03.10.22
TSRC, formerly known as Taiwan Synthetic Rubber Corp., has developed a new type of high-strength, highly elastic, Styrene-Isoprene-Styrene (SIS) copolymer in response to the application requirements of personal hygiene elastic films. In addition to improving the strength of the film, the new SIS also enhances the material’s melt strength, making it more suitable for blown film processing. Odor performance has been significantly improved by newly installed pelletizing equipment, which effectively reduces the amount of volatile organic compounds (VOCs).
TSRC was established in 1973 by founder Glyn T.H. Ing to support the government’s policy on developing a petrochemical industry in Taiwan. TSRC has evolved from a synthetic rubber manufacturer to a leader in today’s synthetic rubber and Styrenic Block Copolymer (SBC) markets. The company’s products have been highly acclaimed and widely adopted by major customers all over the world. TSRC’s annual output of SBR, BR, NBR, TPE, compounding and other synthetic rubbers has reached 805,000 tons. All its manufacturing plants have successively obtained QC 080000 and ISO 50001 international certifications.
Headquartered in Taiwan, TSRC is vigorously expanding its business to establish production bases and commercial teams in China (Nantong in Jiangsu and Song-Jiang in Shanghai), Thailand, India, Vietnam, the U.S. and Luxembourg to service the growing demand of worldwide customers.
Introduction:
TSRC is one of the leading suppliers of high quality thermoplastic elastomers (TPE). The company uses advanced elastomer design and production technology to provide a series of styrene copolymer elastomer products and solutions.
SIS is the thermoplastic elastomer polymer [1] that has the processing properties of plastic and elastic properties without the need for vulcanization. Out of these properties, SIS has the following performance advantages for elastic films:
In recent years, due to the increasing demand for elastic film stretch components, manufacturers have been looking for new ways to improve strength. This can be accomplished by adjusting the compound formulation into the following two approaches:
I. High strength plastic is mixed to increase the strength of the film, but the addition of plastic sacrifices the elastic properties.
II. Polystyrene resin can be added to increase film strength, at the sacrifice of generating a serious odor problem, which is not suitable for the personal hygiene market’s sensitivity to such issues.
The above formulation adjustment approaches must be combined with consideration of melt processing and conversion equipment. A pre-mixing system, suitable compounding extrusion screws, and film die configuration must be optimized to produce a quality elastic film with uniform thickness.
On the other hand, due to the poor melt strength of customary SIS, the bubble stability for blown film processing is insufficient, which limits the material’s application in blown film processing.
To resolve the above-mentioned disadvantages of customary SIS, TSRC improved the film and melt strength of this novel SIS by increasing the styrene content and adjusting the molecular structure. A schematic diagram of the strength and elasticity of thin films based on new and conventional SIS is shown in Figure 1.
Experimental:
A. Materials:
The new high-strength SIS VECTOR 4258ND/4359ND are developed as improved versions of SIS VECTOR 4111ND/4211ND respectively. The specifications of the new high-strength SIS VECTOR and the traditional SIS VECTOR materials are shown in Table 1.
B. Cast film sample preparation:
Labtech experimental casting equipment (LCR300) were used to produce film samples. The related equipment parameter settings are as follows:
I. Single screw temperature setting range: 170~220ºC
II. Screw rotation setting: 30RPM
III. Output elastic film thickness: 100um
C. Film strength and elasticity performance test
An Instron 33R4464 tensile tester was used to evaluate film strength and elastic properties. Tests were performed in accordance with ASTM D-882 in the perpendicular direction of film extrusion.
The elastic hysteresis test method consists of two stretching cycles. The test results are shown in the stress-strain curve in Figure 2. The first cycle at 200% strain is intended to simulate the activation process between the elastic film and PP nonwoven. The second stretching cycle at 100% strain aims to evaluate the stress and elastic properties of the diaper elastic film. Therefore, the performance indicator of the elastic film focuses on the second cycle.
The performance indicator and definition are as follows:
I. Tensile stress at 100% strain (point D in Figure 2): One of the performance indicators of thin film strength.
II. Elastic recovery stress at 50% un-load stress (point E in Figure 2): The elastic recovery stress can be used as an index of the required elastic performance when a diaper is worn.
III. Permanent set (point F in Figure 2): The ability of an elastic component to resist tensile deformation during the stretching process.
D. Test to assess the extensional viscosity of melts:
The Rheotens test was used to measure melt strength of the material at 170°C, which is a commonly used processing temperature for blown films.
E. Volatile Organic Compound (VOC) testing:
Head Space GC was used to test the residual VOCs of SIS materials on fresh production sample.
F. Results and discussion:
I. Mechanical properties of elastic film:
Comparison of the thin film strength performance of VECTOR 4111ND/4258ND and of VECTOR 4211ND/4359ND is shown by the stress-strain curves Figure 3 and of tensile properties in Table 2. Since the styrene content and molecular structure of the new type of VECTOR SIS has been adjusted, the tensile strength performance was significantly improved.
In addition, the modulus performance at lower strains (100%/300%) has also been significantly enhanced. As shown in Figure 4 and Table 2, the above-mentioned improvements confirm the design concept and capabilities of the new high-strength SIS VECTOR 4258ND/4359ND, i.e., it can effectively improve the thin film strength and modulus performance.
II. Elasticity performance of elastic film
The indicators of elastic performance can be divided into: The performance of 50% un-load stress, permanent set and the hysteresis. These are shown in Figure 5 and Table 3. The new high-strength SIS VECTOR significantly improves the elastic recovery stress of thin films while maintaining low permanent set.
III. Melt strength and draw-ability result:
Bubble stability is crucial for blown film processing and is highly correlated with the melt strength of the material; therefore, higher levels of melt strength usually result in better blown film. When comparing the conventional SIS with the new SIS, VECTOR 4111ND/4258ND and VECTOR 4211ND/4359ND, the Rheotens test results, as shown in Figure 6 and Table 4, show that high strength VECTOR SIS has better melt strength and extensibility than conventional VECTOR SIS. Therefore, high-strength VECTOR SIS is more suitable for blown film processing.
IV. Reduction of odor in SIS and improvement of quality in film products:
Head Space GC was used to compare the VOCs before and after the new pelletizer was installed. The results show that VECTOR SIS produced with the new pelletizing equipment has a 73% reduction in VOCs. Therefore, the quality of diapers and masks, whose consumers are sensitive to odors, has been significantly improved.
Conclusions:
In response to the new application requirements of thin elastic films, TSRC has developed high-strength/high-elasticity VECTOR SIS materials that can effectively improve the strength of thin elastic films. Furthermore, the material’s melt strength has also been significantly improved, making them very suitable for blown film processing. In terms of odor performance, the newly installed pelletizing equipment effectively reduces the content of VOCs, significantly minimizing the material’s odor, and improving the quality of film products.
Sources:
1. D. Handlin, Z. Cheng, and M. Berard, ANTEC Tech. Paper. (2015)
TSRC was established in 1973 by founder Glyn T.H. Ing to support the government’s policy on developing a petrochemical industry in Taiwan. TSRC has evolved from a synthetic rubber manufacturer to a leader in today’s synthetic rubber and Styrenic Block Copolymer (SBC) markets. The company’s products have been highly acclaimed and widely adopted by major customers all over the world. TSRC’s annual output of SBR, BR, NBR, TPE, compounding and other synthetic rubbers has reached 805,000 tons. All its manufacturing plants have successively obtained QC 080000 and ISO 50001 international certifications.
Headquartered in Taiwan, TSRC is vigorously expanding its business to establish production bases and commercial teams in China (Nantong in Jiangsu and Song-Jiang in Shanghai), Thailand, India, Vietnam, the U.S. and Luxembourg to service the growing demand of worldwide customers.
Introduction:
TSRC is one of the leading suppliers of high quality thermoplastic elastomers (TPE). The company uses advanced elastomer design and production technology to provide a series of styrene copolymer elastomer products and solutions.
SIS is the thermoplastic elastomer polymer [1] that has the processing properties of plastic and elastic properties without the need for vulcanization. Out of these properties, SIS has the following performance advantages for elastic films:
- Soft touch and comfort-fitting
- High elasticity and good hysteresis performance
- Easy to recycle
In recent years, due to the increasing demand for elastic film stretch components, manufacturers have been looking for new ways to improve strength. This can be accomplished by adjusting the compound formulation into the following two approaches:
I. High strength plastic is mixed to increase the strength of the film, but the addition of plastic sacrifices the elastic properties.
II. Polystyrene resin can be added to increase film strength, at the sacrifice of generating a serious odor problem, which is not suitable for the personal hygiene market’s sensitivity to such issues.
The above formulation adjustment approaches must be combined with consideration of melt processing and conversion equipment. A pre-mixing system, suitable compounding extrusion screws, and film die configuration must be optimized to produce a quality elastic film with uniform thickness.
On the other hand, due to the poor melt strength of customary SIS, the bubble stability for blown film processing is insufficient, which limits the material’s application in blown film processing.
To resolve the above-mentioned disadvantages of customary SIS, TSRC improved the film and melt strength of this novel SIS by increasing the styrene content and adjusting the molecular structure. A schematic diagram of the strength and elasticity of thin films based on new and conventional SIS is shown in Figure 1.
Experimental:
A. Materials:
The new high-strength SIS VECTOR 4258ND/4359ND are developed as improved versions of SIS VECTOR 4111ND/4211ND respectively. The specifications of the new high-strength SIS VECTOR and the traditional SIS VECTOR materials are shown in Table 1.
B. Cast film sample preparation:
Labtech experimental casting equipment (LCR300) were used to produce film samples. The related equipment parameter settings are as follows:
I. Single screw temperature setting range: 170~220ºC
II. Screw rotation setting: 30RPM
III. Output elastic film thickness: 100um
C. Film strength and elasticity performance test
An Instron 33R4464 tensile tester was used to evaluate film strength and elastic properties. Tests were performed in accordance with ASTM D-882 in the perpendicular direction of film extrusion.
The elastic hysteresis test method consists of two stretching cycles. The test results are shown in the stress-strain curve in Figure 2. The first cycle at 200% strain is intended to simulate the activation process between the elastic film and PP nonwoven. The second stretching cycle at 100% strain aims to evaluate the stress and elastic properties of the diaper elastic film. Therefore, the performance indicator of the elastic film focuses on the second cycle.
The performance indicator and definition are as follows:
I. Tensile stress at 100% strain (point D in Figure 2): One of the performance indicators of thin film strength.
II. Elastic recovery stress at 50% un-load stress (point E in Figure 2): The elastic recovery stress can be used as an index of the required elastic performance when a diaper is worn.
III. Permanent set (point F in Figure 2): The ability of an elastic component to resist tensile deformation during the stretching process.
D. Test to assess the extensional viscosity of melts:
The Rheotens test was used to measure melt strength of the material at 170°C, which is a commonly used processing temperature for blown films.
E. Volatile Organic Compound (VOC) testing:
Head Space GC was used to test the residual VOCs of SIS materials on fresh production sample.
F. Results and discussion:
I. Mechanical properties of elastic film:
Comparison of the thin film strength performance of VECTOR 4111ND/4258ND and of VECTOR 4211ND/4359ND is shown by the stress-strain curves Figure 3 and of tensile properties in Table 2. Since the styrene content and molecular structure of the new type of VECTOR SIS has been adjusted, the tensile strength performance was significantly improved.
In addition, the modulus performance at lower strains (100%/300%) has also been significantly enhanced. As shown in Figure 4 and Table 2, the above-mentioned improvements confirm the design concept and capabilities of the new high-strength SIS VECTOR 4258ND/4359ND, i.e., it can effectively improve the thin film strength and modulus performance.
II. Elasticity performance of elastic film
The indicators of elastic performance can be divided into: The performance of 50% un-load stress, permanent set and the hysteresis. These are shown in Figure 5 and Table 3. The new high-strength SIS VECTOR significantly improves the elastic recovery stress of thin films while maintaining low permanent set.
III. Melt strength and draw-ability result:
Bubble stability is crucial for blown film processing and is highly correlated with the melt strength of the material; therefore, higher levels of melt strength usually result in better blown film. When comparing the conventional SIS with the new SIS, VECTOR 4111ND/4258ND and VECTOR 4211ND/4359ND, the Rheotens test results, as shown in Figure 6 and Table 4, show that high strength VECTOR SIS has better melt strength and extensibility than conventional VECTOR SIS. Therefore, high-strength VECTOR SIS is more suitable for blown film processing.
IV. Reduction of odor in SIS and improvement of quality in film products:
Head Space GC was used to compare the VOCs before and after the new pelletizer was installed. The results show that VECTOR SIS produced with the new pelletizing equipment has a 73% reduction in VOCs. Therefore, the quality of diapers and masks, whose consumers are sensitive to odors, has been significantly improved.
Conclusions:
In response to the new application requirements of thin elastic films, TSRC has developed high-strength/high-elasticity VECTOR SIS materials that can effectively improve the strength of thin elastic films. Furthermore, the material’s melt strength has also been significantly improved, making them very suitable for blown film processing. In terms of odor performance, the newly installed pelletizing equipment effectively reduces the content of VOCs, significantly minimizing the material’s odor, and improving the quality of film products.
Sources:
1. D. Handlin, Z. Cheng, and M. Berard, ANTEC Tech. Paper. (2015)
