Composite Resin Particles via Three-Step Polymerization
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Solution Overview
Problem
Existing methods for producing composite resin particle dispersions often result in products with inadequate tackiness in pressure bonding, poor storage stability, and a tendency for sheet tearing after storage, particularly in summer environments.
Innovation Solution
A method involving three polymerization steps: A, B, and C, where a styrene-based resin is first formed, then intermediate resin particles containing both styrene-based and (meth)acrylic acid ester-based resins are produced, and finally, composite resin particles are formed in the presence of these intermediate particles, with a specific mass ratio of styrene-based to (meth)acrylic acid ester-based resin and a defined difference between the glass transition temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only two polymerization steps (A and B) are used to form intermediate resin particles, then the production process is simpler and faster, but the resulting adhesive shows inadequate tackiness in pressure bonding and poor storage stability
Solution Approach 1:
The polymerization process is divided into three distinct segments: Step A (forming styrene-based resin particles), Step B (forming intermediate particles with both styrene-based and acrylic acid ester-based resins), and Step C (forming final composite particles with additional styrene-based resin). This segmentation allows each step to contribute specific properties, with Step C specifically adding the tackiness component without disrupting the storage stability established in Steps A and B.
Solution Approach 2:
Steps A and B are performed first to preliminarily establish the resin particle structure with good storage stability. The tackiness-enhancing styrene-based resin is then added in Step C as a preliminary action before final product formation, ensuring both stability and tackiness are built into the structure in advance.
2Reliability
If intermediate resin particles are formed with high content of acrylic acid ester-based resin to improve flexibility, then the adhesive becomes too soft and loses storage stability, but reducing acrylic acid ester content improves storage stability while reducing tackiness
Solution Approach 1:
The composite resin particles exhibit local quality differentiation where the core contains acrylic acid ester-based resin providing flexibility, while the surface and matrix contain styrene-based resin providing tackiness. This is achieved through the three-step polymerization where different resin types are incorporated at different stages and locations within the particle structure.
Solution Approach 2:
The invention creates a composite resin system combining two distinct resin types (styrene-based and acrylic acid ester-based) with complementary properties. The styrene-based resin contributes tackiness and structural integrity, while the acrylic acid ester-based resin provides flexibility and processability, achieving both high tackiness and storage stability through material composition.
3Productivity
If the polymerization is conducted in a single step to simplify the process, then productivity increases, but the resulting particles cannot achieve the required glass transition temperature difference of 30°C or more
Solution Approach 1:
The three-step polymerization process enables precise control of composition parameters at each stage. Step A establishes the styrene-based resin foundation, Step B incorporates acrylic acid ester-based resin to adjust Tg, and Step C fine-tunes the styrene-based resin content. This sequential parameter adjustment ensures the final particles achieve the required ΔTg ≥ 30°C while maintaining production efficiency.
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 method enhances tackiness in pressure bonding and improves storage stability, preventing sheet tearing after storage, while maintaining the pressure-induced phase transition properties of the composite resin particles.
Implementation Method 1
the composite resin particles have a glass transition temperature difference (T1-T2) of 30° C. or more... pressure-induced phase transition properties
Data Source
AI summary
A method for producing a composite resin particle dispersion includes: performing polymerization A by polymerizing a styrene compound and a vinyl monomer other than the styrene compound to form a styrene-based resin; performing polymerization B by polymerizing a (meth)acrylic acid ester compound in the presence of the styrene-based resin to form intermediate resin particles containing the styrene-based resin and a (meth)acrylic acid ester-based resin; and performing polymerization C by polymerizing a styrene compound and a vinyl monomer other than the styrene compound in the presence of the intermediate resin particles to form composite resin particles. The mass ratio of the styrene-based resin to the (meth)acrylic acid ester-based resin in the composite resin particles is from 80:20 to 20:80. A difference between the lowest glass transition temperature and the highest glass transition temperature in the composite resin particles is 30° C. or more.