| HS Code | 401845 |
| Productname | Skin-Friendly PP Staple Fiber for Diapers & Sanitary Towels |
| Material | Polypropylene |
| Fibertype | Staple Fiber |
| Denier | 1.5D-6D |
| Cutlength | 38mm-65mm |
| Crimpnumber | 8-15 crimps per 25mm |
| Color | White |
| Surfacefinish | Hydrophilic, skin-friendly |
| Tenacity | 2.5-4.0 cN/dtex |
| Elongationatbreak | 100%-200% |
| Moistureregain | 0.01%-0.1% |
| Meltingpoint | 160°C-170°C |
| Density | 0.90-0.91 g/cm3 |
| Softness | Soft hand feel |
| Skincompatibility | Non-irritating, dermatologically friendly |
| Phvalue | Neutral to slightly acidic |
| Recommendedapplication | Diapers and sanitary towels |
As an accredited Skin-Friendly PP Staple Fiber for Diapers & Sanitary Towels factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packed in 250 kg bales, wrapped in PP woven fabric with moisture-proof inner liner, strapped, palletized, and clearly labeled. |
| Container Loading (20′ FCL) | 20′ FCL loaded with skin-friendly PP staple fiber for diapers and sanitary towels, palletized, moisture-protected, evenly distributed, secured for export. |
| Shipping | Skin-Friendly PP Staple Fiber for Diapers & Sanitary Towels is shipped as non-hazardous polypropylene staple fiber in compressed bales or cartons, palletized and stretch-wrapped. Transport in clean, dry containers at ambient temperature. Keep dry, away from moisture, sunlight, and contamination. Handle with care; no special dangerous goods requirements. |
| Storage | Store in a clean, dry, well-ventilated warehouse at ambient temperature, away from direct sunlight, heat, moisture, and ignition sources. Keep in original sealed packaging on pallets, off the floor, separated from oils, chemicals, and strong odors. Avoid excessive compression or stacking that may deform fibers. Protect from rain and condensation. Maintain good housekeeping, inspect packaging regularly, and follow FIFO stock rotation. |
| Shelf Life | Store in cool, dry, ventilated area, away from sunlight and moisture; shelf life typically 24 months in unopened original packaging. |
On a carded air-through bonded baby diaper topsheet line, 1.2–1.5 dtex hydrophilic PP staple fiber is blended with PE/PP bicomponent staple fiber at 25–45 wt% PP content. The web is formed on a triple-doffer card with working width 2.4 m and randomized fiber orientation, producing a basis weight of 14–20 gsm. Through-air bonding occurs in a single-drum TAD oven with hot air temperature 134–138 °C, dwell time 1.8–2.4 s, and air face velocity 0.9–1.3 m/s. The PE sheath of the bicomponent fiber melts at 128–132 °C while the PP core remains dimensionally stable below 160 °C. Finish add-on is maintained at 0.20–0.30 wt% to limit strike-through time to ≤2.5 s under EDANA/INDA NWSP 70.7.R1 (15). Industry compliance for infant skin contact uses OEKO-TEX Standard 100 Annex 4 product class I, EU General Product Safety Directive 2001/95/EC, and REACH Regulation (EC) No 1907/2006 Annex XVII. At 2.4 m working width, card doffer speeds above 220 m/min can generate static charges above 4 kV unless humidification is maintained at 55–60% RH; fuzz accumulation on stationary comb segments after 600,000–800,000 m led to random web tears at calender inlet. Terminal product types are topsheet layers for taped and pant-style baby diapers.
| PP staple addition (wt%) | Basis weight (g/m²) | MD tensile strength ISO 9073-3:1989 (N/50 mm) | Strike-through time NWSP 70.7.R1 (15) (s) |
|---|---|---|---|
| 20 | 18 | 8.5 | 2.4 |
| 30 | 18 | 7.6 | 2.0 |
| 40 | 18 | 6.8 | 1.7 |
| 50 | 18 | 6.0 | 1.5 |
Sanitary napkin coverstock produced on engraved calender lines uses 1.2–2.0 dtex PP staple fiber with durable hydrophilic finish blended with PE/PP bicomponent fiber at 20–40 wt%. The carded web is fed to an engraved calender at 138–145 °C roll surface temperature, linear pressure 60–100 N/mm, and bond area 15–19%. Final basis weight ranges from 20–26 gsm. The nonwoven is subsequently apertured or embossed to direct menstrual fluid to the absorbent core. Compliance is governed by US FDA 21 CFR 884.5425 for sanitary napkins as Class I 510(k)-exempt devices, OEKO-TEX Standard 100 Annex 4 product class I, and ISO 10993-1:2018 for biological evaluation when the finished device requires body-contact testing. Calender release properties are governed by finish chemistry; finish oxidation at roll surface above 145 °C creates stickiness and pinhole defects, with roll wrap occurring after 20,000 m if surface temperature drifts more than 3 °C above setpoint. Terminal product types include menstrual napkin topsheets, pantyliner coverstocks, and absorbent pad facing layers.
In acquisition distribution layers for adult incontinence briefs, high-loft through-air bonded nonwovens introduce PP staple fiber at 10–30 wt% as a coarse matrix within a bicomponent-rich blend. The carded web uses a cross-lapper to reach 30–50 gsm and density 0.03–0.06 g/cm³; oven air temperature is held at 140–146 °C with dwell time 3.0–4.0 s to preserve loft. Liquid acquisition is measured under 300 g/m² load using EDANA/INDA NWSP 70.4.R1 (15); absorption capacity is reported per ISO 9073-6:2003. Industry compliance follows EU MDR 2017/745 for adult incontinence products marketed as Class I medical devices, with ISO 10993-1:2018 and ISO 10993-10:2010 testing for skin irritation. Production-scale bottlenecks include fiber shedding at low binder content when PP content exceeds 35 wt%, observed as lint accumulation on calender extraction hoods. Terminal product types are ADL strips placed between topsheet and fluff/SAP core in adult incontinence briefs and overnight sanitary towels.
When core wrap basis weight drops below 16 gsm in ultra-thin sanitary towels, PP staple fiber is incorporated at 60–80 wt% into carded thermal-bonded nonwoven, with PE/PP bicomponent fiber at 20–40 wt% to maintain seal integrity. The process uses a high-speed card with ≥2.2 m working width and an engraved calender at 130–138 °C, bond area 12–16%, producing 12–18 gsm core wrap. The resulting fabric is slit to 80–120 mm widths and fed synchronously with SAP-containing absorbent cores. Tensile strength is specified at ≥4.0 N/50 mm MD and ≥1.5 N/50 mm CD per ISO 9073-3:1989. When basis weight drops below 16 gsm, pinhole formation occurs if bond area exceeds 16% because fiber density at bond points becomes insufficient; maintaining caliper at 0.08–0.12 mm requires lower pressure but lower pressure reduces CD tensile strength. Compliance standards include OEKO-TEX Standard 100 Annex 4, REACH Regulation (EC) No 1907/2006, and OECD Test Guideline 439 for in vitro skin irritation where the core wrap is included in final product biological safety files. Terminal product types are core wrap rolls for ultra-thin and regular sanitary towels.
Hydrophobic PP staple fiber with 1.2–1.5 dtex linear density is carded and thermally bonded for leg cuff nonwoven substrates in baby diapers and adult incontinence products. The formulation uses 30–50 wt% PP staple blended with 50–70 wt% bicomponent PE/PP fiber; bonding is carried out on smooth calender rolls at 148–152 °C and 80–120 N/mm line pressure to minimize fiber surface fuzz. Basis weight is controlled at 18–25 gsm. The nonwoven is slit, elasticized with spandex strands, and ultrasonically bonded into side gather assemblies. Compliance for skin contact requires OEKO-TEX Standard 100 Annex 4 product class I, while component release is assessed using ISO 10993-10:2010 if the leg cuff is part of a medical device. Linting is measured through a rotary lint box method with acceptance ≤0.5 mg/m². Ultrasonic welding at 20 kHz requires thermoplastic content above 50 wt%; below this threshold weld time increases to 0.08–0.12 s and edge delamination may occur. Terminal product types include leg cuff laminates for baby diapers, pant-style diapers, and adult incontinence briefs.
On through-air bonded underpad face stock lines, hydrophilic PP staple fiber is metered into the blend at 20–40 wt% with bicomponent PE/PP fiber for a carded web of 20–35 gsm. The production line includes a wide card, through-air oven at 136–142 °C, and in-line slitting to 60–90 cm roll widths. The nonwoven top layer is laminated to fluff/SAP absorbent pads and PE film backsheets. Compliance follows EU MDR 2017/745 Class I, ISO 10993-1:2018, and FDA 21 CFR 880.5420 if the underpad is marketed as a medical absorbent device in the United States. Liquid absorption is evaluated using ISO 9073-6:2003; strike-through is controlled by NWSP 70.7.R1 (15) at ≤3.0 s. A known production constraint is nonwoven delamination at the adhesive bonding station when calender temperatures exceed 150 °C and film neck-in exceeds 2%. Terminal product types include disposable medical underpads, maternity bed pads, and veterinary absorbent sheets.
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Skin-Friendly PP Staple Fiber for Diapers & Sanitary Towels is produced as a monocomponent polypropylene staple with a round cross-section and a surface finish system intended for repeated skin contact in disposable hygiene nonwovens. The product grade designation is PP-SF-DS-1.5-38-SK; it has a nominal linear density of 1.5 dtex, a cut length of 38 mm, and a finish applied at 0.10–0.18% by fibre mass. The finish is formulated without alkylphenol ethoxylates, phthalates, or silicone oil. The base polymer is a polypropylene homopolymer with a melt flow rate of 25 g/10 min under 230 °C/2.16 kg determined by ISO 1133-1:2022. Intended conversion routes include carded thermal-bonded and through-air bonded nonwovens for diaper topsheets, acquisition distribution layers, and sanitary towel covers.
Relative to general-purpose PP staple for disposables, the product controls acetone-extractable matter at ≤0.50 mg/g using ISO 10993-12:2021 extraction in water and ethanol at 37 °C. Heavy-metal and formaldehyde residues are maintained below OEKO-TEX Standard 100 class I limits for baby articles. The lower extractable load reduces the probability of oligomer transfer to the skin during wet contact, which is the primary regulatory distinction from industrial-grade staple grades that may contain 0.35–0.60% spin finish and uncharacterised oligomer fractions.
| Property | Test method | Typical specification |
|---|---|---|
| Linear density | ISO 1973:2021 | 1.5 dtex ± 0.15 dtex |
| Cut length | ISO 137:2015 | 38 mm ± 2 mm |
| Breaking tenacity | ISO 5079:2020 | ≥2.6 cN/dtex |
| Elongation at break | ISO 5079:2020 | 180–240% |
| Crimp frequency | ASTM D3937-18 | 12–16/25 mm |
| Extractable matter | ISO 10993-12:2021 | ≤0.50 mg/g |
| CIE whiteness | ISO 11475:2017 | >80 |
| Finish on fibre | Gravimetric solvent extraction, adapted from ISO 10993-12:2021 | 0.10–0.18% |
Batch-to-batch consistency is monitored on production cards because deviations in crimp stability and finish friction appear rapidly as web clouding or cylinder loading. On a 3.0 m card running at 150 m/min, the dynamic fibre-to-metal coefficient of friction is held between 0.45 and 0.65 using a fibre friction tester. When the finish drops below 0.08%, static potential exceeds 5 kV at 20 °C and 40% RH, increasing fly accumulation and doffing variability.
Fibre crimp frequency directly controls web cohesion in high-speed carding. For this 1.5 dtex staple, a crimp frequency below 12/25 mm reduces web cohesion on cards operating above 120 m/min, while a crimp frequency above 16/25 mm increases nep formation and fibre breakage in card clothing with 3.2 mm pin spacing. The specified 12–16/25 mm range is maintained by batch crimper setting and confirmed by ASTM D3937-18. Fibre-to-fibre static and dynamic friction are further modified by the finish package to achieve uniform fibre opening without reducing thermal bonding strength.
Web formation at the outlet of a 3.5 m card at 100 kg/h is not governed solely by fibre length. A 38 mm cut length provides adequate carding productivity for basis weights between 12 g/m² and 20 g/m²; in heavier acquisition layers at 30–50 g/m², the same fibre is blended with polyester or polylactic acid at 20–60% by mass. Basis-weight coefficient of variation measured per ISO 9073-1:1989 remains below 3% on well-maintained carding lines, but configuration-specific published data are limited.
The main physical distinction is density. The product has a density of 0.91 g/cm³ by ISO 1183-1:2019, compared with 1.38 g/cm³ for PET and 1.50 g/cm³ for viscose. This lower density generates higher specific volume at equal basis weight, supporting loft retention in through-air bonded ADL fabrics. Unlike PET and viscose, the PP homopolymer does not hydrolyse in humid storage. Its thermal bonding window is lower than PET, with peak melting at 161–163 °C under ISO 11357-3:2018, permitting calendar bonding without a bicomponent sheath.
| Characteristic | PP-SF-DS-1.5-38-SK | Conventional PP staple | Low-denier PET | Viscose |
|---|---|---|---|---|
| Density (g/cm³) | 0.91 | 0.90–0.92 | 1.38 | 1.50 |
| Thermal bonding window (°C) | 145–155 | 150–160 | 230–250 | Not thermally bondable |
| Finish load (%) | 0.10–0.18 | 0.25–0.60 | 0.12–0.25 | 0.20–0.40 |
| Moisture regain (%, 20 °C/65% RH) | <0.1 | <0.1 | 0.4 | 11–13 |
| Hydrolysis risk in storage | Low | Low | Low | High |
The difference in finish chemistry is more critical than fibre geometry. The skin-friendly finish is characterised by a 0.1% aqueous solution surface tension of 32–36 mN/m at 25 °C, a pH of 6.0–7.5 by ISO 3071:2020, and a dynamic fibre-to-metal friction coefficient of 0.45–0.65. This provides temporary wetting in an acquisition layer without creating a permanent hydrophilic surface. Conventional PP grades often use higher friction finishes that can raise rewet or leave surfactant residues in wet diaper cores. Direct substitution of viscose by the product reduces wet collapse but requires recalibration of calendar bonding conditions.
Because the finish is not covalently bonded to the polymer, its migration under wet conditions follows diffusion-controlled release from the fibre surface. Gravimetric extraction in water at 37 °C for 1 h releases less than 0.05% of fibre mass, leaving sufficient surface activity for liquid handling without excessive surfactant accumulation in the absorbent core. Emulsion viscosity of the finish before application is controlled at 40–70 mPa·s at 25 °C to maintain uniform metering across the fibre finish rolls. The finish is applied in a two-stage system with final top-up controlled by near-infrared spectroscopy to keep batch variation below ±0.02%.
Under ISO 11357-3:2018, the fibre exhibits an onset melting temperature of 158 °C, a peak melting temperature of 162 °C, and a crystallinity of 48–52% at 10 K/min. In calendered fabric, process temperatures above 163 °C initiate rapid relaxation of fibre orientation at the roll surface. Machine-direction shrinkage measured after 60 s at 165 °C can exceed 8%, while the same fabric bonded at 150 °C typically shows shrinkage below 2% under ISO 9073-8:2021 after 60 s. This non-linear response defines the upper boundary of the processing window.
Calender settings are therefore maintained with oil-heated roll surface temperatures of 145–155 °C, nip pressure of 30–70 N/mm², and dwell time of 0.8–2.5 ms. Roll-temperature uniformity across a 1.2 m engraved calender should remain within ±2 °C to avoid edge shrinkage. Batch melt flow rate is controlled to 23–27 g/10 min; resin lots above 27 g/10 min shift the bonding window downward and increase roll-wrap risk. The stabiliser package contains 0.05–0.10% hindered phenolic antioxidant and 0.03–0.06% phosphite processing stabiliser to limit thermo-oxidative degradation during repeated heating cycles.
In a 40 g/m² through-air bonded acquisition distribution layer composed of 60% PP-SF-DS-1.5-38-SK and 40% PET, liquid strike-through time is influenced by fabric density, bonding area, and basis weight. Fabrics with density near 0.045 g/cm³ may show strike-through times of 1.5–2.5 s for synthetic urine under INDA/EDANA NWSP 70.3.R1 (15). Rewet below 0.2 g is attainable when the acquisition layer is combined with an 18 g/m² PP spunbond topsheet. These values are configuration-dependent and require pilot trials on the target diaper assembly.
For calendar-embossed topsheet applications at 14–18 g/m², the product is drylaid and bonded at 150 °C roll temperature. The low finish load reduces residue transfer to embossing rolls; continuous runs on a 3.0 m line can exceed 8 h before roll cleaning is required. Fuzz formation is governed by bonding point geometry and fabric basis weight; the product is compatible with bonding areas of 10–15%. Skin contact is further evaluated by ISO 10993-10:2021 for sensitization and by OECD 439 for reconstructed human epidermis irritation.
Sanitary towel cover stock commonly uses a blend of 70% 1.5 dtex fibre and 30% 2.0 dtex fibre to increase void volume. Cover sheets of 15–22 g/m² produced from this blend show adequate tensile strength for converting, with machine-direction tensile strength above 15 N/5 cm at 20 g/m² after thermal bonding, measured by ISO 9073-3:1989. The blend ratio does not require a different finish level because the surface chemistry is controlled at the fibre-production stage.
Extracts prepared per ISO 10993-12:2021 in polar and non-polar vehicles are tested for cytotoxicity under ISO 10993-5:2009. Skin irritation is assessed using OECD 439; a mean tissue viability above 50% is required for non-irritant classification. The product dossier includes batch-specific extractable data and is aligned with OEKO-TEX Standard 100 class I for baby articles. The fibre is not intended for implantation, wound contact, or prolonged mucosal use without additional device-level validation.
Unlike bicomponent PP/PE sheath-core staple, this monocomponent grade has no polyethylene sheath. The absence of a PE sheath avoids a secondary melting peak at 125–135 °C and improves thin-web loft after through-air bonding. However, the bonding window is narrower than bicomponent PP/PE and requires calender temperature control within ±2 °C. This characteristic makes the product suitable for converters that can control oil-heated roll uniformity but less suitable for older water-heated calenders with wide temperature swing.
The product is delivered in compressed bales with individual bale weights of 200–250 kg and bale density from 0.35–0.45 g/cm³. Bale dimensions are matched to automatic bale openers on high-speed diaper lines; this reduces manual handling and maintains fibre opening consistency across bale changes. Bale-end markers record crimper settings, finish pump rates, and extractable results for traceability.
Storage below 40 °C and 60% RH is recommended. Polypropylene does not hydrolyse, but surface finish distribution may change under condensation. If the fibre is stored at 75% RH or above, equilibrium moisture remains below 0.1%; however, condensed water on fibre surfaces can increase carding friction and should be prevented. Outdoor storage is not advised because the fibre contains no UV stabiliser beyond processing antioxidant.
The product should not be combined with amine-based additives, chlorinated solvents, or strong oxidising agents during downstream finishing. These chemicals can accelerate thermo-oxidative degradation and shift melt flow rate beyond the specified 23–27 g/10 min processing envelope. Carding equipment should use fibre-compatible lubricants; contact with rust inhibitors and mineral-oil greases can create extractable contamination that invalidates the low-extractable profile of the finished fabric.
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