Knowledge and technology of packaging cardboard boxes
1、 Material and production process of cardboard boxes:
1. Paper boxes can be divided into two categories based on their types: color printed boxes and cowhide boxes.
2. In terms of shape, it is mainly divided into ordinary boxes (such as cash register boxes), box sets (such as printing boxes with similar sizes above and below), and buckle boxes (such as copy boxes with smaller sizes above and below if not ordered)
3. In terms of material: Our company mainly uses three-layer and five layer boxes. They are laminated and die cut with face paper, corrugated paper, and liner paper.
3.1 Face paper: The commonly used face paper for printing cardboard boxes is 250g gray bottom whiteboard paper, which has good ink absorption performance and flexibility.
3.2 Corrugated paper: Corrugated paper is generally divided into 90g-150g, and we commonly use double-sided corrugated three-layer cardboard and double core double-sided five layer cardboard. According to the height of the ridges, the shapes can be classified as A (CE type). Common numerical representations include 3 (90G corrugated), 4 (110G high-strength corrugated), 5 (130G high-strength corrugated), and 6 (150G high-strength corrugated). High strength corrugated, also known as adhesive corrugated, is both waterproof and sturdy.
3.3. The inner paper is generally cowhide hanging paper, which has good resistance to breakage and tearing. It is divided into three grades: A (170G wood pulp hanging paper), B (140G wood pulp hanging paper), and C (140G mixed pulp hanging paper),; There is also a distinction between double-sided kraft paper and single-sided kraft paper.
3.4. The material of our five layer color box is 250g W9494B, which is a white board paper with a surface paper of 250g; 110G adhesive double E-rib and 140G kraft paper with inner paper, as well as 100G core paper (9 represents E-rib)
3.5. The currently used three-layer bottom box is 140GW6B: the surface paper is 140g white kraft paper, 140g high-strength corrugated (B-corrugated) paper, and the inner paper is 140gB grade kraft paper.
3.6 Three layer cash register box (75 * 60 cash register paper) A4B is made of 170G wood pulp hanging paper, 110G high-strength corrugated paper, and 140G mixed pulp hanging paper
3.7 Five layer cashier box A434B, which includes 170G wood pulp hanging paper, 110G high-strength corrugated paper, 90G Poirot paper, and 140G wood pulp hanging paper.
4. In terms of production technology:
4.1 Color Box: Printing is done with ink, and the printing requirements are relatively high. Generally, imported printing machines are used for four-color or five color printing. If the color sequence is not sufficient, overprinting should be performed, and the printing should be clear, accurate, and the color difference should not be too significant. There are two methods: one is to apply a light coating, and the other is to polish with V oil to achieve a bright effect (polishing). Our company's main process for color boxes is V-oil polishing. Purple Sky Seal is embossed after applying V oil.
4.2. Tian Di Gai Finished Product: It is a process of laminating facial paper and corrugated cardboard into a single unit using a laminating machine, and then applying pressure through a press to fully bond the cardboard and corrugated cardboard. The cardboard and corrugated cardboard are then die cut into shape using a die-cutting machine, and waste is discharged to produce the finished product.
4.3. Cowhide cardboard box: Cowhide cardboard boxes are directly produced through cardboard production lines. Cowhide cardboard boxes are printed with ink, and because cowhide paper has better ink absorption and dries faster, they are pressed, slotted, and die cut. Our company's commonly used cash register with ribbon requires four processes to form: printing, thread pressing, manual slotting, and die-cutting.
The two main indicators of cardboard boxes are compressive strength and burst resistance.
6. The pricing method is: square meter of paper * unit price of material square * processing factor.
6.1 Cashier box: (length+width+5) * (width+height+3) * 2 * square unit price * 1000 * 25
6.2 Printing box cover: (2 heights+length+4) * (2 heights+width+4) * Unit price per square meter * 1000 * 25
6.3. Bottom box: (length+height * 2+5) * (width+height * 2+3) * unit price per square meter * 1000 * 25]
7. Calculate weight: Paper square * (face paper weight+inner paper weight)+Paper square * Corrugated paper weight * Relative corrugated coefficient
The above is a preliminary understanding of cardboard boxes. Next, let's talk about plastic packaging:
1. Plastic packaging materials can be divided into various materials such as PE, PP, POF, PVC, etc
2. The above material composition: PE polyethylene (LDPE: low-density polyethylene, HDPE: high-density polyethylene),
PP: Polypropylene,
PVC: Polyvinyl chloride
3. Production process:
4.3. Environmentally friendly PE plastic packaging bags. PE packaging bags can be divided into low-pressure materials and high-pressure materials. Low pressure materials have good flexibility and will not make noise when shaken, while high-pressure materials have good hardness and will make noise when shaken. PE low-pressure new materials are available, and dyes can be added according to customer needs to make various colors. We use low-pressure PE materials.
3.1 Production and processing technology: Currently, the blow molding machine is used. When producing PE packaging bags, the machine needs to be preheated first. When the temperature reaches the required level, raw materials are added, and the granular shape, white transparent and odorless raw materials are melted and extruded at high temperature through the machine die to form a cylindrical shape. After rewinding, they are printed and rewound on the printing machine according to the requirements. The subsequent process is bag making. Some bag making machines cut the hot mouth according to the specifications and package the finished product. Handbags are similar in that they need to be die cut after cutting and ironing the mouth, and then molded.
3.2. Film is a heat shrinkable film with high transparency, high shrinkage rate, and good heat sealing performance made by using linear low-density polyethylene (LLDPE) as the intermediate layer and polypropylene (PP) as the inner and outer layers in specialized equipment, and extruding the inner, middle, and outer layers together through a special process.
4.4 Printing requirements: The printing requirements are not too high, there should be no significant color difference, there should be no ink stripping, the printing speed should be controlled, and there should be no wrong version.
4.5 Precautions: When blowing film, it is necessary to control the uniformity of thickness. If the thickness is uneven or the difference is too large, it will affect the printing and usage effects.