In China's huge aluminium composite panel market, there are more and more domestic brands. The quality of domestic brands has been able to compete with international brands. They have occupied an absolute majority in the market. And they have had a professional association, which forms a unified national standard to ensure the quality of aluminum composite panels. However, the small protective film has not yet attracted enough attention from most manufacturers (except for several famous brands). It is not regarded as a “key” product, and often a small film causes a major economic loss for manufacturers and damage their brand image.

    “Protective film” is an abbreviation used by the aluminum composite panel industry. It is a layer of plastic film attached to the surface of aluminum composite panel. The purpose is to protect the produced aluminum composite panel from being damaged during a series of processes, such as handling, inventory, transportation, processing and installation. Generally speaking, after the installation of the aluminum composite panel is completed, it is torn off by the installation engineering team, so that the surface of the aluminum composite panel is as clean as new and plays a decorative effect.

    In fact, the full name of the protective film is temporary self-adhesive film that protects the surface of industrial products.
    As the name implies: the protective film should have the following characteristics:

1. It is a plastic film.
2. It has self-adhesiveness
3. It provides temporary protection
4. It is used on the surface of industrial products.

    It should be emphasized that the average person tends to confuse the protective film with the packaging film. The author believes that the most fundamental difference between the protective film and the packaging film is that the protective film is not only attached after the product is finished to protect the product during handling and transportation. The more importantly, it is often used in the production process, involved in the production process of the product (such as cutting, hemming, drilling, stamping and etc.).

    In the aluminum composite panel industry, the protective film participates in the production process as follows: First, it is used before the aluminum composite panel is cut. Protect the aluminum composite panel from being damaged when it is cut. The second is to participate in the entire process of processing and installation of the final customer (decoration and construction engineering company) to ensure that the product has no scratch and no damage.

Classification of protective film
    1, classified by the base material, protective film can be roughly divided into:

• PE (polyethylene) protective film
• PVC (polyvinyl chloride) protective film

    In addition, depending on the thickness of the base material, it can be from 0.025 um (25 microns) to 0.12 um (120 microns), or even thicker.
    Subdivided by the color of the base material, there are colorless transparent film, transparent blue film, white film, black and white film, and etc.

    2, classified by the nature of adhesive, protective film can be divided into:

• Water based type (usually made of acrylic)
• Solvent based type

      The solvent based type can be further subdivided into:

• Solvent type based on natural rubber
• Solvent type based on acrylic

    At present, the domestic protective film used in the aluminum composite panel market is mainly a solvent-based acrylic protective film, and the imported protective film used on the aluminum composite panel is mainly the rubber-type solvent-based protective film.
In addition, due to the difference in the properties of the protected products (stainless steel, color steel, plastic, paint), and the difference in brightness and surface structure of the protected product, protective film can be subdivided into countless kinds.
According to the characteristics of use, there are protective film for ultraviolet protection for outdoor use, protective film for laser cutting, protective film for heat resistance, easy peeling protective film, and etc.

Application of protective film 
    Protective film is mainly used on the surface of industrial products, and its main industrial fields are:

1. stainless steel product surface: decorative stainless steel plate, stainless steel utensils, stainless steel profiles and etc.
2. pre-coated panel product surface: pre-coated color steel plate (for household appliances, construction sandwich panels, profiled panels and etc.), aluminum composite panels, honeycomb panels and etc.
3. post-coated products: aluminum veneer, post-painted color steel plate and etc.
4. sticking steel plate
5. aluminum plate, aluminum foil, aluminum profiles and etc.
6. plastic panel: PC veneer, PC sandwich panel, PMMA board (including extrusion and casting), PVC board, PE board, PS board and etc.
7. PVC profiles
8. fire prevention board
9. also widely used on other products in the automotive industry, the electronics industry and the textile industry (such as carpets).

Application of protective film on aluminum composite panel and its problems
    Among the above-mentioned areas of protective film applications, aluminum composite panels are one of the most important markets for the use of protective films in China.
    According to the author's shallow understanding of the Chinese aluminum composite panel market, the total volume of this market is about 30 million m2 (excluding imported aluminum composite panels). So famous brands use imported protective film while most of them use domestic protective film.

1, Aluminum composite panels can be divided into exterior wall panels and interior wall panels according to their use.
Since the exterior wall panel is exposed to ultraviolet rays after installation, it is easy to cause glue residue on the panel. And it is very difficult to wipe the glue residue. Even if it is wiped off, the aluminum composite panel surface is obviously off color. Therefore, it is necessary to use a black and white protective film with a good anti-ultraviolet effect.
As for the interior wall panel, a transparent film is generally used. However, in China's aluminum composite panel market, it is difficult for most customers to distinguish exterior and interior wall panels. In order to save costs, many end-users also use interior wall panels for the decoration of exterior wall. So in order to ensure the quality, many manufacturers use anti-ultraviolet black and white protective film on the interior wall panels.
What needs to be mentioned is that the black and white protective film produced by some manufacturers are with poor quality. Under the light, the black and white film still has light transmission, which does not have the effect of resisting the ultraviolet rays and the premature aging of protective film under outdoor sunlight conditions. When removing the film, it can not be peeled in one piece or it is torn into pieces, which brings difficulties to the builder.

2, aluminum composite panel can be divided into two categories of polyester paint and fluorocarbon paint according to the material of paint coating, each of which can be roughly divided into metal paint surface and non-metal paint surface. Due to the difference in the material and structure of the paint, different requirements are imposed on the thickness and viscosity of the protective film glue.
In the process of use, if the adhesive viscosity of the protective film is not good or the viscosity of the glue is unstable, it will bring many problems to the user: it may not stick to product, it may curl, or it can not be peeled off during the shelf life after application.

3, in order to establish a brand image, a major feature of China's aluminum composite panel market is that most manufacturers use protective film printed with the trademark of the factory, and some even have a few to a dozen brands.

The main problems caused due to the quality of printing:

1. The ink is transferred to the aluminum composite panel. Due to technical difficulties, some protective film manufacturers use a transparent film for laminating after printing, which affects the integrity and other physical properties of protective film, so that it is easy to cause a phenomenon such as curling.
2. Shortly after use, the transparent film on protective film surface ages and ruptures
3. In the sun, the printed words are reflected on the protected product surface, and corresponding shadows are produced on the product surface.

    In summary, the protective film accounts for a small proportion of the value in the aluminum composite panel industry. It is only an excipient used by the manufacturer. However, if it is used improperly or if a protective film that does not meet the requirements is used, the hazard is not only no protection. On the contrary, it may damage the surface quality of the product, causing tangible material loss and intangible brand image loss to the user, which ultimately affects the price and sales of the product. More and more manufacturers, especially the main business leaders are paying more and more attention to this issue.

    In order to further improve the quality of the protective film used in the production of aluminum composite composite panels, the author suggests that it is necessary to formulate uniform technical indicators and quality inspection standards for protective films in the industry. For example, how to measure the thickness of the protective film, the allowable range of thickness error, how to measure the viscosity of the protective film, how to measure the tearing property of the protective film, how to measure the stretchability of the protective film (horizontal and vertical), how to test the deployment force of protective film, how to test the peeling force of the protective film, and etc.

    It is necessary to emphasize that the history of protective film production in China is relatively short, only a short period of more than 10 years. However, great progress has been made, and quality and service are constantly improving, and a number of key enterprises with certain production scale and technical strength have emerged.

    Wuxi Isaac Industry Co., Ltd. is the main manufacturer of protective film in the world. In addition to providing protective film for the internationally renowned aluminum composite panel brand, it has provided protective film and after-sales service for domestic famous aluminum composite panel manufacturers for more than 10 years. We are willing to work with other domestic protective film manufacturers to continuously improve product quality, improve customer pre-sales and after-sales service, continuously reduce production costs, improve price competitiveness, and make more effort to further improve the overall quality level of the domestic aluminum composite panel industry.