Plastics are increasingly replacing metals in thermal management. Traditional air-cooling of electronic components is disappearing due to the ongoing miniaturization of modules that contain a large number of high-energy-density components.

Thermal management is becoming increasingly important and complex in electronic modules. Plastics filled with mineral fillers are increasingly replacing metals.

16:9

Messe K-Kunststoffmesse

kunststoffe-international.com

kunststoffe.de

Füllstoffe, mineralisch

Kunststoff Werkstoffe

Füllstoffe für Kunststoffe

Additive

Elektrisch leitende Füllstoffe (Metalllegierungen, Ruß, Graphit)

More than a Gap Filler

At the Fakuma-trade show, the additive manufacturer Quarzwerke is presenting fillers for plastics in electromobility, wind power and for films. They are intended to help processors manage the high requirements on the materials in these industries.

The fillers are based on different minerals

Batterien

Energiespeicherung

Elektromobilität

Mobilität

Messe Fakuma

Füllstoffe, allgemein

Windkraft

Energieerzeugung

Erneuerbare Energie

Kunststoff

Bauwesen

Baustoffe

Folien

Halbzeuge und Zwischenprodukte

Kunststoff-Halbzeuge

Fillers Improve Batteries and Wind Power Plants

After oil extraction and drying, Coffee grounds can be incorporated into plastic compounds as a filler and coloring agent.

The coffee grounds compounds can be used for computer accessories such as a housing of a computer mouse

Bioplastics with Coffee Grounds as a Bio-Based Filler

Biokunststoffe

Coffee Infusion for Plastic Compounds

The selective integration of thermally conductive plastics into assemblies offers huge advantages in terms of freedom of design and technical functionality. The full potential of these materials is then available for the application, provided that the prerequisites have already been created in the product development phase.

Orientation of the filler boron nitride in the area of the weld line on the bezel of a navigation device

How Thermally Conductive Fillers Affect the Weld-Line Strength

Spritzgießen

Kunststoffverarbeitung: Verfahren

Werkstoffprüfung, mechanisch

Messtechnik

Werkstoffprüfung

Bruchmechanische Prüfung

Zug-und Druckfestigkeitsprüfgeräte

A Question of Orientation

In the first quarter of 2021, the official start of a new HPF production plant for high-performance fillers will take place in Dangjin, South Korea. The investment underlines the growth course of the innovative Quarzwerke division HPF The Mineral Engineers in Asia.

Hightech Plant for high-performance fillers in Dangjin, South Korea

Hilfs-und Zusatzstoffe für die Kunststoff-Industrie

Kunststoff-Erzeugung

HPF starts Production in South Korea

Mineral fillers are widely used in the automotive industry to enhance the performance of polymer grades. A recycling concept has now been developed, in which natural fiber-reinforced polymers are pyrolized to produce pyrolysis char as an alternative filler for thermoplastics. 

Recycling of Natural Fiber-Reinforced Polymers to Sustainable Pyrolysis Char Filler 

Thermoplaste

Faserverarbeitung

Kunststoff-Recycling

Kunststoffe

Filler with Lightweight Potential 

Graphite’s good thermal conductivity makes it a suitable functional filler in plastic compounds used for heat management in electronic applications, automobiles, and apparatus engineering. However, different graphites perform differently. Once a suitable, possibly partially modified graphite has been selected, plastics properties can be adapted to the particular area of application. 

Graphite Additives Adapt Plastics to Requirements for Thermal and Electrical Conductivity  

Compound

Recipe for an Extra Portion of Conductivity 

In case of thermoset Sheet Molding Compounds, the density of the resin paste can be reduced up to 22 % by replacing conventional filler materials such as calcium carbonate with bio-based filler materials – with consistent mechanical properties. This was proved on filler materials, which are by-products of plant-based oils and timber production.  

Bio-Based Filler Materials for Sheet Molding Compound Applications 

Duroplaste

Sustainability Depending on the Details 

After the explosion of developments in polymer formulations over the last year, it is worth taking a closer look during Fakuma at details such as functional additives or application-specific modifications. Overall, lightweight design continues to spur development but defined surface characteristics are also in demand. The reported innovations do not just follow current consumer trends but also provide ideas for advanced product and process developments. 

Functional Modifications Characterize Developments in Additives and Compounds 

Hochleistungskunststoffe

Polyamide

Polypropylen

Verbundwerkstoffe / Werkstoffverbunde

Farbstoffe

Pigmente

Additive Fertigung

Oberflächentechnik

Medizintechnik

Compoundeure

Distribuenten

Polymers Can Be Expected Everywhere 

Although fluor-homopolymers already have high performance properties, they are difficult to modify selectively. This is due to the extremely stable chemical bonding of the polymer, which impedes the cohesion to additives. A new type of filler strengthens the bond between particles and plastic. 

New Filler Linking Enhances the Properties of PTFE Compounds 

Fluorkunststoffe

Verstärkungsstoffe

Kohlenstofffasern / -matten

Strong Cohesion 

WACKER is a globally active chemical company with some 13,800 employees and annual sales of around 4.92 billion (2017). Spanning the globe with five business divisions, we currently operate 23 production sites worldwide. WACKER is represented by subsidiaries and sales offices in 28 countries in the Americas, Asia, Australia and Europe.

Wacker Chemie AG  

https://www.wacker.com

Abdeckmassen (Elektronik)

Beschichtungsmassen

Dichtungen

Drucklufttechnik

Betriebsausrüstung / Betriebsmittel

Mechanische Konstruktionselemente

Maschinenelemente

Klebstoffe

Chemisches Fügeverfahren

Verbindungstechnik Verfahren

Klebstoffentferner

Kühlelemente, passive

Kühlkörper

Elektromechanik

Lackieren

Chemisches Bearbeiten (Auftragen)

Polyacetale

Polyvinylacetat

Polyvinylalkohol

Reinigen und Vorbehandeln

Silikone

Teilereinigung

Tenside-Industrie

Verarbeitungshilfmittel

Waschen und Entfetten

Kunststoff-Aufbereitung

Weichmacher

Additives often consist of additive mixtures of heterogeneous components. Their anisometry leads to part properties that depend very strongly on the orientation of the additives. For this reason, it is essential to describe such orientation behavior at an early phase of development when additized plastics parts are being designed.

Simulated fiber orientation in an additive mixture of fibers and spheres with a volume fraction of 4 % each

Simulating the Orientation Behavior of Additive Mixtures

Kunststoffverarbeitung: Maschinen und Komponenten

Additiv-Konzentrate

Prozesssimulation

Software

Simulation

Spritzgießsimulation

Additiv-Batches

Faserverbundwerkstoffe

Andere Werkstoffe

When Fibers Mix with Platelets

To meet stringent flame retardancy demands of areas such as transportation and electronics, components based on thermosets increasingly require a soluble, non-powder flame retardant (FR) due to low layer thicknesses in the final product or due to liquid processing methods. Two flame-retardants developed by Clariant meet these requirements.

20:7

Completely Halogen-Free Flame Retardancy of Epoxy-Fiber Composite Components

Flammschutzmittel

Duroplastische Werkstoffe

Avoiding Filter Effects of  Flame Retardants

Repi has appointed Krunoslav Muha as Business Development Manager to support the development of new additives.

New Business Development Manager at Repi

Additive manufacturer Grafe has developed a new update for its matting agent in 3D printing.

Compared to its predecessor, the matting agent halves the gloss level once again. 

Farbstoffe und Pigmente

Filamente für additive Verfahren

Werkstoffe für additive Verfahren

3D Printing with Less Gloss

Neuburg Siliceous Earth Improves the Performance of PE Greenhouse Film

Greenhouse film should transmit visible light but trap infrared radiation inside the greenhouse. Unfilled PE film cannot wholly accomplish the latter.

Greenhouse film should transmit visible light but trap infrared radiation inside the greenhouse. Unfilled PE film cannot wholly accomplish the latter. With the right filler, however, the film can be a strong IR blocker. Just how well it performs depends very much on the particle size of the additives, as shown in tests on Neuburg siliceous earth.

Greenhouses create the optimum climate for plant growth, enabling earlier harvests and longer growing seasons. This is achieved by ensuring that the film transmits the maximum-possible amount of light in the photosynthetically active region (PAR). In the infrared range (IR), on the other hand, it is desirable for the film to act as a good thermal barrier.

Sunlight supplies radiation extending from 290 nm (UV) through the visible to the near infrared range (approx. 3000 nm). The visible range spans 380 to 720 nm. It is used by plants for photosynthesis. Hence this radiation is also called photosynthetically active radiation (PAR). Measurements, however, often only consider the range from 400 to 700 nm.

The second major spectral range for greenhouses is the mid-infrared wavelength range spanning 7 to 13 µm. It represents the thermal radiation emitted from the earth’s surface, and is also known as terrestrial radiation. This is radiated into the atmosphere and is lost, especially at night. These losses cannot be prevented by a film made of polyethylene (PE), as it is largely transparent to IR radiation in the required wavelength range. PE/EVA copolymer, for example, goes some way toward improving on this by virtue of its vinyl acetate content. Much better results, though, can be achieved with mineral additives that act as an IR blocker.

Fine-particle mineral fillers are used as additives that specifically target a reduction in transmission in the film’s IR range and thus improvements in heat retention. It is important that they do not appreciably reduce transmission in the PAR. Hoffmann Mineral studied the suitability of Neuburg siliceous earth as an IR absorber for greenhouse film. The company investigated blown film made of LDPE (low density polyethylene) or PE/EVA containing Neuburg siliceous earth to assess its optical properties and transmission in the PAR and IR ranges. It also compared the film’s IR efficiency with that of unfilled film containing no IR absorber.

Neuburg siliceous earth is a natural combination of corpuscular Neuburg silica and lamellar kaolinite; it is a loose aggregate that cannot be separated by physical methods. The silica fraction has a round grain shape and consists of aggregated primary particles about 200 nm in diameter (Fig. 1).

Two filler variants were tested. Sillitin V 88 (color values L* 94; a* 0.1; b* 3.8) and Sillitin Z 89 puriss (color values L* 94, a* 0.1, b* 4.0) are both relatively color-neutral representatives of Neuburg siliceous earth. Sillitin V 88 is a coarser grade (particle size d50: 4.0 µm; d97: 18 µm), while Sillitin Z 89 puriss (particle size d50: 1.9 µm; d97: 9.0 µm) is a finer grade that is particularly easy to disperse.

Besides polymer and filler, an antioxidant and calcium stearate were added in typical dosages encountered in practice to stabilize the tested film. The recipe structure was the same for both film types:

<ul><li>92.1 % polymer,</li><li>7.5 % filler,</li><li>0.2 % calcium stearate,</li><li>0.2 % antioxidant.</li></ul>

The compounds were converted into blown mono-film having a thickness of about 100 µm. The LDPE grade employed was Riblene FM 34 F (manufacturer: Versalis; density: 0.924 g/cm³; melt flow rate (MFR): 3.5 g/10 min.), which is suitable for blown-film applications.

Wider-Ranging and More Uniform Light Scattering

Light transmission in the 400 to 700 nm spectral range is an important property of greenhouse film. As mentioned, this is the wavelength range in the solar spectrum that plants use for photosynthesis. Transmission in this range therefore needs to be as high as possible. What is more, it matters whether the light is direct or indirect (diffuse). Too much direct light is detrimental to plant growth, especially in areas of strong sunlight. Mineral fillers offer more extensive and more uniform light scattering, a fact which benefits plant growth.

As expected, the unfilled film exhibits the highest overall transmission. Adding filler reduces light transmission only slightly, however. The fine filler Sillitin Z 89 puriss is somewhat less effective at reducing transmission than the coarser grade Sillitin V 88. The unfilled film produces a diffuse fraction of about 8 %. With the fine filler Sillitin Z 89 puriss, this figure rises to about 28 %. The coarser Sillitin V 88 yields the highest diffuse fraction of about 32 %, and thus produces the strongest light scattering.

Particle Size Influences Haze and Optical Impression

Film haze behaves in a manner similar to that of diffuse transmission. While the unfilled film, as expected, is relatively clear with a haze value of 10 %, the latter figure increases strongly with the addition of filler. The fine filler particles of Sillitin Z 89 puriss, at 35.8 %, produce less haze than the 42.9 % produced by the coarse particles of Sillitin V 88.

The optical impression of the LDPE film fits well with the haze readings. When the same object is viewed through the film, the film filled with Sillitin Z 89 puriss produces the clearest images, whereas those produced by Sillitin V 88 are the milkiest. The reason for this is the particle size of the fillers. Coarser particles cause stronger light scattering and the film appears milkier than in the case of finer particles (Fig. 2).

Gloss was determined at an angle of incidence of 45°. It drops by about 30 gloss units (GUs) as a result of filler addition. Filled film is more matte than unfilled film. Here, Sillitin Z 89 puriss yields the higher gloss value, 36 GU, and thus has a lower matting effect. This correlates well with the lower haze.

As for transmission in the IR range, the focus is on the 7 to 13 µm wavelength range, equivalent to the wavenumbers 1430 to 770 cm-1. The wavelength range around 10 µm corresponds to the maximum energy radiated from the Earth’s surface (terrestrial radiation at 15 °C or 288 K).

The unfilled LDPE film has only a low blocking effect on IR radiation in the required wavelength range. By comparison, Sillitin V 88 lowers transmission significantly in the near- and mid-infrared ranges (Fig. 3). A marked blocking effect on IR radiation is also observed in the case of Sillitin Z 89 puriss. Unlike Sillitin V 88, however, Sillitin Z 89 puriss boosts the blocking effect in the somewhat shorter wavelength range &lt; 9 µm. This is due to the finer grain size of the filler.

IR efficiency, as defined in EN 13206, is the percentage fraction that is blocked by the film in the wavenumber range 1430 to 770 cm-1. Unlike the unfilled PE film, which has an efficiency of just 24 %, the blocking effect arising from use of the mineral filler is 70 to 75 %. Filled film thus has considerably higher heat-retention capacity.

Relative to the unfilled PE film, the fine product Sillitin Z 89 puriss improves IR efficiency by about 47 %, with the coarse Sillitin V 88 improving it by about 52 % (Fig. 4). The material thus has the greatest blocking effect on infrared radiation and accordingly leads to the lowest heat loss. Theoretically, the IR efficiency could feasibly be boosted further by a higher film thickness or higher mineral concentration.

Do PE/EVA and Neuburg Siliceous Earth Complement Each Other?

The PE/EVA films were made with the polymer Escorene Ultra FL 00909 (manufacturer: ExxonMobil; density: 0.928 g/cm³; MFR: 9 g/10 min.; vinyl acetate content: 9.4 wt. %), which is suitable for blown film. As with the results obtained for the LDPE film, the unfilled PE/EVA film showed the highest overall transmission. The light transmission is only slightly reduced by the addition of filler, with the finer grade Sillitin Z 89 puriss again exhibiting the lower losses. The diffuse fraction increases from about 3 % for the unfilled film to about 30 % for the fine filler. In PE/EVA film, too, the coarser Sillitin V 88 gives rise to the highest diffuse fraction of about 35 % and thus to the strongest light scattering.

As expected, the unfilled film is clear, having a haze value of only about 4 %. The haze increases sharply as filler is added, with the finer filler particles of Sillitin Z 89 puriss again producing less haze, at 36.6 %, than the coarser particles of Sillitin V 88, at 43.4 %.

For the PE/EVA films, the optical impression is more or less as would expected on the basis of the haze readings. Of the filled film, that filled with Sillitin Z 89 puriss again has the clearest appearance while that filled with Sillitin V 88 is the milkiest (Fig. 5). Gloss at a 45° angle of incidence drops by 20 to 30 GU as a result of the added filler. The filled film is more matte than the unfilled film.

Even the unfilled PE/EVA film typically has a certain blocking effect in the required IR range of 7 to 13 µm. Filler addition markedly increases the film’s blocking properties even further (Fig. 6). As with the LDPE film, the fine-particle Sillitin Z 89 puriss reduces transmission more strongly in the &lt; 9 µm range than does the coarser Sillitin V 88.

The IR efficiency of unfilled PE/EVA film is inherently around 50 %. Through the addition of fillers, it can be improved to 80 to 85 %. Compared with the unfilled film, this means that the finer filler improves IR efficiency by about 30 % and the coarser one by about 35 % (Fig. 7). Sillitin V 88 is thus the best blocker for infrared radiation and correspondingly exhibits the least heat loss. Theoretically, the IR efficiency could feasibly be boosted further by using a higher film thickness or mineral concentration.

Neuburg siliceous earth makes a suitable IR absorber for greenhouse film made both with PE and with PE/EVA. Compared with unfilled films, light scattering is markedly enhanced in the photosynthetically active wavelength range, with almost no change occurring in overall transmission – this benefits plant growth. In addition, IR efficiency is significantly increased and heat loss is thus markedly reduced.

The two tested products from the Neuburg siliceous earth range differ slightly in this respect. The finer Sillitin Z 89 puriss offers good light scattering and good IR blocking in combination with less optical haze. The filler with the coarser particles, Sillitin V 88, produces the strongest light scattering and the strongest IR blocking, but also exhibits more optical haze.

Other modifications of Neuburg siliceous earth offer scope for further optimization of greenhouse film. Products surface-treated with special additives, for example, are likely to have a positive impact in the form of extended film life and improved weatherability.

Hoffmann Mineral GmbH  

https://www.hoffmann-mineral.com

Ausgabenartikel

The films must promote photosynthesis while retaining heat in greenhouses.

Fig. 6. Comparison of mineral-filled PE/EVA film and unfilled film: Neuburg siliceous earth also markedly raises the IR barrier properties of these films.

Fig. 7. The IR efficiency of filled PE/EVA films reaches values greater than 80 %. However, the increase is lower than that obtained with LDPE films, owing to the higher inherent efficiency in the unfilled state. 

Fig. 1. Neuburg siliceous earth has long served as a filler for plastics intended for various applications, such as tubing, floor coverings and coatings.

Fig. 2. Filler addition renders the LDPE films much milkier. The larger the particles of Neuburg siliceous earth, the milkier the film appears.

Fig. 3. Transmission curves for the mineral-filled and unfilled film: the differential area is shown in red and illustrates the IR blocking properties conferred by the filler.

Fig. 4. The IR efficiency of the film rises markedly with addition of Neuburg siliceous earth. To an extent depending on the filler, the increase is 47 to 52 %.

Fig. 5. The fillers also confer a milkier appearance on PE/EVA film. In these cases, too, the appearance and haze depends on the size of the filler particles.

KUint7-22_Hoffmann-Mineral - Hauptartikel

Siegfried Heckl is Key Account Manager at Hoffmann Mineral; <a href="mailto:siegfried.heckl@hoffmann-mineral.com">siegfried.heckl@hoffmann-mineral.com</a>

Petra Zehnder works in the Applications Technology department at Hoffmann Mineral.

Hubert Oggermüller is Head of the Applications Technology department at Hoffmann Mineral.