Process for the preparation of low density high tensile melamine foam

Abstract

The application discloses a preparation process of low-density high-tensile melamine foam plastic, and the density of the prepared melamine foam plastic is 8-12 kg / m 3 , the tensile strength can reach 250-320 kPa, and the elongation at break can reach 25-30%, and the melamine foam plastic has the characteristics of low density and high tensile strength. In order to improve the tensile strength of the melamine foam plastic, a hydrophilic fullerene derivative is added in the preparation process, the hydrophilic fullerene derivative has a carbon cage containing 50-120 carbon atoms as a body, and has 1-6 flexible ether oxygen chains, the hydrophilic fullerene derivative is very well dispersed in the modified melamine resin and combined with other components, so that the tensile strength of the melamine foam plastic can be significantly improved. In order to further improve the tensile strength of the melamine foam plastic, the melamine resin is subjected to low-temperature freezing treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of foam plastics, in particular to a preparation process of low-density high-tensile melamine foam plastics. BACKGROUND

[0002] Melamine foam plastics have excellent sound absorption performance, flame retardant performance, heat insulation performance, insulation, moisture and heat stability, safety and health, and secondary processing performance, etc., and it is a new type of foam plastics with low density three-dimensional grid structure with a high open rate of 99.9% prepared by taking melamine as the main raw material. Melamine foam plastics have broad application prospects in the fields of building, transportation, vehicle manufacturing, acoustic engineering, electronic information and object surface cleaning and decontamination.

[0003] In recent years, melamine foam plastics are widely used in daily necessities, for example, melamine foam plastics are used to replace polyurethane foam plastics to make seat cushions due to the excellent flame retardant performance of melamine foam plastics, but the tensile strength of the existing melamine foam plastics is generally below 50kPa. The preparation process of high-rebound daily-use melamine foam plastics applied by the present company uses polyvinyl butyral, polyester polyol and polyether-modified polysiloxane copolymer for modification to obtain modified melamine resin, which has better reactivity, can rapidly and fully foam in subsequent reactions, so that the final melamine foam plastics have good rebound performance, and the tensile strength is also improved to 62-75kPa, but the melamine foam plastics do not have much advantage compared with polyurethane foam plastics. Therefore, it is necessary to develop a preparation process of low-density high-tensile melamine foam plastics. SUMMARY

[0004] Based on the technical problems existing in the background art, the present application provides a preparation process of low-density high-tensile melamine foam plastics.

[0005] The technical scheme of the present application is as follows:

[0006] A preparation process of low-density high-tensile melamine foam plastics, comprising the following steps:

[0007] (1) melamine is added into a formaldehyde solution, triethanolamine is used to adjust the pH value to 9-10, heating to 80-90℃ for 50-60min to generate melamine formaldehyde resin, polyvinyl butyral, polyester polyol and polyether-modified polysiloxane copolymer are added while stirring, nitrogen is introduced, hydrophilic fullerene derivative is slowly added, and the reaction is continued for 60-90min, concentrated hydrochloric acid is added to adjust the pH to neutral, and dehydration is performed; then it is frozen in low temperature below minus 40℃ for 120-150min, thawed at room temperature, and modified melamine resin is obtained;

[0008] (2) mixing the modified melamine resin obtained in step (1) with a surfactant and a blowing agent to obtain a first material;

[0009] (3) mixing the isooctyl mercapto propionate with a liquid curing agent to obtain a second material;

[0010] (4) continuously stirring the first material obtained in step (2) for 2-3 hours, preheating to 45-50℃, then adding the second material obtained in step (3), and continuously stirring for 30-40 minutes to obtain a mixture;

[0011] (5) transferring the mixture obtained in step (4) to a microwave heating furnace for microwave foaming to generate melamine foam plastic.

[0012] Preferably, the mass concentration of the formaldehyde solution is 25-30%, and the mass ratio of melamine, formaldehyde, polyvinyl butyral, polyester polyol, polyether modified polysiloxane copolymer, hydrophilic fullerene derivative, surfactant, blowing agent, isooctyl mercapto propionate, liquid curing agent is 1:0.35-0.45:0.2-0.3:0.03-0.04:0.02-0.03:0.008-0.015:0.5-0.7:0.1-0.2:0.7-0.8:0.05-0.1.

[0013] Preferably, the fullerene body of the hydrophilic fullerene derivative contains a carbon cage containing 50 to 120 carbon atoms, the hydrophilic fullerene derivative contains 1 to 6 flexible ether oxygen chains, and the addition site on the methylene-containing fullerene is one of [5,6] and [6,6]; the structural formula is:

[0014]

[0015] wherein R1, R2 are one of carbonyl, aromatic group, substituted aromatic group and any combination thereof;

[0016] wherein n is any number between 1 and 3.

[0017] Preferably, in step (2), the surfactant is sodium dodecyl sulfonate.

[0018] Preferably, in step (2), the blowing agent is a mixture of azobis isobutyronitrile and polyphenyl polyformaldehyde polyisocyanate. Further preferably, the mass ratio of the two is 1:1.

[0019] Preferably, in step (5), the microwave frequency of the microwave foaming furnace is 3000-3500MHz, the power is 600-800W, and the microwave foaming time is 5-8min.

[0020] The low-density high-tensile melamine foam plastic prepared by the preparation process of the low-density high-tensile melamine foam plastic has a density of 8-12 kg / m 3 , a tensile strength of 250-320 kPa and an elongation at break of 30-35%, and has the characteristics of low density and high tensile strength. In order to improve the tensile strength of the melamine foam plastic, the hydrophilic fullerene derivative is added in the preparation process. The hydrophilic fullerene derivative has a carbon cage containing 50-120 carbon atoms as a body and 1-6 flexible ether oxygen chains. Since the hydrophilic fullerene derivative is well dispersed in the modified melamine resin and combined with other components, the tensile strength of the melamine foam plastic can be significantly improved. In order to further improve the tensile strength of the melamine foam plastic, the melamine resin is subjected to low-temperature freezing treatment. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be further described below by means of specific examples. It should be understood that the implementation of the present application is not limited to the following examples, and any form of modification and / or change made to the present application will fall within the scope of protection of the present application.

[0022] In the present application, all the parts and percentages are weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are conventional methods in the art, unless otherwise specified.

[0023] The reagents used in the following examples can be purchased from conventional biochemical reagent stores, unless otherwise specified.

[0024] Example 1

[0025] A preparation process of low-density high-tensile melamine foam plastic comprises the following steps:

[0026] (1) melamine is added to a formaldehyde solution, triethanolamine is used to adjust the pH value to 9.5, heating to 82℃ for 52 min to generate melamine formaldehyde resin, polyvinyl butyral, polyester polyol and polyether modified polysiloxane copolymer are added while stirring, nitrogen is introduced, hydrophilic fullerene derivative is slowly added, and the reaction is continued for 70 min, concentrated hydrochloric acid is added to adjust the pH to neutral, and dehydration is performed; then the modified melamine resin is placed in a low temperature of minus 45℃ for freezing for 130 min, and thawed at room temperature to obtain the modified melamine resin;

[0027] (2) the modified melamine resin obtained in step (1) is mixed with a surfactant and a foaming agent to obtain a first material, which is ready for use;

[0028] (3) mixing and stirring the mercaptan propionic acid isooctyl ester with the liquid curing agent to obtain a second material, which is ready for use;

[0029] (4) continuously stirring the first material obtained in step (2) for 2.5 h, preheating to 48℃, then adding the second material obtained in step (3), and continuing to stir for 35 min to obtain a mixture;

[0030] (5) transferring the mixture obtained in step (4) to a microwave heating furnace for microwave foaming to generate melamine foam.

[0031] The mass concentration of the formaldehyde solution is 28%, and the mass ratio of melamine, formaldehyde, polyvinyl butyral, polyester polyol, polyether modified polysiloxane copolymer, hydrophilic fullerene derivative, surfactant, foaming agent, mercaptan propionic acid isooctyl ester, liquid curing agent is 1:0.42:0.25:0.035:0.025:0.012:0.6:0.18:0.75:0.08.

[0032] The fullerene body of the hydrophilic fullerene derivative contains a carbon cage containing 50 to 120 carbon atoms, the hydrophilic fullerene derivative contains 1 to 6 flexible ether oxygen chains, and the addition site of methylene on the fullerene is one of [5, 6] and [6, 6]; the structure formula is:

[0033]

[0034] wherein R1 and R2 are both carbonyl groups;

[0035] wherein n is any number between 1 and 3.

[0036] In step (2), the surfactant is sodium dodecyl sulfonate.

[0037] In step (2), the foaming agent is a mixture of azobis isobutyronitrile and polyphenyl polyformaldehyde polyisocyanate; the mass ratio of the two is 1:1.

[0038] In step (5), the microwave frequency of the microwave foaming furnace is 3280 MHz, the power is 750 W, and the microwave foaming time is 6 min.

[0039] Example 2

[0040] A preparation process of a low-density high-tensile melamine foam, comprising the following steps:

[0041] (1) melamine is added into formaldehyde solution, triethanolamine is used to adjust pH value to 9, heated to 90℃ for 50min to generate melamine formaldehyde resin, polyvinyl butyral, polyester polyol and polyether modified polysiloxane copolymer are added while stirring, nitrogen is introduced, hydrophilic fullerene derivative is slowly added, continue to react for 90min, add concentrated hydrochloric acid to adjust pH to neutral, dehydrate; then put it into low temperature of minus 42℃ for 150min, thaw at room temperature, to obtain modified melamine resin;

[0042] (2) the modified melamine resin obtained in step (1) is mixed with surfactant and foaming agent to obtain first material, which is ready for use;

[0043] (3) mercaptopropionic acid isopropyl ester is mixed with liquid curing agent to obtain second material, which is ready for use;

[0044] (4) the first material obtained in step (2) is continuously stirred for 2h, preheated to 50℃, then the second material obtained in step (3) is added, continue to stir for 30min to obtain mixture;

[0045] (5) the mixture obtained in step (4) is transferred to microwave heating furnace for microwave foaming to generate melamine foam plastic.

[0046] The mass ratio of formaldehyde solution, melamine, formaldehyde, polyvinyl butyral, polyester polyol, polyether modified polysiloxane copolymer, hydrophilic fullerene derivative, surfactant, foaming agent, mercaptopropionic acid isopropyl ester and liquid curing agent is 1:0.35:0.3:0.03:0.03:0.008:0.7:0.1:0.8:0.05.

[0047] The fullerene body of the hydrophilic fullerene derivative contains carbon cage containing 50 to 120 carbon atoms, the hydrophilic fullerene derivative contains 1 to 6 flexible ether oxygen chains, and the addition site of methylene on the fullerene is one of [5,6] and [6,6]; the structural formula is:

[0048]

[0049] Wherein R1 is carbonyl, R2 is aromatic group;

[0050] Wherein n is any number between 1 and 3.

[0051] In step (2), the surfactant is sodium dodecyl sulfonate.

[0052] In step (2), the foaming agent is a mixture of azobis isobutyronitrile and polyphenyl polyformaldehyde polyisocyanate; the mass ratio of the two is 1:1.5.

[0053] In step (5), the microwave frequency of the microwave foaming furnace is 3500 MHz, the power is 600 W, and the microwave foaming time is 8 min.

[0054] Example 3

[0055] A preparation process of a low-density high-stretch melamine foam plastic, comprising the following steps:

[0056] (1) melamine is added into a formaldehyde solution, triethanolamine is used to adjust the pH value to 10, heating to 80℃ for 60 min to generate melamine formaldehyde resin, polyvinyl butyral, polyester polyol and polyether modified polysiloxane copolymer are added while stirring, nitrogen is introduced, hydrophilic fullerene derivative is slowly added, and the reaction is continued for 60 min, concentrated hydrochloric acid is added to adjust the pH to neutral, and then dehydrated; then it is frozen in low temperature of minus 48℃ for 120 min, and thawed at room temperature to obtain modified melamine resin;

[0057] (2) the modified melamine resin obtained in step (1) is mixed with surfactant and foaming agent to obtain a first material, which is ready for use;

[0058] (3) mercaptopropionic acid isopropyl ester is mixed with liquid curing agent to obtain a second material, which is ready for use;

[0059] (4) the first material obtained in step (2) is continuously stirred for 3 h, preheated to 45℃, then the second material obtained in step (3) is added, and the stirring is continued for 40 min to obtain a mixture;

[0060] (5) the mixture obtained in step (4) is transferred to a microwave heating furnace for microwave foaming to generate melamine foam plastic.

[0061] The mass concentration of the formaldehyde solution is 25%, and the mass ratio of melamine, formaldehyde, polyvinyl butyral, polyester polyol, polyether modified polysiloxane copolymer, hydrophilic fullerene derivative, surfactant, foaming agent, mercaptopropionic acid isopropyl ester, and liquid curing agent is 1:0.45:0.2:0.04:0.02:0.015:0.5:0.2:0.7:0.1.

[0062] The fullerene body of the hydrophilic fullerene derivative contains a carbon cage containing 50 to 120 carbon atoms, the hydrophilic fullerene derivative contains 1 to 6 flexible ether oxygen chains, and the addition site of methylene on the fullerene is one of [5, 6] and [6, 6]; the structural formula is:

[0063]

[0064] wherein R1 is carbonyl, and R2 is substituted aromatic group;

[0065] wherein n is any number between 1 and 3.

[0066] In step (2), the surfactant is sodium dodecyl sulfonate.

[0067] In step (2), the foaming agent is a mixture of azobisisobutyronitrile and polyphenylpolymethylene polyisocyanate; the mass ratio of the two is 1.2:1.

[0068] In step (5), the microwave frequency of the microwave foaming furnace is 3000 MHz, the power is 800 W, and the microwave foaming time is 5 min.

[0069] Comparative Example 1

[0070] The hydrophilic fullerene derivative in Example 1 is replaced by a conventional C60 fullerene, and the rest of the proportions and preparation methods remain unchanged.

[0071] Comparative Example 2

[0072] The low-temperature freezing step in Example 1 is removed, and the rest of the proportions and preparation methods remain unchanged.

[0073] The physical properties of the melamine foams prepared in Examples 1-3 and Comparative Examples 1-2 were detected (the detection standards were GB / T6343-2009, GB / T6344-2008 and GB / T10808-2006, respectively), and the following detection results were obtained. The specific detection results are shown in Table 1.

[0074] Table 1 Physical property detection results of melamine foams prepared in Examples 1-3 and Comparative Examples 1-2

[0075] Density (kg / m 3 )]]> Tensile strength (kPa) Elongation at break (%) Tear strength (N / m) Example 1 10 312 33 90 Example 2 11 307 30 83 Example 3 10 315 34 92 Comparative Example 1 10 113 12 54 Comparative Example 2 10 232 23 72

[0076] From the above test data, it can be known that the melamine foam prepared by the present application has the significant characteristics of low density and high tensile strength.

[0077] The above description is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the present application within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A preparation process for low-density, high-tensile melamine foam, characterized in that, Includes the following steps: (1) Melamine is added to formaldehyde solution, and the pH value is adjusted to 9-10 with triethanolamine. The mixture is heated to 80-90℃ and reacted for 50-60 min to generate melamine-formaldehyde resin. Polyvinyl butyral, polyester polyol and polyether-modified polysiloxane copolymer are added while stirring. Nitrogen gas is introduced and hydrophilic fullerene derivative is slowly added. The reaction is continued for 60-90 min. Concentrated hydrochloric acid is added to adjust the pH to neutral and dehydrate the mixture. Then it is placed in a low temperature of -40℃ for 120-150 min and thawed at room temperature to obtain modified melamine resin. (2) Mix the modified melamine resin obtained in step (1) with surfactant and foaming agent and stir evenly to obtain the first material for later use; (3) Mix isooctyl mercaptopropionate with liquid curing agent until homogeneous to obtain the second material, and set aside. (4) Stir the first material obtained in step (2) for 2-3 hours, preheat to 45-50°C, then add the second material obtained in step (3), and continue stirring for 30-40 minutes to obtain a mixture; (5) The mixture obtained in step (4) is transferred to a microwave heating furnace for microwave foaming to generate melamine foam plastic; The formaldehyde solution has a mass concentration of 25-30%, and the mass ratio of melamine, formaldehyde, polyvinyl butyral, polyester polyol, polyether-modified polysiloxane copolymer, hydrophilic fullerene derivative, surfactant, foaming agent, isooctyl mercaptopropionate, and liquid curing agent is 1:0.35-0.45:0.2-0.3:0.03-0.04:0.02-0.03:0.008-0.015:0.5-0.7:0.1-0.2:0.7-0.8:0.05-0.1; The hydrophilic fullerene derivative has a fullerene body containing 50 to 120 carbon atoms, and the hydrophilic fullerene derivative contains 1 to 6 flexible ether oxygen chains. The addition site on the fullerene containing the methylene group is one of [5, 6] and [6, 6]. The structural formula is: ； Where R1 and R2 are one of carbonyl, aromatic, substituted aromatic groups, or any combination thereof; Where n takes any number between 1 and 3; In step (2), the surfactant is sodium dodecyl sulfonate; the foaming agent is a mixture of azobisisobutyronitrile and polyphenyl polymethylene polyisocyanate, with a mass ratio of azobisisobutyronitrile and polyphenyl polymethylene polyisocyanate of 1:

1. In step (5), the microwave frequency of the microwave foaming oven is 3000-3500MHz, the power is 600-800W, and the microwave foaming time is 5-8min.

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