EVA Hot Melts for Packaging
The manufacturing process of EVA hotmelt involves blending the ethylene vinyl acetate copolymer with additives. The mixture is then heated to a specific temperature, typically within the range of 150 to 180℃, until it becomes a molten liquid. This molten adhesive is then applied to substrates using various methods, such as slot coating, spray coating, or bead extrusion.EVA is a copolymer adhesive, most commonly used in the paper, packaging, and assembly industries, as they bond to a variety of cellulosic materials and have a wide range of formulation. The composition of the adhesive will directly influence its properties. Because they can be specifically formulated for various applications, there are several kinds available on the market.
Advantages of EVA Hot Melts For Packaging
Attractive price-performance ratio: EVA hot-melt adhesives offer an unbeatable combination of quality and cost-effectiveness, making them particularly attractive for companies looking for cost-effective solutions.
Short opening and setting times: In the fast-moving world of production, short curing times are crucial. EVA hot-melt adhesives offer exactly that – fast open and setting times that speed up the production process.
Proven technology and excellent adhesion: EVA hot-melt adhesives have proven themselves over decades. Their excellent adhesion capabilities, even on difficult surfaces, make them a reliable choice in many different applications.
Wide formulation options: The versatility of EVA hot-melt adhesives is demonstrated by their ability to be used in a wide range of applications. From the construction industry to floristry, they offer solutions for a wide range of requirements.
Why Choose Us
Our Factory
Zhejiang Good Adhesive Co., Ltd was established in 1996 in China, covers an area of more than 10000 square meters with annual output of 30000tons of environmental friendly hot melt adhesive series products base on EVA, polyolefin, elastomer, polyurethane, PA and animal protein.
Our Products
We specialize in researching, manufacturing, and selling hot melt adhesive with annual output of 30000tons of environmental friendly hot melt adhesive series products base on EVA,polyolefin,elastomer,polyurethane,PA and animal protein.
Applications fields
Applications fields cover bookbinding industry, packaging industry, tape and label coating, automobile assembly, interior decoration and damping sealing, air filter making, sanitary and medical products making, furniture industry, pest control, etc.
R&D Team
We have our own lab and R&D team, can provide you technical supports at any time. Raw materials are imported from American Dupon and Exxon, Canadian AT, Japanese TOSOH, etc., and our stric QC system will be the best safeguard for you.
Ethylene, on the one hand, promotes adhesion to non-polar substrates such as polyethylene and provides mechanical strength, blocking resistance and is soluble in paraffin. Vinyl acetate, on the other hand, promotes adhesion to polar substrates such as paper and provides flexibility, adhesion and improved low temperature performance.
For example, a higher proportion of ethylene in its composition will provide an EVA adhesive with higher strength, while a higher amount of vinyl acetate will provide stronger adhesion to paper products and improve the flexibility of the adhesive. EVA adhesives containing higher amounts of vinyl acetate can also operate at lower temperatures, have improved wettability and also a longer open time and slower set.
Working of EVA Hot Melt
The EVA hot melt adhesive is applied from the melt, gaining strength upon solidification and crystallization. Although certain types of EVA hot melt adhesives can crosslink over time or with an outside energy source, general-purpose EVA hot melt adhesives remain thermoplastic after application and gelling.
The working mechanism of EVA holt melts includes the steps listed below
Step 1: A hot melt adhesive when heated, melts and becomes a liquid. It is then applied by bringing it between two substrates. Once cooled, it will set and solidify. The cooling of the drop largely depends on the size of the droplet, nature, and temperature of the substrate. In case the substrate is not insulated, it may take a lot of time for the hot melt to cool down.
For example; if the EVA hot melt is applied on a cold surface, the EVA hot melt would cool faster, but the adhesion imparted would be weak as the adhesive will not get enough time to fill in the cavities of the substrate. On the contrary, if the EVA hot melt was applied on a pre heated surface and then allowed to cool gradually along with the substrate, the adhesion would be stronger.
Step 2: The second substrate is applied to the adhesive, in order to join the two substrates with the help of EVA hot melt applied between them.
Step 3: The second substrate is pressed, and one can see the adhesive oozing out, in case the contact surface with the substrate is large. The large surface area of the substrate allows for quicker cooling of the EVA hot melt. This hot melt after cooling sets, making it impossible to separate the two substrates.
The horizontal axis describes the temperature, which decreases with time. The relationship between temperature and time is never the same.
The vertical axis exhibits the viscosity or the cohesion for a period when the EVA hot melt is liquid and cohesion for the later stages of the EVA hot melt.
Precautions When Using EVA Hot Melts
Compression
The right amount of compression will prevent spontaneous bond failure or poor long-term bond integrity, if compression is too low; or deformation of the substrates so that adhesive/substrate contact is inadequate with the bond broken during consolidation, if compression is too high.
Wetting out
Sufficient compression at a high enough temperature should allow difficult surfaces to be properly wet out, such as coated packaging materials that have low surface energy.
Open time
The hot melt glues open time must be equal to that of the application. If the open time is too short, the substrate will not wet out and bonding will not take place or bonds will fail shortly afterward. If too long, then insufficient time will elapse for the hot melt to lose heat and acquire sufficient green strength to prevent the flaps from springing open when leaving the compression section.
Adhesive quantity
The optimum amount of hot melt must be applied to affect an adequate bond. Too much will lead to open time problems, increased consumption, stringing, and squeeze out during compression – leading to machinery contamination and unnecessary cleaning. With too little adhesive applied, the open time and set speed will be reduced, as will the gap-filling properties, wet out of the adhesive, and ultimately, it's bond formation.
Key Application Points of EVA Hot Melts for Cardboard Boxes
Material Selection and Performance Matching
The selection of hot glue for cardboard boxes needs to consider various factors such as the properties of the materials to be bonded, packaging requirements, and production conditions. Different types of hot melt adhesives vary in viscosity, open time, curing speed, etc., so it is essential to ensure that the selected hot melt adhesive matches the material of the carton to achieve the best bonding effect.
Equipment Adjustment and Operational Norms
The bonding effect of hot melt adhesive is also influenced by packaging equipment. On high-speed production lines, it is necessary to ensure that the hot melt adhesive spray gun works stably to avoid issues like leakage or uneven application. Additionally, operators must strictly follow operational procedures to ensure that the sealing position is pressed within the open time of the hot melt adhesive to guarantee bonding quality.
Environmental Control and Temperature Management
Ambient temperature significantly affects the curing speed and bonding effect of hot melt adhesive. In cold environments, the curing time of hot melt adhesive shortens, which may result in weak bonding. Therefore, manufacturers with conditions should control the working environment temperature within a suitable range (e.g., above 20 degrees Celsius) before bonding production to fully leverage the bonding performance of hot melt adhesive.
Quality Control and Testing
To ensure the bonding quality of packaging cartons, strict quality control should be conducted during production. This includes regular testing of the adhesive strength of the hot melt adhesive to ensure that the packaging box remains stable even under different load conditions. Additionally, attention should be paid to the external appearance quality of the packaging boxes to avoid excessive penetration of hot melt adhesive affecting aesthetics.
Factors Affecting the Bonding Quality of Hot Glue for Cardboard Boxes and Solutions
Production Process Factors
Equipment Speed Issues
To address the issue of leakage caused by excessive speed of packaging equipment, optimizing equipment settings and increasing monitoring measures can be effective. Regular maintenance of the equipment ensures it remains in good working condition.
Neglect of Operational Details
Enhance the training of operators to improve their awareness of hot melt adhesive usage requirements. Ensure strict adherence to operational procedures during production to avoid bonding quality problems caused by improper operations.
Carton Material Factors
The Challenge of Bonding Laminated Cartons
To address the difficulty of bonding laminated cartons, a type of hot melt adhesive with a special formula that can penetrate the film surface should be used. This kind of hot melt adhesive can break through the varnish layer on the film surface, achieving effective bonding with the carton substrate. Additionally, extending the open time appropriately ensures the hot melt adhesive fully infiltrates and bonds the film.
Balancing Penetration and Appearance
While pursuing moderate adhesive force, it is also essential to consider its impact on the surface appearance of the cartons. By adjusting the formula and process parameters of the hot melt adhesive, the goal is to avoid excessive penetration that affects the appearance while maintaining acceptable adhesive strength.
Packaging is essential to any business that deals with physical products. It's what keeps your products safe during transportation and storage, and it's what makes them stand out on the shelves. That's where hot melt adhesives come in. Hot melt adhesives are a popular choice for packaging applications because of their superior bonding properties.
Factors to Consider When Selecting Hot Melt Adhesives
When selecting a hot melt adhesive, there are several factors to consider. The first factor is the type of substrate you'll be bonding. Different substrates require different adhesives, so it's important to choose the right adhesive for your specific application.
The second factor is the environmental conditions the adhesive will be exposed to. If so, you'll need to select an adhesive that can withstand those conditions.
The third factor is the speed of production. Some adhesives require a longer set time than others, so it's important to choose an adhesive that can keep up with your production speed.
EVA Hot Melts Testing
Before implementing a new hot melt adhesive, it's important to conduct thorough testing to ensure it meets your bonding requirements. This testing should include both mechanical and environmental testing to ensure the adhesive can withstand the rigors of your packaging application.
Mechanical testing should include testing the adhesive's shear and peel strength.
Environmental testing should include exposure to extreme temperatures, moisture, and humidity. By conducting thorough testing, you'll be able to ensure the adhesive will perform as expected in your specific application.
What Is the Difference Between PUR Hot Melt and EVA Hot Melt
PUR hot melt adhesives can be used in: wood, construction, industrial filters, automotive interiors and assemblies, textiles, packaging, electronics, and so on.
The difference between PUR and EVA
1. PUR is polyurethane, and EVA is ethylene vinyl acetate.
2. The reaction mechanism of PUR is moisture curing, which is an irreversible reaction. This irreversible reaction can provide better strength and heat resistance. EVA is physically bonded and will remelt after heating, which is reversible.
3. The packaging of PUR hot melt adhesive is sealed, and the application of glue requires professional equipment that can be sealed. EVA is not required.
PUR is a moisture curing reactive polyurethane hot melt adhesive. The main component is isocyanate-terminated polyurethane prepolymer. PUR has adjustable adhesion and toughness (elasticity) and has excellent bond strength, temperature resistance, chemical resistance and aging resistance. It has become one of the important varieties in the adhesive industry.
EVA hot melt adhesive is a solvent-free, moisture-free, 100% solid-melt polymer. It is solid at room temperature. When heated and melted to a certain extent, it becomes a fluid and viscous liquid adhesive. It is a light brown translucent body or white after melting.
Compared with EVA hot melt adhesives, water-based and solvent-based adhesives, PUR hot-melt adhesives have the following advantages: no solvent, one-component type. Unlike solvent-based adhesives, which require a drying process, there is no environmental pollution and poisoning problems due to solvents, and it meets environmental protection requirements. The bonding process is simple, and sizing methods such as roller coating or spraying can be used.
Operability is good. The two adherends can be fixed in a short time, so the assembly can be quickly transferred to the next processing procedure to improve work efficiency. Excellent heat resistance, cold resistance, water vapor resistance, chemical resistance and solvent resistance. Compared with the original hot-melt adhesive, due to the cross-linked structure of the reactive hot-melt adhesive, the listed properties and bonding strength are greatly improved.
Why Does EVA Hot Melts Draw Wire During Use
Cohesive strength of hot melt adhesive
The cohesive force and drawing effect of hot melt adhesive are basically: the cohesive force is large, and the drawing phenomenon is obvious; on the contrary, the cohesive strength is low, and the drawing phenomenon will not occur.
Curing time of hot melt adhesive
The curing time of the hot melt adhesive is very important for the occurrence of wire drawing. Generally speaking, the hot melt adhesive with short curing time has a low drawing rate, because the filament formed after the hot melt adhesive is cured cannot continue to be stretched, and it is prone to breakage, and sometimes it is not even drawn out.
Rheology of molten hot melt adhesive
The rheology of the molten hot melt adhesive has a decisive influence on the drawing, which is related to the design of the hot melt adhesive formula, the selection of materials in the formula, and the composition.
The influence of machine temperature
If the temperature is too low, the thinness of the glue itself will increase, and there will be a wire drawing phenomenon.
FAQ
As one of the leading EVA hot melts for packaging manufacturers and suppliers in China, we warmly welcome you to wholesale high quality EVA hot melts for packaging from our factory. Also, custom service and cheap products are available.
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