CN112409391A

CN112409391A - Melamine borate salt thermal polycondensate anti-dropping agent and application thereof in PA6

Info

Publication number: CN112409391A
Application number: CN202011316449.0A
Authority: CN
Inventors: 马兴良; 王斌; 梁俊兰; 万俊成; 吕润陶; 陈云峰; 后雪松; 刘霄
Original assignee: Yunnan Jianglin Group Co ltd
Current assignee: Yunnan Jianglin Group Co ltd
Priority date: 2020-11-20
Filing date: 2020-11-20
Publication date: 2021-02-26
Anticipated expiration: 2040-11-20
Also published as: CN112409391B

Abstract

The invention discloses a boric acid melamine salt thermal polycondensate anti-dropping agent and application of the anti-dropping agent in PA6 plastic. The anti-dropping agent is obtained by reacting melamine borate salt with the molar ratio of boric acid to melamine of 1.5-2.5:1 at the temperature of 400-500 ℃. The preparation process is simple and easy to realize industrialization. Compared with the anti-dropping agent commonly used at present, the anti-dropping agent has moderate addition amount in PA6, and is economical and applicable.

Description

Melamine borate salt thermal polycondensate anti-dropping agent and application thereof in PA6

Technical Field

The invention belongs to the technical field of chemical industry, and relates to a melamine borate thermal condensation polymer anti-dripping agent and application thereof in PA6 plastic.

Background

The PA has good mechanical properties such as high strength, good wear resistance and the like and excellent processability, is a material with large use amount and wide application in general engineering plastics, and is widely applied to the fields of daily consumer products and industry. Among them, PA6 has the largest yield and the most widely used, and its annual usage amount is about half or more of that of PA. However, PA6 is inherently flammable, has an LOI value of 20-21.5, and tends to produce droplets during combustion, thereby facilitating the progress of combustion. In addition, because the impact strength of PA6 is poor, glass fiber is mostly adopted for reinforcement modification in practical application, and the glass fiber is easier to burn due to the candle wick effect in the burning process, and the dripping phenomenon is aggravated accordingly. Although the generation of molten drops is beneficial to taking away heat generated during the combustion of the polymer so as to realize a certain flame retardant effect, due to the fact that the temperature of molten drops is high, other substances are easy to ignite after the molten drops are dropped, and further expansion of fire is caused, and therefore flame retardance and molten drop resistance of PA6 are greatly concerned.

The current general practice is to add polytetrafluoroethylene and phyllosilicate materials: such as montmorillonite, talc, mica, etc., carbon-based materials: such as graphene, graphite powder, carbon nanotubes and the like, and boron nitride and the like, to improve the combustion droplet performance of the PA6.

Polytetrafluoroethylene is the most widely accepted and used anti-dripping agent at present, and the action mechanism of the anti-dripping agent is that the fluidity of a melt is reduced by increasing the viscosity of a polymer during combustion, so that the effect of reducing the dripping is achieved. The literature "liuyuan, royal jelly, melamine cyanuric acid flame retardant nylon 6 anti-drip flammability research [ J ] engineering plastics application 2005,33 (11): 48-50 "analyzed the effect of polytetrafluoroethylene on melamine cyanurate flame retardant nylon 6, demonstrating that the presence of polytetrafluoroethylene reduced the number of droplets of MCA flame retardant nylon 6. However, polytetrafluoroethylene has the disadvantages of poor dispersibility, poor compatibility and the like when used as an anti-dripping agent. And when the polytetrafluoroethylene is used as the anti-melting agent, the polytetrafluoroethylene is generally added into the polymer in a micro powder mode, and the preparation process of the micro powder is difficult and the price is high. The use of polytetrafluoroethylene as an anti-dripping agent in large quantities is therefore greatly restricted.

The use of phyllosilicates as anti-dripping agents has also been reported in the literature. The literature "Xiangyang Hao, Guosheng Gai, et al, flame recovery and anti effect of OMT/PA nanocomposites [ J ]. Materials Chemistry and Physics.2006,96: 34-41" mentions that the OMT/PA6 system does not produce droplets on combustion when the amount of organically modified montmorillonite added is 5%. The document Zhou Xiu Miao, Hu Fang, Li Meng, amino silicone oil and montmorillonite cooperated flame retardant nylon 6[ J ] plastics 2011,40 (3): 31-32 proposes that when the addition amount of montmorillonite is below 5%, the polymer has slight molten drops, and when the addition amount is 7% or 10%, the molten drops are not obvious or no molten drops. Although the sheet silicate has the anti-dripping performance, the addition amount of the sheet silicate is relatively high, so that the mechanical property of the material is influenced to a certain extent.

With the intensive research on the anti-droplet application, the anti-droplet performance of the carbon-based material is fully demonstrated. Chinese patent CN106810830 proposes that graphene, graphite oxide and graphite powder are used as an anti-dripping agent, and are blended and extruded with a flame retardant, a dispersing agent and a plastic substrate (PET, PBT, PTT, PA6 or PA 66) to prepare a flame-retardant anti-dripping master batch; chinese patent CN103923348A mentions that graphene has a significant anti-dripping effect as an anti-dripping agent for thermoplastics such as polyamide, polypropylene, polyethylene, etc. However, the use of carbon-based materials as anti-drip agents increases the electrical conductivity of the finished product, and the color problems inherent in carbon-based materials limit their use as anti-drip agents. In addition, the carbon-based material is relatively expensive, which also limits its large application as an anti-dropping agent.

In The literature, "Yuhua Zhong, Luchong Zhang, et al, The effect OF hBN on The flame retardance and The thermal stability OF P-N flame retardant PA6. JOURNAL OF MACROMOCULAR SCIENCE-PART A: PURE AND APPLIED CHEMISTRY.2018,55(1): 17-23" hexagonal boron nitride is mentioned as an anti-dripping agent for PA6, and The dripping phenomenon completely disappears during The combustion OF PA6 splines when The boron nitride is added in amounts OF 3% and 5%. However, boron nitride is complicated to manufacture and relatively expensive, which limits its use in large quantities as an anti-dripping agent.

The red phosphorus flame retardant is a flame retardant variety which achieves the same flame retardant effect and is added with the least amount in the currently known additive flame retardants. Because the addition amount of the flame retardant is small, the high flame retardant property and the extremely low smoke generation amount of the polymer material can be met, and simultaneously, the good mechanical property and the good electrical property of the polymer material can be maintained. Therefore, the flame retardant is widely applied to the flame retardance of polymers containing oxygen or nitrogen, such as polyamide and polyester. However, when the flame retardant is applied to PA6, the plastic product generates serious molten drop phenomenon during combustion, and the application range of the plastic product is limited. The addition of the anti-dripping agent is favorable for improving the dripping phenomenon of the PA6 plastic product during combustion, thereby improving the flame retardant property of the product and being favorable for the popularization and application of the product in various fields.

Disclosure of Invention

Aiming at the defects of the anti-dropping agent, the invention provides the anti-dropping agent which has moderate addition amount, simple preparation, economy and applicability and application thereof in PA6 plastic.

The invention is realized by the following technical scheme: the melamine borate salt with the molar ratio of the boric acid to the melamine of 1.5-2.5:1 is placed in an environment with the temperature of 400-500 ℃ for reaction for 20-30 minutes, cooled to room temperature and crushed to obtain the finished product of the melamine borate salt condensation polymer anti-dripping agent with the bulk density of 0.25-0.4 g/ml.

In the present invention, the following reaction may occur in the melamine borate salt under the reaction temperature condition:

(1) dehydration of the boronic acid group:

in the formula: x =1-3

(2) Boroacylation:

(3) condensation polymerization of melamine groups:

in the above formula: x =1-3

In the invention, the melamine borate is put into an environment of 400-500 ℃, the steam and ammonia gas generated by the reaction quickly overflow, so that the material is expanded to form a large number of micropores in the material, thus obtaining a spongy material with high porosity, and the bulk density of the finished product obtained by crushing is 0.25-0.4 g/ml. The existence of the microporous structure effectively improves the rheological property of the melt of the polymer during combustion, and further shows a better anti-dripping effect. If the temperature is slowly increased in the process, the gas generated by the condensation polymerization reaction of the melamine borate overflows slowly, the finished product has small void ratio, increased bulk density and weaker anti-droplet effect.

In the invention, the optimal bulk density of the anti-dripping agent of the boric acid melamine salt heat polycondensate is 0.25-0.4 g/ml, the bulk density is higher, the void ratio is reduced, and the anti-dripping effect is not good.

In the invention, the molar ratio of boric acid to melamine is 1.5-2.5:1, and the finished product obtained by excessively high or excessively low ratio has higher bulk density and weaker anti-dripping effect.

In the invention, the reaction temperature is 400-500 ℃, and the reaction time is 20-30 minutes. Low temperature, short reaction time, small finished product void ratio, high bulk density and poor anti-dripping effect. Meanwhile, incomplete reaction is easily caused, and bubbles may be generated in the processing process of the polymer, so that certain negative effects are caused on the performance of the polymer product. The temperature is too high, the time is long, and the product further generates polycondensation reaction, so that the porosity of the finished product is reduced, the bulk density is increased, and the anti-dripping effect of the finished product is reduced. Within the temperature range of the present invention, when the reaction temperature is higher, the reaction time is preferably low, and when the reaction temperature is lower, the reaction time is preferably high.

The invention also provides application of the boric acid melamine salt thermal condensation polymer anti-dripping agent in PA6 plastic, wherein the weight percentages of the materials are as follows: a) 2.5-3% of the melamine borate salt thermal polycondensation anti-dripping agent; b) 6-8% of microencapsulated red phosphorus flame retardant; c) 89-91.5% of PA6 plastic.

The melamine borate thermal polycondensate anti-dripping agent has simple preparation process and easy realization of industrialization. The anti-dripping agent can effectively improve the burning dripping phenomenon when being applied to PA6 plastic. Compared with the anti-dripping agent commonly used at present, the anti-dripping agent has moderate addition amount, and is economical and applicable.

Detailed Description

The invention is described in detail by the following specific embodiments, and the specific detailed description of the embodiments is only an example within the scope defined in the claims, and is only used for specific examples, and does not represent the full scope of the claims.

Preparation of melamine borate salt: the method is carried out in a 5L stainless steel kneader, the kneader is heated or cooled by heat conducting oil in a jacket, the heat conducting oil is heated by electricity, and the cooling is carried out by water cooling. And an internal material temperature detection display instrument is arranged on the side part of the kneading machine.

All examples were carried out in a constant temperature oven, oven temperature range: normal temperature-550 ℃.

The raw materials used in all examples were as follows:

melamine, Sichuan Meifeng chemical Co., Ltd., the content is not less than 99.8%.

Boric acid: h from Liaoning Wide Dian autonomous county Zhihua chemical Co., Ltd₃BO₃The content is more than or equal to 99.4 percent.

Microencapsulated red phosphorus-coated flame retardant: yunnan Jiang phosphorus group GmbH, red phosphorus content: 75. + -. 0.5% average particle diameter (D)₅₀): 10 + -0.5 micron.

PA 6: dupont, designation 1030B.

Test methods for the final products obtained in the examples:

bulk density: a 100 ml measuring cylinder of known weight is filled with 100 ml of material and weighed, the weight of the measuring cylinder is subtracted from the value obtained, the weight of the 100 ml material is obtained, and the weight is divided by 100, so that the bulk density of the material is obtained.

Flame-retardant anti-dripping test:

the flame retardant grade of the sample is judged by adopting a UL94 vertical combustion measuring method in a UL94 horizontal vertical combustion experimental instrument to measure the combustion performance of PA6 sample pieces with different anti-dropping agent adding amounts and according to the results of the combustion time of the sample, whether the sample is dropped, whether the dropping agent ignites absorbent cotton and the like.

Preparation of raw material melamine borate salt:

adding melamine, boric acid and water into a kneader according to the amount determined in the table 1, heating to the material temperature of 75 ℃, reacting for 120 minutes under the temperature condition, heating the material to 110 ℃, and evaporating to dryness to obtain melamine borate salt powder.

TABLE 1 Melamine borate preparation Material ratio

Examples 1 to 3

And flatly paving the No. 2, No. 3 and No. 4 boric acid melamine salt in a stainless steel plate, wherein the thickness of the material is less than or equal to 1/3 of the depth of the plate. And (3) quickly putting the stainless steel plate filled with the materials into a constant-temperature oven which is preheated to the temperature shown in the table 2, reacting for the time shown in the table 2, taking out, naturally cooling to room temperature, and crushing to obtain the finished product of the anti-dropping agent. The final bulk densities are listed in table 2.

Comparative examples 1 to 2

The 1# and 5# melamine borate is paved in a stainless steel plate, and the thickness of the material is less than or equal to 1/3 of the depth of the plate. And (3) quickly putting the stainless steel plate filled with the materials into a constant-temperature oven which is preheated to the temperature shown in the table 2, reacting for the time shown in the table 2, taking out, naturally cooling to room temperature, and crushing to obtain a finished product. The final bulk densities are listed in table 2.

Comparative examples 3 to 6

The 3# melamine borate is paved in a stainless steel plate, and the thickness of the material is less than or equal to 1/3 of the depth of the plate. And (3) quickly putting the stainless steel plate filled with the materials into a constant-temperature oven which is preheated to the temperature shown in the table 2, reacting for the time shown in the table 2, taking out, naturally cooling to room temperature, and crushing to obtain the finished product of the anti-dropping agent. The final bulk densities are listed in table 2.

TABLE 2 preparation conditions of anti-dripping agents and their bulk densities

Comparative example 7

The 3# melamine borate is spread in a stainless steel plate, and the thickness of the material is less than or equal to 1/3 of the depth of the plate. And (3) quickly putting the stainless steel plate filled with the materials into an oven preheated to 300 ℃, then heating the oven to 450 ℃ within 15 minutes, carrying out heat preservation reaction for 25 minutes, taking out, naturally cooling to room temperature, and crushing to obtain the finished product of the anti-dropping agent. Its bulk density was 0.45 g/ml.

And (3) testing the anti-dripping flame retardant property:

the finished products obtained in the above examples and comparative examples are fully and uniformly mixed with microencapsulated red phosphorus and PA6 according to the proportion determined in Table 3, and then are subjected to blending extrusion, granulation and drying by a TSH35B twin-screw extruder, and injection molding by a UN120SK injection molding machine to obtain sample pieces with the length of 130 mm, the width of 13 mm and the thickness of 1.6 mm. The test pieces were subjected to a flame retardant anti-dripping test using a UL94 vertical burning test method, and the results are shown in Table 3.

Comparative test, test pieces were prepared in the above-described manner with the amounts of PA6 and red phosphorus flame retardant determined in Table 3 without adding an anti-dripping agent during the preparation of the pieces, and subjected to a flame-retardant anti-dripping test, the results of which are shown in Table 3.

Table 3 red phosphorus flame retardant PA6 UL94 vertical burn test with anti-drip agent added

From the above results, it can be seen that: firstly, when the bulk density of the boric acid melamine salt thermal polycondensate is 0.25-0.4 g/ml, the boric acid melamine salt thermal polycondensate has better anti-dripping property in PA 6; as the bulk density increases, the anti-drip effect decreases.

Secondly, in terms of material proportion, when the molar ratio of boric acid to melamine in the melamine borate salt is 1.5-2.5:1, the bulk density of the melamine borate salt thermal condensation polymer obtained under the process condition of the invention is 0.25-0.4 g/ml, and when the addition amount of the melamine borate salt thermal condensation polymer in the microencapsulated red phosphorus-coated flame-retardant PA6 is 2.5-3%, the good anti-dripping effect can be achieved, and the flame-retardant grade of the PA6 plastic product is high. And when the molar ratio of boric acid to melamine is greater than 2.5:1 or less than 1.5:1, the boric acid melamine salt thermal polycondensate has higher bulk density, a large amount of molten drops are generated when the addition amount of the boric acid melamine salt thermal polycondensate in the microencapsulated red phosphorus coated flame-retardant PA6 is 3%, the anti-molten drop effect is poor, and the flame-retardant grade of a PA6 plastic product is low.

③ the anti-dripping effect of the boric acid melamine salt thermal polycondensate is closely related to the heating rate, the bulk density of the obtained thermal polycondensate is high when the heating rate is too slow, and the anti-dripping effect of the thermal polycondensate in the microencapsulated red phosphorus-coated flame-retardant PA6 is poor.

And the boric acid melamine salt thermal polycondensate has higher degree of correlation between the anti-molten drop effect and the reaction temperature and the reaction time, the temperature is lower than 400 ℃ or higher than 500 ℃, the bulk density of the obtained thermal polycondensate is higher, and the anti-molten drop effect in the microencapsulated red phosphorus coated flame-retardant PA6 is poorer.

And fifthly, the anti-dripping effect of the boric acid melamine salt thermal condensation polymer is related to the reaction time, and when the reaction time is less than 20 minutes or more than 30 minutes, the bulk density of the obtained thermal condensation polymer is relatively high, and the anti-dripping effect is weak.

Claims

1. The anti-dropping agent of the boric acid melamine salt heat polycondensate is characterized in that the bulk density of the anti-dropping agent is 0.25 to 0.4 g/ml; the anti-dripping agent is prepared by the following method:

the melamine borate salt with the molar ratio of the boric acid to the melamine of 1.5-2.5:1 is placed in an environment with the temperature of 400-500 ℃ for reaction for 20-30 minutes, cooled to room temperature and crushed, and the melamine borate salt thermal polycondensation anti-dropping agent is obtained.

2. The use of the boric acid melamine salt thermal polycondensate anti-dripping agent as defined in claim 1 in PA6, wherein the following are used in percentage by weight:

a) 2.5-3% of the melamine borate salt thermal polycondensation anti-dripping agent;

b) 6-8% of microencapsulated red phosphorus-coated flame retardant;

c) 89-91.5% of PA6 plastic.