Payal Polyplast Payflex-P90 Di-iso-nonyl Phthalate (DINP)

Payal Polyplast Payflex-P90 Di-iso-nonyl Phthalate (DINP) enters low-voltage PVC wire insulation and sheathing compounds as a primary plasticizer in dry-blend extrusion operations where the branched C9 phthalate ester modulates melt viscosity, increases plasticizer retention, and preserves elongation after thermal aging. A suspension PVC resin with K-value 70–71 is typically dry-blended in a vertical high-speed mixer with an impeller tip speed near 25 m/s; frictional heating raises the batch temperature to 110–120 °C, at which point DINP absorption into the PVC particles proceeds without excessive agglomeration. The compounded dry blend is transferred to a cooler and then melt-compounded through a co-rotating twin-screw extruder with an L/D ratio between 24:1 and 30:1, using a vacuum vent at -0.06 MPa to -0.08 MPa to strip residual moisture and low-boiling species. Barrel zones are set from 140 °C to 170 °C, while the crosshead die is held at 165–175 °C to prevent scorch at the pressure die face. Conductor preheat at 80–120 °C improves adhesion of the primary insulation; line speed is adjusted to maintain a minimum heat history for complete fusion because DINP's higher molecular weight relative to DEHP can leave unmelted microdomains if the extruder residence time is too short. In UL 1581 thermal aging at 100 °C for 168 h, a fully fused DINP-PVC insulation retains elongation above the 65 % minimum commonly required for flexible cord constructions; the exact retention depends on Ca-Zn stabilizer dosage, antioxidant level, and filler loading. For North American UL 62 or UL 83 constructions, DINP-based jackets can be formulated for 60 °C or 75 °C continuous conductor temperature, but 105 °C-rated insulation normally requires a trimellitate blend because DINP volatility under extended aging at 136 °C begins to contribute measurable embrittlement. In electrical property testing, plasticized PVC compounds using DINP exhibit volume resistivity typically in the range of 1×10¹² Ω·cm to 1×10¹³ Ω·cm after conditioning at 23 °C and 50 % relative humidity when measured according to IEC 60093 or ASTM D257; this is acceptable for low-voltage insulation but should be re-evaluated after water immersion. Directive 2011/65/EU RoHS Annex II restricts DEHP, DBP, BBP, and DIBP but not DINP, so DINP remains a compliance-relevant alternative in electrical and electronic equipment cables where the four restricted phthalates must be absent. Under REACH Annex XVII entry 52, DINP is restricted only at concentrations above 0.1 % by weight in toys and childcare articles that can be placed in the mouth; permanent wire and cable products are outside the scope of that restriction. In the European Union, cables permanently installed in buildings fall under EN 50575 Construction Products Regulation; DINP-containing PVC sheaths contribute smoke and flaming droplets during fire but do not alter the HCl gas yield per mass of PVC backbone. The operational boundary for extrusion is that the PVC resin must be pre-dried to below 0.2 % moisture if ambient relative humidity exceeds 60 %; otherwise surface defects and porosity arise in the extruded insulation.

How Does DINP Retention Affect Calendered Heterogeneous PVC Flooring?

In calendered heterogeneous PVC floor coverings, Payflex-P90 DINP is metered into the foamable core layer and the compact wear layer at different concentrations because the two layers require different melt rheology and residual plasticizer behaviour. The foamable core typically receives 40–55 phr DINP together with azodicarbonamide blowing agent at 1.5–2.5 phr, zinc oxide kicker, and Ca-Zn stabilizer; the wear layer receives 25–40 phr DINP in a transparent or filled formulation to balance flexibility against indentation resistance. The dry blends are fused in a continuous kneader or Buss co-kneader at 140–160 °C, then calendered through a four-roll or five-roll calender with roll temperatures maintained between 150 °C and 170 °C to avoid plasticizer fuming at the nip. DINP has a lower vapour pressure at 170 °C than DEHP at equivalent addition, which reduces visible condensate on calender extraction hoods and minimises variation in plasticizer content across the web. The individual PVC layers are laminated to a glass-fibre scrim or polyester backing under controlled tension, after which the sheet passes through an embosser at 130–150 °C to impart a registered texture. The mechanical classification of the finished floor covering is assessed under EN 649 or ISO 10582, with abrasion resistance measured according to EN 660-2, and residual indentation measured under EN 433; DINP's contribution to indentation recovery is influenced more by gelation level than by plasticizer type, so calendering operators must ensure that the compound reaches a minimum fusion level before embossing. In the foamed core, insufficient DINP absorption during dry blending creates gel defects that appear as pinholes after expansion; therefore the hot mixer discharge temperature is held at 110–125 °C and the cool mixer discharge is kept below 45 °C to prevent blocking of the dry blend. Published data for this specific Payflex-P90 batch is limited, but the processing window is consistent with general DINP homologue behaviour in calendered PVC floor coverings.

In spread-coated polyester scrim tarpaulins and architectural fabric membranes, DINP is added to PVC plastisols at 60–80 phr with a suspension or emulsion PVC paste resin to create a thixotropic coating with a Brookfield viscosity of 4000–8000 mPa·s at 25 °C. The plastisol is applied to a woven polyester base fabric by knife-over-roll coating at a head gap of 0.2–1.5 mm, then gelled at 165–175 °C and finally fused at 190–200 °C in a multi-zone oven. Payflex-P90 lowers the initial plastisol viscosity compared with higher-molecular-weight plasticizers, which allows higher coating line speeds without excessive penetration through the scrim; the branched C9 structure also slows the development of dilatancy under high shear in the coating head. The coated fabric is tested for peel adhesion according to ISO 2411, tear strength according to ISO 4674-1:2021, and tensile strength according to ISO 1421. Because the end product is an industrial tarpaulin and not a toy or childcare article, the REACH Annex XVII entry 52 restriction of 0.1 % DINP in articles that can be placed in the mouth is not applicable; users must still confirm that the final fabric complies with any customer-specific restricted substance list. The principal processing limitation is the need to keep residual moisture in the polyester scrim below 0.5 % prior to coating, because water released through the hot plastisol generates blisters and reduces peel adhesion at the interface. Amine-based adhesion promoters should be avoided in DINP/PVC plastisols because amino groups accelerate dehydrochlorination and can cause early discoloration at fusion temperatures.

When Plasticizer Viscosity Controls High-Volume Automotive Underbody PVC Plastisol Application

Automotive underbody PVC sealants and anti-chip coatings use DINP as a primary plasticizer in high-solids plastisol formulations applied by airless spray equipment in body shops. The formulation typically contains 80–110 phr DINP per 100 phr PVC paste resin, calcium carbonate filler, Ca-Zn or barium-zinc stabilizer, and a pyrogenic silica thixotrope; the resulting plastisol has a pseudoplastic flow curve with a high yield stress to prevent sag on vertical surfaces, typically measured by a rotational viscometer at 20 °C. When the plastisol is applied at dry film thicknesses of 0.8–1.2 mm, the viscosity must remain stable during 8 h of production line use, and DINP's low vapour pressure at room temperature helps limit viscosity drift from solvent loss. After electrocoat, the applied underbody layer is cured in the E-coat oven at 140–170 °C for 20–30 min, where the plastisol gels and fuses to a dense PVC skin. The branched C9 phthalate ester supports a wider curing latitude than faster-gelling plasticizers, but it requires a slightly higher oven temperature or longer dwell than DEHP-based formulations because the higher molecular weight delays full sintered fusion. Adhesion to electrophoretic-coated steel is measured using a crosshatch or peel test according to the vehicle manufacturer's specification, and the underbody coating is assessed for stone-chip resistance according to ISO 20567-1; published DINP-specific data for stone-chip performance is limited, but plasticizer retention after heat ageing is generally evaluated by mass loss at 100 °C for 48 h. One operational boundary is that acid-scavenging metal carboxylate stabilizers must be selected carefully because sodium carboxylate residues can react with atmospheric moisture and raise plastisol viscosity during storage. The plastisol must also be protected from prolonged exposure to moisture-laden compressed air in the spray circuit, since water contamination can cause microfoaming during the cure cycle.

Single-Ply PVC Roofing Membrane Aging and Plasticizer Extraction Limits

Payflex-P90 is used in calendered or spread-coated PVC roofing membranes at plasticizer loadings from 40 to 55 phr, where the plasticizer must survive prolonged exposure to UV radiation, heat, and standing water without causing embrittlement or weld failure. The PVC compound for membrane production contains suspension PVC with K-value 65–70, DINP, a liquid barium-zinc or Ca-Zn stabilizer, epoxidised soybean oil co-stabilizer, titanium dioxide at 5–10 phr as UV screening pigment, and a flame retardant if required by the building code. The membrane is produced by calendering into a sheet of 1.2–2.0 mm thickness, followed by hot-air welding on site at an air temperature of 300–400 °C and a welding speed that depends on seam pressure. Plasticizer retention is evaluated using volatility loss after 24 h at 130 °C and water extraction after 24 h at 50 °C; DINP's higher molecular weight produces lower volatility loss than DEHP in the same formulation, but it does not eliminate plasticizer exudation if the compound is overplasticized beyond the resin's absorption capacity. The mechanical properties of the finished membrane are tested according to ASTM D4434 or EN 13956, with tensile strength, elongation at break, and seam strength verified both unaged and after heat aging; the usual minimum elongation for flexible PVC roofing membranes is above 250 %, but supplier specifications may be stricter. Plasticizer migration into EPS or XPS insulation board is controlled by the membrane manufacturer's physical separation layer because DINP, like other phthalate esters, can migrate into polystyrene foam and reduce insulation thickness if direct contact occurs. Hot-air welding below 5 °C surface temperature produces incomplete seam interdiffusion; preheating is required. The processing boundary is that external lubricant loading must remain below the formulation-specific saturation limit, because excess lubricant migrates to the membrane surface and inhibits peel adhesion at welded seams.

In single-screw profile extrusion of DINP-plasticized PVC sealing profiles and flexible tubing, Payflex-P90 is combined with suspension PVC K-value 65–70 at 35–50 phr to obtain a compound with a Shore A hardness of 75–85 and a flexural modulus suitable for snap-fit gaskets. The dry blend is fed to a single-screw extruder with an L/D ratio of 24:1, equipped with a barrier screw and a screen pack of 80–120 mesh; barrel temperatures are set from 145 °C to 165 °C, with the die temperature at 165–170 °C. DINP's higher gelation temperature than DEHP means the operator must ensure that the melt temperature reaches at least 155 °C before the die, otherwise the profile surface becomes rough and the tensile strength of the final gasket is reduced. The profile is calibrated in a vacuum water tank at 20–30 °C and cut to length; the resulting compound is assessed for hardness using ISO 48-4 or ASTM D2240, tensile properties using ISO 37, and compression set using ISO 815-1. The extrusion plant should pre-dry the compound only if the storage environment has exceeded 70 % relative humidity, because PVC compounds with DINP do not require conventional drying but surface moisture can cause splay. The principal limitation is that DINP is not the preferred plasticizer for low-temperature trim applications below -30 °C; a sebacate or adipate plasticizer is substituted for cold-flexible grades.

Injection Moulding Shrinkage Anomalies in DINP-PVC Footwear Sole Compounds

Direct injection moulding of DINP-plasticized PVC footwear soles and unit soles uses 60–80 phr DINP with a suspension PVC of K-value 65–68, plus impact modifier, Ca-Zn stabilizer, and lubricant in a screw injection machine with a compression ratio of 2:1 to 2.5:1. The cylinder temperature is set at 150–170 °C, the nozzle at 165–175 °C, and the mould temperature at 20–40 °C; the high plasticizer content creates a low melt viscosity that fills thin sole sections but also increases post-moulding shrinkage anisotropy if the mould is opened too early. Operators compensate by holding the injection pressure until the gate freezes and by maintaining a cushion of 3–5 mm in front of the screw to prevent short shots and air traps. The moulded sole hardness is measured according to ASTM D2240, abrasion resistance according to DIN ISO 4649, and flex crack resistance according to ISO 4643; DINP's contribution to flex fatigue resistance is related to retention of plasticizer in the amorphous phase of the PVC. Because footwear is worn in direct contact with skin, the manufacturer must confirm that the final article is not classified as a toy or childcare article under REACH Annex XVII entry 52; industrial and adult footwear is outside the restriction. A common processing defect is plate-out on the mould surface, which increases when the compound contains excess external lubricant; the DINP plasticizer itself does not cause plate-out, but its solvation of PVC can release low-molecular-weight species that deposit on tooling.