Vinyl Gloves Production Process

Phase 1: Compounding – Crafting the Perfect Formula

The entire process begins with the creation of the primary liquid material, a substance known as PVC sol or plastisol. This is not simply melted plastic; it's a carefully balanced suspension of fine PVC particles in a liquid medium.

1. Raw Material Measurement and Mixing:
   The core ingredients are meticulously measured and combined in large, industrial mixing tanks. These include:

• PVC Paste Resin: The fundamental polymer that forms the structure of the glove.

• Plasticizer: This is a critical component (e.g., DINP, DOTP) that doesn't melt the PVC but rather seeps between its particles. During heating, it helps fuse the PVC into a soft, flexible, and elastic film. Without it, the glove would be rigid and brittle.

• Stabilizer: Protects the PVC from degrading under the high temperatures of the curing oven.

• Additives: Other agents may be included, such as viscosity reducers to control the liquid's flow, colorants to give the gloves their characteristic clear or blue tint, and PU (polyurethane) to enhance the feel and donning properties of the final product.

2. Blending, Filtering, and Deaeration:
   The mixture is stirred continuously for several hours to ensure all components are completely and uniformly dispersed. After blending, the resulting PVC sol is filtered to remove any clumps or impurities. It then undergoes a deaeration process, where it is placed under a vacuum to remove any trapped air bubbles. This step is vital, as even microscopic bubbles could create pinholes or weak spots in the finished glove. The final, smooth, bubble-free sol is then left to mature before being transferred to the production line.

Phase 2: Formation – Shaping the Glove

This phase uses a continuous production line where hundreds of ceramic or metal hand-shaped molds, known as formers, move through a series of stations.

1. Former Cleaning and Pre-heating:
   The production line begins with the formers being thoroughly washed with acid, alkali, and hot water, then dried. This ensures they are perfectly clean, preventing defects in the gloves. The clean formers are then pre-heated before moving to the next step.

2. Coagulant Dipping:
   The heated formers are first dipped into a tank containing a coagulant solution (commonly calcium nitrate). This solution leaves a thin, invisible layer on the former. Its purpose is to help the liquid PVC sol adhere evenly to the former in the next stage, ensuring a uniform glove thickness.

3. PVC Sol Dipping:
   The coagulant-coated formers are then dipped into the tank of prepared PVC sol. The duration of the dip and the viscosity of the sol are precisely controlled to determine the final thickness of the glove. The coagulant causes the PVC sol to gel on contact with the former's surface.

4. Gelation and Curing (Plasticizing):
   As the formers exit the dipping tank, they rotate to allow excess sol to drip off and ensure an even coating. They then enter a long, multi-zone oven.

• Gelation: In the initial, lower-temperature zones of the oven, the PVC sol "gels," transforming from a liquid into a soft, solid mass.

• Curing: In the subsequent high-temperature zones (around 180-200°C), the plasticizing process occurs. The heat causes the plasticizer to be fully absorbed by the PVC resin, fusing the particles into a strong, seamless, and permanent elastic film. Precise temperature control is essential for achieving the desired strength and flexibility.

Phase 3: Finishing and Refinement

Once the glove has been formed and cured, it undergoes several finishing steps to prepare it for use.

1. Leaching and Cooling:
   After exiting the curing oven, the hot gloves on the formers are passed through a series of water tanks. This leaching process washes away residual chemicals and proteins, making the glove purer and more skin-friendly. This step also serves to cool the gloves down.

2. Beading (Cuff Rolling):
   The formers are then rotated against brushes or rollers at the cuff area. This action rolls the still-pliable cuff edge back on itself, creating a thickened "bead." This beaded cuff significantly strengthens the glove, makes it easier to don without tearing, and helps prevent liquids from running down the user's arm.

3. Surface Treatment (Optional):
   To make the gloves easier to put on and take off (donning and doffing), an internal surface treatment is often applied. The most common methods are:

• PU (Polyurethane) Coating: A thin layer of polymer is applied to the glove's interior, creating a smooth, non-tacky surface.

• Chlorination: The gloves are washed in a chlorine solution, which hardens the surface at a molecular level, reducing its natural tackiness.

Phase 4: Finalization and Quality Assurance

The final steps involve removing the gloves from the formers and ensuring they meet stringent quality standards.

1. Stripping (Demoulding):
   The finished gloves are removed from the formers. This can be done manually by workers or, more commonly, by automated systems that use jets of air to blow the gloves off the formers and into collection bins.

2. Quality Control and Inspection:
   This is a critical final stage. Batches of gloves are subjected to a battery of tests to ensure they meet regulatory and performance standards (e.g., ASTM D5250 for medical vinyl gloves). These tests include:

• Water Leak Test: Gloves are filled with one liter of water and visually inspected for any leaks, which would indicate pinholes.

• Visual Inspection: Checking for any defects like stains, tears, or inconsistencies.

• Physical Property Tests: Measuring dimensions, thickness, tensile strength (how much force it can take before breaking), and ultimate elongation (how much it can stretch).

3. Packaging:
   Once a batch has passed quality control, the gloves are counted and stacked by automated machines, placed into dispenser boxes, and sealed. These boxes are then packed into shipping cartons, ready to be distributed for use in industries around the world. For medical-grade gloves, a sterilization step (e.g., gamma irradiation) may occur after packaging.