On the formulation sheet of a hot-melt pressure-sensitive adhesive, naphthenic oil usually appears after SIS/SBS, resin, and antioxidants—yet its dosage can reach over 30%. It is, in fact, the component that determines the adhesive's intrinsic performance.
Plasticizers are indispensable in hot-melt PSA production: they markedly lower melt viscosity, improve surface wetting of the adherend, and directly govern tack, holding power, and 180° peel strength. Among the common choices—naphthenic oil, white mineral oil, liquid paraffin, and phthalates—naphthenic oil offers better tack, longer holding time, and higher peel strength, making it the best all-round plasticizer. This is precisely why naphthenic oil is the default plasticizer in SIS-based HMPSAs.
Naphthenic oil is therefore never a "diluent." It is a formulation variable in its own right. Change the batch and the viscosity index shifts; relax the quality standard and product consistency disappears.
Fig 1. Transparent and colorless naphthenic oil
Mineral oils are classified by molecular structure into aromatic, naphthenic, and paraffinic types. Their performance differences in hot-melt adhesives stem from carbon-type composition:
| Indicator | Naphthenic oil | Paraffinic oil | Aromatic oil |
|---|---|---|---|
| Naphthenic carbon CN% | ≥40% (≥50% for high-purity) | Around 30 | 20–40% |
| Compatibility with SBS | Excellent, compatible with the PB block | Moderate, better matched to SEBS | Excellent, but disrupts PS crosslinking points |
| Low-temperature performance | Low pour point, good cold resistance | Good low-temp and aging resistance; weaker processing | Poor, strong staining |
| Light & heat stability | Very low aromatics, good anti-fading | Excellent | Poor; PAHs carry potential carcinogenicity |
Fig 2. A comparison of petroleum processed oils
The saturated ring structure of naphthenes gives the oil properties of both aromatic and straight-chain carbons—compatible with the PB block of SBS for enhanced chain flexibility, yet without destroying the physical crosslinking points formed by PS end blocks. Industry consensus is clear: domestic SBS oil-extended rubber is mainly extended with naphthenic oil, while SEBS more often uses paraffinic oil.
If CN falls short or aromatics run high, the consequences are tangible: cohesion drops, holding power and peel strength weaken in tandem; excessive polar impurities (N/S/O heterocycles) cause fading, aging, and even polymer cracking under sunlight. A formulation can be adjusted; the carbon-type structure of the oil cannot.
For rubber-based HMAs, what separates the grades is not a single viscosity point, but three interlocked dimensions:
1. Low volatility and high flash point Processing temperatures of 160–180°C mean more low-boiling fractions translate into greater evaporative loss, higher hydrocarbon concentration in the workplace, safety concerns, and potential odor from structural breakdown. Low evaporation loss prevents aging-induced shrinkage and extends service life.
2. Light color and low PCA High naphthenic content and extremely low aromatics yield a water-white, clear appearance. With DMSO extractables far below 3%, no carcinogenic tendency labeling is required—deciding whether the product clears the environmental compliance bar for sanitary and maternal/infant applications.
3. Low-temperature performance High viscosity combined with a low pour point preserves mechanical properties and handling/storage operability even in severe cold—the very dimension most likely to trigger complaints in northern winter markets, and the hardest for suppliers to guarantee.
All our naphthenic oil is procured directly from China National Petroleum Corporation (CNPC), branded as Kunlun (KN series) premium naphthenic rubber oil.
This is not a marketing label; it is a three-layer moat:
A 2,500-ton storage capacity—an industry-leading level in China.
Fig 3. Jaour's oil tanks in Taicang factory (3rd factory)
The value of this scale is far more than "large inventory":
The competition in hot-melt adhesives plays out on the surface as bonding strength—but in reality, it is won or lost in the raw materials. Choose the right oil and the formulation has meaning; lock in a stable oil and quality becomes sustainable.
Directly procured from CNPC Kunlun naphthenic rubber oil, secured by 2,500 tons of storage—locking in the certainty of your adhesive, right at the source.
On the formulation sheet of a hot-melt pressure-sensitive adhesive, naphthenic oil usually appears after SIS/SBS, resin, and antioxidants—yet its dosage can reach over 30%. It is, in fact, the component that determines the adhesive's intrinsic performance.
Plasticizers are indispensable in hot-melt PSA production: they markedly lower melt viscosity, improve surface wetting of the adherend, and directly govern tack, holding power, and 180° peel strength. Among the common choices—naphthenic oil, white mineral oil, liquid paraffin, and phthalates—naphthenic oil offers better tack, longer holding time, and higher peel strength, making it the best all-round plasticizer. This is precisely why naphthenic oil is the default plasticizer in SIS-based HMPSAs.
Naphthenic oil is therefore never a "diluent." It is a formulation variable in its own right. Change the batch and the viscosity index shifts; relax the quality standard and product consistency disappears.
Fig 1. Transparent and colorless naphthenic oil
Mineral oils are classified by molecular structure into aromatic, naphthenic, and paraffinic types. Their performance differences in hot-melt adhesives stem from carbon-type composition:
| Indicator | Naphthenic oil | Paraffinic oil | Aromatic oil |
|---|---|---|---|
| Naphthenic carbon CN% | ≥40% (≥50% for high-purity) | Around 30 | 20–40% |
| Compatibility with SBS | Excellent, compatible with the PB block | Moderate, better matched to SEBS | Excellent, but disrupts PS crosslinking points |
| Low-temperature performance | Low pour point, good cold resistance | Good low-temp and aging resistance; weaker processing | Poor, strong staining |
| Light & heat stability | Very low aromatics, good anti-fading | Excellent | Poor; PAHs carry potential carcinogenicity |
Fig 2. A comparison of petroleum processed oils
The saturated ring structure of naphthenes gives the oil properties of both aromatic and straight-chain carbons—compatible with the PB block of SBS for enhanced chain flexibility, yet without destroying the physical crosslinking points formed by PS end blocks. Industry consensus is clear: domestic SBS oil-extended rubber is mainly extended with naphthenic oil, while SEBS more often uses paraffinic oil.
If CN falls short or aromatics run high, the consequences are tangible: cohesion drops, holding power and peel strength weaken in tandem; excessive polar impurities (N/S/O heterocycles) cause fading, aging, and even polymer cracking under sunlight. A formulation can be adjusted; the carbon-type structure of the oil cannot.
For rubber-based HMAs, what separates the grades is not a single viscosity point, but three interlocked dimensions:
1. Low volatility and high flash point Processing temperatures of 160–180°C mean more low-boiling fractions translate into greater evaporative loss, higher hydrocarbon concentration in the workplace, safety concerns, and potential odor from structural breakdown. Low evaporation loss prevents aging-induced shrinkage and extends service life.
2. Light color and low PCA High naphthenic content and extremely low aromatics yield a water-white, clear appearance. With DMSO extractables far below 3%, no carcinogenic tendency labeling is required—deciding whether the product clears the environmental compliance bar for sanitary and maternal/infant applications.
3. Low-temperature performance High viscosity combined with a low pour point preserves mechanical properties and handling/storage operability even in severe cold—the very dimension most likely to trigger complaints in northern winter markets, and the hardest for suppliers to guarantee.
All our naphthenic oil is procured directly from China National Petroleum Corporation (CNPC), branded as Kunlun (KN series) premium naphthenic rubber oil.
This is not a marketing label; it is a three-layer moat:
A 2,500-ton storage capacity—an industry-leading level in China.
Fig 3. Jaour's oil tanks in Taicang factory (3rd factory)
The value of this scale is far more than "large inventory":
The competition in hot-melt adhesives plays out on the surface as bonding strength—but in reality, it is won or lost in the raw materials. Choose the right oil and the formulation has meaning; lock in a stable oil and quality becomes sustainable.
Directly procured from CNPC Kunlun naphthenic rubber oil, secured by 2,500 tons of storage—locking in the certainty of your adhesive, right at the source.
