Flame-retardant PBT / PC alloy material and preparation method thereof

Abstract

The invention discloses a flame-retardant PBT / PC (polybutylene terephthalate / polycarbonate) alloy material and a preparation method thereof. The flame-retardant PBT / PC alloy material is prepared from the following raw materials in parts by weight: 12-74.97% of polybutylene terephthalate; 10 to 20% of polycarbonate resin; 15 to 40% of flame-retardant glass fiber; 0.01 to 20% of a flame retardant; 0.01-1% of a transesterification inhibitor; 0.01 to 5% of an end-capping reagent; and 0-2% of other auxiliary agents. The flame-retardant glass fiber has the advantages that the DOPO-based derivative is selected as the flame retardant in the formula design according to the resin structure characteristics and the flame-retardant principle of the PBT / PC alloy material, and meanwhile, the DOPO-based epoxy compound with the flame-retardant function is attached to the surface of the glass fiber to prepare the flame-retardant glass fiber; the flame retardant DOPO-based epoxy compound on the surface of the glass fiber can block the wick effect of the glass fiber in the combustion process, compared with simple physical blending, the compatibility and mechanical properties of all components of a formula system are improved, and the PBT / PC alloy material is endowed with the characteristics of low warping and high strength under the combined action of the end-capping reagent and the ester exchange inhibitor.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and in particular to a flame retardant PBT / PC alloy material, a material preparation method and application. Background Art

[0002] Polybutylene terephthalate (PBT) is a polyester made by polycondensation of terephthalic acid and 1,4-butanediol. It is an important thermoplastic polyester and one of the five major engineering plastics. It has excellent mechanical properties, thermal properties, chemical resistance, electrical properties and processing properties. Polycarbonate plastic (PC) is an amorphous polymer that becomes a transparent glass after melting and cooling. It has excellent optical and mechanical properties, is also resistant to low temperatures, has low water absorption, is impact-resistant, has good insulation and aging resistance, and can withstand inorganic and organic dilute acids. PBT / PC alloy materials can combine the advantages of PBT and PC and are widely used in many fields.

[0003] PBT / PC alloy material has excellent heat resistance, impact resistance, chemical resistance, electrical insulation, dimensional stability, weather resistance and machinability. After flame retardant modification, it can meet UL 94V0 flame retardancy and is widely used in automotive parts, electronic equipment, electrical equipment, medical equipment and other fields.

[0004] Chinese invention patent CN115627063A discloses a flame retardant PBT / PC alloy material. By selecting a specific PBT resin, using a specific toughening agent and brominated polycarbonate / antimony trioxide flame retardant system, and adding a certain amount of phosphate, the material has excellent flame retardant properties and impact toughness, and effectively improves the color stability of the material during the injection molding process, which solves the injection molding yellowing problem of the material. Chinese patent CN105086385A discloses a high impact flame retardant PBT / PC alloy material and its preparation method. The invented high impact flame retardant PBT / PC alloy material has high impact resistance and environmental safety while having excellent flame retardancy. The preparation method has the characteristics of simple process, easy control of conditions, low cost, and low equipment requirements, which is suitable for industrial production. In view of the above-mentioned problem that the existing flame-retardant modified PC / PBT alloy material releases a large amount of smoke when burning, the Chinese invention patent CN109575561A provides a low smoke density halogen-free flame-retardant PC / PBT alloy material and its preparation method, and uses zinc borate and dimethyl silicone oil to synergistically suppress smoke, which can greatly reduce the smoke density of the PC / PBT alloy material. The prepared halogen-free flame-retardant PC / PBT alloy material has excellent flame retardancy and thermal stability, and also has the advantages of high strength and good processability. The process conditions involved are also easy to control, and it has the processing stability required for large-scale production, which is suitable for industrial production. The disclosed invention patents have made certain studies on the compounding of flame-retardant PBT / PC flame retardants and synergistic flame retardants, but there are few studies on the application of new flame retardants in PBT / PC alloy materials, especially the application of additives that can play multiple functions in PBT / PC. It is of great significance to study new flame retardants and flame retardant systems to prepare PBT / PC alloy materials to improve their performance and expand their applications. Summary of the invention

[0005] In order to fill the gap in the prior art, the present invention provides a flame retardant PBT / PC alloy material, a material preparation method and an application. In the formula design, the flame retardant glass fiber is prepared by attaching a DOPO-based epoxy compound to the glass fiber, which can block the "wick effect" of the glass fiber during the combustion process and give the alloy material excellent flame retardant properties. At the same time, the new DOPO derivative flame retardant, flame retardant glass fiber, capping agent and ester exchange inhibitor give the PBT / PC alloy material the characteristics of high strength, flame retardancy, low warpage and high heat resistance.

[0006] The present invention is achieved through the following technical solutions:

[0007] A flame retardant PBT / PC alloy material, a material preparation method and an application thereof, comprising the following raw materials in percentage by weight:

[0008]

[0009] The density of the polybutylene terephthalate is 1.30-1.38 g / cm 3 The melting point is 220-267°C. The number average molecular weight is 5000-12000, and the viscosity is 3000-10000 CPS.

[0010] The polycarbonate resin has a number average molecular weight of 17000-40000, a weight average relative molecular mass of 20000-50000, and a melt flow rate (test condition: 300° C.*1.2 kg): 10-25 g / 10 min.

[0011] The flame retardant is a DOPO-based derivative containing a phosphazene structure, with a phosphorus content of 10.5-12.5% ​​and a nitrogen content of 6-7%. The structural formula is as follows:

[0012]

[0013] The glass fiber has an alkali content of <0.8%, a volume density of 0.6-0.8 g / cm3, a single fiber diameter of 7-13 μm, a short cut length of 2-5 mm, a moisture content of ≤0.05%, and a combustible content of 1.10±0.15%. The surface of the glass fiber is sizing treated by spraying a DOPO-based epoxy compound solution on the surface of the glass fiber, and the mass fraction of the sizing agent is >0.3%. The mass fraction of the flame retardant in the DOPO-based epoxy compound solution is 1%-10%, and the structural formula of the DOPO-based epoxy compound is as follows:

[0014]

[0015] The end-capping agent is a DOPO-based epoxy compound, and the structural formula is as follows:

[0016]

[0017] The transesterification inhibitor is calcium hypophosphite or calcium dihydrogen phosphate, and the mass ratio of the capping agent to the inhibitor is capping agent:inhibitor=(6-10):1.

[0018] The other auxiliary agent may be one or more of an antioxidant, a lubricant, and a colorant.

[0019] The flame retardant PBT / PC alloy material, material preparation method and application include the following steps:

[0020] (1) Weigh various raw materials according to the formula ratio; mix polybutylene terephthalate, polycarbonate resin, flame retardant, end-capping agent, transesterification inhibitor and other additives uniformly with a high-speed mixer and set aside; weigh flame-retardant glass fiber according to the ratio and set aside.

[0021] (2) The resin and additive mixture is added through the main feed port of a twin-screw extruder, and flame-retardant glass fiber is added from the side feed port of the twin-screw extruder. After melt extrusion, granulation, drying and other processes at 220-250° C., the flame-retardant PBT / PC alloy material is obtained.

[0022] The PBT / PC alloy material prepared above has the characteristics of high strength, flame retardancy, low warpage and high heat resistance.

[0023] The advantage of the present invention is that the "wick effect" caused by glass fiber is solved by introducing the interfacial flame retardant and volume expansion technology in the formula design. At the same time, the DOPO-based derivative containing the phosphazene structure is used as a flame retardant, which has good compatibility with PBT and PC. While having a flame retardant effect, it has little effect on the mechanical properties of the PBT / PC alloy material. DOPO-based epoxy compounds are used as a capping agent. Calcium phosphate is used as an ester exchange inhibitor. By controlling the addition ratio of the capping agent and the ester exchange inhibitor, PBT / PC is given low warpage and high heat resistance. In addition, the capping agent contains DOPO groups and epoxy groups, which have both flame retardant and capping effects, so that a small amount of flame retardant can be added to achieve excellent flame retardant properties of the PBT / PC alloy material.

[0024] The beneficial effects of the present invention are:

[0025] 1) In the formula design of the present invention, a DOPO-based derivative containing a phosphazene structure is selected as a flame retardant. The synergistic effect of DOPO and the phosphazene structure gives PBT / PC flame retardant properties. The rigid structure of the benzene ring of the flame retardant has good carbonization properties, which gives the flame retardant excellent flame retardant efficiency. In addition, the flame retardant has good compatibility with the PBT / PC alloy material and has little effect on the mechanical properties of the alloy material.

[0026] 2) The present invention introduces interfacial flame retardant and volume expansion technology in the formula design. The surface of the glass fiber is treated with DOPO-based epoxy compounds to prepare flame-retardant glass fiber. The DOPO-based epoxy compounds attached to the surface of the glass fiber can block the "wick effect" of the glass fiber during the combustion process, thereby increasing the flame retardant efficiency during the combustion process. In addition, the flame retardant is evenly dispersed in the resin along with the glass fiber, which improves the distribution of the glass fiber in the resin and the interface bonding force between the glass fiber and the resin. Compared with simple physical blending, the amount of flame retardant added can be greatly reduced to achieve the same flame retardant effect, and the prepared PBT / PC alloy has more excellent mechanical properties. .

[0027] 3) The end-capping agent selected in the present invention contains DOPO groups and epoxy groups, which have both flame retardant and end-capping effects, so that a small amount of flame retardant can be added to achieve excellent flame retardant properties of PBT / PC alloy materials.

[0028] 4) The present invention imparts low warpage and high heat resistance properties to PBT / PC by controlling the addition ratio of the end-capping agent and the ester exchange inhibitor.

[0029] 5) The preparation method of the present invention is simple and is conducive to industrial production.

[0030] Through the above beneficial effects, the flame retardant PBT / PC material has the characteristics of high strength, flame retardancy, low warpage and high heat resistance, and is suitable for industrial production and application. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The embodiments and comparative examples of the present invention use the following materials, but are not limited to the following materials:

[0033] PBT, trade name 4500, produced by Jiangyin Jihua New Materials Co., Ltd.;

[0034] PC, product name 2800, produced by Covestro;

[0035] Flame retardant diethyl aluminum hypophosphite (ADP), trade name: 1230, produced by Clariant;

[0036] Flame retardant melamine polyphosphate (MPP), trade name: PNA350, produced by JLS;

[0037] Flame retardant bisphenol A-bis(diphenyl phosphate) BDP, trade name WSFR-BDP, produced in Wansheng, Zhejiang;

[0038] Phosphazene flame retardant PT100, commercially available;

[0039] Flame retardant DOPO derivative, commercially available;

[0040] Glass fiber, trade name ECS3031H, produced in Chongqing International

[0041] Flame retardant glass fiber, commercially available

[0042] Flame retardant DOPO derivative, commercially available

[0043] Capping agent, commercially available;

[0044] Transesterification inhibitor monocalcium phosphate, commercially available

[0045] Lubricant, silicone powder, commercially available;

[0046] Antioxidant 1010, commercially available;

[0047] Antioxidant 168, commercially available;

[0048] Masterbatch, commercially available;

[0049] Preparation methods of Examples 1-4 and Comparative Examples 1-8:

[0050] Preparation method of flame retardant PBT / PC material

[0051] (1) Weigh various raw materials according to the formula ratio; mix polybutylene terephthalate, polycarbonate resin, flame retardant, end-capping agent, transesterification inhibitor and other additives uniformly with a high-speed mixer and set aside; weigh flame-retardant glass fiber according to the ratio and set aside.

[0052] (2) The resin and additive mixture is added through the main feed port of a twin-screw extruder, and flame-retardant glass fiber is added from the side feed port of the twin-screw extruder. After melt extrusion, granulation, drying and other processes at 220-250° C., the flame-retardant PBT / PC alloy material is obtained.

[0053] Preparation of flame retardant PBT / PC material test specimens:

[0054] The above materials were dried in a forced air drying oven at 120° C. for 4 hours and then injection molded into standard specimens at an injection molding temperature of 220-270° C. The prepared mechanical properties specimens were conditioned in a standard laboratory environment (23° C., 50% RH) for 24 hours before testing.

[0055] Test methods for each performance index:

[0056] Tensile properties: According to ISO 527 method, sample size: 170*10*4mm, test speed 5mm / min.

[0057] Bending properties: According to ISO 178 method, sample size: 80*10*4mm, test speed 2mm / min.

[0058] Notched impact performance: According to ISO 179 method, sample size: 80*10*4mm.

[0059] Flame retardant performance: According to UL94 method, sample size: 127*12.7*1.6mm.

[0060] Table 1: Composition and properties of flame retardant PBT / PC alloy materials of Examples 1-4 and Comparative Examples 1-9

[0061]

[0062] It can be seen from the results of the embodiments and comparative examples in Table 1 that the embodiments of the present invention achieve UL 94V0 flame retardancy while the mechanical properties of the flame retardant PBT / PC material are more excellent. It can be seen from Examples 1, 2, Comparative Examples 1-2 and 9 that the flame retardant glass fiber can reduce the amount of flame retardant added compared to conventional glass fiber. This is only because the DOPO-based epoxy compound attached to the surface of the glass fiber can block the "wick effect" of the glass fiber during combustion, and the mechanical properties of the flame retardant PBT / PC are improved. It can be seen from Examples 1, 3, Comparative Examples 1-2 and 8 that the end-capping agent has an inhibitory effect on the ester exchange between PBT and PC, and the phosphate structure of the end-capping agent can play a flame retardant effect and reduce the amount of flame retardant added. It can be seen from Examples 1 and 4 that the ester exchange inhibitor can further reduce the ester exchange between PC and PBT and improve the mechanical properties of flame retardant PC / PBT. It can be seen from Examples 1-4 and Comparative Examples 1-7 that the flame retardant efficiency of the DOPO derivative flame retardant selected by the present invention is higher than that of the traditional compounded flame retardant, because the synergistic effect of the DOPO group and the phosphazene group in the DOPO derivative can greatly improve the flame retardant efficiency. The PBT / PC alloy material prepared by the present invention has the characteristics of high strength, flame retardancy, low warpage and high heat resistance, meets the use requirements in the fields of automobiles, electronics and electrical, and the preparation method is simple, which is conducive to industrial production.

Claims

1. A flame retardant PBT / PC alloy material, characterized in that: It is composed of the following raw materials in percentage by weight:

2. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The density of the polybutylene terephthalate is 1.30-1.38 g / cm 3 ; Melting point is 220-267℃; Number average molecular weight is 5000-12000, viscosity is 3000-10000CPS.

3. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The polycarbonate resin has a number average molecular weight of 17000-40000, a weight average relative molecular mass of 20000-50000, and a melt flow rate of 10-25 g / 10 min.

4. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The flame retardant is a DOPO-based derivative containing a phosphazene structure, with a phosphorus content of 10.5-12.5% ​​and a nitrogen content of 6-7%. The structural formula is as follows:

5. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The glass fiber has an alkali content of less than 0.8% and a volume density of 0.6-0.8 g / cm 3 , single fiber diameter: 7-13μm, short cut length: 2-5mm, moisture content ≤0.05%, combustible content 1.10±0.15%; the glass fiber surface is sizing treated by spraying DOPO-based epoxy compound solution on the glass fiber surface, and the mass fraction of the sizing agent is greater than 0.3%.

6. The flame retardant PBT / PC alloy material according to claim 5, characterized in that: The mass fraction of the flame retardant in the DOPO-based epoxy compound solution is 1%-10%, and the structural formula of the DOPO-based epoxy compound is as follows:

7. The flame retardant PBT / PC alloy material according to claim 5, characterized in that: The preparation of the flame retardant glass fiber comprises the following steps: (1) soaking the glass fiber in a mixed solution consisting of a silane coupling agent and an aqueous solution of ethylene glycol, wherein the silane coupling agent is aminosilane or the like, and the mass fraction of the silane coupling agent in the mixed solution is 15-25%, adjusting the pH of the solution, and performing a silane coupling agent modification treatment to obtain a silane coupling agent modified glass fiber; (2) The silane coupling agent modified glass fiber is immersed in a solution of a DOPO-based epoxy compound for modification, wherein the mass fraction of the DOPO-based epoxy compound is 0.8-1.3%, the solvent can be tetrahydrofuran, the temperature is 60-120° C., the time is 8-16 hours, and after filtering, washing, and drying, a flame-retardant glass fiber is obtained.

8. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The end-capping agent is a DOPO-based epoxy compound, and the structural formula is as follows:

9. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The transesterification inhibitor is calcium hypophosphite or calcium dihydrogen phosphate, and the mass ratio of the capping agent to the inhibitor is capping agent:inhibitor=(6-10):

1.

10. The flame retardant PBT / PC alloy material according to claim 1, characterized in that: The other auxiliary agents may be one or more of antioxidants, lubricants and colorants.

11. The method for preparing the flame retardant PBT / PC alloy material according to any one of claims 1 to 10, characterized in that: The following steps are involved: (1) Weigh various raw materials according to the formula ratio; mix polybutylene terephthalate, polycarbonate resin, flame retardant, end-capping agent, transesterification inhibitor and other additives uniformly with a high-speed stirrer and set aside; weigh flame-retardant glass fiber according to the ratio and set aside; (2) The resin and additive mixture is added through the main feed port of a twin-screw extruder, and flame-retardant glass fiber is added from the side feed port of the twin-screw extruder. After melt extrusion, granulation, drying and other processes at 220-250° C., the flame-retardant PBT / PC alloy material is obtained.

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