How is high quality coated paper producing

Coated paper is a type of cardboard that can be used for coated cups, has high stiffness and high water resistance, and is generally pure paper. Coated paper is a type of liquid wrapping paper that is used for a relatively short period of time, generally tens of minutes to a week, after the liquid is contained. Depending on the requirements of the original coated paper, it needs to be resistant to water, oil, lactic acid, hydrogen peroxide and other properties.

The ratio of the pulp of each layer of the coated paper varies depending on the requirements of the product, the ratio of fiber raw materials will have some changes, but usually within the following range: face bottom pulp: 30% to 50% of coniferous wood pulp, 50% to 70% of broad leaf wood pulp; core pulp: 5% to 15% of coniferous wood pulp, broad leaf wood pulp.

Pulp 20% to 30%, mechanical pulp 30% to 60%, damaged paper 10% to 20%.

In addition to the general quality requirements and indicators of white cardboard, coated paper also has some other special requirements. High standard and high quality are mainly in the following aspects.

1. High stiffness

Stiffness index is an important indicator of coated paper, and improving stiffness is a technical key to the production of coated paper. The main factors affecting stiffness are: the number of layers of cardboard, the choice of fiber raw materials and their ratios, the thickness of cardboard, moisture control, the use of chemical additives, etc.

The effect of thickness on stiffness

In the tightness of the same, stiffness with the thickness of the cubic increase; in the quantitative constant, stiffness with the thickness of the square and increase. The thickness can be improved by some ways as follows.

(1) Decrease the pulping degree and increase the sheet's slackness.

(2) Using high bulk fiber raw materials.

(3) Reduce the press and calendering pressure.

(4) Reducing the tension of the dryer web in the front section of the dryer.

(5) Reduce the use of filler or not.

However, the application of these measures will inevitably have certain negative effects, such as the paper surface becomes rough, affecting the fineness of the coated paper lamination and printing. For the paper surface fineness and stiffness (or thickness) of the contradiction, there are the following measures to improve the paper surface fineness.

(1) optimize the process formula of surface sizing, increase the amount of surface sizing or to ensure that the surface strength of the premise of qualified in the surface sizing starch glue solution to increase the filler.

(2) Spraying raw starch solution to the wet paper sheet at the web part can improve the fineness of the front side of the paper sheet. This side can be used for printing or for lamination when no printing is needed.

(3) Contact your wool supplier to select a wool type with high fineness.

2. High sizing degree

In order to make the coated paper with high sizing degree to meet the requirements of use, it is necessary to use rosin glue and AKD glue for sizing of the coated paper at the same time. AKD sizing agent can provide resistance to penetration of the packaged liquid/prevent lactic acid from penetrating into the paperboard from the edge but cannot effectively provide resistance to hot hydrogen peroxide. Therefore, the use of both rosin and AKD sizing can make full use of the characteristics of both sizing agents to give the coated base paper a stronger resistance to edge penetration.

3. Other quality requirements

In addition to the above-mentioned quality requirements, the coated paper should also meet the following quality requirements.

(1) High wet strength.

(2) Good (coated original) processing performance.

(3) Ability to resist edge penetration (due to the exposed paper edges on the body and bottom of the coating).

(4) Ability to resist condensation (condensation occurs on the outside of the coated paper when cold liquid is contained in the coated paper with a single-sided coating or single-sided wax coating).

Has the ability to resist the penetration of the paper surface (in the case of coating film leakage, it can resist the penetration of liquid).