Polyurethane Sealant Modulus Reduction via Rosin Esters

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Solution Overview

Problem

Conventional sealants and adhesives face challenges in accommodating thermal, moisture, and structural movements in building joints, particularly in weak substrates like concrete, where high modulus sealants can cause damage and low modulus sealants may not provide sufficient strength and movement capability.

Innovation Solution

A low modulus sealant and adhesive composition is developed, comprising a polyurethane prepolymer with a bio-based content and a modulus reducing additive such as rosin esters, which reduces the 100% modulus to less than 85 psi for sealants and less than 100 psi for adhesives, enhancing flexibility and movement capability while maintaining strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high modulus sealants are used to provide high strength, then strength is improved, but movement capability deteriorates and substrate damage occurs

Engineering Contradiction:

Improvesealant strengthVSAvoidmovement capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The invention modifies the chemical composition parameters of the sealant by incorporating specific additives (rosin esters, hydrogenated rosin esters, or polyethylene glycol) to change the modulus from high to low, enabling the sealant to achieve both high strength and high movement capability simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite sealant formulation combining polyurethane base material with specific modulus-reducing additives (rosin esters, hydrogenated rosin esters, or polyethylene glycol), resulting in a material that exhibits both high strength and high elongation properties

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If low modulus sealants are used to improve movement capability, then movement capability is improved, but strength deteriorates

Engineering Contradiction:

Improvemovement capabilityVSAvoidsealant strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The invention optimizes the concentration parameters of modulus-reducing additives (0.1-10% rosin esters, 0.1-10% hydrogenated rosin esters, or 1-20% polyethylene glycol) to achieve the desired balance between low modulus for movement capability and sufficient strength for structural integrity

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If low modulus sealants are used to reduce stress on substrate, then substrate damage is reduced, but movement capability deteriorates

Engineering Contradiction:

Improvesubstrate stressVSAvoidmovement capability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The invention develops a composite sealant formulation that combines polyurethane with specific additives (rosin esters, hydrogenated rosin esters, or polyethylene glycol) to create a material with low modulus that simultaneously provides high movement capability and reduced substrate stress

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS9080087B2Reduction in modulus of polyurethane sealants and adhesives

Publication Date: 2015.07.14 SIKA TECH AG

AI summary

Low modulus, polyurethane sealant or adhesive compositions and a method of reducing the modulus of a polyurethane sealant or adhesive composition, including adding a modulus reducing additive of at least one of rosin esters, hydrogenated rosin esters, or mixtures thereof, to a sealant or adhesive composition including a polyurethane prepolymer, optionally having a bio-based content of from about 15% to about 75% by weight.