Hot Melt News

Hot melt gun modules are high pressure fluid valves. These are typically attached to heated hot melt gun manifolds for quick and easy removal to minimize line downtime when they do not shut off completely. Incomplete shut off results in extended patterns, leaking, dripping or the “stringing” of the hot melt adhesive.

In these modules a needle valve lifts off the internal seat with compressed air or electric coil. It closes with compressed air or a spring. This action stops the hot melt flow between the needle tip and the needle seat which then flows into and through a nozzle tip onto the
substrate. When the needle is forced down against the seat with compressed air or compressed spring the flow of adhesive is, or should be, stopped completely. Adhesive in the typical hot melt system can be pressurized to over 1000 psi making the intimate seating of the needle
and seat critical.

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Hot Melt Modules - Leaking, Dripping and Stringing - by Pierce Covert,
Glue Machinery Corporation
www.gluemachinery.com

Modules used for the application of hot melt are valves that allow adhesive to flow through nozzle tips and onto substrates.

Modules are attached to heated blocks called guns or applicators. These modules are actuated pneumatically into “On” position by a high speed solenoid or magnetic coil. This lifts the internal needle valve off the needle seat and high pressure hot melt flows.

These modules are turned “OFF” by pneumatic solenoid or internal spring forcing the needle valve against the needle seat stemming the flow of hot melt.

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What are Hot Melt Modules? - by Pierce Covert,
Glue Machinery Corporation
www.gluemachinery.com

Right angle nozzles for the application of hot melt are a standard in all packaging industries. These nozzles attach to a module or valve and are for the redirection of the adhesive as the nozzle has the ability to swirl 360 degrees.

This swivel capability allows customers to move the adhesive pattern rather than readjusting the position of the gun. This is especially important in slow speed case sealing operations where the customer needs to apply hot melt to a variety of package sizes. A simple nozzle adjustment allows for pattern repositioning.

Typically, these nozzles are used by manufacturers of the packaging lines because they allow for easy repositioning of patterns and one applicator is less expensive than multi-module guns.
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Right Angle Hot Melt Nozzles - by Pierce Covert,
Glue Machinery Corporation
www.gluemachinery.com

The debate regarding the use of tape versus hot melt adhesive continues to this day. Both products offer advantages over each other.

Following are the features that should be taken into account when choosing between the two:

Cost
- Hot melt adhesive typically is 1/2 to 1/3 the cost of packaging tape.
- Hot melt systems are more expensive than tape machines to purchase and operate.

Production Speeds
- Hot melt is used extensively for high speed case and carton assembly.
- Hot melt systems can run continuously
- Tape is used for slower intermittent case erecting and sealing.
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Hot Melt Adhesive versus Tape for Case Erecting and Sealing
- by Pierce Covert, Glue Machinery Corporation

Credit cards and gift cards are typically attached to paper substrates using removable adhesive. This process has been offered to industry for 25+ years. With the massive increases in the numbers of credit cards and gift cards sent everyday - the speed and precision of this process is very important.

For many years latex water based adhesive was the standard adhesive used to attach cards to substrates. Latex removable adhesives have decreased in use because of the inconsistent bonds provided and the difficulty maintaining the systems that apply these adhesives. Latex adhesive under pressure tends to clot within the systems…

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Complete Article>>

CreditCardAttachment-RemovableAdhesive - by Pierce Covert, Glue Machinery Corporation www.gluemachinery.com

According to the PSTC standard test condition, appendix A, standard conditions are a temperature of 23 ± 1 degree C and a relative humidity (RH) of 50 ± 2% at that temperature, allowing for short term fluctuation of 23 ± 2 degrees C and RH as 50 ± 5%.

The above standard test condition is rather difficult to achieve in some hot and humid counties, such as those countries in southern Asia and China. As a result, pressure sensitive adhesion test is commonly carried out at 25 ± 2 degrees C and RH of 65 ± 5%.

In many of the previous articles, the effect of test temperature on adhesion performance has been widely discussed. The rheological property, such as G’ and Tan delta, of HMPSA (Hot Melt Pressure Sensitive Adhesive) is affected by… Read Complete Article>>

Humidity and Hot Melt Pressure Sensitive Adhesives
-by Pierce Covert, Glue Machinery Corporation

A water repellent PP film or foam panel is used inside every single auto door. The PP film or foam panel can prevent water from entering into an auto interior during raining or car washing. Conventionally, butyl rubber-based sealant is used to bond these PP films or foam panels onto the door body. Butyl rubber-based sealant does offer excellent moisture impermeability. However, its low cohesion characteristic is not favorable for repositioning purpose in the after service market. The PP film or foam panel should be removable and re-mountable easily without scarifying moisture impermeability after repairing.

Hot melt pressure sensitive adhesives (HMPSAs) have been introduced to this application area in the past few years. Since SBC-based HMPSA is much more elastic than butyl rubber-based sealant… Read Complete Article>>

Foam-able HMPSA Used on Foam Panels for Automobile Doors
- by Pierce Covert, Glue Machinery Corporation

The non skid feature is desired for many consumer products such as mouse pads, area rugs, table mats, and the standing parts of some furniture and appliances. To generate this non skid feature, both rubber and plastic foam are commonly used for this specific application. Most vulcanized rubber films require an adhesive to adhere them onto other materials. Plastic foams can be coated and adhered to certain materials in situations without adhesives. However, pre-foamed plastics also require certain adhesives for laminating purposes.

Thermoplastic compounds including some tackifying resins may provide sufficient hot tack to adhere on certain materials at elevated temperature and then… Read Article>>

Non Skid Hot Melt Compounds
- by Pierce Covert, Glue Machinery Corporation

SWF has produced quality box erectors for poultry and other industries for many years. These erectors typically come with an antiquated hot melt “star wheel” hot melt application system on each side of the machine.

As a blank box advances -it quickly passes the star wheels. The star wheels rotate and create fluid pressure that extrudes the adhesive onto the box. While extremely simple this method of application has its limitations. First, the wheels must make intimate contact with the box which can be difficult. Secondly… Read Article>>

SWF Case Erector with Star Wheel Hot Melt Systems
- by Pierce Covert, Glue Machinery Corporation

Corrugated boxes are used worldwide as the primary package for most products.

For the primary assembly or erecting of these boxes, and the sealing of flaps with hot melt, the following steps must be taken:

1. Open and square the box
2. Fold the minor flaps down
3. Apply hot melt to minor or major flaps
4. Compress the major flaps
5. Flip the box and compress from the inside of the box

In the erecting process most minor flaps tend to deflect away from the major flaps on compression which can create weak bonds between these flaps. Also, operators may use far too much hot melt to extend the open time of the hot melt to allow for the flipping of the box and recompression from the inside of the box.

An effective method of improving the manual erecting of boxes with hot
Melt is to provide your operators with a mandrel stand with a box drop pin. Operators simply slide the box over the mandrel, fold the minor flaps so that they contact the top of the mandrel plate, apply the adhesive and compress the major flaps.

This method of case erecting produces better boxes faster with less hot melt. This method of case erecting also dramatically improves the ergonomics.

- by Pierce Covert, Glue Machinery Corporation