Curing agents have many uses, and this article will introduce some of the more common ones. These include Silanes, Polyisocyanates, and Polymercaptan. We’ll also cover some other types of curing agents, including crosslinking and coupling agents. For more information, please refer to our selection chart. It is designed to help you choose the right curing agent for your project.
Crosslinking
In the lamination-curing process, crosslinking/coupling reactions are necessary for achieving optimal cure. Curing agents can be used to promote or inhibit these reactions. In a study, the effects of organic peroxides on cure behavior were studied. Curing time, torque time, and cure rate were measured. It was discovered that high concentrations of peroxides cause more free radical generation. These agents may also lead to increased curing time.
One example of a crosslinking/coupling agent is EVA-33/Peroxyester peroxide. This agent has a low half-life temperature and is very effective in induced crosslinking reactions. In the current study, the MH value of this compound was comparable to that of a standard MgO/No system. It also showed the highest curing activity.
Silanes
A silane is a chemical compound that is a popular curing Polymercaptan Resin in adhesives. It is commonly used in the bonding process of polyurethanes and in a number of formulated products. It can also serve as an adhesion promoter. In addition to promoting adhesion, silanes improve a variety of physical properties, including chemical resistance, dimensional stability, and tensile strength.
There are two types of surface film structures that silanes can form. The first is a thin, water-adsorbed layer, while the second forms a thicker layer made of Si-O groups bonded to the surface and silane units that form part of the bulk network. Further reaction of the group with solution phase silane molecules suggests a thicker film. Similarly, silane films may be thick or thin depending on the concentration of silane precursor.
Polyisocyanates
The ethylene oxide unit of a polyisocyanate curing agent is introduced at a concentration of 0.1 to 40% by weight. In addition, the curing agent may also contain one or more hydrophobic groups with an active hydrogen containing group, preferably 0.1 to 3.0 mmol/g. Polyisocyanates are polar compounds, and a lower NCO number means a lower cross-linking density and lower bonding strength.
The polyisocyanate prepolymer reacts with a blocking agent, such as lactam, to form a partially blocked polyisocyanate. It is then metered into the reaction zone. It is important to note that the blocking agent is based on the amount of “free” isocyanate functionality in the prepolymer, which is intended to include the excess mole equivalent of the isocyanate.
Polymercaptan
Polymercaptans are well known curing agents for epoxy resins. They are used in a variety of applications including consumer adhesives, industrial adhesives, coatings, sealants, patch kits, and floor repair kits. These agents are also excellent for encapsulation and sealing applications. Here are some useful properties of mercaptans. The most notable of these is its ability to cure epoxies in less time than conventional hardeners.
Polymercaptans are compounds with three or more hydroxyl groups. They are a popular curing agent for epoxy resins and other products that contain acrylic resins. Polymercaptans are extremely difficult to formulate, so many other polymers are used instead. Polymercaptans with a molecular weight of 20,000 are particularly difficult to formulate. However, many polymers with lower molecular weights have the ability to cure a wide range of materials.
Aliphatic polyamines
Aliphatic polyamines are examples of a class of curing agents. These compounds have a broad range of properties. They may include benzyl alcohol, cycloaliphatic polyamines, aromatic polyamines, and heterocyclic polyamines. Most amine formulations use appropriate organic solvents, including benzyl alcohol and toluene. Other exemplary organic solvents include methyl ethyl ketone and acetic acid.
Conclusion
The performance properties of aliphatic polyamines are similar to those of most commercial curing Epoxy Curing Agent. Polyethylene amines, such as m-phenylenediamine, are used for epoxy resin curing. These compounds also improve gloss and thermal stability. A variety of aliphatic polyamines are available for curing epoxy resins, including ethylenediamine, dipropylenediamine, tripropylenetetramine, and tetraethylenepentamine.
