EP0550577A1 - Traitement de l'hydroxyde de magnesium et son utilisation comme charge de plastique - Google Patents

Traitement de l'hydroxyde de magnesium et son utilisation comme charge de plastique

Info

Publication number
EP0550577A1
EP0550577A1 EP91917246A EP91917246A EP0550577A1 EP 0550577 A1 EP0550577 A1 EP 0550577A1 EP 91917246 A EP91917246 A EP 91917246A EP 91917246 A EP91917246 A EP 91917246A EP 0550577 A1 EP0550577 A1 EP 0550577A1
Authority
EP
European Patent Office
Prior art keywords
particles
magnesium hydroxide
surface area
average surface
etching solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91917246A
Other languages
German (de)
English (en)
Inventor
Stephen Clifford 20 Ratcliffe Close Brown
Frederick Horace 6 Nightingale Place Taylor
Natalie Georgina 31 Grosvenor Avenue Mead
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rio Tinto Alcan International Ltd
Original Assignee
Alcan International Ltd Canada
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcan International Ltd Canada filed Critical Alcan International Ltd Canada
Publication of EP0550577A1 publication Critical patent/EP0550577A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/02—Compounds of alkaline earth metals or magnesium
    • C09C1/028—Compounds containing only magnesium as metal
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/14—Magnesium hydroxide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • the present invention relates to fire retardant fillers for plastics materials based upon magnesium hydroxide.
  • fire retardant is intended to include the terms “flame retardant” and “smoke suppressant”.
  • magnesium hydroxide is for many applications a superior fire retardant additive for plastics materials to the commonly-used aluminium hydroxide, usually referred to as aluminium trihydrate "ATH", in view of its greater thermal stability and its higher enthalpy of decomposition.
  • ATH aluminium trihydrate
  • Higher stability allows the use of higher plastics processing temperatures and thus enables a filler based on magnesium hydroxide to be used in a wider range of polymers, especially polypropylene and thermoplastic polyamides such as nylon which are difficult, if not impossible, to fill with aluminium hydroxide.
  • Even with other polymers the use of processing temperatures which are higher than can be tolerated by aluminium hydroxide can enable increased plastics throughputs to be achievable and hence improve the economics for the plastics formulating process.
  • magnesium hydroxide gives rise to two major dif iculties. Firstly, during processing of the liquid plastics precursors or thermoplastic melts the addition of magnesium hydroxide greatly increases the viscosity of liquid and thus imposes a lower maximum filler loading for the finished plastics material than is usually desired.
  • the second disadvantage relates to the physical properties of the finished plastics materials when filled with magnesium hydroxide. Generally they have reduced impact strength and elongation, and are more difficult to shape. Both of these disadvantages apply particularly to the cheapest form of magnesium hydroxide currently available, namely that derived from sea water, and are considered to arise because of the unfavourable surface characteristics of the magnesium hydroxide particles.
  • the present invention seeks therefore to provide a relatively inexpensive route to magnesium hydroxide which possesses substantially equivalent flame retardant properties as compared to the magnesium hydroxide currently available, whilst at the same time not increasing unduly the viscosity of the liquid plastics precursors or thermoplastics melts into which the magnesium hydroxide particles are incorporated.
  • a method of producing magnesium hydroxide particles of reduced average surface area which method comprises contacting particles of magnesium hydroxide of a relatively high average surface area with an etching solution for a time sufficient to dissolve at least some of the particles and to leave particles of reduced average surface area.
  • the present invention also provides magnesium hydroxide particles of reduced average surface area when produced by a method as described in the aforesaid paragraph, and also plastics materials comprising as a flame retardant filler magnesium hydroxide particles when produced by this process.
  • the etching solution can be a solution of an organic or inorganic acid, such as acetic acid or dilute aqueous sulphuric acid, or a dilute aqueous solution of an ammonium salt such as ammonium chloride.
  • the solution may be used at room temperature or at an elevated temperature, including its boiling point.
  • the length of time during which the magnesium hydroxide particles are left in contact with the etching solution will depend upon the type and strength of solution used, the temperature and amount of solution used, and upon the degree of reduction in average surface area that is required, although excessively long contact times should be avoided since otherwise substantial dissolution of the particles can occur thereby reducing the yield of product and increasing its cost.
  • 2 treated particles should be less than 20 m /g and
  • magnesium hydroxide is preferably derived from sea water, it can also be obtained from any other source, .for example brine.
  • magnesium hydroxide powder was treated under varying conditions in accordance with the present invention and the change in average surface area measured.
  • the magnesium hydroxide powder used was that derived from sea water and sold commercially by Steetley Minerals Limited. Prior to treatment, it was found that the average surface area of
  • the powder was approximately 30 m /g.
  • Example 1 the dilute sulphuric acid was at room temperature and had a concentration of 1 M.
  • Example 6 the dilute sulphuric acid had a concentration of 1 M but was maintained at its boiling point throughout the time that it was in contact with the magnesium hydroxide particles.
  • the concentration of the dilute sulphuric acid was 2 M and it was left at room temperature during its contact with the magnesium hydroxide particles.
  • the median particle size of the magnesium hydroxide prior to treatment was about 7 microns, and it was found that after treatment the particle size distribution of the various samples was not substantially different from that of the material prior to treatment.
  • a sample of Mg(0H) 2 with reduced average surface area was produced using the following method:- 2.5 kg of Mg(0H) 2 was added to 12.51 of 1.5 molar sulphuric acid. The mixture was stirred for 1.5 hours and then allowed to settle. Once settlement had occurred excess liquid was poured off, replaced with de-ionised water and the mixture stirred. The solution was again allowed to settle and the excess liquid again poured off and replaced with de-ionised water. This washing sequence was repeated four times. The resulting slurry was then dried at 105°C overnight. This procedure reduced the surface area as measured by the Strohlein method using
  • Magnesium hydroxide was prepared according to the procedure of Example 12 and compounded into a polypropylene sold by ICI under the designation "GMW213" using an APV twin screw extruder (type number MP2030, length/diameter ratio 25:1). For comparison a second compounding run was then carried out using the same magnesium hydroxide starting material as in Example 12 but without the described treatment. Both treated and untreated compounding runs had the same throughput rate, feeder speed, screw speed, die pressure and die temperature, but the sample containing the treated Mg(0H) 2 required a compounder drive torque of only 47 of the maximum permissible whilst the sample containing the untreated feed material required 53 of maximum torque. This demonstrates the improved processing characteristic of the treated product.
  • Treated magnesium hydroxide prepared according to Example 12 was tested for viscosity in de-ionised water and compared with the untreated feed magnesium hydroxide. Both slurries contained 33% by weight of magnesium hydroxide and were measured at 20°C using a Brookfield RVT viscometer with spindle "2" at 100 rpm. The treated magnesium hydroxide had a viscosity of 36 centipoise whereas the untreated feed product had a viscosity of 44 centipoise.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

L'invention décrit des charges ignifuges améliorées destinées à des matériaux plastiques, qui sont constituées par des particules d'hydroxyde de magnésium à surface moyenne réduite. On produit ces particules en mettant en contact des particules d'hydroxyde de magnésium de surface moyenne relativement élevée, avec une solution d'attaque pendant une durée suffisante pour dissoudre au moins quelques unes des particules et laisser les particules à surface moyenne réduite.
EP91917246A 1990-09-26 1991-09-25 Traitement de l'hydroxyde de magnesium et son utilisation comme charge de plastique Withdrawn EP0550577A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB909020938A GB9020938D0 (en) 1990-09-26 1990-09-26 Plastics fillers
GB9020938 1990-09-26

Publications (1)

Publication Number Publication Date
EP0550577A1 true EP0550577A1 (fr) 1993-07-14

Family

ID=10682776

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91917246A Withdrawn EP0550577A1 (fr) 1990-09-26 1991-09-25 Traitement de l'hydroxyde de magnesium et son utilisation comme charge de plastique

Country Status (5)

Country Link
EP (1) EP0550577A1 (fr)
AU (1) AU8540091A (fr)
GB (1) GB9020938D0 (fr)
WO (1) WO1992005113A1 (fr)
ZA (1) ZA917643B (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9415851U1 (de) * 1994-09-30 1995-08-03 Siemens AG, 80333 München Schleifring- bzw. Kommutatormotor
WO2007117840A2 (fr) * 2006-03-31 2007-10-18 Albemarle Corporation Hydroxyde de magnésium comprenant des performances améliorées de mélange et de viscosité
EP2001800A2 (fr) * 2006-03-31 2008-12-17 Albermarle Corporation Hydroxyde de magnésium à performances de compoundage et de viscosité améliorées

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE370157C (de) * 1921-03-12 1923-02-27 Fritz Schneider Verfahren zur Herstellung eines Rostschutzanstriches
US2168228A (en) * 1936-12-28 1939-08-01 Carey Philip Mfg Co Suspension of magnesium hydroxide and materials and process for making same
JPS5440101B2 (fr) * 1974-06-24 1979-12-01
GB1514081A (en) * 1975-05-30 1978-06-14 Kyowa Chem Ind Co Ltd Particulate magnesium hydroxide

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9205113A1 *

Also Published As

Publication number Publication date
ZA917643B (en) 1992-05-27
GB9020938D0 (en) 1990-11-07
WO1992005113A1 (fr) 1992-04-02
AU8540091A (en) 1992-04-15

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