyethyl) dimethylammonium chloride tallow fatty acid ester having an iodine value, calculated as free fatty acid, of 20, a molar ratio of fatty acid moieties to amine moieties of 1.89, and containing 0.044mmol/g bis- (2-hydroxyethyl) methylamine fatty acid ester, 0.041mmol/g bis- (2-hydroxyethyl) methylammonium chloride fatty acid ester and 0.111mmol/g fatty acid by mixing powdered quaternary ammonium salt and solvent in the amounts given in table 1 and melting the mixture.

The storage stability was determined for the fabric softener active compositions stored in closed glass bottles for 5 days at 100 ℃.

By using 50mm parallel plates at 90 deg.CThe melt viscosity was determined by a stressTech rheometer with a plate-to-plate distance of 1mm and a shear rate of 1s^-1、10s^-1And 100s^-1。

TABLE 1 characteristics of fabric softener active compositions

Not in accordance with the invention

Claims (8)

1. A fabric softener active composition comprising

a) 65-95% by weight of a bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester having a molar ratio of fatty acid moieties to amine moieties of 1.80-1.96, the fatty acid moieties having an average chain length of 16-18 carbon atoms and an iodine value, calculated as free fatty acid, of 0-50 excluding 0;

b) 2-8% by weight of fatty acid triglycerides having an average chain length of the fatty acid moieties of 10-14 carbon atoms and an iodine value calculated as free fatty acids of 0-15, excluding 0; and

c) 3-12% by weight of an alcohol selected from the group consisting of ethanol, 1-propanol and 2-propanol.

2. The fabric softener active composition of claim 1 comprising 3-6% by weight of said fatty acid triglyceride and 6-10% by weight of said alcohol.

3. The fabric softener active composition of claim 1 or 2, wherein the combined amount of the fatty acid triglyceride and the alcohol is 10-15% by weight.

4. The fabric softener active composition of claim 1 or 2, wherein the fatty acid triglyceride is coconut oil or hydrogenated coconut oil.

5. The fabric softener active composition of claim 1 or 2 wherein the iodine value, calculated as free fatty acid, of the fatty acid moiety of the bis- (2-hydroxyethyl) dimethylammonium chloride fatty acid ester is from 15 to 35.

6. A process for preparing the fabric softener active composition of claim 1 comprising the steps of:

a) reacting a mixture comprising 78-95 wt.% of a bis- (2-hydroxyethyl) -methylamine fatty acid ester, 2-9 wt.% of a fatty acid triglyceride, and 3-13 wt.% of an alcohol with an excess of methyl chloride at a temperature of 60-120 ℃ to provide a reaction mixture, the bis- (2-hydroxyethyl) -methylamine fatty acid ester has a molar ratio of fatty acid moieties to amine moieties of 1.80 to 1.96, an average chain length of the fatty acid moieties of 16 to 18 carbon molecules and an iodine value, calculated as free fatty acid, of 0 to 50, excluding 0, the fatty acid triglyceride having an average chain length of the fatty acid moieties of 10 to 14 carbon atoms and an iodine value calculated as free fatty acids of 0 to 15 excluding 0, the alcohol being selected from the group consisting of ethanol, 1-propanol and 2-propanol; and

b) separating unreacted methyl chloride from the reaction mixture of step a) by distilling off a mixture of methyl chloride and the alcohol, condensing alcohol from the mixture of methyl chloride and alcohol, and returning the condensed alcohol to the reaction mixture to provide an alcohol content of 3-12 wt.%.

7. A process for preparing the fabric softener active composition of claim 1 comprising the steps of

a) Reacting a mixture comprising 88-98 wt.% of a bis- (2-hydroxyethyl) -methylamine fatty acid ester, 2-9 wt.% of a fatty acid triglyceride, and 0-3 wt.% of an alcohol with an excess of methyl chloride at a temperature of 60-120 ℃ to provide a reaction mixture, the bis- (2-hydroxyethyl) -methylamine fatty acid ester has a molar ratio of fatty acid moieties to amine moieties of 1.80 to 1.96, an average chain length of the fatty acid moieties of 16 to 18 carbon molecules and an iodine value, calculated as free fatty acid, of 0 to 50, excluding 0, the fatty acid triglyceride having an average chain length of the fatty acid moieties of 10 to 14 carbon atoms and an iodine value calculated as free fatty acids of 0 to 15 excluding 0, the alcohol being selected from the group consisting of ethanol, 1-propanol and 2-propanol;

b) adding more of the alcohol to the reaction mixture of step a) to provide an alcohol content of 3-12 wt%; and

c) separating unreacted methyl chloride from the mixture of step b) by distilling off a mixture of methyl chloride and the alcohol, condensing alcohol from the mixture of methyl chloride and alcohol, and returning the condensed alcohol to the reaction mixture to provide an alcohol content of 3-12 wt.%.

8. The process according to claim 6 or 7, wherein the mixture of methyl chloride and alcohol is distilled off at a total pressure of 0.2-1 bar.