Fiberglass antenna radome One of the primary materials used in anti-corrosion projects is vinyl ester resin 901. Here, we will provide a brief introduction to vinyl ester resin 901.

English name: epoxide resin; epoxy resin, abbreviated code EP 。

    Vinyl anti-corrosion resin It is a general term for organic compounds containing two or more epoxy groups in their molecules. With a few exceptions, molecular compounds generally have relatively low molecular weights.

When working with vinyl ester resins, the first three physical concepts you encounter are, from three different perspectives… The epoxy value describes the number of epoxy groups contained in the epoxy resin.

Epoxide value: per The amount of substance of epoxy groups contained in 100 g of resin.

Epoxy group content: per Mass of epoxy groups contained in 100 g of resin (g) 。

Epoxide equivalent: contains The mass of 1 mol of cyclic epoxy resin (in grams):

The three quantities can be converted into one another using the following equation:

Epoxy group content (%)                100

Epoxide value =                      =                   ( 2-1)

Epoxy group molecular weight Epoxy equivalent

In the equation, the molecular weight of the epoxy group is 43.

(1) Vinyl anti-corrosion resin The curing agent—epoxy resin itself is a thermoplastic linear structure. The formulation cannot be used directly; a second component must be added to the resin at a specified temperature. Only after the crosslinking and curing reaction is carried out under specified conditions, resulting in a three-dimensional network‑structured polymer, can it… Use—this second component is called a curing agent. It is used for… Vinyl 901 resin The curing agent can generally… They are classified into three categories. The first category comprises polyamines, including aliphatic primary amines and aromatic primary amines. Adducts of amines with epoxides, cyanoethylated products of amines, phenol or formaldehyde with… amine condensation products, tertiary amines, secondary amines, amides, imidazoles, boron–fluoride amine complexes, and Aminoboranes, among others. Another category comprises anhydride curing agents. Yet another category consists of low-molecular-weight resins.     Classes, such as low-molecular-weight polyamides, phenolic resins, and aniline - Formaldehyde resin, melamine Formaldehyde resins and urea-formaldehyde resins, among others, are curing agents that can reduce the brittleness of epoxy products. Increase impact strength.

Vinyl 910 resin amines differ from anhydride-based curing agents in the following ways.

① Amine-based curing agents are generally more expensive, whereas anhydride-based curing agents are relatively cheaper.

② Amine-based curing agents have a short pot life, whereas anhydride-based curing agents have a long pot life.

③ Amine-based curing agents can cure epoxy resins at room temperature, and their curing speed is relatively… Fast, but anhydride-type curing agents must be… 120–200 °C is required to cure the epoxy resin, whereas Moreover, the curing rate is relatively slow.

④ Amine-based curing agents are somewhat toxic, irritating to human skin, and can easily cause dermatitis. Acid anhydride curing agents are highly irritating but non‑toxic and do not cause dermatitis upon skin contact.

⑤ Some amine-based curing agents may volatilize due to the exothermic heat released during resin curing, while certain anhydride-based ones… The curing agent may be lost due to sublimation;

⑥ When amine-based curing agents are used, the resin releases a large amount of heat during curing, making the processing conditions difficult to control. The formulation employs anhydride-based curing agents, resulting in low exothermic heat during resin curing and facilitating easier control of the processing conditions.

⑦ Products cured with typical amine-based curing agents generally exhibit poor thermal stability, whereas those cured with anhydride-based curing agents… The cured product exhibits relatively high thermal stability.

(2) Calculation of Curing Agent Dosage

① Calculation of the dosage of primary amine curing agents The dosage of primary amine curing agents can be expressed in terms of epoxy equivalents. Calculated on a molar basis. Each hydrogen atom in the amino group can open one epoxy group. Based on this calculation… The amount used must be calculated to ensure that the cured system exhibits the most suitable properties, with variations not exceeding 10% ~ 20% The amount of primary amine is calculated as follows:

Amine equivalent                

Amount of primary amine =              × 100%

Epoxy equivalent             

        Amine molecular weight x epoxy value   × 100%

= Number of active hydrogens （ 2-2 )

            Amine molecular weight   

= Number of active hydrogens

For example, the epoxy equivalent is 200 of 618# Vinyl resin, using triethylenetetramine (amine Equivalent =146/6 =24.3) is used as the curing agent, then the dosage of triethylenetetramine is as follows:

                    24.3  

Triethylenetetramine dosage = 200 = 1 2.15%.

② Calculation of the dosage of anhydride-type curing agents

The ratio of anhydride dosage to resin amount. (%)=(o． 6 ~ o . 9) ×Epoxide value×Anhydride content Sub-quantity

In the formula, 0.6～ o . 9 Within the specified range, a lower value results in a smaller amount of anhydride used, and the fiberglass reinforced plastic… It exhibits relatively high mechanical properties, but its heat resistance and electrical performance are poor; when the value of is large, the anhydride… At higher loadings, the mechanical properties of fiberglass-reinforced plastic are relatively low, while its heat resistance and electrical properties are comparatively good.