Fireproof capsule microbeads, polyurethane foam and preparation method

Abstract

This invention relates to fire-retardant capsule microbeads, polyurethane foam, and their preparation methods, belonging to the technical field of fire-retardant materials and their preparation methods. The preparation method of the fire-retardant capsule microbeads includes the following steps: S1: Stirring perfluorohexanone at a room temperature of 20°C or less; S2: Adding chitosan to the perfluorohexanone in batches until the mass ratio of perfluorohexanone to chitosan reaches 1:(2-3), obtaining a first mixture; S3: Adding benzylphenol polyoxyethylene ether formaldehyde condensate emulsion to the first mixture until the mass ratio of perfluorohexanone to benzylphenol polyoxyethylene ether formaldehyde condensate reaches 1:(0.3-0.5), obtaining a second mixture; S4: Encapsulating the second mixture with a microbead preparation process to obtain capsule microbeads. The technical solution of this invention can obtain polyurethane foam with fire-retardant effects while having minimal impact on the foam volume ratio of the polyurethane foam, thus maintaining good thermal insulation performance.

Description

Technical Field

[0001] This invention belongs to the technical field of fireproof materials and their preparation methods, specifically relating to fireproof capsule microbeads, polyurethane foam and their preparation methods. Background Technology

[0002] Common refrigeration equipment, such as refrigerators and freezers, typically uses polyurethane foam with a volume ratio of 35 to 60 for its insulation layer. This material is flammable and will cause the flame to expand and spread rapidly once it comes into contact with a fire source.

[0003] Based on this, existing technologies add flame retardants to polyurethane foam to give it fire-retardant properties. However, the addition of chemical flame retardants will seriously reduce the foam volume ratio of polyurethane foam materials, making it drop to 8-15. The thermal insulation performance of polyurethane foam prepared with such a foam volume ratio is greatly weakened, reducing the market competitiveness of the corresponding products. Summary of the Invention

[0004] To address the aforementioned technical problems, this application improves the formulation and morphology of flame retardants in polyurethane, aiming to obtain polyurethane foam that has a smaller impact on the foam volume ratio while still effectively providing fire retardant effects. One objective of this invention is to provide a method for preparing fire-retardant capsule microspheres; another objective is to provide corresponding fire-retardant capsule microspheres; and a third objective is to provide corresponding polyurethane foam and its preparation method.

[0005] The specific technical solution is explained below:

[0006] The preparation method of fire-resistant capsule microbeads includes the following steps:

[0007] S1: Stir perfluorohexanone at room temperature (20°C or lower);

[0008] S2: Add chitosan to perfluorohexanone in batches until the mass ratio of perfluorohexanone to chitosan reaches 1:(2~3) to obtain the first mixture;

[0009] S3: Add benzylphenol polyoxyethylene ether formaldehyde condensate emulsion to the first mixture until the mass ratio of perfluorohexanone to benzylphenol polyoxyethylene ether formaldehyde condensate reaches 1:(0.3~0.5), to obtain the second mixture;

[0010] S4: Capsule microbeads are prepared by using a microbead preparation process to encapsulate the second mixture with the capsule wall material.

[0011] In the above technical solution, the core flame-retardant and fire-extinguishing component is perfluorohexanone. When the prepared capsule microbeads rupture upon contact with fire, perfluorohexanone is released, absorbs heat, and volatilizes to extinguish the fire and prevent its spread. At the same time, perfluorohexanone is a safe and non-toxic fire extinguishing material.

[0012] The role of chitosan is to improve the stability of perfluorohexanone. Perfluorohexanone is prone to volatilization at low temperatures. Adding chitosan can reduce its volatilization. The chitosan is added in batches to obtain a first mixture with better homogeneity.

[0013] The benzylphenol polyoxyethylene ether formaldehyde condensate emulsion will encapsulate the stabilized perfluorohexanone, forming a suspension with relatively high viscosity, so that the second mixture meets the requirements of the microbead preparation process and facilitates the production of capsule microbeads.

[0014] Preferably, in step S2, the mass ratio of perfluorohexanone to chitosan added in each batch is 1:(0.1 to 0.3).

[0015] Preferably, in step S3, the addition rate of the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is 300-500 ml / min.

[0016] Preferably, in step S4, the capsule wall material is made of a mixture of polyvinyl alcohol and gelatin, with a mass ratio of polyvinyl alcohol to gelatin of 1:(0.3 to 0.5).

[0017] Polyvinyl alcohol and gelatin do not react with the raw materials for polyurethane foam preparation, ensuring the stability of the capsule microbeads during the polyurethane foam preparation process and reducing the impact on the polyurethane foam preparation process. The rupture temperature of the capsule wall material is approximately 100–150°C.

[0018] Preferably, in step S4, the capsule wall material is polyester or polyamide. These capsule wall materials have a relatively high rupture temperature, which can reach 200-250°C, allowing for higher storage and use temperatures for the capsule microbeads and expanding their application range. However, the triggering temperature of this capsule wall material is relatively high, which is not conducive to preventing the initial flame from burning. It requires a certain burning time or a higher temperature to release the extinguishing agent.

[0019] Fire-resistant capsule microbeads are prepared by the preparation method described in any of the above technical solutions.

[0020] Polyurethane foam, including the aforementioned fire-retardant capsule microbeads.

[0021] Preferably, polyurethane foam is used as the insulation layer for refrigeration equipment.

[0022] The preparation method of polyurethane foam includes the following steps:

[0023] One of the combined polyether and isocyanate is stirred, and the above-mentioned fire-retardant capsule microbeads are added during the stirring process. After stirring evenly, the other of the combined polyether and isocyanate is added, and the reaction is carried out to obtain polyurethane foam.

[0024] Preferably, the mass ratio of the fire-retardant capsule microbeads to the combined polyether and the isocyanate is 1:(1-4):(1-4).

[0025] In summary, the technical solution described in this invention has the following main beneficial effects:

[0026] Compared with the prior art, the technical solution of the present invention can obtain polyurethane foam with fire-retardant effect, while having little impact on the foaming volume ratio of polyurethane foam, so that it still has good thermal insulation performance.

[0027] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Attached Figure Description

[0028] Figure 1 These are diagrams showing the porosity and flame retardant status of the polyurethane foams prepared in Examples 1-4. Detailed Implementation

[0029] The present invention will be further explained in conjunction with the embodiments:

[0030] The core technical problem faced by the technical solution of this application embodiment stems from the inventor's accurate understanding of the prior art. Therefore, how to obtain polyurethane foam that has both fire-retardant and flame-retardant effects and has little impact on the volume ratio of polyurethane foam is a technical problem that the inventor urgently needs to solve.

[0031] It should be noted that the embodiments do not constitute a limitation on the scope of protection of the claims of this invention. All technical solutions that can be reasonably expected by those skilled in the art based on the technical concepts provided / proved by the embodiments should be covered within the scope of protection of the claims of this invention.

[0032] The specific implementation examples are detailed below:

[0033] First, the preparation method of the fire-retardant capsule microbeads and the corresponding polyurethane foam material in the embodiment is as follows:

[0034] 1. Place perfluorohexanone into a stirrer at a temperature below 20°C, start the stirrer, and stir at 250-450 rpm for 1-2 minutes.

[0035] 2. Begin by adding chitosan in several batches. The mass ratio of chitosan to perfluorohexanone (PFH):chitosan should be 1:0.1–0.3 each time. After each addition of chitosan, stir for 2–3 minutes until the mixture is homogeneous. Then, add another equal amount of chitosan and continue stirring until the mass ratio of chitosan to PFH is 1:2–3. During stirring, maintain the temperature of the mixture inside the stirrer below 25°C and keep the stirring speed at 250–450 rpm.

[0036] 3. Slowly add the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion, so that the mass ratio of perfluorohexanone to benzylphenol polyoxyethylene ether formaldehyde condensate is 1:0.3-0.5. The addition rate of the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is 300-500 ml / min. After the addition is completed, continue stirring for 15-25 min. The temperature of the turbid liquid in the stirrer should not exceed 25℃, and the stirring speed should be 250-450 rpm.

[0037] 4. The turbid liquid prepared in the above steps is used to prepare the capsule core by solution polymerization.

[0038] 5. Use a mixture of polyvinyl alcohol and gelatin with a mass ratio of 1:0.3 to 0.5 as the capsule wall material, or use polyester or polyamide as the capsule wall material, and use a microbead physical preparation process (spray method and spray coagulation method) to encapsulate the above core to prepare capsule microbeads with a particle size of 5 to 300 μm.

[0039] 6. At an ambient temperature of 25 degrees Celsius, place one of the polyether or isocyanate components into a stirrer and start stirring at a speed of 50-150 rpm. During the stirring process, add the above-mentioned capsule microbeads. Continue stirring at a speed of 50-150 rpm for more than 10 minutes to achieve uniform distribution of the microbead capsules in the turbid liquid.

[0040] 7. Add the other component of the polyether or isocyanate combination to the suspension prepared in step 6. The mass ratio of the isocyanate component to the polyether combination is 1:1. At this time, the stirring speed is 200-250 rpm and the stirring time is less than 1 min. When the polyether combination and isocyanate come into contact, a chemical reaction will occur, releasing gas and heat to form polyurethane foam.

[0041] The specific preparation methods of the polyurethane foam described in Examples 1-4 are as follows:

[0042] 1. Place perfluorohexanone into a stirrer at a temperature below 20°C, start the stirrer, and stir at 350 rpm for 2 minutes.

[0043] 2. Begin by adding chitosan in batches, with the mass ratio of chitosan to perfluorohexanone (PFH):chitosan = 1:0.2 each time. Stir for 3 minutes after each addition of chitosan, ensuring the mixture is homogeneous. Repeat this process until the mass ratio of chitosan to PFH is 1:2.6. During stirring, maintain the temperature of the mixture inside the stirrer below 25°C and keep the stirring speed at 350 rpm.

[0044] 3. Slowly add benzylphenol polyoxyethylene ether formaldehyde condensate emulsion (model PPB150) from Sorpol Corporation of Japan via injection, so that the mass ratio of perfluorohexanone to benzylphenol polyoxyethylene ether formaldehyde condensate is 1:0.4. The addition rate of the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is 350 ml / min. After the addition is completed, continue stirring for 20 min. The temperature of the turbid liquid in the stirrer should not exceed 25℃, and the stirring speed is 350 rpm.

[0045] 4. The turbid liquid prepared in the above steps is used to prepare the capsule core by solution polymerization.

[0046] 5. Using a mixture of polyvinyl alcohol and gelatin at a mass ratio of 1:0.4 as the capsule wall material, the above core is encapsulated using a spray coagulation method to prepare capsule microbeads with a particle size of 10-150 μm.

[0047] 6. At an ambient temperature of 25 degrees Celsius, place the combined polyether component into a stirrer and start stirring at a speed of 100 rpm. During the stirring process, add the above-mentioned capsule microbeads. Continue stirring at a speed of 100 rpm for more than 10 minutes to achieve uniform distribution of the microbead capsules in the turbid liquid.

[0048] 7. Add isocyanate component to the suspension prepared in step 6. The mass ratio of isocyanate component to polyether is 1:1. At this time, the stirring speed is 200 rpm and the stirring time is less than 1 min. When the polyether and isocyanate come into contact, a chemical reaction will occur, releasing gas and heat to form polyurethane foam.

[0049] Example 1:

[0050] In the above preparation method, the mass ratio of microbeads:polyether:isocyanate is 1:2:2. Please refer to the appendix of the instruction manual for details. Figure 1 The third example from the left shows that the polyurethane foam has good porosity uniformity, which means it has good thermal insulation performance, and the extinguishing agent released by the added fire extinguishing capsule can prevent continued combustion and prevent the fire from spreading.

[0051] Example 2:

[0052] In the above preparation method, the mass ratio of microbeads:polyether:isocyanate is 1:4:4. Please refer to the appendix of the instruction manual for details. Figure 1 The second example from the left has good foam porosity, but the extinguishing agent released by the added fire extinguishing capsule is not effective in stopping the flame from continuing to burn.

[0053] Example 3:

[0054] In the above preparation method, the mass ratio of microbeads:polyether:isocyanate is 2:3:3. Please refer to the appendix of the instruction manual for details. Figure 1 The fourth example from the left shows that the foam porosity has pores and poor pore uniformity, which means that the heat insulation performance is relatively poor. The fire extinguishing agent released by the added fire extinguishing capsule can significantly prevent the flame from burning.

[0055] Example 4:

[0056] In the above preparation method, the mass ratio of microbeads:polyether:isocyanate is 1:1:1. Please refer to the appendix of the instruction manual for details. Figure 1 The fifth example from the left shows a foam with large pores and extremely poor pore uniformity, which means it has very poor thermal insulation performance. The extinguishing agent released by the added fire extinguishing capsule can prevent flames from forming.

[0057] Instruction manual attached Figure 1 In the middle, the first one from the left is polyurethane foam without microbeads, which does not have flame retardant properties.

[0058] Example 5:

[0059] The only difference from Example 1 is that in step 2 of the preparation method, the mass ratio of perfluorohexanone to chitosan is 1:2.

[0060] Example 6:

[0061] The only difference from Example 1 is that in step 2 of the preparation method, the mass ratio of perfluorohexanone to chitosan is 1:3.

[0062] Comparative Example 1:

[0063] The only difference from Example 5 is that in step 2 of the preparation method, the mass ratio of perfluorohexanone to chitosan is 1:1.8.

[0064] Comparative Example 2:

[0065] The only difference from Example 6 is that in step 2 of the preparation method, the mass ratio of perfluorohexanone to chitosan is 1:3.2.

[0066] The same combustion tests as those in Examples 1-4 were performed on Examples 5-6 and Comparative Examples 1-2, and the results showed that:

[0067] The polyurethane foams corresponding to Examples 5 and 6 have a similar degree of foam pore distribution as Example 1, and can also prevent the spread of fire.

[0068] The polyurethane foam corresponding to Comparative Example 1, although it also has a pore distribution degree equivalent to that of Example 1, has a reduced flame retardancy against fire spread, which is comparable to that of Example 2. This may be because when the relative content of chitosan is reduced to this extent, the amount of perfluorohexanone volatilized during the preparation process is large, which greatly reduces the flame retardant performance of the product.

[0069] The polyurethane foam corresponding to Comparative Example 2 also has a pore distribution degree equivalent to that of Example 1. However, its flame retardancy against fire spread is also reduced, which is similar to that of Example 2. The specific reason is not very clear. After analysis, the inventors believe that it may be because as the relative content of chitosan increases, the gel properties of chitosan itself have become an obstacle to the volatilization rate of perfluorohexanone.

[0070] Example 7:

[0071] The only difference from Example 1 is that in step 3 of the preparation method, the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is added at a rate of 300 ml / min.

[0072] Example 8:

[0073] The only difference from Example 1 is that in step 3 of the preparation method, the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is added at a rate of 500 ml / min.

[0074] Comparative Example 3:

[0075] The only difference from Example 7 is that in step 3 of the preparation method, the addition rate of the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is 250 ml / min.

[0076] Comparative Example 4:

[0077] The only difference from Example 8 is that in step 3 of the preparation method, the addition rate of the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is 550 ml / min.

[0078] The same combustion tests as those in Examples 1-4 were performed on Examples 7-8 and Comparative Examples 3-4, and the results showed that:

[0079] Regarding the indicator of the degree of foam pore distribution, Examples 7-8 and Comparative Examples 3-4 are comparable to Example 1, with no significant difference;

[0080] The polyurethane foams corresponding to Examples 7 and 8 were also able to prevent the spread of fire;

[0081] The polyurethane foam corresponding to Comparative Example 3 showed a reduced flame retardancy against fire spread, comparable to Example 2. This may be due to the slow addition rate of the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion, which caused some perfluorohexanone to evaporate before forming the coated suspension, thus reducing its flame retardancy.

[0082] The polyurethane foam corresponding to Comparative Example 4 also showed a reduced degree of flame retardancy against fire spread, similar to Example 2. This may be because the benzylphenol polyoxyethylene ether formaldehyde condensate emulsion was added too quickly, impacting the mixture of chitosan and perfluorohexanone. Before a suspension was formed, some perfluorohexanone escaped rapidly under the impact, resulting in a reduction in flame retardancy.

[0083] In the description of this specification, the references to terms such as "embodiment," "basic embodiment," "preferred embodiment," "other embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0085] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing fire-retardant capsule microbeads, characterized in that, The steps include the following: S1: Stir perfluorohexanone at room temperature (20°C or lower); S2: Add chitosan to perfluorohexanone in batches until the mass ratio of perfluorohexanone to chitosan reaches 1:(2~3), to obtain the first mixture; the mass ratio of perfluorohexanone to chitosan added in each batch is 1:(0.1~0.3). S3: Add benzylphenol polyoxyethylene ether formaldehyde condensate emulsion to the first mixture until the mass ratio of perfluorohexanone to benzylphenol polyoxyethylene ether formaldehyde condensate reaches 1:(0.3~0.5), to obtain the second mixture; the addition rate of benzylphenol polyoxyethylene ether formaldehyde condensate emulsion is 300~500ml / min; S4: Capsule microbeads are prepared by using a microbead preparation process to encapsulate the second mixture with the capsule wall material.

2. The preparation method according to claim 1, characterized in that: In step S4, the capsule wall material is made of a mixture of polyvinyl alcohol and gelatin, with a mass ratio of polyvinyl alcohol to gelatin of 1:(0.3~0.5).

3. The preparation method according to claim 1, characterized in that: In step S4, the capsule wall material is polyester or polyamide.

4. Fire-retardant capsule microbeads, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 3.

5. A polyurethane foam, characterized in that: It includes the fire-retardant capsule microbeads as described in claim 4.

6. The polyurethane foam according to claim 5, characterized in that: Insulation layer used in refrigeration equipment.

7. A method for preparing polyurethane foam, characterized in that, Includes the following steps: One of the combined polyether and isocyanate is stirred, and the fire-retardant capsule microbeads of claim 4 are added during the stirring process. After stirring evenly, the other of the combined polyether and isocyanate is added, and the reaction is carried out to obtain polyurethane foam.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the fire-retardant capsule microbeads to the combined polyether and the isocyanate is 1:(1~4):(1~4).

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