By Abhijit Phadke
Laminates such as Sunmica are basically a blend of paper and plastic. Brown paper and Decorative paper soaked in phenolic and melamine resins are hard pressed together to form a stiff laminate sheet. In this article we are going to take a more detailed look at how decorative laminates such as Sunmica or other such brands are manufactured in the factories.
Sunmica or other Laminates are made up of papers that are treated with chemical resins to impart them with strength and stiffness. The main ingredients required in the manufacturing process are listed below.
The main machinery and equipments required for making laminates/sunmica are listed below.
The Laminate Manufacturing Process
The main steps carried out in the making of laminates are listed below.
Step 1: Soaking the paper in resins
The manufacturing process starts by soaking the paper in resins.
The brown paper that is going to form the bottom side or base of the laminate is soaked in a bath tub that is filled with phenolic resin. On soaking, the brown paper does not just get wet but rather absorbs the resin and is saturated with it. This soaking process is also known as impregnation, and the machinery which moves the rolled up paper from its spools through the resins is called a PIL (Paper Impregnation Line).
The decorative printed paper and the translucent paper is similarly soaked and saturated with the melamine resin. The resin helps to make these surfaces harder, stiffer and better at resisting scratches and wear and tear.
Step 2: Drying the papers
This is followed by a drying process in which the soaked papers are allowed to dry. After the drying is complete, the paper which earlier was easy to tear acquires new physical properties. It becomes stiff and brittle.
Step 3: Cutting
The hardened rolls of paper are then cut to the desired sizes by the cutting machines (called cutters). In India, the standard or most common size for laminate sheets is 8'x4' (8 feet by 4 feet). So the machines accordingly cut the papers to this size.
Step 4: High-pressure pressing and bonding
The next step in the laminate manufacturing process is to hard press these papers together under high pressure and temperature. This is done using hydraulic presses. The papers or sheets are stacked upon each other. The brown paper forms the bottom sheet followed by the decorative sheet, and the topmost layer is of the clear translucent paper. The huge hydraulic presses are designed to press large number of laminate sheets at a single go. So all the laminates that are to be pressed are placed one upon another with steel separator plates interspersed between them (so that the separate laminate sheets do not stick with each other while being pressed). The steel sheets also serve another purpose. They are designed to carry textures or patterns on them that get etched on to the surface of the sunmica/laminate sheet while being pressed. The pressing is one of the most important processes in the manufacturing of laminate sheets and is the reason why decorative laminates are often referred to as HPL and HPDL (High-pressure decorative laminates).
Step 5: Sanding the non-decorative side
In the final step of the process, the bottom side (non-decorative side) is uniformly sanded by a sanding machine. The sanding process makes this surface better suited for adhesion to surfaces. This sanded surface is the one on which carpenters apply Fevicol (or other adhesives) while glueing these sunmica/laminate sheets over plywood or other base substrate materials.
Step 6: Testing, Packing, Shipping
Samples of the finished products may be subjected to standard quality tests for laminates as per norms, and these sheets are then packaged and shipped to the regular distribution channels of the laminate companies.
So this is how sunmica and other laminate sheets are made.
Thickness: The thickness of Laminate sheets usually ranged from 0.6 mm to 1.5 mm, and accordingly more layers of paper can be used in the process. Much thicker laminate sheets (3mm to 30mm thickness) are also manufactured and these are known as compact laminated sheets. These compact types are stiff and self-supporting. Such compact sheets can be used independently without the need to glue them onto plywood, particle board, MDF or any other base materials.