紙張收到水份侵蝕后，瓦楞會發(fā)生垮塌軟化現(xiàn)象，大大降低了包裝安全性。然而大部分人理解中的紙箱防水僅僅是紙箱成型后的防水問題，卻忽視了紙箱紙張本來存在的含水量問題。對于瓦楞紙板含水量的控制，應(yīng)著重哪幾方面控制呢？
瓦楞紙板防水防潮的目的，實際上還是為了維持紙箱的抗壓性能，紙張收到水份侵蝕后，瓦楞會發(fā)生垮塌軟化現(xiàn)象，大大降低了包裝安全性。然而大部分人理解中的紙箱防水僅僅是紙箱成型后的防水問題，卻忽視了紙箱紙張本來存在的含水量問題。事實上控制好瓦楞原紙含水量對提高瓦楞紙箱安全性能同樣也是至關(guān)重要的。對于瓦楞紙板含水量的控制，應(yīng)著重對以下幾方面進(jìn)行控制。
1.瓦楞原紙進(jìn)廠時的含水量應(yīng)嚴(yán)格按照gb13023-91標(biāo)準(zhǔn)進(jìn)行檢驗。
2.進(jìn)廠后對瓦楞原紙的儲存溫度應(yīng)控制在常溫狀態(tài)，相對濕度不大于40%。
3.瓦楞原紙的存放應(yīng)豎著碼垛堆放，地面應(yīng)做防潮處理。
4.瓦楞原紙的儲存時間不宜過長。控制好瓦楞紙板生產(chǎn)過程中的溫度溫度是直接調(diào)整瓦楞原紙含水量，保證粘合劑糊化的重要條件。因此，當(dāng)瓦楞紙板生產(chǎn)線在80米/分～120米/分時，通常采用的溫度應(yīng)控制在160℃～180℃之間，按其換算鍋爐的飽和蒸汽壓力應(yīng)控制在0.9mpa-1.2mpa，這樣既能調(diào)整好瓦楞原紙和單面瓦楞紙板的含水量，又能保證黏合劑的糊化。
為保證瓦楞紙板的強度和良好的粘合，對于瓦楞紙板的形成應(yīng)根據(jù)瓦楞紙板生產(chǎn)線配置的不同進(jìn)行必要的調(diào)整。
1.對于進(jìn)入單面機的瓦楞原紙含水量控制在9%～12%之間時瓦楞成型最為理想。當(dāng)瓦楞原紙含水量高于上述指標(biāo)時，可采取加大預(yù)熱面積或降低車速解決;當(dāng)瓦楞原紙含水量低于上述指標(biāo)時，可采取噴霧解決。筆者認(rèn)為，單面瓦楞紙板通過快速輸紙在天橋輸送帶上呈正∞型且堆積距離一致時，原紙和瓦楞原紙的水分調(diào)整的比較好，其含水量比較合適，單面瓦楞紙板在天橋上堆積的數(shù)量不宜過多，但為保證雙面機不停機，在單面機換紙時單面瓦楞紙板在天橋上的堆積數(shù)量可適當(dāng)增加。
2.烘干機的溫度對瓦楞紙板的含水量影響很大。瓦楞紙板生產(chǎn)線加熱段通常由三組(也有四組)組成，其加熱板數(shù)量的多少是由加熱板的尺寸及瓦楞紙板生產(chǎn)線的速度確定且每組均設(shè)有獨立的控制閥門。為保證單面瓦楞紙板進(jìn)入烘干機前的含水量基本一致，可采取調(diào)整單面瓦楞紙板在三重預(yù)熱器上的預(yù)熱面積的大小解決。其調(diào)整方法為：當(dāng)含水量過高時，預(yù)熱面積加大;當(dāng)含水量過低時，預(yù)熱面積減少。
After the paper is eroded by moisture, the corrugation will collapse and soften, which greatly reduces the packaging safety. However, most people understand that the waterproof of cartons is only the waterproof problem of cartons after forming, but they ignore the original moisture content of cartons. For the control of the water content of corrugated board, which aspects should be focused on?
The purpose of waterproof and moisture-proof corrugated board is actually to maintain the compression resistance of the carton. After the paper is eroded by moisture, the corrugated board will collapse and soften, which greatly reduces the packaging safety. However, most people understand that the waterproof of cartons is only the waterproof problem of cartons after forming, but they ignore the original moisture content of cartons. In fact, controlling the water content of corrugated base paper is also crucial to improve the safety performance of corrugated boxes. For the control of water content of corrugated board, the following aspects should be controlled.
1. The water content of corrugated base paper when entering the factory shall be tested in strict accordance with gb13023-91 standard.
2. After entering the factory, the storage temperature of corrugated base paper should be controlled at room temperature, and the relative humidity should not be greater than 40%.
3. The corrugated base paper should be stacked vertically, and the ground should be moisture-proof.
4. The storage time of corrugated base paper should not be too long. Controlling the temperature in the production process of corrugated board is an important condition for directly adjusting the water content of corrugated base paper and ensuring the gelatinization of adhesive. Therefore, when the corrugated board production line is 80 m / min ~ 120 m / min, the commonly used temperature should be controlled between 160 ℃ ~ 180 ℃. According to its conversion, the saturated steam pressure of the boiler should be controlled between 0.9mpa-1.2mpa, which can not only adjust the water content of the corrugated base paper and single-sided corrugated board, but also ensure the gelatinization of the adhesive.
In order to ensure the strength and good adhesion of corrugated board, the formation of corrugated board should be adjusted according to the different configuration of corrugated board production line.
1. For the corrugated base paper entering the single-sided machine, when the water content is controlled between 9% and 12%, the corrugated forming is the best. When the water content of corrugated base paper is higher than the above indicators, it can be solved by increasing the preheating area or reducing the speed; When the water content of corrugated base paper is lower than the above indicators, spray can be adopted. The author believes that when the single-sided corrugated board is positively ∞ shaped on the overpass conveyor belt through rapid paper transfer and the stacking distance is the same, the moisture content of the base paper and the corrugated base paper is adjusted better, and its moisture content is appropriate. The number of single-sided corrugated board stacked on the overpass should not be too much, but in order to ensure that the double-sided machine does not stop, the number of single-sided corrugated board stacked on the overpass can be appropriately increased when the single-sided machine changes paper.
2. The temperature of the dryer has a great influence on the water content of corrugated board. The heating section of corrugated board production line is usually composed of three groups (there are also four groups). The number of heating plates is determined by the size of heating plates and the speed of corrugated board production line, and each group is equipped with independent control valves. In order to ensure that the water content of single-sided corrugated board before entering the dryer is basically the same, it can be solved by adjusting the preheating area of single-sided corrugated board on the triple preheater. The adjustment method is: when the water content is too high, the preheating area increases; When the water content is too low, the preheating area decreases.
