Water absorbing agent for paper and preparation method thereof

Abstract

The invention provides a water-absorbing agent for paper and a preparation method thereof. The preparation method comprises the following steps: (1) adding polyethylene polyamine and a reaction auxiliary agent to a polybasic acid, reacting at 120-130°C, and then reacting at 155-190°C , lower the temperature to 120-140°C, add hot water, (2) adjust the pH of the polycondensate obtained in step (1) to 5-7 with an acid, then add the aldehyde solution, reflux for 1-2 hours, and dilute with water, (3) Adjust the pH of the solution obtained in step (2) to 8-8.5 with an alkaline solution, dropwise add epichlorohydrin, heat up to 60-75°C to react, add water to dilute, and adjust the pH to 3-5 with an acid solution, That is, the water-absorbing agent is obtained. The present invention is a non-heat-curable cationic polymer. The water-absorbing agent is used in combination with an anionic polymer containing carboxyl or carboxylate and a thermosetting cationic wet-strength agent PAE to increase the dry tensile strength and wet tensile strength of paper. Strength while absorbing moisture quickly.

Description

technical field [0001] The invention relates to a water-absorbing agent for paper and a preparation method thereof. Background technique [0002] Products such as toilet paper and tissue paper require that the paper sheet not only have good water absorption, but also have high wet strength so that it can still maintain structural integrity when subjected to external forces. However, the additives that make the paper sheet have good water absorption tend to reduce the wet strength of the paper, while the wet strength agent often increases the hydrophobicity of the paper surface. For example, wet strength agents such as urea-formaldehyde resin, melamine-formaldehyde resin and polyamide polyamine epichlorohydrin resin commonly used in acidic conditions will reduce the water absorption performance of paper. In addition, additives containing aldehyde groups in the molecule, For example, dialdehyde starch, glyoxal modified acrylamide, etc. can only give the paper a temporary wet ...

AI Technical Summary

Problems solved by technology

For example, wet strength agents such as urea-formaldehyde resin, melamine-formaldehyde resin and polyamide polyamine epichlorohydrin resin commonly used in acidic conditions will reduce the water absorption performance of paper. In addition, additives containing aldehyde groups in the molecule, For example, dialdehyde starch, glyoxal modified acrylamide, etc. can only give temporary wet strength to the paper, and are not conducive to the absorption of water.

[0003] In order to facilitate the absorption of water by the paper, surfactants are usually added to it, but these agents will reduce the dry strength of the paper and reduce the wet strength at the same time.

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