Tire Rubber Composition for Mold Release Without Wet Grip Loss
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Solution Overview
Problem
The rubber composition used in tires forms a hard film on the surface due to paraffin wax, leading to poor mold releasability, followability on uneven road surfaces, and initial wet grip performance, which is further exacerbated by whitening when stored in high-temperature and high-humidity environments.
Innovation Solution
A rubber composition comprising 0.5 to 2.0 parts by mass of a branched alkane with 40 to 70 carbon atoms, 1.2 parts by mass or less of a linear alkane with 45 or more carbon atoms, and 0.1 to 100 parts by mass of a hydrocarbon resin with a weight-average molecular weight of 300 to 15,000, along with 1.2 parts by mass or less of a linear alkane with 20 to 32 carbon atoms, to improve mold releasability and wet grip performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If paraffin wax is used as a mold releasing agent, then mold releasability is improved, but initial wet grip performance deteriorates due to hard film formation
Solution Approach 1:
The patent changes the molecular structure parameter of the wax from linear (paraffin) to highly branched (isotridecyl alcohol derivative), which fundamentally alters the film-forming properties. The branched structure prevents crystallization and hard film formation while maintaining mold releasability, thus resolving the contradiction between ease of operation and reliability.
Solution Approach 2:
The patent uses a composite approach by combining the branched alcohol compound with specific rubber components (SBR, BR) and other additives in controlled proportions. This composite formulation ensures that the mold releasing function is achieved without the harmful hard film effect, balancing mold releasability and wet grip performance.
2Reliability
If paraffin wax is used for ozone crack resistance, then crack resistance is improved, but whitening occurs on rubber surface in high temperature and humidity
Solution Approach 1:
The patent changes the chemical structure parameter from linear paraffin to a highly branched alcohol derivative with specific carbon chain length (C13). This structural modification maintains the protective function against ozone cracking while eliminating the whitening phenomenon that occurs with linear waxes under high temperature and humidity conditions.
Data Source
AI summary
A rubber composition comprising a rubber component and 0.3 to 3 parts by mass of a branched alkane having 40 to 70 carbon atoms, 1.2 parts by mass or less of a linear alkane having 45 or more carbon atoms and 0.1 to 100 parts by mass of a hydrocarbon resin having a weight-average molecular weight of 300 to 15,000 based on 100 parts by mass of the rubber component.