This document summarizes and compares the definitions of VOCs, SVOCs, and TVOCs in coatings, and lists the requirements of relevant product standards for architectural coatings and water-based wood coatings.

VOC , Concept Analysis of SVOC and TVOC

VOC is the abbreviation for volatile organic compounds. Common indoor sources of volatile organic compounds include building materials, carpets, printers, furniture, paint thinners, adhesives, cosmetics, some sprays, and plastic products.

The main components of VOCs are: hydrocarbons, halogenated hydrocarbons, oxygenated hydrocarbons, and nitrogenated hydrocarbons.

Semi-volatile organic compounds (SVOCs) mainly include dioxins, polycyclic aromatic hydrocarbons, pyridines, quinolines, nitrobenzenes, phthalates, anilines, phenols, and other compounds. These organic compounds mainly exist in the form of gas or aerosol in ambient air.

SVOCs are more difficult to degrade in the environment than VOCs, and they can be adsorbed onto particulate matter, easily absorbed by the human body, causing harm.

I. VOC Definition

Table 1 below lists the VOC-related terms according to the national standards GB/T 5206-2015 "Paints and Varnishes - Terminology and Definitions" and GB/T 35602-2017 "Green Product Evaluation - Coatings".

Table 1: Relevant VOC Definitions from National Standards

Chinese Name	English Abbreviation	Definition
Volatile Organic Compound	VOC (volatile organic compound)	Any organic liquid and/or solid that can naturally evaporate at normal temperature and pressure in the surrounding atmospheric environment.
Volatile Organic Compound Content	VOCC (volatile organic compound content)	The mass of volatile organic compounds present in the coating measured under specified conditions.
Semi-volatile Organic Compound	SVOC (semi-volatile organic compound)	Any organic liquid and/or solid that evaporates more slowly than volatile organic compounds at normal temperature and pressure in the surrounding atmospheric environment.
Total Volatile Organic Compound Emission Level	TVOC (total volatile organic compounds emission level)	The total mass of volatile organic compounds with retention times between n-hexane and n-hexadecane (including n-hexane and n-hexadecane) on a non-polar chromatographic column, using adsorption tube sampling under specified simulated coating (including coating) actual release environment.

 

However, VOCs have different definitions in different international organizations. One category is the general definition of VOCs, i.e., volatile organic matter, or volatile organic matter under certain specific conditions; the other category is the environmental protection definition, i.e., the type of volatile organic matter that causes harm (volatilization and participation in atmospheric photochemical reactions). See Table 2 below for details:

Table 2: VOC Definitions from Different International Organizations

American ASTM D3960-98	Any organic compound that can participate in atmospheric photochemical reactions.
US Environmental Protection Agency (EPA)	Except for CO, CO2, H 2 CO3, metal carbides, metal carbonates, and ammonium carbonate, any carbon compound that participates in atmospheric photochemical reactions.
International Standard ISO 4618/1-1998	At normal temperature and pressure, any organic liquid and/or solid that can spontaneously evaporate. When determining the VOC content, any organic compound with a boiling point or initial boiling point less than or equal to 250℃ under normal pressure conditions is specified.
German DIN55649-2000
World Health Organization (WHO, 1989)	A general term for volatile organic compounds with a melting point below room temperature and a boiling point between 50 and 260℃.

EU Resolution (EU) 2015/886 stipulates that SVOCs refer to volatile organic compounds with a boiling point between 250℃ and 370℃ at a standard atmospheric pressure of 101.3 KPa, and a retention time between n-tetradecane and n-docosane (including n-tetradecane and n-docosane) on a non-polar chromatographic column. Other organizations also define SVOCs as having a boiling point between 170℃ and 350℃ (due to the ambiguity of the classification basis, there is often an overlap with volatile organic compounds).
II. VOC and TVOC Control Related Standards

Products of different grades or different applications have different VOC limit requirements. The detection of VOC content in water-based architectural coatings and wood coatings shall be carried out according to the provisions of GB/T 23986-2009. Specific product requirements are shown in Table 3 below.

Table 3: VOC and TVOC Limits for Different Product Standards

Index Standard Number	VOC Content (g/l), ≤			TVOC (mg/m 3 ), ≤
Water-based Architectural Coatings	Interior Wall	Exterior Wall	Putty (g/kg)	-	Interior Wall Primer	Interior Wall Topcoat	Interior Wall Putty (g/kg)
GB 18582-2020 "Limits on Hazardous Substances in Wall Coatings for Buildings"	80	100	10	-
HJ 2537-2014 "Technical Requirements for Environmental Labeling Products Water-based Architectural Coatings"	50 (Gloss ≤10) 80 (Gloss >10) 50 (Primer)	100 (Topcoat) 80 (Primer)	10	-
JG/T 481-2015 "Low Volatile Organic Compound (VOC) Water-Based Interior Wall Coating Materials"	20	-	5	A	4.0	3.0	3.0
				A +	1.0
GB/T34676-2017 "Interior Wall Coatings for Children's Rooms"	10	-	-	-
GB/T 35602-2017 "Green Product Evaluation Coatings"	10 (Gloss ≤10) 50 (Gloss >10)	50	5	1.0
Water-based wood coatings	Clear coat	Color paint	Putty	-
GB 18582-2020 "Limits on Hazardous Substances in Wood Coatings"	300	250	Reference color paint	-
GB/T 33394-2016 "Water-based wood coatings for children's room decoration"	80	70	10	-
JG/T481-2015 "Low Volatile Organic Compound (VOC) Water-Based Interior Wall Coating Materials"	120			A	30
				A +	10

The table shows that green products and low-VOC interior wall coating materials have limited requirements for TVOC; GB/T 35602-2017 "Green Product Evaluation Coatings" stipulates that SVOC needs to provide supporting materials but has not yet set specific limits.

Compared with domestic VOC standards, the TÜV Rheinland certification adds the detection of TSVOC (semi-volatile organic compound release), respectively detecting the VOC, TVOC and TSVOC values of the product 3 days, 10 days and 28 days after construction, and the detection unit is ug/m ³ , while the unit of our national standard is mg/m ³ The TÜV Rheinland certification requirements are stricter.

Conclusion: With the global integration of carbon peaking and environmental protection needs, domestic requirements for VOC limits will certainly become increasingly stringent. Controlling VOC emissions is conducive to the coating industry's development of clean production, circular economy, and structural upgrading, and also helps to upgrade and replace products.