Why does PVC heat shrink film wrinkle when exposed to heat

The width of the hot melt adhesive film made by different processes has different manufacturing processes, so the width of the hot melt adhesive film is also limited according to the different processes. Generally, the hot melt adhesive film made by the blown film process can be made in a wide range, with a width of up to 3260mm. For the hot-melt adhesive film made by laminating and scraping process, the width range is much less, and the general width is about 1600mm.

This is because the squeegee coating and laminating processes are completed on the basis of the release liner substrate, which is greatly affected by the width of the substrate and the width of the equipment, which is why the hot melt adhesive film without release liner can be made wider, while the release liner can be made with a smaller wide range. Although the common width of different types of hot melt adhesive film can be customized, there are certain requirements for the minimum order quantity....

The shrinkage of PVC heat shrinkable film after heating is a physical phenomenon, which needs to be explained by certain physical knowledge, simply put, the thermal movement of molecules makes the PVC heat shrinkable film shrink phenomenon.

The macromolecules of ordinary plastic film are in a state of natural curl, and generally do not shrink when heated. The situation of PVC heat shrinkable film is different, the film formation goes through two steps, after the raw material is melted, the film is stretched at a specified temperature and under the action of external force, and the macromolecules cannot slip with each other, and the unnatural state is frozen.

When the PVC shrinkable film is reheated to a certain temperature, the frozen macromolecules will start to move again, trying to return to their natural state from the unnatural state, and the result is shrinkage.

Because the full name of PVC is polyvinylchlorid, the main ingredient is polyvinyl chloride, and the synthetic material expands and contracts coldly.

Temperature and time are important, but they will be wrinkled to a certain extent, and they have to do with the shape of the packaged product, and the regular ones are better.

After the PVC film is preheated, it is stretched, cooled and shaped (as long as it is not heat-set) to obtain a heat shrinkable film. Under TF close to PVC resin, the resin casting sheet is stretched horizontally and longitudinally, and then quenched, so that the resin molecular chain is frozen in the oriented state, forming a heat shrinkable film. The thermodynamic state of the shrinkable film is unstable, when the shrinkable film is heat-treated, the molecular chains that have been oriented will quickly return to the random clump (curled state), and the film will shrink.

However, the effect of the longitudinal shrinkage rate and the transverse shrinkage rate of the film is not the same, the longitudinal shrinkage rate is too large, and it is easy to wrinkle the PVC film.

It's a bit of membrane preheating, but the degree is different.

When the temperature difference is large, the PVC molecule will shrink rapidly and wrinkle, such as the surface of the heat shrinkable film will be wrinkled when the temperature of the greenhouse is high in winter. Of course, if you increase the stiffness of the film, this temperature difference wrinkle will be alleviated.

Hello dear and thank you for your patience. PVC heat shrinkable film will be deformed or shrunk in summer due to the high heat environment, and there are mainly the following ways to deal with the laque sedan chair: storage environment:

PVC heat shrinkable film should be stored indoors, in a cool, dry, ventilated environment, away from direct sunlight. Conditions of use: When in use, avoid use in high-temperature environments, or minimize exposure to high-temperature environments under non-essential conditions.

Physical protection: If you have to use it in a high temperature environment, you can choose to add a protective layer on the outside, such as cloth or other shields, to reduce the heat caused by direct sunlight. Replacement Material:

If none of the above methods can be implemented or the effect is not good, it is recommended to replace it with a shrink film material that is more resistant to high temperatures, such as polyester wheel (PET) heat shrink film.

The main body is polyvinyl chloride resin, and some additives must be added to the production of PVC, such as stabilizers, lubricants, impact modifiers and plasticizers.

Heat shrinkable film: Heat shrinkable film, which shrinks when exposed to heat, so that it is tightly wrapped on the product.

Material: The materials used are mainly various thermoplastic films. Initially, PVC shrinkable film was the mainstay, but with the continuous development of market demand, PVC shrinkable film gradually decreased, while various PE, PP, PET, OPP, PVDC, POF and other multi-layer co-extrusion heat shrinkable films developed rapidly and became the mainstream of the market.

It's polyvinyl chloride (PVC), of course, some of the flame retardants added to it and the like, depending on the use, the things added are different, but the resin is polyvinyl chloride.

Summary. Kiss! Hello, a blessing, a warmth, a touch.

Have a grateful heart. Life is full of touching! Your question has been received, it will take a little time to type, please wait a moment, please do not end the consultation.

You can also take this time to provide more effective information so that I can better answer for you. I hope mine can solve your problem, and I will sort out the answer for you right away, please wait a moment.

Kiss! Hello, a blessing, a pants to close the warmth, a hu cracked touched. Have a grateful heart.

Life is full of touching! Your question has been received, it will take a little time to type, please wait a moment, please do not end the consultation. You can also take this time to provide more effective information so that I can better answer for you.

I hope I can solve your problem, and I will sort out the answer for you immediately, please wait a moment.

Hello. How to solve the problem of PVC film shrinkage Heat shrinkable film common problem 1 Highlight The shrink film is in the corner of the package to form a prominent triangle Solution: 2

The shrink bag of the wrapping package is too large, so the number of rents and the size of the shrink bag can be made a little smaller3The speed of the conveyor belt of the shrink wrapper is too fast, and the speed of the conveyor belt can be turned down, and the heat shrink film often sees the problem 2 Zipper-shaped holes There are zipper-like intermittent holes on the surface of the shrink film Solution.

Common problems and solutions for the use of PVC heat shrinkable film.

In the process of shrink wrapping, PVC heat shrinkable film often encounters some problems, such as flatulence, atomization, fisheye and other problems of shrink film. The most commonly adjusted packaging machine temperature, circulating air speed, conveyor belt speed, the number of air vents and the size of the shrink film PVC shrink film packaging use problem 1: flatulence hot air retained in the shrink film solution:

1. Increase the number of breathable blue holes to speed up the leakage of air from the shrink film 2. Slow down the conveyor belt speed of the packaging machine, so that the hot air has a longer time to leak out of the shrink film 3. Raise the temperature of the packaging machine to help the air leak out of the shrink film PVC shrink film packaging Use problem 2: The surface of the atomized shrink film becomes blurry, like a mist.

Solution: 1. Adjust the temperature of the charter defense slip loader, the temperature is too high is the cause of the atomization of the shrink film 2. Increase the conveyor belt speed of the packaging machine to reduce the time for the shrink film to contact the heat of the PVC shrink film packaging Problem 3: Fisheye wrinkles on the surface of the fisheye shrink film Solution:

1. The temperature of the shrink packaging machine is too low, and the temperature of the packaging machine can be adjusted up next to the stove 2. The speed of the conveyor belt of the shrink packaging machine is too fast, and the speed of the conveyor belt can be lowered 3. The circulating wind of the shrink packaging machine is too low, and the circulating wind can be lowered.

Do you have any other questions? I can go on and on for you 3I hope this service can help you, you can click on my avatar to follow me, and if you have any questions in the future, you can consult me again, and look forward to serving you again.

You; Have a good life and all the best! 4.If you are satisfied with my service, please give Liang a praise for pure luck, and I wish you all the best!

Peace and joy.

PVC shrink film advantages:

1. Wrap and package the goods stacked on the pallet to make the packaging more stable and tidy, and more waterproof;

2. It has the characteristics of high tensile strength, large elongation, good self-adhesive and high transparency;

3. Shrinkable film, heat shrinkable film is mainly made of several different grades of polyolene resin mixed extrusion, with puncture resistance, super strength and high performance;

PVC heat shrinkable film is insufficient:

For example, some PVC shrinkable films are soft when used in summer and harden in winter; Some shrinkable films tend to absorb dust and become opaque; There are also some PVC heat shrinkable films that do not have a long service life, are easy to age, cannot withstand the attack of wind and frost and sun exposure, and the surface is easy to crack.

According to the cause of the bubble, the countermeasures to solve it are as follows:

1) When the wall thickness of the product is large, the cooling rate of the outer surface is faster than that of the center, so as the cooling progresses, the resin in the center expands to the surface while shrinking, so that the center part is underfilled. This condition is known as a vacuum bubble. The main solutions are:

a) According to the wall thickness, determine the reasonable gate and sprue size. Generally, the gate height should be 50 60 of the wall thickness of the product.

b) Until the gate is sealed, a certain amount of supplementary injection is left.

c) The injection time should be slightly longer than the gate sealing time.

d) Reduce the injection speed and increase the injection pressure, and e) use materials with high melt viscosity grades.

2) The bubbles caused by the generation of volatile gases are mainly solved by the following methods:

a) Pre-drying is carried out thoroughly.

b) Reduce the temperature of the resin to avoid the generation of decomposition gases.

3) Air bubbles caused by poor fluidity can be solved by increasing the temperature of the resin and mold and increasing the injection speed.

There are just a few reasons.

See for yourself!

Let's see how we solve it!

This phenomenon is mainly related to the hot air effect of the heating tunnel of all your shrink furnaces, and of course it can be improved by specific operation methods, and the quality of the PVC film is also very important.

No punching... How can you run away!