Tissue papermakers are constantly searching to improve parameters, such as:
- Better Yankee protection.
- Better reel profile.
- Better softness.
- Higher bulk for lower fibre utilisation with weight reduction.
- Increase stretch, so that wire weight can be maximised, improve bulk and maximise productivity by increasing reel speed/reducing crepe ratio and achieve specs.
- Optimum yield, minimum raw material and production costs at target specifications.
There are several contributors to achieving this.
- Having a very protective (bulky and robust) coating, which can increase the protection of the surface, life of the blade and consequently the quality of the paper.
- Having a coating layer which can assist the softness of the paper albeit softness is more fibre related – short, less coarse fibre and refiner manipulation. However, a coating layer soft and bulky with some softener in it can help.
In addition to the fibre an optimised blade is the key.
Using latest technology AXCHEM can offer a range of high quality, innovative solutions. Axchem base coating products portfolio includes alkaline products made of 100% polymer which are very reactive and non-corrosive to the on the Yankee surface.
This is very important in case of steel or a metalized Yankee surface – the important thing here is avoiding metal to metal contact, so a thick robust coating layer is important.
Axchem Group: chemicals for the paper industry
Our products are designed to optimize mainly the following parameters:
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Picture 2. Thanks to the better Yankee surface coverage, it is also possible to get a better reel profile. A soft protective film to give the best paper quality performance. A nice bulky and robust coating to manipulate very soft grades (or bulky grades, pending blade choice), helps the tissue maker manipulate the coating and blade pocket angle to achieve optimum specifications with good Yankee protection facilitating organic and natural coating layer working well together.
- High protection of the Yankee cylinder surface – should be first point.
- Very homogeneous drying and producing the highest production speed. Some coatings (natural coating) can harm thermal conductivity, but major impact on speed is often “over-achieving” stretch so the reel speed can be increased.
- High paper softness.
- Optimum coating set up and more forgiving of CD moisture profile should lead to an absence of dark stripes on the Yankee and consequent translucent stripes on the roll.
- Fast reaction and rapid control of all the production process variations.
- A bulky soft but robust coating for blade to ride in and develop optimum parameters and cylinder protection, rather than bounce along the hard mix of hard organic and fines related coating, which wears the blade prematurely and can lead to chatter.
- Coating treatment could be made of two products instead of three. Although if it’s a metallised cylinder in particular, MAP will almost certainly have to be used.
Based on our historical cases, we can summarise that, using Axchem coating products it’s possible to achieve following benefits:
- Better yankee coverage and consequently better reel profile.
As shown on the above pictures, we have got a better yankee surface coverage and consequently a better reel profile (picture 2). This is probably due to the chemical composition of our base coating which is made of 100% polymer with no PAE inside. Our coating products can react even if the temperature of the Yankee is low or not optimal. In this condition, it’s also easier to rebuild the layer of the coating after the blade changing. However, this depends on how much natural coating vs organic coating there is and blade angle, etc. - Better paper softness. Using our coating is possible to have a better paper creping and consequently a softer paper. Checking the paper with a microscope, we can see that analysing the paper produced with our coating and with the competitor coating, the number of the “crepe” (or “wave”) is higher using the combination of Axchem products compared with competitor treatment. Using our coating we have 10 crepes in 1,25 mm. Using the competitor 10 crepes in 1,49 mm.
- Blade consumption. Using a steel blade in combination with the high protection level of our product, it’s possible to reduce the blade wear. Blade wear after 10 hours using competitor coating: 1,03 mm (picture 4b). Blade wear after 10 hours using Axchem coating: 0,76 mm. (picture 4a).
