Photoresponsive BDP flame retardant and application thereof in photoinduced flame retardant polyester composite material

Abstract

The invention belongs to the technical field of macromolecular flame-retardant materials, and discloses a photoresponsive BDP flame retardant and application thereof in a photoinduced flame-retardant polyester composite material. The structural formula of the photoresponsive BDP flame retardant is shown in the specification, wherein n is an integer from 1 to 5. When the obtained photoresponse type BDP flame retardant is used for a polyester composite material, a benzophenone group of a sample subjected to injection molding initiates a cross-linking reaction under light and heat conditions, and a compact flame-retardant covering layer is formed. The surface cross-linking layer obstructs the transmission of oxygen and combustible materials, the oxygen index (LOI) can reach 35% or above, and the UL94 flame retardant grade reaches the V-0 grade (3.2 mm spline), which are superior to the conventional BDP system (LOI < = 25%, UL94 V-2 grade) and the conventional OP system (LOI < = 28%, UL94 V-2 grade) with the same addition amount, and are superior to the conventional BDP system (LOI < = 25%, UL94 V-2 grade) and the conventional OP system (LOI < = 28%, UL94 V-2 grade) with the same addition amount.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high molecular flame-retardant materials, and particularly relates to a light-responsive BDP flame retardant and application thereof in a light-induced flame-retardant polyester composite material. BACKGROUND

[0002] Polyester materials (such as polybutylene terephthalate PBT and polyethylene terephthalate PET) are widely used in the fields of electronic appliances, automobile parts and the like due to excellent mechanical properties and processability, but the flammable characteristics thereof limit the application thereof in high-risk environments. In the existing halogen-free flame-retardant system of polyester, OP series flame retardants are mainly used, the addition amount of which is large, the cost of which is high, and the mechanical properties of which are greatly affected. Bisphenol A bis(diphenyl phosphate) (BDP) is a commonly used halogen-free flame retardant, which is cheap and has good thermal stability and is widely used. However, BDP is not suitable for polyester because the conventional BDP has poor compatibility with polyester, and when the addition amount exceeds 3%, the BDP is easily precipitated, resulting in serious quality problems in the appearance of the product.

[0003] If a method for effectively utilizing the precipitation characteristics of BDP in polyester to achieve efficient flame retardation of polyester can be developed, it will have important significance and practical value. SUMMARY

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a light-responsive BDP flame retardant.

[0005] Another purpose of the present application is to provide a preparation method of the light-responsive BDP flame retardant.

[0006] Still another purpose of the present application is to provide application of the light-responsive BDP flame retardant in preparation of a light-induced flame-retardant polyester composite material, which utilizes the easy precipitation characteristics of BDP under heating, combines a light-induced crosslinking reaction to form a dense flame-retardant layer rich in flame retardant on the surface of the material, realizes efficient flame retardation under a low addition amount, and maintains the mechanical properties of the polyester matrix.

[0007] Another purpose of the present application is to provide a light-induced flame-retardant polyester composite material.

[0008] Still another purpose of the present application is to provide application of the light-induced flame-retardant polyester composite material.

[0009] The purposes of the present application are achieved by the following schemes. A light-responsive BDP flame retardant has the following structural formula: wherein n is an integer of 1-5; preferably, wherein n is mainly 1, and also contains an integer of n=2-5.

[0010] A preparation method of the above-mentioned photoresponsive BDP flame retardant, comprising the following steps: The intermediate is generated by reaction of phosphorus oxychloride and bisphenol A; after excess phosphorus oxychloride is removed by negative pressure evaporation, 4-hydroxybenzophenone is added, and then end-capping reaction is performed; after reaction is completed, the target product is obtained by purification through alkali washing and water washing.

[0011] The reaction for generating the intermediate refers to refluxing reaction at 65-80°C for 3-5h; Preferably, the reaction for generating the intermediate can also be performed under catalyst conditions, and the catalyst is a cationic resin, preferably a H-type macroporous cationic resin.

[0012] The molar ratio of bisphenol A, phosphorus oxychloride and 4-hydroxybenzophenone is 1:(3-8):(2.05-2.2); the amount of the catalyst is 2%-8% of the mass of bisphenol A.

[0013] The 4-hydroxybenzophenone is preferably added dropwise, and the dropwise addition time is controlled to be 1-1.5h.

[0014] The end-capping reaction refers to heating to 110-140°C for 1-4h; after reaction is completed, toluene is preferably added for dilution, and then alkali washing and water washing are performed.

[0015] The above-mentioned photoresponsive BDP flame retardant is applied to preparation of a photo-induced flame-retardant polyester composite material.

[0016] A photo-induced flame-retardant polyester composite material, comprising the following components in percentage by weight: Polyester matrix: 89-95.8%; Photoresponsive BDP flame retardant: 4-10%; Antioxidant: 0.1-0.5%; Lubricant: 0.1-0.5%.

[0017] The polyester matrix is at least one of PBT and PET.

[0018] The antioxidant is at least one of hindered phenolic antioxidant and hindered amine antioxidant.

[0019] The lubricant is at least one of pentaerythritol ester and low-molecular polyolefin; preferably, the lubricant is pentaerythritol stearate PETS.

[0020] A preparation method of the above-mentioned photo-induced flame-retardant polyester composite material, characterized by comprising the following steps: (1) Extrusion: polyester matrix, photo-induced flame-retardant polyester composite, antioxidant and lubricant are added into a twin-screw extruder, melt blended at 230-270℃, and extruded into granules; (2) Injection molding: the granules extruded in step (1) are injection molded at a processing temperature of 240-270℃; (3) Photo-crosslinking: the injection molded sample is placed into a UV box with heating function, and irradiated while heated, to obtain the photo-induced flame-retardant polyester composite.

[0021] The temperature of heating in step (3) is 70-140℃; the irradiation refers to irradiating the surface of the injection molded sample with a 365nm UV lamp at an intensity of 80-120mW / cm², and the irradiation is interval irradiation, each time for 10-30s, and the interval between two irradiations is 20-40min, and the total time is 4-8h. The benzophenone group initiates crosslinking reaction to form a dense flame-retardant covering layer.

[0022] The photo-induced flame-retardant polyester composite described above is applied in electronic devices, consumer electronics, medical devices and automobiles.

[0023] Compared with the prior art, the present application has the following advantages and beneficial effects: (1) Excellent flame-retardant performance: the surface crosslinked layer blocks the transmission of oxygen and combustible materials, and the oxygen index (LOI) can reach more than 35%, and the UL94 flame-retardant grade reaches V-0 level (3.2mm sample), which is better than the conventional BDP system (LOI≤25%, UL94 HB level) and OP system (LOI≤28%, UL94 V-2 level) with the same amount of addition.

[0024] (2) Good retention of mechanical properties: BDP is enriched on the surface, and the matrix purity is high, and the notched impact strength retention rate is ≥90%, solving the performance degradation problem caused by traditional flame retardants.

[0025] (3) Controllable process: both heating and UV crosslinking are post-processing, which is compatible with existing polyester molding equipment and does not require special modification. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is an infrared spectrum of the photo-responsive BDP flame retardant prepared in Example 1. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in combination with examples and drawings, but the embodiments of the present application are not limited thereto. In the examples, the specific conditions not mentioned are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not marked with the manufacturer, which are all conventional products that can be purchased on the market.

[0028] Unless otherwise specified, all reagents used in the examples are commercially available.

[0029] Example 1 Flame retardant preparation: 4.57 kg (20 mol) of bisphenol A and 0.23 kg of H-type macroporous cation exchange resin (Amberlyst 15) were added to a 50 L reactor. Under mechanical stirring (200-300 r / min), 15.33 kg (100 mol) of phosphorus oxychloride was slowly added over 1 hour. The temperature was raised to 70 °C, and the mixture was refluxed under normal pressure for 3 hours (a tail gas absorption device for HCl gas was installed at the top of the spherical condenser) until no significant HCl gas escaped from the spherical condenser. Stirring was maintained, the vacuum pump was turned on, and the vacuum degree was controlled at 0.1 MPa. The temperature was controlled at 60-70 °C, and distillation was carried out for 1.5-2 hours to remove excess phosphorus oxychloride. The temperature was then controlled to 80 °C, and 8.13 kg (41 mol) of 4-hydroxybenzophenone was slowly added over 1 hour. After the addition was complete, the temperature was raised to 120 °C and the reaction was maintained for 3 hours. The temperature was then lowered to 50 °C, and 10 L of toluene was added for dilution. The sample was washed successively with 5% sodium carbonate aqueous solution (6 L × 2 times) and deionized water (6 L × 3 times). After standing and separating into layers, the organic phase was collected and toluene was removed by vacuum distillation to obtain a pale yellow viscous liquid product, a photoresponsive BDP flame retardant. The infrared spectrum of the photoresponsive BDP flame retardant is attached. Figure 1 3340cm -1 The peak at 1628 cm⁻¹ is a characteristic peak of the benzene ring in benzophenone. -1 The peak at this point is the carbonyl peak of benzophenone, proving that the photoresponsive BDP flame retardant has been successfully synthesized.

[0030] Comparative Examples 1-2 and Examples 2-11: Extrusion: Polyester particles (PBT is Nantong Xingchen PBT1100, PET is Sinopec FC510A), flame retardant (at least one of the photoresponsive BDP flame retardant prepared in Example 1, BDP (CAS: 5945-33-5, Wansheng WSFR-BDP) or OP1230 (Clariant), antioxidant 1010, and lubricant PETS are added to a twin-screw extruder, melt-blended at 230-270°C, and then extruded and granulated.

[0031] Injection molding: The granules are vacuum dried at 80 degrees for 4 hours, and then injection molded at a processing temperature of 240-270 degrees.

[0032] Photocrosslinking: The injection-molded sample was placed in a UV chamber with heating function and heated to 120℃. Simultaneously, a 365nm UV lamp was used to irradiate the surface of the part at an intensity of 100mW / cm². Irradiation was performed at intervals of 20 seconds each, with a 30-minute interval between irradiations. The total time was 6 hours.

[0033] Mechanical properties and flame retardancy were tested on the photocrosslinked strips. Tensile testing followed ISO 527-2, notched impact strength followed ISO 179 / 1eA, heat distortion temperature followed ISO 75-2, LOI testing followed ISO 4598-2, and flame retardancy testing followed UL 94. Surface exudation was detected by wiping with a paper towel; if liquid was present, exudation occurred; otherwise, no exudation occurred.

[0034] Table 1. Weight percentage (wt%) of each component in Comparative Examples 1-2 and Examples 2-11 and the properties of the obtained samples The data shows that using photoresponsive BDP flame retardant can achieve significantly higher flame retardant performance than ordinary BDP and OP1230 at the same addition amount, while maintaining mechanical properties.

[0035] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A photoresponsive BDP flame retardant, characterized in that... The structural formula is as follows: ； Where n is an integer from 1 to 5.

2. A method for preparing the photoresponsive BDP flame retardant according to claim 1, characterized in that... Includes the following steps: Phosphorus oxychloride and bisphenol A were used as raw materials to generate an intermediate. After removing excess phosphorus oxychloride by negative pressure evaporation, 4-hydroxybenzophenone was added, followed by end-capping reaction. After the reaction was completed, the target product was obtained by purification.

3. The method for preparing the photoresponsive BDP flame retardant according to claim 2, characterized in that: The reaction intermediate refers to the reaction being carried out under reflux at 65-80℃ for 3-5 hours; The terminology for the end-capping reaction refers to heating to 110-140℃ and reacting for 1-4 hours.

4. The preparation method of the photoresponsive BDP flame retardant according to claim 2, characterized in that: The reaction that generates the intermediate is carried out under catalytic conditions, and the catalyst is a cationic resin.

5. The method for preparing the photoresponsive BDP flame retardant according to claim 2, characterized in that: The molar ratio of bisphenol A, phosphorus oxychloride and 4-hydroxybenzophenone is 1:(3-8):(2.05-2.2); when a catalyst is present, the amount of the catalyst is 2%-8% of the mass of bisphenol A.

6. A photo-induced flame-retardant polyester composite material, characterized in that... The components include the following weight percentages: Polyester matrix: 89-95.8%; Photoresponsive BDP flame retardant: 4-10%; Antioxidant: 0.1-0.5%; Lubricant 0.1-0.5%; The photoresponsive BDP flame retardant is at least one of the photoresponsive BDP flame retardants described in claim 1.

7. The photo-induced flame-retardant polyester composite material according to claim 6, characterized in that: The polyester matrix is ​​at least one of PBT and PET; The antioxidant is at least one of hindered phenolic antioxidants and hindered amine antioxidants; The lubricant is pentaerythritol ester, at least one of low molecular weight polyolefins.

8. A method for preparing a photo-induced flame-retardant polyester composite material according to claim 6 or 7, characterized in that... Includes the following steps: (1) Extrusion: The polyester matrix, photoresponsive BDP flame retardant, antioxidant and lubricant are added to a twin-screw extruder, melt-blended at 230-270℃, and then extruded and granulated. (2) Injection molding: The granules extruded in step (1) are injection molded at a processing temperature of 240-270℃; (3) Photocrosslinking: The injection-molded sample is placed in a UV box with heating function and irradiated with light while being heated to obtain photo-induced flame-retardant polyester composite material.

9. The method for preparing the photo-induced flame-retardant polyester composite material according to claim 8, characterized in that: The heating temperature mentioned in step (3) is 70-140℃; the light irradiation refers to using a 365nm UV lamp to irradiate the surface of the injection-molded sample with an intensity of 80-120mW / cm². The irradiation is done in intervals, each time for 10-30s, with an interval of 20-40min between two irradiations, for a total time of 4-8h.

10. The application of the photo-induced flame-retardant polyester composite material according to claim 6 or 7 in electronic devices, consumer electronics, medical devices, and automobiles.

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