Product identification for Daelim Poly LH3750M begins with the trade-name logic of the Daelim Poly LH series, supplied by DL Chemical. The grade is characterized in vendor documentation as a low-colour hydrogenated polybutene fluid in which the numeric suffix 3750 corresponds to a nominal kinematic viscosity of 3750 mm²·s−1 at 100°C determined by ASTM D445. The M suffix is a manufacturer-controlled designation associated with reduced impurity profiles for sensitive end uses; published data for this specific configuration is limited, and the certificate of analysis remains the controlling document. In physical terms, the product is a clear, non-drying, saturated aliphatic hydrocarbon polymer with low odour and negligible aqueous solubility. Industrial use concentrates in adhesive and sealant plasticization, lubricant additive basestocks, tackifier modification, and personal-care emollients. The high nominal viscosity places the grade at the upper end of the liquid polybutene range, making it suitable for formulations where low volatility and high film retention dominate over low-temperature pumpability.

What specification methods govern lot acceptance for Daelim Poly LH3750M?

Lot acceptance for the grade is not determined by a single property; the manufacturer’s certificate of analysis typically carries the standard battery shown below. The controlling viscosity measurement is ASTM D445 using a calibrated Cannon-Fenske or Ubbelohde viscometer at 100°C, with the nominal grade value reported as 3750 mm²·s−1. Colour is reported as platinum-cobalt units under ASTM D1209, which is critical for clear sealant and cosmetic formulations. Density is measured by ASTM D4052 oscillating U-tube; flash point by ASTM D92 Cleveland open cup provides the safety-classification ceiling for hot-melt compounding. Water content is determined by Karl Fischer coulometric titration under ASTM D6304, because residual moisture above the supplier limit produces microvoids in extruded adhesive film. Low halide residuals are quantified by combustion ion chromatography under ASTM D7359; the test is used in electronic sealant qualifications where corrosive chloride and bromide species must be excluded. Acid number under ASTM D974 is monitored as a degradation indicator and as a compatibility check for metal stearate packages. Pour point under ASTM D97 defines the cold-flow boundary, though the test value is only an indicator for formulations because thixotropic fillers and tackifier resins shift the actual cold-failure point.

On a corotating twin-screw extruder with an L/D of 40:1 and barrel zones of 140–180°C, Daelim Poly LH3750M is normally injected through a heated gear pump between the first and second kneading blocks. Addition rates of 15–25 wt% are used in high-viscosity hot-melt adhesive systems to shift the ASTM D3236 Brookfield melt viscosity from an initial plateau of roughly 1200–1800 mPa·s at 180°C to a processable range below 800 mPa·s; the exact shift depends on the base resin melt index and wax content. The high kinematic viscosity of the grade provides a greater viscosity contribution per unit mass than lower-suffix LH products, allowing formulators to reduce polymer content while maintaining peel-strength transfer in ASTM D1876 T-peel testing. At addition levels above 30 wt%, however, the plasticization effect produces cohesive failure in the adhesive layer, and the failure mode under ASTM D1876 transitions from interfacial peeling to stringing and necking. Operators should therefore monitor torque and melt pressure as indirect control variables; a melt pressure rise above 120 bar at the die indicates insufficient temperature control or incorrect gear-pump calibration.

Low Halogen and Sulphur Residue Profiles in Sealant Systems

Insulating glass and electronic sealant specifications require explicit control of halogens and sulphur because ionic residues released during curing accelerate corrosion of aluminum spacers and copper lead frames. The M designation of Daelim Poly LH3750M is applied where a controlled-impurity profile is required; however, the exact upper limits are commercial matters and must be fixed in the purchase specification rather than assumed from the suffix. When total chlorine is measured by ASTM D7359, the reporting limit is commonly 1 mg/kg, and sulphur is often reported by oxidative combustion using ASTM D7041 or by UV fluorescence detection. For the LH series, published data for this specific configuration is limited; formulators should request lot-specific data for both total halogens and extractable ions. In sealant compounding, combining the grade with organic tin catalysts is acceptable, but contact with amine-based adhesion promoters can generate amine carboxylate residues that destabilize the peroxide-cured part. The product should be stored under nitrogen blanketing when bulk storage exceeds 60°C to prevent colour drift and acid number creep.

Differences between Daelim Poly LH3750M and lower-viscosity Daelim Poly grades are primarily expressed through kinematic viscosity at 100°C, volatility, and flash point. A formulator replacing a 950 mm²·s−1 grade with 3750 mm²·s−1 obtains higher film strength, lower evaporative loss under ASTM D972 conditions, and better maintenance of tack after thermal aging; the trade-off is higher room-temperature viscosity, which may require heated storage at 40–60°C and reduced pump speed. In lubricant additive packages, the higher nominal viscosity allows the use of lower treat rates to reach a target kinematic viscosity in hydrocarbon base oils, but the cold-cranking simulator result under ASTM D5293 may become less favourable. Compared with non-hydrogenated polybutene grades of similar viscosity, the hydrogenated structure provides a less reactive aliphatic backbone, which influences UV stability and oxidative degradation rate as measured by ASTM D943 or pressure differential scanning calorimetry. The grade is not compatible with strong oxidizing media; contact with chlorine gas, concentrated nitric acid, or hot peroxides should be excluded.

When Pre-Drying Is Required Before High-Temperature Compounding

Although hydrogenated polybutene is hydrophobic, it is not immune to water pickup during bulk transfer and open-vent storage. In hot-melt lines with slot dies, water above 150 mg/kg measured by ASTM D6304 causes bubble defects and die-lip buildup. The recommended drying regime is vacuum treatment at 80–100°C under 5–10 kPa absolute pressure for 1–2 h, provided the dryer inert gas has a dew point below −40°C. The use of atmospheric air at these temperatures is not advised because oxidation raises acid number under ASTM D974 and shifts colour under ASTM D1209. On production-scale adhesive lines, a drum heater set at 70°C in combination with a nitrogen sparge of 0.1–0.3 L/min often prevents moisture re-entry during long run times. Processing below 100°C without pre-drying is possible for low-moisture lots, but the risk of microvoids increases with residence time in the die.

Food-contact and medical-grade positions for Daelim Poly LH3750M require written regulatory confirmation from the supplier; the product literature alone does not provide self-certification. When the grade is used as an adhesive or sealant component under 21 CFR 175.105, the final formulated article must meet the extraction and end-use limitations of the applicable food type, and the adhesive formulator remains responsible for migration testing. For paper and paperboard contact under 21 CFR 176.170, the acceptable extraction level depends on the food-oil and moisture classification, not simply on the presence of the raw material in the formula. In the EU, REACH registration under Regulation (EC) 1907/2006 must be confirmed for the specific import volume and use descriptor; RoHS compliance under Directive 2011/65/EU applies only to articles, not bulk fluids, but total halogen limits are often imposed privately by electronic component makers. The M suffix may suggest medical suitability, but USP <87> cytotoxicity data and USP <88> implantation data are drug/device-specific and cannot be extrapolated from a raw-material data sheet.

Oxidative Degradation Is Controlled by Hydrogenation and Stabilizer Choice

Hydrogenated polybutene resists radical oxidation more effectively than unsaturated hydrocarbon fluids, but it is not oxidation-proof. Above 120°C in continuous air exposure, the tertiary carbon sites on the aliphatic backbone undergo initiation reactions that raise acid number and generate low-molecular-weight carbonyl by-products. The oxidation stability of a formulated lubricant containing Daelim Poly LH3750M can be screened by ASTM D943 or ASTM D2272 RPVOT; an RPVOT induction time below 100 min in a specific formulation typically indicates that antioxidant dosage or degree of inert gas coverage is insufficient. The M grade is supplied with a manufacturer-selected stabilizer package that should not be combined with amine antioxidants without compatibility testing because amine-phenol antagonism may reduce oxidative protection. In high-temperature gear oil applications, treat rates of 2–8 wt% are processed under nitrogen at 60–80°C with a high-shear disperser running at 1000–3000 min−1; the resulting concentrate is filtered through a 10 µm absolute cartridge before storage. Long-term storage above 60°C should be under nitrogen or dry air with a controlled dew point.

For high-viscosity sealant and adhesive applications, Daelim Poly LH3750M is metered into the sigma-blade mixer at 40–60°C to reduce viscosity before addition of fumed silica and calcium carbonate. The preferred sequence is to add the fluid to the base polymer first, then introduce fillers in two increments at blade speed 20–40 min−1. This sequence avoids silica agglomeration and reduces batch-to-batch viscosity scatter measured by ASTM D2196 Brookfield rotational viscometry. In production-scale insulating glass sealant lines, the mixed compound is transferred with gear pumps below 80°C; higher transfer temperatures can activate moisture-curing systems prematurely. Field experience on industrial mixing lines indicates that poor filler dispersion is more commonly related to inadequate low-shear kneading time than to differences between hydrogenated polybutene suppliers. Published data for this specific configuration is limited, so mixing validation under the actual shear rate and fill level remains necessary.