According to Freedonia Group, U.S. filter demand will rise 3.6% annually to $14.8 billion in 2018. Filters are comprised of several parts assembled together and are used in a variety of markets. Let’s take a closer look at the various filter assembly components and adhesives’ role within their assembly.
Pleated Filter Media
Pleated filter media are an efficient and cost-effective way to eliminate airborne particles. This media is assembled using the following components:
- Edge Seal Pleating
- Pleat Stabilization/Pleat separation
Pleated media are folded like an accordion. This, in turn, maximizes the surface area of the filter media, allowing for the most contaminated air possible to travel through the media without having to force it through with high pressure. The smaller the surface area, the tougher it is to push bulk air through the filter and catch more particles.
In edge seal pleating and pleat stabilization, adhesive beads are applied toward the outside edge of the material to provide an air seal. Types of adhesives used here include:
Additionally, the adhesives can be either solid or foamed.
While foamed adhesives are lighter in weight, more flexible than solids and require less adhesive due to density reduction of the adhesive bead, all three adhesives offer benefits. These include:
- Low cost
- Ability to bond to media
- Fast setting capabilities
Radial Pleated Filter Media
Radial pleating is when the filter media is wrapped into a cylindrical form. This component is assembled using side seam bonding to attach the beginning and end of the pleated filter media together.
Adhesives are also used in the assembly of this component to bond the two ends of the cylindrical form together. For example, hot melt polyamide adhesives now replace metal clips in radial pleated filter media. Additionally, polyamides are usually used due to their short open time and high heat resistance.
Molded End Cap
Molded end caps form fit around the base of pleated filter media, potentially eliminating pleat separation beads.
In particular, adhesives are used in the end cap molding assembly component to hold the media in place. These adhesives are:
Wound Filter Elements
Wound filter elements are tightly, radially wrapped filter media. Because they are tightly wound, multiple layers are created, making the media very efficient.
For this component, multiple adhesive beads are applied to ensure an even separation of the media layers. This means that the adhesive creates gaps in the media, so air has a chance to travel through the filter media. If there is no gap, then it will be difficult for the air to penetrate fully through the filter media.
In particular, adhesives are used in:
- Edge Sealing
- Layer Separation
Polyolefin adhesives in particular work well for this component. Polyolefins:
- Are rather flexible
- Have higher heat resistance than other options
- Bond to polypropylene media
- Have low odor/low VOC compared to other options
For more information on filter assembly components and adhesives’ role within their assembly, call 800-7-BOSTIK. Stay tuned for an upcoming blog post on filters and adhesives for various markets.