How to answer the environmental protection proposition of the film

With the deepening of environmental awareness and the continuous improvement of relevant laws and regulations in the industry, the environmental protection awareness and measures of the printing industry should also advance with the times, and timely adjustments should be made to meet the requirements of green environmental protection printing in order to cope with this profound change.

However, as an important means of finishing after printing, the film coating process is now in a very embarrassing situation. At present, there are many drawbacks in the coating film technology and equipment that China has been using. The pollution problems caused by the coating process are in front of people.

The current problem

Laminating film is a finishing process that uses a thin film to decorate printing products after printing. It has been widely used in the domestic printing and packaging industries for nearly two decades. At present, the vast majority of our country's film-coating technology still adopts the traditional coating film technology that was developed in the 1960s in the world. This technology has a complicated use process and brings great harm to our environment and the body. Several aspects:

First, the technology uses a large amount of organic solvents in the film coating process. As we all know, benzene is an extremely carcinogenic, disabling, and teratogenic substance. Due to the widespread use of a highly toxic coating film process in our country, there are a large number of “dangerous goods” that are obtained through the coating film process in our lives.

Organic solvent coated plastic has many disadvantages, because it uses a binder containing benzene solvent, which has certain harm to the human body, and can easily lead to leukemia and skin allergies, and these diseases have a certain incubation period; There are drawbacks that are flammable, explosive, toxic, harmful to the health of workers, environmental pollution, and fire hazards. Because the use of benzene-containing solvents in the coating process has great harm to the body of production site operators, long-term work in the film-covering workshop is prone to acute benzene poisoning and subacute benzene poisoning.

Second, due to the complicated process of coating technology, glue liquid adjustment, glue coating, and drying are required in production. With the continuous increase of the concentration of the surrounding organic solvents, the static electricity generated by the thin film material can easily become overwhelming. Fire. The three most problem-prone process flows have laid the foundation for pollution, poisoning and fire. The fire accidents caused by the film-covering workshop in China are numerous.

Third, the harmful substances that remain in the product will also have adverse effects on the health of consumers. Benzene and alcohols are highly volatile substances. Most of the volatiles are evaporated during the film coating process and in the short period after the product is formed. However, there are still a small amount of volatiles that remain in the product, along with the storage conditions and storage. The time is prolonged and it slowly volatilizes. The high-speed, high-efficiency production of modern industrial products has led to the rapid transfer of residual substances to consumers. The smell and toxicity of these residual substances have to some extent contaminated the environment in which consumers live and harmed the health of consumers.

Fourth, the coated paper and film materials are difficult to recycle and waste resources. Paper products can be recycled, and the paper products that are coated with film can not be recycled directly by the paper manufacturers, so they need to be manually separated and then processed. A new type of white pollution will result if it is directly disposed of. After the film is coated, it is difficult to recycle and the film material is not degradable, which may easily cause white pollution. The long-term use will also endanger people's health.

It is understood that 80% of China's papermaking fiber is based on the recovery of waste paper, including paper, paper and paper. In the printed matter, the amount of paper on the cover of the book is also huge. If the film is used in large quantities (especially coated material), it is impossible to separate the paper from the plastic film, then the used paper over the film and the edge of the paper Paper and wool will not be recovered and cannot be degraded. This will bring about not a small economic loss. It is actually a waste of resources.

Countermeasures

1. Elimination of coating technology, the use of pre-coating process

Pre-coating technology is currently the domestic advanced film processing technology, is an environmental protection, clean technology, full replacement that is coating film technology is the inevitable trend of the development of post-press coating technology.

The pre-coating technology is to pre-apply hot-melt adhesives to BOPP (biaxially oriented polypropylene film) in a hot melt state at a specialized manufacturing plant. After cooling and solidifying, it becomes a kind of reheat and pressure. A new adhesive coating process that is firmly bonded. Has been used in medicine, food packaging.

The characteristics of the pre-coated film are mainly manifested in the following aspects:

First, pre-coating technology has achieved comprehensive targets for protecting the environment, protecting health, safety in production, and improving production efficiency. During the process of laminating the pre-coating film and the pre-coating film to the printed matter, there is no volatilization of the toxic gas, the working environment is fundamentally improved, and the hidden dangers of the production site and the storage of the product are eliminated.

Second, the pre-coating process greatly simplifies the coating process, improves the quality and efficiency of the coating, and enables high-speed, high-efficiency, and high-quality lamination. No harmful substances remain, the color saturation and sharpness of the printed matter are improved, and its artistic effect is obviously increased. The pre-film dry-type composite process reduces the adjustment of the glue solution, the glue coating, and the drying are the three most likely to occur. The process of the problem, the entire filming process can be completed in a few seconds, to avoid the foaming, stripping and curling problems, also do not need to clean the coating equipment. Eliminates the root causes of pollution, poison, and fire.

Third, because the precoating film has no harmful residual substances, it can be widely used in books, magazines, food, tobacco, alcohol, medicines and other packaging, and will not pose a potential threat to consumers.

2. Develop new materials, improve material recycling and environmental protection.

The ever-increasing print quality standards and market demands require the film-covering industry to make structural adjustments based on changes in objective conditions and new quality and technical standards. At the same time, we should also look for other processes that can replace the film in a timely manner to reduce the pressure on the environment caused by the film contamination.

According to the technical requirements for adhesive products proposed by the Science and Technology Standards Division of the State Environmental Protection Administration, the mandatory requirements for water-based adhesives for packaging are clearly mentioned as follows:

1) No toxic organic solvents such as benzene, toluene, xylene, and halogenated hydrocarbons should be added to the adhesive.

2) The total content of benzene, toluene, and xylene in the adhesive must be less than 1000mg/kg, and the content of benzene must be less than 100mg/kg.

3) The amount of halohydrocarbon (calculated as dichloroethane) in the adhesive must be less than 1000 mg/kg.

Therefore, strict selection of raw materials should be conducted in accordance with national standards.

In addition, printers can consider the use of safe, non-toxic, stable film adhesives, and adhesives with higher bond strengths, such as non-volatile components of Nubond Instant adhesives, are considered harmless. , without any isocyanate, is a one-component solvent-based adhesive that does not require the addition of a curing agent.

Environmentally-friendly XS-109 water-based coating adhesive has a strong cover and adhesion effect on the surface of the printed product, and it is non-toxic and odorless. It is more suitable for the coating of food paper containers. Water-based wet coating is favored by the market for its high brightness, high grade, easy recycling, and no pollution. Environmentally-friendly XS-101 coated rubber is made of high-grade, new materials. The solvent does not contain triphenyl. It is suitable for the carton of environmental protection and the pre-printed face paper. It has high transparency and brightness.

3. Standard process operation

In the film laminating workshop, especially in the application of the gluing process to compound production, whether it is a paper/plastic compound or a plastic/plastic compound, BOPP film coating glue occurred in different seasons, and the glue disk instantly caught fire. accident.

In fact, a variety of ready-to-glue compounding processes are prone to fire where glue is placed on top of the glue plate of the gluing mechanism. This is precisely where the BOPP film feeding mechanism is concentrated. The BOPP film in the compounding process is accumulated during the stretching and slitting process. Electrostatic discharge, which is bound to form electrostatic discharges due to peeling of the film during compounding or printing, and the application of a compounding machine roller, a printing machine's embossing roller, a plate roller's heavy pressure friction, and instantaneous contact and separation. The solvent that is used to dilute the adhesive is classified as a flammable liquid. This causes the vapor that is vaporized by the solvent above the adhesive disk to form a flammable liquid mixture with air and cause instant burning.

Therefore, to eliminate the fire disaster in load production, it is necessary to regulate the production operation. The following is a brief introduction of the operating specifications of several fire-retardant workshops:

1) The film-covered machinery should have a good grounding device. It is better to use a ring grounding net. Adhesives and thinners should be handled lightly and gently to prevent collisions of metal devices such as drums. Self-sensing static eliminators can also be installed on mechanical equipment.

2) Watering the ground and using a humidifier artificially increase the humidity in the production environment, especially in the vicinity of the laminating machine, and can reduce the static electricity of the BOPP film. When the relative humidity is above 75%, it can effectively prevent the accumulation and sudden burst of static electricity. freed.

3) Good ventilation device, which can reduce the volatile concentration of flammable liquids.

4) In the production workshop, storage of adhesives and thinners should do the following work, prohibit smoking and carry fire sources such as lighters to enter, can not use open flame, prohibiting operators to wear chemical fiber clothing does not meet the requirements of anti-static clothing and iron Nailed shoes.

summary

With the renewal and development of environmental protection awareness, health awareness, and management concept, new scientific and technological achievements will surely eliminate the products of the old technology, resulting in a qualitative change in the coating process. “Non-toxic, harmless, and green” is the cover film. Inevitably, the development trend of technology, Chinese companies should take early action, actively, steadily and responsibly deal with the proposition of environmental protection.

(tension)

Reprinted from: Print Quality and Standardization