Common Adhesive Materials

In the self-adhesive industry, hot melt adhesive, hydrosol adhesive, and solvent adhesive are three common adhesive types. Each has unique performance characteristics that can meet the needs of a variety of application scenarios.

Hot Melt Adhesive

Hot melt adhesive is a rubber-based adhesive with high fluidity and viscosity, making it suitable for use in low-temperature environments (-5 to -10°C). It performs better than hydrosol adhesive when the surface of the object is exposed to trace amounts of oil or water. Features:

• Solvent-free, non-toxic, odorless, and environmentally friendly;

• High bond strength and speed;

• Suitable for labeling in low-temperature environments, but not high-temperature resistant;

• Poor repositionability, overall inferior to hydrosol adhesives;

• Hot melt adhesives are generally not suitable for PVC.

Water-based adhesives (Water-Borne adhesives)

Hydrosol adhesives are environmentally friendly, low-cost, and offer excellent initial tack, suitable for a variety of materials and environments. Although they are moisture-sensitive and cure slowly, their environmental and cost advantages make them a common adhesive for self-adhesive labels.

Features:

• Non-toxic and odorless, environmentally friendly;

• Excellent initial tack, quickly forming a strong bond with the surface being applied;

• Good temperature resistance, with some products capable of withstanding temperatures up to 150°C;

• Stable adhesion, which gradually strengthens over time;

• Not suitable for humid environments, and will not adhere well to surfaces with water or oil stains. 

Solvent Adhesives (Oil Adhesives)

Solvent adhesives are based on organic solvents (such as toluene and ethyl acetate). They offer high viscosity, high temperature resistance, and chemical resistance, making them suitable for specialized industrial applications.

Features:

• High viscosity, less prone to overflow;

• High temperature resistance, suitable for outdoor labeling;

• Suitable for a variety of materials and complex environments;

• Quickly and securely bonds to a variety of substrates;

• Short cure time, suitable for quick application;

• Water resistance, maintaining a certain degree of adhesion in humid environments.

Adhesive Classification

Self-adhesive label adhesives can be categorized into two main types based on their viscosity: permanent adhesives and removable adhesives.

This is determined by a combination of factors, including the specific application, material requirements, and the intended use environment. Below are key comparisons and selection recommendations:

Permanent Adhesives

Labels using permanent adhesives have a strong bond and are difficult to remove once applied, making them suitable for applications requiring long-term retention. Features:

• Difficult to remove completely after application; forcible removal may damage the label or the surface material.

• Resists long-term use and is highly resistant to environmental factors (such as heat, humidity, and oil).

• Residual adhesive may remain after removal, requiring cleaning with a solvent.

Applications

Suitable for applications requiring long-term fixation and difficult replacement, such as electronic tags, product packaging, and industrial signage. Due to its strong adhesiveness, it remains stable in a variety of environments.

Removable Adhesive

Removable adhesive self-adhesive labels use a specially formulated adhesive with moderate adhesion, making them easy to remove without leaving residue on the surface.

Features:

• Easy to remove after application, leaving no adhesive residue or damaging the surface.

• Adhesion may weaken over time, making them unsuitable for long-term exposure to harsh environments.

• Reusable (some types support a limited number of adjustments).

Applications

Suitable for applications requiring frequent replacement or adjustment, typically in food and personal care applications, such as office stickers, wet wipe labels, home decoration, and temporary marking. Factors to Consider When Choosing Glue

Object Material:

Select the appropriate glue based on the object being applied (e.g., glass, metal, plastic, etc.). For example, for metal, choose a glue with strong magnetic absorption.

Surface Preparation:

Ensure the surface of the object being applied is clean, dry, and free of oil and dust. Different label surfaces react differently to glue; rougher surfaces require a stronger adhesive.

Environmental Factors:

Consider the operating environment, such as outdoor use, exposure to high temperatures, humidity, UV rays, and proximity to hot car engines. These factors can affect the performance and durability of the glue.

Usage Duration:

For temporary applications, such as promotional labels or trial labels, choose a removable adhesive for easy replacement.

For long-term applications, such as product identification or asset labels, choose a permanent adhesive.

Environmental Requirements:

For labels used in industries with high environmental requirements, such as food and pharmaceuticals, environmentally friendly glues such as hydrosols or hot melts should be preferred. 

Surface Shape of the Object:

Label substrates can have flat or curved surfaces. If the label surface has a certain curvature (for example, a medicine bottle with a diameter less than three centimeters), the paper may require good adhesion or a stronger adhesive.

A material with increased flexibility and stretch resistance may also be needed.

The selection of adhesive for self-adhesive labels requires comprehensive consideration of factors such as the operating environment, the material of the object being applied, the label's shelf life, environmental requirements, cost budget, removal requirements, aesthetic requirements, processing technology, chemical resistance, and aging resistance.

A thorough assessment of these factors ensures that the selected adhesive meets the label's application requirements while ensuring the label's adhesion and longevity.