Explanation of BOPP functional additive masterbatch

The main material used in the BOPP film is homopolymer polypropylene, a special material for BOPP film grade, with an isotacticity of about 97% and a melt index of about 2.0g/10min. The polypropylene used in China's BOPP film production in the early days was mainly imported. At present, China's domestic petrochemical plants basically produce it themselves. For example, Shanghai Petrochemical, Yanshan Petrochemical, Maoming Petrochemical, etc.It can produce special materials for BOPP film polypropylene, and the product performance is stable and can meet the needs of production line and market requirements.

When producing heat-sealable films, in addition to polypropylene, heat-sealing materials are also required. The heat sealing material is generally an ethylene-propylene binary copolymer or an ethylene-propylene-butylene terpolymer. The heat sealing material is only added to the surface of the film. The films can be bonded to each other through a sealing machine at a higher temperature. This is referred to as Heat sealability. The sealing onset temperature of terpolymer is lower than that of binary copolymer, so the heat sealing temperature range is wider. At present, most of the heat sealing materials used in my country's BOPP film industry are imported, and some use domestic materials.

Functional additives for BOPP membranes

The BOPP film production line has a high degree of automation, fast production speed, large daily consumption of raw materials, and a small amount of BOPP functional additives added, generally several thousand PPM. During the production process, it is impossible to mix a small amount of additives with a large amount of polypropylene like in the production of CPP or blown film. Therefore, in actual production applications, various additives and polypropylene are usually mixed in a certain proportion to form a master batch.materials, and then put the masterbatch into production to increase the dispersion and uniformity of the additives. There are many types of BOPP functional additive masterbatch, including antistatic masterbatch, Slip masterbatch, Strengthening Masterbatch, Nucleating agent masterbatch, pearlescent masterbatch, whitening masterbatch, Antiblock masterbatches, and synthetic paper masterbatch , anti-fogging masterbatch, Extinction compound masterbatch, antioxidant masterbatch, etc.

1. Antistatic masterbatch

The antistatic agent used in antistatic masterbatch is mostly a compound of glyceryl monostearate and ethoxyamine. The mechanism of action of the antistatic agent is: the lipophilic group in the organic matter of the antistatic agent interacts with polypropylene to increase its compatibility in polypropylene; on the other hand, the hydrophilic group in the antistatic agent interacts with the air The water in the film interacts to eliminate the electrostatic charge accumulated on the surface of the film. In the actual production of BOPP films, an appropriate amount of antistatic agent is usually added to eliminate static electricity generated by friction during the production and use of BOPP films. Antistatic agents are surfactants with strong mobility. They are usually added to the core layer of the film to ensure the medium and long-term antistatic effect of the film product.

The amount of antistatic agent used in BOPP film products is related to the market’s requirements for the product.For BOPP films with high antistatic requirements (such as packaging powder and dust products), the amount of antistatic agent can be increased. But it is particularly worth noting that since the antistatic agent is a low-melting surface active substance, it migrates to the surface of the film to form a thin organic layer. As the ambient temperature decreases, the film will produce tension due to tension during the winding process.Internal stress and radial pressure can cause the organic layer to solidify, causing film adhesion. Therefore, in actual BOPP film production, in addition to adding antistatic masterbatch to the core layer of the film, inorganic silicon anti-adhesive agents are usually added to the surface layer to eliminate the negative effects caused by antistatic agents.

2. Slip masterbatch

BOPP film slip masterbatch is made by mixing lubricant and polypropylene in a certain proportion through a single-screw or twin-screw extruder. In the production of BOPP film, the lubricants used mainly include erucamide, oleic acid amide, ethylene bisstearamide and silicone lubricants.Erucic acid amide and oleic acid amide have good external lubricity. Erucic acid amide has better high temperature resistance than oleic acid amide, with a decomposition temperature as high as 220°C. It is more suitable for the production of polypropylene masterbatch and the production of BOPP film.

The decomposition temperature of oleic acid amide is around 180°C. In actual masterbatch production, antioxidants and other additives are often added to improve its high temperature resistance. Ethylene distearic acid has poor external lubricity and medium internal lubricity. These three lubricants are all migrating substances and are usually added to the core layer of the film. They migrate to the surface of the film to form a thin lubricating layer, reducing the friction factor of the film. When the film is subjected to corona treatment, the migration is particularly strong and often "frosts" on the surface of the film. Since the migration affects the haze of the film, in actual production, it should be controlled as much as possible on the premise of meeting the technical indicators.its dosage. Silicone lubricant is a non-migrating substance with good external lubrication effect and good external lubrication effect at higher temperatures (such as 80°C). It is more suitable for the packaging operation requirements of BOPP cigarette packaging film. Therefore, , is widely used in the production of BOPP cigarette packaging film. Because it is a non-migratory substance, it can only be used on the surface layer of BOPP cigarette packaging film.

3.Strengthening Masterbatch

Stiffness-increasing masterbatch is a modified material, which is mixed with homopolymer polypropylene and modified stiffness-increasing materials in a certain proportion. Currently, there are two types of stiffness-enhancing materials: 1) terpenoid polymer compounds synthesized from natural rosin oil and orange oil; 2) hydrocarbon polymers. Stiffness-enhancing masterbatch can significantly change the properties of homopolymer polypropylene,giving it some excellent properties that pure polypropylene films do not have. For example, in the production of BOPP cigarette packaging films, 20% stiffness-increasing masterbatch (the addition of stiffening masterbatch in the masterbatch) The content of rigid material is about 40%), which can significantly change the air tightness of the cigarette packaging film, which is beneficial to the long-term flavor of cigarettes; because it has good fluidity, it can reduce the shear between the screw and the polypropylene melt.

Shear force; it can significantly change the thermal shrinkage rate of the film, making the film have a higher thermal shrinkage rate to adapt to the compact requirements of cigarette packaging; in addition,it can also change the transparency and heat sealability of the film, and reduce the haze of the film , heat sealing temperature to adapt to the high-speed packaging requirements of cigarette packaging machines.

A notable feature of the rigidity-increasing masterbatch is that it can significantly increase the tensile strength and Young's modulus of BOPP films. After a certain period of aging, the Young's modulus of the film can be increased by about 40%. Strengthening masterbatch is the masterbatch with the widest range of modifications for BOPP films developed in the market so far. However, because it is relatively expensive, it is currently mainly used in the production of high-end heat shrinkable cigarette packaging films. 

4.Nucleating agent masterbatch

The main components of anti-reflection masterbatch are polypropylene and anti-reflection agent. Currently, the anti-reflection agents used in the international market are mainly dibenzylidene sorbitol organic compounds.The anti-reflection mechanism is to change the crystal form of polypropylene to refine the crystal size, thereby increasing the transparency of the product.

The anti-reflection agent is also a nucleating agent, which can promote the rapid crystallization of polypropylene, which is beneficial to improving the rigidity, surface gloss, heat distortion temperature and other physical and mechanical properties of the product. Since the anti-reflection agent is expensive and the BOPP polypropylene special material itself has high transparency, in actual BOPP film production, except for film varieties that require high transparency, other general-purpose films are rarely used, but increasing Penetrants are widely used in cast films and injection molded products because the haze of such products is generally large.It is worth noting that anti-reflection agents can only reduce the haze of polypropylene itself and cannot eliminate or reduce the impact of migratory additives on film haze.

5.Pearlescent masterbatch

Pearlescent masterbatch is a very important additive material for the production of BOPP film. Its main components are polypropylene, ultrafine calcium carbonate particles and other additives. The principle of producing pearlescent light is: during the orientation stretching process of the film, the polymer chain segments adapt to the orientation of the external mechanical force through conformational changes,but the calcium carbonate inorganic particles cannot be stretched, so the polymer chain segments flow around the inorganic particles and are produced. Small air gaps are eliminated, and it is these air gaps that destroy the refractive properties of the film, thereby giving the film its pearlescent color. It is precisely because of these small air gaps that the density of the matting film (around 0.7g/cm3) is much lower than the density of ordinary BOPP film (0.91g/cm3).

In addition, due to the presence of a large number of inorganic particles in the film, the haze of the film increases significantly (the haze of pearlescent film is generally about 85%), but this is the standard required for product application. The quality of the pearlescent masterbatch has a great influence on the production continuity of the BOPP pearlescent film (the time for continuous production without film breakage), and the quality of the masterbatch depends on the size of the inorganic calcium carbonate particles, the uniformity of the size and its use in the polymerization process. Dispersion in propylene.

6.Whitening Masterbatch 

Whitening masterbatch is designed to improve the whiteness of white opaque films. It is widely used in BOPP pearlescent films. Its main components are titanium dioxide, dispersant and carrier polypropylene. The content of titanium dioxide in the masterbatch can reach 70%. A good whitening masterbatch must have very good dispersion of titanium dioxide in the masterbatch. Otherwise, white spots will easily form in the film, affecting product quality. Whitening masterbatch is generally added to the core layer of the film, and can also be added to the surface layer of the film, with the purpose of increasing the whiteness.

7.Antiblock masterbatches

Antiblock masterbatches is divided into organic Antiblock  masterbatch and inorganic Antiblock masterbatches. The active ingredients of organic Antiblock masterbatches are opening agents, such as erucamide, oleic acid amide, silicone lubricants, etc.Its Antiblock mechanism is: the organic lubricant migrates to the surface of the film to form a lubricating layer, blocking direct contact between the films that are prone to adhesion (such as antistatic substances).

In addition, the organic antiblock masterbatches can reduce the friction factor on the film surface and increase the mutual sliding and peelability between films, thereby achieving an  antiblock masterbatches  effect. The main components of inorganic antiblock masterbatches are silica, dispersant and carrier polypropylene. Its antiblock masterbatches is: by adding inorganic antiblock masterbatches to the surface of the film,the rigid silica particles on the surface of the film will roughen the surface of the film during the film manufacturing process, thereby achieving an antiblock effect. Since the particle size of the silica particles in the inorganic antiblock masterbatches is very small (generally around 3.5 μm), they are prone to agglomeration due to electrostatic interaction, affecting their dispersion in the polypropylene carrier. Therefore, inorganic antiblock masterbatches. The masterbatch must contain a sufficient amount of dispersant. Inorganic antiblock masterbatches with poor dispersion will form many small white spots on the surface of the film, affecting the product quality of the film.Since the inorganic antiblock masterbatches contains a large amount of inorganic substances, adding too much will affect the haze of the film.Therefore, on the premise of meeting the opening requirements, it should be added as little as possible (the amount added is generally 1%-2 of the surface layer of the film). %). Unlike organic antiblock masterbatch, inorganic antiblock masterbatch can only be added to the surface layer of the film.

In order to save enterprise costs and user convenience, organic and inorganic anti-adhesion composite masterbatch are now developed on the market. It is worth noting that in order to give full play to the anti-adhesion effect of inorganic silicon, it should be added to the surface layer of the film when using it. Because inorganic silicon cannot migrate.

8.Synthetic paper masterbatch

Synthetic paper masterbatch is a special masterbatch for producing BOPP synthetic paper. Its active ingredients are inorganic calcium carbonate powder, imitation paper modifier and dispersant and other materials.  Synthetic paper masterbatch is generally added to the core layer of the film. If single-sided synthetic paper is produced, it can be added to the surface layer.BOPP synthetic paper is developing rapidly abroad, but it is only in its initial stage in China. Most synthetic paper masterbatch is imported from abroad.

9.Anti-fog masterbatches

Anti-fog masterbatch is mainly used in BOPP films for packaging food. Most food is packaged under heating. Because food contains moisture, when the temperature decreases, condensed water vapor will form fine dispersed water mist on the surface of the plastic. Like water droplets, the user cannot clearly see the food in the packaging bag, affecting the sensory quality of the product. Adding anti-fogging additives can reduce the difference in surface tension between the polymer film and water, allowing the condensed water droplets to expand into a continuous water film layer, thus increasing the transparency of the packaging bag. The active ingredient of anti-fogging masterbatch is migratory surfactant, which can be added to the surface layer or core layer of the film when used.

10. Extinction compound masterbatch

Extinction compound masterbatch is a BOPP functional masterbatch used to produce matt films. Its main component is α-olefin polymer. Because its refractive index is different from that of homopolymer polypropylene,light scattering occurs at the interface between the two phases, causing the co-extruded BOPP film to have a matting effect. Matt masterbatch is generally used for the surface layer, and the addition amount is 100%. The thickness of the surface layer of the matting film is generally 3-5 μm, which can achieve a haze of 80% and a gloss of about 10%.

11.Antioxidant masterbatch

Antioxidant masterbatch is mainly used to prevent polypropylene and functional additives from oxidative degradation during the production process. It is generally added during temporary maintenance or long-term shutdown of the production line to prevent carbide from being produced in the extruder or die when the maintenance is completed or restarted.

 BOPP functional additive masterbatch is a very important part of BOPP film production. It directly determines the formula of raw materials for BOPP film production and the performance of film products. Precisely because it is so important,it has developed very rapidly. In the early days of my country's BOPP film production, most functional additive masterbatch came from imports, but now they are basically domestically produced. What is certain is that as the application fields of BOPP films expand, the performance of current additive masterbatches cannot meet the market's requirements for film performance, and more new, high-performance additive masterbatches will be developed and applied.

QINGDAO PRIME TRADE CO., LTD is a company with more than 20 years of experience that specializes in distributing international brand engineering plastic granules. Our company currently distributes Constab BOPP film functional masterbatch. We also have our own modification processing factory, Qingdao Primetech  Plastic Co., Ltd., with a professional technical team to provide you with fast and professional services to meet the needs of customers at different levels.