Consolidated nonwoven
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing binder compositions for bituminized roofing membranes lack sufficient longitudinal and transverse breaking strengths at room and elevated temperatures, and exhibit poor thermal dimensional stability, leading to potential cracking and loss of waterproof integrity.
Innovation Solution
A water-based binder composition comprising a polymer obtained by free radical aqueous emulsion polymerization of specific monomers, combined with polyvinyl alcohol and optional starch and metal compounds, which provides improved mechanical strength and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binder compositions are used for consolidating nonwovens, then the nonwoven can be processed, but the breaking strengths at room and elevated temperatures are insufficient and thermal dimensional stability is poor
Solution Approach 1:
The patent uses a composite binder system combining polyacrylic acid with starch and polyvinyl alcohol, creating a multi-component material that synergistically improves both strength and thermal stability. The polyacrylic acid provides adhesive bonding, starch contributes to dimensional stability and rigidity, while polyvinyl alcohol enhances flexibility and strength, particularly at elevated temperatures.
Solution Approach 2:
The patent optimizes specific parameters including the molecular weight of polyacrylic acid (10^5 to 10^7), the degree of hydrolysis of polyvinyl alcohol (70-99%), and the precise weight ratios of components (20-80% polyacrylic acid, 10-40% starch, 5-30% polyvinyl alcohol). These parameter optimizations ensure the binder maintains appropriate viscosity, adhesion, and mechanical properties across a wide temperature range.
2Ease of manufacture
If the nonwoven is stretched during heat treatment, then coating can proceed, but tensions are fixed that cause cracking when reheated
Solution Approach 1:
The binder composition is formulated to maintain optimal viscosity and flexibility at processing temperatures (160-200°C), allowing the nonwoven to be stretched and coated without excessive tension. The polyvinyl alcohol component specifically contributes to maintaining flexibility at elevated temperatures, preventing the fixation of harmful tensions that would lead to cracking during subsequent reheating operations.
Solution Approach 2:
The binder system dynamically adapts its mechanical properties across different temperature stages: at processing temperature it remains flexible to accommodate stretching and coating, while upon cooling it sets with minimal internal tension. This dynamic behavior prevents the fixation of permanent tensions that would cause cracking during later reheating cycles.
3Strength
If the roofing membrane is made stiff and inflexible to improve strength, then structural integrity improves, but fine cracks occur which destroy waterproof effect
Solution Approach 1:
The tri-component binder system creates a balanced composite where polyacrylic acid provides structural adhesive strength, starch contributes to rigidity and dimensional stability, while polyvinyl alcohol maintains flexibility and elongation capacity. This composite structure prevents the formation of fine cracks that would compromise waterproofing while maintaining overall structural integrity.
Solution Approach 2:
The binder composition creates different local properties within the consolidated nonwoven: the polyacrylic acid-starch matrix provides structural strength and rigidity, while the polyvinyl alcohol phases maintain local flexibility and crack resistance. This spatial distribution of different material properties allows the membrane to resist both structural failure and crack formation.
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 binder composition enhances breaking strengths at room and elevated temperatures and reduces thermal dimensional stability issues, ensuring the integrity and waterproof performance of bituminized roofing membranes.
Implementation Method 1
a polymer P, wherein the polymer P is obtainable by free radical aqueous emulsion polymerization of a monomer mixture
Implementation Method 2
consolidated by treatment with a binder composition comprising thermally crosslinkable polymeric binder
Data Source
AI summary
The present invention relates to a consolidated nonwoven consolidated by treatment with an aqueous binder composition comprising:a polymer P,a polyvinyl alcohol,optional a starch compound S andoptional at least one metal compound M selected from the group consisting of magnesium, calcium and zinc, in the form of an oxide, hydroxide, carbonate or bicarbonate,wherein the polymer P is obtainable by free radical aqueous emulsion polymerization of a monomer mixture of75 to 99% by weight of one or more monomers a) selected from the group consisting of esters of acrylic and/or methacrylic acid with alkanols of 1 to 12 carbon atoms, aliphatic conjugated diene and aromatic vinyl compound1 to 25% by weight of one or more monomers b) selected from the group consisting of N-methylolacrylamide, N-methylolmethacrylamide, glycidyl methacrylate and carboxylic acid-functional ethylenically unsaturated monomers≥0 to 15% by weight of one or more further ethylenically unsaturated monomer c) different from any of monomers a) and b)wherein the amounts of monomers a) to c) sum to 100 wt %,the water-based binder composition, the process of for producing the consolidated nonwoven and its use as reinforcing insert for bituminized roofing membranes.