Flame-retardant modified PTT material and preparation method thereof

Abstract

The invention discloses a preparation method of a flame-retardant modified PTT material, and the method comprises the following steps: S1, carrying out transesterification on 1, 3-propylene glycol and dimethyl terephthalate; s2, adding a mixed solution of dihydroxy phenyl phosphaphenanthrene and 1, 3-propylene glycol, and continuously reacting; then dropwise adding an organic solution of tri (methyl formate phenyl)-1, 3, 5-triazine, and carrying out a cross-linking reaction to obtain a prepolymer; s3, continuously reacting to a certain intrinsic viscosity to obtain a primary product; and S4, uniformly mixing the flame-retardant modified PTT material with PTT master batches and an auxiliary agent, performing melt extrusion, and performing granulation to finally obtain a flame-retardant modified PTT material finished product. According to the preparation method disclosed by the invention, the flame retardant property of the PTT material is remarkably improved, so that the PTT material can meet strict fireproof standards, and the original excellent mechanical properties and processability of the PTT material are maintained. In addition, the method also optimizes the thermal stability of the material, and further improves the comprehensive performance and application range of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of PTT materials, and in particular to a flame retardant modified PTT material and a preparation method thereof. Background Art

[0002] Polytrimethylene terephthalate (PTT) is a high-performance synthetic fiber and engineering plastic material. Due to its unique physical properties and processing capabilities, it has been widely used in a variety of fields, including textiles, automotive, and electronics. However, PTT materials have poor flame retardancy, which limits their use in some applications with high fire protection requirements. Traditional flame-retardant modification methods mainly improve the fire resistance of materials by adding flame retardants, but these methods often have some shortcomings. For example, the addition of large amounts of flame retardants may lead to a decrease in the mechanical properties of the material, poor processing performance, and increased material cost. In addition, 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 materials while maintaining their excellent mechanical properties and processing performance is an important research direction. Summary of the Invention

[0003] In light of the above shortcomings of the existing technologies, the present invention provides a method for preparing a flame-retardant modified PTT material to address the technical issues of conventional PTT materials, such as their poor flame retardancy, flammability at high temperatures, and the generation of large amounts of smoke and toxic gases during combustion. Furthermore, the present invention aims to overcome technical issues associated with existing flame-retardant modification methods, such as decreased mechanical properties, thermal stability, and poor processing performance.

[0004] In order to achieve the above objects, the technical solution adopted by the present invention is: A method for preparing a flame retardant modified PTT material, the method comprising the following steps: S1: Add 1,3-propylene glycol and dimethyl terephthalate into a polymerization kettle, add an appropriate amount of transesterification catalyst, and carry out transesterification reaction at a temperature of 200-255°C and a pressure of 0.1-0.4 MPa; S2: After the transesterification reaction in step S1 has proceeded for a certain period of time, a mixture of dihydroxyphenylphosphaphenanthrene and 1,3-propylene glycol and an appropriate amount of a polycondensation catalyst are added, and the reaction is continued for 15 to 60 minutes. Then, an organic solution containing tris(methylformatephenyl)-1,3,5-triazine is added dropwise, and a prepolymer of a flame-retardant modified PTT material is obtained after a cross-linking reaction; S3: The prepolymer is further reacted at a temperature of 265-270° C. and a pressure of less than 80 Pa. When the intrinsic viscosity of the product reaches 0.6-0.9 dL / g, the prepolymer is cast into a strip and pelletized to obtain a primary product of a flame-retardant modified PTT material; S4: The primary product is mixed evenly with the unmodified PTT masterbatch and the additives, and melt-extruded and granulated at a temperature of 250-280° C. and a screw speed of 300-500 r / min to finally obtain the finished flame-retardant modified PTT material.

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

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

[0007] As a preferred technical solution, in step S2, the chemical structural formula of the dihydroxyphenylphosphaphenanthrene is as 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 structure of tris(methyl formate phenyl)-1,3,5-triazine is as shown in Formula II, Structural formula II; wherein R is or .

[0009] As a preferred technical solution, the tris(methyl formate phenyl)-1,3,5-triazine is obtained by reacting tris(carboxyphenyl)-1,3,5-triazine and 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 auxiliary agent is at least one of a lubricant, a toughening agent, a UV absorber, and a pigment.

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

[0013] Another aspect of the present invention is to provide a flame retardant modified PTT material, which is prepared using the above-mentioned method for preparing the flame retardant modified PTT material.

[0014] Beneficial effects of the present invention: The present method for preparing a flame-retardant modified PTT material innovatively introduces dihydroxyphenylphosphaphenanthrene and tris(methylformatephenyl)-1,3,5-triazine branched crosslinkers during the PTT synthesis process. This significantly enhances the material's flame retardancy while also maintaining the material's inherent excellent mechanical properties while further optimizing its thermal stability and processing performance. This design enhances the material's stability in high-temperature environments while maintaining its excellent flexibility and impact resistance, potentially expanding its application in electronics, automotive interiors, building materials, and other fields.

[0015] In general, the flame-retardant modified PTT material of the present invention not only has excellent flame retardancy, mechanical strength and heat resistance, but also has good processing performance, and can meet the strict requirements of various application scenarios for the long-term durability and stability of the material. DETAILED DESCRIPTION

[0016] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0017] Example 1 The method for preparing the flame retardant modified PTT material of this embodiment comprises the following steps: S1: 1,3-Propanediol (76 g) and dimethyl terephthalate (388 g) were added to a polymerization kettle, and 1.2 g of transesterification catalyst (antimony acetate) was added at the same time. The transesterification reaction was carried out at a temperature of 230°C and a pressure of 0.4 MPa. S2: After the transesterification reaction in step S1 was carried out for 2 hours, a mixture of 32 g of 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (abbreviated as ODOPB, CAS number 99208-50-1) and 38 g of 1,3-propylene glycol, and 0.5 g of a polycondensation catalyst (tetrabutyl titanate) was added. After continuing the reaction for 45 minutes, a toluene solution (100 mL) of tris(methylformatephenyl)-1,3,5-triazine with a mass concentration of 25% was added dropwise. After cross-linking reaction and separation, a prepolymer of a flame-retardant modified PTT material was obtained; S3: The prepolymer is reacted at a temperature of 265°C and a pressure of 50 Pa for 3 hours. When the intrinsic viscosity of the product reaches 0.75 dL / g, it is cast into a strip and pelletized to obtain a primary product of a flame-retardant modified PTT material; S4: The primary product with a mass ratio of 40:60:3 is evenly mixed with the unmodified PTT masterbatch and the additives, and melt-extruded and granulated at a temperature of 270° C. and a screw speed of 400 r / min to finally obtain the finished flame-retardant modified PTT material.

[0018] In step S2, the chemical structure of tris(methylformatephenyl)-1,3,5-triazine is as shown in Formula II, Structural Formula II.

[0019] The tris(methylformatephenyl)-1,3,5-triazine is obtained by reacting 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine and methanol. The specific reaction steps are: dissolving 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (25 g) in methanol (200 mL), heating to 80°C, reflux reaction for 2 hours, cooling to room temperature, and filtering to obtain the product.

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

[0021] Example 2 The method for preparing the flame retardant modified PTT material of this embodiment comprises the following steps: [S1: 1,3-Propanediol (76 g) and dimethyl terephthalate (430 g) were added to a polymerization reactor, and 1.2 g of an ester exchange catalyst (antimony trioxide) was added at the same time. The ester exchange reaction was carried out at a temperature of 250°C and a pressure of 0.2 MPa. S2: After the transesterification reaction in step S1 was carried out for 2 hours, a mixture of 48 g of 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (abbreviated as ODOPB, CAS number 99208-50-1) and 57 g of 1,3-propylene glycol, and 0.5 g of a polycondensation catalyst (tetrabutyl titanate) was added. After continuing the reaction for 60 minutes, a toluene solution (100 mL) of tris(methylformatephenyl)-1,3,5-triazine with a mass concentration of 25% was added dropwise. After cross-linking reaction and separation, a prepolymer of a flame-retardant modified PTT material was obtained; S3: The prepolymer is reacted at a temperature of 270°C and a pressure of 60 Pa for 4 hours. When the intrinsic viscosity of the product reaches 0.8 dL / g, the prepolymer is cast into a strip and pelletized to obtain a primary product of a flame-retardant modified PTT material. S4: The primary product was mixed evenly with the unmodified PTT masterbatch and the additives in a mass ratio of 30:70:5, and melt-extruded and granulated at a temperature of 270°C and a screw speed of 400 r / min to obtain the flame-retardant modified PTT material. The additives were the same as those in Example 1.

[0022] In step S2, the chemical structure of tris(methylformatephenyl)-1,3,5-triazine is as shown in Formula II, Structural Formula II.

[0023] The tris(methylformatephenyl)-1,3,5-triazine is obtained by reacting 2,4,6-tris((p-carboxyphenyl)amino)-1,3,5-triazine and methanol. The specific reaction steps are: dissolving 2,4,6-tris((p-carboxyphenyl)amino)-1,3,5-triazine (25 g) in methanol (200 mL), heating to 80°C, reflux reaction for 2 hours, cooling to room temperature, and filtering to obtain the product.

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

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

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

[0027] The flame retardant modified PTT materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to performance tests, and the performance results are shown in Table 1: The flame retardancy test (LOI) is conducted according to ISO 4589-2. A specimen measuring 100 mm x 10 mm x 3 mm is prepared. The specimen is placed in an oxygen and nitrogen mixture, and the oxygen concentration is gradually adjusted until the specimen continues to burn after the flame is removed. The oxygen volume percentage at this point is recorded as the LOI value.

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

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

[0030] Heat Deflection Temperature (HDT) testing is conducted in accordance with ISO 75, using specimen dimensions of 80 mm × 10 mm × 4 mm. The specimen is placed on a test platform, a specified load (0.45 MPa) is applied, and the temperature is raised at a rate of 120°C / h. The temperature at which the specimen undergoes the specified deformation under the load is recorded.

[0031] Table 1

[0032] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Various changes and improvements are possible without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the invention as claimed.

Claims

1. A method for preparing a flame retardant modified PTT material, characterized in that: The preparation method comprises the following steps: S1: Add 1,3-propylene glycol and dimethyl terephthalate into a polymerization kettle, add an appropriate amount of transesterification catalyst, and carry out transesterification reaction at a temperature of 200-255°C and a pressure of 0.1-0.4 MPa; S2: After the transesterification reaction in step S1 has proceeded for a certain period of time, a mixture of dihydroxyphenylphosphaphenanthrene and 1,3-propylene glycol and an appropriate amount of a polycondensation catalyst are added, and the reaction is continued for 15 to 60 minutes. Then, an organic solution containing tris(methylformatephenyl)-1,3,5-triazine is added dropwise, and a prepolymer of a flame-retardant modified PTT material is obtained after a cross-linking reaction; S3: The prepolymer is further reacted at a temperature of 265-270° C. and a pressure of less than 80 Pa. When the intrinsic viscosity of the product reaches 0.6-0.9 dL / g, the prepolymer is cast into a strip and pelletized to obtain a primary product of a flame-retardant modified PTT material; S4: The primary product is mixed evenly with the unmodified PTT masterbatch and the additives, and melt-extruded and granulated at a temperature of 250-280° C. and a screw speed of 300-500 r / min to finally obtain the finished flame-retardant modified PTT material.

2. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: In step S1, the molar ratio of 1,3-propylene glycol to dimethyl terephthalate is 1:1.5-2.

5.

3. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: In step S1, the transesterification catalyst is at least one of antimony trioxide, antimony glycol, antimony acetate, stannous octoate, and dibutyltin dilaurate.

4. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: In step S2, the chemical structural formula of the dihydroxyphenylphosphaphenanthrene is as shown in Formula I, Structural Formula I: wherein R1 to R6 are independently selected from hydrogen, methyl or methoxy.

5. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: In step S3, the chemical structure of tris(methylformatephenyl)-1,3,5-triazine is shown in Formula II, Structural formula II; wherein R is H or .

6. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: The tris(methyl formate phenyl)-1,3,5-triazine is obtained by reacting tris(carboxyphenyl)-1,3,5-triazine and methanol.

7. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: 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.

8. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: The auxiliary agent is at least one of a lubricant, a toughening agent, an ultraviolet absorber, and a pigment.

9. The method for preparing the flame retardant modified PTT material according to claim 1, wherein: The mass ratio of the primary product to the unmodified PTT masterbatch and the additive is 30-50:50-70:1-5.

10. A flame retardant modified PTT material, characterized in that: The PTT material is prepared by the method for preparing the flame-retardant modified PTT material according to any one of claims 1 to 9.

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