Patent Description:
Anionic surfactants are excellent in detergency and foamability, and are widely used as a component of detergents. One known anionic surfactant is an internal olefin sulfonate obtained from, as a raw material, an internal olefin having a double bond not at an end of an olefin chain, but in an internal part thereof. Such an internal olefin sulfonate is obtained by, for example, reacting an internal olefin with a gaseous sulfur trioxide-containing gas to sulfonate the internal olefin, and neutralizing and then further hydrolyzing the resulting sulfonic acid. Such an internal olefin sulfonate is known to be favorable in biodegradability.

Use of an internal olefin sulfonate for washing an article such as tableware has been conventionally proposed.

<CIT> describes a detergent composition comprising an internal olefin sulfonate salt, having from <NUM> to <NUM> carbon atoms, wherein at least <NUM> percent by weight is in the beta-hydroxy alkane sulfonate form.

<CIT> describes a biofilm-removing composition for a hard surface, the composition containing <NUM>% by mass or more and <NUM>% by mass or less of an internal olefin sulfonate.

<CIT> describes a tableware-washing detergent composition for hand-washing, the composition containing: (a) an internal olefin sulfonate having <NUM> or more and <NUM> or less carbons; (b) a fatty acid having <NUM> or more and <NUM> or less carbons, or salt thereof; (c) one or more compounds selected from a specified alkanolamide (c1), specified fatty acid amide propyl betaine (c2) and specified polyoxyethylene alkyl or alkenyl amine (c3); in respective predetermined conditions, in which the mass ratio (c)/(a) is <NUM> or more and <NUM> or less.

<CIT> describes a tableware-washing detergent composition for hand-washing, the composition containing: (a) an internal olefin sulfonate having <NUM> or more and <NUM> or less carbons; (b) a fatty acid having <NUM> or more and <NUM> or less carbons, or a salt thereof; (c) an amine oxide having a hydrocarbon group with <NUM> or more and <NUM> or less carbons; and (d) a compound selected from an alkylsuccinic acid having an alkyl group with <NUM> or more and <NUM> or less carbons, an alkenylsuccinic acid having an alkenyl group with <NUM> or more and <NUM> or less carbons, and salts and anhydrides thereof; in respective predetermined conditions, in which the mass ratio (d)/(a) is <NUM> or more and <NUM> or less.

<CIT> and <CIT> describe detergent compositions containing a mixture of vinyl, vinylidene and internal olefin sulfonates. The examples in these documents use mixtures of C12, C14 and C16 olefin sulfonates.

There are needs for a further enhancement in detergency and excellent rinsability in washing of a hard article such as tableware with an internal olefin sulfonate.

The present invention provides a method for washing a hard article with an internal olefin sulfonate, the washing method providing excellent detergency and rinsability.

The present invention relates to a method for washing a hard article, the method including: the contact step of bringing a detergent liquid obtained by mixing (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more as determined below, into contact with the hard article, and the step of rinsing the hard article after the contact step with water having a hardness of <NUM>° DH or more as determined below, wherein.

The present invention also relates to a detergent composition for a hard article, wherein (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more as determined below are formulated,.

Subject to the appended claims, the present invention encompasses a method for washing a tableware, the method including: the contact step of bringing a detergent liquid obtained by mixing (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more as determined below, into contact with the tableware, and the step of rinsing the tableware after the contact step with water having a hardness of <NUM>° DH or more as determined below, wherein
the detergent liquid at <NUM> or more is brought into contact with the tableware in at least a part of the contact step.

The present invention also encompasses the use, as a detergent for a hard article, such as tableware, a composition wherein (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more as determined below are formulated,.

Hereinafter, the description will be made with (a) a potassium internal olefin sulfonate, as component (a) and (b) water having a hardness of <NUM>° DH or more as determined below, as component (b).

The present invention provides a method for washing a hard article such as tableware with an internal olefin sulfonate, the washing method providing excellent detergency and rinsability. The rinsability is usually determined by the degree of defoaming in rinsing.

It has been found in the present invention that detergency and rinsability are remarkably enhanced by using a potassium ion as a counter ion of an internal olefin sulfonic acid in washing of a hard article such as tableware with an internal olefin sulfonate, and specifying the hardness and the temperature of water for use in washing in detail.

The potassium internal olefin sulfonate (hereinafter, sometimes referred to as "IOS-K") as component (a) in the present invention is a compound obtained by, for example, subjecting an internal olefin as a raw material to sulfonation, neutralization, and hydrolysis. The internal olefin herein is widely meant to also encompass those containing a trace of so-called α-olefin, in which a double bond is present at position <NUM> of a carbon chain. Such an internal olefin is sulfonated to thereby quantitatively generate β-sultone, such β-sultone is partially changed to γ-sultone and an olefin sulfonic acid, and such resultants are then further converted to hydroxyalkanesulfonate and olefin sulfonate in a neutralization/hydrolysis step (for example, <NPL>)). The hydroxyalkanesulfonate here obtained has a hydroxy group in an internal part of an alkane chain, and the olefin sulfonate has a double bond in an internal part of an olefin chain. The resulting product is mainly a mixture thereof, and may also partially contain a trace of a hydroxyalkanesulfonate having a hydroxy group at an end of a carbon chain, or a trace of an olefin sulfonate having a double bond at an end of a carbon chain. Such a product may also contain a trace of an olefin sulfonate in which the sulfonic acid group is present at position <NUM> of a carbon chain. Herein, each of these products and a mixture thereof are collectively referred to as "internal olefin sulfonate. " The hydroxyalkanesulfonate is referred to as a hydroxy form of the internal olefin sulfonate, and the olefin sulfonate is referred to as an olefin form of the internal olefin sulfonate. Among such internal olefin sulfonates, a potassium internal olefin sulfonate is component (a) in the present invention.

In the present invention, the ratio of IOS-K having the sulfonic acid group at position <NUM> in component (a) is preferably <NUM>% by mass or more, more preferably <NUM>% by mass or more, and preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, in view of detergency. The content of IOS-K having the sulfonic acid group at position <NUM> in component (a) can be measured by a procedure such as a gas chromatography or a nuclear magnetic resonance spectrum.

In the present invention, the amount of IOS-K having the sulfonic acid group at position <NUM> of a carbon chain in component (a) is preferably small. In the present invention, the content of IOS-K having the sulfonic acid group at position <NUM> of a carbon chain (hereinafter, referred to as "component (a')") in component (a) is preferably <NUM>% by mass or less. In the present invention, the content of component (a') in component (a) is preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, further preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass or less, in view of detergency and rinsability. The content of component (a') in component (a) can be <NUM>% by mass or more, and may also be <NUM>% by mass.

Component (a') may also be IOS-K having <NUM> or more and <NUM> or less carbons. Examples of the hydrocarbon group of component (a) and component (a') include an alkyl group and an alkenyl group, and a hydroxy group may be contained therein.

IOS-K having the sulfonic acid group at position <NUM> of a carbon chain, as component (a'), the content of which is desirably limited in the present invention, is a compound schematically represented by the following formula. Other compound as component (a) can be expressed as a compound in which the sulfonic acid group is bound to a carbon atom at a position other than position <NUM> of a carbon chain in the following formula. In the following formula, "-SO<NUM>K" is a sulfonic acid group in the form of a potassium salt.

<CHM>
wherein R<NUM> represents an alkyl group, and m is an integer of <NUM> or more, preferably <NUM> or more.

Component (a) preferably has <NUM> or more and <NUM> or less carbons, more preferably <NUM> or more carbons, more preferably <NUM> or more carbons, and preferably <NUM> or less carbons, more preferably <NUM> or less carbons, more preferably <NUM> or less carbons, in view of detergency and rinsability, provided that the ratio of the total of potassium internal olefin sulfonate having <NUM> carbons (hereinafter "C<NUM>IOS-K") and potassium internal olefin sulfonate having <NUM> carbons (hereinafter "C<NUM>IOS-K") in component (a) is <NUM>% by mass or more and a mass ratio of C<NUM>IOS-K/C<NUM>IOS-K is <NUM> or less.

The detergent liquid for use in the present invention more preferably contains IOS-K having <NUM> carbons, as component (a).

The mass ratio of a potassium internal olefin sulfonate having <NUM> carbons (hereinafter, referred to as "C<NUM>IOS-K") and a potassium internal olefin sulfonate having <NUM> carbons (hereinafter, referred to as "C<NUM>IOS-K") in component (a), C<NUM>IOS-K/C<NUM>IOS-K, is preferably <NUM> or less, further preferably <NUM> or less, and preferably <NUM> or more, and may be <NUM>.

In the present invention, the ratio of the total of C<NUM>IOS-K and C<NUM>IOS-K in component (a) is preferably <NUM>% by mass or more, further preferably <NUM>% by mass or more, furthermore preferably <NUM>% by mass or more, furthermore preferably <NUM>% by mass or more, furthermore preferably <NUM>% by mass or more, and preferably <NUM>% by mass or less, and may also be <NUM>% by mass, in view of detergent properties and rinsability.

The detergent liquid for use in the present invention preferably contains component (a) in an amount of <NUM>% by mass or more, more preferably <NUM>% by mass or more, further preferably <NUM>% by mass or more, and preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, further preferably <NUM>% by mass or less.

A detergent liquid obtained by mixing component (a) and water having a hardness of <NUM>° DH or more as component (b) is used in the present invention, in view of detergency and rinsability. The hardness of component (b) is selected from <NUM>° DH or more, further <NUM>° DH or more, and further <NUM>° DH or more. The hardness of component (b) can also be selected from <NUM>° DH to <NUM>° DH or less, further from <NUM>° DH to <NUM>° DH or less, and further from <NUM>° DH to <NUM>° DH or less.

For the hardness of water (° DH) according to the present invention, the concentration expressed in terms of CaCO<NUM> (mg/L) is determined according to "Chelate Titration Method" in <NUM>. <NUM> described in "Total Hardness" in <NUM> of Chapter <NUM> in JIS K <NUM>:<NUM> "Testing Methods for Industrial Water", and this concentration is converted into the hardness of water by the following expression.

The detergent liquid for use in the present invention is obtained by mixing, relative to <NUM> part by mass of component (a), preferably <NUM> parts by mass or more, more preferably <NUM> parts by mass or more, and preferably <NUM>,<NUM> parts by mass or less, more preferably <NUM>,<NUM> parts by mass or less of component (b).

The ratio of component (b) to the total amount of water used for preparing the detergent liquid for use in the present invention can be preferably <NUM>% by mass or more, more preferably <NUM>% by mass or more, further preferably <NUM>% by mass or more and more preferably <NUM>% by mass or more, and <NUM>% by mass or less, and further less than <NUM>% by mass.

The detergent liquid for use in the present invention can contain any surfactant other than component (a), as long as the effect of the present invention is not impaired. Such a surfactant other than component (a) can be any of surfactants usually used in pharmaceutical products, quasi-pharmaceutical products, cosmetics, toiletry products, sundries, and the like, and specific examples include an anionic surfactant other than component (a), a nonionic surfactant, an amphoteric surfactant and a cationic surfactant.

The detergent liquid for use in the present invention preferably contains a compound selected from a magnesium-containing inorganic compound and an alkylenediamine compound (where the alkylene group has <NUM> to <NUM> carbons), preferably a magnesium-containing inorganic compound, in view of an enhancement in emulsification ability against greasy dirt and an increase in detergency. These compounds have a common effect/mechanism of relatively weakly interacting with at least two molecules of component (a) and any optional anionic surfactant to thereby form a complex to result in an enhancement in an effect necessary for the present invention, namely, surface activity such as an emulsification ability.

Examples of the magnesium-containing inorganic compound include magnesium muriate such as magnesium chloride, magnesium salts such as magnesium sulfate and magnesium nitrate, magnesium hydroxide, and magnesium oxide, and a compound selected from magnesium chloride and magnesium sulfate is more preferable and magnesium chloride is further preferable. The alkylenediamine compound is suitably ethylenediamine, propylenediamine, hexylenediamine or cyclohexanediamine, and more preferably cyclohexanediamine.

In the case where the detergent liquid for use in the present invention contains a compound selected from the magnesium-containing inorganic compound and the alkylenediamine compound, the content of the compound in the detergent liquid is preferably <NUM>% by mass or more, more preferably <NUM>% by mass or more, and preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less. The compound may contain crystal water in some cases, and the content here indicated means the mass from which the mass of such crystal water is excluded.

An inorganic compound other than the magnesium-containing inorganic compound may be used, as an aid, in combination with the compound selected from the magnesium-containing inorganic compound and the alkylenediamine compound (where the alkylene group has <NUM> to <NUM> carbons), in the detergent liquid for use in the present invention. Examples of the inorganic compound include sodium chloride, potassium chloride, sodium iodide, potassium iodide, sodium sulfate, potassium sulfate, and alum.

A behavior of foam in washing and in rinsing is very important in the present invention. A surfactant having the effect of increasing foam is used in combination with another surfactant in consideration of foamability/foam durability in washing, in a general research of a detergent composition for a hard article such as tableware. However, care needs to be taken when using such a surfactant having the effect of increasing foam, in the present invention because of having a large effect on defoamability in rinsing. In particular, a surfactant selected from a carbobetaine-type surfactant and an alkanolamide-type surfactant needs to be carefully handled in the present invention. The content of the surfactant selected from a carbobetaine-type surfactant and an alkanolamide-type surfactant in the detergent liquid for use in the present invention is preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, further preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass, namely, the surfactant is furthermore preferably not contained.

The detergent liquid for use in the present invention can contain, in addition to the above components, other component(s) for use as general raw materials for a detergent for a hard article, such as a viscosity reducer, a polyhydric alcohol, an organic solvent, a preservative, a reducing agent, an enzyme, and a perfume.

The detergent liquid for use in the present invention can be produced by mixing component (a) and component (b), and further, if necessary, an optional component. The detergent liquid may also be prepared by diluting a concentrated composition containing component (a) and water, with component (b). The water contained in the concentrated composition may have a hardness of less than <NUM>° DH. The concentrated composition may contain an optional component. The amount of the water contained in the concentrated composition is preferably within a range which does not have any effect on the effect exerted due to use of component (b). As one example, the detergent liquid for use in the present invention can be prepared by preparing a concentrated composition containing <NUM>% by mass or more and <NUM>% by mass or less of component (a) and water having a hardness of less than <NUM>° DH, and mixing <NUM> parts by mass or more and <NUM> parts by mass or less of component (b) relative to <NUM> part by mass of the concentrate composition. The washing method of the present invention may include such a step of preparing the detergent liquid, before the contact step.

The method for washing a hard article of the present invention is as defined in the claims and includes the contact step of bringing a detergent liquid obtained by mixing (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more, into contact with the hard article.

The detergent liquid at <NUM> or more is brought into contact with the hard article in at least a part of the contact step, (hereinafter, sometimes referred to as "high-temperature contact"), in the method for washing a hard article of the present invention. The temperature of the detergent liquid in the high-temperature contact is preferably <NUM> or more, more preferably <NUM> or more, further preferably <NUM> or more, and preferably <NUM> or less, more preferably <NUM> or less. The temperature of the detergent liquid in the high-temperature contact may be constant or varied as long as the temperature is <NUM> or more. In the present invention, the high-temperature contact is performed in at least a part of the contact step, thereby exhibiting excellent detergency and rinsability.

In the contact step in the present invention, the detergent liquid is brought into contact with a hard article for preferably <NUM> seconds or more, more preferably <NUM> minute or more, and preferably <NUM> hours or less, more preferably <NUM> hours or less, in view of detergency and rinsability.

In the high-temperature contact, the detergent liquid at <NUM> or more is brought into contact with a hard article for preferably <NUM> seconds or more, more preferably <NUM> minute or more, and preferably <NUM> hours or less, more preferably <NUM> hours or less, in view of detergency and rinsability.

In the present invention, the ratio of the period of the high-temperature contact to the total period of the contact step is preferably <NUM>% or more, more preferably <NUM>% or more, further preferably <NUM>% or more. The high-temperature contact may be performed throughout the contact step.

The temperature of the detergent liquid may be varied in the contact step encompassing the high-temperature contact. The variation in temperature of the detergent liquid in the contact step may be in various ways, for example, continuous or intermittent. The variation in temperature of the detergent liquid in the contact step may be any of temperature rise, temperature drop, and a combination thereof. In the present invention, the contact step is preferably initiated by bringing the detergent liquid at <NUM> or more into contact with a hard article. That is, the temperature of the detergent liquid to be first brought into contact with the hard article is preferably <NUM> or more.

In the present invention, the contact step is preferably performed by immersing a hard article in the detergent liquid. The high-temperature contact is also preferably performed by immersing the hard article in the detergent liquid at <NUM> or more.

The viscosity of the detergent liquid for use in the present invention is preferably <NUM> mPa·s or more, more preferably <NUM> mPa·s or more, and preferably <NUM>,<NUM> mPa·s or less, more preferably <NUM>,<NUM> mPa·s or less.

The pH pf the detergent liquid for use in the present invention, at a temperature in washing of a hard article, is preferably <NUM> or more, more preferably <NUM> or more, and preferably <NUM> or less, more preferably <NUM> or less.

The hard article after the contact step can be further washed by hand-washing with the detergent liquid in the present invention or other detergent liquid (hereinafter, collectively referred to as "detergent liquid for washing by hand-washing") in the method for washing a hard article of the present invention. In a specific example of such a method for washing by hand-washing, the hard article is washed by hand-washing with a flexible material to which the detergent liquid for washing by hand-washing is attached, followed by rinsing with water. For example, the hard article is washed by allowing a flexible material such as a sponge impregnated with water to retain the detergent liquid for washing by hand-washing, crumpling the sponge several times by hand for foaming, and scrubbing with the sponge.

The method for washing a hard article of the present invention includes the step of rinsing the hard article after the contact step with water having a hardness of <NUM>° DH or more (hereinafter, sometimes referred to as "rinsing step").

The hardness of the water for use in the rinsing step is selected from <NUM>° DH or more, further <NUM>° DH or more, and further <NUM>° DH or more. The hardness of the water for use in the rinsing step can also be selected from <NUM>° DH to <NUM>° DH or less, further from <NUM>° DH to <NUM>° DH or less, and further from <NUM>° DH to <NUM>° DH or less.

The temperature of the water for use in the rinsing step is preferably <NUM> or more, more preferably <NUM> or more, further preferably <NUM> or more, and preferably <NUM> or less, more preferably <NUM> or less.

Such rinsing is performed with the hard article after the contact step being in contact with water having the above hardness, preferably at the above temperature. Rinsing can be, for example, rinsing in standing water, rinsing under running water, or a combination thereof.

The washing method of the present invention is for a hard article. Examples of the material forming the hard article include a material selected from plastic, metal, ceramics, lacquer, wood and glass, and a combination thereof. The hard article suitably includes, as the material, a material selected form plastic and glass in view of remarkably exhibiting the effect of the present invention. The hard article more suitably includes, as the material, plastic in view of a further enhancement in detergency with hard water. Examples of the plastic include polyolefin such as polypropylene and polyethylene, polyester such as polymethacrylate, polycarbonate, ABS, polyethylene terephthalate and polybutylene terephthalate, a melamine resin, a phenol resin, and polyamide. The plastic can include polyolefin, in particular, polypropylene from the viewpoint that the effect of the present invention is remarkably exerted. The plastic may be in the form of a composite with other material, such as FRP. The hard article is preferably glass in view of a further enhancement in detergency at high temperatures. Examples of the hard article include tableware, cooking equipment, a storage container, a bathtub, a toilet bowl, a vehicle, floor, a wall, window glass, a window frame, furniture, and a home appliance. The washing method of the present invention is preferably for a tableware. That is, a preferable embodiment of the present invention relates to a method for washing tableware. Examples of the tableware include tableware including a material selected from plastic, metal, ceramics, lacquer, wood, glass, and a combination thereof.

In the detergent composition for a hard article of the present invention, which is as defined in the appended claims, a potassium internal olefin sulfonate as component (a) and water having a hardness of <NUM>° DH or more as component (b) are formulated. Preferable embodiments of component (a) and component (b) are the same as those in the method for washing a hard article of the present invention. Examples of the hard article also include those described for the method for washing a hard article of the present invention. The detergent composition for a hard article of the present invention is suitably used in the method for washing a hard article of the present invention. A detergent composition for tableware is a preferable embodiment of the present invention.

In the detergent composition for a hard article of the present invention, component (a) is formulated in an amount of preferably <NUM>% by mass or more, more preferably <NUM>% by mass or more, further preferably <NUM>% by mass or more, and preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, further preferably <NUM>% by mass or less of the formulated raw materials. The detergent composition for a hard article of the present invention is excellent in stability even when it is a formulation containing component (a) at a high concentration. The detergent composition for a hard article of the present invention can be used, as it is, as a detergent liquid, preferably as a detergent liquid for use in the washing method of the present invention, depending on the amount of component (a) to be formulated.

The viscosity of the detergent composition for a hard article of the present invention is preferably <NUM> mPa·s or more, more preferably <NUM> mPa·s or more, and preferably <NUM>,<NUM> mPa·s or less, more preferably <NUM>,<NUM> mPa·s or less.

The pH of the detergent composition for a hard article of the present invention, at <NUM>, is preferably <NUM> or more, more preferably <NUM> or more, and preferably <NUM> or less, more preferably <NUM> or less.

The detergent composition for a hard article of the present invention can contain any optional component described for the detergent liquid for use in the present invention, as long as the effect of the present invention is not impaired. The formulation amount of the compound selected from the magnesium-containing inorganic compound and the alkylenediamine compound is, of the formulated raw materials, preferably <NUM>% by mass or more, more preferably <NUM>% by mass or more, and preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less. The formulation amount of the surfactant selected from a carbobetaine-type surfactant and an alkanolamide-type surfactant is, of the formulated raw materials, preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, further preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass or less, furthermore preferably <NUM>% by mass namely, the surfactant is furthermore preferably not blended.

The present invention relates to use, as a detergent for a hard article, of a composition in which (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more are formulated. To the use, the matters described for the method for washing a hard article and the detergent composition for a hard article of the present invention can be appropriately applied.

The present invention further discloses the following: a method for washing a hard article, a detergent composition for a hard article, and use thereof as a detergent for a hard article. To such aspect, the matters described for the method for washing a hard article, the detergent composition for a hard article, and the use as a detergent for a hard article of the present invention can be mutually appropriately applied.

A flask equipped with a stirring device was charged with <NUM> (<NUM> mol) of <NUM>-octadecanol (product name: Kalcol <NUM>, manufactured by Kao Corporation) and <NUM> of γ-alumina (Strem Chemicals, Inc. ) as a solid acid catalyst, and a reaction was performed at <NUM> under stirring while nitrogen was allowed to flow (<NUM>/min) in the reaction system. The reaction time was appropriately adjusted so as to produce internal olefins different in double bond distribution.

Each internal olefin produced in Production Example <NUM> was placed in a thin-film sulfonation reactor (inner diameter: <NUM> mmϕ, length: <NUM>), and a sulfonation reaction was performed using a sulfur trioxide gas having a concentration of SO<NUM> of <NUM>% by volume in a condition that cooling water at <NUM> was allowed to flow in an external jacket of the reactor. The reaction molar ratio of SO<NUM>/internal olefin was set to <NUM>.

The resulting sulfonated product was added to an aqueous alkaline solution which had been prepared by adding potassium hydroxide so as to satisfy an acid value (AV) <NUM> times by mol higher than the theoretical acid value, and the resulting mixture was neutralized with stirring at <NUM> for <NUM> hour. The neutralized product was heated in an autoclave at <NUM> for <NUM> hour to thereby perform hydrolysis, thereby producing a crude product of a potassium internal olefin sulfonate having <NUM> carbons.

<NUM> of the resulting crude product was transferred to a separatory funnel. <NUM> of ethanol was added thereto, and then <NUM> of petroleum ether per operation was added thereto to remove oil-soluble impurities. At this time, a component such as a salt cake precipitated at the oil-water interface by addition of ethanol was also separated and removed from an aqueous phase by the oil-water separation operation, and the operation was performed three times. The aqueous phase was subjected to evaporation to dryness, thereby providing a potassium internal olefin sulfonate having <NUM> carbons. This compound is represented by "C18" and "K salt" in the Tables.

The internal olefin produced in Production Example <NUM> was placed in a thin-film sulfonation reactor (inner diameter: <NUM> mmϕ, length: <NUM>), and a sulfonation reaction was performed using a sulfur trioxide gas having a concentration of SO<NUM> of <NUM>% by volume in a condition that cooling water at <NUM> was allowed to flow in an external jacket of the reactor. The reaction molar ratio of SO<NUM>/internal olefin was set to <NUM>.

The resulting sulfonated product was added to an aqueous alkaline solution which had been prepared by adding sodium hydroxide so as to satisfy an acid value (AV) <NUM> times by mol higher than the theoretical acid value, and the resulting mixture was neutralized with stirring at <NUM> for <NUM> hour. The neutralized product was heated in an autoclave at <NUM> for <NUM> hour to thereby perform hydrolysis, thereby producing a crude product of a sodium internal olefin sulfonate having <NUM> carbons.

<NUM> of the resulting crude product was transferred to a separatory funnel. <NUM> of ethanol was added thereto, and then <NUM> of petroleum ether per operation was added thereto to remove oil-soluble impurities. At this time, a component such as a salt cake precipitated at the oil-water interface by addition of ethanol was also separated and removed from an aqueous phase by the oil-water separation operation, and the operation was performed three times. The aqueous phase was subjected to evaporation to dryness, thereby providing a sodium internal olefin sulfonate having <NUM> carbons. This compound is represented by "C18" and "Na salt" in the Tables.

A flask equipped with a stirring device was charged with <NUM> (<NUM> mol) of <NUM>-hexadecanol (product name: Kalcol <NUM>, manufactured by Kao Corporation) and <NUM> of γ-alumina (Strem Chemicals, Inc. ) as a solid acid catalyst, and a reaction was performed at <NUM> under stirring while nitrogen was allowed to flow (<NUM>/min) in the reaction system. The reaction time was appropriately adjusted so as to thereby produce internal olefins different in double bond distribution.

The internal olefin produced in Production Example <NUM> and the internal olefin produced in Production Example <NUM> were mixed at a mass ratio, internal olefin in Production Example <NUM>/internal olefin in Production Example <NUM>, of <NUM>/<NUM>, thereby providing an internal olefin having <NUM>/<NUM> carbons. This olefin was placed in a thin-film sulfonation reactor (inner diameter: <NUM> mmϕ, length: <NUM>), and a sulfonation reaction was performed using a sulfur trioxide gas having a concentration of SO<NUM> of <NUM>% by volume in a condition that cooling water at <NUM> was allowed to flow in an external jacket of the reactor. The reaction molar ratio of SO<NUM>/internal olefin was set to <NUM>.

The resulting sulfonated product was added to an aqueous alkaline solution which had been prepared by adding potassium hydroxide so as to satisfy an acid value (AV) <NUM> times by mol higher than the theoretical acid value, and the resulting mixture was neutralized with stirring at <NUM> for <NUM> hour. The neutralized product was heated in an autoclave at <NUM> for <NUM> hour to thereby perform hydrolysis, thereby producing a crude product of a potassium internal olefin sulfonate having <NUM>/<NUM> carbons.

<NUM> of the resulting crude product was transferred to a separatory funnel. <NUM> of ethanol was added thereto, and then <NUM> of petroleum ether per operation was added thereto to remove oil-soluble impurities. At this time, a component such as a salt cake precipitated at the oil-water interface by addition of ethanol was also separated and removed from an aqueous phase by the oil-water separation operation, and the operation was performed three times. The aqueous phase was subjected to evaporation to dryness, thereby providing potassium internal olefin sulfonate having <NUM>/<NUM> carbons. The compound is represented by "C16/C18" and "K salt" in the Tables.

Each component (a) and ion exchange water, shown in Tables <NUM> to <NUM>, were used to prepare a concentrated composition for a detergent liquid, the concentrated composition having a content of component (a) of <NUM>% by mass. A compound not corresponding to component (a) was also shown as component (a) in Table <NUM>.

The mass of a glass slide or a polypropylene plate (represented by "PP" in the Tables) was measured (tare mass). The glass slide or polypropylene plate was coated with <NUM> of beef tallow, and the beef tallow was solidified to provide test piece (<NUM>). The mass (mass before washing) of test piece (<NUM>) was measured.

One gram of the concentrated composition for a detergent liquid was diluted with <NUM> of component (b), thereby preparing a detergent liquid.

The detergent liquid and test piece (<NUM>) were set in a tester described in "Detergency Evaluation Method of Synthetic Detergent for Kitchen" in JIS K <NUM><NUM>, and subjected to washing with stirring at each washing temperature in Tables <NUM> to <NUM> for <NUM> minutes. After the washing, test piece (<NUM>) was rinsed with water having the hardness in Tables <NUM> to <NUM>.

After the rinsing, test piece (<NUM>) was dried, the mass thereof (mass after washing) was measured and compared with the mass before washing, the amount of beef tallow removed by washing was calculated, and the washing rate was determined by the following formula. The results were shown in Tables <NUM> to <NUM>.

One gram of the concentrated composition for a detergent liquid was diluted to <NUM>-fold with water having a hardness in Tables <NUM> to <NUM>, thereby preparing a detergent liquid.

Thirty grams of the detergent liquid was absorbed in a sponge (Kikulon A manufactured by Kikulon Co. ) and foamed by crumpling ten times, and <NUM> of such foam was added to a measuring cylinder (manufactured by ARROW, <NUM>: bottom area: <NUM><NUM>).

Water having the hardness at the temperature in Tables <NUM> to <NUM> was continuously dropped from above of the measuring cylinder.

The dropping was performed at a total rate of <NUM>/sec using a tool, which was a resin bottle having a bottom area of <NUM><NUM> and having <NUM> holes each having a diameter of <NUM> on the bottom.

The state of foam immediately after the dropping was observed. The point of time when foam disappeared to allow the water surface to be seen from above of the measuring cylinder was defined as an endpoint, and the amount of water at the endpoint was recorded. The results were shown in Tables <NUM> to <NUM>.

In the Tables, C18 means that the number of carbons in component (a) is <NUM>.

In the Tables, the "Percentage of sulfonic acid at position <NUM>" of component (a) means the ratio of IOS-K or IOS-Na having the sulfonic acid group at position <NUM> in component (a).

In the Tables, water having a hardness not corresponding to the hardness of component (b) is also shown in the column of component (b), for convenience.

Claim 1:
A method for washing a hard article, the method comprising:
a contact step of bringing a detergent liquid obtained by mixing (a) a potassium internal olefin sulfonate and (b) water having a hardness of <NUM>° DH or more as determined below, into contact with the hard article, and
a step of rinsing the hard article after the contact step with water having a hardness of <NUM>° DH or more as determined below, wherein
the detergent liquid at <NUM> or more is brought into contact with the hard article in at least a part of the contact step,
wherein a mass ratio of a potassium internal olefin sulfonate having <NUM> carbons (hereinafter, referred to as "C<NUM>IOS-K") and a potassium internal olefin sulfonate having <NUM> carbons (hereinafter, referred to as "C<NUM>IOS-K") in (a), C<NUM>IOS-K/C<NUM>IOS-K, is <NUM> or less,
wherein the ratio of the total of C<NUM>IOS-K and C<NUM>IOS-K in component (a) is <NUM>% by mass or more; and
wherein, for the hardness of water (° DH), the concentration expressed in terms of CaCO<NUM> (mg/L) is determined according to Section <NUM>.<NUM> "Chelate Titration Method" in Section <NUM> "Total Hardness" in Chapter <NUM> of JIS K <NUM>:<NUM> "Testing Methods for Industrial Water", and this concentration is converted into the hardness of water by the following expression: <MAT>