A method for performing retinal membrane removal is disclosed using vital dyes which are applied to the membrane. Compositions including vital dyes which are useful in the retinal membrane removal methods are also disclosed.

The invention relates to the field of ocular surgery, in particular to surgical procedures for vitreo-retinal surgery.
In the normal eye, the retina is located in the posterior segment of the eye, behind the corpus vitreum. The retina is a thin, translucent membrane resting on a single layer of pigmented epithelium, extending from the ora serrata to the optic disc. It consists of photoreceptor cells (rods and cones), which are connected to neuron pathways terminating in nonmyelinated fibers. These are combined to form the optic nerve. The innermost structure of the retina is the membrana limitans interna.
The vitreous is a clear, transparent, semi-solid gel which occupies about two thirds of the volume of the globe extending from the lens to the optic disc. It is a connective tissue space with the greater portion of the space made up of intercellular collagen and hyaluronic acid networks. The vitreous is in close contact with the epithelium of the pars plicata and pars plana, ora serrata and the internal limiting membrane of the retina as far as the optic disc. This contact may change with advancing years when the vitreous protein tends to shrink, and the vitreous detaches from the retina (=posterior vitreous detachment (PVD)).
The vitreous base represents the most solid attachment of the vitreous to the wall of the eye. It straddles the ora extending anteriorly on the pars plana over 1.5 to 2 mm and posteriorly on the retina over 3 to 4 mm. In PVD, the posterior vitreous separates from the retina and collapses anteriorly toward the vitreous base. Most retinal tears are caused by spontaneous or traumatic PVD, since traction on the vitreous here causes tenting of the retina and ciliary body. Retinal detachment may occur (sub)acutely. Virtually all retinal detachments could be repaired were it not for proliferative vitreoretinopathy (PVR) in which retinal pigment epithelial, glial, and other cells grow on both the inner and outer retinal surfaces and on the vitreous face to form a retinal membrane. These membranes may then contract, causing fixed folds, equatorial traction, detachment of the nonpigmented epithelium of the pars plana, and generalized retinal shrinkage. As a result, the causative retinal breaks may be reopened, or a traction detachment may develop. Hence, PVR is the most common cause of failure of retinal detachment surgery. Combining vitrectomy, scleral buckling, membrane peeling and dissection with extended retinal tamponade with long-acting gas (C3F8) or silicone oil enables about 75-90% of eyes undergoing vitrectomy for PVR to be eventually reattached, and about 50-75% to attain functional visual acuity of 5/200 or better. Eyes with PVR often require repeat procedures to reattach the retina such as fluid-gas exchange, laser photocoagulation, or reoperation.
Other retinal disorders in which membranes are formed include epiretinal membranes (macula Pucker), and macular holes, or a combination thereof. In the latter disorders, the macular function is compromised by gliose over the macula, that causes traction on the underlying retina, and therefore a distorted visual image for the patient. Both the PVR-membranes as well as the epiretinal membranes will be referred to as xe2x80x98retinal membranesxe2x80x99 in the text below.
Retinal membrane peeling and dissection is performed to relieve the traction on the retinal surface, so that the contracted tissue can be flattened out again. Removal of the membranes is often difficult, because the membranes consist of fibrous tissue having nearly the same color as the underlying retina. Improper visualization of the membranes on the retina therefore bears the risk of incomplete removal of the fibrous tissue, so that insufficient relaxation of the retina is achieved, or damage to the underlying retina, compromising its local function.
The present invention seeks to overcome the problems associated with poor visibility of the retinal membranes during vitreo-retinal surgery. It is an object of the invention to make it possible to visually distinguish the retinal membranes from the underlying retina, so that the membranes can be better identified during surgery, for example to prevent the uncomplete removal of the membranes, or damage to the retina itself.
Surprisingly, it has now been found that said object may be attained by using a specific dye or mixture of dyes, which is capable of staining tissue or a tissue component, such as a membrane, and which is physiologically and toxicologically acceptable. Hence, the invention relates to a method for performing retinal membrane removal, wherein the membranes are stained using at least one vital dye.
In a method according to the invention, the outer surface of the retinal membranes is selectively stained, by which is meant that the retinal tissue beneath the membranes is substantially not, or at least to a significantly lesser extent than the retinal membranes, stained. Accordingly, during the removal of the membranes, a clear distinction can be observed between the membranes that are being removed, and the underlying retina. This distinction facilitates the controlled removal of the membranes, and reduces the risk of inadvertent damage to the retina.
It has been observed that the staining of retinal. membranes does not have a detrimental effect on the tissue with which the dye is contacted. Furthermore, it has been observed that shortly after the surgical procedure has been completed, substantially all visible traces of the dye have disappeared. Thus, a patient undergoing vitreoretinal surgery involving staining of the retinal membranes in accordance with the invention experiences no more distress or undesired side effects as when a conventional surgical procedure, not involving staining, is employed.
Furthermore, undesired staining of the intraocular structures other than the retinal membranes does not, or not to an adverse extent, occur.
As has been mentioned above, in a method according to the invention, the retinal membranes are stained using a vital dye. A vital dye is a dye which has a sufficient coloring, or staining capacity at a concentration which is physiologically and toxicologically acceptable. In other words, the minimum amount of dye which is necessary to provide sufficient staining for a useful coloring to be visible should so be low that no, or hardly any, adverse toxic effects occur. Preferably, the dye is not or hardly toxic for the retina and adjacent structures. It is further preferred, that substantially no traces of the dye are present in the eye, shortly after the vitreo-retinal procedure has been completed. As a result, there is hardly any risk of the patient experiencing any side-effects from the use of the dye.
Examples of suitable vital dyes include azafloxin, basic blue (nil blue sulphate), bismarck brown, basic red (rhodamine 6G), bengal red, brilliant crysyl blue, eosin, fluorescein, gentian violet, indocyanine green, janus green, methylene green, methylene blue, neutral red, trypan blue, and trypan red.
Particularly good results have been achieved using a vital dye which is capable of staining tissue or a tissue component, substantially without diffusing through said tissue. The word substantially indicates that, although care is taken that a suitable dye is selected, it is of course possible that the dye diffuses through tissue in very small amounts. It has been found, that in accordance with this embodiment a particularly clear distinction may be observed between the stained retinal membranes and the surrounding tissues, among which the retina. Furthermore, according to this embodiment, the risk that any substantial amounts of dye remain in the eye after the surgical procedure is decreased significantly.
Particularly suitable examples of vital dyes which are capable of staining tissue or a tissue component, substantially without diffusing through said tissue are dyes having the formula (I)
wherein R1 and R2 are the same or different arylgroups, and wherein R3 and R4 are independently chosen from hydrogen, methyl, ethyl, methoxy, amino, hydroxyl, and sulfonate. R1 and R2 are preferably the same and formed by substituted naphtylgroups. Preferably, the naphtylgroups are substituted with one or more of sulfonate groups, amino groups and hydroxyl groups. These dyes have been found to bind predominantly to fibrous tissue, such as the tissue of the retinal membranes, in the circumstances that are envisaged for application of the present invention.
In a highly preferred embodiment, the dye is chosen from the group of trypan blue, trypan red, brilliant crysyl blue, and indocyanine green. It has been found that these dyes provide a clearly visible staining at very low amounts. Also, they have an extremely advantageous toxicity profile. More preferably, the dye is trypan blue.
Of course it is also possible to use mixtures of the above dyes as long as the resulting mixture is capable of achieving a color of retinal membranes which can be easily distinguished from the color of the material below or adjacent to said membranes.
The dye is preferably used as a physiologically compatible solution. In a particularly preferred embodiment, the dye is formulated in an aqueous salt solution, which is isotone with ocular fluid. The salt is preferably sodium chloride, sodium phosphate, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof. Suitable examples are Balanced salt solution or Hartmann""s lactated Ringer""s solution (Nuijts RMMA, Edelhauser HF, Holley GP, xe2x80x9cIntraocular irrigating solutions: a comparison of Hartmann""s lactated Ringer""s solution, BSS and BSS plusxe2x80x9d, Clin. Exp. Ophtamol., vol. 233 (1995), pp. 655-661). In accordance with this embodiment, the salt concentration will be in the range of 0.8 to 1.0 wt. %, based on the weight of the solution.
It is further preferred that the solution has a neutral pH, i.e. a pH between 6.5 and 7.5. The skilled person will be able to select a suitable buffer, which has the properties to be of use in opthtalmic applications. An example of a suitable buffer is phosphate buffered NaCl, commercially available at NPBI, Emmer-Compascuum, The Netherlands.
In certain cases, depending on the desired manner of applying the dye solution to the retinal membranes, it may be desired to formulate said solution as a dispersion, or a viscous or viscoelastomeric solution, for example using hyaluronic acid (see WO-A-96/32929). In certain cases, a higher viscosity may be desired in order to achieve better adherence of the dye to the retinal membranes. It will be well within the standard expertise of the skilled person to select a suitable form for the solution.
The concentration of the dye or the mixture of dyes in the solution will preferably be between 0.01 and 3 wt. %, more preferably between 0.05 and 0.5 wt. %, based on the weight of the solution. Within this range, the concentration may be adapted to the toxicity and coloring characteristics of the dye used. It is preferred that such an amount is chosen that an optimal staining effect is achieved, while at the same time the risk of possible damage to the eye or any part thereof due to the toxicity of the dye is minimized.
A method according to the invention is preferably employed as part of a vitreo-retinal surgical procedure. Such a surgical procedure may for instance be based on one of the following techniques: retinal detachment surgery, macula Pucker removal, or macular hole surgery. Preferably, the surgical procedure is performed on a mammalian eye, more preferably on a human eye.
After the eye is opened, for example by making a scleral incision, the vitreous (ocular gel) is removed and the posterior segment of the eye is filled with air. A few drops of the above described solution comprising the dye in an appropriate concentration is applied onto the retinal membranes. The application of the solution may be carried out by bringing a canula that is attached to a syringe containing the dye onto the vitreous cavity, and to inject a few drops of the dye, generally less than 1 ml, onto the retinal membranes.
The vitreous cavity is filled with air, so that the concentration of the dye in the solution is not lowered by liquid vitreous, and the dye can be applied onto a specific retinal area. As an alternative the dye can be administered in a higher concentration into the liquefied vitreous, or a dispersion of the dye in a viscous or viscoelastomeric solution can be used.
Preferably, excess of dye is washed out by irrigating the vitreous cavity, leaving a faint but clear staining of the retinal membranes, after which the surgery can be continued using routine techniques. The irrigation may be carried out by using Balanced salt solution or any other solution that is commonly used in intraocular surgical procedures.
After the retinal membranes have been stained, the membranes can be removed using routine surgical techniques. Although care should be taken that as much of the retinal membranes as possible is removed, it will be clear that the invention also encompasses surgical procedures wherein small parts of the retinal membranes are unintentionally not removed and remain present after the surgery. The retinal membranes can be identified because of the difference in color between the stained retinal membranes and the non-staining underlying retina, so that the outline of a retinal membrane can be visualized during its removal.

Use of vital dye for facilitating surgical procedures for vitreo-retinal surgery


In a telemarketing system in which responsive to system prompts a user selects a particular path through the system to peach a desired service offering, the present invention "learns" the path that the user repeatedly selects over a period of time and thereafter gives the user the option of advancing to the end point of that path without the user having to listen and respond to the system prompts.

Automated telemarketing systems use programmed voice instructions to handle telephone calls desiring information concerning, for example, financial reports, airline schedules, stock and bond quotations, etc. In essence, and automated telemarketing system is a tree-like structure having a hierachy of nodes each branching out to other nodes, or services. A caller is "talked" through a path starting at a root node, through several intermediate nodes and thence to the desired service. This is done by providing at each node a prerecorded verbal description of the services offered by the next branch of nodes. A caller selects each step in the path by inputting via his/her telephone a digit associated with the next node that the user desires to reach.
The complexity of an automated telemarketing system/user interface is geared to the type of services that the system provides. For example, in a simple automated telemarketing system providing banking services, a caller may only need to deal with one or two levels of prerecorded menus to reach a desired service point. However, in a complex automated telemarketing system providing, for example, stock and bond quotations, a caller may have to deal with four or more levels of prerecorded menus to reach a desired service point.
Human factors studies show that most callers are reluctant to deal with three or more levels of prerecorded menus and are more reluctant to do so when each menu contains four or more service announcements. To deal with this problem, some callers memorize the sequence of digits that they enter to reach a particular service point. Thereafter, they enter a digit of the sequence when reaching a respective node, or menu level to prelude having to listen to a litany of menu items.

Path learning feature for an automated telemarketing system


A cabinet cover construction for a formed sheet metal cabinet includes a front edge with two angled surfaces that are congruent with compatible angled surfaces of the top edge of the cabinet to ensure alignment of a closed cover on the cabinet and to prevent overbite of the cover upon closing thereof.

In a principal aspect the present invention relates to a cabinet cover construction for a sheet metal cabinet and, more particularly, to the construction of the front edge of the cabinet cover and the top edge of the cabinet panel that joins with the cabinet cover when the cover is in the closed position.
Sheet metal cabinets are utilized for many purposes. For example, such cabinets are used for tool storage, as pharmaceutical cabinets, as dental cabinets, and as general storage cabinets. Typically such cabinets include multiple metal drawers arranged in a vertical array, one above the other. Often such a cabinet construction also includes a hinged top cover that permits access to the top of the cabinet and that may serve as a work surface or enclose an additional storage area or both. Such covers are typically formed from sheet metal by a stamping process. Hinges are formed or welded on the backside of the cover for hinged attachment of the cover onto the backside of the cabinet. In this manner the cover may be closed over the top of the cabinet. Most typically, the cover includes vertical front, back and side edges to facilitate the formation of a covered enclosure on the top of the cabinet.
A problem that often exists with such constructions is known as xe2x80x9coverbitexe2x80x9d of the cabinet cover. Because the cabinet cover is formed from sheet metal, which is somewhat flexible particularly in larger sizes of covers, the front edge of the cover may tend to roll over the top edges of the vertical panels forming the cabinet itself. Thus there has remained an xe2x80x9coverbitexe2x80x9d problem in the design of cabinet covers for sheet metal cabinets.
Briefly, the present invention comprises a cabinet cover construction for a formed sheet metal cabinet of the type having a vertical front panel with a top edge and a cover panel with a front, vertically depending edge designed to engage with, mate with, and cooperate with the top edge of the vertical front panel. More specifically the top edge of the vertical panel includes an inwardly extending horizontal run having an inwardly and downwardly angled run extending therefrom. The front, vertically depending edge of the cover, which engages against the top edge of the front panel, also includes an inwardly extending horizontal run and a downwardly depending, angled run as well as a further inwardly extending, horizontal run that terminates on the inside of the cabinet cover. The cabinet cover, when in a closed position, is designed so that the runs when viewed in cross section fully overlap one another. The angled runs thus have common angles and a common apex. As a result, when the top cover is closed with the front edge thereof against the top edge of the front panel, the arrangement of the horizontal and angled runs insures that the cabinet parts will mesh together in a manner that precludes undesirable overbite. Additionally, the second inward extending horizontal run on the inside of the cover provides a strike for engagement by a bolt to thereby facilitate locking the cover in a closed position. Thus it is an object of the invention to provide an improved cabinet cover construction for a formed sheet metal cabinet.
It is a further object of the invention to provide a cabinet cover construction for a formed sheet metal cabinet, which prevents the occurrence of xe2x80x9coverbitexe2x80x9d.
Another object of the invention is to provide a cabinet cover construction for a formed metal sheet cabinet, which is easily manufactured and easily incorporated in sheet metal cabinet constructions.
Another object of the invention is to provide an improved cabinet cover construction for a formed metal cabinet which is economical, rugged, and which may be incorporated easily into preexisting cabinet constructions.
These and other objects, advantages, and features of the invention will be set forth in the detailed description which follows.

Cabinet cover construction for formed sheet metal cabinets


Electric toothbrush comprises an oscillating, bristle bearing head which comprises two or more segments which are integral with one another.

1. Field of the Invention
The present invention relates to an electric toothbrush with an oscillating head.
2. The Related Art
Electric toothbrushes are generally considered to provide a level of cleaning which is at least equal to that obtainable by manual brushes while providing a more convenient mode of operation.
Typical electric toothbrushes comprise a bristle bearing head which oscillates around an oscillating axis, where said axis is usually co-axial with a circular bristle bearing head.
However, some brushes have particular oscillating patterns, such as longitudinally oscillating elements, or they may have multiple brush heads, such as that marketed by Phillips under the tradename xe2x80x98Plaque Remover(copyright)xe2x80x99, which comprises a rotating head and an independent, laterally oscillating array of bristles distal to the brush handle.
An object of the present invention is to provide a cheap electric toothbrush, which provides an improved cleaning benefit and is easy and comfortable to use.
We have found that an electric toothbrush can provide an improvement upon the prior art when the oscillating brush head comprises two or more bristle bearing segments which are integral with one another.
Accordingly, the present invention provides an electric toothbrush comprising an oscillating, bristle bearing head wherein the head includes two or more segments which are integral with one another.
It is to be understood that the term xe2x80x98headxe2x80x99 used with reference to an electric toothbrush means a bristle bearing section and a neck portion connecting the bristle bearing section to the handle.
It is an essential feature of the invention that the segments in the head are integral with one another. By this is meant that they oscillate as a single unit so that a single oscillating means may oscillate the entire head. This in contrast with brushes which have multiple independent oscillating units where a separate mechanism is required to oscillate each bristle bearing member. Accordingly, the term integral is meant to include not just segments which are unitary but also to those which are linked so as to form a single oscillating member.
In a preferred embodiment the oscillating axis of the brush head passes through the brush head. In this way the brush head rotates around the head so that a greater range of motion is effected by the bristles. This is in contrast to a brush head which is merely displaced side to side during oscillation because the axis is remote from the head.
Further to there being any number of segments on such a segmented brush head each segment may be unitary with any of a number of other segments or be linked to any number of other segments by a further material. For example, the brush head may comprise segments which are linked to one another via a material common to both, e.g. a polypropylene base, thereby providing a living hinge. Alternatively, the segments may be separated by a groove or chasm which is comprised solely of the living hinge or it may be partially or solely filled with an elastomeric material. It is, of course, perfectly feasible for different links to be employed for different segments thereby modifying the oscillating characteristics of the individual segments and the brush head as a whole.
The inclusion of a multi-segmented head can modify the vibrational character of the brush head in such a way as to improve the cleaning of an oscillating brush brush. It is also possible that it may reduce the output required from the motor element, which in turn may make the brush more comfortable to use and reduce the power requirements, thus reducing battery changing frequency.
A conventional brush head comprises hard materials, such as polypropylene or polyacrylonitrile and it may be that the physical dimensions of these materials provide the flexibilty of the head, e.g. the brush head comprises segments which are linked by a hinge comprising a material common with the segments but may also comprise an elastomeric material to supplement the flexibility of the link regions. Alternatively, the elastomer may comprise the link region in its entirety. The inclusion of elastomeric material to the link region of the brush head may extend to surrounding any amount of the brush head. This may reduce the incidence of damage to the users gums and lips as the rubbery elastomer absorbs the vibrations of the motor.
By elastomeric material is meant that the material has some elastic nature. Given that electric toothbrushes vibrate at an extremely high frequency it is anticipated that a high elastic nature is not necessary and a material with a Shore A hardness of less than conventionally used polypropylene is suitable for use in the present invention.
In a preferred embodiment, the rubbery material has a Shore A hardness of less than 100, more preferably less than 80, and especially less than 55. An acceptable minimum Shore A hardness is 13.
Particularly suitable rubbery material -include elastomeric materials such as those described in W097/20484, the contents which relate to said elastomeric materials are incorporated by reference. Typical of such suitable elastomeric materials include a thermoplastic vlucanate (TPV) consisting of a mixture of polypropylene and EPDM (ethylene propylene diene monomers) which is available as SANTOPRENE (brand), described in U.S. Pat. No. 5,393,79 issued to Halberstadt et at, or VYRAM (brand), another TPV consisting of a mixture of polypropylene and natural rubber, both SANTOPRENE and VYRAM (brands) being elastomers marketed by Advanced Elastomer Systems. Other suitable elastomers include KRATON, a brand of styrene block copolymer (SBC) marketed by Shell, and DYNAFLEX G 2706 (brand), a thermoplastic elastomer marketed by GLS Corporation and which is made with KRATON (brand) polymer. These and other suitable elastomers have, typically, a Shore A hardness of from about 13 to 94, with about 29 being a preferred hardness.
In a preferred embodiment the flexibilty in the head is achieved through the use of a hinge between the segments. Such a living hinge is preferably arranged so as to allow flexing in an axis which is parallel to the oscillating axis. In this way, the oscillation on the brush head around the oscillating axis also directly produces flexing around the living hinge.
It is also envisaged that the head of the brush according to the invention may be replaceable.
In an alternative aspect the invention provides an electric toothbrush with improved sensory benefits. The brush according to the invention provides an improved feel in the oral cavity, especially when the brush comprises a rubbery elastomeric material in the head or neck. This is particularly so when the non-bristle bearing surfaces of the head is significantly covered by an elastomeric material and contacts the buccal lining. This sensory benefit is seen as an important consumer positive.
The electric toothbrush according to the invention provides an improvement over the prior art by the inclusion of a flexible head section. It is thought that the flexible head provides enhanced oscillation/vibration due to its flexible nature or, more specifically, due to the differences in elasticity of the materials/sections comprising the head.
Further embodiments of the invention are now described with reference to the figures.

Unilever Home and Personal Care USA, division of Conopco, Inc.


The invention relates to a neutralization and granulation method wherein a neutralizing foam is used as granulation adjuvant. The neutralizing foam was previously obtained by mixing an anionic surfactant in its acid form, which was expanded using a gaseous medium, and a highly concentrated, aqueous alkaline component, which was expanded using a gaseous medium. The neutralizing foam has an average pore size of less than 10 mm, preferably less than 5 mm and especially less than 2 mm.

This invention relates to a process for the production of detergents. More particularly, the invention relates to a process by which it is possible to produce detergent compositions with or without a reduced number of spray drying steps.
Granular detergent compositions are largely produced by spray drying. In the spray drying process, the ingredients, such as surfactants, builders etc. containing around 35 to 50% by weight of water, are mixed to form an aqueous suspension, known as a slurry, and the resulting mixture is sprayed into a hot gas stream in spray drying towers, resulting in the formation of the detergent particles. Both the installations for this process and the operation of the process are expensive because most of the water in the slurry has to be evaporated in order to obtain particles having residual water contents of around 5 to 10% by weight. In addition, although the granules produced by spray drying generally show excellent solubility, they have low bulk densities which leads to higher packaging volumes and transportation and storage capacities. The flowability of spray-dried granules is also far from optimal in view of their irregular surface structure which also has an effect on their appearance. Spray drying processes have a number of other disadvantages, so that there has been no shortage of attempts to carry out the production of detergents without any spray drying whatever or at least to have low levels of spray-dried products in the end product.
Thus, W. Hermann de Groot, I. Adami, G. F. Moretti in xe2x80x9cThe Manufacture of Modern Detergent Powdersxe2x80x9d, Hermann de Groot Academic Publisher, Wassenaar, 1995, pages 102 et seq. describe various mixing and granulation processes for the production of detergents. One feature common to all these processes is that premixed solids are granulated in the presence of the liquid ingredients and optionally dried in a following step.
A broad prior art on the non-tower production of detergents also exists in the patent literature. Many of these processes start out from the acid form of anionic surfactants because, in quantitative terms, this class of surfactants represents the largest percentage of detersive substances and because, in the course of their production, anionic surfactants accumulate in the form of the free acids which have to be neutralized to the corresponding salts.
Thus, European patent application EP-A-0 678 573 (Procter and Gamble) describes a process for the production of flowable surfactant granules having bulk densities above 600 g/l, in which anionic surfactant acids are reacted with an excess of neutralizing agent to form a paste containing at least 40% by weight of surfactant and the resulting paste is mixed with one or more powder(s), of which at least one has to be spray-dried and contains anionic polymer and cationic surfactant, the resulting granules optionally being dried. Although this document reduces the percentage of spray-dried granules in the detergents, it does not avoid spray drying altogether.
European patent application EP-A-0 438 320 (Unilever) discloses a batch process for the production of surfactant granules having bulk densities above 650 g/l. In this process, the anionic surfactant acid is added, optionally with other solids, to a solution of an alkaline inorganic substance in water and the whole is granulated with a liquid binder in a high-speed mixer/granulator. Although neutralization and granulation take place in the same apparatus, they are carried out in separate process steps so that the process can only be operated in batches.
European patent application EP-A-0 402 112 (Procter and Gamble) describes a continuous neutralization/granulation process for the production of FAS and/or ABS granules from the acid, in which the ABS acid is neutralized with at least 62% NaOH and is then granulated in the presence of auxiliaries, for example ethoxylated alcohols or alkyl phenols or a polyethylene glycol with a molecular weight of 4,000 to 50,000 melting at temperatures above 48.9xc2x0 C.
European patent application EP-A-0 508 543 (Procter and Gamble) discloses a process in which a surfactant acid is neutralized with an excess of alkali to form an at least 40% by weight surfactant paste which is subsequently conditioned and granulated, the granules being directly cooled with dry ice or liquid nitrogen.
Dry neutralization processes, in which sulfonic acids are neutralized and granulated, are disclosed in EP 555 622 (Procter and Gamble). According to the teaching of this document, the anionic surfactant acids are neutralized in a high-speed mixer with an excess of fine-particle neutralizing agent having a mean particle size below 5 xcexcm.
A similar process, which is also carried out in a high-speed mixer and in which sodium carbonate ground to between 2 and 20 xcexcm in size is used as the neutralizing agent, is described in WO 98/20104 (Procter and Gamble).
Surfactant mixtures which are subsequently sprayed onto solid absorbents and which provide detergent compositions or complonents therefor are also described in EP 265 203 (Unilever). The liquid surfactant mixtures disclosed in this document contain sodium or potassium salts of alkyl benzenesulfonic acids or alkyl sulfuric acids in quantities of up to 80% by weight, ethoxylated nonionic surfactants in quantities of up to 80% by weight and at most 10% by weight water.
Similar surfactant mixtures are also described in earlier EP 211 493 (Unilever). According to the teaching of this document, the surfactant mixtures to be sprayed on contain between 40 and 92% by weight of a surfactant mixture and more than 8 to at most 60% by weight of water. At least 50% of the surfactant mixture itself consists of polyalkoxylated nonionic surfactants and ionic surfactants.
A process for the production of a liquid surfactant mixture of the three components anionic surfactant, nonionic surfactant and water is described in EP 507 402 (Unilever). The surfactant mixtures disclosed in this document, which are said to contain very little water, are obtained by combining equimolar quantities of neutralizing agent and anionic surfactant acid in the presence of nonionic surfactant.
DE-A-42 32 874 (Henkel KGaA) discloses a process for the production of detersive anionic surfactant granules by neutralizing anionic surfactants in their acid form. However, only solid powders are disclosed as the neutralizing agents. The granules obtained have surfactant contents of around 30% by weight and bulk densities below 550 g/l.
EP-A-642 576 (Henkel KGaA) describes a two-step granulation process carried out in two mixer/granulators arranged in tandem, 40 to 100% by weight, based on the total quantity of constituents used, of the solid and liquid constituents being pregranulated in a first low-speed granulator and the xe2x80x9cpregranulesxe2x80x9d being mixed with the remaining constituents, if any, and converted into granules in a second high-speed granulator.
EP 772 674 (Henkel KGaA) describes a process for the production of surfactant granules by spray drying in which anionic surfactant acid(s) and highly concentrated alkaline solutions are separately exposed to a gaseous medium and mixed in a multicomponent nozzle, neutralized and spray-dried by spraying into a hot gas stream. The fine-particle surfactant particles thus obtained are then agglomerated in a mixer to form granules with bulk densities above 400 g/l.
Now, the problem addressed by the present invention was to provide a process by which it would be possible to produce detergents with or without a reduced number of spray drying steps. The process to be provided by the invention would also enable the acid forms of detergent raw materials to be processed in a direct and economically attractive manner, but would avoid the disadvantage of the energy-intensive evaporation of water as far as possible. Theoretical solutions to the described problems are described in the prior-art literature cited in the foregoing. Nevertheless, the processes in question are attended by a number of disadvantages:
the neutralization with NaOH, as described in the prior art, generates a considerable amount of heat, overheating leading to the unwanted darkening of the products in color;
direct cooling with dry ice or liquid nitrogen incurs high operating costs;
cooling by indirect heat transfer requires a slow or even batch reaction with long holding times and large reactor volumes which requires high capital investment costs;
in the case of indirect cooling, the viscosity of the neutralization mixture often increases dramatically, so that water has to be added which in turn entails subsequent drying;
high concentrations of active substances generally increase the viscosity, with the result that the neutralizate is difficult to incorporate uniformly during subsequent agglomeration steps on solid carriers;
where solid neutralizing and agglomerating agents (for example sodium carbonate) are used, the neutralization reaction either proceeds slowly and/or is initially incomplete, so that acid-sensitive solids, such as silicates or zeolites, should not be present in the solid bed.
Avoiding the above-mentioned disadvantages and providing a process which would enable anionic surfactant acids to be quickly and completely neutralized without the danger of overheating and which would include particularly easy further processing to surfactant-containing granules were further objects of the present invention.
The problem stated above is solved by a mixing and granulation process in which anionic surfactant acid(s) and alkali solutions are combined to form a neutralizate foam which acts as a granulation aid. Accordingly, the present invention relates to a process for the production of surfactant granules in which an anionic surfactant in its acid form and a highly concentrated aqueous alkaline component are separately exposed to a gaseous medium, subsequently combined and then neutralized and both the anionic surfactant in its acid form and the highly concentrated aqueous alkaline component are foamed by the gaseous medium and the acidic and alkaline foams formed are combined to form a neutralizate foam which is subsequently applied to a bed of solids accommodated in a mixer.
The term xe2x80x9cfoamxe2x80x9d used in the present specification characterizes structures of gas-filled, spherical or polyhedral cells (pores) which are defined by liquid, semiliquid or highly viscous cell walls.
If the concentration by volume of the gas forming the foam is less than 74% for homodisperse distribution, the gas bubbles are spherical on account of the surface-reducing effect of the interfacial tension. Beyond the close packing limit, the bubbles are deformed to polyhedral lamellae which are defined by ca. 4-600 nm thin skins. The cell wallsxe2x80x94joined via by so-called nodal pointsxe2x80x94form a coherent structure. The foam lamellae extend between the cell walls (closed-cell foam). If the foam lamellae are destroyed or if they flow back into the cell walls at the end of foaming, an open-cell foam is obtained. Foams are thermodynamically unstable because surface energy can be obtained by making the surface smaller. Accordingly, the stability and hence the existence of the foams according to the invention depends on the extent to which it is possible to prevent their self-destruction.
To produce the foams, the gaseous medium may be injected into the above-mentioned liquids. Alternatively, foaming can be achieved by intensive beating, shaking, spraying or stirring of the liquid in the particular gas atmosphere. Because it provides for easier foaming and can be better controlled and carried out, foam generation by injection of the gaseous medium (xe2x80x9cmechanical blowingxe2x80x9d) is distinctly preferred to the other variants for the purposes of the present invention. Depending on the required process variant, mechanical blowing takes place continuously or discontinuously via perforated plates, sintered disks, sieve insets, Venturi nozzles, inline mixers, homogenizers or other standard systems.
Any gases or gas mixtures may be used as the gaseous medium for foaming. Examples of gases used in the art are nitrogen, oxygen, noble gases and noble gas mixtures, for example helium, neon, argon and mixtures thereof, carbon dioxide, etc. For reasons of cost, the process according to the invention is preferably carried out with air as the gaseous medium. Providing the components to be foamed are oxidation-resistant, the gaseous medium may even consist entirely or partly of ozone so that impurities or discoloration destroyable by oxidation in the surfactant-containing liquid components to be foamed can be eliminated or germ infestation of those components can be prevented.
The process according to the invention comprises the independent steps of producing foams from an anionic surfactant in its acid form and from a highly concentrated, aqueous alkaline component. The two foams are then combined to form a neutralizate foam which subsequently serves as a granulation aid when added to a bed of solids accommodated in a mixer. The ingredients of the intermediate products of the first two steps are described hereinafter.
One or more representatives from the group of carboxylic acids, sulfuric acid semiesters and sulfonic acids, preferably from the group of fatty acids, fatty alkyl sulfuric acids and alkylaryl sulfonic acids, is/are preferably used as the anionic surfactants in acid form. In order to obtain adequate surface-active properties, the compounds mentioned should have relatively long hydrocarbon chains, i.e. should contain at least 6 carbon atoms in the alkyl or alkenyl group. The C-chain distributions of the anionic surfactants are normally in the range from 6 to 40, preferably in the range from 8 to 30 and more preferably in the range from 12 to 22 carbon atoms.
On an industrial scale, carboxylic acidsxe2x80x94which are used in the form of their alkali metal salts as soaps in detergentsxe2x80x94are largely obtained from native fats and oils by hydrolysis. Whereas alkaline saponification, which was practised as long ago as the last century, led directly to the alkali metal salts (soaps), only water is now industrially used for hydrolysis, splitting the fats into glycerol and the free fatty acids. Industrially used processes include, for example, hydrolysis in an autoclave and continuous high-pressure hydrolysis. According to the invention, carboxylic acids suitable for use as the anionic surfactants in acid form are, for example, hexanoic acid (caproic acid), heptanoic acid (oenanthic acid), octanoic acid (caprylic acid), nonanoic acid (pelargonic acid), decanoic acid (capric acid), undecanoic acid, etc. According to the invention, it is preferred to use fatty acids, such as dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachic acid), docosanoic acid (behenic acid), tetracosanoic acid (lignoceric acid), hexacosanoic acid (cerotic acid), triacontanoic acid (melissic acid) and the unsaturated species 9c-hexadecenoic acid (palmitoleic acid), 6c-octadecenoic acid (petroselic acid), 6t-octadecenoic acid (petroselaidic acid), 9c-octadecenoic acid (oleic acid), 9t-octadecenoic acid (elaidic acid), 9c,12c-octadecadienoic acid (linoleic acid), 9t,12t-octadecadienoic acid (linolaidic acid) and 9c,12c,15c-octadecatrienoic acid (linolenic acid). For reasons of cost, technical mixtures of the individual acids obtainable from the hydrolysis of fats are used in preference to the pure species. Mixtures such as these are, for example, coconut oil fatty acid (ca. 6% by weight C8, 6% by weight C10, 48% by weight C12, 18% by weight C14, 10% by weight C16, 2% by weight C18, 8% by weight C18xe2x80x2, 1% by weight C18xe2x80x3), palm kernel oil fatty acid (ca. 4% by weight C8, 5% by weight C10, 50% by weight C12, 15% by weight C14, 7% by weight C16, 2% by weight C18, 15% by weight C18xe2x80x2, 1% by weight C18xe2x80x3), tallow fatty acid (ca. 3% by weight C14, 26% by weight C16, 2% by weight C16xe2x80x2, 2% by weight C17, 17% by weight C18, 44% by weight C18xe2x80x2, 3% by weight C18xe2x80x3, 1% by weight C18xe2x80x2xe2x80x3), hydrogenated tallow fatty acid (ca. 2% by weight C14, 28% by weight C16, 2% by weight C17, 63% by weight C18. 1% by weight C18xe2x80x2), technical oleic acid (ca. 1% by weight C12, 3% by weight C14, 5% by weight C16, 6% by weight C16xe2x80x2, 1% by weight C17, 2% by weight C18, 70% by weight C18xe2x80x2, 10% by weight C18xe2x80x3, 0.5% by weight C18xe2x80x2xe2x80x3), technical palmitic/stearic acid (ca. 1% by weight C12, 2% by weight C14, 45% by weight C16, 2% by weight C17, 47% by weight C18. 1% by weight C18xe2x80x2) and soybean oil fatty acid (ca. 2% by weight C14, 15% by weight C16, 5% by weight C18, 25% by weight C18xe2x80x2, 45% by weight C18xe2x80x3, 7% by weight C18xe2x80x2xe2x80x3).
Sulfuric acid semiesters of relatively long-chain alcohols are also anionic surfactants in their acid form and may be used in the process according to the invention. Their alkali metal salts, more especially sodium salts, the fatty alcohol sulfates, can be industrially obtained from fatty alcohols which are reacted with sulfuric acid, chlorosulfonic acid, amidosulfonic acid or sulfur trioxide to form the corresponding alkyl sulfuric acids and then neutralized. The fatty alcohols are obtained from the corresponding fatty acids or fatty acid mixtures by high-pressure hydrogenation of the fatty acid methyl esters. In quantitative terms, the most important industrial process for the production of fatty alkyl sulfuric acids is sulfonation of the alcohols with SO3/air mixtures in special cascade, falling-film or tube-bundle reactors.
Another class of anionic surfactant acids which may be used in the process according to the invention are the alkyl ether sulfuric acids of which the salts, the alkyl ether sulfates, are distinguished from the alkyl sulfates by greater solubility in water and lower sensitivity to water hardness (solubility of the Ca salts). Like the alkyl sulfuric acids, alkyl ether sulfuric acids are synthesized from fatty alcohols which are reacted with ethylene oxide to form the corresponding fatty alcohol ethoxylates. Propylene oxide may be used instead of ethylene oxide. The subsequent sulfonation with gaseous sulfur trioxide in short-time sulfonation reactors gives yields of more than 98% of the corresponding alkyl ether sulfuric acids.
Alkane sulfonic acids and olefin sulfonic acids may also be used as anionic surfactants in acid form for the purposes of the present invention. Alkane sulfonic acids may contain the sulfonic acid group terminally bound (primary alkane sulfonic acids) or along the C-chain (secondary alkane sulfonic acids), only the secondary alkane sulfonic acids being of commercial importance. They are prepared by sulfochlorination or sulfoxidation of linear hydrocarbons. Where sulfochlorination is carried out by Reed""s method, n-paraffins are reacted with sulfur dioxide and chlorine in the presence of UV light to form the corresponding sulfochlorides which directly give the alkane sulfonates on hydrolysis with alkalis and the alkane sulfonic acids on reaction with water. Since di- and polysulfochlorides and chlorinated hydrocarbons can occur as secondary products of the radical reaction in the sulfochlorination process, the reaction is normally continued to conversions of only 30% and then terminated.
Another process for the production of alkane sulfonic acids is sulfoxidation in which n-paraffins are reacted with sulfur dioxide and oxygen in the presence of UV light. Successive alkyl sulfonyl radicals are formed in this radical reaction and then react with oxygen to form the alkyl persulfonyl radicals. The reaction with unreacted paraffin produces an alkyl radical and the alkyl persulfonic acid which breaks down into an alkyl peroxysulfonyl radical and a hydroxyl radical. The reaction of the two radicals with unreacted paraffin gives the alkyl sulfonic acids and water which reacts with alkyl persulfonic acid and sulfur dioxide to form sulfuric acid. In order to keep the yield of the two end products, alkyl sulfonic acid and sulfuric acid, as high as possible and to suppress secondary reactions, this reaction is normally continued to conversions of only 1% and then terminated.
Olefin sulfonates are industrially produced by reaction of xcex1-olefins with sulfur trioxide. Zwitterions are formed as intermediate products and cyclize to form so-called sultones. Under suitable conditions (alkaline or acidic hydrolysis), these sultones react to form hydroxyalkane sulfonic acids or alkene sulfonic acids which may both also be used as anionic surfactant acids.
Alkyl benzenesulfonates as high-performance anionic surfactants have been known since the nineteen thirties. At that time, alkyl benzenes were produced by monochlorination of Kogasin fractions and subsequent Friedel-Crafts alkylation, sulfonated with oleum and neutralized with sodium hydroxide. At the beginning of the fifties, alkyl benzenesulfonates were produced by tetramerizing propylene to form branched xcex1-dodecylene and reacting the product in a Friedel-Crafts reaction using aluminium trichloride or hydrogen chloride to form tetrapropylene benzene which was then sulfonated and neutralized. This economic method of producing tetrapropylene benzene sulfonates (TPS) led to the breakthrough of this class of surfactants which subsequently displaced soaps as the main surfactant in detergents.
In view of the biological non-degradability of TPS, new alkyl benzenesulfonates distinguished by improved ecological behavior had to be produced. These requirements are satisfied by linear alkyl benzenesulfonates which, today, are virtually the only alkyl benzenesulfonates in production and which are referred to in short by the initials ABS.
Linear alkyl benzenesulfonates are prepared from linear alkyl benzenes which in turn can be obtained from linear olefins. To this end, petroleum fractions are separated using molecular sieves into the n-paraffins with the requisite purity and dehydrogenated to the n-olefins, both xcex1- and i-olefins being obtained. The olefins thus obtained are then reacted with benzene in the presence of acidic catalysts to form the alkyl benzenes, the choice of the Friedel-Crafts catalyst having an influence on the isomer distribution of the linear alkyl benzenes formed. Where aluminium trichloride is used, the content of the 2-phenyl isomers in the mixture with the 3-, 4-, 5- and other isomers is approximately 30% by weight. If, by contrast, hydrogen fluoride is used as the catalyst, the 2-phenyl isomer content can be reduced to around 20% by weight. Finally, the sulfonation of the linear alkyl benzenes is now carried out on an industrial scale with oleum, sulfuric acid or gaseous sulfur trioxide, gaseous sulfur trioxide having by far the greatest importance. Special falling-film or tube-bundle reactors are used for the sulfonation process and give as the end product a 97% by weight alkyl benzenesulfonic acid (ABSA) which may be used as the anionic surfactant acid for the purposes of the present invention.
Various salts, i.e. alkyl benzene sulfonates, can be obtained from the ABSA, depending on the choice of the neutralizing agent. For reasons of economy, it is preferred to produce and use the alkali metal salts of ABSA, preferably the sodium salts. The sodium salts correspond to general formula I:
in which the sum of x and y is normally between 5 and 13. Processes according to the invention, in which C8-16, preferably C9-13 alkyl benzene-sulfonic acids are used as the anionic surfactant in acid form, are preferred. Another preferred embodiment of the present invention is characterized by the use of C8-16, preferably C9-13 alkyl benzenesulfonic acids derived from alkyl benzenes having a tetralin content of less than 5% by weight, based on the alkyl benzene. Another preferred embodiment is characterized by the use of alkyl benzenesulfonic acids of which the alkyl benzenes have been produced by the HF process, so that the C8-16, preferably C9-13 alkyl benzene sulfonic acids used have a 2-phenyl isomer content below 22% by weight, based on the alkyl benzenesulfonic acid.
The anionic surfactants in their acid form mentioned above may be used and foamed either individually or in the form of mixtures with one another in the process according to the invention. However, it is also possible and preferred to add other, preferably acidic, detergent ingredients in quantities of 0.1 to 40% by weight, preferably 1 to 15% by weight and more preferably 2 to 10% by weight, based on the weight of the mixture to be foamed, to the anionic surfactant in acid form before foaming.
Besides the xe2x80x9csurfactant acidsxe2x80x9d, the above-mentioned fatty acids, phosphonic acids, polymer acids or partly neutralized polymer acids and xe2x80x9cbuilder acidsxe2x80x9d and xe2x80x9ccomplex builder acidsxe2x80x9d (particulars given hereinafter), either individually or in the form of mixtures, are also suitable acidic reactants for the purposes of the invention. Suitable detergent ingredients, which may be added to the anionic surfactant acid before foaming, are above all acidic detergent ingredients, i.e. for example phosphonic acids which, in neutralized form (phosphonates), are present as incrustation inhibitors in many detergents. According to the invention, (partly neutralized) polymer acids, such as polyacrylic acids for example, may also be used. However, acid-stable ingredients may also be mixed with the anionic surfactant acid before foaming. Suitable ingredients of this type are, for example, so-called minor components which would otherwise have to be added in expensive additional steps, i.e. for example optical brighteners, dyes etc., acid stability having to be tested in each individual case.
Nonionic surfactants may optionally be added to the anionic surfactant in acid form before foaming in quantities of 0.1 to 40% by weight, preferably 1 to 15% by weight and more preferably 2 to 10% by weight, based on the weight of the mixture to be foamed. This addition can improve the physical properties of the anionic surfactant acid foam and can eliminate the need for nonionic surfactants to be subsequently incorporated in the surfactant granules or in the detergent as a whole. The various representatives from the group of nonionic surfactants are described further below.
Concentrated solutions of water-soluble alkalis in water may be used as the highly concentrated, aqueous alkaline components which are also foamed in a separate step. In principle, various alkalis, for example alkanolamines and metal hydroxies, may be used here, although alkali metal hydroxide solutions, preferably sodium hydroxide solutions with concentrations of at least 40% by weight NaOH, preferably at least 50% by weight NaOH and more preferably at least 65% by weight NaOH, based on the aqueous alkaline component to be foamed, are used as the aqueous alkaline component for practical and economic reasons.
The sodium hydroxide concentration of the solution may be increased providing the temperature of the solution is increased at the same time. According to the invention, this is not a problem.
Other ingredients of detergents may also be added to the aqueous alkaline component before foaming. In this case, these other detergent ingredients are added in quantities of preferably 0.1 to 80% by weight, more preferably 10 to 75% by weight and most preferably 25 to 70% by weight, based on the weight of the mixture to be foamed. Through the detergent ingredients to the alkaline component to be foamed, its viscosity can be increased and adapted to the viscosity of the anionic surfactant acid. So far as the subsequent mixing of the two foams produced in the separate steps is concerned, it can be of advantage if the two liquid components to be foamed (surfactant acid and alkali component) have similar and preferably even identical viscosities before foaming. The viscosities are measured in known manner using a Ford cup or spindle viscosimeters, such as the Brookfield viscosimeter. The viscosity of the alkaline component to be foamed may be adjusted with commercially available viscosity adjusters. Besides synthetic polymers, for example polyacrylates, polyurethanes, etc., natural or partly synthetic products such as, for example, xanthans, celluloses and cellulose derivatives, starch and starch derivatives, etc. may also be used. These organic high molecular weight substances or so-called swellng agents, which absorb liquids, swell in the process and finally change into viscous true or colloidal solutions, emanate from the groups of natural polymers, modified natural polymers and fully synthetic polymers. Naturally occurring polymers which may be used as thickeners are, for example, agar agar, carrageen, tragacanth, gum arabic, alginates, pectins, polyoses, guar gum, locust bean gum, starch, dextrins, gelatin and casein. Modified natural materials belong above all to the group of modified starches and celluloses, of which carboxymethyl cellulose and other cellulose ethers, hydroxyethyl cellulose and hydroxypropyl cellulose and also gum ethers are mentioned as examples. A large group of thickeners which are widely used in various fields of application are the fully synthetic polymers, such as polyacrylic and polymethacrylic compounds, vinyl polymers, polycarboxylic acids, polyethers, polyimines, polyamides and polyurethanes.
Thickeners from the classes of compounds mentioned are commercially obtainable and are marketed, for example, under the names of Acusol(copyright) 820 (methacrylic acid (stearyl alcohol-20 EO) ester/acrylic acid copolymer, 30% in water; Rohm and Haas), Dapral(copyright) GT 282 S (alkyl poly-glycol ether; Akzo), Deuterol(copyright) Polymer-11 (dicarboxylic acid copolymer; Schxc3x6ner GmbH), Deuteron(copyright) XG (anionic heteropolysaccharide based on xcex2-D-glucose, D-mannose, D-glucuronic acid; Schxc3x6ner GmbH), Deuteron(copyright) XN (nonionic polysaccharide; Schxc3x6ner GmbH), Dicrylan(copyright) Verdicker-O (ethylene oxide adduct, 50% in water/isopropanol; Pfersse Chemie), EMA(copyright) 81 and EMA(copyright) 91 (ethylene/maleic anhydride copolymer; Monsanto), Verdicker-QR-1001 (polyurethane emulsion, 19-21% in water/diglycol ether; Rohm and Haas), Mirox(copyright)-AM (anionic acrylic acid/acrylate copolymer dispersion, 25% in water; Stockhausen), SER-AD-FX-1100 (hydrophobic urethane polymer; Servo Delden), Shellflo(copyright) S (high molecular weight poly-saccharide, stabilized with formaldehyde; Shell) and Shellflo(copyright) XA (xanthan biopolymer, stabilized with formaldehyde; Shell).
A preferred polymeric thickener is xanthan, a microbial anionic heteropolysaccharide which is produced by Xanthomonas campestris and a few other species under aerobic conditions and which has a molecular weight of 2 to 15 million dalton. Xanthan consists of a chain with xcex2-1,4-glucose (cellulose) with side chains. The structure of the sub-groups consists of glucose, mannose, glucuronic acid, acetate and pyruvate, the number of pyruvate units determining the viscosity of the xanthan. Xanthan may be described by the following formula:
Another viscosity adjuster which has been successfully used is carboxymethyl cellulose (CMC) with which it is even possible, for example, to foam sodium hydroxide in a sufficiently stable manner without using any other additives.
Although it is possible in principle to foam the aqueous alkaline component without any other additives and to combine the resulting foam with the anionic surfactant acid foam to form a neutralizate foam, it is preferred to add foam stabilizers to the aqueous alkali solution before foaming. In preferred processes, surfactants, more particularly anionic and/or nonionic surfactants, preferably ethoxylated alcohols and/or soaps, are added to and mixed with the aqueous alkaline component before foaming.
Preferred nonionic surfactants are alkoxylated, advantageously ethoxylated, more especially primary alcohols preferably containing 8 to 18 carbon atoms and, on average, 1 to 12 moles of ethylene oxide (EO) per mole of alcohol, in which the alcohol radical may be linear or, preferably, methyl-branched in the 2-position or may contain linear and methyl-branched radicals in the form of the mixtures typically present in oxoalcohol radicals. However, alcohol ethoxylates containing linear radicals of alcohols of native origin with 12 to 18 carbon atoms, for example coconut oil, palm oil, tallow fatty or oleyl alcohol, and on average 2 to 8 EO per mole of alcohol are particularly preferred. Preferred ethoxylated alcohols include, for example, C12-14 alcohols containing 3 EO or 4 EO, C9-11 alcohol containing 7 EO, C13-15 alcohols containing 3 EO, 5 EO, 7 EO or 8 EO, C12-18 alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of C12-14 alcohol containing 3 EO and C12-18 alcohol containing 5 EO. The degrees of ethoxylation mentioned represent statistical mean values which, for a special product, can be a whole number or a broken number. Preferred alcohol ethoxylates have a narrow homolog distribution (narrow range ethoxylates, NRE). In addition to these nonionic surfactants, fatty alcohols containing more than 12 EO may also be used, examples including tallow fatty alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.
Another class of preferred nonionic surfactants which may be used either as sole nonionic surfactant or in combination with other nonionic surfactants are alkoxylated, preferably ethoxylated or ethoxylated and propoxylated, fatty acid alkyl esters preferably containing 1 to 4 carbon atoms in the alkyl chain, more especially the fatty acid methyl esters which are described, for example, in Japanese patent application JP 58/217598 or which are preferably produced by the process described in International patent application WO-A-90/13533.
Another class of nonionic surfactants which may be used with advantage are the alkyl polyglycosides (APGs). Suitable alkyl polyglycosides correspond to the general formula RO(G)z where R is a linear or branched, more particularly 2-methyl-branched, saturated or unsaturated aliphatic radical containing 8 to 22 and preferably 12 to 18 carbon atoms and G stands for a glycose unit containing 5 or 6 carbon atoms, preferably glucose. The degree of glycosidation z is between 1.0 and 4.0, preferably between 1.0 and 2.0 and more preferably between 1.1 and 1.4. Linear alkyl polyglucosides, i.e. alkyl polyglycosides in which the polyglycosyl moiety is a glucose unit and the alkyl moiety is an n-alkyl group, are preferably used.
The surfactant granules produced in accordance with the invention may preferably contain alkyl polyglycosides, APG contents in the granules of more than 0.2% by weight, based on the granules as a whole, being preferred. Particularly preferred surfactant granules contain APG in quantities of 0.2 to 10% by weight, preferably 0.2 to 5% by weight and more preferably 0.5 to 3% by weight.
Nonionic surfactants of the amine oxide type, for example N-cocoalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxyethylamine oxide, and the fatty acid alkanolamide type are also suitable. The quantity in which these nonionic surfactants are used is preferably no more than the quantity in which the ethoxylated fatty alcohols are used and, more preferably, no more than half that quantity.
Other suitable surfactants are polyhydroxyfatty acid amides corresponding to formula (II):
in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms, R1 is hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms and [Z] is a linear or branched polyhydroxyalkyl group containing 3 to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known substances which may normally be obtained by reductive amination of a reducing sugar with ammonia, an alkylamine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds corresponding to formula (III):
in which R is a linear or branched alkyl or alkenyl group containing 7 to 12 carbon atoms, R1 is a linear, branched or cyclic alkyl group or an aryl group containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms, C1-4 alkyl or phenyl groups being preferred, and [Z] is a linear polyhydroxyalkyl group, of which the alkyl chain is substituted by at least two hydroxyl groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives of that group.
[Z] is preferably obtained by reductive amination of a reduced sugar, for example glucose, fructose, maltose, lactose, galactose, mannose or xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be converted into the required polyhydroxyfatty acid amides by reaction with fatty acid methyl esters in the presence of an alkoxide as catalyst, for example in accordance with the teaching of International patent application WO-A-95/07331.
Since the alkaline component is intended to neutralize the anionic surfactant acid, but differs considerably therefrom in regard to molecular weight, clear differences in the quantities of foam exist where the pure foams, i.e. the foams containing only the particular active substance (anionic surfactant acid or alkali component), are used so that a relatively large quantity of anionic surfactant acid foam is combined with a relatively small quantity of alkali foam. Although homogeneous, rapid and complete neutralization with no risk of overheating or discoloration is possible by foaming both components, the quantities, i.e. volumes, of anionic surfactant acid and alkali foam can be adapted to one another in order to obtain further optimized process results. This can be done, for example, through the quantity of gaseous medium. Thus, a relatively large quantity of gaseous medium, based on the liquid, can be xe2x80x9cfoamed inxe2x80x9d for foaming the alkali component which leads to an increase in the volume of foam. Another way is to incorporate alkali-stable detergent ingredients in the solution of the alkaline component, nonionic surfactants being particularly suitable because they also have a foam-stabilizing effect. If relatively large quantities of nonionic surfactants, based on the liquid to be foamed, are added to the alkali component in this way before foaming, the foam volumes of the two foams to be combined adapt themselves to one another which leads to optimized process results.
Irrespective of whether the pure anionic surfactant acid, a mixture of anionic surfactant acid and other detergent ingredients, the pure aqueous alkali solution or an aqueous alkali solution containing nonionic surfactant, for example, is foamed, the gaseous medium is used in quantities of at least 20% by volume, based on the amount of liquid to be foamed, for generating foam from the anionic surfactant in its acid form and the highly concentrated aqueous alkaline component.
Accordingly, if, for example, one liter of a highly concentrated ABS acid is to be foamed, at least 200 ml of gaseous medium is preferably used for foaming. In preferred processes, the quantity of gaseous medium is well above that value so that preferred processes are characterized in that the amount of gas used for foaming makes up one to three hundred times, preferably five to two hundred times and more preferably ten to one hundred times the volume of liquid to be foamed. As mentioned in the foregoing, air is preferably used as the gaseous medium. However, other gases or gas mixtures may be used for foaming. For example, pure oxygen or the air to be used for foaming may advantageously be passed through an ozonizer before the gas is used for foam generation. Gas mixtures containing, for example, 0.1 to 4% by weight of ozone may be prepared in this way. The ozone content of the foaming gas then leads to the oxidative destruction of unwanted constituents in the liquids to be foamed. In the case of partly discolored anionic surfactant acids in particular, a distinct lightening effect can be obtained by adding ozone.
Accordingly, 1 to 300 liters, preferably 5 to 200 liters and more preferably 10 to 100 liters of air are preferably used for foaming the liter of ABS acid mentioned by way of example in the foregoing.
The liquids to be foamed in the individual steps may be at room temperature before foaming, although foaming may also be carried out at elevated temperature. Preferred processes are characterized in that the liquid components to be foamed have temperatures before foaming of 20 to 100xc2x0 C., preferably in the range from 30 to 90xc2x0 C. and more preferably in the range from 50 to 75xc2x0 C.
The two foams produced in the individual steps are then combined. A stable neutralizate foam is formed with partial release of the previously trapped gas providing the volumetric gas flow rate is very much larger than the flow of liquid (continuous process). This excess of gas supports the transport of the foam, dissipation of the heat of reaction generated and the discharge of excess water which comes from raw materials and the neutralization reaction. Overly elevated temperatures lead to unwanted brown discoloration of the neutralizate foam which should be avoided. Accordingly, in preferred variants of the process according to the invention, the neutralizate foam has temperatures below 115xc2x0 C., preferably between 50 and 95xc2x0 C. and more preferably between 70 and 90xc2x0 C.
The neutralizate foam formed, which is used as a granulation aid in the next step of the process, can be characterized by other physical parameters. For example, the neutralizate foam preferably has a density of at most 0.80 gcmxe2x88x923, preferably in the range from 0.10 to 0.60 gcmxe2x88x923 and more preferably in the range from 0.30 to 0.55 gcmxe2x88x923. In another preferred embodiment, the neutralizate foam has mean pore sizes below 10 mm, preferably below 5 mm and more preferably below 2 mm. The mean pore size is calculated from the sum total of all pore sizes (pore diameters) which is divided by the number of pores and may be determined, for example, by photographic methods.
The above-mentioned physical parameters of temperature, density and mean pore size characterize the neutralizate foam at the time it is formed. However, the process is preferably controlled in such a way that the neutralizate foam satisfies the above-mentioned criteria even at the time it is introduced into the mixer.
Process control strategies in which the foam satisfies only one or two of the criteria mentioned when introduced into the mixer are possible, although both the temperature and the density and pore size preferably lie within the ranges mentioned when the foam enters the mixer.
After its formation, the neutralizate foam is applied to a bed of solids initially introduced into a mixer where it serves as a granulation aid. This step of the process may be carried out in various mixers and granulators. In one suitable mixer and granulator, for example an Eirich mixer, a Lxc3x6dige mixer, for example a Lxc3x6dige plowshare mixer, or a Schugi mixer, a solid bed is initially introduced at peripheral speeds of the mixing tools of, preferably, 2 to 7 m/s (plowshare mixer) or 3 to 50 m/s (Eirich, Schugi), more particularly between 5 and 20 m/s, and subsequently granulated in the presence of the neutralizate foam. At the same time, a predetermined particle size of the granules may be established in known manner. The granulation and mixing process takes only a very short time, for example about 0.5 to 10 minutes and, more particularly, about 0.5 to 5 minutes (Eirich mixer, Lxc3x6dige mixer), to homogenize the mixture to form the flowable granules. By contrast, in a Schugi mixer, a residence time of 0.5 to 10 seconds is normally sufficient to obtain flowable granules. Mixers suitable for carrying out this step of the process are, for example, Series R or RV Eirich(copyright) mixers (trademarks of Maschinenfabrik Gustav Eirich, Hardheim), the Schugi(copyright) Flexomix, Fukae(copyright) FS-G mixers (trademarks of Fukae Powtech, Kogyo Co., Japan), Lxc3x6dige(copyright) FM, KM and CB mixers (trademarks of Lxc3x6dige Maschinenbau GmbH, Paderborn) and Series T or K-T Drais(copyright) mixers (trademarks of Drais-Werke GmbH, Mannheim).
The solid bed introduced into the mixer may contain all the substances used in detergents. In this way, ready-to-use detergents can be produced by the process according to the invention. Normally, however, certain detergent ingredients are not included in the granulation process in order to prevent these ingredients from entering into unwanted reactions with one another under the mechanical influence of the granulating tools. Ingredients which are normally added to the surfactant granules in a subsequent step, i.e. after the granulation process, include, for example bleaching agents, bleach activators, foam inhibitors and enzymes.
Besides the surfactant, the surfactant granules produced in accordance with the invention preferably contain substances which function as active substances in the final detergent. In preferred processes, therefore, the bed of solids introduced into the mixer contains one or more substances from the group of builders, more especially alkali metal carbonates, sulfates and silicates, zeolites and polymers.
Besides the detersive substances, builders are the most important ingredients of detergents. In the process according to the invention, any of the builders typically used in detergents may be present in the solid bed, i.e. in particular zeolites, silicates, carbonates, organic co-builders andxe2x80x94providing there are no ecological objections to their usexe2x80x94also phosphates.
Suitable crystalline layer-form sodium silicates correspond to the general formula Na2MSixO2x+1. H2O, where M is sodium or hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20, preferred values for x being 2, 3 or 4. Crystalline layer silicates such as these are described, for example, in European patent application EP-A-0 164 514. Preferred crystalline layer silicates corresponding to the above formula are those in which M is sodium and x assumes the value 2 or 3. Both xcex2- and xcex4-sodium disilicates Na2Si2O5. y H2O are particularly preferred, xcex2-sodium disilicate being obtainable, for example, by the process described in International patent application WO-A- 91/08171.
Other useful builders are amorphous sodium silicates with a modulus (Na2O:SiO2 ratio) of 1:2 to 1:3.3, preferably 1:2 to 1:2.8 and more preferably 1:2 to 1:2.6 which dissolve with delay and exhibit multiple wash cycle properties. The delay in dissolution in relation to conventional amorphous sodium silicates can have been obtained in various ways, for example by surface treatment, compounding, compacting or by overdrying. In the context of the invention, the term xe2x80x9camorphousxe2x80x9d is also understood to encompass xe2x80x9cX-ray amorphousxe2x80x9d. In other words, the silicates do not produce any of the sharp X-ray reflexes typical of crystalline substances in X-ray diffraction experiments, but at best one or more maxima of the scattered X-radiation which have a width of several degrees of the diffraction angle. However, particularly good builder properties may even be achieved where the silicate particles produce crooked or even sharp diffraction maxima in electron diffraction experiments. This may be interpreted to mean that the products have microcrystalline regions between 10 and a few hundred nm in size, values of up to at most 50 nm and, more particularly, up to at most 20 nm being preferred. So-called X-ray amorphous silicates such as these, which also dissolve with delay in relation to conventional waterglasses, are described for example in German patent application DE-A-44 00 024. Compacted amorphous silicates, compounded amorphous silicates and overdried X-ray-amorphous silicates are particularly preferred.
The finely crystalline, synthetic zeolite containing combined water used in accordance with the invention is preferably zeolite A and/or zeolite P. Zeolite MAP(copyright) (Crosfield) is a particularly preferred P-type zeolite. However, zeolite X and mixtures of A, X and/or P are also suitable. According to the invention, it is also possible to use, for example, a commercially obtainable co-crystallizate of zeolite X and zeolite A (ca. 80% by weight zeolite X) which is marketed by CONDEA Augusta S.p.A. under the name of VEGOGOND AX(copyright) and which may be described by the following formula:
nNa2O.(1-n)K2O.Al2O3.(2-2.5)SiO2.(3.5-5.5)H2O
Suitable zeolites have a mean particle size of less than 10 xcexcm (volume distribution, as measured by the Coulter Counter Method) and contain preferably 18 to 22% by weight and more preferably 20 to 22% by weight of bound water.
The generally known phosphates may of course also be used as builders providing their use should not be avoided on ecological grounds. The sodium salts of the orthophosphates, the pyrophosphates and, in particular, the tripolyphosphates are particularly suitable.
Useful organic builders are, for example, the polycarboxylic acids usable in the form of their sodium salts, such as citric acid, adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids, aminocarboxylic acids, nitrilotriacetic acid (NTA), providing there are no ecological objections to its use, and mixtures of these acids. Preferred salts are the salts of the polycarboxylic acids, such as citric acid, adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids and mixtures thereof.
Surfactant granules are foamed by the addition of the neutralizate foam in conjunction with the effect of the mixing tools. Processes according to the invention in which the neutralizate foam is added to the solid bed initially introduced into the mixer in a ratio by weight of foam to solid of 1:100 to 9:1, preferably 1:20 to 10:1 and more preferably 1:10 to 1:1 are preferred. Optimal granulation results are obtained with the preferred quantities of granulation aid (neutralizate foam).
The process according to the invention is variable over a broad range in regard to the choice of the ingredients to be used and their concentrations. Nevertheless, it is preferred in accordance with the invention to produce surfactant granules which have surfactant contents above 10% by weight, preferably above 15% by weight and more preferably above 20% by weight, based on the granules, and bulk densities above 600 g/l, preferably above 700 g/l and more preferably above 800 g/l.
The granulation process according to the invention may be carried out in such a way that particles with a predetermined size distribution are obtained. Processes according to the invention in which the surfactant granules have a particle size distribution where at least 50% by weight, preferably at least 60% by weight and more preferably at least 70% by weight of the particles are between 400 and 1600 xcexcm in size are preferred.
The surfactant granules produced by the process according to the invention may be subsequently mixed with other detergent ingredients to form the end product. However, these ingredients may optionally be directly incorporated in the surfactant granules through the solid bed or through the neutralizate foam and are described hereinafter:
Besides the components mentioned (surfactant and builders), typical detergent ingredients from the group of bleaching agents, bleach activators, enzymes, pH regulators, perfumes, perfume carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors are particularly important.
Among the compounds yielding H2O2 in water which serve as bleaching agents, sodium perborate tetrahydrate and sodium perborate monohydrate are particularly important. Other useful bleaching agents are, for example, sodium percarbonate, peroxypyrophosphates, citrate perhydrates and H2O2-yielding peracidic salts or peracids, such as perbenzoates, peroxophthalates, diperazelaic acid, phthaloiminoperacid or diperdodecane dioic acid. Typical organic bleaching agents are diacyl peroxides, such as dibenzoyl peroxide for example. Other typical organic bleaching agents are the peroxy acids, of which alkyl peroxy acids and aryl peroxy acids are particularly mentioned as examples. Preferred representatives are (a) peroxybenzoic acid and ring-substituted derivatives thereof, such as alkyl peroxybenzoic acids, but also peroxy-xcex1-naphthoic acid and magnesium monoperphthalate, (b) aliphatic or substituted aliphatic peroxy acids, such as peroxylauric acid, peroxystearic acid, xcex5-phthalimidoperoxycaproic acid [phthaloiminoperoxyhexanoic acid (PAP)], o-carboxybenzamidoperoxycaproic acid, N-nonenylamidoperadipic acid and N-nonenylamidopersuccinates. and (c) aliphatic and araliphatic peroxydicarboxylic acids, such as 1,12-diperoxycarboxylic acid, 1,9-diperoxyazelaic acid, diperoxysebacic acid, diperoxybrassylic acid, diperoxyphthalic acids, 2-decyldiperoxybutane-1,4-dioic acid, N,N-terephthaloyl-di(6-aminopercaproic acid).
Other suitable bleaching agents in machine dishwashing compositions are chlorine- and bromine-releasing substances. Suitable chlorine- or bromine-releasing materials are, for example, heterocyclic N-bromamides and N-chloramides, for example trichloroisocyanuric acid, tribromoisocyanuric acid, dibromoisocyanuric acid and/or dichloroisocyanuric acid (DICA) and/or salts thereof with cations, such as potassium and sodium. Hydantoin compounds, such as 1,3-dichloro-5,5-dimethyl hydantoin, are also suitable.
In order to obtain an improved bleaching effect where washing is carried out at temperatures of 60xc2x0 C. or lower, bleach activators may be incorporated in the surfactant mixtures according to the invention. The bleach activators may be compounds which form aliphatic peroxocarboxylic acids containing preferably 1 to 10 carbon atoms and more preferably 2 to 4 carbon atoms and/or optionally substituted perbenzoic acid under perhydrolysis conditions. Substances bearing O- and/or N-acyl groups with the number of carbon atoms mentioned and/or optionally substituted benzoyl groups are suitable. Preferred bleach activators are polyacylated alkylenediamines, more particularly tetraacetyl ethylenediamine (TAED), acylated triazine derivatives, more particularly 1,5-diacetyl-2,4-dioxohexa-hydro-1,3,5-triazine (DADHT), acylated glycolurils, more particularly tetraacetyl glycoluril (TAGU), N-acylimides, more particularly N-nonanoyl succinimide (NOSI), acylated phenol sulfonates, more particularly n-nonanoyl or isononanoyloxybenzenesulfonate (n- or iso-NOBS), carboxylic anhydrides, more particularly phthalic anhydride, acylated polyhydric alcohols, more particularly triacetin, ethylene glycol diacetate and 2,5-diacetoxy-2,5-dihydrofuran.
In addition to or instead of the conventional bleach activators mentioned above, so-called bleach catalysts may also be incorporated in the surfactant mixtures according to the invention. Bleach catalysts are bleach-boosting transition metal salts or transition metal complexes such as, for example, manganese-, iron-, cobalt-, ruthenium- or molybdenum-salen complexes or carbonyl complexes. Manganese, iron, cobalt, ruthenium, molybdenum, titanium, vanadium and copper complexes with nitrogen-containing tripod ligands and cobalt-, iron-, copper- and ruthenium-amine complexes may also be used as bleach catalysts.
Suitable enzymes are those from the class of proteases, lipases, amylases, cellulases or mixtures thereof. Enzymes obtained from bacterial strains or fungi, such as Bacillus subtilis, Bacillus licheniformis and Streptomyces griseus, are particularly suitable. Proteases of the subtilisin type are preferred, proteases obtained from Bacillus lentus being particularly preferred. Enzyme mixtures, for example of protease and amylase or protease and lipase or protease and cellulase or of cellulase and lipase or of protease, amylase and lipase or of protease, lipase and cellulase, but especially cellulase-containing mixtures, are of particular interest. Peroxidases or oxidases have also proved to be suitable in some cases. The enzymes may be adsorbed to supports and/or encapsulated in shell-forming substances to protect them against premature decomposition.
In addition, the detergents according to the invention may also contain components with a positive effect on the removability of oil and fats from textiles by washing (so-called soil repellents). This effect becomes particularly clear when a textile which has already been repeatedly washed with a detergent according to the invention containing this oil- and fat-dissolving component is soiled. Preferred oil- and fat-dissolving components include, for example, nonionic cellulose ethers, such as methyl cellulose and methyl hydroxypropyl cellulose containing 15 to 30% by weight of methoxyl groups and 1 to 15% by weight of hydroxypropoxyl groups, based on the nonionic cellulose ether, and the polymers of phthalic acid and/or terephthalic acid known from the prior art or derivatives thereof, more particularly polymers of ethylene terephthalates and/or polyethylene glycol terephthalates or anionically and/or nonionically modified derivatives thereof. Of these, the sulfonated derivatives of phthalic acid and terephthalic acid polymers are particularly preferred.
The detergents may contain derivatives of diaminostilbenedisulfonic acid or alkali metal salts thereof as optical brighteners. Suitable optical brighteners are, for example, salts of 4,4xe2x80x2-bis-(2-anilino-4-morpholino-1,3,5-triazinyl-6-amino)-stilbene-2,2xe2x80x2-disulfonic acid or compounds of similar composition which contain a diethanolamino group, a methylamino group, an anilino group or a 2-methoxyethylamino group instead of the morpholino group. Brighteners of the substituted diphenyl styryl type, for example alkali metal salts of 4,4xe2x80x2-bis-(2-sulfostyryl)-diphenyl, 4,4xe2x80x2-bis-(4-chloro-3-sulfostyryl)-diphenyl or 4-(4-chlorostyryl)4xe2x80x2-(2-sulfostyryl)-diphenyl, may also be present. Mixtures of the brighteners mentioned above may also be used.
Dyes and perfumes are added to the detergents according to the invention to improve the aesthetic impression created by the products and to provide the consumer not only with the required washing performance but also with a visually and sensorially xe2x80x9ctypical and unmistakablexe2x80x9d product. Suitable perfume oils or perfumes include individual perfume compounds, for example synthetic products of the ester, ether, aldehyde, ketone, alcohol and hydrocarbon type. Perfume compounds of the ester type are, for example, benzyl acetate, phenoxyethyl isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl acetate, dimethyl benzyl carbinyl acetate, phenyl ethyl acetate, linalyl benzoate, benzyl formate, ethyl methyl phenyl glycinate, allyl cyclohexyl propionate, styrallyl propionate and benzyl salicylate. The ethers include, for example, benzyl ethyl ether; the aldehydes include, for example, the linear alkanals containing 8 to 18 carbon atoms, citral, citronellal, citronellyloxyacetaldehyde, cyclamen aldehyde, hydroxycitronellal, lilial and bourgeonal; the ketones include, for example, the ionones, xcex1-isomethyl ionone and methyl cedryl ketone; the alcohols include anethol, citronellol, eugenol, geraniol, linalool, phenyl ethyl alcohol and terpineol and the hydrocarbons include, above all, the terpenes, such as limonene and pinene. However, mixtures of various perfumes which together produce an attractive perfume note are preferably used. Perfume oils such as these may also contain natural perfume mixtures obtainable from vegetable sources, for example pine, citrus, jasmine, patchouli, rose or ylang-ylang oil. Also suitable are clary oil, camomile oil, nettle oil, melissa oil, mint oil, cinnamon leaf oil, lime blossom oil, juniper berry oil, vetiver oil, olibanum oil, galbanum oil and labdanum oil and orange blossom oil, neroli oil, orange peel oil and sandalwood oil.
The dye content of detergents is normally below 0.01% by weight whereas perfumes can make up as much as 2% by weight of the formulation as a whole.
The perfumes may be directly incorporated in the detergents, although it can also be of advantage to apply the perfumes to carriers which strengthen the adhesion of the perfume to the laundry and which provide the fabrics with a long-lasting fragrance through the slower release of perfume. Cyclodextrins, for example, have proved to be suitable carriers. In addition, the cyclodextrin/perfume complexes may be coated with other auxiliaries.
In order to improve their aesthetic impression, detergents may be colored with suitable dyes. Preferred dyes, which are not difficult for the expert to select, are characterized by high storage stability and stability to the other ingredients of the detergents and to light and by no pronounced substantivity towards textile fibers so as not to color them.
The neutralizate foam produced in the process according to the invention and its use as a granulation aid have never been described in the prior-art literature. Accordingly, the present invention also relates to a neutralizate foam obtainable by combining an anionic surfactant in its acid form foamed with a gaseous medium and a highly concentrated aqueous alkaline component foamed with a gaseous medium, characterized in that the foam has mean pore sizes below 10 mm, preferably below 5 mm and more preferably below 2 mm.
As already emphasized in the description of the process according to the invention, a neutralizate foam in which the gaseous medium makes up at least 20% by volume, based on the foamed volume of liquid is preferred. In one particularly preferred neutralizate foam, the gaseous medium makes up between one and three hundred times, preferably between five and two hundred times and more preferably between ten and one hundred times the volume of foamed liquid.
So far as the ingredients of the foams produced in separate steps are concerned, reference is again made to the description of preferred embodiments of the process according to the invention. Preferred neutralizate foams are obtained by combining a foam of an anionic surfactant in its acid form, which optionally contains other, preferably acidic, detergent ingredients, and a foam of an aqueous alkali metal hydroxide, preferably sodium hydroxide, solution optionally containing other detergent ingredients, more particularly nonionic surfactants. The neutralizate foam was preferably obtained by combining an anionic surfactant acid foam and a sodium hydroxide foam containing nonionic surfactant, the sodium hydroxide foam containing 5 to 80% by weight, preferably 10 to 75% by weight and more preferably 25 to 70% by weight of nonionic surfactant, based on the weight of the sodium hydroxide foam. Another preferred neutralizate foam is obtained by combining a foam of an anionic surfactant in its acid form, which contains nonionic surfactants in quantities of 0.1 to 10% by weight, preferably 0.5 to 7.5% by weight and more preferably 1 to 5% by weight, based on the weight of the anionic surfactant acid foam, and a foam of an aqueous alkali metal hydroxide, preferably sodium hydroxide, solution optionally containing other detergent ingredients, more particularly nonionic surfactants.
The neutralizate foam according to the invention preferably has a high surfactant content. Neutralizate foams with surfactant contents of 20 to 99% by weight, preferably 60 to 95% by weight and more preferably 70 to 90% by weight, based on the weight of the foam, are preferred.
The present invention also relates to the use of the neutralizate foams according to the invention as granulation aids in the production of surfactant granules. So far as the quantity ratios between granulation aid (neutralizate foam) and solid bed, the mixer to be used and the ingredients suitable for use in the solid bed are concerned, reference is made to the foregoing observations.