Plastic packaging material is one of the important uses of masterbatch. It has light weight, good mechanical properties, suitable barrier and permeability, good chemical resistance, good molding performance, low processing cost, and good secondary processing and decoration. Therefore, it has become the packaging material with the largest amount and the most widely used in metal, ceramics, paper, plastic and fiber packaging materials.

Masterbatch provides solutions for improving the application suitability of plastic packaging materials

The purpose of packaging is to protect items, facilitate use and provide product information. In the molding process of plastic packaging materials, the addition of plastic masterbatch can not only provide the required color for the packaging materials, but also improve the processing performance and fastness of plastics (such as light resistance, heat resistance, migration resistance). In addition, other application functions (such as flame retardant, antibacterial, anti-static, barrier) can be added, providing a perfect solution for improving the application suitability of plastic packaging materials.

Classification of master batch

The masterbatch used in plastic packaging materials can be simply divided into two categories according to the composition of the additives used: color masterbatch (the main component is colorant) and functional masterbatch (such as anti-aging additives, antistatic agents, flame retardants, fillers, etc.).

01 color masterbatch

It is the most widely used coloring method in plastic coloring. Different colorants endow plastic products with different color properties. Such as hue, tinting power, coverage, transparency, color fastness (such as light resistance, weather resistance, solvent resistance, migration resistance, heat resistance), etc.

For plastic packaging materials, the purpose of coloring is far from satisfying the requirements of common color identification. More importantly, it is to attract consumers' attention, win customers' attention to packaging products and promote product sales. Plastic color masterbatch, with customized function, can provide the required color for packaging manufacturers.

In addition to the traditional white, black and gray non color system and the common red, orange, yellow, green, green, blue, purple and brown color system, it can also provide a variety of special color effects, such as pearlescent effect, metal texture effect, multi angle color change effect, warm color change effect, photochromic effect, whitening effect, luminous effect, fluorescent effect, marbling effect, imitation wood grain effect, flash or spot effect, etc, It provides a unique visual appearance for packaging products and enhances the attractiveness of products.

02 Functional masterbatch

It refers to masterbatch containing other functional auxiliary ingredients except color. The specific function depends entirely on the active ingredients contained. These functions can be divided into three categories:

Class I: Improve plastic molding and processing performance

For example, processing aids masterbatch that can reduce die scaling and eliminate melt fracture; The cooling masterbatch that reduces the forming temperature; Dry master batch absorbing water in raw materials; Smooth masterbatch for easy demoulding of injection molded parts; Anti slip masterbatch to prevent slipping during film rolling; Anti adhesion masterbatch to prevent adhesion between films during film unwinding; Saving the cleaning masterbatch for color change and cleaning materials; The use of such functional masterbatch not only facilitates the operation of molding processing, but also improves the quality of products, and at the same time improves the production efficiency and reduces energy consumption.

Category II: Improve the physical and chemical properties of plastics

For example, the anti-oxidation masterbatch can improve the thermal aging property and inhibit the yellowing of the product color; Anti aging masterbatch for improving the weather resistance of finished products; Nucleating masterbatch or antireflection masterbatch to improve the rigidity or transparency of the molded part; Toughened masterbatch for improving mechanical properties of molded parts; Smooth masterbatch for reducing the surface friction coefficient of molded parts; Open masterbatch that reduces the opening torque of bottle cap; Thermal masterbatch for improving thermal conductivity of plastic parts; Conductive masterbatch with improved conductivity, filler masterbatch with improved mechanical properties of plastics and reduced cost, etc.

Category III: Add product application functions

For example, anti-static masterbatch that reduces the surface resistance of molded parts; Flame retardant masterbatch for improving fire resistance of materials; Increase the antibacterial masterbatch of plastics against microbial invasion; Improve the barrier masterbatch of plastic packaging materials to prevent gas (such as oxygen, carbon dioxide, water vapor) from penetrating; Degradable masterbatch to reduce plastic pollution; Deodorizing masterbatch for removing odor; Flavoring masterbatch for adding fragrance to plastics; Reduce the fog on the inner surface of food packaging film; Rust proof masterbatch to prevent electronic components from rusting; Laser masterbatch providing laser coding effect; Matte masterbatch with matt effect or even frosting effect, and foam masterbatch with weight reduction, heat insulation, sound insulation and shock absorption effects;

Generally, the master batch is single function. For example, color masterbatch only provides color function; Antistatic masterbatch, only providing anti-static function; Sometimes, according to the requirements of the end application of the product, it is necessary to have dual functions or even multi-function. If it is necessary to not only color the plastic packaging materials, but also improve the application performance, such as anti-aging, it is also possible to combine the colorant and anti-aging additives in a master batch at the same time, that is, multi-functional master batch.

What effects should be considered when formulating the master batch?

When formulating the product formula, the manufacturer of masterbatch usually needs to know the following information: terminal application requirements, shape of the terminal product, type and specification of resin for molding, molding method and process conditions, addition ratio of masterbatch, regulatory compliance requirements of the product, control requirements and inspection methods for key performance, and acceptable price and expected dosage;

For example, if you need a blue masterbatch for beverage bottle cap, when designing the formula, you need to know: what kind of beverage (carbonated beverage? Fruit juice beverage? Tea beverage? Water?) Which material (PP? HDPE?) Which cover type (single cover? Two covers? 38 covers? 28 covers?) Which molding method (injection molding? Compression molding?) Judgment methods for the highest processing temperature, masterbatch addition ratio and color (visual judgment? Instrument measurement?) If the instrument is used for measurement, the measurement conditions (sample form, sample thickness, light source, color space selection, color difference range), whether secondary processing (printing, assembly) is required, regulatory compliance requirements (whether it conforms to the relevant standards of Chinese food contact materials, European Union standards or US FDA regulations), etc.

Because a color can be realized by multiple color matching schemes, but different colorants have different properties and prices. Even for the same kind of colorants, the performance and prices of products provided by different manufacturers are different. However, even if the colors obtained from several schemes are very similar, other properties such as heat resistance, dispersion, migration resistance, dimensional stability, etc. cannot be guaranteed to be similar. Therefore, their suitability for use is not necessarily the same. Of course, there may be a large difference in the cost of masterbatch.

High quality plastic masterbatch usually has several characteristics:

Good compatibility with molding resin; The dispersivity of functional components is good; Good forming processability; It is non-toxic and environmentally friendly, meeting the regulatory requirements of relevant industries; High dilution ratio (i.e. less added amount); Good stability between batches of product quality; High cost performance.

Precautions for using master batch

The use effect of master batch is not only related to the quality of master batch itself, but also related to the quality of raw materials for molding, molding process, equipment and use method. Improper use may cause molding defects or even waste products in plastic packaging materials. Therefore, pay attention to the following issues when using master batch:

1. Processing suitability:

The first is the suitability of the master batch for processing the forming substrate. The masterbatch contains a certain amount of resin. Each master batch is only applicable to the molding resin compatible with it. If the two incompatible masterbatches, the molded parts may peel, delaminate, and lose mechanical properties; Or even if it is compatible, due to the great difference in the rheological properties of the melt, flow marks, weld lines, color streaks and other defects will occur on the surface of the molded part, which will affect the appearance and performance of the product.

The processing suitability of masterbatch, and the second is the suitability of the shape of plastic packaging materials. There are many forms of plastic packaging materials, such as film, sheet, bottle, barrel, lid, etc. Their requirements for dispersal of additives are different. Different plastic packaging materials have different sensitivity to the dispersion of additives. Film and sheet materials require masterbatch with excellent dispersibility, while thick wall packaging materials, such as chemical plastic packaging barrels, require low dispersibility. Therefore, if ordinary injection grade color masterbatch is used for blow molding or cast film, there may be problems such as color spots, rough surface and even small holes.

The third is the processing suitability of master batch. Due to different sizes of plastic packaging materials and different production rates, the molding cycle of products is very short, such as the molding cycle of beverage bottle caps is only a few seconds, and some are very long, such as the molding cycle of plastic trays is several minutes. Masterbatch is limited by heat resistance. For products with long molding cycle, if the master batch with low heat resistance is used, it will change color, scorch, and the additives will disperse and lose their corresponding efficacy.

The processing suitability of master batch also includes the suitability of metering equipment. For the forming equipment equipped with automatic metering device, there are certain requirements for the particle size and uniformity of master batch, especially for the volume metering device, the particle size and uniformity of master batch are particularly high. If ordinary master batch is used, it may cause uneven metering and affect the quality of formed parts.

2. Compliance with regulations

The regulatory compliance of plastic masterbatches depends on the raw materials used. Different industries have different requirements for compliance with the regulations on plastic packaging materials. If the electrical packaging materials need to meet the ROHS requirements; Food packaging materials shall comply with relevant regulations on plastic materials and products used in food contact, such as GB 9685-2016, GB4806.6-2016 and GB4806.7-2016; Cosmetic packaging materials meet the "Hygienic Standards for Cosmetics"; Those exported to the EU should also meet the requirements of ROHS. If the products meet the requirements of electrical industry regulations, they cannot be used as food packaging materials;

3. Performance suitability

Different masterbatches have different performance suitability. For example, the color performance of color masterbatch is not only related to the resin to be dyed, but also related to the shape of the molded part, the mold, and other auxiliary dosage during molding. Therefore, the same color masterbatch may show color difference when used in different products; Another example is the migration resistance of plastic packaging materials, which is related to the contents of the packaging. When the same masterbatch is used to package different types of articles, it may cause problems due to different mobility. For functional masterbatch, there are more factors that affect the effect, so testing and evaluation are required. For example, antistatic masterbatch, with quick effect but short-term type; Slow but long-term; Others are permanent. If misused, the expected effect will not be achieved.