PVC Resin HS-1000R(SG-5)

PVC Resin HS-1000R(SG-5) is a suspension-polymerized poly(vinyl chloride) resin classified under GB/T 5761-2006 as grade SG-5, with a nominal K-value of 66–68 and an average degree of polymerization in the range 1000–1100. The material is supplied as a white free-flowing powder with apparent bulk density typically 0.48–0.54 g/cm³ when measured according to ISO 60:1977, volatile matter controlled to ≤0.30% by ISO 1269:2006, and air-jet sieve residue on 0.063 mm mesh normally below 5% under ISO 4610:2001. The HS-1000R designation is a manufacturer-specific lot identifier within the SG-5 class; it is distinguished from lower-K SG-7/SG-8 and higher-K SG-3 resins primarily by melt viscosity, fusion rate, and the balance between mechanical strength and processability in rigid dry-blend extrusion. The grade is not a paste resin and is not intended for plastisol processing; emulsion and microsuspension PVC grades are used where fine-particle dispersion in plasticizers is required.

How does HS-1000R(SG-5) differ from SG-3, SG-7, and SG-8 in molecular architecture and melt rheology?

The primary variable differentiating suspension PVC grades is the average degree of polymerization, which controls melt viscosity and gelation kinetics. SG-3 with K 70–72 and average DP 1250–1350 produces higher melt viscosity and greater creep resistance but requires higher processing temperatures and longer fusion time; it is selected for pressure pipes and heavy-wall profiles where long-term hydrostatic strength is critical. SG-7 with K 60–62 and DP 750–850 and SG-8 with K 57–59 and DP 650–750 exhibit lower melt viscosity and faster gelation, making them suitable for injection molding of fittings, thin-wall profiles, and high-flow compounds. HS-1000R(SG-5) occupies the intermediate position: its higher melt viscosity than SG-7/SG-8 supports wall thickness retention in pipe extrusion and reduces melt fracture at high draw ratios, while its lower melt viscosity than SG-3 allows higher output on conical twin-screw extruders and lower torque at start-up. Published capillary rheometry data for this specific HS-1000R lot designation is limited; comparative grade behavior is typically characterized by K-value and Brabender fusion time rather than absolute melt viscosity. The following matrix summarizes the comparative position.

In high-intensity hot/cold mixing, HS-1000R(SG-5) dry blends are prepared with organotin mercaptide or calcium-zinc stabilizers, oxidized or paraffin wax lubricants, impact modifiers such as methacrylate-butadiene-styrene or chlorinated polyethylene, and fillers. The mixer discharge temperature is controlled at 110–130°C for rigid PVC compounds; the blend is then transferred to a cooling mixer and brought to 40–50°C before storage to prevent agglomeration and stabilizer pre-reaction. The resin particle porosity and plasticizer absorption of 19–23 g/100 g by ISO 4608:1998 allow adequate liquid stabilizer uptake without excessive torque rise in the extruder. Uniformity of dry blend bulk density at 0.55–0.65 g/cm³ after mixing is used as a process indicator; values outside this range suggest segregation or incomplete cooling.

Specification conformance envelope for HS-1000R(SG-5)

Lot conformance for HS-1000R(SG-5) is normally established against the SG-5 classification in GB/T 5761-2006, supplemented by ISO analytical methods. The table below summarizes the standard specification envelope and the typical values reported in supplier certificates of analysis. Actual lot values must be verified against the certificate of analysis; the resin should be rejected if K-value falls outside 66.0–68.0, volatile matter exceeds 0.30%, or the 0.063 mm sieve residue exceeds 5% because these deviations alter gelation and cause surface defects in rigid extrusion.

On counter-rotating conical twin-screw extruders with screw L/D ratios of 25:1 to 30:1 and screw diameters from 55 mm to 92 mm, barrel zone settings for rigid pipe compound based on HS-1000R(SG-5) typically progress from 155°C at the feed zone to 185–195°C at the adapter and die. Melt pressure at the die is held between 180 bar and 320 bar depending on pipe diameter and die resistance; pressure fluctuations above ±10% of setpoint are associated with inconsistent feed or inadequate dry blend conditioning. The fusion rate in a Brabender Plastograph torque rheometer at 60 rpm and 190°C for a standard rigid pipe formulation typically reaches maximum torque within 2–4 minutes, with a torque peak between 28 N·m and 35 N·m. Compared with SG-3, the lower K-value of SG-5 shifts the fusion peak earlier and reduces equilibrium torque, which supports higher output at constant screw speed; compared with SG-7, the fusion time is longer, and the melt is less prone to overwetting in calibration sleeves.

When thermal stabilizer depletion and shear heating become boundary conditions

Thermal stability of HS-1000R(SG-5) is governed by the dehydrochlorination induction period in the presence of stabilizers. Static heat stability tests according to ISO 182-1:1990 (Congo red method) are used to measure the time to hydrogen chloride evolution at 200°C; rigid compounds formulated with adequate stabilizer show Congo red times of not less than 60 minutes, while understabilized batches fail in less than 30 minutes. In production, stock temperature must be kept below 205°C at the screw tip and die; above this threshold, the rate of polyene sequence formation increases sharply, leading to yellowing, die plate-out, and a drop in impact strength. Shear heating from excessive screw speed or high die resistance can raise local melt temperature by 10–15°C above barrel setpoint, which is critical when barrel setpoints are already at 190°C. The operating boundary is therefore a processing window of approximately ±5°C around the target die melt temperature of 190–195°C. At relative humidity above 60%, pre-drying of the resin is required because moisture above 0.30% generates splay and microvoids in the extrudate. Avoid combining with amine-based additives or certain lead-free stabilizer packages that can cause premature crosslinking or plate-out; compatibility must be verified by torque rheometry before production.

In production-scale pipe extrusion, batch-to-batch variance in HS-1000R(SG-5) apparent density and K-value modifies feed behavior in gravimetric dosing units. A shift in bulk density from 0.52 g/cm³ to 0.48 g/cm³ alters the mass flow through the feed throat at constant screw speed and can produce pressure oscillations unless the dosing system compensates. Screen pack changes are not used in rigid PVC pipe extrusion; instead, the melt is conditioned by breaker plate design and the gelation level is controlled by barrel temperature and screw speed. Start-up with SG-5 typically requires a purging compound with higher lubricant level to prevent degradation during the residence time of 3–5 minutes at 180–190°C. These effects are routinely observed on parallel and conical twin-screw lines; published values for HS-1000R-specific batch variance are limited, and converters should establish internal process capability indices for incoming lots.

Rigid pressure pipe manufactured from HS-1000R(SG-5) is tested for hydrostatic design stress under ISO 9080:2022 and product dimensions under ISO 1452-2:2009; the compound typically delivers tensile yield stress of 45–55 MPa when tested according to ISO 527-2:2012, notched Charpy impact strength of 3–8 kJ/m² without impact modifier under ISO 179-1:2010, and Vicat softening temperature of 80–85°C under ISO 306:2022 method B50. The grade is also used in foam-core PVC pipe and free-foam sheet extrusion, where balanced gelation prevents premature cell coalescence. Foam extrusion with HS-1000R(SG-5) uses endothermic chemical blowing agents such as sodium bicarbonate/citric acid blends or exothermic azodicarbonamide. The gelation window is narrower than for SG-3 because the lower melt viscosity reduces cell wall strength; foaming density of 0.55–0.80 g/cm³ for free-foam sheet is achievable when the melt temperature at the die is controlled to 175–185°C and the blowing agent decomposition is matched to the gelation level. Published data for this specific SG-5 resin in foam extrusion is limited; converter trials on a 90 mm conical twin-screw line are recommended to establish the stabilizer and lubricant package. In cable bedding and conduit, the SG-5 resin provides crush resistance and dimensional stability; performance is assessed by cold impact at -25°C and heat deformation at 90°C according to relevant product standards. For injection molding, HS-1000R(SG-5) is limited to thick-wall fittings and industrial components; SG-7 or SG-8 is selected for thin-wall fittings where high melt flow is required.

Storage should be in closed silos or bags at ambient temperature below 40°C and relative humidity below 60%. Bulk density segregation can occur during pneumatic conveying if air velocity exceeds 25 m/s; dense-phase conveying is recommended to avoid fines enrichment and flow blockages at rotary valves. REACH compliance is addressed by the polymer exemption in Article 2(9) of Regulation (EC) No 1907/2006, but residual vinyl chloride monomer content must be declared in the safety data sheet and controlled by ISO 6401:2008. RoHS Directive 2011/65/EU restrictions for lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE must be verified on the final compound, not on the resin alone; lead-stabilized formulations are not RoHS-compliant. Food-contact approval of articles made from HS-1000R(SG-5) is not automatic: the converter must demonstrate compliance with migration limits in EU Regulation (EU) No 10/2011 or GB 4806.6-2016, including residual VCM below the applicable limit and total migration below the applicable overall migration limit. The resin should not be assumed suitable for medical devices without ISO 10993 biocompatibility testing on the finished article.

Because HS-1000R(SG-5) is a suspension resin with mean particle diameter typically 100–200 µm and low emulsifier content, it is not suitable for plastisol or organosol processing. Emulsion PVC grades with particle size below 60 µm and microsuspension grades are required for spread coating, rotational molding, and dip molding where plasticizer absorption and paste viscosity stability are primary. This distinction is critical when comparing HS-1000R(SG-5) with PVC paste resins: the SG-5 dry blend route avoids the viscosity aging and shear thinning behavior of plastisols and is selected for rigid building products where dry-blend extrusion is the conversion route.