As a seasoned supplier of PE laminated non woven fabric, I've witnessed firsthand the challenges that come with controlling the shrinkage rate of this versatile material. The shrinkage of PE laminated non woven fabric can significantly impact its quality, dimensions, and performance, which in turn affects the end - use applications. In this blog, I'll share some effective strategies based on my years of experience in the industry.
Understanding the Causes of Shrinkage in PE Laminated Non Woven Fabric
Before we delve into the control methods, it's crucial to understand why shrinkage occurs. Shrinkage in PE laminated non woven fabric is mainly caused by two factors: thermal and mechanical.
Thermal shrinkage happens when the fabric is exposed to high temperatures. The polyethylene (PE) layer, which has a relatively low melting point, tends to contract when heated. This contraction can lead to a reduction in the overall size of the fabric. For example, during the drying or heat - setting processes in manufacturing, if the temperature is not carefully controlled, the PE layer may start to shrink.
Mechanical shrinkage, on the other hand, is a result of external forces applied to the fabric. During the production process, such as winding, unwinding, or cutting, the fabric may be stretched or compressed. If the fabric is not properly relaxed after these mechanical operations, it can shrink when it is later used or stored.
Controlling Thermal Shrinkage
Precise Temperature Management
One of the most effective ways to control thermal shrinkage is to manage the temperature during the manufacturing process. In the lamination process, the temperature of the PE film and the non - woven substrate should be carefully monitored. For instance, when using extrusion lamination, the extrusion temperature of the PE resin needs to be set within a specific range. If the temperature is too high, the PE will flow more easily but may also cause excessive shrinkage. A typical temperature range for extruding low - density polyethylene (LDPE) is around 180 - 220°C.
During the heat - setting stage, which is often used to stabilize the fabric structure, the temperature should be gradually increased and then decreased. This slow heating and cooling process allows the fabric to adjust to the temperature changes without sudden shrinkage. For example, a heat - setting machine can be programmed to heat the fabric at a rate of 5 - 10°C per minute to a maximum temperature of 120 - 130°C, hold it for a few minutes, and then cool it at a similar rate.
Annealing Treatment
Annealing is another useful technique for reducing thermal shrinkage. After the lamination process, the fabric can be subjected to an annealing treatment. This involves heating the fabric to a temperature below its melting point and holding it for a certain period. The annealing process helps to relieve the internal stresses in the PE layer and the non - woven substrate. For PE laminated non woven fabric, an annealing temperature of around 80 - 100°C for 1 - 2 hours can significantly reduce shrinkage.
Controlling Mechanical Shrinkage
Proper Tension Control
Tension control is vital during the manufacturing process to prevent mechanical shrinkage. When the fabric is being wound or unwound on rollers, the tension should be kept consistent. If the tension is too high, the fabric will be stretched, and when the tension is released, it may shrink. For example, in a slitting and rewinding machine, the tension of the fabric should be set according to the thickness and width of the fabric. A general rule of thumb is to keep the tension between 1 - 5 N/m for most PE laminated non woven fabrics.
Relaxation Time
Allowing the fabric sufficient relaxation time after mechanical operations is also crucial. After cutting, folding, or other mechanical processes, the fabric should be left to rest for a period. This relaxation time allows the fabric to return to its natural state and reduces the likelihood of shrinkage. For example, after cutting a large roll of fabric into smaller pieces, the pieces can be stacked and left for at least 24 hours before further processing or packaging.
Material Selection
The choice of raw materials can also have a significant impact on the shrinkage rate of PE laminated non woven fabric.
Non - Woven Substrate
The type and quality of the non - woven substrate play an important role. Non - woven fabrics made from different fibers have different shrinkage characteristics. For example, polyester non - woven fabrics generally have lower shrinkage rates compared to polypropylene non - woven fabrics. When selecting a non - woven substrate, it's important to consider its thermal stability and mechanical properties. A high - quality non - woven substrate with good dimensional stability can help to reduce the overall shrinkage of the PE laminated fabric.
PE Film
The properties of the PE film also matter. Different grades of PE have different shrinkage rates. Low - density polyethylene (LDPE) has a relatively higher shrinkage rate compared to linear low - density polyethylene (LLDPE). By choosing the right grade of PE film, you can better control the shrinkage of the laminated fabric. Additionally, the thickness of the PE film can also affect shrinkage. Thicker PE films may have a higher tendency to shrink, so it's important to balance the thickness according to the requirements of the end - use application.
Quality Control and Testing
Regular quality control and testing are essential to ensure that the shrinkage rate of the PE laminated non woven fabric is within the acceptable range.
Sampling and Testing
Random samples should be taken from each production batch for shrinkage testing. The samples can be tested using standard methods, such as heating the samples in an oven at a specific temperature for a certain time and then measuring the change in dimensions. The test results can be used to adjust the manufacturing process if the shrinkage rate is higher than the specified limit.
Monitoring and Adjustment
Continuous monitoring of the manufacturing process is necessary. By monitoring parameters such as temperature, tension, and material properties, any potential issues that may lead to excessive shrinkage can be detected early. For example, if the temperature in the heat - setting oven starts to deviate from the set value, the control system can automatically adjust the heating elements to maintain the correct temperature.
In conclusion, controlling the shrinkage rate of PE laminated non woven fabric requires a comprehensive approach that includes precise temperature management, proper tension control, material selection, and quality control. By implementing these strategies, we can ensure that the fabric meets the high - quality standards required by our customers.
At our company, we offer a wide range of PE laminated non woven fabric products, including PE Laminated SMS High Absorbent, Coated Non Woven Fabric For Construction, and Blue PE Laminated Viscose. If you are interested in our products or have any questions about controlling the shrinkage rate of PE laminated non woven fabric, please feel free to contact us for further discussion and potential procurement.
References
- "Nonwoven Fabric Handbook", edited by David H. Price, Elsevier, 2017.
- "Polyethylene: Structure, Blends, and Composites", by L. A. Utracki, Hanser Publishers, 2007.
- Technical reports from industry associations related to non - woven fabric manufacturing.