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Epoxy resin molding compounds are manufactured in many ways and can generally be classified into three types of premixing methods, prepreg methods, and extrusion methods. These three types of methods naturally have their own advantages, strengths, and corresponding scope of application. But in the end, what are the advantages and disadvantages? According to experts from the China Epoxy Resin Industry Association, it specifically dispelled doubts.
The first method of manufacturing epoxy resin molding compounds is premixing to make fiber molding compounds. The pre-blending method consists of impregnating short-cut fibers and fillers with an epoxy resin solution, mixing them uniformly, and then tearing and drying them to obtain a fiber molding compound. The characteristics of the molding compound are: loose and non-directional fibers, and good fluidity. , The output can be large or small; but the specific volume is large, the fiber damage during the manufacturing process, the strength will be reduced, and the working conditions are poor. Each process can be manually operated, suitable for small-scale production and trial production; it can also be used for mechanical operation, suitable for mass production, with less fiber damage and high product strength during manual operation.
Experts from the China Epoxy Resin Industry Association said that the following points should be noted in the preparation process: First, fibers treated with reinforcing sizing agents should be used for fiber pretreatment. Otherwise, the paraffin infiltration agent on the surface of the fiber should be removed by heat treatment to make it residue. If the amount is less than 0.3%, not only is this troublesome, but also the fiber strength will be reduced and the fiber will be shortened. When the mechanical premixing, the fiber length does not exceed 20-40 mm, and when the premixing is manual, it does not exceed 30-60 mm, and the fiber is fluffy; Calculate the amount of premixed materials according to the formula, and use the amount of solvent to adjust the glue to have an appropriate viscosity, so that there is no residual glue after impregnation and mixing to ensure the plastic content of the molding compound, usually when the summer temperature is high. To be smaller, when the temperature is low in winter, the viscosity should be a little larger. Third, the preparation of additives. Other solid additives should be ground, sieved, dried to achieve the specified targets; Fourth, the impregnation and mixing should make the resin glue fully impregnated fiber and filler. Mix evenly, the batch hour can be used for repeated rubbing by hand, when the batch is large, z-type kneading machine can be used; fifthly, it is torn and loosely mixed, and the materials that are mixed into a group are used manually or The machine is torn and fluffy. The tearing machine is mainly composed of a feed roller and a pair of tearing rollers with hook teeth. The reversed motion of the tearing roller tears the fed dough. Sixth, the drying will tear. The loose premix is ​​evenly distributed on a clean metal mesh. The ply should not be too thick (generally about 20 to 30 mm). It should be cooled at room temperature first. After most of the solvent is volatilized, it is dried and pre-polymerized. To a certain extent, the oven temperature is 80°C and the drying time is 20-40 minutes. Seventhly, the molded plastics that are batched together and packaged and dried are quickly cooled and then packaged in plastic bags.
The second method is to prepare a fiber molding compound by a prepreg method. The prepreg method is a method for manufacturing a fiber molding compound by continuously dipping a continuous fiber bundle through a process such as dipping, drying and cutting. The characteristics of this molding compound are: bundled, relatively compact, small specific volume, small mold feeding chamber, easy loading, less fiber damage in the production process, and the ability to lay the molding compound in the direction of the product. High-strength products can be obtained, but the flowability of the molding compound and the mutual compatibility between the material bundles are somewhat inferior, and the production volume is lower than that of the premixing method. Prepreg method can be divided into manual method and mechanical method. Mechanical prepreg method is generally used in industrial production. Among them, the manual prepreg method manual prepreg method has the same requirements as the premix method for fiber pretreatment, blending, and drying, but the fiber length is 600-800mm, and no fluffiness is required. The relative density of the glue is controlled at 1.00- 1.025 range. When copper is used for dipping, it acts as a scraper roller, and the fiber is pulled by hand between two copper rods. The dried prepreg is cut into the required length and sealed in a plastic bag. The process of mechanical prepreg method is: the fiber is guided from the creel through the bundle ring into the rubber groove dipped, the relative density of the glue is controlled at 1.00 ~ 1.025, the fiber traction speed is 1.2 ~ 1.35m/min, the fiber is passed through The rubber roller enters the first and second ovens for drying. The first-stage oven temperature is 110-120°C, and the second-stage oven temperature is 150-160°C. The dried prepreg is drawn by the traction rollers into the cutting machine and cut into the required length to seal in the plastic bag.
The extrusion method uses a screw extruder to produce glass fiber molding compounds. It overcomes the disadvantages of the use of large amounts of organic solvents in the premixing method and prepreg method, improves labor hygiene conditions, reduces costs, and makes product quality uniform and continuous. , Automated production, the disadvantage is that the fiber in the screw extruder is worn out, was severely cut and reduced the strength of the product, not used in the production of epoxy fiber molding compound.
The first method of manufacturing epoxy resin molding compounds is premixing to make fiber molding compounds. The pre-blending method consists of impregnating short-cut fibers and fillers with an epoxy resin solution, mixing them uniformly, and then tearing and drying them to obtain a fiber molding compound. The characteristics of the molding compound are: loose and non-directional fibers, and good fluidity. , The output can be large or small; but the specific volume is large, the fiber damage during the manufacturing process, the strength will be reduced, and the working conditions are poor. Each process can be manually operated, suitable for small-scale production and trial production; it can also be used for mechanical operation, suitable for mass production, with less fiber damage and high product strength during manual operation.
Experts from the China Epoxy Resin Industry Association said that the following points should be noted in the preparation process: First, fibers treated with reinforcing sizing agents should be used for fiber pretreatment. Otherwise, the paraffin infiltration agent on the surface of the fiber should be removed by heat treatment to make it residue. If the amount is less than 0.3%, not only is this troublesome, but also the fiber strength will be reduced and the fiber will be shortened. When the mechanical premixing, the fiber length does not exceed 20-40 mm, and when the premixing is manual, it does not exceed 30-60 mm, and the fiber is fluffy; Calculate the amount of premixed materials according to the formula, and use the amount of solvent to adjust the glue to have an appropriate viscosity, so that there is no residual glue after impregnation and mixing to ensure the plastic content of the molding compound, usually when the summer temperature is high. To be smaller, when the temperature is low in winter, the viscosity should be a little larger. Third, the preparation of additives. Other solid additives should be ground, sieved, dried to achieve the specified targets; Fourth, the impregnation and mixing should make the resin glue fully impregnated fiber and filler. Mix evenly, the batch hour can be used for repeated rubbing by hand, when the batch is large, z-type kneading machine can be used; fifthly, it is torn and loosely mixed, and the materials that are mixed into a group are used manually or The machine is torn and fluffy. The tearing machine is mainly composed of a feed roller and a pair of tearing rollers with hook teeth. The reversed motion of the tearing roller tears the fed dough. Sixth, the drying will tear. The loose premix is ​​evenly distributed on a clean metal mesh. The ply should not be too thick (generally about 20 to 30 mm). It should be cooled at room temperature first. After most of the solvent is volatilized, it is dried and pre-polymerized. To a certain extent, the oven temperature is 80°C and the drying time is 20-40 minutes. Seventhly, the molded plastics that are batched together and packaged and dried are quickly cooled and then packaged in plastic bags.
The second method is to prepare a fiber molding compound by a prepreg method. The prepreg method is a method for manufacturing a fiber molding compound by continuously dipping a continuous fiber bundle through a process such as dipping, drying and cutting. The characteristics of this molding compound are: bundled, relatively compact, small specific volume, small mold feeding chamber, easy loading, less fiber damage in the production process, and the ability to lay the molding compound in the direction of the product. High-strength products can be obtained, but the flowability of the molding compound and the mutual compatibility between the material bundles are somewhat inferior, and the production volume is lower than that of the premixing method. Prepreg method can be divided into manual method and mechanical method. Mechanical prepreg method is generally used in industrial production. Among them, the manual prepreg method manual prepreg method has the same requirements as the premix method for fiber pretreatment, blending, and drying, but the fiber length is 600-800mm, and no fluffiness is required. The relative density of the glue is controlled at 1.00- 1.025 range. When copper is used for dipping, it acts as a scraper roller, and the fiber is pulled by hand between two copper rods. The dried prepreg is cut into the required length and sealed in a plastic bag. The process of mechanical prepreg method is: the fiber is guided from the creel through the bundle ring into the rubber groove dipped, the relative density of the glue is controlled at 1.00 ~ 1.025, the fiber traction speed is 1.2 ~ 1.35m/min, the fiber is passed through The rubber roller enters the first and second ovens for drying. The first-stage oven temperature is 110-120°C, and the second-stage oven temperature is 150-160°C. The dried prepreg is drawn by the traction rollers into the cutting machine and cut into the required length to seal in the plastic bag.
The extrusion method uses a screw extruder to produce glass fiber molding compounds. It overcomes the disadvantages of the use of large amounts of organic solvents in the premixing method and prepreg method, improves labor hygiene conditions, reduces costs, and makes product quality uniform and continuous. , Automated production, the disadvantage is that the fiber in the screw extruder is worn out, was severely cut and reduced the strength of the product, not used in the production of epoxy fiber molding compound.
Church candle is used for church, for praying,for memorial. A candle lighted by a worshiper in a church.
Candle originated in the original era of the torch. Primitive man fat or wax like on bark or wood, tied together, made for the lighting of the torch. At about third Century BC the beeswax candles may be seen today. In the west, there is a period of time, the temple in beekeeping to self-made wax, this is mainly because the Catholic church that Mila is a symbol of a virgin conception, so the beeswax as pure light, dedicated to the altar of the church. From the existing literature, beeswax in our country have roughly same time with the west, Japan is in the Nara period (710 to 784 years) in our country was introduced into the candle of, and compared to modern candle, ancient candles have many shortcomings. The Tang Dynasty poet Li Shangyin, "when he cut a total of west window candle" of the poem
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