Editor's Note: The General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) recently issued the "Notice on Launching the "Quality Improvement Service into the Enterprise" Campaign, and organized the national quality inspection system to highlight key areas, key industries and key products, and provide quality improvement services for Wanjia enterprises. Interpret quality and safety knowledge. In order to cooperate with this event, this edition will open the “Hundreds of Experts Interpretation of 100 Kinds of Product Quality†column today. Experts are invited to introduce the quality inspection laws and regulations, technical standards and related policies, interpret quality knowledge, and let you consume. More counted.
Today's attention: Blockboard
Appearance experts:
Lu Bin (Director of National Quality Supervision and Inspection Center for Wood-based Panels and Wood Bamboo Products)
Product introduction
Blockboard, commonly known as large core board, is a kind of board which is coated with rubber and hot pressed by natural rotary cutting veneer and solid wood board. It is one of the main varieties of wood-based panels for decoration and decoration. It has beautiful appearance and high strength. Light weight, small deformation and other characteristics, mainly used in furniture manufacturing, doors and windows, ceilings, floors and wall skirts decoration and so on.
Blockboards generally consist of a watchboard, a coreboard and a core. The surface plate refers to the surface layer of the blockboard, the core plate refers to the veneer layer between the surface plate and the core, and the core is a jig or wooden structural plate composed of wood strips, which is the middle of the blockboard. Floor.
According to the use environment of blockboard, blockboard is divided into indoor blockboard and outdoor blockboard, which are divided into ordinary blockboard and building blockboard according to the purpose, divided into three layers of joinery according to the number of layers. Board, five-layer blockboard and multi-layer blockboard, according to the level of formaldehyde emission, blockboard is divided into E0 class blockboard, E1 blockboard and E2 blockboard.
Key indicators
1. Formaldehyde. According to national standards, the formaldehyde emission limit of blockboard is E0 grade new standard ≤0.5mg/L, E1 grade ≤1.5mg/L, E2 grade ≤5.0mg/L. At present, the unqualified quality of the blockboard sold on the market mainly involves two aspects. First, the amount of formaldehyde released exceeds the standard, which poses a serious threat to human health. Second, the formaldehyde emission of some products is in the E2 level. It did not reach the E1 level, but it was marked with the E1 level, which is also unqualified.
2. Lateral static bending strength. The transverse static bending strength and the bonding strength reflect the ability of the blockboard product to bear the force and resist the deformation. There are three main reasons for the unsatisfactory transverse static bending strength. One is that the raw material itself is defective or decayed, and the core quality is not good. Second, in the production process, the splicing technology does not meet the standard; the third is that the bonding work is not done well.
3. Glue strength. Gluing performance mainly has three process parameters, namely time, temperature and pressure. The use of adhesives is more and less, and it also affects the formaldehyde emission index.
4. Water content. The water content is an index reflecting the water content of the blockboard. If the water content is too high or uneven, the product will be warped or uneven during use, which will affect the performance of the product.
Shopping tips
The first is to look at the appearance. The surface should be dry, smooth and flawless. The whole plate should be flat and free from warping. When standing upright, the corners should be straight, and the diagonal error should not exceed 6 mm. When the whole stack (package) is placed, each plate should be completely fitted; the mark should be complete.
The second is to look at the side. The thickness of the core plate can be seen from the side or the end face after cutting, whether the thickness of the core plate is uniform, whether it is straight, whether there is overlap or separation phenomenon, whether the texture of the filled material is dense, whether the wood strips are spliced ​​tightly, and the core strip is observed. Whether there are cracks and obvious gaps at both ends and decaying wood strips. At the same time, it depends on whether there is no glue or greasy putty around.
The third is the size. Measure the size of the blockboard, especially if the thickness of the blockboard is the same as the nominal thickness.
The fourth is to measure the quality of the glue. The test piece of 75mm×75mm can be intercepted and placed in water of 63°C for 3 hours. Then, whether the adhesive layer of each end face of the test piece is opened or not, the glue layer of the general quality of the blockboard usually does not open. .
The fifth is to check the environmental performance. Stack the unused blockboards in a small house, close the doors and windows, and wait 24 hours after storage for observation. If there is no obvious pungent smell, it means that the formaldehyde emission of the blockboard is small, and the use will not affect the human health; if the smell is large or there is a feeling of tearing, it means that the formaldehyde emission of the blockboard may be higher and should be sent to the relevant The department conducts testing.
Six is ​​the price. In general, the price of E1 grade blockboard should be above 100 yuan, and the price of E0 class blockboard should be above 130 yuan. If the price is too low, you should consider whether there is a quality problem.
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