Guide: At present, the plastic films used for veneer of panel parts mainly include polyvinyl chloride (PVC), polyethylene (PVE), polypropylene (Alcorcell), polyester (PET) and polypropylene (PP).
Veneer decoration is a very important process in the production of panel furniture. It can cover the defects of the material surface and improve the physical properties of the substrate. Veneer materials include veneer veneer (veneer veneer, veneer veneer), wood grain paper veneer, PVC plastic film veneer, melamine board veneer, etc. Let’s introduce veneer veneer, PVC veneer and decorative paper veneer in detail to learn about wood-based panel plastic surgery veneer technology! Veneer veneer is the most important decoration method for panel parts, and it is a technology to glue veneer (plain or various kinds of parquet) to the surface of various substrates (wood-based panels, solid wood paneling boards, solid wood parquet, etc.). Sanding treatment before and after veneering The thickness difference of the same batch of plates after thickness correction of the fixed thickness sanding before veneering is generally required to be controlled within 0.2mm, and there are no obvious sand marks and wavy lines on the surface of the plates. There are no obvious surface irregularities when touching or chalk drawing. However, a certain deviation is allowed between the thickness of the plates and the nominal thickness, which is usually controlled at ± 0.5mm. The common equipment for surface sanding after veneering is a wide band sander, which is usually a three sanding frame. Rubber sanding wheels or air bag sanding pads with low hardness are used as sanding heads, and 150~240 fine sandpaper tapes are installed. The one-time sanding amount of surface sanding shall be controlled within 0.1~0.2mm, and 80%~90% of the surface water adhesive paper can be sanded off. For the plate with a little bending, the sanding amount should be reduced to avoid sand damage at the maximum sanding amount; The wide band sander can not be used for severe bending and warping, and the narrow band manual sander is usually used. Veneer hot pressing veneer technology The veneer veneer usually adopts the hot pressing veneer technology, which includes specific processes such as sheet gluing, blank assembly and hot pressing. Base material gluing technology gluing machine: double side gluing machine, single side gluing machine and manual gluing machine are common, and the most common one is double side gluing machine. Glue: urea formaldehyde resin glue (UF) or polyvinyl acetate lotion (PVAc, commonly known as white emulsion). UF is the most widely used glue due to its high bonding strength, good operability, fast curing speed (within 2 minutes) and low price. In recent years, due to the requirements of environmental protection, there are more and more modified PVAc for hot pressing veneer. Prefabrication technology Hot pressing veneer technology Prefabrication: When hot pressing veneer with fast curing glue is used for processing, the veneer can be directly covered on the board after being coated with glue and then sent to the hot press for pressing treatment. The veneer shall be about 10mm larger than the base material. Cold pressing veneer technology assembly: after the veneer is coated and assembled, it is usually required to put it on the press for a period of time to make the glue fully contact with the veneer and improve the veneer quality. Hot pressing veneer technology equipment: multi-layer hot press or short cycle single-layer hot press. The multi-layer hot press is mainly suitable for the gluing operation of most small and medium-sized furniture enterprises or small specification boards. Short cycle hot press is suitable for mass production enterprises. Hot pressing parameters: hot pressing pressure (P), temperature (T) and time (t), commonly known as hot pressing. Pressure: usually 0.6~1.2MPa; Hot pressing temperature and time: Generally, the temperature of UF glue shall not be lower than 110 ℃ (usually 120~130 ℃). The higher the temperature, the shorter the hot pressing time and the higher the production efficiency; However, if the temperature is too high, the adhesive layer of the veneer will easily crack. Modified PVAc is usually used for low-temperature hot pressing, and the general temperature shall not be higher than 100 ℃ (usually 90~105 ℃). The thicker the base material is, the slower the heat transfer is, so the hot pressing time is required to be prolonged accordingly. In actual production, the specific time is usually determined through experiments, and the basic curing of glue after hot pressing shall prevail. ▲ The hot pressing parameter setting of urea formaldehyde glue # 671 veneer veneer shall refer to the standard printing decorative plastic veneer. At present, the plastic films used for veneer of panel parts mainly include polyvinyl chloride (PVC), polyethylene (PVE), polypropylene (Alkorcell), polyester (PET) and polypropylene (PP). Because PVC is the most widely used, it is often said that PVC is a general term for printing and decoration plastics in actual production. PVC is a kind of widely used surface decorative material, commonly known as plastic veneer. PVC has soft texture, good elasticity and good water resistance, which is very suitable for veneer and edging of special-shaped parts; However, PVC has low hardness, heat resistance, easy scalding and scratching, and poor wear resistance, so it is mainly used in occasions where the contact frequency is not very high. Substrate gluing Substrate: MDF (medium fiber board) with high quality is commonly used. PB board can also be used as the base material when pasting the film on the flat board. Adhesive: nitrile rubber adhesive, polyvinyl acetate lotion (PVAc), polyurethane (PU) adhesive, propylene vinyl acetate copolymer lotion, ethylene vinyl acetate copolymer lotion (EVA), vinyl acetate acrylic acid copolymer lotion, etc. The glue amount is generally 80~150g/㎡. Adhesive method: wet adhesive, finger touch dry adhesive, reactivated adhesive. PVC facing technology for flat panel There are two methods of PVC facing for flat panel: flat pressing method and roller pressing method. The flat pressing method is generally cold pressing method, which has been rarely used in actual production due to low production efficiency. The most commonly used method for veneer of plane parts is the rolling method. The specific working process is as follows: 01 The base material is first treated by the brush roller dedusting machine; 02 The roller gluing machine is used for gluing; 03 The rolling gluing pressure is 1.0~2.0MPa. PVC vacuum cladding technology The PVC cladding of surface formed panels generally adopts the vacuum coating method, commonly known as soft forming veneer. This method has uniform pressure and good veneer effect, but it requires special surface equipment and has low production efficiency. The basic working process is as follows: 01 The workpiece after spraying glue is placed on the workbench; 02 After the glue is dry, the surface is covered with PVC film and clamped to make the workbench enter under the heating plate, and the upper platen is closed to make the upper and lower working cavities sealed; 03 Vacuumize the upper working chamber to remove the cold air in the chamber, and at the same time make the PVC film contact with the upper heating plate for heating and softening; 04 Vacuum the lower working chamber, and inject compressed hot air into the upper working chamber to make the PVC film close to the substrate; 05 After the glue is solidified, remove the positive and negative pressure from the upper and lower working chambers, and turn on the press to complete the pasting of the film pressing parts; 06 The workpieces shall be out of the film and stacked neatly. After the workpieces are cooled, the excess PVC film at the edges shall be removed with tools or sandpaper. Decorative paper Decorative paper is one of the main materials for wood-based panel surface decoration, accounting for more than 50% of the wood-based panel surface decoration. There are many types of decorative paper, which can be divided into thin paper (30g/m2) and decorative paper according to the quantity; It can be divided into Baoli Paper, Gorgeous Paper, Pre painted Paper, Low Pressure Melamine Impregnated Paper, High Pressure Melamine Decorative Paper, etc. Roller press veneer process The roller press veneer is suitable for soft decorative paper, such as thin paper and some pre painted paper. Rolling operation is generally completed continuously in a whole production line, which can be divided into basic processes such as substrate surface sanding, surface dedusting, gluing, pre drying, laminating, and rolling veneer. Flat pressing veneer process The flat pressing veneer requires decorative paper to be neat, thick and smooth, so it is mainly suitable for thick pre painted paper, low pressure melamine impregnated paper, fireproof board and other decorative paper. The precoated paper is usually hot pressed at low temperature, the impregnated paper is often hot pressed at high temperature, and the fireproof board is usually cold pressed. The specific process of the flat pressing method can be divided into the basic processes of paper preparation, substrate gluing, blank assembly, pressure gluing, etc.
