No furniture production is able to do without special adhesive compounds, which would ensure high-quality adhesion of parts during assembly. It is for these purposes that hot melt adhesive is used, which is a solid granule that acquires a viscous flow state when heated and quickly hardens when cooled.
Structure
The properties of this material are provided with special components in the composition. Most often, adhesive materials are made on the basis of vinyl acetate and ethylene copolymer.
This combination gives the product:
- adhesive strength;
- good viscosity;
- cohesive strength;
- Perfect compatibility with other materials.
To further improve the properties of the product, hot melt adhesive may also contain various:
- fillers;
- modifiers
- plasticizers;
- antioxidants.
All this gives the final material better wettability of the surfaces, increased elasticity, less shrinkage, low thermal degradation and much more.
Features of choice
In order for the hot melt glue to fit perfectly, it is necessary to take into account the peculiarities of the materials for facing panel parts. If in production only edges of a certain type are often used, then only hot-melt glue recommended for such products should be used. If different types of edges are used in the work with the same frequency, the adhesive should be chosen universal, which will suit equally for any material.
Glues filled and unfilled are also offered to consumers. The latter are cheaper and often attract attention, but their density is much higher, which means that the consumption during application will be large. As a result, cheapness does not justify itself. There are situations when such adhesives are nevertheless necessary, since they well fill the deep layers of particleboard.
Application Features
Also, when choosing, you should pay attention to the features of the glue itself. The material supplied in the form of rods does not require complete melting for operation. It is applied to the parts, gradually melting from one edge, thereby improving the quality of gluing. The PVC edge and EVA hot-melt adhesive can be joined according to another scheme, often used for complex structures. This option involves applying glue in a liquid state to the edge, after which it is supplied to the consumer. Further, for facing, the adhesive should be re-melted with hot air and connected to other parts. The speed of operation is rather low, but the glue consumption is low, which eliminates all kinds of defects in the porous structure of the bonding parts.
Storage conditions for parts
During operation, possible accumulation of moisture between parts and glue should be avoided, therefore, all edges and furniture parts can only be put into operation directly from a warm warehouse. In the case of their cold state, moisture condenses on the cooled edges and impairs adhesion of the parts with glue.
Working temperature
So that hot-melt glue can provide perfect bonding, you need to work with it only at certain temperatures. Typically, plants are able to provide the desired performance, but under certain conditions, temperatures can be reduced.
For example, with:
- the presence of a burnt layer of glue in the tank;
- low glue feed rate to the application site
- work with cold parts.
Application Nuances
To ensure optimum adhesion, the adhesive layer must be of the correct thickness. With too much glue, it will be squeezed out at the edges when pressed, but will provide better grip. A small amount of the composition will not lead to contamination of the working surfaces, but will not be able to provide the proper degree of bonding. After applying the material, the parts are immediately sent to the clamp, which is carried out by a steel press with smooth rollers.
Modern materials
Today, hot melt adhesive for PVC made of polyurethane materials is considered the best. This composition combines all the advantages of conventional and reaction products. Polyurethane adhesive is able to harden not only under the physical effects of temperatures, but also during chemical ones. Special isocytes in the adhesive structure form cross-links under the influence of moisture, thereby turning the composition into a three-dimensional adhesion structure.
Full hardening of such a product lasts several days, but it all depends on external factors:
- humidity of parts and the environment;
- temperature of parts and the environment;
- chemical composition of glue.
Glues of any composition should be stored strictly in dry enclosed spaces at certain temperatures, since under the influence of adverse conditions the material loses its properties. If moisture gets on the glue, it becomes unusable. After the glue completely goes into solid form, its resistance is observed in the temperature range from -30 to +150 degrees.