Crosslinkable Aliphatic Polycarbonate Adhesive Resin With Low Tg
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Solution Overview
Problem
Conventional polycarbonate resins, including polyalkylene carbonate resins, have high glass-transition temperatures (Tg) due to their rigidity, making them unsuitable for applications requiring flexibility and as pressure sensitive adhesives, and they struggle to exhibit good adhesive strength to both high-polarity and low-polarity materials.
Innovation Solution
Development of an aliphatic polycarbonate resin with an ether structure in the main chain and crosslinkable functional groups in the side chains, produced using carbon dioxide as a raw material, which is randomly copolymerized with specific repeating units to achieve a low Tg and enhanced adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polycarbonate resins are used, then thermal stability is achieved, but flexibility is poor due to high glass-transition temperature
Solution Approach 1:
The patent changes the chemical structure parameters of the polycarbonate resin by introducing ether structures in the main chain and controlling the ratio of aliphatic polycarbonate units to polycarbonate units. This structural parameter change reduces the glass-transition temperature from conventional high values to below -50°C, thereby improving flexibility while maintaining thermal stability through the crosslinkable functional groups.
Solution Approach 2:
The invention creates a composite resin system combining aliphatic polycarbonate units with polycarbonate units containing crosslinkable functional groups. This composite structure integrates the flexibility benefits of ether-containing aliphatic polycarbonate with the thermal stability and adhesion properties of crosslinkable polycarbonate, resolving the contradiction between flexibility and thermal stability.
2Strength
If acrylic-based pressure sensitive adhesives are used, then adhesive strength to high-polarity materials is good, but adhesive strength to low-polarity materials is poor
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating both polar carbonate groups and non-polar hydrocarbon groups in specific ratios. The polycarbonate units provide polarity for adhesion to high-polarity substrates, while the hydrocarbon portions provide compatibility with low-polarity substrates, achieving broad adhesive versatility through compositional parameter optimization.
Solution Approach 2:
The resin structure exhibits local quality differentiation where different segments of the polymer chain have different polarities. The carbonate groups provide polar character for bonding to high-polarity materials, while hydrocarbon segments provide non-polar character for interaction with low-polarity materials, enabling the single resin to adapt to multiple substrate types.
3Reliability
If the resin structure is made rigid for thermal stability, then thermal stability is improved, but flexibility deteriorates
Solution Approach 1:
The patent optimizes the compositional parameters by controlling the ratio of aliphatic polycarbonate units to polycarbonate units containing crosslinkable functional groups. This parameter optimization ensures that the resin maintains thermal stability through the crosslinkable groups while achieving flexibility below -50°C glass-transition temperature through the ether-containing aliphatic polycarbonate segments.
4Strength
If crosslinkable functional groups are added to improve adhesion, then adhesive strength is improved, but manufacturing complexity increases
Solution Approach 1:
The resin contains crosslinkable functional groups that enable self-crosslinking through simple heating or UV irradiation without requiring complex external crosslinking agents or catalysts. This self-service approach improves adhesive strength through crosslinking while minimizing manufacturing complexity by using the resin's own functional groups for the crosslinking reaction.
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 resulting resin exhibits good adhesive strength to both high-polarity and low-polarity materials, with improved holding power and flexibility, suitable for use in pressure sensitive adhesives and other applications.
Implementation Method 1
Patent Document 2 proposes a photopolymerizable composition that contains a monomer mainly comprising an alkyl (meth)acrylate having a 2-12C alkyl group, a tackifying resin, and a photopolymerization initiator and that is photopolymerized by ultraviolet rays
Data Source
AI summary
An aliphatic polycarbonate resin having an ether structure in its main chain and having a structure in which a repeating unit represented by Formula (Ia) below, a repeating unit represented by Formula (Ib) below, a repeating unit represented by Formula (Ic) below, and a repeating unit represented by Formula (Id) below are randomly copolymerized, wherein R1 and R2 are each a hydrocarbon group whose carbon number is 6 or more, and may be the same or different, and R3 and R4 are each a hydrocarbon group having a crosslinkable functional group and may be the same or different.