Methacrylic Copolymer Block Structure for Viscosity Control
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Solution Overview
Problem
The existing methods for producing (meth)acrylic-based copolymers with alkoxysilyl groups result in high viscosity after storage at high temperatures, limiting their application in sealing materials and adhesives.
Innovation Solution
A composition comprising a (meth)acrylic-based copolymer with an XY diblock or XYX triblock structure, where the X block contains a higher concentration of alkoxysilyl groups and the Y block has a minimal amount, combined with an epoxy compound to inhibit hydrolysis and crosslinking, thereby maintaining low viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a (meth)acrylic-based copolymer with alkoxysilyl groups is produced by conventional polymerization methods, then productivity is improved, but storage viscosity becomes high after storage at high temperature
Solution Approach 1:
The copolymer is divided into distinct blocks: X blocks containing alkoxysilyl groups and Y blocks without alkoxysilyl groups. This segmentation prevents uniform distribution of reactive groups, reducing unwanted crosslinking during storage while maintaining productivity benefits of conventional polymerization methods.
Solution Approach 2:
Alkoxysilyl groups are localized specifically in X blocks rather than being uniformly distributed throughout the copolymer chain. The Y blocks serve as spacers with minimal alkoxysilyl content (0-3 wt%), creating local regions of different functionality that reduce overall viscosity while preserving crosslinking capability where needed.
2Strength
If alkoxysilyl groups are distributed throughout the copolymer chain, then crosslinking capability is improved, but viscosity increases due to premature hydrolysis and crosslinking
Solution Approach 1:
The copolymer architecture segments alkoxysilyl-containing X blocks from each other using Y blocks as spacers. This segmentation reduces the probability of premature hydrolysis and intermolecular crosslinking during storage, while still providing sufficient alkoxysilyl groups for effective crosslinking when cured under appropriate conditions.
Solution Approach 2:
Y blocks act as intermediary segments between X blocks, physically separating alkoxysilyl groups and reducing their mutual interaction during storage. This intermediary structure prevents premature crosslinking while allowing the copolymer to maintain its crosslinking capability when activated.
3Speed
If the copolymer is stored at high temperature, then processing speed is improved, but viscosity increases due to accelerated hydrolysis and crosslinking
Solution Approach 1:
The copolymer is pre-synthesized with controlled block structure and low molecular weight distribution (Mw/Mn ≤ 1.8) to minimize premature crosslinking before use. This preliminary structural control allows the material to withstand high-temperature storage and processing conditions without excessive viscosity increase, enabling faster processing.
Solution Approach 2:
The molecular weight distribution parameter is tightly controlled (Mw/Mn ≤ 1.8) to reduce polydispersity and minimize the presence of high molecular weight species that would otherwise crosslink more readily at elevated temperatures. This parameter control allows high-temperature processing while maintaining acceptable viscosity levels.
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 combination effectively reduces storage viscosity and improves stability at high temperatures, enhancing the workability and mechanical properties of the copolymer-based materials.
Implementation Method 1
A polymer molecule having an alkoxysilyl group forms, by hydrolysis of the alkoxysilyl group, a siloxane bond with another polymer molecule.
Implementation Method 2
a siloxane bond with another polymer molecule. Then, it is known that a rubbery cured product is obtained by this crosslinking reaction.
Implementation Method 3
combined with an epoxy compound to inhibit hydrolysis and crosslinking, thereby maintaining low viscosity
Data Source
AI summary
A composition with improved storage viscosity is provided. The composition contains a (meth)acrylic-based copolymer (A′) and an epoxy compound (C). A molecule of the (meth)acrylic-based copolymer (A′) includes an XY diblock structure or an XYX triblock structure therein. A number of repeating units which are derived from a (meth)acrylic ester monomer having an alkoxysilyl group and are included in an X block is 1.0 or more on average; an amount of repeating units which are derived from a (meth)acrylic ester monomer having an alkoxysilyl group and are included in a Y block is 0% by weight to 3% by weight, with respect to a weight of all repeating units included in the Y block. A molecular weight distribution (Mw/Mn) of the (meth)acrylic-based copolymer (A′) is 1.8 or less.