Ingredient Dictionary

METHACRYLIC ACID

Methacrylic acid is an alpha,beta-unsaturated monocarboxylic acid that is acrylic acid in which the hydrogen at position 2 is substituted by a methyl group.

How much products actually contain

No product states its amount yet.

Of the products containing it, 2 list it before the 1% line and 0 after it (usually 1% or less).

Products using this ingredient

2 of 2 confirmed · likeliest to carry enough first

Definition

Methacrylic acid is an alpha,beta-unsaturated monocarboxylic acid that is acrylic acid in which the hydrogen at position 2 is substituted by a methyl group. It is functionally related to an acrylic acid. It is a conjugate acid of a methacrylate.

Source: PubChem

US FDA substance register · UNII 1CS02G8656 · registered name Methacrylic Acid · single chemical substance

Source: US FDA Unique Ingredient Identifier (UNII)

Cosmetic roles

Leaves a thin film where appliedFILM FORMING

Safety & regulatory references

Canada

Conditions of Use by product type : (a) Cosmetics that contain more than 5% methacrylic acid (b) Other cosmetics
Warnings and Cautionary Statements: (to the effect of) : (a) "This product contains methacrylic acid, is poisonous, is to be kept out of reach of children" and,"In the case of accidental ingestion, a Poison Control Centre or physician is to be contacted immediately."

Source: MFDS (Korea) cosmetic regulatory information

Korea’s toxic-substance GHS classification: Danger · H311 (category 3) · H314 (category 1A) · H332 (category 4) · +2 more

Source: Korea toxic substances GHS register (NIER)

Other restriction: ban substances that deplete the ozone layer

Source: EU CosIng ingredient list

Reviewed by CIR: Final Report on the Safety Assessment of Methacrylic Acid

Source: US Cosmetic Ingredient Review (CIR)

More data — names, identifiers, properties, test records, literature

Official labels & definitions

JCIA labelling name メタクリル酸: 本品は、次の化学式で表される有機化合物である。

Source: JCIA labelling names (Japan)

Names & identifiers

METHACRYLIC ACIDINCI메타크릴릭애씨드Korean label name (MFDS standard)2-Propenoic acid, 2-methyl-Synonymメタクリル酸Japanese labelling name

CAS No.chemical registry number: 79-41-4
EC No.EU chemical inventory number: 201-204-4
DTXSIDUS EPA chemical ID: DTXSID3025542
DTXCIDUS EPA compound ID: DTXCID505542

IUPAC: 2-Methylprop-2-enoic acid
Molecular formula: C4H6O2
Molecular weight: 86.09 g/mol

Measured properties

Appearance: Methacrylic acid appears as a clear colorless liquid (or low-melting solid) with a pungent odor. Corrosive to metals and tissue. Flash point 170 °F. Melting point 61 °F. May polymerize exothermically if heated or contaminated. If the polymerization takes place inside a container, the container may rupture violently. Less dense than water. Vapors heavier than air. Used to make plastics. · Methacrylic acid, stabilized appears as a clear colorless liquid with a pungent odor. Corrosive to metals and tissue. Combustible. Flash point 170 °F. Melting point 61 °F. May polymerize if contaminated or heated. If polymerization takes place inside a closed container, the container may violently rupture. Less dense than water and is soluble in water. Vapors heavier than air. Used to make plastic
Odour: Acrid, repulsive odor
Boiling point: 325 °F at 760 mmHg (NTP, 1992) · 325 °F at 760 mmHg (NIOSH, 2024)
Melting point: 61 °F (NTP, 1992) · 61 °F (NIOSH, 2024)
Solubility: greater than or equal to 100 mg/mL at 63 °F (NTP, 1992) · 9 % at 77 °F (NIOSH, 2024)
Density: 1.015 at 68 °F (USCG, 1999) - Denser than water, will sink · 1.02 (Liquid) (NIOSH, 2024) - Denser than water, will sink
Stability: Acrylic acid and methacrylic acid readily polymerize in the presence of light, heat and oxygen, and also under the action of oxidizing agents such as peroxides.
Viscosity: 1.38 mPa.s at 24 °C · 1.38 (24℃, mPa s)
Dissociation constant: pKa = 4.65
Colour: colourless
Melting/freezing point: 16 ℃
Initial boiling point and range: 159~163 ℃
Flash point: 171 ℉
Upper/lower flammability or explosive limits: 8.8 / 1.6 %
Vapour pressure: 0.99 ㎜Hg (25℃)
Water solubility: 89 (20℃, g/L)
Vapour density: 2.97
Relative density: 1.0153 (20℃/4℃)
n-Octanol/water partition coefficient (Kow): 0.93
Molecular weight: 86.09

Values measured on the substance itself. The KOSHA data are a reference for writing and reviewing safety data sheets, not a specification for a commercial raw material.

Source: PubChem · KOSHA safety data sheets (Korea)

What products actually use it for

What the 23 products reported to the US EPA with this ingredient use it for. Products outside cosmetics are included, so the top few rows are its main uses.

Monomers6
Intermediate3
Adhesion/cohesion promoter3
Processing aids not otherwise specified2
Surfactant (surface active agent)2
Binder2
Elasticizer2
Photosensitive agent1

2 other uses

Cleaning agent1
Film former1

Source: US EPA CompTox dashboard

Irritation and sensitisation studies

8 skin studies and 3 eye studies are on record.

Classed as highly irritating1

The study conclusions largely agree (100%). These tests are on the raw material itself; irritation at the amount in a finished product is a different question.

See all 11 studies

Category 8.2B (Category 1B)
Skin Irritation · Read Across
Not likely to be sensitizing
skin sensitisation: in vivo (non-LLNA) · Screening · equivalent or similar to OECD Guideline 406 (Skin Sensitisation)
Skin corrosion/irritation - Category 1A
Skin Irritation · Screening
Skin Corr. 1A
Skin Irritation · Authoritative
Skin corrosion - category 1A
Skin Irritation · Screening
Category 1A
Skin Irritation · Screening
Not classified
Skin Sensitization · Screening
Corrosive
skin irritation: in vivo · Screening · OECD Guideline 404 (Acute Dermal Irritation / Corrosion) according to other guideline: DOT Packing Group Classification according to
Category 1
Eye Irritation · Screening
Category 8.3A (Category 1)
Eye Irritation · Read Across
Corrosive or Irritation Persists for > 21 days
eye irritation: in vivo · Screening · other guideline: Draize according to