The assortment of jelly products does add beauty and vitality to large and small shops and supermarkets, but it should pay more attention to the packaging of jelly on the market. There are many problems with packaging quality, such as:
1 sealing leakage is more serious;
2 Some products are difficult to peel off, but in spite of this, there are leaks in the seal.
3 The liquid jelly is too full. When it is peeled off, it spills onto hands or clothes.
4 cover film is not smooth visual effect;
5 Delamination occurs when peeling off.
The production of these problems is not so much a case of packaging companies shoddy and crude, but it is better because of the lack of research and development efforts to bring them helplessness.
Taking 70g full filling and 180g filling with two kinds of jellies as examples, the cover structure is PET printing/VM-PET/PE/modified EVA. Trial result:
(1) Since the improved EVA can provide excellent peelability, the heat seal strength of the cover film and the cup material is 1 N/mm.
(2) The film delamination mainly depends on the peel strength, and the advanced plasma treatment technology is adopted in the aluminum plating process, so it can ensure the aluminum-plating barrier property and adequate aluminum layer adhesion; when the 0D value is 2.5, it can also maintain PET/VMPET peel strength ≥0.1N/mm; PET/PE composite strength >0.4N/mm.
(3) Good flatness before sterilization and deterioration after sterilization mainly due to the fact that the differential film has high tensile strength and a small elongation, the cup expands at the sterilization temperature, and retracts after cooling, whereas the two-layer PET expands and contracts. The rate is small, so for 70g full-fill packaging, after sterilization, the flatness is slightly reduced, the customer can still accept, but for 180g large packaging, and due to inadequate filling, the package contains 5% gas, thermal expansion and contraction is particularly evident Therefore, the flatness of the film cover is greatly affected and the customer cannot accept it.
(4) For the most important index: no leakage rate, 70g full filling package, the material can meet the requirements (customer requirements ≥ 99.6%) However, for 180g dissatisfied with the filling package, the indicator deviated larger (customer requirements for ≥ 99.1%) The main reason is judged as follows: (a) The extension rate of the cover material is not enough, and it is not possible to buffer the horizontal destructive force of the unsufficiently filled cup body against the seal u. (b) The sealing material strength of the sealing material is not sufficient to withstand the longitudinal damage of the seal to the cup.
If PET/PE is replaced with a single layer to improve the performance of the cover material extension (of course, the permeability and oxygen permeability indicators have been tested and verified). Development of sealing materials, consider the three options of the plant:
(1) using 40% LDPE mixed 60% metallocene;
(2) 50% metallocene mixed with 50% modified E-VA/50% LDPE mixed 50% metallocene;
(3) 50% LDPE mixed with 50% metallocene/50% metallocene mixed with 50% modified EVA.
The heat-sealability is considered in the first plan, and the adhesiveness, heat-sealability, and peelability are taken into account in the second plan. The second plan considers the heat sealability, adhesion, and peelability of the plant. It differs from the plan two only in the order of layers.
Through the dynamic microscopic analysis of the sealed cup and lid section, it can be seen that the sealing layer and the heat seal layer play different roles under certain pressure and temperature, and the adhesion layer is under certain temperature and pressure. Formed in the inner edge of the cup door, the real heat seal layer is on the upper layer. This is the real intention of scheme 2, if only static analysis, scheme 3 is closer to the general thinking. The final conclusion is as follows:
(1) Dissatisfaction with filling large packages, seal strength requirements higher than ordinary jelly (2# sample and PP cup heat seal strength of 19N/15mm).
(2) The leak-free rate can be significantly controlled by the combined structure of the adhesive layer and the heat-seal layer. Of course, the control of the layer thickness and the sequence is very important.
(3) The temperature of the l # sample enclosure is difficult to peel off and easy to leak. Due to the high temperature of sealing, the flatness is not as good as that of 2# and 3#. Some manufacturers use pure metallocene to replace the easily peelable sealing resin. The site of the project needs careful consideration.
(4) All indexes of sample 2# have met customer requirements and can completely replace imports.
(5) According to the structure of the second plan to make appropriate changes can also meet the customer's other requirements, the connection can be dry compound, squeeze mountain compound, co-extruded cast and other ways.
Only after repeated trials, trials, and approvals, can packaging new product development be able to truly grasp the needs of customers, fully verify design solutions, and effectively control the production process.