News Details
Linear phenolic resin coating crosslinking agent
2017-9-2 17:15:41
Linear phenolic resin coating crosslinking agent
Linear phenolic resin is used as the epoxy crosslinking agent is a kind of thermoplastic resin, linear phenolic resin crosslinking agent and crosslinking reaction of the epoxy resin is mainly achieved by phenolic epoxy groups and hydroxyl of addition reaction, thus generating volatile substances, suitable for the preparation of a coating thickness of about 300 microns of the powder coating.
Kind of crosslinking agent and linear phenolic resin epoxy crosslinking to form coating has excellent resistance to chemical corrosion resistance, heat resistance and electrical insulation, so used to the preparation of heat resistant, corrosion resistant powder coatings and electric insulation powder coating.
However, the linear phenolic resin, as epoxy crosslinking agent, also has obvious disadvantages: its brittleness is large, and the coating is brittle and incomplete when used in large amount. When used in conjunction with other crosslinking agents, it is easy to cause shrinkage and foam. In addition, its poor reactivity, with epoxy resin to be above 200 ℃ can completely crosslinking, therefore, have no crosslinking performance at low temperature.
Linear phenolic resin is also known as linear phenolic resin. When the crosslinking agent is not added, it can be dissolved in organic solvents, which can be melted in heat and will not be crosslinked in the long term. The crosslinking agent can be crosslinked with the crosslinking agent, such as hexaethylenetetramine (also known as uloto), and is an insoluble crosslinked resin.
Phenol formaldehyde resin is polymerized by phenol and formaldehyde. Under the catalytic action of the strong base, the polymerization products are the first-order phenolic resins, and formaldehyde and phenol molar ratio are 1.2 ~ 3.0:1. Aqueous solution of formaldehyde with 36 ~ 50%, catalyst for 1 ~ 5% NaOH or Ca (OH) 2, 3 h in 80 ~ 95 ℃ heating reaction get prepolymer. To prevent overreaction and gelation, a vacuum is rapidly dehydrated. The prepolymer is solid or liquid, and the molecule is generally 500 ~ 5000. It is slightly acidic, and its water solubility is related to molecular weight and composition.
Chinese name: Diethyl toluene diamine(DETDA)
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Linear phenolic resin is used as the epoxy crosslinking agent is a kind of thermoplastic resin, linear phenolic resin crosslinking agent and crosslinking reaction of the epoxy resin is mainly achieved by phenolic epoxy groups and hydroxyl of addition reaction, thus generating volatile substances, suitable for the preparation of a coating thickness of about 300 microns of the powder coating.
Kind of crosslinking agent and linear phenolic resin epoxy crosslinking to form coating has excellent resistance to chemical corrosion resistance, heat resistance and electrical insulation, so used to the preparation of heat resistant, corrosion resistant powder coatings and electric insulation powder coating.
However, the linear phenolic resin, as epoxy crosslinking agent, also has obvious disadvantages: its brittleness is large, and the coating is brittle and incomplete when used in large amount. When used in conjunction with other crosslinking agents, it is easy to cause shrinkage and foam. In addition, its poor reactivity, with epoxy resin to be above 200 ℃ can completely crosslinking, therefore, have no crosslinking performance at low temperature.
Linear phenolic resin is also known as linear phenolic resin. When the crosslinking agent is not added, it can be dissolved in organic solvents, which can be melted in heat and will not be crosslinked in the long term. The crosslinking agent can be crosslinked with the crosslinking agent, such as hexaethylenetetramine (also known as uloto), and is an insoluble crosslinked resin.
Phenol formaldehyde resin is polymerized by phenol and formaldehyde. Under the catalytic action of the strong base, the polymerization products are the first-order phenolic resins, and formaldehyde and phenol molar ratio are 1.2 ~ 3.0:1. Aqueous solution of formaldehyde with 36 ~ 50%, catalyst for 1 ~ 5% NaOH or Ca (OH) 2, 3 h in 80 ~ 95 ℃ heating reaction get prepolymer. To prevent overreaction and gelation, a vacuum is rapidly dehydrated. The prepolymer is solid or liquid, and the molecule is generally 500 ~ 5000. It is slightly acidic, and its water solubility is related to molecular weight and composition.
Chinese name: Diethyl toluene diamine(DETDA)
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Flash Point°C161.1°C
The linear phenolic resins are formaldehyde and phenol, which are obtained by the molar ratio of 0.75 ~ 0.85:1. It is often used as a catalyst for oxalic acid or sulfuric acid. The polymerization reaction can be completed by heating the reflux for a certain time. The dosage of the catalyst was 1-2 oxalic acid or less than 1 portion of sulfuric acid for every 100 doses of phenol. Low molecular weight linear polymers can only be generated due to the small amount of formaldehyde added. The reaction mixture was crushed after high temperature dehydration, cooling, and mixed into 5 % - 15 % of 6 methylene tetramine, which was quickly crosslinked.
Phenolic resin plastic is the first commercial synthetic polymer, which has the advantages of high strength and dimension stability, shock resistance, creep resistance, solvent resistance and good moisture resistance. Most of the phenolic resin need to add filler to strengthen, general level of phenolic resin are used such as clay, mineral powder and short fiber to enhance, engineering level phenolic resin with glass fiber, graphite and ptfe to enhance temperature can reach 150 ~ 170 ℃.
Main application areas are: manufacturing molding powder, machine parts, tool handles, stationery, daily necessities, electrical appliances, high insulation products, etc., such as switch, socket shell, resistor shell, automobile ignition components, such as containing phenolic resin composite material can also be used for aerospace vehicles. Phenolic polymers can be used as adhesives for plywood, fiberboard and grinding wheels, as well as coatings, such as phenolic varnish.
Compared with other resin systems, the phenolic resin system has the advantage of low smoke and low toxicity. In the case of combustion, the phenolic resin system produced by scientific formulations will slowly decompose and produce hydrogen, hydrocarbons, water vapor and carbon oxides. The amount of smoke produced during the decomposition is relatively small and the toxicity is relatively low. These characteristics make phenolic resin suitable for public transport and safety requirements of very strict areas such as mines, guardrails and construction.
Heat treatment can improve the glass temperature of crosslinked resin, which can improve the properties of resin. The glass temperature is similar to that of crystallized solid such as polypropylene. The initial vitrification temperature of phenolic resin is related to the crosslinking temperature used in the initial crosslinking stage. Heat treatment process can improve the liquidity of crosslinked resin further prompt response, at the same time also can remove residual volatile phenol, reduce shrinkage, enhance the dimensional stability, hardness, and high temperature strength. The resin also tends to shrink and crispy. The heating curve of resins will depend on the original crosslinking condition and resin system.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
The linear phenolic resins are formaldehyde and phenol, which are obtained by the molar ratio of 0.75 ~ 0.85:1. It is often used as a catalyst for oxalic acid or sulfuric acid. The polymerization reaction can be completed by heating the reflux for a certain time. The dosage of the catalyst was 1-2 oxalic acid or less than 1 portion of sulfuric acid for every 100 doses of phenol. Low molecular weight linear polymers can only be generated due to the small amount of formaldehyde added. The reaction mixture was crushed after high temperature dehydration, cooling, and mixed into 5 % - 15 % of 6 methylene tetramine, which was quickly crosslinked.
Phenolic resin plastic is the first commercial synthetic polymer, which has the advantages of high strength and dimension stability, shock resistance, creep resistance, solvent resistance and good moisture resistance. Most of the phenolic resin need to add filler to strengthen, general level of phenolic resin are used such as clay, mineral powder and short fiber to enhance, engineering level phenolic resin with glass fiber, graphite and ptfe to enhance temperature can reach 150 ~ 170 ℃.
Main application areas are: manufacturing molding powder, machine parts, tool handles, stationery, daily necessities, electrical appliances, high insulation products, etc., such as switch, socket shell, resistor shell, automobile ignition components, such as containing phenolic resin composite material can also be used for aerospace vehicles. Phenolic polymers can be used as adhesives for plywood, fiberboard and grinding wheels, as well as coatings, such as phenolic varnish.
Compared with other resin systems, the phenolic resin system has the advantage of low smoke and low toxicity. In the case of combustion, the phenolic resin system produced by scientific formulations will slowly decompose and produce hydrogen, hydrocarbons, water vapor and carbon oxides. The amount of smoke produced during the decomposition is relatively small and the toxicity is relatively low. These characteristics make phenolic resin suitable for public transport and safety requirements of very strict areas such as mines, guardrails and construction.
Heat treatment can improve the glass temperature of crosslinked resin, which can improve the properties of resin. The glass temperature is similar to that of crystallized solid such as polypropylene. The initial vitrification temperature of phenolic resin is related to the crosslinking temperature used in the initial crosslinking stage. Heat treatment process can improve the liquidity of crosslinked resin further prompt response, at the same time also can remove residual volatile phenol, reduce shrinkage, enhance the dimensional stability, hardness, and high temperature strength. The resin also tends to shrink and crispy. The heating curve of resins will depend on the original crosslinking condition and resin system.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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