Technological breakthrough of environmentally friendly glue in paper bag machine production: from difficulty to efficient application

Release time：2025-08-13 Classification：Knowledge

As the global plastic ban continues to advance, demand for eco-friendly paper bags, a key alternative to plastic packaging, has exploded. As a key step in paper bag production, gluing technology directly determines a bag's strength, environmental friendliness, and production efficiency. Traditional solvent-based glues, due to their harmful volatiles, are being replaced by more environmentally friendly options like water-based glues and biodegradable hot-melt adhesives. However, eco-friendly glues face a number of technical bottlenecks in high-speed, automated paper bag machines, including slow drying, insufficient initial tack, and poor equipment compatibility. This article will delve into the nature of these challenges and innovative solutions for the industry.

1. The problem of balancing glue performance and production efficiency

The primary challenge in applying environmentally friendly glue to paper bag machines is resolving the conflict between drying speed and equipment efficiency. Traditional solvent-based glues rely on evaporation for rapid curing, while water-based and biodegradable glues rely on water evaporation or cooling to form a film. This can easily lead to problems such as stacked bags sticking together and handles falling off during high-speed continuous production.

Analysis of technical difficulties:

  • Insufficient drying speed : The solid content of water-based adhesive is usually 40-60%, and it takes a long time for the water to evaporate, which limits the production line speed.
  • Weak initial adhesion : The colloid cannot quickly form strength in the initial stage of pressing and is prone to displacement during high-speed transmission.
  • Poor temperature resistance : Subsequent processing of paper bags (such as hot pressing) may cause the glue layer to soften and fail.

Innovative solutions:

  1. Formula optimization accelerates curing
    by compounding VAE (vinyl acetate-ethylene copolymer) emulsion with functional additives to significantly increase the speed of film formation. For example:
    • Composite formula of CW40-60IVAE emulsion (20%) + DS58 emulsion (30%) + toughening agent NCP-2 (3%)
    • Combined with water-based wax PE02 (5%) to reduce the surface tension of the adhesive layer and promote water seepage
    This solution increases the speed of the fully automatic bag-making machine from the traditional 70 pieces/minute to 120 pieces/minute, without the need for auxiliary drying equipment.
  2. The glue hot pressing and flattening process
    addresses the problem of food-grade paper bags being fluffy and difficult to flatten. A cylinder-type pressing machine is integrated at the end of the production line :
    • 50mm bore cylinder provides >500N pressure
    • Air damping time relay controls the pressure holding time (usually 8-12 seconds)
    • Composite hard rubber layer on the bottom of the pressure plate to prevent paper surface damage
    Actual measurements show that this process increases the peel strength of the paper bag's bonding points by 40%, while reducing the compressed volume by 10%, significantly reducing packaging material costs.
  3. The new dry powder glue technology for on-site preparation of quick-drying
    glue powder adopts cold water soluble modified starch-based materials:
    • Initial adhesion time is shortened to within 5 minutes
    • 1-hour compressive strength reaches 170% of traditional corn starch glue
    • Support ready-to-use to avoid deterioration of the glue

2. Precise control of glue coating uniformity and dosage

The glue application process on paper bag machines directly impacts glue costs and finished product quality. Traditionally, glue rollers are used for full-surface contact coating, which can easily lead to glue overflowing along the edges of the paper strip, wasting glue and reducing bonding reliability. It's estimated that over-application can increase the cost per bag by 18%.

Technical bottlenecks:

  • Insufficient glue application accuracy in narrow edge areas (such as handle joints)
  • Fluctuations in adhesive layer thickness lead to adhesive seepage or bonding failure
  • Insufficient coating coverage on the special-shaped structure of the bag bottom

Key technological breakthroughs:

  1. The grooved gluing wheel is designed
    in the gluing mechanism of the environmentally friendly paper bag handle machine, transforming the traditional smooth rubber roller into an axially arranged annular groove structure :
    • The groove depth is 1-1.5cm and the width matches the paper tape (usually 10-15cm)
    • The contact area is reduced by 40% and the amount of glue used is reduced by 35%.
    • Cooperate with the pinch roller to control the tension of the paper tape
    Actual tests show that when the groove depth is 1.2cm and the spacing is 0.8cm, the glue transfer rate is optimal and the handle peel strength still reaches 664N/500mm.

  2. The bag bottom gluing device of the dynamic metering coating system adopts closed-loop control:
    • The second electric telescopic rod drives the push plate to move downward to accurately control the amount of glue output
    • The pressure sensor monitors the remaining amount of glue in real time (error <0.5ml)
    • Positioning light guides the bag bottom to the gluing position
    • Synchronous glue spreading with rotating roller brush (speed 120-150rpm)
  3. The modular brush spreading mechanism
    introduces a plug-in brush assembly into the glue spreading process:
    • The brush base and the fixing block adopt an inclined slot structure
    • The best glue spreading effect is when the brush inclination angle is 35°
    • Supports quick replacement (single operation < 30 seconds)

3. Equipment compatibility and process adaptation

The differences in the physical properties of environmentally friendly glues require targeted modifications to paper bag machines. For example, compostable hot-melt adhesives require precise temperature control, while water-based adhesives require rust-resistant flow channel designs. Coordinated optimization of equipment and glue is key to mass production.

Typical compatibility issues:

  • Hot melt adhesive nozzle is clogged at low temperature or carbonized at high temperature
  • Water-based adhesive causes corrosion of metal parts
  • High solid content glue causes blockage of the rubber hose

Equipment innovation direction:

  1. Degradable hot melt adhesive dedicated module
    for compostable materials such as PLA/PBS:
    • Barrel zone temperature control (feeding section 80°C → coating section 130°C)
    • Gear pumps replace screw pumps to reduce shear degradation
    • FDA-compliant food-grade flow channels
    This type of equipment has been used in fully biodegradable paper bag production lines, and the film has passed EN13432 industrial composting certification.
  2. The paper yarn composite bag integrated molding technology
    subverts the traditional bag making process with innovative solutions:
    • Polyvinyl alcohol glue (PVA) is used to bond the vinylon water-soluble yarn and the paper layer
    • The glue forms a microporous membrane (pore size < 5μm) during pressurized lamination
    • Simultaneously achieve moisture-proof and breathable preservation
    • The equipment integrates yarn spreading, gluing and pressing functions, with a speed of up to 20 bags per minute
  3. Servo electric glue valve system
    semi-automatic bottom gluing machine upgrade solution:
    • Water pump pressure constant control (0.2-0.4MPa adjustable)
    • The height of the glue spray head automatically rises and falls along with the threaded rod (accuracy ±0.1mm)
    • Double bevel gear transmission ensures synchronization

4. Coordinated development of environmental protection and functionality

Environmentally friendly glues must not only meet biodegradability requirements but also surpass traditional products in moisture resistance and heat resistance. For example, paper food bags require glue that is both compostable and water-resistant, posing a dual challenge to formulation design.

Performance balancing strategy:

  1. Green alternative to functional additives
    • Replace petroleum-based moisture repellents with plant-based water-based waxes
    • Nanocellulose enhances colloid strength (addition amount 3-5%)
    • Avoid heavy metal catalysts (lead < 1.5 mg/kg)
  2. High temperature resistant yarn reinforcement structure
    in paper yarn composite bag:
    • Vinylon water-soluble yarn can withstand 180°C (higher than the burning point of paper)
    • Warp and weft yarns form a triangular mesh skeleton
    • Glue mainly plays the role of interface bonding rather than load bearing

  3. The latest paper and plastic production line integration of closed-loop glue recycling system :
    • Glue waste heat recovery device (the second heating tube utilizes waste gas)
    • Volatile organic compound adsorption filtration (dust filter >95% retention rate)
    • Cleaning wastewater purification and reuse

Future trends: dual-driven by intelligence and material innovation

With the implementation of an environmentally friendly cushioning packaging equipment project in Zhejiang, grid paper core bag-making machines have implemented servo system linkage control, reducing environmentally friendly adhesive consumption by another 15%. Cutting-edge industrially compostable hot melt adhesives maintain the fast-setting properties of traditional hot melt adhesives while passing tests for adhesive mineralization, film degradation, and ecotoxicity.

Future breakthroughs will focus on:

  • AI visual glue seam monitoring system : real-time adjustment of glue coating parameters
  • Adaptive glue formula : automatically adjusts rheology according to temperature and humidity
  • Washable bonding technology : achieving 100% fiber recycling of paper bags

The application of environmentally friendly glue in paper bag machines has evolved from simple substitution to systematic innovation. Through the coordinated optimization of glue formulations, coating equipment, and process control, the industry is breaking through the old perception that environmental protection must sacrifice performance. With the export of equipment to high-end markets such as South Korea and the European Union, China's intelligently manufactured green paper bag production technology is embracing global opportunities.