Water Absorbent Resin Surface Crosslinking for Gel Blocking
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Solution Overview
Problem
Conventional water absorbent resin materials face challenges in achieving high liquid permeability, water absorbing speed, and fixed height absorption while avoiding issues like coloring and odor, and often require large amounts of additives that increase costs and reduce absorption capacity.
Innovation Solution
A water-soluble or water-dispersible polymer with a LogP of not less than 1.0 is added in small amounts to a surface-crosslinked water absorbent resin, specifically between 0.001 mass% to 0.2 mass%, to enhance liquid permeability, absorption capacity, and water absorbing speed without causing coloring or odor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a water absorbent resin is increased in concentration to improve absorption capacity, then absorption capacity is improved, but liquid permeability deteriorates causing gel blocking
Solution Approach 1:
The patent applies surface crosslinking to create a porous surface structure on the water absorbent resin particles. This porous surface allows liquid to permeate through the resin layer more effectively, preventing gel blocking while maintaining high absorption capacity in the interior of the particles.
Solution Approach 2:
The patent creates a composite structure with a crosslinked surface layer and an uncrosslinked or less crosslinked interior. This composite structure combines the benefits of surface porosity for liquid permeability with the high absorption capacity of the gel interior, resolving the contradiction between absorption capacity and liquid permeability.
2Object-generated harmful factors
If additives are added to improve liquid permeability, then liquid permeability is improved, but absorption capacity deteriorates
Solution Approach 1:
The patent applies crosslinking locally to the surface of the resin particles rather than throughout the entire particle. This local modification improves liquid permeability at the surface where liquid contact occurs, while the interior remains highly absorbent, thus improving liquid permeability without sacrificing absorption capacity.
Solution Approach 2:
The patent segments the resin particle into different functional zones: a crosslinked surface layer for liquid permeability and an uncrosslinked interior for absorption. This segmentation allows each zone to perform its specific function optimally without interfering with the other.
3Object-generated harmful factors
If conventional additives are used to improve performance, then liquid permeability and absorption are improved, but coloring and odor occur
Solution Approach 1:
The patent replaces chemical additives with a physical/chemical crosslinking process on the resin surface. Instead of using conventional additives that cause coloring and odor, the patent uses crosslinking agents to modify the surface structure, achieving liquid permeability improvement without the harmful side effects of additives.
4Object-generated harmful factors
If large amounts of additives are used to improve performance, then liquid permeability and absorption are improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the crosslinking degree parameter to achieve optimal performance. By controlling the crosslinking degree to be 1-50% on the surface, the patent achieves sufficient liquid permeability with minimal additive usage, thereby reducing manufacturing cost while maintaining performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach results in a water absorbent resin with improved liquid permeability, absorption capacity, and water absorbing speed, reducing the likelihood of liquid leakage and maintaining a low coloration, thus producing a more effective and cost-efficient hygienic material.
Implementation Method 1
A water-soluble or water-dispersible polymer whose LogP is not less than 1.0 is added in small amounts to a surface-crosslinked water absorbent resin
Implementation Method 2
A water absorbent resin absorbs water-based liquid to swell
Implementation Method 3
A water absorbent resin (SAP/Super Absorbent Polymer) is a water-swelling and water-insoluble polymer gelatinizer
Data Source
AI summary
An object of the present invention is to provide a water absorbent resin which attains high liquid permeability and water absorbing speed, and which does not have problems of coloring and odor. The water absorbent resin includes: (A) a water absorbent resin particle having a carboxyl group; (B) a covalent surface crosslinking agent in which the number of carbons is not more than 10; (C) 0.001 mass% to 0.2 mass% of a water-soluble or water-dispersible polymer whose LogP is not less than 1.0; and (D) 0.001 mass% to 1 mass% of a water-soluble polyvalent cation. The water absorbent resin has not less than 20 g/g of a fixed height absorption (FHA) at a height of 20 cm.