Modified Liquid Diene Rubber Composition for Pumpability and Adhesion
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Solution Overview
Problem
Conventional rubber compositions are unsatisfactory in pumpability, dripping resistance, processability, and reactivity, and the cured products do not meet the requirements for rubber elasticity and adhesion to various substrates.
Innovation Solution
A curable resin composition comprising a modified liquid diene rubber with specific molecular and viscosity properties, combined with a curable resin such as epoxy or unsaturated polyester, which includes a functional group derived from an acid anhydride, and a resin curing agent, to enhance pumpability, dripping resistance, and reactivity, resulting in cured products with excellent rubber elasticity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rubber compositions are used, then adhesion properties are improved, but pumpability and processability deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the functional group equivalent weight (400-3,500 g/eq) and number average molecular weight (5,000-20,000) of the modified liquid diene rubber. This optimization balances the adhesion properties provided by functional groups with the pumpability determined by molecular weight and viscosity, resolving the contradiction between strong adhesion and easy pumping.
2Strength
If conventional rubber compositions are used, then adhesion properties are improved, but reactivity deteriorates
Solution Approach 1:
The patent optimizes the functional group equivalent weight to a specific range (400-3,500 g/eq) to ensure sufficient reactive sites for crosslinking while maintaining adhesion. This parameter control resolves the contradiction by providing the right balance between adhesion strength and curing reactivity.
3Strength
If conventional rubber compositions are used, then adhesion properties are improved, but dripping resistance deteriorates
Solution Approach 1:
The patent controls the number average molecular weight (5,000-20,000) and melt viscosity (≥3 Pa·s at 38°C) to prevent dripping while maintaining adhesion. The higher molecular weight provides dripping resistance, while the controlled functional group content maintains adhesion properties.
4Ease of operation
If modified liquid diene rubber with specific properties is used, then pumpability and processability are improved, but molecular weight control becomes more difficult
Solution Approach 1:
The patent establishes specific parameter ranges (Mn: 5,000-20,000, functional group equivalent weight: 400-3,500 g/eq) that optimize both processability and molecular weight control. These defined ranges provide clear manufacturing targets, making the process more controllable despite the complexity of modifying liquid diene rubber.
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 modified liquid diene rubber composition exhibits improved pumpability, dripping resistance, and processability, and the cured products demonstrate enhanced rubber elasticity, mechanical characteristics, and adhesion to various substrates, making them suitable for applications like sealing materials and tire bead fillers.
Implementation Method 1
by being crosslinked, give crosslinked products which exhibit excellent adhesion with respect to adherends and other surfaces
Implementation Method 2
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
Data Source
AI summary
The invention provides a modified liquid diene rubber, and a composition including the modified liquid diene rubber which are each excellent in pumpability, dripping resistance and reactivity and give cured products having excellent rubber elasticity, and which are suitably used in or as a sealing material, a tire bead filler, etc. A modified liquid diene rubber (A) has a functional group (a) derived from an acid anhydride, and satisfies all the requirements (I) to (III) below: (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)) .