Polypropylene Impact Copolymer Hot Melt Adhesive Bond Retention
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Solution Overview
Problem
Hot melt adhesives used in the manufacturing of disposable goods, such as diapers, face challenges in achieving high bond strength and retention under mechanical and thermal stress, particularly when using non-woven and elastomeric materials, where styrenic block copolymers are not effectively replaced by other polymers like metallocene-based olefinic polymers due to lack of adhesive bond retention.
Innovation Solution
A hot melt adhesive composition utilizing polypropylene impact copolymers, combined with olefin-based elastomers and tackifying resins, which provides improved adhesion, creep resistance, and thermal stability, allowing for bonding of non-woven materials and elastomeric substrates with enhanced mechanical and thermal resistance without the need for styrenic block copolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If metallocene-based olefinic polymers are used to replace styrenic block copolymers, then the adhesive can be processed with improved flow characteristics, but the adhesive bond retention under mechanical and thermal stress deteriorates
Solution Approach 1:
The patent uses a composite polymer system combining metallocene-based olefinic polymer (providing flow characteristics) with polypropylene impact copolymer (providing bond retention). This composite approach allows the adhesive to achieve both improved processability and reliable bond retention that cannot be obtained with single polymers alone.
2Strength
If styrenic block copolymers are used to achieve high bond strength, then the adhesive provides good bond retention, but the adhesive requires higher application temperatures and has limited adaptability to heat-sensitive substrates
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating polypropylene impact copolymer with specific ethylene content (5-20%) and utilizing metallocene-based olefinic polymers with controlled comonomer content. These parameter changes enable the adhesive to achieve high bond strength at lower application temperatures, expanding adaptability to heat-sensitive substrates.
3Strength
If olefin polymers with low crystallinity are used to improve adhesion characteristics, then the adhesive shows better adhesion, but the adhesive lacks bond retention under mechanical stress
Solution Approach 1:
The patent applies local quality by creating a multi-phase system where metallocene-based olefinic polymer provides local adhesion zones with low crystallinity, while polypropylene impact copolymer provides local reinforcement zones with higher strength. This spatial differentiation of properties allows simultaneous achievement of good adhesion and bond retention.
Data Source
AI summary
A hot melt adhesive using polypropylene impact copolymers that is particularly well suited for elastic attachment and stretch films in diaper structures. The hot melt adhesive composition is a blend of about 2.5% to about 30%, by weight, of a polypropylene impact copolymer; about 2.5% to about 30%, by weight, of an olefin based elastomer; about 10% to about 70%, by weight, of a tackifying resin having a softening point of at least about 80° C. and up to about 140° C.; about 0% to about 60%, by weight, of a plasticizer; and about 0.1% to about 5% of a stabilizer or antioxidant.