Flame-retardant modified PTT material and preparation method thereof

Abstract

The application discloses a kind of preparation methods of flame-retardant modified PTT materials, which includes the following steps: S1: 1,3-propanediol is reacted with dimethyl terephthalate by ester exchange reaction;S2: continue to react by adding the mixed solution of dihydroxy phenyl phosphine and 1,3-propanediol;Then drop the organic solution of tri (formic acid methyl ester phenyl) -1,3,5-triazine, and obtain the prepolymer after crosslinking reaction;S3: continue to react to a certain intrinsic viscosity, obtain the initial product;S4: it is mixed uniformly with PTT masterbatch and auxiliary agent, after melt extrusion, granulation, finally obtain the flame-retardant modified PTT material finished product.The preparation method of the application not only significantly improves the flame-retardant performance of PTT material, so that it can meet the strict fireproof standard, but also maintains the original excellent mechanical properties and processing performance of PTT material.In addition, the method also optimizes the thermal stability of the material, further improves the comprehensive performance and application range of the material.

Description

Technical Field

[0001] This invention relates to the technical field of PTT materials, and in particular to a flame-retardant modified PTT material and its preparation method. Background Technology

[0002] Polypropylene terephthalate (PTT) is a high-performance synthetic fiber and engineering plastic material widely used in textiles, automobiles, electronics, and other fields due to its unique physical and processing properties. However, PTT's poor flame retardancy limits its use in applications with high fire protection requirements. Traditional flame retardant modification methods mainly improve the material's fire resistance by adding flame retardants, but these methods often have some drawbacks. For example, adding large amounts of flame retardants may lead to a decrease in the material's mechanical properties, worsen its processing performance, and increase its cost. Furthermore, some flame retardants may release toxic fumes under high-temperature conditions, posing potential hazards to the environment and human health. Therefore, developing a flame retardant modification method that can effectively improve the flame retardancy of PTT while maintaining its excellent mechanical and processing properties is an important current research direction. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a method for preparing flame-retardant modified PTT materials to solve the technical problems of poor flame retardant performance, easy combustion at high temperatures, and the generation of large amounts of smoke and toxic gases during combustion of traditional PTT materials. Furthermore, the present invention also aims to overcome the technical problems of decreased material mechanical properties, deteriorated thermal stability, and reduced processing performance existing in existing flame-retardant modification methods.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a flame-retardant modified PTT material, the method comprising the following steps: S1: 1,3-Propanediol and dimethyl terephthalate are added to a polymerization reactor, along with an appropriate amount of transesterification catalyst. The transesterification reaction is carried out at a temperature of 200–255℃ and a pressure of 0.1–0.4 MPa. S2: After the transesterification reaction in step S1 has been carried out for a certain period of time, a mixture of dihydroxyphenylphosphazene and 1,3-propanediol, as well as an appropriate amount of polycondensation catalyst, is added. After the reaction continues for 15 to 60 minutes, an organic solution containing tris(methyl methacrylate phenyl)-1,3,5-triazine is added dropwise. After the crosslinking reaction, a prepolymer of flame-retardant modified PTT material is obtained. S3: The prepolymer is further reacted at a temperature of 265-270℃ and a pressure of less than 80Pa. When the intrinsic viscosity of the product reaches 0.6-0.9dL / g, it is cast into strips and cut into pellets to obtain the initial product of flame-retardant modified PTT material. S4: The primary product is mixed evenly with unmodified PTT masterbatch and additives, and then melt-extruded and granulated at a temperature of 250-280℃ and a screw speed of 300-500r / min to finally obtain the flame-retardant modified PTT material product.

[0005] As a preferred technical solution, in step S1, the molar ratio of 1,3-propanediol to dimethyl terephthalate is 1:1.5 to 2.5.

[0006] As a preferred technical solution, in step S1, the transesterification catalyst is at least one of antimony trioxide, antimony glycolate, antimony acetate, stannous octoate, and dibutyltin dilaurate.

[0007] As a preferred technical solution, in step S2, the chemical structural formula of the dihydroxyphenylphosphaphenanthrene is shown in Formula I. Structural formula I; wherein R1 to R6 are independently selected from hydrogen, methyl or methoxy.

[0008] As a preferred technical solution, in step S2, the chemical structural formula of the tris(methyl formate phenyl)-1,3,5-triazine is shown in Formula II. Structural formula II; where R is or .

[0009] As a preferred technical solution, the tris(methylformate phenyl)-1,3,5-triazine is obtained by reacting tris(carboxyphenyl)-1,3,5-triazine with methanol.

[0010] As a preferred technical solution, the tris(carboxyphenyl)-1,3,5-triazine is 2,4,6-tris((p-carboxyphenyl)amino)-1,3,5-triazine and / or 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine.

[0011] As a preferred technical solution, the additive is at least one of lubricant, toughening agent, ultraviolet absorber, and pigment.

[0012] As a preferred technical solution, the mass ratio of the primary product to the unmodified PTT masterbatch and additives is 30-50:50-70:1-5.

[0013] Another aspect of the present invention is to provide a flame-retardant modified PTT material, wherein the PTT material is prepared by the method described above for preparing flame-retardant modified PTT materials.

[0014] The beneficial effects of this invention are: This invention discloses a method for preparing flame-retardant modified PTT materials. By innovatively introducing dihydroxyphenylphosphine and tris(methylformate phenyl)-1,3,5-triazine branched crosslinking agents into the PTT material synthesis process, it not only significantly improves the flame-retardant properties of the material but also further optimizes its thermal stability and processing performance while maintaining the original excellent mechanical properties of the PTT material. This design not only enhances the material's stability under high-temperature environments but also preserves the good flexibility and impact resistance of the PTT material, helping to broaden its application range in fields such as electronics, automotive interiors, and building materials.

[0015] In summary, the flame-retardant modified PTT material of the present invention not only possesses excellent flame retardancy, mechanical strength, and heat resistance, but also exhibits good processing performance, meeting the stringent requirements for long-term durability and stability in various application scenarios. Detailed Implementation

[0016] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0017] Example 1 The preparation method of the flame-retardant modified PTT material in this embodiment includes the following steps: S1: 1,3-propanediol (76g) and dimethyl terephthalate (388g) were added to the polymerization reactor, and 1.2g of transesterification catalyst (antimony acetate) was added at the same time. The transesterification reaction was carried out at a temperature of 230℃ and a pressure of 0.4MPa. S2: After the transesterification reaction in step S1 proceeded for 2 hours, a mixture of 32 g of 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB, CAS number 99208-50-1) and 38 g of 1,3-propanediol, as well as 0.5 g of polycondensation catalyst (tetrabutyl titanate), was added. After the reaction continued for 45 minutes, a 25% (w / w) toluene solution (100 mL) of tris(methyl phenyl)-1,3,5-triazine was added dropwise. After the crosslinking reaction was separated, the prepolymer of the flame-retardant modified PTT material was obtained. S3: The prepolymer is reacted at 265℃ and 50Pa for 3 hours. When the intrinsic viscosity of the product reaches 0.75dL / g, it is cast into strips and cut into pellets to obtain the initial product of flame-retardant modified PTT material. S4: The primary product with a mass ratio of 40:60:3 is mixed evenly with unmodified PTT masterbatch and additives, and then melt-extruded and granulated at a temperature of 270℃ and a screw speed of 400r / min to finally obtain the flame-retardant modified PTT material product.

[0018] In step S2, the chemical structural formula of the tris(methyl formate phenyl)-1,3,5-triazine is shown in Formula II. Structural Formula II.

[0019] The tris(methylformate phenyl)-1,3,5-triazine was obtained by reacting 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine with methanol. The specific reaction steps were as follows: 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (25 g) was dissolved in methanol (200 mL), heated to 80 °C, refluxed for 2 hours, cooled to room temperature, and filtered to obtain the product.

[0020] The additive is composed of the following raw materials in parts by weight: 2 parts lubricant (calcium stearate), 1 part toughening agent (polyolefin elastomer, such as POE), 0.5 parts ultraviolet absorber (benzotriazole, such as UV-327) and 0.1 parts pigment (titanium dioxide).

[0021] Example 2 The preparation method of the flame-retardant modified PTT material in this embodiment includes the following steps: [S1: 1,3-propanediol (76g) and dimethyl terephthalate (430g) were added to the polymerization reactor, and 1.2g of transesterification catalyst (antimony trioxide) was added at the same time. The transesterification reaction was carried out at a temperature of 250℃ and a pressure of 0.2MPa. S2: After the transesterification reaction in step S1 proceeded for 2 hours, a mixture of 48 g of 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB, CAS number 99208-50-1) and 57 g of 1,3-propanediol, as well as 0.5 g of polycondensation catalyst (tetrabutyl titanate), was added. After the reaction continued for 60 minutes, a 25% (w / w) toluene solution (100 mL) of tris(methyl phenyl)-1,3,5-triazine was added dropwise. After the crosslinking reaction was separated, the prepolymer of the flame-retardant modified PTT material was obtained. S3: The prepolymer is reacted at 270℃ and 60Pa for 4 hours. When the intrinsic viscosity of the product reaches 0.8dL / g, it is cast into strips and cut into pellets to obtain the initial product of flame-retardant modified PTT material. S4: The initial product with a mass ratio of 30:70:5 is mixed evenly with unmodified PTT masterbatch and additives. The mixture is then melt-extruded and granulated at 270°C and a screw speed of 400 r / min to obtain the final flame-retardant modified PTT material. The additives are the same as in Example 1.

[0022] In step S2, the chemical structural formula of the tris(methyl formate phenyl)-1,3,5-triazine is shown in Formula II. Structural Formula II.

[0023] The tris(methyl formate phenyl)-1,3,5-triazine was obtained by reacting 2,4,6-tris((p-carboxyphenyl)amino)-1,3,5-triazine with methanol. The specific reaction steps were as follows: 25 g of 2,4,6-tris((p-carboxyphenyl)amino)-1,3,5-triazine was dissolved in 200 mL of methanol, heated to 80 °C, refluxed for 2 hours, cooled to room temperature, and filtered to obtain the product.

[0024] Example 3 The preparation method of flame-retardant modified PTT material in this embodiment is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of this embodiment, the mass ratio of the primary product to the unmodified PTT masterbatch and additives is 50:50:1.

[0025] Comparative Example 1 The preparation method of this comparative flame-retardant modified PTT material is basically the same as that of Example 1 in terms of raw material composition and preparation steps. The difference is that ODOPB is not added in step S2 of this comparative preparation method.

[0026] Comparative Example 2 The preparation method of this comparative flame-retardant modified PTT material is basically the same as that of Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of this comparative example, tris(methylformate phenyl)-1,3,5-triazine is not added in step S2.

[0027] The flame-retardant modified PTT materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the performance results are shown in Table 1: The flame retardancy performance test (LOI) was conducted according to ISO 4589-2 standard. First, a sample with dimensions of 100mm × 10mm × 3mm was prepared. The sample was placed in a mixed gas environment of oxygen and nitrogen, and the oxygen concentration was gradually adjusted until the sample could continue to burn after the flame was removed. The volume percentage of oxygen at this point was recorded as the LOI value.

[0028] Flame retardancy testing (UL-94) is conducted according to the UL-94 standard, using a sample measuring 125mm × 13mm × 3mm. The sample is vertically fixed to the test stand, a flame is applied for 10 seconds, and then the flame is removed. The burning behavior of the sample is observed and recorded to determine its flame retardancy rating.

[0029] Tensile strength and elongation at break tests were conducted according to ISO 527 standard. The specimens were dumbbell-shaped, measuring 150 mm × 10 mm × 4 mm. The specimens were mounted on a tensile testing machine, and the tensile speed was set to 50 mm / min. The specimens were stretched until fracture, and the maximum tensile stress was recorded as the tensile strength. The elongation at fracture was recorded as the elongation at break.

[0030] The heat distortion temperature (HDT) test was conducted according to ISO 75 standard, with a specimen size of 80 mm × 10 mm × 4 mm. The specimen was placed on the test platform, a specified load (0.45 MPa) was applied, and the temperature was increased at a rate of 120 °C / h. The temperature at which the specimen under the load underwent the specified deformation was recorded.

[0031] Table 1

[0032] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a flame-retardant modified PTT material, characterized in that, The preparation method includes the following steps: S1: 1,3-Propanediol and dimethyl terephthalate are added to a polymerization reactor, along with an appropriate amount of transesterification catalyst. The transesterification reaction is carried out at a temperature of 200–255℃ and a pressure of 0.1–0.4 MPa. S2: After the transesterification reaction in step S1 has been carried out for a certain period of time, a mixture of dihydroxyphenylphosphazene and 1,3-propanediol, as well as an appropriate amount of polycondensation catalyst, is added. After the reaction continues for 15 to 60 minutes, an organic solution containing tris(methyl methacrylate phenyl)-1,3,5-triazine is added dropwise. After the crosslinking reaction, a prepolymer of flame-retardant modified PTT material is obtained. S3: The prepolymer is further reacted at a temperature of 265-270℃ and a pressure of less than 80Pa. When the intrinsic viscosity of the product reaches 0.6-0.9dL / g, it is cast into strips and cut into pellets to obtain the initial product of flame-retardant modified PTT material. S4: Mix the primary product with unmodified PTT masterbatch and additives evenly, and then melt-extrude and granulate it under the conditions of 250-280℃ and screw speed of 300-500r / min to finally obtain the flame-retardant modified PTT material product. In step S2, the chemical structural formula of the dihydroxyphenylphosphaphenanthrene is shown in Formula I. Structural formula I; wherein R1 to R6 are independently selected from hydrogen, methyl or methoxy; In step S3, the chemical structural formula of the tris(methyl formate phenyl)-1,3,5-triazine is shown in formula II-1 or II-2. Structural formula II-1; or Structural formula II-2.

2. The preparation method of the flame-retardant modified PTT material as described in claim 1, characterized in that, In step S1, the molar ratio of 1,3-propanediol to dimethyl terephthalate is 1:1.5 to 2.

5.

3. The preparation method of the flame-retardant modified PTT material as described in claim 1, characterized in that, In step S1, the transesterification catalyst is at least one of antimony trioxide, antimony glycolate, antimony acetate, stannous octoate, and dibutyltin dilaurate.

4. The preparation method of the flame-retardant modified PTT material as described in claim 1, characterized in that, The tris(methylformate phenyl)-1,3,5-triazine is obtained by reacting 2,4,6-tris((p-carboxyphenyl)amino)-1,3,5-triazine with methanol, or by reacting 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine with methanol.

5. The preparation method of the flame-retardant modified PTT material as described in claim 1, characterized in that, The additive is at least one of lubricant, toughening agent, ultraviolet absorber, and pigment.

6. The preparation method of the flame-retardant modified PTT material as described in claim 1, characterized in that, The mass ratio of the primary product to unmodified PTT masterbatch and additives is 30-50:50-70:1-5.

7. A flame-retardant modified PTT material, characterized in that, The PTT material is prepared using the method for preparing flame-retardant modified PTT material as described in any one of claims 1 to 6.

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