Curing agents, also known as hardeners, are essential components of many polymer systems, including Epoxy Resins. Curing agents react with the epoxy resin to form a three-dimensional crosslinked network, resulting in a cured polymer with improved mechanical properties, chemical resistance, and thermal stability. Curing Agent,Epoxy Curing Agent,Curing Agent Coating,Polyether Amines Shanghai Shengduan Trading Co., Ltd. , https://www.shsdchem.com
The theoretical composition of the talc mineral is MgO = 31.72%, SiO 2 = 63.12%, and H 2 O = 4.76%. The silicon contained is sometimes replaced by aluminum or titanium (up to 2% for aluminum and 0.1% for titanium), and magnesium is often replaced by iron , manganese , nickel and aluminum. Containing FeO up to 5%, containing Fe 2 O 3 up to 4.2%, NiO up to 1%. Some contain a small amount of potassium, sodium, and calcium. Substituted by isomorphism can form talc variants with different compositions, such as iron talc Fe 3 [Si 4 O 10 ](OH) 2 , calcite Ca 3 [Si 4 O 10 ](OH) 2 , nickel talc Ni 3 [ Si 4 O 10 ](OH) 2 and the like.
Talc belongs to the orthorhombic column crystal. The fine crystals are hexagonal or diamond-shaped, but rare. It is usually a dense block, leaf or scaly aggregate.
Pure talc is white or slightly yellowish, pink, light green, and light brown. Talc with a darker color is caused by impurities. Glass luster. The dense block talc is a shell-like fracture. The hardness is 1, and the density is 2.58 to 2.83 g/cm 3 . Talc has a smooth feel and high electrical insulation.
According to the use, talc mineral raw materials are divided into two types, namely, block talc and talc powder. The color of the block talc used for carving crafts can beautify, so the impurity-induced coloring element is a beneficial component here. Talc powder for paper and chemical industry requires whiteness. Therefore, the coloring element impurities such as iron, manganese, nickel and titanium contained are harmful components.
Pure talc ore is rare and usually associated with other minerals such as chlorite, magnesite , tremolite , dolomite, siderite, quartz , pyrite. These minerals change the chemical composition of the ore, coloring the ore, and significantly affecting the physical properties of the ore, which in turn reduces its industrial grade.
The types of ore of talc are generally divided into four categories in foreign countries:
(1) Block talc A dense block shape that can be processed into blocks of different shapes of a certain size. Less impurities, talc content of more than 70%.
(2) Flaky soft talc is an alteration product of magnesium carbonate rock. The common associated mineral is chlorite. This is the most versatile ore.
(3) Tremolite talc Sometimes called hard talc, it is a block or layer of rock. Contains different amounts of tremolite, amphibole, calcite , dolomite, serpentine and other associated minerals. This ore is characterized by a high calcium oxide content of 6% to 10%.
(4) Mixed talc is a kind of flaky rock containing talc, dolomite, calcite, serpentine, chlorite, etc. It is white and brittle.
In the country, according to the talc content, it is divided into block talc and talc. The latter has a talc content of less than 70%, which needs to be used for beneficiation . The talc rocks are mainly talc chlorite rocks and talc carbonate rocks. In addition to chlorite and talc, talc chlorite is often accompanied by serpentine, pyroxene, etc. Most of the color is green. The talc carbonate rock associated with talc is magnesite or dolomite, and the color is mostly light gray.
There are several types of curing agents, each with its own unique properties and applications. The most common type is amine-based curing agents, which react with the epoxy functional group to form a secondary amine and an alcohol. This reaction is exothermic and can be accelerated by heat, making it ideal for high-temperature applications.
Another type of curing agent is anhydride-based, which react with the epoxy group to form a cyclic acid anhydride and a hydroxyl group. These curing agents are typically used in applications where water resistance is critical, such as marine coatings and adhesives.
Other types of curing agents include phenolic, acid, and catalytic curing agents. Phenolic curing agents are used in high-temperature applications, while acid curing agents are used in low-temperature applications. Catalytic curing agents are used to accelerate the curing process and are typically used in combination with other curing agents.
The choice of curing agent depends on the specific application requirements, such as cure time, cure temperature, and final properties of the cured polymer. It is important to choose the correct curing agent to ensure that the final product meets the desired specifications.
In summary, curing agents are essential components of many polymer systems, including epoxy resins, and play a critical role in improving the mechanical, chemical, and thermal properties of the cured polymer. The choice of curing agent depends on the specific application requirements and must be carefully considered to ensure the final product meets the desired specifications.
Talc is a layered structure with an aqueous magnesium silicate mineral matter, chemical formula Mg 3 [Si 4 O 10] (OH) 2, an oxide expressed as 3MgO • 4SiO 2 • H 2 O. Because of its soft texture, it has a strong sense of slippery and gets its name. Talc has high electrical insulation, heat insulation, high melting point and strong adsorption properties to oils, so it has a wide range of applications in the industry. And with the development of industry, the amount of use continues to increase, and the scope of application is expanding. China's annual output is nearly 1 million tons, which is used in the paper industry for about 60% of the total output, and the linoleum industry accounts for about 15%. In addition, it is widely used in many fields such as medicine, chemical industry, textile, ceramics and sculpture. Therefore, talc is one of the most important minerals in the national economy.