I. What is extrusion rate? 

Adhesive extrudability (also referred to as extrudability) refers to the amount of adhesive that is extruded from a standard cartridge under specified temperature, pressure, nozzle orifice diameter, and time conditions. /  The rate of mass or volume extruded from the packaging (common units: g/min、mL/min ), is a measure of paste-like /  The extrusion rate is a key indicator of the ease of application and caulking efficiency for semi-paste adhesives. A lower extrusion rate indicates a thicker adhesive, while a higher extrusion rate indicates better flowability. 

Scope of application: Primarily used for paste-like and semi-paste-like adhesives (such as sealants and structural adhesives); flowability /  The flowability of semi-fluid materials is generally measured using a rotational viscometer. 

II. Factors Affecting Extrusion Rate 

1. Temperature and Humidity 

Temperature and humidity are two critical factors that influence the extrusion rate of adhesives. As temperature increases, the adhesive’s flowability improves, leading to a higher extrusion rate; conversely, at lower temperatures, the adhesive’s viscosity rises, resulting in a reduced extrusion rate. Excessively high humidity can adversely affect the adhesive’s viscosity and flowability, thereby decreasing its extrusion rate as well. 

2. Applied pressure 

The pressure applied to the adhesive is a direct factor influencing the extrusion rate. Increasing the applied pressure generally leads to an increase in the extrusion rate; however, beyond a certain point, the adhesive’s extrusion rate may reach a saturation level. 

3. Rheological Properties 

The rheological properties of adhesives describe their deformation and flow behavior under stress. Some adhesives exhibit shear-thinning, meaning that their viscosity decreases under shear, thereby increasing extrusion rate. 

4. Rheological Index 

The rheological index is a parameter that characterizes the rheological properties of a liquid and directly affects the extrusion rate. Adhesives with a high rheological index exhibit more pronounced viscosity changes under stress, which may result in a lower extrusion rate. 

III. Common Testing Methods and Tools 

1. Manual testing : Use a simple caulking gun to observe whether the adhesive extrudes smoothly; this is suitable for rapid assessment. 
2. Instrument testing : Utilize specialized equipment to precisely control pressure and temperature, thereby obtaining quantitative data. 
3. Simulation Scenario Testing : Conducted under conditions that closely mimic actual construction, providing a more realistic representation of real-world usage. 

The glue extrusion rate is a crucial performance indicator. Testing this parameter provides valuable insights into the adhesive’s flow behavior and viscosity characteristics, making it of great significance for adhesive material production and quality control. It is hoped that this article will help readers better understand the extrusion rate of adhesives and the associated testing methods, thereby offering useful guidance for industrial manufacturing.

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