Flame-retardant polyvinyl alcohol composite material capable of being subjected to thermoplastic processing and preparation method thereof

Abstract

The invention discloses a thermoplastic processing flame-retardant polyvinyl alcohol composite material and a preparation method thereof, and relates to the technical field of thermoplastic materials, the composite material is prepared from the following raw materials by weight: 100 parts of thermoplastic polyvinyl alcohol, 10-30 parts of an inorganic filler, 5-20 parts of a plasticizer, 5-20 parts of a flame retardant, 0.05-1 part of an antioxidant, and 0.05-1 part of an anti-ultraviolet agent; the polyvinyl alcohol is endowed with certain flame retardant property through chemical modification, and the flame retardant durability of the polyvinyl alcohol composite material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of thermoplastic materials, and in particular to a flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing and a preparation method thereof. Background Art

[0002] Most polymer materials are composed of carbon and hydrogen elements and are easy to burn. Plastic films are easy to burn because of their large surface area and easy heat conduction. In recent years, with the rapid development of high-tech fields such as new energy vehicles, advanced photovoltaics, new energy storage, and artificial intelligence, higher requirements have been placed on the flame retardant properties of plastic films and the environmental performance of flame retardants. It is urgent to develop new environmentally friendly flame retardant plastic films that have excellent physical and mechanical properties and flame retardant properties to meet the needs of the rapidly developing high-tech fields for high-performance polymer functional films.

[0003] As an environmentally friendly polymer material with excellent comprehensive performance, polyvinyl alcohol (PVA) has a wide range of theoretical applications, but because its melting point (226°C) and decomposition temperature (230-250°C) are very close, it is difficult to process by thermoplastics. In addition, the limiting oxygen index (LOI) of PVA is only 20%, which is very easy to ignite and accompanied by molten droplets, and there are great safety hazards in actual use. Therefore, improving the thermoplastic processability of PVA and preparing environmentally friendly film products with excellent mechanical and flame retardant properties are of great significance to broadening the application of PVA. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a flame-retardant polyvinyl alcohol composite material that can be thermoplastic processed and a preparation method thereof, and to give polyvinyl alcohol certain flame-retardant properties through chemical modification to improve the flame-retardant durability of the polyvinyl alcohol composite material.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] The first object of the present invention is to provide a flame retardant polyvinyl alcohol composite material that can be thermoplastic processed, which is made of the following raw materials in parts by weight:

[0007] 100 parts of thermoplastic polyvinyl alcohol, 10-30 parts of inorganic filler, 5-20 parts of plasticizer, 5-20 parts of flame retardant, 0.05-1 part of antioxidant, 0.05-1 part of UV protection agent;

[0008] The thermoplastic polyvinyl alcohol is obtained by an addition reaction between polyvinyl alcohol and (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane.

[0009] The second object of the present invention is to provide a method for preparing a flame-retardant polyvinyl alcohol composite material that can be thermoplastically processed, comprising the following steps:

[0010] (1) mixing thermoplastic polyvinyl alcohol, inorganic filler, plasticizer, flame retardant, antioxidant and UV protection agent to obtain a premix;

[0011] (2) adding the premix into a twin-screw extruder, melt blending, extruding and granulating, and obtaining a polyvinyl alcohol composite material.

[0012] The beneficial effects of the present invention are as follows: the present invention uses (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane to modify polyvinyl alcohol, and imparts certain flame retardant properties to polyvinyl alcohol through chemical modification, thereby improving the flame retardant durability of the polyvinyl alcohol composite material, avoiding the addition of a large amount of flame retardant by physical mixing to affect the physical and mechanical properties of the composite material, and at the same time can also improve the strength of the polyvinyl alcohol composite material. DETAILED DESCRIPTION

[0013] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0014] The present invention provides a flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing, which is made of the following raw materials in parts by weight:

[0015] 100 parts of thermoplastic polyvinyl alcohol, 10-30 parts of inorganic filler, 5-20 parts of plasticizer, 5-20 parts of flame retardant, 0.05-1 part of antioxidant, 0.05-1 part of UV protection agent;

[0016] The thermoplastic polyvinyl alcohol is obtained by an addition reaction between polyvinyl alcohol and (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane.

[0017] Furthermore, the mass ratio of the polyvinyl alcohol to (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane is (1-2):1. The molecular structure of polyvinyl alcohol contains a large number of hydroxyl groups, which makes polyvinyl alcohol have good hydrophilicity and film-forming properties. The present invention utilizes the epoxy group in the molecular structure of (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane to react with the hydroxyl group in the molecular structure of polyvinyl alcohol to convert part of the hydroxyl groups in the molecular structure of polyvinyl alcohol into an organic silicon side chain, which contains hydroxyl groups, ether groups and siloxy groups, which can not only retain the hydrophilicity of polyvinyl alcohol, but also increase the decomposition temperature of polyvinyl alcohol (the decomposition temperature reaches above 300°C), making polyvinyl alcohol suitable for thermoplastic processing. The thermoplastic polyvinyl alcohol prepared by the present invention generates silicon dioxide with a high specific surface area and porosity during combustion, which imparts flame retardancy to polyvinyl alcohol through the mechanism of absorbing heat, absorbing free radicals and increasing the exchange interface, and can also improve the strength of polyvinyl alcohol.

[0018] Furthermore, the degree of polymerization of the polyvinyl alcohol is 1000-3000, and the degree of alcoholysis is 88-99%.

[0019] Furthermore, the addition reaction is carried out under the action of an acidic catalyst or a basic catalyst. Under preferred conditions, the acidic catalyst includes protonic acids (such as sulfuric acid, phosphoric acid, hydrofluoric acid, etc.) and Lewis acids (such as zinc chloride, aluminum chloride, boron trifluoride, etc.); the basic catalyst includes inorganic bases (such as sodium hydroxide, potassium hydroxide, etc.) and organic bases (such as sodium alcoholate, potassium alcoholate, tertiary amine, etc.).

[0020] Furthermore, the inorganic filler can be an inorganic filler well known to those skilled in the art, including but not limited to at least one of calcium carbonate, talc, mica powder, silicon dioxide, kaolin, diatomaceous earth, white carbon black, and carbon black. The purpose of adding an inorganic filler to a composite material is to improve the mechanical properties, heat resistance, and flame retardancy of the composite material.

[0021] Furthermore, the plasticizer can be a plasticizer well known to those skilled in the art, including but not limited to at least one of phthalate plasticizers, epoxy plasticizers, citrate plasticizers, aliphatic dibasic acid esters, and phosphate plasticizers. Plasticizer molecules can be inserted into polymer molecular chains to weaken intermolecular forces, increase the distance and activity space between polymer molecular chains, increase the plasticity of polymers, and reduce the processing temperature of polymers.

[0022] Furthermore, the flame retardant can be a flame retardant well known to those skilled in the art, including but not limited to at least one of phosphorus flame retardants, nitrogen flame retardants, silicon flame retardants, and metal hydroxide flame retardants. Flame retardants mainly achieve flame retardant effects by reducing flammability, increasing thermal decomposition temperature, inhibiting flame spread, absorbing heat, and generating non-combustible gas. Since the thermoplastic polyvinyl alcohol of the present invention has certain flame retardancy, the amount of flame retardant can be reduced.

[0023] Furthermore, the antioxidant may be an antioxidant known to those skilled in the art, including but not limited to at least one of phenolic antioxidants and amine antioxidants. The purpose of adding an antioxidant to the composite material is to delay the oxidation process of the composite material, thereby extending the service life of the composite material.

[0024] Furthermore, the UV blocker can be a UV blocker known to those skilled in the art, including but not limited to at least one of benzophenone UV blockers and benzotriazole UV blockers. The purpose of adding a UV blocker to the composite material is to inhibit and delay the light aging of the composite material caused by ultraviolet rays and improve the durability of the composite material.

[0025] The present invention also provides a method for preparing the aforementioned flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing, comprising the following steps:

[0026] (1) mixing thermoplastic polyvinyl alcohol, inorganic filler, plasticizer, flame retardant, antioxidant and UV protection agent to obtain a premix;

[0027] (2) adding the premix into a twin-screw extruder, melt blending, extruding and granulating, and obtaining a polyvinyl alcohol composite material.

[0028] Furthermore, the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 50-300 rpm.

[0029] Example 1

[0030] Preparation of thermoplastic polyvinyl alcohol:

[0031] Add 200g of polyvinyl alcohol (PVA2488), 100g of (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane and 1g of boron trifluoride to tetrahydrofuran, heat to 80°C and react for 8h. After the reaction, distill under reduced pressure to recover tetrahydrofuran, and dry the residue in vacuum to obtain thermoplastic polyvinyl alcohol.

[0032] Preparation of polyvinyl alcohol composite materials:

[0033] (1) 100 parts of thermoplastic polyvinyl alcohol, 20 parts of calcium carbonate, 10 parts of dioctyl phthalate, 5 parts of ammonium polyphosphate, 0.5 parts of tert-butylhydroquinone and 0.4 parts of UV-531 were mixed to obtain a premix.

[0034] (2) adding the premix into a twin-screw extruder, melt-blending, and extruding into granules; the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 100 rpm, to obtain a polyvinyl alcohol composite material.

[0035] Example 2

[0036] Preparation of thermoplastic polyvinyl alcohol:

[0037] Add 150g of polyvinyl alcohol (PVA2499), 100g of (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane and 1g of boron trifluoride to tetrahydrofuran, heat to 80°C and react for 8h. After the reaction, distill under reduced pressure to recover tetrahydrofuran, and dry the residue in vacuum to obtain thermoplastic polyvinyl alcohol.

[0038] Preparation of polyvinyl alcohol composite materials:

[0039] (1) 100 parts of thermoplastic polyvinyl alcohol, 10 parts of mica powder, 20 parts of epoxy soybean oil, 10 parts of melamine, 0.5 parts of tert-butylhydroquinone and 0.3 parts of UV-360 were mixed to obtain a premix.

[0040] (2) adding the premix into a twin-screw extruder, melt-blending, and extruding into granules; the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 150 rpm, to obtain a polyvinyl alcohol composite material.

[0041] Example 3

[0042] Preparation of thermoplastic polyvinyl alcohol:

[0043] Add 100 g of polyvinyl alcohol (PVA2699), 100 g of (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane and 0.5 g of boron trifluoride to tetrahydrofuran, heat to 80°C and react for 8 hours. After the reaction is completed, distill under reduced pressure to recover tetrahydrofuran, and dry the residue in vacuum to obtain thermoplastic polyvinyl alcohol.

[0044] Preparation of polyvinyl alcohol composite materials:

[0045] (1) 100 parts of thermoplastic polyvinyl alcohol, 15 parts of kaolin, 15 parts of tributyl citrate, 5 parts of aluminum hydroxide, 0.4 parts of p-phenylenediamine and 0.25 parts of UV-blocker UV-326 were mixed uniformly to obtain a premix.

[0046] (2) adding the premix into a twin-screw extruder, melt blending, extruding and granulating, the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 300 rpm to obtain a polyvinyl alcohol composite material.

[0047] Example 4

[0048] Preparation of thermoplastic polyvinyl alcohol:

[0049] Add 120g of polyvinyl alcohol (PVA1799), 100g of (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane and 1g of boron trifluoride to tetrahydrofuran, heat to 80°C and react for 8h. After the reaction, distill under reduced pressure to recover tetrahydrofuran, and dry the residue in vacuum to obtain thermoplastic polyvinyl alcohol.

[0050] Preparation of polyvinyl alcohol composite materials:

[0051] (1) 100 parts of thermoplastic polyvinyl alcohol, 25 parts of diatomaceous earth, 5 parts of epoxidized soybean oil, 15 parts of magnesium hydroxide, 0.3 parts of p-phenylenediamine and 0.5 parts of UV-531 are mixed uniformly to obtain a premix.

[0052] (2) adding the premix into a twin-screw extruder, melt-blending, and extruding into granules; the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 50 rpm, to obtain a polyvinyl alcohol composite material.

[0053] Example 5

[0054] Preparation of thermoplastic polyvinyl alcohol:

[0055] Add 180g of polyvinyl alcohol (PVA1788), 100g of (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane and 0.8g of boron trifluoride to tetrahydrofuran, heat to 80°C and react for 8h. After the reaction, distill under reduced pressure to recover tetrahydrofuran, and dry the residue in vacuum to obtain thermoplastic polyvinyl alcohol.

[0056] Preparation of polyvinyl alcohol composite materials:

[0057] (1) 100 parts of thermoplastic polyvinyl alcohol, 30 parts of white carbon black, 10 parts of tributyl citrate, 5 parts of zinc borate, 0.8 parts of tert-butylhydroquinone and 0.2 parts of UV-blocker UV-326 were mixed uniformly to obtain a premix.

[0058] (2) adding the premix into a twin-screw extruder, melt-blending, and extruding into granules; the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 250 rpm, to obtain a polyvinyl alcohol composite material.

[0059] Comparative Example 1

[0060] The method of Example 5 was followed, except that (3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane was replaced with 3-glycidyloxypropyltriethoxysilane.

[0061] Preparation of thermoplastic polyvinyl alcohol:

[0062] 180 g of polyvinyl alcohol (PVA1788), 100 g of 3-glycidyloxypropyltriethoxysilane and 0.8 g of boron trifluoride were added to tetrahydrofuran, and the temperature was raised to 80° C. for reaction for 8 h. After the reaction was completed, the tetrahydrofuran was recovered by reduced pressure distillation, and the residue was vacuum dried to obtain thermoplastic polyvinyl alcohol.

[0063] Preparation of polyvinyl alcohol composite materials:

[0064] (1) 100 parts of thermoplastic polyvinyl alcohol, 30 parts of white carbon black, 10 parts of tributyl citrate, 5 parts of zinc borate, 0.8 parts of tert-butylhydroquinone and 0.2 parts of UV-blocker UV-326 were mixed uniformly to obtain a premix.

[0065] (2) adding the premix into a twin-screw extruder, melt-blending, and extruding into granules; the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 250 rpm, to obtain a polyvinyl alcohol composite material.

[0066] Comparative Example 2

[0067] The method of Example 5 is followed, except that the thermoplastic polyvinyl alcohol is replaced by polyvinyl alcohol that is not chemically modified.

[0068] Preparation of polyvinyl alcohol composite materials:

[0069] (1) 100 parts of polyvinyl alcohol (PVA1788), 30 parts of white carbon black, 10 parts of tributyl citrate, 5 parts of zinc borate, 0.8 parts of tert-butylhydroquinone and 0.2 parts of UV-blocker UV-326 were mixed to obtain a premix.

[0070] (2) adding the premix into a twin-screw extruder, melt-blending, and extruding into granules; the temperature of the twin-screw extruder is 150-200° C., and the screw speed is 250 rpm, to obtain a polyvinyl alcohol composite material.

[0071] The polyvinyl alcohol composite materials prepared in the above examples and comparative examples were respectively added to a film blowing machine, and melted, extruded, blown, pulled, and wound under the conditions of a rotation speed of 300 r / min, a temperature of 140-180° C., and an aspect ratio of 20 to obtain a polyvinyl alcohol film. The prepared polyvinyl alcohol film was subjected to a performance test, and the test results are shown in Table 1.

[0072] The longitudinal tensile strength and elongation at break of the film were tested according to standard GB / T 1040.3-2006; the oxygen index of the film was tested according to standard GB / T 2406.2-2009.

[0073] Table 1 Oxygen index and tensile strength of polyvinyl alcohol composites

[0074] Oxygen index (%) Tensile strength(MPa) Elongation at break (%) Example 1 29.9 26.1 87.4 Example 2 31.2 25.3 84.1 Example 3 29.4 23.6 86.2 Example 4 31.8 24.5 89.5 Example 5 30.6 26.9 90.3 Comparative Example 1 27.2 20.8 78.6 Comparative Example 2 25.3 18.7 72.4

[0075] It can be seen from Table 1 that, compared with the unchemically modified polyvinyl alcohol and the polyvinyl alcohol chemically modified with 3-glycidyloxypropyltriethoxysilane, the thermoplastic polyvinyl alcohol prepared in the present invention can substantially improve the flame retardant properties and tensile properties of the polyvinyl alcohol composite material.

[0076] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing, characterized in that: Made from the following raw materials in parts by weight: 100 parts of thermoplastic polyvinyl alcohol, 10-30 parts of inorganic filler, 5-20 parts of plasticizer, 5-20 parts of flame retardant, 0.05-1 part of antioxidant, 0.05-1 part of UV protection agent; The thermoplastic polyvinyl alcohol is obtained by an addition reaction between polyvinyl alcohol and (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane.

2. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol to (3-glycidyl ether propyl)-1,1,3,3-tetramethyldisiloxane is (1-2):

1.

3. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The polymerization degree of the polyvinyl alcohol is 1000-3000, and the alcoholysis degree is 88-99%.

4. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The addition reaction is carried out under the action of an acidic catalyst or a basic catalyst; Preferably, the acidic catalyst comprises a protonic acid and a Lewis acid; Preferably, the basic catalyst includes inorganic bases and organic bases.

5. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The inorganic filler is at least one of calcium carbonate, talc, mica powder, silicon dioxide, kaolin, diatomaceous earth, white carbon black and carbon black.

6. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The plasticizer is at least one of phthalate plasticizers, epoxy plasticizers, citrate plasticizers, aliphatic dibasic acid esters, and phosphate plasticizers.

7. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The flame retardant is at least one of a phosphorus flame retardant, a nitrogen flame retardant, a silicon flame retardant, and a metal hydroxide flame retardant.

8. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The antioxidant is at least one of a phenolic antioxidant and an amine antioxidant.

9. The flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to claim 1, characterized in that: The UV protection agent is at least one of a benzophenone UV protection agent and a benzotriazole UV protection agent.

10. The method for preparing the flame-retardant polyvinyl alcohol composite material capable of thermoplastic processing according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) mixing thermoplastic polyvinyl alcohol, inorganic filler, plasticizer, flame retardant, antioxidant and UV protection agent to obtain a premix; (2) adding the premix into a twin-screw extruder, melt blending, extruding and granulating, and obtaining a polyvinyl alcohol composite material.