Master SBS, SIS Based Hot-melt Adhesive Formulas in 10 Minutes ——A Guide to HMA Formulation Expertise 1. Hot Melt Pressure Sensitive Adhesive (HMPSA) Hot Melt Pressure Sensitive Adhesive (HMPSA) is a solvent-free, pollution-free pressure-sensitive adhesive that exhibits adhesive properties immediately after cooling following application in a molten state. The main material is thermoplastic rubber, and it also requires the addition of tackifying resins, plasticizers, and a small amount of other components. It is prepared by melting and mixing at elevated temperatures (160-200 °C). It can be applied in a molten state, and a light finger pressure can quickly achieve adhesion, while also allowing for easy removal and not contaminating the surface of the bonded materials. It has now been widely used. 2. Application of Petroleum Resin in HMPSA 2.1 SIS-Based PSA Styrene-Isoprene-Styrene (SIS) block copolymer has excellent cohesion and adhesion properties, making it an excellent primary adhesive for hot melt pressure-sensitive adhesives. The compatibility between petroleum resins and SIS is very good, mostly pressure-sensitive adhesives are produced by blending two different grades of SIS. Hot melt pressure-sensitive adhesives made with C5 resins as tackifiers exhibit high peel strength and holding power but relatively poor initial tack. Patent CN102604570A discloses a hot melt pressure-sensitive adhesive for HDPE self-adhesive rolls, composed of the following raw materials by mass fraction: 18%-21% thermoplastic elastomer, 2%-5% composite elastomer, 15%-24% first polyisobutylene, 10%-12% second polyisobutylene, 30%-40% first C5 petroleum resin, 5%-12% second C5 petroleum resin, 5%-12% third C5 petroleum resin, and a trace amount of antioxidant. This hot melt pressure-sensitive adhesive effectively utilizes the high and low-temperature stability of SIS, the excellent adhesion of composite elastomers, and the low high-temperature viscosity conducive to coating application, resulting in a product that is resistant to both high and low temperatures while exhibiting excellent room temperature performance, surpassing conventional hot melt pressure-sensitive adhesives. The process is simple, requiring no special production equipment, resulting in low manufacturing costs and no complex or difficult pretreatment processes. Patent CN102093831A discloses a hot melt pressure-sensitive adhesive with the following composition: 35-70 parts of SIS; 20-70 parts of tackifying resin (selected from rosin resin, terpene resin, C5 petroleum resin, and hydrogenated petroleum resin, or a combination thereof); 40-80 parts of plasticizer (selected from liquid paraffin, Tween 80, dibutyl phthalate, lanolin, castor oil, and naphthenic oil, or a combination thereof); and 1-5 parts of antioxidant and/or anti-aging agent (selected from microcrystalline wax, propyl gallate, and rubber accelerators, or a combination thereof). This hot melt pressure-sensitive adhesive has moderate adhesion performance, good antioxidant capability, a low softening point, and good drug compatibility. Additionally, the invention also discloses the preparation method of this hot melt pressure-sensitive adhesive and its application in the preparation of traditional Chinese medicine plasters. Patent CN103074013A discloses a hot melt pressure-sensitive adhesive composed of 20%-22% natural rubber, 10%-11% petroleum rubber, 25%-30% petroleum resin, 15%-20% terpene resin, 2%-3% polyisobutylene, 14%-15% naphthenic oil, 3.0%-3.5% rubber accelerator, and 1%-3% anti-aging agent. This technology maintains the holding power of SIS-based pressure-sensitive adhesives while improving the low-temperature flexibility and initial tack of the adhesive. Patent US5869562 A discloses a HMPSA adhesive formulation that can be applied to the covers of books. The adhesive comprises 20%-30% of the adhesive material, which is a blend of two different grades of SIS, with the styrene content in the SIS molecular chain ranging from 15% to 25%. The tackifying resin is composed of more than one solid resin (making up 30%-60% of the tackifying resin, with a melting point of 70-150 °C) and a liquid resin or a modified liquid elastomer (making up 20%-40% of the tackifying resin). The liquid elastomer can be selected from polybutadiene, polyisobutylene, or polypropylene, or a blend of these. This pressure-sensitive adhesive enhances the deformation resistance of polyolefin films. Patent US20030168165 discloses a HMPSA adhesive formulation designed for use in disposable hygiene products. This hot melt pressure-sensitive adhesive is a blend of two or more SIS types, with one SIS having a styrene content of 15%-22% in its molecular chain, and the other having a styrene content of 26%-32%. The adhesive material constitutes 10%-40% of the formulation. The formulation also includes at least one tackifying resin, a plasticizer, an antioxidant, and a wax. This adhesive is particularly suitable for disposable hygiene products, such as women's sanitary napkins, adult or baby diapers, etc. The tackifying resins in the formulation can include C5 and C9 petroleum resins or their derivatives, as well as C5/C9 copolymer petroleum resins. 3.2 SBS-Based PSA SBS (Styrene-Butadiene-Styrene) thermoplastic elastomer combines the solubility and thermoplasticity of polystyrene (PS) with the flexibility and resilience of polybutadiene (PB), exhibiting characteristics of both thermoplastic plastics and vulcanized rubber. These properties arise from the thermodynamic incompatibility between the PS end blocks and the PB mid-blocks. The PS end domains are in a glassy state at room temperature, acting as rigid cross-linking points, while above the PS flow temperature, the PS becomes flowable, breaking the cross-links and allowing for plastic processing. These characteristics make SBS an important raw material for the preparation of pressure-sensitive adhesives. Common tackifying resins used in HMPSA include rosin resin, terpene resin, and petroleum resin. The compatibility of these tackifying resins with SBS varies. Wang Yu and others conducted a study from an industrial perspective, focusing on the relationship between the structural differences of tackifying resins and their performance. The results indicated that when the softening point of the tackifying resin is between 1.0-10 °C, the corresponding HMPSA can achieve lower melt strength and higher peel strength, with an initial tack of 1-2 cm. When the softening point of the tackifying resin is 10 °C, the peel strength follows the order: HMPSA with terpene resin > HMPSA with rosin resin > HMPSA with petroleum resin. When the weight fraction of tackifying resin is 210% (relative to the SBS elastomer), the overall performance of HMPSA with petroleum resin is inferior to that with rosin resin (or terpene resin). At this point, the melt viscosity of HMPSA is below 10,000 mPa/s, but the holding power increases (indicating enhanced cohesion). Jing Peng and others used hydrogenated C5 petroleum resin as a tackifier for HMPSA, adding plasticizers and a small amount of antioxidants and anti-aging agents to prepare an environmentally friendly hot melt pressure-sensitive adhesive. By measuring the initial tack, melt viscosity at 180 °C, and peel strength, they obtained the optimal formulation for the hot melt pressure-sensitive adhesive. The results indicated that when the mass fraction of hydrogenated C5 petroleum resin is 40%, plasticizer is 35%, SBS is 20%, and the additives (antioxidants and anti-aging agents) are 5%, the performance of the hot melt pressure-sensitive adhesive meets industry standards and can be effectively applied in industries such as labeling and hygiene products. Patent CN 103102854A discloses a high-temperature resistant hot melt pressure-sensitive adhesive composed of 12%-13% natural rubber, 12%-13% petroleum rubber, 20%-22% petroleum resin, 20%-22% terpene resin, 10%-11% alkyl phenol formaldehyde resin, 14%-15% naphthenic oil, 3.0%-3.5% rubber accelerator, and 1%-3% anti-aging agent. This technical solution maintains the solubility, thermoplasticity, flexibility, and resilience of S15 series pressure-sensitive adhesives while improving the high-temperature softness and adhesion of the adhesive. Patent CN102618194A discloses a hot melt pressure-sensitive adhesive for high-speed automatic labeling, composed of 40%-45% petroleum resin, 35%-45% SIS, 10%-15% naphthenic oil, 2%-5% calcium carbonate, 1%-3% polyethylene wax, and 1%-2% antioxidant. It also describes the preparation method for the hot melt pressure-sensitive adhesive. This adhesive has the advantages of being environmentally friendly and low-cost, while also exhibiting high initial tack and holding power, with excellent die-cutting performance, making it suitable for high-speed automatic labeling. Lu Yancheng and others used styrene and isoprene as modifiers, with anhydrous AlCl3 as a catalyst, to synthesize C5 petroleum resin through cationic polymerization. They analyzed the factors affecting the wax haze point, softening point, and yield of the resin. The results indicated that by using 10% styrene, 15% isoprene, 2% catalyst, and an appropriate amount of solvent, a high-grade C5 petroleum resin could be synthesized with a wax haze point of 92 °C, a softening point of 87.5 °C, and a Gardner color value not exceeding 2. This product can be used as a tackifier resin directly in the preparation of hot melt adhesives and pressure-sensitive adhesives. If you have any interest of SIS, SBS, SEBS, SEPS, or SSBR materials, feel free to send a private message or leave a comment in the comment section. Our technical staff will provide product recommendations accordingly.