The world of pigments is very rich, there are different kinds of pigments, there is a pigment called plastic pigment, do you know what it is? What are the characteristics of plastic pigments? Today we will look at these aspects.

Plastic pigment is a kind of color that can change the color of plastic raw materials, plastic color is actually divided into three kinds of coloring, the first use of powder pigment directly colored, plasticizer mixed into paste, and then mixed, the third use of color masterbatch mixed.

The basic needs of plastic pigments are not high, this pigment temperature does not migrate, easy to disperse, and very fast, inorganic pigments belong to a metal oxide, generally high temperature resistance, not migration, suitable for all plastic products, but the coloring power is relatively low, the color category is not complete, the cost ratio is relatively low, some contain heavy metals.

Plastic pigments can be used in many places, such as in the field of ink production, in the field of paint production, in the field of paint production, in the field of synthetic fiber pulp coloring, there are many places that can be applied. The current market competition pressure is very large, the pigment market is also so good pigments in short supply, the general pigment can not be sold, which has become the current reality, in the pigment market to take into account the color, but also have good quality.

The main characteristics of plastic pigments in applications

The main properties of pigments in plastics are determined by factors such as their weather resistance or aging, light resistance, warping or nucleation, transparency, heat resistance and dispersion.

Weather resistance/aging

Exposure to sunlight and outdoor climates can adversely affect the service life of plastic products, so polymers used outdoors often require UV protection and highly weather-resistant pigments, to assess weather-resistance in practice, you must perform outdoor exposure testing in the relevant climate area, which is obviously not always feasible, an alternative method that can be used is accelerated testing. The light stabilizer system must be considered in conjunction with the pigment formulation and the specified fastness criteria for the final product.

Light resistance

Light resistance is the main measure of the color fastness of plastic products in indoor applications, if the pigment has good light resistance, it does not always mean that it has good weather resistance. Pigment performance is also affected by the surface of the product, processing heat and stable packaging. In general, inorganic pigments show better light resistance than organic pigments.

Warping/nucleation

Crystallinity and crystallization rate determine the final properties of plastic products, and organic pigments are known to affect these parameters during the cooling phase of plastic processing, especially in HDPE injection molding, which can lead to:

● Reduce the mechanical stability of plastic products

● Influence on dimensional stability, such as warping and shrinkage

transparency

Typically, transparency is achieved by minimizing the particle size of the plastic pigment as much as possible, which is achieved by surrounding the particle with a coating immediately after the particle formation, thus preventing crystal growth, the most commonly used product of this coating is rosin or rosin derivatives, which is particularly useful for printing ink pigments that require high transparency. And it has the added advantage that such pigments disperse more easily.

Iron oxide pigments can be opaque or transparent, and transparent varieties are an important class of inorganic pigments because they are widely used in metal finishes, their high transparency provides an attractive finish, and their weather resistance improves the weather resistance of pigments that can be combined with them, which is known as a synergistic effect. Transparent iron oxide depends on the particles being unusually small and also having a crystal shape.

● The effect of dispersion on transparency: the dispersion process will affect transparency, because it involves the disintegration of the particle's agglomerate into a single primary particle, but the primary particle will not be split by the dispersion process, the only thing to do is to make full use of the original particle size of the pigment, good dispersion will maximize the transparency of small particles.

Measurement of transparency: Transparency is simply assessed by applying the coating to a black and white contrast chart and measuring the color difference, the greater the color difference, the higher the transparency.

Heat resistance

Heat resistance is defined by the temperature and the residence time of the colorant exposed to that temperature, heat is required when processing polymers, however it can be harmful to the properties of the polymer and colorant, it is important to understand exactly what conditions will be applied when handling, this is especially important when considering that many plastic products produced are actually subjected to heat more than once, Some pigments show an intolerance to temperature, and their performance deteriorates sharply after multiple treatments.

dispersivity

Excellent dispersion of plastic pigments is critical to the performance of the final product. Defects caused by non-dispersed pigment particles (specifications) can lead to a serious drop in performance levels, and the following problems can be avoided through good dispersion of pigments.

● Color inconsistency, color yield loss, color deviation between batches;

Negative effects on the physical and mechanical properties of the final product, such as loss of electrical performance in wire and cable applications;

Negative processing effects, such as filter clogging, fiber breakage or accidental splitting of blown film.

An optimized combination of processing conditions, pigment selection, and dispersants can help you achieve a good dispersion and avoid some of the problems listed above. The finer the pigment is dispersed (the smaller the average particle size), the greater the total surface area of the pigment particles and the greater the color intensity.

In some cases, dispersion of organic pigments is difficult to achieve, when coloring engineering plastics and certain PVC applications, it is recommended to use pre-dispersed pigments, they provide better tone consistency and repeatability, they are not affected by high shear high speed mixer caking during dry mixing. It also has higher color intensity (at representative comparable concentrations), purity, and transparency. 

Understand the types of plastic pigments

It is very important to understand the different types of plastic pigments.

At present, there are three main types of plastic pigments on the market: organic pigments, inorganic pigments and color masterbatches, understanding these different types of colorants will help you better choose the right plastic pigments.

1、 organic pigment is a widely used plastic pigment. There are many kinds of organic pigments, complete colors, bright colors, strong coloring power, and some organic pigments have good stability and durability. Organic pigments can be mixed to create a variety of colors, suitable for the coloring of various polymers.

2、 inorganic pigments: mainly made of natural minerals or chemicals, the most common iron oxide pigments, titanium dioxide and carbon black. Inorganic pigments are characterized by high hiding power and good light resistance, but the color color is not as bright as organic pigments, and the coloring power is relatively low, which is often used in heat-resistant plastics and engineering plastics.

3、 color masterbatch is a mixture of pigment particles and carrier particles, it is an extension of the pigment products, designed for plastic coloring, easy to store, no dust, easy to use and resin stability. Mainly used in injection molding and blow molding products, different plastic pigments have different characteristics. Therefore, these characteristics need to be considered when choosing plastic pigments, such as some pigments have high light and heat resistance, suitable for outdoor or high temperature environment, some pigments have high transparency and color stability, suitable for making transparent plastic products.

In short, choosing the right plastic pigment is an important link in the manufacture of high-quality plastic products. When choosing plastic pigments, it is necessary to understand different types of pigments, consider the characteristics of pigments, determine the required color and effect, consider safety and environmental protection requirements and other factors to ensure that the appearance and performance of plastic products can meet the expected requirements.

Article source: Shanghai Jingyan Chemical, Gaoyou colorful Chemical