Low-Density Moisture-Curing Composition With Stable Pumpability
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Solution Overview
Problem
Existing moisture-curing compositions with hollow spheres for reducing density suffer from poor mechanical properties, instability in density over time, and poor pumpability, leading to undesirable leakage and irreversible density increase during application.
Innovation Solution
A moisture-curing composition combining inorganic fillers with specific-sized hollow spheres and defined quantities of components, ensuring improved tensile strength, stable reduced density, and easy applicability without runoff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If microscopic hollow spheres are used to reduce density, then density is reduced, but mechanical properties such as tensile strength and elongation at break deteriorate
Solution Approach 1:
The patent uses a composite filler system combining inorganic filler particles (such as calcium carbonate, barite, or talc) with microscopic hollow spheres. This composite approach allows the inorganic filler to provide mechanical reinforcement while the hollow spheres contribute to density reduction, achieving both low density and acceptable mechanical properties simultaneously
Solution Approach 2:
The patent specifies precise parameter ranges for the hollow spheres including particle size (D90 less than 150 μm, preferably 50-100 μm), density (0.1-0.6 kg/L), and shell thickness (1-20 μm). These parameter optimizations ensure the hollow spheres provide sufficient structural support while maintaining low density, preventing excessive degradation of tensile strength
2Strength
If large quantities of reinforcing carbon black are added to improve mechanical properties, then tensile strength is improved, but the composition becomes extremely thick and pumpability deteriorates
Solution Approach 1:
The patent optimizes the carbon black content to a specific range (1-10 phr, preferably 2-5 phr) rather than using large quantities. This controlled parameter approach provides sufficient reinforcement for acceptable tensile strength while preventing excessive viscosity increase that would impair pumpability. The low density fillers also contribute to reduced overall viscosity compared to high-density filler systems
3Weight of stationary object
If microscopic hollow spheres with polymer shells are used to reduce density, then density is reduced and compatibility is improved, but compressibility increases leading to leakage during dispensing
Solution Approach 1:
The patent specifies that the hollow spheres should have a shell thickness of 1-20 μm and be made of inorganic materials (such as glass, silicates, or metal oxides) rather than polymer shells. This material and dimensional parameter selection provides sufficient structural rigidity to prevent compressibility and leakage during dispensing while maintaining low density
Solution Approach 2:
The patent uses inorganic filler particles as a sacrificial component that provides structural support during application. These inorganic particles (calcium carbonate, barite, talc) are inexpensive and provide rigid structural framework that prevents hollow sphere compression, accepting that some filler may be lost during application but gaining leakage-free dispensing performance
4Weight of stationary object
If microscopic hollow spheres are added to reduce density, then density is reduced, but density stability deteriorates with irreversible increase after pumping and prolonged storage
Solution Approach 1:
The patent uses a composite system where inorganic filler particles form a stable structural framework that prevents hollow sphere collapse during storage and pumping. This framework provides mechanical support that maintains the hollow spheres' integrity, preventing density increase over time while the hollow spheres continue to provide density reduction
Solution Approach 2:
The patent specifies precise parameter ranges including hollow sphere particle size (D90 less than 150 μm), shell thickness (1-20 μm), and inorganic filler content (20-80 wt%). These optimized parameters ensure the hollow spheres maintain structural stability during storage and pumping operations, preventing irreversible density increase while maintaining the desired low density
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 a density of less than 1.20 kg/L with enhanced mechanical properties, stable density over time, and easy application without leakage, addressing the limitations of prior art.
Implementation Method 1
microscopic hollow spheres have a density of sometimes well below 1.00 kg/L and, when mixed into moisture-curing compositions, can significantly reduce their resulting overall density
Implementation Method 2
Their curing is achieved through crosslinking reactions, which occur under the influence of water via free or latent reactive groups such as isocyanate or silane groups
Data Source
AI summary
The present invention relates to a moisture-curing composition comprising a) at least one moisture-reactive polymer P with a proportion of 10% to 60% by weight, based on the overall composition, b) at least one inorganic filler F with a proportion of at least 9% by weight, based on the overall composition, c) between 3% and 25% by weight, based on the overall composition, of at least one type of microscopic hollow beads H, characterized in that the composition has a density of less than 1.20 kg/l, preferably less than 1.10 kg/l, and the microscopic hollow beads H have a compressive strength, measured to ASTM D3102-72, of at least 2.5 MPa, preferably at least 5 MPa, and the microscopic hollow beads H have a volume-based particle size D90, measured by a Coulter counter, of less than 100 µm. The moisture-curing composition of the invention has good tensile strength coupled with high extensibility, good application properties with low expression forces, excellent pumping stability, and density stability after pump applications and in the case of prolonged storage, and is of very good suitability as an adhesive, sealant or coating material having low density for insulation applications or lightweight construction.