Quick answer. M230 is a two-component, solvent-free, low temperature polyurethane adhesive for metal panels, sandwich structures, and metal-to-insulation laminates. Winter production still requires dry metal, controlled component temperature, accurate A:B metering, and enough clamping time; cold-service capability does not mean an uncured joint can be assembled on wet or ice-cold steel. Buyers should approve M230 from conditioned production trials and lap-shear results, not from a generic claim such as “low-temperature resistant.”
The central distinction is cure temperature versus service temperature. Cure temperature governs viscosity, wetting, reaction speed, and time under pressure, while service temperature describes the environment faced after the polyurethane network has fully formed. A formulation may survive sub-zero service yet cure too slowly at 5°C for the planned takt time.
What the M230 designation tells a metal-bonding buyer
The published M230 adhesive product page identifies the grade as a two-component polyurethane for SIP, sandwich-panel, and metal-panel bonding. It lists a solvent-free formulation, working viscosity of 30–450 mPa·s, and two equipment-dependent weight ratios: A:B = 1:1.25 for a vertical machine and 1:1.5 for a horizontal machine.
Those ratios cannot be transferred into a purchase specification without confirming the dispensing configuration. The listed 200 kg Part A and 250 kg Part B drums form a 1:1.25 package set. A line running 1:1.5 would consume 300 kg of Part B for every 200 kg of Part A, so procurement must reconcile drum quantities, pump calibration, and expected residual stock before issuing the purchase order.
The product page also states a 50-second cure time after mixing and says the formulation can be adjusted. “Cure time” is not sufficiently precise for factory acceptance: 50 seconds could describe gel development, loss of flow, or another internal test endpoint. The signed TDS should separately define mix time, application window, open time, press time, handling time, and full cure at stated temperatures.
M230 is therefore a defined starting grade rather than permission to skip application engineering. Ask SPC Adhesives to match the formulation to metal type, core material, bond-line thickness, line speed, and the lowest measured winter workshop temperature. The broader PU adhesive for metal bonding page distinguishes structural 2K PU from heated PVC/PET film-lamination adhesive; these are different processes and should not share an approval sheet.
| Purchase-control item | Published M230 information | Evidence required before approval |
|---|---|---|
| Chemistry | Two-component, solvent-free polyurethane | Current TDS and SDS for both components |
| Mix ratio by weight | 1:1.25 or 1:1.5, depending on equipment | Signed ratio for the selected machine plus a 100-shot ratio study |
| Application viscosity | 30–450 mPa·s | Test temperature, instrument, spindle, speed, and component-specific values |
| Reported post-mix time | 50 seconds; formulation described as adjustable | Separate open-time, press-time, handling-time, and full-cure definitions at 5°C, 10°C, and 23°C |
| Packaging | Part A 200 kg; Part B 250 kg iron drums | Consumption balance against the contracted ratio |
| Storage period | Six months in a general indoor warehouse | Minimum storage temperature, maximum storage temperature, resealing rules, and batch expiry on the CoA |
Surface preparation for steel, galvanized sheet, and aluminum
Cold weather increases the penalty for poor preparation. A colder resin wets the metal more slowly, while condensation can create a microscopic water layer between polyurethane and the oxide surface. The result is often interfacial failure: the cured adhesive releases cleanly from the metal instead of leaving cohesive residue on both adherends.
Measure metal temperature, room temperature, and relative humidity at the bonding station. Keep the substrate at least 3°C above the calculated dew point as a practical production control. A panel moved from a 0°C warehouse into warm, humid air can remain below the room dew point even though the air thermometer reads 18°C.
Cold-rolled and mild steel
Remove oil with a cleaner confirmed compatible with the coating and PU system. Replace contaminated wipes instead of redistributing oil across the sheet. For uncoated steel, a qualification trial can begin with uniform P80–P120 abrasion, followed by complete dust removal; the final abrasive grade must be fixed from bond tests because excessive roughness can trap air beneath a thin glue line.
Prepare and bond steel before flash rust appears. If orange staining develops after water-based cleaning, the oxide condition has already changed. Do not cover it with additional adhesive. Rework the surface and shorten the interval between cleaning and application.
Galvanized and pre-coated sheet
Galvanized steel carries a zinc surface that may contain passivation chemistry, rolling oil, or temporary corrosion protection. Aggressive grinding can remove zinc and create a mixed steel-zinc bond area. Start with cleaning and a light, repeatable abrasion method, then compare unabraded and abraded specimens by the same lap-shear procedure.
Coil-coated or powder-coated sheet is bonded to the coating rather than directly to metal. Record the coating supplier, chemistry, bake schedule, gloss, and batch. A strong adhesive cannot compensate for a coating that detaches from its metal substrate, so peel the failure surface apart and identify which interface separated.
Aluminum
Aluminum reforms an oxide layer rapidly after abrasion. Use a controlled abrade-clean-bond interval and prevent bare panels from waiting through an entire shift. Stainless-steel abrasives or specified nonwoven media reduce the risk of embedding carbon-steel particles that later form corrosion sites.
A water-break observation can screen for gross oil contamination: clean water should form a continuous film rather than beads. Treat it as a shop-floor check, not a substitute for bond testing. Solvent residue, oxide chemistry, and primer compatibility still require qualification.
Use ASTM D1002 or an agreed equivalent to compare preparation routes on metal-to-metal single-lap specimens. ASTM describes the method as comparative and warns that small-specimen apparent shear strength is not automatically a design-allowable stress for a different joint geometry.
How to control winter cure on the production line
Condition unopened Part A and Part B to the TDS-approved processing range before metering. Heating only the workshop air for 30 minutes does little for a 200 kg drum whose core remained overnight at 5°C. Record component temperature with a probe or approved drum measurement method rather than assuming it equals room temperature.
A common chemical-engineering rule estimates that reaction rate changes by about twofold for each 10°C temperature change, but it is only a screening heuristic. If a fixture time is 30 minutes at 23°C, the estimate might approach 60 minutes at 13°C and 120 minutes at 3°C. M230 release times must come from measured trials because formulation, bond-line thickness, substrate heat capacity, and catalyst package change the result.
Cold viscosity also changes the applied mass and mixing pattern. A fixed pump speed may deliver fewer grams per square metre, while unequal pressure between A and B can move the ratio outside its target. Weigh separate A and B shots for 30–60 seconds, calculate the ratio, and repeat at startup, after a drum change, and after any large temperature shift.
For automatic equipment, inspect the mixed bead for alternating color or texture, then make a cured-bead cut after the stated cure interval. Soft streaks, brittle veins, or liquid pockets indicate incomplete mixing or off-ratio dispensing. Purge volume and static-mixer replacement frequency should be written into the work instruction in millilitres or shots, not left to operator judgment.
| Winter control point | Starting production limit | Failure prevented | Verification record |
|---|---|---|---|
| Metal versus dew point | Metal at least 3°C above dew point | Condensation and adhesive failure at the metal interface | Air temperature, RH, dew point, and metal temperature per shift |
| Component conditioning | Use only inside the supplier-approved TDS range | Poor pumping, weak wetting, and ratio drift | Part A and Part B temperatures before startup |
| Metering ratio | Contracted M230 ratio, verified gravimetrically | Soft or brittle off-ratio polymer | Timed A/B shot weights and calculated ratio |
| Open time | Parts joined before the validated wetting limit | Skin formation and incomplete transfer | Mix, coat, close, and press timestamps |
| Pressure | Enough for continuous contact without starving the joint | Voids, spring-back, and squeezed-dry bond lines | Press pressure, panel stack height, and dwell time |
| Release | Witness coupon reaches the approved handling criterion | Panel creep or skin-core displacement | Coupon result linked to batch and production lot |
Do not use excessive press pressure to force cold adhesive to spread. Metal skins can look flat while foam or mineral-wool cores contain local thickness variation. Excess pressure can squeeze resin away from high spots, crush a low-density core, or leave a bond line too thin to accommodate differential thermal movement.
Maintain a traceable winter log containing adhesive batch numbers, drum opening times, substrate lot, surface-preparation route, component temperatures, ambient temperature, relative humidity, shot-weight ratio, coating mass in g/m², assembly time, pressure, and release time. This record separates material variation from a cold-start equipment problem.
Qualification, failure analysis, and supplier documentation
Build qualification coupons from the actual alloy, galvanized finish, coating, and cleaning process. Test at least five specimens per condition so one preparation defect does not decide the purchase. ISO 4587:2003 specifies tensile lap-shear testing of rigid-to-rigid bonded assemblies and explicitly states that the procedure does not provide design information.
Include three cure conditions: the nominal laboratory condition, the lowest planned winter production temperature, and one deliberate cold-start challenge. After full cure, test specimens at room temperature and at the lowest specified service temperature. Winter cure and cold service then receive separate pass/fail evidence.
Report both MPa and failure mode. A 6 MPa result with cohesive failure through the adhesive tells a different story from 6 MPa accompanied by clean release from galvanized steel. Photograph every fracture face and classify adhesive, cohesive, substrate, or mixed failure using one written rule across all suppliers.
Panel factories should add full-scale checks because lap joints cannot reproduce skin waviness, core porosity, thermal mass, or press distribution. Cut witness sections from the panel edge, inspect adhesive transfer and voids, then perform the plant’s peel or skin-removal test after the contracted cure interval.
For export procurement, request a TDS revision number, SDS for Parts A and B, batch CoA, packing specification, shelf-life statement, transport classification, and country-specific regulatory documents. Do not treat an ISO 9001 logo as product certification; obtain the certificate, certificate number, issuing body, expiry date, and scope covering the manufacturing site.
Polyurethane handling controls must follow the current SDS. OSHA’s isocyanates guidance identifies polyurethane adhesive work as a potential source of isocyanate exposure and associates exposure with skin and respiratory effects. Ventilation, gloves, eye protection, spill response, and worker training must be selected through the site’s exposure assessment.
For EU industrial or professional use, check free-diisocyanate status and training duties against REACH Annex XVII, Entry 74. The restriction uses a 0.1% by-weight threshold and requires training before use for covered products at or above that concentration; the supplier should provide supporting composition or regulatory documentation rather than a sales-email assurance.
Factory-direct sourcing has practical value when it produces controlled changes rather than an undocumented relabel. For a customized winter cure PU glue, require an agreed change-control procedure, retained samples, and new validation whenever the catalyst level, raw-material source, ratio, or open-time package changes.
The commercial quotation should state exact MOQ in kg or tonnes, sample quantity in kg, production lead time in calendar days, Incoterm, drum configuration, pallet dimensions, net and gross weight, and remaining shelf life at dispatch. These values are order-specific; inserting assumed MOQ or lead-time numbers into the specification creates a false contractual baseline.
Before a container order, run enough sample material to cover a cold startup, steady production, one pause, one mixer change, and a restart. Approve the supplier only after the same acceptance limits are written into the purchase specification and batch CoA. This converts M230 from a product name into a controlled metal-bonding process.
FAQ
Q: Can M230 cure below 0°C?
The public product information describes low-temperature resistance but does not publish a minimum application temperature. Do not infer sub-zero cure from cold-service language. Obtain a temperature-specific TDS and validate mixing, wetting, fixture time, full cure, lap shear, and failure mode at the actual plant minimum.
Q: Is M230 suitable for stainless steel and aluminum?
Two-component PU can bond both metals, but the approval applies to the tested surface condition. Stainless oil, aluminum oxide, anodizing, conversion coating, and coil coating each alter adhesion. Submit the exact alloy and finish for coupon testing before ordering production volume.
Q: Should we heat the metal or the adhesive during winter?
Both must remain inside their approved process windows. Warming drums without warming a 1,200 mm steel panel can leave the mixed adhesive cooling immediately after contact. Measure Part A, Part B, and metal temperatures separately, and keep the metal at least 3°C above dew point.
Q: What does the published 50-second M230 cure time mean?
The online wording does not identify whether 50 seconds is gel time, loss of flow, green strength, or another endpoint. Ask the manufacturer to define the test temperature, mixed mass, timing method, and endpoint, then obtain separate open-time and press-time values for your line.
Q: Which M230 mix ratio should our factory use?
The product page lists 1:1.25 by weight for vertical equipment and 1:1.5 for horizontal equipment. Use only the ratio confirmed in the signed TDS for the supplied formulation and machine. Verify it by weighing independent A and B shots; do not set pump speed from drum size alone.
Q: What is the minimum test package before a bulk order?
Use at least five lap-shear specimens per preparation and cure condition, record failure modes, and add a full-size panel trial. Include nominal cure, lowest winter cure, cold-service exposure, a mixer restart, and a production-rate run with recorded g/m² coating mass and A:B ratio.