Epoxy foam

日期:2022/6/20 8:42:06 / 阅读: / 来源:本站

Epoxy foam
Epoxy resin is a kind of polymer which contains secondary alcohol group and ether bond in the polymer molecular chain and reactive epoxy group at both ends of the molecule. Epoxy resin is a linear macromolecule. Because it contains active epoxy group, hydroxyl group, ether bond, etc. in the molecular structure, it can cross-linking and curing reaction with various types of curing agents, and change the linear structure to the body structure, and the performance changes from thermoplastic to thermosetting. The epoxy foam is made of epoxy resin as base material, adding curing agent, foaming agent, toughening agent, etc. PVDF film production line www.handenr. com
The production methods of epoxy foamed plastics can be divided into chemical foaming method, reactive gas foaming method, physical foaming method and curing method by adding glass or ceramic or plastic hollow microspheres. Epoxy foam is characterized by high temperature resistance and good electrical properties. It can be used as packaging material for electronic components, and also suitable for aircraft and electrical industry. PVDF film production line www.handern. com
1、 Raw materials
1. epoxy resin
Generally, epoxy resin with viscosity (25 ℃) of 7~25pa*s and melting point of 65~155 ℃ is selected. Mainly bisphenol A epoxy resin. PVDF film production line www.handern. com
2. curing agent see table 8-17 for common curing agents of oxygen foam plastics. Table 8-17 types of common curing agents for epoxy foam plastics
Fatty primary amine triethylenetriamine, triethylenetetramine, tetraethylenetriamine, dimethylaminopropylamine, diethylaminopropylamine, aminoethyl ethanolamine fatty polyamine N-aminoethyl piperazine aromatic polyamine aldehyde resin m-phenylenediamine; 4,4 diaminodiphenyl sulfone; 4.4-diaminodiphenylmethane; 2,4,6-tris (dimethylaminomethylphenol) for aniline; Benzyl dimethylamine Lewis acid boron trifluoride ether ester, boron trifluoride ethylamine integrated anhydride phthalic anhydride, maleic anhydride, pyromellitic anhydride
3. foaming agent
The foaming agent used for epoxy foams is the same as that used for phenolic foams. Generally, polyamines and carbamates with boiling point of 50~150 ℃ and azo compounds, hydrazides, diazo compounds and hydrogen boron compounds with decomposition temperature lower than 150 ℃ are used.
The thermal insulation efficiency of epoxy foam produced by fluorochloromethane blowing agent is higher than or equal to that of polyurethane foam, and it can remain in the cell for a long time.
4. surfactant
Surfactants can significantly change the surface tension of liquid or the interfacial tension between two phases. This liquid molecule contains hydrophilic and hydrophobic groups. In the liquid, it tends to concentrate on the interface between the liquid and another phase, forming a thin molecular film to reduce the tension, thus wetting, emulsifying, dispersing and foaming. The surfactants used in epoxy foams are basically the same as those used in phenolic and polyurethane foams. PVDF film production line www.handern. com
5. thixotropic agent
Thixotropic agent has certain influence on the formation of cellular structure of epoxy foam. It depends on the type of foam produced, the choice of resin and curing agent. When thixotropic agent is used in the production of foam, the degree of freedom of operation becomes larger. Commonly used thixotropic agents include pigments, asbestos, silica gel, bentonite, diatomite, mica, organic complexes, solid vegetable oil and metal soap powder. 6. filler
Common fillers for epoxy foamed plastics include glass microspheres or plastic microspheres, ceramics, and fibers
2、 Foaming method
The production methods of epoxy foamed plastics include chemical foaming method, reactive gas foaming method, physical foaming method and curing by adding glass or ceramic or plastic (including fiber materials) hollow microspheres. The first three methods are applicable to the production of low density (<64kg/m) and medium density (64~320kg/m ³) Foamed plastic. High density foam (>320kg/m ³) Most of foam (also known as composite foam) is produced by the fourth method. Generally, the density of foam mainly depends on the formula.
1. chemical foaming PVDF film production line www.handern. com
First mix the blowing agent, toluene and surfactant according to the proportion in the formula, then add them to the heated epoxy resin, and then fully mix them. Add human diethylenetriamine under stirring conditions, and start foaming after about 30s. The density of foam is 112kg/ M ³, The foam is cured at 75~100 ℃ for 1~2h after forming.
Compared with liquid epoxy resin, powdered epoxy resin has the advantage that it is powdery and will not completely fill the mold cavity due to resin stickiness. Mix the powdered epoxy resin with 4.4'- diaminodiphenyl sulfone, etc., pour it into a metal mold, heat it at 150~200 ℃ for foaming, and cure it for 1H. The higher the heating temperature is, the better the curing is. The product that can be used above 250 ℃ can be prepared. The storage life of the resin mixture can reach more than three years. The chemical foaming agent decomposition foaming method is applicable to the production of low-density and medium density epoxy foams with high strength and high service temperature. Table 8-18 shows the chemical foaming formula of epoxy foam. Table 8-19 and table 8-20 respectively show the formula of low density and medium density chemical foaming method. PVDF film production line www.handern. com


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