Professional Operation - Paste Formula and System Improvement (I)

Fourth -- "No need to complain about the paste again and again"

China, like other development regions, faces all kinds of great changes and growth. New demands and high quality standards come to you. Carton boxes are used to package and sell products from home and abroad. These cartons require the same quality and packaging functions as the products themselves. This is not the same as before. The order specifications you received are color accuracy and carton pressure resistance. These stringent specifications require you to revisit the corrugated board manufacturing process. This has also caused many manufacturers to purchase new high-tech control system new equipment to meet new requirements. When purchasing paper, you also require it to achieve a certain level of quality in order to ensure that the final manufactured cartons achieve the required quality and functionality.

The three major elements of corrugated board production: base paper, machinery equipment and pastes. Because the base paper accounts for 60% of the total cost, it receives the highest priority. Machine equipment is also an important tool for producing cardboard tools. However, the paste is different. It only accounts for 2% to 3% of the total cost. It doesn't seem to be taken seriously. Although paste is indispensable during the manufacturing process, many carton manufacturers still hold different views. I have heard customers say this: “Our operating methods have been like this since the beginning and why we need to change it.”

When using artificially prepared pastes, due to human factors, in many occasions, only a single formula of paste can be used to make a variety of cardboards of different textures, and the viscosity of the paste cannot be controlled. The paste prepared is of different quality in each batch. In this issue, most of the solutions provided to you are for you to use additives to supplement. Yes, these traditional assembly lines can solve some problems. However, this is not a permanent solution. It does not eradicate the real paste problem, but only slightly reduces the viscosity of the paste. I have also seen that some single-bucket paste blending methods that are rarely used in the world have also been introduced to China and introduced to manufacturers. This situation needs immediate correction. The era of passing pigeons has passed, and now is the era of e-mail high-tech! If the production equipment and technology are not commensurate, then the new corrugated board production line you invest in will not be fully used and wasted.

As an equipment manufacturer, we studied the above defects in detail. The conclusion is that you only use one or two different viscosity paste formulations. The paste formulation requirements for A, B and C waves (楞) and E, F and N waves (楞) vary. According to the principle of heat conduction, different recipes must be used on the upper and lower layers of the double-sided machine. The definition of the nature of paste can be divided into the following three: viscosity, gelatinization (gelation) temperature and solid content (Figure 1).

On this picture, it clearly indicates where the formula is used. Some papers are of poor quality, low permeability, or high water absorption; they require specific infiltration capabilities, so the paste formulation can be adjusted to match these requirements.

The reason why you don't do this is that the answer is simple. Pasting three or four formulas is too time-consuming. Ordinary systems are not competent and your starch or additive suppliers are helpless.

Therefore, the requirements for many paste qualities and formulations have to be compromised and reconciled. The reason for the compromise is very simple. It may be that the volume of the paste system currently in place is large and the time required for deployment is long. Ordinary batches are 2500 cubic meters to 3000 cubic meters, deployment time is about more than an hour. To provide two different recipes, two vats are needed to store paste for more than two hours. If more than two formulas are used, the storage tank will need to be bigger, very cumbersome, and occupying the place, it will be difficult to work. Furthermore, the paste in the storage tank will be transported to the paste machine of each corrugated paper machine and its paste circulation line when it is used. During this process, the paste will be subjected to more pressure and shear again, and the viscosity of the paste will begin to decrease and thin, resulting in the emergence of various problems in paperboard bonding. The reason why the viscosity of the paste becomes lower is because the paste prepared by using conventional paste making equipment is used in the preparation. Because the viscosity of the paste cannot be pushed to its stable viscosity during the preparation, the paste is used for a period of time. With more pressure and shear, the viscosity begins to drop. Another reason for the compromise is due to the design flaws on the system, human error and inconvenience of operation. It takes a long time to complete each batch and cannot deploy multi-formulation pastes, causing the factory to give up the use of multi-formulation pastes.

In the daily production of corrugated board, due to the decrease of the viscosity of the paste prepared using the traditional type, the operator will increase the amount of paste to compensate for the change in the viscosity of the paste, hoping that this will reduce the chance of poor adhesion. For example, employees will add more paste on the lower layer of the double-sided machine. Because that is the paste of the same formulation, the speed may have to be adjusted downwards to fully evaporate the water in the paste when the amount of upper paste is increased. At the same time: other possible conditions will occur one after another.

E.g:

◆ The cardboard is unevenly curved ◆ The cardboard is broken ◆ When the box is made, the upper cardboard is easily damaged ◆ The appearance of “washboard” like corrugated cardboard and ribs ◆ Foaming ◆ Degumming, poor adhesion

The use of modified starch can help stabilize the viscosity of the paste, but it results in increased costs. Stable paste viscosity can indeed increase production and efficiency, but the price of modified starch is high, increase the cost, and can not be used! The use of additives, stabilizers can enhance the function of the paste, or better meet the requirements of the production environment. Perhaps for those traditional systems, it may make a difference and help. Don't forget that with these additives and stabilizers, the cost has increased and is long-term. These added costs are "absorbed" by cardboard. There is no direct manifestation. So most users can accept it. As mentioned earlier, it is not low cost but it is not noticeable.

Based on the above situation and description, the ideal arrangement is of course to prepare the required pastes according to the respective paste recipes required. The paste quality of each batch must remain the same, and the paste viscosity must remain stable. Different corrugated combinations, different types of corrugated paper and cardboard, providing the specific different pastes required to the different pasting machines.

E.g:

E and F require higher paste solids content. Because the number of B and C enthalpies is less than the enthalpy of E and F per metre of medium, relatively low solid content formulas are required.

1. The upper layer and the lower layer of the double-sided adhesive are different from the surface of the hot plate, so the solid content and the gelatinization temperature of the required paste are not the same;

2. Paste and single-sided and double-sided pastes have different powder-water ratios and pasting temperatures.

3. When it is required that the paste penetrates into the inner layer of the base paper, the caustic soda content of the formula will increase;

4. Different base paper qualities require specific recipes.

High solids content or low powder to water ratio is another factor that affects the quality of corrugated board. It reduces the moisture ratio in the paste, directly reducing the drying time and reducing the drying temperature, thus saving energy. However, the conventional paste preparation system is limited and it is difficult to bring out an ideal high solids paste.

(to be continued)