Aluminum Chlorohydrate (ACH)

Chemical formula: Al₂(OH)₅Cl·2H₂O

CAS No.: 12042-91-0

Molecular weight: 210.48g/mol

 

Properties:

Aluminum Chlorohydrate (ACH) is an inorganic macromolecular compound as a white powder. Specific gravity is 1.33-1.35g/ml (20℃). It is easy to dissolve in water, and the solution shows a colorless or tawny transparent liquid with corrosion.

Aluminum hydroxychloride, as a highly effective antiperspirant and antibacterial agent, possesses distinct structural characteristics and outstanding application properties. It appears as a colorless to slightly yellow transparent liquid (50% by mass) or a white spray-dried powder (purity ≈92%). A 15% aqueous solution exhibits a pH of 3.8~4.3. Heavy metal content is strictly controlled: Lead (Pb) ≤ 2 ppm, Arsenic (As) ≤ 1 ppm. It complies with ICH Q3D requirements, ensuring good safety and regulatory compliance.

Specification:

Description:

The mechanism of action for aluminum hydroxychloride manifests in three primary aspects.

First, it induces reversible pore occlusion. Al³⁺ rapidly crosslinks with carboxyl groups in skin keratin, forming 20-50 nm gel plugs that seal sweat ducts. This reduces sweat secretion by 40-60% within 30 minutes.

Second, its astringent and antibacterial action effectively inhibits the growth of pathogenic bacteria such as Staphylococcus and Bacillus in a pH 4-4.5 environment, reducing body odor intensity by ≥70% within 24 hours.

Third, its mild buffering properties. The inherent hydroxyl groups in its molecular structure eliminate the need for additional acidification adjustments. Franz cell testing (48 hours) shows a skin permeation rate < 0.05 μg・cm⁻²/h. This falls below the EU safety threshold of 0.6 μg/g, demonstrating excellent biocompatibility.

Application:

1. Antiperspirant

Aluminum Chlorohydrate (ACH) is primarily used in the cosmetic field for antiperspirant applications, accounting for over 80% of its global consumption. Formulations and processing methods for different dosage forms accommodate diverse usage requirements.

For roll-on formulations, the composition consists of 8-15% ACH, 15% ethanol, and 5% propylene glycol. Processing via ball milling at 30°C yields a clear, stable product ensuring uniform texture and easy application.

Spray formulations employ a base composition of 6-10% ACH and 55% anhydrous ethanol. After canning, 15% propane/butane is added as the propellant. The spray angle is controlled at 45°, with a drying time < 15 seconds, enabling rapid film formation and a dry, non-sticky finish.

For stick formulations, Aluminum Chlorohydrate (18-22%) is blended with stearyl alcohol (20%) and cyclopentasiloxane (18%). After hot filling at 85°C and cooling, this process prevents “white residue” during use while balancing antiperspirant efficacy and user experience.

2. Deodorant

In roll-on and wipe formulations, aluminum chlorohydrate (ACH) delivers a simple yet highly effective deodorizing solution. With 3-5% ACH as the core ingredient, synergistically blended with 0.5% decanediol, it achieves ≥80% deodorizing efficacy for 24 hours. This efficacy has been validated by EU Cosmetics Claim Validation. Combining mildness with regulatory compliance, it is suitable for daily deodorant care scenarios.

3. Oil-Control and Pore-Minimizing Serum

This astringent oil-control serum represents another key cosmetic application of aluminum hydroxychloride (ACH). Its formula is precisely tailored for oily and acne-prone skin: a blend of 0.5-1% ACH combined with 2% niacinamide, adjusted to a pH of 4.2-4.5, delivers immediate skincare benefits— — reducing pore diameter by 8% and facial shine by 25%. This formulation leverages ACH's astringent properties while harnessing niacinamide's conditioning effects, delivering both oil control and skin texture improvement.

4. Post-Shave Soothing Lotion

Aluminum Chlorohydrate (ACH) delivers gentle astringent and soothing effects. Formulated with 0.3-0.8% ACH combined with 1% panthenol, it effectively inhibits seepage from razor-induced micro-wounds. Delivers astringent and calming benefits. Clinically proven to reduce skin stinging scores by 30%, meeting post-shave sensitivity care needs. Alleviates discomfort and promotes skin condition restoration.

Usage:

The application of aluminum hydroxychloride (ACH) in cosmetic formulations requires strict control over addition conditions, pH range, compatibility, and stability to ensure functional efficacy and product uniformity.

1. Addition Stage

ACH should be added to aqueous systems at ambient temperatures up to 50°C. If the system temperature exceeds 60°C, hydrolysis readily occurs, forming aluminum hydroxide (Al(OH)₃) precipitates. This reduces active aluminum content by 15%, significantly diminishing the product's core efficacy.

2. pH Optimization

The optimal pH range for the final product is 3.8~4.5. This range maximizes the antiperspirant and astringent functions of ACH. If pH adjustment is required, slowly neutralize the system using triethanolamine or aminomethylpropanol. Avoid local pH values exceeding 5.0, as this may cause white haze formation, which compromises product appearance and performance.

3. Compatibility Requirements

Formulation design must avoid coexistence with carbonate and phosphate components in the same phase to prevent reactions forming aluminum phosphate (AlPO₄) and aluminum carbonate (Al₂(CO₃)₃) precipitates.

Addition levels of strong chelating agents such as EDTA and sodium citrate must be spaced apart by more than 0.2%. Otherwise, aluminum ions (Al³⁺) will be chelated and immobilized, reducing antiperspirant efficacy by 20-30%.

ACH exhibits good compatibility with cationic guar gum and polyquaternium-10. These ingredients can synergistically enhance thickening effects. When formulating with xanthan gum, pre-dispersion treatment is required to prevent agglomeration and ensure system uniformity.

4. Stability Testing Standards

The product must undergo rigorous stability validation. After 12 weeks of accelerated aging at 45°C, the decrease in Al¹³⁺ content within the system must be less than 5%. pH drift must not exceed 0.2. After freeze-thaw cycling tests (-20°C to 25°C, 3 cycles), no precipitation should form. The median particle size (D₅₀) must be less than 50 nm. Performance stability and appearance consistency must be ensured across different storage environments.

Packing:

Solution: 1000L IBC, 200L plastic drums, or 1,4000-2,4000L flexitank. Solid powder: 25kg fiber drums/multiwall paper bags.

Packing and handling: Storage tanks and piping for Aluminum Chlorohydrate (ACH) solutions should be constructed of materials recommended for corrosive products. FRP, PVC, HDPE and/or rubber are the materials of choice for piping and storage tanks. Metering pumps and other equipment that comes in contact with concentrated solutions of Aluminum Chlorohydrate (ACH) must also be constructed of acid-resistant materials such as PVC, rubber, Teflon, ceramic, and Hastolly C. No wetted parts should contain any metals such as carbon steel, stainless steel, brass or aluminum.

Slightly corrosive, non-toxic, non-dangerous article and non-contraband. Safety protection and processing Aluminum Chlorohydrate (ACH) solution. While on the job, wear goggles long sleeves rubber gloves.

Transportation:

General transportation method.

Synonyms:

Aluminum Hydroxychloride; Aluminum chloride hydroxide; Aluminum chlorhydrol; Aluminium Chlorohydrate; Aluminum (III) chloride pentahydroxide; Dialuminium chloride pentahydroxide; Hydroxyl aluminum chloride ACH; Basic Aluminum Chloride; Polyaluminum Chloride; MICRO-DRY SUPERULTRAFINE; MICRO-DRY ULTRAFINE; REACH 101 AND 103; REACH 301; REACH 501; locron extra; locron flakes; locron powder; locron solution; wickenol 303/321/323/324; astringen; aloxicoll.