Adhesion is the measure of strength with which one material sticks to another.
Adhesion is one of the key performance criteria for ALG's products.
To solve our customers' adhesion problems and meet their adhesion requirements, ALG focuses on:
If you have adhesion performance problems or tough application requirements, the ALG sales and customer service teams, along with our product managers, will listen, recommend and then test, proving out our recommendations for your specific applications.
There are 4 key factors that must be considered in determining adhesion:
Below, are the related areas that ALG can provide experience and knowledge to your adhesion challenges.
ALG has expertise in providing adhesion solutions for the following surfaces:
ALG has adhesion solutions for the following conditions:
There are many applications where removability of a label is required.
ALG has a wide variety of solutions for label removal across many surfaces.
See in our Performance section, the Tamper Evident page
for detailed information.
Environmental and Application Conditions
An adhesive designed to stick to a substrate without edge lifting and that cannot be removed without damaging either the label or the substrate.
An adhesive designed to stick to a substrate without edge lifting that can be removed without damage to either the label or the substrate.
Good, acceptable adhesion is when a label is removed or attempted to be removed and the:
Good, Acceptable Adhesion
The measurement of the force required to remove a material from another surface at a specified angle and speed, after the material has been applied under specific conditions.
The measure of the time required to slide a specific sized area of a pressure sensitive label material from a standard flat surface in a direction parallel to the surface. Weight and heat are sometimes used to speed up the test.
The final bond, achieved under controlled conditions, between ink, coating or adhesive to any flexible or rigid substrate.
Initial Tack is the quality or strength of a material's tack (or "stickiness") at the point of application, while the material is in a fluid or semi-fluid state.
A label with high initial tack will grab the substrate quickly.
A label with low initial tack will exhibit a low level of adhesion when first applied and may remove cleanly.
Ultimate Adhesion is the ultimate or maximum holding power that the label will achieve as the adhesive penetrates into the substrate.
The time required to obtain ultimate adhesion may depend on the stiffness (shear) of the adhesive, the roughness of the substrate and the temperature of the environment.
Ultimate adhesion is usually achieved in 72 hours after application.
Shear Resistance is a measure of the internal cohesive strength of the adhesive. The shear of the adhesive is an indication of how soft an adhesive is.
A low-shear (soft) adhesive has more of a tendency to flow (resulting in higher initial tack), and has a higher chance that the adhesive will split apart if put under stress.
A high-shear (firm) adhesive is less likely to split under stress due to its good internal, cohesive strength, and will be less likely to flow (possibly lower initial tack).
Application Temperature is the temperature of the actual label material or the surface to which the label will be applied at the time of the label application.
All adhesives have a minimum application temperature rating.
If the application temperature is below the minimum application of the adhesive, the label adhesion will be negatively impacted.
Service Temperature Range is the temperature range that a label will withstand after being applied to the substrate for a 24-hour period.
The range is expressed in degrees Fahrenheit or Celsius.
Repositionability is the ability of a pressure sensitive label to be bonded to a surface, then removed and repositioned.
This can be done for a limited period of time after application (e.g., 20 minutes).
Beyond that time, the bond may begin to become permanent if a removable adhesive was not used.
Solvent-based Acrylic Adhesives are acrylic polymers in petroleum-based solvents.
Advantages of solvent-based adhesives are their strength. They provide superior shear and peel strength versus water-based and rubber-based adhesives.
Solvent-based acrylic adhesives are used in outdoor applications because of their overall strength and resistance to moisture, environmental conditions, chemicals and ultraviolet light.
Emulsion-based Acrylic Adhesives are commonly used for packaging, labeling and tapes. There are both permanent and removable formulations.
Permanent formulations offer high tack and peel strength.
Removable formulations maintain a more consistent level of removability throughout their life.
Rubber-based Adhesives are formulated from organic or synthetic rubbers. Rubber-based adhesives are cost effective however, they are negatively impacted from exposure to environmental conditions and ultraviolet light.
They are designed for general purpose applications like sticking to boxes and containers in indoor applications.
Rubber-based adhesives, in general, exhibit higher initial tack (quick stick) because of the softer formulation, however they are more prone to cause sticky edges because of adhesive flow (edge ooze*).
Removable rubber-based adhesives tend to increase in adhesion throughout the life of the label and could possibly become permanent.
Emulsion-based Acrylic Adhesives
LOOP TACK TEST
This test provides adhesion data on the initial
tack of the adhesive to the surface. The loop
value of a pressure sensitive label is the force
required to separate, at a specific speed, a
loop of material/adhesive, which has been
brought into contact with the surface.
Once full contact to the surface has been achieved, the loop of material/adhesive is reversed and measured. The contact is for only a second or two.
180 DEGREE PEEL TEST
The 180 Peel Test is similar to the 90 degree peel test with the exception exception being the bonded area between the label and surface is
is placed vertically between the peel test grips while the free end
is gripped by the bottom and the free end of the label is gripped
by the top so that it creates a "U" shape.
ALG has this test performed for initial tack after the label has been applied to the surface for 10 minutes.
POLYKEN PROBE TACK TEST
This probe tack test is important for determining adhesive properties. The test is administered with a machine that brings the tip of a probe into contact with a pressure sensitive adhesive that is held in a fixed position.
These will allow for control parameters to be tested that include speed, contact pressure, dwell time between the probe and the test surface, and the rate of separation between the two.
It allows for testing using a variety of options such as choice of surface material, tip shapes and sizes, fixture options, and control of the probe itself.
90 DEGREE PEEL TEST
This test requires a 90 degree peel test fixture to
determine the adhesion between a label and
rigid surface, where the surface lies horizontally
with the gripped end of the label sticking up perpendicular, while the rest of the label is bonded to the plate so that it forms an "L" shape.
ALG has this test performed for initial tack after the label has been applied to the surface for 10 minutes. The same test is then performed after the label has been applied for 24 hours and again at 72 hours to represent ultimate bond.
A Shear Test is to apply stress from the label to the surface so that it experiences a sliding failure as force is being applied in the form of weight.
The label is applied to the surface and hung vertical with a per-determined weight applied to the bottom portion of the label. The label, surface and weight are allowed to hang until the label moves or slides off of the surface. The time it takes is the shear value. Most label shear tests are stopped after 48 hours.
LOOP TACK TEST
180 DEGREE PEEL TEST
POLYKEN PROBE TACK TEST
90 DEGREE PEEL TEST
ALG Labels and Graphics is a custom manufacturer of pressure sensitive labels and decals celebrating over 50 years in business. Our focus is delivering value to our customers with responsive service, quality products and low cost production. Our mission is to make it easy for you to do business with ALG.
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Birmingham, Alabama 35233
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