Resin-coated sand

Hexa, which is not suppHed with the resin, is usuaUy added either with the water as a solution or just before or immediately after the water addition. By quenching the mix with water, the resin-coated sand is cooled to a point where there is no significant reaction with the curing agent. Any reaction between the resin and the hexa in the muller affects the bonding properties of the coated sand. As the batch cools and begins to break up, more lubricant may be added, which remains on the outside of the coated grains where it is most effective. 

Proppants are solid particles used to hold open the fracture after conclusion of the well treatment. Criteria to choose the economically most effective proppant for a given set of formation conditions have been discussed (7 6). While sand is the most commonly used proppant because of its low cost, resin-coated sand, sintered bauxite, and A O particles have also been used because of their greater compressive strength and resistance to dissolution at high temperature and pH (55). While epoxy resins are most commonly used, the use of other resins such as phenol-formaldehyde has been described. 

Chem. Descrip. Diisobutyl phthalate CAS 84-69-5 EINECS/ELINCS 201-553-2 Uses Plasticizer for thermoplastic and thermoset resins solvent, plasticizer in cellophane, resin-coated sand for foundry casting, org. peroxides food pkg. adhesives, coatings, paper, cellophane, rubber articles, l6Xlil6 ... 

Resin-coated sand (e.g., Borden, Santrol, Hepworth)... 

Resin-coated sand Synthetic ceramics Total =... 

A heated metal pattern is placed over a box of thermosetting resin-coated sand. The box is inverted for a fixed time to cure the sand. The box is re-inverted, and the excess sand falls out. The shell is then removed from the pattern and joined with the other half (previously made). They are supported in a flask by an inert material ready for casting (see 1.2F). 

Mechanical attrition is used to remove most of the spent binder. First, dry attrition or abrasion processes crush lumps to grain size. Mechanical abrasion is then used to separate the binder from the sand grains. Sometimes, sand is pneumatically propelled against a metal target plate. The impact of the sand on the plate scrubs off the clay and resin coating from the sand grains. Fines are separated and removed by dry classification. 

Sand has been treated with oil-soluble organosilicon compounds to form a hydrophobic proppant (77). A double layer resin coating has also been developed. The inner layer coating the sand particle is a cured gamma-aminopropyltriethoxvsilane - hexamethylenetetramine. The outer layer is an uncured mixture of the same two chemicals which cures within the fracture to form a consolidated permeable mass holding the fracture open (78). 

To fight fire, use G-1 powder, dr)" sodium chloride, dty" sodium carbonate, dry calcium carbonate, dry sand, resin-coated sodium chloride, or dry soda ash. Never use water, graphite, carbon dioxide, halocarbons, or foam. 

The resin used for pre-coating is a phenolic "novolac", with a formaldehyde/phenol ratio lower than 1. Hexamethylenetetramine is added to the resin as a hardener. Hexa decomposes at 160 C into its 2 basic components formaldehyde and ammonia. When pre-coated sand contacts the heated pattern, the hexamethylenetetramine decomposes and the formaldehyde cross-links the resin binder to form the characteristic strong bond. 

Shell emissions Compared to the hot-box process, cured sand consumption is very low. However, the pre-coated sand contains 2 to 3 times more resin, but as the pattern temperatures are approximately the same, the resulting impact on working conditions is... 

Chem. Descrip. 100% Acidic latex resin Uses Acrylic for architectural coatings, sanding sealers Features Versatile offered at an acidic pH to reduce tannin bleed in clear sealers good hardness useful where low color is desired Properties Dens. 8.7 Ib/gal vise. 60 cps acid no. 33 pH 4.8 VOC 0 g/l hardness (Sward) 34 43% solids NeoCryl A-6109 [NeoResins]... 

Proppants hold the fracture walls apart to create conductive paths for the natural gas to reach the wellbore. Silica sands are the most commonly used proppants. Resin coating the sand grains improves their strength. 

Both cold- and warm-coating processes employ solutions of phenoHc resins. The principal process used for foundry resins is the hot-coating process. It is the fastest, least expensive, and safest process, and it requires no volatile removal. The sand is heated to 135—170°C in a muller, and soHd novolak resin in flake form is added, which melts quickly and coats the sand. A lubricant may be added at this point. After one minute of mulling, the batch is cooled by adding water, which evaporates rapidly. 

Several coats of resin are applied to the prepared substrate at approximately 4- to 6-hour intervals, with one or more coats being dressed with colored paint flakes which are sealed in by the next coat and then lightly sanded. This type of flooring was widely marketed about ten years ago but, in the main, they were considered unsatisfactory due to rapid discoloration of the floor because of the lack of ultraviolet stability of the urethane resins used, which rapidly turned yellow-brown and looked dirty. However, ultraviolet-stable urethane resins that do not suffer this discoloration are now available, and this type of durable decorative flooring is gaining re-acceptance (for example, for kitchens, toilets and reception areas). 

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