CN112409391B

CN112409391B - Melamine borate salt thermal polycondensate anti-dripping agent and application thereof in PA6

Info

Publication number: CN112409391B
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: 2023-06-06
Anticipated expiration: 2040-11-20
Also published as: CN112409391A

Abstract

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

Description

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

Technical Field

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

Background

PA has good mechanical properties such as high strength, good wear resistance and good processing property, is a material with large use amount and the widest application in general engineering plastics, and is widely applied to the fields of daily consumer goods and industry. Among them, the PA6 yield is the largest, the application is the most widely, and the annual usage of the PA is more than half of the annual usage of the PA. However, PA6 is flammable, LOI value is 20-21.5, and molten drops are easy to generate in the combustion process, so that the combustion is promoted. In addition, because PA6 has poor impact strength, glass fiber is mostly adopted for reinforcement modification in practical application, and because of the 'candlewick effect' of the glass fiber in the combustion process, the combustion is easier, and the molten drop phenomenon is aggravated. Although the generation of the molten drops is favorable for taking away the heat generated when the polymer burns so as to realize a certain flame-retardant effect, other substances are easy to cause ignition after the molten drops are dropped due to higher temperature of the molten drops, and further expansion of fire is caused, so that the flame retardance and the molten drop resistance of the PA6 are greatly concerned.

The current common practice is to add polytetrafluoroethylene and layered silicate substances: such as montmorillonite, talc, mica, etc., carbon-based materials: substances such as graphene, graphite powder, carbon nanotubes and the like, boron nitride and the like are used for improving the combustion droplet performance of PA6.

Polytetrafluoroethylene is currently accepted and most widely used as an anti-dripping agent, and the action mechanism is to reduce the fluidity of a melt by increasing the viscosity of a polymer during combustion so as to achieve the effect of reducing dripping. Document "Liu Yuan, wang Qi. Research on anti-droplet flammability of melamine cyanurate flame retardant nylon 6[ 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 defects of poor dispersibility, poor compatibility and the like when being used as an anti-dripping agent. And polytetrafluoroethylene is generally added into the polymer in a micro powder mode when the polytetrafluoroethylene is used as an anti-dripping agent, and the micro powder is difficult in preparation process and high in price. Thus, the use of polytetrafluoroethylene as an anti-drip agent is greatly limited in its large number.

The use of layered silicates as anti-drip agents is also reported in a large number of documents. The literature "Xiangyang Hao, guosheng Gai, et al flame retardancy and antidripping effect ofOMT/PA nanocomposites [ J ]. Materials Chemistry and Physics 2006,96:34-41" mentions that when the addition of organically modified montmorillonite is 5%, no droplets are produced on combustion of the OMT/PA6 system. The literature Zhou Xiumiao, hu Guosheng, li Meng, amino silicone oil and montmorillonite cooperate with flame retardant nylon 6[J. Plastic 2011,40 (3): 31-32 "suggests that the polymer has slight or insignificant or no dripping when the montmorillonite is added below 5% and at 7 or 10% of the amount. Although the sheet silicate has anti-dripping performance, the addition amount of the sheet silicate is relatively high, so that the mechanical properties of the material are negatively affected to a certain extent.

With the deep research of anti-dripping application, the anti-dripping performance of the carbon-based material is fully exhibited. Chinese patent CN106810830 proposes that graphene, graphite oxide, and graphite powder are used as anti-dripping agents, and are mixed with flame retardant, dispersant, and plastic matrix (PET, PBT, PTT, PA or PA 66) for extrusion to prepare flame retardant anti-dripping master batch; chinese patent CN103923348A mentions that graphene has a remarkable anti-dripping effect as an anti-dripping agent for thermoplastic plastics 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 inherent color problems of carbon-based materials limit its use as an anti-drip agent. In addition, carbon-based materials are relatively expensive, which also limits their use in large amounts as anti-drip agents.

In the document "Yuhua Zhong, luchongZhang, et al The effect of hBN on the flame retardancy and thermal stability of P-N flame retardant PA6. JOURNAL OFMACROMOLECULAR SCIENCE- -PART A: PURE AND APPLIED CHEMISTRY.2018,55 (1): 17-23", hexagonal boron nitride was mentioned as an anti-dripping agent for PA6, and the dripping phenomenon completely disappeared during the combustion of the PA6 bars when the boron nitride addition was 3% and 5%. However, boron nitride is a complex manufacturing process and is relatively expensive, which limits its use in large quantities as an anti-drip agent.

The red phosphorus flame retardant is a flame retardant variety with the least addition amount for achieving the same flame retardant effect in the currently known additive flame retardants. Because of the small addition amount, the high flame retardant property and extremely low smoke generation amount of the polymer material can be met, and meanwhile, the good mechanical property and electrical property of the polymer material can be maintained. It is widely used for flame retardance of polymers containing oxygen or nitrogen themselves, such as polyamides, polyesters, etc. However, when the flame retardant is applied to PA6, the plastic product generates serious molten drop phenomenon when being burnt, and the application range of the plastic product is limited. The addition of the anti-dripping agent is beneficial to improving the dripping phenomenon of the PA6 plastic product during burning, thereby improving the flame retardant property of the product and being beneficial to popularization and application in various fields.

Disclosure of Invention

Aiming at the defects of the anti-dripping agent, the invention aims to provide the anti-dripping agent which has moderate addition amount, simple preparation, economy and applicability and the application thereof in PA6 plastics.

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

In the present invention, the melamine borate salt may react under the reaction temperature conditions as follows:

(1) Dehydration of the boric acid groups occurs:

wherein: x=1-3

(2) Boration:

(3) Condensation polymerization of melamine groups:

in the above formula: x=1-3

In the invention, the melamine borate salt is put into the environment of 400-500 ℃, the steam and ammonia generated by the reaction quickly overflow, so that the material is puffed, a large number of micropores are formed in the material, the sponge-like material with high void ratio is obtained, and the bulk density of the finished product obtained by crushing is 0.25-0.4 g/ml. The existence of the micropore structure effectively improves the rheological property of the melt when the polymer burns, and further shows better anti-dripping effect. If the temperature is slowly increased in the process, the gas generated by the polycondensation reaction of the melamine borate has low overflow speed, small void ratio of the finished product, increased bulk density and weaker anti-dripping effect.

In the invention, the optimal bulk density of the melamine borate thermal polycondensate anti-dripping agent is between 0.25 and 0.4 g/ml, the bulk density is higher, the void ratio is reduced, and the anti-dripping effect is poor.

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

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

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

The melamine borate salt thermal polycondensate anti-dripping agent has simple preparation process and is easy to realize industrialization. The anti-dripping agent can effectively improve the burning and dripping phenomena when being applied to PA6 plastics. Compared with the anti-dripping agent commonly used at present, the anti-dripping agent has moderate adding amount and is economical and applicable.

Detailed Description

The present invention is described in detail by the following detailed description, and examples given are only examples within the scope defined in the claims, and are intended to be illustrative only and not to be construed as limiting the scope of the claims.

Preparation of melamine borate salt: the heating and cooling of the kneader are carried out in a 5-liter stainless steel kneader, the inside of the jacket is heated or cooled by heat conducting oil, the heat conducting oil is heated by electricity, and the cooling is cooled by water. The side of the kneader is provided with an internal material temperature detection display instrument.

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

The raw materials used in all examples were as follows:

melamine, sichuan Meifeng chemical Co., ltd, content is more than or equal to 99.8%.

Boric acid: liaoning Wide Dian Manchurian county Zhimanhua chemical Co., ltd, H ₃ BO ₃ The content is more than or equal to 99.4 percent.

Microencapsulated coated red phosphorus flame retardant: yunnan river phosphorus group Co., ltd., red phosphorus content: 75.+ -. 0.5%, average particle diameter (D ₅₀ ): 10 plus or minus 0.5 microns.

PA6: dupont, trade name 1030B.

The final product test method obtained in the examples:

bulk density: 100 milliliters of material is filled into a 100 milliliter measuring cylinder with known weight, the measuring cylinder weight is subtracted from the obtained value, the weight of the 100 milliliters of 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:

and (3) determining the combustion performance of the PA6 sample pieces with different addition amounts of the anti-dripping agent by adopting a UL94 vertical combustion determination method in a UL94 horizontal vertical combustion experimental instrument, and judging the flame retardant grade of the sample according to the results of the sample combustion time, whether the dripping is caused to ignite absorbent cotton and the like.

Preparing raw material melamine borate:

melamine, boric acid and water were added to a kneader in the amounts specified in table 1, and the temperature was raised to 75 ℃ for 120 minutes at which temperature the material was raised to 110 ℃ and the water was evaporated to dryness to give melamine borate powder.

Table 1 material ratios for the preparation of melamine borate salts

Examples 1 to 3

And (3) paving the 2# boric acid melamine salt, the 3# boric acid melamine salt and the 4# boric acid melamine salt in a stainless steel disc, wherein the thickness of the material is less than or equal to 1/3 of the depth of the disc. And (3) quickly placing the stainless steel plate with the materials into a constant temperature oven 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 anti-dripping agent finished product. The final bulk densities are listed in table 2.

Comparative examples 1 to 2

The No. 1 and No. 5 boric acid melamine salts are paved in a stainless steel disc, and the thickness of the materials is less than or equal to 1/3 of the depth of the disc. And (3) quickly placing the stainless steel plate with the materials into a constant temperature oven 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 No. 3 boric acid melamine salt is paved in a stainless steel disc, and the thickness of the material is less than or equal to 1/3 of the depth of the disc. And (3) quickly placing the stainless steel plate with the materials into a constant temperature oven 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 anti-dripping agent finished product. The final bulk densities are listed in table 2.

TABLE 2 preparation conditions of anti-dripping agent and bulk Density thereof

Comparative example 7

The No. 3 boric acid melamine salt is paved in a stainless steel disc, and the thickness of the material is less than or equal to 1/3 of the depth of the disc. And (3) quickly placing the stainless steel plate with the materials into a baking oven preheated to 300 ℃, then heating the baking oven to 450 ℃ within 15 minutes, preserving heat for reaction for 25 minutes, taking out, naturally cooling to room temperature, and crushing to obtain the anti-dripping agent finished product. The bulk density was 0.45 g/ml.

Testing of anti-dripping flame retardant property:

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

Comparative test no anti-drip agent was added during the preparation of the sample, and the test sample was prepared as described above with PA6 and red phosphorus flame retardant in the amounts determined in Table 3, and flame retardant anti-drip test was performed, and the results are shown in Table 3.

TABLE 3 Red phosphorus flame retardant PA6 UL94 vertical burn test with anti-drip agent

From the above results, it can be seen that: (1) when the bulk density of the melamine borate thermal polycondensate is 0.25-0.4 g/ml, the melamine borate thermal polycondensate has better anti-dripping property in PA 6; as the bulk density increases, the anti-dripping effect decreases.

(2) 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 polycondensate obtained under the process condition of the invention is 0.25-0.4 g/ml, the good anti-dripping effect can be achieved when the adding amount of the melamine borate salt thermal polycondensate in the microencapsulated coated red phosphorus flame-retardant PA6 is 2.5-3%, 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: when the ratio of the melamine borate to the thermal polycondensate is 1.5:1 or less, the bulk density of the melamine borate thermal polycondensate is higher, a large amount of molten drops are generated when the addition amount of the melamine borate thermal polycondensate is 3% in the microencapsulated coated red phosphorus flame-retardant PA6, the anti-molten drop effect is poor, and the flame-retardant grade of the PA6 plastic product is low.

(3) The anti-dripping effect of the melamine borate salt thermal polycondensate is closely related to the temperature rising rate, and the obtained thermal polycondensate with the too slow temperature rising rate has high bulk density and poor anti-dripping effect in the microencapsulated coated red phosphorus flame-retardant PA6.

(4) The anti-dripping effect of the melamine borate salt thermal polycondensate has higher correlation degree with 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-dripping effect in the microencapsulated coated red phosphorus flame-retardant PA6 is poorer.

(5) The anti-dripping effect of the melamine borate salt thermal polycondensate is also related to the reaction time, and when the reaction time is lower than 20 minutes or higher than 30 minutes, the obtained thermal polycondensate has relatively high bulk density and weak anti-dripping effect.

Claims

1. The application of the melamine borate salt thermal polycondensate anti-dripping agent in PA6 is characterized in that the bulk density of the melamine borate salt thermal polycondensate anti-dripping agent is 0.25-0.4 g/ml;

the melamine borate salt thermal polycondensate anti-dripping agent is prepared by the following method: placing melamine borate salt with the molar ratio of boric acid to melamine of 1.5-2.5:1 in the environment of 400-500 ℃, reacting for 20-30 minutes, cooling to room temperature, and crushing to obtain the melamine borate salt thermal polycondensate anti-dripping agent;

the melamine borate salt thermal polycondensate anti-drip agent is applied after a microencapsulated coated red phosphorus flame retardant is mixed with PA6, and the weight percentages of the materials are as follows:

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

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

c) 89-91.5% of PA6 plastic.