Core-sheath particle for use as a filler for feeder masses
The present invention relates to a core-sheath particle for use as filler for feeder compositions for the production of feeders, comprising (a) a carrier core which has a size within a range of from 30 μm to 500 μm and consists of a material which is maximally resistant up to a temperature of 1400° C. and does not contain any polystyrene, (b) a sheath which encloses the core and consists of or comprises (b1) particles having a D 50 value for the particle size of at most 15 μm, which are resistant up to a temperature of at least 1500° C., and (b2) a binder which binds the particles to one another and to the carrier core, the core-sheath particle being resistant up to a temperature of at least 1450° C.
1. Feeder comprising a cured feeder composition,
said cured feeder composition comprising:
a multitude of core-sheath particles being resistant up to a temperature of at least 1500° C.,
wherein said core-sheath particles comprise:
(a) a carrier core which has a size within a range of from 30 μm to 500 μm and is formed of a material which is resistant up to a temperature of at most 1400° C.
and does not contain any polystyrene,
wherein the carrier core (a) consists of glass material and
wherein the carrier core (a) is a hollow sphere or a porous particle,
(b) a sheath which encloses the core and consists of or comprises
(b1) particles having a D50 value for the particle size of at most 10 μm,
which are resistant up to a temperature of at least 1600° C.,
wherein the particles (b1) consist of one or more materials selected from the group consisting of aluminum oxide, silicon carbide and mullite
and
(b2) a cured binder that binds the particles (b1) to one another and to the carrier core (a), wherein said binder is a polyurethane cold box binder
and
a cured binder binding the core-sheath particles together, wherein said binder is identical to the binder (b2).
2. The feeder according to claim 1 , wherein said carrier core (a) is formed of fine-pored foam glass.
3. The feeder according to claim 1 , wherein said binder (b2) is a polyurethane cold box binder produced from a benzyl ether resin and a polyisocyanate.
4. The feeder according to claim 1 , having a density of 0.7 g/cm 3 or less.
5. The feeder according to claim 1 , wherein said feeder composition further comprises a readily oxidizable metal and an oxidizing agent therefore, for the exothermic reaction with one another.
6. The feeder according to claim 1 , wherein said particles (b1) are resistant up to a temperature of at least 1850° C.
7. The feeder according to claim 6 , wherein said particles (b1) consist of one or more materials selected from the group consisting of aluminum oxide and silicon carbide.
8. The feeder according to claim 7 , wherein said particles (b1) consist of aluminum oxide and are resistant up to a temperature of at least 2050° C.
9. The feeder according to claim 7 , wherein, said particles (b1) consist of silicon carbide and are resistant up to a temperature of at least 2300° C. and have a D50 value for the particle size of approximately 5 μm.
10. The feeder according to claim 1 , wherein:
said carrier core (a) is formed of fine-pored foam glass;
said particles (b1) are resistant up to a temperature of at least 1850° and consist of one or more materials selected from the group consisting of aluminum oxide and silicon carbide; and
said binder (b2) is a polyurethane cold box binder produced from a benzyl ether resin and a polyisocyanate.
11. The feeder according to claim 10 , wherein said particles (b1) consist of aluminum oxide and are resistant up to a temperature of at least 2050° C.
12. The feeder according to claim 10 , wherein said particles (b1) consist of silicon carbide and are resistant up to a temperature of at least 2300° C. and have a D50 value for the particle size of approximately 5 μm.
13. The feeder according to claim 10 , having a density of 0.7 g/cm 3 or less.
14. The feeder according to claim 10 , wherein the feeder composition further comprises a readily oxidizable metal and an oxidizing agent therefore, for the exothermic reaction with one another.
15. Process for producing a feeder according to claim 1 , comprising:
molding a feeder composition into a feeder, wherein the feeder composition comprises
a multitude of core-sheath particles being resistant up to a temperature of at least 1500° C., wherein said core-sheath particles comprise:
(a) a carrier core which has a size within a range of from 30 μm to 500 μm and is formed of a material which is resistant up to a temperature of at most 1400° C.
and does not contain any polystyrene,
wherein the carrier core (a) consists of glass material and
wherein the carrier core (a) is a hollow sphere or a porous particle,
(b) a sheath which encloses the core and consists of or comprises
(b1) particles having a D50 value for the particle size of at most 10 μm,
which are resistant up to a temperature of at least 1600° C.,
wherein the particles (b1) consist of one or more materials selected from the group consisting of aluminum oxide, silicon carbide and mullite
and
(b2) a cured binder that binds the particles (b1) to one another and to the carrier core (a), wherein said binder is a polyurethane cold box binder,
and
a curable binder for binding the core-sheath particles together, wherein said binder is identical to the binder (b2);
and curing the molded feeder.
16. The process according to claim 15 , wherein molding takes place according to the cold-box process.
17. The process according to claim 15 , wherein said feeder is cured by adding dimethylpropylamine.
18. The process according to claim 15 , wherein said particles (b1) are resistant up to a temperature of at least 1850° C.
19. The process according to claim 15 , wherein said feeder has a density of 0.7 g/cm 3 or less.
20. The process according to claim 15 , wherein said feeder is an exothermic feeder.