Guide: Melamine impregnated paper veneer is widely used in furniture manufacturing. How many people know about its defects and the corresponding solutions? The full name of melamine impregnated paper is melamine impregnated adhesive film paper, also known as “melamine” paper. It is a kind of industrial paper that is impregnated with amino resin (melamine formaldehyde resin and urea formaldehyde resin) and dried to a certain extent by plain base paper or printing decorative paper. It has a certain content of resin and volatile matter, and can be bonded with each other or with the wood-based panel substrate after hot pressing! The melamine impregnated paper veneer has the advantages of less production materials, low energy consumption, fewer processes, low cost, beautiful appearance, certain wear resistance, heat resistance, pollution resistance, easy cleaning, etc. It is rapidly expanding to office and civil furniture, vehicle manufacturing, construction, shipbuilding, interior decoration and other material industries, and has already occupied a considerable market share. Therefore, the quality requirements in the production of melamine impregnated paper veneer are becoming higher and higher.
Now let’s share the defects and corresponding measures of melamine impregnated paper veneer.
- There are many reasons for the warping of veneers, mainly including: ① The base paper is not evenly impregnated and has different volatiles. ② Hot pressing without thickness gauge; ③ The temperature difference between the upper hot pressing plate and the lower hot pressing plate is too large, which makes the curing speed on both sides of the veneer inconsistent, causing the plate to bend towards the side with fast curing. Measures: ① Adjust the impregnation speed of base paper and prepare impregnating resin as required; ② Increase the hot pressing thickness gauge to control the compression thickness; ③ Adjust the temperature difference between upper and lower platens to make the difference not exceed 4 ℃
- Part of the melamine resin adhered to the polished board during curing, which caused the surface of the veneer to crack. The reasons are: ① The curing time is too long or the hot pressing temperature is too high; ② There is no release agent in melamine resin; ③ The quality of the polished plate decreases. The above disadvantages can be overcome by adjusting the hot pressing temperature, adding release agent when mixing glue, and better polishing plates, such as chrome plated polishing plates.
- The surface porosity of the porous board on the surface of the veneer is mainly due to the insufficient flow of resin under high temperature or low pressure. In addition, the surface structure of the particle board also has a certain impact on the veneer. Therefore, the pressure can be increased to the maximum, and the volatile matter content and resin content of the paper can be increased; Increase the content of modifier to 0.5%. In addition, check whether the impregnated paper is stored too long or improperly.
- The layering of veneers and the layering of blister veneers mainly include the following aspects: ① resin waterproof paraffin, oil or paraffin coating on the surface of chipboard; ② The resin content in impregnated paper is very little, and the resin fluidity is too low, which makes the resin on the surface of particleboard insufficient; ③ The moisture content of particleboard is too low or the volatile content of impregnated paper is too low. The reason for cloth blistering is that the substrate is too thin or the moisture content is too high, and water vapor is generated during the veneering time, which causes blistering when the press is turned on.
- Board edge damage When the veneer is cut, its edge is damaged and degraded due to the tearing of wood chips. The cause of the defect may be: the strength of the base material edge is not enough; The shear strength of the surface layer of the substrate is not enough, or the shape of the cutter and the sawtooth need to be adjusted. The sawing speed is too low or the feed speed of the plate is too fast. Therefore, in addition to purchasing high-quality base materials, tools should be checked regularly.
- There are many reasons for the folding of impregnated paper during hot pressing. Generally, the following measures are taken to overcome it: ① slow down the closing speed of the press; ② Check whether the pressing strip of the upper polishing plate is warped or whether the polishing plate needs to be renewed; ③ Check the electrostatic device and clean or switch the power supply; ④ Check the weather condition of the impregnated paper in the storage room and the rigidity of the wet paper.
- The measures taken for paper folding immersed in the drying box include: ① relax the friction brake on the release device to reduce the tension of the paper; ② Reduce the tension between the driving roll and the driven roll; ③ Release the drive scraper after the base paper passes through the first impregnation tank.
- The causes of surface water marks (wet flowers): ① The moisture content of the substrate is too high; ② The moisture content measuring instrument of impregnated paper is not properly installed; ③ Excessive residual volatile matter of impregnated paper; ④ The following measures shall be taken: ① adjust the moisture content of base material; ② Adjust the water content tester; ③ Adjust the drying conditions of impregnated paper; ④ Increase the temperature of the hot pressing plate to increase 5 ℃. In addition, pay attention to the storage of the impregnated paper.
- This type of defect of emulsion shift mainly occurs in hot pressed color coated plate, and the main reasons are: ① the pressure is too low; ② The thickness tolerance of base material is large; ③ The polished plate is contaminated. The measures mainly include: ① increasing the pressure of hot pressing plate; ② Adjust the sanding amount of the base material or improve the thickness requirements of the base material; ③ Clean the polishing plate or replace it.
In a word, the defects in the production process of melamine resin impregnated veneer wood-based panels are constantly found and the causes are found out to overcome. As long as we strictly follow the process requirements and control the quality inspection, we will be able to produce more and better products and improve the economic benefits of the enterprise.
