CN101302325A - A kind of preparation method of high temperature resistant phenolic foam - Google Patents

Abstract

The invention discloses a preparation method of high temperature resistant phenolic foam, a. using silicate as catalyst, the molar ratio of phenol:catalyst is 1: (0.05～2.00), while silicate is used as resole phenolic resin synthesis catalyst Silicon ion reacts with methylol to form a resole phenolic resin containing structural formula (I), and forms a resole phenolic resin containing structural formula (II) by adding a molybdenum compound to react with the resole phenolic resin in the later stage of preparation of the modified resole phenolic resin. Step phenolic resin; B. with the modified resole phenolic resin, surfactant, blowing agent and curing agent, and relative to the inorganic short fiber of modified resole phenolic resin consumption 0.5～15%, mixing, high-speed stirring, Inject into the mold and cure at 60-100°C for 30-120 minutes to obtain the product. The high temperature resistant phenolic foam developed by the invention can be used for a long time under the high temperature condition of 250°C.

Description

A kind of preparation method of high temperature resistant phenolic foam

technical field

The invention relates to a method for modifying a resole phenolic resin, and more specifically relates to a method for preparing a high-temperature-resistant phenolic foam.

Background technique

The energy problem is a problem that countries all over the world pay attention to at present, and it is listed as one of the four major survival problems faced by human beings. In the world's energy consumption, since the proportion of building energy consumption is very high (generally 20-40%), all countries in the world have listed building energy conservation as the focus of energy-saving work. Statistics show that every ton of thermal insulation material used in construction can save 1 ton of fuel oil every year. Every cubic meter of thermal insulation material used in industrial thermal insulation can save about 3 tons of standard coal per year. In the 1980s, scientists discovered that phenolic resin and its products have outstanding flame retardancy, low smoke, and low toxicity (that is, FST characteristics), and phenolic foam products also have excellent energy-saving and thermal insulation effects. Therefore, since the 1990s, phenolic composite materials including phenolic foam have been greatly developed, and have been used in aerospace, national defense and military industries, and places with strict fire protection requirements such as civil aircraft, ships, stations, and oil wells, and gradually extended to Civil buildings, factories, warehouses, hospitals, schools, exhibition centers, sports facilities, mobile homes and other fields.

The preparation of phenolic foam usually uses resole phenolic resin as main raw material, and its known and commonly used technology is: resole phenolic resin, surfactant (such as Tween-80), foaming agent (such as pentane), curing agent ( Various inorganic acids or organic acids), stirred at high speed, poured into the mold, and cured at 60-100°C for 30-120 minutes to obtain the product. Due to the low thermal conductivity of phenolic foam (0.018-0.032W/mk), compared with traditional thermal insulation materials such as mineral wool, rock wool, glass wool, etc. (0.034-0.043W/mk), its energy-saving and thermal insulation performance is nearly doubled. Polyurethane (PU) foam is equivalent and better than polystyrene (PS) foam, and its energy-saving and thermal insulation performance ranks first among all thermal insulation materials. At the same time, PU and PS foams are flammable and are very unsafe as thermal insulation building materials. In recent years, their market applications have been greatly restricted.

Although phenolic foam has excellent thermal insulation, its temperature range is generally between -190 and +150°C, and cold thermal insulation is better than thermal thermal insulation. If the use temperature exceeds 150°C, severe cracking and thermal decomposition will occur, and the heat preservation effect will be lost. At present, inorganic thermal insulation materials are widely used in high temperature insulation. Although they can withstand high temperatures of several hundred degrees, inorganic thermal insulation materials are heavy and have high thermal conductivity, and their thermal insulation effect is far inferior to that of phenolic foam.

Contents of the invention

The technical problem to be solved by the present invention is to provide an improved preparation method of high-temperature-resistant phenolic foam, which can prepare high-temperature-resistant phenolic foam insulation materials that can be used for a long time at a high temperature of 250 ° C. The high-temperature-resistant phenolic foam can be widely used Applied to -190～+250°C thermal insulation places, greatly expanding the use of phenolic foam thermal insulation materials.

The technical scheme adopted in the present invention: a preparation method of high temperature resistant phenolic foam, comprising the following steps:

a. Preparation of modified resole phenolic resin:

Adopt silicate as catalyzer, phenol: the mol ratio of catalyst is 1: (0.05～2.00), silicon ion and methylol react to form formazan containing structural formula (I) when silicate is made resol synthetic catalyst Resole phenolic resin, in the later stage of preparation of modified resole phenolic resin, by adding molybdenum compound and resole phenolic resin to react to form the resole phenolic resin containing structural formula (II), the synthetic modified resole phenolic resin contains Si-O bond and Mo-O bonds;

b. Preparation of phenolic foam:

Mix the modified resole phenolic resin, surfactant, foaming agent and curing agent, and inorganic short fibers with an amount of 0.5 to 15% relative to the modified resole phenolic resin, mix them, stir them at a high speed, and pour them into the mold at 60 to Curing at 100°C for 30-120 minutes to obtain the product.

Beneficial effects of the present invention: the present invention successfully develops a high-temperature-resistant phenolic foam insulation material that can be used for a long time under the high temperature condition of 250°C by modifying the phenolic resin and adding a certain amount of short inorganic fibers during the foaming stage. Expanded the scope of use of thermal insulation of phenolic foam insulation materials.

Detailed ways

The present invention is described in further detail below by the examples, and content of the present invention is made up of following two parts: a. preparation of modified resole phenolic resin: the main reason that phenolic foam is not resistant to high temperature is that phenolic resin is to connect benzene ring by C-C bond, bond energy At the same time, its phenolic hydroxyl group is easily oxidized, so it is easy to crack and decompose under high temperature conditions. The first important technical measure of the present invention is to introduce Si-O bonds and Mo-O bonds with higher bond energy into the resole phenolic resin. At present, the catalysts used in the synthesis of resole phenolic resin are sodium hydroxide, ammonium hydroxide, barium hydroxide, calcium hydroxide and the like. In the later stage of synthesis, the pH value is adjusted with sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, etc. The present invention uses sodium silicate, potassium silicate, silica sol and other silicates as catalysts, and the consumption is: phenol:catalyst=1:0.05～2.00 (molar ratio). Its purpose is to react silicon ions with methylol to form structure (I) when silicate is used as a catalyst for the synthesis of resole phenolic resin.

In the later stage of the synthesis of the modified resole phenolic resin, molybdenum compound is added to react with the resole phenolic resin to form a resole phenolic resin with structural formula (II). Since Si-O bonds and Mo-O bonds with better thermal stability are introduced into the main chain structure, it is beneficial to improve the high temperature resistance of phenolic foam. The molybdenum compound used in the present invention includes: molybdic acid, sodium molybdate, ammonium molybdate, molybdenum powder and the like. The amount of molybdenum compound relative to the catalyst is: catalyst:molybdenum compound=1:0.50～5.00 (molar ratio).

b. Improvement of foaming formula:

Currently known phenolic foam preparation formula and technology are: resole phenolic resin, surfactant (such as Tween-80), foaming agent (such as pentane), curing agent (acid), high-speed stirring, injection mold, at 60 At ~100°C, cure for 30-120 minutes to obtain the product. The present invention adopts the above modified resole phenolic resin, and adds 0.5-15% inorganic short fiber relative to the amount of the modified resole phenolic resin in the formula. The inorganic short fibers used include ceramic short fibers, glass short fibers and the like. The purpose of adding short inorganic fibers is to solve the problem of cracking of phenolic foam at high temperature, which is beneficial to improve the high temperature resistance and thermal insulation effect of phenolic foam at high temperature.

Example 1

Into a 250ml three-neck flask, add in sequence: 20 grams of distilled water, 94.1 grams of phenol, 40.6 grams of paraformaldehyde, and 85.2 grams of sodium silicate, heat and stir in a water bath, keep the reaction at 80-85 ° C for 3 hours, stop heating, and cool to room temperature. Add 90 grams of molybdic acid, stir and react for 1 hour to obtain a modified resole phenolic resin. Add 65 grams of modified resole phenolic resin, 3.5 grams of Tween-80, 6 grams of ceramic short fibers, 6.5 grams of pentane, and 9 grams of 65% p-toluenesulfonic acid into the mixing pot in turn, stir at high speed for 30 seconds, and quickly pour into the 1000cm In the mold of ³ , close the mold, foam and solidify at 75°C for 1 hour, cool, and demould to obtain a high temperature resistant phenolic foam with a density of about 83kg/ ^m3 .

The main performance index of embodiment 1 product is:

Apparent density 40～200 kg/m ³ (GB6343)

Thermal conductivity 0.025～0.06 w/mk (GB10294)

Combustion performance Class B1 flame retardant (GB8625)

Compressive strength ≥0.10 Mpa (GB8813)

Maximum operating temperature 250 ℃ (GB17430)

Example 2

Into a 250ml three-neck flask, add in turn: 20 grams of distilled water, 94.1 grams of phenol, 40.6 grams of paraformaldehyde, and 31.6 grams of potassium silicate, heat and stir in a water bath, keep the reaction at 80-85 ° C for 3 hours, stop heating, and cool to room temperature. Add 20 grams of acetic acid and 29 grams of molybdenum powder, stir and react for 1 hour to obtain a modified resole phenolic resin. Add 130 grams of modified resole phenolic resin, 7 grams of Tween-80, 6 grams of short glass fiber, 13 grams of pentane, and 18 grams of 65% p-toluenesulfonic acid into the mixing pot in turn, stir at high speed for 30 seconds, and quickly pour into the 1000cm In the mold of ³ , close the mold, foam and solidify at 75°C for 1 hour, cool, and demould to obtain a high temperature resistant phenolic foam with a density of about 160kg/ ^m3 .

Example 3

Into a 250ml three-neck flask, add in sequence: 94.1 grams of phenol, 40.6 grams of paraformaldehyde, and 90 grams of silica sol, heat and stir in a water bath, keep the reaction at 80-85°C for 3 hours, stop heating, cool to room temperature, add 30 grams of acetic acid and 70 grams of sodium molybdate was stirred and reacted for 1 hour to obtain a modified resole phenolic resin. Add 32.5 grams of modified resole phenolic resin, 1.8 grams of Tween-80, 4 grams of short ceramic fiber, 3.2 grams of pentane, and 4.5 grams of 65% p-toluenesulfonic acid into the mixing pot in turn, stir at high speed for 30 seconds, and quickly pour into the 1000cm In the mold of ³ , close the mold, foam and solidify at 75°C for 1 hour, cool, and demould to obtain a high temperature resistant phenolic foam with a density of about 43kg/ ^m3 .

The above content is only a basic description of the concept of the present invention, and any equivalent transformation made according to the technical solution of the present invention shall fall within the scope of protection of the present invention.

Claims (1)

1. the preparation method of a high temperature resistance phenolic aldehyde foam comprises the following steps:

A. modification resole preparation:

Employing silicate is catalyzer, phenol: the mol ratio of catalyzer is 1: (0.05～2.00), silicon ion and methylol reacted and form the resole that contains structural formula (I) when silicate was made the resole synthetic catalyst, later stage in the preparation of modification resole is contained the resole of structural formula for (II) by adding molybdenum compound and resole reaction formation, and synthetic modification resole contains Si-O key and Mo-O key;

B. prepare phenol formaldehyde foam:

With resole, tensio-active agent, whipping agent and the solidifying agent of modification, and with respect to the inorganic staple fibre of modification resole consumption 0.5～15%, mix, high-speed stirring is injected mould, solidifies 30～120min down in 60～100 ℃ and gets product.