Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/02—Making microcapsules or microballoons
  • B01J13/06—Making microcapsules or microballoons by phase separation
  • B01J13/14—Polymerisation; cross-linking
  • B01J13/16—Interfacial polymerisation

Definitions

• the present invention relates to a method for encapsulating substances by interfacial reaction with formation of the capsule shell in a centrifugal reactor with rotating packing.
• a core material the disperse phase
• a continuous phase By bringing the two liquid, mutually immiscible phases into contact with one another, which in each case comprise the wall-forming reactive starting materials, the chemical reaction results at the interface of the emulsion droplets, with the formation of polymeric capsule walls.
• WO 03/101606 describes the encapsulation of hydrophobic organic substances in polyurea microcapsules by interfacial polymerization, during which an aqueous phase comprising di- or polyamines and a water-immiscible phase comprising di- or polyisocyanates are brought into contact.
• US 2007/0220686 describes the microencapsulation of pigments in polyurea or polyurethane microcapsules by interfacial polymerization.
• US 6,338,838 describes the production of encapsulated light protection compositions, where the outer capsule shell is likewise produced by interfacial polymerization.
• WO 2009/091726 describes the microencapsulation of hydrophobic cosmetic substances by means of interfacial polymerization of isocyanates and amines with the formation of polyureas.
• US 7,537,644 B2 describes the use of such a reactor type for the degassing of liquids.
• This document refers to numerous publications relating to other uses of this reactor type, for example the use for producing nanoparticles from calcium carbonate.
• the object of the present invention was to find a method for encapsulating substances which helps to overcome the described disadvantages, and leads, in a simple manner and with good yields, to encapsulated products with good properties. Accordingly, a method has been found for encapsulating substances where the capsule walls are obtained by reactions at interfaces, wherein the interfacial reaction is carried out in a centrifugal reactor with rotating packing.
• the interfacial reaction takes place in a disperse system of at least two immiscible phases, in which one disperse phase A is dispersed in a continuous phase B.
• the immiscible phases are ones which spontaneously form different phases upon mixing.
• an emulsion i.e. a two-phase system, in which both the phase A and also the phase B are liquid phases, is produced in the centrifugal reactor with rotating packing in the presence of an interface-active substance.
• a phase A comprising a water-immiscible organic solvent and a starting material A
• an aqueous phase B comprising a starting material B
• a phase A is used which in turn is itself an emulsion of a water-immiscible organic solvent in water.
• the reactive starting substance A here is present in the organic phase.
• the preemulsification takes place in the presence of an interface-active substance.
• the emulsion of phase A and phase B can be of the oil-in-water emulsion type or of the water-in-oil emulsion (W/O) type.
• the substance to be encapsulated can be a hydrophilic or a hydrophobic substance.
• a hydrophilic substance to be encapsulated a water-in-oil emulsion is produced.
• an oil-in-water emulsion (O/W) is produced.
• the method according to the invention is used for encapsulating hydrophobic substances.
• the emulsion type can be adjusted via the selection of the interface- active substance.
• the emulsion type can be adjusted via the quantitative ratio of continuous phase to disperse phase.
• water-immiscible organic solvents are those solvents which spontaneously form a separate phase upon contact with water under standard conditions (at 20°C and a pressure of 0.1 MPa).
• Suitable water-immiscible organic solvents are in particular synthetic or natural aromatic or nonaromatic hydrocarbons, and also synthetic or natural oils. Suitable oils are: vegetable and animal oils, silicone oils, paraffins, triglycerides or oily monomers.
• Aromatic solvents such as benzene or toluene are also suitable. Likewise of suitability are aliphatic hydrocarbons such as Cs-Cso-alkanes.
• the capsule wall obtained by interfacial reaction is a polycondensate.
• Suitable polycondensates are preferably polyureas, polyurethanes, melamine-formaldehyde condensates, polyamides or polycarbonates.
• Suitable polycondensates are preferably polyureas, polyurethanes or a polycarbonate, in particular polyureas.
• polyureas or polyurethanes as wall material for the microcapsules.
• a di- or polyfunctional isocyanate is used as starting material A.
• a di- or polyfunctional compound from the group of amines, hydroxylamines or alcohols is used as starting material B.
• starting material A are, in particular, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, 1 ,4-phenylene diisocyanate or hexamethylene diisocyanate or mixtures thereof.
• starting material B for producing polyureas are primarily C2-C6-alkylene- diamines, in particular 1 ,6-hexamethylenediamine, or alkylenetriamines such as diethylene- triamine.
• triamines is particularly advisable if relatively high degrees of crosslinking of the capsule wall and less permeable wall material is desired.
• polycondensates can be obtained by reaction of phosgene or acid dichlorides such as sebacoyl dichloride, terephthaloyl dichloride or phthaloyl dichloride with di- or polyfunctional amines, hydroxylamines or alcohols.
• phosgene or acid dichlorides such as sebacoyl dichloride, terephthaloyl dichloride or phthaloyl dichloride
• the encapsulation takes place in the presence of at least one interface-active substance.
• Suitable interface-active substances are surfactants or emulsifiers.
• Anionic, cationic or nonionic emulsifiers for O/W and W/O emulsions can be used.
• Suitable emulsifiers for W/O emulsions can be sorbitan fatty acid esters, for example Span® types, also polysorbates, fatty acid esters of glycerol, polyglycerol esters, fatty acid esters of ethylene glycol, polyethylene glycols, amine alkoxylates (for example Quadrol®), copolymers or block copolymers of polyalkylene oxides, polyoxamines or polyisobutene-polyamine polymers (for example Glissopal®) suitable as emulsifiers.
• sorbitan fatty acid esters for example Span® types
• polysorbates also polysorbates, fatty acid esters of glycerol, polyglycerol esters, fatty acid esters of ethylene glycol, polyethylene glycols, amine alkoxylates (for example Quadrol®), copolymers or block copolymers of polyalkylene oxides, polyoxamines or polyisobut
• Suitable emulsifiers for O/W emulsions are, for example, sorbitan esters, glycerides, polyglyceryl esters or lignosulfonates. Further suitable W/0 or O/W emulsifiers are described in ⁇ . ⁇ . Fiedler, Lexikon der Hilfsstoffe [Lexicon of auxiliaries], keyword: HLB values, p. 77-82, vol. 1 , 4th edition, Editio Cantor Verlag Aulendorf).
• the emulsifiers can be used in amounts of from 0.5 to 10% by weight, based on the disperse phase.
• the amount of the disperse phase, based on the total amount of the emulsion can be 5 to 60% by weight.
• Centrifugal reactors which can be used are all devices of this type known per se which are equipped with a rotating packing. According to the invention, the centrifugal reactors are operated continuously.
• the centrifugal reactor can be operated at pressures of from 0.1 MPa to 3 MPa.
• the centrifugal accelerations are in the range from 500 to 2000 g, preferably 800 to 1500 g [m/s 2 ].
• the temperature in the centrifugal reactor can be in the range from 0 to 150°C, preferably 5 to 70°C.
• the parameters are applied cumulatively, i.e. the interfacial reaction can be carried out at pressures of from 0.1 MPa to 3 MPa and centrifugal accelerations of from 500 to 2000 g and at temperatures of from 0 to 150°C.
• the preferred ranges in each case are freely combinable with one another.
• the flow rates in the centrifugal reactor can be 1 l/min to 1000 l/min.
• the rotating packing used can be, for example, a fabric mesh which consists of metal, ceramic or a textile fabric.
• the fabric meshes can have mesh widths in the range from 0.5 to 10 mm.
• the method according to the invention is suitable for producing microcapsules which comprise a biologically active substance as substance to be encapsulated.
• Suitable biologically active substances are pharmaceutical or cosmetic substances or agrochemicals.
• the method is also suitable for encapsulating inorganic substances such as calcium nitrate or iron oxide for use as concrete ingredients.
• inorganic or organic pigments can be microencapsulated.
• Solvesso 200 aromatic solvent - light oil, boiling range 220-290°C
• Lupranat® M20S 4,4'-diphenylmethane diisocyanate
• hexamethylenediamine Packing material textile fabric, mesh width 2 mm
• Spray lances 5 bores with a diameter of 1 mm
• Diameter of the reactor drum 160 mm
• Diameter of the rotating packing 107 mm
• initial charge 1 The components in initial charge 1 were preemulsified using an oblique-blade stirrer or an Ultra-Turrax. The substances from both initial-charge containers were then sprayed at the same time onto the rotating packing via the spray lances. In the packing, a fine- emulsification of the drops and the formation of the capsules took place as a result of the reaction between isocyanate and amine. Following the capsule formation, the suspension was stirred gently for 3.5 h at 55°C in order to completely cure the capsules formed. The microcapsules obtained had average particle sizes (d(0.5), volume-average) of 2.05 pm.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Manufacturing Of Micro-Capsules (AREA)
• Polyurethanes Or Polyureas (AREA)

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• 2011
  • 2011-08-16 EP EP11177665A patent/EP2559481A1/de not_active Withdrawn
• 2012
  • 2012-08-16 CN CN201280038948.5A patent/CN103732219A/zh active Pending
  • 2012-08-16 EP EP12824551.1A patent/EP2744486A4/de not_active Withdrawn
  • 2012-08-16 WO PCT/IB2012/054172 patent/WO2013024452A1/en active Application Filing

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