For corrugated boxes to have good protection, they must have certain firmness and durability. Corrugated boxes are made of corrugated cardboard. Corrugated cardboard is made of box cardboard and corrugated core paper. It is made by rolling corrugated base paper. Therefore, the performance of corrugated box is affected by the quality and performance of corrugated base paper and box board.

This article will briefly introduce the performance indexes of corrugated base paper and boxboard and some basic principles of storage and selection.

Performance index of corrugated base paper

The quality of corrugated base paper directly affects the elasticity, flat compressive strength and vertical compressive strength of corrugated cardboard. However, with the continuous improvement of the technical level of the corrugated box industry, many companies have put forward higher requirements for corrugated base paper.

1 quantitative

Quantitative refers to the weight of paper or cardboard per square meter, the unit is g / m2. At present, carton companies mostly use corrugated base paper with a basis weight of 150g / m2 and 125g / m2. However, with the continuous improvement of people's requirements for carton functions, corrugated carton has developed from a simple transport packaging to a combination of transport packaging and decorative packaging. Lightweight carton is imperative. At the same time, with the gradual improvement of environmental protection requirements, the application of low-quantitative, high-strength corrugated cardboard is more and more widely. Some companies with strong technical strength have begun to use corrugated base paper with a basis weight of 90g / m2 and 95g / m2. Obviously, the amount of corrugated base paper shown in Table 1 is not enough to meet the current development needs of the carton industry.

2 tightness

Tightness, also known as apparent density, refers to the weight of paper or cardboard per cubic centimeter. Tightness indicates the structure, air permeability, absorbability, etc. of paper or paperboard to a certain extent. Generally, the tightness of corrugated base paper should be 0.45 ~ 0.50g / cm3. The tightness of corrugated base paper such as A in Table 1 is 0.50g / cm3, and in some current enterprise standards, some of this index is 0.55g / cm3 and some is 0.53g / cm3.

3 Transverse ring compression strength

Ring compression strength refers to inserting a sample of a certain size (width 12.7mm, length 152mm) into the sample holder to form a circular ring, which is compressed between the two measuring plates. The sample can be compressed before crushing. The maximum force to bear, the unit is Newton (N). Affected by the production process of corrugated cardboard, the transverse compressive strength of the corrugated cardboard determines the compressive strength of the carton after forming.

4 Longitudinal split length

Split length refers to the length of a paper strip with a uniform width required to pull the paper by its own weight in kilometer (km). When the paper strip breaks, if the width direction is the horizontal direction of the paper, the measured result is the longitudinal length of the paper. The longitudinal cracking length of corrugated base paper such as A in Table 1 is 4.30km, and some enterprise standards set it as 4.50km.

5 Delivery moisture

Delivery moisture refers to the moisture content in corrugated base paper or paperboard at the time of delivery, expressed as a percentage (%). The moisture of delivery has a great influence on the strength of the carton box. If the water content is too high, the stiffness of the cardboard becomes poor, and the quality of corrugation and bonding is also poor; if the water content is too low, the paper will be too brittle, it will easily break during corrugation, and the folding resistance is also poor.

Selection principle of corrugated base paper and cardboard

When selecting corrugated base paper and box board, their selection should meet the following two principles.

1 Quality selection principle

Generally, corrugated cardboard and cardboard with similar quality grades should be selected as far as possible. For high-grade carton board, A-level corrugated base paper should be used as much as possible; for lower-grade carton board, C and D-level corrugated base paper can be used. If high-grade boxboard paper and low-grade corrugated base paper are used, the resulting corrugated board has low flat compressive strength and is very easy to collapse, and the excellent performance of the boxboard cannot be reflected.

2 quantitative matching principle

If the basis weight of the corrugated base paper is too high, and the basis weight of the carton board cannot be matched with it, it will make the surface of the corrugated board uneven and produce obvious corrugated stripes, affecting the appearance quality and printing effect; High, the two will deform the corrugated tooth shape after they are attached, affecting the thickness, edge pressure strength and cushioning performance of corrugated cardboard. The quantitative ratio of boxboard to corrugated base paper is generally maintained at 2: 1.

Procurement recommendations for corrugated base paper and cardboard

The variety of corrugated base paper and carton board has increased the complexity of carton companies in purchasing.

First of all, carton companies should classify customers and arrange them according to their needs. At the same time, they should carry out a series of analysis and statistics based on the positioning of the customer base and the performance of production equipment. The base paper suitable for production and operation is used as the basic paper for enterprises. These basic requirements for paper should meet the various physical performance indicators proposed by most customers, and it is the reasonable solution with the lowest cost, the smallest variety specifications, and the easiest procurement. For this type of basic regulation paper, the purchase volume can be reasonably increased when purchasing.

Secondly, determine other business papers, mainly used to meet the special needs of some customers. For this order, some carton companies may temporarily buy paper, or negotiate with customers to use corrugated base paper and carton board of similar specifications. When the production volume is not large, carton companies can discuss with customers to minimize the specifications of corrugated base paper and box board as much as possible, such as facial paper and liner paper, corrugated paper and sandwich paper, etc., which can greatly reduce the The number of paper changes and downtimes during line operation reduces the number of corrugated base paper and box cardboard remnants, reducing paper consumption, management costs and storage costs.

Storage of corrugated base paper and cardboard

The storage environment and methods of corrugated base paper and boxboard will also affect the strength and performance of the corrugated board, which in turn will affect the quality of the finished product of the corrugated box. When storing corrugated base paper and cardboard, the following issues should be noted.

1 Storage environment

Corrugated base paper and cardboard should not be stored in the open air as much as possible. If it is unavoidable, the storage time in the open air should not be too long. At the same time, it needs to be covered with canvas to avoid rain. Corrugated base paper and cardboard are very sensitive to air humidity, easily absorb or lose moisture, causing lotus leaf edges or tight edges, which will cause problems such as inaccurate overprinting and wrinkles in printing. Therefore, choose a clean and dry environment during storage. The relative humidity is best maintained at 50% to 65%, and the temperature is preferably 15 ° C to 25 ° C. In addition, corrugated base paper and carton board can not be stacked close to the wall.

2 Static problems

Factors such as high temperature and high pressure environment in the process of making corrugated base paper and boxboard and friction during storage and transportation will generate static electricity on the surface. Sometimes the paper with static electricity will be difficult to separate, resulting in multiple sheets of paper feeding, or printing displacement, inaccurate overprinting, uneven paper collection, or difficult paper rewinding in web printing. In addition, static paper is also easy to absorb dust and paper dust in the air, directly contaminating the printed matter. It is particularly worth noting that when static electricity accumulates to a certain degree, sparks will also be generated, burying hidden fire hazards.

3 Avoid light

The base paper contains lignin and many other chemical components. It will fade and yellow after being exposed to light, making it unusable and scrapped. At the same time, the moisture in the base paper will evaporate after exposure, and its water content will change, causing the base paper to become brittle or deformed, affecting the smooth production.

4 Stacking height

The stacking height of the base paper should not be too high to prevent crushing the lower paper. If it is roll paper, the paper core tube should also be protected from damage. Generally, the stacking height should not exceed three layers.

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