9 STEPS FOR EASY TRANSITION FROM PVC SHRINK SLEEVE TO PETG SHRINK SLEEVE

Previously in an article, I have discussed pros and cons of PVC and PETG and myths related to them. Now many Indian and Global FMCG manufacturers are shifting or wanting to shift from PVC Shrink Sleeves to PETG Shrink Sleeves for Global compliance as well as environmental reasons.

And this transition always brings out a lot of queries and hesitation before you reach out to find the right vendor, film grade and infrastructure.

If you too are considering making this shift, here are some essential considerations which will make this transition easier for you –

1. Shrinkage Curve Graph of PETG
The most important consideration while making PVC to PETG transition is the Shrink Force. A shrink curve analysis will tell you at what temperature a certain percentage of shrinkage happens for the shrink sleeve.

Remember, the comparison of Shrink Initiation Temperature and the Peak Shrinkage Temperatures of PVC shrink sleeve and PETG shrink sleeve is the main difference between the two shrink films.

Most containers and hot air Shrink tunnels are adjusted to run for PVC sleeves. To make it easier for PETG to run on similar tunnels, the shrinkage curve of PETG must closely resemble that of PVC, primarily in case of hot air tunnels.

2. Hot Air or Steam Tunnel
Steam tunnels are the easiest to convert from PVC to PETG sleeves. Steam provides more uniform heat across the tunnel chamber as compared to a hot air tunnel. For steam tunnel, switch to any grade of PETG can be done immediately.

But again, if you are using PETG for a high shrinkage application, such as the neck of a full-body shrink sleeve for a bottle, it is essential to adjust the steam nozzles on the neck area. Doing so will enable you to achieve better shrink results where a higher shrinkage is required.

3. Shrink Force
Shrink force refers to the force exerted by the shrink film on the walls of the container when the film shrinks in the heat tunnel.

This characteristic is important to understand because the sleeve may try to de-form or de-shape the container upon shrinking.

It is especially true if the container has thin walls, low or no ribs. A low shrink force PETG film is recommended for thin-walled containers to replace PVC sleeve.

4. Ambient Temperature and All-Weather Trials

HDPE and PP containers expand or contract, depending on the temperature. So a sleeve may give different results on such containers based on the weather. Hence, the recommendation is to have trials and machine adjustments in all kinds of extreme weathers.

5. Hot Melt / HAL
A vertical hot-melt strip in PVC sleeve is generally alright. But in PE/PP container with PETG Shrink sleeves, a vertical Hot Melt might create wrinkles, if there is even a minor looseness with the container wall.

In such cases, HAL gives better results when using PETG sleeves on HDPE and PP containers. HAL can be applied anywhere where we are unlikely to observe looseness.

6. Sources of PETG
In general, the availability of PETG is better as compared to CAST PVC. In India itself, you will find multiple PETG manufacturers and many high-quality manufacturers in countries around India such as Thailand, China and Taiwan, etc.

CAST PVC is mostly a generic film available with most manufacturers. Different makes of CAST PVC have mostly common properties and is easily replaceable with each other. However, in the case of PETG, each manufacturer has different grades of PETG sometimes even for the same applications, but the difference among them might be more as compared to PVC vendors.

Hence, if you are going for multiple vendors of PETG shrink sleeves, it is imperative to have proper trials with all grades of PETG manufactures.

7. Container Strength
Keeping in mind the shrink force of the shrink film, the container strength is another important aspect you must look into while converting from PVC to PETG sleeves. And this is especially true in the case of hot air tunnels and a thin-walled container.

8. Stiffness of Film
PETG shrink film is stiffer and harder than PVC. So, it is a must to have proper trials when you are using the material in roll form as the stiffness might hinder the machine’s ability to run correctly.

Also, a higher thickness of PETG film has more stiffness and can create crackling sounds after shrinking, when the bottle squeezes. So, do keep that in mind to avoid problems later on.

Now many of us are shifting from 40 mic to 50/55 mic shrink sleeves due to latest PWM rules. While opting for a higher thickness of PETG, such as 50/55/60 µm, do keep in mind a critical aspect that PETG has higher initiation temperature and is stiffer than PVC. Note that PETG may require a high temperature which might affect the results.

9. BEHAVIOUR OF PETG SHRINK SLEEVES, BASED ON THE CONTAINER
MATERIAL

1. PET Bottles or containers using PVC Sleeves are the easiest to switch to PETG.

2. HDPE containers showcase properties of Thermal Expansion. Simply put, HDPE containers expand when heated and contract when cooled. So when we shrink PVC on an HDPE container, the PVC Sleeve shrinks at low temperature (which is before the container starts to expand.)

When we shrink most grades of PETG sleeves on an HDPE container, the container starts to expand before the PETG sleeve begins to shrink. As a result, the PETG sleeves shrink on the expanded container, primarily due to the difference between Shrink-Initiation temperatures of PVC and PETG.

So when the container cools down to its original size, the PETG sleeve will start showing looseness and wrinkles. It’s why factors like the grade of PETG, shrinkage curve and quality of shrink tunnel are very important.

3. Most thin-walled PP containers behave similarly to HDPE containers, in terms of
their thermal expansion, so similar precautions are necessary.

4. Glass Bottles and Jars generally require a full-body sleeve whenever a higher
shrinkage is desirable.

In such cases, PETG is the ideal choice due to its higher shrinkage percentage compared to PVC. However, do take into account that it can easily shrink with any grade of PETG but a proper shrink tunnel is required for using hot air. Any air trapped in the sleeve  and glass surface will create wrinkle, which is not easy to remove.

5. HIPS are mostly used for Yogurt and Dahi Cups.
Such cups usually have thin walls which can get deformed due to a high shrink force of PETG. You can reduce the temperature to reduce the force of the shrink film on the cup walls, but this may cause uneven shrinkage or wrinkles.

Here, the suggestion is to use low shrink force or medium shrinkage PETG.
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This article is based on the practical and hands-on research we have done while working on numerous client projects – helping them convert their PVC sleeves to PETG sleeves while using their existing Shrink Tunnel infrastructure.

I hope it will help you plan your move from PVC to PETG shrink sleeves. In case you need an expert opinion, feel free to reach out to me by booking a discovery call at www.chetan-jain.com, and I will be happy to assist you.

Written by
Chetan Jain
Author | Packaging and Shrink Sleeve Expert | Entrepreneur

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