Pen Surface Raised Structures Soft-Touch UV Curing
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Solution Overview
Problem
Existing methods for producing pens with raised structures using UV-hardened plastic materials result in hard structures that do not provide a satisfactory feel and grip, despite the addition of soft-touch additives, as these additives become tightly bound within the polymer network during crosslinking, failing to develop their haptic effect effectively.
Innovation Solution
A method involving a flowable UV-crosslinkable plastic mass containing a urethane-acrylate oligomer, a monofunctional monomer, a soft-touch additive, and a photoinitiator from the bis-acyl phosphine oxide group, with minimal or no co-photoinitiator, is applied to the pen surface, allowing the additives to protrude and develop their haptic effect after crosslinking, resulting in significantly improved soft-touch properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If soft-touch additives are added to the plastic mass to improve feel and grip, then the haptic properties should improve, but the additives become tightly bound within the polymer network during crosslinking and fail to develop their haptic effect
Solution Approach 1:
The patent changes the photopolymerization parameters by selecting a specific photoinitiator system (bis-acyl phosphine oxide as main photoinitiator with limited co-photoinitiator from other chemical groups) to control the crosslinking kinetics. This parameter change allows soft-touch additives to remain on the surface rather than being tightly bound within the network, enabling them to develop their haptic effect while maintaining satisfactory adhesion and structural integrity.
2Loss of time
If UV irradiation is used to harden the plastic mass quickly, then the drying time is shortened, but the structures become relatively hard which reduces the grip quality
Solution Approach 1:
The patent modifies the photopolymerization parameters by choosing specific photoinitiators (bis-acyl phosphine oxide group) that enable controlled crosslinking. This allows the plastic mass to cure quickly under UV irradiation while producing a polymer network with appropriate flexibility, resulting in structures that are both fast to produce and provide satisfactory grip quality.
Solution Approach 2:
The patent creates a composite plastic mass system combining urethane-acrylate oligomer, monomer, soft-touch additives, and specific photoinitiators. This composite formulation allows the soft-touch additives to remain partially on the surface after crosslinking, providing both quick curing and improved haptic properties for better grip.
3Reliability
If a photoinitiator system with co-photoinitiators is used to ensure complete curing, then the crosslinking is thorough, but the soft-touch properties are impaired because co-photoinitiators from other chemical groups reduce the surface presence of soft-touch additives
Solution Approach 1:
The patent optimizes the photoinitiator system parameters by specifying bis-acyl phosphine oxide as the main photoinitiator and limiting co-photoinitiators from other chemical groups to minimal proportions. This parameter optimization ensures sufficient crosslinking completion while preserving soft-touch properties by preventing excessive competition for the polymerization process that would displace soft-touch additives from the surface.
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 method achieves very soft and non-slip structures with enhanced tactile properties, as demonstrated by improved adhesion, soft-touch properties, hardness, drying time, and scratch resistance, outperforming comparative examples in all evaluated categories.
Implementation Method 1
The UV irradiation causes the corresponding polymer to be formed from the urethane-acrylate oligomer and the monomer, initiated by the main and any co-initiator
Implementation Method 2
a photoinitiator from the Group containing bis-acyl phosphine oxides
Data Source
AI summary
The invention relates to a method for manufacturing a pen in which a flowable UV-crosslinkable plastic mass is applied to the pen surface and cured by UV irradiation, wherein the plastic mass contains - 20%-98% of a urethane acrylate oligomer, - 0.1% to 60% of a monomer crosslinking with this oligomer under UV irradiation, 0.1%-30% of a soft-touch additive and - 0.1%-30% of a main photoinitiator from the chemical group of bis-acyl phosphine oxides, and a co-photoinitiator from another chemical group is not present or is present only in a smaller proportion than the main photoinitiator.