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Views: 7 Author: Site Editor Publish Time: 2021-08-25 Origin: Site
EVA foam material is a new material with high quality and environmental protection. Used as lining, shoe material, luggage material, car wash brush, handicraft, widely used, mainly because EVA foam is extremely plastic and easy to punch and press.
But the relative price is higher than inferior quality and low stability rubber and plastic products. EVA foam material is produced from the main material EVA foot pads, fillers, foaming agents, bridging agents, foaming accelerators, and lubricants.
Accessories: leftover material, antistatic agent, flame retardant, quick-curing agent, coloring agent, the raw material is made into soft glue by the glue machine, and the soft glue is pressed into flakes by the roller machine, and the flake materials are put in Inside the large flat-plate foaming mold, after a high temperature of 160 to 170 degrees, foaming is formed. This process produces a plate, and the desired size and thickness are drawn through the opener.
EVA foam has good elasticity, abrasion resistance, air tightness, and is harmless to the human body.
Water resistance: airtight cell structure, no water absorption, moisture resistance, and good water resistance.
Corrosion resistance: resistant to chemical corrosion such as sea water, grease, acid, alkali, antibacterial, non-toxic, odorless, and pollution-free.
Processability: easy to process such as hot pressing, cutting, gluing and laminating.
Anti-vibration: high resilience and anti-tension, high toughness, with good shock-proof, anti-skid and cushioning properties.
Thermal insulation: excellent thermal insulation, cold-preservation and low-temperature performance, and can withstand severe cold and exposure.
Sound insulation: airtight cell, good sound insulation effect.
Environmental protection: Most of the EVA foot pads in Dongguan are environmentally friendly products and can be used with confidence.
The foaming process of EVA foam
The foaming process of EVA foam has a complicated mechanism and many influencing factors, making it difficult to control the quality of the foam. In foaming, it is necessary to observe various phenomena in real time and adjust the formula in time to produce foam with fine and uniform cells, good resilience and high tensile strength.
In this paper, based on the foam foaming practice experience, on-site quality control and defect correction in the foaming site. In addition, the polymerization degree distribution will also affect the processing performance and product performance. It is better to choose the PVC resin with a narrow molecular weight distribution so that the processing performance and product performance are more uniform. Conducive to control processing conditions and product quality.
Low molecular weight will reduce the thermal stability, aging performance, mechanical properties, etc. of the product, but the high molecular weight will make it difficult to uniformly plasticize during processing, causing particles or "fish eyes" to appear when the internal and external quality of the product decreases severely. PVC resin The plasticizing time is also an important selection indicator.
Too small particle size also has a certain effect on plasticization. The friction between particles is reduced and the plasticization time is prolonged. Therefore, the resin is required to have good fluidity and a larger particle size and a narrow particle size distribution. Both the higher viscosity PVC powder and compact PVC powder are not conducive to the full foaming of the foam.
Generally, the loose suspension PVC resin with an average degree of polymerization of 750-650K and a value of 59-55 is used for foam. Its processing performance is easy to be plasticized. It is used to produce large-scale sheet foaming ratio and sheet thickness is easy to control. The product qualification rate is high.
Three issues were explained: regular foam formula adjustment, special foam formula adjustment, and cause analysis and corrective measures for common defects. 1 Conventional foam formula adjustment. Under the reference conditions of material temperature 18~20"C and air temperature 20℃, the formula of foaming cylindrical foam with a diameter of 2 meters and a height of 1 meter is called the standard formula. Commonly used standard formulas are shown in Table 1.0. Table 1.0 Commonly used benchmark formulations.