PVC Polymer Blend with Crosslinked Acrylic Core
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Solution Overview
Problem
Current PVC formulations face challenges in achieving mechanical strength, flexibility, dimensional stability, and weatherability due to the migration of phthalate plasticizers and limitations in existing impact modifiers.
Innovation Solution
A polymer blend comprising 20-90 parts by weight of polyvinyl chloride resin and 10-80 parts by weight of a flexible acrylic polymer with a crosslinked core, intermediate layers, and an outermost layer, where the crosslinked core has a Tg of -85 to -10 °C, intermediate layers transition between -30 °C and 70 °C, and the outermost layer has a Tg of 40 °C to 110 °C, enhancing mechanical properties and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phthalate plasticizers are incorporated into PVC formulations to improve flexibility, then flexibility is improved, but plasticizers migrate out over time causing loss of mechanical properties
Solution Approach 1:
The patent extracts and eliminates phthalate plasticizers from the PVC formulation entirely, replacing them with a flexible acrylic polymer impact modifier that provides flexibility without migration issues. The impact modifier contains a rubber core with low Tg values that provides the needed flexibility through its polymer structure rather than through migratable plasticizer molecules.
Solution Approach 2:
The patent uses a composite impact modifier structure consisting of a rubber core with specific Tg range (-85 to -10°C) surrounded by an acrylic shell. This composite structure provides flexibility through the rubber core's low glass transition temperature while the acrylic shell prevents migration and maintains long-term mechanical properties.
2Strength
If existing impact modifiers are used to improve mechanical strength, then impact resistance is improved, but dimensional stability and weatherability are compromised
Solution Approach 1:
The patent employs a core-shell composite impact modifier where the rubber core provides impact resistance through its low Tg (-85 to -10°C) and the acrylic shell provides dimensional stability and weatherability. The shell acts as a protective barrier that maintains the structural integrity and environmental resistance of the PVC product.
Solution Approach 2:
The patent applies different material properties to different regions of the impact modifier: the core region contains rubber with low Tg for impact absorption, while the shell region contains acrylic polymer for dimensional stability and weatherability. This local differentiation of material properties resolves the contradiction between impact resistance and stability.
3Reliability
If flexible acrylic polymer with crosslinked core and intermediate layers is used to improve mechanical strength and stability, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the acrylic polymer into distinct functional regions: a crosslinked core region for structural stability, intermediate layers with specific Tg ranges for flexibility control, and an outer shell for environmental resistance. This segmentation allows each region to perform its specific function optimally while maintaining overall reliability.
Solution Approach 2:
The patent controls the glass transition temperatures of different regions within the impact modifier to achieve desired mechanical properties. The core has Tg of -85 to -10°C, intermediate layers transition between -30°C and 70°C, providing a gradient of flexibility that balances strength and stability without excessive structural complexity.
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 polymer blend provides improved mechanical strength, flexibility, and dimensional stability, while reducing the migration of plasticizers, thereby enhancing the performance and durability of PVC-based products.
Implementation Method 1
the crosslinked core has a Tg of from -85 to -10 °C
Implementation Method 2
there is a compositional gradient between the intermediate layers and said compositional gradient transitions between a lower Tg and an upper Tg, wherein said lower Tg is at least -30 °C and said upper Tg is 70 °C or less
Implementation Method 3
an outermost layer which comprises from 98.5 to 100 weight percent units derived from one or more monomers selected from the group consisting of alkyl (meth)acrylate, styrenic monomers, and combinations of two or more thereof, from 0 to 1.5 weight percent units derived from one or more chain transfer agents, and has a Tg of from 40 °C to 110 °C
Data Source
AI summary
A polymer blend comprising from 20 to 90 parts by weight, based on the total weight of the polymer blend, polyvinyl chloride resin; and from 10 to 80 parts by weight, based on the total weight of the polymer blend, a flexible acrylic polymer is provided. Also provided are films or sheets or pipe made from the polymer blend, a capstock made from the film and a method for preparing a film.