XPS Extruded Board 100 Q&A - Chapter 4

Table of Contents:

1. High molecular polymer foam materials

2. The common sense of extruded board

3. The performance characteristics of the extruded board

4. Production and technology of extruded board

5. The use and construction of the extruded board

6. Other related information of extruded board

1. What is the production process of the extruded board?

The polystyrene resin, nucleating agent, combustion aid, etc. enter the first-stage plastic extruder through the feeder.

After being fully plasticized in the extruder, the foaming agent is injected (freon, gas, and environmentally friendly carbon dioxide foaming agents are also commonly used). The foaming agent is fully mixed with other raw materials in the second-stage extruder and extruded through the die after cooling.

After the die is extruded, the pressure is released rapidly, and the foaming agent wrapped in plastic expands rapidly to form closed cells. Under the action of the cells, the polystyrene plastic forms a foamed plate with honeycomb-shaped closed cells.

Then the plate is shaped to the required thickness and width through the shaping tractor and then cut into shape.

Auxiliary equipment also includes an extruded board surface roughening machine, recycling granulator, edge forming machine, slotting machine, automatic packaging machine, etc.

2. What materials will be added in the production process of the extruded board?

Polystyrene resin, foaming agent, nucleating agent, flame retardant, color masterbatch, foam stabilizer, etc.

3. What is the process of foam molding of the extruded board?

Over time, the blowing agent in the extruded board will be replaced by air.

4. What are the typical foam molding steps for thermoplastic foam materials?

Foaming agent dissolution→bubble nucleation→bubble growth and stabilization→curing and molding.

5. What is the key to bubble nucleation?

Increase the speed and density of nucleation as much as possible. The nucleation density is a key factor in determining the blasthole density.

6. Homogeneous nucleation and heterogeneous nucleation?

The formation of bubbles in a single homogeneous phase is called homogeneous nucleation. The formation of bubbles under the catalysis of the interface of fine particles is called heterogeneous nucleation.

7. What are the influencing factors in the curing and molding stage?

Cooling rate, gas precipitation from the melt, decomposition, and gasification of the blowing agent.

8. How many extruded boards can one extruded board production line produce in one day?

The general extruded board production line 24H can produce 200+m³ of extruded boards.

9. What are the flame retardants of the extruded board?

Flame retardants are divided into the additive type and reactive type. Mainly include inorganic, halogen, phosphorus, and nitrogen. The most used is hexabromododecane (HBCD).

10. What is the amount of flame retardant added?

The addition amount of B2 grade extruded board is 5%-6%, and the addition amount of B1 grade is 10%+.

11. Does the extruded board have environmentally friendly flame retardants?

Yes, but because the price is too high, there is basically no enterprise use. HBCD has been banned in developed countries such as Europe and the United States.

12. What are the foaming agents for extruded boards?

HCFC-22, HCFC-142b, carbon dioxide, butane, ethanol, dimethyl ether, liquefied petroleum gas, etc.

13. What is the classification of the foaming agent?

It can be divided into physical blowing agents and chemical blowing agents, as well as organic blowing agents and inorganic blowing agents.

14. What are the nucleating agents?

Commonly used are talc, calcium carbonate, citric acid, metal powder, etc., as well as gaseous nucleating agents such as nitrogen and carbon dioxide. Nucleating agents affect the structure and density of the foam.

15. What color is the extruded board?

The new extruded board without any color masterbatch is white. The extruded boards on the market are white, blue, red, yellow, green, etc., among which white is the highest end.

16. How to measure solid feed?

There are usually constant volume type quantitative feeding system and weight type quantitative feeding system.

17. How to feed the liquid?

The foaming agent is delivered from the storage tank to the metering pump under a fixed pressure.

18. What are the influencing factors of the foaming process?

The viscosity and elasticity of the melt, gas permeability, vapor pressure, solubility, and decomposition temperature of the blowing agent.

19. The main process parameters that affect the blowing agent?

Quantitative: The constant and balanced input of raw materials ensures that the machine head has a constant amount of material extrusion.

Constant temperature: The viscosity of the melt, whether the foaming is sufficient, and the molding are all related to the temperature.

Constant pressure: reasonable system pressure comes from a balanced quantitative and suitable temperature range.

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