A hotmelt adhesive is provided in the form of a granulate comprising at least one compact outer layer (shell) made up of at least one component which is not pressure sensitive up to 45xc2x0 C. and which surrounds a core made up of other components of the hotmelt adhesive. The hotmelt adhesive granulates are free flowing even after storage at a high temperature under pressure.

This invention relates to a pressure-sensitive hotmelt adhesive in the form of granules having at least one outer layer of at least one non-pressure-sensitive adhesive component of the pressure-sensitive hotmelt adhesive and a core of the other components of the pressure-sensitive hotmelt adhesive surrounded by said outer layer.
Coated granules such as these of pressure-sensitive adhesives to be applied from the melt are known. Thus, EP 531 927 describes a dimensionally stable pressure-sensitive hotmelt adhesive containing resins, elastomers and plasticizers as principal constituents. It is in the form of pellets or granules of which the surface consists of adhering powder of a meltable elastomer suited to the formulation. The powder-form elastomer preferably compensates for a small amount of the elastomer in the hotmelt adhesive of the core. The powdered granules are produced by depositing drops of the molten hotmelt adhesive onto a powder-covered conveyor belt and thus covering them with powder. The disadvantage of this is that the powder only affords the surface partial protection against unwanted sticking. This is because the granules show a tendency towards cold flow in the event of prolonged storage and block in the process, i.e. no longer flow freely.
Similar disadvantages arise with the free-flowing granules according to DE 20 34 038. These particles with a diameter of preferably 1 to 30 mm consist of an adhesive, dimensionally stable material in the core and a layer of powder on its surface. The particles preferably consist of an adhesive thermoplastic, more particularly an atactic polyolefin such as, for example, polybutene-1 or PP, and are covered with a powder layer of a special or similar kind of a hard thermoplastic, for example an isotactic polyolefin, such as polybutene-1. For their production, the particles to be powdered are formed by extrusion and cutting and are powdered in a fluidized bed simultaneously with the cooling of the particles obtained from the hot melt. The powder is solid. The particles to be powdered may be in an almost still liquid state or may be cooled to such an extent that they are only just tacky.
U.S. Pat. No. 4,359,492 describes the coating of pellets of tacky elastomeric materials with powder-form materials. The elastomeric materials are preferably pressure-sensitive adhesives while the powder-form materials are crumb-form polymers with a softening temperature of at least 95xc2x0 C.
EP 294 141 describes coated pellets of synthetic polymers, for example EVA coated with PE. They are produced by
a) extruding a first synthetic polymer to form a strand or pellets,
b) cutting the strand while it is still molten into pellets,
c) powdering the pellets with powder of a second polymer, the powder melting under the effect of the high temperature of the pellets and forming a layer,
d) cooling the coated pellets.
The powder may be heated to 30-40xc2x0 C. before application. The coated pellets do not stick to one another. The disadvantage of the described coated pellets is that the surrounding layer is not continuous, allowing parts of the melt to leak out (xe2x80x9cbleedingxe2x80x9d).
WO 96100747 describes a process for coating hotmelt adhesives which essentially comprises the following steps:
a) extruding the hotmelt adhesive through a suitable nozzle,
b) spraying the surface of the extruded hotmelt adhesive with a molten film-forming polymeric material of relatively low molecular weight or with a polymer formulation, the coating material having no significant effect on the properties of the adhesive composition after it has been remelted,
c) heating the surface of the coated adhesive so that the film-forming polymer is remelted and forms a continuous coating and
d) cooling the adhesive thus coated to temperatures suitable for handling.
The extruded hotmelt adhesive can be cooled after its extrusion and before its spray coating. However, it is preferably coated directly after extrusion. Finally, the coated extrudate is cut up. The disadvantage of this process and the resulting products is that the cut faces are not coated. Accordingly, the portions are not free-flowing.
EP 14 467 describes a process for the underwater granulation of ethylene copolymers, for example ethylene/vinyl acetate copolymers, in which 1 to 1,000 ppm of a surfactant are said to be added to the water to reduce agglomeration. The agglomeration temperature is thus increased by at least 10xc2x0 C.
WO 97119582 describes a thermoplastic polymer composition with a non-tacky surface in the form of pellets of which 97 to 99.9% by weight consists of a pressure-sensitive adhesive and 0.1 to 3% by weight of a pelleting material which surrounds the thermoplastic composition. Materials from the group consisting of PE wax, modified PE wax, PA wax and stearamide wax and mixtures thereof are specifically mentioned as pelleting materials. They are in powder form. The document in question also mentions underwater granulation as a process for producing the tacky hotmelt adhesive pellets from which pellets with non-tacky surfaces which do not block are produced using the pelleting material. Production comprises the following steps:
producing a melt mixture from the starting components,
forming pellets with the aid of nozzles,
solidifying the pellets by cooling,
applying the pelleting material at certain places during the pelleting process and
drying.
The pelleting material is said to be applied during each extruder pass. It is added to the cooling medium. Its concentration in the water is between 0.1 and 3% by weight.
The disclosed process does not lead to the described products. More particularly, it does not lead to free-flowing granules after storage for 3 months at 30xc2x0 C. for a layer thickness of the granules of 15 to 30 cm. The granules stick to one another and to the pack.
EP 156 274 describes a water-based release agent for the temporary antiadhesive surface finishing of tacky pellets, granules etc. which consists of a 0.5 to 25% by weight solution or dispersion of an at least difunctional aliphatic alcohol containing 3 to 7 carbon atoms and/or an at least trifunctional aliphatic hydroxycarboxylic acid or water-soluble salts thereof. 0.2 to 15% by weight of water-insoluble salts of a C12xe2x88x9236 aliphatic or alicyclic mono- or dicarboxylic acid may be additionally used. The release agent is intended above all for the antiadhesive finishing of granules of hotmelt adhesives. To this end, the granules are treated with the solution or suspension at 18 to 22xc2x0 C. and, after the solution or suspension has been removed under suction, the granules are dried for 15 minutes with warm air having a temperature of 30xc2x0 C. The granules then contain 0.3 to 0.5% by weight of active substance. They can be protected. The release effect remains in tact for at least 3 months at 25xc2x0 C. However, it is not sufficient for the storage temperature and the storage pressure to be increased. In addition, the finishing process is difficult on account of the agglomeration of the as yet non-finished granules.
German utility model 9116662.4 describes a packed adhesive composition where a quantity of substantially homogeneous separate portions of the adhesive composition is completely surrounded by a net or a bag of a plastic packaging material, preferably by a welded bag. The separate portions are preferably externally coated with a separating antiadhesive substance. Despite this antiadhesive substance, the portions stick to one another because of cracks in or flaking of the coating material, particularly after prolonged storage at varying temperatures. The surfaces of the individual adhesive portions are thus exposed and adhere to one another. This makes the hotmelt adhesives difficult to handle and, above all, to dose. To avoid this disadvantage, the adhesive portionsxe2x80x94depite their antiadhesive coatingxe2x80x94are packed in a bag which is then handled. The bag preferably contains 100 to 4,000 individual portions. The disadvantage of welding inadequately coated portions in a bag is that the entrapped air prevents the bag from being immersed in melting tanks. It floats on the adhesive melt which lengthens the melting time. Alternatively, larger melting units than actually necessary have to be used.
Against the background of this prior art, the problem addressed by the present invention was to provide a pressure-sensitive hotmelt adhesive which would still be easy to handle and, more particularly, easy to dose even after prolonged storage at varying temperatures and under high pressure. This would also include avoidance of the particles sticking to one another and to the pack. Rapid melting would also be possible. The adhesive properties would not of course be adversely affected by the antiadhesive finish.
The solution to this problem is defined in the claims and consists essentially in the formation around a granule core of a complete compact coating of material of a similar type.
Accordingly, the present invention relates primarily to a hotmelt adhesive in the form of granules having at least one compact outer layer (shell) of at least one adhesive component of the pressure-sensitive hotmelt adhesive which is not pressure-sensitive up to 40xc2x0 C. and a core of the other components of the pressure-sensitive hotmelt adhesive surrounded by said outer layer.
The outer layers surround the core so completely, i.e. 90% and more particularly 99% of the core surface is surrounded, that the granules remain free-flowing. This degree of coverage is determined by the surface evaluation of micrographs.
Free-flowing means that the granules xe2x80x9cflowxe2x80x9d through a 5 cm diameter opening under their own weight, even after storage for 4 months and at least 2 months at temperature of xe2x88x9210 to +40xc2x0 C. in a weekly rotation and under the pressure generated by a filling level of 30 cm.
The granules are 1 to 30 mm and preferably 4 to 10 mm in diameter. The granule size is determined by sieve analysis. The granules are preferably spherical in shape. However, they may also be elliptical.
It is surprising that free flow even after storage under extreme conditions is achieved despite the fact that the outer layers make up only a small percentage by weight of the hotmelt adhesive as a whole. The percentage by weight of the outer layers, based on the hotmelt adhesive as a whole, is between 0.5 and 10% by weight, preferably from 1 to 5% by weight and more preferably from 1 to 2% by weight. The percentage by weight is determined by statistical weighing.
The outer layers have a melting point to ASTM D 3461 or a softening temperature as determined by the R+B method of below 130xc2x0 C., above all below 120xc2x0 C. and more particularly below 110xc2x0 C. However, it is generally above 95xc2x0 C. and, more particularly, is 115xc2x0 C. The measuring methods are carried out to ASTM D 3461.
The outer layers consist at least partly of a material which is also present in the core. Mixtures of materials may of course also be used although tackifiers should preferably be avoided. The outer layer may also consist of a low molecular weight, non-brittle raw material for the production of the pressure-sensitive hotmelt adhesive, preferably of a plasticizer.
However, more than 50% by weight of the outermost layer consists of at least one polymer, preferably a thermoplastic elastomer, more particularly from the group consisting of ethylene-based polymers, such as ethylene/vinyl acetate, ethylene acrylate, ethylene methacrylate, ethylene methyl acrylate, ethylene methyl methacrylate, high-density and low-density polyethylene, polyethylene mixtures and chemically modified polyethylene, copolymers of ethylene and di-unsaturated monomers, polybutadiene rubber, polyesters, such as polyethylene terephthalate, polybutylene terephthalate; thermoplastic polycarbonates, atactic poly-xcex1-olefins, including atactic polypropylene and others; thermoplastic polyacrylamides, homopolymers and copolymersxe2x80x94more especially block copolymersxe2x80x94of acrylonitrile and other monomers, such as butadiene and styrene; polymethyl pentene, polyphenylene sulfide, polyurethanes; styrene/acrylonitrile, styrene/butadiene rubbers, polyphenylene sulfide, elastomers of the A-B-, A-B-A-, A-(B-A)n-B- and (A-B)n-Y-block copolymer type, in which the A comprises an aromatic polyvinyl block, above all styrene, while the B block comprises a rubber middle block, above all butadiene or isoprene, which may be partly hydrogenated, and mixtures of these substances.
It is appropriate to select a composition for the outer layer which, together with the core, corresponds to the required composition that would be used even without a coating. In other words, the type and quantity of the coating material corresponds to the difference between the packaged composition and the desired adhesive composition. Accordingly, the granule layer may consist of a hotmelt adhesive composition which, together with the granule core, gives a pressure-sensitive hotmelt adhesive after melting. In this case, it is not possible for the coating material to have any adverse effect whatever on the properties of the adhesive composition.
An ethylene/vinyl acetate copolymer with a vinyl acetate content of 10 to 45%, more particularly 15 to 30%, and a softening point of 80 to 130xc2x0 C. is proposed as a particularly suitable coating material. It has a melt index of about 1 to 2,500 and more particularly in the range from about 6 to 400, as measured to ASTM D 1238/90 b.
Thermoplastic elastomers in particular, such as styrene block copolymers, are eminently suitable for producing the coating. The same also applies to polyisoprene.
Should the melting or softening temperature of the polymers be too high, it can be reduced by mixing with other adhesive components, for example with waxes or plasticizers. The mixture should not of course assume the properties of a pressure-sensitive adhesive, nor should it lead to blocking.
The coating material may bexe2x80x94in part at leastxe2x80x94a plastic or a plastic composition which is not a constituent of the hotmelt adhesive, but which is suitable for simultaneous melting with the contents of the container and is miscible therewith in the molten state without the properties of the adhesive composition being adversely influenced to any significant extent by the mixing process. The plastic or plastic composition in question may be selected, above all, from known antiadhesive substances, for example polyethylene, preferably polyethylene powder.
The granules may also be made up of several layers, the tackifier generally making up the core which is surrounded by a first layer of a mixture of plasticizers and fillers and by a second layer of polymers and oxidants. The outer layer may also consist of a mixture of polymers and plasticizers in order to reduce the melting temperature or softening temperature in this way. However, the plasticizer has to be carefully selected to avoid unwanted migration into the outer layer.
The coating component is liquid during application and is preferably a water-free melt. However, a high-solids aqueous dispersion may also be used. An actual example of a melt is polyethylene wax or EVA while actual examples of an aqueous dispersion include a polyethylene emulsion, more particularly an emulsion of a Fischer-Tropsch wax containing a polyester film former, and polyvinyl acetate- or EVA-based emulsions. The aqueous dispersion is a fine-droplet dispersion with a mean droplet diameter of 0.5 to 12 xcexcm.
From the perspective of the type and quantity of the individual components, the material of the granule core corresponds to a typical hotmelt adhesive composition, more particularly a pressure-sensitive hotmelt adhesive composition, provided that it is compatible with the material selected for the coating so that the coating can readily be dissolved by the user in the molten hotmelt adhesive. The hotmelt adhesive systems comprise a number of basic polymers which are mixed with other ingredients, such as plasticizers, tackifiers, stabilizers, waxes and extenders, to form the adhesive. The basic polymers largely determine the properties of the adhesive layer in regard to adhesion, strength and temperature behavior. The most important basic polymers are polyolefins, polyamides and polyurethanes.
Olefinic materials of the outer layer, such as polyethylene and poly(ethylene-co-vinyl acetate), are compatible with aliphatic and aromatic hydrocarbon hotmelt adhesives. Commercially available hotmelt adhesive compositions of this type contain hotmelt adhesives based on ethylene/vinyl acetate copolymer and on amorphous propylene-xcex1-olefin (APAO). Any hotmelt adhesives based on styrene/butadiene/styrene(SBS) copolymer-A-B-A-B-A-multiblock, structural hotmelts based on radial styrene/butadiene/styrene, (SB)n copolymers and structural hotmelts based on styrene/isoprene/styrene (SIS) and -A-B-A- block copolymers may also be present. Other polymers are polybutene, ethylene/acrylate, ethylene/CO and propylene/hexene copolymers.
Polyamide-based hotmelt adhesives may also be packaged by the process according to the invention, a container of a corresponding polyamide which is compatible with the hotmelt adhesive during the simultaneous melting process being preferred. Suitable polyamides are PA 6.6, PA 6.10, PA 6 and above all polyamides of diamines and dimerized fatty acids, more particularly of ethylenediamine and dimerized linoleic acid. Copolymers, for example polyamide/EVA copolymers, polyamide/siloxane copolymers, polyester amides, polyether amides, polyester amide imides and polyether ester amides, are of course also suitable.
For example, the present invention may also be applied to hotmelt adhesives which have been made from polymers and copolymers of synthetic resins, rubbers, polyethylene, polypropylene, polyurethane, polyacrylate, polyvinyl acetate, ethylene/vinyl acetate copolymers and polyvinyl alcohol.
The present invention is of particular advantage for hotmelt adhesives with serious handling problems, for example for the above-mentioned pressure-sensitive hotmelt adhesives which are tacky even at room temperature.
Special examples are hotmelt adhesives made from the following components:
1) elastic polymers, such as block copolymers, for example styrene/butadiene, styrene/butadiene/styrene, styrene/isoprene/styrene, styrene/ethylene/butylene/styrene, styrene/ethylene/propylene/styrene;
2) ethylene/vinyl acetate polymers, other ethylene esters and copolymers, for example ethylene/methacrylate, ethylene/n-butyl acrylate and ethylene/acrylic acid;
3) polyolefins, such as polyethylene and polypropylene;
4) polyvinyl acetate and copolymers therewith;
5) polyacrylates;
6) polyamides;
7) polyesters;
8) polyvinyl alcohols and copolymers therewith;
9) polyurethanes
10) polystyrenes;
11) polyepoxides;
12) copolymers of vinyl monomers and polyalkylene oxide polymers;
13) aldehydes containing resins, such as phenol-aldehyde, urea-aldehyde, melamine-aldehyde and the like.
Components for improving adhesion, plasticizers, wax components, diluents, stabilizers, antioxidants, dyes and fillers may also be present.
The following are examples of components for improving adhesion:
1) natural and modified resins,
2) polyterpene resins,
3) phenol-modified hydrocarbon resins,
4) aliphatic and aromatic hydrocarbon resins,
5) phthalate esters and
6) hydrogenated hydrocarbons, hydrogenated resins and hydrogenated resin esters.
Examples of diluents include liquid polybutene or polypropylene, petroleum waxes, such as paraffin and microcrystalline waxes, semiliquid polyethylene, hydrogenated animal, fish and vegetable fats, mineral oil and synthetic waxes and also hydrocarbon oils.
Examples of the other additives can be found in the literature. To add to the disclosure, reference is specifically made to the detailed comments in EP 0 469 564 B1 on the usable hotmelt adhesive system, the thermoplastic polymers, tackifiers and plasticizers present therein, the subject matter of those comments being made part of the present application.
The present invention also relates to the process for producing the pressure-sensitive hotmelt adhesive in the form of granules. This process essentially comprises keeping the underwater granulation temperature so low that the granules have no real surface tackiness and keeping the temperature sufficiently low until the granules are coated. The low temperatures required for this purpose may readily be determined by tests for any pressure-sensitive hotmelt adhesive. The production process is characterized in that
a) the core components are melted,
b) the melt is granulated under water,
c) the underwater granules are cooled to such low temperatures that the surface tackiness of the cores is suppressed for at least 15 minutes, preferably to temperatures below 15xc2x0 C., more preferably to temperatures below 10xc2x0 C. and most preferably to temperatures below 5xc2x0 C.,
d) the cooled underwater granules are dried,
e) the dried underwater granules are sprayed with the fine-droplet liquid coating component until a sufficiently thick layer, preferably with a thickness of 5 to 50 xcexcm, has formed on the core and f) the coated cores are kept at an ambient temperature of 15 to 30xc2x0 C. and more particularly ca. 20xc2x0 C.
The temperature of the molten adhesive is preferably selected so that its Brookfield viscosity during extrusion is at least 2,000 mPas, as measured to ASTM D 3236. The preferred temperature of the adhesive during extrusion depends upon the composition of the pressure-sensitive hotmelt adhesive. In the case of the standard pressure-sensitive hotmelts, it has been found to be of advantage for the temperature of the adhesive during extrusion to be in the range from 80 to 150xc2x0 C. and preferably in the range from 110 to 130xc2x0 C.
A low temperature of the separate portions, more particularly the underwater granules, pending their coating is crucial to the invention. This requirement is satisfied particularly economically if the molten adhesive is extruded into a cooling fluid, more particularly into a water bath, of which the temperature is low enough to ensure that the separate portions have no real surface tackiness. The temperature of the cooling fluid depends upon the composition of the adhesive. For the usual pressure-sensitive hotmelt adhesives, the temperature of the cooling fluid is preferably at most 15xc2x0 C., more preferably at most 10xc2x0 C. and most preferably at most 5xc2x0 C.
In general, the cooling effect is sufficient to prevent the surfaces of the separate portions from becoming tacky before they are coated. However, the cooling effect may be supported by the presence in the cooling fluid of a release agent, more particularly a fatty acid derivative and, in one particularly preferred embodiment, a stearate. Where a release agent is used, the temperature of the cooling fluid does not have to be as low as without the release agent and/or the time from the cooling of the separate portions to their coating can be extended. However, the process according to the invention can also be carried out without the use of a release agent, in which case weakening of the adhesive strength or other adverse effects on the product properties is avoided.
In some cases, it may be desirable for the granules according to the invention to have a low bulk density. This can be achieved if the granules are substantially spherical in shape and have various diameters. Where the adhesive is extruded into a water bath, this requirement can be satisfied if the extrusion die used has bores with different cross-sections.
In one particularly preferred embodiment, the granules have two different diameters and the diameter of the smaller granules is selected so that these granules find space in the voids of a close packing formed from the large granules and the smaller granules in particular have the largest possible diameter in fulfilling this requirement. Accordingly, this embodiment of the invention is aimed at filling the voids between the large granules with the smaller granules. In a particularly preferred embodiment, the smaller granules adjoin the surfaces of the larger granules on all sides.
The mixing of granules differing in size can be achieved in various ways. On the one hand, the multiple-bore extrusion die can have bores differing in their cross-sections so that the granules differing in size can be simultaneously produced and mixed in the same granulator. On the other hand, the granules differing in size can also be produced in granulators with different bore diameters and then mixed in a subsequent step.
In addition, it is of advantage in the interests of a close packing if 20 to 40% by weight and more particularly 30% by weight of the pressure-sensitive hotmelt adhesive consists of the smaller diameter granules.
After the separate portions have been produced and cooled with a cooling fluid, more particularly water, the cooling fluid should be separated from the pressure-sensitive hotmelt adhesive. It has surprisingly been found that this can be achieved by drying in a drum dryer with warm air having a temperature of 5 to 40xc2x0 C. and more particularly 10 to 25xc2x0 C. without the separate portions of pressure-sensitive hotmelt adhesive sticking to the walls of the dryer or to one another and forming lumps.
The coating component has a temperature during spraying of 20 to 60xc2x0 C. and more particularly in the range from 25 to 35xc2x0 C.
Drying and coating are preferably carried out in a fluidized bed, drying preferably being carried out continuously in the first zone of a fluidizing channel and coating being carried out in at least one other zone. Corresponding fluidized bed processes are known in the pharmaceutical industry for the production of dragxc3xa9es. In a preferred embodiment, the granules are placed in a state of intensive motion before being repeatedly guided statistically past at least one nozzle from which the coating component is sprayed onto the granules, the motion of the granules being generated either by xe2x80x9cwhirlingxe2x80x9d with cold air at 25 to 50xc2x0 C. and preferably 30 to 40xc2x0 C. or by a rotating container, for example in the form of a drum. The sprayed droplets are between 0.5 and 200 xcexcm in size and preferably between 2 and 20 xcexcm in size. On encountering the sprayed droplets, the liquid emulsion flows around the surfaces of the cores of granules and completely envelops them. Providing the machine parameters are set accordingly, a compact and completely continuous layer can thus be applied to the granule cores and will not burst open or become tacky, even under pressure.
The granules are thus protected against further sticking and can be directly packed in boxes, bags, etc.
For use, the free-flowing granules are melted and applied in molten form.
The solution according to the invention affords the following advantages over powder coating for example: fully continuous surface, clean process (dust), better control of coating, easier and better handling by the customer.

Hot-melt-type adhesive in the form of a granulate


A process for making neutral sugar surfactant granules involving: (a) providing a water-containing alkaline sugar surfactant selected from the group consisting of an alkyl oligoglycoside, an alkenyl oligoglycoside, a fatty acid-N-alkyl polyhydroxyalkylamide, and mixtures thereof; (b) providing a thin-layer evaporator or dryer having rotating internals; (c) neutralizing the water-containing alkaline sugar surfactant to a pH of from 6.8 to 7.5 to form a neutralized water-containing sugar surfactant; (d) introducing the neutralized water-containing alkaline sugar surfactant into the thin-layer evaporator or dryer; and (e) drying the water-containing alkaline sugar surfactant in the thin-layer evaporator or dryer until it has a residual water content below 2% by weight.

This invention relates to a process for the simultaneous drying and granulation of water-containing, alkaline sugar surfactant pastes in a thin layer evaporator/dryer.
Sugar surfactants, for example alkyl oligoglucosides or fatty acid-N-alkyl glucamides, are distinguished by excellent detergent properties and high ecotoxicological compatibility. For this reason, these classes of non-ionic surfactants are acquiring increasing significance. Although, hitherto, they have generally been used in liquid formulations, for example dishwashing detergents or hair shampoos, there is now also a market need for solid, water-free formulations which may even be incorporated, for example, in powder-form detergents or syndet soaps.
On an industrial scale, liquid surfactant formulations are generally dried by conventional spray drying, in which the water-containing surfactant paste is sprayed in the form of fine droplets at the head of a tower, the droplets encountering hot drying gases flowing in countercurrent. Unfortunately, this technology cannot readily be applied to sugar surfactant pastes because the temperatures required for drying are above the caramelization temperature, i.e. the decomposition temperature, of the sugar surfactants. The conventional drying of sugar surfactant pastes results in the formation of carbonized products, in addition to which caking occurs on the walls of the spray drying tower so that they have to be cleaned at considerable expense at short intervals.
Attempts have been made in the past to overcome this problem. For example, German patent application DE-A1 41 02 745 (Henkel) describes a process in which a small quantity of 1 to 5% by weight of alkyl glucosides is added to fatty alcohol pastes which are then conventionally spray dried. Unfortunately, the process can only be carried out in the presence of a large quantity of inorganic salts. According to German patent application DE-A1 41 39 551 (Henkel), pastes of alkyl sulfates and alkyl glucosides which may contain at most only 50% by weight of the sugar surfactant are sprayed in the presence of mixtures of soda and zeolites. However, this process only gives compounds with a low surfactant concentration and an inadequate bulk density. Finally, International patent application WO 95/14519 (Henkel) reports on the drying of sugar surfactant pastes with superheated steam. Unfortunately, this is technically very complicated. In fact, there has not yet been a reliable process which enables high-quality, substantially water-free sugar surfactant powders or granules to be produced, but which does not entail the use of carriers during the drying process. Another problem of known processes is that they do not lead to the particularly preferred heavy powders with a bulk density above 500 g/l and, at the same time, a greatly reduced dust content. However, it is precisely these two parameters which are so important on economical, applicational and safety grounds.
German patent DE-C1 195 34 371 (Henkel) describes a process for the production of sugar surfactant granules in which water-containing pastes of alkyl glucosides or fatty acid-N-alkyl glucamides are dried in a thin layer evaporator. The preparations are highly alkalized (pH=11-12) for antimicrobial stabilization. However, a neutral to slightly acidic pH value is required for cosmetic product formulations. The discontinuous nature of the neutralization step in the paste is very time-consuming and can only be reproduced to a limited extent on account of the considerable buffer effect so that frequent readjustment is necessary. In addition, if the pH falls below the neutral point, the paste foams vigorously with evolution of carbon dioxide. In addition, a subsequent heat treatment during drying leads to a poorly reproducible increase in the pH value so that neutral granules cannot readily be produced by this method.
Accordingly, the complex problem addressed by the present invention was to convert water-containing, alkaline sugar surfactant pastes with minimal outlay on equipment into substantially water-free and dust-free granules with a neutral or slightly acidic pH value which, compared with known products, would be distinguished simultaneously by improved colour quality and storage stability, by a high bulk density and by good flow properties
The present invention relates to a process for the production of neutral sugar surfactant granules, in which water-containing pastes of
a) alkyl and/or alkenyl oligoglycosides and/or
b) fatty acid-N-alkyl polyhydroxyalkylamides
with a solids content of at least 20% by weight and preferably in the range from 25 to 75% by weight are dried in a horizontally arranged thin-layer evaporator or dryer with rotating internals to a residual water content below 2% by weight, preferably below 1.5% by weight and, more preferably, below 1% by weight and, at the same time, converted into particulate form, characterized in that the sugar surfactant pastes are neutralized immediately before entering the thin-layer evaporator/dryer.
It has surprisingly been found that the introduction of the neutralizing agent immediately before the alkaline pastes enter the thin-layer evaporator/dryer leads to rapid and uniform neutralization and ultimately to products which are far more light-colored and color-stable than known products. Conversely, this means that neutralized sugar surfactant pastes can be dried at distinctly higher temperatures, i.e. at increased product throughputs, and that granules equivalent in their color quality to known granules can still be obtained. The products have a high apparent density of 550 to 650 g/l and an average particle diameter of 2 to 4 mm which leads to a reduction in the unwanted absorption of water and in the caking of the particles. High stability in storage is also achieved in this way. At the same time, the particles are dust-free, i.e. the percentage of particles smaller than 200 xcexcm in diameter is less than 5% by weight, and considerably harder than comparable granules which has a favorable effect on their flow properties.
Alkyl and/or alkenyl oligoglycosides
Alkyl and alkenyl oligoglycosides are known nonionic surfactants which correspond to general formula (I):
R1Oxe2x80x94[G]pxe2x80x83xe2x80x83(I)
where R1 is an alkyl and/or alkenyl radical containing 4 to 22 carbon atoms, G is a sugar unit containing 5 or 6 carbon atoms and p is a number of 1 to 10. They may be obtained by the relevant methods of preparative organic chemistry. EP-A1-0 301 298 and WO 90/03977 are cited as representative of the extensive literature available on this subject.
The alkyl and/or alkenyl oligoglycosides may be derived from aldoses or ketoses containing 5 or 6 carbon atoms, preferably glucose. Accordingly, the preferred alkyl and/or alkenyl oligoglycosides are alkyl and/or alkenyl oligoglucosides. The index p in general formula (I) indicates the degree of oligomerization (DP degree), i.e. the distribution of mono- and oligoglycosides, and is a number of 1 to 10. Whereas p in a given compound must always be an integer and, above all, may assume a value of 1 to 6, the value p for a certain alkyl oligoglycoside is an analytically determined calculated quantity which is generally a broken number. Alkyl and/or alkenyl oligoglycosides having an average degree of oligomerization p of 1.1 to 3.0 are preferably used. Alkyl and/or alkenyl oligoglycosides having a degree of oligomerization of less than 1.7 and, more particularly, between 1.2 and 1.4 are preferred from the applicational point of view. The alkyl or alkenyl radical R1 may be derived from primary alcohols containing 4 to 11 and preferably 8 to 10 carbon atoms. Typical examples are butanol, caproic alcohol, caprylic alcohol, capric alcohol and undecyl alcohol and the technical mixtures thereof obtained, for example, in the hydrogenation of technical fatty acid methyl esters or in the hydrogenation of aldehydes from Roelen""s oxosynthesis. Alkyl oligoglucosides having a chain length of C8 to C10 (DP=1 to 3), which are obtained as first runnings in the separation of technical C8-18 coconut oil fatty alcohol by distillation and which may contain less than 6% by weight of C12 alcohol as an impurity, and also alkyl oligoglucosides based on technical C9/11 oxoalcohols (DP=1 to 3) are preferred. In addition, the alkyl or alkenyl radical R1 may also be derived from primary alcohols containing 12 to 22 and preferably 12 to 14 carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol, cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol, brassidyl alcohol, Gurbet alcohols and technical mixtures thereof which may be obtained as described above. Alkyl oligoglucosides based on hydrogenated C12/14 coconut oil fatty alcohol having a DP of 1 to 3 are preferred.
Fatty acid-N-alkyl polyhydroxyalkylamides
Fatty acid-N-alkyl polyhydroxyalkylamides are non ionic surfactants corresponding to formula (II):
in which R2CO is an aliphatic acyl radical containing 6 to 22 carbon atoms, R3 is hydrogen, an alkyl or hydroxyalkyl radical containing 1 to 4 carbon atoms and [Z] is a linear or branched polyhydroxyalkyl radical containing 3 to 12 carbon atoms and 3 to 10 hydroxyl groups. The fatty acid-N-alkyl polyhydroxyalkylamides are known compounds which may normally be obtained by reductive amination of a reducing sugar with an alkylamine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride. Processes for their production are described in U.S. Pat. Nos. 1,985,424, 2,016,962 and 2,703,798 and in International patent application WO 92/06984. An overview of this subject by H. Kelkenberg can be found in Tens. Surf. Det. 25, 8 (1988). The fatty acid-N-alkyl polyhydroxyalkylamides are preferably derived from reducing sugars containing 5 or 6 carbon atoms, more particularly from glucose. Accordingly, the preferred fatty acid-N-alkyl polyhydroxyalkylamides are fatty acid-N-alkyl glucamides which correspond to formula (III):
Preferred fatty acid-N-alkyl polyhydroxyalkylamides are glucamides corresponding to formula (III) in which R3 is an alkyl group and R2CO represents the acyl component of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, arachic acid, gadoleic acid, behenic acid or erucic acid or technical mixtures thereof. Fatty acid-N-alkyl glucamides (III) obtained by reductive amination of glucose with methylamine and subsequent acylation with lauric acid or C12/14 coconut oil fatty acid or a corresponding derivative are particularly preferred. In addition, the polyhydroxyalkylamides may also be derived from maltose and palatinose.
Neutralization
To neutralize the alkaline sugar surfactant pastes, a continuous stream of an aqueous neutralizing agent is added to the pastes immediately before they enter the thin-layer evaporator/dryer in such a quantity and at such a rate that a pH value of 6.8 to 7.5 is spontaneously established. By means of the high-speed rotor of the evaporator, homogenization is achieved in a very short time so that the formation of acidic or alkaline xe2x80x9cknotsxe2x80x9d can be reliably avoided; there is also no unwanted foaming of the mixture. The neutralizing agent can be regulated by pH measurement in the end product. Basically, aqueous mineral acids or organic acids are suitable neutralizing agents. Phosphoric acid, lactic acid and preferably citric acid in the form of aqueous solutions with a solids content of 25 to 50% by weight are preferably used.
Drying and Granulation in the Thin-Layer Evaporator/Dryer
The simultaneous drying and granulation process takes place in a horizontally arranged thin-layer evaporator or dryer with rotating internals of the type marketed, for example, by the VRV company under the name of xe2x80x9cFlash Dryerxe2x80x9d or by the Vomm company under the name of xe2x80x9cTurbo Dryerxe2x80x9d. In simple terms, the flash dryer is a tube which can be heated to different temperatures over several zones. The paste-form starting material, which is introduced by a pump, is projected onto the heated wall by one or more shafts fitted with paddles or plowshares as rotating internals and is dried on the heated wall in a thin layer typically with the thickness of 1 to 10 mm. According to the invention, it has been found to be of advantage to apply a temperature gradient of 120-170xc2x0 C. (product entrance) to 20xc2x0 C. (product exit) to the thin layer evaporator. To this end, the first two zones of the evaporator for example may be heated to 120-190xc2x0 C. and preferably to 120-130xc2x0 C. and the last zone to 20xc2x0 C. Higher drying temperatures have not been found to be of advantage in view of the thermal lability of the starting materials. The thin-layer evaporator is operated at atmospheric pressure. Air or, for example, an alkaline gas stream is passed through in countercurrent (throughput about 50-150 m3/h for an area of 0.5 m2). The gas entry temperature is generally in the range from 20 to 30xc2x0 C. while the exit temperature is in the range from 90 to 1 10xc2x0 C.
The water-containing sugar surfactant pastes which may be used as starting materials may have a solids content above 20% by weight and preferably in the range from 25 to 75% by weight. Typically, their solids content is of the order of 30 to 50% by weight. The throughput is of course dependent on the size of the dryer, but is typically in the range from 5 to 15 kg/h. It is advisable to heat the pastes to 40 to 60xc2x0 C. during their introduction. In addition, in one preferred embodiment of the invention, the product may even be partly recycled, i.e. part of the product output may be returned to the drying stage and mixed with the aqueous paste.
In addition, after drying, it has proved to be of considerable advantage to transfer the granules, which still have a temperature of around 50 to 70xc2x0 C., to a conveyor belt, preferably in the form of a vibrating shaft, and rapidly to cool them thereon, i.e. over a period of 20 to 60 seconds, to temperatures of around 30 to 40xc2x0 C. using ambient air. In order further to improve their resistance to the unwanted absorption of water, the granules may also be xe2x80x9cdustedxe2x80x9d, for example by addition of 0.5 to 2% by weight of silica, alkalil metal carbonate or the like.
The granules obtainable by the process according to the invention may be subsequently mixed with other ingredients of powder-form surface-active formulations, for example tower powders for detergents. In addition, the powders may readily be incorporated in aqueous preparations. In fact, where the powders are used, no differences in performance properties are observed in relation to the water-containing starting pastes. The granules may also readily be incorporated in syndet soap formulations and toothpastes, for example together with fatty acids, fatty acid salts, starch, polyglycol and the like.

Method for producing neutral sugar surfactant granulates


State based full and empty control for rechargeable batteries that will assure a uniform battery empty condition, even in the presence of a load on the battery. A fuel gauge provides a prediction of the open circuit voltage of the battery, and when the predicted open circuit voltage of the battery reaches the predetermined open circuit voltage of an empty battery, the load is terminated, after which the battery will relax back to the predetermined open circuit voltage of an empty battery. A similar technique is disclosed for battery charging, allowing faster battery charging without overcharging. Preferably an RC battery model is used as the fuel gauge to provide the prediction, but as an alternative, a coulomb counter may be used to provide the prediction, with error correction between successive charge discharge cycles.

1. Field of the Invention
The present invention relates to charging methods for rechargeable batteries.
2. Prior Art
The standard definition of empty for a (rechargeable) battery is when a particular battery terminal voltage defined as the empty voltage occurs. This definition is naïve and simple-minded, since the external voltage says little about the internal state of the battery. The real reason for this definition is that there has been no better way to define empty, and battery vendors must provide a rule of some sort, so they define a voltage.
Other approaches have been used, but they lose capacity as a function of load, temperature, battery characteristic, and empty voltage. For instance, coulomb counters have been used, but a coulomb counter must traverse full and empty often or error accumulates. Also there is no reliable method to recognize actual light-load capacity shrinkage, since the capacity to an empty voltage is dependent on the actual load from each cycle, because of battery impedance. Another approach uses battery impedance to predict traditional cell voltage definition of empty. Still another approach is to use a previous model gauge approach, that is, to use empty compensation to predict traditional cell voltage definition of empty, i.e., to account for the relaxation of a battery after a load is removed so that after relaxation, the open circuit voltage of the battery should be the predetermined empty voltage. All of these previous approaches result in variation of capacity utilization and residual charge which is unused.
Maxim Integrated Products, assignee of the present invention, manufactures and sells voltage-based battery fuel gauges that model the battery itself, and track the state of charge of the battery independent of the current load, if any, on the battery. In particular, an ideal battery of a given amp-hour capacity would provide a constant voltage output until outputting its total amp-hour capacity, after which the battery voltage would fall to zero. Real batteries, however, exhibit a decrease in terminal voltage with a decreasing state of charge and/or an increasing current load. Some batteries have a terminal voltage that falls off rapidly as the fully discharged state is approached.
One battery model that can be used is a simple RC network, where R represents the internal impedance of the battery and C represents the equivalent capacitance of the battery for any given open circuit battery voltage. R can be easily determined by loading and unloading the battery, and to the first order, generally can be taken as a constant value. The apparent capacitance C in the simple RC model at any point in the open circuit voltage versus state of charge curve is equal to the inverse of the rate of change of the open circuit voltage of the battery per amp-hour of current withdrawn. Consequently one may plot the equivalent capacitance of the battery versus open circuit voltage, and the plot of capacitance versus battery open circuit voltage can be approximated as piecewise constant C values over various increments of the open circuit voltage. Of course R and C may be scaled as desired without effecting the result. Then on charging and discharging, using the RC model and sensing the battery terminal voltage and current to and from the battery, the open circuit voltage of the battery can be calculated to determine the state of charge of the battery independent of the current flow. Of course one can also use a more complicated battery model to account for such things as long term recovery of the battery (a long time constant component), temperature, variations in battery impedance (R), current, etc. Also a coulomb counter can be used with such modeling, the coulomb counter increasing the transient and short term accuracy of the modeling and the modeling increasing the long term accuracy of the coulomb counter.
In the description to follow, whenever exemplary values are given, it is assumed that the battery is a Li-ion battery, though the principles of the present invention are applicable to other types of rechargeable batteries as well.
One embodiment of the present invention takes advantage of the fact that by modeling the battery, such as in the prior art described above, one can know the open circuit voltage of the battery, even when the battery is under a load. The particular model used is not of great importance, as any reasonable prediction of the open circuit voltage of a battery under load will be better at determining the battery state of charge than simply using the terminal voltage of the battery for that purpose. Thus the present invention allows the setting of state based full and empty conditions of the battery, and adhering to those states even when under a load.
By way of example, state-based empty control allows the immediate battery terminal voltage to be disregarded and allow full battery utilization across a wide range of load conditions, such as load variations, temperature variations, battery variations, age, etc. Normally the impedance drop of a battery would be responsible for capacity loss. Additionally, state based full and empty control reduces the overall error budget which allows for better battery utilization. In particular, state based full and empty control takes advantage of the capacity of the specific battery being monitored, rather than limiting that capacity because of battery impedance. State based full and empty control can also be used to provide additional well controlled limitations on battery charge and discharge limits for the purpose of battery lifespan extension. This is especially important in applications which demand more than the typical 5 year battery lifespan (such as automotive, which demands more than 10 years).
FIGS. 1a through 1d depict the state based empty vs. the traditional methods of defining empty. In these curves, the thin lines or curves represent traditional methods and the thick lines or curves represent the state based empty of the present invention. The curves for Q(@C/2) represent the discharge rate under a heavy load, while the curves for Q(@C/8) represent the discharge rate for a light load. The traditional method stops at the same immediate battery voltage independent of load (3.0 volts in FIG. 1b), yet stops or settles at a different battery state which is evidenced by the difference in the following relaxation voltage. The state of the battery (open circuit battery terminal voltage) is different in each of these two cases, as can be seen in FIGS. 1a and 1c. However, the state based empty of the present invention stops at the same state (same open circuit battery terminal voltage as shown in FIG. 1c), but allows for a different immediate battery voltage when stopping (FIG. 1d), and manages the following relaxation state to be relatively independent of load condition, to settle on the same open circuit voltage. To achieve this, the fuel gauge must be capable of accurate OCV predictions, which is a compounded challenge near empty when OCV and resistance become very nonlinear.
The state based full condition also provides better control of the full state for optimized charge control and charge speed. This can be achieved in life-span optimized applications, such as 3-year warrantee situations (currently seen in the industry for Apple and HP laptop computers). In these applications the charge voltage is often reduced from 4.2V to 4.1V to improve battery lifespan, since time at full often dominates as a cause of battery aging (especially for users who keep laptops always plugged in). The common solution for this lifespan extension is to simply charge to 4.1V instead of 4.2V. A smarter way to achieve the same lifespan improvement is to charge to a higher immediate battery terminal voltage, such as 4.2V, but change charge termination to occur at the same state (same open circuit battery terminal voltage) as the prior art 4.1V charging. This provides lifespan extension (and warrantee extension) while simultaneously providing a feature to accelerate charging.
This concept is depicted in the FIG. 2. The sloped line at the left represents the charging rate. For an extended battery life in the prior art, the charging voltage peaks at 4.1 volts, and after a period of time, the charger is shut off and the battery open circuit voltage relaxes to 4.05 volts. With the present invention, charging can proceed to 4.2 volts for a shorter time to achieve the same state of charge, with the relaxation starting earlier and being more pronounced to ultimately reach the same open circuit voltage of 4.05 volts, thereby charging to the same open circuit voltage as the prior art charging technique produces (4.05 volts). Again this is achieved with a fuel gauge that manages an accurate OCV prediction. This same concept might be used for the 4.2V charging by overcharging to 4.3V but stopping early to the same state as 4.2V full. However, one should verify that going to an even higher charging voltage than specified by the battery manufacturer, even for a short time, would possibly somehow not achieve the desired effect or further shorten the battery life.
In extreme long lifespan applications, it is common to charge to only 70% and discharge to only 30% in order to maximize the total battery life utility (cycles*capacity). This is done in space applications where the service cost is extreme, but it is also done in automotive applications where the vehicle must last more than 10 years. State based full and empty control can extend this existing concept by more accurately and directly managing battery state by the open circuit prediction and perception used in the present invention.
Thus by having a good prediction of the battery state, one can more accurately define the full and empty states and utilize more of the battery capacity without risk of overcharging or overdischarging the battery. As a result, state based full and empty control should improve run-time by more than 30% for an aged battery because of its higher impedance. At cold temperatures (such as 0° C.) a battery can lose over half the capacity. At cold, state based full and empty control can improve run-time by more than 50%. When the loading on the battery is high, there is much more voltage drop, and battery voltage is more disassociated with battery state. At 1 C load, state based full and empty control can improve run-time by more than 20% on some new batteries, relative to higher 3.4V and 3.3V empty voltages.
Fuel-gauging is a real-time activity and cannot be allowed to depend on a future relaxed condition which happens after the critical event (empty) is already past. Real-time fuel-gauging must make its predictions while there is loading present. By defining empty according to a prediction of the open circuit voltage, the fuel-gauge can actually limit and manage the empty state of the battery, instead of using a simple immediate voltage. This will be typically performed with 2% or 3% battery capacity held in reserve, i.e., discharge will be terminated at 2% or 3% actual battery state of charge to leave a reserve capacity. That reserve capacity may be used to support:                1. Reserve & background functions (saving data, shutting down, maintaining clock).        2. Error budget (no fuel-gauge can be perfect).        3. Protect the battery from overdischarge. Discharging down to the bottom 1% of the battery could injure the battery and will accelerate aging.
Another technique that could be used to practice the present invention is to use a coulomb counter type of fuel gauge and note the open circuit voltage of the battery after each discharge and after the battery has an opportunity to relax. Then the coulomb count from full to empty may be adjusted up or down for the next charge discharge cycle based on the error between the open circuit voltage of the battery after relaxation and the intended open circuit voltage of the battery representing empty. Similarly, the open circuit voltage of the battery after each charge and after the battery has an opportunity to relax could be noted. Then the coulomb count from empty to full may be adjusted up or down for the next discharge charge cycle based on the error between the open circuit voltage of the battery after relaxation and the intended open circuit voltage of the battery representing full.
While this could work, it has the disadvantage that it is dependent on the habits of the device user even more than the typical coulomb counter. In particular, not only may the user of the device not fully charge the battery between discharges, which allows drift in the coulomb count, but the user may initiate recharging right after an indicated empty occurs, so that an accurate reading of open circuit voltage after an empty is indicated is not obtainable. Accordingly the battery model method is preferred, though the specific battery model used is itself a matter of preference and the model itself is not a part of this invention.
Thus the present invention has a number of aspects, which aspects may be practiced alone or in various combinations or sub-combinations, as desired. While certain preferred embodiments of the present invention have been disclosed and described herein for purposes of illustration and not for purposes of limitation, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.


The harmonic structure of music is visually represented by establishing a correlation of each degree of the diatonic scale with a specified color and applying that correlation to a musical composition so that each note of the composition is represented by the respective color uniquely identified with its scale degree.

1. Field of the Invention
This invention pertains to music notation and provides an a alternative system of notation based upon the correlation of colors to the tones of a musical scale.
2. State of the Art
Systems for the notation of western music have evolved over the past millennium, together with the concurrent evolution of music theory and the application of that theory to compositions and performances. For at least several centuries, the importance of harmonic structure has been recognized and taught.
Music notation is symbolic in nature, typically reflecting rhythm, melody and harmonic structure with reference to printed staffs. A staff comprises a plurality of parallel lines, each of which represents a specified pitch (selected audible frequency) within a musical scale (conventionally in the key of C major). The spaces between staff lines represent intermediate pitches within the same musical scale. The lines and spaces may be termed xe2x80x9cstaff positionsxe2x80x9d and are arranged to correspond to each whole tone and semitone (scale degree) of a musical scale. As the use of staffs became common, it became conventional practice to utilize vertical bar lines to divide them into measures of prescribed duration.
Historically, the appropriate pitch, rather than a specified scale degree, has sometimes been assigned to each line and space in a staff. According to this convention, the staff position corresponding to any given pitch remains constant. Players of transposing instruments (those pitched in keys other than C) are trained to use a different fingering to sound a designated pitch, in essence, performing the transposing function mentally. It requires less skill, however, and has thus became conventional practice to assign specific scale degrees to each staff position and to provide players of transposing instruments written music with individual notes transposed to the staff positions appropriate for the pitch of their respective instruments.
Because the audible range of music extends for several octaves, staffs representing different standardized frequency bands are in use, the most common being the treble, tenor and bass clef staffs.
The staff system may be regarded as a means for the graphical representation of music. Symbolic xe2x80x9cnotesxe2x80x9d and xe2x80x9crestsxe2x80x9d divide each measure of the staff, indicating the duration of xe2x80x9cstruckxe2x80x9d (or otherwise xe2x80x9csoundedxe2x80x9d) tones and intervals of silence, respectively. Notes are positioned upon the staff to designate the scale degree (and thereby the pitch) of each note of a melody. Pitches outside the scale of the staff are designated by xe2x80x9caccidentalxe2x80x9d symbols, indicating that the pitch corresponding to a scale degree should be either raised (sharped) or lowered (flatted), typically by a semitone. Traditionally, scale tones are assigned staff positions which correspond to the Key of C; that is, a C scale is represented without accidentals. Scales in keys other than C could be graphically represented by a staff which assigned pitches appropriate to that key to the staff. An alternative convention has been adopted, however. Specifically, the fundamental pitch of a staff is changed to keys other than C through the use of key signatures. In essence, the use of key signatures avoids the need for repetitive accidentals to graph compositions of varying keys on a common staff.
The graphical representation of harmony on a staff has also undergone evolution. Two-part harmony and counterpoint melodies could be written out as parallel melody lines. Harmonic accompaniment, however, was, until relatively recently, often improvised. An early method for indicating harmonic structure was the xe2x80x9cfigured bassxe2x80x9d system. That system designated by numerals the harmonic scale positions of specific chords. Thus, the accompanyist could use the same graphical representation without regard to the key of the composition. Modem jazz notation still uses a form of figured bass notation, wherein scale positions are usually designated by roman numerals, and chord structures are designated by superscript Arabic numerals and letters.
Harmonic structure is susceptible to systematic analysis and application. Harmonic relationships, intervals, chord structures, progressions, scales, modes, and other theoretical topics have been studied and taught utilizing various organization approaches. Western music is conventionally based upon a xe2x80x9ctemperedxe2x80x9d diatonic scale, that is, a scale in which an octave is divided into twelve evenly spaced semitones. The very nature of the diatonic scale imposes both a fundamental logic and a degree of complexity to the study and understanding of harmonic structure. The diatonic scale may be viewed as two tetra chords, specifically do-re-mi-fa and so-la-ti-do, separated by the whole step: fa-la. The construction of triads at each degree of a scale thus produces a non-repeating series of chords. Identifying each scale degree by a roman numeral, a minor interval as xe2x80x9cmxe2x80x9d and a major interval as xe2x80x9cM,xe2x80x9d beginning students learn the following construction of triads:
The parenthetical arabic numerals in the table designate the scale tones of each triad, with xe2x80x9c8thxe2x80x9d being an octave higher than xe2x80x9c1st.xe2x80x9d Each triad may be xe2x80x9cinverted,xe2x80x9d that is, built up from any of its three individual notes. For example, triad VII (the diminished chord) may be built alternatively as 7th, 9th, 11th; 2nd, 4th, 7th or 4th, 7th, 9th. The student must thus learn to distinguish inverted triads from other chords which start from the same scale degree, but are spelled somewhat differently. For example, a If chord (2nd, 4th, 6th) must be differentiated from the inverted VII chord (2nd, 4th, 7th). This challenge increases with chords of greater complexity.
Music is generally written graphically, with individual notes assigned to staff positions, and the staff positions being assigned scale degrees corresponding to the key of C, augmented by key signatures. Chords are thus conventionally xe2x80x9cspelledxe2x80x9d by reference to the letter names designating the scale degrees of the key in which a composition is written (or transposed).
The spelling systems in use can be confusing, in that chords which are congruent (that is, spelled the same or containing the same notes) are given different names, depending upon the specific harmonic constraints of a composition. The discipline of music theory requires consistency within a selected key, inevitably requiring redundant nomenclature to describe the same chord in different environments. While many students of music gain a complete mastery of music theory, including harmonic structure, they do so with considerable effort and dedication. Even after devoting considerable effort to this study, many, including proficient performing musicians, fail to recognize the harmonic structure of musical compositions and are thus disadvantaged in their efforts to improvise. Others who are exposed to music theory simply find the subject matter inaccessible and/or incoherent.
Students of music are often instructed by reference to printed music which displays each note to be played, without reference to the harmonic structure of the composition. It is thus possible to progress in xe2x80x9csight readingxe2x80x9d and other performance skills without gaining a good understanding or appreciation of harmonic structure. Many highly skilled performers thus lack the ability to improvise. Other performers improvise xe2x80x9cby ear.xe2x80x9d While certain individuals achieve virtuosity by this means, an understanding of, or at least a xe2x80x9cfeelingxe2x80x9d for, harmonic structure is generally regarded as essential for high-level improvised performance.
Color has been used as a guide to proper finger positioning in certain instructional systems for keyboard and fretted instruments. Colors have also been incorporated into devices and systems which display colors in response to pitches or other characteristics of audible musical signals. Heretofore, however, the color spectrum has not been correlated to harmonic structure for purposes of either performance or instruction.
This invention provides a musical notation system which correlates xe2x80x9crainbowxe2x80x9d colors to the seven degrees of the diatonic major and minor scales. While other correlations are operable, the preferred notation system identifies the first through seventh degrees of Major and Minor Tonic scales, respectively, as: Red, Green, Violet, Yellow, Blue, Orange and Turquoise. The preferred correlation for the seven degrees of a relative minor scale are thus: Orange, Turquoise, Red, Green, Violet, Yellow and Blue, respectively. This correlation makes use of the conventional color wheel arrangement of primary and secondary colors. It assigns the primary colors (red, yellow and blue) to the scale notes conventionally regarded as most xe2x80x9cimportantxe2x80x9d (1st, 4th and 5th). The secondary colors (green, violet and orange) are assigned to the scale notes generally regarded as of secondary harmonic importance (2nd, 3rd and 6th). A tertiary color (e.g., turquoise or aqua) is assigned to the 7th scale tone, consistent with its generally recognized lesser status within the scale family.
It is recognized that the specific correspondence of the primary colors to the respective first, fourth and fifth scale notes can be selected from among any of the six possible arrangements. The specific correspondence of the secondary colors to the respective second, third and sixth scale notes can be similarly rearranged, although there is value in organizing the color sequence of the scale tones such that the middle note of each of the I, IV and V triads is the blended color of the colors representing the other two notes. Accordingly, while any tertiary color can be assigned to the seventh scale note without a serious consequence to the practical application of the invention, ideally that tertiary color will be the resultant of blending the colors representing the 5th and 9th (identical to the 2nd) scale notes. These considerations are reflected by the color sequence selected for purposes of this disclosure.
Various notation systems can be constructed upon this relationship of colors to sound. Among those notation systems is one designated the xe2x80x9cChromatic Music Notationxe2x80x9d (CMN) system, which constitutes an exemplary embodiment of the invention. To avoid redundancy of description, this disclosure emphasizes the CMN system, but it is recognized that many equivalent alternative notation systems can be devised. The CMN system is one example of a notation system which correlates scale degrees to colors in a practical graphical manner. Compositions may be represented by CMN (or other color-coordinated notation systems) in a format suitable for sight-reading. Equally important, however, software can be utilized to convert conventional notation into CMN, suitable for display on a computer screen or printed out as a hard copy, for example. CMN data may be digitized and processed by conventional means for use with existing or evolving media devices and formats. Alternative software can adduce the harmonic structure of a composition from the audio signals of a recorded or live performance. CMN data, no matter how obtained, can be processed into a CMN video display, a CMN hard copy, a realtime or stored color display or any other realization corresponding to the harmonic structure of the composition. A student of music perceives the harmonic structure of the composition in terms of scale degree, without regard to the key in which it is written or performed.
The CMN system of this invention is based upon a perceived correlation between the color hierarchy of the visible light segment of the electromagnetic spectrum and the scale note hierarchy of any diatonic scale constructed within the audible sound segment of the electromagnetic spectrum. It is believed that analogous correlations inherently exist for natural scales and other scales which depart philosophically from the diatonic scale. Because modern musical instruction focuses on the diatonic scale, this invention finds more immediate application within that realm, and the CMN system is described as a currently preferred practical embodiment. The seven conventional rainbow colors are thus correlated with the seven tones of the diatonic scale, as follows:
so that the three primary colors (red, yellow and blue) are inherently associated with the three primary triads (those based upon the scale positions I, IV and V, respectively). By this means, many abstract aspects of music are visually displayed, making them more accessible to a large segment of the public. For example, adjacent scale tones (seconds) are inherently represented by complementary colors, and are thus readily seen to correspond to each other musically as dissonance. Thirds, which are heard as consonant intervals, are represented by a primary color and a secondary color comprising that primary color. For example, the third (I-III) interval is represented by red-violet (a blend of red and blue). The third (II-IV) is represented by green (a blend of yellow and blue) and yellow. The third (V-VII) is represented by blue and turquoise (a blend of blue and green). Sixth intervals, which are also perceived psychologically as consonant, follow a similar pattern, being represented by two colors, each of which either is or comprises a common primary color. For example, the sixth (I-VI) is represented by red-orange (a blend of red and yellow), while the sixth (II-VII) is represented by green (a blend of blue and yellow) and turquoise (a blend of blue and green). The degree of relatedness of the colors defining 2nd, 3rd and 6th intervals is useful in establishing xe2x80x9cmemory tiesxe2x80x9d for a student of harmony. The relationships of the colors (as adopted by the CMN system) representing all of the basic intervals starting at all scale positions are shown by the following table:
CMN may take various forms. Ideally, the root note of the harmonic domain is displayed in a visually dominant manner, such as by a larger image. Such a display offers the immediate identification of the harmonic changes in music and facilitates ear training in developing recognition of chord inversions. Similarly, it is often useful to display the tonic, dominant and subdominant scale notes proportionately larger than the other scale notes. By this means, the scale note hierarchy and relationships are emphasized in a manner believed to provide xe2x80x9cmemory tiesxe2x80x9d useful for ear training.
An appropriate display of the diatonic scale for purpose of harmony instruction is:
This arrangement places the tonic scale tone at the center, which reflects its harmonic importance. The harmonic universe is bounded by the relatively significant dominant and subdominant scale tones, while the relatively less important scale tones are de-emphasized. It should be understood that the color names would ordinarily be represented by correspondingly colored symbols, and that those symbols could optionally be sized as suggested by the table. That is, the red tonic symbol could be relatively large, the blue dominant and yellow subdominant symbols of intermediate size and the remaining scale note symbols relatively small. The mental image arising from this graphic display is believed to better represent the scale from a harmonic perspective, although displaying scale notes in sequence, starting with the tonic, is appropriate to illustrate the manner in which scales are played.
In practice, musical compositions may be displayed in formats which preserve some aspects of conventional notation, while relying upon the color correlations of this invention merely to display harmonic structures of the cm position may be displayed in conventional fashion within measure bars, while the melody line is indicated by colored symbols. Alternatively, the composition may be displayed dynamically upon a display such that tempo is directly indicated by the pace of the display. Note duration and rests may be indicated directly by the duration of the colored note symbols on the display. Dynamics may also be indicated by color intensity or other visually perceivable indicia. Each of these parameters, among others, may be adjustable through software or hardware devices in accordance with conventional electronic data processing technologies.