Advantages and disadvantages of SMS non-woven fabric offline composite process

The off-line composite process means that spunbonded nonwovens and meltblown nonwovens are prepared by spunbonding and meltblown processes respectively, and then the two nonwovens are composited together to form SMS composite nonwovens through composite equipment cloth.


Offline composite SMS needs to go through 3 sets of equipment. Spunbond nonwoven fabric is produced by spunbond production line, meltblown fabric is produced by meltblown production line, and two layers of spunbonded nonwoven fabric are sandwiched in between. The melt-blown cloth is hot-rolled and bonded into a three-layer composite SMS through a special hot-rolling laminating machine.


The main advantages of off-line composite process


Off-line composite process has the following advantages.


(1) High flexibility and strong product adaptability;


(2) Especially suitable for small order production;


(3) If the hot rolling mill is in the form of multiple rolls, it can produce a variety of composite products, not just limited to SMS;


(4) Short production line distance and low maintenance;


(5) Small investment and quick results;


(6) It is conducive to the compounding of materials after functional finishing, which not only guarantees the use performance, but also prevents waste and saves costs;


(7) Suitable for products with high content of composite meltblown non-woven fabrics to improve the water pressure resistance of composite materials;


(8) Rolls with different patterns can be designed to meet corresponding user requirements.


Disadvantages of offline composite process


Off-line composite technology also has its shortcomings, mainly in the following aspects.


(1) Since the melt blown cloth is first rolled and then unrolled, the weight of the melt blown cloth cannot be less than 10g/m2, otherwise the melt blown cloth cannot be compounded due to its low strength, which limits the SMS Produce SMS non-woven fabrics with a meltblown layer above 10g/m2;


(2) Meltblown fabric produced separately, because it does not have the support of S cloth, it is easy to be injured, so it is difficult to guarantee the barrier property and hydrostatic pressure resistance of SMS non-woven fabric, and it is difficult to guarantee SMS non-woven fabric The cloth has good filtering performance, and the uniformity of the SMS non-woven fabric produced in this way is difficult to control;


(3) Because the SMS fabric is made first, the SMS can no longer be adjusted during compounding. It is difficult to guarantee the physical properties of the SMS non-woven fabric made in this way, especially the breathability and strength of the product. Aspect indicators. Even if a problem is found, the only process parameters that can be adjusted are the mill temperature and pressure. At the National SMS Quality Standards Conference in September 2005, some offline composite manufacturers specifically mentioned the strength of SMS non-woven fabrics.


(4) Offline lamination cannot produce thin SMS non-woven fabrics below 30g/m2;


(5) Since the gram weight of the melt blown layer cannot be less than 10g/m2, in order to avoid stratification between SMS when doing SMS, the working temperature and pressure of the hot rolling mill should be increased accordingly, resulting in the product The hand feel is relatively hard, the air permeability is poor, and the strength is poor, especially not suitable for the production of protective clothing. If you only consider the feel of the product to adjust the process, it will cause the SMS to be easily delaminated and the surface of the product will fluff. This shortcoming is a unique problem that cannot be easily overcome in the two-step production of SMS, which seriously affects the SMS nonwoven fabric produced by the two-step method Applications;


(6) The production volume is small. According to the data, the largest offline composite production line in China has an annual output of only 6000t;


(7) Since offline compounding uses the SMS fabric to first make a finished roll and then unwind it, when doing this SMS non-woven fabric, the waste is relatively large and the cost is relatively large, which is not conducive to market competition;


(8) The width of offline composite products is restricted. Most domestic offline composite lines have a width between 1.6 and 2.4m. For application manufacturers, use SMS non-woven fabrics with a width of 1.6m or 2.4m. Will bring a lot of waste to production;


(9) Because it is impossible to make SMS coils with large roll lengths, in this case, due to the different tension control of SMS fabrics, it is difficult to start and end unwinding with three roll lengths at the same time. And the production speed cannot be raised very high, the domestic offline compound production speed is generally below 100m/min;


(10) The roll length of products made by offline compounding cannot be guaranteed to be consistent, and there are joints in the fabric rolls produced, which will affect the customer's use;


(11) When producing color SMS, it is difficult to achieve accurate SMS color, because the color of SMS cloth has been made, but there is no color contrast after compounding, so the color is almost not adjusted, and the production is completely based on experience. Large waste and inaccurate colors.