五月的婷婷综合视频,五月的婷婷综合视频,美女日逼视频免费观看,狠狠干狠狠日狠狠爱,不卡视频一二三区免费视频,亚洲中文自拍另类在线,99久久99久久免费精品十八禁,97caopen视频,日本免费一曲二曲三曲

Chemical name: Hydroquinone-bis (β-hydroxyethyl) ether, hydroquinone dihydroxyethyl ether (aromatic glycol chain extender HQEE)-solid

Molecular formula: C10H14O4

Molecular weight: 198.20

CAS NO.:104-38-1

Hydroquinone dihydroxyethyl ether (aromatic diol chain extender HQEE)-solid is a symmetrical aromatic diol chain extender. It has good compatibility with MDI, can significantly improve and improve the tensile strength, hardness and resilience of products. HQEE / MDI is a PU elastomer series in parallel with MOCA / TDI.PUs using this product are generally used in areas with high requirements for product physical properties.
   
HQEE is a new non-toxic chain extender that replaces MOCA. Widely used in MDI PUR system (CPU, TPU, MPU). It can significantly improve the temperature resistance level and mechanical properties (tearing strength, shearing property, hardness, resilience, etc.) of PUR products, improve the storage stability of MPU compound and prevent scorching. The performance of PUR is improved and adjusted well. MDI / HQEE is often used in areas that have high requirements on the physical properties of products. Such as: PU products such as oil well seals, forklift tires, hydraulic cylinder seals, conveyor belts, etc., are very helpful to improve the performance of high resilience microcellular foam products.

Chain extender is one of the three main components of cast polyurethane elastomer. Hydroquinone bis (β-hydroxyethyl) ether (HQEE) is a chain extender mainly used for diphenylmethane diisocyanate (MDI). The elastomers produced by this chain extender system are mainly used for heavy-duty applications, such as forklift tires, oil well and hydraulic equipment seals, coarse material tank linings, and skateboard wheels. However, if you do not understand the performance of HQEE, you cannot get the best product.
In general, equipment that uses MOCA as a chain extender to produce elastomers can also be used to produce HQEE systems. But the process of the two is obviously different. HQEE and MOCA melt at nearly the same temperature (100 ° C), but MOCA will appear too cold to crystallize. HQEE does not appear to be too cold, but the processing equipment must maintain 110-116 ℃ (up to 122 ℃). The HQEE melting tank must be heated evenly above 110 ° C, stirring slowly to prevent foaming on the surface and the tank wall. The pipelines of the process equipment used in HQEE should be properly insulated and heated to prevent the occurrence of "cold spots" that could cause pipeline blockages and errors in the mixing ratio of HQEE prepolymers.
The mixing ratio of MOCA / prepolymer can be changed within the range of 90-100% of the theoretical value, and the ideal product can still be obtained. However, for the HQEE system, the ratio of diol chain extender / prepolymer must be precisely controlled to obtain the best product performance. The prepolymer should also be kept at 110 ° C, and after the HQEE is mixed with the prepolymer, the temperature must be maintained to prevent HQEE from crystallizing. The entire molding temperature must be maintained between 110-120 ℃. For thin parts, higher temperatures are required. Below the above temperature will cause defects in HQEE crystal. The oven or mold heating equipment must exceed the required molding temperature.

The fluidization time of uncatalyzed HQEE / MDI elastomers takes about 2 hours for thin parts (such as gaskets); for thick parts (such as forklift tires), it can significantly reduce the demolding time.
In order to reduce the melting temperature of the chain extender to reduce the processing temperature, HQEE can be mixed with other diols, triols and industrial chain extenders. The commonly used ratio is HQEE 80-90%, diol or triol 10-20%.

Some defects of the product can be avoided by improving the operation. The surface frost is caused by the chain extender / prepolymer mixing or the molding temperature is too low, or the mold temperature is too low. The surface scoring of the molded product is caused by improper mixing or premature mold closing. The warpage of the surface of the molded product indicates that the mold may be closed too late.

Application range

PU products such as oil well seals, forklift tires, hydraulic cylinder seals, conveyor belts, etc. can also be used in spandex.

Package

Carton, 20kg (inside 2kg small package)

Store

Hydroquinone dihydroxyethyl ether (aromatic glycol chain extender HQEE)-The solid is hygroscopic, so it should be placed in a closed container in a ventilated and dry place to prevent moisture absorption. Put desiccant in the drum. If it is not used up once, the remaining part should be resealed. HQEE is sensitive to light (UV), and it will turn yellow or brown under the influence of ultraviolet light.