Block Copolymer Resin Composition for Balanced Impact and Transparency
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Solution Overview
Problem
Conventional resin compositions containing block copolymers of vinyl aromatic hydrocarbons and conjugated dienes struggle to achieve a balance between high impact resistance and transparency in formed products like sheets and films without compromising other properties such as folding strength and elastic modulus in tension.
Innovation Solution
A resin composition with specific content ratios of conjugated diene and vinyl aromatic hydrocarbon, molecular weight distribution, and dynamic viscoelasticity characteristics, including a loss tangent with a local maximum value within a certain temperature range, is developed to enhance impact resistance and transparency while maintaining other properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content ratio of conjugated diene is increased to improve impact resistance, then transparency and rigidity deteriorate
Solution Approach 1:
The patent optimizes the content ratio of conjugated diene within a specific range (5-20 mass%) and controls the molecular weight distribution (Mw/Mn between 1.05-1.30) to achieve the best balance between impact resistance and transparency. This parameter optimization resolves the contradiction by finding the optimal point where both properties are satisfied simultaneously.
2Illumination intensity
If the block ratio of vinyl aromatic hydrocarbon is increased to improve transparency and rigidity, then impact resistance deteriorates
Solution Approach 1:
The patent specifies that the block ratio of vinyl aromatic hydrocarbon should be between 80-95%, which is a controlled parameter change that ensures sufficient transparency and rigidity while maintaining adequate impact resistance through the balanced composition.
3Strength
If the molecular weight is increased to improve mechanical strength, then processability and folding strength deteriorate
Solution Approach 1:
The patent controls the molecular weight distribution by specifying Mw/Mn between 1.05-1.30 and weight average molecular weight between 100,000-300,000. This narrow molecular weight distribution ensures good processability while maintaining adequate mechanical strength, resolving the contradiction between these properties.
4Strength
If the loss tangent peak temperature is shifted to improve low-temperature impact resistance, then high-temperature properties deteriorate
Solution Approach 1:
The patent positions the loss tangent peak temperature within -80°C to -20°C, which optimizes low-temperature impact resistance while the specific compositional parameters (conjugated diene content, block ratio, molecular weight) ensure that high-temperature properties are maintained.
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 resin composition achieves balanced high impact resistance and transparency in formed products without decreasing folding strength, elastic modulus, or sheet impact, by optimizing the block copolymer's structure and properties through precise control of molecular weights and viscoelasticity.
Implementation Method 1
the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement has one local maximum value (tan δ (max)) within a temperature range of from −90 to −30° C., and tan δ (tan δ (max+30° C.)) at a temperature higher by 30° C. than the temperature at the local maximum value (tan δ peak temperature) is in a specific proportion relative to tan δ (tan δ (max)) at the temperature at the local maximum value
Data Source
AI summary
To provide a resin composition containing a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, from which a formed product such as a sheet or a film, having excellent transparency and impact resistance, can be obtained. A resin composition containing a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, which satisfies the following (A) to (D):(A) the content ratio (mass) of the conjugated diene is from 22 to 32%,(B) the block ratio of the vinyl aromatic hydrocarbon is from 90 to 98%,(C) Mw/Mn (wherein Mw is the weight average molecular weight and Mn is the number average molecular weight) is from 1.1 to 1.6 obtained by GPC by differential refractive index method,(D) the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement has one local maximum value (tan δ (max)) within a temperature range of from −90 to −30° C., and tan δ (tan δ (max+30° C.)) at a temperature higher by 30° C. than the temperature at the local maximum value (tan δ peak temperature) is at least 0.6 relative to tan δ (tan δ (max)) at the temperature at the local maximum value.