Halogen-free phosphorus-free flame-retardant EVA film and preparation method thereof

Abstract

The invention provides a halogen-free phosphorus-free flame-retardant EVA film and a preparation method thereof. The EVA film is prepared from the following raw materials in parts by weight: 100 parts of an ethylene-vinyl acetate copolymer, 10 to 50 parts of flame-retardant master batch, 0.5 to 1.0 part of a thermal radical initiator, 0.5 to 2 parts of a crosslinking aid, 0.3 to 2 parts of a silane coupling agent, 0.1 to 0.5 part of an antioxidant, 0.05 to 1.0 part of an ultraviolet absorbent and 0.05 to 1.0 part of a light stabilizer. Through the direct flame-retardant effect of the flame-retardant master batch and the synergistic effect of the thermal radical initiator, the cross-linking aid, the silane coupling agent and the like, the flame-retardant performance of the EVA film is improved from multiple aspects, and meanwhile, the processing performance and the service life of the material are considered.

Description

Technical Field

[0001] The present application relates to the technical field of polymer composite materials, and in particular to a halogen-free and phosphorus-free flame-retardant EVA film and a preparation method thereof. Background Art

[0002] With the development of the construction and automotive industries, laminated glass is increasingly used. Laminated glass uses an interlayer to bond multiple sheets of glass together, significantly improving the safety and impact resistance of the glass. However, traditional interlayer materials for laminated glass have significant drawbacks. For example, SGP film, while offering high strength, is cumbersome to process and expensive. PVB film, while offering excellent adhesion and high transparency, is highly water-absorbent and prone to delamination after long-term use. The commonly used EVA film, while easy to process and inexpensive, lacks flame retardancy, making it highly combustible and releasing toxic gases in the event of a fire, posing a safety hazard.

[0003] Currently, flame-retardant modification of polymer materials mostly uses halogen or phosphorus-based flame retardants. However, halogen flame retardants produce large amounts of toxic smoke during combustion, posing a threat to people and the environment. In contrast, phosphorus-based flame retardants not only overcome the defects of halogen-containing flame retardants, such as large amounts of smoke and the release of toxic and corrosive gases, but also improve the shortcomings of inorganic flame retardants, which seriously affect the physical and mechanical properties of the material when added in high amounts. They achieve high flame retardancy, low smoke, low toxicity, and no corrosive gas production. Therefore, the development of a halogen-free and phosphorus-free environmentally friendly flame-retardant EVA film has become an urgent problem to be solved in the industry. Although there are studies on related flame-retardant EVA films in the prior art, most of them have problems such as complex processes, unsatisfactory flame-retardant effects, or inability to meet the long-term use requirements in the construction and automotive fields. Therefore, providing an environmentally friendly and efficient halogen-free and phosphorus-free flame-retardant EVA film and its preparation method is of great significance for improving the safety and reliability of laminated glass. Summary of the Invention

[0004] The present application provides a halogen-free and phosphorus-free flame-retardant EVA film and a preparation method thereof to solve the following technical problem: how to improve the flame retardant properties of EVA film.

[0005] On the one hand, the embodiments of the present application provide a halogen-free and phosphorus-free flame-retardant EVA film and a preparation method thereof, comprising the following raw materials in parts by weight:

[0006] 100 parts of ethylene-vinyl acetate copolymer, 10-50 parts of flame retardant masterbatch, 0.5-1.0 parts of thermal free radical initiator, 0.5-2 parts of crosslinking aid, 0.3-2 parts of silane coupling agent, 0.1-0.5 parts of antioxidant, 0.05-1.0 parts of ultraviolet absorber, and 0.05-1.0 parts of light stabilizer.

[0007] Optionally, the VA mass fraction of the ethylene-vinyl acetate copolymer is 15%-33%, and the melt index of the ethylene-vinyl acetate copolymer is 3-40 g / 10 min.

[0008] Optionally, the raw materials for preparing the flame retardant masterbatch include polyborosiloxane and an inorganic hydroxide flame retardant.

[0009] Optionally, the inorganic hydroxide flame retardant includes at least one of the following: magnesium hydroxide, aluminum hydroxide; and / or the raw materials for preparing the polyborosiloxane include: terminal hydroxyl polydimethylsiloxane and boric acid.

[0010] Optionally, the mass ratio of the polyborosiloxane to the inorganic hydroxide flame retardant is 5-10:1

[0011] Optionally, the compatibilizer includes at least one of the following: bis-(-3-triethoxysilylpropyl)-disulfide, 3-aminopropyltriethoxysilane; and / or,

[0012] The thermal free radical initiator includes at least one of the following: dicumyl peroxide, dibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl ester; and / or,

[0013] The cross-linking auxiliary agent includes at least one of the following: triallyl cyanurate, triallyl isocyanurate, polytriallyl isocyanurate; and / or,

[0014] The silane coupling agent includes at least one of the following: 3-(methacryloyloxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane.

[0015] Optionally, the antioxidant includes at least one of the following: β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6-di-tert-butyl-4-methylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4,4'-thiobis(6-tert-butyl-3-methylphenol); and / or,

[0016] The ultraviolet absorber includes at least one of the following: 2-hydroxy-4-n-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)-benzotriazole, 2-[2,4-bis(2,4-xylyl)-2-(1,3,5-triazinyl)-octyloxyphenol], 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol; and / or,

[0017] The light stabilizer includes at least one of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol) succinate, and 2,2,6,6-tetramethylpiperidinyl hexamethylenediamine.

[0018] Optionally, the thickness of the EVA film is 0.3mm-0.8mm; and / or,

[0019] The upper surface and the lower surface of the EVA film are respectively embossed with geometric patterns.

[0020] In a second aspect, an embodiment of the present application further provides a method for preparing the halogen-free and phosphorus-free flame-retardant EVA film according to the first aspect, comprising:

[0021] The polyborosiloxane is modified with a compatibilizer to form a transparent colloid;

[0022] adding an inorganic hydroxide flame retardant to the transparent colloid, and performing a first stirring to obtain a mixed colloid;

[0023] mixing a portion of ethylene-vinyl acetate copolymer with the mixture colloid to granulate through a first melt extrusion to obtain a flame retardant masterbatch;

[0024] mixing a thermal free radical initiator, a crosslinking auxiliary agent, a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer to obtain a mixed auxiliary agent;

[0025] mixing the remaining portion of the ethylene-vinyl acetate copolymer with the flame retardant masterbatch to obtain mixed particles;

[0026] spraying the mixing auxiliary agent on the surface of the mixed particles, and performing a second stirring on the mixed particles so that the mixing auxiliary agent is absorbed by the mixed particles to obtain auxiliary agent particles;

[0027] The auxiliary agent particles are subjected to a second melt extrusion, and are subjected to cast molding, surface embossing, cooling, drawing, slitting and winding to obtain the halogen-free and phosphorus-free flame-retardant EVA film.

[0028] Optionally, the temperature of the first melt extrusion is 120°C-150°C and / or,

[0029] The temperature of the second melt extrusion is 60°C-100°C; and / or,

[0030] The parameters of the second stirring include: temperature of 30° C.-50° C., and time of 2-10 hours.

[0031] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0032] The embodiments of the present application provide a halogen-free and phosphorus-free flame-retardant EVA film. Through the synergistic effect of multiple raw materials, the flame retardant properties of the EVA film are improved in many aspects. First, the flame retardant masterbatch is the core component for improving the flame retardant properties and plays a key role in the EVA film. The flame retardant masterbatch usually contains highly efficient flame retardant elements or compounds that can decompose to produce free radical scavengers or form a stable protective layer when heated, thereby inhibiting the combustion reaction. For example, certain flame retardant masterbatches release inert gases at high temperatures, diluting the concentration of combustible gases and preventing the spread of flames. Secondly, the addition of thermal free radical initiators and cross-linking aids can promote the cross-linking reaction of the EVA film. The formation of the cross-linked structure forms a tight network between the molecular chains of the EVA film, improving the thermal stability and mechanical properties of the material. During the combustion process, the cross-linked network can reduce the thermal decomposition and dripping of the material, thereby reducing the combustion rate and heat release. At the same time, the cross-linked structure can also enhance the material's resistance to deformation, allowing it to maintain a certain shape at high temperatures, further hindering the spread of flames. The use of silane coupling agents significantly improves the compatibility between inorganic flame retardants and the EVA matrix. Inorganic flame retardants generally offer good flame retardancy, but their compatibility with the EVA matrix is ​​poor, which can lead to uneven dispersion. Silane coupling agents chemically connect the inorganic flame retardant to the EVA matrix, ensuring uniform dispersion within the matrix and improving flame retardancy. Furthermore, silane coupling agents form a dense inorganic oxide protective film during combustion, further preventing the transfer of heat and oxygen. The addition of antioxidants, UV absorbers, and light stabilizers enhances the performance of EVA films from the perspective of environmental stability. Antioxidants inhibit oxidation during processing and use, extending the material's service life. UV absorbers and light stabilizers absorb ultraviolet light and inhibit light-induced degradation, preventing accelerated aging and performance degradation under light exposure. The synergistic effect of these additives not only improves the flame retardancy of EVA films but also enhances their durability and stability in practical applications. In summary, this application improves the flame retardant properties of EVA film from multiple levels through the direct flame retardant effect of flame retardant masterbatch and the synergistic effect of thermal free radical initiators, cross-linking aids, silane coupling agents, etc., while taking into account the processing performance and service life of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following summarizes the drawings necessary for the embodiments or the description of the prior art. Obviously, for professionals in this field, other relevant drawings can be derived based on these drawings without creative efforts.

[0035] Figure 1 A flow chart of a halogen-free and phosphorus-free flame-retardant EVA film and a preparation method thereof provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] To more clearly illustrate the purpose, technical solutions, and advantages of the embodiments of the present application, the technical solutions of the embodiments are described in detail below with reference to the accompanying drawings. Please note that the embodiments described herein are merely illustrative and do not represent all possible implementation paths. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present application without creative effort are within the scope of protection of this application.

[0037] The ranges described herein, regardless of numerical values ​​or ratios, include all subranges and individual numerical values ​​therein. For example, when referring to '1 to 6' or '1-6', it means including any subrange from 1 to 6 (such as 1 to 3, 2 to 5) and all individual numbers (1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "include", "comprising", etc. used herein mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or simultaneously; expressions such as "at least one", "multiple", and "at least one" all refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the text, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments, and equipment used in this article can all be purchased on the market or prepared by existing methods.

[0038] In a first aspect, the present invention provides a halogen-free and phosphorus-free flame-retardant EVA film, comprising the following raw materials in parts by weight:

[0039] 100 parts of ethylene-vinyl acetate copolymer, 10-50 parts of flame retardant masterbatch, 0.5-1.0 parts of thermal free radical initiator, 0.5-2 parts of crosslinking aid, 0.3-2 parts of silane coupling agent, 0.1-0.5 parts of antioxidant, 0.05-1.0 parts of ultraviolet absorber, and 0.05-1.0 parts of light stabilizer.

[0040] Ethylene-vinyl acetate copolymer (EVA): A polymer material formed by the copolymerization of ethylene and vinyl acetate, with good flexibility, hot melt and adhesion. Flame retardant masterbatch: A granular material containing flame retardant ingredients, used to give the base material flame retardant properties. Thermal free radical initiator: A compound that can produce free radicals under thermal conditions, used to initiate polymerization reactions or cross-linking reactions. Cross-linking aid: A compound that promotes the formation of cross-linked structures between polymer molecular chains. Silane coupling agent: A compound that can connect organic polymers and inorganic materials, used to improve the compatibility and performance of materials. Antioxidant: An additive used to prevent oxidative degradation of materials. UV absorber: A compound that can absorb ultraviolet rays and prevent photodegradation of materials. Light stabilizer: An additive used to prevent aging of materials due to light exposure.

[0041] Ethylene-vinyl acetate copolymer (100 phr): Serves as the matrix material, providing the essential properties of EVA film, such as flexibility, adhesion, and hot melt properties. Flame retardant masterbatch (10-50 phr): A key component in enhancing the flame retardancy of EVA film. During combustion, the flame retardant masterbatch effectively inhibits the spread of the combustion reaction through multiple mechanisms, including endothermic decomposition, release of inert gases, and formation of a protective layer. For example, at a flame retardant masterbatch content of 10 phr, the flame retardant effect may be weak, but increasing the content to 50 phr significantly improves the flame retardancy. Thermal free radical initiator (0.5-1.0 phr): Initiates the crosslinking reaction between EVA molecular chains. This crosslinking structure improves the thermal stability and mechanical properties of the material and reduces dripping during combustion. For example, at a thermal free radical initiator content of 0.5 phr, the degree of crosslinking is low, while increasing it to 1.0 phr results in a higher crosslink density and improved flame retardancy. Crosslinking aid (0.5-2 phr): Further promotes the crosslinking reaction and enhances the stability of the crosslinked network. For example, when the cross-linking agent content is 0.5 parts, the cross-linking network is relatively sparse, but increasing it to 2 parts results in a denser cross-linking network, effectively preventing the spread of flames. Silane coupling agents (0.3-2 parts): Improve the compatibility of the inorganic flame retardant with the EVA matrix, ensuring uniform dispersion of the flame retardant within the matrix and enhancing flame retardant efficiency. Furthermore, silane coupling agents form a protective film during combustion, preventing the transfer of heat and oxygen. For example, when the silane coupling agent content is 0.3 parts, the compatibility improvement effect is limited, but increasing it to 2 parts significantly enhances both compatibility and flame retardancy. Antioxidants (0.1-0.5 parts): Prevent EVA from oxidative degradation during processing and use, extending the material's service life. For example, increasing the antioxidant content from 0.1 to 0.5 parts significantly enhances its antioxidant effect. UV absorbers (0.05-1.0 parts): Absorb ultraviolet rays, preventing EVA from aging and degradation due to light exposure. When the UV absorber content increases from 0.05 to 1.0 phr, a significant improvement in light stability can be observed. Light stabilizer (0.05-1.0 phr): Further enhances the light stability of EVA, preventing the material from degrading due to light exposure. Increasing the light stabilizer content from 0.05 to 1.0 phr can bring about a significant improvement in light stability. Example:

[0042] EVA: 100 parts;

[0043] Flame retardant masterbatch: 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc.

[0044] Thermal free radical initiator: 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1.0 part, etc.;

[0045] Cross-linking aid: 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, etc.;

[0046] Silane coupling agent: 0.3 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, etc.;

[0047] Antioxidant: 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, etc.;

[0048] UV absorber: 0.05 part, 0.2 part, 0.4 part, 0.6 part, 0.8 part, 1.0 part, etc.;

[0049] Light stabilizer: 0.05 part, 0.2 part, 0.4 part, 0.6 part, 0.8 part, 1.0 part, etc.

[0050] In some embodiments, the VA mass fraction of the ethylene-vinyl acetate copolymer is 15%-33%, and the melt index of the ethylene-vinyl acetate copolymer is 3-40 g / 10 min.

[0051] VA mass fraction: refers to the mass percentage of vinyl acetate (VA) in ethylene-vinyl acetate copolymer. Melt index: an indicator that measures the fluidity of a polymer melt. A higher value indicates better fluidity.

[0052] VA mass fraction (15%-33%): The VA content affects the flexibility, adhesion and hot melt properties of EVA. When the VA mass fraction is 15%, the EVA is harder and the flame retardant properties may be poor; when the VA mass fraction is 33%, the EVA is softer and the flame retardant properties are better. Melt index (3-40g / 10min): The melt index determines the fluidity of EVA during processing. When the melt index is 3g / 10min, the fluidity is poor and the processing is difficult; when the melt index is 40g / 10min, the fluidity is good and the processing is easier, but the flame retardant properties may be affected. Example:

[0053] VA quality fraction: 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 33%, etc.;

[0054] Melt index: 3g / 10min, 10g / 10min, 20g / 10min, 30g / 10min, 40g / 10min, etc.

[0055] In some embodiments, the raw materials for preparing the flame retardant masterbatch include polyborosiloxane and an inorganic hydroxide flame retardant.

[0056] Polyborosiloxane, as an organosilicon compound that combines boron and silicon elements, exhibits excellent thermal stability and significant flame retardant properties. Inorganic hydroxide flame retardants: such as magnesium hydroxide, aluminum hydroxide, etc., produce water vapor through endothermic decomposition to inhibit combustion. Polyborosiloxane: During the combustion process, polyborosiloxane can form a stable protective layer to prevent the transfer of heat and oxygen. At the same time, it has high thermal stability and can maintain its performance at high temperatures. Inorganic hydroxide flame retardants, with their ability to endothermically decompose, release a large amount of water vapor, which not only effectively reduces the combustion temperature, but also successfully curbs the spread of flames by diluting the concentration of combustible gases. For example, magnesium hydroxide and aluminum hydroxide decompose into magnesium oxide and aluminum oxide, respectively, during the combustion process, forming a dense protective layer.

[0057] In some embodiments, the inorganic hydroxide flame retardant includes at least one of the following: magnesium hydroxide, aluminum hydroxide; and / or,

[0058] The raw materials for preparing the polyborosiloxane include: terminal hydroxyl polydimethylsiloxane and boric acid.

[0059] During combustion, magnesium hydroxide decomposes into magnesium oxide and water, absorbing heat to achieve a cooling effect. The resulting magnesium oxide forms a solid protective layer, effectively blocking the transfer of heat and oxygen. Aluminum hydroxide decomposes into aluminum oxide and water during combustion, absorbing heat to achieve a cooling effect. The protective layer formed by the aluminum oxide prevents the transfer of heat and oxygen.

[0060] The preparation method of the polyborosiloxane comprises:

[0061] The hydroxyl-terminated polydimethylsiloxane (PDMS-OH) was dried at 110-120° C. under vacuum for at least 24 hours to remove its moisture.

[0062] The dried hydroxyl-terminated polydimethylsiloxane (PDMS-OH) is heated from room temperature to 140-150° C. in a kneader and then boric acid is added.

[0063] The mixed hydroxyl-terminated polydimethylsiloxane and boric acid are heated to 180-190° C. and reacted at this temperature for 2-4 hours.

[0064] The reactants were cooled to room temperature to obtain polyborosiloxane (PBDMS).

[0065] In some embodiments, the mass ratio of the polyborosiloxane to the inorganic hydroxide flame retardant is 5-10:1

[0066] Polyborosiloxane provides thermal stability, while the inorganic hydroxide flame retardant provides an endothermic decomposition mechanism. When the mass ratio is 5:1, the flame retardant effect mainly depends on the inorganic hydroxide; when the mass ratio is 10:1, the protective effect of polyborosiloxane is stronger, and the two synergistically improve the flame retardant performance. Example:

[0067] The mass ratio of polyborosiloxane to inorganic hydroxide flame retardant: 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0068] In some embodiments, the compatibilizer includes at least one of: bis-(-3-triethoxysilylpropyl)-disulfide, 3-aminopropyltriethoxysilane; and / or,

[0069] The thermal free radical initiator includes at least one of the following: dicumyl peroxide, dibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl ester; and / or,

[0070] The cross-linking auxiliary agent includes at least one of the following: triallyl cyanurate, triallyl isocyanurate, polytriallyl isocyanurate; and / or,

[0071] The silane coupling agent includes at least one of the following: 3-(methacryloyloxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane.

[0072] Compatibilizers, such as bis-(3-triethoxysilylpropyl)-disulfide, are intended to enhance the compatibility of inorganic flame retardants with the EVA matrix, ensure uniform dispersion of the flame retardant, and thus improve flame retardant efficiency. Thermal free radical initiators, such as diisopropyl peroxide, mainly function to initiate cross-linking reactions between EVA molecular chains, thereby enhancing the thermal stability and mechanical properties of the material. Cross-linking aids, such as triallyl cyanurate, can further promote the progress of the cross-linking reaction, thereby enhancing the stability of the cross-linked network. Silane coupling agents, such as 3-(methacryloyloxy)propyltrimethoxysilane, not only improve the compatibility of inorganic flame retardants with the EVA matrix, but also form a protective film during combustion, effectively blocking the transfer of heat and oxygen.

[0073] In some embodiments, the antioxidant includes at least one of the following: β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6-di-tert-butyl-4-methylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4,4'-thiobis(6-tert-butyl-3-methylphenol); and / or,

[0074] The ultraviolet absorber includes at least one of the following: 2-hydroxy-4-n-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)-benzotriazole, 2-[2,4-bis(2,4-xylyl)-2-(1,3,5-triazinyl)-octyloxyphenol], 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol; and / or,

[0075] The light stabilizer includes at least one of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol) succinate, and 2,2,6,6-tetramethylpiperidinyl hexamethylenediamine.

[0076] Antioxidants, such as β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, prevent EVA from oxidative degradation during processing and use, extending the material's service life. UV absorbers, such as 2-hydroxy-4-n-octyloxybenzophenone, absorb ultraviolet light to prevent EVA from aging and degradation due to light exposure. Light stabilizers, such as bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, further enhance EVA's light stability and prevent performance degradation due to light exposure.

[0077] In some embodiments, the thickness of the EVA film is 0.3 mm to 0.8 mm; and / or,

[0078] The upper surface and the lower surface of the EVA film are respectively embossed with geometric patterns.

[0079] VA film thickness (0.3mm-0.8mm): Thinner films are more flexible in processing and application, while reducing material consumption and lowering costs. For example, 0.3mm film is thinner and suitable for lightweight applications, while 0.8mm film is thicker and has better flame retardant properties. Geometric patterns: Embossing the surface of EVA film not only improves its aesthetics, but also increases the friction coefficient and effectively prevents slippage. In addition, these pattern designs can also be applied to specific scenarios, such as anti-counterfeiting logos and decorative beautification. Example:

[0080] The thickness of the EVA film can be: 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.;

[0081] The geometric patterns on the surface of the EVA film include but are not limited to: diamond patterns, grid patterns, dot patterns and striped patterns.

[0082] Figure 1 This is a flow chart of a method for preparing a halogen-free and phosphorus-free flame-retardant EVA film provided in an embodiment of the present application.

[0083] See Figure 1 In a second aspect, an embodiment of the present application further provides a method for preparing the halogen-free and phosphorus-free flame-retardant EVA film according to the first aspect, comprising:

[0084] The polyborosiloxane is modified with a compatibilizer to form a transparent colloid;

[0085] adding an inorganic hydroxide flame retardant to the transparent colloid, and performing a first stirring to obtain a mixed colloid;

[0086] mixing a portion of ethylene-vinyl acetate copolymer with the mixture colloid to granulate through a first melt extrusion to obtain a flame retardant masterbatch;

[0087] mixing a thermal free radical initiator, a crosslinking auxiliary agent, a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer to obtain a mixed auxiliary agent;

[0088] mixing the remaining portion of the ethylene-vinyl acetate copolymer with the flame retardant masterbatch to obtain mixed particles;

[0089] spraying the mixing auxiliary agent on the surface of the mixed particles, and performing a second stirring on the mixed particles so that the mixing auxiliary agent is absorbed by the mixed particles to obtain auxiliary agent particles;

[0090] The auxiliary agent particles are subjected to a second melt extrusion, and are subjected to cast molding, surface embossing, cooling, drawing, slitting and winding to finally produce the halogen-free and phosphorus-free flame-retardant EVA film.

[0091] In some embodiments, the temperature of the first melt extrusion is 120°C-150°C and / or,

[0092] The temperature of the second melt extrusion is 60°C-100°C; and / or,

[0093] The parameters of the second stirring include: temperature of 30° C.-50° C., and time of 2-10 hours.

[0094] First melt extrusion temperature (120℃-150℃): This temperature range ensures that the polyborosiloxane and inorganic hydroxide flame retardant can be evenly dispersed to form a stable flame retardant masterbatch, just as shown in polycarbonate materials. For example, at 120℃, the dispersion effect is poor; while at 150℃, the dispersion effect is better. Second melt extrusion temperature (60℃-100℃): The lower temperature range ensures that the EVA film will not be excessively degraded during the molding process, while ensuring that the additive particles can be evenly dispersed. For example, at 60℃, the molding speed is slower; while at 100℃, the molding speed is faster. The parameter setting of the second stirring step (temperature of 30℃-50℃, time of 2-10 hours) is intended to ensure that the additive particles can fully absorb the mixed additives, thereby improving the overall performance of the material. For example, at 30℃, the absorption rate is slower; while at 50℃, the absorption rate is faster; the longer the stirring time, the more complete the absorption of the additives. Example:

[0095] The temperature of the first melt extrusion can be: 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, etc.;

[0096] The temperature of the second melt extrusion can be: 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.;

[0097] The temperature of the second stirring can be: 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, etc.; the time of the second stirring can be: 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0098] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0099] Example 1

[0100] Raw material ratio:

[0101] Ethylene vinyl acetate copolymer (EVA): 100 parts, VA content is 28%, melt index is 6g / 10min

[0102] Flame retardant masterbatch: 20 parts (compound flame retardant is PBDMS and magnesium hydroxide, mass ratio PBDMS: magnesium aluminum flame retardant = 5:1)

[0103] Thermal free radical initiator: 0.6 parts (tert-butyl peroxycarbonate-2-ethylhexyl ester)

[0104] Crosslinking aid: 0.6 parts (triallyl isocyanurate)

[0105] Silane coupling agent: 0.7 parts (3-(methacryloyloxy)propyltrimethoxysilane)

[0106] Antioxidant: 0.2 parts (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

[0107] UV absorber: 0.1 part (2-hydroxy-4-n-octyloxybenzophenone)

[0108] Light stabilizer: 0.1 parts (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[0109] Preparation method:

[0110] Polyborosiloxane (PBDMS) was compatibilized and modified using Si-75 compatibilizer to form a transparent colloid.

[0111] Magnesium hydroxide is added into the transparent colloid, and a mixed colloid is obtained through a first stirring.

[0112] A portion of EVA is mixed with the mixture colloid, and granulated through a first melt extrusion to obtain a flame retardant masterbatch.

[0113] A thermal free radical initiator, a cross-linking auxiliary agent, a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer are mixed to obtain a mixed auxiliary agent.

[0114] The remaining portion of EVA is mixed with the flame retardant masterbatch to obtain mixed particles.

[0115] The mixing aid is sprayed on the surface of the mixed particles, and the mixed particles are subjected to a second stirring (temperature of 30° C.-50° C., time of 2-10 hours) to allow the mixing aid to be absorbed by the mixed particles to obtain additive particles.

[0116] The auxiliary agent particles are subjected to a second melt extrusion (temperature of 60° C.-100° C.), and are subjected to tape casting, surface embossing, cooling, drawing, slitting and winding to obtain the halogen-free and phosphorus-free flame-retardant EVA film.

[0117] Example 2

[0118] Raw material ratio:

[0119] Ethylene vinyl acetate copolymer (EVA): 100 parts, VA content is 28%, melt index is 6g / 10min

[0120] Flame retardant masterbatch: 20 parts (compound flame retardant is PBDMS and aluminum hydroxide, mass ratio PBDMS: magnesium aluminum flame retardant = 5:1)

[0121] Thermal free radical initiator: 0.6 parts (tert-butyl peroxycarbonate-2-ethylhexyl ester)

[0122] Crosslinking aid: 0.6 parts (triallyl isocyanurate)

[0123] Silane coupling agent: 0.7 parts (3-(methacryloyloxy)propyltrimethoxysilane)

[0124] Antioxidant: 0.2 parts (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

[0125] UV absorber: 0.1 part (2-hydroxy-4-n-octyloxybenzophenone)

[0126] Light stabilizer: 0.1 parts (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[0127] Preparation method: same as Example 1.

[0128] Example 3

[0129] Raw material ratio:

[0130] Ethylene vinyl acetate copolymer (EVA): 100 parts, VA content is 28%, melt index is 6g / 10min

[0131] Flame retardant masterbatch: 25 parts (compound flame retardant is PBDMS and magnesium hydroxide, mass ratio PBDMS: magnesium aluminum flame retardant = 5:1)

[0132] Thermal free radical initiator: 0.6 parts (tert-butyl peroxycarbonate-2-ethylhexyl ester)

[0133] Crosslinking aid: 0.6 parts (triallyl isocyanurate)

[0134] Silane coupling agent: 0.7 parts (3-(methacryloyloxy)propyltrimethoxysilane)

[0135] Antioxidant: 0.2 parts (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

[0136] UV absorber: 0.1 part (2-hydroxy-4-n-octyloxybenzophenone)

[0137] Light stabilizer: 0.1 parts (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[0138] Preparation method: same as Example 1.

[0139] Example 4

[0140] Raw material ratio:

[0141] Ethylene vinyl acetate copolymer (EVA): 100 parts, VA content is 28%, melt index is 6g / 10min

[0142] Flame retardant masterbatch: 30 parts (compound flame retardant is PBDMS and magnesium hydroxide, mass ratio PBDMS: magnesium aluminum flame retardant = 5:1)

[0143] Thermal free radical initiator: 0.6 parts (tert-butyl peroxycarbonate-2-ethylhexyl ester)

[0144] Crosslinking aid: 0.6 parts (triallyl isocyanurate)

[0145] Silane coupling agent: 0.7 parts (3-(methacryloyloxy)propyltrimethoxysilane)

[0146] Antioxidant: 0.2 parts (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

[0147] UV absorber: 0.1 part (2-hydroxy-4-n-octyloxybenzophenone)

[0148] Light stabilizer: 0.1 parts (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[0149] Preparation method: same as Example 1.

[0150] Comparative Example 1

[0151] Note: In Comparative Example 1, PBDMS was not added, and only magnesium hydroxide was used as a flame retardant to compare the effect of PBDMS on flame retardancy.

[0152] Raw material ratio:

[0153] Ethylene vinyl acetate copolymer (EVA): 100 parts, VA content is 28%, melt index is 6g / 10min

[0154] Flame retardant masterbatch: 20 parts (contains only magnesium hydroxide, does not contain PBDMS)

[0155] Thermal free radical initiator: 0.6 parts (tert-butyl peroxycarbonate-2-ethylhexyl ester)

[0156] Crosslinking aid: 0.6 parts (triallyl isocyanurate)

[0157] Silane coupling agent: 0.7 parts (3-(methacryloyloxy)propyltrimethoxysilane)

[0158] Antioxidant: 0.2 parts (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

[0159] UV absorber: 0.1 part (2-hydroxy-4-n-octyloxybenzophenone)

[0160] Light stabilizer: 0.1 parts (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[0161] Preparation method:

[0162] Polyborosiloxane (PBDMS) was compatibilized and modified using Si-75 compatibilizer to form a transparent colloid.

[0163] Magnesium hydroxide is added into the transparent colloid, and a mixed colloid is obtained through a first stirring.

[0164] A portion of EVA is mixed with the mixture colloid, and granulated through a first melt extrusion to obtain a flame retardant masterbatch.

[0165] A thermal free radical initiator, a cross-linking auxiliary agent, a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer are mixed to obtain a mixed auxiliary agent.

[0166] The remaining portion of EVA is mixed with the flame retardant masterbatch to obtain mixed particles.

[0167] The mixing aid is sprayed on the surface of the mixed particles, and the mixed particles are subjected to a second stirring (temperature of 30° C.-50° C., time of 2-10 hours) to allow the mixing aid to be absorbed by the mixed particles to obtain additive particles.

[0168] The auxiliary agent particles are subjected to a second melt extrusion (temperature of 60° C.-100° C.), and are subjected to tape casting, surface embossing, cooling, drawing, slitting and winding to obtain the EVA film.

[0169] Comparative Example 2

[0170] Note: In Comparative Example 2, no inorganic hydroxide flame retardant was added, and only PBDMS was used as a flame retardant to compare the effect of the inorganic hydroxide flame retardant on the flame retardant performance.

[0171] Raw material ratio:

[0172] Ethylene vinyl acetate copolymer (EVA): 100 parts, VA content is 28%, melt index is 6g / 10min

[0173] Flame retardant masterbatch: 20 parts (contains only PBDMS, no magnesium hydroxide or aluminum hydroxide)

[0174] Thermal free radical initiator: 0.6 parts (tert-butyl peroxycarbonate-2-ethylhexyl ester)

[0175] Crosslinking aid: 0.6 parts (triallyl isocyanurate)

[0176] Silane coupling agent: 0.7 parts (3-(methacryloyloxy)propyltrimethoxysilane)

[0177] Antioxidant: 0.2 parts (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)

[0178] UV absorber: 0.1 part (2-hydroxy-4-n-octyloxybenzophenone)

[0179] Light stabilizer: 0.1 parts (bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate)

[0180] Preparation method:

[0181] Polyborosiloxane (PBDMS) was compatibilized and modified using Si-75 compatibilizer to form a transparent colloid.

[0182] PBDMS is added to the transparent colloid, and a mixture colloid is obtained through a first stirring.

[0183] A portion of EVA is mixed with the mixture colloid, and granulated through a first melt extrusion to obtain a flame retardant masterbatch.

[0184] A thermal free radical initiator, a cross-linking auxiliary agent, a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer are mixed to obtain a mixed auxiliary agent.

[0185] The remaining portion of EVA is mixed with the flame retardant masterbatch to obtain mixed particles.

[0186] The mixing aid is sprayed on the surface of the mixed particles, and the mixed particles are subjected to a second stirring (temperature of 30° C.-50° C., time of 2-10 hours) to allow the mixing aid to be absorbed by the mixed particles to obtain additive particles.

[0187] The auxiliary agent particles are subjected to a second melt extrusion (temperature of 60° C.-100° C.), and are subjected to tape casting, surface embossing, cooling, drawing, slitting and winding to obtain the EVA film.

[0188] Effect data: The effect data of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1.

[0189] Experimental methods for effect data:

[0190] 1. Flame retardant performance test: Tested in accordance with UL-94 standard.

[0191] Test indicators: flame retardant grade (V-0, V-1, V-2).

[0192] 2. Transparency test: Use a spectrophotometer to measure the light transmittance of the film.

[0193] Test index: light transmittance (%).

[0194] 3. Adhesion performance test: 180° peel strength test is carried out according to ASTM D1000 standard.

[0195] Test index: peel strength (N / cm).

[0196] 4. UV aging resistance test: UV aging test is carried out in accordance with ISO 4892 standard, with a test cycle of 1000 hours.

[0197] Test index: light transmittance retention rate after aging (%).

[0198] Table 1

[0199]

[0200] The above effect data table can intuitively compare the differences between different examples and comparative examples. The following conclusions can be drawn:

[0201] Examples 1 to 4: All use a compound system of PBDMS and an inorganic hydroxide flame retardant (magnesium hydroxide or aluminum hydroxide), which exhibits excellent flame retardant properties (V-0 grade), high transparency (84%-87% transmittance), good bonding properties (3.4-3.7N / cm peel strength), and good UV aging resistance (transmittance retention rate after aging 80%-82%).

[0202] Comparative Example 1: Using only magnesium hydroxide as a flame retardant, the flame retardant performance is slightly poor (V-1 grade), and the transparency and adhesion performance are also slightly low. Comparative Example 2: Using only PBDMS as a flame retardant, the flame retardant performance is slightly poor (V-1 grade), and the transparency and UV aging resistance are also slightly low.

[0203] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A halogen-free and phosphorus-free flame-retardant EVA film, comprising the following raw materials in parts by weight: 100 parts of ethylene-vinyl acetate copolymer, 10-50 parts of flame retardant masterbatch, 0.5-1.0 parts of thermal free radical initiator, 0.5-2 parts of crosslinking aid, 0.3-2 parts of silane coupling agent, 0.1-0.5 parts of antioxidant, 0.05-1.0 parts of ultraviolet absorber, and 0.05-1.0 parts of light stabilizer.

2. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 1, characterized in that: The VA mass fraction of the ethylene-vinyl acetate copolymer is 15%-33%, and the melt index of the ethylene-vinyl acetate copolymer is 3-40 g / 10 min.

3. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 1, characterized in that: The raw materials for preparing the flame retardant masterbatch include polyborosiloxane and an inorganic hydroxide flame retardant.

4. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 3, characterized in that: The inorganic hydroxide flame retardant includes at least one of the following: magnesium hydroxide, aluminum hydroxide; and / or The raw materials for preparing the polyborosiloxane include: terminal hydroxyl polydimethylsiloxane and boric acid.

5. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 3, characterized in that: The mass ratio of the polyborosiloxane to the inorganic hydroxide flame retardant is 5-10:

1.

6. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 1, characterized in that: The compatibilizer includes at least one of the following: bis-(-3-triethoxysilylpropyl)-disulfide, 3-aminopropyltriethoxysilane; and / or The thermal free radical initiator includes at least one of the following: dicumyl peroxide, dibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl ester; and / or, The cross-linking auxiliary agent includes at least one of the following: triallyl cyanurate, triallyl isocyanurate, polytriallyl isocyanurate; and / or, The silane coupling agent includes at least one of the following: 3-(methacryloyloxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and γ-aminoethylaminopropyltrimethoxysilane.

7. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 1, characterized in that: The antioxidant comprises at least one of: β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,6-di-tert-butyl-4-methylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl)hexanediamine, 4,4'-thiobis(6-tert-butyl-3-methylphenol); and / or The ultraviolet absorber includes at least one of the following: 2-hydroxy-4-n-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)-benzotriazole, 2-[2,4-bis(2,4-xylyl)-2-(1,3,5-triazinyl)-octyloxyphenol], 2-(2H-benzotriazole-2-yl)-6-dodecyl-4-methylphenol; and / or, The light stabilizer includes at least one of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol) succinate, and 2,2,6,6-tetramethylpiperidinyl hexamethylenediamine.

8. The halogen-free and phosphorus-free flame-retardant EVA film according to claim 1, characterized in that: The thickness of the EVA film is 0.3mm-0.8mm; and / or, The upper surface and the lower surface of the EVA film are respectively embossed with geometric patterns.

9. A method for preparing the halogen-free and phosphorus-free flame-retardant EVA film according to any one of claims 1 to 8, comprising: The polyborosiloxane is modified with a compatibilizer to form a transparent colloid; adding an inorganic hydroxide flame retardant to the transparent colloid, and performing a first stirring to obtain a mixed colloid; mixing a portion of ethylene-vinyl acetate copolymer with the mixture colloid to granulate through a first melt extrusion to obtain a flame retardant masterbatch; mixing a thermal free radical initiator, a crosslinking auxiliary agent, a silane coupling agent, an antioxidant, an ultraviolet absorber and a light stabilizer to obtain a mixed auxiliary agent; mixing the remaining portion of the ethylene-vinyl acetate copolymer with the flame retardant masterbatch to obtain mixed particles; spraying the mixing auxiliary agent on the surface of the mixed particles, and performing a second stirring on the mixed particles so that the mixing auxiliary agent is absorbed by the mixed particles to obtain auxiliary agent particles; The auxiliary agent particles are subjected to a second melt extrusion, and are subjected to cast molding, surface embossing, cooling, drawing, slitting and winding to obtain the halogen-free and phosphorus-free flame-retardant EVA film.

10. The preparation method according to claim 9, characterized in that The temperature of the first melt extrusion is 120°C-150°C and / or, The temperature of the second melt extrusion is 60°C-100°C; and / or, The parameters of the second stirring include: temperature of 30° C.-50° C., and time of 2-10 hours.

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