Combining a compound and master batch for strong and durable stadium seats

A project with a tight deadline and strict quality requirements: De Monchy was the right partner

In the spring of 2021, the seats in the stadium of Dutch football club Sparta Rotterdam were in urgent need of replacement. The once red, black and white chairs had become faded, pink and grey. The club therefore decided to replace more than 7,500 stadium seats with new ones, based on a strong and future-proof material.

Stadium seats have to meet a lot of requirements: The seats are used intensively, and must have a high stiffness and impact resistance. In addition, the chairs are fire-retardant, color-retaining and UV-resistant for longer quality retention. Sparta Rotterdam wanted to be assured of a solution that was representative for the club and that could last for years. Therefore, Sparta approached a supplier and manufacturer for their new seats. The manufacturer for the new seats came to De Monchy with their challenge of selecting the proper material.

The challenge

The first challenge was the choice of material. Normally, a compound was used, in which the additives for UV resistance, for example, were already incorporated. The customer had already tested with a standard polypropylene with 30% glass fiber, but after adding the masterbatch, this material failed the mechanical test. It was clear that a special, mechanically stronger solution was needed. Paul Hendriks, Business Unit Manager of the Thermoplastics department and project manager on the project, also noted that for such a project, a standard compound had a major drawback: a lack of flexibility. The specific application, a project requiring a one-off large print run in specific colors, required a fast, customer-specific solution.

This necessity for speed immediately presented the second challenge. The tight deadline of the project called for a solution that could be delivered quickly, but was fully tested and secure. Fortunately, De Monchy was already in the picture as a reliable and knowledgeable partner, with the right portfolio of materials and network for this project.

Combining a compound and master batch for strong and durable stadium seats
Combining a compound and master batch for strong and durable stadium seats

The solution

When the demand for a plastic with such requirements came in at De Monchy, Paul Hendriks immediately started looking for a product that could meet all the requirements. The choice was soon made for a glass fiber filled polypropylene (PPH). To ensure that the end product in combination with the additives would not become too brittle, De Monchy opted to work with Polykemi to supply POLYfill PPH GF5030 HC, which is 30% glass fiber filled PPH. To further improve the mechanical properties, this product is highly crystalline (the HC in the product name stands for High Crystallinity).

Johan Sonesson, Sales Representative at Polykemi, explains further: "By choosing a highly crystalline material, which is also additionally reinforced with fiberglass, we were able to achieve the required hardness and stiffness of the product. This way the seats can withstand the force of the football fans." In addition, Polykemi has taken an environmentally friendly solution into account: The production of this Polypropylene is accompanied by very low CO2 emissions compared to other plastics. The product also has a low density, which makes the chairs lightweight. This makes transport and maintenance easier.

The masterbatch for the seats was developed in collaboration with Gabriel-Chemie. The masterbatch, which adds color to the plastic and imparts UV-protective, fire-retardant and color-retaining properties to the product, was supplied in three colors as a combination masterbatch. This means that the stadium seats meet the M3 fire standard, which is in compliance with local fire regulations.

The advantages

The solution that De Monchy provides has several important advantages for the customer. De Monchy can achieve a much faster delivery time by opting for the separate plastic compound and masterbatch. In this case, because of the tight deadline, that was extra important. Because the masterbatch has already been homologated, and has already been tested in combination with POLYfill, the solution could be delivered faster and the supply conditions could be simplified. Because the basic material is always the same, and only a customer-specific color needs to be added, it is not necessary to do additional testing in follow-up projects. The entire project, including coordination, was completed in 6 weeks.

De Monchy takes care of the customer's challenges by choosing a homologated solution. The quality of the plastic was of extra importance in this project. The stadium seats have to deal with enthusiastic football fans, and therefore have to be able to take a high load of pressure. In addition, they must be able to retain their color for a long time and be fire-retardant. The UV resistance also played an important role: the stiffness of a plastic always decreases over time due to the influences of UV radiation, and by adding a UV protector this decrease in quality is further inhibited. This way, the chairs last longer, and Sparta Rotterdam supporters can enjoy their new places for a long time to come.

The customer is very satisfied with the material-masterbatch combination delivered, and is looking forward to further projects in which De Monchy's knowledge can be applied again.


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