Core-shell particles for use as a filler for feeder compositions

Abstract

The invention relates to core-shell particles for use as a filler for feeder compositions for producing feeders, comprising (a) a core which possesses one or more cavities and a wall surrounding these cavities, where the core (a) has an average diameter in the range from 0.15 to 0.45 mm, (b) a shell enclosing the core and consisting of or comprising (b1) particles comprising or consisting of a material from the group consisting of calcined kaolin or cordierite, where the particles (b1) have a d10 of at least 0.05 m and a d90 of at most 45 m, and also (b2) a binder which binds the particles (b1) to one another and to the core (a).

Claims

1. Core-shell particles for use as a filler for feeder compositions for producing feeders, comprising: (a) a core possessing one or more cavities and a wall surrounding the one or more cavities, where the core (a) has an average diameter in the range from 0.15 to 0.45 mm; (b) a shell enclosing the core and consisting of or comprising: (b1) particles comprising or consisting of a material selected from the group consisting of calcined kaolin and cordierite, where the particles (b1) have a d10 of at least 0.05 m and a d90 of at most 45 m; and (b2) a binder which binds the particles (b1) to one another and to the core (a).

2. The core-shell particles as claimed in claim 1, where the core (a) comprises glass or consists of glass.

3. The core-shell particles as claimed in claim 1, where the core (a) comprises silicon dioxide and aluminum oxide, the weight ratio between the silicon dioxide and the aluminum oxide being 27:1 or more, in the particles (b1) the weight ratio between the silicon dioxide and the aluminum oxide is in the range from 1:1 to 1:1.6.

4. The core-shell particles as claimed in claim 1, where (i) the core-shell particles have a d10 in the range from 0.1 mm to 0.2 mm and a d90 in the range from at most 0.30 mm to 0.40 mm, where the core-shell particles have an average particle size d50 of 0.2 mm to 0.3 mm or (ii) the core-shell particles have a d10 in the range from 0.30 mm to 0.40 mm and a d90 in the range from 0.50 mm to 0.60 mm, where the core-shell particles have an average particle size d50 of 0.4 mm to 0.5 mm.

5. The core-shell particles as claimed in claim 1, where the core (a) comprises silicon dioxide and aluminum oxide, the weight ratio between the silicon dioxide and the aluminum oxide being 30:1 or more, in the particles (b1) the weight ratio between the silicon dioxide and the aluminum oxide is in the range from 1:1 to 1:1.6.

6. The core-shell particles as claimed in claim 1, where the core (a) comprises silicon dioxide and aluminum oxide, the weight ratio between the silicon dioxide and the aluminum oxide being 45:1 or more, in the particles (b1) the weight ratio between the silicon dioxide and the aluminum oxide is in the range from 1:1 to 1:1.6.

7. The core-shell particles as claimed in claim 1, where (i) the core-shell particles have a d10 in the range from 0.1 mm to 0.2 mm and a d90 in the range from at most 0.30 mm to 0.40 mm, where the core-shell particles have an average particle size d50 of 0.22 mm to 0.27 mm or (ii) the core-shell particles have a d10 in the range from 0.30 mm to 0.40 mm and a d90 in the range from 0.50 mm to 0.60 mm, where the core-shell particles have an average particle size d50 of 0.42 mm to 0.47 mm.

8. The core-shell particles as claimed in claim 1, where (i) the core-shell particles have a d10 in the range from 0.1 mm to 0.2 mm and a d90 in the range from at most 0.30 mm to 0.40 mm, where the core-shell particles have an average particle size d50 of 0.24 mm to 0.26 mm or (ii) the core-shell particles have a d10 in the range from 0.30 mm to 0.40 mm and a d90 in the range from 0.50 mm to 0.60 mm, where the core-shell particles have an average particle size d50 of 0.44 mm to 0.46 mm.

9. The core-shell particles as claimed in claim 1, where the core (a) consists of or comprises expanded glass or foamed glass.

10. A method for producing core-shell particles as claimed claim 1, comprising: providing cores (a) which each possess one or more cavities and a wall surrounding the one or more cavities, where the cores (a) have a d50 in the range from 0.15 to 0.45 mm, providing particles (b1) comprising or consisting of a material selected from the group consisting of calcined kaolin and cordierite, where the particles (b1) have a d10 of at least 0.05 m and a d90 of at most 45 m; contacting the cores (a) with the particles (b1) in the presence of a binder (b2), so that particles (b1) are bound to the cores (a) and to one another, and individual or all the cores (a) are enveloped; and curing and/or drying the binder.

11. A method of producing a feeder or a moldable composition for producing a feeder, comprising providing the core-shell particles as claimed in claim 1 as an insulating filling material for the feeder.

12. A pourable filling material for use as a filler for feeder compositions for producing feeders, comprising or consisting of a multiplicity of core-shell particles as claimed in claim 1.

13. A moldable composition for producing feeders, consisting of or comprising: core-shell particles as claimed in claim 1; and a binder for binding the core-shell particles.

14. A feeder comprising core-shell particles as claimed in claim 1, bound by a binder.

15. A method of casting iron or steel comprising utilizing a feeder as claimed in claim 14.

Description

(1) In the context of the present invention, it is preferred for two or more of the aspects identified above as being preferred to be actualized at one and the same time; especially preferred are the combinations of such aspects and of the corresponding features that arise from the appended claims.

(2) FIG. 1 shows a scanning electron micrograph of a polished section of core-shell particles of the invention having a core of expanded glass and a shell of calcined kaolin.

(3) FIG. 2 depicts an aluminum element mapping image of the scanning electron micrograph from FIG. 1. The regions shown as light contain aluminum. It is clearly apparent here that the aluminum-containing shell particles (b1) are arranged around the core (a).

(4) FIG. 3 shows a silicon element mapping image of the scanning electron micrograph from FIG. 1. The regions shown as light contain silicon. It is clearly apparent here that both the core particles of expanded glass (SiO.sub.2) and the shell particles contain silicon.

(5) FIG. 4 shows the photograph of a cut-open cube casting with residual feeder for the cube tests described in more detail in the examples. The casting was made using a feeder produced according to working example 9. The lowest point of the cavity is located 3 mm in the casting. This gives a cavity depth of 3 mm.

(6) FIG. 5 shows the photograph of a cut-open cube casting with residual feeder for the cube tests described in more detail in the examples. The casting was made using a feeder produced according to working example 10. The lowest point of the cavity is located 18 mm above the casting in the residual feeder. This gives a cavity depth of +18 mm.

(7) FIG. 6 shows the photograph of a cut-open cube casting with residual feeder for the cube tests described in more detail in the examples. The casting was made using a feeder produced according to comparative example 3. The lowest point of the cavity is located 8 mm in the casting. This gives a cavity depth of 8 mm.

(8) FIG. 7 shows the photograph of a cut-open cube casting with residual feeder for the cube tests described in more detail in the examples. The casting was made using a feeder produced according to comparative example 4. The lowest point of the cavity is located 26 mm in the casting. This gives a cavity depth of 26 mm.

(9) FIG. 8 shows the photograph of a cut-open cube casting with residual feeder for the cube tests described in more detail in the examples. The casting was made using a feeder produced according to comparative example 5. The lowest point of the cavity is located 7 mm in the casting. This gives a cavity depth of 7 mm.

(10) The invention is elucidated in more detail below using examples and figures:

(11) A Production of Inventive Core-Shell Particles (Bulk Product):

WORKING EXAMPLE 1

(12) A BOSCH Profi 67 mixer is charged with 664 g of Liaver expanded glass (standard particle size 0.1 to 0.3 mm; Liaver GmbH und Co. KG) as carrier material and this initial charge is wetted uniformly with 72 g of cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). 136 g of calcined kaolin (d50=1.4 m, d10=0.4 m, d90=7 m) are added and the components are mixed homogeneously. Lastly around 0.5 mL of dimethyl propyl amine is added to cure the binder. After a few seconds, the core-shell particles formed are in the form of a bulk product for further use.

WORKING EXAMPLE 2

(13) A BOSCH Profi 67 mixer is charged with 640 g of Liaver expanded glass (standard particle size 0.25 to 0.5 mm; Liaver GmbH und Co. KG) as carrier material and this initial charge is wetted uniformly with 72 g of cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). 160 g of calcined kaolin (d50=1.4 m, d10=0.4 m, d90=7 m) are added and the components are mixed homogeneously. Lastly around 0.5 mL of dimethyl propyl amine is added to cure the binder. After a few seconds, the core-shell particles formed are in the form of a bulk product for further use.

WORKING EXAMPLE 3

(14) A BOSCH Profi 67 mixer is charged with 664 g of Poraver foamed glass (standard particle size 0.1-0.3; Dennert Poraver GmbH) as carrier material and this initial charge is wetted uniformly with 72 g of cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). 136 g of calcined kaolin (d50=1.4 m, d10=0.4 m, d90=7 m) are added and the components are mixed homogeneously. Lastly around 0.5 mL of dimethyl propyl amine is added to cure the binder. After a few seconds, the core-shell particles formed are in the form of a bulk product for further use.

WORKING EXAMPLE 4

(15) A BOSCH Profi 67 mixer is charged with 640 g of Poraver foamed glass (standard particle size 0.25-0.5; Dennert Poraver GmbH) as carrier material and this initial charge is wetted uniformly with 72 g of cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). 160 g of calcined kaolin (d50=1.4 m, d10=0.4 m, d90=7 m) are added and the components are mixed homogeneously. Lastly around 0.5 mL of dimethyl propyl amine is added to cure the binder. After a few seconds, the core-shell particles formed are in the form of a bulk product for further use.

(16) B Production of Comparative Core-Shell Particles (Not Inventive):

COMPARATIVE EXAMPLE 1 (NOT INVENTIVE)

(17) A BOSCH Profi 67 mixer is charged with 700 g of Poraver (standard particle size 0.1-0.3; Dennert Poraver GmbH) as carrier material and this initial charge is wetted uniformly with 120 g of cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). 300 g of silicon carbide powder (d50 for particle size: <5 m) are added and the components are mixed homogeneously. Lastly around 0.5 mL of dimethyl propyl amine is added to cure the binder. After a few seconds, the core-shell particles formed are in the form of a bulk product for further use.

COMPARATIVE EXAMPLE 2 (NOT INVENTIVE)

(18) For the carrier core, a suitable BOSCH Profi 67 mixer is charged with 560 g of Poraver (standard particle size 0.1-0.3; Dennert Poraver GmbH) as carrier material and this initial charge is wetted uniformly with 72 g of cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). 240 g of aluminum oxide powder (d50 for particle size: around 12 m) are added and the components are mixed homogeneously. Lastly around 0.5 mL of dimethyl propyl amine is added to cure the binder. After a few seconds, the core-shell particles formed are in the form of a bulk product for further use.

(19) C Production of Feeder Compositions and also Feeder Caps and other Profile Elements:

WORKING EXAMPLE 5

(20) The core-shell particles produced according to working example 1 are mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

WORKING EXAMPLE 6

(21) The core-shell particles produced according to working example 2 are mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in is each case by gassing with dimethylpropylamine.

WORKING EXAMPLE 7

(22) The core-shell particles produced according to working example 3 are mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

WORKING EXAMPLE 8

(23) The core-shell particles produced according to working example 4 are mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

WORKING EXAMPLE 9

(24) The core-shell particles produced according to working examples 1 and 2 are mixed homogeneously in a weight ratio of 4:3. The resulting mixture is mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

WORKING EXAMPLE 10

(25) The core-shell particles produced according to working examples 1 and 2 are mixed homogeneously mixed homogeneously in a weight ratio of 4:3. The resulting mixture is mixed homogeneously with particles consisting of cordierite (standard particle size<5 mm; Csk lupkov zvody, a.s.), resulting in a weight ratio of core-shell particles to cordierite particles of 7:3. This mixture is mixed homogeneously with cold box binder is (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

COMPARATIVE EXAMPLE 3 (NOT INVENTIVE)

(26) The core-shell particles produced according to comparative example 1 are mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

COMPARATIVE EXAMPLE 4 (NOT INVENTIVE)

(27) The core-shell particles produced according to comparative example 2 are mixed homogeneously with cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1).

(28) From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

COMPARATIVE EXAMPLE 5 (NOT INVENTIVE)

(29) 445 g of the core-shell particles produced according to comparative example 2 are mixed homogeneously with 250 g of aluminum (spray-atomized Al with a particle grading of <0.2 mm), 60 g of iron oxide, 220 g of potassium nitrate (flowable, commercial product; particle grading less than 2 mm), and 25 g of ignitor, and also cold box binder (from Httenes-Albertus: Benzyl ether resin based on Activator 6324/Gas resin 7241 with an Activator 6324: Gas resin 7241 ratio of 1:1). From the resulting mixture, feeder caps and other profile moldings (a) are rammed and (b) are shot using core shooting machines (e.g., Rper, Laempe). Curing takes place in each case by gassing with dimethylpropylamine.

(30) D Cube Tests:

(31) Feeder caps in accordance with the working examples and comparative examples from section C were checked for practical usefulness by means of so-called cube tests. In these tests, a casting in the form of a cube needs to be free from cavities when using a modularly appropriate feeder cap.

(32) Relatively reliable dense feeding was demonstrated for all the embodiments. In the respective residual feeders (above the cubes), the cavity behavior found was better in each case for the working examples than for the comparative examples. The cavity depths determined are reproduced in the table below. Where the cavity depth is negative, this means that the cavity is located at least partly in the casting, whereas a positive value to the cavity depth means that the cavity is formed in the respective residual feeder. The corresponding cube castings with residual feeders are depicted in FIGS. 4 to 8.

(33) TABLE-US-00001 Working Working Compara- Compara- Compara- example example tive tive tive 9 10 example 3 example 4 example 5 Cavity depth 3 +18 8 26 7 determined [mm]