A low electrochemical corrosion flame-retardant polyamide composition and preparation method thereof

Abstract

The invention discloses a low electrochemical corrosion flame-retardant polyamide composition and a preparation method thereof. The composition is composed of the following raw materials in parts by weight: 26-89.96% of a polyamide resin; 10-35% of a filler; 0.01-25% of a flame retardant; 0.01-5% of a molecular sieve; 0.01-5% of an acid scavenger; 0.01-1% of an antioxidant; 0-2% of a processing aid; and 0-1% of a masterbatch. The beneficial effects of the present invention are as follows: When flame-retardant polyamide materials come into contact with metal conductors, the metal conductors are usually corroded under the combined effects of the corrosiveness of the material, the current, and the environment. In order to solve the "pain points" in the application of flame-retardant polyamide materials, a new type of highly heat-resistant flame retardant is introduced in the formula design, thereby reducing the corrosion of the polyamide material caused by the degradation of the flame retardant and the flame retardant processing process, effectively solving the shortcomings of the P-N system, such as low temperature resistance and strong corrosiveness. At the same time, through the synergistic effect of molecular sieves and acid absorbers, the generation and residue of small molecules in the processing of flame-retardant polyamide materials are reduced, further reducing the corrosiveness of the flame-retardant polyamide materials.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, in particular to a low electrochemical corrosion flame-retardant polyamide composition and a preparation method thereof. Background Art

[0002] Polyamide (nylon) is a key engineering plastic with excellent fatigue resistance, creep resistance, wear resistance, chemical resistance, self-lubrication, and high mechanical properties. It is widely used in automobiles, aircraft, high-speed rail, instrumentation, electronics, sporting goods, and other fields. However, unmodified nylon is easily flammable and produces large amounts of molten droplets during combustion, which can easily cause fires in the electronics industry. Therefore, research on the flame retardancy of nylon is a focus of both academic and industrial research.

[0003] Research on PA flame retardancy has achieved remarkable results in recent years. The following methods are usually used to improve the flame retardant properties of nylon materials: ① adding flame retardants during the PA molding process; ② grafting flame retardant molecules on the PA surface or molecular chain; ③ copolymerizing with flame retardants during the resin polymerization stage; the first melt blending method is the method commonly used in the industrial field. In recent years, a series of studies have been conducted on flame retardant nylon materials through physical blending.

[0004] Chinese patent CN202210147454 provides a novel P / N multi-element reactive nylon 66 flame retardant and its preparation method. Under the protection of inert gas, trimethyl phosphite or triphenyl phosphite, cyanuric chloride, and β-alanine are used as the main raw materials. Through a two-step reaction, the flame retardant is grafted onto the PA66 molecular chain to achieve the synergistic flame retardancy of the P / N multi-element. CN202111666196 grafts DOPO derivatives onto PA6 resin to achieve the flame retardant properties of PA6 resin. Chinese patent CN202111483904 achieves the flame retardant properties of PA66 materials through flame retardants, synergistic flame retardants, and liquid silicone rubber in the formulation design. The prepared flame-retardant PA66 has excellent flame retardant effects and good comprehensive mechanical properties. When the amount of flame retardant used is small, a modified material with flame retardancy of UL94 V0 can be prepared, which has a significant cost advantage compared to traditional flame retardant materials on the market. Chinese patent CN202011411857 ​​relates to a method for preparing a novel phosphorus / nitrogen / sulfur flame retardant based on thiourea and ammonium polyphosphate. The preparation principle is through the ion exchange reaction between thiourea and ammonium polyphosphate, belonging to the field of flame retardant synthesis and flame retardant modification of nylon materials. The resulting thiourea-ammonium polyphosphate flame retardant is mainly used in the flame retardant treatment of nylon materials, and the flame retardant properties and thermal stability of nylon materials are improved by melt blending. Published invention patents have more research on the flame retardant properties of nylon materials, but less on electrochemical corrosion properties, especially electrochemical corrosion in high temperature and high humidity environments. However, the relevant properties are crucial for the material application of flame-retardant nylon. Summary of the Invention

[0005] In order to fill the gap in the prior art, the present invention provides a low electrochemical corrosion flame-retardant polyamide composition and a preparation method thereof. Through the principle of flame retardant molecular structure design, a highly heat-resistant flame retardant with a new structure is introduced, which reduces the impact of the flame retardant and the flame retardant processing on corrosion. The corrosiveness of the flame retardant material is further reduced by adsorbents and molecular sieves, thereby achieving the low corrosion characteristics of the flame-retardant polyamide.

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

[0007] A low electrochemical corrosion flame-retardant polyamide composition, comprising the following raw materials in parts by weight:

[0008] Polyamide resin 26-89.96%;

[0009] Filler 10-35%;

[0010] Flame retardant: 0.01-25%;

[0011] Molecular sieve 0.01-5%

[0012] Acid absorbent: 0.01-5%;

[0013] Antioxidant: 0.01-1%;

[0014] Processing aids: 0-2%;

[0015] Masterbatch: 0-1%.

[0016] The polyamide resin may be one or more of PA6T / X, PA10T, PA10T / X, PA9T, PA46, PA4T, PA5T, PA5T / X, PA6, PA56, PA66, PA6 / 66, PA66 / 6, and PA66 / 6T;

[0017] The filler can be a fibrous or non-fibrous filler according to its form. The fibrous filler can be one or more of glass fiber, aramid fiber, carbon fiber, basalt fiber, etc., and the non-fibrous filler can be one or more of whiskers, glass beads, calcium carbonate, wollastonite, mica, kaolin, and talc.

[0018] The preferred filler of the present invention is glass fiber, with an alkali content of less than 0.8%, a bulk density of 0.6-0.8 g / cm3, a monofilament fiber diameter of 7-13 μm, a short cut length of 2-5 mm, and a moisture content of ≤0.05%.

[0019] The flame retardant is diethyl hypophosphite cage polysiloxane with whiteness > 95%, moisture < 0.3%, pH > 4, Si content: 10-15%; P content: 25-30%, density 1.32-1.40g / cm 3 ; Particle size (D 50 ) 10-20; the structural formula of the flame retardant is as follows:

[0020]

[0021] The molecular sieve is a Beta structure molecular sieve with SiO2 / Al2O3 as the product composition and a specific surface area of ​​500m 2 / g, powder form.

[0022] The acid absorbent is magnesium oxide, with an effective content of >99% and a specific surface area of ​​>170 m 2 / g, powder form.

[0023] The antioxidant is a mixture of a phosphite antioxidant and a hindered phenol antioxidant in a ratio of 1:1 (by weight), wherein the phosphite antioxidant can be tetrakis(2,4-di-tert-butylphenol)-4,4'-biphenyl diphosphite, CAS: 119345-01-6; tris[2,4-di-tert-butylphenyl]phosphite, CAS No. 31570-04-4; 3,9-bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, CAS No. 154862-43-8; and the hindered phenol antioxidant can be N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, CAS No. 23128-74-7; triethylene glycol ether-bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, CAS No. 36443-68-2; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, CAS No. 6683-19-8, etc.

[0024] The hindered phenol antioxidant of the present invention is preferably N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, and the phosphite antioxidant is preferably tetrakis(2,4-di-tert-butylphenol)-4,4'-biphenyl diphosphite.

[0025] The processing aid is an organic additive that can provide both internal and external lubrication without affecting flame retardancy, and can be one or more of silicone powder, silicone masterbatch, PETS, montan wax, polyethylene wax, oxidized polyethylene wax, calcium stearate, and the like.

[0026] The processing aid of the present invention is preferably a mixture of silicone powder, phenyl silicone and silicon dioxide in a ratio of 1:1.

[0027] The masterbatch has a carbon black content of 10-99% and a carrier of PA6 or a lubricant.

[0028] The method for preparing the low electrochemical corrosion flame-retardant polyamide composition comprises the following steps:

[0029] (1) The moisture content of polyamide resin is not higher than 2000ppm;

[0030] (2) Weigh the dried raw materials according to the formula ratio; mix the polyamide resin, flame retardant, molecular sieve, acid absorber, antioxidant, processing aid, and masterbatch uniformly through a high-speed mixer and set aside; weigh the filler according to the ratio and set aside;

[0031] (3) The resin and additive mixture is added through the main feed port of a twin-screw extruder, and the filler is added through the side feed port of the twin-screw extruder. After melt extrusion at 260°C, granulation, and drying, the flame retardant polyamide composition is obtained.

[0032] The flame retardant polyamide composition can be used in fields such as new energy vehicles, home appliances, and electronic appliances.

[0033] Beneficial effects of the present invention:

[0034] 1) The present invention is based on the principle of flame retardant molecular structure design and selects a novel flame retardant molecule, diethyl hypophosphite cage polysiloxane, which combines the fluidity of the carbon film formed by ADP during combustion with the increased residual carbon content of cage polysiloxane, thereby improving the flame retardant efficiency of the flame retardant and overcoming the disadvantage of easy precipitation of halogen-free flame retardants on the market. The flame retardant's characteristics of low precipitation and high temperature resistance give it low electrochemical corrosion, and at the same time give the flame retardant nylon material prepared with the flame retardant the characteristics of low electrochemical corrosion.

[0035] 2) The acidic characteristics of halogen-free flame-retardant nylon materials are an important reason for their corrosiveness. During the formulation design process, the acidity and alkalinity of the material are adjusted through the synergistic effect of molecular sieves and acid absorbers, thereby reducing corrosiveness.

[0036] 3) The present invention achieves the purpose of reducing the corrosiveness of flame retardant polyamide materials by limiting the specifications of molecular sieves. The selected molecular sieves have a high specific surface area (greater than 500m 2 / g) can have a strong adsorption capacity for small molecules in the material, and the Al2O3 in the molecular sieve component can + reaction, reducing the acidity in the material, thereby reducing the corrosiveness of the flame retardant polyamide material.

[0037] 4) The present invention achieves the purpose of reducing the corrosiveness of flame-retardant polyamide materials by selecting and limiting the specifications of the acid scavenger. Magnesium oxide with high reactivity and large specific surface area is selected as the acid scavenger, which synergistically reduces the corrosiveness of flame-retardant nylon materials with the molecular sieve.

[0038] 5) The selection of the flame retardant molecular structure, the type of molecular sieve and the specifications of the acid absorber in the present invention are selected and designed based on the characteristics of the flame retardant nylon material. The three work together to achieve the low electrochemical corrosion characteristic of the flame retardant nylon material.

[0039] The above-mentioned beneficial effects achieve the excellent flame retardant properties, low electrochemical corrosion, low precipitation and high strength characteristics of the polyamide composition, thereby enhancing the market competitiveness of the product. DETAILED DESCRIPTION

[0040] 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 the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] The following materials are used in the examples and comparative examples of the present invention, but are not limited to the following materials:

[0042] Polyamide resin, trade name YH800, produced by Yueyang Petrochemical;

[0043] Flame retardant, trade name OP1230, produced by CLARIANT;

[0044] Flame retardant, trade name OP1314, produced by CLARIANT;

[0045] Flame retardant, trade name OP1400, produced by CLARIANT;

[0046] Flame retardant: diethyl hypophosphite cage polysiloxane, commercially available;

[0047] Glass fiber, trade name ECS301HP-3, produced by Chongqing International Composite Materials Co., Ltd.;

[0048] Synergistic flame retardant, trade name; DC43-821, produced by Dow Corning;

[0049] Processing aid, commercially available under the trade name silicone powder;

[0050] Antioxidant 1098, hindered phenol antioxidant, commercially available;

[0051] Antioxidant PEPQ, a phosphite antioxidant, commercially available;

[0052] Black masterbatch, PA6-2015, commercially available;

[0053] Molecular sieve: Trade name BEA150 produced by CLARIANT;

[0054] Molecular sieve: Trade name CZP 27, produced by CLARIANT;

[0055] Acid absorbent, trade name RA150, produced by ICL;

[0056] Acid scavenger, trade name Kyowamag 150, produced by Kyowa Chemical Industry Co., Ltd.

[0057] Preparation methods of Examples 1-10 and Comparative Examples 1-7:

[0058] Preparation of flame retardant polyamide composition:

[0059] Weigh various dried raw materials according to the formula ratio; mix polyamide resin, flame retardant, molecular sieve, acid absorber, synergistic flame retardant, antioxidant, processing aid, and masterbatch uniformly with a high-speed mixer and set aside; weigh filler according to the ratio and set aside; add the above-mentioned resin and additive mixed raw materials through the main feeding port of the twin-screw extruder, and add the filler through the side feeding port of the twin-screw extruder; and obtain the flame-retardant polyamide composition after melt extrusion, granulation, drying and other processes at 260°C.

[0060] Preparation of flame retardant polyamide composition test specimens:

[0061] 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 280-300°C. The mechanical properties of the injection-molded specimens were conditioned in a standard laboratory environment (23°C, 50% RH) for 24 hours before testing.

[0062] Test methods for various performance indicators:

[0063] Tensile properties: According to ISO 527 method, specimen size: 170*10*4mm, test speed 5mm / min.

[0064] Bending properties: According to ISO 178 method, specimen size: 80*10*4mm, test speed 2mm / min.

[0065] Notched impact performance: According to ISO 179 method, sample size: 80*10*4mm.

[0066] Flame retardant performance: According to UL94 method, sample size: 127*12.7*1.6mm.

[0067] Precipitation resistance: Place a 150*100*3.2mm sample in an environmental chamber with the following settings: temperature: 85°C, humidity 85% RH, time 250h, and visually evaluate the state of surface precipitation.

[0068] Electrochemical corrosion performance: A 1cm cylindrical copper wire was directly inserted into the flame-retardant polyamide material with a current of 1mA. The above device was placed in an environmental chamber at 85℃ and 85%RH for 250h. At the end of the experiment, the electrochemical corrosion performance was evaluated by evaluating the degree of corrosion on the surface of the copper wire in contact with the flame-retardant nylon. The corrosion levels were divided into three levels from light to heavy: no corrosion, slight corrosion, corrosion, and severe corrosion.

[0069] Table 1: Composition and properties of flame retardant polyamide compositions of Examples 1-10:

[0070]

[0071] Table 2: Composition and properties of flame retardant polyamide compositions of comparative examples 1-6:

[0072]

[0073] As can be seen from Tables 1 and 2, compared with other halogen-free flame retardants commercially available on the market, diethyl hypophosphite cage polysiloxane can effectively reduce the amount of flame retardant added to achieve the same flame retardant effect. The flame retardant polyamide material prepared has low electrochemical corrosion (Examples 1-5 and Comparative Examples 5-6). Compared with the flame retardant nylon material prepared by physical blending of ADP and silicon synergists, it can achieve a better flame retardant effect and lower corrosion at the same addition amount (Example 1 and Example 5). Molecular sieves and acid scavengers can further reduce the corrosion of flame retardant nylon (Examples 1-10 and Comparative Examples 1-4), and molecular sieves and acid scavengers have a certain synergy in reducing the electrochemical corrosion of flame retardant nylon materials (Example 6 and Comparative Examples 3-4). This may be due to the large specific surface area of ​​the molecular sieve and the H + The reaction activity is low and the specific surface area of ​​the acid scavenger is small, but it is + The high reactivity of the nylon molecule is related to the high reactivity. Furthermore, the specifications of the molecular sieve and acid scavenger significantly influence the acid absorption effect (Example 6 and Comparative Examples 1-2), demonstrating the necessity of specifying the acid scavenger and molecular sieve specifications in the present invention. The flame-retardant polyamide material prepared by the present invention exhibits excellent flame retardancy and mechanical properties, as well as low precipitation and electrochemical corrosion resistance, meeting the flame-retardant nylon requirements for applications in power batteries, connectors, low-voltage electrical switches, and other fields.

Claims

1. A low electrochemical corrosion flame retardant polyamide composition, characterized in that: It is composed of the following raw materials in parts by weight: Polyamide resin 26-89.96%; Filler 10-35%; Flame retardant 0.01-25%; Molecular sieve 0.01-5% Acid absorbent 0.01-5%; Antioxidant 0.01-1%; Processing aids 0-2%; Masterbatch 0-1%; The molecular sieve is BEA150, the acid absorber is RA150; the flame retardant is diethyl hypophosphite cage polysiloxane; whiteness>95%, moisture<0.3%, pH>4, Si content: 10-15%; P content: 25-30%, density 1.32-1.40g / cm 3 ; Particle size D 50 10-20μm; the structural formula of the flame retardant is as follows: 。 2. The low electrochemical corrosion flame retardant polyamide composition according to claim 1, characterized in that: The polyamide resin is selected from one or more of PA6T / X, PA10T, PA10T / X, PA9T, PA46, PA4T, PA5T, PA5T / X, PA6, PA56, PA66, PA6 / 66, and PA66 / 6T.

3. The low electrochemical corrosion flame retardant polyamide composition according to claim 1, characterized in that: The filler is selected from fibrous or non-fibrous fillers according to its form. The fibrous filler is selected from one or more of glass fiber, aramid fiber, carbon fiber, and basalt fiber. The non-fibrous filler is selected from one or more of whiskers, glass beads, calcium carbonate, wollastonite, mica, kaolin, and talc.

4. The low electrochemical corrosion flame retardant polyamide composition according to claim 3, characterized in that: The filler is glass fiber with an alkali content of less than 0.8% and a bulk density of 0.6-0.8 g / cm 3 , monofilament fiber diameter: 7-13μm, short cut length: 2-5mm, moisture content ≤0.05%.

5. The low electrochemical corrosion flame retardant polyamide composition according to claim 1, characterized in that: The antioxidant is a mixture of a phosphite antioxidant and a hindered phenol antioxidant in a weight ratio of 1:1, wherein the phosphite antioxidant is selected from at least one of tetrakis(2,4-di-tert-butylphenol)-4,4'-biphenyl diphosphite; tris[2,4-di-tert-butylphenyl]phosphite; 3,9-bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane; and the hindered phenol antioxidant is selected from at least one of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine; triethylene glycol ether-bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate; and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

6. The low electrochemical corrosion flame retardant polyamide composition according to claim 5, characterized in that: The hindered phenol antioxidant is N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, and the phosphite antioxidant is tetrakis(2,4-di-tert-butylphenol)-4,4'-biphenyl diphosphite.

7. The low electrochemical corrosion flame retardant polyamide composition according to claim 1, characterized in that: The processing aid is an organic additive that can take into account both internal and external lubrication and does not affect flame retardancy, and is selected from one or more of silicone powder, silicone masterbatch, PETS, montan wax, polyethylene wax, oxidized polyethylene wax, and calcium stearate.

8. The low electrochemical corrosion flame retardant polyamide composition according to claim 7, characterized in that: The processing aid is silicone powder, which is composed of phenyl silicone and silicon dioxide, and the mass ratio of phenyl silicone to silicon dioxide is 1:

1.

9. The low electrochemical corrosion flame retardant polyamide composition according to claim 1, characterized in that: The carbon black content of the masterbatch is 10-99%, and the carrier is PA6 or lubricant.

10. The method for preparing the low electrochemical corrosion flame retardant polyamide composition according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) The moisture content of polyamide resin is not higher than 2000ppm; (2) Weigh the dried raw materials according to the formula ratio; mix the polyamide resin, flame retardant, molecular sieve, acid absorber, antioxidant, processing aid, and masterbatch uniformly through a high-speed mixer and set aside; weigh the filler according to the ratio and set aside; (3) The resin and additive mixture is added through the main feed port of a twin-screw extruder, and the filler is added through the side feed port of the twin-screw extruder. After melt extrusion at 260°C, granulation, and drying, the flame retardant polyamide composition is obtained.

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