Synthesis and application of rosin modified phenol

2022-08-02
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The synthesis process and development of rosin modified phenolic resin for offset printing ink. Due to its unique honeycomb structure, it can be well wetted with pigments, and can react properly with gel agent to obtain a bonding material with certain viscoelasticity and energy consumption of reducing 100million tons of standard coal, which is widely used in lithographic ink. The experimental results show that the performance of the resin can be fully utilized. The whole length of the saw blade largely depends on the type of alkyl phenol. At present, the phenols used in rosin modified phenolic resin are tert butylphenol, octyl phenol, nonyl phenol, dodecyl phenol, etc., as well as phenol and bisphenol A with poor oil solubility. The use of high-grade alkylphenol makes the resin have good solubility, high viscosity and large molecular weight, which can basically meet the needs of high-speed printing and large-scale use of aromatic free mineral oil. The length and branched chain degree of alkylphenols have great influence on the reactivity of the condensate, the softening point and the accommodation of rosin modified resin

I. synthesis process of rosin modified phenolic resin

rosin modified phenolic resin is still characterized by the traditional synthesis process. The one-step method is characterized by direct reaction after mixing phenol, aldehyde and other raw materials with rosin. The process form is simple, but the control requirements for temperature rise in subsequent steps are high; The characteristic of the two-step process is to synthesize phenolic condensation intermediates in advance, then react with rosin system, and finally form a resin with low acid value, high softening point, equivalent molecular weight and certain mineral oil solvent solubility through each specific reaction stage

1. one step process

reaction principle of one-step process:

① synthesis of A-grade phenolic resin:

alkyl phenol is added to the molten rosin. Paraformaldehyde exists in the system in granular form, and then decomposes into monomer formaldehyde, which is subject to polycondensation reaction with alkyl phenol

② formation of methylene quinone

temperature rise dehydration. In the process of temperature rise, the activity of hydroxymethyl in the system increases rapidly, resulting in dehydration within hydroxymethyl molecules, condensation and etherification between hydroxymethyl molecules, forming phenolic condensates with different degrees of polymerization

③ addition of rosin with methylene quinone and maleic anhydride

maleic anhydride is added at 180 ℃, and the unsaturated double bond of maleic anhydride is added with the double bond in rosin acid. At the same time, methylene quinone and rosin acid are also subject to Diels alder addition reaction to form maleated benzodihydrofuran compound

④ esterification of polyols

the existence of a large number of carboxyl groups in the system will destroy the balance of the system and cause instability of the resin. So we add polyols and use the esterification reaction between hydroxyl groups of polyols and carboxyl groups in the system to reduce the acid value of the system. At the same time, through the esterification of polyols, a polymer suitable for offset printing ink was formed

2. two step process

reaction principle of two-step process:

① under the action of special catalyst, formaldehyde forms a variety of methyl phenolic oligomers containing a large amount of active hydroxymethyl in the solution of alkylphenol. Since the system has no inhibitory effect of rosin acid, more than 5 phenol structure units can be synthesized

② polyols and rosin are esterified at high temperature. Under the action of alkaline catalyst, the required acid value can be achieved quickly

③ in the reacted rosin polyol ester, slowly add the synthetic grade a phenolic resin, control the dropping rate and temperature, and the dropping is completed. Heat up and dehydrate, and finally form the required resin

the advantage of the one-step process is that the waste is removed in the form of steam, which is easy for environmental treatment. However, the phenolic condensation reaction in the molten rosin is prone to many side reactions due to high reaction temperature and uneven dissolution. Therefore, it is difficult to control the detection and quality adjustment of condensation products, and it is not easy to obtain stable resin products. The advantage of the two-step method is that the phenolic condensation oligomer with relatively stable structure and composition can be obtained, each reaction stage is easy to monitor, and the product quality is relatively stable. The disadvantage is that the traditional phenolic pulp condensate must be neutralized by acid and rinsed with a large amount of water for many times before it can react with rosin, resulting in a large amount of phenolic wastewater, which causes great damage to the environment and consumes a lot of man hours

the question of whether one-step or two-step process is right or wrong has long been the focus of attention of ink manufacturers. However, recently, with the successful development of the non washing process for the synthesis of phenolic condensates, the two-step synthesis process has become more reasonable

here is the difference between the two-step washing process and the traditional washing process:

the traditional washing process

all the food contact materials industry will face some challenges. The main differences between the two processes

2. The development of resin bonding materials

ink bonding materials are still dominated by rosin modified phenolic resin. Looking at a large number of patent documents published in recent years, The main work still focuses on how to select alkyl phenols, use fatty acids or alkyd resins modified by fatty acids and various modification processes. In addition, to adapt to the trend of ink solvent de aromatics, general lithographic inks contain 10% ~ 30% aromatic solvent and remove aromatics to less than 1%, and their aniline point will rise by more than 10 ℃, which will greatly reduce the solubility of the resin and make the fluidity and gloss of the ink worse. Therefore, a resin with higher solubility must be used to adapt to it. To meet the needs of manufacturing lithographic ink by the extrusion process, the production of lithographic ink by the extrusion process is considered to be a production method with the highest efficiency, better quality and lower cost. By kneading and dehydrating the wet pigment and the binder at a certain temperature, the pigment particles can be directly dispersed into the binder of the ink. According to the size and surface treatment of the pigment particles, the binder must be controlled to have appropriate surface tension and water resistance, The binder made of rosin modified phenolic resin with low polarity, high solubility and high molecular weight is suitable for the manufacturing process of extrusion ink

the development of ink is inseparable from the development of resin. Adapting to the development of printing industry, stabilizing the quality of resin products, improving the production process and developing new products will be the focus of the future development of resin. □

information source: Guangdong packaging

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