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Plastic molding method for coating foam molding and two forming
Publisher:SHANGHAI DAKE MACHINERY CO.,LTD   Time:2015/6/10   Read:1133

Coating. In order to prevent corrosion, insulation, decoration, etc., in order to liquid or powder form in the fabric, paper, metal foil or plate and other objects on the surface of a plastic sheet (such as.0.3 mm below) method.

The most commonly used plastic coating method is generally hot plastic, such as polyethylene, polyvinyl chloride, polyamide, polyvinyl alcohol, polyvinyl chloride three.

Coating process has hot melt coating, spray coating, flame spraying, electrostatic spraying and plasma spraying.

(1) hot melt coating. With compressed air to the plastic powder through the spray gun, spray to the surface of the workpiece surface, the plastic melt, the formation of the cooling layer.

(2) fluid spraying. The workpiece is immersed in a container of resin powder and the resin powder is melted and adhered to the surface.

(3) flame spraying. A method of spraying the fluid flow through a conical flame zone of the lance to be melted and realized.

(4) electrostatic spraying. The use of high voltage electrostatic field, that is, the workpiece is connected to the positive, plastic powder spraying with negative charge, then the plastic electrostatic spraying onto the workpiece.

(5) plasma spraying. With a plasma gun passing through the plasma generating region of inert gas, such as gas mixture of argon, nitrogen, helium has 5500 ~ 63 DEG C high speed and high energy plasma flow, entrainment powder resin to high-speed jet to surface melting to form a coating.

Foam forming. Foaming process is the process of making the plastic produce the porous structure. Almost all of the thermosetting and thermoplastic plastics can be made from foamed plastics, commonly used resin polystyrene, polyurethane, polyvinyl chloride, polyethylene, urea formaldehyde, phenol, etc..

Bubble pore structure of the foam is divided into two categories according to, if the vast most stomata is connected with each other is called open pore foam; if the vast most stomata are separated from each other, said closed cell foam. The foam structure holes or obturator is decided by the manufacturing method.

(1) chemical foaming. Chemical foaming agent, which is composed of a chemical blowing agent, which has a special chemical blowing agent, the gas generated by the chemical reaction between the heating decomposition or the raw material, so that the plastic melt is filled with the bubble hole. Chemical foaming agent in the heating of carbon dioxide, nitrogen, ammonia, etc.. Chemical foaming commonly used in polyurethane foam production.

(2) physical foaming. Physical foaming plastics in dissolved gas or liquid, and then the expansion or gasification of foam. Physical foaming to adapt to a variety of plastics.

(3) mechanical foaming. By mechanical stirring method, the gas is mixed in the liquid mixture, and then the foam is formed by the process of shaping. Often use this method to sleep urea formaldehyde resin and other such as polyvinyl formal, poly vinyl acetate, polyvinyl chloride sol and also apply.

Two forming. The two molding is one of the methods of plastic forming. A method of making a product of the desired shape with a plastic profile or a blank as a material to make it through heating and external force.

(1) hot forming. Heat forming is a thermoplastic sheet that is heated to a softening in the gas (1) hot forming process. Heat forming is a kind of forming method which can be used to heat the hot plastic sheet to soften, under the pressure of gas, liquid pressure or mechanical pressure. There are a lot of ways in the plastic molding, which can be divided into:

Molding the single-mode (male or female) or to die, to use external mechanical pressure or weight, sheet material forming method of a variety of products, it is different in a processing molding. This method is suitable for all thermoplastic plastics.

Differential pressure forming the single-mode (male or female) or to die, you can not die, in the role of the gas pressure, heating to soft plastic sheet surface close to die, after cooling into forming method of a variety of products. Differential pressure forming can be divided into vacuum forming and air pressure forming.

Heat forming is especially suitable for the manufacture of the products with the thin wall and large surface area. Commonly used plastic varieties have a variety of types of polystyrene, organic glass, PVC, ABS, polyethylene, polypropylene, polyamide, polycarbonate and polyethylene terephthalate, etc..

Heat forming equipment includes a clamping system, heating system, vacuum and compressed air system and forming mould, etc..

(2) biaxial stretching. In order to make the molecular reorientation of thermoplastic film or sheet metal, especially in the glass transition temperature of the two way stretching process. Directional tension between the polymer glass transition temperature and melting point, after stretching and orienting and rapid cooling to room temperature after the films or filaments, in the direction of the tensile mechanical properties are greatly improved.

Fit to stretch and orientation of polymers: poly (vinyl chloride), poly (ethylene terephthalate), poly partial dichloro ethylene, poly (methyl methacrylate), polyethylene, polypropylene, polystyrene and styrene copolymer. (3) solid phase forming. Solid forming is the method of forming the product by using the hot plastic profile or the blank under pressure. The molding process in the plastic melt (softening) temperature below (at least below the melting point 10-20). Are solid forming. The non crystalline plastics in glass transition temperature above and below the melting point of high elastic region processing often call for hot forming, and near the glass transition temperature below processing is called cold forming or room temperature molding, also often called plastic cold working methods or room temperature plastic processing.

This method has the following advantages: short production cycle, improving the toughness and strength of the product, the equipment is simple, and the production of large and ultra large products can be produced. The disadvantage is: it is difficult to produce complex, sophisticated products; production process is difficult to control, products

 
 

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