Preparation method of melamine foam component with adjustable and controllable density

Abstract

The invention belongs to the technical field of material processing, and particularly relates to a preparation method of a melamine foam component with adjustable and controllable density. The preparation method comprises the following steps: foaming a melamine formaldehyde resin solution in a microwave radiation field to form light melamine foam, cooling the light melamine foam, and cutting the cooled light melamine foam into cuboid plates by a cutting machine; soaking the plate in an aqueous solution containing 0-5% of silane or siloxane hydrolysate or slurry with 0-25% of solid phase volume content to improve the surface performance of the plate; placing the foam fully absorbed with the aqueous solution in a hot-pressing mold with a top cover with a large number of through holes; performing hot-pressing treatment on the plate by adopting a hot press, and adjusting the density and shape of the plate by controlling the distance between an upper metal hot-pressing plate and a lower metal hot-pressing plate of the hot press; and a vibration cutting machine or a carving machine is used for carrying out appearance machining on the hot-pressed plate, the final density-adjustable melamine foam component is obtained, the density range of the density-adjustable melamine foam component is 10-100 kg / m < 3 >, and the density uniformity of the product can be effectively controlled through the method.

Description

Technical Field

[0001] The invention belongs to the technical field of material processing, and in particular relates to a method for preparing a melamine foam component with adjustable and controllable density. Background Art

[0002] Melamine foam, also known as melamine foam, is a new type of polymer material with a high open porosity (at least 98%) formed by curing and foaming melamine formaldehyde resin. The melamine foam prepared by microwave foaming technology has the characteristics of orderly internal network structure, low and uniform density, stable physical properties, and good sound absorption and noise reduction functions. In view of these advantages, melamine foam has been widely used in industry, construction, transportation, aviation and aerospace fields. With the continuous improvement of the performance of melamine foam and the verification of its reliability in practical applications, this material has been used for lightweight components in the aerospace field in recent years. However, although the density of high-open-cell melamine foam produced by microwave foaming technology is usually 5 to 8 kg / m 3 It can meet the needs of daily construction and industrial fields, but it is insufficient for the elasticity and thermal insulation performance of higher density melamine foam required in the aviation and aerospace fields. The usual method from low density to high density is hot pressing, including the following methods.

[0003] Single-step hot pressing method: This is the simplest hot pressing method, suitable for small products or products with a single density requirement. It completes the entire hot pressing process by heating and pressing once. The process is simple and easy, but it may not meet complex density requirements.

[0004] Multi-stage hot pressing method: In order to improve the density controllability of foam materials and the quality of the final product, the multi-stage hot pressing method is gradually being adopted. This method includes multiple steps such as preheating, main heating, pressurization and cooling. By finely controlling the temperature, pressure and time of each stage, the density of the material can be precisely controlled.

[0005] Continuous hot pressing method: For large-scale production and production lines that require continuous supply, continuous hot pressing method is more suitable. This method uses continuous heating and pressurizing devices to achieve continuous flow and shaping of materials, and is suitable for producing long or continuous foam sheets.

[0006] Vacuum hot pressing: In order to further improve product quality and density consistency, vacuum hot pressing is widely used in high-end products. By hot pressing in a vacuum environment, the air content inside the material can be effectively reduced, thereby improving the density and physical properties of the product.

[0007] Composite hot pressing method: For plastic foam products that require special properties, such as products with fireproofing, heat insulation and other functions, composite hot pressing method is an ideal solution. This method usually adds other functional materials or coatings during the hot pressing process to enhance the comprehensive performance of the foam material.

[0008] The above method is usually suitable for components with small thickness. For thick foam components, due to the thermal insulation properties of the foam itself, high temperature cannot be transmitted to the inside, and the density of the foam after hot pressing is uneven. Summary of the invention

[0009] To solve the above problems, the present invention provides a method for preparing a melamine foam component with adjustable and controllable density, which can achieve precise control of the density of the melamine foam component with adjustable density and realize the requirements for rapid and high-precision shape processing of melamine foam boards.

[0010] The present invention provides a method for preparing a melamine foam component with adjustable and controllable density, comprising the following steps in order:

[0011] a. The melamine formaldehyde resin solution is foamed in a microwave radiation field to obtain a microwave foamed lightweight melamine foam, wherein the microwave foamed lightweight melamine foam has a density of 5 to 10 kg / m 3 ;

[0012] b. The microwave foamed lightweight melamine foam is cooled, and the cooled microwave foamed lightweight melamine foam is divided into a cuboid material, a cylindrical material or a contoured material by a cutting machine to obtain a cut foam material;

[0013] c. Then, the cut foam material is immersed in an aqueous solution or an aqueous slurry to obtain a foam that is fully absorbed by the aqueous solution or the aqueous slurry; the aqueous solution includes organic silane and / or siloxane hydrolyzate; the aqueous slurry includes solid phase powder, silane and siloxane hydrolyzate; the weight content of silane or siloxane in the aqueous solution is 0-5%; the solid phase powder in the aqueous slurry is nano silicon oxide, fumed silicon dioxide, aluminum oxide or silicon carbide, and the solid content of the aqueous slurry is 0-25% of the volume of the aqueous slurry; the weight content of silane or siloxane in the aqueous slurry is 0-5%;

[0014] d. The foam filled with aqueous solution or aqueous slurry is loaded into a hot pressing mold, the top cover of the hot pressing mold has a through hole, the aperture of the through hole is The number of through holes is 100 to 10,000 per m 2 ;

[0015] e. hot pressing the foam absorbed with the aqueous solution or aqueous slurry using a hot press, adjusting the density and shape of the hot-pressed sheet by controlling the distance between the upper and lower metal hot-pressing plates of the hot press to obtain a hot-pressed sheet;

[0016] f. Using a vibration cutting machine and an engraving machine to shape the hot pressed sheet to obtain a melamine foam member with adjustable and controllable density;

[0017] g. Measuring the density of the adjustable and controllable melamine foam member, the density of the adjustable and controllable melamine foam member is 10 to 100 kg / m 3 , measure the density of the hot pressed sheet scraps removed during the shape processing, and the difference between the maximum density and the minimum density of the hot pressed sheet scraps shall not exceed 0.2kg / m 3 .

[0018] Preferably, the hot pressing of the foam absorbed with the aqueous solution using a hot press comprises a preheating stage, a pressurizing stage and a cooling and pressure relief stage performed in sequence, the temperature of the preheating stage is 110-180°C, the temperature of the pressurizing stage is 200-300°C, the cooling and pressure relief stage is naturally cooled in the air, and the pressure of the hot pressing is adjusted according to the density setting; the bottom plate, top cover and side plates of the hot press are heatable, the bottom plate and the side plates constitute a fixed mold cavity, and the top cover has pores for water replenishment and ventilation during the hot pressing process; the time of the hot pressing is regulated according to the steam escape process, and is maintained for 3-15 minutes after the steam escapes completely.

[0019] The present invention adjusts the compression rate of the plate-like melamine foam by hot pressing, thereby realizing the transformation of microwave-foamed lightweight melamine foam into high-density matured foam, effectively solving the defects of microwave-foamed melamine foam such as internal rawness, powder loss, and low tensile tear strength, thereby realizing the elastic performance index of the density-adjustable melamine foam component. After the hot pressing is completed, the melamine foam has a certain rebound. The traditional hot pressing method will result in inconsistent rebound rates at different positions, causing the problem of poor long-term shape-maintaining ability of the product. The present method can improve the uniformity of the internal and external density of the foam component, and no non-uniform deformation will occur during placement or service. DETAILED DESCRIPTION

[0020] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0021] Example 1 Preparation density is 20kg / m 3 of Melamine foam components

[0022] (1) The melamine formaldehyde resin solution is foamed in a microwave radiation field to obtain a microwave foamed lightweight melamine foam with a density of 5 kg / m 3 ;

[0023] (2) cooling the microwave foamed lightweight melamine foam, and cutting the cooled microwave foamed lightweight melamine foam into 330×330×96 mm plate materials by a cutting machine to obtain cut foam materials;

[0024] (3) then soaking the cut foam material in distilled water to obtain foam that is fully absorbed by water;

[0025] (4) The foam fully absorbed with water is placed in a 330×330 mm square hot pressing mold. The top cover of the mold has a through hole and the side has a scale. The aperture of the through hole is The number of through holes is 900 / m 2 ;

[0026] (5) hot pressing the foam fully absorbed with water using a hot press, wherein the temperature in the preheating stage is 130° C. for 10 min, the temperature in the pressurizing stage is 220° C., and the hot pressing time is maintained for 5 min after the steam escapes completely. The density of the sheet is adjusted by controlling the distance between the upper and lower metal hot pressing plates of the hot press to 20 mm. During the hot pressing process, the water in the foam boils and turns into water vapor, which escapes through the pores of the top cover to achieve foam drying, and then naturally cools and releases the pressure in the air to obtain a hot pressed sheet;

[0027] (6) After the hot pressing, the hot pressed sheet was taken out and placed at room temperature for 48 hours. The thickness of the hot pressed sheet rebounded from 20 mm to 24 mm. The hot pressed sheet was layered using sand wire cutting to form two square sheets of 330×330×12 mm. The upper and lower surfaces of the square sheets were processed using a grinder to ensure a thickness of 10 mm. The sheets were then processed into 18 The circular component is used to obtain a melamine foam component with adjustable and controllable density;

[0028] (7) Randomly select 10 circular components, weigh their masses, and divide them by their volumes to obtain densities of 19.9 kg / m 3 , 20.1kg / m 3 , 20.1kg / m 3 , 20kg / m 3 、19.9kg / m 3 、19.9kg / m 3 , 20kg / m 3 , 20kg / m 3 , 20.1kg / m 3 and 19.9kg / m 3 The average density of the components is 20kg / m3 , the fluctuation range is ±0.1kg / m 3 .

[0029] (8) Five of the circular components were vacuum packaged using an aluminum-plastic composite film to obtain five foam vacuum insulation panels with an average thermal conductivity of 0.002 W / m·K.

[0030] Example 2 Preparation density is 50kg / m 3 The hydrophobic melamine foam threaded cylindrical component has an outer thread centerline diameter of 400mm, an inner thread centerline diameter of 300mm, a height of 20mm, inner and outer sides are threaded, and a thread width of 4mm.

[0031] (1) The melamine formaldehyde resin solution is foamed in a microwave radiation field to obtain a microwave foamed lightweight melamine foam with a density of 10 kg / m 3 ;

[0032] (2) cooling the microwave foamed lightweight melamine foam, and processing the cooled microwave foamed lightweight melamine foam into a cylindrical material with an outer diameter of 400 mm, an inner diameter of 300 mm, and a height of 100 mm by a cutting machine to obtain a cut foam material;

[0033] (3) then immersing the cut foam material in an aqueous solution, wherein the aqueous solution includes an organic silane or a siloxane hydrolyzate, wherein the weight content of the silane or siloxane in the aqueous solution is 2.75%, to obtain a foam fully absorbed by the aqueous solution;

[0034] (4) The foam fully absorbed by the aqueous solution is squeezed into a hot pressing mold. Both the inner mold and the outer mold are heated. The top cover of the mold has a through hole and the side has a scale. The diameter of the through hole is 2 mm, and the number of through holes is 10,000 / m 2 ;

[0035] (5) using a top cover to squeeze the foam fully absorbed by the aqueous solution, the foam is subjected to hot pressing after entering the mold, the temperature of the preheating stage is 150° C., the time is 7 minutes, the temperature of the pressurizing stage is 240° C., the hot pressing time is maintained for 3 minutes after the steam escapes completely, and the distance between the top cover and the bottom plate of the mold is controlled to be 20 mm; during the hot pressing process, the water in the foam boils and turns into water vapor, which escapes through the pores of the top cover, thereby achieving foam drying, preheating and heating, and then naturally cooling and decompressing in the air to obtain a hot pressed sheet;

[0036] (6) After hot pressing, the hot pressed sheet is taken out and placed at room temperature for 48 hours, and then a vibration cutting machine is used to process the protrusions on the top surface of the cylindrical member caused by the exhaust holes;

[0037] (7) Weigh and measure the cylindrical components. The average density of the components is 50 kg / m 3, the water repellency reaches 98%.

[0038] Example 3 Preparation density is 100kg / m 3 , Melamine foam fireproof insulation board with dimensions of 600mm×400mm×10mm

[0039] (1) The melamine formaldehyde resin solution is foamed in a microwave radiation field to obtain a microwave foamed lightweight melamine foam with a density of 10 kg / m 3 ;

[0040] (2) cooling the microwave foamed lightweight melamine foam, and cutting the cooled microwave foamed lightweight melamine foam into 600 mm×400 mm×70 mm plate materials by a cutting machine to obtain cut foam materials;

[0041] (3) then immersing the cut foam material in an aqueous slurry, wherein the aqueous slurry includes a solid phase powder, silane and a siloxane hydrolyzate, wherein the solid phase powder in the aqueous slurry is fumed silica, the solid content of the aqueous slurry is 20% of the volume of the aqueous slurry, and the weight content of the siloxane in the aqueous slurry is 5%, to obtain a foam fully absorbed by the aqueous slurry;

[0042] (4) The foam fully absorbed with the aqueous slurry is placed in a 600 mm × 400 mm rectangular hot pressing mold. The top cover of the mold has through holes and the side has scales. The diameter of the through holes is 5 mm and the number of through holes is 2500 / m 2 ;

[0043] (5) hot pressing the foam absorbed with the aqueous slurry using a hot press, wherein the temperature in the preheating stage is 160° C. for 20 min, the temperature in the pressurizing stage is 260° C., and the hot pressing time is 5 min after the steam escapes completely. The density of the sheet is adjusted by controlling the distance between the upper and lower metal hot pressing plates of the hot press to 10 mm. During the hot pressing process, the water in the foam boils and turns into water vapor, which escapes through the pores of the top cover to achieve foam drying, and then naturally cools and releases the pressure in the air to obtain a hot pressed sheet;

[0044] (6) After hot pressing, the hot pressed sheet is taken out, placed at room temperature for 48 hours, and weighed and measured. The foam rebound elasticity is small, and then a vibration cutting machine is used to obtain a foam component;

[0045] (7) Weigh the mass of the foam component and divide it by the foam volume to obtain a density of 100 kg / m 3 , the water repellency reaches 98%, the thermal conductivity is 0.026W / mK, and the fire resistance is Class A melamine insulation foam components;

[0046] (8) The hot-pressed foam component is vacuum-packaged, and the packaging film material is an aluminum-plastic composite film material to obtain a foam nano-powder vacuum insulation board with an average thermal conductivity of 0.003 W / mK.

[0047] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a melamine foam component with adjustable and controllable density, characterized in that: The steps include the following sequence: a. The melamine formaldehyde resin solution is foamed in a microwave radiation field to obtain a microwave foamed lightweight melamine foam, wherein the density of the microwave foamed lightweight melamine foam is 5 to 10 kg / m 3 ; b. The microwave foamed lightweight melamine foam is cooled, and the cooled microwave foamed lightweight melamine foam is divided into a cuboid material, a cylindrical material or a contoured material by a cutting machine to obtain a cut foam material; c. Then, the cut foam material is immersed in an aqueous solution or an aqueous slurry to obtain a foam that is fully absorbed by the aqueous solution or the aqueous slurry; the aqueous solution includes organic silane and / or siloxane hydrolyzate; the aqueous slurry includes solid phase powder, silane and siloxane hydrolyzate; the weight content of silane or siloxane in the aqueous solution is 0-5%; the solid phase powder in the aqueous slurry is nano silicon oxide, fumed silicon dioxide, aluminum oxide or silicon carbide, and the solid content of the aqueous slurry is 0-25% of the volume of the aqueous slurry; the weight content of silane or siloxane in the aqueous slurry is 0-5%; d. The foam filled with aqueous solution or aqueous slurry is loaded into a hot pressing mold, the top cover of the hot pressing mold has a through hole, the aperture of the through hole is The number of through holes is 100 to 10,000 per m 2 ; e. hot pressing the foam absorbed with the aqueous solution or aqueous slurry using a hot press, adjusting the density and shape of the hot-pressed sheet by controlling the distance between the upper and lower metal hot-pressing plates of the hot press to obtain a hot-pressed sheet; f. Using a vibration cutting machine and an engraving machine to shape the hot pressed sheet to obtain a melamine foam member with adjustable and controllable density; g. Measuring the density of the adjustable and controllable melamine foam member, the density of the adjustable and controllable melamine foam member is 10 to 100 kg / m 3 , measure the density of the hot pressed sheet scraps removed during the shape processing, and the difference between the maximum density and the minimum density of the hot pressed sheet scraps shall not exceed 0.2kg / m 3 .

2. The preparation method according to claim 1, characterized in that: The hot pressing of the foam absorbed with the aqueous solution by using a hot press comprises a preheating stage, a pressurizing stage and a cooling and pressure relief stage, wherein the temperature of the preheating stage is 110-180° C., the temperature of the pressurizing stage is 200-300° C., the cooling and pressure relief stage is naturally cooled in the air, and the pressure of the hot pressing is adjusted according to the density setting; the bottom plate, the top cover and the side plates of the hot press are heatable, the bottom plate and the side plates constitute a fixed mold cavity, and the top cover has pores for water replenishment and ventilation during the hot pressing process; the time of the hot pressing is regulated according to the steam escape process, and is maintained for 3-15 minutes after the steam escapes completely.