what's glue is used in plywood?
Author: source: Datetime: 2018-11-06 10:28:50
Plywood is made by glueing several layers of wood veneer (thin sheets of wood) over each other with the grain pattern alternating at right angles in every subsequent layer.Do you know which glue to glue plywood?
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).
Later on, adhesives are spread on these veneers using a glue-spreader machine. The machine helps in achieving a uniform glue spread. After
this the layers are placed upon each other and strongly pressed together using a hot-press machine. The high temperature and pressure created by the machine, ensures that the adhesive fully cures, thus firmly bonding the layers to each other.
The number of layers in each plywood sheet can vary (could be 3-ply, 5-ply ... 13-ply etc.) depending on the requirement.
There are two major types of adhesives used for making plywood, 'Urea formaldehyde' and 'Phenol formaldehyde'.
1. Urea formaldehyde 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.
2. Phenol formaldehyde 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.
JCT recommends that you use plywood glue.Plywood glue is produced by reaction vessel.JCT can provide you with reaction kettle and technical formula.
If you want to know more ,Please contact JCT Machinery :
E-mail: [email protected]