Calcium carbonate (CaCO3) is the most widely used, convenient, and inexpensive inorganic filler in the plastics industry. Using CaCO3 to fill and modify plastics not only reduces costs and saves petroleum resources, but also improves the creep resistance, heat deflection temperature, dimensional stability, and processing performance of the products.

Calcium carbonate (CaCO3) is the most widely used, convenient, and inexpensive inorganic filler in the plastics industry. Using CaCO3 to fill and modify plastics not only reduces costs and saves petroleum resources, but also improves the creep resistance, heat deflection temperature, dimensional stability, and processing performance of the products. CaCO3 is divided into heavy calcium carbonate (HCC) and light calcium carbonate (LCC) depending on the production method. HCC is produced by selecting, crushing, and grading calcium carbonate ore, such as calcite or marble. This method is simple, energy-efficient, and low-cost. LCC, however, is chemically produced through limestone calcination, lime digestion, and carbonation to generate calcium carbonate, followed by dehydration, drying, and sieving. The production process of LCC shows that its cost is higher than that of ordinary HCC, and it is also more polluting and energy-intensive. However, in terms of raw material resources, LCC has more abundant resources. Currently, the ratio of HCC to LCC used in the plastics industry in developed countries is 17-20:1, mainly HCC, while in China, the ratio is only about 2:1, lower than that in developed countries. With the increasing application of CaCO3 in plastics and the advancement of HCC processing equipment and grading methods, the production of ultra-fine HCC is no longer difficult. The future trend is to replace LCC with HCC. However, currently, whether to use HCC or LCC in plastics is a common concern for CaCO3 manufacturers and users. Therefore, we conducted a comparative study on the application of HCC and LCC in several plastics and obtained meaningful results. In this paper, HCC, LCC, and mixed calcium carbonate (HCC:LCC = 1:1) were used to fill and modify HDPE, PP, and rigid PVC. The tensile strength, impact strength, and density of the filled systems were compared, and some beneficial results were obtained. 1 Experimental Section 1.1 Raw Materials Polypropylene (PP), S-1003, product of Beijing Yanshan Petrochemical Co., Ltd. High-density polyethylene (HDPE), 5000S, product of Beijing Yanshan Petrochemical Co., Ltd. Polyvinyl chloride (PVC), SG-8, product of Beijing Chemical Plant No. 2 Co., Ltd. Heavy calcium carbonate (2% aluminate ester activation treatment), 400 mesh, Fujian San Nong Calcium Carbonate Co., Ltd. Light calcium carbonate (after passing through a 400-mesh sieve, treated with 2% aluminate ester), Fujian San Nong Calcium Carbonate Co., Ltd. Other auxiliaries are industrial products