1、填料過多。

1. Too much filler.

由于目前市場上石塑電梯門套的低，原材料又在上漲，很多石塑電梯門套廠家都在降低成本上著手。而正規的石塑電梯門套廠家都是在不降低質量的前提下，通過配方的優化組合降低了成本;有些廠家卻在降低成本的同時也降低了制品質量。

Due to the low price of stone plastic elevator door pocket in the market and the rising price of raw materials, many stone plastic elevator door pocket manufacturers are starting to reduce costs. The regular stone plastic elevator door pocket manufacturers reduce the cost through the optimal combination of formulas without reducing the quality; Some manufacturers have reduced the quality of products while reducing the cost.

2、抗沖擊改性劑的數量及添加種類。

2. Quantity and type of impact modifier.

在應力作用下，抗沖擊改性劑能夠提高聚氯乙烯破裂的總能量。目前，CPE、ACR、MBS、 abs、EVA等是硬質聚氯乙烯的抗沖擊改性劑的主要品種，其中CPE、EVA、ACR改性劑的分子結構中不含雙鍵，耐候性能好，適宜做戶外建筑材料，它們與PVC共混，能有效的提高硬聚氯乙烯的抗沖擊性能、加工性、耐候性及在一定范圍內提高焊角強度。

Under the action of stress, the impact modifier can increase the total energy of PVC rupture. At present, CPE, ACR, MBS, ABS and EVA are the main varieties of impact modifiers for rigid polyvinyl chloride. Among them, CPE, EVA and ACR modifiers do not contain double bonds in their molecular structure and have good weather resistance. They are suitable for outdoor building materials. Their blending with PVC can effectively improve the impact resistance, processability and weather resistance of rigid polyvinyl chloride and improve the fillet strength in a certain range.

3、穩定劑過多或過少。

3. Too much or too little stabilizer.

穩定劑的作用是抑制降解，或與釋放出的氯化氫反應以及防止聚氯乙烯加工時變色。穩定劑用量多少也會對型材的抗沖擊強度造成影響，過多或過少都會造成型材強度降低引起型材發脆現象。

The function of stabilizer is to inhibit degradation or react with released hydrogen chloride and prevent discoloration of PVC during processing. The amount of stabilizer will also affect the impact strength of the profile. Too much or too little will reduce the strength of the profile and cause the embrittlement of the profile.

4、外潤滑劑用量過多。

4. Excessive amount of external lubricant.

外潤滑劑與樹脂相溶性較低，能夠促進樹脂粒子間的滑動，從而減少摩擦熱量并推遲熔化過程，潤滑劑的這種作用在加工過程早期(也就是在外部加熱作用和內部產生的摩擦熱使樹脂完全熔化和熔體中樹脂失去識別特征之前)是的。

The compatibility between the external lubricant and the resin is low, which can promote the sliding between the resin particles, so as to reduce the friction heat and delay the melting process. This effect of the lubricant is the largest in the early stage of the processing process (that is, before the external heating and internal friction heat make the resin completely melt and the resin in the melt lose its recognition characteristics).

5、熱混加料順序，溫度設值以及熟化時間對型材的性能也有決定性的因素。

5. The hot mixing feeding sequence, temperature setting value and curing time also have decisive factors on the properties of profiles.

PVC-U配方的組分很多，所選擇加料順序應有利于發揮每種助劑的作用，并有利于提高分散速度，而避免其不良的協同效應，助劑的加料順序應有助于提高助劑的相輔相成效果，克服相克相消的作用，使用在PVC樹脂中分散的助劑，充分進入PVC樹脂內部。

PVC-U formula has many components. The selected feeding sequence should be conducive to giving full play to the role of each additive and improving the dispersion speed to avoid its adverse synergistic effect. The feeding sequence of additives should help to improve the complementary effect of additives, overcome the function of eliminating each other, and use the additives dispersed in PVC resin to fully enter the interior of PVC resin.