Posts tagged ‘hollow glass microspheres’

During the process of bilateral cooperation, Lu Jianping said that everyone has never been “red faced”. “Even if we encounter some problems, it is our main line to communicate quickly and clearly, maximize cooperation, minimize disputes, and achieve harmonious development.”

Jingjiang in late spring ushered in another continuous drizzle. Although this is a weekend, Song Guangzhi, who arrived overnight from Beijing, did not come here to enjoy the spring scenery along the Yangtze River. He quickly finished his breakfast and immediately began the day’s work.

Song Guangzhi is a researcher of the Institute of Physical and Chemical Technology of the Chinese Academy of Sciences (hereinafter referred to as the Institute). He and his colleague Zhang Jingjie led the team to put the industrial work of the hollow microsphere project here. In January 2013, the Institute of Physical and Chemical Technology and the local enterprise Jiangsu Huaxing Heavy Industry Machinery Manufacturing Co., Ltd. jointly established Zhongke Huaxing Jingjiang New Material Engineering Co., Ltd.

The purpose of his trip is to provide on-site technical guidance to the Zhongke Huaxing workshop.

“We both have quite high expectations for the cooperation of this project,” Lu Jianping, General Manager of China Science Huaxing, said in an interview with China Science Daily. “Currently, we are advancing in the expected direction in an orderly manner, and we believe that we will succeed in the future.”

“Love at first sight”

Lu Jianping said that as a business owner, he hopes that the cooperation with scientists from the Chinese Academy of Sciences will bring not only economic benefits, but also social benefits.

With the support of the national “863” plan, the hollow glass microbeads project developed by the Institute of Physics and Chemistry has independent intellectual property rights. In today’s era of increasing attention to environmental issues, the introduction of environmentally friendly new materials into the market is a positive response made by enterprises and research institutes.

After encountering the hollow glass micro bead project of the Institute of Physics and Chemistry, CSHI is facing the challenge of enterprise transformation and upgrading.

A series of factors, such as the appreciation of the RMB, inflation, rising labor costs, and the international financial crisis, continue to stimulate the nerves of domestic small and medium-sized enterprises, affecting the development of some small and medium-sized enterprises to a large extent. Many enterprises are facing unprecedented difficulties and challenges in their production and operation.

Although Huaxing Heavy Industry is not here yet, it hopes to take precautions. “Therefore, transformation and upgrading have been put on our agenda,” Lu Jianping admitted. This time, he will lead the team to take the path of “innovation main body”.

In 2012, a trip to Beijing for scriptures became a transfer. At that time, the Jingjiang Science and Technology Bureau led a team and led dozens of Jingjiang enterprises to investigate projects at several research institutes of the Chinese Academy of Sciences.

After arriving at the Institute of Physics and Chemistry, a leader of the Jingjiang Science and Technology Bureau discovered that the entrepreneur around him, Lu Jianping, had “disappeared.”. It turned out that he had a crush on the hollow micro bead project of Song Guangzhi and Zhang Jingjie at a glance, and had already started the industrialization discussion together with scientific researchers.

“We are grafting advanced technology from the Chinese Academy of Sciences at a high level, aiming to create an energy-saving and environmentally friendly building material industrialization base, and seeking a breakthrough in self transformation,” he said.

Small beads with high energy
Therefore, through the Jingjiang Municipal Bureau of Science and Technology, Huaxing Heavy Industry and the Institute of Physics and Chemistry were engaged in a marriage. “This has also become one of the key factors that our cooperation can achieve,” Lu Jianping said.
Under a high-power electron microscope, high-performance hollow glass microspheres appear to be crystal clear hollow glass beads. Due to this unique structure at a very small scale, hollow glass beads have become a new type of lightweight material with extensive uses and excellent performance that has been developed in recent years.
Song Guangzhi and Zhang Jingjie have developed advanced preparation techniques for hollow glass microspheres over the past decades. In December 2006, the technical achievement of “surface modification of hollow glass beads” passed the appraisal jointly organized by relevant departments and the Chinese Academy of Sciences.
Since then, with the continuous support of projects such as the National “863” Plan, the Institute of Physics and Chemistry has continuously deepened its research on hollow glass microspheres, optimized its preparation technology and production process, and continuously improved its product performance.
The research results of hollow glass microspheres have been gradually improved, laying a solid foundation for industrialization. For China Science and Technology Huaxing, the purpose of industrialization is very clear. “We have conducted multiple surveys and tests to determine the main development route of environmentally friendly building materials,” Lu Jianping said.
Although any new product needs to undergo a period of testing to enter the market, he is confident: “Currently, there are not many environmentally friendly building materials on the market, which is a great opportunity for us to enter the market.”
Lu Jianping said that currently, partners have used and tested Zhongke Huaxing’s products, and customers are very excited about Zhongke Huaxing’s products.
“Two sets of thinking” do not exist
During the process of bilateral cooperation, Lu Jianping said that everyone has never been “red faced”. “After we encounter some issues, we quickly communicate clearly to maximize cooperation and minimize disputes. Harmonious development is our main line.”
Lu Jianping disagrees with the statement that scientists and entrepreneurs have “two sets of thinking modes” and hinder the cooperation between scientific research institutions and enterprises: “because what we pursue in cooperation is win-win.” It is true that the thinking of scientific researchers is more inclined to the progressiveness of achievements; The thinking of enterprises is more biased towards cost control. “But there is no conflict between the two. The progressiveness nature of the results does not mean that the cost is increased or uncontrollable. On the contrary, it can promote production process innovation and achieve the effect of reducing costs.” Lu Jianping said.
On the other hand, Zhongke Huaxing’s business thinking is not blindly pursuing profit maximization. “We have a long-term strategic plan, and maintaining the progressiveness of scientific research achievements is the constant purpose in our enterprise development plan.” He said.
In the cooperation, the Institute of Physics and Chemistry and China Science and Technology Huaxing understand each other and learn from each other’s strengths to complement each other. What the enterprise possesses is business strategy and practical experience, while what the scientific research institutions possess is the basic conditions for conducting research work, advanced technology, and scientific logical thinking methods. The combination of the two will greatly contribute to the long-term development of both sides.

ARTICLE SOURCE: China Science Daily

1. The alkaline lime borosilicate ingredients of the glass microspheres make it stable and inertia for its chemical properties, which gives them safely as a filler or as an additive, without worrying Can resist other chemical corrosion other than strong alkali.
2. The perfect spherical shape gives them excellent consistency, so that after processing, it will not cause warning and contraction due to inconsistent stress.
3. The hollow glass micro -ball is a tiny ball. In the liquid, the action -like micro -rolling bearing bearing should be more liquid than the fillers of the chip, needle, or irregular shape. Decreasing the viscosity of the mixture, the performance of the model is naturally excellent; good processing performance can increase production efficiency by 10%to 20%.
4. The perfect spherical shape makes it have a small ratio of Z, so its oil absorption is low. Compared with the conventional filling material calcium carbonate, the fuel absorption rate/volume of hollow glass microspheres is much lower, and different types of products are 100 grams per 100 grams The oil absorption rate is between 7 and 40 mg, while the oil absorption rate per 100 grams of light calcium carbonate is as high as 120 to 130 mg, and the heavy calcium carbonate is as high as 50 to 60 mg. The amount of resin is reduced, and at the same time, because it can play a role in increased liquidity of the resin, the resin can only be processed as a substrate rather than the filler, which also reduces the amount of resin.
5. Due to the particle size distribution of glass microspheres, small microspheres fill the gap of large microspheres, which increases its solid content. At the same time, its volatile capacity is very low, which reduces VOC.
6. The color is white, so it has good color compatibility.
7, very low real density and strong compressive strength, resulting in its high compressive strength density ratio, which makes it in some applications that require high pressure resistance, such as squeezing, pressing, or pressurizing, or pressing, or pressing, or pressing, or pressing, or pressing, or pressing, or pressing, or pushing, or pushing, or The oil industry can not only play the role of fillers or additives that density density, but also enable it to have a good survival rate and stability in the processing process
8. The particle size is small, and it may not reduce its toughness when mixing with the resin.
9: The interior of the hollow glass microsphere is a vacuum and thin gas. There are poor density and heat conduction coefficients in two different materials. Therefore, it has the characteristics of sound insulation, heat insulation, and low heat conduction. Fill. The thermal insulation characteristics of microspheres can also be used to protect the heat shock caused by alternating changes between the products and the cold conditions of the product.

10: The closed rate is very high, the spherical shape is tight and perfect, and it is insoluble in water, so that its application in the water is also very stable, and the water will not enter the inside of the microsphere. Therefore It is insoluble in water, and its applications in water such as yachts and rowing are also extremely stable.
11: As a test shows that the fillers of hollow or low hardness will absorb and digest the impact intensity when they are impacted, which improves the impact performance of the material. Therefore, it can improve the physical and mechanical properties of plastic products. At the same time, its filling plastic can greatly increase the hardness and elastic modulus of the material, and the ability of stiffness and stress damping has also improved.
12: It can maintain its stability below 600 degrees, so it is also stable in some applications that require a slightly higher temperature.


The impact of micro -pearl powder in the plating fluid on chemical silver plating
In order to eliminate the single -quality silver in the middle of the powder, the amount of plating powder is used to reduce the silver content in the plating powder. Figure 6 shows the overall powder of 20%of the AG content and the surface shape of a single powder. Compared with Figure 6 (a) and 4, it can be seen that with the increase of the amount of powder coverage, the single silver from the pink decrease significantly. This is because the larger the loading capacity, the larger the surface area, the more the core of the silver nucleus, which reduces the appearance of silver single. From Figure 6 (b), it can be seen that except for a few silver particles on the surface of the powder, the size is basically about 50 nm, which is related to the increase in the surface area of ​​the powder and the increase in the area of ​​silver -shaped nuclei, which is related to the increase in the number of cores. Because in the same amount of silver analysis, the larger the number of silver cores, the shorter the core of the core, and the result is reduced to the silver particle size plated on the surface.
in conclusion

The chemical silver plating of hollow glass microspheres is prepared to prepare the hollow glass micro beaded powder with a dense and continuous coating layer. The thickness of the coating layer is about 50 nm. Energy characteristics. At the same time, the effect of chemical silver -plated process parameters on the silver -plated silver plating of hollow glass, and found that:
1. By increasing the content of NAOH in the plating solution. Increasing the P field value of the plating liquid can increase the amount of silver analysis in the plating solution, the coating of the micro -bead surface is more dense and continuous, but there is a single -quality silver with free states;
2. Stabilizer can improve the self -decomposition of the plating fluid, but it has little effect on the uniformity and thickness of the coating of the microfin surface. On the contrary, when the amount of stabilizer is too large, it will also cause the unevenness and denseness of the surface covering layer;
3. By adjusting the loading capacity of the hollow glass microsphere, it can adjust the particle size of the surface of the silver particles, control the thickness of the silver -plated layer, and increase the loading capacity at the same time, which can also reduce the phenomenon of self -decomposition.

Glass microspheres are divided into hollow glass microspheres and solid glass microspheres

1. The main application fields of solid glass microbeads are:
1. Road reflective glass beads:

Road reflective glass beads are divided into internal mixing type and surface scattering type. The internal mixing type is mixed in the paint during the production of road reflective paint, which can ensure the long-term reflection of road markings within the life period.
The surface sprinkler type is used in road marking construction to spread on the surface of the marking line to achieve an instant reflective effect. Road marking glass beads are divided into two specifications: coated and non-coated. Surface-treated coated glass beads are used in road marking construction, which can greatly improve the adhesion between the glass beads and the road marking paint. , Water resistance, enhance the reflectivity of road markings, and have self-cleaning, anti-fouling, moisture-proof and other uses.


2. Shot peening glass beads:

Shot peening glass beads Glass beads used for industrial shot peening and additives can be used on metal surfaces and mold surfaces without damaging the surface of the workpiece and improving the accuracy of the workpiece. It is used for cleaning and polishing of metal metal, plastic, jewelry, precision casting and other objects. It is a high-grade finishing material commonly used at home and abroad.





3. Grinding glass beads:

Grinding glass beads have the advantages of good chemical stability, mechanical strength and hardness, surface finish, good fluidity, low abrasion, easy industrial and mining control, etc. As abrasive materials, they are widely used in chemical materials, coatings, pigments, food, medicine and other fields.






4. Glass beads for decoration:

Glass microbeads, glass sand and colored glass microbeads for handicrafts are ideal materials for garment printing, garment heat transfer, Christmas tree surface decoration, artificial fruit, artificial flower crafts surface decoration, and hourglass quicksand manufacturing.






5. Filling:

Glass beads are also widely used as a new type of material in various fields such as medical equipment and nylon, rubber, engineering plastics, and aviation. Such as additives, enhancers and so on.



2. The main application fields of hollow glass microspheres are:

1. The color is pure white, which can be widely used in any products that have requirements on the appearance color.
2. The specific gravity is light, and the density of hollow glass microspheres is about one tenth of the density of traditional filler particles. After filling, the basis weight of the product can be greatly reduced, more production resins can be replaced and saved, and the product cost can be reduced.
3. Lipophilic, hollow glass microspheres are easy to wet and disperse, and can be filled in most thermosetting thermoplastic resins, such as polyester, epoxy resin, polyurethane, etc.
4. Good fluidity. Since hollow glass microspheres are tiny spheres, they have better fluidity in liquid resins than flake, needle or irregular fillers, so they have excellent mold filling performance. More importantly, the small microbeads are isotropic, so there is no disadvantage of inconsistent shrinkage rates in different parts due to orientation, which ensures the dimensional stability of the product and will not warp.
5. Heat and sound insulation, the hollow glass beads are thin gas inside, so it has the characteristics of sound insulation and heat insulation, and it is an excellent filler for various thermal insulation and sound insulation products. The insulating properties of hollow glass microspheres can also be used to protect products from thermal shock caused by alternating between rapid heating and rapid cooling conditions. High specific resistance and extremely low water absorption make it widely used in the production of cable insulation materials.
6. The oil absorption rate is low. The particles of the sphere determine that it has the smallest specific surface area and low oil absorption rate. During use, the amount of resin can be greatly reduced. Even under the premise of high addition amount, the viscosity will not increase a lot, which is greatly improved. The production operating conditions can be improved, and the production efficiency can be increased by 10% to 20%.

Article Source:HS glass beads

RTP Company announces the availability of specialty compounds containing hollow glass microspheres which reduce part weight, enhance properties and lower part costs in demanding applications.

High loadings of these microspheres, which are manufactured by 3M and known as ScotchliteTM Glass Bubbles, can be added to thermoplastics to reduce overall part weight, and thus per part material costs. Additionally, they can modify polymer characteristics, achieving lower viscosity, improved flow, and reduced shrinkage and warpage.

For example, some compounds containing ScotchliteTM Glass Bubbles can have their specific gravity reduced by as much as 30 percent. The use of glass bubbles also provides more uniform control and reproducibility than other methods typically used for weight reduction, such as foaming agents.

ScotchliteTM Glass Bubbles reduce thermal conductivity and lower dielectric constants of most thermoplastics. Non-combustible and non-porous, the glass bubbles do not absorb moisture. Compounds containing ScotchliteTM Glass Bubbles are available in most engineering resins and easily adapt to common processing methods, including injection molding and extrusion. Applications that can benefit from this weight saving technology exist in the aerospace, automotive, marine, electronic, and medical industries.

FROM:RTP Company

In order to give full play to the effect of hollow glass microspheres, it is necessary to ensure that the hollow structure remains intact during the addition process. The strong shear in the twin-screw extruder can easily break the glass beads. Once the hollow glass beads are broken, they will become glass fragments with a density of 2.5g/cm3, which cannot achieve weight reduction. This is also the main reason why many application products did not achieve the desired effect in the initial stage of the experiment.
Therefore, how to reduce the breakage rate of microbeads in the twin-screw extruder granulation process is the key to the excellent performance of hollow glass microbeads.
Specifically, it can be considered from the extruder thread combination, feeding and pelletizing method, main engine speed, and compressive strength of microbeads.

01 . Adjustment of twin screw thread combination



In a twin-screw extruder, the shear force of the screw on the material makes the filler evenly dispersed. The spherical shape of the microbeads is easier to disperse, and excessive shear force can easily cause them to break. Therefore, the angle of the thread block of the meshing section should be adjusted, and the shear force should be reduced according to the low shear design. The specific adjustment method is as follows (real shot by St. Wright Laboratory):







After improving the thread combination
Comparison of crushing rates caused by different feeding methods and granulation methods




02. Adjustment of feeding method
To better reduce the bead breakage rate, you should:
1) Select side feeding to reduce the chance of microbeads being sheared in the screw.
2) Select long particles for granulation to reduce the damage of strong mechanical force during granulation.
After improving the thread combination
Comparison of crushing rates caused by different feeding methods and granulation methods





1. Sanlight HS46, compressive strength: 16000psi, D90 (typical value) 30μm, specific gravity 0.46g/cm3.
2. Sanlight HL60S, compressive strength: 18000psi, D90 (typical value) 55μm, specific gravity 0.60g/cm3.

03. The influence of the rotational speed of the twin-screw machine
When the rotation speed is high, the shear force on the material is greater, which makes the microbeads more easily broken. Therefore, under the premise of ensuring the production process, reduce the speed and reduce the shear force of the screw.
After improving the thread combination, long particle granulation and side feeding conditions
Comparing the crushing rate caused by different screw speeds




When the content of microbeads is about 10wt%, the crushing rate of microbeads increases with the increase of screw speed, and the crushing rate rises to 7.23% at 400r/min.

04. Common problems and solutions






1) What is the normal breakage rate of microbeads during extrusion?
Due to the problem of the processing method, the microbeads will have a certain breakage rate during the extrusion process.

Adjust the screw combination, add microbeads to the side feed, granulate long particles, and the crushing rate can be controlled at 2-3%.

2) Does the addition of microbeads affect the resin processing performance?
Microbeads are an inorganic powder filler, similar to other inorganic fillers, which can improve the heat resistance of the resin after adding. Therefore, the processing temperature is increased.

1. The extruder is at the original processing temperature;
2. Add a small amount of lubricant to the formula to solve.

3) After the microbeads are fed from the side, how to ensure the uniformity of feeding?
1. Side feeding chooses twin-screw forced feeding;
2. A stirring rod should be added to the side feeding to prevent microbeads from “bridging” and ensure uniform feeding.
4) Will the mechanical properties of the resin drop significantly after adding microbeads?
Part of the impact performance will be sacrificed after adding microbeads, but part of the flexural modulus can be improved.

ways to improve:
1. Add a small amount of toughening agent;
2. Modify the surface of the microbeads with a coupling agent to improve the binding properties of the microbeads and the resin.
In addition, the compatibility of hollow glass microspheres with resin is not good, and the interfacial adhesion between resin and glass microsphere material will become poor, which will greatly reduce the performance of hollow glass microspheres, so improve the interfacial adhesion between them. Compatibility is very important.

Commonly used methods to improve compatibility include:
(1) Add compatibilizer: use coupling agent or maleic anhydride graft resin to improve the interface adhesion between the two;
(2) Surface etching: using acid and alkali to produce a large number of defects on the surface of the microbeads, at this time, the resin will be filled into the defect gap to achieve a stable effect;
(3) Surface modification: Through the reaction of strong oxidants and or acid-base and SiO, compatible functional groups such as silicon carboxyl groups and hydroxyl groups are generated; these functional groups can also be modified, and these modified functional groups can be grafted, polymerization and other reactions. Thereby improving the interfacial adhesion.

FROM: Eighth Element Plastic Edition

The development of the times has put forward higher requirements for materials, shoes are lighter, cars are more fuel-efficient, plastic products are more environmentally friendly, processing performance is better, cost is lower, and quality is better…
These are the source of material innovation and the driving force of the development of the times. As a new type of functional filler, hollow glass microspheres have gradually come under the spotlight of the material industry, bringing possibilities for more innovations.

Application of hollow glass microspheres in resin system
High-strength, low-density hollow glass microspheres can be used as lightweight additives in a variety of polymers and applications, while maintaining or improving processability and material physical properties, including:
1) Polyolefins, nylon composites and other thermoplastics
2) Thermosetting materials, liquids and pastes
3) Sheet molding and bulk molding composites
4) Elastomers
5) Substitute wood/polymer composites

Performance improvement of hollow glass microspheres for resin systems
The hollow microspheres can withstand processing conditions such as temperature and pressure of blending, injection molding, extrusion and other manufacturing processes. Correct use can improve product quality:

reduce weight
First of all, the density of glass beads is 0.4-0.75g/cm3, which reduces the density of the composite material to achieve the effect of weight reduction. Secondly, due to the hollow characteristics, the use of resin is reduced while meeting the performance; The development of aviation lightweight.

Improved dielectric properties
Since the interior of the glass beads is air, the dielectric constant of the air is 1, which makes the dielectric constant of the hollow glass beads very low as a whole, reducing the loss of high-frequency signals, which is very useful in the 5G industry and autonomous vehicles. .

Improve flow performance
Hollow glass microspheres are tiny spheres that play the role of miniature ball bearings in the resin, and have better fluidity than flake, needle or irregular shaped filler particles. The resulting microsphere effect makes mixing The viscosity of the material decreases, the filling performance is naturally excellent, and the good processing performance can increase the production efficiency by 15% to 20%.

Reduce shrinkage and warpage of products
Since spherical objects are isotropic, filled microbeads can overcome the disadvantage of inconsistent shrinkage rates of different parts caused by orientation, ensure the dimensional stability of the product, reduce warpage, and solve the problem that has always existed in the molding of special-shaped materials and large injection molding products. deformation problem. In addition, hollow glass microspheres are used as fillers to improve the processing speed of filling and modified materials and improve production efficiency.

lower oil absorption
The oil absorption rate of hollow glass microspheres is 0.20~0.60cc/g, because of its spherical structure, the specific surface area per unit volume is lower, and the oil absorption value is lower.

Volume cost is more economical
The density of high-performance hollow glass microspheres is only 1/5~1/2 of the resin density, and only a small amount of hollow glass microspheres can be used to replace other heavier powder materials under the same volume. When considering the cost per unit volume, the weight of the product can be reduced after filling, thereby reducing the amount of the main raw material resin and rubber, and reducing the cost of the product.

Reinforced resin rigidity, sound insulation and noise reduction
Hollow glass microspheres are rigid particles themselves, which can improve the compressive strength and modulus of the material after being added to the resin.
At the same time, because the interior of the glass beads is air, the air thermal conductivity is low, and the porous material will absorb the vibration of the sound wave, thereby reducing the heat and hindering the transmission of the sound wave.

FROM:Eighth Element Plastic Edition

White roof coatings have existed in hot countries for a long time. These coatings help to reflect solar energy back into the atmosphere, rather than heating up the building. To achieve this white finish, pigments and fillers like titanium dioxide and calcium carbonate are used.

This article demonstrates that, with the use of hollow glass microspheres in a coating, one can achieve a high level of total solar reflection with the dry film. This helps to reduce the need for energy-intensive cooling systems.

It is worth noting that there are many coating applications possible with this technology and that it is not just restricted to improving the energy efficiency of buildings. Other examples that would benefit from the use of solar heat reflective coatings include caravans, mobile homes, cold storage distribution centres, refrigerated vehicles, oil and gas storage tanks, cryogenic tanks and tankers, and deck coatings.

Total solar emission comprises UV, visible and IR radiation – the latter responsible for heating. In this article, we will show that hollow glass bubbles offer an excellent level of reflection in both the visible and IR regions of the spectrum.

Testing hollow glass microspheres for Total Solar Reflectance when incorporated into a coating
A waterborne coating was formulated for the subsequent TSR testing. Glass bubbles are compared with calcium carbonate on a volume replacement basis. For this study, 22.5% by volume of glass bubbles or calcium carbonate were used.

A Perkin-Elmer spectrophotometer was used to analyse the Total Solar Reflectance of the subsequent coating at 400 microns. hollow glass microspheres outperformed the reference filler (calcium carbonate). Conventionally filled roof coatings absorb over 50% more solar energy compared to systems containing the novel, small particle size glass bubbles. This correlates to impressive temperature reduction. These coatings can also be applied with an airless sprayer, without breakage of the hollow glass microspheres.

How does Total Solar Reflectance correlate with the reflection of heat?
Each coating was painted onto an aluminium panel and exposed to an IR lamp. A thermocouple on the other side of a supporting polystyrene box was monitored over time, to investigate the thermal barrier presented by the coating.

A good correlation is found between Total Solar Reflectance and the level to which heat transfer is reduced through the coating. with a reduction of 10°C when compared to the coating containing only calcium carbonate.

What other benefits can hollow glass bubbles impart to your coating?
Additionally, hollow glass bubbles reduce microcracks forming in the coating, due to the reduction of shrinkage and warpage under temperature fluctuations. These cracks can form thermal bridges through the coating and areas for water infusion, leading to subsequent algae and fungal growth. Glass bubbles reduce crack formation when using nails or screws.

Author: Adam Morgan , Ph.D.

We will take a closer look at how the unique morphology of Glass Bubbles translates to benefits in modern composite systems. We will also explore the latest in Glass Bubbles technology for composites systems.

What are Glass Bubbles?
Glass Bubbles are tiny, hollow glass microspheres. They appear as a white free-flowing powder and are made from a water-resistant and chemically stabile soda-lime-borosilicate glass. Originally developed by 3M in the 1960s, they can nowadays be found almost everywhere: from the deep seas to the stratosphere, from specialist industrial applications to consumer goods. Cars, airplanes, bowling balls, fishing line, snowboards, deck chairs, and so on, all make use of the unique properties of Glass Bubbles.

The composites sector recognised early on that Glass Bubbles have an exceptional ability to reduce the weight of composite parts. Compared to conventional fillers such as talc or calcium carbonate, the density of Glass Bubbles can be 20 times lower (depending on the grade). Glass Bubbles have since become ubiquitous in resin systems including polyesters, polyurethanes, and epoxies.

Glass Bubbles are hollow glass microspheres that behave like free-flowing powders. The automotive industry has embraced these materials for their unique ability to lightweight parts as well as add other benefits.
The automotive industry in particular embraced Glass Bubble technology as lighter parts translate to improved fuel economy. In cars and trucks, Glass Bubbles can be found in composite parts such as exterior body panels, roofs, headlight reflectors, wind deflectors, fenders, floorboards, access doors, and internal panels such as engine housings and spare tire wells.

While Glass Bubbles are best known for their ability to reduce the weight of parts, this is far from their only feature. Modern applications in composites rely on the ability of Glass Bubbles to improve processing and to enhance the properties of the final composite parts. Processing improvements generally refer to the ability to produce parts at increased production speed and with greater ease. Property enhancements refer to complementary functionalities brought on by the Glass Bubbles. These can be extremely diverse, ranging from mechanical properties (stiffening) to fire-retardant properties, acoustics & dampening, and thermal insulative properties.

Glass Bubbles are lightweight
The density of Glass Bubbles ranges from 0.15 g/cc to 0.60 g/cc. In contrast to other mineral fillers such as chopped glass fibre, calcium carbonate and talc, the volume per unit of weight is therefore much greater. Replacing inorganic fillers with Glass Bubbles therefore results in composite parts with reduced density. For example, 1 kg of typical Glass Bubble material (K20) has a volume of 5000 cm3, while the equivalent weight of CaCO3 displaces only 370.4 cm3. Due to the extremely low densities of Glass Bubbles, formulation, therefore, needs to be on a volume basis rather than a weight basis. If one were simply to substitute an equal weight of Glass Bubbles for the calcium carbonate in a formulation, the volume ratio of all other ingredients would be reduced substantially. Formulating by volume instead of weight allows the proper balance of resin, filler, and reinforcement, so components can be made lighter while still maintaining a good balance of physical properties.

An older but useful example of the use of Glass Bubbles to precisely control the weight of the final part can be found in the manufacturing of bowling balls. Here, the inner cores of bowling balls are prepared using a cast polyester resin. The more Glass Bubbles used in the resin, the lower the density of the bowling ball. Therefore, the final weight of the bowling ball can be adjusted precisely and easily by adjusting the volume concentration of Glass Bubbles in the resin. Importantly, the addition of Glass Bubbles does not affect the stability of the resin, and the resin mixture remains free-flowing. As this simple example highlights, Glass Bubbles have more to offer advanced composite materials besides the obvious density reduction. In the next section, we will explore the secondary benefits and how they relate to the unique physical characteristics of Glass Bubbles.

When incorporating Glass Bubbles into a composite, one is essentially replacing a fraction of resin and/or solid fillers with uniform and microscopic pockets of air. The replacement of resin by air results in some unique side effects.

For example, the reduction of mass in turn reduces the heat capacity of the resin, which in turn results in shorter cooling times allowing parts to be produced faster. Moreover, the composite’s coefficient of linear thermal expansion (CLTE) decreases. The low CLTE means that larger composite parts can be manufactured, and these are less prone to deformation during cooling, also known as warpage.

The low CLTE can also provide benefits in the finished parts. For example, solid parts engineered using Glass Bubbles (e.g. roofing trims) will be less prone to cracking when exposed to hot/cold cycles.

In a similar vein, the thermal conductivity is lowered by the presence of Glass Bubbles. The resulting thermally insulative parts find extensive use in energy-saving applications (e.g. bathtubs which keep water warm for longer) and also add value to various consumer goods (e.g. steering wheels or shower trays which are warm to the touch).

Replacing resin and solid fillers with hollow Glass Bubbles also lowers the calorific content of the composite part. A useful side effect of this property is that fire retardant performance is improved by the introduction of hollow Glass Bubbles – simply put there is less material to burn – resulting in better fire ratings. Recently researchers also discovered secondary mechanisms by which the hollow nature of Glass Bubbles leads to a fire hazard reduction, for example in rigid foams.
The hollow nature of the Glass Bubbles further impacts the composite’s interaction with light and sound waves. This property finds its use in specialised applications such as acoustic damping.

Glass Bubbles, as the name implies, are perfectly spherical. Glass Bubbles therefore have the lowest possible surface to volume ratio of any filler. As a result, Glass Bubbles require less resin to be wetted out compared to non-spherical fillers. In many cases this means that the resin content can be lowered, resulting in cost savings and reduction of VOC emissions.

Another side effect of the spherical nature of Glass Bubbles is that the effect on the viscosity of the resin is minimised. This property is often described as a ‘ball-bearing’ effect. A better flowing resin not only allows parts to be produced more quickly, but it also results in a more isotropic filling of the mould. This in turn leads to composite parts in which stresses are more uniformly distributed. In contrast, angular fillers such as talc or glass fibres tend to interlock at higher loadings resulting in stress concentrations and fracture points in the cured part.

A great example of a technology that has successfully exploited the low viscosity impact of Glass Bubbles is Reaction Injection Moulding (RIM). RIM is a manufacturing process in which liquid polyurethane or polyurea precursors are combined, injected into a mould, and subsequently polymerised to produce the part. Since the resin is introduced into the mould as a liquid, flowability of the resin is key to ensure the precise reproduction of components with thin walls and complex geometries. Glass Bubbles work in this application to maintain flowability and to reduce the density of the parts, typically alongside heavier reinforcing fillers such as acicular Wollastonites.

Glass Bubbles are closed spheres consisting of a chemically stable soda-lime-borosilicate ‘shell’, so they are intrinsically stable toward heat damage and chemical degradation. Glass Bubbles can therefore be added into most resin systems including polyester, epoxy, and polyurethane. Their size, shape, and chemistry will not be affected by processing conditions such as temperature, humidity, nor will their properties change over time, such as during storage. The dimensional and chemical stability of Glass Bubbles is a unique advantage over other lightweight fillers such as plastic microspheres.

The stability of Glass Bubbles is particularly useful in applications in which there is some delay between mixing and curing of the resin formulation, which includes epoxy or polyester marine putties, adhesives, sealants, and polyurethane structural foams.

Glass Bubbles can withstand high external pressures due to their spherical shape and chemical make-up. The strength of Glass Bubbles quantified as the isostatic crush strength, which is dependent on the grade and varies between 100 to 30 000 PSI. Since the crush strength of a specific grade depends greatly on the wall thickness, the crush strength and density of the grade are inversely related. As a result, the selection of a grade of Glass Bubble for a specific application is usually determined by the crush strength required to survive the processing during manufacturing of the part.
Sheet moulding compound (SMC), the most prominent mass manufacturing technique to produce large composites structures, is a great example of a process in which the high strength of Glass Bubbles is of benefit. SMC is produced in sheets that consist of a thermosetting resin combined with glass fibres and other fillers. The SMC is moulded by part manufacturers under high pressure and subsequently cured. As described in the introduction, the automotive industry relies on SMC to fabricate both external surfaces (body panels, roofs), as well as internal panels (engine housing, spare tire wells, floorboards). SMC is also widely used in structural applications ranging from trench covers to lightweight roofing panels.

Author: Koen Nickmans , Ph.D.

Hollow Glass Microspheres is a Free Flowing White Powder and showed to be hollow sealed sphere under microscope. Application Hollow glass microspheres have a significant effect to reduce weight and noise insulation, make the products have good anti-cracking performance and re-processing performance, is widely used in glass, steel, artificial marble, artificial agate and other composite materials, and the oil industry, aerospace , new high-speed train, car ferry, insulation coatings and other fields.

Low density drilling fluids made with hollow glass microspheres:
1) Adjustable density in a wide range
2) Incompressible and uniform in density
3) Good lubricity, Reduce drilling tool wear
4) No pollution for reservoir
5) Good stability at high temperature and pressure
6) No loss of MWD signal
7) Mud cake quality improved

Low density cement slurries made with hollow glass microspheres:
1) Density can be decreased to as low as 0.90g/cm³
2) Low porosity
3) High compressive strength
4) Good stability at high temperature and pressure
5) Low fluid loss rate
6) Adjustable thickening time