Die-cutting characteristics of adhesive materials
Adhesive material is a composite material, composed of surface, adhesive, silicone oil coating and paper.
The die-cutting of adhesive materials is different from traditional printing materials, such as paper die-cutting, is to cut through the whole material; And the die-cutting of adhesive materials is only the surface and adhesive layer cut through, retain the bottom paper and its surface of silicone oil coating, and finally make the die-cutting formed labels remain on the bottom paper.
Adhesive material of the die cutting quality related to many factors, such as die-cutting way, die cutting device, die-cutting precision, precision die cutting blades with matching situation of materials, in addition, die-cutting quality is associated with the properties of adhesive materials, such as paper, adhesive performance and the bottom paper, all kinds of die cutting properties of the adhesive is different also.
The following will be on the surface of adhesive materials, adhesives and paper on the impact of die - cutting quality to give a brief introduction.
The factors that affect the quality of die - cutting surface types, strength and thickness.
1. Types of dough
Surface material basically can be divided into paper and film two categories.
The cutting principle of ordinary paper is slightly different from that of thin film materials. Although in theory, die cutting must be cut with the surface and adhesive, but in fact, die cutting paper materials are cutting tools and paper stress fracture results, that is, the blade cutting down at the same time will also paper to the two sides of the extrusion, so, relatively speaking, the paper material die cutting precision is not very high. In the analysis of samples, it is often seen that some labels have rough edges, which is due to the coarse fiber dimension of the material, the phenomenon of natural fracture.
Based on the paper material die cutting characteristics, and considering the blade wear, flat die cutting blade Angle is usually specified as 52°, if the Angle is large, the extrusion deformation of the material is large, that is, the horizontal direction of the separation force will make the material fracture separation phenomenon intensified.
Thin film material die - cutting, is simply the process of cutting through. Because most of the thin film materials have toughness, will not naturally break, so cut through two-thirds is not suitable, must be completely cut through or cut through four-fifths of the thickness, or exhaust will be stripped together with the label.
Therefore, die cutting thin film material blade to be sharp, high hardness, to use a small Angle die cutting knife, blade Angle is usually 30° ~ 42°. If you use a large Angle of the die cutting knife, not only die cutting difficult, and if the blade is not sharp and will appear on the surface of the cutting material does not wear, the bottom of the paper broken, or make the end of the label edge flanging phenomenon, caused by cementing. In short, the precision of die - cutting film than paper materials, so die - cutting film material on the accuracy of equipment, die - cutting version of the precision and the bottom paper have certain requirements.
2. Strength of the surface
The strength of the material with the thickness of the material, fiber (polymer) structure and its own humidity. In the die-cutting process of adhesive materials, and the surface of the biggest factor is the exhaust speed. The greater the environmental humidity, the weaker the strength of the material itself after being affected by moisture, so it is easy to pull off, or even unable to exhaust.
When designing the layout, it is necessary to arrange the waste size and waste discharging speed of labels reasonably according to the strength of materials through tests, which can not only improve the production efficiency, but also reduce the waste of materials.
3. Thickness of the surface
Material thickness directly affects the depth of die cutting, the thicker the material, the easier die cutting. Because the thicker the material, the greater the tolerance of die cutting, cutting through the bottom of the paper is less. Relatively speaking, thin material, easy to cut through the bottom of the paper. As in the same flat label die cutting machine respectively die cutting 80g/m2 and 60g/m2, the same surface paper. The results show that: 80g/m2 of material die cutting waste normal, and replace 60g/m2 of material, die cutting often appear waste fracture, bottom paper cutting and wear and mark phenomenon, often need to stop, pad plate, a big waste. There are a variety of reasons for this, if the use of rotary die-cutting method or reduce die section product, using high precision equipment, such as this phenomenon can be reduced or avoided.
So die cutting thin surface material, must be in high precision equipment, as far as possible to reduce the die cutting area (especially small label), using professional die cutting version manufacturers die cutting version, also pay attention to pad precision.
The thickness of the surface material is directly proportional to the strength, which directly affects the waste discharging speed. The waste discharge comparison test can be conducted with 80g/m2 and 60g/m2 materials respectively. The result is that the former is 20% ~ 30% more efficient than the latter.
Adhesive effect on die - cutting
There are four types of adhesive commonly used in adhesive materials: acrylic water-based latex, rubber hot melt adhesive and solvent rubber or acrylic adhesive, among which the most widely used are latex and hot melt adhesive.
Due to the raw material and formula of the adhesive, so the physical and chemical properties are not the same. Water latex is composed of tiny capsules, relatively small cohesion, easy separation between the film, and hot melt adhesive is composed of a large cohesion of rubber, film is difficult to separate. So in die cutting, if it is water latex material, in the adhesive layer is not cut or not cut at all, the label is still waste, because the pull of waste is easy to break the rubber layer. And in die - cutting hot - melt adhesive type adhesive material, if die - cutting is not in place, either label together with waste paper edge strip, is cut through the bottom of the paper. Because hot melt layer only completely cut off (or most of the cut) to normal exhaust, otherwise not cut through the film will be stripped with the label, raising the die cutting difficulty.
For this reason, die - cutting latex adhesive material is relatively easy, hot - melt adhesive material on die - cutting technology requirements. This is the main reason for high consumption and low production efficiency of hot melt adhesive materials.
Bottom paper on the impact of die - cutting
Bottom paper quality is the key to affect the quality of die cutting, bottom paper thickness, flatness, fiber structure and strength are directly affecting the quality of die cutting. At present, commonly used bottom paper is divided into two categories, namely opaque bottom paper and translucent bottom paper. Non-transparent bottom type adhesive material quantitative generally in more than 90g/m2, there is a certain stiffness, suitable for sheet-fed printing, also suitable for web printing, finished product labels for manual labeling. The quantitative quantity of transparent bottom type adhesive material is generally 60 ~ 70g/m2, and the bottom paper fiber has a certain density or tightness, which is mainly used for web printing, not suitable for sheet-fed printing, and the finished product label is used for automatic labeling.