TPE skin-like soft rubber is transparent, soft and comfortable.
I. Significance of TPE Hardness of Thermoplastic Elastomer
Hardness is the most basic and important physical parameter of thermoplastic elastomer. It can be said that the different hardness of TPE provides a wide range of application industries and produ
Contact 138 2720 9711
Product details
I. Significance of TPE Hardness of Thermoplastic Elastomer
Hardness is the most basic and important physical parameter of thermoplastic elastomer. It can be said that the different hardness of TPE provides a wide range of application industries and products.
For example, TPE with a hardness of about 0A can be used for adult products. TPE with hardness of 35A can be used for disposable rubber bands. TPE with hardness of 60A is generally used for various tool handles, erasers, etc.
II. Main Hardness Units of TPE
The principle of hardness measurement is generally to test TPE of different hardness with special hardness tester and indenter of different shapes. During the test, the indenter is pressed vertically on the surface of TPE test samples, and the stress of the indenter shows different test values.
TPE materials with general hardness below 10A are suitable for Shore C table, hardness unit SHORE C,OO, or pressure head of Q,C table is curved surface. TPE with hardness of 10~90A is suitable for Shore A hardness meter, hardness unit Shore A; TPE with hardness above 90A is applicable to SHORE D table, hardness unit Shore D. ..
Another measurement method is to press steel balls with a diameter of about 2.5mm on the test piece at a low contact pressure for a period of time, measure the depth of the pressed test piece, and calculate the hardness of the material. This method is mainly used to measure TPE with a hardness of about 0A, which is more accurate than the measurement result of Shore C table, and the hardness unit is VLRH. This hardness expression method is seldom used in practice.
Three, grasp the TPE material hardness should pay attention to five factors
The hardness test results of TPE materials are mainly affected by four factors: thickness of test piece, reading time, human error and accuracy of instrument. In fact, sometimes the ambient temperature will also affect the test results of the samples.
3.1. Thickness of test piece
The thickness of the standard TPE test piece is about 6 mm (6.35mm), and the test result is relatively accurate when the thickness is measured. The test piece is thin and the hardness test value is high. The test piece is too thick and the hardness test value is too low.
3.2 Reading Time
Testing TPE hardness and the length of time the durometer pressure head presses the test piece will also affect the measurement accuracy. Because TPE is an elastic material, there will be a deformation time. Some experimenters are used to reading within 5 seconds, while others delay reading after 10~15 seconds. Delayed reading, measured material hardness is softer than immediate reading within 5 seconds.
In principle, the reading time should be noted for hardness data on TPE physical property table.
3.3 Human Error
When different people measure, the difference in measurement details will lead to errors, such as casual measurement, the pressure head is not perpendicular to the surface of the test sample; Or directly test the thickness of the template with non-standard thickness and uneven surface, so the test results are often inaccurate.
3.4 Measuring Instruments
The measuring instrument is out of order, such as the dial does not return to zero initially, the pressure head is worn or damaged, etc. Will lead to inaccurate test data.
3.5 ambient temperature
This is a dynamic comparison. For example, the hardness of the same TPE test piece may be softer in summer, while it may be harder in winter (usually about 5 years). The difference in hardness caused by ambient temperature is mainly due to lower temperature, partial crystallization of TPE elastomer segments and hardening of materials.
IV. Influence of Material Proportioning Process on TPE Hardness
The above is to analyze the factors that affect the measurement accuracy from the aspect of measurement method habits. The following is a brief talk on the influence of material ratio and process on TPE hardness.
4.1 material ratio
In the proportioning, the components are not weighed accurately. If the proportion of reinforced plastic is too large, the material will be hard. If there is too much operating oil, the material will be soft.
4.2 granulation process
If the granulation process is not plasticized sufficiently, the TPE materials of the same batch will be hard and soft.
Although the influence of material ratio and process on TPE hardness seems to be avoidable. However, at present in China, TPE production capacity is expanding blindly and extensive production and operation is inevitable under the premise of brutal growth of manufacturers. Hardness problems caused by such reasons are also common.
