50 Common Questions on Hot Melt Road Marking Construction, Question 2: “Drying Time”

In the scorching summer, the drying time of the markings is particularly important. Slow drying not only affects the construction progress, but also makes the markings less resistant to dirt, causing them to turn black and, in severe cases, sticking to the tire. Why do the markings dry slowly?

The reason is that when the summer temperature exceeds 33 ℃, the temperature of asphalt pavement will reach 55 ℃ -60 ℃. During extreme hot weather, the temperature of asphalt pavement can exceed 70 ℃. Assuming the surface drying temperature of the hot-melt marking coating is below or close to 60 ℃, the marking will not dry and will turn black after being rolled by the wheels. Since the reason has been found, why didn’t the material factory increase the drying temperature of the coating when designing the formula?

There are two reasons for this: Firstly, the formula design of the material factory is unreasonable. Some material factories are very unprofessional and do not even know the reason for the “slow drying”. They can only “seek medical treatment everywhere” and obtain some “life-saving additives”. After adding them, the performance of the coating is “neglected” and sometimes even has no effect at all. How can the coating be done well in this way?

2、 Some material factories are very professional, but unfortunately, in the current market environment, technicians spend their days researching how to reduce costs and minimize resin usage. In such an environment, it is impossible to produce good products or drive technological progress in the entire industry upstream and downstream. Reasonable formula design should balance the various properties of the coating based on local climate environment, traffic conditions, and other factors.
For example, based on your raw material testing, CPVC (pigment volume concentration) is 13%. Therefore, your organic content should be at least 13% or higher to achieve the minimum required performance of the coating. On the premise of meeting the basic dispersion requirements of the coating, the minimum amount of wax should be added to maximize the amount of petroleum resin used. As for plasticizers (such as white oil/pop), the minimum amount should also be added in summer. This can determine a basic formula for “quick drying” of summer coatings. Then, based on the indicators of the basic formula (material temperature, fluidity, settling, compressive strength, drying temperature, etc.) and the cost of raw materials, different indicators of raw materials such as high and low melting point wax and petroleum resin should be selected, or the same raw material with different indicators should be compounded. Finally, a cost-effective coating that meets the requirements can be designed. Not all end users in the market blindly seek the lowest price, but the current market environment has higher requirements for small and medium-sized material factories. Non standard customization, more professionalism, higher quality, and better service are the virtuous cycle.

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