Hydroxyl silicone emulsion

01

Identify the silicone, active content and emulsifier

The Cosmetic Ingredient Review (CIR) Expert Panel's dimethiconol safety assessment (panel meeting, December 2010) identifies dimethiconol with the CAS numbers 31692-79-2 and 70131-67-8, both describing hydroxy-terminated dimethylsiloxane. It says dimethiconol has a reactive hydroxyl group bonded directly to silicon at the chain ends, that these compounds condense under acid or alkaline catalysis to raise molecular weight and release water, and that the SiOH groups react with alkoxy silanes to form new siloxane bonds. [1]

The assessment reports infrared analysis of dimethiconol at 60% in anionic surfactant emulsions and of dimethiconol/silsesquioxane copolymer (5%) with dimethiconol (20%) in anionic surfactant emulsion, and lists D4 and D5 cyclic siloxanes as impurities in some tested materials. [1]

Editorial calculation: to put 2% dimethiconol into 100 kg of a conditioner using an emulsion with 60% active, add 100 × 2 / 60 ≈ 3.3 kg of emulsion; with a 20% active emulsion you would need 10 kg, so compare offers on price per kilogram of active silicone. [1]

A silicone maker's catalogue shows how such emulsions are specified for industrial use. Shin-Etsu's Silicone Emulsions catalogue groups high-viscosity dimethyl silicone emulsions that include a hydroxyl end-capped grade with 30% non-volatile content (105 °C × 3 h), a base fluid viscosity above 1,000,000 mm²/s at 25 °C and an anionic/nonionic emulsifier, which it says can be used as a raw material in condensation-cure formulations, beside a 34% grade on a 100,000 mm²/s fluid; medium-viscosity grades run at 35–60% non-volatile content on 1,000–10,000 mm²/s fluids, some with reduced low-molecular-weight siloxane, and its reactive emulsions cure with a catalyst or at 200–300 °C. The catalogue marks these as typical, not specified, values. [4] Editorial calculation: if a 30% non-volatile emulsion is treated as 30% silicone (an upper bound, since emulsifier also counts as non-volatile), 2% silicone in a 100 kg batch needs at least 6.7 kg of emulsion, twice the 3.3 kg of a 60% emulsion worked out above; ask for active silicone content separately from non-volatile content. [4]

Give the supplier the silicone type (dimethiconol or other), active content, emulsifier type (anionic, nonionic, cationic), particle size, viscosity of the base silicone, pH, preservative system, intended use (hair, skin, textile, leather), target concentration in your formula, cyclic siloxane (D4, D5, D6) limits, regulatory documents needed (TDS, SDS, COA, INCI, REACH), packaging and quantities.

02

Check use concentrations and safety conclusions

According to the CIR assessment, dimethiconol was reported in 935 personal care products to the US FDA Voluntary Cosmetic Registration Program in 2010, that the ingredients reviewed function as skin or hair conditioning agents in its Table 1, and an industry survey reported use in body and hand creams, lotions and powders at 0.004% to 36%. The Expert Panel concluded that dimethiconol and its esters and reaction products are safe as cosmetic ingredients in the present practices of use and concentration described in the assessment. [1]

Ruihe lists hydroxyl silicone emulsion RH-5311 (INCI dimethiconol) for personal care, with an average particle size of 3 µm, film-forming and conditioning claims, packing in 25 kg and 200 kg drums, COA with each batch and SDS and TDS on request, and states that the grade is cosmetic-only and not for food, medical or rubber manufacturing. [2]

Editorial note: the CIR conclusion covers cosmetic use; for textile or leather finishing, ask for the SDS, cyclic siloxane content and any restricted-substance declarations your customers require.

Cyclic siloxane impurities carry a legal limit in rinse-off products. Commission Regulation (EU) 2018/35 added entry 70 to REACH Annex XVII: octamethylcyclotetrasiloxane (D4, CAS 556-67-2, EC 209-136-7) and decamethylcyclopentasiloxane (D5, CAS 541-02-6, EC 208-764-9) shall not be placed on the market in wash-off cosmetic products at a concentration equal to or greater than 0.1% by weight of either substance after 31 January 2020, where wash-off products are those washed off with water after application under normal conditions of use. The legislation.gov.uk text shows the entry as it stood on 31 December 2020; ask the supplier whether later EU amendments apply to your market. [3]

Editorial calculation: in the conditioner example above, 3.3 kg of 60% emulsion in a 100 kg batch is 3.3% of the product, so if the emulsion were the only source of D4, its D4 content would need to stay below 0.1 ÷ 3.3 × 100 ≈ 3.0% of the emulsion to keep the rinse-off product under 0.1%; ask for measured D4 and D5 values on the COA. [3] [1]

03

Compare what suppliers offer

Suppliers linked to this page list hydroxyl silicone emulsions; each card links to the page reviewed.

Listings include hydroxyl, methyl and elastomer silicone emulsions alongside hydroxy and other silicone oils.

04

Trace the emulsion components

This is a functional reference built from the sources cited; it is not one maker's formula.

05

Fill the specification fields with values for your formula

A hydroxyl silicone emulsion quotation needs values for your formula. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

06

Send the silicone, formula and compliance needs together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Silicone: [dimethiconol; active %; base viscosity]
Emulsion: [emulsifier type; particle size; pH]
Use: [hair; skin; textile; leather; level in formula]
Compliance: [INCI; SDS; COA; D4/D5/D6]
Stability: [temperature; shelf life]
Supply: [pack size; quantity]

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