①The choice of coating amount
Because the fiber structure of paper causes the surface of the paper to have larger gaps and absorbs more glue, it is necessary to increase the amount of dry base coating when making paper-plastic composite and paper pulp molded products. However, the coating amount is not as large as possible. The thickness of the glue layer stored between the paper surface and the aluminum foil interface after lamination is the effective coating amount, and the glue liquid absorbed into the paper does not contribute to the composite fastness.
If the coating amount is too large, the adhesive is not easy to solidify, and the surface is prone to "orange peel" phenomenon, and it may also cause the waste product to have a higher hardness; if the coating amount is too small, the adhesion between the paper and the film will decrease.
In addition, the smoothness of the paper is high, the fiber is tight, and the coating amount should be reduced; on the contrary, the smoothness of the paper is low and the fiber is loose, and the coating amount should be further increased.
Therefore, it is recommended that the amount of glue applied by customers should be above 3.5g/m2, and the amount of fine glue should be affirmed according to materials, equipment, technology, product usage, etc.
②The choice of glued surface
Due to the fiber structure of the paper, the paper has larger voids and will absorb more glue. In severe cases, the surface will lack glue and delaminate. When the paper is glued, it is usually necessary to increase the amount of glue to compensate for the amount of glue absorbed by the paper. When the plastic film is coated with glue, it can reduce the amount of paper absorbed by the glue, and the amount of coating can be reduced accordingly.
It is assumed that paper pulp molding or aluminum-plastic composite products are produced using a dry compounding process, and the adhesive is dissolved in a solvent. If paper is used for gluing, the solvent has a strong permeability to the paper and will also bring a large amount of adhesive into the paper. In this case, a large amount of glue will be required at this time. It is generally difficult for our equipment to meet the requirements. Once the amount of glue is not well controlled, it is easy to cause problems such as poor composite strength and glue penetration. Therefore, we generally do not recommend that customers use paper Glue on the surface. For example, when we consume BOPP/paper/PE, we first use BOPP sizing composite paper, and then PE sizing composite paper/BOPP.
③Setting of tension
We mainly adjust the tension according to the membrane material. Due to the high tensile strength of paper, it is not prone to deformation, so a relatively large second unwinding tension or rewinding tension is required during the consumption process. The tension control of the film only needs to meet the small tension in the film lamination process. If the tension setting of the two is unreasonable, the deformation of the two membrane materials may be different, and problems such as wrinkles and curling may occur.
④Setting of drying tunnel temperature
When the plastic film is glued, the temperature of the drying tunnel of the laminating machine is too high, which is easy to cause the plastic film to stretch and deform. At the same time, the glue is too monotonous and the leveling is poor; the temperature is too low, the glue cannot be dried out, and it is easy to form a bond Phenomena such as force drop and foggy appearance.
⑤Setting of pressure roller temperature and pressure
The temperature of the pressure roller is low, and the adhesive cannot fully penetrate and level the paper, resulting in low bonding strength and low gloss; too high temperature will easily deform and shrink the plastic film, which may cause waste products to crease.
Appropriate pressure will make the adhesive in viscous flow state penetrate into the paper fiber through the pressure of the press roller, and complete the physical, mechanical, chemical bond and other multiple bonding of the paper. At the same time, under the pressure, the adhesive will be fully spread and leveled, and the color of the printed matter will be combined. Bright.
