home > news > company news
formulating epoxy systems: resins and curing agents
when developing a one component heat curable, or two component heat curing epoxy system, we often use the resin system to give it properties. for the resin which is usually designated as part a in a two component epoxy system or isused as is in a one component heat curable epoxy system, we can choose:
双酚f树脂 (bisphenol f resin)
双酚a树脂 (bisphenol a resin)
酚醛清漆树脂 (novolac resin)
脂环族环氧树脂 (cycloaliphatic epoxy resin)
多官能团树脂 (multifunctional resin)
in some formulations, these resins can be used on their own or in combination with other resins to formulate the optimal epoxy system.
when choosing curing agents, in order to help in attaining the desired properties in a wide range of applications, here are some of the options while formulating an epoxy system:
脂肪胺 (aliphatic amines)
脂环族胺 (cycloaliphatic amines)
芳香胺 (aromatic amines)
路易斯酸 (lewis acids)
similarly, when formulating an epoxy system, these curing agents can be combined in certain formulations to achieve the desired effect.
thermal curing of multifunctional epoxy resin
multifunctional epoxy resins are well known for their high glass transition temperatures, high decomposition temperatures, long term high temperature performance and good wet strength performance.
when s-510 is used with anhydride curing agent, the product has a higher tg. with amine curing agent, the weight loss rate is smaller and the processing temperature can be lower. the use of anhydride plus tertiary amine system seems to have both effects.
s-186 has two glycidyl ester groups with excellent adhesion to carbon fibers, and can bond well even to carbon fibers without surface treatment. generally, m-phenylene diamine or liquid tetrahydrophthalic anhydride (70# anhydride) can be used as the curing agent, and the tg after curing is higher.
s-720/mhhpa system exhibits the largest tg. after cured for a prolonged duration, the tgddm/mhhpa system possessed the most excellent performance in heat resistance.
in light of the recent development of tri and tetra-functional epoxy resins, we began to investigate the effectiveness of anhydrides as curing agents for these resins. as our work progressed, certain properties that make these systems well suited for prepreg manufacture, filament winding and pultrusion were revealed.
with the polyfunctional epoxies the ratio of epoxy groups to hydroxyl groups is very high and the initial step of the reaction does not readily occur. therefore, as long as low free acid anhydrides are used, long pot lives can be expected. this is a unique property of anhydride cured systems where in the highly reactive polyfunctional resins exhibit longer pot lives than many conventional epoxies.
a significant advantage to the use of liquid anhydrides is their ability to reduce nux viscosity. many of the polyfunctional epoxy resins are viscous liquids or semisolids. low viscosity anhydrides (60-300 cps) used inratios of approximately 1:1 greatly reduced the viscosity of the resin mix and facilitate processing without the use of solvents or other viscosity reducers.
the polyfunctional resins show better high temperature performance and are stiffer with lower elongation. the shrinkage on cure is significantly higher.
nantong synasia new material co., ltd. has focused on the production and sales of multifunctional epoxy resins for more than ten years. the development of our special epoxy resin provides a guarantee of raw materials for the development of domestic new materials and military enterprises, and makes a certain contribution to the development of domestic new materials to break the monopoly of large foreign companies. at the same time, the synthesis process of these special epoxy resins is independently developed by our company, which means that this type of project has a great competitive advantage in the market.
上一条： the review of the highlights of china composites expo 2020! 下一条： photoinitiators: scope of application for free radical and cationic photoinitiator