PP-R is a (PP and PE) gas-phase synthesis of random copolymer polypropylene, its structure is characterized by the rules of PE elements will have no links among the PP molecule, molecular weight from 30 million to 800 thousand range. The use of raw materials to produce PP-R pipe PP-R pipe, also known, is the late 80s early 90s development and application of new plastic pipe products. It is excellent in its own performance and wider applications, has a place in the plastic pipe market and is recognized as a green environmental protection product. However, through the operation of the market in recent years found a PP-R pipe market a lot of problems to a large extent constrained the PP-R pipe benign development.
Through market research and analysis, the current PP-R pipe problems are as follows:
1, PP-R pipe there is the most prominent problem is improper use of raw materials, mainly in the following cases:
1, individual producers to PP-B, PP-H materials as PP-R materials, and some even act as the direct use of general PP material PP-R materials.
2, various modified PP material flooding the market, such as: PP / PE blends, as PP-R materials promote the use of or in the PP-R materials to add PP-B, PP-H or ordinary PP to reduce costs.
3, PP-R raw materials to add too much or do not meet the requirements of the recycling material.
4, adding masterbatch process, because of masterbatch products resulting from improper use of physical and mechanical properties to reduce or health performance does not meet national standard requirements phenomenon.
5, due to frequent turnover of individual producers to reduce costs of raw materials or for consideration, pipe and pipe fittings used for raw material inconsistencies. Pipe, pipe fittings which are inconsistent with a direct impact on raw material pipe, pipe fittings welding quality. Of different materials, in particular, PP-R and PP-B between the welding, due to the melting point of different materials (PP-R is 140 ℃ or so, PP-B is generally about 160 ℃), welding conditions are different, so that welding quality easy to grasp; two kinds of crystalline materials, in varying degrees, cooling rate is also different in the welding process due to the different shrinkage rates which led to stress concentration; pipes and pipe fittings hot-melt welding process is the spread between the molecular chain processes, the proliferation of more fully, the more uniform, the link performance is relatively good. PP-R and PP-B materials in the different content of PE, resulted in PP-R and PP-B compatibility is poor, and thus directly affect the connection reliability; In addition, the two kinds of materials, the melt flow rate, if the gap is too large, is generally believed that the gap is greater than 0.5 or so, also affects the quality of welding.
6, in the production and sales, artificially pipe into cold water pipes and hot water pipes. Cold water tubes PP-B raw materials, hot water tubes PP-R raw materials. This practice has virtually turned into a misunderstanding of consumers, it is not correct! In terms of a certain material, the pressure certain circumstances, should be based on the use of engineering design of environmental requirements, to determine the level of the corresponding pipe S (to determine pipe wall thickness).
7, PP-B although the pressure in the high-temperature performance than PPR, but their use at room temperature or cold places than the PP-R performance, particularly in low-temperature impact resistance superior performance comparison. Meet the national standard of PP-B pipe can be used under certain conditions, hot and cold water delivery systems. As the PP-B pipe has good low temperature impact properties, to make it more suitable for low-temperature conditions, the installation and construction, as well as the delivery of cold water. Therefore, the market should make a clear orientation, so that consumers understand the PP-B, to the PP-B pipe a reasonable space, and thus can also avoid using a certain extent, PP-B fake PP-R to happen.
8, for the above-mentioned serious problems, we approach the identification of raw materials has given greater attention. At present, through various channels and markets to explore and some professionals argue, have been a number of analytical test methods can be used to identify genuine and fake materials. For example: you can melt mass flow rate (MFR) will be screened out of PP modified materials, the standard provides for hot and cold water pipes PP (including PP-H, PP-B, PP-R) of the MFR not greater than 0.5 g/10min, so MFR greater than 0.5g/10min positive is not acceptable. Second, it can by IR, melting point, nuclear magnetic resonance and other means for further identification.
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