Precipitated calcium carbonate rubber

Calcium carbonate is one of the most versatile mineral fillers and is consumed in a wide range of products, including paper, paint plastics, rubber, textiles, caulks, sealants, and printing inks. High purity grades of both natural and precipitated calcium carbonate meet the requirements of tile Food Chemicals Codes and the United Stales Pharmacopeia and are used in dentifrices, cosmetics, foods, and pharmaceuticals. 

Absorption of C02 in aqueous slurry of lime for the manufacture of precipitated calcium carbonate (which is reused in large quantities as a rubber filler, a pigment, etc.). Here lime is sparingly soluble in water and the reaction occurs between the dissolved carbon dioxide and OH" ions. 

Calcene [PPG]. TM for a specially prepared precipitated calcium carbonate for use in compounding rubber, paints, and plastics. The particles of grade TM are coated with stearic acid to aid in dispersion. Grade NC is not coated. 

Figure 8.62 shows the compression set of rubber with different fillers at 1 1 proportion to rubber.Fillers, such as precipitated calcium carbonate, whiting, calcinated clay, each of which have limited interaction with the matrix give a substantially lower compression set. As the interaction between filler and the matrix... 

Chem. Descrip. Precipitated calcium carbonate CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Reinforcing agent, filler for rubber (SBR, NR, NR, CR), PVC plasti-sols, paints/coatings, extruded and molded goods, adhesives, sealants, sundries... 

Both the ground and precipitated calcium carbonates can by treated with stearic acid to control water absorption, improve dispersabUity, and promote better wetting of the flUer by rubber. Silane treatment of these fillers is not effective. However, there is an ultra-fine grade coated with carboxylated polybutadiene, which reactively links to the particle surfaces. Such treated ultra-fine products can give reinforcement of about the same level of the semireinforcing thermal carbon blacks. 

Prominent markets today for fine CaCOs are as fillers in paper, paint, PVC, rubber, putty, cosmetics, and toothpaste and as an antacid and a calcium supplement in foods. Surface-coated grades are also produced and are more easily dispersed in organic materials. CaCOs is also used to coat paper, and its use as a filler has increased rapidly with the increase in alkaline papermaking. Many small precipitation plants now operate at papermill sites. Controlled precipitation of calcium carbonate allows control of crystal geometry and particle size distribution. This allows custom production with attractive properties for various markets. With the recent expansion in precipitated calcium carbonate capacity, there are fewer possibilities for disposal of the relatively low-quality material from a brine plant. 

In terms of weight, calcium carbonate is the most important filler for plastics and it is also widely used in rubber and paints. Calcium carbonate is, in fact, much more than chalk (as it is universally described in the plastics industry). The term covers natural chalk, limestone, and marble - and also precipitated calcium carbonate, which has a very fine particle size, is relatively expensive, and offers some interesting properties in polymer compounds. 

Table 4.4 A comparison of a rosin and a fatty add coated precipitated calcium carbonate in a sulfur cured styrene-butadiene rubber (SBR) elastomer (100 phr filler) ...

Some precipitated calcium carbonate is also available as a by-product of water-softening plants. These grades are generally coarser with poorer control of properties and, naturally, less costly. Other precipitated calcium carbonate grades are available from 0.2 to 5 pm but do not find general applicability in rubber. 

Raw limestone is used to produce whiting (ground limestone) as an economical diluent filler in rubber compounding. It is also used as a feedstock to manufacture precipitated calcium carbonate, which is also used as a little more costly, but better, filler for extending a rubber formulation. 

Sometimes ground marble can be used as a feedstock to make calcium oxide (quicklime). This precipitated form of calcium carbonate is finer in particle size and of a significantly higher purity and cost than the ground limestone. Still, these precipitated calcium carbonates are not reinforcing fillers in that they do not significantly improve the physical properties of the cured rubber compound. 

Abstract A new low density mineral material has been synthesized via a simple, flexible, cheap and easy to control process. This material is a synthetic carbonate produced by carbonation of a solid phase composed of a calcic part and a magnesian part. Typically, its production process includes the calcination of a raw dolomite (general formula CaC03.MgC03) into the oxide form, followed by an at least partial hydration of this oxide and a subsequent carbonation step. This process is thus close to the well-known process used for the production of Precipitated Calcium Carbonate (PCC), a common filler and pigment in plastic, paper and rubber, except that the raw material is a dolomite instead of a limestone. It has to be pointed out that flue gases from different industries can be used as a source of CO2 for the carbonation. 

Type of dryer tions, extracts, milk, blood, waste liquors, rubber latex, etc. gents, calcium carbonate, bentonite, clay sbp, lead concentrates, etc. trifuged sobds, starch, etc. dry. Examples centrifuged precipitates, pigments, clay, cement. ores, potato strips, synthetic rubber. objects, rayon skeins, lumber. sheets. her sheets. 

Nonblack fillers such as the precipitated silicas can reduce both rate and state of cure. The mechanism appears to be one of a competitive reaction between rubber and filler for the zinc oxide activator. Use of materials such as diethylene glycol or triethanolamine prevents this competition thereby maintaining the desired cure characteristics. Neutral fillers such as calcium carbonate (whiting) and clays have little or no effect on the cure properties. 

Instruct others to maintain a safe distance. Wear self-contained breathing apparatus, eye protection, butyl rubber gloves, and a laboratory coat. Cover the spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. When the hydrofluoric acid has been absorbed, scoop the mixture into a plastic pail and transport to the fume hood. Slowly add to a pail of cold water. Add an excess of calcium carbonate or calcium hydroxide. Let the precipitate settle for 24 hours. Decant the solution to the drain. Allow the solid residue (calcium fluoride and bentonite) to dry and package for disposal in accordance with local regulations.7,8... 

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