CN112574559B - High-heat-resistance halogen-free flame-retardant polyamide compound and preparation method thereof - Google Patents

Abstract

The invention provides a high heat-resistant halogen-free flame-retardant polyamide compound, which is characterized in that: the preparation method comprises the following steps of: aliphatic polyamide: 10-60 parts; aromatic polyamide: 5-30 parts; halogen-free flame retardant: 10-30 parts; phenolic resin: 1-10 parts; glass fiber: 10-50 parts; antioxidant: 0.1 to 0.5 portion; the phenolic resin is linear phenolic resin, and the molecular weight of the phenolic resin is 1000-4000g/mol. According to the high-heat-resistance halogen-free flame-retardant polyamide compound and the preparation method thereof, the halogen-free flame-retardant polyamide compound is endowed with excellent aging resistance, flame retardance and mechanical property through the synergistic effect of the phenolic resin, the antioxidant, the aromatic nylon and the halogen-free flame retardant.

Description

High-heat-resistance halogen-free flame-retardant polyamide compound and preparation method thereof

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a high heat-resistant halogen-free flame-retardant polyamide compound and a preparation method thereof.

Background

The halogen-free flame-retardant polyamide has the characteristics of excellent flame retardant property, mechanical property, heat resistance, low smoke, environmental protection and the like, and is widely applied to the fields of electronics, electricity, automobiles, aerospace, aviation and the like. At present, industries such as electronic and electric appliances, new energy and the like show development trends of high current, thin wall, miniaturization and integration, the high current, the miniaturization and the integration can cause local overhigh temperature of a workpiece, and plastic can be thermally oxidized at high temperature to cause rapid reduction of mechanical property of the workpiece, so that the functional failure of the workpiece is caused, and safety accidents can be caused under severe conditions. Therefore, it puts more severe requirements on the heat resistance of the halogen-free flame retardant polyamide. In addition, the trend of thinning the wall also requires that the halogen-free flame retardant polyamide has better flame retardant property.

At present, the main way to improve the heat resistance of polyamide is to add a heat stabilizer comprising an organic antioxidant and a copper salt, wherein the organic antioxidant is roughly divided into a hindered phenol antioxidant, an amine antioxidant and a phosphite antioxidant. The organic antioxidant has good anti-aging effect at lower temperature (below 120 ℃), but the anti-aging effect at high temperature is reduced; while copper salts still have a good heat resistance at higher temperatures, chinese patent CN99813522 discloses polyamide compositions comprising a copper salt and a halide of a strong organic base, which still show a good heat resistance at a temperature of 170 ℃. However, copper salts tend to discolor at high temperatures and are only suitable for dark products. Chinese patent CN103168076 adopts dipentaerythritol to improve the heat resistance of flame-retardant polyamide, the high-temperature heat resistance of which is much higher than that of copper salt flame-retardant polyamide materials, but the compatibility of dipentaerythritol and polyamide is poor, and the risk of precipitation exists in the long-term use process.

Disclosure of Invention

In view of the above, in order to overcome the defects in the prior art, the invention aims to provide a high heat-resistant halogen-free flame-retardant polyamide compound and a preparation method thereof, and the halogen-free flame-retardant polyamide compound is endowed with excellent aging resistance, flame retardancy and mechanical properties through the synergistic effect of multiple components of phenolic resin, antioxidant, aromatic nylon and halogen-free flame retardant.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the high heat-resistant halogen-free flame-retardant polyamide compound is prepared from the following raw materials in parts by weight:

aliphatic polyamide: 10-60 parts;

aromatic polyamide: 5-30 parts;

halogen-free flame retardant: 10-30 parts;

phenolic resin: 1-10 parts;

glass fiber: 10-50 parts;

organic antioxidant: 0.1 to 0.5 portion;

the phenolic resin is linear phenolic resin, and the molecular weight of the phenolic resin is 1000-4000g/mol.

Further, the feed is prepared from the following raw materials in parts by weight:

aliphatic polyamide: 20-50 parts;

aromatic polyamide: 10-20 parts;

halogen-free flame retardant: 15-25 parts;

phenolic resin: 3-8 parts;

glass fiber: 20-50 parts;

antioxidant: 0.1 to 0.3 portion.

Further, the aliphatic polyamide is one or a mixture of two or more of PA6, PA46, PA66, PA56, PA610, and PA612, and is preferably a PA66 resin.

The aromatic polyamide is one or a mixture of two or more of PA66/6T, PA6T/6I, PA MXD6, PA10T and PA1012/10T, preferably PA66/6T and/or PA6I/6T.

Further, the halogen-free flame retardant is compounded by 15-16 parts by weight of aluminum diethylphosphinate, 4-5 parts by weight of boehmite and 2-3 parts by weight of zinc borate.

Further, the glass fiber is any one selected from E glass fiber, H glass fiber, R, S glass fiber, D glass fiber, or C glass fiber.

Further, the glass fiber is an E glass fiber.

Further, the organic antioxidant is a hindered phenol antioxidant.

Further, the hindered phenol antioxidant is selected from the group consisting of N, N ' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine (antioxidant 1098), triethylene glycol bis [ beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ] (antioxidant 245), N-octadecyl beta- (4-hydroxy-3, 5-di-tert-butylphenyl) propionate (antioxidant 1076), pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] (antioxidant 1010), 4' -butylidenebis (6-tert-butyl-3-methylphenol) (antioxidant BBM) 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -2,4, 6-trimethylbenzene (antioxidant 1330), ethyl 2,2' -thiobis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] (antioxidant 1035), 2-oxamido bis [ ethyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) ] propionate (antioxidant 697), bis (3, 5-di-tert-butyl-4-hydroxy-phenylpropionyl) hydrazine (antioxidant 1024), 1,3, 5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione (antioxidant 1790), any of 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione (antioxidant 3114), 1,3, 5-tris (3, 5-di-tert-butyl-4-hydroxyphenylpropionyloxyethyl) isocyanurate (antioxidant 3125), 3, 9-bis [2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy ] -1, 1-dimethylethyl ] -2,4,8, 10-tetraoxaspiro [5.5] undecane (antioxidant 80).

The invention also provides a preparation method of the high heat-resistant halogen-free flame-retardant polyamide compound, which is characterized by comprising the following steps: the method comprises the following steps:

weighing aliphatic polyamide, aromatic polyamide, halogen-free flame retardant, phenolic resin, glass fiber and antioxidant according to the proportion, premixing in a high-speed mixer to obtain a premix, putting the premix into a double-screw extruder for melt mixing, and extruding and granulating.

Compared with the prior art, the high heat-resistant halogen-free flame-retardant polyamide compound has the following advantages:

1) The phenolic resin and the aromatic polyamide have a synergistic effect, and can quickly form a barrier layer on the surface of the halogen-free flame-retardant polyamide compound, prevent oxygen from entering the inside of the matrix, and keep the property of excellent physical and mechanical properties inside the halogen-free flame-retardant polyamide compound, so that the aging resistance of the compound is improved.

2) The phenolic resin and the organic antioxidant have synergistic effect; in the processing process and at a lower aging temperature, the antioxidant plays a protective role; at higher ageing temperature, the phenolic resin plays a role in protection. Phenolic hydroxyl of the phenolic resin can form hydrogen bonds with amide groups of polyamide molecular chains, and can consume oxygen or peroxide, so that the amide groups are protected from being damaged by oxidation at the molecular level, and the aging resistance of the halogen-free flame-retardant polyamide compound is improved.

3) The phenolic resin and the halogen-free flame retardant have synergistic effect, and promote the halogen-free flame retardant to rapidly form a compact carbon layer on the surface of the polymer in the combustion process.

4) The phenolic resin can be used as a compatilizer to improve the compatibility of the polyamide resin and the glass fiber, thereby improving the mechanical property of the halogen-free flame-retardant polyamide compound.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The present invention will be described in detail with reference to examples.

1. The raw materials used in the invention are as follows:

PA66, designation PA66 EP-158, huafeng group;

PA66/6T, brand C1504T, the grand boundless company of Shandong;

PA6T/6I, trade designation SELAR PA-3426NC010, duPont;

glass fiber, mark number ECS10-3.0-568H, megalithic gmbh, china;

1-phenol-formaldehyde novolac resin, molecular weight 500g/mol, shengquan group;

phenol novolac-2, molecular weight 2000g/mol, shengquan group;

linear phenolic resin-3, molecular weight 5000g/mol, shengquan group;

halogen-free flame retardant:

aluminum diethylphosphinate, grade OP1230, phosphorus content 23-24%, crainen corporation;

boehmite, brand BG-613SO, yishitong;

zinc borate, brand ZB-500, chengdu all turn on the high energy chemistry;

hindered phenolic antioxidant, brand IRGANOX1098, basf.

Copper salt antioxidant, no. 8

Dipentaerythritol, trade name charmer DP40, perstorp corporation.

2. Preparation of high heat-resistant halogen-free flame-retardant polyamide compound

Weighing the components according to the proportion, premixing in a high-speed mixer to obtain a premix, then putting the premix into a double-screw extruder for melt mixing, and extruding and granulating; wherein the length-diameter ratio of a screw of the double-screw extruder is 40-48, glass fiber is fed to the 5-6 sections of the screw, the temperature of a screw barrel is 240-300 ℃, and the rotating speed of the screw is 300rpm; according to the test requirements, the halogen-free flame-retardant polyamide composite particles are subjected to injection molding, the injection molding temperature is 280 ℃, and the injection molding pressure is 70MPa.

3. The performance test method comprises the following steps:

flame retardant property: carrying out flame retardant property test on the sample strip according to the relevant standard of UL94, wherein the thickness of the sample is 0.8mm; the flame retardant property has great significance on electrical safety, and the UL94 flame retardant grade can meet the application requirement only when reaching V-0;

aging resistance: the aging resistance test was evaluated according to the relevant rules and methods of UL 746B, with an aging temperature of 230 ℃ and ISO 527-2 1BA samples as test samples with a thickness of 0.8mm, and the time required for the tensile strength to decay to 50% of the initial performance was recorded and used as an evaluation index for aging resistance.

Tensile property: testing according to ISO 527-2 standard, wherein the tensile speed is 10mm/min;

bending property: testing according to ISO 178 standard, wherein the bending speed is 2mm/min;

izod notched impact strength: testing according to ISO 178 standard, the notch type is A type;

TABLE 1 compounding and Performance test sheet for examples 1-6

TABLE 2 compounding and Performance test Table for comparative examples 1-6

As can be seen from examples 1-6, the halogen-free flame-retardant polyamide composite has excellent mechanical properties, flame retardancy and aging resistance.

Compared with the comparative example 1, the halogen-free flame-retardant nylon is poor in aging resistance, flame retardance and mechanical property without adding phenolic resin and aromatic polyamide;

compared with the embodiment 1, the comparative example 1 and the comparative example 2, the aromatic polyamide has a certain effect on the aging resistance and the flame retardance of the halogen-free flame-retardant nylon, but the improvement is not obvious, because the aromatic polyamide has a certain barrier effect and delays the catalytic degradation of oxygen on a polyamide molecular chain, but the aromatic polyamide has a certain side effect on the mechanical property of the halogen-free flame-retardant polyamide compound;

as can be seen from example 1, comparative example 1 and comparative example 3, the phenolic resin can improve the aging resistance, the flame retardancy and the mechanical property of the halogen-free flame retardant nylon, wherein the flame retardancy and the mechanical property are obviously improved, and the aging resistance is not obviously improved; the phenolic resin can be used as a compatilizer to improve the compatibility of polyamide and glass fiber, so that the mechanical property of the compound is improved; the phenolic resin can also be cooperated with a halogen-free flame retardant, and the carbon forming speed and the carbon forming quality of the flame retardant are improved in the combustion process, so that the mechanical property of the compound is improved; phenolic hydroxyl of the phenolic resin can react with oxygen to consume and oxidize, and a polyamide molecular chain is protected from being attacked by the oxygen, so that the aging resistance of the phenolic resin is improved. But phenolic hydroxyl is a sacrificial protection mechanism, and when the phenolic hydroxyl is completely oxidized, the phenolic hydroxyl cannot play a role in protection, so that the aging resistance of the composite is improved to a limited extent;

from the example 1 and the comparative example 4, it can be seen that when the amount of the phenolic resin is too much, the mechanical properties, the flame retardant property and the aging resistance of the halogen-free flame retardant polyamide compound are greatly reduced, because the content of the phenolic resin is too much, on one hand, the phenolic resin is separated from the polyamide resin, and on the other hand, the degradation of the polyamide resin is initiated;

from example 1 and comparative example 5, it is clear that the halogen-free polyamide compound has a poor ageing resistance when the antioxidant IRGANOX1098 is not added. This is because IRGANOX1098 can protect the phenolic hydroxyl groups of the phenolic resin from premature degradation during processing or at lower aging temperatures;

as can be seen from example 1, comparative example 6 and comparative example 7, when the molecular weight of the phenolic novolac resin is too small and too large, a halogen-free flame retardant composite having high heat resistance, high strength and flame retardancy can not be obtained. When the molecular weight of the linear phenolic resin is too small, the thermal stability is low, the linear phenolic resin is easy to degrade in the processing process, and the performance of the material is deteriorated; when the molecular weight of the linear phenolic resin is too large, the influence on the mechanical property and the flame retardant property of the linear phenolic resin is not large, but the influence on the aging property of the linear phenolic resin is large. In high-temperature aging, the phenolic resin has high molecular weight and limited molecular chain motion, is not easy to migrate to the surface of a polymer and is cooperated with aromatic polyamide to generate a compact barrier layer, so that the heat resistance of the phenolic resin is greatly reduced.

As can be seen from example 1 and comparative example 8, the phenolic resin is superior to DP40 in terms of mechanical properties, flame retardancy and heat resistance. For the aging performance, on one hand, phenolic hydroxyl groups of the phenolic resin are more active than hydroxyl groups of DP40, and can be synergistic with aromatic polyamide at lower temperature to quickly form a barrier layer on the surface of the compound, and the formed barrier layer has higher strength and compactness due to the benzene ring structure of the phenolic resin; on the other hand, phenolic hydroxyl groups of the phenolic resin can consume oxygen, and form hydrogen bonds with amide groups of polyamide molecular chains, so that the amide groups are protected from being damaged by oxidation at the molecular level; in addition, the phenolic resin can be used as a compatilizer and a flame-retardant synergist to improve the mechanical property and the flame-retardant property of the halogen-free flame-retardant polyamide.

It can be seen from example 1 and comparative example 9 that the effect of copper salt on the flame retardant property and mechanical property of the halogen-free flame retardant polyamide composite is the same as that of the hindered phenol antioxidant, but the improvement of the heat resistance of the halogen-free flame retardant polyamide composite by copper salt is far lower than that of the hindered phenol antioxidant because the copper salt is mainly coordinated with amide groups of polyamide molecular chains to protect the polyamide molecular chains from being attacked by oxygen and cannot protect the phenolic resin, so that the copper salt and the phenolic resin have no synergistic effect, and the hindered phenol antioxidant has phenolic hydroxyl groups similar to that of the phenolic resin, but the phenolic hydroxyl groups of the hindered phenol are more active and can prevent the phenolic hydroxyl groups of the phenolic resin from being oxidized and damaged in advance during the processing or at a lower temperature, so the hindered phenol antioxidant and the phenolic resin have better synergistic effect.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (8)

1. A high heat-resistant halogen-free flame-retardant polyamide compound is characterized in that: the compound is prepared from the following raw materials in parts by weight:

aliphatic polyamide: 10-60 parts;

an aromatic polyamide: 5-30 parts;

halogen-free flame retardant: 10-30 parts;

phenolic resin: 1-10 parts;

glass fiber: 10-50 parts;

organic antioxidant: 0.1 to 0.5 portion;

the phenolic resin is linear phenolic resin, and the molecular weight of the linear phenolic resin is 2000-4000g/mol;

the aromatic polyamide is PA66/6T and/or PA6T/6I;

the antioxidant is hindered phenol antioxidant IRGANOX 1098.

2. The highly heat-resistant halogen-free flame-retardant polyamide compound according to claim 1, characterized in that: the compound is prepared from the following raw materials in parts by weight:

aliphatic polyamide: 20-50 parts;

aromatic polyamide: 10-20 parts;

halogen-free flame retardant: 15-25 parts;

phenolic resin: 3-8 parts;

glass fiber: 20-50 parts;

organic antioxidant: 0.1 to 0.3 portion.

3. The highly heat-resistant, halogen-free, flame-retardant polyamide composite as claimed in claim 1, characterized in that: the aliphatic polyamide is one or a mixture of more than two of PA6, PA46, PA66, PA56, PA610 and PA 612.

4. The highly heat-resistant halogen-free flame-retardant polyamide compound according to claim 1, characterized in that: the aliphatic polyamide is PA66 resin.

5. The highly heat-resistant halogen-free flame-retardant polyamide compound according to claim 1, characterized in that: the halogen-free flame retardant is compounded by (15-16) parts by weight of aluminum diethylphosphinate, 4-5 parts by weight of boehmite and (2-3) parts by weight of zinc borate.

6. The highly heat-resistant halogen-free flame-retardant polyamide compound according to claim 1, characterized in that: the glass fiber is any one selected from E glass fiber, H glass fiber, R, S glass fiber, D glass fiber or C glass fiber.

7. The highly heat-resistant halogen-free flame-retardant polyamide compound according to claim 6, characterized in that: the glass fiber is E glass fiber.

8. A method for preparing the high heat-resistant halogen-free flame-retardant polyamide compound as claimed in any one of claims 1 to 7, characterized in that: the method comprises the following steps:

weighing aliphatic polyamide, aromatic polyamide, halogen-free flame retardant, phenolic resin, glass fiber and antioxidant according to the proportion, premixing in a high-speed mixer to obtain a premix, putting the premix into a double-screw extruder for melt mixing, and extruding and granulating.