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Do You Want to Know What Happen to Your EPS Raw Material

2019-11-14

Recently, many customers have responded that there is a problem with eps raw materials because they used to be very light. Now, according to the previous parameter method, the board is heavy, cracked, shrinkage and so on. And this situation is still relatively common

 

So 

      what is the cause of this phenomenon? 

      Is there a problem with the raw materials? 

      Or other reasons? 

      What is the essence of this?

 

eps raw material.jpg


An Important Factor That Can Not Be Ignored-Temperature

 

Entering the autumn and winter, the temperature is low, and the temperature is relatively 

sensitive to the EPS production process. If the board is broken, the first thing to look at is 

foaming. Once the foaming is not good, and the quality of the board is not good. Generally 

speaking, we talk about the influencing factors and more about the temperature.


eps raw material .jpg


The temperature of the pellets just pre-event from the pre- expander is generally between 

40 and 50 ° C, and some of the steam permeates into the interior of the pellet during the 

pre-expansion process. Because the temperature difference between the foam particles 

and the environment is large, the residual foaming agent and steam inside the foam 

particles are quickly condensed into a liquid, and the liquid foaming agent is dissolved 

into the polystyrene foam  particles, and the internal pressure of the foam particles is 

rapidly lowered. The inside presents a negative pressure (or partial vacuum). At this time, 

the foam particles appear soft and are easily deformed. It is impossible to make an EPS 

foam product, which must be matured after a while; after ripening, on the one hand, it 

is dried, on the other hand, the air is made. It penetrates the inside of the bubble to 

eliminate the negative pressure, balances the pressure inside and outside the bubble, 

makes the bubble round and elastic, ensures the expansion of the bubble and the fusion 

between the beads during the molding, thereby improving the quality of the EPS product.


eps raw material.jpg


Understand the mechanism of pre-fabrication and maturation, if the winter pre-fabrication 

and maturation workshops have poor heat preservation effect, the temperature is low, the 

thermal expansion and contraction, the easy particle collection is severe, and the bubble 

structure is destroyed, so it cannot rebound when    matured. At this time, the lighter weight 

plate is used, and the plate is prone to shrinkage, cracking, and the board becomes heavier. 

Generally, the curing temperature has the best value. Generally, the curing temperature is 

18~22°C, and the air penetrates the inside of the bubble. The pentane inside the bubble 

does not diffuse outward. The temperature exceeds 22 °C, and the air infiltration speed 

increases and accelerates. At the same time, the rate of out- ward diffusion of pentane is 

also accelerated; on the contrary, if the temperature is lower than 20 ° C, the air infiltration 

rate is also significantly reduced, and the curing time is lengthened. For this reason, the 

general curing temperature is controlled between 20 and 25 ° C. If the main production 

of light board customers, the temperature of the curing workshop can be appropriately 

increased to about 28 or so.


eps raw material.jpg


If the temperature of the curing chamber is too low, in some winters, some foam factory 

insulation facilities do not do well, and the air leaks on all sides. Basic and outdoor 

temperature is similar, winter temperature is low, basically 0, so the foaming agent inside 

the bubble is liquid, can not be vaporized and expanded, resulting in shrinkage of the 

bubble, poorly finished hand feeling. 


Therefore, in winter, it is necessary to strengthen the silo insulation to make good products.


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