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Commonly used flame-retardant methods for wood include: spraying method, soaking method, cooking method, vacuum method, vacuum pressure method, etc. The spraying method and the immersion method are generally applied to wood surfaces that are no longer planed and flame-retardant treatment of thin plates with a thickness of less than 10mm, and are not suitable for the production of wooden fire doors.
Although the vacuum method and vacuum pressure method have excellent flame retardant effects, they have not been used in fire door manufacturers in our province because of their expensive equipment. At present, most of the fire door enterprises in our province use the cooking method for flame retardant treatment. The author believes that the following points should be paid attention to when using the cooking method for flame retardant treatment:
1. When the fire-retardant wood is dry and not wet
The moisture content of the wood to be flame-retardant is an important factor that affects the flame-retardant quality of wood. Because dry wood enters the fire-retardant pool, it is easier to absorb the fire-retardant liquid, and the amount of the fire-retardant liquid absorbed by the wood directly affects the fire-retardant quality of the wood, and its absorption is directly proportional to the oxygen index and the fire-retardant depth of the fire-retardant wood relationship. The more the wood absorbs the flame-retardant liquid, the better the wood's flame-retardant performance, the higher the oxygen index, and the deeper the flame-retardant depth. However, many companies believe that anyway, the wood will be wetted by the flame retardant liquid when it is flame-retardant, so it does not matter whether the moisture content of the wood is high or low. The wood to be flame-retardant is generally not dried. The wet square timber that has just been sawn is flame-retardant. I don't know that the moisture content of wood will affect the flame-retardant quality, and cause the flame-retardant quality of flame-retardant wood to be unstable. According to experiments, under the same flame-retardant conditions, wood with a moisture content of less than 15% can increase the oxygen index by more than 5 and the depth of flame-retardant by more than 3mm compared with wood with a moisture content of more than 40%.
2. Fire retardant first, water then wood
In the flame retardant process, most manufacturers adopt the order of loading wood→adding flame retardant→adding water→starting flame retardant. Generally speaking, when the wood absorbs the most water at the beginning, the use of this process often causes the wood to absorb a very low concentration of flame retardant liquid, so in the wood flame retardant process, it is necessary to make the wood absorb the flame retardant liquid concentration by The process from low concentration to normal concentration directly affects the dry salt absorption and absorption speed of wood, and then affects the flame retardant effect. However, in the order of adding flame retardant → adding water → loading wood → starting flame retardant, what the wood absorbs at the beginning is the standard concentration of flame retardant liquid, thus avoiding the excessive process of the flame retardant liquid absorbed by the wood from a low concentration to a normal concentration. , Thereby improving the flame retardant quality. If the company has the conditions, the flame retardant can be formulated into a flame retardant liquid with a specified concentration and then added to the flame retardant pool. The flame retardant quality will be better.
