Modified polyurethane curing agent for alkyd resin with high hydroxyl content and preparation method thereof

Abstract

The invention discloses a modified polyurethane curing agent for an alkyd resin with high hydroxyl content. The modified polyurethane curing agent is prepared by the following raw materials by weight parts: 5-8 of alkyd resin, 5-8 of trimethylolpropane and 26-29 of toluene diisocynate, wherein the hydroxyl content of the alkyd resin is 5.5 to 6.4 percent. The invention also provides a preparation method for the modified polyurethane curing agent. The addition reaction is performed among the alkyd resin with hydroxyl content of 5.5 to 6.4 percent, trimethylolpropane and toluene diisocynate containing NCO groups, and the prepared modified bicomponent polyurethane curing agent has crosslinked NCO groups with high reactivity, so that modified polyurethane curing agent can be copolymerized with paint component containing hydroxyl groups at normal temperature to form paint films with different characteristics. Therefore, the modified polyurethane curing agent is excellent in operational performance and wide in application field.

Description

technical field [0001] The invention relates to the technical field of curing agents, in particular to a high-hydroxy alkyd resin modified polyurethane curing agent and a preparation method thereof. Background technique [0002] The two-component polyurethane curing agent contains active NCO groups, which can cross-link with paint components containing active hydroxyl groups to form paint films with various properties. [0003] The general two-component polyurethane curing agent is a kind of curing agent with the largest production volume and the most widely used in my country, which is synthesized by using trimethylolpropane (TMP) and toluene diisocyanate (TDI) through a specific formula and process reaction. Due to the high price of trimethylolpropane raw materials, this type of curing agent has a high cost and cannot meet the special requirements of some low-end markets. [0004] However, some polyurethane curing agent manufacturers use general hydroxyl-containing alkyd ...

AI Technical Summary

Problems solved by technology

Due to the high price of trimethylolpropane raw materials, this type of curing agent has a high cost and cannot meet the special requirements of some low-end markets

[0004] Some polyurethane curing agent manufacturers use general hydroxyl-containing alkyd resins and trimethylolpropane and NCO-containing toluene diisocyanate (TDI) to synthesize modified polyurethane curing agents through specific formulas and processes. The hydroxyl content of the alkyd resin used is less than 5.5%, and relatively speaking, the alkyd resin formula contains more saturated fatty acids, while the hard monomeric acid content containing a benzene ring structure is less, and the alkyd resin itself has low hardness. The molecular weight is small, and the polyol excess is less, and the effective hydroxyl content in the molecular structure is low. When this alkyd resin is used to replace part of the trimethylolpropane modified polyurethane curing agent, the prepared polyurethane curing agent has relatively low More disadvantages: low effective NCO content, low hardness

When the polyurethane curing agent cross-links with the hydroxyl-containing paint component to form a film, the cross-linking reaction activity is low, the drying speed is slow, the cross-linking density is poor, the hardness of the paint film is low, and the adhesion is poor.

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