MDF Board Melamine Paper Lamination Solution

Key Words:

1, Melamine Formaldehyde:

2, Urea Formaldehyde;

3, 2nd Melt

4, 2nd Melting Point

5, Loose MDF/HDF

In Plain MDF/PB/Plywood board chemical structure, there is MF/UF as the veneer/wood fiber adhesive; it is well known, same element is easier to be bonded together. Thus, for décor printed paper, a common concept will be, applying same glue into its core; MF also has its character, it will be re-melt at degree of 1800C under some pressure. That is ‘Melamine impregnation line’ comes into being.

Also, from the view of science, Melamine Formaldehyde Glue, it needs time go thorough into core of paper mesh fiber structure, this is paper permeability; MF glue melts into paper core, is also under its solid property, it generally gets hard under its timing Chart. In real design and operating, front 2 oven, rear 4 ovens, is the classic formula for impregnation line. In some case, due to workshop length limits, there is also 2+3oven model adopted, while for paper quality, it is a little difficult to avoid melamine overheating or less-heating while too much vapor remains in paper or too much crisp on paper top surface.

Melamine Formaldehyde Resin will melt at the temperature of 1800 again. We call its 2nd Melting Point; under this temperature, MF resin can only run into MDF/PB/Veneer fiber structure from Melamine Paper. This property is the principle of Melamine short cycle lamination press and door skin press. Leaving this 2nd melting point, melamine paper on MDF gets its solidity; the more cooling speed, the more shine of its surface melamine crystal. In jumbo production, that is why “cooling hedgehog” device is a must.

In short cycle lamination press, and also Door skin press, the common factor need to be considered is, hot platen transfer heating to melamine paper melting, also heating the base MDF, pressure will also push melt MF forced running into inner MDF; the only difference for Door skin and MDF lamination is: Door skin need two step treatment to avoid paper crisp, first punch and get loose MDF marked in frame door skin shape, then apply paper and let two parts melt and solid together; while for MDF lamination, only one time is finished.

Here, loose MDF/HDF, mean less density MDF/HDF, in previous, MDF/HDF need special soften by chemical agent then be treated in above mentioned two steps method. And now, tailor made loose MDF/HDF is softer than normal one, easier to get Door skin mold Shape before meet melamine paper, this guarantee the ratio of qualified finishing.

Production Capacity for Melamine Impregnation line

Standard 4ft 2+4 model impregnation line, at 80gsm paper, 120% pickup, suitable for MDF content, whole line speed at min. 20m/min, it will be 20m/min x 60min x 20hr /2.44meter = 10,000sheet

For 4ft 3+5 model, the speed is min 25m/min, it will be 25/min x 60min x 20hr /2.44meter = 12,500sheet.

If the décor printed paper property is good, glue by experienced formula with very good permeability, also 100% of glue pickup, 2+4 can run at speed at 25m/min, 3+5 can run at speed of 30m/min.

Above also says, impregnation line speed is subject to paper property, glue property, and glue pickup requirement. In general, for MDF paper, the glue pickup about 100~120%, for particle board, it is about 125~135%. These requires variety speed in real operating.  

Melamine Short cycle laminating press

Melting timing: this is a key concept in lamination. In 1800C flat heating Chart, melamine glue gets melt need a time, it normally is 13~18seconds; factors to glue formula, and MF, UF percentage.

Pressing time: liquid MF glue under 2nd Melting, running into MDF/PB inner surface under pressure. It is a complicate factor results by pressure in kg/cm2, plain board structure and surface smoothness, this duration is normally 1second per 1mm base board thickness.

Loading time: plain board is transferred into body of main press for heating and pressing.

Hydraulic station force preparation and action speed, this is also factoring to determine short cycle laminating process. In some design, accumulator is adopted to shorten a little for pressure re-preparation from valley to summit.

Above factors cause the capacity of Short cycle laminating press as 40-50second per cycle, 1.2sheets per minutes. Or say basically 70sheets per hour.

If high speed servo belt conveyor is adopted, and accumulator in hydraulic station, the capacity will increase to 80/90 sheets.

Super capacity of short cycle lamination presses especially refer to more than 100sheet/hr model, the press cost will greatly be increasing.

For basic short cycle laminating press, 70pcs x 20hr = 1400sheets per day, or say 70~80sheet per hour.

Door Skin Press

Its principle is short cycle laminating press alike. There are two factors need to be considered:

1, why two steps treatment.   Two steps treatment, means, first only thin MDF board in to mold and get door skin mold shape and curing mark.   Due to paper and MDF inner expanding ratio is different, if paper and MDF together and even slowly pressing, the paper will still easier getting broke in mold cut-off area. This will be much low ratio of qualified finishing. In real operating, thin MDF is pressing marked, then apply paper again to get door skin. This two-step method also can guarantee door skin surface uniform while not burl reflect on surface.

2, why multi press. Above two steps door skin lamination, one whole cycle needs about 3~5minutes, to increase economic effect, door skin press is designed to be multi daylight. Normally is 5DL, too many DL, the loading position of top DL is out of limits of employee’s hand range.

Capacity calculation: 60min / 4mins x 5DL x 20hr = 1500 sheets per day. 70sheet per hour average. 

Impregnation line, short cycle lamination presses matching balance

Short cycle lamination is normally dual side, it needs two pieces of melamine paper for one Melamine MDF finishing. 1400sheets Melamine board, means 2800pcs of melamine paper. In real operating, we can say one 4ft 2+4impregnation line, need 3short cycle laminating press as production matching balance.

For door skin, due to it is one melamine paper needed, so, normally one impregnation line need 6line of door skin press getting matching balanced in production. 

Other Heating Issue

Both impregnation line, short cycle laminating press, door skin gets heating source from thermal oil boiler normally, but due to heating summit duration is long and huge for impregnation line, and shorter in frequency for lamination press. We strongly suggest different boiler for impregnation line. Don’t make same heating boiler supply for both impregnation line and lamination press.

In the coming proposal, we are to guide classic specification for impregnation line, short cycle lamination press and door skin. If high production in jumbo capacity, synchronization laser tracker, high speed loading, accumulator, vacuum un-lifter, 4-sides trimmer, cooling device can also update.