EP0126039B1 - Mühle zum Dispergieren von Pigmenten in einer Trägerflüssigkeit - Google Patents

Mühle zum Dispergieren von Pigmenten in einer Trägerflüssigkeit Download PDF

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Publication number
EP0126039B1
EP0126039B1 EP84830147A EP84830147A EP0126039B1 EP 0126039 B1 EP0126039 B1 EP 0126039B1 EP 84830147 A EP84830147 A EP 84830147A EP 84830147 A EP84830147 A EP 84830147A EP 0126039 B1 EP0126039 B1 EP 0126039B1
Authority
EP
European Patent Office
Prior art keywords
casing
mill
rotor
pigment
carrier fluid
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.)
Expired
Application number
EP84830147A
Other languages
English (en)
French (fr)
Other versions
EP0126039A3 (en
EP0126039A2 (de
Inventor
Antonio Pelizza
Pietro Ponzano
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.)
Industrie Vernici Italiane SpA Te Milaan Itali
Original Assignee
INDUSTRIE VERNICI ITALIANE Srl
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 INDUSTRIE VERNICI ITALIANE Srl filed Critical INDUSTRIE VERNICI ITALIANE Srl
Priority to AT84830147T priority Critical patent/ATE38787T1/de
Publication of EP0126039A2 publication Critical patent/EP0126039A2/de
Publication of EP0126039A3 publication Critical patent/EP0126039A3/en
Application granted granted Critical
Publication of EP0126039B1 publication Critical patent/EP0126039B1/de
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/16—Mills in which a fixed container houses stirring means tumbling the charge

Definitions

  • the present invention relates to a mill of the type comprising a cylindrical casing having a predetermined internal radius and a rotor rotatably mounted within the said casing for dispersing a pigment in a carrier fluid, by means of a grinding medium, for example microspheres, contained in the said casing.
  • a necessity which arises in the paint industry is to disperse pigment in a carrier fluid, causing the breaking down and crushing of the pigment into its elementary particles, and in such a way that the carrier fluid is interposed between individual particles, completely wetting their external surfaces.
  • sand or microsphere mills of the type described above are known and widely used, in which the dispersion is effected by imparting a velocity gradient to the mixture, thereby subjecting it to a localised shearing action.
  • the grinding medium, sand, microspheres or the like, contained in the mill renders the dispersion more rapid, favouring the breaking down and crushing of the pigment.
  • mills of the type specified are that in which a plurality of rings supported from the rotor by spokes, serve to cause the desired dispersion of the pigment in the carrier fluid. Although this is advantageous from various points of view and serves the intended purpose, mills of this type require a high driving power the rotor. This is normally provided by an electric motor of approximately 40 horsepower. Furthermore, it is necessary for the pigment-carrier fluid mixture to spend a prolonged period inside the mill in order to obtain the desired degree of dispersion of the first in the second.
  • US-A-3,448.931 discloses a process for grinding solids, in particular an aqueous slurry of unmilled titanium dioxide particles by means of a great quantity of grinding medium in respect of the mill capacity (2200 Ib and 3400 Ib (1000-1543 Kg) of Ottawa sand in respect of about 250 I and 1600 I of capacity of the mill respectively in example 1 and 2) and recovering them by filtration or by use of a centrifuge.
  • This process is a preliminary phase putting at disposal a pigment, which have to be dispersed, in a subsequent phase, in a carrier fluid.
  • the problem which is at the root of the present invention is that of devising a mill of the type specified, which satisfies the said requirements while at the same time overcoming the cited disadvantages of the mills of the prior art.
  • a mill of the type specified which is characterised in that the rotor is provided with a plurality of coaxial discs, of external radius R 2 and thickness s, spaced part along the length of the rotor at a mutual spacing d between two and three times the thickness s, the difference between the internal radius R 1 of the casing and the external radius R 2 of the discs being substantially equal to the thickness s of the said discs.
  • the apparent volume of the grinding medium in the said casing that is, the volume including the free space between the microspheres or the like, is a predetermined proportion, between 30% and 40%, of the capacity of the mill.
  • reference numeral 1 indicates generally a mill according to the invention.
  • the mill 1 comprises a cylindrical casing 2, having its axis X-X disposed vertically with an internal radius R 1 and provided with opposite end walls and 4.
  • the lower end wall 3 is fixed to the casing 2 by means of dogs 5 and screws 6.
  • the upper end wall 4 is fixed to the casing 2 by means of four spaced apart columns, all indicated by reference numeral 7. There is thus defined between the casing 2 and the end wall 4 an annular aperture 8 interrupted by the said columns 7.
  • the mill 1 is provided with a wire gauze 9 extending between the casing 2 and the end wall 4, inside the columns 7.
  • the mill 1 is provided with an annular collection gutter 10 fixed to the casing 2.
  • the lower end wall 3 of the mill 1 is provided with an inlet port 11, connected to a pipe 12 through a connector 13.
  • a mixture of pigment and carrier fluid is introduced continually into the casing 2 in the direction of arrow F, through the pipe 12 and the port 11.
  • Reference numeral 14 indicates a non-return valve mounted in the inlet port 11 for permitting flow of the mixture in the direction of the arrow F and for preventing flow in the opposite direction.
  • the valve 14 is in itself entirely conventional and is therefore represented schematically and will not be described in detail.
  • the casing 2 is formed by two tubular coaxial elements 15, 16 between which an interspace 17 is defined.
  • a helical element 18 is inserted in the interspace 17 and defines therein a helical path 19 extending throughout the length of the casing 2 between two end apertures 20 and 21 formed in the outer tubular element 16, and provided with respective connectors 22 and 23.
  • a coolant fluid for example water, is made to flow through the helical path 19.
  • the casing 2 defines a cylindrical chamber 24 the axis X-X of which extends between the opposite end walls 3 and 4, and the volume of which will be referred to in the description which follows as the capacity of the mill 1.
  • a rotor 25 Within the casing 2 there is rotatably mounted a rotor 25, the axis X-X of which extends longitudinally in the chamber 24.
  • the rotor 25 has a lower end 26 spaced a short distance from the lower end wall 3, and an opposite, upper end rotatably supported in the upper end wall 4 by rolling bearings which are entirely conventional and which are not therefore shown.
  • Reference numeral 28 indicates a shaft coaxial with the rotor, fixed to the latter, and projecting from the end wall 4.
  • the shaft 28 is adapted to be connected, in a known manner, to drive means, not shown, for rotating the rotor 25 at an angular speed between 1000 and 2000 revolutions per minute, and preferably at 1450 revolutions per minute.
  • the rotor 25 is provided with a plurality of coaxial discs, each indicated 29, there being sixteen in the example described.
  • the discs 29, are all identical, have an outer radius R 2 and a thickness s and are spaced apart at regular intervals along the rotor 25.
  • the spacing d between neighbouring discs 29 is chosen to be between two and three times the thickness s while the radius R 2 is so chosen that the difference between R 1 and R 2 is approximately the same as the thickness s.
  • the rotor 25 comprises a central shaft 30 on which the discs 29 are keyed, the latter being maintained at the desired inter-disc spacing d by spacer sleeves indicated 31, having an outer radius approximately half the radius R 2 of the discs 29.
  • the spacer sleeves 31 have a radius of 30 mm.
  • the casing 25 contains a grinding medium, generally indicated by reference numeral 32, comprising microspheres or sand or the like.
  • the quantity of the grinding medium in terms of apparent volume, is chosen to be between 30% and 40% of the capacity of the mill 1.
  • a coarsely formed mixture of a pigment and of a carrier fluid in suitable mutual proportions is fed continually at a predetermined rate to the inlet port 11. This rate is to advantage chosen so that the interior of the mill contains a volumetric quantity of the said mixture substantially equal to the volume of the grinding medium 32.
  • the grinding medium 32 and the said mixture become intermixed and distributed within the chamber 24 along the internal walls of the casing 2, forming internally a surface of revolution indicated 33 and having a shape corresponding to a parabolic section.
  • the mixture which is in the casing 2 is displaced upwardly in the casing, and is subjected to the desired action of dispersion of the pigment in the carrier fluid, until it reaches the aperture 8.
  • the wire gauze 9 retains the grinding medium 32, while allowing the mixture to flow through it into the gutter 10 where it collects.
  • the resulting paraboloid has its vertex at a point on the axis X-X at a considerable distance from the lower end wall 3, approximately 9-10 metres and the combination of the grinding medium and the mixture contained in the casing 2 therefore has a thickness which is for practical purposes equal throughout the length of the casing 2.
  • the mill according to the invention has an effective shearing action on the pigment-carrier fluid mixture, causing a rapid dispersion of the first in the second, due to the fact that the combination of the grinding medium and the mixture is entirely localised at the periphery of the rotor, where the peripheral speed is highest.
  • the mill according to the invention absorbs a significantly lower power compared with mills of the prior art, for a given product load.
  • For driving the rotor it is sufficient to use an electric motor of 10 horsepower, for a productivity of the mill comparable to that of the mills mentioned in the preamble.
  • the mill according to the invention has, for a given product load, significantly smaller dimensions, with evident advantages as regards costs, both initial costs and maintenance costs.
  • the running costs are also reduced, as will be apparent when one considers that a much smaller quantity of product is lost in each production run.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Pigments, Carbon Blacks, Or Wood Stains (AREA)

Claims (2)

1. Verfahren zum Dispergieren eines Pigments in einem Trägerfluid unter Anwendung einer Mühle des Typs, umfassend ein zylindrisches Gehäuse (2) mit einem vorbestimmten Innenradius "R," und einen Rotor (25), der rotierbar innerhalb des Gehäuses befestigt ist zur Dispergierung des Pigments in dem Trägerfluid mittels einem in dem Gehäuse (2) enthaltenen Mahlmedium (32), beispielsweise Mikrokügelchen oder dergleichen, wobei der Rotor (25) mit einer Vielzahl koaxialer Scheiben (29) mit Außenradius "R2" und Dicke "s" ausgestattet ist, die entlang der Länge des Rotors (25) mit einem gegenseitigen Abstand "d", der zwischen dem zwei- und dreifachen der Dicke "s" liegt, getrennt voneinander verteilt sind, wobei die Differenz zwischen dem Innenradius "R1" des Gehäuses (2) und dem Außenradius "R2" der Scheiben (29) im wesentlichen gleich der Dicke "s" der Scheiben (29) ist, dadurch gekennzeichnet, daß das Scheinvolumen des Mahlmediums (32) in dem Gehäuse (2), d.h. das den freien Raum beinhaltende Volumen, zwischen 30% und 40% der Kapazität der Mühle beträgt, daß eine Mischung aus Pigment und Trägerfluid kontinuierlich der Mühle zugeführt wird, um in letzterer eine volumetrische Menge der Mischung beizubehalten, die im wesentlichen gleich dem Volumen des Mahlmediums (32) ist, und daß der Rotor (25) mit einer vorbestimmten Winkelgeschwindigkeit angetrieben wird, so daß das Mahlmedium (32) und die Mischung in dem Gehäuse (2) derart verteilt werden, daß im Inneren eine Rotationsfläche (33) einer Form entsprechend einem Parabolschnitt gebildet wird.
2. Mühle des Typs, umfassend ein zylindrisches Gehäuse (2) mit einem vorbestimmten Innenradius "R" und einen Rotor (25), der rotierbar innerhalb des Gehäuses (2) befestigt ist zur Dispergierung eines Pigments in einem Trägerfluid mittels einem in dem Gehäuse (2) enthaltenen Mahlmedium (32), beispielsweise Mikrokügelchen, Sand oder dergleichen, wobei der Rotor (25) mit einer Vielzahl koaxialer Scheiben (29) mit Außenradius "R2" und Dicke "s" ausgestattet ist, die entlang der Länge des Rotors (25) mit einem gegenseitigen Abstand "d", der zwischen dem zwei- und dreifachen der Dicke "s" liegt, getrennt voneinander verteilt sind, wobei die Differenz zwischen dem Innenradius "R1" des Gehäuses (2) und dem Außenradius "R2" der Scheiben (29) im wesentlichen gleich der Dicke "s" der Scheiben (29) ist, dadurch gekennzeichnet, daß das Scheinvolumen des Mahlmediums (32) in dem Gehäuse (2), d.h. das den freien Raum beinhaltende Volumen, einen vorbestimmten Anteil, zwischen 30% und 40%, der Kapazität der Mühle beträgt.
EP84830147A 1983-05-17 1984-05-14 Mühle zum Dispergieren von Pigmenten in einer Trägerflüssigkeit Expired EP0126039B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84830147T ATE38787T1 (de) 1983-05-17 1984-05-14 Muehle zum dispergieren von pigmenten in einer traegerfluessigkeit.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT2112983 1983-05-17
IT21129/83A IT1163374B (it) 1983-05-17 1983-05-17 Mulino microsfere per disperdere un pigmento in un veicolo fluido

Publications (3)

Publication Number Publication Date
EP0126039A2 EP0126039A2 (de) 1984-11-21
EP0126039A3 EP0126039A3 (en) 1985-11-21
EP0126039B1 true EP0126039B1 (de) 1988-11-23

Family

ID=11177167

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84830147A Expired EP0126039B1 (de) 1983-05-17 1984-05-14 Mühle zum Dispergieren von Pigmenten in einer Trägerflüssigkeit

Country Status (4)

Country Link
EP (1) EP0126039B1 (de)
AT (1) ATE38787T1 (de)
DE (1) DE3475277D1 (de)
IT (1) IT1163374B (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1208868B (it) * 1987-04-15 1989-07-10 Antonio Pelizza Mulino verticale a microsfere perfezionato particolarmente per la dispersione di pigmenti in veicolo fluido
ES2031789A6 (es) * 1991-06-27 1992-12-16 Oliver & Battle Sa Mejoras en el objeto de la patente principal n{ 9002766 por molino para triturar y desaglomerar solidos predispersados en liquidos.
KR100417748B1 (ko) * 1995-06-06 2004-05-31 고토부키 기켄 고교 가부시키가이샤 습식 교반 볼 밀 및 분쇄 방법
CN105170293B (zh) * 2015-09-29 2023-11-24 深圳市科力纳米工程设备有限公司 强制分散装置

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1109988B (de) * 1956-03-27 1961-06-29 Du Pont Vorrichtung zum fortlaufenden Dispergieren von Pigmenten in filmbildenden Fluessigkeiten
BE649152A (de) * 1963-06-13
GB1075926A (en) * 1965-07-31 1967-07-19 British Titan Products Milling process and apparatus
US3865316A (en) * 1973-10-23 1975-02-11 Du Pont Process for milling dyes with staurolite sand

Also Published As

Publication number Publication date
IT8321129A0 (it) 1983-05-17
EP0126039A3 (en) 1985-11-21
IT8321129A1 (it) 1984-11-17
EP0126039A2 (de) 1984-11-21
ATE38787T1 (de) 1988-12-15
DE3475277D1 (en) 1988-12-29
IT1163374B (it) 1987-04-08

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