Application of Polyisobutylene in Rubber-Based Adhesives and Sealants

Polyisobutylene can be used in adhesives and sealant formulations. Its share of global total consumption is approximately 13% to 15%. Polyisobutylene is particularly well-suited for environments that are sensitive to moisture and require water-insolubility. Typically, low-molecular-weight polyisobutylene is employed as a tackifier or plasticizer, whereas medium- and high-molecular-weight polyisobutylene is used to adjust elasticity, elongation, cohesion, and air tightness. Polyisobutylene products exhibit superior aging resistance compared to rubber-based products and maintain long-lasting adhesion, making them suitable for surfaces to which other polymers cannot adhere.

Polyisobutylene can be used in adhesives and sealant formulations. Its share of global total consumption is approximately 13% to 15%. Polyisobutylene is particularly well-suited for environments that are sensitive to moisture and require water-insolubility. Typically, low-molecular-weight polyisobutylene is employed as a tackifier or plasticizer, whereas medium- and high-molecular-weight polyisobutylene is used to adjust elasticity, elongation, cohesion, and air tightness. Polyisobutylene products exhibit superior aging resistance compared to rubber-based products and maintain long-lasting adhesion, making them suitable for surfaces to which other polymers cannot adhere.

Polyisobutylene exhibits durable adhesion in pressure-sensitive adhesives (PSAs), hot-melt adhesives (HMAs), and hot-melt pressure-sensitive adhesives (HMPSAs). It is compatible with resins, elastomers, and solvents commonly used in adhesive formulations and demonstrates excellent color stability and chemical resistance. Adhesives containing polyisobutylene are widely used in applications such as paper-based laminates, labels, and medical dressings, as well as in the fields of paper, films, foils, and industrial tapes. Polyisobutylene can also serve as an ingredient in skin-penetrating tablet and block-shaped silicone-based pressure-sensitive adhesives. Additionally, it can be employed as a tackifier, plasticizer, and humectant in hot-melt adhesives.

Adding polyisobutylene to sealants can enhance the plasticity of elastomers used to generate cohesion and rubber-like properties. As a primary vehicle for pigments, polyisobutylene ensures that fillers are uniformly wetted and firmly incorporated. Polyisobutylene-filled sealant formulations improve adhesion and weather resistance, as well as enhance water resistance and oxidative stability. Due to its excellent barrier properties and low-temperature elasticity, polyisobutylene is widely used as a raw polymer in window sealants.

Tapes containing polyisobutylene can prevent corrosion of pipelines in underground or underwater environments. Polyisobutylene-based compounds, which contain mineral oil, paraffin, thermoplastic elastomers, and low-density polyethylene, when injected into optical cables, can enhance the cables' resistance to voltage breakdown, moisture protection, and self-healing capabilities.

This sealant is made from a homogeneous blend of PIB with a molecular weight of 80,000, butyl rubber, and paraffin oil, to which ZnO, CaCO3, silicone oil, and bifunctional siloxanes have been added. It has a relative density of 1.5 and, after being stored for 6 months, exhibits an Shore A hardness of 23. This sealant can be used as a sealing layer for the lids of aviation fuel barrels.

A sealing tape was prepared by mixing 21 parts of PIB with a molecular weight of 10,000–15,000, 9 parts of butyl rubber, 24 parts of clay, 30 parts of CaCO3, and 14 parts of the plasticizer DOP. The resulting tape has a non-sticky feel and exhibits excellent processability and filling performance. After being kept at 50℃ for 24 hours, the sealing layer shows no leakage, and its compression set ranges from 12% to 58%. This sealing tape is suitable for sealing corrosion-resistant conduits.