Study on the release agent for the hottest wood co

Research on release agent for wood composite materials (I)

in the production of various wood composite plates, the lining plate and slab of hot pressing plate in hot press are easy to produce adhesion, that is, sticking plate. At the same time, the hot pressing plate, the key component of the hot press, is damaged due to long-term heating, humidity and the erosion of curing agent in various thermosetting resin adhesives during production, as well as the influence of factors such as wear and adhesion during the pressing process, which increases the replacement times of the pressing plate, seriously affects the quality of composite plates and the service life of the hot pressing plate, thus reducing the production quality of the hot press. For this reason, many domestic manufacturers have done a lot of research work. The usual method is: if the corrosion surface of the pressing plate is small, reprocess and repair the plate surface; If the surface corrosion surface is large and cannot be repaired, the pressing plate must be replaced frequently, resulting in frequent shutdown, reduced production efficiency and loss of economic benefits. Another solution is to pad the stainless steel lining plate on the hot pressing plate surface, which solves the corrosion of the hot pressing plate, but only this will increase the hot pressing cost, and the heat energy loss is large, the energy is wasted, and the hot pressing cycle is prolonged, which will affect the production of the whole production line, and the effect is not ideal. The demoulding of the plate cannot be really solved. Therefore, it is very necessary and key to treat the surface of hot pressing plate with anti-corrosion and anti sticking film. It can fundamentally solve the problems of hot pressing plate corrosion and sticking, greatly improve the pollution ability of composite plates, strengthen the production quality and the production efficiency of hot pressing, and significantly improve the service life of plates treated with release agent

1. Performance of release agent

in view of the characteristics of high hot pressing temperature and strong mold adhesion of slabs, a good release agent should have the following properties:

1.1 good lubrication and release performance. That is, the mold release agent is required to have sufficient adsorption strength on the slab surface at high temperature, form a complete shielding layer during slab deformation, and have a low friction coefficient

1.2 good cooling and thermal insulation, increased temperature of hot pressed blank, coupled with plastic deformation and friction heat, are easy to reduce the temperature of the die and accelerate the wear, thus shortening the service life. A good mold release agent should have high-efficiency cooling effect and heat insulation effect, so that the mold can work at a lower temperature

1.3 it has strong high temperature resistance and lubrication performance. As a hot pressing mold release agent, it must have good lubrication performance to ensure its lubrication and mold release

1.4 good thermal and chemical stability. Good stability requires that the release agent should not oxidize and burn within the temperature range, keep the performance unchanged, not corrode the mold, and not have residual decomposition products on the mold surface

in addition, the release agent should not produce harmful gas and smoke in the process of use, which is non-toxic, safe, easy to operate and low cost

2. Type of release agent

release agent, also known as release lubricant or mold release lubricant, is to prevent rubber, resin, polyurethane and other elastomeric substances as well as molded products, laminated products, spinning parts and other substances of other materials or molded composite products from adhering to the mold, and a kind of isolation mold is applied between the product and the mold, so that the product can be easily detached from the mold, At the same time, ensure the surface quality of products and the integrity of film. It is required to be insoluble in rubber or resin, most of which are liquid or low melting point substances. It is used to paint the inner wall of the mold or the surface of the lining plate, and can also be directly added to the material. Commonly used release agents mainly include the following categories:

2.1 according to the mode of use

release agents can be divided into external release agents and internal release agents according to the mode of use. The external release agent is directly applied to the surface of the film to prevent the bonding between the product and the mold; The commonly used external release agents are:

2.1.1 silicone release agents

silicone compounds, silicone oil, silicone resin and other organic silicon soluble series release agents. Their surface tension is small, and they are a release agent with good isolation. They are heat-resistant, toxic, glossy, not compatible with resin, and have little pollution to molds. They are mainly used for model products of natural rubber, plastic and butyl rubber. As long as it is painted once, it can be demoulded once. For example, Michacl in German patent de proposes a mold release agent with more stable performance than usual silicone, which can maintain a stable number of repeated demoulding and the paintability of molded products. [1] Its composition includes polydimethylsiloxane, organosiloxane resin, alkyl titanate or titanium chelate. Silicone release agents mainly include solvent type (silicone oil, silicone paint); Lotion type (silicone oil); Complex type (silicone oil, silicon dodecaoxide); Aerosol type (silicone oil); Drying type (bridging silicone)

2.1.2 wax oil mold release agent

wax oil series mold release agent is characterized by low price and good adhesion performance, but the disadvantage is that the product surface is easy to be oily and easy to pollute the mold. Its main varieties are:

(1) industrial Vaseline, which is directly used as a mold release agent

(2) paraffin, directly use the schematic diagram of waste plastic circular economy system as the release agent

(3) sulfonated vegetable oil, directly used as mold release agent

(4) printing and dyeing oil (Turkish red oil, Swire oil), add 0.5% to 100 parts of boiling water The lotion made of printing and dyeing oil has better demoulding effect than soapy water

(5) polyethylene wax (relative molecular weight). Mixing polyethylene with a certain proportion of emulsifier is suitable for release agent of rubber products

(6) polyethylene glycol (relative molecular weight) is directly used for demoulding of rubber products

in Japanese patent 77/68266, a polyurethane foam release agent mixed with paraffin and other waxes was proposed. [1] For example:

40 parts of paraffin wax (m..P.68 ℃), 40 parts of microcrystalline wax (m..P. ℃), 20 parts of microcrystalline wax (m..P. ℃), melt at 100 ℃, spray on an iron mold or aluminum mold preheated to 80 ℃, and cool to 40 ℃, foam is easy to be molded

the former Soviet Union once proposed the following two formulas:

① refined ground wax%, peat wax%, 20% surfactant aqueous solution 30% - 70% (surfactant is non-ionic, such as os-20), stearic acid as stabilizer and water to make a lotion, which can be used as a release agent for foam polyurethane

② microcrystalline wax 2.7, silicone oil 2, thickened white oil 7.88, fungicide 0.1, ethoxylated fatty alcohol 1.5, ethoxylated nonylphenol 0.4, fatty alcohol polyethylene ether 0.34, water 84.78. The above lotion can be used for demoulding polyurethane water baffle of automobile

German Riza Nur ozell et al. Proposed a release agent based on fatty acid aluminum salt, which is suitable for PU foam, especially for whole skin foam. [1] As long as a very thin solution is applied to the mold, a very thin film is formed. Although the amount is small, the effect is good. The subtle features on the mold can be copied to the molded object, and it can be painted and painted once without purification, and can be reused many times. Its composition is that when we find and judge which part of the system is faulty, the number of carbon atoms of the fatty acid is. The preparation method is to dissolve the mixed fatty acid aluminum salt in dichloromethane to make a 1% solution. Spray the solution on the metal mold wall to form a very thin film, which can be reused for 10 times after coating once, and the demoulding effect is grade I. (to be continued)

therefore, this is the first time to prepare two-dimensional metal carbides