Graft Copolymer Binder for Ceramic Green Sheet Strength
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Solution Overview
Problem
Existing binders for ceramic green sheets face challenges in achieving a balance between mechanical strength, flexibility, and thermal decomposability, often resulting in poor sheet properties over time, especially for thin sheets, due to issues like residual carbide formation and moisture absorption.
Innovation Solution
A graft copolymer composed of polyvinyl butyral and poly(meth)acrylic compounds with specific molecular weight ranges and structural characteristics is used as a binder, ensuring uniform performance and reduced viscosity, which enhances mechanical strength, flexibility, and thermal decomposability while minimizing moisture absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyvinyl acetal resin is used alone as a binder, then sheet strength is improved, but thermal decomposability deteriorates causing residual carbide formation or rapid decomposition
Solution Approach 1:
The invention uses a composite binder system combining polyvinyl acetal resin with acrylic resin. The polyvinyl acetal provides sheet strength while the acrylic resin ensures good thermal decomposability and reduces residual carbide formation. This composite approach allows both materials to complement each other's advantages.
Solution Approach 2:
The invention specifies precise parameter ranges for the polyvinyl acetal resin including degree of polymerization (500-2000), hydroxyl content (20-40 mol%), and degree of butyralization (60-80 mol%). These parameter controls optimize the balance between sheet strength and thermal decomposability.
2Reliability
If acrylic resin is used as a binder, then thermal decomposability is improved, but sheet strength and flexibility deteriorate
Solution Approach 1:
The binder combines acrylic resin (providing thermal decomposability) with polyvinyl acetal resin (providing sheet strength and flexibility). The acrylic resin content is controlled at 1-50 wt% to ensure good thermal decomposability while maintaining sufficient mechanical properties through the polyvinyl acetal component.
3Ease of operation
If plasticizer is added to improve flexibility, then sheet flexibility is improved, but moisture absorption increases and sheet properties change over time
Solution Approach 1:
The invention optimizes the hydroxyl content of polyvinyl acetal resin to 20-40 mol%, which provides sufficient flexibility through hydrogen bonding without requiring additional plasticizers. This parameter control prevents moisture absorption issues associated with plasticizer-containing systems.
4Length of stationary object
If ceramic green sheet thickness is reduced for miniaturization, then device size is reduced, but sheet strength decreases and handling becomes difficult
Solution Approach 1:
The invention specifies degree of polymerization of 500-2000 for polyvinyl acetal resin, which provides optimal molecular weight for thin sheet applications. This ensures sufficient entanglement and strength even at reduced thickness while maintaining processability.
Solution Approach 2:
The composite binder system provides enhanced sheet strength that enables production of ultra-thin ceramic green sheets (5 μm or less) suitable for miniaturized electronic devices while maintaining handling capability.
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 binder provides ceramic green sheets with improved mechanical strength, flexibility, and long-term stability, reducing residual carbide formation and moisture absorption, thus maintaining excellent sheet properties during processing and over time.
Implementation Method 1
firing the molded article to sinter the inorganic powder while decomposing and scattering the binder
Data Source
AI summary
The present invention provides a binder for producing an inorganic sintered body having excellent thermal decomposability and capable of providing, especially when used as a binder for a ceramic green sheet, a ceramic green sheet that has sufficient mechanical strength and flexibility, is less likely to absorb moisture, and can maintain its excellent sheet properties over a long period of time. The present invention also provides a paste for producing an inorganic sintered body and a ceramic green molded article each obtained using the binder for producing an inorganic sintered body. The present invention relates to a binder for producing an inorganic sintered body containing a graft copolymer, the graft copolymer having a unit including polyvinyl butyral and a unit including a poly(meth)acrylic compound, the polyvinyl butyral having a degree of polymerization of 800 to 5,000, a hydroxy group content of 20 to 40 mol%, and a degree of butyralization of 60 to 80 mol%, the unit including a poly(meth)acrylic compound having a glass transition temperature of -65°C or higher and lower than 0°C.