There are many types of shrink films. Some common ones are PE, POF, PVC, BOPP, PETG, PVDC, etc. They are used a lot in the packaging industry for things like shrink sleeve labels, cluster packaging, casing film, and other types of packaging for food, medicine, tobacco, electronic products, cars, everyday chemical products, and other things. Different products come in different shapes and sizes, so the shrink film needs to be very good at shrinking to meet the needs of different product packaging.
Heat shrinkable instruments, like heat shrinkable rate measuring instruments, can be used to test the heat shrinkability of materials and the heat shrinkability of different films in liquid media at different temperatures, like PE heat shrinkable film for integrated packaging of wine, cans, mineral water, and other drinks, as well as PVC, POF, Ops, pet, and other shrinkable films, flexible packaging composite films, PVC, and PVC hard film.
In short, the thermal shrinkage tester is a tool used to test how well film shrinks when it gets hot. The instrument can accurately and quantitatively measure the thermal shrinkage force, the cold shrinkage force, the thermal shrinkage rate, and other properties of plastic film as it shrinks when heated.
Connect the tested sample to the force sensor and displacement sensor, quickly heat it to the shrinkage temperature, and then cool it. The system automatically and in real time keeps track of the shrinkage force, temperature, rate of shrinkage, and other parameters, and then analyzes the measurements.
Why packaging materials should be tested for heat shrinkage?
Flexible packaging is a big business, and plastic film is an important part of it. Performance testing is a step that must be taken in order for packaging materials to meet their needs. The thermal shrinkage performance test of materials looks at how the size of plastic film doesn’t change when it’s heated, how the surface doesn’t shrink, and how the packaging doesn’t change shape. The shape and size of the product and the beauty of flexible packaging are both affected by how much plastic film shrinks when it gets hot.
Proper thermal shrinkage can make the package smaller, and uniform longitudinal and transverse shrinkage can make the film tighter and more even. This keeps wrinkles on the package cover from being caused by uneven shrinkage. The rate at which the size of a piece of film changes at a certain time and temperature is called its shrinkage.
Comparison of testing methods for thermal shrinkage of thin films
The shrinkage rate, the heat shrinkage force, and the cold shrinkage force that are made during the shrinkage process are all indicators of how well the film shrinks. If the performance of the three indexes is bad or the product isn’t useful, the shrinkage of the film will be loose, the fit of the body will be bad, and the product may even be extruded and deformed. At the moment, the oil bath method, the oven method, and the air heating method are the main ways to test the thermal shrinkage properties of films.
The oil bath method involves putting a sample of film cut to a certain size into heat transfer oil (like silicone oil) at a certain temperature to heat and shrink it. After a certain amount of time, the sample is taken out and its size is measured. The sample’s shrinkage rate is the ratio of the size change before and after shrinkage to the size before shrinkage.
As the name suggests, the oven method involves putting a sample of a certain size into an oven set to a certain temperature. After a certain amount of time, the sample is taken out and its size is measured. The shrinkage rate of the sample is then calculated as the ratio between the size change value and the size before shrinkage.
The air heating method heats the sample with hot air in a closed cavity, figures out the shrinkage rate based on how long it takes for the sample to shrink and how much it changes size, and figures out the heat shrinkage force and cold shrinkage force based on how the sample’s force changes as it is heated and cooled.
In terms of the test range, all three methods can measure how much the film shrinks, but only the air heating method can measure the film’s temperature shrinkage and cold shrinkage. Both the oil bath method and the oven method require a manual measurement of the sample’s size after shrinkage.
The air heating method has the advantage that the equipment automatically measures the change in the sample’s size and force value and can show the measured value as the sample is being heated. Also, the oil bath method involves heating the sample in the heat transfer oil, the oven method involves heating and shrinking the kaolin or stainless steel plate, and the air heating method involves exposing the sample directly to the air without touching anything. This difference in shrinking conditions will affect how the sample shrinks, so the shrinkage rates measured by the three methods cannot be compared.
When testing how well the film shrinks, the right test method should be chosen based on the material, the product standard, the purpose of the test, and other factors. If it is clear in the product standard, the test must be done according to the standard. If the test method isn’t made clear, it can depend on what’s going on.
How to test with a heat shrinkage tester
1) Sample preparation: cut the sample into a 15 mm 130 mm long strip sample. Both ends of the sample are punched with a punch to install the sample on the instrument, and the linear distance between the two holes is 100 mm.
2) Clamp the samples to the fixture of the heat shrinkage tester to ensure that the samples are flat.
3) Once the heat shrinkage temperature is set, the equipment will begin to heat up. When the temperature in the test chamber reaches the set temperature, send the sample to the test chamber.
(4) The shrinkage force and displacement of the sample are measured in real time by the sensor.
5) Record the large shrinkage force and shrinkage rate if the large shrinkage force occurs within 15 30 seconds. Otherwise, adjust the heat shrinkage temperature setting and retest.
6) Following the test, the system will immediately issue the test data. The test report can be printed.
The thermal shrinkage tester can accurately measure the force of shrinkage and the rate of shrinkage of the film when it is heated. This can give a full picture of how the material performs when it is heated and is a good way to check the quality of the film. The heat shrinkable performance tester can also be used to check the shrinkage performance of other materials, as well as the shrinkage performance of heat shrinkable materials used in different industries, such as beverage bottles, heat shrinkable labels, heat shrinkable packaging, and so on.
The Use of a Heat Shrinkable Tester
Detection of heat shrink ability of labels outside beverage bottles
Most of the time, a layer of labels is stuck to the outside of the bottle. Most of the time, the label is self-adhesive or can be shrunk with heat. The first is folded over and stitched through the self-adhesive on the label, which is usually a shrinkable label made mostly of PP. The second type of label is a shrink sleeve label, which uses the shrinking ability of the shrink film label to cut the sleeve label to the right size and then wrap it around the container. The sleeve label is then heated with steam, infrared, or hot air to make it close to the surface of the container. Most of it is made from PET, PVC, and PS.
During thermal shrinkage, if the shrinkage rate is too high or the shrinkage force (which includes both thermal shrinkage force and cold shrinkage force) is too high, it is easy for label consumption to go up. If the label shrinks too much, the printed pattern will be messed up, and in the worst cases, the plastic bottle body will also be messed up. If the rate of shrinkage of the label is low and the shrinkage force is low, the label is easy to put on the bottle. So, keeping an eye on how well heat-shrinkable label film shrinks at the right time is a key way to keep beverage bottles looking nice and cut down on packaging costs.
Detection of thermal shrinkage of the lithium battery diaphragm
Positive and negative electrodes, electrolytes, battery diaphragms, and protective circuit chips are the main parts of a lithium battery. Among them, the battery diaphragm is an important part that helps the lithium battery finish the electrochemical process of charge and discharge. Its main job is to keep the positive and negative poles of the battery from touching and short-circuiting. It also helps electrolyte ions move through the battery. Its performance has a direct effect on how well the lithium battery works as a whole.
Most of the time, high-strength film is used to make the battery diaphragm, and PE or PP is used as the base material. It doesn’t get corroded by organic solvents and is the most important part of making sure that lithium batteries work safely. When the temperature of the battery goes up because it has been used for a long time or because of unusual circumstances, the battery diaphragm should be stable enough to keep the positive and negative electrodes separate.
The lithium battery diaphragm’s thermal shrinkage detector is controlled by a microcomputer, has PID temperature control, a liquid heating medium, temperature control, and even heating. It is used to test how well the battery diaphragm, heat shrinkable tube, back plate, and other materials keep their size and shape at different temperatures. It can measure the force of thermal shrinkage and the amount of shrinkage of a lithium battery diaphragm when it is heated. It can also give a full picture of how well a material handles thermal shrinkage. It gives a good point of reference for checking the quality of battery diaphragm.
Thermal shrinkage test of BOPP smoke film
BOPP film is a great way to package cigarettes because it is bright, shiny, stiff, resistant to moisture, and keeps the smell of the cigarettes. The flatness and beauty of the cigarette are directly affected by the fact that BOPP film shrinks. Most cigarette packs are either soft or hard. For the first, the shrinkage rate and shrinkage force of the cigarette film used for packaging should be low so that the cigarette pack doesn’t get bent or the cigarettes don’t get bent when they come out of the pack because of too much shrinkage. For the latter, the shrinkage rate and shrinkage force of the cigarette film need to be fairly high so that the cigarettes stay flat, uniform, and tightly packed for a long time.
So, the shrinkage test of BOPP smoke film can make sure that the shrinkage performance is suitable and uniform, and it is a very important part of making cigarettes look better. The heat shrinkable instrument can be used to test plastic, polyethylene, ethylene copolymer, and their mixtures that can be shrunk by heat. Testing the shrinkage performance of BOPP smoke film can also be done by figuring out the shrinkage stress.