Liquid PUR Adhesive Suppliers

Hangzhou Yihe New Materials Co., Ltd. is a China-based Liquid PUR Adhesive manufacturer and specialty adhesives producer established in 1997. From our site in Tonglu beside the Fuchun River we run our own laboratory, formulation and production, and supply water-based, PUR and EVA systems to woodworking, door, panel, packaging and automotive interior plants whose customer base covers countries and regions across the world.

The Liquid PUR Adhesive range is the ambient-applied, 100% solids part of our PUR programme. The core grade, LM2260, is a single-component moisture-curing polyurethane supplied as a flowable liquid: poured or scraped onto the workpiece, closed cold, and left to build strength while it reacts with moisture from the substrate and the air. Nothing has to be melted, and no water or solvent carrier has to be driven off.

Where Liquid PUR Sits in a Bonding Programme

Four PUR formats cover most panel, door and profile work, and they are not interchangeable. Liquid PUR is chosen where the bond area is large, the substrates are thick or mixed, the press is cold, or the glue line has to bridge gaps and surface irregularity rather than simply seal an edge.

A cold press, a honeycomb or plywood core, a stone or HPL skin and a workshop with no melter point toward the liquid route. A 20 m/min edgebander running 0.4 mm ABS points toward an edgebanding hot melt. We produce both, so the recommendation follows the line rather than the catalogue.

How the Bond Forms

The adhesive is a polyurethane prepolymer with free isocyanate groups and no carrier at all. Once the joint is closed, those groups react with moisture and the polymer crosslinks into a thermoset network that will not re-soften under summer heat or a hot press in a downstream process.

• 100% solids. There is no water or solvent to evaporate, so the glue line does not shrink back or pull the faces together as it dries.
• Foaming cure. The reaction releases carbon dioxide, which expands the film into the open structure of the second face, the cell walls of a honeycomb core or the machining tolerance of a door stile.
• Green strength in the press. Pressure brings the surfaces into contact and the pressed part can be handled; full cure develops over the following hours and is faster in warm, humid air than in a cold, dry plant.
• Permanent bond. A reactive bond tolerates moisture, heat and load far better than a thermoplastic glue line of the same weight.

Because the film expands, coat weight and press pressure do more to determine bond quality than the amount of adhesive a buyer thinks they are saving. Starved glue lines and flooded ones fail for different reasons, and both are visible at the squeeze-out.

Application Fit by Assembly

• Aluminium honeycomb and sandwich panels. Skins in aluminium, HPL, FRP, stone or wood veneer bonded to honeycomb or other cores. The foam line fills the open cells at the interface and absorbs small variations in core height, which is why this grade suits the job better than a line that simply sits on top of the cell walls.
• Flat lamination of boards. HPL, veneer, melamine and decorative film onto MDF, plywood and particleboard where a cold press or a short-cycle press is available and the panel cannot be run through a heated laminator.
• Door and frame assembly. Stiles, rails, skins and cores where machining tolerance and slight warpage have to be taken up inside the joint instead of showing as a dry line on the face.
• Mineral and composite boards. Gypsum, fibre cement and mineral cores where a solvent-free reactive bond is preferable to a water-based system that would sit on the surface.
• Mixed-material industrial assembly. Metal-to-wood, composite-to-board and other dissimilar joints in automotive interior and general industrial work.

Where a decorative face is involved, the foaming action also needs watching: too much adhesive and the squeeze-out can mark a veneer or a high-gloss film, so the coat weight is usually trimmed to the minimum that still gives a continuous, slightly foamed line.

Substrate and Workpiece Considerations

• Moisture content. Wood and board supply a large part of the water the cure needs. Very dry stock slows the reaction and can leave a powdery, under-cured line; soaked stock over-foams and voids. Interior wood is commonly run around 8–12% and should be measured, not assumed.
• Surface condition. Sanding dust, mould release agents, oil and metal oxide films all interfere with wetting. Aluminium is normally degreased and lightly abraded before bonding.
• Flatness and fit. A foam line bridges small steps but not a bowed panel. Platen pressure has to be distributed, and thin skins need caul plates to spread the load.
• Core geometry. Open honeycomb cells consume adhesive; cell size and foil thickness therefore drive coat weight more than panel area alone.
• Plastics and coatings. PVC, PET and ABS wet out differently, low-energy surfaces may need pre-treatment, and plasticiser migration in flexible PVC should be checked before a film is specified.

Workshop climate belongs on the same list. A board at 5 °C in winter and a drum stored in an unheated store both change viscosity, open time and cure speed, and the line settings that worked in September will not repeat in February.

Setting the Process Window

Coat weight, open time and press dwell are decided together, on the actual substrate pair and with the actual press. The table below is the structure we work through with a customer before the first production batch.

Adhesive temperature is part of the same picture: a cold drum pumps badly, meters unevenly and wets out slowly, so storage conditions are treated as a process variable rather than a warehouse detail.

Equipment and Line Integration

The liquid route keeps the equipment simple compared with a hot-melt installation, and most of the integration work is about repeatability rather than heat.

• Application. Manual pour from the supply container, roller or scraper for short runs, or a pump-fed traversing head for repeated patterns. A gear pump with a metered dispense head gives the most repeatable coat weight across a large panel.
• Pressing. A hydraulic cold press with flat platens; for honeycomb, caul plates distribute load and prevent core crush at the edges.
• Wetted parts. Stainless steel or compatible polymer in pumps, hoses and nozzles, with a flush routine before product can gel in the line.
• Cleaning. Uncured adhesive is removed with a suitable solvent; once cured it can only be taken off mechanically, so nozzles, scrapers and platens are cleaned at the end of each shift.
• Ventilation and PPE. Isocyanate-based products need local exhaust at the dispense point, general ventilation and nitrile gloves with eye protection for anyone handling the drum or the wet line.
• Interlocks. Dispense pattern, robot path and press sequence are best interlocked so adhesive is never applied to a panel that is not going straight into the press.

On a manual cell the operator controls all of this by habit; on an automated cell the same decisions become recipe parameters, and they should be written down once and carried across every shift.

Quality, Acceptance and Documentation

Hangzhou Yihe holds National High-Tech Enterprise qualification and operates ISO 9001 quality and ISO 14001 environmental management systems, supported by in-house laboratory facilities and inspection equipment for raw material, in-process and finished goods checks. The Lima brand was featured on the CCTV programme Quality in 2018. Production and quality control sit on the same site in Tonglu, which keeps the loop between a customer complaint, a formulation change and the next batch short.

Acceptance for a reactive PUR bond is settled at the line trial rather than in a data sheet. The checks that decide whether a process is under control are:

• Bond strength in the agreed geometry: tensile shear for lap joints, flatwise tensile or peel for sandwich panels
• Percentage of wood failure on wood substrates, which shows whether the joint failed in the adhesive or in the wood
• Foam line continuity, thickness and even squeeze-out, with no starvation at panel edges or corners
• Cure state at release, since a pressed but under-cured part will move during trimming or edgebanding
• Climatic exposure: hot, humid, cold and, where the specification calls for it, boil or soak cycles to the destination standard
• Appearance on decorative faces, including any bleed-through or staining on veneer and film

Specification data for a reactive PUR grade covers solids content, viscosity at the stated temperature, density, isocyanate content, open time and cure profile; the safety data sheet covers isocyanate handling and first aid. Declarations required for a destination market are confirmed grade by grade before shipment.

Storage, Handling and Line Hygiene

A moisture-curing product has to be protected from moisture before it is used, which shapes both packaging and daily handling on site.

• Keep containers closed and store them dry, within the temperature range stated on the label; stock is rotated so older material is consumed first.
• Part-used containers are resealed promptly and kept out of humid air; skins that form on the surface are removed before dispensing rather than stirred back in.
• Adhesive taken out for a run is not returned to the original container.
• Solvent used for flushing is handled as hazardous waste in line with the plant's ISO 14001 procedures.

Because the same wetted parts serve the whole run, a simple flush-and-clean routine at shift end protects both the pump and the coat weight accuracy far more effectively than corrective maintenance after a blockage.

Information We Use to Configure Your Solution

A workable proposal needs more than a substrate name. The details below let us select the grade, propose a coat weight and open time, and predict where the trial is likely to need adjustment.

Send the current adhesive and the problem it creates as well, whether that is bleed-through, a slow press cycle, edge starvation or movement after machining. That single detail usually shortens the trial more than any other.

Frequently Asked Questions

Is Liquid PUR Adhesive a two-component product?

The grade we supply is one-component. No inline mixing, metering ratio or pot life management is needed; the product cures from moisture present in the substrate and the surrounding air. That removes a whole class of mixing faults from the line, but it also means substrate moisture and ambient humidity become process variables in their own right.

Can it bond aluminium honeycomb sandwich panels?

Yes. This is one of the defining applications for the liquid grade, because the foaming cure expands into the open cells and compensates for small variations in core height rather than sitting only on the cell walls. Skins should be degreased and lightly abraded, press pressure kept low enough to avoid crushing the core, and caul plates used to distribute load on thin faces.

How does it differ from PUR hot melt used in edgebanding or wrapping?

PUR hot melt is applied molten through a roller, slot die or glue pot and sets as it cools before curing, which suits edgebanding and profile wrapping at line speed. Liquid PUR is applied at room temperature, gives a longer assembly window for large panels, and expands into gaps and open structures. The two formats solve different problems and are often used side by side in the same factory.

What determines how fast the bond cures?

Substrate moisture, ambient temperature and humidity, coat weight and the porosity of the faces. A warm, humid plant with normally conditioned board will cure noticeably faster than a cold, dry one. Press time gives handling strength; full crosslinking continues afterwards, so parts should not go straight into trimming, edgebanding or packing without a defined cure check.

How are coat weight and press time decided?

From the substrate pair, the glue-line target, the core type and the capability of your press. We start with a calculated coat weight, run trial panels, then adjust against destructive test results and the appearance of the foam line. The settings that pass the trial are recorded as the working recipe for that product and carried across shifts.

What should be included with a quotation request?

Substrates and their surface condition, part dimensions and core geometry, press type and pressure range, target cycle time, workshop climate, the test method and pass criteria, expected consumption and the market the finished product is sold into. With those in hand we can propose a grade, a starting process window and a trial plan rather than a price against a product name.