Plywood Manufacturers In Ahmedabad

Adhesives used for bonding of plywood. Plywood is made by gluing several layers of wood veneer which are thin sheets of wood over each other with the grain pattern alternating at right angles in every subsequent layer. During the plywood manufacturing process, the individual layers of veneer are first obtained by rotary-cutting a log. For this the timber logs are rotated about their longitudinal axis, while a cutter peels the log at the set thickness (each layer is usually less than 2.5 mm in thickness). Once this is done, a glue spreading machine is used to spread the adhesives on the veneer sheets, following this the sheets are placed upon each other and strongly pressed using a hot-pressed machine. The high temperature and pressure created by the machine help in ensuring that the adhesive is fully cured, therefore firmly bonding the layers to each other. As per the requirements, the number of layers in each plywood sheet vary. There are two major types of adhesives used for making plywood, ‘Urea Formaldehyde’ and ‘Phenol Formaldehyde.’ Urea Formaldehyde or UF Resins. – These are a type of adhesives known as aminoplastic synthetic resins. – Made by a chemical reaction between Urea and formaldehyde, these adhesives are cheaper than phenol formaldehydes. – Commercial MR grade plywood (Moisture resistant type) is often made using this kind of adhesive. Phenol Formaldehyde or PF Resins. – This is type of synthetic or artificial polymer that is obtained by a chemical reaction between 'phenol' and 'formaldehyde (methanal)'. – The ratio of formaldehyde to phenol is generally in the ratio 1.5:1. These types of phenolic synthetic resins are called 'resoles'. – Phenolic resins enable a stronger bond compared to urea based resins, and hence these are used in the making of exterior grade plywood (BWR-Boiling water resistant) and marine grade plywood. Health risks involving Formaldehyde. Several concerns have been raised regarding the potential health hazards are caused by formaldehyde emissions, according to general consensus it seems that a high amount of emissions does lead to some health hazards for humans. The use of these synthetic resins containing formaldehyde is why plywood can not be considered as eco-friendly as natural solid wood. However, over time the emissions reduce considerably and if the plywood is properly finished by either painting or using laminates, it also helps in making the product safer. We hope this was a helpful and informative read for you.