= 7, 8 and y = 4, 5, 6) [9–11], can assist in glass design for achieving better glass mechanical properties and facilitating melting and fiber‐forming processes.
2.2 Major Fiberglass Producers
Worldwide production of E‐glass fibers reached about 7.3 million metric tons (7.3 1012 kg) in 2018 and is projected to grow continuously. The expansion of E‐glass fiber production capacity is expected to occur in parallel. Fiberglass companies can be ranked by total annual sales in volume whereas total production capacity of each company is much more difficult to find in the public domain. The current top 10 fiberglass producers globally based on sales in past 5 years are listed in Table 3. The largest rate of expansion has taken place in China, where newly built furnaces in recent years ranged from annual capacity of 30 000 metric tons to 120 000 metric tons per furnace.
Table 3 Top 10 fiberglass producers (2008 – 2013).
Source: Fiber glass market study, PPG, 2014.
| Name | Headquarter | Sales ranking | Major market | History |
|---|---|---|---|---|
| Owens Corning (OC) | US | 1 | Construction/Transportation | Since 1938 |
| China Fiberglass Co., Ltd. (Jushi) | China | 2 | Construction/Infrastructure | Since 1993 |
| PPG Industries, Inc. (PPG)a | US | 3 | Transportation/Renewable energy/Electronics | Since 1945 |
| Chongqing Polycomp International Corporation (CPIC) | China | 4 | Transportation/Renewable energy | Since 1986 |
| Johns Manville (JM) | US | 5 | Construction | Since 1958 |
| Taishan Fiberglass Inc. | China | 6 | Renewable energy/Construction | Since 1983 |
| Nippon Electronic Glass (NEG)a | Japan | 7 | Transportation | Since 1976 |
| 3B – Binani (3B) | India | 8 | Automotive | Since 1996 |
| Sichuan Weibo | China | 9 | Transportation/Infrastructure | Since 1996 |
| Taiwan Glass Group (TGG) | Taiwan | 10 | Construction | Since 1990 |
a PPG sold its Fiber Glass business to NEG in 2017, which makes NEG's rank No. 3.
3 Manufacturing of Glass Fibers
3.1 Primary and Secondary Processes
The production of glass fibers encompasses a wide range of processes, from raw‐material sourcing, batch weighing and mixing, batch‐to‐glass melting and fining, fiber drawing with the application of a water‐based organic sizing, to finally drying. Much of today's glass‐fiber production for reinforcements incorporates direct processing wherein the finished product, whether wound into a continuous spool of fiberglass strand or chopped directly after the fibers are formed and coated with sizing, is produced in one step as a part of the forming operation. Secondary downstream processes are still in use for some applications and may include twisted yarn on bobbins, roving packages made by assembling collections of smaller strands into larger strands, fibrous mats made from chopped or continuous strands bound together by mechanical or chemical binders, and chopped products for some specialty applications. The general process is sketched in Figure 2. For E‐glass fiber production, combustion technology is moving from natural gas–air or oil–air to natural gas–oxygen to achieve better energy transmission efficiency. Where C‐glass fiber is still in production, the use of syngas remains prevalent for furnace and combustion systems because of lower capital costs. For both types of fibers, electric boost technology has increased in utilization for energy efficiency and for lowering top firing and hence lowering the crown temperature of the furnace to prolong its life. The following sections briefly discuss some of the key areas of glass melting/fining, fiber drawing, and sizing chemistry design.
Figure 2 Schematic illustrations of continuous fiberglass manufacturing processes: (a) batch operation, batch melting/glass fining, and glass delivery to bushing positions, common burner locations used in the primary canal and forehearth (not shown) and (b) steps in fiber drawing and downstream processes.
Source: Fiber glass market study, PPG, 2014
.
3.2 Glass Melting and Fining
Commonly used raw materials for E‐glass fiber include sand (SiO2) as the primary silicon source, kaolin or china clay consisting of kaolinite (Al2Si2O5(OH)4) as the primary source of aluminum, limestone (CaCO3) or quicklime (burnt lime, CaO) as that calcium, and boric acid (H3BO3) as that of boron. More complex minerals are often used in place of or in combination with these major components to manage cost, improve melting performance, or utilize locally sourced ingredients. Some examples of commonly used complex minerals include pyrophyllite (Al2Si4O10(OH)2), colemanite (Ca2B6O8(OH)6∙2H2O), ulexite (NaCaB5O6(OH)6∙5H2O),