Water-based polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a water-based polyurethane adhesive and a preparation method thereof. The preparation method is characterized by comprising the following steps: mixing and emulsifying a non-water-soluble blocked isocyanate curing agent and a polyurethane prepolymer, thereby obtaining the water-based polyurethane adhesive, wherein the non-water-soluble blocked isocyanate curing agent serves as the core, and the polyurethane prepolymer serves as the shell; or mixing and emulsifying a polyurethane prepolymer of which the NCO terminal group is blocked by a blocking agent and the non-water-soluble blocked isocyanate curing agent, thereby obtaining the water-based polyurethane adhesive, wherein the non-water-soluble blocked isocyanate curing agent serves as the core, and the polyurethane prepolymer of which the NCO terminal group is blocked by the blocking agent serves as the shell; or mixing and emulsifying a prepolymer of which the NCO terminal group is blocked by a blocking agent and non-water-soluble polyamine, thereby obtaining the water-based polyurethane adhesive, wherein the non-water-soluble polyamine serves as the core, and the polyurethane prepolymer of which the NCO terminal group is blocked by the blocking agent serves as the shell. According to the water-based polyurethane adhesive disclosed by the invention, the double components are stably stored under the mixing condition at normal temperature, the construction process is simple, the manual labor is not consumed compared with the conventional double-component polyurethane due to the operations of mixing and metering, and hazards of release of the blocking agent on the environment can be controlled.

Description

technical field [0001] The invention belongs to the technical field of water-based polyurethane materials, and in particular relates to a water-based polyurethane adhesive and a preparation method thereof. Background technique [0002] According to the book "Waterborne Polyurethane and Its Application" (Chemical Industry Press, 2015 edition), waterborne polyurethane adhesives can be divided into one-component and two-component waterborne polyurethane adhesives. Most water-based polyurethane adhesives are one-component systems. One-component water-based polyurethane adhesives use water-based polyurethane resin as the base material, add additives, fillers, etc., and use water as the dispersion medium. A type of single-component adhesive, mostly Linear thermoplastic polyurethane or cross-linked polyurethane with low cross-linking degree (generally less than 2% cross-linking degree). One-component water-based polyurethane is easy to use, but many properties such as water resist...

AI Technical Summary

Problems solved by technology

For example, the two components are strictly packaged and prepared according to a certain proportion before use. They must be prepared immediately after use. The operation has a certain time limit. Generally, the prepared glue cannot be used after 2-4 hours. Adhesives are prone to bubbles, which are difficult to eliminate quickly. Part B needs to be stored in an anhydrous and oxygen-free system, and the cost is generally high

Moreover, aziridine-based two-component systems and carbodiimide-based two-component systems are highly toxic and can cause great harm to the human body; the reaction rate is slow, and solvent-based curing agents are difficult to dissolve in water-based systems. The obtained adhesive is actually a two-phase system, and the water-based curing agent itself contains hydrophilic groups, which will have a certain impact on the water resistance of the material after introduction

[0004] China "Painting Industry" in October 2012, Volume 42, Issue 10, Page 21-24 reported the use of 3,5-dimethylpyrazole as a blocking agent to obtain a blocked water-based isocyanate curing agent. After the agent is mixed, it is heated to deblock, and then cured and cross-linked, but the oil-soluble blocked curing agent (or blocked curing agent) still faces the problem of incompatibility with the water-based system, and it is difficult to obtain a good bonding effect

Relevant reports on water-based blocked curing agents, such as "Preparation and Performance Research of Blocked Water-based Polyisocyanate Curing Agents" reported on pages 17-19 of the 37th volume 12 of China's "Painting Industry" in December, 2007, utilize methyl ethyl ketone oxime and IPDI trimer reaction grafted polyethylene glycol methyl ether to prepare a blocked water-based polyisocyanate curing agent. Although it can be directly mixed with water-based resins, the introduction of water-soluble polyethylene glycol monomethyl ether will affect the water resistance of the material. There is a certain impact, the synthesis process of the end-blocking curing agent is complicated, and the unblocking temperature is high

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