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Melamine impregnated paper and melamine impregnated paper laminated veneer production quality controlSource:   Release time:2015/04/21

Melamine impregnated paper is a new kind of material of facing of man-made board, through its ACTS the role of the man-made board, fire, high temperature resistant, acid and alkali resistance, moisture resistance, abrasion resistance, easy cleaning, widely used in office equipment, kitchen furniture, interior decoration and transport, etc. Especially suitable for making mesa, aggrandizement floor, etc. The specifications of the products, varieties, design and color, can according to customer requirements processing production. Its main produce melamine resin impregnated paper veneered plywood, the board (hereinafter referred to as melamine laminated board) to the production of materials, low energy consumption, less operation, and low cost, less and beautiful appearance, there 'surface wear resistance, heat resistance, resistance to pollution, easy to clean, such as performance, is rapidly to the office and civil furniture, vehicle manufacturing, construction, shipbuilding, interior decoration, such as timber industry development, and has set up a occupies considerable market share. According to statistics, 1980 European melamine impregnated paper appropriate panel market share (ratio) of all cover man-made board is 8%, increased to 18% in 1995, is expected in the next 10 years is a large potential for growth, and therefore melamine impregnated paper veneers are more and more attention. The author combined with years of practice, the melamine impregnated paper veneers article discusses the quality control in the process of production.


                


1 the production process quality control

1.1 the paper quality and the impregnation process

In order to guarantee melamine-impregnated paper quality, must use high quality decorative base paper. No matter what kind of paper should be in/at that time the use after inspection, unqualified resolute can't shed production line. In dip process, in strict accordance with the technological requirements, once every half an hour to sampling inspection, guarantee the gluing quantity was 130% ~ 150%, 6% ~ 7% content of volatile matter, technical requirements in the process of the curing degree of 65% or less; Dipping and drying after the film to be packed in plastic film, paper and glue stick sealing; 20 -- 25 ℃ is stored in temperature and humidity 55% one 65%, installation of air-conditioned room, storage time should not more than three door; Take along with it when using the principle of open, one should be made to burn paper immediately sealed and sent to the warehouse storage, to prevent moisture absorption from the film adhesive in, and can't use, cause needless loss.

1.2 base material quality

Stick a face of man-made board base material commonly used medium density fiberboard and particleboard. For particle board, should according to the different requirements of customers to outsourcing, but particleboard products must meet the requirements of GB/T4897-92 grade a.

About the quality of the base material requirements:

(1) board face level off, clean, there is no stain, oily be soiled, effective size is edge, on the first class phenomenon;

(2) the thickness of the plank deviation should be no more than + / - 0.2 mm, uniform and sanding, there is no sand leakage phenomenon;

(3) the lumber moisture content should be controlled in the range of 6% to 10%. Due to particle board is outsourcing more, changes in the environment can be

The plank moisture content changes. If the moisture content is on the high side, can lead to stick a face appeared in the process of shooting, the phenomenon such as hierarchical; If the moisture content is low, or impregnated paper low volatile content, may cause thermal surface does not produce good wetting board stratification. Therefore, in the process of production need to observe, timely eliminate the unqualified base material.

1.3 hot pressing process

Hot-pressing process of the three elements are interdependence and restraining each other, when making process adjustment needs unified analysis and adjustment. Three factors affect veneers each are not identical, hot pressing temperature is mainly on the impregnating resin catalysis of chemical reactions, which accelerate the curing. According to the actual requirements of production and the experience of the author hot platen temperature at 145 ~ 165 ℃ is more appropriate. After high temperature is advantageous to the pressure on the mold release, and can shorten the hot pressing at the same time, increase production, but too high temperature is uniform resin to flow curing, causing panel has a tiny pore. According to the 1998 national melamine-impregnated paper cover, man-made board quality TongJian data show that there was a considerable number of enterprises to achieve the purpose of increasing production, to shorten the hot pressing time by increasing hot-pressing temperature, resulting in the plate could rebound and not smooth. Seemingly improved yield, but at the expense of the quality of the products at the expense of, at the same time also to the formal product manufacturers.

Appropriate pressure can guarantee the good combination between substrate and impregnated paper, under the appropriate temperature and pressure, the resin impregnated paper after melting and solidification, closed, and the density of surface formation, still can make uneven and tiny pore on the surface of the base material to fill. Usually, pressure is 2.0 ~ 3. Commonly OMPa, under the premise that does not affect the quality of products, should as far as possible with low pressure, so to the service life of equipment, hydraulic oil, base material of the inner structure is good; But it is too low pressure affect the bond strength with the impregnated paper and resin flow ability. In practical production, therefore, should be aimed at different substrate and cushion condition adjust unit pressure.

The length of the hot-pressing time depends on the curing speed of resin impregnated and hot-pressing temperature, usually in 40 ~ 50 s advisable. Time is too long can cause excessive resin curing, losing its elasticity, easy to cause the product or internal stress of crack, crack appeared in the process of make it in the subsequent processing, warping; Time is too short, resin curing insufficient, prone to stick plate phenomenon, and the influence on the performance of the product surface physical and chemical, influence the durability of the products. Time needed for different materials, different response to each panel for the experiment of curing degree of new products, and then adjust the hot-pressing parameters according to the results of the test.

In addition, in the process of operation, the movement of the impregnated paper carefully, avoid damage; Not allowed to wear dirty gloves operation; Groups such as found in the process of billet board face is not clean to clean up in time; Base material incoming check carefully, if found a large shaving board face, missing Angle, damaged and defects such as sand marks, should be promptly eliminate, refused to use; Shop is installed in the roller pressure, discharge of suction cups, stacking feature of small suction cups, the conveying roller should be cleaned regularly, to prevent the panel have suction cups printing and dust caused by the product fall, etc.


             

2 common problem analysis and solving measures

2.1 stick plate phenomenon

Sticky pad is refers to the sheet during hot-pressing process part or all of the stick on the plate. The reason has the following kinds:

(1) hot pressing time is short, or hot platen temperature low or local low, resin curing incomplete;

(2) base material moisture content is too high;

(3) resin impregnated paper is too large, high volatile content;

(4) steel plate surface is not clean, demoulding agent type is not suitable or uneven coating;

(5) when hot-pressing slab position is not accurate.

Glue board phenomenon occurs around the perimeter of the plate, this is due to the low temperature of edge, could be the slab position deviation caused by people in the press. Should be checked item by item, find out the real reason for glue plate occurred, timely solve, reduce the loss. Glue plate number is caused due to the adhesive curing incomplete, therefore, appropriately increased temperature or to extend the time of hot pressing is the effective way to solve such problems.

2.2 plate warping

(1) from the Angle of the thermal analysis, plate warping is due to the large temperature difference of upper and lower platen, causing pressure stick a film on the surface of the substrate on both sides of the paper in the process of curing speed out of sync, plate caused by bending to one side of the solid 17 fast. The author thinks that, upper and lower platen appropriate platen temperature on temperature difference should be higher than the press table 3 ~ 5.

(2) from the material itself, the village of material used in the two layers of impregnated paper performance - not the sample sheet can also lead to warp. If the base material single stickers, the warp is the inevitable result. From the Angle of production, can be adjusted by using the same impregnated paper or the temperature difference between the upper and lower platen is appropriate to ensure that the board does not produce warp.

(3) after extrusion product stacking method is not correct, another major cause of the warp, the solution is to use an even and straight skid or pallet storage hot-pressing good melamine impregnated paper veneers.

Above all, to produce the high quality products, must choose good impregnated paper and base material, the reasonable processing technology; In addition also need operation, inspection personnel to cooperate, there is a problem should be timely feedback, only in this way, to ensure product quality stability, occupies a larger market.



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