阅读说明：本技术 高活性发泡酚醛树脂及中性酚醛泡沫的制备方法 (Preparation method of high-activity foaming phenolic resin and neutral phenolic foam ) 是由 薛永顺 王锦程 王文浩 于 2020-07-22 设计创作，主要内容包括：一种高活性发泡酚醛树脂及中性酚醛泡沫的制备方法,属于有机化学技术领域。该高活性发泡酚醛树脂的制备方法包括以下过程：称取一定量的苯酚、液体甲醛和碱性催化剂加入反应瓶中,在70～90℃下反应一段时间后,降温至50～60℃,再加入碳酰胺和六次甲基四胺恒温反应20～40分钟；之后真空负压脱水,至粘度达到500～3000cps,得到高活性发泡酚醛树脂。本发明制备工艺简单,能耗低,制得的酚醛泡沫呈中性,解决了酚醛泡沫呈酸性的问题,避免了对水泥砂浆、混凝土、金属的腐蚀。(A preparation method of high-activity foaming phenolic resin and neutral phenolic foam belongs to the technical field of organic chemistry. The preparation method of the high-activity foaming phenolic resin comprises the following steps: weighing a certain amount of phenol, liquid formaldehyde and an alkaline catalyst, adding the phenol, the liquid formaldehyde and the alkaline catalyst into a reaction bottle, reacting at 70-90 ℃ for a period of time, cooling to 50-60 ℃, adding carbamide and hexamethylenetetramine, and reacting at constant temperature for 20-40 minutes; and then dehydrating under vacuum and negative pressure until the viscosity reaches 500-3000 cps to obtain the high-activity foamed phenolic resin. The preparation process is simple, the energy consumption is low, the prepared phenolic foam is neutral, the problem that the phenolic foam is acidic is solved, and the corrosion to cement mortar, concrete and metal is avoided.)

1. The preparation method of the high-activity foaming phenolic resin is characterized by comprising the following steps of:

weighing a certain amount of phenol, liquid formaldehyde and an alkaline catalyst, adding the phenol, the liquid formaldehyde and the alkaline catalyst into a reaction bottle, reacting at 70-90 ℃ for a period of time, cooling to 50-60 ℃, adding carbamide and hexamethylenetetramine, and reacting at constant temperature for 20-40 minutes; and then dehydrating under vacuum and negative pressure until the viscosity reaches 500-3000 cps to obtain the high-activity foamed phenolic resin.

2. The method for preparing the high-activity foamed phenolic resin as claimed in claim 1, wherein the concentration of formaldehyde in the liquid formaldehyde is 25-50%, and the molar ratio of formaldehyde to phenol is 1.1-1.5.

3. The method for preparing high-activity phenolic resin foam as claimed in claim 1, wherein the alkaline catalyst is at least one of sodium hydroxide, barium hydroxide and sodium carbonate, and the amount of the alkaline catalyst added is 0.5-5% of the weight of the phenol.

4. The method for preparing the high-activity foamed phenolic resin according to claim 1, wherein the content of free phenol is detected in the reaction process at 70-90 ℃, and the temperature is reduced to 6.0-10.0% to terminate the condensation polymerization of the phenolic resin.

5. The method for preparing high-activity foamed phenolic resin according to claim 1, wherein the amount of hexamethylenetetramine added is 5-30% by weight of phenol.

6. The preparation method of the neutral phenolic foam is characterized by comprising the following steps of:

taking a certain amount of high-activity foamed phenolic resin prepared by the method of any one of claims 1 to 5, adding a foaming agent, a foam stabilizer and a flame retardant in proportion, uniformly stirring, adding an acid curing agent in a certain proportion, uniformly stirring at a high speed, pouring into a mold preheated to 60-70 ℃, foaming and curing in an oven at 60-70 ℃ for 10-15 minutes to obtain a neutral phenolic foam material.

7. The method for preparing neutral phenolic foam according to claim 6, wherein the acid curing agent is added in an amount of 5-10% by weight based on the high activity foamed phenolic resin.

8. The method for preparing the neutral phenolic foam according to claim 6, wherein the acid curing agent is one or more complex acids of phenolsulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, sulfuric acid and phosphoric acid.

9. The method for preparing the neutral phenolic foam according to claim 6, wherein the high-speed stirring speed is not less than 2000 r/min.

10. The method for preparing the neutral phenolic foam according to claim 6, wherein the foaming agent is pentane or hexane, and the foam homogenizing agent is silicone oil or Tween 80; the addition amount of the foaming agent is 5-10% of the weight of the phenolic resin, and the addition amount of the foam stabilizer is 0.5-2.0% of the weight of the phenolic resin.

Technical Field

The invention relates to a technology in the field of organic chemistry, in particular to a preparation method of high-activity foaming phenolic resin and neutral phenolic foam.

Background

The phenolic foam has excellent fire resistance, heat insulation, dimensional stability and chemical resistance, and is widely applied to the fields of building external wall heat insulation, central air-conditioning ventilation pipelines, industrial pipelines, tank body heat insulation and the like. In the general production process of the phenolic foam, a large amount of acid is required to be added as a curing agent, the addition amount is about 20-60% of the weight of the resin, so that a large amount of acid remains in the phenolic foam, and the pH value is generally between 1-4. In the field of building external wall heat insulation, the corrosivity of phenolic foam residual acid on cement mortar and mixed soil; in the field of heat preservation of central air-conditioning ventilation pipelines, phenolic foam residual acid corrodes color steel and aluminum foil; in the field of industrial pipeline and tank body heat preservation, the development and use of phenolic foam are restricted by the corrosion of residual acid of the phenolic foam on metal pipelines and tank bodies.

Chinese patent application publication No. CN102558757A mentions a method for preparing neutral phenolic foam by adding alkaline slow-release type microcapsules into phenolic resin and neutralizing residual acid of foam with alkali metal. However, alkali metal released by the alkaline slow-release microcapsules is very slow, the effect is not obvious after the foam is solidified stably, the adding amount of the alkaline slow-release microcapsules needs to be increased to achieve the effect of neutral foam, and the reduction of the strength of the phenolic foam material can be caused by the large adding amount of the capsule particles.

Chinese patent application No. CN102286188A discloses a method for preparing neutral phenolic foam, which comprises mixing thermoplastic phenolic resin and thermosetting phenolic resin, curing the thermoplastic phenolic resin with hexamethylenetetramine, and adding acid curing agent. However, hexamethylenetetramine curing thermoplastic phenolic resin needs very high temperature, which can be basically realized at a temperature of more than 130 ℃, and if the temperature is controlled at a temperature of more than 130 ℃ in the phenolic foaming process, firstly, the energy consumption is high, secondly, the realization difficulty of the foaming process is high, the generation process is complex, and the cost is high.

The present invention has been made to solve the above-mentioned problems occurring in the prior art.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a preparation method of high-activity foaming phenolic resin and neutral phenolic foam, the preparation process is simple, the energy consumption is low, the prepared phenolic foam is neutral, and the problem of the corrosivity of the acidity of the phenolic foam on cement mortar, concrete and metal is solved.

The invention relates to a preparation method of high-activity foaming phenolic resin, which comprises the following steps:

weighing a certain amount of phenol, liquid formaldehyde and an alkaline catalyst, adding the phenol, the liquid formaldehyde and the alkaline catalyst into a reaction bottle, reacting at 70-90 ℃ for a period of time, cooling to 50-60 ℃, adding carbamide and hexamethylenetetramine, and reacting at constant temperature for 20-40 minutes; and then dehydrating under vacuum and negative pressure until the viscosity reaches 500-3000 cps to obtain the high-activity foamed phenolic resin.

Preferably, the concentration of formaldehyde in the liquid formaldehyde is 25-50%, and the molar ratio of formaldehyde to phenol is 1.1-1.5.

Preferably, the alkaline catalyst is at least one of sodium hydroxide, barium hydroxide and sodium carbonate, and the addition amount is 0.5-5% of the weight of the phenol.

Preferably, the phenol content of the liquid is detected in the reaction process at 70-90 ℃, and the measured concentration is reduced to 6.0-10.0% so as to terminate the condensation polymerization reaction of the phenolic resin.

Preferably, hexamethylenetetramine is added in an amount of 5% to 30% by weight of phenol.

The invention also relates to a preparation method of the neutral phenolic foam, which comprises the following steps:

taking a certain amount of high-activity foamed phenolic resin, adding a foaming agent, a foam stabilizer and a flame retardant in proportion, uniformly stirring, adding a certain proportion of an acid curing agent, uniformly stirring at a high speed, pouring into a mold preheated to 60-70 ℃, and foaming and curing in an oven at 60-70 ℃ for 10-15 minutes to obtain the neutral phenolic foam material.

Preferably, the addition amount of the acid curing agent is 5-10% of the weight of the high-activity foamed phenolic resin, and the high-speed stirring speed is more than or equal to 2000 r/min.

Preferably, the acid curing agent is one or more complex acids of phenolsulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, sulfuric acid and phosphoric acid.

Preferably, the foaming agent is pentane or hexane, and the foam homogenizing agent is silicone oil or Tween 80; the addition amount of the foaming agent is 5-10% of the weight of the phenolic resin, and the addition amount of the foam stabilizer is 0.5-2.0% of the weight of the phenolic resin.

Technical effects

Compared with the prior art, the invention has the following technical effects:

1) performing activity test on the synthesized high-activity foamed phenolic resin, and after adding phenolsulfonic acid, measuring that the heat release temperature can reach 110-130 ℃, the heat release is 20-40 ℃ higher than that of the common foamed phenolic resin, the curing time is 50-80 seconds, and the curing time is about 30-50 seconds faster than that of the common foamed phenolic resin; the high-activity foaming phenolic resin has high heat release and high curing speed, so that the addition amount of an acid curing agent can be greatly reduced in the process of preparing neutral phenolic foam by using the high-activity foaming phenolic resin;

2) in the process of preparing the phenolic foam, the amount of the added acid curing agent is small, and then hexamethylene tetramine in the high-activity foaming phenolic resin is decomposed in the foaming process to release NH₃Formation of NH₄OH neutralizes acid remained in the phenolic foam, and the pH value of the prepared phenolic foam is 6.0-6.5, so that the corrosivity of the phenolic foam acidity to cement mortar, concrete and metal is solved to a great extent.

Detailed Description

The present invention will be described in detail with reference to specific embodiments. The experimental procedures, in which specific conditions are not specified in the examples, were carried out according to the conventional methods and conditions.

In the synthesis of the high-activity foamed phenolic resin in the embodiment of the invention, the raw material formulation is shown in the following table 1.

Table 1 raw material ratio table one

The synthesis process is as follows:

firstly, putting phenol, formaldehyde and an alkaline catalyst into a reaction bottle, heating to 80 +/-10 ℃ for reaction, starting to detect the content of free phenol (phenol) in a solution after reacting for 2.0 hours, stopping heating when the concentration of the free phenol reaches 6.0-10.0%, and quickly cooling to 55 +/-5 ℃;

then, adding carbamide and hexamethylenetetramine at the temperature of 55 +/-5 ℃, and reacting for 20-40 minutes at the temperature of 55 +/-5 ℃;

and finally, starting vacuum negative pressure dehydration operation, stopping vacuum dehydration when the vacuum degree reaches more than 700mmHg and the viscosity of the resin reaches 500-3000 cps, and quickly cooling to below 30 ℃ to obtain the high-activity foamed phenolic resin for later use.

And (3) carrying out activity detection on the synthesized high-activity foaming phenolic resin: at 25 ℃, 50g of the synthesized high-activity foamed phenolic resin is poured into a 150ml disposable plastic cup, 10g of phenol sulfonic acid with the concentration of 65 percent is added, a mercury precision thermometer with the measuring range of 0-200 ℃ is used for stirring and timing, the thermometer is inserted into the middle part of the liquid level after the stirring is uniform, and the time and the temperature value on the thermometer are recorded after the phenolic resin is completely cured.

In the synthesis of the phenolic foam of the present invention, the raw material formulation is shown in table 2 below.

TABLE 2 raw materials proportioning Table II

Serial number	Name of raw materials	Grade	Addition amount (parts)
				1	High-activity foaming phenolic resin	Self-made	100
2	Foaming agent	Industrial grade	5.0～10.0
				3	Foam homogenizing agent	Industrial grade	0.5～2.0
4	Flame retardant	Industrial grade	5～10
				5	Acid curing agent	Industrial/homemade	5～10

The synthesis process is as follows:

taking 100g of high-activity foamed phenolic resin, adding a foaming agent, a foam homogenizing agent and a flame retardant, fully stirring, and adjusting the temperature to 25 ℃; and adding an acid curing agent with the adjusted temperature (25 ℃), stirring at a high speed for 5-10 seconds, immediately pouring into a mold preheated to 60-70 ℃, then placing into a drying oven at 60-70 ℃ for foaming and curing for 10-15 minutes, and then taking out to obtain the neutral phenolic foam.

And (3) carrying out pH detection on the synthesized neutral phenolic foam: 5g of the foam was poured into a 250ml beaker containing 200g of distilled water, and after stirring for 24 hours, the supernatant was taken and its pH was measured with a pH meter.