Ethylene-vinyl-acetate (EVA) resin blended foam products have soft, good elasticity, chemical corrosion resistance, and other properties, making them widely used in shoe materials, sound insulation boards, gymnastics mats, sealing materials, and other fields. In the shoe industry, EVA is primarily used in high-end travel shoes, hiking shoes, slippers, sandals soles, and some interior materials.
However, if the production process of EVA is not strictly controlled, it can often result in the presence of harmful substances in the products. Some examples of these substances include formamide, acetophenone, and 2-phenyl-2-propanol.
Source of Harmful Substances
EVA in shoes usually uses azodiformamide (also known as blowing agent AC) as a blowing initiator in the production process and uses dicumyl peroxide (also known as DCP) as a crosslinking initiator. If the foaming temperature is not strictly controlled in the production process, and the appropriate catalyst is not selected, azodiformamide can easily decompose into formamide products, resulting in a higher formamide residue in the product.
As a cross-linking agent, DCP will be decomposed to produce methane, acetophenone, and 2-phenyl-2-propyl alcohol (2-phenylisopropyl alcohol) and other substances in the crosslinking effect. Acetophenone and 2-phenyl-2-propanol have a special odor. If the concentration of the substance in the product is too high, it is easy to cause people’s discomfort and draw attention to product safety.
Harmfulness of Substances
Formamide is classified as a toxic substance for reproduction (CMR) by the European Chemicals Agency (ECHA). Regulation (EC) No 1272/2008 classifies formamide as a Group 1B carcinogenic substance. In 2012, formamide was included in the European REACH regulation Substances of High Concern (SVHC) list.
Acetophenone is an aromatic ketone that has hypnotic properties. According to the relevant provisions of the EU Directive on the classification, packaging, and labeling of dangerous substances, acetophenone is classified as toxic and harmful substances. If accidentally swallowed by children, it can be harmful to the body and can also cause eye irritation. Therefore, it is prohibited for children’s products such as toys. 2-phenyl-2-propanol may have adverse effects on the skin, respiratory tract, mucosa, and central nervous system of users.
Prohibited/Restricted Use of Substances
The European Union’s New Toy Safety Directive (2009/48/EC) prohibits the sale of foam toy puzzle pads containing formamide from 2013. Industry organizations such as CADS and AFIRM have also included it in the restricted use list.
Since 2005, the European Union has reported at least 24 cases of products containing acetophenone and 2-phenyl-2-propanol from multiple causes through the Rapid Alert System for Consumer Non-Food Products (RAPEX). The countries notified are mainly Germany, Italy, Poland, and Slovakia, and the types of products notified are mainly EVA jigsaw floor mats, EVA women’s slippers, children’s rubber sandals, and children’s plastic shoes. These notified products were refused import or recalled by the customs of exporting countries, which caused serious losses to exporting enterprises.
How to Avoid Harmful Substances
To avoid harmful substances in EVA foam materials, it’s important to explore alternative cross-linking agents other than DCP. However, some potential substitutes for DCP are questioned for generating more hazardous byproducts, so the use of alternative substances should be approached with caution.
Additionally, it’s important to reduce the amount of byproducts through strict processing controls, such as closely monitoring the foaming temperature. For all formulations, suppliers must be required to provide safety data sheet documents that comply with the current Globally Harmonized System of Classification and Labelling of Chemicals (GHS) requirements.
About PFI Fareast
Founded in Germany in 1956, PFI boasts extensive experience in textile and garment, PPE and consumer goods industries, with unrivalled track record in footwear and leather goods. We are widely recognised for our industry-leading expertise in providing sustainable supply chain solutions.
As an independent third-party company headquartered in Hong Kong, PFI Fareast offers testing, inspection, audit, consulting and certification services. Our strong team, which thrives on professionalism, reliability, dedication and astuteness, is fully committed to providing innovative, effective and sustainable solutions throughout the whole journey from product development to procurement.