Impact Resistant Acrylic Alloy Melt Processability
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Solution Overview
Problem
Impact modified acrylic resin formulations face impaired melt processability due to increased melt viscosity from core/shell modifiers, which also compromises other physical properties like chemical resistance when attempting to improve mechanical properties.
Innovation Solution
Incorporating a low melt viscosity polymer, such as polylactic acid, that is miscible with the acrylic polymer, along with a hard-core core/shell impact modifier to enhance melt processability while maintaining or improving mechanical and chemical resistance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If core/shell impact modifiers are added to improve impact strength, then impact resistance is improved, but melt viscosity increases and melt processability deteriorates
Solution Approach 1:
The patent changes the molecular weight parameter of the acrylic polymer matrix by incorporating low molecular weight acrylic polymer additives (5-50 parts by weight per 100 parts of acrylic polymer). This parameter change reduces the overall molecular weight and thus reduces melt viscosity, improving melt processability while maintaining impact resistance through the core/shell modifiers
Solution Approach 2:
The patent creates a composite formulation combining acrylic polymer, core/shell impact modifiers, and low molecular weight acrylic polymer additives. This composite approach allows the system to benefit from the impact resistance of core/shell modifiers while the low molecular weight additive component addresses the melt viscosity issue, achieving both improved impact strength and maintained melt processability
2Ease of manufacture
If molecular weight of acrylic polymer is decreased to improve melt processability, then melt viscosity decreases and processability improves, but resistance to chemical attack deteriorates
Solution Approach 1:
The patent applies local quality by using only 5-50 parts by weight of low molecular weight acrylic polymer additive per 100 parts of acrylic polymer. This limited, localized use of low molecular weight polymer provides sufficient melt processability improvement while minimizing the degradation of chemical resistance, as the majority of the polymer matrix (100 parts) remains high molecular weight acrylic polymer with good chemical resistance
3Strength
If core/shell modifiers with rubbery core layer are used to improve impact resistance, then impact strength is improved, but modulus and UV resistance deteriorate
Solution Approach 1:
The patent introduces an intermediary shell layer made of glassy polymer that is compatible with the acrylic polymer matrix. This shell layer acts as a mediator between the rubbery core and the acrylic matrix, allowing the core to provide impact strength while the shell maintains modulus and UV resistance by being compatible with and integrated into the acrylic polymer matrix
Data Source
AI summary
The invention relates to an acrylic polymer, modified with one or more hard core core/shell impact modifier, which is blended with one or more low melt viscosity polymer. The alloy formed by the blend has good impact properties, good melt processability, high modulus, high surface hardness, and excellent resistance to chemical attack.