Flame-retardant film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and discloses a flame-retardant film as well as a preparation method and application thereof. The flame-retardant film comprises a film base material and a flame-retardant coating, the flame-retardant coating is arranged on the surface of the film base material, the flame-retardant coating is formed by coating and drying paint, and the paint comprises piperazine pyrophosphate, diammonium hydrogen phosphate and auxiliaries. Piperazine pyrophosphate in the flame-retardant film and the flame-retardant coating serves as a carbon source and an acid source, diammonium hydrogen phosphate serves as an acid source and an air source, the flame-retardant film has the excellent flame-retardant effect, meanwhile, the flame-retardant coating is arranged on the surface of the film base material and formed through coating and drying, the mechanical property of the film base material cannot be affected, and the flame-retardant film has the good flame-retardant effect. Therefore, a thinner film base material can be adopted, and the thickness of the flame-retardant film is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a flame retardant film and a preparation method and application thereof. Background Art

[0002] At present, flame retardant materials mainly have the following methods to play a flame retardant role:

[0003] 1. Heat absorbing and flame retardant

[0004] The heat released by combustion is limited. If part of the heat released by combustion can be absorbed in a shorter time, the flame temperature will be reduced, the heat radiated to the combustion surface and the heat acting on the decomposition of the already gasified combustible molecules into free radicals will be reduced, and the combustion reaction will be inhibited to a certain extent. For example, Al(OH) 3 The flame retardant mechanism of flame retardants is to increase the heat capacity of polymers so that they absorb more heat before reaching the thermal decomposition temperature, thereby improving their flame retardant properties. This type of flame retardant takes advantage of its ability to absorb a large amount of heat when combined with water vapor, thereby improving its own flame retardant ability.

[0005] 2. Flame retardant covering

[0006] After adding flame retardants to combustible materials, they can form a glassy or stable foam covering layer at high temperatures, isolating oxygen, and have the functions of heat insulation, oxygen isolation, and preventing the escape of combustible gases, thereby achieving the purpose of flame retardancy. For example, when organic phosphorus flame retardants are heated, they can produce cross-linked solid substances or carbonized layers with more stable structures. The formation of the carbonized layer can prevent the polymer from further pyrolysis on the one hand, and prevent the thermal decomposition products inside it from entering the gas phase and participating in the combustion process on the other hand.

[0007] 3. Inhibit chain reaction and flame retardant

[0008] According to the chain reaction theory of combustion, free radicals are needed to maintain combustion. Flame retardants can act on the gas phase combustion zone, capture free radicals in the combustion reaction, thereby preventing the spread of flames, reducing the flame density in the combustion zone, and reducing the combustion reaction rate until it stops. For example, the evaporation temperature of halogen-containing flame retardants is the same or similar to the decomposition temperature of polymers. When the polymer is decomposed by heat, the flame retardant also evaporates at the same time. At this time, the halogen-containing flame retardant and the thermal decomposition products are in the gas phase combustion zone at the same time, and the halogen can capture the free radicals in the combustion reaction and interfere with the chain reaction of combustion.

[0009] 4. Suffocation and flame retardant

[0010] When heated, the flame retardant decomposes into non-combustible gas, which dilutes the concentration of the combustible gas decomposed from the combustible to below the lower limit of combustion. At the same time, it also dilutes the oxygen concentration in the combustion zone, preventing the combustion from continuing, thus achieving the flame retardant effect.

[0011] For endothermic flame retardancy, a high proportion of metal oxides or metal hydroxides is required to achieve the corresponding flame retardant effect. This method has a high production cost and is gradually being eliminated by the market.

[0012] In order to inhibit chain reaction flame retardancy, halogen elements are needed in flame retardants, which leads to the precipitation of gases harmful to the human body during the production process. Flame retardants will also release substances harmful to the environment and human body at high temperatures.

[0013] For covering flame retardant and suffocating flame retardant, it is the current development trend of flame retardant materials. These two flame retardant methods are usually used in combination, such as adding a certain proportion of poly-2-amino-4,6-piperazinyl-1,3,5 triazine, ammonium polyphosphate and other substances to the film substrate for melt co-extrusion preparation. Under high temperature environment (generally refers to combustion temperature, 300-800℃), poly-2-amino-4,6-piperazinyl-1,3,5 triazine is dehydrated into carbon (carbon source, the role is carbon insulation), and ammonium polyphosphate decomposes to form phosphoric acid and ammonia. Among them, phosphoric acid has strong water absorption (acid source, the role is water absorption), which can absorb the water lost by poly-2-amino-4,6-piperazinyl-1,3,5 triazine and accelerate carbonization. Ammonia can play the role of heat insulation and suffocating flame retardant, preventing the substrate from burning (gas source, the role is heat insulation and suffocating flame retardant). This type of flame retardant method requires adding a higher proportion of flame retardant additives to the film substrate. Generally speaking, the addition ratio is 30-50wt% depending on the flame retardant effect. Due to the addition of a higher proportion of flame retardant additives, the mechanical properties of the film will inevitably be greatly affected. In order not to affect the use of the product other than the flame retardant function, it is necessary to increase the thickness of the film to compensate for the impact of the decline in mechanical properties. For example: the current thickness of the flame retardant film is 250-500μm. If a flame retardant film below 250μm is produced according to the current method, due to the problem of decreased mechanical properties, the film may not be formed during the film drawing process. In addition, ammonium polyphosphate is currently used as a gas source and acid source. The price of this type of flame retardant material is relatively high. Using a high proportion in the film will increase the product cost. Summary of the invention

[0014] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a flame retardant film and a preparation method and application thereof, wherein the flame retardant film has excellent flame retardant effect and mechanical properties and has a thickness of ≤250 μm.

[0015] In a first aspect, the present invention provides a flame retardant film, which includes a film substrate and a flame retardant coating. The flame retardant coating is arranged on the surface of the film substrate. The flame retardant coating is formed by coating and drying a coating. The coating includes piperazine pyrophosphate, diammonium hydrogen phosphate and an additive.

[0016] In some embodiments of the present invention, the auxiliary agent includes an adhesive, a solvent and a dispersant.

[0017] In some embodiments of the present invention, the coating includes 5-15% piperazine pyrophosphate, 10-20% diammonium hydrogen phosphate, 20-40% adhesive, 20-40% solvent and 0.3-0.8% dispersant by mass fraction. Selecting the appropriate amount helps to improve flame retardant properties. For example, if the content of piperazine pyrophosphate is less than 5%, the flame retardant effect will be relatively poor; when it reaches 15%, the flame retardant effect reaches the V0 level under VTM test conditions. If it is greater than 15%, it will only increase costs.

[0018] In some embodiments of the present invention, the adhesive comprises Latex 950 emulsion and / or Latex 930 emulsion. Adding the adhesive makes the flame retardant coating sticky and improves the bonding strength with the film substrate.

[0019] In some embodiments of the invention, the solvent comprises water.

[0020] In some embodiments of the present invention, the dispersant includes disodium hexyl sulfosuccinate. Disodium hexyl sulfosuccinate as a dispersant can improve the dispersion uniformity of materials in the coating. If the dispersant is lacking, the coating coating effect will be poor, affecting the subsequent composite processing steps of the film.

[0021] In some embodiments of the present invention, there are a plurality of the film substrates, and the flame retardant coating is disposed between a plurality of adjacent film substrates.

[0022] In some embodiments of the present invention, there are two film substrates, and the flame retardant coating is disposed between two adjacent film substrates to form a sandwich structure.

[0023] In some embodiments of the present invention, the thickness of the flame retardant film is ≤250 μm, preferably 10-100 μm.

[0024] In some embodiments of the present invention, the thickness of the flame retardant coating is 50-100% of the thickness of the film substrate.

[0025] In some embodiments of the present invention, the film substrate has a thickness of 10-20 μm.

[0026] In some embodiments of the present invention, the film substrate includes at least one of biaxially oriented polypropylene (BOPP), cast polypropylene (CPP), biaxially oriented polyester (BOPET), polyvinyl chloride (PVC), polyethylene (PE) and biaxially oriented polyethylene (BOPE).

[0027] The second aspect of the present invention provides a method for preparing the flame retardant film according to the first aspect of the present invention, comprising the following steps:

[0028] mixing piperazine pyrophosphate, diammonium hydrogen phosphate and an additive to obtain a coating;

[0029] The coating is applied to the surface of the film substrate and dried to form a flame retardant coating to obtain a flame retardant film.

[0030] In some embodiments of the present invention, the coating is applied between a plurality of adjacent film substrates.

[0031] In some embodiments of the present invention, the surface of the film substrate in contact with the flame retardant coating is pre-corona treated. After the film substrate is subjected to the surface corona treatment, the surface energy of the film is increased, thereby enhancing its adhesion to the flame retardant coating.

[0032] In some embodiments of the present invention, the drying temperature is 60-80°C.

[0033] The third aspect of the present invention provides a flame retardant product, wherein the flame retardant film of the first aspect of the present invention is provided on the surface of the flame retardant product. The flame retardant film of the present invention can be used for decoration of occasions and places with flame retardant requirements. For example, catering services (including bars), shopping centers (including department stores), supermarkets, agricultural (collective) trade markets, beauty salons, theaters, art galleries, museums, memorial halls, cultural centers (stations), libraries, etc.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] The flame-retardant film of the present invention has piperazine pyrophosphate as a carbon source and an acid source, and diammonium hydrogen phosphate as an acid source and a gas source in the flame-retardant coating, so that the flame-retardant film has an excellent flame-retardant effect. At the same time, the flame-retardant coating is arranged on the surface of the film substrate, and is formed by coating and drying, which will not affect the mechanical properties of the film substrate, so that a thinner film substrate can be used to reduce the thickness of the flame-retardant film.

[0036] The flame retardant coating of the present invention is formed by coating and drying, and has no strict requirements on the flame retardant, the properties and thickness of the substrate material, as long as no obvious deformation occurs under the conventional drying process; while the traditional method of adding flame retardants to the substrate and melt extrusion has strict requirements on the flame retardant, the properties and thickness of the substrate material, such as the need to increase the thickness of the film to compensate for the impact of the decrease in mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic structural diagram of the flame retardant film of Example 1;

[0038] Figure 2 This is a schematic diagram of the structure of the flame retardant film of Example 2.

[0039] Reference numerals: 100, first BOPP film substrate; 110, upper surface of the first BOPP film substrate; 200, flame retardant coating; 300, second BOPP film substrate; 310, lower surface of the second BOPP film substrate. DETAILED DESCRIPTION

[0040] In the description of the present invention, it is necessary to understand that the orientation or positional relationship indicated by the terms upper, lower, etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0041] In the description of the present invention, the meaning of "above", "below", "exceed", etc. is not inclusive of the number itself, and the meaning of "above", "below", "within", etc. is inclusive of the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0042] The present invention is further described in detail below by specific examples. The raw materials, reagents or devices used in the examples can be obtained from conventional commercial sources or by prior art methods unless otherwise specified. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0043] Example 1

[0044] like Figure 1 As shown, a flame retardant film comprises a first BOPP film substrate 100, a flame retardant coating 200 and a second BOPP film substrate 300, wherein the flame retardant coating 200 is disposed between the first BOPP film substrate 100 and the second BOPP film substrate 300;

[0045] The flame retardant coating 200 is formed by coating and drying a coating, wherein the coating comprises piperazine pyrophosphate, diammonium hydrogen phosphate, Latex 950 emulsion, deionized water and disodium hexane sulfosuccinate.

[0046] The flame retardant film of this example, its preparation method comprises the following steps:

[0047] S1, 15 parts of Latex950 emulsion, 15 parts of deionized water, 5 parts of piperazine pyrophosphate, 7 parts of diammonium hydrogen phosphate and 0.25 parts of disodium hexyl sulfosuccinate were mixed and stirred to obtain a coating;

[0048] S2. The upper surface 110 of the first BOPP film substrate with a thickness of 20 μm is subjected to corona treatment, and the coating is evenly applied on the upper surface 110 of the first BOPP film substrate. The lower surface 310 of the second BOPP film substrate with a thickness of 20 μm is subjected to corona treatment, and the second BOPP film substrate 300 is placed on the upper surface 110 of the first BOPP film substrate (wherein the lower surface 310 of the second BOPP film substrate is in contact with the coating), and after pressing, it is dried at 80° C. for 1 min to form a 15 μm thick flame retardant coating 200, thereby obtaining a flame retardant film with a sandwich structure.

[0049] Example 2

[0050] like Figure 2 As shown, a flame retardant film comprises a first BOPP film substrate 100 and a flame retardant coating 200, wherein the flame retardant coating 200 is disposed on an upper surface 110 of the first BOPP film substrate;

[0051] The flame retardant coating 200 is formed by coating and drying a coating, wherein the coating comprises piperazine pyrophosphate, diammonium hydrogen phosphate, Latex 930 emulsion, deionized water and disodium hexane sulfosuccinate.

[0052] The flame retardant film of this example, its preparation method comprises the following steps:

[0053] S1, 15 parts of Latex930 emulsion, 15 parts of deionized water, 3 parts of piperazine pyrophosphate, 7 parts of diammonium hydrogen phosphate and 0.25 parts of disodium hexane sulfosuccinate were mixed and stirred to obtain a coating;

[0054] S2. Corona treat the upper surface 110 of the 20 μm thick first BOPP film substrate, then evenly apply the coating on the upper surface 110 of the first BOPP film substrate, and dry it at 80° C. for 1 min to form a 15 μm thick flame retardant coating 200 to obtain a flame retardant film.

[0055] Example 3

[0056] A flame retardant film, comprising a BOPP film substrate and a flame retardant coating, wherein the flame retardant coating is arranged on the upper surface of the BOPP film substrate;

[0057] The flame retardant coating is formed by coating and drying the coating, and the components of the coating are composed of piperazine pyrophosphate, diammonium hydrogen phosphate, Latex930 emulsion, deionized water and disodium hexane sulfosuccinate.

[0058] The flame retardant film of this example, its preparation method comprises the following steps:

[0059] S1, 15 parts of Latex930 emulsion, 15 parts of deionized water, 5 parts of piperazine pyrophosphate, 7 parts of diammonium hydrogen phosphate and 0.25 parts of disodium hexane sulfosuccinate were mixed and stirred to obtain a coating;

[0060] S2. The upper surface of the 10 μm thick BOPP film substrate is subjected to corona treatment, and then the coating is evenly applied on the upper surface of the BOPP film substrate, and dried at 80° C. for 1 min to form a 10 μm thick flame retardant coating to obtain a flame retardant film.

[0061] Example 4

[0062] A flame retardant film, comprising a BOPP film substrate and a flame retardant coating, wherein the flame retardant coating is arranged on the upper surface of the BOPP film substrate;

[0063] The flame retardant coating is formed by coating and drying the coating, and the components of the coating are composed of piperazine pyrophosphate, diammonium hydrogen phosphate, Latex930 emulsion, deionized water and disodium hexane sulfosuccinate.

[0064] The flame retardant film of this example, its preparation method comprises the following steps:

[0065] S1, 15 parts of Latex930 emulsion, 15 parts of deionized water, 1 part of piperazine pyrophosphate, 3 parts of diammonium hydrogen phosphate and 0.25 parts of disodium hexyl sulfosuccinate were mixed and stirred to obtain a coating;

[0066] S2. The upper surface of the 20 μm thick BOPP film substrate is subjected to corona treatment, and then the coating is evenly applied on the upper surface of the BOPP film substrate, and dried at 80° C. for 1 min to form a 15 μm thick flame retardant coating to obtain a flame retardant film.

[0067] Comparative Example 1

[0068] The only difference from Example 1 is that the coating component of Comparative Example 1 does not contain piperazine pyrophosphate and diammonium hydrogen phosphate, and the other conditions are the same as those of Example 1.

[0069] Comparative Example 2

[0070] The only difference from Example 1 is that in Comparative Example 2, an equal amount of diamine hydrogen phosphate in the coating component is replaced by aluminum hypophosphite, and the other conditions are the same as those in Example 1.

[0071] Comparative Example 3

[0072] The only difference from Example 1 is that in Comparative Example 3, an equal amount of piperazine pyrophosphate in the coating component is replaced by aluminum diethylphosphinate, and the other conditions are the same as those in Example 1.

[0073] Comparative Example 4 (using traditional melt extrusion method)

[0074] The film of this example, its preparation method comprises the following steps:

[0075] 15 parts of Latex930 emulsion, 15 parts of deionized water, 5 parts of piperazine pyrophosphate, 7 parts of diammonium hydrogen phosphate and 0.25 parts of disodium hexane sulfosuccinate were mixed and stirred evenly, and then melt-coextruded with polypropylene pellets to an extrusion thickness of 250 μm to obtain a film.

[0076] Comparative Example 5 (using traditional melt extrusion method)

[0077] The film of this example, its preparation method comprises the following steps:

[0078] 15 parts of Latex930 emulsion, 15 parts of deionized water, 5 parts of piperazine pyrophosphate, 7 parts of diammonium hydrogen phosphate and 0.25 parts of disodium hexane sulfosuccinate were mixed and stirred evenly, and then melt-coextruded with polypropylene pellets with an extrusion thickness of 50 μm. Due to insufficient melt strength, film formation could not be achieved during the extrusion process.

[0079] Product performance testing

[0080] The films prepared in Examples 1-4 and Comparative Examples 1-4 were used as test samples to test the longitudinal tensile strength, and the flame retardant properties were tested according to the UL94 flame retardant test standard; the test results are shown in Table 1.

[0081] Table 1

[0082] sample Flame retardant grade Longitudinal tensile strength (MPa) Example 1 V0 95 Example 2 V0 92 Example 3 V0 84 Example 4 V1 89 Comparative Example 1 Not flame retardant 95 Comparative Example 2 Not flame retardant 93 Comparative Example 3 Not flame retardant 96 Comparative Example 4 Not flame retardant 50

[0083] It can be seen from Table 1 that the flame retardant films prepared in Examples 1-4 of the present invention not only have excellent flame retardant effects (can reach V0 flame retardant level), but also have excellent mechanical properties; the flame retardant level of Example 4 is V1 because the amount of piperazine pyrophosphate and diammonium hydrogen phosphate used is relatively small, resulting in relatively poor flame retardant effect.

[0084] Piperazine pyrophosphate is used as a carbon source and an acid source, and diammonium hydrogen phosphate is used as an acid source and a gas source. Comparative Example 1 lacks piperazine pyrophosphate and diammonium hydrogen phosphate, resulting in a lack of flame retardant properties.

[0085] In Comparative Example 2, diammonium hydrogen phosphate is replaced with aluminum hypophosphite. Due to the lack of gas source, the flame cannot be prevented from contacting the combustion-supporting material (the combustion-supporting material is generally oxygen in the air), so the flame retardant effect cannot be achieved; in Comparative Example 3, piperazine pyrophosphate is replaced with aluminum diethylphosphite. Due to the lack of carbon source, the flame retardant effect cannot be achieved.

[0086] Comparative Example 4 uses a traditional melt extrusion process. Since diammonium hydrogen phosphate decomposes due to high temperature during the plasticization process of the plastic particles, a product with a flame retardant effect cannot be obtained.

[0087] The preferred embodiments of the present invention are specifically described above, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A flame retardant film, characterized in that: The flame retardant film comprises a film substrate and a flame retardant coating, wherein the flame retardant coating is arranged on the surface of the film substrate, and the flame retardant coating is formed by coating and drying a coating, wherein the coating comprises piperazine pyrophosphate, diammonium hydrogen phosphate and an auxiliary agent.

2. The flame retardant film according to claim 1, characterized in that: The auxiliary agents include adhesives, solvents and dispersants.

3. The flame retardant film according to claim 2, characterized in that: Calculated by mass fraction, the coating comprises 5-15% of piperazine pyrophosphate, 10-20% of diammonium hydrogen phosphate, 20-40% of adhesive, 20-40% of solvent and 0.3-0.8% of dispersant.

4. The flame retardant film according to claim 1, characterized in that: There are a plurality of film substrates, and the flame retardant coating is disposed between a plurality of adjacent film substrates.

5. The flame retardant film according to claim 1, characterized in that: The thickness of the flame retardant film is ≤250 μm.

6. The flame retardant film according to claim 1, characterized in that: The thickness of the flame retardant coating is 50-100% of the thickness of the film substrate.

7. The method for preparing a flame retardant film according to any one of claims 1 to 6, characterized in that: The following steps are involved: mixing piperazine pyrophosphate, diammonium hydrogen phosphate and an additive to obtain a coating; The coating is applied to the surface of the film substrate and dried to form a flame retardant coating to obtain a flame retardant film.

8. The preparation method according to claim 7, characterized in that: The coating is applied between a plurality of adjacent film substrates.

9. The preparation method according to claim 7, characterized in that: The surface of the film substrate in contact with the flame retardant coating is pre-corona treated.

10. A flame retardant product, characterized in that: The surface of the flame retardant product is provided with the flame retardant film according to any one of claims 1 to 6.

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