1.1 Paper quality and impregnation process
In order to ensure the quality of impregnated film,high-quality decorative base paper must be used.No matter what kind of paper,it should be used after passing/inspection for a while,and if it fails,it must not be allowed to flow into the production line.In the process of impregnation,strictly follow the technical requirements,sampling and inspection every half hour to ensure that the amount of glue is 130%to 150%,the content of volatile matter is 6%to 7%,and the technical requirements of pre-curing degree≤65%;And the dried film should be packaged with plastic film immediately and sealed with adhesive strips;stored in a warehouse with temperature 20-25℃,humidity 55%to 65%,air conditioner installed,the storage time should not exceed 3 doors;Use the principle of opening and closing when using.The paper that is not used at one time should be sealed immediately and sent to the warehouse for storage,to prevent the moisture absorption caused the adhesive film to stick and become unusable,causing unnecessary losses.
1.2 Quality of base material
The base material of veneer-based artificial board is usually MDF and particle board.For particle board,it should be purchased out according to different requirements of customers,but the particle board products must meet the requirements of the first-class products of GB/T4897-92.
Quality requirements for substrates:
(1)The surface of the board is flat and clean,no water stains or oil stains are allowed,and there should be no edging or biting in the effective size;
(2)The thickness deviation of the board should not exceed±0.2mm,and the sanding is uniform,no sand leakage is allowed;
(3)The moisture content of the board should be controlled within the range of 6%-10%.Since particleboard is mostly purchased,changes in the environment can be cited
Changes in the moisture content of the sheet.If the water content is too high,it may cause blasting and delamination during the coating process;if the water content is low,or the volatile content of the impregnated paper is low,it may cause the surface to not wet well during hot pressing.Cardboard layering phenomenon.Therefore,it is necessary to observe and remove unqualified substrates in time during the production process.
1.3 Hot pressing process
The three elements of the hot pressing process are interdependent and mutually restrictive,and need to be analyzed and adjusted in a unified way when adjusting the process.Three factors have different effects on the veneer.The hot pressing temperature mainly catalyzes the chemical reaction of the impregnated resin,that is,accelerated curing.According to the actual requirements of production and the author's experience,the temperature of the hot platen is more suitable at 145～165℃.High temperature is good for demolding after pressing,and can shorten the hot pressing period and increase production,but too high temperature will make the resin solidify before it can flow evenly,resulting in tiny pores on the board surface.According to the 1998 national unified quality inspection data of impregnated film paper veneer wood-based panels,a considerable number of enterprises used to increase the output temperature by shortening the hot-pressing time by increasing the hot-pressing temperature.smooth.It seems that the output has been increased,but at the expense of product quality,it also has an impact on regular product manufacturers.
Appropriate pressure can ensure a good bond between the substrate and the impregnated paper.Under the appropriate temperature and pressure,the resin in the impregnated paper melts and solidifies to form a closed,dense surface,and can also make the substrate surface Peaceful tiny pores are filled.Generally,the pressure is generally 2.0~3.OMPa,under the premise of not affecting the quality of the product,the lowest pressure should be used as much as possible,which is beneficial to the service life of the equipment,hydraulic oil,and the internal structure of the substrate;but it is too low Pressure affects the bonding strength of the substrate to the impregnated paper and the resin's ability to flow.Therefore,in actual production,the unit pressure should be appropriately adjusted according to the new and old degree of different substrates and cushions.
The length of the hot pressing time depends on the curing speed of the impregnated resin and the hot pressing temperature,and it is generally 40 to 50 seconds.If the time is too long,the resin will be over-cured and lose its elasticity,which will easily cause cracks or internal stress to the product,which will cause cracks and warpage during subsequent processing;if the time is too short,the resin will not be cured sufficiently,and it will easily cause sticking.Phenomenon,and affect the physical and chemical properties of the product surface,affect the durability of the product.The time required for different materials is different.The degree of curing of each new product should be tested,and then the hot pressing parameters should be adjusted according to the test results.
In addition,during the operation,the movement of the impregnated paper needs to be careful to avoid damage;it is not allowed to wear dirty gloves;if the board surface is unclean,it should be cleaned in time;the substrate should be carefully checked when feeding,if found The surface of the board has defects such as large shavings,missing corners,damage,sand marks,etc.,which should be removed in time and refused to be used;the pressure roller of the paver,the large suction cup of the discharge,the small suction cups of the stacking,etc.,and each conveyor roller must be regular Clean to prevent the product from degrading due to suction cup printing and dust on the board surface.