The production process of low-halogen nitrile gloves is more complicated than that of ordinary nitrile gloves, which is mainly reflected in the control of halogen content, selection of raw materials, and optimization of production process. The following is an analysis of the process difficulties, key links and technical challenges:
I. Complexity of production process
1. Strict selection of raw materials
- Acquisition of low-halogen nitrile butadiene rubber latex:
Ordinary nitrile butadiene rubber latex may use halogen-containing initiators, emulsifiers or catalysts (such as chlorine-containing compounds) during polymerization, whereas low-halogen process needs to adopt halogen-free/low-halogen initiation system (such as peroxodisulphate instead of chlorine-containing initiator) or to remove the residual halogen through the purification process at a later stage.
Limitations of matching agents:
Sulfurizing agents, accelerators, antioxidants and other additives need to avoid halogen-containing (such as bromine-containing flame retardants, chlorine-containing vulcanization accelerators), and need to use environmentally friendly additives (such as halogen-free vulcanization systems, silane coupling agents, etc.), which are more costly and more difficult to match the performance of the additives. 2.
2. Halogen control in the production process
-Polymerization process optimization:
NBR polymerization reaction (such as emulsion polymerization) needs to accurately control the temperature, pressure and reaction time, to reduce by-products (such as halogenated hydrocarbons) generation. Low-halogen processes may require extended reaction times or segmented polymerization, increasing energy consumption and process complexity.
Cleaning and purification:
After polymerization, the latex needs to be washed by multi-stage water, centrifugal separation and other processes to remove residual halogenated monomers and additives, ordinary gloves may only need 1-2 times to wash, while low-halogen gloves need 3-5 times or more, resulting in lower production efficiency and increased wastewater treatment costs.
The special characteristics of the drying process:
The drying process needs to avoid the degradation of materials at high temperatures to produce halogen compounds, may need to use low-temperature drying or vacuum drying technology to extend the production cycle.
3. High threshold of quality inspection
- Accurate inspection of halogen content:
High-precision inspection equipment (e.g. ion chromatograph, X-ray fluorescence spectrometer) is required to quantitatively analyze the Cl and Br content of each batch of the product (the detection limit needs to be at the ppm level), while ordinary gloves may only be inspected for their physical properties (e.g. tensile strength and elongation at tear).
Multi-dimensional performance balance:
Low-halogen treatment may affect the mechanical properties of gloves (e.g., elasticity, puncture resistance), and it is necessary to adjust the formula (e.g., adding special plasticizers, reinforcing agents) to balance the low-halogen, high-strength, and comfort, which involves a large number of experiments and parameter optimization.
Key production process steps
Take the typical production of low-halogen nitrile butadiene gloves by leaching method as an example, the process and difficulties are as follows:
1. Latex preparation
-Low-halogen latex preparation:
Select low-halogen nitrile butadiene rubber latex (halogen ≤ 150ppm), add non-halogenated vulcanizing agent (e.g. zinc oxide + sulfur yellow system), non-halogenated accelerators (e.g. hyposulfonamides), antioxidant (e.g. phenyl naphthyl amines), mix well and filter to remove impurities.
-Difficulties: uneven dispersion of additives may lead to incomplete vulcanization or fluctuations in performance, high shear emulsification equipment is required.
2. Mould treatment
-Coating pre-treatment:
Moulds need to be dipped and coated with non-halogenated release agent (e.g. starch or cellulose solution) first to avoid sticking during glove release, ordinary gloves may use halogenated release agent (e.g. chlorinated paraffin).
3. Glove dipping and vulcanization
-Segmental dipping:
Firstly dipping and applying primer (to enhance adhesion), then dipping latex to form the glove body, part of the process need to dipping several times to increase the thickness, and drying after each dipping (temperature ≤80℃, to avoid halogenation reaction).
Vulcanization process:
The traditional nitrile gloves vulcanization temperature is about 120-150℃, while the low halogen process may require low temperature and long time vulcanization (e.g. 100℃×60 minutes) to reduce the decomposition of additives to produce halogen compounds under high temperature.
4. Washing and drying
-Multi-stage washing:
After vulcanized gloves need to be washed with deionized water for more than 3 times to remove residual auxiliaries and soluble halogen compounds, and centrifugal dewatering is required after each washing.
Drying:
use hot air circulation drying (temperature ≤ 90 ℃) or vacuum drying to ensure that the moisture content <1%, to avoid the migration of halogen ions in a humid environment.
5. Testing and packaging
-Halogen testing:
Random sampling of each batch to test the content of Cl-, Br- (if ion chromatography is used, the limits are usually Cl ≤ 900 ppm, Br ≤ 900 ppm, and total halogens ≤ 1500 ppm).
-Performance test:
Tensile strength (≥14MPa), elongation at tear (≥600%), puncture resistance (≥10N) and other indexes should be in accordance with ASTM D6319 and other standards.
III. Technical Challenges and Industry Status
1. Balance between cost and efficiency
Due to expensive raw materials and long process, the production cost of low-halogen process is 20%-30% higher than ordinary nitrile gloves, and the production capacity is reduced by about 15% (e.g. longer washing and drying time).
2.Risk of performance degradation
The vulcanization efficiency of some low-halogen additives is lower than that of traditional halogen-containing additives, which may lead to the decrease of aging resistance of gloves, and it needs to be compensated by nano-fillers (e.g., silica) or composite cross-linking technology.
3. Environmental regulations drive
EU Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive (RoHS), the International Electrotechnical Commission (IEC) and other standards mandatory use of low-halogen materials in the electronic field to promote the upgrading process.
4.High industry concentration
At present, global low-halogen nitrile gloves are mainly produced by Top Glove of Malaysia, Ansell of the United States and other giants. Domestic enterprises such as Lanshan Medical and Ingenics Medical are gradually breaking through the low-halogen technical barriers.
Post time: May-27-2025