Screen printing hot melt coating machine
A screen printing hot melt coating machine applies molten adhesive through a stencil screen onto a substrate. This method is derived from textile screen printing and is used when thick, high-resolution patterns (e.g., dots, lines, logos, grids) of hot melt adhesive are needed. Typical coat weights range from 30 to 500 gsm, much thicker than slot die or gravure. The machine consists of a flatbed or rotary screen, a squeegee blade, a hot melt supply system, a heated substrate platen (for flatbed), and a cooling section. The adhesive is forced through the open mesh areas of the screen by the squeegee, transferring directly to the substrate. This technique is particularly valued for making anti-slip coatings on carpet or rugs, applying gripper dots on gloves or sportswear, producing thick-film adhesive for textile bonding, and creating embossed or textured adhesive layers.
The working principle: For a flatbed screen coater, the substrate (e.g., fabric, nonwoven, foam) is placed on a heated table. A screen (a metal or polyester mesh with a stencil pattern) is lowered onto the substrate. Hot melt adhesive, maintained at 100-200°C in a heated trough, is poured onto the screen. A squeegee (metal or heat-resistant polyurethane) moves across the screen, pressing the adhesive through the open mesh areas. The adhesive transfers to the substrate, and the screen is lifted. The coated substrate then moves to a chill plate or cooling tunnel to solidify the pattern. For a rotary screen printer, a cylindrical screen rotates continuously, and a stationary squeegee inside forces the adhesive through the screen onto a moving web – this allows higher speeds (10-50 m/min) compared to flatbed (1-5 m/min).
Hot Melt Coating Machine - Hot Melt Adhesive Coating Machine
Typical applications: 1) Anti-slip coatings on industrial floor mats, stair treads, and carpet tiles – thick patterns of polyamide or polyurethane hot melt provide grip. 2) Gripper dots on medical gloves or sports gloves – small, raised dots for better handling. 3) Textile lamination – applying adhesive as discrete dots to bond two fabric layers while maintaining breathability and drape. 4) Bra pad manufacturing – thick, soft adhesive patterns for comfort. 5) Heat transfer labels – thick adhesive for embossed logos. 6) Automotive interior – bonding foam to vinyl with patterned adhesive to allow flexibility. The ability to vary pattern thickness (by screen mesh count and emulsion thickness) is a unique advantage.
Key parameters: Screen mesh count (threads per cm) determines the open area; typical counts from 10 to 60 mesh. Lower mesh gives thicker adhesive deposits. Emulsion thickness (10-500 microns) defines the maximum pattern height. The squeegee durometer (hardness) and angle affect how much adhesive is forced through; a harder squeegee (80 Shore A) and steeper angle (60°) give lower deposit. The adhesive viscosity should be 20,000-200,000 cP – higher than for spray, to prevent dripping through the screen. Temperature control is critical: the screen and squeegee must be heated to prevent adhesive from freezing mid-process. Some machines use infrared heating above the screen.
Advantages and limitations: Screen printing provides extremely precise pattern definition and thick layers that other methods cannot achieve. It allows variable pattern height for 3D effects. However, it is a batch process (flatbed) or low-speed continuous (rotary) compared to slot die. Screen life is limited; metal screens last longer than mesh screens but are more expensive. Cleaning is labor-intensive because hot melt must be removed from the screen before it solidifies. Maintenance involves regular screen re-tensioning and squeegee replacement. When selecting a screen printing hot melt coating machine, consider the maximum substrate width (flatbed up to 2m, rotary up to 3m), pattern complexity, and production volume. For high-volume, simple patterns (e.g., uniform dots), rotary screen is preferred. For small batches or complex logos, flatbed with CNC screen registration is suitable. This technology is niche but essential for applications requiring thick, patterned adhesive bonds that combine function and aesthetics.
