ES2712055T3 - Spray drying process - Google Patents

Abstract

A spray drying process for preparing a spray dried powder comprising: (a) anionic detersive surfactant; (b) 0% by weight of zeolite-type builder; (c) 0% by weight of phosphate-type builder; (d) 0 wt% silicate salt; (e) optionally, carbonate salt; (f) optionally, polymeric material; and (g) optionally from 0 wt% to 10 wt% water, wherein the process comprises the steps of: (i) spraying an aqueous suspension comprising (a) anionic detersive surfactant; (b) 0% by weight of zeolite-type builder; (c) 0% by weight of phosphate-type builder; (d) 0 wt% silicate salt; (e) optionally, carbonate salt; (f) optionally, polymeric material; and (g) water, in a spray drying zone, wherein the spray drying zone is under negative pressure and wherein the temperature of the inlet air in the spray drying zone is higher than 150 ° C; and (ii) drying the aqueous suspension to form a spray-dried powder, wherein the spray-drying zone is at a pressure of at least -50 Nm-2.

Description

DESCRIPTION

Spray drying process

Field of the invention

The present invention relates to a spray drying process for preparing a highly soluble spray-dried powder with low additive content which is suitable for incorporating, or using as, a laundry detergent composition.

Background of the invention

Detergent manufacturers seek to provide low density laundry detergents that have improved dissolution profiles at cooler wash temperatures, such as 30 0C or ^{20 0} C. Water-insoluble materials, especially water-replenishing additives. Zeolite-type detergents have been removed, or their amount present in the powder has been significantly reduced.

In addition, there is also the need to ensure that the environmental profile of laundry detergent powder is as optimal as possible. This means that there is a tendency for manufacturers of laundry detergent powder to remove phosphate material, such as sodium tripolyphosphate (stpp) from spray-dried powder.

The main process for preparing a low density laundry detergent powder is to spray dry an aqueous suspension comprising detergent ingredients. Typically, this involves spraying the aqueous suspension in a spray-drying tower having hot air flow through which water is then evaporated from the aqueous suspension droplets, forming spray-dried powder as the material descends through the spray. tower.

However, the inventors have discovered that when materials such as zeolite and phosphate are removed from the solid content of the aqueous suspension, the temperature of the resultant spray-dried powder that is formed in the spray-drying zone has a tendency to overheat and its temperature profile is difficult to control. The inventors have discovered that the phenomenon of low temperature profile control is a specific problem of these highly soluble spray-dried powders with low content of laundry additives and had not been observed to any appreciable extent previously when spray-dried. conventional laundry detergents for laundry.

The inventors have discovered that this problem can be improved by operating the spray-drying tower under vacuum. The inventors have found that by ensuring that the spray drying zone is under vacuum, that is, so that the pressure in the spray drying zone is negative. This ensures that the ambient air is sucked into the interior of the spray-drying tower, which in turn provides a much more necessary cooling effect on the spray-dried powder formed therein. The inventors have found that control of the vacuum conditions in the spray drying zone provides good temperature control of the resulting spray dried powder.

All of the documents US-38949327, WO01 / 44427, DE-4208773 relate to spray drying processes for preparing powder.

Summary of the invention

The present invention provides a spray drying process as defined in claim 1.

Detailed description of the invention

Spray drying process

The spray drying process comprises the steps of: (i) spraying an aqueous suspension in a spray-drying zone, wherein the spray-drying zone is under negative pressure and wherein the temperature of the inlet air in the zone spray drying is greater than 150 ⁰ C; and (ii) drying the aqueous suspension to form a spray-dried powder. The aqueous suspension and the spray-dried powder are described in greater detail below.

2 The drying zone p 1o 2r p 1 ulverization is at 2 a p lesion of at least -50 Nm-2, p 1referibl 2emente at least -60 N 2m-, or at least -70 Nm, or at least -80 Nm , or at least -90 Nm, or at least -100 Nm, or at least -125 Nm, or at least -1500 Nm-2, or at least -175 Nm-2, or at least -200 Nm-2, or at least -250 Nm-2, or even at least -300 Nm-2. The greater the vacuum, the more ambient air is sucked into the lower part of the spray drying tower and the greater the cooling effort achieved. Typically, the maximum pressure that is can be used is determined by the structural strength of the spray drying tower and care must be taken not to exceed this maximum vacuum so that excessive stress is not exerted on the spray-drying tower. Typically, pressures of up to -600 Nm ^-2 or up to -500 Nm-2 are preferably used.

Preferably, the vacuum is controlled by controlling the speed setting and / or dampers of the inlet and outlet air fans. For example, when configuring the parameters of the spray drying tower, the inlet air fan (dilution air fan) is set at a fixed air flow rate. The configuration of the speed or of the shock absorbers of the exhaust air fans is then adjusted accordingly to control the strength of the vacuum in the tower. Some spray drying towers and manufacturing plants have a control loop to control the extractors (and thus the vacuum) that is normally activated approximately 5 minutes after startup. If more vacuum is needed, the extractors / shock absorbers are adjusted accordingly. The negative pressure in the spray drying tower can be measured by any available means. Typically, there are pressure sensors in the spray drying zone (inside the spray drying tower).

The temperature of the inlet air in the spray drying is preferably in the range of more than 150 0C to 500 ⁰ C, preferably from 200 ⁰ C, or 250 0C and preferably up to 450 ⁰ C, or even up to 400 ⁰ C. the temperature of the exhaust air (exhaust) is typically in the range from 50 0C to 150 ⁰ C, preferably 60 ⁰ C, or 70 or even 80 0C ⁰ C, and preferably up to 140 ⁰ C, or until 130 ⁰ C, or up to 120 ⁰ C, or up to 110 ⁰ C, or even up to 100 ⁰ C.

The temperature of spray dried powder leaving the tower spray drying this manner typical in the range of 50 to 150 ° C, preferably 60 ° C or even 70 ° C and preferably up to 140 ⁰ C, or to 130 ° C, or up to 120 ° C, or to 110 ° C, or even up to 100 ⁰ C. preferably the spray dried powder leaving the spray drying tower has a temperature below 150 ° C, preferably less at 140 ° C, or lower than 130 ° C, or lower than 120 ° C, or lower than 110 ° C, and preferably lower than 100 ° C.

The spray-dried powder typically leaves the spray-drying zone (eg, it falls from the spray-drying tower) onto a conveyor belt, where other ingredients (such as percarbonate particles) are added in dry form. to the powder to form a laundry detergent composition.

Aqueous solution

The aqueous solution comprises (a) anionic detersive surfactant; (b) 0% by weight of zeolite-type builder; (c) 0% by weight of phosphate-type builder; (d) 0 wt% silicate salt; (e) optionally, carbonate salt; (f) optionally, polymeric material; and (g) water. The aqueous suspension may comprise other adjuvant ingredients of the detergent.

Powder-dried powder

The spray dried powder comprises: (a) anionic detersive surfactant; (b) 0% by weight of zeolite-type builder; (c) 0% by weight of phosphate-type builder; (d) 0 wt% silicate salt; (e) optionally, carbonate salt; (f) optionally, polymeric material; and (g) optionally from 0 wt% to 10 wt% water,

Anionic detersive surfactant

The anionic detersive surfactant preferably comprises alkylbenzene sulfonate. Preferably the anionic detersive surfactant comprises at least 50%, preferably at least 55%, or at least 60%, or at least 65%, or at least 70%, or even at least 75%, by weight of the alkylbenzene anionic detersive surfactant sulfonate. Preferably, the alkylbenzene sulfonate is a linear or branched, substituted or unsubstituted C ^8-18 alkylbenzene sulphonate. This is the optimum level of C ^8-18 alkylbenzene sulfonate to provide a good cleaning capacity. The C ^8-18 alkylbenzene sulfonate can be a modified alkylbenzene sulphonate (MLAS) as described in more detail in WO 99/05243, WO 99/05242, WO 99/05244, WO 99/05082, WO 99/05084, WO 99/05241, WO 99/07656, WO 00/23549, and WO 00/23548. C ^8-18 alkylbenzene sulfonates Most preferred are alkylbenzene sulphonates C ^10-13 linear. Especially preferred are linear C ^10-13 alkylbenzene sulphonates which can be obtained, preferably, commercial linear sulfonated alkylbenzenes (LAB); Suitable LABs include LAB with low 2-phenyl content, such as those supplied by Sasol under the trade name Isochem® or those supplied by Petresa under the trade name Petrelab®, other suitable LABs include LAB with high 2-phenyl content, as those supplied by Sasol under the trade name Hyblene®.

The anionic detersive surfactant may preferably comprise other anionic detersive surfactants. A preferred adjuvant anionic detersive surfactant is a non-alkoxylated deionic anionic surfactant. The non-alkoxylated anionic detersive surfactant can be an alkyl sulfate, an alkyl phosphate, an alkyl phosphonate, an alkylcarboxylate or any mixture thereof. The non-alkoxylated anionic surfactant can be selected from the group consisting of: C ¹⁰ -C ²⁰ alkyl alkylsulphates (AS) primary, random chain, straight chain and branched chain typically having the following formula:

CH3 (CH2) xCH2-OSC> 3 "M +

wherein M is hydrogen or a cation that provides charge neutrality; the preferred cations are the sodium and ammonium cations, wherein x is an integer of at least 7, preferably at least 9; alkyl (2,3) C ¹⁰ -C ¹⁸ secondary sulfates, which typically have the following formula:

wherein M is hydrogen or a cation that provides charge neutrality, the preferred cations include sodium and ammonium cations, wherein x is an integer of at least 7, preferably at least 9, and is an integer of at least 8 , preferably at least 9; C ¹⁰ -C ¹⁸ alkylcarboxylates; branched chain alkyl sulfates which have been described in greater detail in US-6,020,303 and US 6,060,443; methyl ester sulfonate (MES); alpha-olefin sulfonate (AOS); and mixtures thereof.

Another preferred anionic detersive surfactant is an alkoxylated anionic detersive surfactant. The presence of an alkoxylated anionic detersive surfactant in the spray dried powder provides a good greasy dirt cleaning ability, provides a good sudsing profile, and improves the hardness tolerance of the anionic detersive surfactant system. It may be preferred that the anionic detersive surfactant comprises from 1% to 50%, or 5%, or 10%, or 15%, or 20%, and up to 45%, or up to 40%, or up to 35% , or up to 30%, by weight of the anionic detersive surfactant system, of an alkoxylated anionic detersive surfactant. Preferably, the alkoxylated anionic detersive surfactant is a linear or branched, substituted or unsubstituted alkylalkoxyC ^12-18 sulfate having an average degree of alkoxylation from 1 to 30, preferably from 1 to 10. Preferably, the alkoxylated anionic detersive surfactant is a sulfate alkylethoxylated C ^12-18 linear or branched, substituted or unsubstituted, having an average ethoxylation degree from 1 to 10. Most preferably, the alkoxylated anionic detersive surfactant is a linear C ^12-18 surfactant alkylethoxylated unsubstituted having a average degree of ethoxylation from 3 to 7.

The alkoxylated anionic detersive surfactant, when present with an alkylbenzene sulfonate can also increase the activity of the alkylbenzene sulfonate by making it less likely that the alkylbenzene sulfonate will be separated by precipitation from the solution in the presence of free calcium cations. Preferably, the weight ratio of the alkylbenzene sulfonate and the alkoxylated anionic detersive surfactant is in the range of 1: 1 to less than 5: 1, or less than 3: 1, or less than 1.7: 1, or even less than 1.5: 1. This ratio provides an optimum whiteness holding capacity combined with a good hardness tolerance profile and a good sudsing profile. However, it may be preferred that the weight ratio of the alkylbenzene sulfonate to the alkoxylated deionic anionic surfactant is greater than 5: 1, or greater than 6: 1, or higher than 7: 1, or even higher than 10: 1. This ratio provides an efficiency of optimum greasy dirt cleaning capacity combined with a good hardness tolerance profile and a good sudsing profile.

Some suitable alkoxylated anionic detersive surfactants are: Texapan LEST ™ by Cognis; Cosmacol AESTM from Sasol; BES151TM by Stephan; Empicol ESC70 / UTM; and mixtures thereof.

Preferably, the anionic detersive surfactant comprises from 0% to 10%, preferably up to 8%, or up to 6%, or up to 4%, or up to 2%, or even up to 1%, by weight of the detersive anionic surfactant, of detersive surfactants anionic unsaturates such as alpha-olefin sulfonate. Preferably the anionic detersive surfactant is practically free of unsaturated anionic detersive surfactants such as alpha-olefin sulfonate. By "practically exempt from" it means, in a typical way, "it does not contain deliberately added". Without wishing to impose any theory, it is believed that these levels of unsaturated anionic detersive surfactants such as alpha-olefin sulfonate ensure that the anionic detersive surfactant is compatible with bleaches.

Preferably, the anionic detersive surfactant comprises from 0% to 10%, preferably up to 8%, or up to 6%, or up to 4%, or up to 2%, or even up to 1%, by weight of alkyl sulfate. Preferably the anionic detersive surfactant is practically free of alkyl sulfate. Without intending to impose any theory, it is believed that these levels of alkyl sulfate ensure that the anionic detersive surfactant is tolerant to hardness.

Zeolite type builder

Zeolite-type builders include zeolite A, zeolite X, zeolite P and zeolite MAP.

Phosphate type detergent builder

The phosphate-type builders include sodium tripolyphosphate.

Silicate salt

Silicate salts include amorphous silicates and crystalline layered silicates (e.g., SKS-6). A preferred silicate salt is sodium silicate.

Carbonate salt

Suitable carbonate salts include sodium salts of carbonate and / or bicarbonate. A most preferred carbonate salt is sodium carbonate.

Polymer material

A preferred polymeric material is a polymeric carboxylate, such as a copolymer of maleic acid and acrylic acid. However, other polymers may also be suitable, such as polyamines (including the ethoxylated variants thereof), polyethylene glycol and polyesters. Also particularly suitable are polymeric soil suspending aids and polymeric soil release agents.

Adjuvant detergent ingredients

Suitable adjuvant detergent ingredients include: detersive surfactants such as nonionic detersive surfactants, cationic detersive surfactants, hybrid detersive surfactants, amphoteric detersive surfactants; the preferred non-ionic detersive surfactants are alkylalkoxylated alcohols Cs-is with an average degree of alkoxylation from 1 to 20, preferably from 3 to 10, more preferred are the ^C12-18 alkyl ethoxylated alcohols with an average degree of alkoxylation from 3 to 10; the preferred cationic detersive surfactants are monoalkyl chlorides ^6-8 mono-hydroxyethyldimethylammonium quaternary, mono-alkyl Cs- ¹⁰ mono-hydroxyethyldimethylammonium quaternary chloride, mono-alkyl C ^10-12 monohydroxyethyldimethylammonium chloride and chloride are more preferred. of mono-alkyl C ¹⁰ mono-hydroxyethyldimethylammonium quaternary; peroxygen source such as percarbonate salts and / or perborate salts, the sodium percarbonate is preferred, the peroxygen source is preferably at least partially coated, preferably completely coated, by a coating ingredient such as a carbonate salt, a salt of sulfate, a silicate salt, a borosilicate, or mixtures thereof, including mixed salts thereof; bleach activator such as tetraacetyl ethylenediamine, oxybenzenesulfonate bleach activators such as nonanoyloxybenzene sulfonate, caprolactam type bleach activators, imide type bleach activators such as N-nonanoyl-N-methylacetamide, preformed peracids such as N, N acid -phthaloylaminoperoxycaproic, nonilamidoperoxyadipic acid or dibenzoyl peroxide; enzymes such as amylases, carbohydrases, cellulases, laccases, lipases, oxidases, peroxidases, proteases, pectate lyases and mannanases; suds suppressor systems such as silicone-based suds suppressors; fluorescent whitening agents; photobleaching; filler salts such as sulfate salts, preferably sodium sulfate; fabric softening agents such as clay, silicone and / or quaternary ammonium compounds; flocculants such as poly (ethylene oxide); dye transfer inhibitors such as polyvinylpyrrolidone, poly (4-vinylpyridine N-oxide) and / or copolymer of vinylpyrrolidone and vinylimidazole; components for the integrity of tissues such as hydrophobically modified cellulose and oligomers produced by condensation of imidazole and epichlorohydrin; dirt dispersants and soil anti-redeposition coadjuvants such as alkoxylated polyamines and ethylenimine ethoxylated polymers; antiredeposition components such as carboxymethylcellulose and polyesters; perfumes; sulfamic acid or its salts; citric acid or its salts; and dyes such as orange dye, blue dye, green dye, purple dye, pink dye or any mixture thereof.

Preferably, the bleach adjuvant ingredients, such as sodium percarbonate and / or sodium perborate, are not spray dried. Typically, these adjuvant detergent ingredients are dry-added to the spray-dried powder and are not subjected to the higher temperatures and vacuum of the spray-drying process described above.

Examples

Example 1. A laundry detergent powder dried by spray and process to make it.

Aqueous solution composition.

Preparation of a laundry detergent powder spray dried.

An aqueous suspension having the composition as described above is prepared with a moisture content of 34.0%. Any ingredients added above in liquid form at 70 ⁰ C are heated, ensuring that the aqueous suspension never this at a temperature below 70 ⁰ C. At the end of preparation, the aqueous suspension is heated to 80 0C and pumped under pressure (7.5x10 ⁶ Nm-2), in a countercurrent spray drying tower with an air inlet temperature between 250 0C and 330 ⁰ C. The inlet air fan is configured in such a way that the air enters the tower flows to 187,500 kgh-1. The air extractor is controlled to provide a negative pressure in the tower of - 200 Nm ^-2 (Typically, the output air flow through the extractor is between 220,000 kgh ^-1 and 240,000 kgh-1, this includes the water evaporated from the suspension). The aqueous solution is atomized and the atomized aqueous solution is dried to produce a solid mixture which is then cooled and sieved to remove material of too large size (> ^1.8 mm) to form a spray-dried powder which is loose. Fine material (<0.175 mm) is decanted with the exhaust air from the spray-drying tower and collected in a post-tower confinement system. The spray-dried powder has a moisture content of 2.0% by weight, an apparent density of 350 g / l and a particle size distribution such that more than 90% by weight of the spray-dried powder has a particle size. from 175 to 710 micrometers. The temperature of the powder leaving the tower has a temperature below 150 ⁰ C. The composition of the spray dried powder is given.

Composition of washing powder detergent spray dried.

Claims (1)

A spray drying process for preparing a spray-dried powder comprising: (a) anionic detersive surfactant; (b) 0% by weight of zeolite-type builder; (c) 0% by weight of phosphate-type builder; (d) 0 wt% silicate salt; (e) optionally, carbonate salt; (f) optionally, polymeric material; Y (g) optionally from 0% by weight to 10% by weight of water, wherein the process comprises the steps of: (i) spraying an aqueous suspension comprising (a) anionic detersive surfactant; (b) 0% by weight of zeolite-type builder; (c) 0% by weight of phosphate-type builder; (d) 0 wt% silicate salt; (e) optionally, carbonate salt; (f) optionally, polymeric material; Y (g) water, in a spray drying zone, wherein the spray drying zone is under negative pressure and wherein the temperature of the inlet air in the spray drying zone is higher than 150 0C; Y (ii) drying the aqueous suspension to form a spray-dried powder, where the spray drying zone is at a pressure of at least -50 Nm-2. A spray drying process according to claim 1, wherein the spray drying zone is at a pressure of at least -100 Nm-2. A spray drying process according to claim 1, wherein the spray drying zone is at a pressure of at least -200 Nm-2. A spray drying process according to claim 1, wherein the spray-dried powder exiting the spray drying zone has a temperature below 150 ° C.