No hexa shell sand
View Patent ↗A formulation and method of use for eliminating the use of hexa in shell sand encapsulation is disclosed. The composition of matter consists of standard novalac resins with the hexa component replaced by solid granular resole or curing agent. The preferred formulation and method of compounding is given. Trace elements of ammonia, phenol and the like are further reduced by the addition of a preferred 50:50 mix of an ammonia buffer and masking agent. The preferred compounds for the ammonia buffer and masking agent mix are given.
1. A process for producing a free flowing resin coated industrial aggregate comprising
(a) adding a solid polymer curing resin to a mass of aggregate particles carrying a molten novolac resin coating in an amount sufficient to completely cure the novalac resin,
(b) mixing the mixture so formed at a temperature high enough so that the polymer curing resin coats the individual aggregate particles,
(c) quenching the mixture before substantial crosslinking of the novalac resin occurs, and
(d) drying the quenched mixture to produce the free-flowing resin coated industrial aggregate product,
wherein the solid polymer curing resin when added in step (a) is in the form of granular particles having a particles size of about ¾ inch to 40 mesh, and
further wherein the free flowing resin coated industrial aggregate product is made without addition of liquid hexamethylenetetramine.
2. The process of claim 1 , wherein the particle size of the solid polymer curing resin when added in step (a) is about ½ inch to 20 mesh.
3. The process of claim 1 , wherein the solid polymer curing resin is a phenol-aldehyde resin.
4. The process of claim 3 , wherein the solid polymer curing resin is the reaction product of a phenol-aldehyde resin and hexamethylenetetramine or a benzoxazine polymer.
5. The process of claim 4 , wherein the particle size of the solid polymer curing resin when added in step (a) is about 1 /2 inch to 20 mesh.
6. The process of claim 1 , wherein the resin coated industrial aggregate product is made without a liquid curing agent.
7. The process of claim 1 , wherein the solid polymer curing resin is added in step (a) at a temperature of about 230 to 285° F., wherein the solid polymer curing resin is the reaction product of a phenol-aldehyde resin and hexamethylenetetramine, and wherein the amount of solid polymer curing resin added is about 15 to 50%, based on the combined amount of novalac resin and solid polymer curing resin in the resin coated industrial aggregate product.
8. The process of claim 7 , wherein the resin coated industrial aggregate product is made without a liquid curing agent.
9. The process of claim 8 , wherein the amount of solid polymer curing resin added is about 30%.
10. The process of claim 8 , wherein an odor control agent comprising an organic plant extract buffering agent capable of reacting with and thereby capturing free ammonia is combined with the aggregate prior to step (d).
11. The process of claim 10 , wherein a masking agent is combined with the aggregate prior to step (d).
12. The process of claim 11 , wherein the masking agent is vanillin.
13. The process of claim 1 , wherein the industrial aggregate product is a foundry sand product in which the novalac resin and solid polymer curing resin have been combined in such a way so that, when heated to curing temperature, the foundry sand product cures into a cured mass having a tensile strength sufficient to form a foundry sand mold useful for metal casting.
14. The process of claim 13 , wherein the solid polymer curing resin is added in step (a) at a temperature of about 230 to 285° F., and further wherein the foundry sand product is made without a liquid curing agent.
15. The process of claim 14 , wherein the particle size of the solid polymer curing resin when added in step (a) is about ½ inch to 20 mesh.
16. The process of claim 14 , wherein the solid polymer curing resin is a phenol-aldehyde resin.
17. The process of claim 14 , wherein the solid polymer curing resin is the reaction product of a phenol-aldehyde resin and hexamethylenetetramine or a benzoxazine polymer.
18. The process of claim 14 , wherein the solid polymer curing resin is the reaction product of a phenol-aldehyde resin and hexamethylenetetramine, and wherein the amount of solid polymer curing resin added is about 15 to 50%, based on the combined amount of novalac resin and solid polymer curing resin in the resin coated industrial aggregate product.
19. The process of claim 18 , wherein the amount of solid polymer curing resin added is about 30%.
20. The process of claim 18 , wherein the particle size of the solid polymer curing resin when added in step (a) is about ½ inch to 20 mesh.
21. The process of claim 18 , wherein an odor control agent comprising an organic plant extract buffering agent capable of reacting with and thereby capturing free ammonia is combined with the aggregate prior to step (d), and further wherein a masking agent comprising vanillin is also combined with the aggregate prior to step (d).
22. The process of claim 13 , wherein an odor control agent comprising an organic plant extract buffering agent capable of reacting with and thereby capturing free ammonia is combined with the aggregate prior to step (d).
23. The process of claim 22 , wherein a masking agent is combined with the aggregate prior to step (d).
24. The process of claim 23 , wherein the masking agent is vanillin and further wherein approximately equal amounts of odor control agent and masking agent are added.