A low smoke, flame retardant ethylene vinyl acetate copolymer composition and a process for its preparation

Abstract

This invention discloses a low-smoke flame-retardant ethylene-vinyl acetate copolymer composition and its preparation method, relating to the field of polymer materials technology. 80-100 parts of ethylene-vinyl acetate copolymer, 8-20 parts of inorganic phosphorus-based flame retardant, 1-3 parts of auxiliary flame retardant, and 0.05-2 parts of antioxidant are added to a high-speed mixer and mixed evenly. The evenly mixed material is fed into a twin-screw extruder for extrusion granulation. The material is fully melted under the shearing, mixing, and conveying action of the screws. Finally, the product is produced after extrusion, stranding, and cooling. The product of this invention can be widely used in fields such as wires and cables, fire-resistant building materials, automotive parts, and electronic appliances.

Description

Technical Field

[0001] This invention belongs to the field of polymer modification, and specifically relates to a low-smoke flame-retardant ethylene-vinyl acetate copolymer composition and its preparation method. Background Technology

[0002] Ethylene-vinyl acetate copolymer, also known as EVA resin, typically contains 5% to 40% vinyl acetate (VA). Compared to polyethylene, EVA, due to the introduction of vinyl acetate monomers into its molecular chain, exhibits reduced crystallinity and improved flexibility, impact resistance, filler compatibility, and heat-sealing properties. It is widely used in foamed shoe materials, functional greenhouse films, packaging films, hot melt adhesives, wires and cables, and toys. Generally, the performance of EVA resin depends primarily on the vinyl acetate content in its molecular chain. EVA has excellent low-temperature resistance, with a relatively low thermal decomposition temperature of approximately 230°C. As the molecular weight increases, the softening point of EVA rises, and processability and surface gloss of finished products decrease, but strength increases, and impact toughness and resistance to environmental stress cracking improve. EVA's resistance to chemicals and oils is slightly inferior to PE and PVC, and this variation becomes more pronounced with increasing vinyl acetate content.

[0003] With the continuous development of computer and network engineering, and for the sake of computer room security, people are increasingly using halogen-free flame-retardant cables and silane cross-linked cables. Because EVA resin has good filler compatibility and cross-linking properties, it is widely used in halogen-free flame-retardant cables, semiconductor shielded cables, and two-step silane cross-linked cables.

[0004] However, ethylene-vinyl acetate copolymers produce a large amount of toxic gases and smoke when burned. Therefore, it is necessary to modify the ethylene-vinyl acetate copolymer compositions and their preparation methods to improve their flame retardant properties and reduce their smoke emission. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-smoke flame-retardant ethylene-vinyl acetate copolymer composition and its preparation method.

[0006] A low-smoke flame-retardant ethylene-vinyl acetate copolymer composition comprising the following components and their weight fractions:

[0007] 80-100 parts of ethylene-vinyl acetate copolymer

[0008] 8-20 parts of inorganic phosphorus flame retardant

[0009] 1-3 parts of auxiliary flame retardant

[0010] Antioxidant 0.05-2 parts

[0011] The vinyl acetate content in the ethylene-vinyl acetate copolymer is 10%-30%.

[0012] The melt index of the ethylene-vinyl acetate copolymer is 3-5 g / 10 min (190℃, 2.16 kg).

[0013] The inorganic phosphorus-based flame retardant is preferably a red phosphorus flame retardant.

[0014] The red phosphorus flame retardant is preferably a coated red phosphorus flame retardant.

[0015] The auxiliary flame retardant is a complex of molybdenum compound and organomontmorillonite, and the preferred weight ratio of molybdenum compound to organomontmorillonite is (1):(2-4).

[0016] The molybdenum compound is preferably one of ammonium octamolate or molybdenum trioxide.

[0017] Organic montmorillonite includes sodium-based montmorillonite and calcium-based montmorillonite.

[0018] The preferred particle size of the montmorillonite is 1000-3000 mesh.

[0019] The polar vinyl acetate (VA) groups in ethylene vinyl acetate copolymer (EVA) have excellent binding ability with organomontmorillonite (OMMT). When organomontmorillonite and molybdenum compounds are added to ethylene vinyl acetate copolymer in a homogeneous mixture, the binding force between them is further enhanced, and the homogeneity is further improved.

[0020] The antioxidant is selected from at least one of antioxidant 1076, antioxidant 168, antioxidant 1010, antioxidant 1098, and antioxidant 300.

[0021] The present invention also provides a method for preparing a low-smoke flame-retardant ethylene-vinyl acetate copolymer composition, the method comprising the following steps:

[0022] Add 80-100 parts of ethylene-vinyl acetate copolymer, 8-20 parts of inorganic phosphorus flame retardant, 1-3 parts of auxiliary flame retardant, and 0.05-2 parts of antioxidant to a high-speed mixer and mix evenly. Feed the evenly mixed material into a twin-screw extruder through a feeding device for extrusion granulation. The material is fully melted under the shearing, mixing, and conveying of the screw. Finally, the product is made after extrusion, stranding, and cooling. The temperature of each section of the extruder is set as follows: feeding section 100-150℃, melting section 150-200℃, and homogenization section 170-200℃.

[0023] Beneficial effects:

[0024] Compared with commercially available ammonium octamolate and molybdenum trioxide, the auxiliary flame retardant in the ethylene-vinyl acetate copolymer composition of the present invention not only enables the composition to achieve the UL94 V0 level with a smaller amount of red phosphorus flame retardant added, but also significantly reduces the smoke emission of the composition.

[0025] The product of this invention can be widely used in fields such as wires and cables, fireproof building materials, automotive parts, and electronic appliances. Detailed Implementation

[0026] Unless otherwise specified, all raw materials used in this invention are commercially available or prepared according to conventional methods in the art. Unless otherwise defined or stated, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. Other aspects of this invention will be apparent to those skilled in the art from the disclosure herein. The invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0027] Unless otherwise specified, experimental methods in the following examples are generally performed according to national standards. If no corresponding national standard exists, general international standards, standard conditions, or conditions recommended by the manufacturer are followed. Unless otherwise stated, all parts are parts by weight, and all percentages are weight percentages.

[0028] It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of this invention. These all fall within the scope of protection of this invention.

[0029] In the following examples and comparative examples, some raw material specifications and sources are described, but not limited to these materials:

[0030] Ethylene-vinyl acetate copolymer, Arkema 33-45 (France).

[0031] The coated red phosphorus flame retardant is a whitened coated red phosphorus flame retardant, Guangdong Fantian Technology FT-6101.

[0032] Ammonium octamolate, Ba Shifu (Shanghai) Biomedical Technology Co., Ltd.

[0033] Molybdenum trioxide, Pande (Shanghai) International Trading Co., Ltd.

[0034] Montmorillonite is classified into sodium-based montmorillonite and calcium-based montmorillonite. Sodium-based montmorillonite has an average particle size of 2000 mesh, while calcium-based montmorillonite has average particle sizes of 1000 mesh, 2000 mesh, and 3000 mesh. (Source: Lingshou County Tuolin Mineral Products Processing Company)

[0035] Antioxidant 1010 and Antioxidant 168, BASF, Germany.

[0036] The present invention will be further described below with reference to embodiments, which are intended only to better understand the purpose of the present invention and not to limit the scope of protection of the present invention.

[0037] Example 1

[0038] 80 parts of ethylene-vinyl acetate copolymer, 8 parts of coated red phosphorus flame retardant, 1 part of auxiliary flame retardant, and 0.05 parts of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 100℃, melting section 150℃, and homogenization section 170℃.

[0039] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(2). The molybdenum compound is molybdenum trioxide, and the montmorillonite is calcium-based montmorillonite with a particle size of 1000 mesh.

[0040] Example 2

[0041] 100 parts of ethylene-vinyl acetate copolymer, 18 parts of coated red phosphorus flame retardant, 3 parts of auxiliary flame retardant, and 1.5 parts of antioxidant 168 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing, and conveying of the screw. Finally, the product was made after extrusion, stranding, and cooling. The temperature of each section of the extruder was set as follows: feeding section 150℃, melting section 190℃, and homogenization section 200℃.

[0042] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(4). The molybdenum compound is ammonium octamolate, and the montmorillonite is calcium-based montmorillonite with a particle size of 3000 mesh.

[0043] Example 3

[0044] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0045] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(3). The molybdenum compound is ammonium octamolate, and the montmorillonite is calcium-based montmorillonite with a particle size of 2000 mesh.

[0046] Example 4

[0047] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0048] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(3). The molybdenum compound is ammonium octamolate, and the montmorillonite is sodium-based montmorillonite with a particle size of 2000 mesh.

[0049] Example 5

[0050] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0051] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(3). The molybdenum compound is molybdenum trioxide, and the montmorillonite is calcium-based montmorillonite with a particle size of 2000 mesh.

[0052] Example 6

[0053] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0054] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(2). The molybdenum compound is molybdenum trioxide, and the montmorillonite is calcium-based montmorillonite with a particle size of 2000 mesh.

[0055] Example 7

[0056] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0057] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(3). The molybdenum compound is ammonium octamolate, and the montmorillonite is calcium-based montmorillonite with a particle size of 1000 mesh.

[0058] Comparative Example 1

[0059] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0060] The auxiliary flame retardant is ammonium octamolate.

[0061] Comparative Example 2

[0062] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0063] The auxiliary flame retardant is molybdenum trioxide.

[0064] Comparative Example 3

[0065] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0066] The auxiliary flame retardant is calcium-based montmorillonite with a particle size of 2000 mesh.

[0067] Comparative Example 4

[0068] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0069] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(1). The molybdenum compound is ammonium octamolate, and the montmorillonite is calcium-based montmorillonite with a particle size of 2000 mesh.

[0070] Comparative Example 5

[0071] 90 parts of ethylene-vinyl acetate copolymer, 10 parts of coated red phosphorus flame retardant, 2 parts of auxiliary flame retardant, and 1 part of antioxidant 1010 were added to a high-speed mixer and mixed evenly. The evenly mixed material was fed into a twin-screw extruder through a feeding device for extrusion granulation. The material was fully melted under the shearing, mixing and conveying of the screw. Finally, the product was made after extrusion, stretching and cooling. The temperature of each section of the extruder was set as follows: feeding section 120℃, melting section 170℃, and homogenization section 180℃.

[0072] The weight ratio of molybdenum compound to organomontmorillonite in the auxiliary flame retardant is (1):(8). The molybdenum compound is ammonium octamolate, and the montmorillonite is calcium-based montmorillonite with a particle size of 2000 mesh.

[0073] Test methods for each embodiment and comparative example product:

[0074] Flame retardant performance was tested according to UL-94 standard, with a sample thickness of 1.6 mm and vertical burning.

[0075] The maximum smoke density Dm was tested according to the GB / T8323-2008 standard.

[0076] Please see Table 1 for specific data.

[0077] Table 1. Performance test results of the examples and comparative examples.

[0078] Flame retardant UL94 Maximum smoke density Dm Example 1 V0 117 Example 2 V0 93 Example 3 V0 96 Example 4 V0 101 Example 5 V0 109 Example 6 V0 102 Example 7 V0 105 Comparative Example 1 V1 174 Comparative Example 2 V1 165 Comparative Example 3 V2 272 Comparative Example 4 V1 114 Comparative Example 5 V1 114

[0079] As can be seen from the table above, compared with the commonly available ammonium octamolate and molybdenum trioxide, the auxiliary flame retardant in the ethylene-vinyl acetate copolymer composition of the present invention can not only achieve the UL94 V0 level with a smaller amount of red phosphorus flame retardant added, but also significantly reduce the smoke emission of the composition.

[0080] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A low-smoke flame-retardant ethylene-vinyl acetate copolymer composition, characterized in that, It is prepared from the following components in parts by weight: 80-100 parts of ethylene-vinyl acetate copolymer 8-20 parts of inorganic phosphorus flame retardant 1-3 parts of auxiliary flame retardant Antioxidant 0.05-2 parts.

2. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 1, characterized in that, The vinyl acetate content in the ethylene-vinyl acetate copolymer is 10%-30%; the melt index of the ethylene-vinyl acetate copolymer is 3-5 g / 10 min (190℃, 2.16 kg).

3. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 1, characterized in that, The inorganic phosphorus-based flame retardant mentioned is a red phosphorus flame retardant.

4. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 3, characterized in that, The red phosphorus flame retardant mentioned above is a coated red phosphorus flame retardant.

5. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 1, characterized in that, The auxiliary flame retardant is a complex of molybdenum compound and organomontmorillonite, with a weight ratio of molybdenum compound to organomontmorillonite of (1):(2-4).

6. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 5, characterized in that, The molybdenum compound is either ammonium octamolate or molybdenum trioxide; the organomontmorillonite is either sodium-based montmorillonite or calcium-based montmorillonite.

7. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 6, characterized in that, The montmorillonite has a particle size of 1000-3000 mesh.

8. The low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 1, characterized in that, The antioxidant is selected from at least one of antioxidant 1076, antioxidant 168, antioxidant 1010, antioxidant 1098, and antioxidant 300.

9. A method for preparing a low-smoke flame-retardant ethylene-vinyl acetate copolymer composition, comprising the following steps: Add 80-100 parts of ethylene-vinyl acetate copolymer, 8-20 parts of inorganic phosphorus flame retardant, 1-3 parts of auxiliary flame retardant, and 0.05-2 parts of antioxidant to a high-speed mixer and mix evenly. Feed the evenly mixed material into a twin-screw extruder through a feeding device for extrusion granulation. The material is fully melted under the shearing, mixing, and conveying of the screw. Finally, the product is made after extrusion, stretching, and cooling.

10. The method for preparing a low-smoke flame-retardant ethylene-vinyl acetate copolymer composition as described in claim 9, characterized in that, The extruder temperature is set as follows: feeding section 100-150℃, melting section 150-200℃, homogenization section 170-200℃.