Epoxy curing agent (3)

4, Amino

Amines are polycondensation products of polyamines, with relatively high molecular weight, low volatility and low toxicity. Low moisture absorption, no whitening phenomenon. Long application period, heat release

Low temperature, no condensation

(1) Amino-105 epoxy curing agent. Also known as 105 aminals from meta-xylylenediamine catalyzed and condensed to produce amines, light yellow transparent and viscous, viscosity 500~1000 mp.s

Reference dosage 30~35 phr. Curing conditions RT*24H or 80 0C *3H or 100*2H

(2), KB-2 epoxy curing agent Condensed from fatty amines and aromatic amines, light brownish transparent liquid reference amount 50 ~ 55 phr. Curing conditions RT*48H or

120 0C ×2H

5. Polyamine-thiourea condensate

The polyamine reacts with thiourea to form a condensate by condensation, and has a fast curing and low-temperature curing properties.

6, Ketimine

Ketimine is produced by the condensation reaction of ketones (such as acetone, methyl ethyl ketone, methyl isobutyl ketone) and fatty polyamines (such as ethylenediamine, diethylenetriamine, m-phenylenediamine, etc.)

Therefore, the residual polyamine must be blocked with a monoepoxy compound. After the ketimine absorbs water, a reverse reaction occurs, and a polyamine is produced again so that it can be wet or under water

Cured epoxy resin, so called moisture curing agent.

7, polyamine blends

Aromatic polyamines, such as m-phenylenediamine, diaminodiphenyl sulfone, etc. are solid, difficult to mix with epoxy resin into a homogeneous system, and the method of heating with high temperature

Will shorten the application period. If several solid polyamines are eutectic mixed in advance to obtain a supercooled liquid or a low-melting-point solid, it is easy to mix with epoxy resin.

Evenly, no side effects are produced without affecting the properties of the cured product.

(1) 60 g (or 75 g) of m-phenylenediamine and 40 g (or 25 g) of diaminodiphenylmethane are mixed and heated to melt to form a eutectic mixture of supercooled liquid

Room temperature can be maintained for several days.

(2) Press m-phenylenediamine (m-PDA), 4,4-diaminodiphenylmethane (DDM), 3,3-dichloro-diaminodiphenylmethane (MOCA),

10:7:3 (mass ratio) is mixed, heated and melted under inert gas protection, stirred uniformly, cooled and ground to a certain degree of fineness to obtain a ternary low

Melt blends, minimum eutectic temperature 230C, and epoxy resin equimolar ratio, the cured glass of Tg highest temperature.

8, low molecular polyamide

Low molecular polyamides, strictly speaking, should be amino polyamides. Compared with nylons (polyamides), although they all contain amides, they are called polyamides.

However, there is a great difference in the structure and performance of the two synthesis methods, so it cannot be compared.

(E) Acid anhydride curing agent

Anhydride was first used as an epoxy curing agent and is still an important category of epoxy curing agents. Anhydride curing agent has a long pot life, low irritation, slow curing reaction and small shrinkage rate. The cured epoxy resin has excellent mechanical and electrical properties, and the dielectric properties are superior to those of amine cured materials, and the heat resistance is relatively high. However, the medium resistance and heat and humidity resistance are poor. Anhydride curing agents are low in activity and require high temperature curing. Generally 800C or more is required for reaction. The theoretical amount of anhydride curing agent can be calculated as follows:

WA=K×AE×EV

WA---Addition of curing agent per 100g epoxy acid anhydride (g)

K --- coefficient, according to the performance requirements of different types of anhydride vary: about 0.70 ~ 0.90 general anhydride take K = 0.85, halogen containing anhydride K = 0.60; required electrical performance K = 1

AE - anhydride equivalent. The equivalent weight of monobasic anhydride is the relative molecular mass

EV---Epoxy value of epoxy resin

The amount of anhydride additive can be calculated as follows:

WA=56100 / (AV × eq) × 100%

Acid Value of AV --- Anhydride Adducts

Eq--- epoxy equivalent of epoxy resin

The anhydride curing agents of different water types have great differences in the curing speed and the properties of the cured epoxy resin. According to the performance requirements, the use of occasions, process methods, the price level, the size of toxicity and other factors, comprehensive consideration should be given to choose the right anhydride curing agent.

(VI) Imidazole curing agents

Imidazole is a five-membered ring containing two nitrogen atoms. One nitrogen atom constitutes a secondary amine and the other nitrogen atom constitutes a tertiary amine. Either an epoxy resin curing agent or an epoxy resin curing accelerator can be used. It can cure epoxy resin at medium temperature, but it has excellent heat resistance and mechanical properties. It can be compared with arylamine curing agent, but its resistance to dielectric and heat aging is slightly inferior. Imidazole is a kind of very important epoxy resin curing agent, and it is a very important epoxy resin curing agent. The amount of less volatile is not low toxicity or non-toxic. The cured product has excellent performance and is highly valued. There are many varieties available.

(7) Boron amine complex curing agent

Boron trifluoride (BF3) is a Lewis acid with high activity. It quickly solidifies at room temperature after mixing with epoxy resin. The heat is large and the pot life is too short. BF3 is easy to absorb moisture, and it has corrosion and irritant effects. Boron itself should not be used alone as a curing agent for epoxy resins. BF3 is generally used after forming a complex with Lewis bases (amines). Due to the reduced reactivity, the amine complexes of boron trifluoride and the epoxy resin are stable after being mixed with the epoxy resin, and they are stable at high temperatures. The complex is automatically decomposed and the epoxy resin is rapidly cured, so the boron trifluoride amine complex is a latent catalytic hardener.

Practical amines capable of forming boron trifluoride amine complexes are monoethylamine, n-butylamine, aniline, dimethylaniline, pyridine and the like. The amine complexes of boron trifluoride have strong hygroscopicity and will be hydrolyzed and liquefied when placed in moist air. They will no longer have a curing effect and must be protected from moisture and moisture. In addition, boron trifluoride amine complexes are all solids and generally need to be first dissolved in dried acetone and mixed with epoxy resin.

(8) Polymer Curing Agent

(1) Phenolic resin The phenolic resin contains hydroxymethyl and phenolic hydroxyl groups, which can be cured under heating conditions to improve the bonding strength. Heat resistance and water resistance

Long-term use in 2600C, the amount of 30% to 40% can add 0.5% dimethyl dimethylamine accelerator. FB High Temperature Flame Retardant Thermosetting Phenolic Resin Cured Epoxy Resin Heat Resistance

Up to 300C~5000C.

(2) Melamine formaldehyde resin contains hydroxyl and hydroxymethyl groups in the molecular structure, can cure epoxy resin at high temperature can improve the bonding strength, durable thermal and medium resistance

Reference dosage 4%

(3) Aniline-formaldehyde resin The curing effect is similar to that of primary and secondary amines and the amount is 35%. Curing heat distortion temperature 1550C is equivalent to aromatic amine curing agent.

(4) Liquid Polyurethanes Both amino and isocyanate groups in polyurethanes react with epoxy groups and hydroxyl groups to cure the epoxy resin. Cured material has better toughness and lower

Moisture permeability and water absorption

(5) Polyester resin The hydroxyl group and the hydroxyl group at the end of the polyester resin can cure the epoxy group and the hydroxyl group to react to cure the epoxy resin. Cured material has excellent adhesive strength,

Toughness and electrical properties.

(6) Liquid Polysulfide Rubber The thiol group (-SH) at the end of the liquid polysulfide rubber can react with the epoxy group, but the reaction proceeds very slowly at room temperature. Add accelerator or high

The temperature can accelerate curing. The cured product has better softness and tightness.

(7) Polythiol A low molecular weight, low viscosity thioether with a terminal thiol. It is a room temperature fast curing agent. Even with low temperatures (00C) and in humid environments

Into the accelerator DMP-30 can also be cured epoxy resin, the pot life of 2 ~ 10min, 10 ~ 30min after the practical strength can be achieved, fully cured 7d

(8). The aldehyde resin contains a hydroxyl group and can react with an epoxy group to cure the epoxy resin.

(9) Phosphorus-containing polymer The SP resin contains a hydroxyl group and is miscible with 70 anhydride and HK-021 anhydride.