Flame-retardant and heat-insulating composition polyurethane foam board and refrigerated container

Abstract

The invention relates to a flame-retardant heat-insulating composition, a polyurethane foamed sheet and a refrigerated container. The flame-retardant and heat-insulating composition is used for a polyurethane foaming process and comprises expandable graphite, ammonium polyphosphate and sodium alginate. According to the flame-retardant and heat-insulating composition, the expansible graphite expands after being heated to form a porous carbon layer so as to form a flame-retardant and heat-insulating barrier, the ammonium polyphosphate is decomposed after being heated to generate polyphosphoric acid, the expansible graphite can be catalyzed to form carbon and release non-combustible gas for further flame retardance, and meanwhile, metal oxide generated by decomposition of the sodium alginate can react with the polyphosphoric acid, so that the flame retardance of the flame-retardant and heat-insulating composition is improved. Therefore, the carbon layer is stabilized, the strength and the isolation effect of the carbon layer are improved, and the ternary synergistic flame-retardant and heat-insulating effects are achieved.

Description

Technical Field

[0001] This application relates to the field of container technology, and more specifically to a flame-retardant and heat-insulating polyurethane foam board and a refrigerated container. Background Technology

[0002] As a key piece of equipment in modern cold chain logistics, the thermal insulation performance and fire safety of refrigerated containers are of paramount importance. Commonly used container insulation materials, such as polyurethane foam and polystyrene foam, while lightweight and offering good insulation, generally pose safety hazards due to their flammability and the release of toxic fumes during combustion. At the same time, existing technologies often struggle to balance excellent thermal insulation and energy efficiency with high-level fire resistance requirements: high-efficiency insulation materials are often flammable, while fireproofing treatments can increase costs or damage material properties.

[0003] Therefore, novel flame-retardant, non-toxic, high-performance vacuum insulation materials have become an important research and development direction. Currently, halogen-based, phosphorus-based, nitrogen-based, or inorganic flame retardants are commonly used for modification. However, single flame retardants are usually added in large quantities and have poor compatibility with the matrix, which can significantly reduce the mechanical strength, toughness, and thermal insulation performance of the material, and may also lead to environmental problems. For example, conventional ammonium polyphosphate is prone to moisture absorption and has insufficient weather resistance; although expanded graphite can form a thermally insulating carbon layer, when used alone, the carbon layer has low strength and is prone to peeling off.

[0004] Therefore, there is a need for a flame-retardant and heat-insulating polyurethane foam board and a refrigerated container to at least partially solve the above problems. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] To at least partially address the above-mentioned problems, a first aspect of this application provides a flame-retardant insulation composition for use in a polyurethane foaming process, the flame-retardant insulation composition comprising expandable graphite, ammonium polyphosphate, and sodium alginate.

[0007] According to the flame-retardant and heat-insulating composition of this application, expandable graphite expands when heated to form a porous carbon layer, thereby forming a flame-retardant and heat-insulating barrier. Ammonium polyphosphate decomposes when heated to generate polyphosphoric acid, which can catalyze the expansionable graphite to form carbon and release non-flammable gas to further retard the flame. At the same time, the metal oxides generated by the decomposition of sodium alginate can also react with polyphosphoric acid, thereby stabilizing the carbon layer and improving the strength and insulation effect of the carbon layer, thus forming a ternary synergistic flame-retardant and heat-insulating effect.

[0008] Optionally, the flame-retardant and heat-insulating composition has an encapsulation structure in which the sodium alginate is coated on the surface of the expandable graphite particles and the ammonium polyphosphate particles.

[0009] Optionally, the wrapping structure is obtained through the following process: Sodium alginate is dissolved in water by heating to form a gel. After mixing the coupling agent, dispersant and water, ammonium polyphosphate is added and dispersed by a disperser at the first shear rate to form a slurry. The slurry is added to the adhesive and dispersed and mixed evenly by a disperser at a second shear rate to form a mixture, wherein the second shear rate is less than the first shear rate. While the mixture is in a non-shear-stirring state, expandable graphite is added in batches and mixed evenly to form a flame-retardant and heat-insulating liquid composition. The flame-retardant and heat-insulating liquid composition is used to mix with the polyol component of the polyurethane foam.

[0010] Optionally, the flame-retardant and heat-insulating composition comprises: Expandable graphite, 15-35 parts by weight; Ammonium polyphosphate, 10-25 parts by weight; Sodium alginate, 3-10 parts by weight.

[0011] Optionally, the flame-retardant and heat-insulating composition comprises: Expandable graphite, 20-30 parts by weight; Ammonium polyphosphate, 15-20 parts by weight; Sodium alginate, 3-8 parts by weight.

[0012] Optionally, the expandable graphite has a particle size of 80-300 mesh and an initial expansion temperature of 180-220°C.

[0013] Optionally, the ammonium polyphosphate is selected as type II or type V, and the degree of polymerization of the ammonium polyphosphate is greater than or equal to 1000.

[0014] Optionally, the coupling agent is a silane coupling agent, and the dispersant is a polycarboxylate dispersant.

[0015] Optionally, the amount of the flame-retardant and heat-insulating composition added to the polyol component of the polyurethane foam is 10% to 30% of the weight of the polyurethane foam.

[0016] Optionally, the amount of the flame-retardant and heat-insulating composition added to the polyol component of the polyurethane foam is 15% to 25% of the weight of the polyurethane foam.

[0017] A second aspect of this application provides a polyurethane foam board, characterized in that the polyurethane foam board comprises the flame-retardant and heat-insulating composition described in the first aspect above.

[0018] The polyurethane foam board according to this application has similar technical effects to the flame-retardant and heat-insulating composition of the first aspect described above.

[0019] A third aspect of this application provides a refrigerated container, the refrigerated container comprising the polyurethane foam board described in the second aspect above.

[0020] The refrigerated container according to this application has the polyurethane foam board of the second aspect and the flame-retardant and heat-insulating composition of the first aspect, and therefore has similar technical effects as the flame-retardant and heat-insulating composition of the first aspect. Attached Figure Description

[0021] The following figures are included as part of this application for understanding the application. The figures illustrate embodiments of the application and their descriptions, serving to explain the principles of the application. In the figures: Figure 1 The residue after burning polyurethane foam without added flame retardants; Figure 2 The residue after combustion of polyurethane foam containing expandable graphite and ammonium polyphosphate binary system; Figure 3 This refers to the residue left after the polyurethane foam in Example 2 of this application was burned. Detailed Implementation

[0022] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.

[0024] The ordinal numbers such as “first” and “second” used in this application are merely identifiers and have no other meaning, such as a specific order. Furthermore, for example, the term “first component” does not imply the existence of a “second component,” and the term “second component” does not imply the existence of a “first component.” It should be noted that the terms “upper,” “lower,” “front,” “back,” “left,” “right,” “inner,” “outer,” and similar expressions used herein are for illustrative purposes only and are not intended to be limiting.

[0025] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings.

[0026] The first aspect of this application provides a flame-retardant insulation composition for use in a polyurethane foaming process, the flame-retardant insulation composition comprising expandable graphite, ammonium polyphosphate and sodium alginate.

[0027] According to the flame-retardant and heat-insulating composition of this application, expandable graphite expands when heated to form a porous carbon layer, thereby forming a flame-retardant and heat-insulating barrier. Ammonium polyphosphate decomposes when heated to generate polyphosphoric acid, which can catalyze the expansionable graphite to form carbon and release non-flammable gas to further retard the flame. At the same time, the metal oxides generated by the decomposition of sodium alginate can also react with polyphosphoric acid, thereby stabilizing the carbon layer and improving the strength and insulation effect of the carbon layer, thus forming a ternary synergistic flame-retardant and heat-insulating effect.

[0028] Preferably, the flame-retardant and heat-insulating composition has a coating structure in which sodium alginate is coated on the surface of expandable graphite particles and ammonium polyphosphate particles. Thus, the sodium alginate coating on the surface of the expandable graphite particles and ammonium polyphosphate particles acts as an adhesive, and also provides adhesion and protection for the carbon flakes formed after the expandable graphite particles expand, thereby making the carbon layer strong and stable, together forming a flame-retardant and heat-insulating carbon layer.

[0029] The aforementioned encapsulation structure can be obtained by dissolving sodium alginate and then mixing it with ammonium polyphosphate and expandable graphite.

[0030] Specifically, sodium alginate is first dissolved in water by heating to form a colloid. For example, sodium alginate is slowly added to deionized water, heated in a water bath to 50-70°C, and continuously stirred until completely dissolved. In another container, coupling agent, dispersant, and water are mixed, and then ammonium polyphosphate is added. The mixture is dispersed using a disperser at a first shear rate to form a slurry. The slurry is then added to the colloid and dispersed and mixed uniformly using a disperser at a second shear rate, where the second shear rate is lower than the first shear rate. The first shear rate can be a high shear rate, and the second shear rate can be a medium shear rate. While the mixture is under non-shear stirring conditions, such as slow stirring, expandable graphite is added in batches and mixed uniformly to form a flame-retardant and heat-insulating liquid composition.

[0031] Therefore, the dissolved sodium alginate can wet the surface of expandable graphite and ammonium polyphosphate. When the above-mentioned flame-retardant and heat-insulating composition liquid is used, it is first mixed with the polyol component of the polyurethane foam. During the foaming process of the polyol component and the isocyanate component, the high temperature generated will cause the water to evaporate, thereby forming a structure in which sodium alginate encapsulates ammonium polyphosphate and expandable graphite inside the foam material.

[0032] The flame-retardant and heat-insulating composition comprises, by weight, 15-35 parts expandable graphite, 10-25 parts ammonium polyphosphate, and 3-10 parts sodium alginate. Preferably, the flame-retardant and heat-insulating composition comprises 20-30 parts expandable graphite, 15-20 parts ammonium polyphosphate, and 3-8 parts sodium alginate. The expandable graphite has a particle size of 80-300 mesh and an initial expansion temperature of 180-220°C. The ammonium polyphosphate is selected as type II or type V, and the degree of polymerization of the ammonium polyphosphate is greater than or equal to 1000.

[0033] For the flame-retardant and heat-insulating composition with the above weight proportions, the total amount of water required in preparing the liquid composition is 30-60 parts by weight, while the total amount of dispersant and coupling agent is 1-5 parts by weight. Preferably, the total amount of water is 40-50 parts by weight, the dispersant is 0.5-1.5 parts by weight, and the coupling agent is 1.5-2.5 parts by weight. A silane coupling agent is selected as the coupling agent, and a polycarboxylate dispersant is selected as the dispersant.

[0034] In the process of preparing the flame-retardant and heat-insulating composition liquid, sodium alginate is first dissolved in a portion of water to form a colloid, for example, 20-80% of the total water volume, and then ammonium polyphosphate is mixed with the remaining water to form a slurry.

[0035] In one implementation, the flame-retardant and heat-insulating composition is added to the polyol component of the polyurethane foam at a rate of 10% to 30% of the weight of the polyurethane foam. Adding within this range provides both good flame-retardant and heat-insulating effects to the final foamed material. Preferably, the flame-retardant and heat-insulating composition is added to the polyol component of the polyurethane foam at a rate of 15% to 25% of the weight of the polyurethane foam.

[0036] The amount of flame-retardant and heat-insulating composition added to the polyol component refers to the total amount of the three components: expandable graphite, ammonium polyphosphate, and sodium alginate. Water is not included in the addition amount because a certain amount of water is also required in traditional polyurethane foaming for viscosity adjustment or cooling, and water will evaporate at high temperatures during the foaming reaction.

[0037] A second aspect of this application provides a polyurethane foam board, characterized in that the polyurethane foam board comprises the flame-retardant and heat-insulating composition of the first aspect described above.

[0038] The polyurethane foam board according to this application has similar technical effects to the flame-retardant and heat-insulating composition of the first aspect described above.

[0039] A third aspect of this application provides a refrigerated container, which includes the polyurethane foam board described in the second aspect above.

[0040] The refrigerated container according to this application has the polyurethane foam board of the second aspect and the flame-retardant and heat-insulating composition of the first aspect, and therefore has similar technical effects as the flame-retardant and heat-insulating composition of the first aspect.

[0041] The present application will now be described in more detail with reference to embodiments and comparative examples.

[0042] Example 1 Weigh out 5 parts by weight of sodium alginate and slowly add it to 15 parts by weight of deionized water. Heat the solution in a water bath to 60°C and stir continuously until completely dissolved to form a gel.

[0043] Add 2 parts by weight of KH-560 silane coupling agent and 1 part by weight of polycarboxylate dispersant to 30 parts by weight of deionized water and mix. Then weigh 20 parts by weight of type II ammonium polyphosphate and add it to form a slurry by high shear dispersion.

[0044] The above-mentioned adhesive and slurry are mixed at a medium shear rate to form a homogeneous mixture. The total water content in the mixture is 45 parts by weight.

[0045] Under the condition of slow stirring of the mixture, 15 parts by weight of 200 mesh expandable graphite are weighed and slowly added, and after mixing, a flame-retardant and heat-insulating liquid composition is obtained.

[0046] The flame-retardant and heat-insulating composition liquid prepared above was added to the polyol component of the polyurethane foam, with the addition amount being 20% ​​of the total foam volume. The mixture was then reacted, foamed, and cured in a mold to produce standard test strips and boards. Performance tests were then conducted on the test strips.

[0047] Example 2 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 5 parts by weight.

[0048] Example 3 It is basically the same as Example 1, except that the expandable graphite is 20 parts by weight, the ammonium polyphosphate is 15 parts by weight, and the sodium alginate is 8 parts by weight.

[0049] Example 4 It is basically the same as Example 1, except that the expandable graphite is 30 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 3 parts by weight.

[0050] Example 5 It is basically the same as Example 1, except that the expandable graphite is 35 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 5 parts by weight.

[0051] Example 6 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 25 parts by weight, and the sodium alginate is 5 parts by weight.

[0052] Example 7 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 10 parts by weight, and the sodium alginate is 5 parts by weight.

[0053] Example 8 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 10% of the total amount of foaming material.

[0054] Example 9 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 15% of the total amount of foaming material.

[0055] Example 10 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 20% of the total amount of foaming material.

[0056] Example 11 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 25% of the total amount of foaming material.

[0057] Example 12 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 30% of the total amount of foaming material.

[0058] Comparative Example 1 Add 2 parts by weight of KH-560 silane coupling agent and 1 part by weight of polycarboxylate dispersant to 45 parts by weight of deionized water and mix. Then weigh 20 parts by weight of type II ammonium polyphosphate and add it to form a slurry by high shear dispersion.

[0059] Under the condition of slow stirring of the slurry, 25 parts by weight of 200 mesh expandable graphite were weighed and slowly added, and after mixing, a control liquid was obtained.

[0060] The comparative liquid material prepared above was added to the polyol component of the polyurethane foam, with an addition amount of 20% of the total foam material. The mixture was then reacted, foamed, and cured in a mold to produce standard test strips and boards. Performance tests were then conducted on the test strips.

[0061] Comparative Example 2 It is basically the same as Example 2, except that 5 parts by weight of starch are used instead of sodium alginate.

[0062] Comparative Example 3 It is basically the same as Example 2, except that the expandable graphite is 10 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 5 parts by weight.

[0063] Comparative Example 4 It is basically the same as Example 1, except that the expandable graphite is 40 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 5 parts by weight.

[0064] Comparative Example 5 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 5 parts by weight, and the sodium alginate is 5 parts by weight.

[0065] Comparative Example 6 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 30 parts by weight, and the sodium alginate is 5 parts by weight.

[0066] Comparative Example 7 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 1.5 parts by weight.

[0067] Comparative Example 8 It is basically the same as Example 1, except that the expandable graphite is 25 parts by weight, the ammonium polyphosphate is 20 parts by weight, and the sodium alginate is 12 parts by weight.

[0068] Comparative Example 9 No flame retardants are added; foaming is carried out directly using polyol components and isocyanate components.

[0069] Comparative Example 10 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 5% of the total amount of foaming material.

[0070] Comparative Example 11 It is basically the same as Example 2, except that the amount of flame-retardant and heat-insulating composition added during foaming is 35% of the total amount of foaming material.

[0071] The test specimens prepared in Examples 1-12 and Comparative Examples 1-11 were subjected to performance tests, and the results are shown in Table 1.

[0072] Table 1 As can be seen from Examples 1-7 and Comparative Examples 1-9, the flame-retardant effect of Examples 1-7 is significantly better than that of Comparative Examples 1-9. While the foam material without flame retardant has the best thermal insulation effect, it has no flame-retardant effect whatsoever. Figure 1 As shown. The addition of traditional flame retardants (without sodium alginate) will increase the thermal conductivity to some extent, thus worsening the insulation effect of the foamed material, and its flame retardant effect is also generally poor, such as... Figure 2 As shown. However, in Examples 1-7, the addition of sodium alginate synergistically strengthens the porous carbon layer formed by expandable graphite, thus mitigating the adverse effects of adding flame retardants on the original insulation performance, such as... Figure 3 The results show that a regular char layer can be formed for flame retardancy and heat insulation. In other words, the ternary synergistic effect of expandable graphite, ammonium polyphosphate, and sodium alginate in this application is significant, while providing good flame retardancy and heat insulation properties.

[0073] If the amount of expandable graphite added is too low, the expanded carbon layer will be insufficient; if it is too high, it will damage the foam structure, resulting in a decrease in mechanical and thermal insulation properties. If the amount of ammonium polyphosphate added is too low, the catalytic carbonization will be insufficient, and the flame retardant effect will be poor; if the amount added is too high, the acidity will be too strong, which may corrode equipment and increase smoke production. If the amount of sodium alginate added is too low, it cannot effectively stabilize and enhance the carbon layer; if the amount added is too high, the system viscosity will be too high, affecting the foaming process and thermal insulation performance.

[0074] As can be seen from Examples 8-12 and Comparative Examples 10-11, in the foaming system, if the amount of the flame-retardant and heat-insulating composition added in this application is too low, the flame-retardant effect is insufficient, and it cannot pass the V-0 rating of the UL-94 rating standard. If the amount added is too high, although the flame retardancy is maintained at a high level, too much slurry leads to excessive system viscosity, poor cell structure, significantly reduced compressive strength, and deteriorated thermal conductivity, resulting in low practical application value.

[0075] The processes and steps described in all the preferred embodiments above are merely examples. Unless adverse effects occur, various processing operations can be performed in a different order than the above-described processes. The order of steps in the above processes can also be added, combined, or deleted according to actual needs.

[0076] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this application. Features described in one embodiment may be applied, alone or in combination with other features, to another embodiment, unless that feature is not applicable in that other embodiment or is otherwise stated.

[0077] This application has been described through the above embodiments. However, it should be understood that the above embodiments are only for illustrative purposes. This application is not limited to the above embodiments. Many variations and modifications can be made based on the teachings of this application, and all such variations and modifications fall within the scope of protection claimed in this application.

Claims

1. A flame-retardant and heat-insulating composition, characterized in that, The flame-retardant and heat-insulating composition is used in a polyurethane foaming process, and the flame-retardant and heat-insulating composition includes expandable graphite, ammonium polyphosphate, and sodium alginate.

2. The flame-retardant and heat-insulating composition according to claim 1, characterized in that, The flame-retardant and heat-insulating composition has an encapsulation structure in which the sodium alginate is coated on the surface of the expandable graphite particles and the ammonium polyphosphate particles.

3. The flame-retardant and heat-insulating composition according to claim 2, characterized in that, The encapsulation structure is obtained through the following process: Sodium alginate is dissolved in water by heating to form a gel. After mixing the coupling agent, dispersant and water, ammonium polyphosphate is added and dispersed by a disperser at the first shear rate to form a slurry. The slurry is added to the adhesive and dispersed and mixed evenly by a disperser at a second shear rate to form a mixture, wherein the second shear rate is less than the first shear rate. While the mixture is in a non-shear-stirring state, expandable graphite is added in batches and mixed evenly to form a flame-retardant and heat-insulating liquid composition. The flame-retardant and heat-insulating liquid composition is used to mix with the polyol component of the polyurethane foam.

4. The flame-retardant and heat-insulating composition according to claim 1, characterized in that, The flame-retardant and heat-insulating composition comprises: Expandable graphite, 15-35 parts by weight; Ammonium polyphosphate, 10-25 parts by weight; Sodium alginate, 3-10 parts by weight.

5. The flame-retardant and heat-insulating composition according to claim 1, characterized in that, The flame-retardant and heat-insulating composition comprises: Expandable graphite, 20-30 parts by weight; Ammonium polyphosphate, 15-20 parts by weight; Sodium alginate, 3-8 parts by weight.

6. The flame-retardant and heat-insulating composition according to claim 1, characterized in that, The expandable graphite has a particle size of 80-300 mesh and an initial expansion temperature of 180-220℃.

7. The flame-retardant and heat-insulating composition according to claim 1, characterized in that, The ammonium polyphosphate is selected from type II or type V, and the degree of polymerization of the ammonium polyphosphate is greater than or equal to 1000.

8. The flame-retardant and heat-insulating composition according to claim 3, characterized in that, The coupling agent is a silane coupling agent, and the dispersant is a polycarboxylate dispersant.

9. The flame-retardant and heat-insulating composition according to claim 3, characterized in that, The amount of the flame-retardant and heat-insulating composition added to the polyol component of the polyurethane foam is 10% to 30% of the weight of the polyurethane foam.

10. The flame-retardant and heat-insulating composition according to claim 3, characterized in that, The amount of the flame-retardant and heat-insulating composition added to the polyol component of the polyurethane foam is 15% to 25% of the weight of the polyurethane foam.

11. A polyurethane foam board, characterized in that, The polyurethane foam board comprises the flame-retardant and heat-insulating composition according to any one of claims 1-10.

12. A refrigerated container, characterized in that, The refrigerated container includes the polyurethane foam board according to claim 11.

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