Preparation method of high-strength melamine foam material

Abstract

The invention discloses a preparation method of a high-strength melamine foam material, which comprises the following steps: firstly, adding an aldehyde compound and melamine according to a certain molar ratio, uniformly mixing, heating to a certain temperature in a weak alkaline environment, and reacting to prepare expandable melamine resin; then uniformly stirring phenolic aldehyde or melamine fiber with foaming substances such as melamine resin, a foaming agent and a curing agent to obtain foaming liquid, and performing microwave foaming and high-temperature curing to obtain melamine foam. According to the melamine foam prepared by the preparation method disclosed by the invention, the excellent flame retardant property of the melamine foam can be kept while the strength is ensured to be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of flame-retardant, heat-insulating melamine foam and preparation thereof, and particularly relates to a preparation method of a high-strength melamine foam material. Background Art

[0002] Melamine foam is a foam material with excellent performance. Compared with traditional foam materials, it has the characteristics of high open porosity, good sound absorption and moisture absorption, and aging resistance. Due to its unique three-dimensional network structure with highly cross-linked triazine rings, it has better flame retardant performance and thermal stability. Due to its special properties, it is widely used in aerospace, building materials, closed trains, battery pack insulation and fire protection and other fields.

[0003] Although melamine foam is light and flame retardant, its high hardness, low strength, easy to fall off and other characteristics greatly limit its application range. In order to broaden its application field, domestic and foreign scholars have conducted a lot of research on the enhancement of melamine foam mechanical properties from two aspects: modification of melamine foam and regulation of pore structure. Significant results have been achieved, but there are still some problems, such as the contradiction between the improvement of mechanical properties and the production process and raw material costs, the loss of flame retardant properties, the reduction of heat resistance, and the limited toughening range.

[0004] Phenolic / melamine fiber is a fiber material formed by the reaction of phenol, melamine and formaldehyde. The use of aldehyde in the reaction makes the phenolic fiber and melamine have a natural affinity. A chemical bond has been formed between the two interfaces, which enhances the ability of the fiber to reinforce the melamine foam.

[0005] The present invention uses phenolic or melamine fibers prepared by wet spinning as reinforcing filling materials, further improves the mechanical properties of melamine foam by reinforcing and toughening melamine foam, and conducts a series of explorations on the properties of the prepared melamine foam. Summary of the invention

[0006] The invention provides a method for preparing a high-strength melamine foam material, which has a simple process and little pollution. The prepared melamine foam can ensure increased strength while maintaining excellent flame retardant properties of the melamine foam.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: The invention comprises the following steps: uniformly mixing melamine and aldehyde compounds, reacting them under weak alkaline conditions, heating them for reaction, cooling them down to obtain expandable melamine resin, uniformly stirring the obtained melamine resin with phenolic formaldehyde or melamine fiber, a foaming agent and other foaming substances to obtain a foaming liquid, foaming them with microwaves, and aging them at high temperature to obtain melamine foam.

[0008] The present invention provides a method for preparing a high-strength melamine foam material, the steps of which are as follows: (1) Melamine, aldehyde compound and alkaline catalyst are mixed and added to deionized water, the pH is adjusted to weak alkalinity, and the mixture is heated to 85-110°C. After the solution becomes clear, the reaction is continued for 20-60 minutes, and then the mixture is quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin.

[0009] (2) By mass, 100 parts of the melamine resin obtained in step (1) are mixed with 1-5 parts of phenolic formaldehyde or melamine fiber, 4-15 parts of a foaming agent, 1-5 parts of a curing agent and 3-10 parts of an emulsifier, and stirred to obtain a foaming liquid, and the foaming liquid is subjected to microwave foaming and high-temperature aging to obtain a melamine foam.

[0010] In the step (1), the molar ratio of melamine to aldehyde compound is 1:(2-3.5), and the mass ratio of melamine to alkaline catalyst is 1:(0.001-0.01).

[0011] In the step (1), the aldehyde compound is formaldehyde or acetaldehyde; the phenolic or melamine fiber is primary phenolic or melamine fiber, or phenolic or melamine fiber cured in air at 180° C. for 0.1 to 3 hours; and the alkaline catalyst is one of sodium hydroxide, potassium hydroxide, triethanolamine, and hexamethylenetetramine.

[0012] In the step (2), the foaming agent is one of n-pentane, isopentane, cyclopentane, n-hexane and cyclohexane.

[0013] In the step (2), the curing agent is one of formic acid, acetic acid, hydrochloric acid, sulfuric acid, and p-toluenesulfonic acid.

[0014] In the step (2), the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium chloride, dodecyl polyoxyethylene ether, and Tween-80.

[0015] In the step (2), the stirring process uses a high-speed mechanical stirring of 4000 r / min for 30-110 s, the microwave foaming power is 3000-4000 W, and the high-temperature aging is aging at a high temperature environment of 100-140° C. for 1-5 h.

[0016] The beneficial effects of the present invention are:

[0017] 1. Both phenolic / melamine fiber and melamine foam are made of aldehyde resin, which has better compatibility. During the reaction, the fiber and foam skeleton can be cross-linked without surface treatment of the fiber. The fiber has higher strength, which makes the mechanical properties of melamine foam reinforced by phenolic / melamine fiber in situ more excellent.

[0018] 2. Melamine foam material itself has good sound insulation and heat insulation properties. The in-situ reinforced phenolic / melamine fiber further improves the sound absorption performance, making the material perform better in sound insulation and heat insulation applications, such as in building insulation, sound insulation panels and industrial sound insulation equipment, effectively improving energy efficiency and comfort.

[0019] 3. Phenolic / melamine fiber has good flame retardant properties, and the flame retardant properties of melamine foam are further improved by adding fibers.

[0020] 4. Phenolic / melamine fiber has good chemical stability. The in-situ reinforced melamine foam material shows better corrosion resistance when it comes into contact with chemicals such as acids, alkalis and organic solvents. This makes the material more widely used in fields such as chemical industry and anti-corrosion engineering that need to resist chemical corrosion. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention. Example 1

[0022] This embodiment provides a method for preparing a high-strength melamine foam material, and the steps are as follows: (1) Melamine and formaldehyde are mixed evenly and added to deionized water, and an alkaline catalyst sodium hydroxide is added to adjust the pH to a weak alkaline state, and the mixture is heated to 85°C. After the solution becomes clear and transparent, the mixture is reacted at a constant temperature for 20 minutes, and then the solution is taken out and quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin. The molar ratio of melamine to aldehyde compound is 1:2, and the mass ratio of melamine to alkaline catalyst is 1:0.01.

[0023] (2) 100 parts by mass of the obtained expandable melamine resin were mixed with 1 part of primary phenolic fiber, 4 parts of n-pentane, 1 part of formic acid and 3 parts of sodium dodecyl sulfate, and then stirred at 4000 r / min for 30 seconds to prepare a foaming liquid, and the foaming liquid was subjected to microwave foaming at a foaming power of 3000 W, and then aged at a high temperature environment of 100° C. for 1 hour to obtain melamine foam.

[0024] The apparent density of the melamine foam is 4 kg / m 3 The open porosity is 96%, the tensile strength is 950kPa, the elongation at break is 32%, the sound absorption coefficient of 10cm melamine foam at a frequency of 110Hz-4000Hz reaches 98.5%, the vertical burning UL-94 rating is V-0, the limiting oxygen index is 46.1%, the thermal conductivity is 0.036W / (m·K), and the foam is not easy to fall off. Example 2

[0025] This embodiment provides a method for preparing a high-strength melamine foam material, and the steps are as follows: (1) Melamine and acetaldehyde are mixed evenly and added to deionized water, and alkaline catalyst potassium hydroxide is added to adjust the pH to a weak alkaline state, and the mixture is heated to 110°C. After the solution becomes clear and transparent, the reaction is continued at a constant temperature for 60 minutes, and then the solution is taken out and quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin. The molar ratio of melamine to aldehyde compound is 1:3.5, and the mass ratio of melamine to alkaline catalyst is 1:0.001.

[0026] (2) 100 parts by mass of the obtained expandable melamine resin were mixed with 5 parts of phenolic fiber cured at 180°C in air for 3 h, 15 parts of isopentane, 5 parts of formic acid and 10 parts of sodium dodecylbenzene sulfonate, and then stirred at 4000 r / min for 110 seconds to prepare a foaming liquid, and the foaming liquid was subjected to microwave foaming at a foaming power of 4000 W, and then aged at a high temperature of 140°C for 5 h to obtain melamine foam.

[0027] The apparent density of the melamine foam is 3.5 kg / m 3 The open porosity is 98%, the tensile strength is 845kPa, the elongation at break is 63%, the sound absorption coefficient of 10cm melamine foam at a frequency of 130Hz-4000Hz reaches 98.7%, the vertical burning UL-94 rating is V-0, the limiting oxygen index is 44.1%, the thermal conductivity is 0.017W / (m·K), and the foam is not easy to fall off. Example 3

[0028] This embodiment provides a method for preparing a high-strength melamine foam material, and the steps are as follows: (1) Melamine and formaldehyde are mixed evenly and added to deionized water, and the alkaline catalyst triethanolamine is added to adjust the pH to a weak alkaline state, and the mixture is heated to 90°C. After the solution becomes clear and transparent, the mixture is reacted at a constant temperature for 50 minutes, and then the solution is taken out and quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin. The molar ratio of melamine to aldehyde compound is 1:3, and the mass ratio of melamine to alkaline catalyst is 1:0.008.

[0029] (2) 100 parts by mass of the obtained expandable melamine resin were mixed with 5 parts of primary melamine fibers, 4 parts of cyclopentane, 1 part of acetic acid and 5 parts of hexadecyltrimethylammonium chloride, and then stirred at 4000 r / min for 80 seconds to prepare a foaming liquid. The foaming liquid was subjected to microwave foaming at a foaming power of 4000 W, and then aged at a high temperature of 130° C. for 2 hours to obtain melamine foam.

[0030] The apparent density of the melamine foam is 11 kg / m 3The open porosity is 96%, the tensile strength is 354kPa, the elongation at break is 31%, the sound absorption coefficient of 10cm melamine foam at a frequency of 130Hz-4000Hz reaches 98.8%, the vertical burning UL-94 rating is V-0, the limiting oxygen index is 44.5%, the thermal conductivity is 0.005W / (m·K), and the foam is not easy to fall off. Example 4

[0031] This embodiment provides a method for preparing a high-strength melamine foam material, and the steps are as follows: (1) Melamine and formaldehyde are mixed evenly and added to deionized water, and alkaline catalyst hexamethylenetetramine is added to adjust the pH to a weak alkaline state, and the mixture is heated to 95°C. After the solution becomes clear and transparent, the reaction is continued at a constant temperature for 60 minutes, and then the solution is taken out and quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin. The molar ratio of melamine to aldehyde compound is 1:2.5, and the mass ratio of melamine to alkaline catalyst is 1:0.002.

[0032] (2) 100 parts by mass of the obtained expandable melamine resin were mixed with 3 parts of melamine fiber cured at 180°C in air for 0.1 h, 5 parts of n-hexane, 2 parts of hydrochloric acid and 6 parts of dodecyl polyoxyethylene ether, and then stirred at 4000 r / min for 40 seconds to prepare a foaming liquid, which was then subjected to microwave foaming at a foaming power of 3400 W and then aged at a high temperature of 110°C for 2 hours to obtain melamine foam.

[0033] The apparent density of the melamine foam is 9kg / m 3 The open porosity is 95%, the tensile strength is 952kPa, the elongation at break is 84%, the sound absorption coefficient of 10cm melamine foam at a frequency of 110Hz-4000Hz reaches 98.4%, the vertical burning UL-94 rating is V-0, the limiting oxygen index is 43.1%, the thermal conductivity is 0.016W / (m·K), and the foam is not easy to fall off. Example 5

[0034] This embodiment provides a method for preparing a high-strength melamine foam material, and the steps are as follows: (1) Melamine and acetaldehyde are mixed evenly and added to deionized water, and the alkaline catalyst sodium hydroxide is added to adjust the pH to a weak alkaline state, and the mixture is heated to 95°C. After the solution becomes clear and transparent, the reaction is continued at a constant temperature for 30 minutes, and then the solution is taken out and quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin. The molar ratio of melamine to aldehyde compound is 1:2.8, and the mass ratio of melamine to alkaline catalyst is 1:0.001.

[0035] (2) 100 parts by mass of the obtained expandable melamine resin were mixed with 4 parts of melamine fiber cured at 180°C in air for 0.1 h, 12 parts of cyclohexane, 4 parts of hydrochloric acid and 6 parts of Tween-80, and then stirred at 4000 r / min for 50 seconds to prepare a foaming liquid. The foaming liquid was subjected to microwave foaming at a foaming power of 3500 W, and then aged at a high temperature of 120°C for 4 hours to obtain melamine foam.

[0036] The apparent density of the melamine foam is 3.5 kg / m 3 The open porosity is 95%, the tensile strength is 957kPa, the elongation at break is 133%, the sound absorption coefficient of 10cm melamine foam at a frequency of 130Hz-4000Hz reaches 98.3%, the vertical burning UL-94 rating is V-0, the limiting oxygen index is 34.7%, the thermal conductivity is 0.008W / (m·K), and the foam is not easy to fall off. Example 6

[0037] This embodiment provides a method for preparing a high-strength melamine foam material, and the steps are as follows: (1) Melamine and acetaldehyde are mixed evenly and added to deionized water, and the alkaline catalyst potassium hydroxide is added to adjust the pH to a weak alkaline state, and the mixture is heated to 90°C. After the solution becomes clear and transparent, the reaction is continued at a constant temperature for 35 minutes, and then the solution is taken out and quickly cooled to room temperature in a cold water bath to obtain a expandable melamine resin. The molar ratio of melamine to aldehyde compound is 1:2.3, and the mass ratio of melamine to alkaline catalyst is 1:0.006.

[0038] (2) 100 parts by mass of the obtained expandable melamine resin were mixed with 5 parts of melamine fiber cured at 180°C in air for 0.9 h, 8 parts of n-hexane, 3 parts of sulfuric acid and 6 parts of sodium dodecylbenzene sulfonate, and then stirred at 4000 r / min for 90 seconds to prepare a foaming liquid, which was then subjected to microwave foaming at a foaming power of 3600 W and then aged at a high temperature of 110°C for 2 hours to obtain melamine foam.

[0039] The apparent density of the melamine foam is 4 kg / m 3 The open porosity is 96%, the tensile strength is 760kPa, the elongation at break is 33%, the sound absorption coefficient of 10cm melamine foam at a frequency of 110Hz-4000Hz reaches 98.6%, the vertical burning UL-94 rating is V-0, the limiting oxygen index is 45.2%, the thermal conductivity is 0.037W / (m·K), and the foam is not easy to fall off.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-strength melamine foam material, characterized in that Here are the steps: (1) Melamine, aldehyde compound and alkaline catalyst are mixed and added to deionized water, the pH is adjusted to be weakly alkaline, and the mixture is heated to 85-110°C. After the solution becomes clear and transparent, the mixture is reacted for 20-60 minutes, and then the mixture is quickly cooled to room temperature in a cold water bath to obtain a foamable melamine resin; (2) By mass, 100 parts of the melamine resin obtained in step (1) are mixed with 1-5 parts of phenolic formaldehyde or melamine fiber, 4-15 parts of a foaming agent, 1-5 parts of a curing agent and 3-10 parts of an emulsifier, and stirred to obtain a foaming liquid, and the foaming liquid is subjected to microwave foaming and high-temperature aging to obtain a melamine foam.

2. The method for preparing a high-strength melamine foam material according to claim 1, characterized in that: In the step (1), the molar ratio of melamine to aldehyde compound is 1:(2-3.5), and the mass ratio of melamine to alkaline catalyst is 1:(0.001-0.01).

3. The method for preparing a high-strength melamine foam material according to claim 1, characterized in that: In the step (1), the aldehyde compound is formaldehyde or acetaldehyde; the phenolic or melamine fiber is primary phenolic or melamine fiber, or phenolic or melamine fiber cured in air at 180° C. for 0.1-3 hours; and the alkaline catalyst is one of sodium hydroxide, potassium hydroxide, triethanolamine, and hexamethylenetetramine.

4. The method for preparing a high-strength melamine foam material according to claim 1, characterized in that: In the step (2), the foaming agent is one of n-pentane, isopentane, cyclopentane, n-hexane and cyclohexane.

5. The method for preparing a high-strength melamine foam material according to claim 1, characterized in that: In the step (2), the curing agent is one of formic acid, acetic acid, hydrochloric acid, sulfuric acid, and p-toluenesulfonic acid.

6. The method for preparing a high-strength melamine foam material according to claim 1, characterized in that: In the step (2), the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium chloride, dodecyl polyoxyethylene ether, and Tween-80.

7. The method for preparing a high-strength melamine foam material according to claim 1, characterized in that: In the step (2), the stirring process uses a high-speed mechanical stirring of 4000 r / min for 30-110 s, the microwave foaming power is 3000-4000 W, and the high-temperature aging is aging at a high temperature environment of 100-140° C. for 1-5 h.