📋 Table of Contents
- Chemical Identity: INCI Name, CAS Number & Molecular Description
- Key Technical Properties
- Connection to Alpha-Methylstyrene (AMS) Monomer
- Industrial & Cosmetic Applications
- Regulatory & Safety Status
- Formulation Tips for Cosmetic Manufacturers
- Sourcing & Supply Chain Considerations
- Frequently Asked Questions
1. 🔬 Chemical Identity: INCI Name, CAS Number & Molecular Description
Hydrogenated styrene/methylstyrene/indene copolymer is a synthetic hydrocarbon resin produced by the catalytic hydrogenation of a terpolymer derived from styrene, alpha-methylstyrene (AMS), and indene monomers. Hydrogenation saturates residual double bonds, dramatically improving color stability, oxidative resistance, and compatibility with polar formulation components.
| Identifier | Detail |
|---|---|
| INCI Name | Hydrogenated Styrene/Methylstyrene/Indene Copolymer |
| Common Abbreviation | HSMI Copolymer |
| CAS Number | 68441-35-0 |
| EC Number (EINECS) | 270-671-4 |
| Chemical Family | Hydrogenated Hydrocarbon Resin (Aromatic / Aliphatic) |
| Monomer Building Blocks | Styrene · Alpha-Methylstyrene (AMS) · Indene |
| Physical Form | Pale yellow to water-white pellets or flakes; low odour |
💡 Why "hydrogenated"? The raw terpolymer of styrene, AMS, and indene retains reactive olefinic double bonds that cause yellowing and oxidative degradation over time. Catalytic hydrogenation eliminates these bonds, yielding a water-white, thermally stable resin well-suited to high-end cosmetic and personal care applications.
2. ⚗️ Key Technical Properties
HSMI copolymer's performance profile stems from its controlled monomer ratio and degree of hydrogenation. Typical commercial grades exhibit the following characteristics:
| Property | Typical Value / Range | Significance |
|---|---|---|
| Softening Point (Ring & Ball) | 80 – 140 °C (grade-dependent) | Determines processing temperature & product hardness |
| Color (Gardner / Hazen) | < 1 (water-white); < 3 (pale yellow) | Critical for transparent cosmetic products |
| Number Average Mol. Wt. (Mn) | 500 – 1,500 g/mol | Influences viscosity, film flexibility & gloss |
| Glass Transition Temp. (Tg) | 30 – 85 °C | Governs hardness and wear resistance at use temperature |
| Saponification Value | < 1 mg KOH/g | Confirms absence of ester linkages - chemically inert |
| Acid Value | < 1 mg KOH/g | Low acidity → excellent stability in emulsions |
| Solubility | Soluble in aliphatic/aromatic hydrocarbons, esters, ketones; insoluble in water & alcohols | Formulation solvent selection guide |
| Oxidative Stability | Excellent (fully saturated backbone) | Ensures long shelf life; no yellowing over time |
✨
Water-White Color
Gardner <1 grades meet the strictest transparency standards for cosmetic applications.
🛡️
Thermal Stability
Withstands hot-pour processing at 90–130 °C without decomposition or discoloration.
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Broad Compatibility
Miscible with carnauba wax, candelilla wax, synthetic waxes, castor oil, and most cosmetic esters.
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Superior Gloss
Creates high-gloss films on lips and nails - a primary reason for its use in premium lip colour.
3. 🏭 Connection to Alpha-Methylstyrene (AMS) Monomer
The quality and performance of HSMI copolymer is fundamentally tied to the purity of its alpha-methylstyrene (AMS) monomer feedstock. AMS (CAS 98-83-9, also known as isopropenylbenzene or 2-phenylpropene) contributes the following critical attributes to the final polymer chain:
⚡
Enhanced Steric Bulk → Higher Tg
The alpha-methyl group on AMS increases chain stiffness, raising the glass transition temperature compared to a pure styrene-indene copolymer. This translates to better wear resistance and harder films in lip products.
🎨
Improved Color After Hydrogenation
High-purity AMS (≥99.5%) minimises coloured impurities in the terpolymer precursor, making it easier to achieve water-white colour after hydrogenation without excessive bleaching steps.
📐
Molecular Weight Tuning
The AMS:styrene:indene feed ratio controls the final Mn and polydispersity of the copolymer. Resin producers rely on consistent AMS supply specifications to maintain batch-to-batch reproducibility.
🔒
Oxidative Stability Enhancement
AMS units in the backbone, once hydrogenated, contribute to a fully saturated segment that resists UV-induced oxidation - vital for outdoor-use and long-wear cosmetic products.
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Upstream Connection
Sinolook Chemical supplies pharmaceutical- and industrial-grade Alpha-Methylstyrene (AMS) - the key monomer feedstock for HSMI copolymer production. Consistent purity ≥ 99.5%, with full COA documentation on every batch.
4. 💄 Industrial & Cosmetic Applications
HSMI copolymer serves as a multifunctional performance ingredient. Its combination of film-forming ability, high gloss, low odour, and excellent wax compatibility makes it indispensable across several sectors.
| Application Sector | Typical Use Level | Primary Function | Key Co-Ingredients |
|---|---|---|---|
| Lipstick / Lip Colour | 5 – 20% | Film-forming, gloss, wear | Castor oil, carnauba wax, candelilla wax |
| Mascara | 2 – 8% | Film reinforcement, curl retention | Acrylate copolymers, beeswax |
| Nail Polish | 3 – 10% | Gloss, adhesion, chip resistance | Nitrocellulose, tosylamide/formaldehyde resin |
| Hair Wax / Pomade | 5 – 15% | Hold, sheen, texture | Petroleum jelly, microcrystalline wax |
| Hot-Melt Adhesive | 15 – 40% | Tackification, cohesive strength | EVA, SBS, paraffin wax |
| Printing Ink / Varnish | 10 – 25% | Gloss, rub resistance, set speed | Aliphatic solvents, nitrocellulose |
5. 🏛️ Regulatory & Safety Status
Hydrogenated styrene/methylstyrene/indene copolymer has been evaluated by major regulatory bodies and is broadly accepted for cosmetic use globally. Formulators and purchasing managers should verify the specific grade and its documentation against their target market requirements.
🇪🇺 EU (Cosmetics Regulation EC 1223/2009)
Listed in CosIng (the EU Cosmetics Ingredient Database) under the INCI name Hydrogenated Styrene/Methylstyrene/Indene Copolymer. Not restricted or prohibited. Suppliers must provide safety data consistent with the SCCS safety assessment framework.
🇺🇸 USA (FDA & PCPC)
Cosmetic ingredients in the US are governed by FDA under the FD&C Act. HSMI copolymer is on the CTFA/PCPC International Cosmetic Ingredient Dictionary. No specific restrictions apply; standard cosmetic GMP and labelling rules govern its use.
🌏 China (NMPA)
China's NMPA (National Medical Products Administration) regulates cosmetic ingredients through the Cosmetic Safety Technical Standard. Importers and domestic manufacturers should verify current listing status in the INCI catalogue maintained by NMPA before commercialisation.
⚠️ REACH (EU)
HSMI copolymer with EC 270-671-4 has been pre-registered under REACH. Suppliers exporting to the EU must ensure their substance is properly registered and an up-to-date Safety Data Sheet (SDS) is provided in the relevant EU language.
✅ Best practice for buyers: Always request a current SDS (GHS-compliant), Certificate of Analysis (COA), and INCI declaration letter from your supplier. For EU imports, additionally request REACH registration number or confirmation of downstream user status.
6. 🧪 Formulation Tips for Cosmetic Manufacturers
Getting the best performance from HSMI copolymer requires attention to processing conditions and co-ingredient selection. The following guidance is based on standard industry practice.
1
Melt at 90–120 °C under gentle agitation
HSMI resin should be added to the wax/oil phase and melted at the appropriate softening-point grade + 20 °C. Excessive heat (>150 °C sustained) can cause slight yellowing in pale grades. Use a stainless steel vessel; avoid prolonged contact with reactive metals.
2
Pre-blend with lipophilic components first
HSMI copolymer is insoluble in water and alcohols. Pre-dissolve it in a portion of castor oil, isododecane, or another lipophilic carrier at elevated temperature before combining with pigment dispersions or active ingredients to prevent heterogeneous mixing.
3
Grade selection by end-product hardness requirement
Use low softening-point grades (80–100 °C) for lip glosses, balms, and pomades requiring a creamy texture. Use high softening-point grades (120–140 °C) for stick lipsticks and hard wax products requiring structural integrity at ambient temperature.
4
Compatibility testing with emollients
While HSMI copolymer is broadly compatible with non-polar emollients, conduct a brief compatibility check when combining with polar esters (e.g., isopropyl myristate) at high levels (>30%), as phase separation may occur depending on the specific grade and temperature profile.
5
Stability testing: heat cycle and light exposure
Finished formulations containing HSMI copolymer should undergo standard stability testing including heat-cycle tests (4 °C ↔ 45 °C, 6 cycles) and photostability assessment under ICH Q1B conditions to confirm no unexpected phase changes or discolouration.
7. 🌐 Sourcing & Supply Chain Considerations
Buyers of HSMI copolymer - whether resin producers or cosmetic manufacturers - should evaluate suppliers on the following criteria:
📄
Documentation Completeness
COA, SDS (GHS), INCI declaration, REACH registration (for EU), Kosher/Halal certificates (if applicable), heavy metals analysis.
🔬
Monomer Purity Traceability
Ask whether the resin producer can confirm the purity specification of their AMS feedstock - ≥99.5% GC purity is the benchmark for cosmetic-grade HSMI resin.
📦
Packaging & MOQ
HSMI resin is typically supplied as pellets or flakes in 25 kg kraft paper bags or multi-layer PE bags. MOQs range from 200 kg (sample/trial) to full container loads (FCL) for high-volume buyers.
🚢
Lead Time & Logistics
China-based AMS monomer suppliers with established resin-producer relationships can offer competitive lead times of 15–30 days for bulk orders, with full export documentation support.
🏭 About Sinolook Chemical & the AMS Supply Chain
Sinolook Chemical Co., Ltd. is a China-based specialty chemical exporter with over a decade of experience supplying industrial and cosmetic-grade monomers and intermediates to manufacturers in 50+ countries. While we supply Alpha-Methylstyrene (AMS) monomer as a primary product, our technical team can assist resin manufacturers and cosmetic formulators with:
- AMS purity specifications and COA documentation for resin production qualification
- Connecting buyers with downstream HSMI copolymer producers in our supply network
- Technical consultation on AMS monomer selection for specific Tg and color targets
- Competitive bulk pricing with flexible terms for long-term partners
8. ❓ Frequently Asked Questions
Q1 - What is the CAS number for hydrogenated styrene/methylstyrene/indene copolymer?
The CAS number is 68441-35-0 and the EC (EINECS) number is 270-671-4. These identifiers are used consistently in regulatory submissions, SDS documents, and customs declarations. Always verify the CAS number matches your supplier's CoA when evaluating a new source.
Q2 - Is HSMI copolymer the same as a styrene-indene resin?
Not exactly. A plain styrene/indene copolymer uses only two monomers. HSMI copolymer incorporates alpha-methylstyrene as a third monomer, which raises the glass transition temperature and enhances thermal stability. The hydrogenation step is the other key differentiator - it saturates double bonds, delivering the superior colour and oxidative stability that makes HSMI suitable for cosmetic applications.
Q3 - Is HSMI copolymer safe for lip products (food contact / ingestion risk)?
HSMI copolymer is widely used in lip cosmetics, and cosmetic-grade material from reputable suppliers meets the purity requirements set by the EU CosIng framework and PCPC guidelines. It is a fully polymerised, hydrogenated material with no free monomer. However, it is not approved as a food additive; "cosmetic-grade" and "food-grade" are distinct classifications. Formulators should rely on the supplier's SDS and ingredient safety file to support their product safety assessments.
Q4 - What is the difference between the various softening-point grades of HSMI copolymer?
Softening point is determined by the molecular weight and monomer ratio during polymerisation. Lower softening-point grades (80–100 °C) are softer and more flexible at room temperature - ideal for lip balms, glosses, and creamy sticks. Higher softening-point grades (120–140 °C) are harder and provide better structural integrity for bullet lipsticks and anhydrous wax bars. Work with your resin supplier to select the appropriate grade for your target product texture and climate zone.
Q5 - How does AMS monomer purity affect finished HSMI copolymer quality?
AMS purity directly impacts resin colour, batch-to-batch consistency, and hydrogenation efficiency. Impurities such as cumene, dimethylstyrene isomers, or peroxides in the AMS feedstock can generate coloured chromophores in the polymer that are difficult to remove even after hydrogenation. Cosmetic-grade HSMI resin producers typically require AMS of ≥99.5% GC purity with controlled peroxide values. Consistent feedstock quality from a reliable supplier is the foundation of a consistent finished resin.
Q6 - Can Sinolook Chemical supply both AMS monomer and HSMI copolymer?
Sinolook Chemical specialises in supplying Alpha-Methylstyrene (AMS) monomer (CAS 98-83-9), which is the upstream feedstock for HSMI copolymer production. We can assist resin producers in qualifying our AMS for their polymerisation processes and provide technical documentation to support regulatory submissions. For buyers seeking finished HSMI copolymer resin, our commercial team can provide sourcing guidance and connect you with qualified resin producers within our supply network. Please contact us for details.
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Looking for High-Purity Alpha-Methylstyrene?
Sinolook Chemical supplies industrial- and cosmetic-grade AMS (CAS 98-83-9) to resin producers and formulators across 50+ countries. Request a quote, sample, or technical datasheet today.
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