How is hot melt adhesive produced? Popular science on the manufacturing process from raw materials to granules

Many people use hot melt adhesive to sew books and seal boxes, but they rarely think about how this glue is made. Simply put, hot melt adhesive isMix several raw materials together and melt them, then squeeze them out and cut them into small particlesof Let’s explain this production line clearly below (taking the most common EVA hot melt adhesive as an example).

1、 What is the raw material of hot melt adhesive

• Main base material: EVA (ethylene vinyl acetate copolymer)The training materials clearly state that EVA is the main type of hot melt adhesive. It heats and melts, cools and solidifies, and its characteristic is that its physical state changes with temperature while its chemical properties remain unchanged – this is the fundamental reason why hot melt adhesive can be repeatedly heated and used.
• Tackifying resinImprove initial adhesion and bonding strength, allowing the adhesive to better grip different surfaces such as paper and plastic.
• Wax typeAdjust the opening time, hardness, and fluidity to affect the spreading speed during machine operation.
• Antioxidants and other additivesSlow down oxidative aging at high temperatures and stabilize batch quality.
• Different uses (book and magazine back glue, edge glue, pearl cotton, packaging) rely on adjusting the proportions of these materials to obtain formulas with different softening points, viscosities, and opening times.

2、 The manufacturing process from raw materials to granules

1. ingredientsAccording to the formula, EVA base material, tackifying resin, wax, and additives are quantitatively added, and the ratio is the core (the specific formula/equipment is subject to the actual production line and belongs to the enterprise process).
2. Melt mixingMelt and stir each component evenly at high temperature, allowing the resin and wax to be fully dispersed into the EVA matrix, forming a uniform melt.
3. extrusion moldingUniform melt is extruded into continuous strips or flakes through a die.
4. Cooling and solidificationThe material strip is re solidified from a molten state to a solid state through a cooling water tank or air cooling.
5. pelletizingThe solidified material strip enters the granulator and is cut into cylindrical particles/round particles/block shapes (the shape varies depending on the model).
6. Screening and PackagingFilter out dust and particles, package and store according to batches, and wait for shipment.

3、 Why does’ well made ‘directly affect computer performance

• Uneven mixing → performance driftThe resin dispersion is not good, and the same batch of glue may not stick here and there, resulting in random occurrences of falling pages and wire drawing on the machine.
• Unstable temperature control → carbonizationIf the melting temperature is too high or locally overheated, EVA will thermally disintegrate, carbonize and become brittle (the best temperature for use is 160-180 ℃), and the back of the finished book will become brittle and easy to peel off.
• Batch consistency → Process replicableStable ingredients and temperature control are necessary to ensure that the opening time and viscosity of each batch of adhesive match the process card, and printing factories do not need to readjust machines when changing batches.

Sunlife’s Manufacturing and Quality Control Positioning

Sunlife (Sunlife/SL) hot melt adhesive is manufactured by Foshan Jucai Base, focusing on the fields of book binding, etc. It ranks among the top five in terms of sales volume in the book field nationwide and the first in South China. From ingredients, melt mixing to granule packaging, each batch is temperature and ratio controlled according to the process card, and then matched with real models (books and magazines 292/296/295/298, flat 391, graphic store 393/395, pearl cotton 39B/399, etc., the model is subject to the process card) and shipping stock, so that the printing factory can obtain glue with “parameters matched and batch stable”.

Frequently Asked Questions

Q: Hot melt adhesive is chemically synthesized, is it environmentally friendly?
A: EVA hot melt adhesive is a relatively clean bonding method with 100% solid content, heated use, and no solvent evaporation; The RoHS ten items of Sunlife related samples were not detected (the report is only responsible for the submitted samples).

Q: Are particles of different colors made from different raw materials?
A: Colors are mostly used for identification purposes (distinguishing models/batches), and the core differences lie in formula ratios and performance parameters, rather than the colors themselves; The specific model and process card shall prevail.

Q: How to determine the reliability of the factory when buying glue?
A: Check if the corresponding parameters, process cards, batch testing, and supply stability of the actual model can be provided.

Hot melt adhesive is not a “black box” formed by melting – it is made by adding several types of additives to EVA base material, melting and mixing, extruding, cooling, and cutting into granules. Stabilize the formula and temperature control so that every piece of glue is truly easy to machine and stick firmly.