A kind of temperature-controllable microsphere foaming agent and preparation method thereof

Abstract

The present invention provides a controllable temperature microsphere foaming agent and a preparation method and application thereof. The controllable temperature microsphere foaming agent comprises a packaging material and a core material located inside the packaging material, with urea-formaldehyde resin as the packaging material and triazene polymer as the core material. The foaming temperature can be precisely controlled, and the foaming starting temperature is 220°C. In low-temperature operations, there is no need to worry about the failure of the microspheres due to damage to the packaging material, and the drawback of residual solvents affecting product performance in the prior art is avoided. The foaming temperature is close to the melting point of PVC, the foaming uniformity is excellent, the product purity is high, there is no residue, and it has excellent expansion performance.

Description

Technical Field

[0001] The invention relates to the technical field of foam material preparation, and in particular to a temperature-controllable microsphere foaming agent and a preparation method and application thereof. Background Art

[0002] Foaming materials refer to materials that are prepared by adding a foaming agent to the base material and some additives, and then using extrusion foaming, injection foaming and other technologies to fill the base with pores. Because there are a large number of tiny bubbles distributed in the plastic base, the foaming material has excellent properties such as low density, sound absorption, shock absorption and heat preservation, while also saving ingredients and resources. Common foaming materials include polyurethane foaming materials, polyvinyl chloride foaming materials and rubber foaming materials.

[0003] Foaming agent refers to a type of auxiliary agent added during the processing of foaming materials to release a large amount of gas when heated, so that the base material forms a cellular structure. It is a key component for the foaming of foaming materials. Foaming agents are mainly divided into chemical foaming agents and physical foaming agents. Chemical foaming agents are further divided into inorganic foaming agents and organic foaming agents. Inorganic foaming agents have the advantages of stable and delicate bubbles, but poor dispersibility in the matrix and a small application range. They are mainly used in low-foaming materials such as polyvinyl chloride and polystyrene. Organic foaming agents are developing rapidly and have many types. They have good dispersibility in the matrix, uniform and delicate bubbles, controllable dispersion temperature, and high foaming efficiency. However, organic foaming agents will rapidly release heat and decompose during foaming, resulting in uneven pores. Physical foaming agents refer to a type of foaming agent that produces gas through changes in its physical state, thereby causing the base material to have a porous structure. They have the characteristics of simple foaming process and low cost.

[0004] Microcapsules are tiny particles composed of a core material wrapped in a wall material. The wall material is generally a natural or synthetic polymer material, and the core material is a gas, liquid or solid. In the 1930s, American scholar Wurster first used the suspension method to prepare air microcapsules and successfully applied this method to drug preparation. With the continuous innovation of science and technology, microcapsule technology has developed rapidly in the following decades and has been widely used in the fields of medicine, chemical industry, food and cosmetics. Microcapsule foaming agent is a kind of physical foaming agent. Its wall material is generally a thermoplastic polymer and the core material is a low-boiling organic solvent. The application of microcapsule foaming agent is very wide. The most important thing is to use it as a foaming agent to reduce the density of the material. In addition, it can also be used as an additive. Microcapsule foaming agent foams evenly and finely. Compared with the foaming material prepared by a simple gas foaming agent, it has great advantages in strength, mechanics and other properties.

[0005] Patent CN112574465A proposes an expandable microsphere containing a chemical foaming agent and a preparation method thereof, which solves the problem of foaming agent leakage of expandable microspheres after a period of time, but its foaming uniformity needs to be further improved. Patent US20110123807A1 provides a preparation method of heat-expandable foaming microspheres with a core-shell structure, with a foaming agent as the core and a long-chain crosslinking agent as the shell, which increases the viscosity of the monomer and foaming agent mixture, and the prepared heat-expandable microspheres have uniform diameters, but because of the addition of acrylic ester long-chain crosslinking agents, the stable foaming temperature range is narrowed. Patent US7931967B2 provides a heat-expandable microsphere, the shell layer includes a polymerizable monomer copolymer and an organosilicon compound, because the addition of organosilicon functional groups avoids the agglomeration problem of foaming microsphere particles during the preparation process and foaming process, but the liquid increases the preparation cost, affects the polymerization reaction of the acrylic ester monomer and the inorganic particles bonded to the surface of the microspheres affect the purity of the microspheres.

[0006] Therefore, in order to better meet the needs of production and practical applications, it is necessary to provide a microsphere foaming agent with high purity and no residue, good foaming uniformity, controllable foaming starting temperature, and good expansion performance. Summary of the invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a microsphere foaming agent with high purity and no residue, good foaming uniformity, controllable foaming starting temperature, and excellent expansion performance to meet actual production needs.

[0008] To achieve this object, the technical solution of the present invention is as follows:

[0009] The present invention provides a controllable temperature microsphere foaming agent, wherein the packaging material of the controllable temperature microsphere foaming agent is urea-formaldehyde resin, and the core material is triazene polymer, wherein the triazene polymer has the following structure:

[0010]

[0011] Wherein, a is an integer of 1-7, and b is an integer of 1-5.

[0012] Furthermore, the method for preparing the triazene polymer comprises the following steps:

[0013] (1) 4,4'-diaminophenyl ether and hydrochloric acid are mixed and mechanically stirred to obtain a milky white turbid liquid, and then a sodium nitrite solution is added under ice bath conditions to obtain a light yellow transparent clear solution;

[0014] (2) Adjust the pH value to 9-10, add diamine to the product of step (1) under ice bath conditions, precipitate a beige solid, continue stirring and filter, and the product is a triazene polymer.

[0015] In some embodiments of the present invention, the molar ratio of 4,4'-diaminophenyl ether to diamine is 1:1-1.2 (for example, it can be 1:1, 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19, 1:1.2 or any value therein).

[0016] In some embodiments of the present invention, the concentration of the hydrochloric acid in step (1) is 40-60% (for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60% or any value therein).

[0017] In some embodiments of the present invention, the diamine in step (2) is anhydrous piperazine or 1,6-hexanediamine.

[0018] Furthermore, the preparation method of the controllable temperature microsphere foaming agent comprises the following steps:

[0019] (1) Mix urea and formaldehyde evenly and dissolve them in deionized water;

[0020] (2) heating the system and stirring it to obtain a prepolymer;

[0021] (3) adding the triazene polymer into the system, adding an emulsifier, and then dispersing it into a uniform and stable emulsion;

[0022] (4) Adjust the pH to 2-3, start polymerization, increase the temperature for aging reaction, and then adjust the pH to about 7-9, remove water, and obtain a microsphere foaming agent.

[0023] In some embodiments of the present invention, the molar ratio of urea to formaldehyde in step (1) is 1.5-2:1 (for example, it can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1 or any value therein), and the mass of deionized water is 2-4 times the sum of the masses of urea and formaldehyde (for example, it can be 2 times, 2.5 times, 3 times, 3.5 times, 4 times or any value therein).

[0024] In some embodiments of the present invention, the temperature of the system in step (2) is raised to 70-80°C (for example, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C or any value therein).

[0025] In some embodiments of the present invention, the mass of the triazene polymer described in step (3) is 8-9 times that of the packaging material (for example, it can be 8 times, 8.1 times, 8.2 times, 8.3 times, 8.4 times, 8.5 times, 8.6 times, 8.7 times, 8.8 times, 8.9 times, 9 times or any value therein); the emulsifier is PVA1788 or PVA1799.

[0026] In some embodiments of the present invention, the reaction temperature in step (4) is 40-60°C (for example, it can be 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C or any value therein).

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The temperature-controllable microsphere foaming agent provided by the present invention uses triazene polymer as the foaming agent, and the foaming temperature can be precisely controlled. It has a high foaming starting temperature. In low-temperature operations, there is no need to worry about the failure of the microspheres due to damage to the packaging material.

[0029] (2) The controllable temperature microsphere foaming agent provided by the present invention avoids the drawback of residual solvent in the prior art that affects product performance. The product has high purity, no residue, and excellent expansion performance.

[0030] (3) The temperature-controllable microsphere foaming agent provided by the present invention has a triazene polymer with a specific structure, and the foaming temperature is close to the melting point of PVC, and the foaming uniformity is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the IR spectrum of triazene polymer I-1-1;

[0032] Figure 2 is the TGA spectrum of triazene polymer I-1-1;

[0033] Figure 3 This is the IR spectrum of triazene polymer I-2-1. DETAILED DESCRIPTION

[0034] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, but not to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0035] Preparation of triazene polymer I-1-1

[0036] The preparation method is as follows:

[0037] (1) Dissolve 1 mol of 4,4'-diaminophenyl ether in 50% hydrochloric acid and mechanically stir for 30 min to obtain a milky white turbid liquid. Then, place the solution in an ice-water bath and stir to cool it down. Dissolve 1 mol of sodium nitrite in 5 ml of water. Add the sodium nitrite aqueous solution dropwise into the reaction flask. The turbid liquid gradually turns clear and finally turns into a light yellow transparent clear solution.

[0038] (2) The pH value was adjusted to 9-10. 1 mol of anhydrous piperazine was dissolved in 30 ml of water and then added to the product of step (1). The mixture was stirred vigorously in an ice bath. A large amount of beige solid was precipitated. After stirring and reacting for 1 h, the mixture was filtered, washed with water, and dried to obtain a brown solid, i.e., the triazene polymer I-1-1. The solid was subjected to IR infrared spectroscopy and thermogravimetric analysis. The results are shown in the attached drawings. Figure 1 , 2 .

[0039] Preparation of triazene polymer I-1-2

[0040] The preparation method is as follows:

[0041] (1) Dissolve 1 mol of 4,4'-diaminophenyl ether in 50% hydrochloric acid and mechanically stir for 30 min to obtain a milky white turbid liquid. Then, place the solution in an ice-water bath and stir to cool it down. Dissolve 1 mol of sodium nitrite in 5 ml of water. Add the sodium nitrite aqueous solution dropwise into the reaction flask. The turbid liquid gradually turns clear and finally turns into a light yellow transparent clear solution.

[0042] (2) The pH value was adjusted to 9-10. 1.2 mol of anhydrous piperazine was dissolved in 30 ml of water. The mixture was then added to the product of step (1). The mixture was stirred vigorously in an ice bath. A large amount of beige solid precipitated. The reaction was continued with stirring for 1 h. The mixture was filtered, washed with water, and dried to obtain a brown solid, which was the triazene polymer I-1-2.

[0043] Preparation of triazene polymer I-2-1

[0044] The preparation method is as follows:

[0045] (1) Dissolve 1 mol of 4,4'-diaminophenyl ether in 50% hydrochloric acid, stir mechanically for 30 minutes to obtain a milky white turbid liquid, then place in an ice water bath and stir to cool, dissolve 1 mol of sodium nitrite in 5 ml of water, and drop the sodium nitrite aqueous solution into the reaction flask. The reactant gradually changes from turbid liquid to clear, and finally becomes a light yellow transparent clear solution. After the sodium nitrite is added, continue to stir and react for 30 minutes;

[0046] (2) The pH value was adjusted to 9-10. 1 mol of 1,6-hexanediamine was dissolved in 30 ml of water and then added to the product of step (1). The mixture was stirred vigorously in an ice bath. A large amount of beige solid was precipitated. After stirring and reacting for 1 hour, the mixture was filtered, washed with water, and dried to obtain a brown solid, i.e., the triazene polymer I-2-1. The solid was subjected to IR infrared spectroscopy analysis. The results are shown in the attached figure. Figure 3 .

[0047] Preparation of triazene polymer I-2-2

[0048] The preparation method is as follows:

[0049] (1) Dissolve 1 mol of 4,4′-diaminophenyl ether in 50% hydrochloric acid and mechanically stir for 30 min to obtain a milky white turbid liquid. Then, place the solution in an ice-water bath and stir to cool it down. Dissolve 1 mol of sodium nitrite in 5 ml of water. Add the sodium nitrite aqueous solution dropwise into the reaction flask. The turbid liquid gradually turns clear and finally turns into a light yellow transparent clear solution.

[0050] (2) The pH value was adjusted to 9-10. 1.2 mol of 1,6-hexanediamine was dissolved in 30 ml of water. The mixture was then added to the product of step (1). The mixture was stirred vigorously in an ice bath. A large amount of beige solid was precipitated. The reaction was continued with stirring for 1 h. The mixture was filtered, washed with water, and dried to obtain a brown solid, which was the triazene polymer I-2-2.

[0051] Preparation of triazene polymer II

[0052] The preparation method is as follows:

[0053] (1) Dissolve 1 mol of 4,4′-diaminophenyl ether in 50% hydrochloric acid and mechanically stir for 30 min to obtain a milky white turbid liquid. Then, place the solution in an ice-water bath and stir to cool it down. Dissolve 1 mol of sodium nitrite in 5 ml of water. Add the sodium nitrite aqueous solution dropwise into the reaction flask. The turbid liquid gradually turns clear and finally turns into a light yellow transparent clear solution.

[0054] (2) The pH value was adjusted to 9-10. 1 mol of anhydrous ethylamine was dissolved in 30 ml of water. The mixture was then added to the product of step (1). The mixture was stirred vigorously in an ice bath. A large amount of beige solid was precipitated. The reaction was continued with stirring for 1 h. The mixture was filtered, washed with water, and dried to obtain a brown solid, which was triazene polymer II.

[0055] Example 1

[0056] A controllable temperature microsphere foaming agent is prepared by the following method:

[0057] (1) Mix 0.15 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0058] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0059] (3) Add 2 mol of triazene polymer I-1-1 into the system, add PVA1788, and then disperse into a uniform and stable emulsion;

[0060] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0061] Example 2

[0062] A controllable temperature microsphere foaming agent is prepared by the following method:

[0063] (1) Mix 0.15 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0064] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0065] (3) Add 2 mol of triazene polymer I-1-2 into the system, add PVA1788, and then disperse into a uniform and stable emulsion;

[0066] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0067] Example 3

[0068] A controllable temperature microsphere foaming agent is prepared by the following method:

[0069] (1) Mix 0.15 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0070] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0071] (3) Add 2 mol of triazene polymer I-2-1 into the system, add PVA1788, and then disperse into a uniform and stable emulsion;

[0072] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0073] Example 4

[0074] A controllable temperature microsphere foaming agent is prepared by the following method:

[0075] (1) Mix 0.15 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0076] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0077] (3) adding 2 mol of triazene polymer I-2-2 into the system, and adding PVA1788, and then dispersing into a uniform and stable emulsion;

[0078] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0079] Example 5

[0080] A controllable temperature microsphere foaming agent is prepared by the following method:

[0081] (1) Mix 0.2 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0082] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0083] (3) adding 2.4 mol of triazene polymer I-1-1 into the system, and adding PVA1799, and then dispersing into a uniform and stable emulsion;

[0084] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0085] Example 6

[0086] A controllable temperature microsphere foaming agent is prepared by the following method:

[0087] (1) Mix 0.2 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0088] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0089] (3) adding 2.4 mol of triazene polymer I-1-2 into the system, and adding PVA1799, and then dispersing into a uniform and stable emulsion;

[0090] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0091] Example 7

[0092] A controllable temperature microsphere foaming agent is prepared by the following method:

[0093] (1) Mix 0.2 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0094] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0095] (3) adding 2.4 mol of triazene polymer I-2-1 into the system, and adding PVA1799, and then dispersing into a uniform and stable emulsion;

[0096] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0097] Example 8

[0098] A controllable temperature microsphere foaming agent is prepared by the following method:

[0099] (1) Mix 0.2 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0100] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0101] (3) adding 2.4 mol of triazene polymer I-2-2 into the system, and adding PVA1799, and then dispersing into a uniform and stable emulsion;

[0102] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0103] Example 9

[0104] A controllable temperature microsphere foaming agent is prepared by the following method:

[0105] (1) Mix 0.18 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0106] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0107] (3) adding 2.3 mol of triazene polymer I-1-1 into the system, and adding PVA1788, and then dispersing into a uniform and stable emulsion;

[0108] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0109] Example 10

[0110] A controllable temperature microsphere foaming agent is prepared by the following method:

[0111] (1) Mix 0.18 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0112] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0113] (3) adding 2.52 mol of triazene polymer I-1-2 into the system, and adding PVA1788, and then dispersing into a uniform and stable emulsion;

[0114] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0115] Embodiment 11

[0116] A controllable temperature microsphere foaming agent is prepared by the following method:

[0117] (1) Mix 0.17 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0118] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0119] (3) adding 2.3 mol of triazene polymer I-2-1 into the system, and adding PVA1799, and then dispersing into a uniform and stable emulsion;

[0120] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0121] Example 12

[0122] A controllable temperature microsphere foaming agent is prepared by the following method:

[0123] (1) Mix 0.17 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0124] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0125] (3) adding 2.35 mol of triazene polymer I-2-2 into the system, and adding PVA1799, and then dispersing into a uniform and stable emulsion;

[0126] (4) adding dilute hydrochloric acid to adjust the pH to 2-3, starting polymerization, raising the temperature for aging reaction, adjusting the pH to about 7-9 with sodium hydroxide, removing water, and obtaining a controllable temperature microsphere foaming agent.

[0127] Comparative Example 1

[0128] A microsphere foaming agent is prepared by the following method:

[0129] (1) Mix 0.15 mol urea and 0.1 mol formaldehyde evenly and dissolve them in deionized water;

[0130] (2) heating the system to 70° C. and stirring to obtain a prepolymer;

[0131] (3) adding 2 mol of triazene polymer II into the system, and adding PVA1788, and then dispersing into a uniform and stable emulsion;

[0132] (4) Add dilute hydrochloric acid to adjust the pH to 2-3, start polymerization, increase the temperature for aging reaction, adjust the pH to about 7-9 with sodium hydroxide, remove water, and obtain a microsphere foaming agent.

[0133] Comparative Example 2

[0134] A microsphere foaming agent is prepared by the following method:

[0135] (1) Preparation of aqueous dispersion: 1 g of sodium hydroxide, 3.05 g of magnesium chloride hexahydrate, and 0.4 g of a 1 wt% sodium dodecyl sulfate aqueous solution were added to 27 g of deionized water in order, and the mixture was stirred vigorously for half an hour to form a stable suspension protective solution;

[0136] (2) Add 6 g acrylonitrile, 3 g methyl acrylate, 1 g vinyl acetate, 2.5 g blowing agent n-hexane, 0.18 g initiator AIBN and 0.044 g cross-linking agent EGDMA in a beaker in proportion, mix well, add to the water phase, stir vigorously for 15 min to obtain a stable suspension, seal, react at 62 ° C for 19 h, cool, discharge, wash with dilute hydrochloric acid to remove surface magnesium hydroxide, and place in a 50 ° C oven to dry to obtain a light yellow or white product, which is the microsphere foaming agent.

[0137] The microsphere foaming agent prepared in the above examples and comparative examples was placed on a glass slide and heated on a hot stage of a constant temperature controller. Then, a microscope was adjusted to observe the foaming process of the heat-expandable microspheres on the glass slide. The starting foaming temperature, the highest foaming temperature, the initial microsphere diameter, and the diameter of the expanded microspheres after foaming were recorded. The experimental results are shown in Table 1:

[0138] Table 1 Test results of relevant indicators of microsphere foaming agent in Examples and Comparative Examples

[0139]

[0140] Comparison of Comparative Example 1 with Example 1 shows that the controllable temperature microsphere foaming agent prepared in Example 1 uses triazene polymer as the core material, has a higher foaming temperature, and has good expansion performance. Comparison of Comparative Example 2 with Example 1 shows that compared with the conventional physical foaming method, the microsphere foaming agent prepared in Example 1 has a higher foaming starting temperature, and the foaming temperature is close to the melting point of the PVC material, and the foaming uniformity is good. Comprehensive comparison of the above embodiments and comparative examples shows that the controllable temperature microsphere foaming agent provided by the present invention uses triazene polymer as the foaming agent, and the foaming starting temperature can be accurately controlled at about 220°C, with a higher foaming starting temperature. In low-temperature operations, there is no need to worry about the failure of the microspheres due to the damage of the packaging material, which avoids the disadvantages of residual solvents in the prior art that affect product performance. The product has high purity, no residue, and excellent expansion performance. By designing a triazene polymer with a specific structure, the foaming temperature is close to the melting point of PVC, and the foaming uniformity is excellent.

[0141] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A controllable temperature microsphere foaming agent, characterized in that: The controllable temperature microsphere foaming agent comprises a packaging material and a core material located inside the packaging material, wherein the packaging material is a urea-formaldehyde resin, and the core material is a triazene polymer, wherein the triazene polymer is selected from the following compounds of Formula I-1 and / or Formula I-2: I-1； I-2； Wherein, a is an integer from 1 to 7, and b is an integer from 1 to 5; The method for preparing the triazene polymer comprises the following steps: (1) 4,4'-diaminophenyl ether and hydrochloric acid are mixed and mechanically stirred to obtain a milky white turbid liquid, and then sodium nitrite solution is added under ice bath conditions to obtain a light yellow transparent clear solution; (2) adjusting the pH value to 9-10, adding a diamine to the product of step (1) under ice bath conditions, precipitating a beige solid, continuing to stir and filter, and the product is a triazene polymer; The molar ratio of the 4,4'-diaminophenyl ether to the diamine is 1:1-1.

2.

2. The controllable temperature microsphere foaming agent according to claim 1, characterized in that: The concentration of the hydrochloric acid in step (1) is 40-60%.

3. The controllable temperature microsphere foaming agent according to claim 1, characterized in that: The diamine in step (2) is anhydrous piperazine or 1,6-hexanediamine.

4. The method for preparing the controllable temperature microsphere foaming agent according to any one of claims 1 to 3, comprising the following steps: (1) Mix urea and formaldehyde evenly and dissolve them in deionized water; (2) heating the system and stirring it to obtain a prepolymer; (3) adding the triazene polymer into the system and adding an emulsifier, and then dispersing it into a uniform and stable emulsion; (4) Adjust the pH value to 2-3, start polymerization, increase the temperature for aging reaction, and then adjust the pH to 7-9, remove the water, and obtain the microsphere foaming agent.

5. The method for preparing the controllable temperature microsphere foaming agent according to claim 4, characterized in that: The molar ratio of urea to formaldehyde in step (1) is 1.5-2:1, and the mass of deionized water is 2-4 times the sum of the mass of urea and formaldehyde.

6. The method for preparing the controllable temperature microsphere foaming agent according to claim 4, characterized in that: The system in step (2) is heated to 70-80°C.

7. The method for preparing the controllable temperature microsphere foaming agent according to claim 4, characterized in that: The mass of the triazene polymer described in step (3) is 8-9 times that of the packaging material, and the emulsifier is PVA1788 or PVA1799.

8. Use of the controllable temperature microsphere foaming agent according to any one of claims 1 to 3 in the field of foaming material preparation.

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