Preparation method of flame-retardant degradable polyester plastic

Abstract

The invention discloses a preparation method of flame-retardant degradable polyester plastic, and relates to the technical field of plastic. Maleic anhydride and allyl glycidyl ether are used for preparing self-crosslinking unsaturated resin, melamine-coated ammonium polyphosphate, microencapsulated red phosphorus, erythritol, mannitol and melamine are used as flame retardants, and polycaprolactone and polyhydroxyalkanoate are used as degradation agents. One or more of stannous octoate, dibutyltin oxide or tetrabutyl titanate is / are used as catalysts, and the materials are prepared through a common reaction. The raw materials are reasonably matched to generate an interactive superimposed effect, so that the prepared polyester plastic has excellent flame retardance, degradability, corrosion resistance and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of plastics, and specifically to a preparation method of a flame-retardant and degradable polyester plastic. Background Art

[0002] Traditional polyester plastics are widely used in many fields due to their good physical and mechanical properties and chemical stability. However, their difficulty in degradation and flammability have become major hidden dangers to the environment and safety. In recent years, although there have been some reports on flame-retardant and degradable polyester materials, these materials often have deficiencies in terms of flame-retardant efficiency, mechanical properties, degradation rate, or production cost.

[0003] Currently, there are mainly three ways to flame-retard polyester plastics: one is reactive flame-retardant polyester, the second is additive flame-retardant polyester, and the third is post-treatment of the finished product. Among them, in reactive flame-retardant polyester, the flame retardant participates in the synthesis reaction of polyester as a component of the resin and becomes a link in the polyester molecular chain. It exhibits high flame retardancy and no precipitation phenomenon, but the process is relatively complex and the production cost is expensive. Post-treatment of the finished product refers to treating the surface of polyester plastic with a flame retardant. The advantage of this method is that it is convenient and fast to operate, and the disadvantage is that after long-term use, the flame retardant attached to the surface will fall off and the flame-retardant performance will seriously decline. Additive flame-retardant polyester plastic is to add a flame retardant during the processing of polyester plastic. The used flame retardant basically does not undergo a chemical change with the polyester resin and is mainly dispersed in the polyester plastic physically to endow the material with flame retardancy. This method is convenient for processing and widely used. Summary of the Invention

[0004] The purpose of the present invention is to provide a flame-retardant and degradable polyester plastic and its preparation method to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solution: A flame-retardant and degradable polyester plastic, the flame-retardant and degradable polyester plastic includes the following components by weight: 80 - 120 parts of maleic anhydride, 40 - 60 parts of vinyl glycidyl ether, 10 - 15 parts of melamine-coated ammonium polyphosphate, 5 - 10 parts of microencapsulated red phosphorus, 3 - 5 parts of erythritol, 3 - 5 parts of mannitol, 1 - 2 parts of aluminum diethylphosphinate, 2 - 4 parts of melamine, 20 - 30 parts of a degradable aid, and 0.5 - 1 part of a catalyst.

[0006] Further, the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%.

[0007] Further, the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 - 10 μm with melamine, and the melamine coating amount is 23%.

[0008] Further, the catalyst is one or a mixture of more of stannous octoate, dibutyltin oxide, or tetrabutyl titanate.

[0009] Further, the degradable auxiliary agent is polycaprolactone and polyhydroxyalkanoate, which are mixed in a mass ratio of 1:2.

[0010] A preparation method of a flame-retardant degradable polyester plastic comprises the following preparation steps: (1) Mix maleic anhydride and allyl glycidyl ether uniformly in a solvent, and react at 120-140 °C for 30 min to obtain a self-crosslinking unsaturated resin; (2) Extrude and pelletize the self-crosslinking unsaturated resin, melamine-coated ammonium polyphosphate, microencapsulated red phosphorus, erythritol, mannitol, aluminum diethylphosphinate, degradable auxiliary agent, and catalyst at 150-200 °C to obtain a polyester plastic.

[0011] Further, the solvent in step (1) is a mixture of toluene and dichloromethane with a mass ratio of 3:1.

[0012] Further, the mass ratio of maleic anhydride to the solvent in step (1) is 2:5.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) In the present invention, maleic anhydride and allyl glycidyl ether undergo a cyclization reaction to generate a self-crosslinking unsaturated resin. The molecular chain forms a cyclic structure. The planarity of the cyclic structure enables better conjugation of the π electron clouds within the molecule. The polyester formed by polymerizing with this monomer has cyclic structures linked to each other in space, forming a three-dimensional spatial network structure. The internal π electron cloud conjugation disperses heat, reduces bond breakage, and improves the thermal stability of the product; in addition, when synthesizing the polyester monomer in the present invention, an aromatic hydrocarbon is introduced, which undergoes an addition reaction with the allyl double bond in allyl glycidyl ether. The aromatic rings can enhance the intermolecular attraction through π-π interaction, forming a superposition effect with the internal cyclic structure of the molecule, improving the stiffness and stability of the polyester plastic. The π electron clouds on the aromatic rings can participate in various chemical reactions, increasing the reaction activity, facilitating the introduction of flame-retardant functional groups such as phosphate functional groups, and facilitating product modification to enhance the flame retardancy; (2) The present invention uses melamine-coated ammonium polyphosphate, microencapsulated red phosphorus, erythritol, mannitol, and melamine as an intumescent flame retardant in a specific compounding ratio to flame-retardantly modify the synthesized self-crosslinking unsaturated resin through the combined effects of gas-phase and condensed-phase flame retardancy; when melamine-coated ammonium polyphosphate and microencapsulated red phosphorus are heated and decomposed into phosphoric acid and polyphosphoric acid substances, these substances will promote the esterification and dehydration of erythritol, mannitol, and the matrix into carbon, which will cover the surface of the polymer, playing the role of heat insulation and mass isolation; on the other hand, gases such as NH3 generated by the decomposition of melamine will promote the formation of an intumescent barrier in the carbon layer, further enhancing the isolation effect of the carbon layer. Diethylaluminum hypophosphite is added as a synergist. On the one hand, when diethylaluminum hypophosphite is heated and decomposed, PO• and PO2• free radicals are generated, which can capture HO• and H• free radicals in the flame region, inhibit the chain reaction of free radicals, and thus delay the combustion; at the same time, the metaphosphoric acid generated by the decomposition will further promote the dehydration of the polymer matrix into carbon, improving the char yield and char quality of the composite material and strengthening the condensed-phase flame retardancy. Detailed implementation mode

[0014] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] In order to more clearly illustrate the method provided by the present invention, the following examples are used for detailed description. The test methods for each index of the flame-retardant and degradable polyester plastic prepared in the following examples are as follows: Flame retardancy: The limiting oxygen index is tested according to the standard GB / T2406.2-2009; Degradability: The plastics obtained in each embodiment and the materials of the comparative examples are made into thin sheets with the same thickness of 50mm*50mm as samples. The samples are placed on the surface of black soil and fixed with nylon window screens above to avoid loss. In the natural environment, they are taken out after 15, 30, and 60 days, washed with anhydrous ethanol, dried, and weighed. Calculate the weight loss rate corresponding to the number of days = 1 - the mass corresponding to the number of days / the initial mass.

[0016] Example 1 (1) 100 parts of maleic anhydride and 50 parts of allyl glycidyl ether are uniformly mixed in 250 parts of a solvent. The solvent is prepared by mixing toluene and dichloromethane in a volume ratio of 3:1. React at 120°C for 30 min to obtain a self-crosslinking unsaturated resin; (2) Mix 100 parts of self-crosslinking unsaturated resin, 10 parts of melamine-coated ammonium polyphosphate, 5 parts of microencapsulated red phosphorus, 3 parts of erythritol, 3 parts of mannitol, 1 part of aluminum diethylphosphinate, 2 parts of melamine, 20 parts of biodegradable additive, and 0.5 part of stannous octoate at 150 - 200 °C, extrude and pelletize to obtain polyester plastic; the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%; the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 μm with melamine, and the melamine coating amount is 23%; the biodegradable additive is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.

[0017] Example 2 (1) Mix 80 parts of maleic anhydride and 40 parts of allyl glycidyl ether evenly in 200 parts of solvent. The solvent is prepared from toluene and dichloromethane in a volume ratio of 3:1, and react at 130 °C for 30 min to obtain self-crosslinking unsaturated resin. (2) Mix 100 parts of self-crosslinking unsaturated resin, 12 parts of melamine-coated ammonium polyphosphate, 7 parts of microencapsulated red phosphorus, 4 parts of erythritol, 4 parts of mannitol, 2 parts of aluminum diethylphosphinate, 3 parts of melamine, 25 parts of biodegradable additive, and 1 part of dibutyltin oxide at 150 - 200 °C, extrude and pelletize to obtain polyester plastic; the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%; the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 μm with melamine, and the melamine coating amount is 23%; the biodegradable additive is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.

[0018] Example 3 (1) Mix 120 parts of maleic anhydride and 60 parts of allyl glycidyl ether evenly in 300 parts of solvent. The solvent is prepared from toluene and dichloromethane in a volume ratio of 3:1, and react at 140 °C for 30 min to obtain self-crosslinking unsaturated resin. (2) Mix 100 parts of self-crosslinking unsaturated resin, 15 parts of melamine-coated ammonium polyphosphate, 10 parts of microencapsulated red phosphorus, 5 parts of erythritol, 5 parts of mannitol, 2 parts of aluminum diethylphosphinate, 4 parts of melamine, 30 parts of biodegradable additive, and 1 part of tetrabutyl titanate at 150 - 200 °C, extrude and pelletize to obtain polyester plastic; the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%; the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 μm with melamine, and the melamine coating amount is 23%; the biodegradable additive is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.

[0019] Comparative Example 1 (1) Mix 100 parts of maleic anhydride and 50 parts of allyl glycidyl ether evenly in 250 parts of solvent. The solvent is prepared from toluene and dichloromethane in a volume ratio of 3:1, and react at 120 °C for 30 min to obtain self-crosslinking unsaturated resin. (2) Extrude and pelletize 100 parts of self-crosslinking unsaturated resin, 10 parts of melamine-coated ammonium polyphosphate, 3 parts of erythritol, 3 parts of mannitol, 1 part of aluminum diethylphosphinate, 2 parts of melamine, 20 parts of degradable additive, and 0.5 part of stannous octoate at 150 - 200 °C to obtain polyester plastic; the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%; the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 μm with melamine, and the melamine coating amount is 23%; the degradable additive is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.

[0020] Comparative Example 2 (1) Mix 100 parts of maleic anhydride and 50 parts of allyl glycidyl ether evenly in 250 parts of solvent. The solvent is prepared by mixing toluene and dichloromethane in a volume ratio of 3:1, and react at 120 °C for 30 min to obtain self-crosslinking unsaturated resin. (2) Extrude and pelletize 100 parts of self-crosslinking unsaturated resin, 5 parts of microencapsulated red phosphorus, 3 parts of erythritol, 3 parts of mannitol, 1 part of aluminum diethylphosphinate, 2 parts of melamine, 20 parts of degradable additive, and 0.5 part of stannous octoate at 150 - 200 °C to obtain polyester plastic; the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%; the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 μm with melamine, and the melamine coating amount is 23%; the degradable additive is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.

[0021] Comparative Example 3 (1) Mix 100 parts of maleic anhydride and 50 parts of allyl glycidyl ether evenly in 250 parts of solvent. The solvent is prepared by mixing toluene and dichloromethane in a volume ratio of 3:1, and react at 120 °C for 30 min to obtain self-crosslinking unsaturated resin. (2) Extrude and pelletize 100 parts of self-crosslinking unsaturated resin, 10 parts of melamine-coated ammonium polyphosphate, 5 parts of microencapsulated red phosphorus, 3 parts of erythritol, 3 parts of mannitol, 20 parts of degradable additive, and 0.5 part of stannous octoate at 150 - 200 °C to obtain polyester plastic; the melamine coating amount in the melamine-coated ammonium polyphosphate is 15%; the microencapsulated red phosphorus is prepared by coating red phosphorus with a particle size of 5 μm with melamine, and the melamine coating amount is 23%; the degradable additive is a mixture of polycaprolactone and polyhydroxyalkanoate in a mass ratio of 1:2.

[0022] Effect Example The performance analysis results of the polyester plastics of Examples 1 to 3 and Comparative Examples 1 to 3 of the present invention are given in Table 1 below.

[0023] Table 1 From the limiting oxygen index of the examples and effect examples of this experiment and the degradation rate measured under simulated natural environment, it can be found that the self-crosslinking unsaturated resin synthesized from maleic anhydride and allyl glycidyl ether in the present invention realizes self-crosslinking as the base material, forms a three-dimensional network structure in the molecule, and has good mechanical properties, thermal stability, and corrosion resistance. In addition, some active groups (such as hydroxyl groups, amino groups, etc.) in the reaction system undergo cyclization reactions with the conjugated double bonds of maleic anhydride, further increasing the crosslinking density and stability of the resin. In addition, the present invention uses melamine-coated ammonium polyphosphate, microencapsulated red phosphorus, erythritol, mannitol, and melamine as the intumescent flame retardant according to a specific compounding ratio, and conducts flame retardant modification on the synthesized self-crosslinking unsaturated resin through the combined effects of gas-phase and condensed-phase flame retardancy. Then, aluminum diethylphosphinate is added as a synergist. On the one hand, aluminum diethylphosphinate decomposes when heated to generate PO• and PO2• free radicals, which can capture HO• and H• free radicals in the flame region and inhibit the chain reaction of free radicals, thereby delaying the combustion process; at the same time, the metaphosphoric acid generated by decomposition will further promote the dehydration and carbonization of the polymer matrix, increasing the char yield and char quality of the composite material and strengthening the condensed-phase flame retardancy.

[0024] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A method for preparing a flame retardant and degradable polyester plastic, characterized in that: The method comprises the following preparation steps: (1) 80 parts of maleic anhydride and 40 parts of allyl glycidyl ether are uniformly mixed in 200 parts of a solvent, wherein the solvent is toluene and dichloromethane in a volume ratio of 3:1, and reacted at 130° C. for 30 minutes to obtain a self-crosslinking unsaturated resin; (2) 100 parts of self-crosslinking unsaturated resin, 12 parts of melamine-coated ammonium polyphosphate, 7 parts of microencapsulated red phosphorus, 4 parts of erythritol, 4 parts of mannitol, 2 parts of diethylaluminum hypophosphite, 3 parts of melamine, 25 parts of degradable additives, and 1 part of dibutyltin oxide are extruded and granulated at 150-200° C. to obtain a polyester plastic; the melamine-coated ammonium polyphosphate has a melamine coating amount of 15%; the microencapsulated red phosphorus is prepared by melamine-coated red phosphorus with a particle size of 5 μm, and the melamine coating amount is 23%; the degradable additives are polycaprolactone and polyhydroxyalkanoate, which are mixed in a mass ratio of 1:2.

Images