Adhesives production

Advantages of co-rotating twin-screw extruder in the production of adhesives.

Usually, the production of adhesives occurs with discontinuous systems, resulting in a series of critical issues. However, through the continuous process with our co-rotating twin-screw extruder, we are able to overcome them, while obtaining the following advantages:

• Easy reproducibility;
• Simplified cleaning: the screw profile of the co-rotating twin-screw extruder, being self-cleaning, allows a quick transition from one formulation to another;
• Closed system and safer process for the operator thanks to reduced exposure to the solvents used;
• Completely automatic process with precise dosing of the formulation components through the use of gravimetric feeders;
• Continuous monitoring of process parameters.

Many years of experience in the sector have allowed us to optimize co-rotating twin-screw extruder technology for the continuous production of the different types of adhesives:

·     HOT MELT ADHESIVE
·     SOLVENT BASED ADHESIVE
·     TOTAL SOLID ADHESIVE

Continuous hot-melt production

Adhesive extruders

Discontinuous production of solvent-based adhesive

The traditional discontinuous production of solvent-based adhesive entails various issues, also in terms of safety:

• Conspicuous percentage of solvent, which is between 65% and 70%;
• Presence of a considerable quantity of solvent-based adhesive in the production area, due to the large size of the dissolvers;
• Prolonged solvent evaporation times and significant dispersion in the production environment;
• High-energy consumption due to solvent evaporation;
• Low level of automation.

Our consolidated experience in the sector has guided us in the development of continuous production systems, specifically designed to successfully address the issues of traditional production. This has allowed us to obtain results such as:

Significant reduction (up to 40%) in the percentage of solvent;

• Low quantity of solvent-based adhesive in the production area;
• Reduction of solvent evaporation timing;
• Lower energy consumption for solvent evaporation;
• Adoption of a closed system and drastic reduction in solvent dispersion in the work environment.

Our production systems are divided into two categories: one step and two steps. Both processes are patented.

Solvent-based adhesive

The discontinuous (traditional) production of solvent-based adhesive shows the following critical issues:
  • large percentage of solvent (between 65% and 70%);
  • large quantity of solvent-based adhesive in the production area, due to the large size of the dissolvers;
  • extended solvent evaporation times;
  • high energy required for evaporation of the solvent;
  • significant quantity of solvent dispersed in the production environment;
  • low level of automation.
Thanks to the considerable experience gained in the sector, we offer continuous production systems that overcome the following issues:
  • the percentage of solvent can be reduced by up to 40%;
  • low quantity of solvent-based adhesive in the production area;
  • reduced solvent evaporation times;
  • lower energy for solvent evaporation;
  • closed system and drastic reduction of solvent dispersed in the working environment.

One step

PATENTED

In the one-step process, a single extruder handles the production of the adhesive.

The rubber and solid components are fed into the first part of the extruder, followed by the gradual addition of solvent at various points along the extruder. Downstream of the extruder, a screen changer is followed by two tanks: one for the ‘re-melt’, which recycles a small percentage of adhesive during the start-up and stop phases, reducing waste, and the other connected directly to the coating line. In case of frequent color changes, it is possible to color the material by using a dedicated extruder downstream of the production plant and before coating.

Process of the extrusion of adhesives

Two Steps

PATENTED

The two-step process offers greater flexibility and output. It involves two drop-down co-rotating twin-screw extruders, each with unique features: the first extruder takes care of mixing the solid materials and a fraction of solvent, while the second completes the recipe according to the percentage of solvent present in the formulation. The use of two subsequent tanks reduces waste and facilitates the recycling. Furthermore, it is possible to install a small coloring extruder, which facilitates cleaning for frequent color changes.

Extrusion adhesives process

Total solid adhesive production

For this type of material, the formulation excludes the use of solvent and includes a significant percentage of mineral filler, usually CaCO3.

The extruder is set up according to a specific layout: the rubber and any additives are fed in the first part. In accordance with the formulation and to improve quality, both the resin and CaCO3 can be split along the extruder.

If present in the recipe, it is possible to inject process oil along the extruder.

Extrusion Adhesives