A Complete Guide to Shrink Wrapping

Shrink wrap is used for the sale and transportation of various products, and its main function is to stabilize, cover and protect the product as a flexible protective packaging material. This blog post will show you all you need to know about shrink wrapping (specifically PE shrink wrapping) so you can understand it thoroughly.

1. What is shrink wrap?

Shrink film (equivalent to shrink film) is the most common shrink material and is made of two or three layers of material. The first layer is the sealing layer on the outside of the package, while the second layer is the sealing layer, which can  better prevent moisture, insects, etc.

heat shrink wrapping

Shrink packaging has high puncture resistance, excellent shrinkage force, sufficient thermal energy, and certain shrinkage stress. The shrink film cannot create holes during the shrinking process. Since shrink wrap is usually used outdoors, it requires the addition of anti-ultraviolet agents.

1) Different Types of Shrink Films

PE shrink film, PVC shrink film, PET shrink film, POF shrink film, OPS shrink film.

2) Polyethylene Shrink Wrap

Different types of PE materials

There are three types of polyethylene commonly used, namely: LDPE (low density polyethylene), HDPE (high density polyethylene) and LLDPE (linear low density polyethylene).

In the process of synthesizing this polyethylene, the process conditions used are different, so to produce three different varieties of polyethylene, the properties of the three materials are very different.

3) Features and Benefits of PE Shrink Packaging

1) standardization

With the superior winding force and shrink ratio of the film, the product is tightly and securely bundled into a single unit, making small pieces a single unit.

The product does not loosen and separate, even under unfavorable conditions, without sharp edges and sticking to avoid damage.

2) main protection

Primary protection provides surface protection for the product, forming a very light protective shell around the product, thus providing protection against dust, oil, moisture, water and theft.

3) Compression and fixation

Due to the low shrinkage force, the product is packaged into a compact unit that does not take up much space. Product trays are tightly packed together. Effectively prevent product dislocation and movement during transportation.

4) Saving cost

The cost of using PE shrink film packaging is only 15% of the original carton packaging and 50% of the carton packaging. At the same time, it can reduce the waste and labor intensity of workers, and improve the packaging efficiency.

4) Polyethylene Packaging Applications

PE shrink packaging is extremely durable and is widely used in the packaging of wine, cans, mineral water, various beverages, fabrics and other products. The product has the characteristics of flexibility, impact resistance, tear resistance, not easy to break, not afraid of moisture, and large shrinkage rate.

2. PVC shrink wrap

The top layer of the PVC shrink wrap is paint, the main component in the middle is polyvinyl chloride, and the bottom layer is back glue. It is one of the most popular and widely used synthetic materials today. Among the materials that can be used to make three-dimensional surface films, PVC is the most suitable material.

1) Features of PVC Shrink Film

PVC shrink packaging has the characteristics of waterproof, flame retardant, low cost and high yield.

2) PVC Shrink Packaging Application

It is not environmentally friendly and is widely used in industrial packaging.

Not suitable for food packaging.

3. PET shrink wrap

PET shrink film is a new type of shrink packaging material. It is easy to recycle, non-toxic, odorless, and has good mechanical properties, especially in line with environmental protection. In developed countries, polyester has become an ideal substitute for PVC heat shrinkable film.

1) The characteristics of PET shrink packaging

  • Transparent, reflecting the image of the product.
  • The packaging is tight and the anti-dispersion performance is good.
  • Rain, moisture and mildew proof.
  • Non-elastic, with a certain anti-counterfeiting function.

2) PET shrink packaging applications

PET packaging is commonly used in convenience food, beverage markets, electronic appliances, and metal products, especially shrink labels are its main application areas.

Because with the rapid development of PET beverage bottles, beverage bottles such as Coke, Sprite, and various juices all require PET heat shrinkable film to be used as heat seal labels. They are all polyester, which are environmentally friendly materials and are easy to recycle and reuse. .

4. POF shrink wrap

POF shrink film has the characteristics of high surface gloss, good toughness, strong tear strength, good thermal shrinkage uniformity, suitable for automatic high-speed packaging, etc. It is an alternative to PVC products.

POF full name is multi-layer co-extruded polyolefin heat shrinkable film, which is the middle layer of linear low density polyethylene (LLDPE), copolymerized polypropylene (pp) for the inner and outer layers, plasticized by three, by three extruded It is extruded out of the machine and then subjected to special processing processes such as die forging and film foam blowing.

1) Features and Benefits of POF Shrink Film

  • High transparency, good gloss, can clearly display the appearance of the product.
  • The shrinkage rate is large, up to 75%, and the elasticity is good, and it can pack irregular-shaped items.
  • Good welding and sealing performance, high strength, suitable for manual, semi-automatic, high-speed automatic packaging.
  • Excellent cold resistance, can maintain elasticity at -50 ℃ without brittleness, suitable for storage and transportation of packaged goods in cold environment.
  • Environmentally friendly and non-toxic, in line with FDA and USDA standards, it can be used as a food packaging material.

2) POF shrink packaging applications

Widely used in automotive products, plastic products, stationery, books, electronics, circuit boards, MP3, VCD, handicrafts, photo frames and other wood products, toys, pesticides, daily necessities, food, cosmetics, canned beverages, dairy products, pharmaceuticals, Products such as cassette tapes and video tapes.

5. OPS shrink wrap

OPS (Oriented Polystyrene) shrink film is a new type of packaging material that meets environmental protection requirements.

1) Features of OPS Shrink Packaging

  • Its transverse shrinkage rate is about 74%, and it is not easy to wrinkle during the shrinkage process.
  • It has almost no crystallization point.
  • It has a lighter specific gravity.
  • The specific gravity is only 1.05. For OPS, PVC and PET materials of the same thickness and area, OPS can reduce the weight by 25%.
  • The tear line made after shrinking the OPS label is very uniform and easy to tear without destroying the overall effect of the label.

2) OPS shrink wrap application

It is widely used in the fully enclosed heat shrinkable packaging of medicine, food, beverage, stationery, ceramics, daily chemicals, auto parts, needlework, electronic audio, film and television and other products.

3) Disadvantages of shrink wrap

  • The heating time should not be too long, otherwise decomposition and burning will occur.
  • Should not come into contact with organic solvents to prevent breakage.
  • When soft plastic has shallow side grooves, it can be forcibly pressed off the mold.
  • The shrinkage range and shrinkage value are large, the directionality is obvious, the deformation is easy, the cooling speed should be slow, and the mold is provided with a cold cavity and a cooling system.

6. How to use shrink wrap?

shrink tunnel

  • Set the heating time of the shrink tunnel machine
  • After pressing the manual or automatic button, the solenoid valve of the rack cylinder is energized to push the gear, the gear drives the chain, and the proximity switch behind the rack cylinder is disconnected.When the rack oil cylinder runs to the upper gear, the proximity switch in front of the rack oil cylinder is turned on, and the solenoid valve of the oven oil cylinder is output.
  • When the oven cylinder runs to the top dead center, the timer starts to delay, and the solenoid valve of the rack cylinder is de-energized.
  • When the timer expires, the oven cylinder solenoid valve opens.
  • According to the position of the work mode flag, decide whether to continue the next work flow.

by heat gun

  • Wrap the item with shrink film, and then blow hot air on the item with a heat gun. The shrink film has shrinkage properties.
  • After natural shrinkage, it can be closely attached to the surface of the article to achieve the effect of waterproof protection of the package.
  • Blow the hot air evenly, do not always blow to a certain place, to prevent the heat shrinkable film from being scalded. In addition, if the heat shrinkable film does not need to be sealed, you can blow the non-sealed side first, then blow other parts, and try to place the sealing line at the bottom or in an inconspicuous position

7. Where can I buy PE shrink wrap?

For small quantities of 1 or 2 pallets, please buy from your local distributor. For bulk container quantities you can consider to buy it from China, there are many supplier on alibaba.

8. How much does shrink wrap cost?

According to different purchase amount, usd2.40 ~$3.20/kg.

9. What is the standard thickness of shrink wrap?

30μm ~ 200μm.

10. What is the standard width for shrink wrap?

Shrink wrap is a tube wrap with a bifurcated edge structure. Hemming width: 1020mm~1490mm (40 inch~59 inch), fork width: 460mm~595mm (18 inch~23 inch), circumference: 3880mm~5360mm (153 inch~211 inch).

11. What is the standard length of shrink wrap per roll?

1000 mm (39 inches).

12. How many types of shrink wrap are there?

Various forms: fork edge tube, ink cartridge film, L-shaped folded film, single film can also be processed into ink cartridge bag, flat bag, trapezoidal bag.

13. What is the difference between cling film and shrink film?

Cling film is also called stretch film. It is the earliest winding film with PVC as the base material and DOA as the plasticizer. Shrink film is a shrink material made of polyethylene (LDPE, HDPE, LLDPE).

14. What are the benefits of shrink wrapping?

It is an inexpensive industrial shrink wrapping material. It is suitable for bundling of multiple items, product packaging, warehousing, production care, machine packaging, and is mainly used in the manufacturing and construction fields.

15. Can shrink wrap stick to itself?

It is self-adhesive by heating, which is better than stretched film. Shrink wrap is a package that basically protects goods in a stretched state.

16. The problem and solution of the shrinkage film not shrinking tightly

1)Low temperature

Shrinkers work on the principle that the speed matches the temperature. When the temperature is low, the surface of the product will wrinkle, and when the temperature is high, the film will be scalded. The operating temperature of POF film is about 150 degrees, and the operating temperature of PE film is about 170 degrees.

2) Inappropriate size of furnace

The furnace channel is too large to cause heat dissipation, and it is necessary to increase the temperature of the packaging machine to a very high level. If the furnace tunnel is too small, the membrane will stick to the inner wall of the furnace tunnel, causing the membrane to be burned out.

3) no holes

When the product needs to be completely wrapped, some small holes must be pierced in the surface of the shrink film. Otherwise, the gas will concentrate in the film and expand.

4) speed mismatch

The user shrinks different products, the length of the furnace passage is different, the temperature of the furnace is different, and the required conveying speed is also different.

The longer the furnace tunnel, the higher the temperature and the faster the speed, which needs to be set by customers according to their own needs.

5) Poor quality or inappropriate width

The shrink film applied to the shrink machine needs to meet certain requirements. If the quality of the shrink film is too poor, the shrink effect will either wrinkle or be supported.
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