All About High-Temperature Retort Packaging (3)

How should high-temperature retort packaging deal with the frequent adhesion failure of aluminum foil packaging?

What should be noted when high-temperature retort packaging contains spicy and acidic contents?

In response to these problems that occur frequently in flexible packaging enterprises, on the afternoon of March 23, the Information Committee of the Guangdong Packaging Association, Packaging Frontier, and Beijing Huateng (Guangdong Guowang) jointly held an online technical exchange meeting titled 'Discussion on High-Temperature Retort Lamination Processes for Plastic/Plastic and Aluminum/Plastic Structures.' About 3000-plus group members from the Packaging Frontier Technical QQ main group, Group 1, and three WeChat groups participated online.

Today we continue to share the questions from the online exchange:

1. PET/aluminum foil/CPP, retorted at 121℃ for 40min, filled with fish tofu; the inner CPP in contact with the tofu delaminates from the aluminum foil, and not a single product is free from delamination. How can this be solved?

Beijing Huateng (Chongqing Jute) Lü Minghua:

This is clearly the contents affecting the lamination effect. I suggest trying our UF3026A/UF3026B. Because delamination occurs where there are contents and there is no problem where there are no contents, it must be the influence of the contents.

Beijing Huateng Fan Zhiguo:

Consider the following issues: 1. Whether the CPP is retort-grade; 2. whether the adhesive coating weight is up to standard; 3. the corona value of the raw materials; 4. whether curing is complete.

Taiyangdao Zhu Lixiang: All four points are up to standard; it is probably the effect of red oil.

Beijing Huateng Li Ming:

In addition to the possible problem factors pointed out by Engineer Fan just now, I think it may also be caused by food additives, because customers do not necessarily list ethyl maltol; we encountered such a situation in Wenzhou. Let's check the factors one by one.

Guangdong Guowang Lü Minghua: I think that in addition to ethyl maltol, other food additives may also cause delamination. Previously, one of our hot and sour kelp products had the same situation; there was no ethyl maltol in the ingredient list.

Beijing Huateng Li Ming: Right! Other food additives can also cause it.

Beijing Huateng Fan Zhiguo:

It is also necessary to select raw materials and adhesives specifically targeted at the contents.

1. The structure is PA//CPP, filled with duck eggs, sterilized at 116℃ for 40min; the bags become brittle, all are nonconforming, and they break or snap as soon as they are pulled. Please help look into how to solve this.

Beijing Huateng (Chongqing Jute) Lü Minghua:

This is also a brittleness problem of the material, and it is closely related to material selection.

Zhongcai Printing - Huang:

Yes, choose an inner-layer material with good toughness.

Beijing Huateng Fan Zhiguo:

If bag cost is not taken into account, you might consider trying a three-layer structure.

Beijing Huateng (Zhuhai Furui) Tan Gu:

If the duck eggs are filled but not sterilized, does brittleness occur?

Shandong Zhucheng Dingtai Packaging Zhuang Jinhong:

We are currently troubled by this material; without sterilization, the softness is still acceptable.

Beijing Huateng (Chongqing Jute) Lü Minghua:

Is this bag of yours vacuum-packed?

Shandong Zhucheng Dingtai Packaging Zhuang Jinhong:

Yes, vacuum-packed, filled with salted duck eggs.

Chen Mengjie:

I have encountered this situation before. Please check whether the strength of the related materials is up to standard, then check the additives in the materials. If brittle cracking occurs before the salted duck eggs are filled, the problem lies with the raw materials. Raw materials must be tested for strength when entering the factory.

Beijing Huateng (Chongqing Jute) Lü Minghua:

By 'it breaks as soon as it is pulled after retorting', do you mean tearing the bag open and then pulling from the seal edge?

Shandong Zhucheng Dingtai Packaging Zhuang Jinhong:

The transparent area without ink on the back does not break; the inked area breaks. The cause cannot be found.

Beijing Huateng (Chongqing Jute) Lü Minghua:

Is the outer layer you use NY film?

Chen Mengjie:

I have investigated the rupture; there are many causes.

Beijing Huateng (Chongqing Jute) Lü Minghua:

You did not use the wrong material, did you?

Shandong Zhucheng Dingtai Packaging Zhuang Jinhong:

It is nylon; there can be no mistake.

Foshan Packaging:

Check which side the adhesive layer is on?

Beijing Huateng (Zhuhai Furui) Tan Gu:

The inked side is damaged; is there any delamination?

Beijing Huateng (Chongqing Jute) Lü Minghua:

It may still be necessary to troubleshoot through testing. Let's find another time to continue the discussion.

Everyone has encountered many similar problems in high-temperature retorting. The online discussion on high-temperature retorting can be said to provide everyone with an approach to problem-solving and also introduced many corresponding solutions. Through the wonderful sharing by Mr. Tan, Dr. Xu, and Dr. Feng from Huateng, with explanations combining theory and actual cases, we have gained a deeper understanding of high-temperature retort products. In particular, if you encounter adhesion failure in aluminum foil retort structures or nylon-containing packaging again, everyone will probably know what to do. How to choose the most suitable adhesive for different contents is also very practical experience. I believe that the analysis of many cases from actual production and the introduction of corresponding solutions will provide very good guidance and reference for the production of our flexible packaging enterprises.

The emergence of every problem is closely related to the specific production environment, equipment, materials, process, and operating staff. Therefore, the solutions to some problems still require more in-depth discussion. If anything is unclear, you are welcome to continue communicating with us. Packaging Frontier is willing to build a more practical technical exchange platform for everyone.

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