In the whole process of carbon fiber products forming, the bonding force between the surface of the molding commodities and grinding tools will be strong. In addition, from the raw material to the grinding tool mouth, with the increase of temperature, the resin viscosity decreases, and the volume expands. The efficiency of the resin is slowly generated, expanded and accumulated in the working pressure on the inner wall of the grinding tool, and the highest value of (Zui) is achieved in the cementation area. In order to avoid the additional load of the molded FRP products sticking to the grinding tool, it is necessary to release a kind of isolation film (i.e. pull extrusion internal release agent) between the product and the grinding tool, so that the products can easily slide off the grinding tool, so as to ensure the product process performance and the grinding tool are perfect.

Because the production and manufacture of extrusion process is a continuous whole process, the actual effect of high quality die making is the key standard to ensure the smooth development of the extrusion process. The internal release agent of pull extrusion is divided into two parts: external release agent and internal release agent according to different application methods. The initial extrusion molding process is to use external pulling extrusion internal release agent, common methyl silicone oil, etc. In application, the internal release agent of pull extrusion is put into the special groove. When the commodity is pulled, the internal release agent is sent to the surface of glass fiber molding material soaked with resin, and then into the molding mold to dry and solid to achieve the mold effect. However, the release agent has been used in a large amount and the product technical performance is not ideal, and has been changed into the internal release agent.

Matters needing attention when using pultrusion internal release agent for carbon fiber products

Selection of internal release agent in extrusion

The internal release agent is to add it to the resin immediately. It is soluble with liquid resin, but it is incompatible with dry solid resin. Under certain production and processing temperature standards, it diffuses from the outside of resin PCB to the surface of dry solid products, and produces a layer of isolation film between grinding tools and products, which has the effect of mold making. The release agent in extrusion generally includes phosphate, ammonium sulfate, polyether salt, triethanolamine oil, etc.

The actual effect of zinc stearate is good. Because of the high viscosity of resin, it is impossible to mix and even add powder zinc stearate immediately. Moreover, zinc stearate is loose and large in volume, and more gas is brought into the resin, which leads to more bubbles of resin. Therefore, zinc stearate is usually added to crosslinking agent before application, which can be made into a uniform paste and then added to resin. Zinc stearate as internal pulling and extrusion internal release agent has no obvious harm to the color, dry solid rate and resin viscosity of the products.

According to Chen Gong, in the production and manufacture of extrusion, it is more desirable to apply the internal extrusion internal release agent with liquid shape at room temperature. At present, the main demoulding agents on the market are the compound of primary amine, secondary amine and organic chemical ammonium sulfate mixed with human fat ester.

Advantages of liquid extrusion internal release agent in extrusion process:

1. It is very easy to disperse in resin;

2. It has the function of cleaning grinding tools;

3. Can maintain metal material grinding tools from corrosion;

4. In addition, the productivity is increased by reducing friction resistance and wear loss of friction tools;

5. It can reduce the interfacial tension of resin compounds, reduce the viscosity of resin, improve the permeability of raw materials and fillers, and improve the circulation of resin;

6. Assist in anti foaming and improve the process performance of components, and make the surface of the products smooth and smooth;

7. It does not harm the dry solid characteristics of resin, does not change the availability period of mixed resin, does not harm the physical and physical properties of products, and does not harm the aging resistance of products.

Because most of the liquid internal pulling and extrusion internal release agents are acid-base, the following problems should be paid attention to in application:

1. The color change is caused by the application of acid sensitive color paste;

2. When using the partial alkali packing, such as calcium phosphate, the acid-base pull extrusion internal release agent will reflect the release agent, which will cause the viscosity of the mixture to be improved, but it is not easy to harm the actual effect of the mold;

3. If the filler is aluminum chloride, the acid-base pull extrusion internal release agent will release water during the whole process of dry and solid mixing material, which will cause problems such as bubble and crack.

Generally, the starting and ending use of the internal release agent is 1% of the resin amount, and the reasonable addition of the category is 0.75-2% of the net weight of the resin. It should be adjusted appropriately according to the specific situation.

1. The amount of aluminum with thick wall can be reduced, such as 0.8% or less;

2. Thin-walled or complex aluminum must be added.

3. In the high filling management system, the amount of release agent in the extrusion shall be increased, but the amount of the release agent in the extrusion process is too much, which will delay the time of dry fixation.

4. In the production and manufacture of extrusion, if the friction resistance is too large and can not be found, the usage of the release agent in the extrusion must be appropriately increased. Pay attention to the feeding sequence when applying. Before adding epoxy curing agent, filler and other resin preservative, the internal release agent shall be added to the resin management system and mixed evenly. That can achieve the best practical effect of Zui.