Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/16—Oxyacids of phosphorus; Salts thereof
  • C01B25/26—Phosphates
  • C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
  • C01B25/327—After-treatment
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
  • A61K8/24—Phosphorous; Compounds thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses

Definitions

• the degree of stabilization is determined by means of the so-called glycerol test, wherein the DCP is pasted up with glycerol and water to give a just mobile paste, which is heated in the water bath for 30 minutes to a temperature of 100 C.
• the glycerol test is stated to be very good when, after that time, the paste is found to have an unchanged consistency. The result obtained must be considered as being insufficient when the paste is found to have hardened.
• the adjectives good, satisfactory, and sufficient are reserved to the characterization of transition grades lying between these two extremes.
• the stabilization of DCP is indispensable when it is desired substantially to reduce dehydration.
• the following compounds have inter alia been proposed for use as stabilizing agents.
• Alkali metal pyrophosphates e.g. tetrasodium pyrophosphate. They are used in a proportion of 0.5 to 1.25% by weight, referred to DCP, and they are prepared either separately in an aqueous solution to be added then to DCP, or are dissolved in the phosphoric acid necessary for preparing the DCP.
• Alkaline earth metal pyrophosphates e.g. calcium "ice pyrophosphate and magnesium pyrophosphate.
• the proportion necessary to achieve stabilization is 5% by weight for calcium pyrophosphate, and is 3% by weight for magnesium pyrophosphate.
• the calcium pyrophosphate is added to the phosphoric acid necessary for ⁇ making the DCP, whereas the magnesium pyrophosphate is prepared from MgO and pyrophosphate ions in the phosphoric acid.
• Alkali metal hexametaphosphates (l-qThese compounds are added in aqueous solution in a proportion of 0.3 to 3% by weight to the DCP in a separate operational step or during another operation, e,g, filtration.
• Alkali metal tripolyphosphates These stabilizers are used in a manner analogous to the alkali metal hexametaphosphates.
• Magnesium phosphates e.g. trimagnesium phosphate and dimagnesium phosphate. Dirnagnesium phosphate is used in a proportion of 2 to 4% by weight, the trimagnesium phosphate is used in a proportion of 0.5 to 2% by weight. In either case, the stabilization is achieved by admixing the stabilizer with dry DCP.
• the stabilizer referred to the dicalcium phosphate dihydrate
• 0.4 to 0.9% by weight, more preferably 0.8% by weight of the stabilizer, referred to the dicalcium phosphate dihydrate is added to the dicalcium phosphate during preparation, and additionally 0.2 to 0.6% by weight, advantageously 0.4 by weight, of the stabilizer is added to isolated, solid dicalcium phosphate dihydrate, and ultimately ground jointly with the solid dicalcium phosphate.
• the stabilizer portion to be added during the preparation of the dicalcium phosphate is added at a pH-value of 7.5 to 8.5, preferably at a pH-value of 8.0, and when the stabilizer portion to be added before the dicalcium phosphate is ground has a grain size approximately the same as that of the dicalcium phosphate.
• the present invention has proved especially advantageous for making stabilized dicalcium phosphate dihydrate formed of grains with a size of less than 40% from coarsely crystalline dicalcium phosphate which consists to an extent of more than 30% by weight, e.g. of 70 to by weight, of grains having a size larger than 40,14.
• the dicalcium phosphate is most advantageously admixed, during its preparation, at a pH- value of 7.5 to 8.5, with 0.4 to 019% by weight of the stabilizer, referred to the dicalcium phosphate, and the isolated, solid dicalcium phosphate dihydrate formed to an extent of more than 30% by weight of grains having a size larger than 40 is admixed then with 0.2 to 0.6% by weight of the stabilizer, referred to the dicalcium phos- TABLE II S tahilizer N arlgOy Addition prior to grinding Stabilized in reactor at pH Glycerol test 1 1.2 Sufficient.
• the pH-value was finally adjusted in a second process step while reacting the phosphoric acid in excess with calcium chloride (25-35% by weight strength) and with sodium hydroxide solution (20-50% by Wfiight strength) in stoichiometric quantitative proportions.
• the temperature in the reactor raised from initially 25-3Q C. (first step) to 40-45 C.
• the supply of calcium chloride and sodium hydroxide solution was arrested at a pH-value of 8.0. Thereafter 0.8% by "weight sodium pyrophosphate was added to achieve the stabilization.
• the finished DCP was filtered by means of a vacuum drum filter, and washed.
• the filter cake which contained about 40% by weight water of adhesion was dried in a twostage turbulent layer drier, admixed with 0.4% by weight sodium pyrophosphate, and ground in a sitter bowl mill to obtain grains of which 99.5% had a size of less than 40a.
• the sodium pyrophosphate added was formed of grains of which about to had a size larger than 40 i.e. a size approximately corresponding to that of the DCP before grinding.
• step (B) has a grain size about the same as the dicalcium phosphate dihydrate.
• step (B) is larger than 40 and the (C) step is etfected to obtain combined grain size of less than 40g.
• the stabilizer is a member selected from the group consisting of tetrasodium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, calcium-disodium pyrophosphate, alkali metal tripolyphosphates, alkali metal hexametaphosphates, dimagnesium phosphate, and trimagnesium phosphate.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Public Health (AREA)
• Organic Chemistry (AREA)
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• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Inorganic Chemistry (AREA)
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• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
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• Oral & Maxillofacial Surgery (AREA)
• Paper (AREA)
• Materials For Medical Uses (AREA)
• Cosmetics (AREA)
• Detergent Compositions (AREA)

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• 1965
  • 1965-06-16 DE DEK56393A patent/DE1259861B/de active Pending
• 1966
  • 1966-05-05 CH CH654166A patent/CH471038A/de not_active IP Right Cessation
  • 1966-05-13 SE SE6652/66A patent/SE320959B/xx unknown
  • 1966-05-18 US US551058A patent/US3464786A/en not_active Expired - Lifetime
  • 1966-05-26 NL NL666607318A patent/NL151318B/xx not_active IP Right Cessation
  • 1966-05-27 GB GB23816/66A patent/GB1089245A/en not_active Expired
  • 1966-06-08 AT AT547866A patent/AT265208B/de active
  • 1966-06-15 DK DK308566AA patent/DK113009B/da unknown
  • 1966-06-16 BE BE682627D patent/BE682627A/xx not_active IP Right Cessation

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