CN114573773B - Method for preparing modified high-ortho cresol-formaldehyde resin by condensation of amines and aldehydes - Google Patents

Abstract

The invention relates to the technical field of phenolic resin products, in particular to a method for preparing modified high-ortho-cresol formaldehyde resin by adopting amine and aldehyde condensation. Firstly, synthesizing high-ortho-cresol formaldehyde resin by adopting a double-catalyst method, and then introducing amine containing amino groups and aldehydes containing long chains into the synthesized high-ortho-cresol formaldehyde resin by chemical grafting. After thermal weight loss test, the residual rate of the modified high-ortho-position o-cresol formaldehyde resin synthesized by the invention is higher than that of unmodified resin at 300 ℃ and 600 ℃, the modified high-ortho-position o-cresol formaldehyde resin has higher thermal stability, and meanwhile, the toughness of the modified high-ortho-position o-cresol formaldehyde resin is obviously improved through friction material test. And the method has simple process and wide application range, and is suitable for industrial production.

Description

Method for preparing modified high-ortho cresol-formaldehyde resin by condensation of amines and aldehydes

technical field

The invention relates to the technical field of phenolic resin products, in particular to a method for preparing modified high-ortho cresol aldehyde resin by condensation of amines and aldehydes.

Background technique

O-cresol phenolic resin has the characteristics of easy availability of raw materials, convenient synthesis, manufacturability, excellent thermal performance and electrical insulation performance, and has been widely used in the fields of electronics, fireproof coatings, refractory materials, aerospace vehicles and advanced composite materials.

The synthesis of high-ortho phenolic resin is mainly obtained by polycondensation reaction of phenol and aldehyde under the condition of divalent metal oxide or hydroxide or its salt as a catalyst. In U.S. Patent No. 4,097,463, divalent metal salts are used as catalysts. Under the condition of pH 4-7, xylene is used as solvent. At 140-160 ° C, the reaction temperature is higher than that of ordinary thermoplastic phenolic resins, and high ortho position is obtained. Phenolic resin, but the high ortho phenolic resin obtained by this method has a high content of free phenol and is prone to gelation. In U.S. Patent No. 4,299,947, a two-step method is used to react with a lower aldehyde-phenol molar ratio (0.6-0.8), and the pH value of the reaction system is adjusted to 1-5 by acid to obtain a high-ortho-position phenolic resin, but free The phenol is still high, and the heat resistance is reduced.

With the development of industry, the modification of phenolic resin has never stopped in order to meet the constantly updated needs of high-tech fields such as automobiles, electronics, aerospace and national defense. After years of unremitting efforts, researchers have developed many modified phenolic resins with different properties to meet the different application requirements of various industrial sectors. However, its cured product has high water absorption, high brittleness, and weak mechanical properties, which can no longer fully meet the requirements of modern society for high-performance composite materials. Therefore, it needs to be modified to obtain excellent heat resistance; improve flexibility and overcome its brittleness Larger weakness, improved mechanics.

Amines are weakly basic, and amine groups are reductive and easily oxidized by strong oxidants. The current method of modifying o-cresol resin with amines still has the following problems: using amines alone to modify the resin is prone to the risk of gelation. Moreover, the phenolic resin modified by amine alone has obvious brittleness and limited application range.

Contents of the invention

Based on the technical problems pointed out in the background technology section, the present invention proposes a method for preparing modified high-ortho cresol aldehyde resin by condensation of amines and aldehydes, using amines and aldehydes to react first, and adopting the method of dropping Adding it to the high-ortho-ortho-cresol aldehyde resin to prepare the modified high-ortho-ortho-cresol aldehyde resin successfully avoids the risk of gelation and can significantly improve the flexibility, heat resistance and storage stability of the phenolic resin. In addition, the present invention The process is simple and suitable for industrialized production.

The method for preparing modified high-ortho cresol-formaldehyde resin by condensation of amines and aldehydes comprises the following steps:

(1) add o-cresol, paraformaldehyde, the first catalyzer in the stirred reactor in proportion, heat up and keep warm and react, then add the second catalyzer, continue keep warm and react;

Wherein, the molar ratio of paraformaldehyde and o-cresol is controlled at 0.75-0.95, and the first catalyst is one of zinc acetate, calcium acetate, or magnesium oxide; and the mass ratio of the first catalyst and o-cresol is controlled at 1%. -3%; the heat preservation reaction time is 2-4h, and the reaction temperature is 90-110°C; the preferred reaction temperature is 95-105°C, and the heat preservation reaction time is 2-3h.

The second catalyst is one or a mixture of oxalic acid or p-toluenesulfonic acid, the mass ratio of the second catalyst to o-cresol is controlled between 0.5%-2%; the holding time is 2-4h, and the temperature is 90- 110°C.

(2) Add a solvent to dissolve the reaction product of the above step (1), wash off the precipitate with deionized water at 80-90°C, and wash until neutral; heat and dehydrate at normal pressure until no water flows out, and then dephenolize under reduced pressure To 190-200°C, product A is obtained; product A drops to about 90-110°C, add solvent again to dissolve the product;

Wherein, the solvent is one of methyl isobutyl ketone (MIBK), a mixture of acetone and butanol. And the mass ratio of the solvent to the o-cresol novolac resin is 0.5-1.

The external temperature of normal pressure dehydration is 150-170°C, the vacuum degree of vacuum dephenolation is above -0.09Mpa, the dehydration temperature is 190-200°C, and the maintenance time is 1-3h.

(3) In addition, amines and aldehydes are heated to react to obtain product B;

The amine is p-phenylenediamine, a kind of aniline, and the aldehyde is a kind of butyraldehyde, furfural or isobutyraldehyde. And the molar ratio of aldehydes to amines is 1.4-1.6, the pre-reaction time is 0.5-2h, and the temperature is 60-80°C.

(4) Add oxalic acid into the three-necked bottle containing the dissolved product A, and then drop the product B into the bottle by adding drops. After 0.5-2 hours, the temperature is 90-110°C. After the drop, 90- Reaction at 110°C for 1-4 hours; dehydration at normal pressure until no water flows out to obtain a high-ortho cresol resin modified by p-phenylenediamine and butyraldehyde.

The molar ratio of oxalic acid to amines is 0.1-0.2; the mass ratio of product B to product A is 0.2-0.5; the dropping time is preferably 1-2h, the temperature is preferably 95-105°C, and the heat preservation reaction temperature is preferably 95-105 °C, the time is preferably 1.5-2.5h.

The present invention adopts the condensation method of amines and aldehydes to prepare modified high-ortho-ortho-cresol aldehyde resins. The amines and aldehydes are heated up for pre-reaction, and then dripped into the high-ortho-ortho-cresol aldehyde resins in a dropwise manner. The amine groups on the class and the long chains on the aldehydes are incorporated into the high-ortho-ortho-cresol aldehyde resin, which changes the toughness and heat resistance of the resin, and obtains the amine-aldehyde modified high-ortho-ortho-cresol aldehyde resin.

Compared with the prior art, the present invention mainly has the following advantages:

(1) The long chains of amine groups and aldehydes of the present invention are grafted onto the high-ortho-ortho-cresol phenolic resin, the product performance is stable, and the phenolic resin has excellent flexibility and heat resistance.

(2) The modifying agent of the present invention is aldehydes and amines containing long chains, and the aldehydes and amines used are widely used, and no special modification is required.

(3) The present invention adopts the mode of dropping to add in high ortho cresol aldehyde resin, has prevented gel.

Due to the reaction between amines and aldehydes, on the one hand, the product contains long chains of aldehydes, which can modify high-ortho cresol resins, reduce their crosslinking density, and improve their toughness; Amino groups can also be successfully incorporated into high-ortho cresol resins, thereby improving the heat resistance of phenolic resins.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present invention, preferred embodiments of the present invention will be described below in conjunction with specific examples, but it should not be construed as a limitation of the present invention.

The test methods or test methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, are obtained from conventional commercial channels or prepared by conventional methods.

The polycondensation reaction formula is as follows:

The pre-reaction reaction formula is as follows:

The final reaction formula is as follows:

Example 1

Put 1000kg of preheated and melted o-cresol into the high-level metering tank with a special pump, and then add 236kg of paraformaldehyde and 100kg of zinc acetate into the reaction kettle A, heat up to 105°C and keep it warm for 2 hours, and add 100kg of oxalic acid at the end of the heat preservation , continue to keep warm for 3 hours, add solvent MIBK 800kg to dissolve the resin at the end of the keep warm, add hot deionized water at 90°C and stir, pour into the funnel, wash with water several times until neutral. Then dehydrate under normal pressure to 160°C, then remove phenol and solvent under reduced pressure, and the vacuum degree is above -0.09Mpa. After dehydration to 195°C, stop the reaction for 2 hours, then cool down to 100°C, and add 800kg of MIBK to dissolve the resin. Add 100kg of p-phenylenediamine into another high-level metering tank, meter it into the reactor B, then add 150kg of butyraldehyde, raise the temperature to 80°C and keep it warm for 2 hours, and release the product after the keep warm. Add 220 kg of oxalic acid into reactor A, drop the product of p-phenylenediamine and butyraldehyde into reactor A in the form of dropwise addition, and finish the dropwise addition within 2 hours, keeping the temperature at 100°C. After the dropwise addition, keep the temperature for 3 hours, then dehydrate under normal pressure to 160°C, stop the reaction, release the product, and obtain 1442kg of yellow-brown solid resin after cooling.

Example 2

Put 1000kg of preheated and molten o-cresol into the high-level metering tank with a special pump, and then add 236kg of paraformaldehyde and 150kg of calcium acetate, heat up to 95°C and keep it warm for 3 hours, and add p-toluenesulfonate at the end of the heat preservation Acid 100kg, continue to keep warm for 3h, add solvent MIBK700kg to dissolve the resin at the end of the keep warm, add 90°C hot deionized water to stir, pour into the funnel, wash with water several times until neutral. Then dehydrate under normal pressure to 160°C, then remove phenols and solvents under reduced pressure, the vacuum degree is above -0.09Mpa, stop the reaction after dehydration to 195°C for 2 hours, then cool down to 110°C, add 800kg MIBK to dissolve the resin. Add 100kg of aniline into another high-level metering tank, meter it into the reactor B, then add 150kg of furfural, raise the temperature to 70°C and keep it warm for 2 hours, and release the product after the keep warm. Add 220kg of oxalic acid into reactor A, drop the product of aniline and furfural into reactor A in the form of dropwise addition, finish the dropwise addition within 2 hours, and keep the temperature at 110°C. After the dropwise addition, keep the temperature for 3 hours, then dehydrate under normal pressure to 160°C, stop the reaction, release the product, and obtain 1630kg of yellow-brown solid resin after cooling.

Example 3

Put 1000kg of preheated and melted o-cresol into the high-level metering tank with a special pump, and then add 250kg of paraformaldehyde and 150kg of zinc acetate into the reaction kettle A, raise the temperature to 105°C and keep it warm for 3 hours, and add 100kg of oxalic acid at the end of the heat preservation , continue to keep warm for 3h, add 450kg of solvent acetone and 350kg of butanol to dissolve the resin at the end of the keep warm, add hot deionized water at 90°C and stir, pour into the funnel, wash with water several times until neutral. Then dehydrate under normal pressure to 160°C, then remove phenol and solvent under reduced pressure, the vacuum degree is above -0.09Mpa, stop the reaction after dehydration to 195°C for 2 hours, then cool down to 100°C, add 400kg of acetone and 400kg of butanol to dissolve the resin . Add 110kg of aniline into another high-level metering tank, meter it into the reactor B, then add 165kg of isobutyraldehyde, raise the temperature to 70°C and keep it warm for 3 hours, and release the product after the keep warm. Add 220 kg of oxalic acid into reactor A, drop the product of p-phenylenediamine and isobutyraldehyde into reactor A in the form of dropwise addition, finish the dropwise addition within 1.5 hours, and keep the temperature at 100°C. After the dropwise addition, keep the temperature for 4 hours, then dehydrate under normal pressure to 160°C, stop the reaction, release the product, and obtain 1634kg of yellow-brown solid resin after cooling.

Example 4

Put 1000kg of preheated and molten o-cresol into the high-level metering tank with a special pump, and then add 250kg of paraformaldehyde and 200kg of zinc acetate, heat up to 100°C and keep it warm for 3 hours, and add p-toluenesulfonate at the end of the heat preservation Acid 150kg, continue to keep warm for 3h, add 700kg of solvent MIBK to dissolve the resin at the end of the keep warm, add 90°C hot deionized water to stir, pour into the funnel, wash with water for many times until neutral. Then dehydrate under normal pressure to 160°C, then remove phenols and solvents under reduced pressure, the vacuum degree is above -0.09Mpa, stop the reaction after dehydration to 195°C for 2 hours, then cool down to 110°C, add 800kg MIBK to dissolve the resin. Add 100kg of p-phenylenediamine into another high-level metering tank, meter it into the reaction kettle, then add 150kg of butyraldehyde, raise the temperature to 70°C and keep it warm for 3 hours, and release the product after the keep warm. Add 220kg of oxalic acid into the first reactor, drop the product of p-phenylenediamine and butyraldehyde into the first reactor in the form of dropwise addition, finish the dropwise addition within 2 hours, and keep the temperature at 100°C. After the dropwise addition, keep the temperature for 3 hours, then dehydrate under normal pressure to 160°C, stop the reaction, release the product, and obtain 1766kg of yellow-brown solid resin after cooling.

Comparative example 1

Put 1000kg of preheated and molten o-cresol into the high-level metering tank with a special pump, and then add 236kg of paraformaldehyde and 100kg of zinc acetate, heat up to 105°C and keep it warm for 2 hours, and add 100kg of oxalic acid after the heat preservation is over. Continue to keep warm for 3 hours, add solvent MIBK 800kg to dissolve the resin, add 90°C hot deionized water to stir, pour into the funnel, and wash with water several times until neutral. Then dehydrate under normal pressure to 160°C, then remove phenol and solvent under reduced pressure, the vacuum degree is above -0.09Mpa, and stop the reaction after dehydration to 195°C for 2 hours, and obtain 1063kg of light yellow transparent solid resin after cooling.

Comparative example 2

Put 1000kg of preheated and molten o-cresol into the high-level metering tank with a special pump, and then add 100kg of p-phenylenediamine, 236kg of paraformaldehyde, and 100kg of zinc acetate, heat up to 105°C and keep it warm for 2 hours. At the end of the heat preservation, add 100kg of oxalic acid, and continue the heat preservation for 3 hours. After the heat preservation, add 800kg of solvent MIBK to dissolve the resin. Then dehydrate under normal pressure to 160°C, then remove phenol and solvent under reduced pressure, and the vacuum degree is above -0.09Mpa. After dehydration to 195°C, the reaction is stopped for 2 hours, and the product is released. After cooling, 1078kg of yellow solid resin is obtained.

Comparative example 3

Put 1000kg of preheated and melted o-cresol into the high-level metering tank with a special pump, and measure it into the reactor, then add 150kg of butyraldehyde, 236kg of paraformaldehyde, and 100kg of zinc acetate. Add 100kg of oxalic acid, continue to keep warm for 3h, add 800kg of solvent MIBK to dissolve the resin at the end of the keep warm, add 90°C hot deionized water to stir, pour into the funnel, wash with water for many times until neutral. Then dehydrate under normal pressure to 160°C, then remove phenol and solvent under reduced pressure, the vacuum degree is above -0.09Mpa, and stop the reaction after dehydration to 195°C for 2 hours, and obtain 1063kg of light yellow transparent solid resin after cooling.

The yellowish-brown transparent resin obtained in Example 1 of the present invention (the high ortho-orthocresol resin modified by p-phenylenediamine and butyraldehyde), and the solid resin obtained in Comparative Example 1 to Comparative Example 3 are tested for performance, and the test results As shown in Table 1:

Table 1 embodiment and comparative example o-cresol resin performance test

Phenolic Resin Softening point/℃ Ju speed/s Viscosity/P Free phenol/% molecular weight Example 1 85 55 1.356 1.3 Mn=785, Mw=5447, d=8.21 Comparative example 1 88 49 1.488 1.5 Mn=735, Mw=2561, d=3.48 Comparative example 2 89 56 1.621 1.6 Mn=705, Mw=1760, d=2.49 Comparative example 3 90 58 1.712 1.4 Mn=745, Mw=1860, d=2.68

As can be seen from the above table, the softening point of the resin will decrease to a certain extent, and the ratio of Mw to Mn of the amines and aldehydes chemically modified high-ortho cresol-formaldehyde resin of the present invention is higher than that of the physical mixed resin. This is because the amines The long chains of amino groups and aldehydes are grafted with o-cresol, which increases the proportion of high molecular weight resin in the resin system. The above shows that the long chain of butyraldehyde, p-phenylenediamine and phenol are chemically grafted and introduced into the phenolic resin chain.

The yellowish-brown transparent resin obtained in the embodiment of the present invention 1 (using p-phenylenediamine and butyraldehyde modified high ortho cresol resin), the solid resin obtained in comparative example 1 to comparative example 3 and the thermal weight loss test are carried out, wherein The resin of Example 1 was cross-linked and cured at 250° C. by adding 3% dodecylbenzenesulfonic acid for 2 hours. The resins of Comparative Examples 1 to 3 were cross-linked and cured by adding 5% tropane. The test results are shown in Table 2:

Table 2 embodiment and comparative example phenolic resin thermal weight loss test

Phenolic Resin 300℃ residual rate/% 600℃ residual rate/% Example 1 92.3 54.8 Comparative example 1 90.1 51.5 Comparative example 2 90.6 51.8 Comparative example 3 90.2 51.3

As can be seen from Table 2, the high-temperature stability of amines and aldehydes condensation-modified high-ortho-orthocresol-formaldehyde resin embodiment 1 of the present invention is higher than comparative examples 1, 2 and 3, illustrating that amines of the present invention and aldehydes chemistry The heat resistance of the graft-modified high-ortho-cresol phenolic resin is higher than that of the unmodified phenolic resin.

The samples of the above examples and comparative examples prepare friction materials, and the friction material components are calculated by mass percent: 18% phenolic resin, 19% aramid fiber, 10% glass fiber, 9% aluminum oxide, and 9% pyrite powder , graphite 9%, vermiculite 6%, petroleum coke powder 4%, barium sulfate 4% and molybdenum disulfide 12%. It is prepared by the following method: Material mixing: weigh each component raw material according to the above proportion, add it into a high-speed mixer and stir for 30 minutes to obtain a uniformly dispersed mixed raw material.

Hot pressing molding: Pour the uniformly dispersed mixed raw materials into the mold, and press the hot pressing machine at a temperature of 150°C and a pressure of 16 MPa. During the hot pressing process, the pressure is kept for 5 minutes, and the mold needs to be opened and deflated 4 times within the first five minutes of keeping the pressure. . Heat treatment: put the hot-pressed sample into an oven, heat treatment at a temperature of 160°C for 12 hours, and obtain a friction material sample after cooling down. The obtained friction material samples were subjected to a constant speed test according to GB5763-2008. Here, Example 1 and Comparative Examples 1, 2, and 3 with basically the same experimental conditions were used for comparison. The test results are shown in Table 3.

Coefficient of friction and wear rate of table 3 embodiment and comparative example

Note: The better the flexibility of the resin, the higher the friction coefficient of the friction material; the better the heat resistance of the resin, the more stable the friction coefficient of the friction material.

As can be seen from Table 3, the amines of the present invention and aldehydes are condensed and modified to prepare high-ortho cresol resin embodiment 1. The coefficient of friction and stability are all higher than those of Comparative Examples 1, 2, and 3, indicating that amines of the present invention are compatible with The flexibility and heat resistance of high-ortho-cresol-formaldehyde resin prepared by condensation modification of aldehydes are higher than those of unmodified or individually modified ortho-cresol-formaldehyde resin. In addition, the wear rate of Example 1 is lower than that of Comparative Examples 1, 2, and 3, indicating that the high-ortho cresol resin prepared by condensation modification of amines and aldehydes in the present invention improves the wear resistance of the phenolic resin.

The above are only preferred implementations of the present invention, and it should be noted that the above preferred implementations should not be regarded as limiting the present invention, and the scope of protection of the present invention should be based on the scope defined in the claims. For those skilled in the art, without departing from the spirit and scope of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (5)

1. a kind of method that adopts amines and aldehydes condensation to prepare modified high ortho cresol resin, is characterized in that, described method step is as follows: (1) Add o-cresol, paraformaldehyde, and the first catalyst in the stirred reactor in proportion, heat up and keep warm for reaction, then add the second catalyst, keep warm for reaction; (2) Add a solvent to dissolve the reaction product in step (1), wash off the precipitate with hot deionized water, and wash until neutral; heat and dehydrate at normal pressure until no water flows out, and then dephenolize under reduced pressure to obtain product A; The product A is lowered to 90-110°C, and the solvent is added again to dissolve the product; (3) Take amines and aldehydes for pre-reaction with temperature to obtain product B; The amines are one of p-phenylenediamine and aniline, and the aldehydes are one of butyraldehyde, furfural, and isobutyraldehyde; the molar ratio of aldehydes to amines is 1.4-1.6, and the pre-reacted The time is 0.5-2h, the temperature is 60-80°C; (4) Add oxalic acid into the three-neck bottle containing the dissolved product A, then drop the product B into the bottle by dropping, and keep warm after the dropping; dehydrate at normal pressure until no water flows out to obtain amine-aldehyde Modified high ortho cresol resin; The molar ratio of added oxalic acid to amines is 0.1-0.2; the mass ratio of product B to product A is 0.2-0.5; the dropping time is 1-2h, the temperature is 90-110°C, and the heat preservation reaction temperature is 90-110°C , the time is 1-4h. 2. The method for preparing modified high-ortho-ortho-cresol resins by condensation of amines and aldehydes according to claim 1, wherein the molar ratio of paraformaldehyde to ortho-cresol in step (1) is 0.75 -0.95, the first catalyst is one of zinc acetate, calcium acetate, and magnesium oxide, the mass ratio of the first catalyst to o-cresol is controlled between 1% and 3%, the heat preservation reaction time is 2-4h, and the reaction temperature 90-110°C. 3. The method for preparing modified high-ortho-orthocresol-formaldehyde resins by condensation of amines and aldehydes according to claim 1, wherein the second catalyst in step (1) is oxalic acid or p-toluenesulfonic acid One or a mixture of the two, the mass ratio of the second catalyst to o-cresol is controlled between 0.5%-2%; the holding time is 2-4h, and the temperature is 90-110°C. 4. the method for preparing modified high-ortho cresol-formaldehyde resin by condensation of amines and aldehydes according to claim 1, characterized in that, the solvent described in step (2) is methyl isobutyl ketone, acetone or a mixture of butanol, the mass ratio of the solvent to the o-cresol novolac resin is 0.5-1, and the temperature of the hot deionized water is 80-90°C. 5. The method for preparing modified high-ortho-o-cresol novolac resin by condensation of amines and aldehydes according to claim 1, characterized in that, in step (2), the external temperature of normal pressure dehydration is 150-170°C, and The vacuum degree of pressure dephenolization is above -0.09Mpa, the temperature to dephenolation is 190-200°C, and the maintenance time is 1-3h.