TW202219030A - Accelerator for controlling curing reaction time and temperature of vinyl ester resin and preparation method thereof capable of controlling the time and temperature of the curing reaction of vinyl ester resin by using the unique steric effect and electronic properties of an aniline derivative of an accelerator - Google Patents

Abstract

The present invention provides a new type of accelerator, which can control the time and temperature of the curing reaction of vinyl ester resin by using the unique steric effect and electronic properties of the aniline derivative of the accelerator alone. The present invention further provides a method for producing the accelerator.

Description

A kind of accelerator to control the curing reaction time and temperature of vinyl ester resin Feed and method of making the same

The present invention relates to an accelerator and its preparation method, in particular to an accelerator for controlling the curing reaction time and temperature for forming vinyl ester resin and its preparation method.

The application of the international unsaturated polyester/vinyl ester market is concentrated in building materials and transportation/ships, with an output value of 1.5 billion US dollars in 2014. The domestic market is distributed in perfusion, plastic shell, soil filling, buttons, FRP, ships, winding, decorative panels, artificial stone and SMC/BMC, etc. Both types of resins need to be started by adding hardeners and accelerators during hardening molding, but the heat release and reaction speed need to be controlled if large/thick shell workpieces are to be poured.

The curing of vinyl ester resin is generally guided by the peroxide curing agent MEKPO and cobalt salt. The peroxide first reacts with cobalt to generate free radicals, and the free radicals then undergo a free radical copolymerization reaction with the double bond in the vinyl ester. The commonly used curing agent is an organic peroxide such as MEKPO, and the cobalt accelerator is generally a cobalt salt, commonly used are cobalt octoate and cobalt oxalate.

In the curing of vinyl esters, initiators and accelerators must be used, and then the reaction solvent styrene and vinyl ester monomers are cross-linked into a network structure (curing) by free radical reaction. The two most commonly used organic peroxides, Methyl Ethyl Ketone Both Peroxide (MEKPO) and Bezoyl peroxide (BPO) can be used as initiators. Since the free radical reaction will be accompanied by a large amount of heat, when the workpiece is too large, the heat will accumulate and cause defects to fail.

The previous technology is to coat the fiber with resin, and then complete the preparation of the composite material through the curing of the resin. In this technology, the curing of the resin is only adjusted by the proportion of retarder or curing agent to control the time when curing starts. However, vinyl ester curing uses free radical reaction cross-linking, the reaction speed is fast and a large amount of reaction heat is released; once curing When it begins to occur, the temperature will rise rapidly, and the rate of temperature change will be out of the control of the ratio of retarder or curing agent, so the previous technology cannot improve the problem of too fast temperature change.

Therefore, at present, the industry needs chemical substances or methods to control the exothermic temperature and reaction speed of the vinyl ester curing reaction in order to control the quality of the vinyl ester workpieces.

In view of the shortcoming of the above-mentioned prior art, the main purpose of the present invention is to form a new type of accelerator by regulating the electron and steric effect of the substituent on the accelerator to control the generation of free radicals in the presence of peroxide in the vinyl ester maturation reaction and curing temperature kinetics.

Another object of the present invention is to provide novel accelerators for controlling free radical polymerization of vinyl ester systems, with or without polymeric inhibitors, using novel accelerators to control the heat release and rate in the presence of peroxides.

In order to achieve the above purpose, according to a scheme proposed by the present invention, A kind of accelerator is provided, which is a cyclobutane tetraester compound, and has the structure of formula (I):

Wherein, R1 is alkyl or cycloalkyl; R2 is alkyl or cycloalkyl; R3, R4, R5, R6, R7 are one of hydrogen, electron withdrawing group or electron pushing group, among which, electron withdrawing group The group and the electron-pushing group do not exist in R3, R4, R5, R6, and R7 at the same time.

In the above, the substituents R1 and R2 of the amino group of the amino group in the formula (I) have the following structures:

In the above, the alkyl group is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, di-sec-butyl, and tert-butyl, and the cycloalkyl group is selected from pyrrolidinyl or piperidinyl, cyclopentyl A group consisting of alkane and cyclohexane.

Among the above, the electron withdrawing group is selected from the group consisting of NO ₂ , CN, F, COOH, Cl, Br, and I.

In the above, the electron-pushing group is selected from the group consisting of (CH ₃ ) ₃ C, (CH ₃ ) ₂ CH, and CH ₃ CH ₂ .

The present invention also proposes a method for making an accelerator, wherein the accelerator has the following structure:

The steps include: (a) pouring bromofluorobenzene and isopropylamine into a bottle and slowly adding potassium tert-butoxide to mix; (b) heating the mixed solution to reflux, and then filtering to remove potassium tert-butoxide after cooling to room temperature (c) isopropylamine and tert-butanol are taken out by the mode of underpressure distillation by the filtered liquid again; (d) after the layering in the bottle is taken the organic phase and add water extraction and wash until the organic layer is not turbid, then The organic layer is dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to remove excess solvent. Finally, the concentrated organic layer is vacuum distilled to remove excess reactant bromofluorobenzene to obtain a promoter.

The present invention further provides a thermosetting resin polymerization initiating system, comprising a peroxide-containing initiator and an accelerator as described in formula 1.

In the above, the thermosetting resin system is vinyl ester resin, and the peroxide initiator system is dibenzyl peroxide.

The novel accelerator of the present invention can regulate the free radical reaction mechanism, and can control the whole process of the vinyl ester resin curing reaction to be below 160° C. and the reaction time is not more than 100 minutes, so as to improve the defect caused by the accumulation of heat when the workpiece is too large Disadvantage of failure.

The above summary, the following detailed description and the accompanying drawings are all for the purpose of further illustrating the manner, means and effect adopted by the present invention to achieve the predetermined object. The other objects and advantages of the present invention will be explained in the following descriptions and drawings.

S101~S104: Steps

The first figure is a flow chart of the preparation method of the accelerator of the present invention;

The second figure is a graph showing the relationship between the temperature and time of polymer polymerization when DMA, N-Et-N-Meaniline and DEA are used as accelerators in the present invention;

The third figure is the relationship between DEA and N-iPr-N-Meaniline of the present invention as accelerators, and the temperature and time of polymer polymerization;

The fourth figure is a graph showing the relationship between the temperature and time of polymer polymerization when N-iPr-N-Meaniline, N-Et-N-iPraniline and N,N-diisopropylaniline are used as accelerators in the present invention;

The fifth figure is a diagram of a sample of polymer polymerization as DMA of the present invention as an accelerator;

The sixth figure is a diagram of the polymer polymerization sample of N-iPr-N-Meaniline of the present invention as an accelerator;

Figure 7 is a diagram of a sample of polymer polymerization using N,N-diisopropylaniline as an accelerator of the present invention.

The following describes the implementation of the present invention by means of specific specific examples In this way, those skilled in the art can easily understand the advantages and effects of the present invention from the contents disclosed in this specification.

A novel accelerator of the present invention is a method for controlling the time and temperature of the aging reaction of vinyl ester resin by using the unique steric effect and electronic properties of the aniline derivative of the accelerator alone.

The present invention provides a kind of accelerator, this accelerator is cyclobutane tetraester compound, has the structure such as formula (I):

其中，R1為烷基或環烷基；R2為烷基或環烷基；R3、R4、R5、R6、R7分別為氫、拉電子基團或推電子基團其中之一，其中，拉電子基團及推電子基團不同時存在於R3、R4、R5、R6、R7中。

Wherein, R1 is alkyl or cycloalkyl; R2 is alkyl or cycloalkyl; R3, R4, R5, R6, R7 are hydrogen, electron withdrawing group or electron pushing group, respectively, wherein, electron withdrawing group The group and the electron-pushing group do not exist in R3, R4, R5, R6, and R7 at the same time.

Please refer to the first figure, which is a flow chart of the production method of the accelerator of the present invention, and its steps include: (a) pouring bromofluorobenzene and isopropylamine into a bottle and slowly adding potassium tert-butoxide to mix; (b) mixing The liquid is heated to reflux, and the potassium tert-butoxide is removed by filtration after being lowered to room temperature; (c) isopropylamine and tert-butanol are taken out of the filtered liquid by distillation under reduced pressure; (d) the stratification in the bottle is taken out. After taking the organic phase and washing with water until The organic layer is not cloudy, then the organic layer is dried with anhydrous magnesium sulfate and filtered, and the excess solvent is removed by concentration under reduced pressure. Finally, the concentrated organic layer is vacuum distilled to remove the excess reactant bromofluorobenzene. agent, the accelerator prepared by the present invention has the following structure:

Generally, when BPO is used as a free radical polymerization initiator, its reaction temperature is about 60-80 °C to promote BPO to undergo O-O bond and homolytic cleavage to generate free radicals. When an accelerator is added to the reaction system, the redox reaction (redox) can be carried out at low temperature to generate free radicals, and the polymer polymerization reaction can be carried out at room temperature.

From the reaction mechanism of BPO and DMA accelerator, it can be speculated that the steric effect of the substituents of the amino group of the accelerator is sufficient to affect the rate of the polymerization reaction. Therefore, we designed and synthesized novel accelerators N-Ethyl-N-methylaniline(I-a), N,N-diethylaniline with different steric barriers/electronic effects. (DEA)(I-b), N-isopropyl-N-methylaniline(I-c), N-ethyl-N-isopropylaniline(I-d), N,N-diisopropylaniline(I-e), para-N,N-diisopropylfluoroaniline(I-f), meta -N,N-diisopropylfluoroaniline (I-g).

In general vinyl ester polymerization, the free radical (Radical) is generated by the added Peroxide (BPO in this example) and the initiator (Initiator, DMA in this example), due to the substitution of the accelerator amino group (amino group) The steric effect is sufficient to influence the rate of the polymerization reaction. Therefore, we synthesize different sterically hindered substituent promoters of formula (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g) and observe their effects on the polymerization reaction rate and reaction temperature. .

Example 1 Synthesis of N-Et-N-Meaniline (I-a): Take a 150-ml round-neck flask, under a nitrogen atmosphere, add N-methylaniline (N-methylaniline, 10 g, 1 equiv.) and 1.2 equiv. bromoethane, and heated to reflux for 8 hours. After the reaction, it was extracted three times with an aqueous sodium hydroxide solution and dichloromethane, the organic layer was dewatered with anhydrous magnesium sulfate, concentrated under reduced pressure to remove the dichloromethane, and then carried out column chromatography (SiO 0.045-0.075mm, EA/Hexane=1:40).

Example 2 Synthesis of N,N-diethylaniline (I-b): Take a 150 ml round-neck flask, add aniline (10 g, 1 equivalent) and 2.2 equivalents of bromoethane under a nitrogen atmosphere, And heated to reflux for 8 hours. After the reaction, it was extracted three times with an aqueous sodium hydroxide solution and dichloromethane, the organic layer was dewatered with anhydrous magnesium sulfate, concentrated under reduced pressure to remove the dichloromethane, and then carried out column chromatography (SiO 0.045-0.075mm, EA/Hexane=1:25).

Example 3 Synthesis of N-iPr-N-Meaniline (I-c): Take a 150-ml round-neck flask, under a nitrogen atmosphere, add N-methylaniline (N-methylaniline, 10 g, 1 equiv.) and 1.2 equiv. 2-bromopropane and heated to reflux for 18 hours. After the reaction, extract three times with aqueous sodium hydroxide solution and dichloromethane, dewater the organic layer with anhydrous magnesium sulfate, concentrate under reduced pressure to remove dichloromethane, and then carry out column chromatography (SiO2 0.045-0.075mm, EA /Hexane=1:40).

Example 4 Synthesis of N-ethyl-N-isopropylaniline (I-d): Take a 150 ml round-neck flask, add N-ethylaniline (N-ethylaniline) under a nitrogen atmosphere ethylaniline, 10 g, 1 equiv) and 1.2 equiv of 2-bromopropane and heated to reflux for 18 hours. After the reaction, extract three times with aqueous sodium hydroxide solution and dichloromethane, dewater the organic layer with anhydrous magnesium sulfate, concentrate under reduced pressure to remove dichloromethane, and then carry out column chromatography (SiO2 0.045-0.075mm, EA /Hexane=1:40).

Example 5 Synthesis of N-diisopropylaniline (I-e): Take a 250 ml round-necked flask, add bromobenzene (22.5 g, 1 equivalent) and 4 equivalents of diisopropylamine under a nitrogen atmosphere and 2.8 equivalents of potassium tert-butoxide (potassium tert-butoxide), and heated to reflux for 2-3 days. After the reaction, the unreacted diisopropylamine was removed by concentration under reduced pressure, neutralized with an aqueous hydrogen chloride solution and extracted three times with diethyl ether, and the aqueous layer was taken, and then the aqueous layer was basified with an aqueous sodium hydroxide solution. , extracted three times with diethyl ether, the organic layer was dewatered with anhydrous magnesium sulfate, and then concentrated under reduced pressure to remove diethyl ether to obtain the product.

Example 6 Synthesis of para-N,N-diisopropylfluoroaniline(I-f), meta-N,N-diisopropylfluoroaniline(I-g): Preparation of 1:1 m-fluoroisopropyl with bromofluorobenzene, potassium tert-butoxide and isopropylamine A mixture of aniline and p-fluoroisopropylaniline N,N-diisopropylfluoroaniline and diisopropylaniline, pour 70mL of 4-Bromofluorobenzene and 360mL of Diisopropylamine into a bottle, slowly add 200g of t-buOK and stir, then heat to reflux at 140~150℃, when After the reaction solution was cooled to room temperature, t-buOK was removed by filtration, and diisopropylamine and tBuOH were taken out of the filtered liquid by distillation under reduced pressure. At this time, the bottle was layered. The organic layer was not cloudy, and then the organic layer was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to remove excess solvent. Finally, the concentrated organic layer was vacuum distilled to remove excess reactant 4-Bromofluorobenzene to obtain Mixtures of m-fluoroisopropylaniline (I-g) and p-fluoroisopropylaniline (I-f).

Example 8: 150 g of vinyl ester (Mono) and 3 g of BPO were added to the accelerators listed in the table below for vinyl ester curing, and the effects of various sterically hindered substituent accelerators on the polymerization reaction rate and reaction temperature were observed.

Please refer to Figure 2. Figure 2 shows the relationship between the temperature and time of polymer polymerization with DMA, N-Et-N-Meaniline and DEA as accelerators. It can be seen from the figure that DMA and N-Et-N- When Meaniline is used as an accelerator, the polymerization temperature rises to 132-133°C, and the highest temperature is about 6.3 minutes after mixing. The experimental results show that when the amine groups on the accelerator are two methyl groups or one methyl-ethyl group, the reaction rate and reaction temperature have no effect. When the substituent was two ethyl groups, the maximum reaction temperature was 130°C. Although similar to the previous experiment, the maximum reaction temperature was extended to 11 minutes (closer to twice as fast). This result clearly shows that when the accelerator When the amine group on it has a large steric hindrance, it can extend Slow the onset rate of polymerization.

Please refer to Figure 3. Figure 3 shows the relationship between DEA and N-iPr-N-Meaniline as accelerators, and the temperature and time of polymer polymerization. Compare the amine groups on the accelerator as two ethyl groups and the introduction of isopropyl At the base time, the time to reach the maximum reaction temperature can be extended to 11.8 minutes. Although the time was extended again, the time at the maximum reaction temperature did not extend further, probably because the other substituent was methyl, and the steric hindrance did not increase too much. Overall, the amine groups on the accelerator will affect the rate of the initial reaction.

Please refer to Figure 4, Figure 5, Figure 6 and Figure 7. Figure 4 shows the temperature and The relationship of time, Figure 5 shows DMA as accelerator and polymer polymerization sample, Figure 6 shows N-iPr-N-Meaniline as accelerator, polymer polymer sample, Figure 7 shows N,N -diisopropylaniline is used as accelerator, the sample diagram of polymer polymerization, it can be seen from the above figure 3 that when the amine group on the accelerator is introduced into the isopropyl group, the time to reach the maximum reaction temperature can be prolonged, so a larger steric barrier substituent is further introduced , observe its effect on the time it takes to reach the maximum reaction temperature. It can be seen from Figure 4 that when N,N-diisopropylaniline is used as the accelerator, the time for reaching the maximum reaction temperature can be extended to 37.3 minutes. In addition to the temperature and time, it can be clearly seen from Figure 5, Figure 6 and Figure 7 that the polymer is relatively free of white cracks. This phenomenon is most likely because the rate of polymerization of the accelerator with less steric hindrance is too fast, A Hot Spot was generated, resulting in popcorn polymerization. Therefore, increasing the steric hindrance of the substituent on the amine group of the accelerator can not only reduce the reaction rate, but also improve the polymerization quality of the polymer.

Among the above, N,N-Diisopropylaniline with the largest steric effect is the most effective, which can regulate the polymerization reaction rate and reaction temperature of vinyl ester with BPO initiator, and can perfectly produce the polymerized product under the correct equivalent.

The cost of the accelerator of the present invention is low, and it can be directly applied to the existing unsaturated polyester/vinyl ester market, and can also be applied to the special market with high demand for thickness control.

The accelerators of the present invention can control the thermosetting properties of vinyl ester resins, especially with a positive (positive) effect on time and/or temperature. This is controlled by the unique steric effects and electronic properties of aniline derivatives alone, enabling good peroxide polymerization.

In the present invention, a new type of accelerator is developed to regulate the free radical reaction mechanism. It is hoped that the whole process of the curing reaction should be controlled below 160 °C and the reaction time should not exceed 100 minutes. The reaction temperature (100 °C ~ 160 °C) The reaction is not complete, and the workpiece will be overheated and deformed when the temperature is higher than 160 °C.

The above-mentioned embodiments are merely illustrative of the features and effects of the present invention, and are not intended to limit the scope of the essential technical content of the present invention. Any person skilled in the art can make modifications and changes to the above embodiments without departing from the spirit and scope of the invention. Therefore, the protection scope of the right of the present invention should be as follows The scope of the patent application is listed.

Claims (8)

A kind of accelerator, this accelerator is cyclobutane tetraester compound, has following structure:

Wherein, R1 is alkyl or cycloalkyl; R2 is alkyl or cycloalkyl; R3, R4, R5, R6, R7 are hydrogen, electron withdrawing group or electron pushing group, respectively, wherein, electron withdrawing group and electron pushing group are not present in R3, R4, R5, R6, R7 at the same time middle. The accelerator as described in item 1 of the claimed scope, wherein the substituents R1 and R2 of the amine group have the following structures:

The accelerator according to claim 1, wherein the alkyl group is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, di-sec-butyl, tert-butyl, cycloalkyl Selected from the group consisting of pyrrolidinyl or piperidinyl, cyclopentane, cyclohexane. The accelerator according to claim 1, wherein the electron withdrawing group is selected from the group consisting of NO ₂ , CN, F, COOH, Cl, Br, and I. The accelerator according to claim 1, wherein the electron-pushing group is selected from the group consisting of (CH ₃ ) ₃ C, (CH ₃ ) ₂ CH, and CH ₃ CH ₂ . A preparation method of an accelerator, wherein the accelerator has the following structure:

The steps include: (a) bromofluorobenzene and isopropylamine are poured into the bottle and slowly add potassium tert-butoxide to mix; (b) the mixed solution is heated to reflux, and then filtered to remove potassium tert-butoxide after being lowered to room temperature; (c) isopropylamine and tert-butanol are taken out by the mode of underpressure distillation with the filtered liquid again; (d) Take the organic phase from the layers in the bottle and add water to extract and wash until the organic layer is not cloudy, then dry the organic layer with anhydrous magnesium sulfate, filter, and concentrate under reduced pressure to remove excess solvent, and finally concentrate the The organic layer is subjected to vacuum distillation to remove excess reactant bromofluorobenzene to obtain the accelerator. A thermosetting resin polymerization initiating system, comprising a peroxide-containing initiator and an accelerator as described in Patent Scope 1. The thermosetting resin polymerization initiating system as described in Patent Scope 7, wherein the thermosetting resin is vinyl ester resin, and the peroxide initiator is dibenzoyl peroxide.

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