LOW FOAMING DETERGENT COMPOSITION

Abstract: Detergent compositions are provided which have a beneficial combination of low foaming and good wetting characteristics and which comprise a combination of certain selected glycoside surfactants in a specified range of proportions with certain conventional low foaming alkoxylated nonionic surfactant materials.

Description: LOW FOAMING DETERGENT COMPOSITION BACKGROUND OF THE INVENTION The present invention pertains generally to low foaming detergent compositions which are particularly well suited for automatic dishwashing, metal degreasing and hard surface cleaning applications and the like. More specifically, said invention pertains to compositions of the sort indicated wherein the surfactant component employed is a combination of a conventional low foaming alkoxylated nonionic surfactant with certain selected alkyl glycoside surfactants. Alkyl glycoside materials such as, for example, higher alkyl monoglycosides, higher alkyl polyglycosides and mixtures thereof are known materials; are known, at least in certain circumstances, to function as nonionic surfactants; and have been suggested as being suitable for use in certain specially formulated detergent 'compositions. See in ' this regard, for example, U.S. Patent 3,219,656 to Boettner, U.S. Patent " 3,547,828 to Mansfield et al., U.S. Patent 3,839,318 to Mansfield, U.S. Patent 3,721,633 to Ranauto, U.S. Patents 3,598,865 and 3,707,535 to Lew, U.S. Patent 4,014,808 to Herpers et al., U.S. Patent 4,147,652 to Kaniecki, U.S. Patent 4, 154, 706. to Kenkare et al., U.S. Patent 4,230,592 to Miller et al. and U.S. Patent 4,240,921 to Kaniecki. See also U.S. Patent 4,483,779 to Llenado et al. and U.S. Patent No. 4,483,780 to Llenado which disclose certain formulated laundry detergent compositions containing mixtures of certain conventional ethoxylated nonionic deterπents with alkylpolysaccharide surfactants having an average saccharide repeat unit content of 1.5 and above. In certain specialized cleaning applications such as, for example, automatic dishwashing formulations, hard surface cleaning applications, metal degreasing compositions and the like, it is common practice (and, indeed, is oftentimes mandatory from a practical standpoint) to employ surfactants which produce very low foam levels under the conditions encountered in the intended end-use application . Unfortunately, however, the indicated low foaming surfactant materials are typically characterized as also having relatively poor wetting characteristics under the indicated end-use conditions and this latter feature necessarily places practical limits on such surfactants' ability to facilitate, or effectively participate in, the actual cleaning task of concern . In view of the foregoing, it would be highly desirable to provide a means for obtaining low foaming detergent compositions having improved or enhanced wetting characteristics. SUMMARY OF THE I NVENTION It has now been discovered that the wetting characteristics of conventional low foaming alkoxylated nonionic surfactant-containing detergent compositions can be significantly and substantially improved without unacceptably increasing the foaming characteristics thereof by incorporating therein certain carefully selected glycoside surfactants in a particular range of glycoside surfactant to alkoxylated surfactant ratios or proportions . Accordingly, the present invention in one of its main aspects is a detergent composition which comprises a low foaming alkoxylated nonionic surfactant and a glycoside surfactant having an hydrophilic/lipophilic balance (HLB) of from about 6 to about 13.5 and wherein the weight ratio of said glycoside surfactant to said low foaming alkoxylated nonionic surfactant is from about 1 :20 to about 4: 1 with the proviso that when the glycoside surfactant has an HLB of greater than 12, the weight ratio of said glycoside surfactant to said low foaming alkoxylated nonionic surfactant is 1 : 1 or less (preferably 0.5 : 1 or less) . As a general rule, the indicated detergent compositions will have a cloud point of less than 60°C . Especially preferred compositions hereof will have a cloud point of less than 50°C and most preferably less than 40° C . As used herein , the term "low foaming" means and mandates that the su rfactant ingredient or detergent composition to which said term refers exhibits a high shear foam height of less than 1 .5 centimeter when tested at 55°C using a single speed Waring Blender equipped with a jacketed cylindrical container. DETAI LED DESCRI PTION OF THE INVENTION Glycoside surfactants suitable for use in the practice of the present invention include, so long as the herein discussed HLB and glycoside surfactant to low foaming alkoxylated nonionic surfactant weight ratio requirements are satisfied, those of the formula: RO(R'O) (Z) v A y * ■ wherein R is a monovalent organic radical (e. g. , a monovalent saturated aliphatic, unsaturated aliphatic or aromatic radical such as alkyl, hydroxyalkyl, alkenyl, hydroxyalkenyl, aryl, alkylaryl, hydroxyal ylaryl, arylalkyl, alkenylaryl, arylalkenyl, etc. ) containing from about 6 to about 30 (preferably from about 8 to about 16, more preferably from about 12 to about 16 and most preferably from 12 to 14) carbon atoms; R' is a divalent hydrocarbon radical containing from 2 to about 4 carbon atoms such as ethylene, propylene or butylene (most preferably the unit (R'O) represents repeating units of ethylene oxide, propylene oxide and/or random or block combinations thereof) ; y is a number having an average value of from 0 to about 12; Z represents a moiety derived from a reducing saccharide containing 5 or 6 carbon atoms (most preferably a glucose unit) ; and x is a number having an average value of from 1 to about 3 (preferably from 1 to about 2, and more preferably from 1 to less than 1 .5 and most preferably from 1 to about 1 .4) . Glycoside surfactants of the sort mentioned above, and various subgenera thereof, are described in U . S. Patent 4,565,647 to Llenado (issued January 21 , 1986) the discussion and description of which is hereby incorporated by reference. Glycoside surfactants suitable for use herein also include those of the Formula A above in which one or more of the normally free (i . e. , un reacted) hydroxyl groups of the saccharide moiety, Z, have been alkoxylated (preferably, ethoxylated or propoxylated) so as to attach one or more pendant alkoxy or poly (alkoxy) groups in place thereof . I n such event, the amount of alkylene oxide (e. g . , ethylene oxide, propylene oxide, etc. ) employed will typically range from about 1 to about 20 (preferably from about 3 to about 10) moles thereof per mol of saccharide moiety within the Formula A glycoside material . Examples of the indicated alkoxylated glycoside materials, and of methodology suitable for the preparation of same, are described in Published PCT Application Serial Number WO86/04899, published August 28, 1986. Glycoside surfactants especially preferred- for use herein include those of the Formula A above wherein R is an alkyl group containing from about 8 to about 18 (especially from about 10 to about 16 and most preferably from 10 to 14) carbon atoms ; y is zero; Z is glucose or a moiety derived therefrom; and x has an average value of from 1 to about 2 (more preferably from 1 to less than 1 .5 and especially from 1 to about 1 .4) . As has been noted above, glycoside surfactants suitable for use herein must have an HLB of from about 6 to about 13.5 with the proviso that when said glycoside surfactant has an HLB in excess of 12 (e. g . , as in the case where, in the formula A above, the R group is less than C. o, Y > s zero, Z is glucose and x is 2 or greater or in the case where x is 1 .5 or greater, R is about 10 or less and y is zero and Z is glucose) then the glycoside su rfactant to low foaming alkoxylated nonionic surfactant weight ratio employed in the detergent composition of concern must be about 1 : 1 or less and is preferably about 0.5: 1 or less . In certain especially preferred embodiments hereof, the glycoside surfactant to low foaming alkoxylated nonionic surfactant weight ratio employed is also confined to the indicated restricted ratio ranges (i.e. from about 1 :20 to about 1 : 1 , preferably from 1 :20 to about 0.5: 1 ) in those instances wherein the HLB of the glycoside surfactant employed is in exces of 10.5. The preferred glycoside surfactants for use herein are those having an HLB of from about 8 to about 12 and most preferably such glycoside surfactant ingredient has an HLB of from about 8 to about 10.5. As a general rule, glycoside surfactants derived from fatty alcohols havfng from 8 to 14 carbon atom must have a degree of polymerization (D. P. or "x" in the Formula A above) of less than 1 .5 in order to have an HLB in the specified most preferred 8 to about 10.5 range. Alkoxylated nonionic surfactants to which the present invention is applicable include any ethoxylated or ethoxyla ted/propoxylated nonionic surfactant which when used at a temperature above its cloud point is "low foaming" in character and which has relatively poor wetting characteristic as evidenced, for example, by said surfactant exhibiting a Draves Wetting Time (at a temperature above its cloud point) of 2 minutes or greater. Illustrative of such low foaming/poor wetting alkoxylated nonionic surfactant materials are those which are either block or random co-condensates of ethylene oxide and propylene oxide with each other and with or without a relatively long chain (e. g . , from about C fi to about C-^) monohydric -alcohol residue. Generally speaking, said co-condensate materials can be represented by the structural formula: R"O(EO) n (PO) m H wherein R"-O is either the residue of a C fi to C ^ n monohydric alcohol or a propylene glycol-propylene oxide condensation product of the formula: OH CH--C-C-O(PO) H 3 H a wherein "a" has a value of from about 1 to about 15 and (preferably from about 2 to about 10) and wherein PO represents a propylene oxide repeat unit, EO represents an ethylene oxide repeat unit, n has an average value of from about 1 to about 40 (preferably from about 3 to about 15) and m has an average value of from about 1 to about 15 (preferably from about 2 to about 10). Typically, the low foaming alkoxylated nonionic surfactants to which the present invention is applicable will have a cloud point of about 35°C or less and an HLB of about 10 or less. As has been previously noted, the indicated glycoside surfactant and low foaming alkoxylated nonionic surfactant ingredients are as a general proposition employed in a weight ratio of the former to the latter ranging from about 1:20 (i.e., 0.05:1) to about 4:1 with the proviso that said ratio must be no greater than 1:1 (preferably no greater than 0.5:1) when the HLB of the glycoside surfactant ingredient is greater than 12. Preferably, the indicated glycoside surfactant: low foaming alkoxylated nonionic surfactant weight ratio is maintained within a range of from about 1:10 (i.e., 0.1:1) to about 2:1 (most preferably from about 1:10 to about 1:1) with these latter preferred ratio ranges being subject to the same proviso as has been previously stated . As a result of operating within the boundaries set forth above (i . e. , concerning the use of the specified surfactant ingredients and the specified relative proportions of said surfactant ingredients to each other) , there are provided detergent compositions which, when used at temperatures in excess of their cloud points, have a beneficial combination of at most a moderate foaming propensity along with good wetting characteristics . Indeed, there can be obtained in accordance the present invention detergent compositions which are of a "low foaming" character (as such term as defined herein above) but wtiich nonetheless still exhibit Draves Wetting Times of 1.5 minute or less and which in many instances exhibit Draves Wetting Times of less than 1 minute. From a practical perspective, the low foaming detergent compositions hereof may suitably take the form o substantially dry powders, granules, etc. or may, if desired, take the form of aqueous liquid formulations . In their dry powdered or granular form, said compositions can, if desired, be composed solely of (or consist essentially of) the above-described combination of the essential surfactant ingredients . More typically, however, said substantially dry compositions will contain additional commonly used ingredients such as organic and/or inorganic builder ingredients, water soluble filler salts (e.g. , alkali metal, ammonium or substituted chlorides, fluorides, sulfates, etc. ) , anti-caking agents, alkaline materials such as alkali metal and alkaline earth metal hydroxides, alkaline silicates and the like in addition to the above-described essential surfactant combination. Care must be taken, however, to avoid the inclusion within said compositions of any ingredients (e.g., high foaming cosurfactant ingredients, etc.) which would destroy the requisite low foaming characteristics of the subject detergent compositions. In one preferred embodiment hereof, a substantially dry powdered or granular detergent formulation is provided which typically comprises, on a total composition weight basis: (a) from about 0.5 to about 20 (preferably from 0.5 to about 10) weight percent of the above-described glycoside surfactant/low foaming alkoxylated nonionic surfactant combination; (b) from about 5 to about 95 (preferably from about 15 to about 75) weight percent of an organic or inorganic builder ingredient; (c) from about 0 to about 30 (preferably from about 0 to about 20) weight percent of a water soluble alkaline or neutral f-^ler (i.e., noπ-builder/non-sequestrant) salt ingredient; and (d) from 0 up to about 30 (preferably from 0 to about 20) weight percent water. In their aqueous liquid formulation form, the detergent compositions hereof can, if desired, consist essentially of an aqueous solution of the above-described essential surfactant combination, for example, in the form of an aqueous solution containing, on a total solution weight basis, from about 0.5 to about 20 (preferably from about 0.5 to about 10) weight percent of the indicated glycoside surfactant/low foaming alkoxylated nonionic surfactant combination with the balance of said composition being compossd solely of water. More typically, however, said liquid formulationsr will generally further contain one or more of the usually employed auxiliary detergent formulation ingredients such as, for example, solvents, thickeners, weighting agents, hydrotropes, builders, abrasive agents, dyes, soil suspending agents, alkaline materials, and the like. Here again, however, care must be exercized to avoid the inclusion of ingredients such as high foaming cosurfactants of a type (or in an amount) which would serve to destroy the requisite low foaming character of the desired detergent compositions . I n a representative example, the liquid detergent formulations hereof will oftentimes comprise, on a total composition weight basis, (a) from about 0.5 to about 20 (preferably from about 0.5 to about 10) weight percent of the above-described glycoside surfactant/low foaming alkoxylated nonionic surfactant combination; (b) from about 10 to about 60 (preferably from about 20 to about 50) weight percent of an inorganic or organic builder ingredient; (c) from about 30 to about 90 (preferably from about 50 to about 70) weight percent water; (d) from 0 to about 20 weight percent of an organic or inorganic thickener ingredient; and (e) up to about 3 to 5 weight percent each of one or more of the aforementioned conventional auxiliary detergent formulation ingredients . Water soluble detergent builders suitable for use herein include the various water soluble alkali metal , ammonium or substituted ammonium phosphates, polyphosphates, phosphonates, polyphosphonates, carbonates, silicates, borates, polyhydroxysulfonates, polyacetates, carboxylates, and polycarboxylates . Preferred are the alkali metal , especially sodium, salts of the above. Specific examples of suitable water soluble inorganic phosphate builders are sodium and potassium tripolyphosphate, pyrophosphate, polymeric metaphosphates having a degree of polymerization of from about 6 to 21 , and orthophosphate. Examples of polyphosphonate builders are the sodium and potassium salts, of ethylene-1 , 1 -diphosphonic acid, the sodium and potassium salts of ethane-1 , l ,2-triphosphonic acid . Examples of suitable water soluble nonphosphorus, inorganic builders for use herein include sodium and potassium carbonate, bicarbonate, sesquicarbonate, tetraborate decahydrate, and silicate having a molar ratio of SiO~ to alkai metal oxide of from about 0.5 to about 4.0, preferably from about 1 .0 to about 2.4. Water soluble, nonphosphorus organic builders useful herein also include the various alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates and polyhydroxysulfonates . Examples of pol.yacetate and polycarboxylate builders are the sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediamine tetraacetic acid, nitrilotriacetic acid, oxydissuccinic acid, mellitic acid, benzene polycarboxylic acids, and citric acid . Water miscible organic solvents suitable for use in the compositions of the present invention include alkylene glycols and/or ethers thereof such as, for example, ethylene gfycol mono-n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-hexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, isopropyleπe glycol monoethyl or monopropyl or monobutyl ether, etc. ; polyalkylene glycols and/or ethers thereof such as, for example, diethylene glycol monoethyl or monopropyl or monobutyl ether, di- or tripropylene glycol monomethyl ether, di- or tripropylene glycol monoethyl ether, etc. ; t-butyl alcohol; tetra-hydrofurfuryl alcohol; N-methyl-2-pyrrolidone; and the like. As has been noted above, the detergent composition can, if desired in a given instance, optionally include one or more of the various known types of supplemental ingredients or additives such as, for example, hydrotropes (e. g . , water soluble salts of low molecular weight organic acids such as the sodium or potassium salts of toluene-, benzene-, or cumene sulfonic acid, sodium or potassium sulfosuccinate, etc. ) ; perfumes, dyes or colorants; thickeners and/or soil suspending agents (e. g carboxymethyl cellulose, sodium polyacrylate, polyethylene glycols having molecular weights of from about 400 to about 100,000) ; deodorizers; ammonia; germicides; antioxidants; and the like. Preparation of the detergent compositions hereof can be accomplished in any convenient conventional fashion . For example, in the case of substantially dry powdered or granular formulations, the ingredients can be obtained in (or, if obtained in aqueous solution or dispersion form, can be converted to) dry powdered or granular form and can simply be admixed together in the desi red proportion and dry blended or milled to form an intimate substantially homogeneous mixture thereof . Alternatively, said ingredients can be initially combined to form an aqueous solution or suspension (e. g . , a crutcher slurry) thereof; intimately admixed in that form; and be subsequently dried (e. g . , as a solid cake and ground, via a spray drying operation etc. ) to form the desi red substantially dry granular or powdered product. I n the preparation of liquid formulations in accordance with the present invention , there is no criticality associated with the order of ingredient addition or the technique employed in manufactu ring or formulating same and such can therefore be accomplished in any fashion that may be convenient or expedient under the circumstances to provide the subject composition of interest in the form of a stable, homogeneous aqueous solution thereof. As a general rule, however, it will typically be convenient to first admix the water and any other liquid ingredients to be employed together and to thereafter add thereto (and dissolve therein) the remainder of the ingredients to be employed within the subject liquid detergent composition . As has been noted above, the detergent compositions hereof are, by vi rtue of thei r unique combination of low foaming and good wetting characteristics, are especially well suited for use in automatic dishwashing, hard surface cleaning and metal degreasing applications . The present invention is further illustrated and understood by reference to the following examples thereof. Examples 1 - 6 I n these examples , a series of formulations are prepared containing a 1 : 1 weight ratio mixtu re of one of th ree different glycoside surfactants with TM PLURAFAC RA40 which is an ethoxylated/propoxylated primary fatty alcohol product commercially available from BASF and which is known to be a relatively low foaming/poor wetting surfactant when used above its cloud point of about 26°C . The resulting formulations are then evaluated to determine their respective wetting characteristics via Draves Wetting Time testing at 60°C . The results of such evaluations are summarized in Table A below. Also included in Table A are the Draves Wetting Time results for the individual glycoside TM surfactants and for the PLURAFAC RA40 product. TABLE A EXAMPLE SURFACTANT INGREDIENT NUMBER AND AMOUNT ( T. % IN SOLUTION) GLYCOSIDE AMOUNT OF DRAVES WETTING TIME GLYCOSIDE AMOUNT PLURAFAC RA40 (MINUTES) Control Example lΛ 0.1 None 0.340* Example pl2pl.4 0.1 0.1 0.370* 0.05 0.05 0.573* Control irjΞxample 1.4 0.1 None 0.117* 0.1 0.1 0.263** Example 0.05 0.05 1.402* Control Example plθ.4 0.1 None 0.769* 65*** Example z 0.1 0.1 1.3 0.05 0.05 1.520* Control R u otne lΛ ' None 0.1 5.480** *Average of 3 separate tests. •5**Average 0 f 4 separate tests. *** Average of 6 separate tests. Dodecyl glucoside having average D.P. of about 1.4. HLB _1 - = 10 r lz r l lθ . Decyl glucoside having average D.P. of about 1.4. HLB = 11.7. C 14 G 1.4 Tetradecyl glucoside having average D.P. of about 1.4. HLB = 0 1- HLB determined according to J. T. Davies, Prbc. Intern. Congr. Surface Activity, 2nd London, 1957, I, 426 (1957). 5 0 As can be seen from the results in Table A the combined giycoside/PLURAFAC RA40 compositions exhibit notably better wetting characteristics than that of the PLURAFAC RA40 product alone. EXAMPLES 7 - 14 i n these examples, a series of detergent compositions containing a mixture of one of several different glycoside surfactants and PLURAFAC RA40 are prepared and subjected to high shear foam height testing. The foam height testing is conducted at 55°C and at a dilution of 3 grams of the detergent composition per liter of wash solution in artificially hardened water (150 ppm as calcium carbonate; Ca :Mg = 2) and both with and without egg yolk addition as a food soil simulation using a single speed Waring Blender unit equipped with a jacketed cylindrical container. The results of such foam height testing are summarized in Table B below. TABLE B FOAM HEIGHT (cm) AMOUNT OF EGG YOLK EXAMPLE SURFACTANT 1,3 SOLUTION ADDED (ml) NUMBER SYSTEM NONE 4ml 5 7 2%RA40/1 C 1Q G 1 4 0.6 1.1 8 2%RA40/1%C 12 G 1 4 0.5 1.1 9 2%RA40/1%C 12 G 1 4 0.4 1.0 Control 5 2%RA40 only 0.2 1.2 10Coπtrol 6 None 0 0.8 10 4%C 1Q G 1 4 /2%RA40 1.2 2.8 11 4%C 12 G 1 4 /2%RA40 1.0 2.0 12 2 RA40/2%C 1( -G 1 4 0.8 1.4 15 13 2%RA40/2%C 1£ G 1 4 0.6 1.9 14 2%RA40/2%C 1 .G 1 . 0.9 0.8 1 . Built with 20% sodium carbonate, 30% sodium tripolyphosphate and 20% sodium silicate. 20 2- Egg yolk solution is 8: 2 weight ratio of egg yolk to deionized water. 3. Surfactants are as identified in Table A of Examples 25 1 -6. 30 As can be seen from the results in Table B, lower foam heights are generally obtained when the- glycoside surfactant to PLURAFAC RA40 ratio is 1 : 1 or less as opposed when said ratio is greater than 1 : 1 . While the subject matter hereof has been described and illustrated by reference to certain specific examples and embodiments thereof, such is not to be interpreted as in any way limiting the scope of the instantly claimed invention .

Claims: What is Claimed is: 1. A low foaming detergent composition which comprises a low foaming alkoxylated nonionic surfactant and a glycoside surfactant having a hydrophilic/ lipophilic balance (HLB) of from about 6 to about 13.5 and wherein the weight ratio of said glycoside surfactant to said low foaming alkoxylated nonionic surfactant is from about 1:20 to about 4:1 with the proviso that when the glycoside surfactant has an HLB of greater than 12, the weight ratio of said glycoside surfactant to said low foaming alkoxylated nonionic surfactant is 1:1 or less. 2. The composition of Claim 1 wherein the glycoside surfactant has an HLB of from about 8 to about 12. 3. The composition of Claim 1 wherein the glycoside surfactant has- an HLB of from about 8 to about 10.5. 4. The composition of Claim 1 wherein the weight ratio of the glycoside surfactant to the low foaming alkoxylated nonionic surfactant is from about 1:20 to about 1:1. 5. The composition of Claim 1 wherein the weight ratio of the glycoside surfactant to the low foaming alkoxylated nonionic surfactant is from about 1:20 to about 0.5:1. 6. The composition of Claim 1 wherein the weight ratio of the glycoside surfactant to the low foaming alkoxylated nonionic surfactant is from about 1:10 to about 1:1. 7. The composition of Claim 1 wherein the glycoside surfactant corresponds to the formula: RO(R'O) (Z) A y x wherein R is a monovalent organic radical containing from about 6 to about 30 carbon atoms; R' is a divalent hydrocarbon radical containing from 2 to about 4 carbon atoms; y is a number having an average value of from 0 to about 12; Z represents a moiety derived from a reducing saccharide containing 5 or 6 carbon atoms; and x is a number having an average value of from 1 to about 3. 8. The composition of Claim 7 wherein , in the glycoside surfactant of the formula A, R is an alkyl group containing from about 8 to about 16 carbon atoms, y is zero, and x has an average value of from 1 to less than 1 .5. 9. The composition of Claim 8 wherein x has an average value of from 1 to about 1 .4. 10. The composition of Claim 9 wherein R is an alkyl group containing from about 8 to about 14 carbon atoms . - 11 . The composition of Claim 1 wherein the low foaming alkoxylated surfactant has a cloud point of about 35°C or less . 12. The composition of Claim 11 wherein the low foaming alkoxylated surfactant has an HLB of about 10 or less . 13. The composition of Claim 1 wherein the cloud point of said composition is less than 60°C. 14. The composition of Claim 1 wherein the cloud point thereof is less than 50°C. 15. The composition of " Claim 1 wherein the cloud point thereof is less than 40°C.

Inventors: GESSFORD MARY K, HILL RANDAL M, SWARTZLANDER MICHAEL W, GESSFORD, MARY, K., HILL, RANDAL, M., SWARTZLANDER, MICHAEL, W.
Applicants: STALEY CONTINENTAL INC, STALEY CONTINENTAL, INC.
Application year: 1988
Main classification: C11D17
IPC codes: C11D1, C11D17, C23G1