Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/39—Organic or inorganic per-compounds
  • C11D3/3902—Organic or inorganic per-compounds combined with specific additives
  • C11D3/3905—Bleach activators or bleach catalysts
  • C11D3/3907—Organic compounds
  • C11D3/3917—Nitrogen-containing compounds
  • C11D3/392—Heterocyclic compounds, e.g. cyclic imides or lactames
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D17/00—Detergent materials or soaps characterised by their shape or physical properties
  • C11D17/0039—Coated compositions or coated components in the compositions, (micro)capsules

Definitions

• the present invention relates to active substrates such as bleach activators releasably encapsulated in a coating thereon and methods of applying the same.
• bleaches and bleach activators in detergent formulations.
• One of the important aspects of such formulations is that they should be capable of being stored over a significantly long period both by the producers of such formulations, the retailers of the product and by the end user, e.g. the housewife, who usually buys in bulk and likes to use it in small aliquots for washing as and when necessary.
• the components of such formulations, especially the bleaches and bleach activators have an unacceptably short storage life due to their tendency to undergo undesirable physical or chemical changes, thereby resulting in deterioration of the formulation which may manifest itself as, e.g.
• the present invention relates to an encapsulated active substrate comprising a bleach activator releasably encapsulated in a coating of at least one metal salt of an inorganic acid, said salt being soluble in an aqueous medium such that upon contacting the encapsulated substrate with the aqueous medium the the active substrate is released into said medium.
• active substrate a bleach activator as such or a composite which comprises such bleach activator and one or more other components including conventional binders such as e.g. a bentonite clay; surfactants such as polyoxyalkylene sorbitan oleate esters, e.g. Tween (Registered Trade Mark) an alkali metal salt of a polycarboxylic acid, e.g. Dispex-G40 (Registered Trade Mark, ex Allied Colloids, UK); disintegrating aids such as cross-linked carboxy methyl cellulose derivatives e.g. Ac-di-sol (Registered Trade Mark) or a polyacrylate; and fillers such as the cellulosic type, e.g. Avicel (Registered Trade Mark).
• conventional binders such as e.g. a bentonite clay
• surfactants such as polyoxyalkylene sorbitan oleate esters, e.g. Tween (Registered Trade Mark) an alkali
• the bleach activator in the active substrate suitably comprises at least one compound selected from a cyclic anhydride of the structural formula (I) or a lactone of the structural formula (II) below: wherein Q is a divalent organic grouping such that Q and N together with the carbonyl and oxygen functions form one or more cyclic structures and in (I) R is H, an alkyl, aryl, halogen, a carboxylic or a carbonyl containing function, and in (II) R is a C 2 or higher alkyl, alkaryl, aryl, aralkyl, alkoxyl, haloalkyl, amino, amino alkyl, dialkyl amino, carboxylic or a carbonyl-containing function.
• Q is a divalent organic grouping such that Q and N together with the carbonyl and oxygen functions form one or more cyclic structures and in (I) R is H, an alkyl, aryl, halogen, a carboxylic or a carbonyl containing
• Bleach activators of formula (I) are claimed and described in our published EP-A-331300 and those of formula (II) are claimed and described in our published EP-A-332294 and are incorporated herein by reference.
• such compounds include bleach activators such as 2-hydrocarbyl (4H) 3,1-benzoxazin-4- ones (especially the 2-methyl and 2-aryl derivatives), the 2-N,N-dialkylamino (4H) 3,1-benzoxazin-4-ones (especially the 2-N,N-dimethyl derivative) and isatoic anhydride and its homologues and derivatives.
• bleach activators described in published EP-A-170386 N-alkoyl-6-aminoperoxycarboxylic acids and their salts
• GB-A-2832021 tetraacetyl ethylene diamine
• aqueous medium as used herein and throughout the specification is meant to include the aqueous alkaline medium encountered in a wash cycle or during a washing procedure.
• the metal salts of inorganic acids which can be used to form the encapsulating coating must be soluble in the aqueous medium although it would be advantageous if they are soluble in water.
• the solubility should preferably be at least 3g/100g of the aqueous medium at ambient temperatures, eg 15°C, although the greater the solubility, the better.
• examples of such compounds include the water soluble carbonates, sulphates and phosphates of the metals in Groups I-III of the Periodic Table, especially the alkali metals, some alkaline earth metals such as magnesium, zinc and Group III metals such as aluminium. Particularly preferred are the sulphates and phosphates of sodium, potassium, zinc and aluminium. Whichever metal salt is chosen, the salt should be such that it is capable of forming an encapsulating barrier coating on the active substrate.
• activators of the structure type (II) especially if the compound is a 2-aryl substituted benzoxazin-4-one, such activators cause dye damage.
• the performance of such activators can be improved by using an encapsulating coating of a zinc salt such as zinc sulphate.
• activators of the type (I) ie those having an isatoic anhydride type structure, the problems of staining and dye damage can be mitigated by using an encapsulating coating of an aluminium salt such as aluminium sulphate.
• the encapsulating coating should suitably form a minor proportion of the encapsulated product. That is, the active substrate should be at least 50% w/w of the encapsulated product, preferably greater than 65% w/w of the encapsulated product and most preferably from 65-80% w/w.
• the thickness of the coating encapsulating the active substrate is suitably such that it does not peel off or is not readily removed by attrition and is preferably at least 0.03 micrometers.
• the encapsulation should however be such that it completely covers the active substrate coated.
• the active substrate is suitably in the form of a powder or granules prior to encapsulation.
• the initial particle size of the substrate should be preferably from 50-200 micrometers for the powder and from 200-2000 micrometers for the granules.
• Substrates having particle sizes within this range can be produced from commercially available material by milling and/or grinding, granulation or preferably by the technique of extrusion and spheronisation.
• the powder or granules of the active substrate they may be in the form of a composite comprising the bleach activator, binders, dispersing aids, surfactants and fillers as described above.
• the encapsulating coating can be applied on the substrate by conventional means. It is preferable to create a fluidised bed of the substrate particles and to spray them with a solution of the metal salt. In using this technique the conditions should be controlled carefully in order to achieve satisfactory encapsulation. For instance, the fluidisation of the substrate particles should be such that they float in the fluidising medium as separate and distinct particles for a sufficiently long time in the coating environment so as to enable the spray of the metal salt to substantially completely encapsulate and hermetically seal substantially all of the particles individually. At the same time the residence time within the coating environment and the temperature within the coating environment should be such that before the encapsulated particles emerge from the environment they are substantially dry and resistant to (a) loss of coating by attrition and (b) agglomeration.
• a fluidising medium is also important in that it should be substantially inert to the encapsulating process and should not adversely affect the nature of the substrate being encapsulated or the encapsulating coating.
• An example of a suitable fluidising medium is air.
• the above components were formed into a dough in water and subjected to extrusion followed by spheronisation to obtain granules having a particle size of 500-1000 micrometers.
• the granules were then fluidised in a Strea-1 fluidiser at a spray rate of about 6g/min through two-fluid nozzle with atomising air pressure of about 0.8 bar.
• Air was used as the fluidising medium at an air volume of 10 units on Strea 1.
• the inlet air temperature was 48 °C and the outlet air temperature was 36 C.
• a solution of 150g of anhydrous sodium sulphate in 700g of water was used as the encapsulating solution.
• This sodium sulphate solution was sprayed in a direction cocurrent with the fluidising air using a Wurster column. The spraying of the solution took about 1.5 hours to encapsulate the granules. The encapsulated granules were then dried for a further 20 minutes during which time the temperature was increased to 52 ° C at the inlet and 46 ° C at the outlet to bake the encapsulating coating into a solid, dry barrier.
• the encapsulated granules so produced were mixed at a concentration of 5% w/w with a detergent powder containing 80% w/w ECE Base (ex Westlairds Limited, North Green, Datchet, Slough SL3 9JH, Berkshire, UK) and 15% w/w of a perborate bleach and stored in open packs at 37°C and 70% relative humidity.
• the resultant detergent formulation did not suffer any discolouration or substantial loss of activity after storage for 2 months.
• solubility of the coating in the aqueous medium is unaffected is illustrated by a comparison of coated and uncoated spheres made with the above formulation where it can be seen that there is no significant difference between whole and crushed spheres:
• Granules containing 80% isatoic anhydride bleach activator were encapsulated with the inorganic salts detailed below. These coated granules (20 parts) were mixed with a phosphate-free detergent base which contained 25% sodium perborate monohydrate (80 parts). Samples from the detergent formulations thus prepared were then spread in narrow strips of ca. 2cm width onto a test cloth of white cotton (EMPA 221). This cloth had previously been placed in a tray and dampened with sufficient water to absorb into and dampen the strips of detergent formulation. After 30 minutes the cotton test cloth was thoroughly rinsed in running tap water and air dried.
• EMPA 221 white cotton
• Granules containing 82% 2-phenyl benzoxazine-4-one (2PB4) bleach activator were encapsulated with the inorganic salts detailed below. These coated granules (20 parts) were mixed with a phosphate-free detergent base which contained 25% sodium perborate monohydrate (80 parts). Samples from the detergent formulations thus prepared were then spread in narrow strips of ca. 2cm width onto a test cloth of cotton dyed with immedial black (EMPA 115). This cloth had previously been placed in a tray and dampened with sufficient water to absorb into and dampen the strips of detergent formulation. After 30 minutes the cotton test cloth was thoroughly rinsed in running tap water and air dried. The above test was repeated.
• 2PB4 2-phenyl benzoxazine-4-one

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• Chemical & Material Sciences (AREA)
• Wood Science & Technology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Detergent Compositions (AREA)
• Formation Of Insulating Films (AREA)
• Laminated Bodies (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Nitrogen And Oxygen As The Only Ring Hetero Atoms (AREA)
• Cosmetics (AREA)

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Cited By (24)

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Citations (5)

• 1990
  • 1990-10-23 GB GB909023000A patent/GB9023000D0/en active Pending
• 1991
  • 1991-10-14 AT AT91309432T patent/ATE131864T1/de not_active IP Right Cessation
  • 1991-10-14 ES ES91309432T patent/ES2081441T3/es not_active Expired - Lifetime
  • 1991-10-14 DE DE69115637T patent/DE69115637T2/de not_active Expired - Fee Related
  • 1991-10-14 EP EP91309432A patent/EP0482807B1/fr not_active Expired - Lifetime
  • 1991-10-22 CA CA002054003A patent/CA2054003A1/fr not_active Abandoned
  • 1991-10-23 JP JP3275708A patent/JPH04314799A/ja active Pending

Patent Citations (5)

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