Impregnated paper veneer
Melamine resin impregnated paper laminate (melamine laminate for short) 18mm melamine board is rapidly expanding to the public and civil furniture, vehicle anufacturing, construction, shipbuilding, interior decoration and other material industries, and has a considerable market share because of its advantages of less material, low energy consumption, fewer processes, low cost, etc., as well as its beautiful appearance, the surface has a certain degree of wear resistance, heat resistance, pollution resistance, easy to clean and other properties. According to statistics, Europe 1980 melamine impregnated paper veneer market share (refers to the ratio of all veneer man-made panels) for 8%, in 1995 rose to 18%, is expected to the next 10 years of growth potential is still very large, so melamine mdf sheets impregnated paper veneer by more and more attention.
1、Production process quality control
1.1 Paper quality and impregnation process
Hardware processing costing formula to ensure the quality of impregnated adhesive film paper melamine sheets sizes bunnings, must use high-quality decorative paper. No matter what kind of paper should be used in the factory after inspection and qualified, unqualified firmly can not flow into the production line. In the impregnation process, strictly in accordance with the process requirements for operation, every half hour sampling inspection, to ensure that the amount of glue on 130% ~ 150%, volatile content of 6% ~ 7%, pre-curing degree < 65% of the technical requirements; impregnation and drying of the melamine boards prices film paper need to be immediately packaged with plastic film and sealed with adhesive strips; storage in temperature 20 ~ 25 ℃, humidity 55% ~ 65% installed in the warehouse with air conditioning The storage time is not more than 3 months; when using the principle of open as you go, a pair of paper not used should be immediately sealed and sent to the warehouse for storage, to prevent moisture absorption and cause the adhesive film paper together and can not be used.
The base material of black melamine board 4×8 man-made board is commonly used MDF and particle board. For particle board, it is outsourced according to different requirements of customers, but the particle board products must meet the requirements of GB/T4897-92 first-class products.
Quality requirements for substrate :
(1) The surface of the board is flat and clean, no water and oil stains are allowed, and there should be no slippery edges and gnawing heads in the effective size;
- The thickness deviation of the particle board with 18mm white melamine should not exceed ± 0.2mm, and the sanding is even, no sand leakage is allowed;.
- Board moisture content should be controlled within the range of 6%~10%. As the particle board is mostly purchased, changes in the environment can cause changes in the moisture content of the plastic coated mdf. If the moisture content is high, it may lead to the phenomenon of release and delamination in the veneering process; if the moisture content is low or the volatile content of impregnated colored melamine sheets paper is low, it may lead to the phenomenon of delamination of cardboard because the surface is not well wetted during hot pressing. Therefore, it is necessary to observe and reject the unqualified substrates at any time during the production process.
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1.3 Hot pressing process of white laminated mdf
The three elements of the hot pressing process are interdependent and mutually constrained, and need to be analyzed and adjusted in a unified manner when making process adjustments. The three factors have different effects on the laminate, the hot pressing temperature is mainly to catalyze the chemical reaction of the impregnated resin, that is, to accelerate the curing. Depending on the actual requirements of the production. Generally, the temperature of the hot press board is 145~165℃ is more suitable. The high temperature is good for the demoulding after pressing, and 25mm white melamine board can shorten the hot pressing cycle and improve the output, but the high temperature makes the resin too late to flow evenly that curing, resulting in small pores on the 12mm white melamine board surface. According to the 1998 national quality statistics of impregnated paper laminate, there were a considerable number of enterprises to achieve the purpose of increasing production, by increasing the hot pressing temperature to shorten the hot pressing time, resulting in the mdf with melamine finish surface easy to rebound and not smooth.
The right pressure can ensure a good combination between the substrate and the impregnated paper 18mm white mdf. Under the action of suitable temperature and pressure, the resin in the impregnated melamine boards near me paper melts and cures to form a closed, dense surface, which can also fill the unevenness and tiny pores on the surface of the substrate. Usually, the pressure is generally 2.0~3.0mpa, without affecting the product quality, the pressure should be as low as possible, which is beneficial to the equipment, the service life of the hydraulic oil, and the inherent structure of the substrate; however, too low a pressure affects the bond strength and resin flow ability of the substrate and the impregnated paper white melamine faced mdf. Therefore, in actual production, the unit pressure should be adjusted appropriately for different substrates and the newness of the cushion.
The length of the hot pressing time builders warehouse melamine boards depends on the curing speed of the impregnating resin and the hot pressing temperature, generally 40~50s is appropriate. If the time is too long, the resin will be cured excessively and lose its elasticity, which will easily cause cracks or inherent force to the product and make it crack and warp during the subsequent processing; if the time is too short, the resin will not be cured sufficiently, which will easily produce the phenomenon of sticky board and affect the physical and chemical properties of the product surface and the durability of the white mdf shelving. Different materials require different times. In addition, during the operation, the impregnated paper needs to be moved carefully to avoid breakage; operation with dirty gloves is not allowed; the grouping process should be cleaned up in time if the board surface is found to be unclean; the substrate should be carefully inspected when feeding, if the melamine boards bunnings surface is found to have large shavings, missing corners, broken, sand marks and other defects, it should be rejected in time; refuse to use; the pressure roller of the lay-up machine, the large suction cup of the discharge, the small suction cup of the stacking division, etc., and each conveyor roller should be regular cleaning to prevent the 18mm laminated mdf surface from having suction cup marks and dust and resulting in product degradation, etc.
2. Analysis of common problems and solution measures
2.1 Sticky pad phenomenon
Sticky pad refers to the hot pressing process in which the plate is partially or completely stuck to the pad. The reasons for this are as follows.
(l) Short hot pressing time, or low or locally low temperature of the hot pressing white mdf board 18mm, which makes the resin curing incomplete.
- Excessive water content of the substrate.
- Excessive amount of glue on the impregnated paper and high content of volatile fraction.
- unclean surface of steel plate, unsuitable type of release agent or uneven coating.
- Inaccurate positioning of the slab during hot pressing. The phenomenon of sticky melamine faced ply mostly occurs around the board, which is due to the low temperature of the edge, and also may be due to the deviation of the position of the slab in the press too much. Therefore, an appropriate increase in temperature or extended hot pressing time is an effective way to solve such problems.
- From the perspective of hot pressing, the melamine sheets b&q warping is due to the temperature difference between the upper and lower platen is too large, the curing speed of the adhesive film paper melamine sheets for sale on both sides of the substrate in the press process is not synchronized, the board bends to the side of the curing fast. The upper and lower pressure plate suitable temperature difference should be the upper pressure plate temperature than the lower pressure plate high 3 ~ 5 ℃.
- From the material buy melamine sheets, the two layers of impregnated paper used in the substrate performance is not the same will also lead to plate warping. If a single side of the base material is used for lamination, warping is a natural result. From the production point of view, it can be ensured that the black laminated mdf does not warp by using the same impregnated paper or by adjusting the appropriate temperature difference between the upper and lower platens.