High-fluidity antistatic PBT material and preparation method thereof

Abstract

The invention discloses a high-flowability antistatic PBT (polybutylene terephthalate) material and a preparation method thereof, and the high-flowability antistatic PBT material comprises the following raw materials by weight: 50-80 parts of polybutylene terephthalate; 10 to 30 parts of glass fiber; 2 to 5 parts of a hyperbranched macromolecule / antistatic agent premix; 1-3 parts of an antistatic agent; the hyperbranched macromolecule / antistatic agent premix has a structure, an antistatic agent enters the inner cavity of the hyperbranched macromolecule, and the antistatic agent is selected from at least one of glycerol monostearate, alkyl amino acid salt or phosphate salt. The high-flowability antistatic PBT has the advantages of lasting antistatic property and high flowability, is suitable for injection molding of precise parts with thin walls and complex structures, and has obvious advantages in cost compared with permanent antistatic materials.

Description

Background Art

[0001] Polybutylene terephthalate (PBT) is a crystalline saturated polyester resin with excellent mechanical properties, low moisture absorption, chemical corrosion resistance and other characteristics. It is widely used in electronic and electrical components, packaging, automobiles and other fields. However, due to its high resistivity, PBT is prone to generate static electricity on the surface of the product during friction and contact, which brings a lot of trouble to the processing and application of the material. Especially in the electronics industry, static electricity leakage can cause semiconductor devices to malfunction and interfere with the normal operation of the circuit.

[0002] According to the different conductive mechanisms, antistatic agents can be roughly divided into two types: permanent antistatic and short-term antistatic. Permanent antistatic generally forms a conductive network inside the material through the antistatic agent to conduct the accumulated "electrons" to achieve the purpose of static dissipation, but its unit price and addition ratio are relatively high, resulting in the high market price of the final product, which cannot be widely rolled out in the mid- and low-end fields; short-term antistatic absorbs water molecules in the environment and internal antistatic agent molecules through the hydrophilic chain at the end of its molecular structure, and continuously migrates to the surface to fill the defective parts caused by long-term use. This type of antistatic agent has a continuous action time of 3-6 months, but its impact on cost is relatively small. Therefore, extending the action time of short-term antistatic agents can greatly broaden the application range of materials.

[0003] Chinese patent document CN 105778442 discloses a high temperature resistant antistatic PBT material, which is composed of the following weight parts: 60-70 parts of polybutylene terephthalate resin; 15-20 parts of polymer polyol, 5-10 parts of dihydroxy polydiphenylsiloxane modified with nanosilver, 3-10 parts of toughening agent; 10-15 parts of antistatic agent; 0.5-3 parts of antioxidant; 4-8 parts of dispersant; 1-5 parts of light shielding. The antistatic PBT material is prepared by adding a large amount of permanent antistatic agent and metal-modified siloxane, but the addition of a high proportion of additives significantly reduces the mechanical properties of the material, and does not show any cost advantage. Summary of the invention

[0004] The present invention provides a high-flow antistatic PBT material, which has the advantages of long-lasting antistatic and high flow, is suitable for injection molding of thin-walled, complex-structured precision parts, and has obvious cost advantages over permanent antistatic materials. It can fill the gap between short-acting antistatic PBT and permanent antistatic PBT, and expand the application range of antistatic PBT.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A high-flow antistatic PBT material, the raw material composition includes, by weight: 50-80 parts of polybutylene terephthalate; Glass fiber 10-30 parts; 2-5 parts of hyperbranched macromolecule / antistatic agent premix; 1-3 parts of antistatic agent; 0.5~1 part of antioxidant; Processing aid 0.5-1 part; The hyperbranched macromolecule / antistatic agent mixture has an inclusion structure, and the antistatic agent is dispersed in the internal cavity structure of the hyperbranched macromolecule material.

[0006] The antistatic agent is selected from a mixture of one or more of glycerol monostearate, alkyl amino acid salt or phosphate salt.

[0007] The intrinsic viscosity of the polybutylene terephthalate is 0.8-1.0 dl / g, and the melt mass flow rate is 40-60 g / 10 min; specifically, XW321 produced by Yizheng Chemical Fiber can be selected.

[0008] The glass fiber is alkali-free chopped strands with a diameter of 10-13 μm and a length of 3.0-4.5 mm; specifically, T435N or T436H of Taishan Fiberglass can be selected.

[0009] The hyperbranched macromolecule / antistatic agent premix, by weight percentage, comprises the following raw materials: Hyperbranched macromolecules 30-80%; Antistatic agent 20~70%.

[0010] The preparation method of the hyperbranched macromolecule / antistatic agent premix is ​​specifically as follows: Dissolve the hyperbranched macromolecule in methanol solution, add antistatic agent after it is completely dissolved, and seal and stir for 10-12 hours.

[0011] After the stirring is completed, the solution is rotary evaporated until the methanol is completely evaporated, and finally dried and crushed to prepare a hyperbranched macromolecule / antistatic agent premix, which is taken out for use.

[0012] The antistatic agent fully contacts the hyperbranched macromolecules in the methanol solution and enters the internal cavity.

[0013] The stirring method can be selected from magnetic stirring, bubble stirring, and ultrasonic stirring. According to common sense in the art, it is believed that the ultrasonic stirring effect of the formulation system of the present invention is better than magnetic stirring or bubble stirring. However, during the research and development process, it was unexpectedly found that magnetic stirring with a stirring speed of 80~120r / min for this system can achieve better results than bubble stirring and ultrasonic stirring of different frequencies (15KHz~60KHz).

[0014] Preferably, in the hyperbranched macromolecule / antistatic agent premix, the percentage of hyperbranched macromolecules is 60-80%.

[0015] The experiment found that the use of hyperbranched macromolecule / glycerol monostearate premix can significantly extend the antistatic validity period of the material.

[0016] Preferably, the antistatic agent is selected from a mixture of one or more of glycerol monostearate, alkyl amino acid salts or phosphate salts. AS-105 produced by Riken is further preferred.

[0017] The antioxidant is selected from a composite mixture of a primary antioxidant and an auxiliary antioxidant: The main antioxidant is one or more of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-tert-butyl-4-hydroxyphenyl) propionate, bis(2,4-di-tert-butylphenyl)tetratertol or 2,6-di-tert-butyl-4-4-cresol, and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine.

[0018] The processing aid is selected from one or more of calcium stearate, silicon masterbatch, and ethylene bisstearamide.

[0019] On the basis of the preferred raw material varieties mentioned above, it is further preferred that, by weight, the raw material composition of the high flow antistatic PBT material comprises: 60-70 parts of polybutylene terephthalate; Glass fiber 20-30 parts; 2-5 parts of hyperbranched macromolecule / antistatic agent premix; 1-3 parts of antistatic agent; 0.5~1 part of antioxidant; Processing aid 0.5-1 part.

[0020] More preferably, the raw material composition comprises: 65-70 parts of polybutylene terephthalate; Glass fiber 30 parts; 2-5 parts of hyperbranched macromolecule / antistatic agent premix; 1-3 parts of antistatic agent; 0.5~1 part of antioxidant; Processing aid 0.5-1 part.

[0021] The present invention also discloses a method for preparing the high-flow antistatic PBT material, comprising: After the raw materials are uniformly mixed, they are melt-kneaded and extruded into granules in a twin-screw extruder; the barrel temperatures of each section in the twin-screw extruder are: zone 1 temperature 180-210°C, zone 2 temperature 220-240°C, zone 3 temperature 220-240°C, zone 4 temperature 220-240°C, zone 5 temperature 210-230°C, zone 6 temperature 180-210°C, zone 7 temperature 180-210°C, zone 8 temperature 180-210°C, zone 9 temperature 180-210°C, and die head: 220-240°C.

[0022] The main engine speed is 300~400rpm, and the length-to-diameter ratio of the twin screw is 35:1.

[0023] Compared with the prior art, the advantages of the present invention are: Hyperbranched macromolecular materials have a cavity structure inside, and active functional groups are enriched on the surface. Antistatic small molecules can be included in the cavity, which can play a slow release role during subsequent use. In the early stage, PBT was used as a carrier to mix hyperbranched macromolecules and short-acting antistatic agents to prepare masterbatches, so that the antistatic agent is enriched in the cavity of the hyperbranched macromolecule, and then the antistatic PBT material is blended with PBT. The hyperbranched macromolecular structure is used to form a lubricating layer between polymer melts, reduce the entanglement of polymer molecular chains, and extend the antistatic effective period of the material through the slow release effect of the inner cavity. The cost of the prepared material has obvious advantages over permanent antistatic materials; it expands the application range of antistatic PBT. It meets certain application scenarios between short-term and permanent antistatic. Implementation

[0024] The PBT resin grade is PB XW321, and the relative density is 1.30g / cm 3 , intrinsic viscosity 0.8dl / g, Yizheng Chemical Fiber; The glass fiber grade is T435N, alkali-free chopped glass fiber, Taishan fiberglass; The hyperbranched macromolecule is CYD-C600, from Weihai Chenyuan; The antioxidant and processing aid are a mixture of antioxidant 1010, antioxidant 168 produced by Qibashi Company and EBS of Sino in a weight ratio of 1:1:1.

[0025] In the following examples and comparative examples, unless otherwise specified, the amounts of raw materials used are calculated in parts by weight.

[0026] 40 parts by weight of the hyperbranched macromolecules are gradually added to 200 parts by weight of a methanol solution, and after the solution is completely dissolved, 60 parts by weight of an antistatic agent are added, and the solution is sealed and stirred at a low speed for 12 hours, so that the hyperbranched macromolecules and the antistatic agent are fully in contact, and the antistatic agent is incorporated into the internal cavity. The solution is then rotary evaporated until the methanol is completely evaporated, and finally dried and crushed to prepare a hyperbranched macromolecule / antistatic agent premix, which is taken out for use.

[0027] The material performance test methods are as follows: 1. Flow properties: According to GB / T 3682.1-2018 "Determination of mass flow rate and volume flow rate of thermoplastic melts", tested at 250℃ / 2.16kg.

[0028] 2. Antistatic performance: Double 85 condition test is adopted to accelerate the precipitation of antistatic agent, and the surface resistivity of the material is tested by sampling at intervals of 200 hours.

[0029] Comparative Examples 1 to 7 and Examples 1 to 7 The raw material formulas for preparing high flow antistatic PBT materials in various embodiments and comparative examples are listed in Table 1 and Table 2 below. The preparation method of the material comprises the following steps: Weigh each component by weight percentage, mix in a high-speed mixer for 1-3 minutes; mix evenly to obtain a premix; place the premix in the main feed port of a twin-screw extruder, and let the glass fiber enter from the side feed port, melt co-extrude, and then granulate and cool. Except for Example 7, which uses 20kHz frequency ultrasonic stirring for 10 hours, the hyperbranched macromolecule / antistatic agent premix in the other examples or comparative examples uses 100r / min magnetic stirring for 10 hours.

[0030] The mechanical strength, flowability and antistatic properties of the antistatic PBT materials prepared in the examples and comparative examples were measured, and the specific data are listed in Table 3 and Table 4 below.

[0031] Table 1 serial number Comparative Example 1# Comparative Example 2# Comparative Example 3# Comparative Example 4# Comparative Example 5# Comparative Example 6# Comparative Example 7# PBT GX112 96 94 96 96 86 75 66 Glass fiber T435N 0 0 0 0 10 20 30 Glyceryl Monostearate 3 3 0 0 3 2 3 Alkyl amino acid salt 0 0 3 0 0 0 0 Phosphate salts 0 0 0 3 0 0 0 Hyperbranched macromolecules 0 2 0 0 0 0 0 Hyperbranched macromolecule / glyceryl monostearate premix 0 0 0 0 0 2 0 Hyperbranched macromolecule / alkyl amino acid salt premix 0 0 0 0 0 0 0 Hyperbranched macromolecule / phosphate premix 0 0 0 0 0 0 0 Antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Processing Aids 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Table 2 Example 1# Example 2# Example 3# Example 4# Example 5# Example 6# Example 7# PBT GX112 95 95 95 65 64 63 64 Glass fiber T435N 0 0 0 30 30 30 30 Glyceryl Monostearate 1 2 2 2 1 0 1 Alkyl amino acid salt 0 0 0 0 0 0 0 Phosphate salts 0 0 0 0 0 0 0 Hyperbranched macromolecules 0 0 0 0 0 0 0 Hyperbranched macromolecule / glyceryl monostearate premix 3 0 0 2 4 6 4 Hyperbranched macromolecule / alkyl amino acid salt premix 0 2 0 0 0 0 0 Hyperbranched macromolecule / phosphate premix 0 0 2 0 0 0 0 Antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Processing Aids 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Table 3 serial number Comparative Example 1# Comparative Example 2# Comparative Example 3# Comparative Example 4# Comparative Example 5# Comparative Example 6# Comparative Example 7# Tensile strength MPa 47 40 46 46 81 103 119 Bending strength MPa 70 62 67 68 104 158 193 <![CDATA[Izod impact strength kJ / m 2 > 6.6 6.1 6.8 7.1 6.2 6.7 7.5 Melt flow rate (250℃, 2.16kg) g / 0min 33 49 33 31 24 36 21 Surface resistivity (initial) <![CDATA[4.2×10 9 ]]> <![CDATA[5.2×10 9 ]]> <![CDATA[6.0×10 9 ]]> <![CDATA[3.3×10 9 ]]> <![CDATA[5.3×10 9 ]]> <![CDATA[6.7×10 9 ]]> <![CDATA[2.3×10 9 ]]> Surface resistivity (double 85 aging 200h) <![CDATA[3.7×10 9 ]]> <![CDATA[4.8×10 9 ]]> <![CDATA[2.8×10 9 ]]> <![CDATA[3.1×10 9 ]]> <![CDATA[3.2×10 9 ]]> <![CDATA[5.1×10 9 ]]> <![CDATA[4.4×10 9 ]]> Surface resistivity (double 85 aging 400h) <![CDATA[6.2×10 9 ]]> <![CDATA[1.9×10 9 ]]> <![CDATA[4.5×10 9 ]]> <![CDATA[5.2×10 9 ]]> <![CDATA[3.6×10 9 ]]> <![CDATA[5.9×10 9 ]]> <![CDATA[3.9×10 9 ]]> Surface resistivity (double 85 aging 600h) <![CDATA[1.7×10 10 ]]> <![CDATA[4.3×10 9 ]]> <![CDATA[3.9×10 10 ]]> <![CDATA[6.3×10 10 ]]> <![CDATA[4.4×10 10 ]]> <![CDATA[3.1×10 10 ]]> <![CDATA[4.1×10 10 ]]> Surface resistivity (double 85 aging 800h) <![CDATA[7.5×10 12 ]]> <![CDATA[6.2×10 11 ]]> <![CDATA[4.4×10 13 ]]> <![CDATA[1.8×10 12 ]]> <![CDATA[2.9×10 11 ]]> <![CDATA[7.0×10 11 ]]> <![CDATA[3.7×10 12 ]]> Surface resistivity (double 85 aging 1000h) <![CDATA[3.9×10 14 ]]> <![CDATA[2.8×10 13 ]]> <![CDATA[1.8×10 14 ]]> <![CDATA[5.5×10 14 ]]> <![CDATA[1.9×10 14 ]]> <![CDATA[2.5×10 12 ]]> <![CDATA[2.4×10 13 ]]> Table 4 serial number Example 1# Example 2# Example 3# Example 4# Example 5# Example 6# Example 7# Tensile strength MPa 41 40 39 121 110 102 109 Bending strength MPa 64 67 63 196 183 165 180 <![CDATA[Izod impact strength kJ / m 2 > 6.2 6.4 6.1 8 6.7 6.1 6.6 Melt flow rate (250℃, 2.16kg) g / 0min 45 41 39 32 44 61 48 Surface resistivity (initial) <![CDATA[2.5×10 9 ]]> <![CDATA[3.2×10 9 ]]> <![CDATA[6.8×10 9 ]]> <![CDATA[2.2×10 9 ]]> <![CDATA[7.6×10 9 ]]> <![CDATA[4.3×10 8 ]]> <![CDATA[9.6×10 9 ]]> Surface resistivity (double 85 aging 200h) <![CDATA[3.3×10 9 ]]> <![CDATA[5.7×10 9 ]]> <![CDATA[4.1×10 9 ]]> <![CDATA[5.5×10 9 ]]> <![CDATA[2.8×10 9 ]]> <![CDATA[1.7×10 8 ]]> <![CDATA[7.8×10 9 ]]> Surface resistivity (double 85 aging 400h) <![CDATA[4.7×10 9 ]]> <![CDATA[3.3×10 9 ]]> <![CDATA[5.2×10 9 ]]> <![CDATA[1.4×10 9 ]]> <![CDATA[8.1×10 9 ]]> <![CDATA[6.3×10 9 ]]> <![CDATA[1.0×10 10 <!-- 4 -->]]> Surface resistivity (double 85 aging 600h) <![CDATA[7.1×10 9 ]]> <![CDATA[2.9×10 9 ]]> <![CDATA[4.9×10 9 ]]> <![CDATA[3.4×10 9 ]]> <![CDATA[5.3×10 9 ]]> <![CDATA[1.6×10 9 ]]> <![CDATA[5.8×10 10 ]]> Surface resistivity (double 85 aging 800h) <![CDATA[1.8×10 10 ]]> <![CDATA[7.4×10 11 ]]> <![CDATA[7.4×10 11 ]]> <![CDATA[5.6×10 9 ]]> <![CDATA[1.6×10 9 ]]> <![CDATA[5.3×10 9 ]]> <![CDATA[2.4×10 11 ]]> Surface resistivity (double 85 aging 1000h) <![CDATA[6.6×10 11 ]]> <![CDATA[2.5×10 11 ]]> <![CDATA[2.5×10 11 ]]> <![CDATA[1.8×10 10 ]]> <![CDATA[2.8×10 9 ]]> <![CDATA[3.8×10 9 ]]> <![CDATA[9.8×10 11 ]]> As shown in Tables 1 to 4, the addition of antistatic agent reduces the surface resistivity of PBT material to 10 to the 9th power, achieving antistatic effect. It can be learned from Comparative Examples 1, 2 and Example 1 and Comparative Example 7 and Examples 4, 5, and 6 that the addition of hyperbranched macromolecules can delay the precipitation of antistatic, especially after hyperbranched macromolecules and antistatic premixing, the effect is more obvious, premixing can prompt more antistatic agents to enter the internal cavity of hyperbranched macromolecules, and the material plays a slow release effect during use. The presence of glass fiber can also reduce the precipitation rate of antistatic agent. In addition, hyperbranched macromolecules weaken the chain entanglement of PBT molecules and play a sliding bearing effect between molecular chains, thereby reducing the apparent viscosity of the material and improving the fluidity of the material. However, when the addition exceeds a certain value, the overall mechanical strength of the material will decline. Hyperbranched macromolecule / antistatic agent premixing uses low-speed magnetic stirring more effectively than ultrasonic stirring.

[0032] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high-flow antistatic PBT material, the raw material composition includes, by weight: 50-80 parts of polybutylene terephthalate; Glass fiber 10-30 parts; 2-5 parts of hyperbranched macromolecule / antistatic agent premix; 1-3 parts of antistatic agent.

2. The high flow antistatic PBT material according to claim 1, characterized in that: The polybutylene terephthalate has an intrinsic viscosity of 0.8-1.0 dl / g and a melt mass flow rate of 25-35 g / 10 min.

3. The high flow antistatic PBT material according to claim 1, characterized in that: The glass fiber is alkali-free chopped strands with a diameter of 10-13 μm and a length of 3.0-4.5 mm.

4. The high flow antistatic PBT material according to claim 1, characterized in that: The hyperbranched macromolecule / antistatic agent mixture has an inclusion structure, the antistatic agent is dispersed in the internal cavity structure of the hyperbranched macromolecule material, and the antistatic agent in the premix is ​​selected from a mixture of one or more of glycerol monostearate, alkyl amino acid salt or phosphate ester salt.

5. The high flow antistatic PBT material according to claim 1, characterized in that: The hyperbranched macromolecule / antistatic agent premix, by weight percentage, comprises the following raw materials: Hyperbranched macromolecules 30-80%; Antistatic agent 20~70%.

6. The high flow antistatic PBT material according to claim 5, characterized in that: The preparation method of the hyperbranched macromolecule / antistatic agent premix is ​​specifically as follows: dissolving the hyperbranched macromolecule in a methanol solution, adding an antistatic agent after the hyperbranched macromolecule is completely dissolved, and sealing and stirring for 10 to 12 hours; after the stirring is completed, rotary evaporating the solution until the methanol is completely evaporated, and finally drying and crushing to prepare the hyperbranched macromolecule / antistatic agent premix, which is taken out for use.

7. The method for preparing the hyperbranched macromolecule / antistatic agent premix according to claim 6, characterized in that: The sealed stirring is one of three methods: magnetic stirring, bubble stirring, and ultrasonic stirring.

8. The method for preparing the hyperbranched macromolecule / antistatic agent premix according to claim 7, characterized in that: The stirring speed of magnetic stirring is 80~120r / min.

9. The high flow antistatic PBT material according to claim 1, characterized in that: The antistatic agent is selected from a mixture of one or more of glycerol monostearate, alkyl amino acid salts or phosphate salts.