WAX EMULSIONS
WAX EMULSIONS
Wax emulsions > for industrial applications
ATAMAN KIMYA’s product portfolio covers a wide range of waxes, including polyethylene waxes, ethylene copolymer waxes and polyether waxes.
WAX emulsions are ideal products in industrial formulations when surface modification, or Surface protection properties are requested.
Wax additives enhance the performance of surface printing ink and overprint varnish formulations
Our portfolio comprises also various wax emulsions, based on different polyethylene copolymer waxes.
WAX EMULSIONS are liquids and are often incorporated in water-based formulations to improve surface properties.
Wax-based additives and wax emulsions are widely used for optimizing the final performance of coatings and inks by efficiently controlling surface properties.
A solid understanding of waxes and how they work will allow you to use these performance additives to your greatest advantage.
Even with careful selection of the appropriate wax surface modifier, your results will depend on the manufactured quality of the emulsion or dispersion.
Wax emulsions and dispersions are formulated additives made of fine and stabilized wax particles, homogeneously distributed in water. Being in the liquid form, they are easily incorporated into coatings and inks formulations by simple mixing.
WAX EMULSIONS normally have particle size < 1µm, and therefore, a minimized effect on the coating gloss
WAX DISPERSIONS (either water or solvent-based), have a particle size typically > 1-2µm
Their very fine particle size ensures thorough, homogeneous incorporation with other ingredients of the formulation, maximizing the required effects.
Wax emulsions can be stabilized by either non-ionic emulsifiers (steric mechanism) or by ionic emulsifiers, most often anionic (electrostatic mechanism). Combining anionic and non-ionic emulsifiers provides the emulsion the optimum stability because wax particles are protected through both stabilization mechanisms.
In addition, each stabilization mechanism not only has its own advantages and limitations but also significantly impacts the overall formulation giving added flexibility in formulating.
Factors to be Considered While Formulating Wax Emulsions
Wax emulsions are now well established and extensively used in various aqueous formulations. These ready-to-use wax emulsions can be easily incorporated into a formula by simple mixing.
Benefits of Wax Emulsions
Waxes are typical additives that significantly influence the surface properties of any coatings by modifying the surface free energy. This has an impact on properties described below. All of them are critical properties in the paint, coating and ink applications. Hence, waxes are often classified as Surface Conditioner or Modifier Additives.
Wax Emulsions as Anti-block Agents
Anti-blocking is a term defining a non-stick condition between two surfaces or the resistance to adhesion between two surfaces under the influence of:
Temperature
Relative humidity, or
Pressure
A very well-known example of a blocking condition is when a freshly painted window frame is closed too soon. Sometimes, it can be very difficult to open the window again. Factors affecting blocking include:
Coating surface-free energy
Topography of the coatings
Hardness, and
Tg of the polymer
Wax emulsions as anti-blocking agents are also used extensively for items that are coated, dried and immediately stacked, rolled up for storage or shipment.
Effect of Wax on Slip & Mobility
Slip properties (or lubricity) represent the ability of two surfaces to glide over each other without causing any mechanical damage. Good slip properties require that the slip additive concentrate to the surface during and immediately after application and curing.
Generally speaking, the harder the wax, the better the slip properties
Thanks to this property, wax is widely used in applications:
Inks, OPV’s & Primers,
Paper, Film, & Foil Coatings
Metal coatings
Slip resistance is the ability to manipulate the surface energy by increasing the coefficient of friction of a cured coating. This can be realized by addition of wax surface modifiers.
In particular, polypropylene waxes or wax emulsions:
Control slip without adversely affecting scratch and mar resistance
Have good migration performance which results in an increased wax density on the coating surface
When formulating with polypropylene wax emulsions, it is crucial to adapt the particle size of the emulsion to the coating layer, in order to maximize the wax effects on the coating surface.
Wax emulsions are used for their slip resistance property in Floor Polish.
Effect of Wax on Abrasion Resistance
Abrasion resistance is produced by a combination of basic characteristics such as elasticity, hardness, strength, toughness, and in some cases, thickness.
Abrasion Resistance in Coatings using Wax Emulsions
It has also been established that a trend similar to that of slip additives exists between the wax hardness and the capability of the wax to resist rubbing damage.
Hard wax resists abrasion better than soft wax
Thanks to its mar, scratch and rub resistance properties, wax emulsions are used in a wide range of applications such as:
Architectural Coatings & Floor Polishes
Paper Film, & Foil Coatings
Inks, OPV’s & Primers
Metal Coatings
Waxes for Scrub & Mar Resistance
Wax Emulsions for Water Resistance
Water repellency or water resistance is another important property obtained or improved with waxes. As the name implies, this characteristic is the protection of a surface against water penetration (in liquid form).
Depending on formulation, the protection may be temporary or very durable and long-lasting.
Water Resistance in Coatings Using Wax Emulsions
Thanks to this property, wax emulsion is a key ingredient in a wide range of formulation for:
Wood Coatings
Architectural Coatings & Floor Polishes
Effect of Wax on Touch & Feel
Although coatings are usually applied to provide optical effects (color, gloss or matting etc.) or to protect a substrate, some applications also require the surface to have tactile properties.
In modern car interiors, coatings with a soft-feeling are applied on plastic substrates (mainly PVC) such as instrument panels and door handles to convey a “leather-like touch”, i.e. a feeling of smoothness and luxury.
With electronic devices (PCs, mobile phones, etc.) a “soft-feeling” effect created by specialized coatings is becoming increasingly more in demand.
By employing a coating that incorporates coarse wax particles, a rough and uneven surface is created at the microscopic level that is very similar to that observed with matting agents. Because tactile properties are largely dependent on the coating formulation, it is important that the wax particles protrude through the coating layer and this requires a particle size larger than the film thickness.
Thanks to this texturizing effect, wax emulsions are commonly used in Wood and Plastic Coatings.
Matt Effect Using Wax Emulsions
Providing wax dispersions have a particle size much higher than 1 µm, they will significantly reduce the gloss, by introducing micro-roughness on the coating surface. The so-created uneven surface will cause the light to be scattered.
The degree of the micro-roughness is determined by the number of particles present at the surface, which directly depends on wax properties such as:
Particle size and particle size distribution
Particle density
Amount of matting agent incorporated
Matt Effect using Wax Emulsion
Thanks to this matting property, wax emulsions are widely used in wide range of applications such as: Architectural, Wood coatings and Inks, OPV’s & Primers.
Waxes to Obtain Desired Matting Effect in your Application
Effect of Wax on Black Heel Marks
Black heel marks occur in a floor coating when the heel or sole of a shoe leaves residue on the floor after a shoe scuffs or scrapes the coating surface. Grocery carts, platform trucks, hand trucks and fork lifts can all produce black marks.
By reducing the coefficient of friction of the coating, carefully selected waxes such as HDPE will have better mobility across a coating surface improving the heel mark resistance.
Thanks to its heel mark resistance property, wax emulsions are used in Floor Polish.
Wax Types and Properties
Wax is a generic term that encompasses materials that have some specific properties such as:
Solid at 20°C, varying from soft / plastic to brittle / hard
A mp > 40°C without decomposing
A relatively low viscosity slightly above the melting point
Transparency to opaque, but not glass-like
Buffable under slight pressure
This includes:
Natural products based on C16 – C 36 Fatty Acids or
Some synthetic polymers with Mw from 700 to 10.000
Product Groups
Waxes and Wax Emulsions
Sub Product Groups
Wax Emulsions
Function
Wax Emulsion
Form of Delivery
Aqueous Emulsion
Chemical Description
Oxidized and Nonoxidized polyethylene wax emulsions / dispersions
Application
Hard Surface Cleaning
Institutional Cleaning and Sanitation
Vehicle and Transportation Care
Industrial Cleaning
WAX EMULSIONS
INDUSTRIES OF APPLICATION
Polish industry– floor polishes–car polishes– shoepolishes– furniture polishes
Textile industry
Paper and packaging industry
Paints and varnishes
Print ing ink industry
Coatings in general(e.g. metal,glass)
Hot melt
Anti-Fingerprint
Segmentation by Application
Printing Inks
Masterbatches
Adhesives
Rubber
Plastics
Rubber
Properties of waxes and wax emulsions
Synthetic waxes refer to pure waxes of oxidized polyethylene waxes or ethylene copolymers.
They are defined by their mechanical and physical properties.
The chemical constitution is mainly different.
Oxidized polyethylene waxes are of high hardness and higher molar mass.
Polyethylene Wax Emulsion Preparation
The preparation of polyethylene emulsion have three major steps: splitting, oxidation and emulsification.
Splitting: split high pressure low density polyethylene under temperature of 300~400℃ in the cracking furnance and we can get low molecular weight polyethylene.
During the splitting process, it is important to control splitting temperature and time to ensure characters and quality of wax.
Oxidation: low molecular weight polyethylene can be oxidized in high pressure reactor under temperature of 120~145℃ by putting compressed air or mixed O2/N2 gas then we can get oxidized polyethylene wax.
Emulsification: add KOH concentrated solution, emulgator and water to oxidic polyethylene and stir them in high speed under high temperature to make emulsion with required concentration.
Ionicity of polyethylene emulsion depend on its emulgator.
HOW IS WAX EMULSION PRODUCED ?
Oxidized waxes are solid at ambient temperature and have a melting point around 100°C.
Because of their high melting and setting points, Wax are products that can be easily emulsified under pressure in a closed system, for example in a low-pressure autoclave.
Nonionic-anionic emulsifier systems composed of fatty alcohol ether ethoxylates together with alkali hydroxide or amines have proved to be particularly effective.
Wax emulsions products are already emulsified waxes and for ready to formulate purposes.
The oxidized ethylene polymers provide the property of emulsification and thus wax emulsions can be prepared.
Factors to be Considered While Formulating Wax Emulsions
Wax emulsions are now well established and extensively used in various aqueous formulations. These ready-to-use wax emulsions can be easily incorporated into a formula by simple mixing.
The wax properties that have the greatest impact on formulation performances include:
The Melting Point: When curing is required, it is important that the wax has a lower melting point than the curing temperature. Thus, the wax can:
Considering Melting Point in Wax Emulsion Formulation
The Coating Thickness Layer: In order to maximize the wax effects, it is important to have the highest dried wax density to be at dried film surface.
Hence, the wax emulsion should have a particle size as closest as possible to the thickness of the coating layer
Sometimes a wax emulsion with a smaller particle size performs equally well, provided that the concentration is correctly adapted.
pH of the Wax Emulsion should be within approximately one unit of the system to which it is added. If necessary, the pH of the emulsion can usually be adjusted using aqueous ammonia or acetic acid.
pH of the Wax Emulsion
The Type of surfactant can also influence compatibility with the other components, as well as the overall formulation stability. Matching the emulsion charge with the coating charge enhances stability.
The Order of Component Addition: In water-based formulations, the order of component addition can be a critical factor in maintaining stability. Agglomeration can be prevented and overall stability maximized by adding the wax emulsion last. A further dilution of the emulsion with soft or demineralized water before incorporation can also reduce the shock.
The Regulatory Aspects of Waxes: If the emulsion is intended for food contact use (in a coating or in a package), both the wax and other incorporated additives (emulsifiers, antifoams, biocides etc.) must be in compliance with applicable statutes and regulations (FDA, BfR, European Directives, Kosher Certification etc.).
Determination of Wax content in a Formulation
Drying Optimization Strategies for Waterbased Systems
Mechanism of Action of Wax Emulsions
The Blooming Mechanism
Molten wax particles float (or bloom) to the surface. The coating cools and re-crystallization of wax particles takes place, forming a thin but continuous wax-enriched surface layer.
The softer the wax or lower the melting point, the more predominant the blooming mechanism becomes
The compatibility between the wax emulsion and other formulation components determines the wax migration rate
Blooming Mechanism for Formulating Wax Emulsions
The Ball Bearing Mechanism
In this case, solid wax particles migrate individually or protrude through to the surface.
By protruding slightly above the coating surface like ping-pong balls floating on a pool of water, they:
Act as a physical spacer, and
Prevent another surface from coming into close contact
Hard and high melting point waxes (HDPE, PTFE) operate using this mechanism under certain conditions. Both the particle density and the extent of protrusion influence the magnitude of the effect.
Once at the surface, the layer of wax particles has the ability to modify the Coefficient of Friction (CoF) of the substrate, imparting the desired characteristics. This explains why waxes are often classified as “Surface Conditioner Additives”.
Applications of waxes and wax emulsions in industrial applications
The use of waxes and wax emulsions is versatile.
In industrial applications waxes are used for a variety of applications due to their versatile properties.
APPLICATIONS OF WAX EMULSIONS:
– smoothing agents in textile finishing,
– anti-abrasion agents in water-based paints,
– rubbing fastness improvers in aqueous printing inks,
– rubbing fastness improvers in water-based coating varnishes,
– mold release agents in plastic and cast-metal processing.
WAX EMULSION is used in metal and plastic applications to provide temporary protection against corrosion and enhances the optical appearance of the surface.
WAX EMULSION is also usable as mould release agent.
In combination with nonionic and anionic emulsifiers WAX EMULSIONS are used in paper board coatings, overprint varnishes, polyurethane coatings, printing inks, textile finishing, besides others.
Polyethylene Wax Emulsion is an extraordinary coarse particle size emulsion.
This has been achieved by pressure emulsifying without alkali-application.
Because of the enlargement of the particles, the scuff resistance and anti-block is importantly improved.
Polyethylene wax emulsion helps you improve a multitude of processes and products.
Polyethylene wax emulsion helps to make your printing inks perform better, manufacture more easily, and maintain cost-effectiveness.
Polyethylene wax emulsion gives you a competitive edge in the marketplace that lets you increase profitability.
Wax emulsion is a kind of application form of common wax product, it is generally effective solid content in the emulsion of 10%～30% oil-in-water-type structure, by the emulsifying agent of wax and different sorts, performance and suitable conditioning agent, through emulsion reaction, made solid-true emulsion of the heterogeneous dispersion system of oil-water, generally according to purposes, select the kind of required wax product and emulsifying agent.
Wax emulsion does not need heating and melting while using, and has stable performance, exquisiteness, film forming is even, spreadability good, easily mix composite use with the aqueous solution or the milk sap of other materials, and nontoxic, non-corrosiveness, is convenient to storage, the advantage such as easy to use.
And with water, having replaced organic solvent, greatly reduced the cost of wax work, is that the various wax works including petroleum wax have been opened up Application Areas.
Be widely used in: the fields such as metal rust preventing, coating and printing ink, leather coating, glazing polishing, papermaking, weaving, building materials waterproof.
How You Can Use Polyethylene wax emulsion
Polyethylene emulsions are a family of synthetic waxes used as additives or modifiers in printing inks to improve mar and abrasion resistance, slip, control of rheology, and other properties.
In ink applications, a fluid is spread in a thin layer on a substrate.
The layer hardens into an adherent film through the action of any of a number of mechanisms.
You can use polyethylene waxes to modify the properties of both the applied fluid and the final film.
In the fluid, the polyethylene wax can control its rheology characteristics.
In the final film, the low molecular weight polyethylene wax can modify surface properties, such as coefficient of friction, mar and abrasion resistance, and gloss.
These property enhancements are important to ink manufacturers.
Important Characteristics
Liquid Polyethylene Wax is an emulsion of high melting point polyethylene wax and does not contain APE.
Liquid Polyethylene Wax is used as an additive in water based inks, coatings and over print varnishes, where improved slip, rub resistance, scratch resistance and/or block resistance are needed.
Liquid Polyethylene Wax can be used as an additive to paper coatings, wood coatings, metal coatings, overprint varnishes, floor polish and other markets where slip and hardness are required, without significant degradation of gloss.
Addition levels range from 3 – 10%, depending on application requirements.
Excellent compatibility with acrylics & styrene acrylics
Liquid Polyethylene Wax
Polyethylene Wax Emulsion
Ink and Coating Applications (lithographic and flexographic inks )
Polyethylene Wax Emulsion improves rub and mar resistance and slip characteristics may be secured by addition of 0.5 to 2% Liquid
Polyethylene Wax Emulsion improves flattening that is not subject to over-grinding may be obtained using Liquid Polyethylene Wax liquid polyethylene concentrations of about 3% because of its excellent resistance to solvents
Polyethylene Wax Emulsion improves slip characteristics may be achieved in stir-in ink applications where Liquid Polyethylene Wax liquid polyethylene can be used as substitutes for PTFE
Liquid Polyethylene Wax Polyethylene emulsion offers many important advantages and properties that can be utilized effectively in a wide variety of ink formulations.
The characteristics they provide let you make more efficient, cost-effective products that keep your customers satisfied
Wax additives have many areas of application.
They can be used, for example, to control the processability of products or to improve the properties of surfaces.
Waxes can be of a natural, semisynthetic or synthetic origin.
In these three groups of origin we can see that each wax basis has its own range of properties.
The fundamental properties are derived from the chemical basis, the melting point and the polarity of a wax.
WHAT IS POLYETHYLENE WAX (PE WAX) ?
Polyethylene wax is prepared by ethylene polymerization which is obtained from crude oil.
The polymerization in the manufacturing process is significant because physical properties get affected by the level of polymerization.
Polyethylene waxes are basically low molecular weight polymers of ethylene, produced via the polymerization of Ethylene.
This can be high pressure or catalytic polymerization (Ziegler-Natta, Metallocene).
Final properties like molecular weight, branching and crystallinity and therefore hardness, flexibility, melt viscosity and melting point differ per production method.
A completely different production method for producing PE waxes is by thermal degradation of Polyethylene polymers.
This results a well defined molecular weight distribution and therefore improved rheological properties.
This method also allows for the recycling of Polyethylene polymers into waxes.
PE waxes can be functionalized through oxidation, maleic grafting or copolymerization, of which oxidation is by far the must used method.
The reason for the controlled oxidation of PE waxes is to build in polar functionality in order to make them easier to emulsify.
Maleic grafting and copolymerization with polar functional groups (Acrylic acid or Acetate) is mainly done to increase the adhesion on polar substrates like glass, metal or paper.
Properties
Polyethylene wax is a white hard material and is nontoxic.
Polyethylene waxes are available as powder, flakes, and pellets.
Polyethylene wax Application of polyethylene is found in industries such as textile, food processing, and packaging, pharmaceuticals, oil and gas, paints and varnishes, cosmetics, leather, paper, printing ink, and coating.
Based on their molecular weights, they can be classified as emulsified and non-emulsified waxes.
The molecular weight (Mn) of PE waxes can vary roughly between 300 and 10.000 with melting points starting at 90°C and going up to 140°C.
Melt viscosities can also differ to a great extent starting from very low (<40 mPa.s) up to very high (around 90.000 mPas.).
Oxidized waxes have acid numbers starting at 14 going up to 30 and generally slightly lower melting points and melt viscosities due to the partial breakdown of the PE backbone during the oxidation process.
Non-oxidized PE waxes are water white, where oxidized PE waxes can be slightly off-white to light yellow.
The density of Polyethylene waxes can be controlled like this is done with high molecular weight polymers.
LDPE waxes have densities ranging from 0.92 to 0.94 whereas HDPE waxes range from 0.95 to 0.98.
HDPE waxes have higher melting points and melt viscosities than LDPE waxes.
Applications
Oxidized PE waxes are mainly used in water and solvent based emulsions and dispersions. For applications of wax emulsions please follow this link.
Non-oxidized PE waxes are used in the following applications:
Masterbatches
PVC
Hotmelt adhesives
Cable industry
Polyethylene wax is utilized in lubricants, candles, plastic additives, adhesives, coating, and cosmetics.
Properties of polyethylene wax are low solubility, heat resistance, and chemical resistance.
WHAT IS OXIDIZED POLYETHYLENE WAX ?
Oxidized polyethlene wax (Oxidized polyethylene wax)) be the oxidation products of low molecular weight polyethylene.
The cere glossiness that oxidized polyethylene wax emulsion forms is high, and hardness is large, good hand touch, and having can polishability, self-repairability, anti-scratch and wearing quality, is widely used in the fields such as leather, papermaking, weaving.
The oxidized polyethlene wax that field of textiles uses is conventionally take emulsion state as main.
OXIDIZED POLYETHYLENE WAX can be used as yarn sizing agent, improve flexibility and the oilness of fiber.
In noniron finish working fluid, OXIDIZED POLYETHYLENE WAX emulsion, can improve tearing brute force and the wear resistance of fabric.
Wax emulsion arranges cotton knitwear, can reduce the frictional coefficient of yam surface, reduces fluffing probability, thereby has greatly improved the anti-fluffing and anti-pilling performance of fabric.
Wax emulsion can also be used for softening and the water repellent finish etc. of fabric.
Industries served include:
Composite Wood—We provide specialty wax emulsions for oriented strand board (OSB), particleboard (PB) and fiberboard (medium and high density FB), hardboard, doors and moldings.
Packaging and Converting—Our specialized wax and wax/resin systems improve the manufacture of flat board stock and multi-ply paperboard using recycled pulp.
Coatings and Industrial Processing—Our waxes are used in coatings and in release applications for industrial processes.
Food-grade Applications—Our emulsions may be used as components in food packaging adhesives.
Please contact yourATAMAN representative to obtain specific approved uses for a product of interest.
Construction and Other Applications—We offer wax emulsions for use in paint and edge sealer formulations and in other applications
Composite Wood
Wax is used in the engineered wood industry for two principal reasons: water absorption and lubrication.
Wax helps control water absorption and thickness swelling in a finished board, especially along the edges.
This temporary water resistance is important when boards are left outside at a job site or exposed to water prior to and after installation.
To ensure dimensional stability, board manufacturers must meet strict accreditation requirements on thickness swell and water absorption.
During the manufacturing process, wax also lubricates the individual fibers or flakes that make up composite boards, allowing individual particles/flakes to be transported more easily from the blender through the press.
For OSB mills, our wax emulsions provide optimal performance at reduced cost compared to molten slack waxes.
Our products also meet the requirements of standard PB and medium density fiberboard mills.
Wax emulsions achieve equal or greater control over water absorption and thickness swell compared to standard products, while delivering low-foaming properties at a lower total applied cost.
Packaging and Converting
ATAMAN’s specialized wax and wax-resin systems for the packaging and converting industries help manufacturers of flat board stock and multi-ply paperboard—using recycled pulp—to achieve remarkable results.
These specialized emulsions impart water resistance, an improved surface finish and higher levels of opacity for white stock.
Coatings and Industrial Processing
ATAMAN maarkets wax emulsions for use in many coating and release applications for multiple industries.
Spray-on coatings and release agents for industrial processes aid in the cleanup and maintenance of equipment such as blenders and presses by creating temporary protective barriers between substrate and plant environment, and by preventing process materials from sticking during the manufacturing process.
Removal of these wax barriers is easily accomplished with hot water or steam, saving on costly cleanup time.
Food-grade Applications
ATAMAN markets several emulsions that may be used as components in food packaging adhesives—under the conditions defined by the U.S. Food and Drug Administration (21 CFR 175.105, 176.170, and/or 176.180).
Please consult the FDA regulations for other specifications and limitations which may apply.
Please contact your ATAMAN representative to obtain specific approved uses for a product of interest.
Construction and Other Applications
Our wax emulsions may be used in paints and edge sealers, providing a consistent neutral color and offering formulators maximum flexibility in pigmented applications.
Uses of our products include:
Industrial coatings
Fiberglass insulation
Tires
Pressure treated lumber
Our wax emulsions provide better distribution of the paraffin molecule to more effectively cover the dry furnish of chips, flakes or fines when compared to a molten wax application.
In addition, our products are nonflammable and emit less fumes and vapors.
Formulating with Wax Emulsions
Wax emulsions are now well established and extensively used in aqueous formulations such as coatings, inks and OPVs, textile and leather treatments, polishes, paper and cardboard coatings, etc.
These ready-to-use emulsions can be easily incorporated by simple mixing.
Their very fine particle size ensures an intimate and homogeneous incorporation within other ingredients of the formulation, maximizing the required effect(s).
Wax emulsions can be stabilized by either a steric mechanism (using with non-ionic emulsifiers) or by an electrostatic mechanism (using ionic emulsifiers, most often anionics).
Combining anionic and non-ionic emulsifiers gives the emulsion an optimum stability because wax particles are protected through both stabilization mechanisms, referred to as the electro-steric stabilization mechanism.
In addition to giving more flexibility in formulating, each stabilization mechanism has not only its own advantages and disadvantages but also significantly impacts on the overall formulation.
Wax properties that have the greatest impact on formulation performance include the chemical composition, the molecular weight, the melting point, the hardness and, in case of emulsions or dispersions, the particle size.
The end application and the coating application process (including the curing) also influence the wax selection.
When selecting a wax, it is important to consider:
Melting point.
When curing is required, it is important that the wax has a lower melting point than the curing temperature.
Thus, the wax can melt, migrate to the surface of the coatings, re-crystallize as the coatings cool and, eventually, form a continuous film for the blooming mechanism to occur.
Particle size and the particle size distribution should be slightly larger or at least equal to the film thickness.
This is particularly true if wax is hard (ball bearing mechanism).
Sometimes, a wax emulsion with a smaller particle size performs equally, providing that the concentration is correctly adapted.
In order to meet specific requirements, the particle size range can be controlled during the emulsification process.
pH should be within approximately one unit of the system to which it is added.
If possible, the pH of the wax emulsion can be adjusted by using aqueous ammonia or acetic acid.
Type of surfactant can also influence the compatibility with the other components, as well as the overall formulation stability.
Matching the emulsion charge with the coating charge enhances stability.
Order of component addition: In waterborne formulations, the order of component addition can sometimes be critical.
Agglomeration can be prevented and overall stability maximized by adding the wax emulsion last.
A further dilution of the emulsion with soft or demineralized water before incorporation can sometimes reduce the shock too.
Typical Effects Obtained with Waxes
Waxes are usually less expensive, more reliable and less often associated with side effects (e.g., recoatability) than other surface conditioner additives.
In most cases, a decrease in intercoat adhesion is related to the usage of extremely non-polar waxes like paraffins.
Furthermore, the obtained surface effect(s) generally last longer because wax particles migrate very slowly to the surface.
Anti-Blocking
Anti-blocking is a term defining a non-stick situation between two surfaces, their resistance to adhesion under the influence of temperature, relative humidity or even pressure fusing the surfaces together.
A very well-known example of a blocking situation is when a freshly painted window frame is too rapidly closed.
Sometimes, it can be very difficult to open the window again.
Factors affecting blocking include the coating surface-free energy, topography of the coating, the hardness and the Tg of the polymer.
HDPE, paraffin and carnauba waxes are typically used to counteract blocking.
Anti-blocking agents are also very useful for any type of items that are coated, dried and immediately stacked or rolled up for storage or shipment.
Slip Aid
Slip represents the ability of two surfaces to glide over each other without causing any mechanical damages.
Good slip properties require the slip additive to concentrate at the surface during and immediately after application and curing.
A very interesting evaluation study with microcrystalline waxes clearly demonstrated that the harder the wax, the better the slip properties.
This can be explained by the fact that a softer wax would tend to be more easily liquefied, and as a consequence, there remains less of it in a solid state to impart slip.
In other words, the harder wax would have a relatively higher proportion of crystals in the solid state to impart slip.
Abrasion Resistance
Abrasion is a phenomenon caused by the mechanical action of rubbing, scraping or erosion.
Since intimately related to scratching and slip, it is not surprising that many slip aids also function as mar and abrasion-resistance additives.
Abrasion resistance is actually a combination of basic factors such as elasticity, hardness, strength, toughness, and in some cases, thickness.
Using the same series of microcrystalline waxes but with different hardness values, a similar trend was also established between properties of hard waxes and the capability of the wax to resist rubbing damage. Hard waxes resist abrasion better than soft materials.
The same trend was observed when comparing the behaviour of soft microcrystalline wax with hard PE and PTFE materials in the abrasion resistance of an ink formulation.
Furthermore, this study also demonstrated that:
Both PE and PTFE waxes function by the ball bearing mechanism, while the softer microcrystalline wax works via the layer (bloom) mechanism.
If the particle size of the wax is similar or slightly larger than the thickness of the printed ink film, the effectiveness of the wax is maximized.
Water Repellency
Water repellency, or water resistance, is another important property obtained with waxes.
As the name indicates, it implies the protection of a surface against water penetration.
The protection can be temporarily only (water resistance or repellency) or over a nearly infinite period of time (waterproof).
Also, water resistance generally implies the resistance to liquid water, whereas moisture resistance means the protection against water in a gaseous or vapor state.
Usually, paraffin waxes, including scale waxes (a lower refined paraffin grade containing up to 5 % oil), perform very well, particularly on porous surfaces.
The oil penetrates easily within the pores and fissures, rapidly imparting a very hydrophobic character to the treated surface.
Texturizer
Although coatings are usually applied to provide optical effects (colour, gloss or matting etc.) or to protect a substrate, some applications also require the surface to have tactile properties.
In modern car interiors, soft-feeling coatings are applied on plastic (mainly PVC) substrates like instrument panels and door handles, and convey a “leather-like” touch, i.e., a feeling of smoothness and luxury.
In coatings for electronic devices (PCs, mobile phones, etc.) a “soft-feeling” effect is demanded too, especially in Asia.
By incorporating coarse wax particles, a rough and uneven surface is created, very similar to that observed with matting agents.
Because tactile properties depend on the coating formulation, it is important that the wax particles protrude through the coating layer, hence require a particle size larger than the film thickness.