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The newest metallic powder coating bonding process

Preface
Powder coatings Bonding process, also called thermal Bonding technology, is under a certain temperature, the metallic pigments adhesion on powder coating particles, create a coating of metallic effect. Traditional bonding mixer is the use of plastic industry for some improvement high mixing equipment, temperature control by friction heating way, short of good binding effect, this paper introduces a new bonding process where special design and intelligent temperature control device can mix for a long time under 65-70 ℃ without caking, it provides very good binding effect.

Advantages for bonding process in metallic powder coating
1. Developing brand-new environmental coatings
Nowadays environmental requirement is no longer a concept and sense, but a regulation and compulsion. The VOC paints with liquid metal effect will be gradually eliminated from market, and the bonding powder coatings complying with environmental requirement and exhibiting metal effect will play an important role of substitution in this transformation. In the bonding powder coatings the content of metallic pigment can be increased to 10% or higher, and the coating effect can completely rival the liquid paints. One who is the first to master this bonding process and technology is the winner in this transformation.

2. Eliminating quality problems of coatings
The bonding process can eliminate the following quality problems existing in conventional dry mixing process:
Problems in coating: poor leveling
Existence of sand
Existence of chromatic aberration
Liable to discolor
Problems in spraying: poor powder absorption
Liable to burn out spray gun
Useless recovery powder

3. Reducing cost of production
For metal coatings with the same effect, the metallic pigment in ingredient with bonding process can be approximate 10%~20% lower than that with conventional dry mixing process, enabling reduction of the cost of ingredient. With adoption of bonding process, recovery powder can be reused so as to save resources and reduce wastes.
In spraying the rate of finished products is increased so as to reduce spraying expenses.
Thanks to environmental coating, high amount of environment related costs are not required in production and application.

II Traditional bonding mixer of powder coating is the use of plastic industry high mixing equipment, some improvement on friction heat production, temperature rise to about 50 ℃ immediately feeding. This technology has some disadvantages
1. It is difficult to control in production process, often produces a subscription fee
2. Because the temperature is not enough, metallic pigment adhesive effect is poor
3. Bonding mixing time is not enough, not fully mixed with adhesive
4. There is a big quality difference between production batches
5.It can't produce high flash coatings because the metal paint is damaged by high speed friction heating process, ,
6.Metallic pigment were broken and caused metallic pigment dosage increased

III A new state on bonding process
In 2011, we launched a new bonding process which can make the powder coating materials in higher temperature (65-70 ℃) for a long time (3-5 minutes) mixing through to the equipment of special design and intelligent temperature control technology. It has the following advantages.

1.The bonding process is conducted at constant torque and shear force so as to avoid damage of high shear force to metallic flake pigment in conventional bonding machines
2.The bonding effect is very good by high temperature long time mixing
3.The entire process by the computer intelligent control
4.Material temperature can be controlled precisely during bonding
5.Material sticking will not happen during production..
6.Product batch quality stability
7.The bonding system takes automation of production process into full account.

IV Features for this process
1．Effectiveness of bonding
Really effective bonding process is embodied in uniform mixing between basic material and metal pigment above Tg point for long time. The Wisdome bonding system can guarantee bonding mix of general powder coatings for 3-5min without caking at 65℃-70℃ to as to achieve real bonding effect, and this is absolutely benefited from its professional design and precise control.
A． Inner wall, lid and discharge of the bonding machine are made of special steel, which is mirror polished after special treatment, so material sticking will not happen during production..
B．The distance between mixing tools and container wall is especially specified to T avoid dead spaces in mixing area..
C．The mixing tools are designed into unique multi-layer structure, and the angles and motion curves of mixing tool on each layer are different. Moreover the mixing tools have self-cleaning feature so as to guarantee uniform mixing of all materials.
D．The deflector is installed through the container lid and is adjustable in angle to guarantee the optimized flow of material.
E．Intelligent temperature control system enables precise control of material temperature during bonding process.
2．Intelligence of process
The whole process is under intelligent judgment and control of computer system, as a result, material temperature can be controlled precisely during bonding. Moreover, the bonding process is
conducted at constant torque and shear force so as to avoid damage of high shear force to metallic flake pigment in conventional bonding machines， therefore, coatings with high-flash effect can be produced.
3．Reliability of equipment
In Wisdome bonding system the driving system adopts German SIEMENS motor and SIEMENSfrequency converter, the control system adopts SIEMENS PLC and SIEMENS touch screen, low-voltage electric appliances are from Schneider, and pneumatic system is from Taiwan ARTIC.The whole configuration and reasonable design guarantee reliability and safety of the system.
4．Safety of production
A．During running of the whole system, oxygen monitoring and nitrogen protecting systems prevent the risk of dust explosion.
B．All mechanical parts should be grounded reliably to guide away generated static immediately. C．At running and connecting parts of machinery sensors and interlocking mechanisms are set to guarantee reliability of connection and safety of operation.
5．Simplicity of operation
The Wisdome bonding system takes automation of production process and simplicity of operation
process into full account.
A.The system can save various production process parameters of products for real-time callout to perform production, or can be networked with PC for centralized control and management.
B. The whole operation is fulfilled just by one key, and nitrogen detection, heating up, bonding, cooling and feeding processes are carried out automatically without operations by personnel.
C. Production modes are divided into manual mode, trial production and mass production mode with convenience for trial and production
D. The discharge is designed in swing-way, easy to clean machine change type.
V Technical data
三．TYPE HM350/KM1200 HM200/KM800 HM10
HM volume 350L 200L 10L
KM volume 1200L 800L ——
Batch loading capacity 100KG 60KG 3KG

Production per hour 400KG 240KG ——
Operating voltage 380V，50HZ 380V ，50HZ 380V ，50HZ
Motor drive way frequency
controlled
frequency
controlled
frequency
controlled
Control mode PLC PLC PLC
Temperature sensor PT100 PT100 PT100
Water connections R2” R1” R1/2”
Nitrogen
connections
R1/4” R1/4” R1/4”
Air pressure 0.4-0.6MP 0.4-0.6MP 0.4-0.6MP
Paint color RAL9010
RAL5013
RAL9010
RAL5013
RAL9010
RAL5013

TESTING METHODS FOR POWDER COATING

These test methods are designed for two purposes: Performance reliability and Quality control

1/ GLOSS TEST (ASTM D523)

Test coated flat panel with Gardner 60 degree meter. Coating shall not vary 5% from data sheet requirements on each material supplied

2/ BENDING TEST (ASTM D522)

Coating on 0.36 inch thick phosphated steel panel shall withstand 180 degree bend over 1/4" mandrel. No crazing or loss of adhesion and finish at the bend be able to removed with 3M Y-9239 tape.

3/ HARDNESS TEST (ASTM D3363)

Faber Castell wood pencils are used in hardness of 1, 2, 3, 4. Coating shall show no marks from 2H pencil.

4/ CROSS HATCH ADHESION TEST (ASTM D3359)

Scribe parallel lines through coating to substrate, 1/4" apart a distance of one inch. Scribe anoth set of parallel lines 1/4" apart and perpendicular to the first set. Apply any sticky tape then remove quickly. Results should be no lifting of the cured powder between scribe lines.

5/ CHEMICAL RESISTANCE TEST (ASTM D1308)

Place approximately 10 drops of test solvent, consisting of 95% by weight toluene and 5% by weight Methal Ethly Ketone on the surface of the coating. Allow to stand for 30 seconds. Wipe off with soft, dry cloth. Coating shall show no more than a slight circular mark.

6/ IMPACT TEST (ASTM D2794)

Coating on 0.36 inch thick phosphated steel panel shall withstand impact with 1/2" Gardner impact tester ball at 26 inch pounds direct and reverse. No grazing of loss of adhesion. Finish shall not be able to removed at impact area with 3M Y-9239 tape.

7/ SALT SPRAY CORROSION TEST (ASTM B117)

Use a 5% salt solution at 92-97 degrees F in a sealed weather cabinet. Scribe X in steel Zince phosphated test panel to bare metal. Inspect every 24 hours. End test and toto hours after 1/4" creepage from scribed area. Creepage shall not exceed 1/4" in either direction from scribe line after 500 hours exposure.

Another group of powder coating materials that make up about 5–10 percent of the powder market are thermoplastic powder coatings. Thermoplastic powder coatings differ from thermosetting powder coatings mainly in the fact that no chemical reaction occurs during curing. Thus thermoplastic materials can be reclaimed and re-melted to be applied again.

Thermoplastic powder coatings are most frequently applied by fluidized bed application—that is, dipping parts into a container of powder coating that is fluidized by a flow of air blown up through the container. These types of coatings have a much coarser particle size than thermosetting powder coating and are therefore normally not sprayed with powder coating guns.

After application, thermoplastic powder coatings melt in the curing oven and develop into a solid film upon cooling. Repair of thermoplastic powder coatings is relatively easy and can be accomplished by simply re-heating and re-melting the coating. As mentioned, no chemical reaction occurs during curing, allowing the powder coating to be re-melted. One of the drawbacks of thermoplastic powder coatings is relatively low surface hardness.

Most applications for thermoplastic powder coatings are in aggressive chemical environments. One particular area of use is valves. Following is information on some of the more common thermoplastic powder coatings used in today’s market:

Nylon-based powder coatings. Nylon is still the most common thermoplastic powder coating because of its resistance to abrasion and chemical exposure. Applications can be found in medical instruments, where cleaning by autoclave is required, as well as dishwasher baskets and so on.

Polyolefin-based coatings are based on polypropylene or polyethylene resins. They have a soft, almost waxy feel. Adhesion is an issue for these coatings even on sandblasted surfaces, and outdoor application is not recommended. Copolymers are used to improve adhesion and, with the correct primer, applications can be found in the pipeline business as insulation coatings.

Vinyls. PVC-based coatings have a good water resistance and, with a proper primer, can be used in such applications as dishwasher baskets. Surface hardness is limited, and the surface scratches easily.

PVDF (polyvinylidene fluoride) resins are normally used in liquid systems to create very high-performing architectural coatings. In powder coatings, PVDF resins are mainly used in applications requiring very high chemical resistance. Valves, pipelines and other equipment in the chemical industry are often coated with PVDF powder coatings. A primer is recommended for adhesion.

Corona Charging

This kind of charging is made by pushing the uncharged partilces (powder) through an electric field created by high voltage circuit. The powder is then be charged and trend to the grounded objects.

Advantages

1) Strong electrostatic field results in rapid charging and deposition

2) Electrostatic fieldlines support the powder particles to move towards the work piece

3) Simple repairs of the powdered surface are possible

4) Light, robust spray gun

5) Accepts different types of powder materials and particle sizes

6) Film thickness can be simply changed by voltage variations

7) Simple construction is suited for fast colour changes

Disadvantages

1) Redundant ions generate a self-limiting effect

2) Strong fieldlines lead to Faraday effect (irregular coating, corners and crevices are not properly covered)

3) These effects can be reduced or eliminated respectively by voltage changes or use of anti-ionisation rings (to reduce Faraday and Orange peel effect)

Tribo Spray

In Tribo charging, the powder is charged by friction. Particles (powder) moves through the spray gun will rub against the media in the gun and get charged.

Advantages

1) No Faraday effect; deep crevices, corners and hollow spaces can be better penetrated

2) Powder can be better directed by the use of directional finger sprayers and aerodynamics

3) Less, if any, fat edges on the coated surface

4) Uniform coating

5) Very good automation possibilities

6) No high voltage generator required

7) Higher film builds possible without back-ionisation

8) Higher productivity by closer arrangement of objects

9) Better flow; practically no orange peel effect

Disadvantages

1) Performance is strongly influenced by uncontrolled air-streams

2) Special powder is necessary; formulation must be adapted to the Tribo charging process

3) Particles smaller than 10 microns are difficult to charge

4) Powder deposition slower than for corona

5) Colour changes take a long time

6/ Charging dependent on atmospheric moisture

7// The quantity of powder that can be charged from tribo guns is less, more tribo guns are required to coat.

There are 2 basic stages of creating a desired coating effects in the Sublimation technique:

Surface treatment and Coating,

A pretreatment of chemical conversions applied to a raw aluminum surface is required prior to powder coating, this will help creating thin layers of amorphous oxide to protect the substrate. The next step is using of the electrostatic guns to apply a 60~80 micron film layer which is cured at 400⁰F in approx 20 minutes, Polymerization is then performed. Such base coat is conductive to creating sifficient hardness on the finalized product. The coated film layer also protects aluminum against factors like Weather, Corrosion, Abrasion, Light and Humidity.

Decoration

In this stage, a preprinted film transfer which containing organic photosensitive pigments and cellulose resin will have to be properly wrapped around the product and then set on the surface of a trolley. A vacuum suction system removes air and in turn, produces a perfect thermo print. In order to let all the desired effects “transit” on the target subtrate, the trolley will be placed within a specialized oven, affecting the decoration by converting ink pigments from solid, into gas and back again to solid within the paint layer. In the last step of the powder coat process, the film is removed upon cooling.

POWDER COATING FOR HEAT TRANSFER (SUBLIMATION)

WHAT IS POWDER COATING?

Powder coating is an advanced method of applying a free-flowing and dry powder on the substrate without solvent requirement. The powder is charged and adhere on the grounded surface until it is heated and fused into a form coating layer in the curing oven. The finished coating gives uniform, durable and attractive appearance surface.

WHAT ARE THE ADVANTAGES OF POWDER COATINGS?

• 99% used powder is recyclable.
• Giving superior coating film properties.
• A wide range of colors and surface effects is available.
• Easy performance without much technical skill requirement.
• VOCs free & Environmentally friendly.
• Curing time is much shorter than ever.
• various metal and non-metal substrates and can be applied
• Energy saving.

ARE POWDER COATINGS CLASSIFIED AS DANGEROUS GOODS?

Dangerous Goods are the articles or substances which are capable of posing a significant threat to health, safety, property or the environment and which are classified as per the IATA Dangerous Goods Regulations.

Powder Coatings are not classified as dangerous goods. There are no solvents in powder coatings which simplifies the transport and storage of powder coatings.

POWDER COATING APPLICATIONS

HOME APPLIANCES

In the home appliance industry, powder coatings are well recognized as being a high quality finish for both major and minor applications. In the appliance finishing industry, the Advantages of high corrosion resistance with single coat application has resulted in powder coatings being used on a wide variety of electrical appliances, including; air conditioners, clothes dryers, cookers, dishwashers, fans, freezers, microwave ovens, rice cookers, refrigerators, stereo components, television components, video components, washing machines, water coolers. In addition to the major appliances noted powder coatings are also widely used for smaller appliances such as toasters, irons, can openers, juice extractors, food processors, vacuum cleaners and floor polishers.

AUTOMOTIVE COMPONENTS

Although powder coatings are not yet widely used on auto bodies, they are finding growing applications on components for both interior and exterior applications. Current applications in the automotive industry include: air filter housing, alloy road wheels, brake calipers & components, bright trim molding, bumper bars, door handles engine blocks-iron & alloy, mirror housings, motorcycle frames, oil filter housings, rocker covers, seat frames, steel wheels assemblies, stereo system, components suspension systems, underbody primer, windscreen wipers.

FURNITURE

The furniture industry is a major market for powder coatings. Powder coatings are used extensively on both commercial and domestic furniture for both their performance and for their appearance. The performance characteristics of powder coatings which make them so suited to the furniture industry include Toughness, Hardness, Corrosion resistance

ARCHITECTURAL

Powder coatings have developed a strong position in the architectural industry as a coating for aluminum profile, cladding and other building components.

ELECTRICAL AND ELECTRONIC INDUSTRY

Computer casings, computer components, encapsulation, telecommunications equipments.

The applications of Powder coatings are continuously being expanded nowaday, it is easy to find some specific powder for UV cured, MDF or non-metal substances before long. Various special coating effects and properties are being developed rapidly and might comes to serve the industry very soon ie. Stainless steel like, Super high heat resistance, etc.

MAX Powder Coating started when the founders recognized the need for finishing industry that utilized current technology. We are a complete Turnkey Finishing Provider dedicated to supplying pretreatment chemicals, coating powder, designing, engineering, fabricating and installing the latest technology and most energy efficient systems available. We provide Total Turnkey Solutions.

Our unique formulated powders allow for significant efficiencies in powder coating equipment, production, and installation resulting in increased system value. We serve our customers from engineering through system start-up by providing custom design, engineering, fabrication, and installation of complete, state-of-the-art finishing supplies.

Working against time in the finishing industry, we have been earning expert experiences that help us confidently support our customers. From initial consultation to system start-up, our team approach coordinates pretreatement, powder, and application equipment suppliers that are best matched for your project. Our customer focused sales, engineering, and project management teams work closely with you to integrate technologies that meet your finishing needs, maximize productivity, and fit with your budget considerations. Even after sales, we offer ongoing customer support and technical assistance.

SUSTAINABILITY

We pledge ourselve to provide customers with reliable quality powder coating for their finishing job, and we believe the key of quality product is not only just from good materials, adequate facility but the people and how they manage it. That's what Max is focussing on.

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