A castor oil-based flame retardant plasticizer and its preparation method

Abstract

A castor oil-based flame-retardant plasticizer and a preparation method thereof, castor acryloyl ethyl methacrylate and pentaerythritol tetra-3-mercaptopropionate are uniformly mixed in a solvent, azobisisobutyronitrile is used as a catalyst, after reaction and purification, a castor oil-based intermediate is obtained; the castor oil-based intermediate is uniformly mixed with a flame retardant containing a terminal double bond in a solvent, azobisisobutyronitrile is used as a catalyst, after reaction and purification, a castor oil-based flame-retardant plasticizer is obtained. The present application prepares a castor oil-based plasticizer with excellent flame-retardant performance through click reaction, and the development of a new type of bio-based flame-retardant plasticizer can not only effectively solve the current huge consumption of petroleum-based resources and environmental pollution problems, but also has important significance for sustainable development. The bio-based plasticizer has good flame-retardant performance and has a broad application prospect in many industrial fields.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a castor oil-based plasticizer with excellent flame retardant performance and a preparation method thereof. Background Art

[0002] With the rapid development of the economy and the continuous improvement of environmental protection requirements, replacing petroleum resources with renewable resources has become the main trend of economic development. Vegetable oils have been widely used in coatings, foams, flame retardants, plasticizers, etc. due to their advantages such as renewability, low cost, low environmental pollution and biodegradability. Among them, plasticizers are an important additive added to plastics, resins or elastomers to change their processability, plasticity, flexibility and tensile properties. In recent years, reports on bio-based plasticizer products have emerged one after another. The preparation of bio-based plasticizers with renewable resources as the main raw materials not only reduces the consumption of petrochemical products in the plastics industry, but also reduces the pollution of petrochemical raw materials to the environment during the production process. It has the dual functions of saving petroleum resources and protecting the environment, so it has important application value and broad development space.

[0003] Castor oil is one of the four major inedible oils in the world, primarily produced in China, Brazil, and India. It is a low-cost, widely available renewable vegetable oil widely used in industrial applications. Castor oil is a pale yellow, viscous, non-drying oil primarily composed of fatty acid glycerides. Its molecular structure contains three types of reactive groups: hydroxyl groups, ester groups, and double bonds, allowing it to undergo chemical reactions such as esterification, hydrolysis, double bond addition, and epoxidation. Based on its molecular structure, castor oil-based products with diverse properties can be obtained by modifying its chemical structure using the principles of addition, polycondensation, and esterification.

[0004] Although bio-based plasticizers offer significant advantages in resource conservation and environmental protection, certain specific properties, such as flame retardancy, still require further improvement. This method aims to improve the flame retardancy of bio-based plasticizers by attempting to adjust and design the plasticizer's structure at the molecular level, resulting in the synthesis of a castor oil-based flame-retardant plasticizer. This method significantly improves flame retardancy compared to additive flame retardants. Furthermore, flame retardant molecules are introduced into the castor oil-based plasticizer's structure through a click reaction between thiol groups and double bonds, with minimal impact on the mechanical properties of polyvinyl chloride (PVC) resin. This castor oil-based flame-retardant plasticizer is not only environmentally friendly but also exhibits high thermal stability, excellent flame retardancy, non-toxicity, and anti-drip properties. Furthermore, the introduced sulfur element imparts resistance to thermal and thermo-oxidative degradation, and its positively charged α-C atoms act as electrophilic centers, reacting electrophilically with PVC, effectively inhibiting PVC blackening. In summary, the combined influence of these factors significantly improves the flame retardancy and thermal stability of castor oil-based plasticizers. This method is not only conducive to the industrial promotion of castor oil and its development towards multiple varieties and high performance, but also conducive to expanding the application range of castor oil-based products. Summary of the Invention

[0005] Technical problem to be solved: The present invention provides a castor oil-based flame retardant plasticizer and a preparation method thereof. As a new type of biomass plasticizer, this material improves its flame retardant properties and thermal stability on the basis of saving resources and protecting the environment. It is of great significance to the high-value utilization of castor oil products, the development of bio-based additives and other industries.

[0006] Technical solution: A method for preparing a castor oil-based flame retardant plasticizer, comprising the following steps: (1) mixing ricinoleyl ethyl methacrylate and pentaerythritol tetra-3-mercaptopropionate in a solvent, the reaction temperature being 25-60°C under nitrogen protection, wherein the molar ratio of ricinoleyl ethyl methacrylate to pentaerythritol tetra-3-mercaptopropionate is 1:(1-3), azobisisobutyronitrile is used as a catalyst, the catalyst content is 0.1%-2% of the mass of ricinoleyl ethyl methacrylate, and the reaction time is 0.5-24 h; after the reaction is completed and purified, a castor oil-based intermediate is obtained; (2) the castor oil-based intermediate and the flame retardant containing a terminal double bond are mixed in a solvent, the reaction temperature is 25-60° C., nitrogen protection is used, wherein the molar ratio of the castor oil-based intermediate to the flame retardant containing a terminal double bond is 1:(1-5), azobisisobutyronitrile is used as a catalyst, the catalyst content is 0.1%-2% of the mass of ricinoleyl ethyl methacrylate, and the reaction time is 0.5-24h; after the reaction is completed and purified, a castor oil-based flame retardant plasticizer is obtained.

[0007] The solvent in step (1) and step (2) is any one of tetrahydrofuran, dichloromethane, chloroform and acetone.

[0008] The reaction time of the castor oil-based intermediate in step (1) is 12 h, and the reaction temperature is 45° C.

[0009] The amount of azobisisobutyronitrile used in step (1) is 1.5 wt.% of the total mass of the reaction system.

[0010] The flame retardant containing a terminal double bond in step (2) is any one of dibromostyrene, pentabromobenzyl acrylate, di(β-chloroethyl) vinylphosphonate, 2-hydroxyethyl methacrylate, and diphenyl phosphate.

[0011] The molar ratio of the castor oil-based intermediate and the flame retardant containing a terminal double bond in step (2) is 1:3.

[0012] The amount of azobisisobutyronitrile used in step (2) is 2 wt.% of the total mass of the reaction system.

[0013] The reaction time of step (2) is 30 min-12 h.

[0014] The castor oil-based flame retardant plasticizer is prepared by the preparation method.

[0015] Beneficial Effects: This invention utilizes a castor oil-based plasticizer prepared from ricinoleylethyl methacrylate and pentaerythritol tetrakis(3-mercaptopropionate) and a flame retardant containing terminal double bonds as raw materials to produce a castor oil-based plasticizer with excellent flame retardancy through a click reaction. The development of novel bio-based flame-retardant plasticizers not only effectively addresses the current challenges of massive petroleum resource consumption and environmental pollution, but also holds significant significance for sustainable development. This bio-based plasticizer exhibits excellent flame retardancy and has broad application prospects in numerous industrial fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Thermogravimetric analysis curve of plasticized PVC products;

[0017] Figure 2 Mechanical properties of plasticized PVC materials;

[0018] Table 1 Plasticized PVC product formula;

[0019] Table 2 Oxygen index of plasticized PVC products. DETAILED DESCRIPTION

[0020] Example 1

[0021] Castor oil based intermediate (1) was prepared by mixing castor acrylate and pentaerythritol tetra-3-mercaptopropionate in tetrahydrofuran at 50 °C under nitrogen protection, where the molar ratio of castor acrylate and pentaerythritol tetra-3-mercaptopropionate was 1:2, azobisisobutyronitrile was used as catalyst, the catalyst content was 1% of the mass of castor acrylate, the reaction time was 12 h; after the reaction was completed and purified, castor oil based intermediate (1) was obtained. Castor oil based intermediate (1) and dibromostyrene were added to the reaction flask, the molar ratio of the reactants was: castor oil based intermediate (1): flame retardant molecule (dibromostyrene) = 1:1. The total amount of catalyst azobisisobutyronitrile added was 2 wt.% of the mass of castor acrylate, and the reaction was stirred at 60 °C under nitrogen protection for 12 h. After the reaction was completed and purified, the castor oil based flame retardant plasticizer was obtained. The obtained castor oil based flame retardant plasticizer was blended with PVC and the like to prepare a PVC material, and the mechanical properties and flame retardant properties of the PVC material were tested. When 20% of the castor oil based plasticizer was added, the limiting oxygen index was 28.5±1.0%, the tensile strength was 26±0.5 MPa, and the elongation at break was 218±5%.

[0022] Example 2

[0023] Castor oil based intermediate (1) was prepared by mixing castor acrylate and pentaerythritol tetra-3-mercaptopropionate in tetrahydrofuran at 50 °C under nitrogen protection, where the molar ratio of castor acrylate and pentaerythritol tetra-3-mercaptopropionate was 1:2, azobisisobutyronitrile was used as catalyst, the catalyst content was 1% of the mass of castor acrylate, the reaction time was 12 h; after the reaction was completed and purified, castor oil based intermediate (1) was obtained. Castor oil based intermediate (1) and dibromostyrene were added to the reaction flask, the molar ratio of the reactants was: castor oil based intermediate (1): flame retardant molecule (dibromostyrene) = 1:1. The total amount of catalyst azobisisobutyronitrile added was 2 wt.% of the mass of castor acrylate, and the reaction was stirred at 60 °C under nitrogen protection for 12 h. After the reaction was completed and purified, the castor oil based flame retardant plasticizer was obtained. The obtained castor oil based flame retardant plasticizer was blended with PVC and the like to prepare a PVC material, and the mechanical properties and flame retardant properties of the PVC material were tested. When 20% of the castor oil based plasticizer was added, the limiting oxygen index was 28.5±1.0%, the tensile strength was 26±0.5 MPa, and the elongation at break was 218±5%.

[0024] Example 3

[0025] The methacrylic acid ricinoleyl ester and pentaerythritol tetra-3-mercaptopropionate were mixed in dichloromethane, the reaction temperature was 50 ° C, nitrogen protection, wherein the molar ratio of methacrylic acid ricinoleyl ester to pentaerythritol tetra-3-mercaptopropionate was 1:2, azobisisobutyronitrile was used as a catalyst, the catalyst content was 1% of the mass of methacrylic acid ricinoleyl ester, and the reaction time was 12 hours; after the reaction was completed and purified, a castor oil-based intermediate (1) was obtained. The castor oil-based intermediate (1) and dibromostyrene were added to the reaction flask, and the reactant molar ratio was: castor oil-based intermediate (1): flame retardant molecule (dibromostyrene) = 1:3. The catalyst azobisisobutyronitrile was added, the total amount was 1wt.% of the mass of methacrylic acid ricinoleyl ester, nitrogen protection, heated to 45 ° C and stirred for 15 hours, and after the reaction was completed and purified, a castor oil-based flame retardant plasticizer was obtained. The castor oil-based flame retardant plasticizer obtained was blended with PVC and the like to prepare PVC materials, and its performance was tested. When 60% of the castor oil-based plasticizer is added, the limiting oxygen index is 36.7±1.1%, the tensile strength is 10.6±0.2 MPa, and the elongation at break is 424±11%.

[0026] Example 4

[0027] The method comprises the following steps: mixing ricinoleyl ethyl methacrylate and pentaerythritol tetra-3-mercaptopropionate in dichloromethane, reacting at a temperature of 40°C under nitrogen protection, wherein the molar ratio of ricinoleyl ethyl methacrylate to pentaerythritol tetra-3-mercaptopropionate is 1:3, using azobisisobutyronitrile as a catalyst, the catalyst content of which is 1.5% of the mass of ricinoleyl ethyl methacrylate, and the reaction time is 20 hours; after the reaction is completed and purified, a castor oil-based intermediate (2) is obtained. The castor oil-based intermediate (2) and vinylphosphonic acid di(β-chloroethyl) ester are added to a reaction flask, the reactant molar ratio being: castor oil-based intermediate (2): flame retardant molecule (vinylphosphonic acid di(β-chloroethyl) ester) = 1:1. The catalyst azobisisobutyronitrile is added, the total amount of which is 2wt.% of the mass of ricinoleyl ethyl methacrylate, under nitrogen protection, heating to 60°C and stirring for 12 hours, and after the reaction is completed and purified, a castor oil-based flame retardant plasticizer is obtained. The castor oil-based flame retardant plasticizer was mixed with PVC to prepare a PVC material, and its performance was tested. When 20% of the castor oil-based plasticizer was added, its initial thermal decomposition temperature was 163.2°C and the residual carbon rate was 11.7%.

[0028] Example 5

[0029] The method comprises mixing ricinoleyl ethyl methacrylate and pentaerythritol tetra-3-mercaptopropionate in dichloromethane, and the reaction temperature is 40°C, and nitrogen is used as a protection. The molar ratio of ricinoleyl ethyl methacrylate to pentaerythritol tetra-3-mercaptopropionate is 1:3. Azobisisobutyronitrile is used as a catalyst, and the catalyst content is 1.5% of the mass of ricinoleyl ethyl methacrylate. The reaction time is 20 hours. After the reaction is completed and purified, a castor oil-based intermediate (2) is obtained. The castor oil-based intermediate (2) and 2-hydroxyethyl methacrylate diphenyl phosphate are added to a reaction flask, and the reactant molar ratio is: castor oil-based intermediate (2): flame retardant molecule (2-hydroxyethyl methacrylate diphenyl phosphate) = 1:2. The catalyst azobisisobutyronitrile is added, and the total amount is 2wt.% of the mass of ricinoleyl ethyl methacrylate. The method comprises heating to 60°C and stirring for 10 hours. After the reaction is completed and purified, a castor oil-based flame retardant plasticizer is obtained. The castor oil-based flame retardant plasticizer was mixed with PVC to prepare a PVC material, and its performance was tested. When 40% of the castor oil-based plasticizer was added, its initial thermal decomposition temperature was 228°C and the residual carbon rate was 8.9%.

[0030] Example 6

[0031] The methacrylic acid ricinoleyl ester and pentaerythritol tetra-3-mercaptopropionate were mixed in tetrahydrofuran, the reaction temperature was 55 ° C, nitrogen protection, wherein the molar ratio of methacrylic acid ricinoleyl ester to pentaerythritol tetra-3-mercaptopropionate was 1:2, azobisisobutyronitrile was used as a catalyst, the catalyst content was 0.5% of the mass of methacrylic acid ricinoleyl ester, and the reaction time was 10 hours; after the reaction was completed and purified, a castor oil-based intermediate (3) was obtained. The castor oil-based intermediate (3) and dibromostyrene were added to a beaker, and the reactant molar ratio was: castor oil-based intermediate (3): flame retardant molecule (dibromostyrene) = 1:1. The catalyst azobisisobutyronitrile was added, the total amount was 1wt.% of the mass of methacrylic acid ricinoleyl ester, nitrogen protection, heated to 50 ° C and stirred for 16 hours, and after the reaction was completed and purified, a castor oil-based flame retardant plasticizer was obtained. The castor oil-based flame retardant plasticizer obtained was blended with PVC and the like to prepare PVC materials, and its performance was tested. When 60% of the castor oil-based plasticizer was added, the initial thermal decomposition temperature was 226° C. and the residual carbon rate was 12.2%.

[0032] Table 1 Plasticized PVC product formula

[0033]

[0034] Table 2 Oxygen index of plasticized PVC products

[0035]

[0036] The present invention is not limited to the above embodiments, and all of the contents of the present invention can be implemented and have the above good effects.

Claims

1. A method for preparing a castor oil-based flame retardant plasticizer, characterized in that: Ricinoleyl ethyl methacrylate and pentaerythritol tetra-3-mercaptopropionate are mixed in tetrahydrofuran, the reaction temperature is 55°C, nitrogen protection is used, the molar ratio of ricinoleyl ethyl methacrylate to pentaerythritol tetra-3-mercaptopropionate is 1:2, azobisisobutyronitrile is used as a catalyst, the catalyst content is 0.5% of the mass of ricinoleyl ethyl methacrylate, and the reaction time is 10 h; after the reaction is completed and purified, a castor oil-based intermediate (3) is obtained; the castor oil-based intermediate (3) and dibromostyrene are added to a beaker, the reactant molar ratio is: castor oil-based intermediate (3): dibromostyrene = 1:1, azobisisobutyronitrile is added as a catalyst, the total amount is 1 wt.% of the mass of ricinoleyl ethyl methacrylate, nitrogen protection is used, the reaction is heated to 50°C and stirred for 16 h, and after the reaction is completed and purified, a castor oil-based flame retardant plasticizer is obtained.

2. The castor oil-based flame retardant plasticizer prepared by the preparation method of claim 1.

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