Curable Polyester Polyols for Soft Feel Coatings
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Solution Overview
Problem
Soft feel coatings face a challenge in maintaining chemical resistance, particularly against sunscreen lotions, while preserving the desired soft touch and aesthetic value, as existing solutions often compromise on comfort and durability.
Innovation Solution
A thermosetting soft feel coating composition comprising a curable aliphatic polyester with specific diol and diacid residues, a soft segment polyol, an isocyanate crosslinker, and a solvent, which provides superior chemical resistance and maintains the soft touch sensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross link density is increased to improve chemical resistance, then chemical resistance is improved, but soft touch feeling deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the polyester polyol by specifying precise molecular weight ranges (500-5000 g/mol), hydroxyl number ranges (50-200 mg KOH/g), and compositional ratios (aliphatic diacid residues ≥90 mol%). These parameter adjustments optimize the balance between cross-link density for chemical resistance and molecular flexibility for soft touch sensation.
Solution Approach 2:
The patent creates a composite coating formulation combining cured polyester polyol with soft segment polyol (silicone or polyether) and crosslinking agents. This composite structure allows the rigid cross-linked network to provide chemical resistance while the soft segment maintains tactile comfort.
2Reliability
If film hardness is increased to improve sunscreen resistance, then sunscreen resistance is improved, but comfort and aesthetic value deteriorate
Solution Approach 1:
The patent adjusts film hardness parameters through controlled cross-linking by selecting specific crosslinking agents and controlling the NCO:OH ratio (0.8-1.2), achieving sufficient sunscreen resistance while maintaining soft touch properties through optimized hardness rather than excessive hardness.
Solution Approach 2:
The patent applies different functional properties to different aspects of the coating: the cross-linked polyester matrix provides local chemical and sunscreen resistance, while the soft segment polyol provides local soft touch sensation, creating spatial differentiation of properties within the coating film.
3Strength
If cross link density is increased to improve adhesion, then adhesion is improved, but soft touch feeling deteriorates
Solution Approach 1:
The patent optimizes adhesion through controlled cross-linking parameters including molecular weight (500-5000 g/mol) and hydroxyl number (50-200 mg KOH/g), which provide sufficient adhesion strength without creating excessive rigidity that would eliminate soft touch sensation.
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 composition achieves enhanced sunscreen lotion resistance while maintaining the comfort and aesthetic value of the coating, ensuring robust adhesion and durability.
Implementation Method 1
an isocyanate crosslinker
Implementation Method 2
curable aliphatic polyester composition
Data Source
AI summary
A soft feel curable polyester composition comprising the residues of a 2,2,4,4-tetraalkylcyclobutane-1,3-diol, a C2-C20 diol other than 2,2,4,4- tetraalkylcyclobutane-1,3-diol, a C2-C20 polyol, an alicyclic diacid and an acyclic aliphatic diacid, wherein said curable polyester contains at least 90 mole percent of aliphatic diacid residues, based on the total moles of diacid residues, and wherein said curable polyester has a hydroxyl number of about 100 to about 250 mgKOH/g, an acid number of 0 to about 30 mgKOH/g, and a number average molecular weight of about 500 to about 10,000 g/mole, a soft segment polyol, an isocyanate crosslinker and a solvent or a solvent mixture.