CN1312190C - Resinoid phenols solidified agent and preparation method - Google Patents

Abstract

The invention relates to a resinous phenolic curing agent and a preparation method thereof, which belongs to a special additive for polymer materials and is an excellent fast curing agent for epoxy powder coatings. It is characterized in that the curing agent is composed of low-molecular-weight epoxy resin and bisphenol resin, and is chain-extended under the catalysis of a catalyst to obtain a resinous curing agent containing phenolic hydroxyl groups as terminal groups. The resinous phenolic curing agent of the present invention can be produced by bulk polymerization, and the obtained product is pure. The main properties of the resinous phenolic curing agent of the present invention are: softening point 90-95°C, glass transition temperature 70-80°C, hydroxyl value 0.28-0.40eq/100g. The coating cured by this curing agent has a wider application field and greater application value than the phenolic resin curing agent. The resinous phenolic curing agent of the present invention has simple production process, pure product, narrow molecular weight distribution, all domestic raw materials are used, and the cost is low.

Description

Resin-like phenolic curing agent and preparation method thereof

Technical field: The present invention relates to a resinous phenolic curing agent and its preparation method, which belongs to special additives for polymer materials and is an excellent fast curing agent for epoxy powder coatings.

Background technology: At present, in the construction of pipe bending, hoisting, crossing and installation, it is very necessary to obtain a curing agent with good adhesion and mechanical properties, and at the same time, it can withstand cold bending at -30°C. For the anti-corrosion epoxy resin powder coatings currently used in our country, the commonly used curing agent is mainly phenolic resin. The epoxy resin powder coating with phenolic resin as curing agent has good heat resistance, high mechanical properties, wide sources and low price. However, due to the large number of benzene rings in the structure, the coating film is brittle, especially at a low temperature of -30°C, the toughness is poor, and there are a lot of cracks when cold bending at -30°C. None of the existing curing agents has the characteristics of high mechanical properties, excellent adhesion, good cold bending performance at -30°C, and rapid curing of epoxy powder coatings.

Summary of the invention: In order to avoid the shortcomings of the existing technology, the present invention has developed a new type of resinous phenolic curing agent, which not only has good adhesion and mechanical properties, but also can withstand cold bending at -30°C, and can make epoxy powder The coating cures quickly, which can meet the construction requirements of pipelines during pipe bending, hoisting, crossing and installation, so it can meet the urgent needs of the anti-corrosion market.

The technical idea of the invention is: the main raw materials are low molecular weight epoxy resin and bisphenol resin, and the chain extension is carried out under the catalysis of a catalyst to obtain a resinous phenolic curing agent containing phenolic hydroxyl groups as terminal groups. Epoxy resin is a low-molecular-weight linear epoxy resin with good toughness, and the chain can be further extended so that both ends contain phenolic hydroxyl groups, so that the epoxy resin can be cured. Because of its epoxy resin structure, as an epoxy resin curing agent, it has good compatibility with epoxy resin, contains a large number of hydroxyl groups, and has high adhesion. Bisphenol resin, because the structure contains phenolic hydroxyl groups, the first step is to react with epoxy resin to achieve the purpose of chain extension, and the second step is to react in excess, so that the two ends of the generated product contain phenolic hydroxyl groups, which can be used as a curing agent. At the same time, due to the excessive addition, the system contains unreacted bisphenol resin, which can increase the reaction speed of the system and achieve the purpose of rapid curing. In addition, a large number of phenolic hydroxyl groups endow the coating with excellent adhesion.

The low-molecular-weight epoxy resin and the bisphenol resin are reacted in a ratio of 60-100:20-60 in parts by weight, and the mixed catalyst is 0.1-0.5% of the total amount of reactants.

Bisphenol resin can use alkyl substituted bisphenol A or halogen substituted bisphenol A and so on.

Catalysts can use quaternary ammonium salts and quaternary phosphorus salts, such as butyl ammonium chloride and butyl triphenylphosphorus chloride, etc. The reaction of this catalyst is mild and easy to control. The product has less branching, no crosslinking, and a molecular weight The distribution is more concentrated. In the curing process of powder coatings, it has a fast catalytic effect.

The mixed catalyst composed of quaternary ammonium salt and quaternary phosphonium salt is 1:1, and the addition amount is 0.1-0.5% of the total amount of reactants.

Low molecular weight epoxy resin, the dosage is 60-100, the epoxy value is 0.48-0.52eq/100g, the epoxy equivalent is 750-950g/eq, the molecular weight is 300-900, and the softening point is 85-100°C.

Preparation method of the present invention:

(1) Low-molecular-weight epoxy resin and bisphenol resin are mixed by weight 60～100: 20～60, add the mixed catalyst of 0.1～0.5% of the above-mentioned mixture gross weight, react 1～3 hours at 150～160 ℃, Cool down to 120°C, this is product I;

(2) Add 60-100 parts of bisphenol resin and 0.1-0.5 parts of mixed catalyst to product I, raise the temperature to 150-160°C, react for 2-4 hours, discharge while hot, cool and pulverize.

The resinous phenolic curing agent of the present invention can be produced by bulk polymerization, and the obtained product is pure. The main properties of the resinous phenolic curing agent of the present invention are: softening point 90-95°C, glass transition temperature 70-80°C, hydroxyl value 0.28-0.40eq/100g. The coating cured by this curing agent has a wider application field and greater application value than the phenolic resin curing agent.

The advantage of the present invention compared with prior art is:

Reasonable formula and production process, in the case of greatly improving the toughness of the coating, it has achieved the high adhesion and excellent leveling properties of foreign anti-corrosion special curing agents, and the cost has been greatly reduced. Using low-molecular-weight epoxy resin for chain extension makes the curing agent and epoxy resin have good compatibility, reduces cross-linking density, and has excellent toughness, especially low-temperature toughness. The bisphenol resin provides reactive sites, endows the curing agent with high reactivity, increases the phenolic hydroxyl content of the system, and greatly improves the adhesion and heat resistance. Moreover, the resinous phenolic curing agent of the present invention can be produced by the bulk method, the production process is simple, the product is pure, the molecular weight distribution is narrow, all domestic raw materials are used, and the cost is low.

Description of drawings

Fig. 1 is the step schematic diagram of the preparation method of resinous phenolic curing agent of the present invention

Detailed ways:

Example 1:

First put 100 parts by weight of low molecular weight epoxy resin into the reactor, raise the temperature to 120°C, stir for 0.5 hours, add 25 parts by weight of bisphenol resin and 0.5 parts of mixed catalyst, raise the temperature to 150°C, react for 3 hours, and cool down to 120°C ℃, this is the product I;

Mix product I with 96 parts of bisphenol resin and 0.5 part of catalyst, stir evenly, raise the temperature to 150°C, react for 4 hours, discharge, and cool to obtain the resinous phenolic curing agent of the present invention.

Claims (5)

1, a kind of arborescens phenols curing agent is characterized in that: main raw material is low-molecular-weight epoxy resin and bisphenol resin, carries out chain extending reaction under catalyst, obtains the arborescens phenols curing agent; Low-molecular-weight epoxy resin and bisphenol resin are 60～100: 20～60 ratios reactions by weight, mixed catalyst be low-molecular-weight epoxy resin and bisphenol resin total amount 0.1～0.5%; Preparation process is: a, with low-molecular-weight epoxy resin and bisphenol resin by weight 60～100: 20～60 mix, 0.1～0.5% the mixed catalyst that adds the said mixture gross weight, in 150～160 ℃ of reactions 1～3 hour, be cooled to 120 ℃, this is product I; B, product I is added 60～100 parts of bisphenol resins and 0.1～0.5 part of mixed catalyst, be warming up to 150～160 ℃, react discharging while hot, cooling, pulverizing 2～4 hours.

2, arborescens phenols curing agent according to claim 1 is characterized in that: bisphenol resin is to use alkyl to replace dihydroxyphenyl propane or halogen replaces the dihydroxyphenyl propane preparation.

3, arborescens phenols curing agent according to claim 1 is characterized in that: mixed catalyst is quaternary ammonium salt and quaternary alkylphosphonium salt.

4, arborescens phenols curing agent according to claim 3 is characterized in that: mixed catalyst quaternary ammonium salt and quaternary alkylphosphonium salt are butyl ammonium chloride and Butyltriphenylphosphonium chloride.

5, arborescens phenols curing agent according to claim 1 and 2, it is characterized in that: the oxirane value of low-molecular-weight epoxy resin is 0.48～0.52eq/100g.

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