Glass fiber is an inorganic non-metallic material with excellent performance. The material has very high insulation, heat resistance, corrosion resistance and mechanical strength, and is often used as a reinforcing material in composite materials, electrical insulation materials, thermal insulation materials, circuit substrates and other fields of the national economy. new material industry. Widely used in petroleum, chemical, construction, environmental protection, aviation, national defense and other fields.

The Ministry of Industry and Information Technology issued the "Specification Conditions for the Glass Fiber Industry" in July. The "Specification Conditions" covers construction layout, process technology and equipment, product quality and technological innovation, environmental protection, energy consumption, safe production, occupational health and social responsibility, supervision Management and other aspects of the glass fiber industry were standardized.

In late September, the reporter learned that China Jushi's customers notified that from October 1, 2020, the sales price of glass fiber coarse sand and products will be increased by 10%. Zhang Yuqiang, general manager of China Jushi, believes that the price of glass fiber has stopped falling and stabilized since June, and began to rebound in August. The conditions for price increase in September are already in place. In the next two years, a new round of stable growth will begin to open.

☆Classification of fiberglass

☆Fiberglass production process

Flowchart of glass fiber production process

1. Raw material processing

The production of glass fiber is inseparable from the participation of non-metallic ores. The main raw materials are pyrophyllite, quartz sand, limestone, dolomite, borosite and borosite. According to the summary table of national mineral resources and reserves (Ministry of Land and Resources in May 2016), by the end of 2015, the national pyrophyllite ore resources were identified as 99.9897 million tons, mainly distributed in Fujian, Zhejiang and Jiangxi provinces. The quartz sand resources and production enterprises are self-evident. my country's Hubei Qichun, Jiangsu Donghai, and Anhui Fengyang are important positions for quartz sand processing and application. Limestone, dolomite, borosite, boronite and other ores are rich in resources.

What should be paid attention to when choosing raw materials?

1. Homogenization of raw material powder

The homogenization of powder can be carried out in various forms. There are three commonly used methods: ①Mechanical homogenization ②Gravity homogenization ③Pneumatic homogenization.

2. Raw material powder needs to control the following elements:

①Uniformity;②Chemical Composition;③Moisture Content

Second, batch preparation

1. Process flow of ingredients

E glass powder is characterized by dry micropowder with good fluidity. It requires fully sealed operation in preparation to prevent dust from flying. Pneumatic system is used for material conveying; electronic scale is used for weighing; most of the mixing uses pneumatic mixing mixing conveying equipment. The conveying, weighing, mixing and sending of materials to the kiln head bin can be completed continuously and automatically. The batching production process is mainly composed of three parts: feeding, weighing and mixing, and conveying.

2. Main ingredients and main equipment

①Pneumatic sending tank (single bin pump); ②Screw feeder;③Pneumatic mixing tank;④Two-way distributor;⑤Electronic scale.

In addition, the batch preparation also has quality inspection content (uniform performance inspection, COD value control), batch control system and other issues.

Third, the melting of glass fiber

The melting process of glass fiber refers to the process that the batch material undergoes silicate reaction at high temperature, melts and then converts into a homogeneous glass liquid.

Melting refers to the process of solid phase fusion after batch reaction; clarification refers to the process of removing bubbles from the molten glass; and homogenization refers to reducing defects such as lines, streaks and nodules to an acceptable level The process is also the process of homogenizing the chemical composition of the glass. These processes are interleaved in stages.

Fourth, glass fiber sizing agent

In the process of glass fiber drawing, it is necessary to coat the surface of the glass fiber with a special surface treatment agent with a multiphase structure mainly based on an organic emulsion or solution.

Function: effectively lubricate the surface of glass fiber; integrate hundreds or even thousands of glass fiber monofilaments into one bundle; improve the surface state of glass fiber; provide the properties required for further processing and application; Good compatibility and interfacial chemical adsorption properties.

1. Classification of wetting agents

Reinforced sizing, textile sizing, reinforced textile sizing

2. Components of the sizing agent

The sizing agent is a system composed of a variety of organic and inorganic substances. From the outside, it can be a deep liquid, an emulsion, a thixotropic colloid or a paste. Due to its diverse functions and properties, its components are quite complex. The main components and auxiliary components included in its formula are as follows:

The main components are: ① coupling agent; ② film-forming agent; ③ lubricant; ④ antistatic agent

The auxiliary components are: ① wetting agent; ② pH regulator; ③ plasticizer; ④ cross-linking agent; ⑤ preservative or bactericide; ⑥ defoamer; ⑦ pigment

V. Forming of glass fiber< /p>

After the high temperature viscous glass liquid flows out from the leak nozzle in the form of droplets, it is drawn and solidified into continuous glass fibers of a certain diameter by the wire drawing machine below at a certain constant speed. At the lower part of the outlet of the leak nozzle, due to the balance of the surface tension and the drafting force of the molten glass, a gradually tapering part with a shape like a crescent shape is formed, which is called a silk root. From the outlet of the leak nozzle to the fiber with the same final diameter, this distance is called the fiber forming line. The section containing this fiber forming line is called the fiber forming area. The distance from the outlet of the leak nozzle to the fiber winding point on the wire drawing machine is called the wire drawing operation line, and this distance can be artificially specified to be longer or shorter depending on the process requirements.

Six, raw silk drying< /p>

In order to reduce the contact friction between the fiber and the concentrator and cable arrangement, protect the original shape of the fiber and give the fiber some special properties, the outer surface of the fiber must be passed through the oiling roller or sheave during the drawing process. Apply sizing. This sizing agent can be divided into two categories: starch type and reinforced type, the former is used for textile sand, and the latter is used for reinforced products. They are usually water lotions. In addition to the main components such as lubrication and bonding, more than 80% of the liquid is water. Generally, the moisture content of a raw silk cake is about 8% to 14% of its total weight. This moisture has adverse effects on subsequent processing procedures and products, so it must be removed.

For non-reinforced ordinary glass fiber precursors, the moisture content of the precursor fibers is allowed to be larger, and the precursor fibers take a long time from various processes such as drawing, decoupling, warping, and weaving, so only natural drying is required. It can meet the requirements of the production process and products. The specific method is to hang the raw silk on the trolley and put it in a normal room for 1 to 2 days to let it dry naturally. The raw silk can also be blown and dried with hot air (30~40℃) during de-merging.

The moisture content of reinforced glass fiber precursors must be controlled within a certain range. Generally, the moisture content is about 0.1%, and some are below 0.07%. It is difficult to achieve the above requirements with natural drying, which requires the use of special drying equipment to give artificial drying.

1. There are two main drying purposes for reinforced glass fiber strands:

①Remove the moisture in the raw silk cake to make its moisture content reach the specified index; ②After the binder in the sizing agent is heated and melted, it is converted into polymerization, cross-linking and film formation to improve the performance of the raw silk .

2. The drying process of raw silk

The drying process of glass fiber strands in the drying furnace can be roughly divided into two stages:

(1) Preheating: The preheating temperature is set to 105~120℃, and the preheating time is 1.5~3h.

(2) Drying: The drying temperature and time are determined by the requirements of various reinforced glass fiber precursors and their corresponding sizing agents. The drying temperature is in the range of 120~135℃, and the drying time is 8~18h.

3. The factors that affect the drying of glass fiber strands are:

Temperature, air volume, relative humidity, thickness and arrangement of raw silk cake, sizing agent, raw silk Tex, drying method

4. Types of drying furnaces

(1) Batch furnace; (2) Steam tunnel furnace; (3) Microwave tunnel furnace

5. The composition of the drying furnace

(1) Heat source part; (2) Furnace body structure; (3) Hot air circulation system; (4) Temperature control system; (5) Exhaust system; (6) Large tunnel drying furnace and transmission device

☆Application fields of fiberglass products