Soft Touch Polypropylene Composition for Spunbond Nonwovens
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Solution Overview
Problem
Current polypropylene compositions for spun bond nonwoven fabrics face challenges in achieving high softness while maintaining tensile strength and elongation at break, with existing methods either complicating reactor conditions or reducing fiber processability.
Innovation Solution
A polypropylene composition comprising a random copolymer of propylene and ethylene or α-olefin, combined with a C10-C30 aliphatic carboxylic acid amide and a nucleating agent, specifically a metal salt of hexahydrophthalic acid, which improves softness and maintains tensile properties, and can be processed into fibers with high throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the molecular weight of polypropylene is decreased to impart softness, then softness is improved, but difficulty in controlling reactor conditions increases
Solution Approach 1:
The invention changes the chemical composition parameters by incorporating specific comonomers (ethylene and/or α-olefins with 4-6 carbon atoms) at controlled levels (1.0-10.0 wt%) to achieve softness without requiring molecular weight reduction, thereby avoiding reactor control difficulties
Solution Approach 2:
The invention creates a composite polypropylene system by combining polypropylene with specific comonomers and additives (C10-C30 aliphatic carboxylic acid amide and nucleating agent) to achieve softness through compositional modification rather than molecular weight control
2Shape
If comonomer is incorporated to impart softness, then softness is improved, but tenacity decreases which narrows the thermos-bonding window
Solution Approach 1:
The invention optimizes comonomer content within a specific range (1.0-10.0 wt%) to achieve softness while maintaining adequate tenacity, and introduces a nucleating agent to enhance crystallization and restore thermal bonding properties
Solution Approach 2:
The nucleating agent acts as an intermediary that compensates for the tenacity reduction caused by comonomer incorporation, enabling thermos-bonding by promoting crystallization without requiring high comonomer levels
3Shape
If higher level of comonomers is used to impart softness, then softness is improved, but processability of fibers for making spun bond fabrics deteriorates
Solution Approach 1:
The invention limits comonomer content to a controlled range (1.0-10.0 wt%) and combines it with specific additives to achieve softness while maintaining fiber processability, avoiding the negative effects of excessive comonomer levels
4Strength
If polypropylene homopolymer is used to maintain tensile strength, then tensile strength is maintained, but softness is reduced
Solution Approach 1:
The invention creates a composite system combining polypropylene with comonomers and softening additives (C10-C30 aliphatic carboxylic acid amide) to achieve both softness and maintained tensile strength through synergistic composition design
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 softness and maintains tensile strength and elongation at break, with improved processability and higher throughput, outperforming polypropylene homopolymer-based fibers in terms of softness and production efficiency.
Implementation Method 1
a nucleating agent comprising a metal salt of hexahydrophthalic acid
Data Source
AI summary
The invention relates to a composition comprising: (A) a random copolymer of propylene and a comonomer, wherein the comonomer is ethylene and/or an α-olefin having 4 to 8 carbon atoms, wherein the amount of propylene-derived units is 90 to 99 wt % and the amount of comonomer-derived units is 1.0 to 10 wt % based on the random copolymer, (B) a C10-C30 aliphatic carboxylic acid amide and (C) a nucleating agent comprising a metal salt of hexahydrophthalic acid represented by formula (I) wherein M1 and M2 are the same or different, and may be combined into one cation, and are selected from at least one metal cation of calcium, strontium, lithium, and monobasic aluminum; and wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are either the same or different and are individually selected from the group consisting of hydrogen, C1-C9 alkyl, hydroxy, C1-C9 alkoxy, C1-C9 alkyleneoxy, amine, and C1-C9 alkylamine, halogens, and phenyl, wherein the amount of (B) in the composition is 1000 to 5000 ppm based on the total weight of the composition and the amount of (C) in the composition is 100 to 1000 ppm based on the total weight of the composition.