Preparation method of hot-melt polyurethane resin for bonding material

Abstract

The invention discloses a preparation method of hot-melt polyurethane resin for a bonding material. The preparation method comprises the following steps of performing a dehydration treatment on polyester polyol, polyether polyol, natural oligomer polyol or a mixture of two or more of the polyols aforementioned in certain conditions; adding an amine catalyst or a metal organic compound catalyst, and uniformly stirring and mixing at a room temperature; then reacting the mixture obtained from the former step with polyisocyanate or diisocyanate at 50-70 DEG C; after reacting for a certain time, adding an appropriate amount of a chain extender in the system (an appropriate amount of a good solvent can be added as needed to adjust the viscosity); after the chain extension reaction is concluded, adding a certain amount of acrylate with hydroxyl and a certain amount of an antioxidant in the system; determining the content of NCO via a titration method, when the needed theoretical value is achieved, stopping the reaction, and discharging, thereby obtaining the needed hot-melt polyurethane resin for the bonding material. The hot-melt polyurethane resin for the bonding material is applied to the field of medicine and tobacco packaging as an adhesive, and has the greatest advantages of high bonding strength, low viscosity and low readily oxidizable substance content, and is beneficial to customer use and cost reduction.

Description

technical field [0001] The invention belongs to the field of adhesives, and in particular relates to a preparation method of a hot-melt polyurethane resin for adhesive materials. Background technique [0002] For a long time, the polyurethane adhesives used in the packaging field, especially in the field of pharmaceutical and tobacco packaging, mainly include solvent-based polyurethane adhesives, two-component polyurethane adhesives and one-component solvent-free polyurethane adhesives. All there are deficiencies in the above three types of adhesives and are unfavorable for application. It is mainly reflected in the fact that the high viscosity is not conducive to coating use; the bonding strength is not high, which is reflected in the long curing time resulting in poor initial bonding strength, especially the low bonding force between PVC plates and aluminum foil; the existing solvent-based polyurethane adhesive The adhesive system needs to use a large amount of organic so...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a preparation method of hot-melt polyurethane resin for bonding materials, which concentrates on solving the existing deficiencies of the existing polyurethane adhesives: such as the excessive amount of organic solvent in the solvent-based polyurethane adhesive system leads to The coating amount is low, the viscosity of the one-component solvent-free polyurethane adhesive is too high, which is not conducive to glue application, and the application process of the two-component polyurethane adhesive is complicated; the invention also solves the problems of the above three types of polyurethane adhesives. The content of easy oxides in the adhesive exceeds the standard, and the bonding strength is low, especially the problem of low initial bonding strength