WO1995022519A1

WO1995022519A1 - Synthesis of polyhydroxy fatty acid amides from triglycerides

Info

Publication number: WO1995022519A1
Application number: PCT/US1995/001687
Authority: WO
Inventors: Jeffrey John Scheibel; Randall Thomas Reilman; Joe Frederick Sherman
Original assignee: The Procter & Gamble Company
Priority date: 1994-02-17
Filing date: 1995-02-10
Publication date: 1995-08-24
Also published as: MX9603509A; JPH09509416A; CN1145063A

Abstract

Fats and oils such as hardened palm kernel oil are reacted directly with N-substituted polyhydroxy amines to provide high yields of N-substituted polyhydroxy fatty acid amide surfactants having improved odors and low fatty acid content. Hardened palm kernel oil is reacted with N-methylglucamine in the presence of an ethoxylated alcohol, but in the absence of methanol solvent, using sodium propylene glycolate catalyst to provide the mixed corresponding fatty acid amide of N-methylglucamine.

Description

SYNTHESIS OF POLYHYDROXY FATTY ACID AMIDES FROM TRIGLYCERIDES

FIELD OF THE INVENTION The present invention relates to a process for preparing detersive surfactants. CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of co-pending application serial number 08/198,008, filed February 17, 1994.

BACKGROUND OF THE INVENTION The synthesis of polyhydroxy fatty acid amide surfactants on an industrial scale is becoming of considerable importance. This class of nonionic surfactants is finding utility in a wide variety of laundering and dishwashing compositions. Polyhydroxy fatty acid amide surfactants exhibit high grease and oil removal performance, mildness to skin and fabrics, and are available from non-petrochemical resources.

The synthesis of polyhydroxy fatty acid amide surfactants is not a routine matter. Unfortunately, these materials are heat labile, and, during synthesis, can undesirably form darkened color bodies. Moreover, their polyhydroxy substiruent group can undesirably cyclize, with the formation of unwanted by-products. In addition, certain ester-amide materials can be formed. In general, however, these synthetic problems can be overcome by means of alcohol solvents and the proper selection of catalysts and reaction temperatures. Such matters are described in U.S. Patent 5,194,639.

However, it has also been recognized that the manufacture of polyhydroxy fatty acid amide surfactants from polyhydroxy amines and fatty acid methyl esters can result in reaction products which are undesirably contaminated with free fatty acids and/or sources of "nascent" fatty acids. As described in U.S. Patent 5,188,769, such fatty acid materials can be converted into their amide form in a separate reaction step. However, it would be desirable if a synthesis of polyhydroxy fatty acid amide surfactants could be devised which would not result in the formation of free fatty acids in the main reaction product. This is particularly true in circumstances where the odor of the polyhydroxy fatty acid amide is of concern to the formulator, inasmuch as odors from even small amounts of fatty acid impurities can be quite offensive. By the present invention it has been determined that triglycerides, such as those which constitute natural fats and oils, can be reacted directly with polyhydroxy amines to form the desired polyhydroxy fatty acid amide surfactants, but with minimal formation of fatty acids in overall reaction product. The improved process as described herein allows the formulator to work directly with the fats and oils without the need for first converting them into methyl esters. This can result in substantial savings of time and expense. Moreover, the additional fatty acid removal step as disclosed in US 5,188,769, cited above, can be avoided. Importantly, the improved process disclosed herein provides high yields of high quality, non- odoriferous polyhydroxy fatty acid amides which are suitable for use as detersive surfactants and for other uses.

BACKGROUND ART U.S. Patents 5,338,487, 5,338,486, 5,334,764, 5,194,639, 5,188,769, 1,985,424, 2,016,962, 2,653,932, 2,703,798, EPO 91917936.6, EP 558,515, EP 556,348, Japanese Kokai Hei 3[1991]-246265 and DE 4,235,783 and 4,235,784 all relate to various aspects of the synthesis of polyhydroxy fatty acid amides.

SUMMARY OF THE INVENTION

The present invention encompasses, in a method for preparing a polyhydroxy fatty acid amide surfactant reaction product by reacting a fatty acid ester with an N- alkyl, N-alkoxy or N-aryloxy polyhydroxy amine, the improvement which comprises conducting the reaction using a fatty acid triglyceride as the fatty acid ester, and in the absence of a monohydric alcohol solvent, whereby the fatty acid content of the reaction product is minimized to a level not greater than about 1% by weight of said reaction product, typically not greater than about 0.2% by weight of said reaction product. Moreover, the reaction product herein also typically will contain as low as about l%-4%, and even as low as 0.1%, by weight, of the polyhydroxy amine reactant. In a preferred process, the reaction product comprises less than about

0.2%, preferably less than about 0.1%, by weight, of fatty acid and less than about

0.2%, preferably less than about 0.1%, of unreacted polyhydroxy amine. While the reaction herein does not employ an alcohol solvent, it most preferably involves conducting the reaction in the presence of an alkoxylated alcohol

(preferably, NEODOL) or alkoxylated alkyl phenol. Moreover, the reaction is preferably conducted in the presence of an alkoxide catalyst selected from the alkali metal salts of a polyhydroxy alcohol, especially the alkali metal salts of ethylene glycol, 1,2- or 1,3-propylene glycol or glycerol.

All percentages, ratios and proportions herein are by weight, unless otherwise specified. Relevant parts of all cited documents are incorporated herein by reference. DETAILED DESCRIPTION OF THE INVENTION The N-alkyl polyhydroxy fatty acid amide surfactants provided by the present process comprise materials of the formula:

O R⁴

R ^>-c-ύ-; (I)

The N-alkoxy or N-aryloxy polyhydroxy fatty acid amide surfactants provided by the present process comprise materials of the formula:

wherein in formulas (I) and (II): R^ is C5-C31 hydrocarbyl, preferably C9-C17 hydrocarbyl, including straight-chain and branched-chain alkyl and alkenyl, or mixtures thereof; R¹ is C2-Cg hydrocarbyl including straight-chain, branched-chain and cyclic (including aryl), and is preferably C2-C4 alkylene, i.e., -CH2CH2-, - CH2CH2CH2- and -CH2(CH2)2CH₂-; R² is Ci-Cg straight-chain, branched-chain and cyclic hydrocarbyl including aryl and oxy-hydrocarbyl, and is preferably C1-C4 alkyl, especially methyl, or phenyl. In compounds of Formula (I), R^ is typically Ci- Cg alkyl or hydroxyalkyl, including methyl (preferred), ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, 2-hydroxyethyl, 3-hydroxypropyl, and the like. Z is a polyhydroxyhydrocarbyl moiety having a linear hydrocarbyl chain with at least 2 (in the case of glyceraldehyde) or at least 3 hydroxyls (in the case of other reducing sugars) directly connected to the chain, or an alkoxylated derivative (preferably ethoxylated or propoxylated) thereof. Z preferably will be derived from a reducing sugar in a reductive amination reaction; most preferably Z is a glycityl moiety. Suitable reducing sugars include glucose, fructose, maltose, lactose, galactose, mannose, and xylose, as well as glyceraldehyde. As raw materials, high dextrose corn syrup, high fructose corn syrup, and high maltose corn syrup can be utilized as well as the individual sugars listed above. These corn syrups may yield a mix of sugar components for Z. It should be understood that it is by no means intended to exclude other suitable raw materials. Z preferably will be selected from the group consisting of -CH₂-(CHOH)_n-CH₂OH, -CH(CH₂OH)-(CHOH)_n.₁-CH2θH, -CH₂- (CHOH)2(CHOR')(CHOH)-CH2OH, where n is an integer from 1 to 5, inclusive, and R' is H or a cyclic mono- or poly- saccharide, and alkoxylated derivatives thereof. As noted, most preferred are glycityls wherein n is 4, particularly -CH2- (CHOH)4-CH₂OH. In compounds of the above formula (II), nonlimiting examples of the amine substituent group -R^-O-R² can be, for example: 2-methoxyethyl-, 3-methoxy- propyl-, 4-methoxybutyl-, 5-methoxypentyl-, 6-methoxyhexyl-, 2-ethoxyethyl-, 3- ethoxypropyl-, 2-methoxypropyl, methoxybenzyl-, 2-isopropoxyethyl-, 3-iso- propoxypropyl-, 2-(t-butoxy)ethyl-, 3-(t-butoxy)propyl-, 2-(isobutoxy)ethyl-, 3- (isobutoxy)propyl-, 3-butoxypropyl, 2-butoxyethyl, 2-phenoxyethyl-, methoxy- cyclohexyl-, methoxycyclohexylmethyl-, tetrahydrofurfuryl-, tetrahydropyran- oxyethyl-, 3-[2-methoxyethoxy]propyl-, 2-[2-methoxyethoxy]ethyl-, 3-[3-meth- oxypropoxy]propyl-, 2-[3-methoxypropoxy] ethyl-, 3-[methoxypolyethylene- oxy]propyl-, 3-[4-methoxybutoxy]propyl-, 3-[2-methoxyisopropoxy]propyl, CH3O- CH₂CH(CH₃)- and CH₃OCH₂CH(CH3)CH2-O-(CH2)3-.

In compounds of the above formulas I and π, R^-CO-N< can be, for example, cocoamide, stearamide, oleamide, lauramide, myristamide, capricamide, palmitamide, tallowamide, etc. As an overall proposition, the improved synthesis method for these surfactants comprises reacting the corresponding N-substituted polyhydroxy amines with fatty acid triglycerides without a monohydric alcohol solvent, but preferably with an ethoxylated alcohol such as NEODOL, using a specified type of alkoxide catalyst at temperatures of typically about 50°C to about 140°C for batch processes to provide high yields (90-98%) of the products having desirable low levels not only of fatty acids as noted above, but also low levels (preferably, less than about 1%) of ester amide or cyclized by-products and also with improved color and improved color stability, e.g., Gardner Colors below about 4, preferably between 0 and 2. For a continuous process, temperatures up to about 180°C may be used. If desired, any unreacted polyhydroxy amine remaining in the product can be acylated with an acid anhydride, e.g., acetic anhydride, maleic anhydride, or the like, in water at 50°C- 85°C to minimize the overall level of such residual amines in the product. However, the present process has the advantage that the level of unreacted polyhydroxy amine in the final product can be as low as 0.1%; accordingly, this additional step can often be omitted.

By "cyclized by-products" herein is meant the undesirable reaction by¬ products of the primary reaction wherein it appears that the multiple hydroxyl groups in the polyhydroxy fatty acid amides can form ring structures. It will be appreciated by those skilled in the chemical arts that the preparation of the polyhydroxy fatty acid amides herein using the di- and higher saccharides such as maltose will result in the formation of polyhydroxy fatty acid amides wherein linear substituent Z (which contains multiple hydroxy substituents) is naturally "capped" by a polyhydroxy ring structure. Such materials are not cyclized by-products, as defined herein.

If desired, the water solubility of the solid polyhydroxy fatty acid amide surfactants herein can be enhanced by quick cooling from a melt. While not intending to be limited by theory, it appears that such quick cooling re-solidifies the melt into a metastable solid which is more soluble in water than the pure crystalline form of the polyhydroxy fatty acid amide. Such quick cooling can be accomplished by any convenient means, such as by use of chilled (0°C-10°C) rollers, by casting the melt onto a chilled surface such as a chilled steel plate, by means of refrigerant coils immersed in the melt, or the like. This additional processing step is especially useful with the N-alkoxy polyhydroxy fatty acid amides, but its use is not limited thereto.

Triglyceride Reactant - The triglycerides used in the present process can be any of the well-known fats and oils, such as those conventionally used as foodstuffs or as fatty acid sources. Non-limiting examples include: CRISCO® oil; palm oil; high oleoyl sunflower oil and high euricic rapeseed oil; palm kernel oil; corn oil; cottonseed oil; soybean oil; tallow; lard; canola oil; rapeseed oil; peanut oil; tung oil; olive oil; menhaden oil; coconut oil; castor oil; sunflower seed oil; palm stearine; and the corresponding "hardened", i.e., hydrogenated oils. If desired, low molecular weight or volatile material can be removed from the oils by steam-stripping, vacuum stripping, treatment with carbon or "bleaching earths" (diatomaceous earth), or cold tempering to further minimize the presence of malodorous by-products in the surfactants prepared by the present process.

N-substituted Polyhydroxy Amine Reactant - The N-alkyl, N-alkoxy or N- aryloxy polyhydroxy amines used herein are commercially available, or can be prepared by reacting the corresponding N-substituted amine with a reducing sugar, typically in the presence of hydrogen and a nickel catalyst as disclosed in the art. Non-limiting examples of such materials include: N-methylglucamine (preferred herein); N-(3-methoxypropyl)glucamine; N-(2-methoxyethyl)glucamine; N-propyl- glucamine; N-butylmaltamine; N-hexylglucamine, and the like. Catalyst - The preferred catalysts herein are the alkali metal salts of polyhydroxy alcohols having at least two hydroxyl groups. The sodium (preferred), potassium or lithium salts may be used. The alkali metal salts of monohydric alcohols (e.g., sodium methoxide, sodium ethoxide, sterically hindered monohydric alcohols such as sodium tert-butoxide may also be preferred, etc.) may be used herein, but are not preferred because of the possible formation of malodorous short-chain methyl esters, and the like. Rather, it has been found to be advantageous to use the alkali metal salts of polyhydroxy alcohols to avoid such problems. Typical, non-limiting examples of such catalysts include: sodium glycolate, sodium glycerate and propylene glycolates such as sodium propyleneglycolate (both 1,3- and 1,2-glycolates can be used; the 1,2-isomer is preferred), and 2-methyl-l,3-propyleneglycolate. Sodium salts of NEODOL-type ethoxylated alcohols can also be used. Reaction Medium - The process herein is preferably not conducted in the presence of a monohydric alcohol such as methanol, because malodorous acid esters may form. However, it is preferred to conduct the reaction in the presence of a material such as an alkoxylated alcohol or alkoxylated alkyl phenol of the surfactant type which act as a phase transfer agent to provide a substantially homogeneous reaction mixture of the polyhydroxy amine and triglyceride reactants. Typical examples of such materials include: NEODOL 10-8, NEODOL 23-3, NEODOL 25- 12 AND NEODOL 11-9 and GENAPOL 26-L-5. Pre-formed quantities of compounds of formulas (I) and (II) can also be used for this purpose. In a typical mode, the reaction medium will comprise from about 10% to about 25% by weight of the total reactants.

Reaction Conditions - The process herein is preferably conducted in the melt. N-substituted polyhydroxy amine, the phase transfer agent (preferred NEODOL) and triglyceride oil are co-melted at 120°C-140°C under vacuum for about 30 minutes. The catalyst (preferably, sodium propylene glycolate) at about 5 mole % relative to the polyhydroxy amine is added to the reaction mixture. The reaction becomes homogeneous in a few seconds. The reaction mixture is immediately cooled to about 85°C. At this point, the reaction is nearly complete. The reaction mixture is held under vacuum for an additional hour and is complete at this point.

In an alternate mode, the NEODOL, oil, catalyst and polyhydroxy amine are mixed at room temperature. The mixture is heated to 85°C-90°C, under vacuum. The reaction becomes clear (homogeneous) in about 75 minutes. The reaction mixture is maintained at about 90°C, under vacuum, for an additional two hours. At this point the reaction is complete.

In the foregoing reactions, the mole ratio of triglyceride oi polyhydroxy amine is typically in the range of about 1 :2 to 1 :3.0.

Product Work-Up: The product of the present process will contain the polyhydroxy fatty acid amide surfactant and glycerol. The glycerol may be removed by distillation, if desired.

The following describes and illustrates the syntheses in more detail. Preparation of Low Odor and Low Color Polyhydroxy Fatty Acid Amides

Fully hydrogenated palm kernel oil (733.8 grams, 1.0418 moles, 1.0 mole equivalents) is melted and placed under vacuum for 0.5 to 1 hours at 70°C to 100°C to remove any volatiles. NEODOL 25-12 (320 grams) is also melted and placed under vacuum for 0.5 to 1.0 hours at 70°C to 100°C to remove volatiles. At 60°C the palm kernel oil and NEODOL 25-12 are loaded into a 3 liter, 3 neck round bottom flask under nitrogen. The flask is fitted with mechanical stirrer, thermometer and gas inlet/outlet. The mixture is stirred while powdered N-methylglucamine (E. Merck, 521.6 grams, 2.6720 moles, 2.56 mole equivalents) is added. After all the N- methylglucamine is added, the reaction mixture is placed under vacuum and heated to 85°C. 1,2-Propylene glycolate (54.73 grams of 24% solution in propylene glycol, 0.1336 moles, 5 mole % relative to N-methylglucamine) solution is added as catalyst. The reaction mixture is placed under vacuum. The slurry clears within 1 to 2 hours. The reaction mixture is stirred at 85°C for a total of four hours. Small pieces of unreacted N-methylglucamine are filtered out and reaction mixture is bottled and allowed to solidify. Conversation of N-methylglucamine to the fatty acid amide surfactant is typically 95-99% and can be as high as 99.95% depending on reaction conditions and ratio of oil used. The material has low odor and, typically, contains less than about 0.2% by weight of fatty acid contaminants as measured by gas chromatography.

The above procedure can be conducted using N-(3-methoxypropyl) glucamine in place of N-methylglucamine to secure the corresponding fatty acid amide surfactant.

The following illustrates the industrial use of the polyhydroxy fatty acid amide surfactants made by the process of this invention, but is not intended to be limiting thereof. Various laundering dishwashing and personal cleaning compositions in the form of granules, bars, flakes, liquids and gels can be formulated using the surfactants provided herein.

EXAMPLE I A liquid laundry detergent composition comprises the following: Ingredient % (wt ^c12-14 ^{E0 2}-^{25 sulfate 15} ° C12-14 alkyl sulfate 6.0

Fatty Acid N-methyl glucamide* 6.0

Sodium citrate 6.0

Monoethanolamine 2.5

Water/1, 2-propylene glycol/ethanol (100: 1 : 1) Balance *Manufactured using hardened palm kernel fatty acids.

In the above formulation, the glucamide surfactant can be replaced by an equivalent amount of the hardened palm kernel fatty acid amides of N-(3- methoxypropyl) glucamine to secure improved inhibition of dye transfer between fabrics.

The following further illustrates the present process. In general, the operating parameters preferably take into account the following four factors. 1. Dehydrate the N-methylglucamine (NMG) by heating to 120°C and then using vacuum to less than 100 mm Hg for 30 minutes. 2. Add the pretreated hardened palm kernel oil (70°C) to the N-methylglucamine solution. Additional water should be extracted. Maintain at 120°C and slight vacuum for approximately 30 minutes. 3. Slurry sodium methylate powder in NEODOL or propylene glycol (5 mol. %; preferably 8-10 mol. %) and add it to the reaction mixture. This will bring down the temperature of the mixture; the optimum reaction temperature is 100-105°C. Run the reaction under 200-300 mm Hg or, alternatively, a nitrogen blanket. 4. The approximate reaction time will be 3-4 hours. Adding some (e.g., 1-2% of the catalyst after the reaction has been running about 2 hours can result in higher conversions.

EXAMPLE π

H-PKO Glucose Amide Melt Reaction with Neodol 11-9. To a 1000 ml three-necked round-bottomed flask equipped with an internal thermometer, vacuum line, nitrogen line and mechanical stirrer is added powdered N- methylglucamine (245.98 g, 1.26 mol). The N-methylglucamine is melted at 130-

140°C and dried under vacuum. To a separate 1000 ml round-bottom flask equipped with internal thermometer and vacuum line is added hardened palm kernel oil (305 g, 0.434 mol) and Neodol 11-9 (102.36 g). The hardened palm kernel oil

(H-PKO)/Neodol 11-9 is heated to 130-140°C and dried under vacuum. To the dried N-methylglucamine, with mixing, is added the dried hardened palm kernel oil/Neodol 11-9 mixture. To this mixture, at 136°C, is added sodium methoxide

(3.40 g, 0.063 mol) as a 25 wt. % solution in methanol and full vacuum applied immediately to remove methanol. The mixture becomes homogeneous in 1 minute at which time cooling is applied slowly. The mixture is cooled to 95°C in 27 minutes and is maintained at approximately 95-100°C for the duration of the reaction. The mixture is poured out at 60 minutes. Analysis by GC indicated less than 1% residual

N-methylglucamine. EXAMPLE HI 100 lb. H-PKO Glucose Amide To a 72 L three-necked round-bottomed flask equipped with an internal thermometer, vacuum line, nitrogen line (to break vacuum) and mechanical agitator, is added hardened palm kernel oil (15.357 kg, 21.804 mol) and Neodol 25-12 (6.803 kg). Once addition is complete, the mixture is heated to 50°C and dried under vacuum. To the dried mixture, with mixing, is added powdered N-methylglucamine (11.067 kg, 56.69 mol) and then sodium propylene glycolate (1.111 kg, 2.8345 mol) and the mixture is heated to 70-80°C and placed under vacuum (approximately 5" Hg). The mixture becomes homogeneous in 1 hour. After 3 hours, the mixture is poured out. Analysis by GC indicates less than 1% residual N-methylglucamine.

EXAMPLE IV H-PKO Glucose Amide Low Temperature Slurry To a 500 ml three-necked round-bottomed flask equipped with an internal thermometer, vacuum line, nitrogen line (to break vacuum) and mechanical agitator is added hardened palm kernel oil (126.60 g, 0.17973 mol) and Neodol 11-9 (51.14 g). Once addition is complete, the mixture is heated to 100°C and dried under vacuum. The dried mixture is cooled to 50-60°C and to the mixture is added sodium methoxide (1.38 g, 0.02561 mol) as a 25 wt. % solution in methanol. The mixture is heated to 90-95°C and the methanol removed under vacuum. To the methanol stripped mixture, at 90-95°C, is added powdered N-methylglucamine (100.00 g, 0.51224 mol) and vacuum applied. The mixture becomes homogeneous in 1 hour. After 4 hours, the mixture is poured out. Analysis is done by GC.

EXAMPLE V H-PKO Glucose Amide Melt Reaction with Propylene Glycol

To a 500 ml three-necked round-bottomed flask equipped with an internal thermometer, vacuum line, nitrogen line and mechanical stirrer is added powdered N- methylglucamine (127.45 g, 0.67285 mol). The N-methylglucamine (NMG) is melted at 130-140°C and dried under vacuum. To a separate 500 ml round- bottomed flask equipped with internal thermometer and vacuum line is added hardened palm kernel oil (156.41 g, 0.22206 mol). The hardened palm kernel oil is heated to 130-140°C and dried under vacuum. To the dried N-methylglucamine, with mixing, is added the dried hardened palm kernel oil and propylene glycol (31.54 g). To this mixture, at 120 C, is added sodium methoxide (1.76 g, 0.03264 mol) as a 25 wt. % solution in methanol and vacuum (15" Hg) applied immediately to remove methanol. The mixture becomes homogeneous in 1.5 minutes at which time cooling is applied. The mixture is cooled to 90°C in 7 minutes and is maintained at approximately 90°C for the duration of the reaction. The mixture is poured out at 85 minutes and analysis is done by GC.

It has been observed that by applying a vacuum after the HPKO is added to the NMG, the amount of water in the system can be further decreased. (The NMG has a tendency not to want to give up water.) By decreasing the last 1-5% of water in the total reaction mixture down to the bare minimum (less than about 0.1%) fatty acid formation is substantially minimized (1% or less, typically less than about 0.5% fatty acid) and the effectiveness of the catalyst is substantially increased.

Claims

WHAT IS CLAIMED IS:

1. A method for preparing a polyhydroxy fatty acid amide surfactant reaction product by reacting a fatty acid ester with an N-alkyl, N-alkoxy or N- aryloxy polyhydroxy amine, characterized in that it comprises conducting the reaction using a fatty acid triglyceride as the fatty acid ester, and conducting the reaction in the absence of a monohydric alcohol solvent, whereby the fatty acid content of the reaction product is minimized.

2. A method according to Claim 1 which is conducted in the presence of less than 0.1% by weight of water.

3. A method according to Claim 1 wherein the improvement additionally comprises conducting the reaction in the presence of an alkoxide catalyst selected from the alkali metal salts of a polyhydroxy alcohol.

4. A method according to Claim 2 wherein the alkoxide catalyst is selected from the alkali metal salts of ethylene glycol, propylene glycol and glycerol.

5. A method according to Claim 1 wherein the reaction is carried out in the presence of an alkoxylated alcohol or ethoxylated alkyl phenol.

6. A method according to Claim 1 wherein the fatty acid content of the reaction product is less than 1%, by weight.

7. A method according to Claim 2 wherein the fatty acid content of the reaction product is less than 1%, by weight.

8. A method according to Claim 1 wherein the polyhydroxy amine and fatty acid content of the reaction product are each less than 1%, by weight.