Chlorinated rubber is a rubber derivative obtained by chlorinating natural rubber or synthetic polyisoprene rubber. The chlorination process involves complex reactions such as addition, substitution, and cyclization, ultimately yielding a polymer with an irregular cyclic structure [1]. Its chlorine content is approximately 65%, and its empirical structural formula is (C10H11Cl7)n. Due to the strong polarity and chemical inertness of the C–Cl bond, chlorinated rubber exhibits excellent resistance to chemical corrosion, abrasion, flame retardancy, water resistance, and adhesion. It has been widely used in anticorrosive coatings, including marine paints, road-marking paints, printing inks, architectural coatings, and coatings for offshore oil platforms [2]. In fact, chlorinated rubber demonstrates outstanding adhesion to both metals and polymers, making it a promising candidate for use as an adhesive. Currently, research on chlorinated rubber adhesives remains limited, and their applications are mainly documented in patent literature.
1. Properties of chlorinated rubber

Chlorinated rubber has a highly polar molecular structure yet exhibits excellent water resistance, with a water absorption rate of only 0.1% to 0.3% [2]. At the same time, its molecular chains contain rigid cyclic structures that restrict molecular motion, resulting in significantly lower permeability to water vapor and oxygen compared to most polar polymers (such as acrylates, epoxy resins, and alkyd resins)—only about one-tenth that of alkyd resins [3]. Consequently, corrosive media such as water and oxygen find it extremely difficult to penetrate through the chlorinated rubber membrane and attack base materials like steel. As an adhesive, chlorinated rubber also effectively prevents moisture from damaging the bonding interface.
Due to its high chlorine content, chlorinated rubber possesses a relatively high cohesive energy, resulting in a film with brittle properties. Therefore, plasticizers are typically added to improve its brittleness. Commonly used plasticizers include chlorinated paraffin, chlorinated biphenyl, and phthalates [4, 5]. Chlorinated rubber exhibits excellent adhesion to polar interfaces such as metals. However, for interfaces with weaker polarity (e.g., natural rubber and styrene-butadiene rubber), excessively strong polarity can actually hinder bonding. Consequently, depending on the characteristics of the materials to be bonded, it is often necessary to use polymer blends in conjunction with chlorinated rubber to achieve effective adhesion between metals and various other materials. Chlorinated rubber can be compounded with chloroprene rubber, nitrile rubber, phenolic resins, alkyd resins, acrylic resins, polyurethanes, and other polymers [4, 6–10] to prepare different types of adhesives. Chinese patent CN 101418197 A discloses a chloroprene adhesive modified with chlorinated rubber; the incorporation of chlorinated rubber enhances the adhesive strength on polar surfaces such as metals [6]. According to U.S. Patent US 4,256,615 [8], the addition of an appropriate amount of chlorinated rubber to a two-component castor oil-based polyurethane adhesive can significantly improve both initial tack and ultimate bond strength.
Like other chlorinated polyolefins, chlorinated rubber readily loses hydrogen chloride at high temperatures. Thermal degradation studies have shown that between 160 and 390 °C, chlorinated rubber undergoes dehydrochlorination, forming a conjugated structure and turning yellow; between 390 and 585 °C, chlorinated rubber primarily undergoes oxidative degradation [11]. In humid and hot environments, it begins to decompose at as low as 60 °C [3]. Therefore, chlorinated rubber products must be compounded with heat stabilizers that can absorb the trace amounts of hydrogen chloride released during decomposition, thereby preventing further catalytic acceleration of the dehydrochlorination process. Commonly used heat stabilizers include lead soaps, epoxides, organic phosphites, and aliphatic polyamines [4, 12]. In the presence of appropriate stabilizers, chlorinated rubber can be used in heat-resistant adhesives.
2. Interaction at the Interface Between Chlorinated Rubber and Metal
One of the major application areas for chlorinated rubber as an adhesive is bonding between metals and rubber. Therefore, understanding the interaction between chlorinated rubber and metal interfaces is of great significance for designing adhesive formulations. Feliu S et al. studied the interaction of a commercial chlorinated rubber paint (soluble in xylene, containing aluminum oxide and silica fillers—specific formulation details are undisclosed) with metal surfaces including copper, aluminum, stainless steel, cold-rolled steel, and zinc [13]. The study found that chlorinated rubber exhibited the strongest adhesion to polyvinyl chloride, with no chemical changes observed at the interface. On the other hand, zinc metal can degrade C–Cl bonds, forming ZnCl2 and thus resulting in the lowest adhesion strength. For copper and cold-rolled steel, some Cl− was also formed at the interface, leading to the formation of a weak interfacial layer rich in hydrocarbons; however, their adhesion strength remained higher than that of zinc. As for aluminum and stainless steel, due to the easy formation of passivation layers on their surfaces (composed of Al2O3 or chromium-based protective coatings), the amount of Cl− generated by degradation was minimal, resulting in higher adhesion strengths. Liu XW et al. investigated the anti-corrosion effects of different coating systems on carbon steel and found that a zinc-rich primer followed by a chlorinated rubber topcoat led to more severe corrosion than a chlorinated rubber coating applied alone [14]. The likely reason for this phenomenon is the degradation of chlorinated rubber caused by zinc. When an epoxy intermediate coat was introduced between the two coats, the corrosion resistance was significantly enhanced. These findings indicate that metallic zinc has a relatively strong destructive effect on chlorinated rubber coatings, whereas chlorinated rubber exhibits better adhesion on inert interfaces such as aluminum and stainless steel.
Gao Shouchao et al. used X-ray photoelectron spectroscopy to investigate the elemental composition at the interface between chlorinated rubber and metal, finding that the adhesion between the two materials relies solely on van der Waals forces without any chemical bonding occurring [15]. Increasing surface roughness promotes adhesion by enhancing the contact area between the two phases [16]. Some studies have also shown that the rust layer on steel surfaces can degrade chlorinated rubber, releasing Cl− ions, which in turn catalyze the degradation of the coating [17]. A humid environment accelerates this degradation process [18]. In practical applications, the addition of fillers such as glass flakes can significantly reduce the water vapor permeability of the coating. Research by Berio M et al. indicates that after incorporating anti-corrosion pigments like zinc phosphate, the water absorption rate of the coating actually decreases [19]. Moreover, many anti-corrosion pigments—such as aluminum tripolyphosphate and zinc phosphate—can form a dense passivation film on the steel surface [3], thereby reducing the corrosive effect of the metal on chlorinated rubber. However, research on the interfacial interactions between chlorinated rubber and metal in these complex systems containing anti-corrosion pigments remains scarce.
3. Chlorinated rubber adhesive
3.1 Applications in Metal-Rubber Bonding
The bonding of metals to rubber finds extensive applications in fields such as aerospace and automotive engineering. For instance, oil seals for engines and flexible joints for solid-propellant rocket nozzles both involve the bonding of metals to rubber. Chlorinated rubber, thanks to its excellent chemical inertness, can meet the requirements for oil-resistant and high-temperature-resistant adhesives when appropriately formulated.
Chinese Patent CN 101421370 A discloses an oil- and high-temperature-resistant adhesive used for bonding polyacrylate rubber to degreased cold-rolled steel sheets, primarily intended for oil seals in engines and transmission systems [20]. This adhesive is formulated by dispersing 45–75% by weight of phenolic resin (the same applies hereinafter), 5–25% of chloroprene rubber, and 10–30% of metal oxides (zinc oxide and titanium dioxide) in a solvent. If the amount of chloroprene rubber in the formulation is reduced or omitted altogether, the adhesion to metals will be insufficient and the bond will easily peel off. Conversely, if the amount of chloroprene rubber is excessive, the adhesion to polyacrylate rubber will be inadequate, and the interface will also tend to peel. By properly adjusting the ratio between these two polymers, it is possible to obtain an adhesive interface with a bonding strength greater than that of the polyacrylate rubber itself; moreover, the fracture interface can be entirely composed of polyacrylate rubber, reaching a 100% coverage rate.
U.S. Patent No. 2,459,742 discloses a nitrile rubber-metal adhesive [21] characterized by the incorporation of 1–5% by weight of aliphatic polyamines (such as tetraethylenepentamine, diethylenetriamine, and triethylenetetramine) mixed with a chlorinated rubber solution. After curing, the adhesive’s bonding strength remains unchanged even after being immersed in gasoline for more than 10 weeks. The polyamines serve to absorb hydrogen chloride—a degradation product—and crosslink the chlorinated rubber adhesive layer, thereby enhancing the adhesive’s oil resistance. This adhesive is suitable for bonding aircraft fuel tanks and metal components.
U.S. Patent No. 3,108,035 discloses a single-component chlorinated rubber solvent-based adhesive composed of 100 parts of chlorinated rubber, 5 to 200 parts of lead dioxide (preferably 60 parts), and 2 to 30 parts of diphenylquinone dioxime (preferably 10 parts) [22]. After curing at temperatures ranging from 149 to 177 °C, the adhesive exhibits varying bond strengths depending on the type of rubber used. For nitrile rubber and chloroprene rubber, the adhesive achieves a peel strength of 27 kg/cm; for natural rubber and styrene-butadiene rubber, the peel strength is 25 kg/cm; and for butyl rubber bonded to steel, the adhesive strength is 16 kg/cm. The influence of different rubbers on bonding strength is also evident in U.S. Patent No. 4,994,519, which discloses a rubber-metal adhesive whose main components are chlorinated rubber and brominated poly(dichlorobutadiene), with the addition of p-benzoquinone dioxime and sulfur as vulcanizing agents [23]. The bonding strength of this adhesive to rubber and steel decreases in the order of nitrile rubber, styrene-butadiene rubber, and natural rubber. Clearly, chlorinated rubber adhesives are highly effective for bonding polar rubbers to metals.
3.2 Applications in Fiber-Reinforced Rubber Domains
Fiber-reinforced rubber is primarily used in transmission systems, such as timing belts and conveyor belts for automobile engines. The operating environment of these components often involves high temperatures (above 100°C), which necessitate that the fiber-rubber adhesives employed be able to withstand such high temperatures. In recent years, high-temperature and oil-resistant rubbers, such as hydrogenated nitrile rubber and chlorosulfonated polyethylene, have been widely adopted in the manufacture of conveyor belts. The reinforcing fibers commonly used in these applications include glass fiber, polyester, and nylon. To enhance the adhesion between the fibers and the rubber matrix, the fibers typically undergo a three-step treatment process: First, the fiber surface is activated using an epoxy compound or an isocyanate; next, a latex emulsion composed of resorcinol-formaldehyde-rubber (RFL) is applied; finally, a chlorinated rubber-based adhesive is coated onto the surface. Among these steps, the third adhesive layer plays the crucial role of providing strong bonding between the fiber and the rubber matrix.
Chinese Patent CN 101671959 A discloses a treatment agent for preparing glass fiber cords used in the reinforcement of rubber [24]. (Prior to using this treatment agent, the fibers must be pre-treated with an RFL emulsion.) This treatment agent enhances the adhesion between glass fibers and materials such as chlorinated polyethylene and hydrogenated nitrile rubber, thereby improving the service life and heat resistance of automotive engine timing belts. The treatment agent contains components including chlorosulfonated polyethylene, chlorinated rubber, and isocyanates; the specific formulation is shown in Table 1. As can be seen from the table, the treatment agent formulated with both chlorinated rubber and chlorosulfonated polyethylene exhibits superior adhesive strength and hot-water resistance compared to using either component alone.

Table 1. Adhesive Formulations and Performance for Glass Fiber and Hydrogenated Nitrile Rubber Interfaces [24]

Table 2. Adhesive Formulation and Performance for the Interface Between Polyester Fiber and Hydrogenated Nitrile Rubber [25]

U.S. Patent No. 5,219,902 also discloses an adhesive for fiber-reinforced hydrogenated nitrile rubber (including fibers such as polyester, polyaramid, and nylon) [25]. This adhesive contains (hydrogenated) nitrile rubber and chloroprene rubber (typically used in equal weight ratios) along with toluene solvent (with a solid content of 10%). Before using this adhesive, the fibers must be activated with isocyanates and coated with an RFL emulsion. Table 2 presents the performance of polyester-hydrogenated nitrile rubber composites prepared using this adhesive. After being treated at 140°C for 7 days, the adhesive strength remained remarkably good—superior to that achieved when either nitrile rubber or chloroprene rubber was used alone as adhesives. In conveyor belts made from this composite material, after operating at 120°C for 220 hours, cracks appeared in the rubber. By contrast, the control sample exhibited fiber delamination (Table 2), indicating that its adhesive strength was insufficient.
Japanese Patent JP 02258653 discloses an adhesive composed of hydrogenated nitrile rubber, chlorinated rubber, and isocyanate, which is used to enhance the adhesion between glass fibers and rubber for the production of high-performance rubber products [26].

3.3 Applications in Other Fields
Chinese Patent CN 102153965 A discloses a room-temperature-curing adhesive for high-temperature-resistant conveyor belt joints, along with a method for its preparation [27]. This adhesive uses chloroprene rubber, chlorinated rubber, and isocyanates as the primary film-forming substances. It can bond the overlapping surfaces of conveyor belts at room temperature, with a surface-drying time ranging from 1 to 10 seconds. Its average shear strength is 3 MPa, and its average tensile strength is 2.5 MPa. The adhesive exhibits excellent high-temperature resistance: after aging at 200°C for 12 hours, it still maintains a shear strength of 1.55 MPa and a tensile strength of 1.45 MPa. This adhesive enables conveyor belt joints to withstand temperatures up to 180°C.

John N et al. studied rubber adhesives used for bonding wood chips [28]. The basic composition of these adhesives consists of chloroprene rubber and chlorinated rubber. When the amount of chlorinated rubber ranges from 0% to 30%, the bonding strength increases almost linearly; however, once the chlorinated rubber content exceeds 30%, the bonding strength begins to decline (see Figure 1). When chlorinated rubber is used in combination with natural rubber, the bonding strength is at its lowest, and increasing the amount of chlorinated rubber has little effect on the bonding strength.
4. Conclusion
Chlorinated rubber boasts water resistance, strong polarity, and chemical inertness, making it compatible with a wide variety of polar polymers. When appropriate thermal stabilizers are added (to prevent dehydrochlorination), the resulting adhesives exhibit high bonding strength, oil resistance, and high-temperature durability. Metal-rubber products and fiber-reinforced rubber products prepared using chlorinated rubber adhesives have found promising applications in areas such as automotive oil seals and engine belts. Currently, most available application data come from patent literature; systematic studies on how the intrinsic properties of chlorinated rubber—such as molecular weight and molecular weight distribution—affect bonding performance remain lacking. The emergence of high-viscosity chlorinated rubber (i.e., high-molecular-weight chlorinated rubber) holds great potential to further enhance its adhesive properties, leading to chlorinated rubber adhesives with even superior performance.