Waterproof backing board is a widely used waterproof material in the fields of construction, underground engineering, tunnels, etc. Its process involves multiple key links to ensure the waterproof performance, durability, and construction convenience of the product. The following is the detailed process flow of waterproof backing board, which is divided into four parts: raw material preparation, production and processing, quality inspection, and construction application, totaling about 1000 words.

---

1、 Raw material preparation

The core raw materials of waterproof backing board include high molecular weight polymers (such as HDPE, PVC, TPO, etc.), reinforcement materials (such as polyester fiber, glass fiber), additives (such as antioxidants, UV absorbers, flame retardants), and adhesive layer materials (such as hot melt adhesive, pressure-sensitive adhesive). The quality of raw materials directly affects the performance of products, so strict screening is required.

1. High molecular polymer: select materials with excellent weather resistance and aging resistance to ensure that the backing plate will not be embrittled or cracked in long-term use.   

2. Reinforcement material: Polyester fiber or glass fiber mesh cloth is used to improve the tensile strength and dimensional stability of the board.   

3. Additives: Add anti UV agents (for outdoor use), flame retardants (for places with high fire prevention requirements), etc. according to the usage environment.   

4. Adhesive layer: Hot melt adhesive needs to have good initial adhesion and durability to meet the bonding needs of different substrates.

Before the raw materials are put into storage, they need to undergo sampling and testing, including indicators such as melt index, tensile strength, acid and alkali resistance, to ensure compliance with national standards (such as GB/T 23457-2017 "Pre laid Waterproof Membrane").

---

2、 Production and processing flow

The production of waterproof backing board mainly includes steps such as mixing, extrusion molding, composite reinforcement layer, surface treatment, cutting and rolling.

1. Mixing materials

Add polymer particles and additives in proportion to the high-speed mixer, mix evenly, and then feed them into the extruder hopper. The mixing temperature should be controlled between 80-120 ℃ to avoid material degradation.

2. Extrusion molding

Using a single screw or twin-screw extruder, the molten polymer is extruded into a sheet through a flat mold. Segmented control of extrusion temperature:

-Feeding section: 160-180 ℃

-Compression section: 180-200 ℃

-Homogenization section: 190-210 ℃

The mold temperature is controlled at around 200 ℃ to ensure a smooth and bubble free surface of the board.

3. Composite reinforcement layer

When the extruded sheet is not completely cooled, polyester fiber mesh cloth is compounded into the middle layer of the sheet through hot pressing process to enhance the tensile strength (up to 50-100N/cm). The composite pressure is 0.5-1.0MPa, and the temperature is maintained at 150-170 ℃.

4. Surface treatment

-Embossing treatment: By using roller pressing technology to form concave and convex patterns on the surface of the board, the bonding strength with concrete is improved.   

-Coating adhesive layer: Apply hot melt adhesive or pressure-sensitive adhesive on the back, with a coating amount of about 200-300g/m ², and cover with anti adhesive isolation film for easy removal during construction.

5. Cooling and shaping

The board is rapidly cooled and shaped by a cooling roller (water temperature 10-20 ℃) to avoid deformation. After cooling, the thickness deviation (± 0.1mm) was detected by an online thickness gauge.

6. Cutting and winding

Cut into rolls with a width of 1-2m according to customer requirements, usually 10-20m/roll, and control the winding tension between 50-100N to avoid looseness or deformation.

---

3、 Quality inspection

Each batch of products must pass the following testing items:

1. Physical properties: tensile strength, elongation at break, tear strength (refer to GB/T 328 standard).   

2. Waterproof performance: No leakage after 24 hours of 0.3MPa water pressure test.   

3. Durability: The strength retention rate after 72 hours of thermal aging at 80 ℃ is ≥ 80%.   

4. Environmental friendliness: Check whether the content of heavy metals and VOCs complies with GB 18586-2001.   

The sampling ratio is to take 3 sets of samples per 1000 square meters. Unqualified batches need to be reworked or scrapped.

---

4、 Construction application technology

The construction process of waterproof backing board includes base surface treatment, board laying, joint treatment, and protective layer construction.

1. Base treatment

Remove floating ash and oil stains from the base layer, repair cracks, and ensure a flatness of ≤ 3mm/2m. Wet substrates need to be pre coated with primer (such as epoxy resin).

2. Board laying

-Pre laying method: Lay the backing board empty on the base surface, with a lap width of ≥ 100mm, and use a hot air welding gun to weld the joints.   

-Wet laying method: After removing the isolation film, stick it directly, roll it to eliminate bubbles, and the bonding area should be ≥ 90%.

3. Seam treatment

The lap joint should be filled with specialized sealant (such as polyurethane adhesive) or hot melt welded to form a continuous waterproof layer.

4. Construction of protective layer

Pour 50mm thick fine aggregate concrete or lay geotextile on the backing board to avoid mechanical damage.

---

5、 Precautions

During storage, the rolls should be stacked upright to avoid high temperatures or direct sunlight.   

2. The construction environment temperature should be ≥ 5 ℃, and work is prohibited on rainy days.   

3. Irregular parts (such as pipe roots and internal and external corners) need to be reinforced with matching sealing materials.

Through the above process, the waterproof backing board can achieve full adhesion with the structural layer, forming a long-term stable waterproof barrier with a service life of over 20 years.

p2