Preparation method of novolac epoxy resin with high softening point and high epoxy equivalent

Abstract

The invention relates to the field of high polymer chemistry, in particular to a preparation method of high-softening-point and high-epoxy-equivalent novolac epoxy resin, and novolac epoxy resin with different softening points and epoxy equivalents is obtained under different raw material proportions at different reaction temperatures and reaction time.

Description

Technical Field

[0001] The invention relates to the field of polymer chemistry, and in particular to a method for preparing a phenolic epoxy resin with a high softening point and a high epoxy equivalent. Background Art

[0002] Epoxy resin is an important thermosetting resin with excellent comprehensive properties. The cured product of phenolic epoxy resin has a large cross-linking density, excellent bonding strength, heat resistance and chemical resistance, and is widely used in electronic copper clad boards, electronic laminates, heat-resistant adhesives, composite materials, high-temperature resistant coatings, civil engineering and electronic inks. The commonly used phenolic epoxy resin EMTE638 has a softening point of 35-40°C. In the powder coating industry and other industries, a new softening point requirement of >50°C is proposed, which cannot meet its use requirements.

[0003] High softening point phenolic epoxy resin is widely used in electronic copper clad boards, electronic laminates, heat-resistant adhesives, composite materials, high-temperature resistant coatings, civil engineering and electronic inks, powder coatings and other fields. It has broad market prospects.

[0004] Bisphenol A novolac epoxy resin is a multifunctional glycidyl ether epoxy resin. It contains a phenolic structure in its molecular structure. It exhibits excellent mechanical strength, electrical insulation, water resistance, chemical resistance, high glass transition temperature and thermal stability. It is widely used in copper clad laminates, electronic laminates, heat-resistant adhesives, composite materials, high-temperature resistant coatings, civil engineering and electronic inks. Ordinary bisphenol A novolac epoxy resin has the disadvantage of easy agglomeration due to its low softening point (60-70℃). The high softening point bisphenol A novolac epoxy resin (80-90)℃ overcomes this disadvantage and has a higher cross-linking density. The product will be more suitable for high-temperature resistant adhesives, high Tg epoxy powder coatings and laminated materials.

[0005] The present invention invents a method for synthesizing a high softening point and high epoxy equivalent phenolic epoxy resin by using phenolic epoxy resin, phenolic resin, catalyst and organic solvent. By using the method of reacting under different temperature conditions, different reactions occur at different synthesis stages to generate a specific epoxy resin structure, which is also beneficial to slow down the release of reaction heat and control the reaction temperature. Finally, after the organic solvent is recovered, phenolic epoxy resins with different softening points are obtained, and the resin index is controllable. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a high-softening point and high-epoxy equivalent novolac epoxy resin: the process comprises the following steps: fully mixing the novolac epoxy resin, the phenolic resin and the organic solvent under heating and stirring conditions, adding a catalyst, reacting for a period of time, and then continuing to react for a period of time under another temperature condition. After the reaction is completed, the organic solvent is recovered under high temperature and vacuum conditions to obtain a high-softening point and high-epoxy equivalent novolac epoxy resin product.

[0007] The present invention adopts the following technical solutions: The preparation method of the high softening point and high epoxy equivalent phenolic epoxy resin of the present invention comprises the following steps: (a) mixing a phenolic epoxy resin and an organic solvent, heating and dissolving them to obtain a raw material mixed liquid; (b) adding phenolic resin to the raw material mixed solution, and continuing to dissolve at a certain temperature to obtain a mixed solution I; (c) adding a catalyst under the temperature condition of ①, and then reacting for a period of time under the temperature condition of ② to obtain product I; (d) Product I, continue to react for a period of time under temperature ③ to obtain product II; (e) recovering the organic solvent from the reaction product II under high temperature and vacuum conditions to obtain a phenolic epoxy resin with a high softening point and high epoxy equivalent.

[0008] 1. Preferably, in step a), the organic solvent is one or more of toluene, 1,4-dioxane, isopropanol, methyl isobutyl ketone, xylene, and n-butanol.

[0009] 2. Preferably, in steps a) and b), the weight ratio of phenolic epoxy resin, organic solvent and phenolic resin is 100:(10-50):(3-20).

[0010] 3. Preferably, in step c), the temperature ① is 80-100°C, the temperature ② is 100-120°C, and the reaction time is 1-4 hours.

[0011] 4. Preferably, in step c), the catalyst is one of 2-methylimidazole, 2-ethyl, 4-methylimidazole, triphenylphosphine, and butyltriphenylphosphine bromide, and the weight ratio of the added amount to the phenolic resin is: catalyst: phenolic resin = (1-10):100.

[0012] 5. Preferably, the reaction temperature ③ in step (d) is 150-180°C, and the reaction time is 1-4 hours.

[0013] 6. Preferably, in step (e), the organic solvent recovery temperature is 160° C. and the vacuum pressure is <3 KPa.

[0014] The present invention has the following beneficial effects: (1) The high softening point and high equivalent weight phenolic epoxy resin of the present invention has a softening point of 45-90° C., an epoxy equivalent of 200-270 g / eq, a narrow molecular weight distribution, a high purity of the obtained resin, and controllable resin indicators.

[0015] (2) The present invention conducts the reaction in stages by reacting under different temperature conditions, so that the structure of the generated resin is stable, the reaction temperature is mild, and the reaction process is easy to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Flow chart for the preparation of high softening point and high epoxy equivalent phenolic epoxy resin DETAILED DESCRIPTION

[0017] Combined with Figure 1 The present invention is described in further detail: See also Figure 1 The present invention is the synthesis of high softening point high epoxy equivalent phenolic epoxy resin: phenolic epoxy resin, phenolic resin, organic solvent are fully mixed under heating and stirring conditions, a catalyst is added, and the reaction is carried out under different temperature conditions. After the reaction is completed, the organic solvent is recovered and recycled under high temperature and vacuum conditions to obtain a high softening point high epoxy equivalent phenolic epoxy resin product. The high softening point high epoxy equivalent phenolic epoxy resin production process is as follows: The phenolic epoxy resin and the organic solvent are added to the reaction kettle, stirred and fully mixed, and heated to dissolve. After the dissolution is completed, the phenolic resin is added and stirred to dissolve. After the dissolution is completed, the catalyst is added to the reaction kettle at a temperature of 80 to 100° C. After completion, the reaction is carried out at a temperature of 100 to 120° C., and then the temperature is raised to 150 to 180° C. The reaction is completed for a period of time. After the reaction is completed, the organic solvent is recovered at a temperature of 160° C. and a vacuum pressure of less than 3KPa to obtain a phenolic epoxy resin with a high softening point and high epoxy equivalent.

[0018] The present invention is described in detail below with reference to the examples. It should be noted that unless otherwise specifically stated, the steps and values ​​described in these examples do not limit the scope of the present invention.

[0019] Embodiment 1:

[0020] (a) Phenol novolac epoxy resin, toluene and phenolic resin are mixed in a weight ratio of 100:20:3 according to the process to obtain a raw material mixed solution.

[0021] (b) adding 2-methylimidazole at 80° C. in a ratio of 1:100 to phenolic resin, exothermic reaction and heating to 100° C. for 1 hour to obtain a reaction solution I.

[0022] (c) The reaction solution I was heated to 150° C. and reacted for 1 hour to obtain a reaction solution II.

[0023] (d) The reaction solution II is heated to 160° C. and vacuum pressure is less than 3 KPa to recover the organic solvent and obtain a phenol novolac epoxy resin having a softening point of 46.6° C. and an epoxy equivalent of 201.3 g / eq.

[0024] Embodiment 2:

[0025] (a) Phenol novolac epoxy resin, methyl isobutyl ketone, isopropyl alcohol and bisphenol F are mixed in a weight ratio of 100:50:20 according to a process to obtain a raw material mixed solution.

[0026] (b) adding 2-ethyl 4-methylimidazole at a ratio of 10:100 to phenolic resin at 100° C., exothermic reaction and heating to 120° C. for 4 hours to obtain a reaction solution I.

[0027] (c) The reaction solution I was heated to 180° C. and reacted for 4 hours to obtain a reaction solution II.

[0028] (d) The reaction solution II is heated to 160° C. and vacuum pressure is less than 3 KPa to recover the organic solvent and obtain a phenol novolac epoxy resin having a softening point of 83.8° C. and an epoxy equivalent of 261.6 g / eq.

[0029] Embodiment 3: (a) Mix bisphenol A novolac epoxy resin, methyl isobutyl ketone, 1,4-dioxane and bisphenol A in a weight ratio of 100:30:5 according to a process to obtain a raw material mixed solution.

[0030] (b) adding triphenylphosphine at a ratio of 5:100 to bisphenol A at 90° C., exothermic reaction was carried out and the temperature was raised to 110° C. for 3 hours to obtain a reaction solution I.

[0031] (c) The reaction solution I was heated to 170° C. and reacted for 3 hours to obtain a reaction solution II.

[0032] (d) The reaction solution II is heated to 160° C. and vacuum pressure is less than 3 KPa to recover the organic solvent and obtain a bisphenol A novolac epoxy resin having a softening point of 89.3° C. and an epoxy equivalent of 235.7 g / eq.

[0033] Embodiment 4: (a) Mix o-cresol-formaldehyde epoxy resin, methyl isobutyl ketone, xylene and o-cresol-formaldehyde resin in a weight ratio of 100:40:4 according to a process to obtain a raw material mixed solution.

[0034] (b) At 80° C., butyl triphenylphosphonium bromide was added in a ratio of 6:100 to o-cresol-formaldehyde resin, the reaction was exothermic and the temperature was raised to 110° C., and the reaction was continued for 1 hour to obtain a reaction solution I.

[0035] (c) The reaction solution I was heated to 170° C. and reacted for 4 hours to obtain a reaction solution II.

[0036] (d) The reaction solution II is heated to 160° C. and vacuum pressure is less than 3 KPa to recover the organic solvent and obtain an o-cresol-formaldehyde epoxy resin having a softening point of 88.5° C. and an epoxy equivalent of 240 g / eq.

Claims

1. A method for preparing a high softening point and high epoxy equivalent phenolic epoxy resin, characterized in that: The preparation comprises the following steps: (a) mixing a phenolic epoxy resin and a solvent and heating and dissolving them to obtain a raw material mixed solution; (b) adding phenolic resin to the raw material mixed solution, and continuing to dissolve at a certain temperature to obtain a mixed solution I; (c) adding a catalyst to the mixed solution I, reacting for a period of time at a certain temperature to obtain a reaction solution II; (d) continuing the reaction of the reaction solution II at another temperature for a period of time to obtain a reaction solution III; (e) recovering the organic solvent from the reaction solution III under high temperature and vacuum conditions to obtain a phenolic epoxy resin with a high softening point and high epoxy equivalent.

2. The method for preparing a high softening point high equivalent weight epoxy resin according to claim 1, characterized in that: The organic solvent in step (a) is one or more of toluene, 1,4-dioxane, isopropanol, methyl isobutyl ketone, xylene and n-butanol.

3. The method for preparing a high softening point high equivalent weight epoxy resin according to claim 1, characterized in that: The novolac epoxy resin in step (a) includes phenol novolac epoxy resin, bisphenol A novolac epoxy resin, and o-cresol novolac epoxy resin.

4. The method for preparing a high softening point high equivalent weight epoxy resin according to claim 1, characterized in that: The phenolic resin in step (b) includes phenolic resin, bisphenol A phenolic resin, o-cresol resin, bisphenol A, and bisphenol F.

5. The method for preparing a high softening point high epoxy equivalent phenolic epoxy resin according to claim 1, characterized in that: In steps (a) and (b), the following weight proportions of phenolic epoxy resin, organic solvent and phenolic resin are used: 100 parts of phenolic epoxy resin; 10-50 parts of organic solvent; 3~20 parts of phenolic resin.

6. The method for preparing a high softening point high epoxy equivalent phenolic epoxy resin according to claim 1, characterized in that: In step (c), the catalyst is one of 2-methylimidazole, 2-ethyl, 4-methylimidazole, triphenylphosphine, butyltriphenylphosphine bromide, etc., and the weight ratio of the added amount to the phenolic resin is: catalyst: phenolic resin = (1-10): 100, the reaction temperature is 100-120°C, and the reaction time is 1-4 hours.

7. The method for preparing a high softening point high equivalent weight epoxy resin according to claim 1, characterized in that: In step (d), the temperature is 150-180°C and the reaction time is 1-4 hours.

8. The method for preparing a high-softening-point high-equivalent phenolic epoxy resin according to claim 1, characterized in that: In step (e), the organic solvent recovery temperature is 160° C. and the vacuum pressure is <3 KPa.

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