PVC plastisol may look like a simple paste, but a good result needs a balanced formulation. The type and level of resin, plasticizer and additives determine how the paste flows, how it gels and how flexible the final product is. This article outlines the main components of a PVC plastisol formulation and shares the approach behind the phthalate-free plastisol we use in our own production.
1. PVC paste resin
The main component of plastisol is fine PVC paste resin produced by emulsion or micro-suspension. The particle size and distribution of the paste resin affect how it disperses in the plasticizer and the viscosity of the paste. Some formulations combine resins of different particle sizes (for example blending resins) to adjust viscosity.
2. Plasticizer
The plasticizer forms the liquid phase of the plastisol and makes the final product flexible. More plasticizer makes the product softer; less makes it harder. In phthalate-free formulations, DOTP and DOA are the most common plasticizers: DOTP, with its general-purpose character, forms the backbone of the formulation, while DOA supports flexibility in the cold. The plastisol used in our own production is prepared with DOTP or DOA. See our DOTP plasticizer and DOA plasticizer pages.
3. Heat stabiliser
PVC must be protected against degradation when exposed to heat during processing. Heat stabilisers are added to the formulation for this purpose. The stabiliser is chosen according to processing temperature, product colour and application.
4. Pigment and colouring
Plastisol is coloured with pigment pastes or powder pigments. Colour consistency matters especially for products such as labels and patches made in brand colours. Even dispersion of pigment in the plastisol makes the colour look uniform throughout the product.
5. Fillers and other additives
Some formulations use fillers, viscosity modifiers, defoamers or additives that affect surface properties. Their type and level are set according to what the product needs. Each additive can affect the flow of the paste and the properties of the final product, so they should be chosen carefully.
Why does viscosity matter?
The viscosity of the plastisol must suit the processing method. In micro-injection, the paste must be able to fill fine mould details; in spread-coating applications, the flow behaviour that sets coating thickness comes to the fore. Viscosity is adjusted through resin type, plasticizer level and additives. Whether the paste’s viscosity changes over time, its storage stability, is also considered in the formulation.
The ratio logic
In plastisol formulations, amounts are usually expressed per 100 parts of resin (phr: parts per hundred resin). The quantities of plasticizer, stabiliser and other additives are given on this basis. Ratios are set by trial according to target hardness, flexibility and processing behaviour. There is no single “correct ratio”; every product needs its own formulation.
Our approach in our own production
At ASLAB we use plastisol in our own production, in the rubber labels, patches, footwear parts and home products we make by micro-injection. We prepare this plastisol with DOTP or DOA in a phthalate-free formula, and we also prepare the same plastisol as a raw material for companies making their own products. The plasticizer option can be DOTP-based, DOA-based or a blend of the two.
For a quote
Sharing your application, processing method, target hardness or flexibility and plasticizer preference in your PVC plastisol request helps the quote be prepared correctly. Packaging and quantity are clarified in the quote.
Recording the formulation
The components, ratios and preparation method of an approved formulation should be recorded so that later batches can be made with the same properties. When a raw material supplier or grade changes, retesting the formulation is recommended to avoid unexpected changes in product properties.
Noting formulation changes with their date and reason makes it easier for quality teams to trace past batches.
Frequently asked questions
Which plasticizer is plastisol made with?
It can be made with different plasticizers. Our plastisol is prepared with DOTP or DOA and is phthalate-free.
Do you prepare coloured plastisol?
Requests for colour and other properties are assessed at the quote stage according to the application.
Conclusion
A PVC plastisol formulation is a balanced combination of paste resin, plasticizer and additives. See our PVC plastisol page for details, and send your needs via the quote form.