Gradient Block Copolymer Adhesive Melt Processability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acrylic hot-melt-type adhesives face challenges in combining melt processability and holding power, especially at high temperatures and under load, while also requiring good transparency and weather resistance, which existing technologies fail to adequately address.
Innovation Solution
A block copolymer with a gradient copolymer block structure, specifically represented by a formula (I) with a polymer block composed of methacrylic acid ester units and a copolymer block composed of acrylic and methacrylic acid ester units, having a controlled molecular weight and monomer sequence distribution, is used to enhance both processability and holding power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hot-melt-type adhesive is used to eliminate solvent drying steps and improve productivity, then productivity and environmental load are improved, but holding power at high temperature and under load decreases
Solution Approach 1:
The patent uses a block copolymer composed of a polymer block and a copolymer block with gradient structure, creating a composite material system where each block contributes different properties. The polymer block provides structural integrity while the copolymer block with gradient composition enhances adhesive performance, resulting in both high holding power and good melt processability.
Solution Approach 2:
The copolymer block contains a gradient copolymer section where the copolymerization ratio continuously changes from one end to the other. This local variation in composition allows different regions of the same block to exhibit different properties, enabling the material to simultaneously achieve good melt processability and high holding power.
2Strength
If block copolymer with gradient structure is used to improve holding power, then holding power is improved, but melt processability deteriorates
Solution Approach 1:
The patent carefully controls the copolymerization ratio gradient, the weight-average molecular weight (30,000 to 300,000), and the molecular weight distribution (1.0 to 1.5) of the block copolymer. By optimizing these parameters, the material achieves both high holding power and good melt processability, resolving the contradiction between strength and ease of manufacture.
3Ease of manufacture
If wide molecular weight distribution is used to improve melt processability, then melt processability is improved, but holding power decreases
Solution Approach 1:
The patent specifies a narrow molecular weight distribution (Mw/Mn ratio of 1.0 to 1.5) for the block copolymer. This controlled parameter ensures that the polymer chains have similar lengths, providing uniform adhesive performance and high holding power while maintaining adequate melt processability through the gradient copolymer structure.
4Productivity
If hot-melt coating at low temperature and high speed is performed to improve productivity, then productivity is improved, but holding power has room for improvement
Solution Approach 1:
The block copolymer is pre-designed with an optimal gradient copolymer structure and molecular weight distribution before the coating process. This preliminary structural optimization ensures that the adhesive achieves both high holding power and good melt processability, enabling effective hot-melt coating at low temperature and high speed without compromising holding power.
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 adhesive achieves improved melt processability, high holding power, good weather resistance, and transparency, allowing for efficient hot-melt coating at low temperatures and maintaining adhesive performance over time without the need for solvent drying.
Implementation Method 1
the block copolymer forms a microphase separation structure
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
Provided are an acrylic hot-melt adhesive that has both good hot-melt processability and good holding power, that is suitable for applications to a hot-melt coating method in which coating is performed at a low temperature at a high speed, that has good transparency and good weather resistance, and that further has good adhesiveness at low temperatures, and a block copolymer suitable for use in the adhesive. Prepared is an adhesive containing a block copolymer having at least one structure represented by a general formula: - [A1]-[B/A2]- (where, in the formula, [A1] represents a polymer block composed of a structural unit derived from a methacrylic acid ester (A1), [B/A2] represents a copolymer block composed of a structural unit derived from an acrylic acid ester (B) and a structural unit derived from a methacrylic acid ester (A2), and the copolymer block [B/A2] has a gradient copolymer block section in which a copolymerization ratio of the methacrylic acid ester (A2) continuously increases from a section connected to the polymer block [A1]), and having a total content of the structural units derived from the methacrylic acid ester (A1) and the methacrylic acid ester (A2) of 5% to 60% by mass, a weight-average molecular weight (Mw) of 30,000 to 300,000, and a molecular weight distribution (Mw/Mn) of 1.0 to 1.5.