The quality of release paper is the key to the quality of die-cutting. The thickness, flatness, fiber structure and strength of release paper directly affect the quality of die-cutting. At present, the commonly used release paper is divided into two categories: opaque release paper and translucent release paper. Opaque release paper-based pressure-sensitive adhesive material is generally more than 90g / ㎡, with a certain stiffness, suitable for single sheet printing, also suitable for web printing, and the labels of finished products are mostly used for manual labeling. The weight of transparent release paper type pressure-sensitive adhesive material is generally 60-70g / ㎡, and the release paper fiber has certain density or tightness, which is mainly used for web printing, not suitable for single sheet printing, and the finished product label is used for automatic labeling.

The pressure-sensitive adhesive material requires good flatness, uniform thickness, uniform overall light transmittance, the higher the density, the better, so as to facilitate the complete die-cutting of the substrate.

1. Opaque release paper

The commonly used opaque release paper can be divided into yellow and white by color, and pre coated PE coating and non PE Coating by structure. There are two purposes for coating PE coating: one is to seal the pores on the paper surface to make it smooth and flat, and coating silicone oil on it to reduce the coating amount and reduce the cost; the other is to improve the die cutting characteristics, because PE coating is equivalent to a cushion cushion, with certain toughness and elasticity, which can reduce the fracture of release paper. The results show that the fracture resistance of release paper with PE coating is much lower than that of release paper without PE coating.

As the thick release paper label is mainly used for manual labeling, the unqualified die-cutting quality has a certain influence on the manual labeling. If the die-cutting is continuous, the label will be removed together with the manual waste discharge; if the release paper is cut through or cut through half, the operator is also very difficult to uncover the label.

When the opaque release paper is cut on the flat die-cutting machine, the common fault is the break of the release paper. Therefore, on the basis of ensuring the accuracy of the die-cutting cutter and the flatness of the liner, the release paper with good flatness, large fiber tension and uniform thickness should be selected as far as possible to improve the quality of the die-cutting.

2. Translucent release paper

Translucent release paper is also called thin release paper. At present, grazin release paper (glass release paper) is commonly used in die-cutting of pressure-sensitive adhesive materials.

There are two indexes that influence the quality of die cutting: one is the uniformity of thickness, the other is the fiber structure. Among them, the thickness uniformity of the release paper is extremely important, especially in the round die cutting, because the size of the die cutting cutter roll is determined by the thickness of the release paper. If the thickness of the release paper is not uniform, the blade will cut through or cannot cut the release paper, which brings trouble to the waste discharge process.

The fiber structure of grazin release paper mainly affects the cutting speed of circular die-cutting, because the fiber strength directly affects the breaking speed of waste discharge. The faster the speed, the greater the tensile force, the easier the waste discharge. If the strength of the material itself is large, the cutting speed can be improved. However, for the slow flat die cutting, the fiber structure has little effect on the quality of die cutting. In addition, the toughness and fracture resistance of fibers have a great influence on the quality of die-cutting. For the release paper with good fiber toughness, there may be no problem in die-cutting on the equipment with low precision. However, if the fiber of the release paper is brittle and poor toughness, die-cutting can only be carried out on the equipment with high precision and good die-cutting quality, which shows that the equipment precision is also one of the factors affecting the quality of die-cutting 。

There are two kinds of pressure-sensitive adhesive materials with the same base material and different release paper, which are processed on two label equipment at the same time, the result is die-cutting on the equipment with high precision, and the die-cutting quality of both materials is normal; while die-cutting on the equipment with low precision, the materials with poor fiber toughness of release paper often have problems and cannot be produced normally. This case shows that the die cutting quality is related to the pressure-sensitive adhesive material itself and also to the accuracy of the equipment.