If the base paper used by carton manufacturers in China is divided according to the origin, it can be simply divided into imported base paper and domestic base paper; According to the variety of base paper, it can be divided into kraft cardboard (also known as Kraft linerboard in China), corrugated base paper, whiteboard for higher-grade packaging and printing, hanging kraft paper, coated kraft paperboard, etc. Due to the rapid development of China's carton industry, the demand for base paper in Baiyun District is increasing year by year. Guangzhou carton packaging factory, especially coated kraft board, has not only the advantages of kraft board and coated white board, but also the strength of kraft board and the printability of white board, so the import volume has increased significantly. In recent years, although the overall quality of domestic base paper has been greatly improved, there is still a gap compared with that of foreign base paper. Moreover, even if individual paper mills can reach the same level abroad, they can not meet the demand in the production of some kraft paper and corrugated paper with low gram weight and high strength due to limited production capacity. Most still rely on imports. For imported base paper, China's inspection and quarantine department has specific provisions: according to the provisions of the commodity inspection law, the commodities listed in the category list must be inspected by the inspection and quarantine institution or its designated inspection department, and shall not be sold and used without inspection. Most of the base paper for cartons imported from China are legally inspected goods, so they must be inspected. At present, the inspection standards followed by the inspection and quarantine department when inspecting these papers are roughly as follows:
1. Mandatory standards of laws and regulations or other inspection standards that must be implemented;
2. If there are no mandatory standards or other inspection standards that must be implemented in laws and regulations, the inspection can be carried out according to the standards agreed in the contract between the two parties. (if the mandatory standards of laws and regulations are lower than the standards agreed in the contract, the standards agreed in the contract shall be followed);
3. If the above two points are not available, they can be inspected according to the standards of the producing country, relevant international standards or the standards designated by the national inspection and quarantine authority. If there is no suitable testing standard, the approved internal method standard shall be selected.
Here, we need to make a special explanation for the above point 2. In our actual inspection process, we found that most domestic users do not have enough agreement or even agreement on the quality terms of imported base paper in the trade contract. They often only recognize the brand and origin and ignore the quality fluctuation of the product itself. In the first half of this year, our inspection and quarantine department inspected and found that there were several batches of imported paper with quality problems. However, due to the customer's failure to agree on the quality requirements and inspection standards of the goods in advance in the contract, it was difficult for the inspection and quarantine department to issue the unqualified certificate and brought trouble to the customer's claim and return, We call on enterprises importing base paper to agree on quality terms in the contract to protect their own income.
The specific inspection contents of paper include: safety, health, environmental protection, quality, quantity, weight, packaging and other items. Due to space constraints, we will only introduce the conventional physical testing items and the methods and standards used.
1. Appearance inspection:
The appearance inspection of paper is one of the important inspection items, which is generally composed of on-site sampling inspection and laboratory inspection. The appearance defect of paper not only affects the appearance of paper, but also affects the use of paper. The inspection methods and standards we adopt are: ISO, TAPPI standards, Sn / T 0874-2000 and national standard GB / T 1541 dust detection, etc. It mainly adopts light exposure test, head up test, squint test and hand touch test. The paper surface shall be flat and clean, and no folding is allowed.
2. Physical property inspection
Before carrying out the physical property inspection, the paper must be pretreated with constant temperature and humidity according to the standard. Because the test items required for different paper are different, here are mainly listed:
Good whiteboard paper generally requires close texture, smooth surface, consistent thickness, no fuzzing on the paper surface, good absorption, small expansion rate, and can meet the requirements of multi-color overprint. In order to meet the requirements of box making, whiteboard paper should also have the characteristics of large stiffness and good folding resistance. The main importing countries are: South Korea, Indonesia, the United States, Japan and so on, especially the quality of whiteboard produced in Japan. Test items include: quantitative, thickness, whiteness, smoothness, crack length, breaking resistance, folding resistance, sizing, stiffness and IGT.
(2) Kraft cardboard:
Kraft cardboard, known as carton board paper in China, is one of the main types of carton paper. Domestic box board paper is divided into three grades: excellent products, first-class products and qualified products. Kraft paper must be tough, with high burst resistance, ring crush strength and tear strength. In addition, it must have high water resistance. Due to different processes and materials, generally speaking, the quality of most imported kraft paper is better than that of domestic kraft paper, especially the quality of American Kraft paper. The test items include: quantification, thickness, tightness, burst resistance, burst index, ring pressure strength, transverse ring pressure index, fracture length, tear degree, sizing degree, moisture, banner quantitative difference, transverse folding resistance, etc.
(3) The test items of coated kraft cardboard and coated kraft paper are kraft cardboard and whiteboard.
(4) Corrugated base paper:
Corrugated base paper is one of the important constituent materials in the production of corrugated board. Corrugated base paper requires good fiber bonding strength, flat paper surface, good tightness and stiffness, and certain elasticity, so as to ensure that the made carton has shockproof and pressure resistance. In addition, the moisture index should be controlled. If the moisture is too small, the paper will be brittle and rupture will occur during Corrugated processing; Excessive moisture and soft paper will bring difficulties to processing and molding. Generally, the water content of paper should be controlled at about 10%. Domestic corrugated base paper is divided into four grades: A, B, C and D.
The test items include quantification, thickness, tightness, burst resistance, ring pressure strength, transverse ring pressure index, flat pressure strength, fracture length, sizing degree, moisture, etc. The methods and standards used for detection mainly include GB, Sn, ISO, TAPPI, scan, JIS, etc. Here is a simple example of China's inspection standards:
1. GB / T 451.2-2002 paper and board - Determination of quantitation
2. GB / T 451.3-2002 paper and board - Determination of thickness
3. GB / T 453-2002 paper and board Determination of tensile strength (constant speed loading method)
4. GB / T 454-2002 determination of bursting resistance of paper
5. GB / T 455-2002 paper and board Determination of tear
6. GB / T 456-2002 paper and board - Determination of smoothness (Buick method)
7. GB / T 457-2002 determination of folding resistance of paper (Schopper method)
8. GB / T 458-2002 paper and board - Determination of air permeability (Schopper method)
9. GB / T 459-2002 paper and board - Determination of flexibility
Determination of moisture in paper and board GB / T 462-2003
11. GB / T 13024-2003 carton board
12. GB / T 13023-1991 corrugated base paper
13. Sn / t0874-2000 inspection procedures for import and export paper and paperboard
The above mentioned are some conventional detection methods of carton paper. With the rapid development of science and technology and people's increasing attention to environmental protection, carton paper is developing in the direction of functional and environmental protection. For example, functional paper such as anti-corrosion, anti bacteria, anti oil and high temperature resistance. At present, China's national standards for this kind of special paper are not complete, and some are in the process of revision and formulation. For the detection of this kind of paper, the inspection and quarantine department generally refers to the relevant international standards, the standards of the exporting country or the standards of the manufacturer. In addition, some base paper used for food packaging cartons must also comply with China's relevant health standards, which is now the focus of our inspection and quarantine work, because it is directly related to the health and safety of our people. The inspection standards involved in these papers mainly include:
1. GB 11680-89 hygienic standard for base paper for food packaging
2. GB 18192-2000 paper based composites for aseptic packaging of liquid food
3. GB 18706-2002 paper based composite materials for fresh-keeping packaging of liquid food (roof package). For some printed paper used for food packaging, it is also necessary to detect the content of relevant heavy metal elements, such as lead, chromium, cadmium, mercury, etc.
In addition, EU countries now strictly control the total content of heavy metals in imported packaging cartons. The scope of testing covers a wide range, including carton itself, carton nails, adhesives, contents and so on. Relevant testing standards include:
1. DD ENV 12498:1998 paper and board intended to come into contact with food stuffs. Determination of cadmium, lead and chromium in an aqueous extract;
2. DD ENV 12497:1998 paper and board intended to come into contact with food stuffs. Determination of mercury in an aqueous extract; With the strengthening of people's awareness of environmental protection, countries all over the world have their own restrictive laws and regulations on imported packaging. Our carton manufacturers should pay special attention to international trade to prevent unnecessary losses.