Reasons for tasteless and tasteful BIPB and DCP

Thermal decomposition process of DCP:

In the structural diagram of DCP, we can see that the isopropyl phenoxy radical generated after the peroxide bond breaks during the thermal decomposition of DCP can also form methyl radical and acetophenone. acetophenone is a substance with an unpleasant smell and is harmful to human health, which is why DCP has an unpleasant smell during the cross-linking process and the finished product when it is used as a cross-linking agent for the polymer. It can be seen that the smell of DCP is not due to the residue of DCP or impurities, so there is no argument that the higher the purity of DCP, the smaller the smell.

BIPB thermal decomposition process:

It generates alkyl radicals, which react with free polymer matrix. We can see that the cross-linked small molecule products of BIPB are:

Methane (CH4)...... Gas

Acetone...... Volatile

Tert butyl alcohol...... Volatile

The rest are odorless solid compounds, so there is little or no odor in the cross-linking process and finished products of BIPB.

Advantages, disadvantages and solutions of BIPB

In addition to the similar structure, there is another important reason why BIPB is called tasteless DCP. It can be replaced almost where DCP can be used. The rubber properties of BIPB instead of DCP, including hardness, breaking strength, elongation, tear strength, oil resistance and aging coefficient, are basically the same. However, BIPB is superior to DCP in compression deformation at high temperature.

But BIPB has a significant disadvantage, that is, the price is too much higher than DCP, which is the biggest factor limiting the wide use of BIPB. The use of BIPB in Europe is much higher than that in DCP. With the strengthening of environmental awareness of domestic producers and consumers, the demand for BIPB in China is increasing.

Another major disadvantage of BIPB is that when BIPB is used as the crosslinking agent of EPDM, it is easy to spray crystal (note that it is spray crystal, not frost). It will be shiny when exposed to light, but DCP will not. This is due to the poor compatibility between the decomposition products of BIPB and EPDM. If your products are exported to foreign countries, especially in Europe, you can rest assured that customers will know that you are using a good curing agent and gladly accept it. If you want to solve this spray crystal phenomenon, there are two main methods:

1. Add PEG4000 into the formula;

2. Reducing the amount of BIPB and adding part of bis (2,5) is equivalent to reducing the decomposition products of BIPB without affecting the crosslinking efficiency.

There are successful examples of these two schemes. Of course, some manufacturers use BIPB as cross-linking agent for EPDM without crystal spraying, perhaps because some of the additives restrict the crystal spraying. The specific reason is unknown.

Thermoplastic rubber TPV also uses BIPB as the crosslinking agent, but with the increasing requirements of the automotive industry for odor, that is, after using BIPB, the odor may not meet the requirements, and further treatment is needed, such as chemical/physical adsorption, devolatilization, drying and other processes to reduce the odor.