Soft Contact Lens Dual Coating for Durable Hydrophilicity

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Solution Overview

Problem

Existing soft contact lenses suffer from insufficient hydrophilicity and lubricity when worn for extended periods, leading to discomfort and oxygen deprivation, and existing surface treatments are either complex or lack durability evaluations.

Innovation Solution

A soft contact lens with two coating layers: a hydrogel layer containing glycidyl groups, a first coating layer with carboxyl or amino groups, and a second coating layer with glycidyl groups bonded via covalent bonds, using polymers derived from specific monomers to enhance hydrophilicity and lubricity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plasma treatment or chemical bonding method is performed on the soft contact lens to achieve sufficient hydrophilicity, then the hydrophilicity is improved, but the surface treatment step becomes complicated and highly controlled manufacturing equipment is required

Engineering Contradiction:
ImprovehydrophilicityVSAvoidsurface treatment step
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The surface treatment is divided into multiple coating layers (first coating layer with carboxyl/amino groups, second coating layer with glycidyl groups) applied sequentially, where each layer performs a specific function. This segmentation allows complex hydrophilization to be achieved through simple sequential dipping steps rather than complex plasma or chemical bonding equipment

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hydrogel base material is pre-designed to contain glycidyl groups that can covalently bond with the first coating layer. This preliminary preparation of reactive groups eliminates the need for subsequent plasma treatment or complex chemical bonding steps, achieving durable hydrophilicity through simple immersion coating

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If a single coating layer is applied to the soft contact lens, then the manufacturing process is simplified, but the hydrophilicity becomes insufficient when the contact lens is worn for a whole day

Engineering Contradiction:
Improvecoating processVSAvoidhydrophilicity duration
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The coating is segmented into two functional layers: the first coating layer provides initial hydrophilicity and serves as an adhesive interface, while the second coating layer provides sustained hydrophilicity and lubricity. This segmentation achieves durable all-day comfort without complicating the manufacturing process

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses composite coating structure combining different polymer materials with complementary functions. The first layer uses carboxyl/amino group-containing polymers for bonding and initial hydrophilicity, while the second layer uses glycidyl group-containing polymers for sustained hydrophilicity, creating a composite surface that maintains performance throughout the day

Inventive Principle:
Principle #40Composite materials

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 lens maintains sufficient hydrophilicity and lubricity even after prolonged wear, addressing discomfort and oxygen deprivation issues.

Implementation Method 1

the glycidyl group of the hydrogel is bonded to the carboxyl group and/or the amino group of the first coating layer via a covalent bond

Methodology Applied
Scientific EffectCovalent bonding: Chemical Bonding

Implementation Method 2

the carboxyl group and/or the amino group of the first coating layer is bonded to the glycidyl group of the second coating layer via a covalent bond

Methodology Applied
Scientific EffectCovalent bonding: Chemical Bonding

Data Source

PatentUS20250321358A1Soft contact lens having coating layer
Publication Date: 2025.10.16 NOF CORP

AI summary

Provided is a soft contact lens including a hydrogel having a glycidyl group, a first coating layer having a carboxyl group and/or an amino group, and a second coating layer having a glycidyl group, in which two coating layers are formed on a surface, and the surface has sufficient hydrophilicity and lubricity even in a case where the soft contact lens is worn continuously for a long period of time.