Page 48 - Market Analysis Report of Optical Communications Field in China & Global market 2024

CHINA
Exploration on Production Technology of PET Material
for Secondary Coating of Optical Fiber
FAN Xuanhu1, NIE Taotao2, ZHANG Yijun1, SUN Guoqing1, SI Zhengzhong1
1.Furukawa Electric Xi’an Optical Communication Co., Ltd. 2.Jiangsu Hengtong Fiber Optic Technology Co., Ltd.
Abstract: The optical cable products made of PET for optical
fiber secondary coating have high impact resistance and low
manufacturing cost, which can meet the diversified needs of
optical cable products. The several technical difficulties existing optical fibers, this article conducted a large number of PET
in the process of making PET loose tube optical cable with PET
for secondary coating of optical fiber are explored. By reasonably
setting the extrusion processing temperature of PET loose tube,
optimizing the extrusion cooling temperature and production
speed of PET loose tube, appropriately increasing the loose tube
wall thickness, reducing the cable yarn binding tension, and
quickly and fully cooling the sheath, the trial production of PET
loose tube optical cable products of multiple specifications has
been realized. After testing, the product performance indexes
of PET loose tube optical cable with outer diameter of loose
tube ≥1.8mm and wall thickness ≥0.3mm meet the requirements
of acceptance standards. Although the thermal deformation
and binding marks of these size PET loose tubes after cable
completion can not be completely eliminated, they have been
greatly improved.
Key word: polyethylene terephthalate (PET);secondary coating
of optical fiber;optical cable;process;polybutylene terephthalate
(PBT)
1. Introduction
The secondary coating of optical fibers refers to the use of
extruded sleeves or directly wrapped around the outside
of the fiber to provide a buffering and protective layer
against external impacts. It is the most important protective
structure for optical fibers. The reasonable selection of
secondary coating materials for optical fibers is crucial
to ensuring their performance. Conventional secondary
coating materials for optical fibers include polybutylene
terephthalate (PBT), polypropylene (PP), polycarbonate
(PC), etc[1]. With the rapid development of fiber optic
communication technology, the laying scenarios, uses,
and costs of optical cables are undergoing rapid changes,
gradually putting forward more diverse requirements for
the properties and costs of the materials used. Polyethylene
glycol terephthalate (PET) is a newly introduced type of
fiber optic secondary coating material that can improve the
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impact resistance of optical cable products while reducing
the manufacturing cost of optical cables. In order to
make PET better used as a secondary coating material for
production process experiments to explore its application
in the field of secondary coating for optical fibers and meet
the diverse needs of optical cable materials.
2. Overview of PET for secondary coating
of optical fibers
2.1 Structural Features
The chemical formula of PET material is
COC6H4COOCH2CH2O (C10H8O4), which is usually
synthesized by exchanging dimethyl terephthalate with
ethylene glycol ester or by esterification of terephthalic acid
with ethylene glycol, followed by condensation reaction
to obtain dihydroxyethyl terephthalate. PET material
belongs to crystalline saturated polyester, which is a highly
crystalline polymer with a smooth and glossy milky white
or light yellow surface. PET materials can be divided into
amorphous polyethylene terephthalate (APET), renewable
polybutylene terephthalate (RPET), and polyethylene
terephthalate 1,4-cyclohexanedimethanol ester (PETG).
Compared to the four methylene groups in the main
chain of conventional PBT molecules, the main chain
of conventional PET molecules only has two methylene
groups, resulting in poor flexibility, large intermolecular
forces, slow crystallization, and poor processing
performance. It cannot be used for extrusion molding and
can only be used for film production and injection molding.
But with the development of PBT synthesis technology,
modified PET for secondary coating of optical fibers has
good extrusion processing performance and has gradually
entered the field of optical cable production.
2.2 Performance Characteristics
The special molecular structure of PET used for secondary
coating of optical fibers gives it numerous excellent
properties[2]: a. Good mechanical properties, high impact
strength, and good bending resistance; b. Resistant to
oil, fat, dilute acid, dilute alkali, most solvents, soluble
in cresol, concentrated sulfuric acid, nitrobenzene,