Colors can turn plastics products into real eye-catchers. Kunststoffe asked colorant manufacturers to predict which colors will be trending in the coming year.

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Trend Report on the Coloring of Plastics

Pigmente

Kunststoff Werkstoffe

Additive

Masterbatches

Farbstoffe und Pigmente

Farbstoffe

Farben, flüssig

Garish or Necessarily Plain?

A trade show highlight of masterbatch manufacturer Lifocolor will be its biodegradable plant-based color concentrates. These are claimed to enable a closed-loop system for biodegradable plastics.

When it comes to long-term closed-loop recycling, it is not only the plastics that matter, but also the colorants employed. Lifocolor has developed masterbatches specifically for coloring recycled materials.

Messe K-Kunststoffmesse

kunststoffe-international.com

kunststoffe.de

Farbkonzentrate (Batches)

Biokunststoffe

Biodegradable Plant-Based Colors

Plastics processors have a wide range of colors at their disposal to color their products. Choosing the right color can ultimately be the key to success. But colors are just as subject to trends as materials and designs. Kunststoffe asked manufacturers of pigments, masterbatches, and colorants which colors would be particularly popular in the coming year.

Colors inspired by nature will also be very much in demand in2021. They give products a more sustainable appearance

Trend Report on the Coloration of Plastics

Pigmente, bunt

Kunststoffe

Photonik

Optik

Streifinger, Florian

Recycling

Umweltmanagement

Effektpigmente

Kunststoff-Recycling

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

What Will Be the Color of 2021?

Besides compounds modified for special applications and lightweight components, sustainable materials are also becoming an increasingly important focus. In the additives sector, too, recyclates, the circular economy, and reprocessing are now playing a key role.

Not only Polymers but also Additives and Masterbatches Must Be Sustainable

Zubehör / Hilfsmittel Wärmebehandlung

Wärmebehandlung

Compound

Thermoplaste

PVC-Additive

Andere Werkstoffe

Werkstoffe für additive Verfahren

Vernetzungsmittel

Compoundeure

Dienstleistungen

Handel

PVC-weich (Compounds)

Verarbeitungshilfsmittel, allgemein

Flammhemmende Mittel, allgemein

Betriebsausrüstung / Betriebsmittel

Verarbeitungshilfmittel

Filamente für additive Verfahren

Flammschutzmittel

Gleitmittel für Kunststoff

Attention to Detail

Colored plastics are not just a marketing gimmick, but fulfill important functions with technical components. In particular, they warn of hazards and permit the fast and direct identification of components. However, when coloring such plastic components, the processors are faced with several difficulties. For example, the colorants used must exhibit long-term resistance to high temperatures and must not impair the polymer’s mechanical properties. Therefore, when selecting the colorant, compounders and processors must observe several important points.

How Plastics Processors Find the Most Suitable Colorants for High-Performance Polymers

Kunststoff

Bauwesen

Baustoffe

Hochleistungskunststoffe

Colors for the High-Performance Sector

Sustainable development is the focus of the Israeli company Tosaf’s trade show presence. The company presents functional, color and combined masterbatches for processing by extrusion and injection molding. These will include color masterbatches for recyclates with a special focus on post-consumer plastics as well as biodegradable masterbatches.

Special masterbatches can be used for permanent orange coloring of high-voltage components in electric vehicles

Elektromobilität

Mobilität

Messe Fakuma

Kunststoff-Rezyklat

Masterbatches for Current Trends

At Fakuma, Granula presents masterbatches specially tailored to more sustainable plastic products. For this purpose, the company has developed grades with biological pigments and degradable additives for injection molding and extrusion.

The masterbatches are used, e. g., for pigmenting the lids of to-go cups 

Bio- and PCR-Based Masterbatches

Effect pigments can be used to injection mold thermoplastic parts with a shiny metallic surface. However, non-uniform pigment orientation can lead to optical defects. Suitable simulation methodology enables defects to be predicted and prevented.

There is huge demand for automobiles that have metallic finishes. Plastic parts are often painted or electroplated for this purpose. Metallic effect pigments constitute an alternative. Audi and PEG are working on a simulation process for these pigments with a view to ruling out surface defects. 

Simulating Surface Defects in Parts Using Effect Pigments

Simulation

Software

Effective Prediction

Milliken introduced an orange colorant for electric vehicles. It is said to be very color-stable even at high temperatures.

The colorant offers excellent thermal stability up to 300 °C or more.

Orange Colorant for Engineering Plastics

To be able to manufacture products from 100 % recycled post-consumer materials (PCR), Avient has developed appropriate colorant and additive masterbatches with PCR matrix.

Especially for packaging, post-consumer recycled percentages of 100 % are increasingly in demand

Verpackungsmaterial

Logistik

Standardkunststoffe

Additiv-Batches

100 Percent Made from Recycling Material

The circular economy, electromobility and the continuing corona pandemic are influencing color selection for plastics. Kunststoffe asked colorant manufacturers about the resulting color trends. We also wanted to know what effects the increased use of recyclates is having and the extent to which manufacturers are affected by the present supply bottlenecks.

Colored Mood Enhancers

A metallic look and decorative design using lasers have been very popular for some time. To meet this demand, Rowa Masterbatch includes optimized raw materials in its portfolio.

Metallic surfaces are very popular right now for personal care products and packaging. The fact that they can also be laser-marked without any loss of quality is ensured by a specially developed masterbatch. 

Laserbeschriftung in Farben

Oberflächentechnik

Laserbearbeitungen

Laserbeschriftung

Laser without Color Loss

The mass of recyclable plastic waste has been growing steadily for years. This in turn is raising the requirements imposed on the recycled materials themselves. Aside from the nature of the polymer and the previous application, the color of the recycled material is important.

Due to the intrinsic color of recycled materials, it is very important to check their color frequently. 

Ensuring Color Consistency of Recycled Materials

Messgeräte für Farbe

Qualitätssicherung

Qualitätssicherung Kunststoff

Messtechnik

The Color Loop

BYK-Gardner is introducing a new spectrophotometer which combines several, different measurement methods for precise color measurement.

The compact and lightweight instrument can be easily rotated to adapt the orientation – “top or front port” – to one’s personal needs or sample size and shape.

Farbmessgeräte

Optische Mess- und Prüftechnik

Combined Spectrophotometer and Fluorimeter

Grafe Advanced Polymers GmbH, Blankenhain, Germany, is expanding its color range with black Black3 masterbatches. According to the company’s own information, these have very high color depth and so offer the possibility of creating a piano black look in PP or PE. The products can be used for many different applications in injection molding and extrusion and can be readily processed to achieve both matt and glossy surfaces. 

A new matting agent produces different surface ­effects, also in polished molds (© Grafe) 

Grafe Advanced Polymers 

Matt Is the Trend 

Automated Color Measurement for Bulk Materials

With automated color measurement, it is possible to check the color of pellets during production. This saves time, increases the process reliability and quality and thus reduces scrap. This can be achieved with a specially developed color measurement system.

In compounding, many of the materials used and produced are bulk materials. As intermediate products, they often determine the quality of the final product. Therefore, quality control close to the process is crucial for a high-quality product. Of course, this also applies to colored granules. Color is closely associated with emotions – for example, blue is often associated with relaxation, red with passion and green with harmony [1]. The recognition value of brands is also very often related to their color. Other than the shape, the color of plastics is the first perceived characteristic of a product. People often make the decision whether to buy a product within about 90 s. This decision is oftentimes (62 to 90 %) based on just the color [2]. Even small differences in color give the impression of poor quality, even if the technical properties are otherwise impeccable. For this reason, enormously high expectations are placed on the quality and consistency of color.

Due to these high requirements, continuous quality control is essential. Typically, this is done by laboratory analysis. For this purpose, samples are taken during production, which are then injection molded into plates. After cooling to room temperature, these are visually inspected and analyzed with a laboratory spectrometer. Thus, hours pass between sampling and measurement. This method is also state of the art in the field of color formulation, which makes it possible to adapt the desired color shade (with possible iterations for color correction) for new products or formulations as precisely as possible to the requirements and customer wishes. Batches in production are usually approved after assessment of a sample that complies with the quality parameters. However, if a significant deviation occurs, the entire batch produced within this timeframe is scrap. To keep the time delay and thus the production of scrap for a set color as low as possible, a method that allows a near-process control in a short time must be found.

There are several options for in-process quality control. A distinction is made between methods that measure in the process (inline), measurements in a bypass (online) and measurements close to the production site (atline) (Fig. 1). With the aim of measuring as flexible and close to the process as possible, ColorLite GmbH, together with the German Plastic Center SKZ, has developed a measurement concept in a prototype as part of a publicly funded project that can be used inline, online and atline.

The system consists of a spectrophotometer with an external measuring unit connected to a sample chamber. The measuring unit is connected to the central unit via an optical fiber and electrical cables and is housed in a separate small control cabinet. Built into the control cabinet is the industrial computer with a touch screen for operation, which could also be connected to the production process control system via an industrial interface.

The pellets are illuminated by a white light from an LED-array. The reflected light from the sample gets directed to the evaluation unit via light fibers, where it is spectrally analyzed by a grating spectrometer. Diffuse homogeneous illumination is very important when measuring strongly structured surfaces. This illumination is generated by a barium sulfate coating on the inside of the measuring head.

For inline applications, the measuring chamber can be installed above the dosing unit and thus enables controlling 100 % of the masterbatch used. The feed for the prototype is provided via a suction conveyor (type: Metro HLI 50–1-A220–0, manufacturer: Motan ColorTronic). This setup is also suitable for online applications. In this case, both the educt and the pellet product can be sampled.

SKZ has also designed a substructure specifically to make a flexible, mobile atline application for the prototype possible (Fig. 2). This enables measurements to be made directly on each extrusion line without additional expense. As a result, the time delay between production and measurement is very short, which minimizes any possible scrap production.

Automatic Measurements in the Common Color Spaces

The measuring chamber is equipped with a level sensor (type: KG5306, manufacturer: IFM Electronics), which automatically triggers the measurement as soon as the measuring chamber is fully filled. After the measurement, the bulk material is discharged via a hydraulic trap door. During the measurement, the reflection in the wavelength range from 400 to 700 nm is detected within a measuring spot of 120 mm diameter. This range approximately represents the visible wavelength range.

Using this method, the usual color spaces (CIE Lab, LCh, etc.) can be mapped in addition to the recorded spectral data. The recorded data also includes the temperature of the bulk materials, which is monitored via the additionally installed infrared temperature sensor (type: CS LTH, manufacturer: Optris). The ColorDaTra software, which was specially developed by ColorLite for the project, takes over the control of the sensor technology, the triggering and execution of the measurement and the output and display of the measurement data. All measurements are performed automatically with the desired settings. Only the calibration at the beginning of the measuring day is done manually. However, this requires little effort.

If there are fluctuations in temperature, thermochromic effects occur that influence the color measurements. Thermochromism refers to the property of a substance to exhibit a reversible temperature-dependent color change [3]. The effect is due to a change in the crystal structure of the pigment. For color measurements in the laboratory, which are often carried out according to DIN 5033–4, the temperature of the sample and the laboratory must be kept constant. Often, thermochromism at elevated temperature leads to a darker and less saturated color (Fig. 3). Red pigments in particular are very thermochromic. At a temperature difference of 20 °C, a color difference dE of 2 is already possible (Fig. 4).

Temperature fluctuations throughout the day are not unusual in production halls. The sample temperature can also vary considerably. For example, a freshly produced pellet can still be at a temperature of 70 °C, depending on the granulation and the type of cut-off. Thus, monitoring the temperature is essential in order to correct thermochromic effects if necessary. Since each pigment shows thermochromism differently, calibration series are necessary for such corrections [4].

Granules Can Be Analyzed without  Large Deviations

Granules differ greatly from injection-molded plates. So-called white fracture can occur during cold cut. In this case, the edges of the granules appear white. In addition, the bulkiness of the granules plays a role in the measurement. Thanks to the large measuring spot of the developed system, over which a measurement is averaged, these differences to plates hardly affect the measurement results. The determined color values and their standard deviation are comparable with a benchtop spectrometer (Fig. 5). Also, the cycle times as well as the measured amount of bulk material are consistent over several measuring cycles. This ensures accurate and precise measurements close to the process.

The continuous measurement of color during a production process is useful to improve the quality of the process and its resulting product. While laboratory analysis is suitable for color formulation, it is less suitable for ongoing process control. A prototype developed by ColorLite and SKZ enables in-process rapid determination of the color of bulk materials. The prototype can be used for inline, online and atline measurements. Due to the flexible design, incoming goods and product inspections are possible.

In addition to color control, temperature monitoring also plays an important role due to the thermochromism of some colorants. Previous investigations have shown that it is possible to calculate the thermochromic behavior of samples [4]. By compensating for thermochromism, very accurate color values can be recorded during operation. Based on the values, timely measures can be taken to prevent contamination of a batch.

The prototype developed provides a flexible solution for automatic and in-process control of color. The time delay between sampling and measurement is only a few minutes. Therefore, it is possible to react immediately to process variations and thus minimize scrap. Since no sample preparation is required, measurements can be carried out at short intervals. In addition, the automated measurement and the specially developed software prevent operator errors. ColorLite is currently transferring the prototype into a market-ready device.

[1] Kaya, N.; Epps, H.: Relationship between color and emotion: A study of college students. College student journal 38 (2004), pp. 396–409

[2] Singh, S.: Impact of color on marketing. Management Decisions 44 (2006) 9, pp. 783–789

[3] Etzrodt, G.; Müller, A.: Kunststoffeinfärbung. 2. Aufl. Carl Hanser Verlag, München 2018

[4] Zentgraf, T.; Heidemeyer, P.; Bastian, M.; Pryor, D.: Den richtigen Farbton getroffen?. Kunststoffe 9 (2011), pp. 116–118

SKZ - KFE gGmbH  

https://www.skz.de

ColorLite GmbH  

https://www.colorlite.de

Ausgabenartikel

With the measuring system, color analysis measurements are possible inline, online and atline. This allows for quick intervention during production.

Fig. 1. Overview of measurement methods based on a compounding process: inline, online and atline measurements are analysis methods close to the process.

Fig. 2. One of the prototypes is a mobile version that can be used for atline measurement.

Fig. 3. Temperature-induced color change, known as thermochromism, is common among red pigments.

Fig. 4. L*, a*, b* and dE values of pellets (Maxithen Red) at different temperatures: with increasing temperature, there is a clear deviation in all values.

Fig. 5. Comparison of the L*, a*, b* values of the developed prototype with different measuring devices on the two materials Maxithen Green and Maxithen Red: the prototype measures similar values as the benchtop spectrometer.

KUint1-23_SKZ_Klein - Hauptartikel

With automated color measurement, it is possible to check the color of pellets during production. 

Julia Klein has been working at the research group spectroscopy at the German Plastic Center SKZ, Würzburg, Germany, for two years; <a href="mailto:j.klein@skz.de">j.klein@skz.de</a>

Dr. David Pryor is the managing director of ColorLite GmbH; <a href="mailto:dpryor@colorlite.de">dpryor@colorlite.de</a>

Dr. Linda Mittelberg has been working at SKZ for five years as head of the spectroscopy research group.

Prof. Dr. Martin Bastian is the institutional director of the SKZ.

This Project was supported by the Federal Ministry for Economic Affairs and Climate Action (BMWK) via the AiF as a part of the ZIM project funding (Central Innovation Program for SMEs) on the basis of a decision by the German Bundestag. The authors would like to thank for the support.

ColorLite GmbH, founded in 2003 and based in Katlenburg-Lindau in Lower Saxony, Germany, specializes in spectral color measurement technology. The company offers inline solutions for a wide spectrum of applications such as film, extrudate, granulate and powder measurement. The product range also includes mobile and stationary spectrophotometers.

<a href="https://www.colorlite.de/?lang=en" target="_blank">www.colorlite.de</a>