Ultrahigh-whiteness yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material

Abstract

The invention relates to an ultrahigh-whiteness and yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material, which is characterized by being prepared from the following raw materials in percentage by weight: 48 to 73.6 percent of PA6 slices, 0 to 6 percent of chopped glass fibers, 8 to 15 percent of nitrogen flame retardants, 14 to 20 percent of glass fiber powder, 0.1 to 2.2 percent of yellowing-resistant additives, 0.3 to 0.8 percent of wetting agents and 5 to 8 percent of titanium dioxide. The glass fiber reinforced halogen-free flame-retardant polyamide material provided by the invention has the characteristics of ultrahigh whiteness and yellowing resistance.

Description

Technical Field

[0001] The invention relates to the field of modified plastics, and in particular to the modification of an ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material. Background Art

[0002] In the unfilled and unreinforced formula, the whiteness (L) value of nitrogen-based flame-retardant polyamide materials can only reach above 97 after adding a large amount (addition amount exceeds 6%) of titanium dioxide (fluorescent whitening agent cannot be added, fluorescent whitening agent will cause material discoloration), and the whitest one is about 97.2. However, when glass fiber is added to the material, due to the interaction between titanium dioxide and short-cut glass fiber in the barrel of the twin-screw equipment, the whiteness (L) can only reach about 95 at most. When the whiteness is to be improved further, the addition of titanium dioxide is close to saturation, and it is difficult to increase the whiteness (L) even if more materials are added. Nitrogen-based flame-retardant polyamide materials are used in electrical housing materials and belong to decorative plastic parts. The market has put forward new requirements for the whiteness and yellowing of materials. Some electrical appliance manufacturers have put forward requirements for material indicators, with whiteness values ​​greater than 94, whiteness greater than 97 for some products, and glow-wire flame retardancy less than 30 seconds. At the same time, the yellowing requirements and toughness requirements must be met.

[0003] The mechanical properties of the ordinary color (L value of about 86) 20% glass fiber reinforced nitrogen flame retardant material are: density of about 1.34 g / cm3, modulus of about 5500Mpa, simple beam unnotched impact of 45 kJ / m2 (refer to DSM's K222-KGV4), but when the whiteness (L value) of the material exceeds 94, the modulus of the material will drop to 4500-4800Mpa due to the addition of a large amount of titanium dioxide, and the notched impact of the material will drop to 22-25 kJ / m2. For 20% glass fiber reinforced nitrogen flame retardant polyamide materials, under the premise of ensuring the flame retardant toughness modulus, the whiteness greater than 97 has been a technical problem that has been difficult to solve in this field for a long time. Summary of the invention

[0004] The purpose of the present invention is to develop a 20% glass fiber reinforced nitrogen flame retardant polyamide material with ultra-high whiteness, high flame retardancy and high toughness. The whiteness value is greater than 94, the flame retardancy is less than 30s, and the simply supported beam unnotched impact is greater than 25 kJ / m2. Some parts even require the material whiteness to be greater than 97, the flame retardancy does not exceed 10s, the simply supported beam unnotched impact is greater than 30 kJ / m2, and the yellowing resistance is significantly improved.

[0005] The present invention uses a twin-screw extruder with a specific aspect ratio, optimizes the antioxidant combination, adds a specific brand of wetting agent, pre-treats the short-cut glass fibers added as the main feed into glass fiber powder of about 50 meshes and then mixes with MCA, and pre-stirs the processing aid before adding it into PA6 slices that have been wetted with a liquid additive, and finally prepares an ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material, and the performance of the material is well maintained.

[0006] The present invention is achieved through the following technical solutions: An ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material, characterized in that it is composed of the following raw materials in percentage by weight: PA6 slices 48~73.6%; Chopped glass fiber 0~6%; Nitrogen flame retardant 8~15%; Glass fiber powder 14~20%; Anti-yellowing additive 0.1~2.2%; Wetting agent 0.3~0.8%; Titanium dioxide 5~8%.

[0007] The relative viscosity index of PA6 chips in the above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material is 2.0-2.5 viscosity, preferably one or two of 2.0 viscosity and 2.45 viscosity, and most preferably 2.45 viscosity PA6 chips.

[0008] The chopped glass fibers in the above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material are glass fibers with a chopped length of 3-5 mm and a monofilament diameter of 9-13 μm. The preferred size is a chopped length of 3 mm and a monofilament diameter of 10 μm.

[0009] The nitrogen-based flame retardant in the above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material is MCA, and the shape of MCA is powder.

[0010] The glass fiber powder of the ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material is mainly obtained by grinding short-cut glass fibers, and the preferred mesh size is 50-200 meshes, and the most preferred mesh size is 50 meshes.

[0011] The above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material, the anti-yellowing additive is a compound of two or more of antioxidant 1010, antioxidant 1098, antioxidant S-9228, and antioxidant JY-928. The preferred compounding scheme is a compounding of antioxidant 1010, antioxidant 1098 and antioxidant JY-928, and the most preferred compounding scheme is antioxidant 1010: antioxidant 1098: antioxidant JY-928 = 2:1:1.

[0012] The above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material, the wetting agent is a liquid additive model POLINYL ST of the Italian POLICHEM company, which not only plays a wetting role, but also makes the material have a very good demoulding effect. In this formula system, the addition of this additive improves the whiteness and toughness. For 20% glass fiber reinforced nitrogen-based flame-retardant polyamide materials, POLINYL ST makes its whiteness (L value) exceed 97.

[0013] The titanium dioxide described in the above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material is domestic rutile titanium dioxide, preferably titanium dioxide produced by the chlorination process.

[0014] The above-mentioned ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material is extruded and granulated using a parallel twin-screw extruder, the screw aspect ratio of the twin-screw extruder is 36:1~44:1, and the optimal is 40:1. The main engine speed is 300~350 rpm, and the temperature of each temperature zone of the twin-screw extruder is set to: Zone 1: 280°C, Zones 2 to 4: 250°C, Zone 5: 225°C, Zone 6: 200°C, Zone 7: 190°C, Zones 8 to 10: 175°C, and die head: 225°C. Wenzhou is the set value, and fluctuations within the range of ±10°C are allowed. The vacuum degree is a negative pressure of 0.04~0.08MPa. DETAILED DESCRIPTION

[0016] The twin screw extruder used in Comparative Example 3 has a length-to-diameter ratio of 44:1, and the twin screw extruder used in Comparative Example 4 has a length-to-diameter ratio of 36:1; the twin screw extruders used in other comparative examples and embodiments have a length-to-diameter ratio of 40:1.

[0017] Table 1 shows the preferred anti-yellowing additives: various raw materials are weighed according to the ratio in Table 1, mixed in a high-speed mixer, and then extruded and granulated by a twin-screw extruder, and then injection molded color plates are used to analyze the anti-yellowing effect of the materials.

[0018] Table 1 Comparative Example 1 and Examples 1 to 12.

[0019] Table 1 Components Comparative Example 1 Implementation 1 Implementation 2 Implementation 3 Implementation 4 Implementation 5 Implementation List 6 Implementation List 7 Implementation 8 Implementation List 9 Implementation 10 Implementation 11 Implementation 12 PA6 viscosity 2.45 62 62 62 62 62 62 62 62 62 62 62 62 62 Chopped Glass Fiber 20 20 20 20 20 20 20 20 20 20 20 20 20 MCA 12 12 12 12 12 12 12 12 12 12 12 12 12 Titanium dioxide 5 5 5 5 5 5 5 5 5 5 5 5 5 Antioxidant 1010 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Antioxidant 1098 0.5 0.4 0.3 0.25 0.15 0.1 0 0.4 0.3 0.25 0.15 0.1 0 Antioxidant S-9228 0 0.1 0.2 0.25 0.35 0.4 0.5 0 0 0 0 0 0 Antioxidant JY-928 0 0 0 0 0 0 0 0.1 0.2 0.25 0.35 0.4 0.5 Whiteness (L) HunterLab UltraScan PRO Colorimeter 85.3 88.9 89.3 90.2 90.6 90.9 88.3 88.7 89.4 91.0 89.5 88.9 88.3 Color plate baking conditions 150℃ / 24h after △E 18.22 10.32 5.67 3.88 2.75 1.95 1.55 9.35 5.24 3.45 2.59 1.81 1.51 As for whiteness value, the combination of three antioxidants is better than that of two antioxidants; when antioxidants 1010, 1098 and JY-928 are mixed, the higher the proportion of JY-928 is, the higher the whiteness is not necessarily.

[0020] Since the price of both S-9228 and JY-928 is much higher than that of ordinary antioxidants, considering the cost performance, whiteness, and actual anti-yellowing effect, the most preferred anti-yellowing additive is antioxidant 1010: antioxidant 1098: antioxidant JY-928 = 2:1:1.

[0021] Table 2 shows Examples 2 to 4 and Comparative Examples 13 to 22. MCA, glass fiber powder, titanium dioxide and processing aids were uniformly stirred with a high-speed stirring device for 10 min. At the same time, the PA6 slices and the liquid additive POLINYL ST were fully mixed with a high-speed stirring device to completely wet the PA6 slices. Finally, the stirred powder mixture was added to the PA6 slices wetted with the liquid additive POLINYL ST and continued to stir for 5 min before discharging. The main machine and the side feeding device were turned on to extrude the strands and pelletize.

[0022] The processing aids are antioxidants 1010, 1098, and JY-928. Antioxidant 1010: antioxidant 1098: antioxidant JY-928 = 2:1:1.

[0023] The present invention will be further described below in conjunction with Comparative Examples 2 to 4 and Embodiments 13 to 22.

[0024] Weigh each raw material according to the ratio in Table 2, mix them in a high-speed mixer, and then extrude and granulate them into a composite material through a twin-screw extruder. The composite materials prepared in the above comparative examples and examples are subjected to conventional physical and chemical analysis and color analysis to examine the conventional physical and chemical properties and color whiteness (L value) of the composite materials.

[0025] Table 2 Specific proportions of Comparative Examples 2-4 and Implementation Examples 13-22.

[0026] Table 2

[0027] Material Description Comparative Example 2 Comparative Example 3 Comparative Example 4 Implementation 13 Implementation 14 Implementation 15 Implementation 16 Implementation 17 Implementation 18 Implementation column 19 Implementation 20 Implementation 21 Implementation column 22 PA6 slice 2.45 60 58.2 58.2 58.8 58.8 58.2 60.2 61.2 62.2 61.4 61.6 61.4 61.4 MCA (powder) 12 12 12 12 12 12 12 12 12 12 12 12 12 Chopped glass fiber (main feed) 15 \ \ 15 \ \ \ \ \ \ \ \ \ Glass fiber powder (main feed) 0 15 15 0 15 15 15 15 15 15 15 14 13 Titanium dioxide 8 8 8 8 8 8 6 5 4 5 5 5 5 Chopped glass fiber (side feed) 5 5 5 5 5 5 5 5 5 5 5 6 7 Liquid additive POLINYL ST 0 0.6 0.6 0 0 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Anti-yellowing additives 0 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.0 0.8 1.0 1.0 Table 3 is the results of general physical and chemical performance analysis of Examples 2-4 and Examples 13-22.

[0028] Test items Detection Methods Comparative Example 2 Comparative Example 3 Comparative Example 4 Implementation 13 Implementation 14 Implementation 15 Implementation 16 Implementation 17 Implementation 18 Implementation column 19 Implementation 20 Implementation 21 Implementation column 22 Simply supported beam impact strength (flat without notch) kJ / m2 GB / T 1043.1-2008 20 28.7 27.9 20.5 23.1 30.1 33.5 34.5 37.3 34.2 33.8 35.5 38.5 Flexural modulusMpa (GB / T 9341-2008) 5000 5300 5350 5050 5030 5350 5530 5550 5500 5450 5490 5550 5750 Glow wire test (960°C, 1.5mm wafer), S GB / T 5169.11-2017 Not passed 17 19 Not passed 28-30 18 10 9 10 8 10 29-30 Not passed Table 4 shows the color analysis whiteness (L value) results of Examples 2 to 4 and Examples 13 to 22.

[0029] Test items Testing Instruments Comparative Example 2 Comparative Example 3 Comparative Example 4 Implementation 13 Implementation 14 Implementation 15 Implementation 16 Implementation 17 Implementation 18 Implementation column 19 Implementation 20 Implementation 21 Implementation column 22 Whiteness(L) HunterLab UltraScan PRO Colorimeter 92.15 96.11 96.01 95.14 96.51 97.25 97.15 97.08 95.95 97.05 95.89 96.89 96.85 According to Table 4, in order to achieve a whiteness value exceeding 97, the aspect ratio, titanium dioxide content, liquid additives, anti-yellowing additives, and glass fiber powder content are all indispensable.

[0030] Table 5 shows the color difference changes (△E) of Examples 2-4 and Examples 13-22 after baking in an oven at 150 degrees for 24 hours.

[0031] Color difference after 150℃ / 24h test Testing Instruments Comparative Example 2 Comparative Example 3 Comparative Example 4 Implementation 13 Implementation 14 Implementation 15 Implementation 16 Implementation 17 Implementation 18 Implementation column 19 Implementation 20 Implementation 21 Implementation column 22 △E HunterLab UltraScanPRO Colorimeter 20. 51 3.98 3.79 3.55 3.52 3.35 3.15 3.29 3.20 3.48 6.05 3.75 3.66 The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by the claims.

Claims

1. An ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material, characterized in that: It is composed of the following raw materials in weight percentage: PA6 slices 48~73.6%; Chopped glass fiber 0~6%; Nitrogen flame retardant 8~15%; Glass fiber powder 14~20%; Anti-yellowing additive 0.1~2.2%; Wetting agent 0.3~0.8%; Titanium dioxide 5~8%.

2. The ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The PA6 slices are PA6 slices with a relative viscosity index of 2.0-2.

5.

3. The ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The chopped glass fibers are chopped glass fibers with a chopped length of 3-5 mm and a single fiber diameter of 9-13 μm.

4. The ultra-high whiteness yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The nitrogen-based flame retardant is MCA.

5. The ultra-high whiteness yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The glass fiber powder is mainly obtained by grinding short chopped glass fibers.

6. The ultra-high whiteness yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The anti-yellowing auxiliary agent is prepared by compounding two or more of antioxidant 1010, antioxidant 1098, antioxidant S-9228 and antioxidant JY-928.

7. The ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The wetting agent is a liquid auxiliary agent with the model number of POLINYL ST produced by POLICHEM of Italy.

8. The ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to claim 1, characterized in that: The titanium dioxide is domestic rutile titanium dioxide.

9. The method for preparing an ultra-high whiteness, yellowing-resistant glass fiber reinforced halogen-free flame-retardant polyamide material according to any one of claims 1 to 8, characterized in that: A parallel twin-screw extruder is used for extrusion granulation, the screw aspect ratio of the twin-screw extruder is 40:1, the main engine speed is 300-350 rpm, and the temperature of each temperature zone of the twin-screw extruder is set as follows: zone 1: 280°C, zone 2 to zone 4: 250°C, zone 5: 225°C, zone 6: 200°C, zone 7: 190°C, zone 8 to zone 10: 175°C, and die head: 225°C.