Flame-retardant pbt composite material, preparation method and application thereof

Abstract

This invention discloses a flame-retardant PBT composite material, comprising the following components by weight: 40-73 parts PBT; 0.8-3.2 parts alkali lignin; 13-18 parts brominated flame retardant; 3-5 parts antimony trioxide; and 0.5-1 parts pentaerythritol. The weight-average molecular weight of the alkali lignin is 3000-10000. By selecting alkali lignin and pentaerythritol with specific molecular weights and using antimony trioxide as a laser color developer, this invention can effectively improve the laser marking defects of PBT composite materials modified with brominated flame retardants and has the advantage of thin-walled flame retardancy.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a flame-retardant PBT composite material, its preparation method, and its application. Background Technology

[0002] As one of the five major engineering plastics, polybutylene terephthalate (PBT) is widely used in various fields, such as electronics, lighting, home appliances, and automobiles, due to its excellent processing performance, solvent resistance, electrical properties, and heat resistance. Flame-retardant PBT, as an important branch of PBT materials, is often used in injection-molded lighting cups and household appliance housings.

[0003] Existing technologies that simultaneously achieve flame retardancy and laser marking include:

[0004] CN109852011A discloses a high flame-retardant, high-flowability, laser-printable glass fiber reinforced PBT material comprising: 100 parts PBT resin, 20-30 parts main flame retardant, 12-16 parts auxiliary flame retardant, 4-8 parts toughening agent, 0.2-0.8 parts antioxidant, 0.2-0.4 parts lubricant, 0.2-0.5 parts laser engraving powder (the laser engraving powder is bismuth oxide or an organic compound of copper), 0.2-0.6 parts anti-drip agent, and 25-30% glass fiber reinforcing agent by weight of the above total components. This patent not only possesses good flame retardancy but also laser marking performance.

[0005] CN107163518A discloses a high glow wire ignition temperature flame-retardant PBT composite material that can be laser-marked, comprising the following raw materials in parts by weight: 40-60 parts of PBT resin, 25-35 parts of glass fiber, 10-15 parts of main flame retardant, 5-10 parts of compound synergistic flame retardant, 2-6 parts of toughening agent, 0.5-1.0 parts of laser marking powder (the laser marking powder is tin oxide, antimony oxide and neodymium oxide), 0.1-0.2 parts of antioxidant, and 0.5-1.0 parts of other additives.

[0006] Because PBT has weak laser absorption, higher laser power and slower marking speeds are often required to obtain sufficiently clear marks during laser marking. Existing laser marking technologies frequently encounter problems such as poor marking quality, blurred patterns, and yellowing of marked areas when processing PBT. Therefore, there is a need for a PBT composite material that provides clear marking patterns, good color rendering, and thin-walled flame retardancy. Summary of the Invention

[0007] The purpose of this invention is to provide a thin-walled flame-retardant PBT composite material with good flame retardancy and excellent infrared laser marking properties, as well as its preparation method and application.

[0008] This invention is achieved through the following technical solution:

[0009] A flame-retardant PBT composite material, comprising the following components by weight:

[0010] PBT 40-73 copies;

[0011] Alkali lignin 0.8-3.2 parts;

[0012] 13-18 parts of brominated flame retardant;

[0013] 3-5 parts of antimony trioxide;

[0014] Pentaerythritol 0.5-1 part;

[0015] The weight-average molecular weight of the alkali lignin is 3000-10000.

[0016] In the flame-retardant PBT composite material of the present invention, the PBT content can be any value or a range between two values, ranging from 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts, 70 parts, 71 parts, 72 parts, and 73 parts. The alkali lignin content can be 0.8 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, and 1.8 parts. The content of the brominated flame retardant can be any one of the following values ​​or a range between two: 1.9 parts, 2.0 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, 3.0 parts, and 3.2 parts; the content of the antimony trioxide can be any one of the following values ​​or a range between two: 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, and 18 parts; the content of the antimony trioxide can be any one of the following values ​​or a range between two: 3 parts, 3.5 parts, 4 parts, 4.5 parts, and 5 parts; and the content of the pentaerythritol can be any one of the following values ​​or a range between two: 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, and 1.0 parts.

[0017] Based on the total weight percentage of flame-retardant PBT composite materials, the proportion of PBT shall not be less than 40 wt%.

[0018] The weight-average molecular weight of alkali lignin can be any value among 3000, 4000, 5000, 6000, 7000, 8000, 9000, and 10000, or a range between the two.

[0019] Preferably, the weight-average molecular weight of the alkali lignin is 3000-5000.

[0020] Alkali lignin is purified by ultrafiltration to obtain raw materials with different weight-average molecular weights. The ultrafiltration purification method is as follows: Alkali lignin is dissolved in a NaOH solution at pH=12, pre-filtered to remove insoluble particles, and then filtered using a membrane with the highest molecular weight cutoff (e.g., 10 kDa). The retentate is the high molecular weight fraction, and the permeate is the low molecular weight fraction. These fractions are then sequentially filtered through membranes with lower molecular weight cutoffs (e.g., 5 kDa and 3 kDa). The retentate and permeate of each fraction are then treated with acid precipitation to recover lignin, and finally dried.

[0021] If the weight-average molecular weight of alkali lignin is too low, it is easy to decompose during melt processing, resulting in insufficient laser marking performance. On the other hand, if the weight-average molecular weight of alkali lignin is too high, the proportion of active groups that absorb laser in alkali lignin is small, resulting in insufficient laser marking performance.

[0022] The intrinsic viscosity of PBT resin at 25℃ is 0.67-0.83 dl / g. The test standard GB / T 1632.5-2008 specifies the test method: at 25℃, the solution is phenol-tetrachloroethane solvent (mass ratio of phenol to tetrachloroethane is 3:2), using a capillary viscometer.

[0023] The average particle size of the antimony trioxide can range from 0.1 to 5 μm. The average particle size is measured using a Malvern particle size analyzer in an aqueous phase.

[0024] Depending on the actual situation, you can choose to add reinforcing glass fiber. Add 0-30 parts of glass fiber by weight.

[0025] Depending on the actual situation, 0-2 parts of additives may be added; the additives are selected from at least one of antioxidants, lubricants, and anti-dripping agents.

[0026] The amount of antioxidant added can be any value or a range between 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 parts.

[0027] The amount of lubricant added can be any value or a range between 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 parts.

[0028] The amount of anti-dripping agent added can be any value or a range between 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 parts.

[0029] The method for preparing the flame-retardant PBT composite material of the present invention is characterized by comprising the following steps: mixing the components uniformly according to the formula, and granulating the mixture by extrusion through a twin-screw extruder to obtain the flame-retardant PBT composite material. The temperature of each zone of the twin-screw extruder is 220-250℃, the feed rate is 300-500 kg / h, and the main extruder speed is 300-400 rpm.

[0030] The flame-retardant PBT composite material of the present invention is used to manufacture electrical appliance housings.

[0031] The present invention has the following beneficial effects:

[0032] This invention selects alkali lignin and pentaerythritol with specific molecular weights, uses antimony trioxide as a laser color developer, and utilizes the laser absorption characteristics of alkali lignin with a specific weight-average molecular weight to convert light energy into heat energy, accelerating the carbonization of pentaerythritol. In addition, alkali lignin can also develop color, which can effectively improve the laser marking defects of PBT composite materials modified by brominated flame retardants, and has the advantage of thin-wall flame retardancy. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0034] The raw materials used in this invention are sourced from the following sources:

[0035] PBT resin 1: Yizheng GX110, with an intrinsic viscosity of 0.67 dl / g at 25℃.

[0036] PBT resin 2: Yizheng GX112, with an intrinsic viscosity of 0.83 dl / g at 25℃.

[0037] Alkali lignin: derived from Quanlin, Shandong, and subjected to ultrafiltration grading.

[0038] Alkali lignin A: weight average molecular weight 3871;

[0039] Alkali lignin B: weight average molecular weight 4725;

[0040] Alkali lignin C: weight average molecular weight 7535;

[0041] Alkali lignin D: weight average molecular weight 13542;

[0042] Alkali lignin E: weight average molecular weight 2320;

[0043] Brominated epoxy: F-2100, Dead Sea, Israel;

[0044] Brominated polystyrene: SAYTEX 621, Albemarle;

[0045] Brominated polycarbonate: FG-8500, Teijin;

[0046] Poly(pentabromobenzyl acrylate): FR-1025, Dead Sea, Israel;

[0047] Antimony white: average particle size 0.7μm, S-05N, Changde Chenzhou;

[0048] Pentaerythritol (pure), from Eugenia, Switzerland;

[0049] Pentaerythritol stearate: PETS, Guangzhou Jiadel;

[0050] Antioxidants: RIANOX 1010 and RIANOX 168 were selected in a 1:1 mass ratio, along with Rianon.

[0051] Lubricant: LOXIOL P861 / 3.5, Corning;

[0052] Anti-dripping agent: X-010, Guangzhou Huigui;

[0053] Preparation method of flame-retardant PBT composite material in the examples and comparative examples: The components were mixed evenly according to the formula, and then extruded and granulated using a twin-screw extruder to obtain the flame-retardant PBT composite material. The temperature of each zone of the twin-screw extruder was 220-250℃, the feed rate was 300-500 kg / h, and the main extruder speed was 300-400 rpm.

[0054] Test methods:

[0055] (1) Laser Marking Performance: A laser marking machine was used to laser mark a square plate. The color difference ΔE of the square plate before and after laser marking was measured using a spectrophotometer. At the same time, a two-dimensional magnifying glass was used to test the diameter of a single point. The laser marking machine used was a TFL-M20 (Shenzhen Taide Laser Technology Co., Ltd.), and the marking parameters were: power of 60% of the rated power, frequency of 20KHz, and speed of 1500mm / s. The higher the color difference, the better the laser marking effect. The diameter of the single point of the laser marking was also examined. If the diameter of the single point was too large, it indicated that the laser marking point was diverging, resulting in a blurred pattern.

[0056] (2) Flame retardancy of thin walls: According to UL94-2013 standard, 0.8mm flame retardant strips were injection molded and the flame performance was tested.

[0057] Table 1: Component content and test results of flame-retardant PBT composite materials in Examples 1-6

[0058] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PBT resin 1 41 60 72 PBT resin 2 50 50 50 Alkali lignin A 1 2 1.5 3 Alkali lignin B 2 Alkali lignin C 2 Brominated epoxy 13 15 16 18 15 15 antimony white 3 4 3.5 5 4 4 Pentaerythritol 0.5 0.8 0.7 1 0.8 0.8 antioxidants 0.3 0.3 0.3 0.3 0.3 lubricant 0.3 0.3 0.3 0.3 0.3 Anti-dripping agent 0.3 0.3 0.3 0.3 0.3 0.3 Marking color difference △E 24.5 34.8 28.7 40.4 32.1 28.6 Single point diameter / μm 13.1 16.7 14.5 22.4 16.1 16.5 Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0

[0059] As can be seen from Examples 2 / 5 / 6, the preferred weight-average molecular weight of alkali lignin is 3000-5000.

[0060] Table 2: Component content and test results of flame-retardant PBT composite materials in Examples 7-10

[0061] Example 7 Example 8 Example 9 Example 10 PBT resin 2 50 50 50 50 Alkali lignin A 2 2 2 2 Brominated polystyrene 15 13 Brominated polycarbonate 15 Polypentabromobenzyl acrylate 15 2 antimony white 4 4 4 4 Pentaerythritol 0.8 0.8 0.8 0.8 antioxidants 0.3 0.3 0.3 0.3 lubricant 0.3 0.3 0.3 0.3 Anti-dripping agent 0.3 0.3 0.3 0.3 Marking color difference △E 33.6 36.7 40.8 38.2 Single point diameter / μm 16.6 16.2 16.5 16.8 Flame retardancy V-0 V-0 V-0 V-0

[0062] As shown in 2 / 7-9, the higher the color difference of laser marking, the better the flame retardant is when poly(pentabromobenzyl acrylate).

[0063] Table 3: Component content and test results of flame-retardant PBT composite materials in Comparative Examples 1-5

[0064] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PBT resin 2 50 50 50 50 50 Alkali lignin A 2 2 2 Alkali lignin D 2 Alkali lignin E 2 Brominated epoxy 15 15 15 15 15 antimony white 4 4 4 4 4 Pentaerythritol 0 0.2 2 0.8 0.8 antioxidants 0.3 0.3 0.3 0.3 0.3 lubricant 0.3 0.3 0.3 0.3 0.3 Anti-dripping agent 0.3 0.3 0.3 0.3 0.3 Marking color difference △E 15.3 16.3 48.5 21.2 24.6 Single point diameter / μm 16.3 16.6 31.2 16.4 15.2 Flame retardancy V-0 V-0 V-0 V-0 V-0

[0065] As shown in Comparative Example 1 / 2, when pentaerythritol is absent or present in very low amounts, the carbonization performance of laser marking is poor, resulting in small color difference in the marking.

[0066] As shown in Comparative Example 3, when the pentaerythritol content is too high, the char-forming performance is too strong, resulting in an excessively large single-point diameter and unclear pattern.

[0067] As shown in Comparative Example 4 / 5, the marking color difference is low when the weight average molecular weight of alkali lignin is too low or too high. This is because alkali lignin with a low weight average molecular weight is easily decomposed during the melt processing, while alkali lignin with a high weight average molecular weight has fewer active groups that absorb laser light, thus resulting in insufficient marking performance.

[0068] Table 4: Component content and test results of flame-retardant PBT composite materials of Comparative Examples 6-8

[0069] Comparative Example 6 Comparative Example 7 Comparative Example 8 PBT resin 2 50 50 50 Alkali lignin A 2 0.5 4.5 Brominated epoxy 15 15 15 antimony white 4 4 4 Pentaerythritol 0.8 0.8 Pentaerythritol stearate 0.8 antioxidants 0.3 0.3 0.3 lubricant 0.3 0.3 0.3 Anti-dripping agent 0.3 0.3 0.3 Marking color difference △E 14.7 19.2 55.8 Single point diameter / μm 14.5 11.3 30.8 Flame retardancy V-0 V-0 V-0

[0070] As can be seen from Comparative Example 6, pentaerythritol stearate cannot achieve the purpose of this invention.

[0071] As shown in Comparative Example 7, when the alkali lignin content is too low, the system's absorption of laser light is insufficient, resulting in a low color difference that does not meet the standard.

[0072] As shown in Comparative Example 8, when the alkali lignin content is too high, the single-point diameter is too large and the pattern is not clear.

Claims

1. A flame-retardant PBT composite material, characterized in that, By weight, it includes the following components: PBT 40-73 copies; Alkali lignin 0.8-3.2 parts; 13-18 parts of brominated flame retardant; 3-5 parts of antimony trioxide; Pentaerythritol 0.5-1 part; The weight-average molecular weight of the alkali lignin is 3000-10000.

2. The flame-retardant PBT composite material according to claim 1, characterized in that, The intrinsic viscosity of PBT resin at 25°C is 0.67-0.83 dl / g.

3. The flame-retardant PBT composite material according to claim 1, characterized in that, The brominated flame retardant includes at least one of brominated epoxy, brominated polystyrene, brominated polycarbonate, and pentabromobenzyl polyacrylate, preferably pentabromobenzyl polyacrylate.

4. The flame-retardant PBT composite material according to claim 1, characterized in that, The weight-average molecular weight of the alkali lignin is 3000-5000.

5. The flame-retardant PBT composite material according to claim 1, characterized in that, The average particle size range of the antimony trioxide is 0.1-5 μm.

6. The flame-retardant PBT composite material according to claim 1, characterized in that, It also includes 0-30 parts by weight of glass fiber.

7. The flame-retardant PBT composite material according to claim 1, characterized in that, The product also includes 0-2 parts by weight of additives; the additives are selected from at least one of antioxidants, lubricants, and anti-dripping agents.

8. A method for preparing the flame-retardant PBT composite material according to any one of claims 1-8, characterized in that, The process includes the following steps: mixing the components evenly according to the formula, and then extruding and granulating the mixture using a twin-screw extruder to obtain a flame-retardant PBT composite material.

9. The application of the flame-retardant PBT composite material according to any one of claims 1-8, characterized in that, Used to manufacture electrical appliance housings.