Tire Bead Filler Rubber Composition Balancing Adhesion and Pumpability
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Solution Overview
Problem
Conventional rubber compositions are unsatisfactory in terms of pumpability, dripping resistance, processability, and reactivity, and the cured products lack rubber elasticity and adhesion to various substrates.
Innovation Solution
A modified liquid diene rubber with specific properties, including a functional group derived from an acid anhydride, is used to create a rubber composition that exhibits excellent pumpability, dripping resistance, processability, and reactivity, resulting in cured products with enhanced rubber elasticity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rubber compositions are used, then adhesion with respect to metals is improved, but pumpability deteriorates
Solution Approach 1:
The patent modifies the liquid diene rubber by introducing functional groups (carboxyl, hydroxyl, or amino groups) to change its chemical parameters. This modification enables the rubber to achieve both good adhesion to metals and satisfactory pumpability by altering the molecular structure and reactivity of the base rubber without compromising its flow properties
2Strength
If modified liquid diene rubber with functional groups is used, then adhesion with respect to substrates is improved, but processability deteriorates
Solution Approach 1:
The patent introduces functional groups at specific locations on the rubber molecule (side chains or terminal positions) rather than uniformly throughout the entire polymer structure. This localized modification allows the rubber to maintain its bulk processing characteristics while providing enhanced adhesion properties at the interface with substrates
3Ease of manufacture
If conventional rubber compositions are used, then manufacturing simplicity is maintained, but reactivity deteriorates
Solution Approach 1:
The functional groups are pre-introduced into the liquid diene rubber during its synthesis or modification stage, before the rubber is used in final product manufacturing. This preliminary functionalization ensures high reactivity is built into the material itself, eliminating the need for additional complex reaction steps during subsequent manufacturing processes
4Strength
If rubber composition is optimized for reactivity, then adhesion of cured products is improved, but rubber elasticity deteriorates
Solution Approach 1:
The patent carefully controls the type and quantity of functional groups introduced into the liquid diene rubber. By selecting specific functional groups (carboxyl, hydroxyl, or amino) and controlling their concentration, the rubber achieves optimal balance between adhesion enhancement and maintenance of elastic properties in the cured product
Data Source
AI summary
The invention provides a tire bead filler rubber composition. Cured products obtained from such a rubber composition exhibit excellent rubber elasticity, mechanical characteristics (rigidity) and adhesion with respect to various substrates. The tire bead filler rubber composition comprises 100 parts by mass of a solid rubber (B) , 1 to 20 parts by mass of a modified liquid diene rubber (A) having a functional group (a) derived from an acid anhydride, and satisfies all the requirements (I) to (III) below, 5 to 40 parts by mass of a phenolic resin (C) and 0.5 to 2.0 parts by mass of a curing agent (D): (I) The functional group equivalent weight of the functional groups (a) is in the range of 400 to 3,500 g/eq. (II) The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 5,000 to 20, 000. (III) The melt viscosity at 38°C is not less than 3 Pa·s and X (K) is not less than 6100 K wherein X is the slope of a linear line passing through two points in a graph in which the two points are values of melt viscosity η (Pa·s) at 38°C and 60°C measured with a Brookfield viscometer which are plotted as Ln [η/(Pa·s)] on ordinate versus 1/T (K-1) on abscissa (with the proviso that T is temperature (K)).