Wuhan Handern Dipping and Gluing Process
日期：2020/12/1 10:18:03 / 阅读： / 来源：本站
Wuhan Handern Dipping and Gluing Process
Dipping and sizing is a key process for manufacturing the advantages and disadvantages of laminated plastic products. If the impregnation is uneven, and the control strip does not meet the process requirements, high-quality products cannot be obtained. During the dipping process, the content and distribution of the base resin, the volatile content, the degree of resin flow after drying, and the soluble resin content all affect the product quality and cost. handern.com Spunbond Non-woven Fabric Making Machinery
(1) Impregnating resin The curing degree and curing time of the resin have a great influence on the impregnation speed and drying speed, because the speed is too fast to be controlled, and too slow will affect the product. The control of the viscosity of the resin is very important. If the viscosity is too high, it will not easily penetrate into the paper or cloth and affect the quality. If the viscosity is too small, the immersion amount will be insufficient. It is usually controlled by the amount of solvent added and the temperature. The temperature of the immersion tank is preferably 25-30℃ hot water. If the temperature is too high, the volume of solvent will increase and cause waste. For doctor blade impregnation, the impregnation amount is controlled by viscosity and impregnation speed: for squeeze roll impregnation, the pressing force of the pressure roll can also be used to force impregnation and control the amount of impregnation and remove the trapped air, but When the pressure roller is too tight, it will be broken due to too much tension of the paper base, and it will also cause uneven coating on the surface of substrates such as paper and cloth. handern.com Spunbond Non-woven Fabric Making Machinery
(2) Control of the dryer. Steam pressure, temperature and vehicle speed are closely related. Generally, the steam pressure is controlled at 0.5~
About 0.7MPa (5~7kgt/cm2), the steam pressure should be adjusted according to the specifications of the substrate and the curing speed of the resin. For example, the impregnated paper (cloth) base requires small fluidity and the resin cures slowly. Higher steam pressure (actual Above, the temperature of phenolic resin impregnated paper base should not be too high). The vehicle speed is determined by the length of the resin curing time. If the thermosetting time is fast, the vehicle speed should be increased, otherwise the fluidity of the tree on the substrate is too small (the content of fusible resin is also small), otherwise, the vehicle speed should be slowed down.
(3) Control of resin content and volatile content The compressive strength of laminated products mainly depends on the base material, while other mechanical properties are closely related to the resin content. Although the strength of plant fiber is high, the lack of adhesion between the internal fiber and the fiber can not fully display its strength. When the resin is impregnated, this shortcoming is made up. Generally, the content of the tree is controlled in the direction of 30-55% (32±3% for phenolic laminate, 40±3% for diallyl phthalate). Excessive resin will cause moisture and volatiles to be difficult to remove. Affect layered electrical insulation performance and so on. handern.com Spunbond Non-woven Fabric Making Machinery
If the volatile content in the resin impregnated substrate after drying is too high, the gold will affect the electrical properties of the finished product, and the mechanical properties will also be affected. It will also cause appearance defects such as surface blistering, edge green blooming, etc.; too small volatile content It affects the fluidity of the tree and makes lamination difficult.
Generally, the volatile content is measured before drying. For the base material for laminated foil-clad laminates, the volatile content is about 2.5%. For laminates, tubes, rods, etc., it can be controlled at 4 to 6%.
(4) Control of soluble resin content and fluidity. Soluble resin refers to a B-stage resin that is still soluble in acetone. If the content is too small, it will affect the adhesion between the substrates and reduce the performance of the finished product; if the content is too large, it will be laminated The large loss of resin will also cause the substrate (especially paper or cloth) to slip and cause waste. Fluidity is a simple judgment index for determining the content of soluble resin in industrial production.
(5) Abnormalities in the dipping and drying process
①The amount of substrate immersion is uneven. Adjust the viscosity of the resin solution and the temperature of the immersion tank, adjust the tension of the doctor blade or squeeze roller, and keep the roller pitch equal. Pulling the chain net by the substrate in the drying room will also cause uneven resin content. The speed of the vehicle and the tension plate of the winding part should be adjusted to maintain a certain degree of tension on the substrate.
②The resin fluidity and volatile matter on the substrate suddenly increase. As the steam becomes an electric heating imbalance, especially due to insufficient steam in winter, the vehicle speed should be slowed down. Generally, for every 5°C decrease in temperature, the vehicle speed should slow down by 3~6s/m (cloth basis) or 2～3s/m (paper basis). If the air volume of the air supply box of the drying room is not balanced, the temperature will also decrease. At this time, the ventilation valves of the upper and lower air ducts should be adjusted to balance the hot air.
③There are black spots or black stains on the substrate. It is caused by the drop of low-molecular substances and volatile substances accumulated on the wall of the entrance and exit of the drying room and on the exhaust pipe, so it should be wiped clean.
④Multi-layer film base rewinding occurs between squeezing and losing tension due to the loosening or unwinding of the reeling roller. It may also be that the squeezing roller is faster than the rewinding roller. Exit processing.
⑤The film base suddenly loosens and the joint breaks in the drying room. It may be caused by the fast delivery speed of the squeeze rolls and the low winding speed, or the pressure adjustment between the squeeze rolls is too tight or unilateral is tight. fracture. The speed should be adjusted and the materials in the drying room should be quickly sent out of the drying room for processing. handern.com Spunbond Non-woven Fabric Making Machinery
⑥The blower of the drying room stops suddenly. If the power is cut off, the immersion will be stopped, the film base will be cut, and it will be manually reeled at the exit with the same speed.