CN114436725A

CN114436725A - Gas generating agent with excellent performance and preparation method thereof

Info

Publication number: CN114436725A
Application number: CN202111248090.2A
Authority: CN
Inventors: 姚俊; 胡发灵; 彭辉; 陈淑娟; 余维维; 韩剑鹏
Original assignee: Hubei Institute of Aerospace Chemical Technology
Current assignee: Hubei Institute of Aerospace Chemical Technology
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2022-05-06
Anticipated expiration: 2041-10-26
Also published as: CN114436725B

Abstract

The invention provides a gas generating agent with excellent performance and a preparation method thereof, wherein the gas generating agent comprises the following components in percentage by mass: 25% -60% of organic fuel; 37% -72% of an oxidant; 1-10% of high molecular adhesive added with water-resistant zirconium carbonate salt, wherein the proportion is calculated by the solid content of the effective components. The improved gas generating agent component has the function of preventing and slowing down the moisture seeping into the generating agent by adding the adhesive containing the zirconium carbonate salt, thereby achieving the purposes of enhancing the moisture resistance of the gas generator and ensuring the stability of the output performance of the gas generator for a long time; meanwhile, zirconium oxide, which is a combustion product of zirconium carbonate salt, has a high melting point, and can improve filterability and reduce the amount of liquid residues sprayed out of the gas generator, thereby reducing the risk of damaging the gas bag.

Description

Gas generating agent with excellent performance and preparation method thereof

Technical Field

The invention relates to the technical field of pyrotechnic gas generants for automobile safety airbags, in particular to a gas generant with strong moisture resistance and a preparation method thereof.

Background

At present, the technology relating to the protection of motor vehicle occupants has been greatly developed, the latest generation of motor vehicles incorporate several safety systems of the airbag type in the passenger compartment, the combustion gases of pyrotechnic gas generants ensure the operation of the safety systems; among airbag-type systems, there are front airbags (for drivers or passengers) and side airbags (curtain, chest protection).

The gas generating agent prepared from an oxidizing agent represented by Basic Copper Nitrate (BCN) and strontium nitrate and an organic fuel represented by Guanidine Nitrate (GN) and 5-aminotetrazole has the main disadvantages that the raw materials and the pressed raw materials have stronger hygroscopicity, the requirement on the assembly environment is higher, and the assembly in a low-humidity environment is required. The gas generating agent is inevitably affected by the humidity of the environment when used for a long period of time. This process is slow but is time-consuming, especially now the life of a car is easily over 10 years. After the gas generating agent absorbs certain moisture, the combustion performance is affected, ignition delay is caused, even complete failure is caused in severe cases, and an expected gas output curve cannot be achieved. The high field events of japan corporation brought profound training and influence to the gas generator industry, and the stability of the combustion of the agent, particularly the long-term moisture absorption performance, must be highly valued.

The prior art also solves the problems by checking the tightness by filling helium or adding some molecular sieves as moisture absorbent inside the gas generator, but the effect is not obvious and the production cost of the generator is high.

More importantly, the air bag requires the generator to work, so that the solid residue generated is low, and the total discharge amount of the solid residue is limited. The major disadvantage of Basic Copper Nitrate (BCN) and Guanidine Nitrate (GN) formulated gas generants is the high proportion of liquid residue that is not easily filterable during combustion. This low filterability is due to the inherent disadvantage of the copper residues in liquid form in the gas generator at high combustion temperatures, which can be easily carried away by the combustion gas flow, solidified and ejected at the outlet of the gas generator. Subsequently, excessive residue generated by the gas generator easily burns the air bag. In order to reduce the influence of the residue, the complexity of the filter screen is generally increased, and the thickness and heat resistance of the air bag are increased, however, the above method increases the weight and cost of the system and is unacceptable, so that the reduction of the amount of the discharged solid residue is a continuous pursuit of the engineering personnel.

Disclosure of Invention

In order to overcome the defects in the prior art, the inventor carries out intensive research and provides a gas generating agent with excellent performance and a preparation method thereof, the improved gas generating agent component has the function of preventing and slowing down the water penetrating into the generating agent by adding a binder containing zirconium carbonate salt, thereby achieving the purposes of enhancing the moisture resistance of the gas generator and ensuring the stability of the output performance of the gas generator for a long time; meanwhile, zirconium oxide, which is a combustion product of zirconium carbonate salt, has a high melting point, and can improve filterability and reduce the amount of liquid residues sprayed out of the gas generator, thereby reducing the risk of damaging the gas bag. The zirconium carbonate is added into the formula in a liquid state, the mixing uniformity is greatly improved, and the zirconium carbonate is different from the common solid zirconium carbonate.

The technical scheme provided by the invention is as follows:

in a first aspect, a gas generating agent with excellent performance comprises the following components in percentage by mass: 25% -60% of organic fuel; 37-72% of an oxidant; 1-10% of high molecular adhesive added with water-resistant agent zirconium carbonate salt, wherein the proportion is calculated by the solid content of the effective components;

preferably, the polymer binder is selected from cellulose derivatives and salts such as cellulose, hemicellulose, modified cellulose, reduced methyl cellulose salt, cellulose acetate and the like, or at least one of polyvinyl alcohol, guar gum, starch, modified starch, styrene acetate white latex, styrene butadiene latex, nitrile butadiene latex, soy protein, acrylic acid emulsion and styrene acrylic acid copolymer emulsion, acrylic acid copolymer modified emulsion or styrene copolymer modified emulsion; when the high-molecular adhesive is in an emulsion form, the solid content is 10-60%;

preferably, the water-repellent zirconium carbonate is at least one of ammonium zirconium carbonate and potassium zirconium carbonate, and the amount of the water-repellent agent is 1-8% of the polymeric binder.

In a second aspect, a method for producing a gas generating agent having excellent properties, comprises the steps of:

step 1, weighing organic fuel and oxidant according to the designed component proportion;

step 2, weighing the high molecular adhesive added with water repellent zirconium carbonate according to the designed component proportion, and uniformly mixing the high molecular adhesive with the organic fuel and the oxidant;

and 3, adopting wet granulation, dry granulation or spray granulation to press the mixture into tablets.

The gas generating agent with excellent performance and the preparation method thereof provided by the invention have the following beneficial effects:

(1) according to the gas generating agent with excellent performance, the moisture resistance of the gas generating agent is improved by adding the adhesive containing the water-resistant agent, so that the risks of combustion and output uncertainty caused by moisture absorption of the gas generating agent in a high-humidity environment are reduced; the specific water repellent agent zirconium carbonate is selected, so that the moisture resistance is improved, the zirconium carbonate is combusted, decomposed and absorbs heat, the combustion temperature is reduced, the influence on the combustion speed is limited, the melting point of zirconium oxide serving as a combustion product of the zirconium carbonate is 2700 ℃, the melting point is higher than the formula combustion temperature, liquid is condensed in the combustion process, the filterability can be improved, the amount of liquid residues sprayed out by a gas generator is reduced, and the risk of damaging an air bag is reduced;

(2) according to the gas generating agent with excellent performance, the problems of moisture resistance and liquid residue filterability of the gas generating agent are effectively solved by adding the zirconium carbonate, the addition amount of auxiliary materials in the gas generating agent is reduced, the effective gas generating performance of the gas generating agent is stable, and the gas generating agent is improved in process operability and economic cost.

(3) The gas generating agent with excellent performance is used in a gas generator of a passive safety airbag system of an automobile, is suitable for inflating various safety airbags such as a front side airbag, a passenger side airbag, a side airbag and a curtain type airbag, and has wide applicability.

Detailed Description

The features and advantages of the present invention will become more apparent and appreciated from the following detailed description of the invention.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

According to a first aspect of the present invention, there is provided a gas generating agent with excellent performance, comprising the following components by mass: 25% -60% of organic fuel; 37% -72% of an oxidant; 1-10% of high molecular adhesive added with water-resistant zirconium carbonate salt, wherein the proportion is calculated by the solid content of the effective components.

In a preferred embodiment, the polymer binder is selected from cellulose derivatives and salts such as cellulose, hemicellulose, modified cellulose, methyl cellulose salt, cellulose acetate, or at least one of polyvinyl alcohol, guar gum, starch, modified starch, styrene-acetate white latex, styrene-butadiene latex, acrylonitrile-butadiene latex, soy protein, acrylic emulsion, styrene-acrylic copolymer emulsion, or styrene copolymer emulsion, preferably styrene-acetate white latex.

When the high molecular adhesive is in an emulsion form, the solid content is determined according to the property and the process of the formula materials and is 10-60%, and preferably 50%.

In a preferred embodiment, the water repellent zirconium carbonate salt is selected from at least one of ammonium zirconium carbonate or potassium zirconium carbonate, preferably ammonium zirconium carbonate. Further, the amount of the water repellent agent is 1 to 8 percent of the amount of the polymer adhesive, preferably 3 to 6 percent of the amount of the water repellent agent based on the solid content of the effective component.

In a preferred embodiment, the oxidizing agent comprises a primary oxidizing agent, which is basic copper nitrate. The oxidizing agent may further include a secondary oxidizing agent selected from at least one of a metal oxide, a perchlorate, a hypochlorite, or a nitrate. The metal oxides include, but are not limited to, iron oxide, copper oxide; the perchlorate salts include, but are not limited to, Ammonium Perchlorate (AP); the nitrate salts include, but are not limited to, potassium nitrate, sodium nitrate, or strontium nitrate; such hypochlorites include, but are not limited to, potassium hypochlorite, sodium hypochlorite.

In a preferred embodiment, the organic fuel is selected from at least one of 5-aminotetrazole, guanidine nitrate or nitroguanidine and derivatives thereof.

In order to optimize the process performance and combustion performance of the improved gas generating agent formula, various combustion rate catalysts, process aids, low-temperature slag bonding agents and the like can be added into the formula, and the components can also influence the calculation of oxygen balance and the formation of residues; the content of the organic fuel, the oxidant and the polymer binder added with the water repellent agent zirconium carbonate salt in the improved gas generating agent is more than 95 percent of the total mass. Because of the differences of the forming process, the design of the generator and the transfer powder of the gas generating agent, the addition of the emulsion containing organic matters as the adhesive can affect the oxygen balance of the formula, and the oxygen balance is controlled to be 3 to-5 percent, preferably-1.5 to-3.5 percent in the formula calculation. The composition of the modified gas generant formulation may be appropriately adjusted depending on the residue form and gas composition.

The improved preparation method of the gas generating agent adopts wet granulation, dry granulation or spray granulation and then is pressed into tablets; the compressed modified gas generant tablets are either mesoporous or solid, and the diameter and thickness of the tablets may be adjusted depending on the performance of the generator.

According to a second aspect of the present invention, there is provided a method for producing a gas generating agent excellent in performance, comprising the steps of:

and 3, adopting wet granulation, dry granulation or spray granulation and then pressing into tablets.

Examples

Example 1

Weighing 4.0kg of guanidine nitrate and 5.2kg of basic copper nitrate respectively; weighing 1kg of styrene acetate white latex with the solid content of 50 percent and 0.1kg of ammonium zirconium carbonate with the solid content of 30 percent, mixing the styrene acetate white latex with guanidine nitrate and basic copper nitrate, adding the mixture into 10kg of water with the temperature of 40 ℃, uniformly stirring, carrying out spray granulation and drying to obtain particles with good fluidity, pressing into circular tablets with the diameter of 5mm and the thickness of 2mm by using a rotary tablet press, drying for 4 hours at the temperature of 110 ℃ in an oven, controlling the water content of the improved gas generating agent to be less than or equal to 0.3 percent, and actually measuring the water content to be 0.23 percent. 40g of the gas generating agent was weighed and charged into a standard generator, and after the ignition of a 60L container, the sprayed residue was collected, and the weight of the residue was measured to be 0.723 g.

Example 2

4.8kg of guanidine nitrate and 5.2kg of basic copper nitrate were weighed and mixed, respectively. Weighing 2kg of polyvinyl alcohol with the solid content of 20 percent and 0.12kg of ammonium zirconium carbonate with the solid content of 20 percent, adding the polyvinyl alcohol and the ammonium zirconium carbonate into the mixed guanidine nitrate and basic copper nitrate, uniformly stirring, preparing granules with good fluidity by wet granulation, and pressing into round tablets with the diameter of 5mm and the thickness of 2mm by using a rotary tablet press to prepare the improved gas generant, wherein the water content of the improved gas generant is controlled to be less than or equal to 0.3 percent, and the actual measurement value is 0.18 percent. 40g of the gas generating agent was weighed and charged in a standard generator, and after the ignition of a 60L container, the sprayed residue was collected, and the weight of the residue was measured to be 0.632 g.

Example 3

4.8kg of guanidine nitrate and 5.2kg of basic copper nitrate were weighed and mixed dry. Weighing 1kg of modified starch solution with the solid content of 50% and 0.14kg of ammonium zirconium carbonate liquid with the solid content of 25%, mixing the modified starch solution with guanidine nitrate and basic copper nitrate, preparing granules with good fluidity through wet granulation, drying the granules in an oven for 4 hours at 110 ℃, pressing the granules into round tablets with the diameter of 5mm and the thickness of 2mm by using a rotary tablet press to prepare the improved gas generant, controlling the water content of the improved gas generant to be less than or equal to 0.3%, and measuring the water content to be 0.19%. Weighing 40g of gas generating agent, putting the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is finished, and drying to obtain 0.685g of residues.

Comparative examples 1 to 1

Weighing 4.0kg of guanidine nitrate and 5.2kg of basic copper nitrate respectively; mixing, adding into 10kg water at 40 deg.C, stirring, spray granulating, drying to obtain granules with good flowability, making into round tablet with diameter of 5mm and thickness of 2mm by rotary tablet press, and oven drying at 110 deg.C for 4 hr while controlling water content of the improved gas generating agent to be less than or equal to 0.3% and measured value to be 0.25%. Weighing 40g of gas generating agent, filling the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is completed, and drying to obtain 1.242g of residues.

Comparative examples 1 to 2

Weighing 4.0kg of guanidine nitrate and 5.2kg of basic copper nitrate respectively; weighing 1kg of styrene acetate white latex with the solid content of 50%, mixing the styrene acetate white latex with guanidine nitrate and basic copper nitrate, adding the mixture into 10kg of water with the temperature of 40 ℃, uniformly stirring, carrying out spray granulation and drying to obtain particles with good fluidity, pressing into circular tablets with the diameter of 5mm and the thickness of 2mm by using a rotary tablet press, drying for 4 hours at the temperature of 110 ℃ in an oven, and controlling the water content of the improved gas generating agent to be less than or equal to 0.3%, wherein the actual measurement value is 0.23%. Weighing 40g of gas generating agent, filling the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is completed, and drying to obtain 1.535g of residues.

Comparative example 2-1

4.8kg of guanidine nitrate and 5.2kg of basic copper nitrate were weighed and mixed, respectively. Stirring uniformly, granulating by wet method to obtain granules with good fluidity, and pressing into round tablet with diameter of 5mm and thickness of 2mm with rotary tablet press to obtain improved gas generant with water content of 0.3% or less and measured value of 0.18%. Weighing 40g of gas generating agent, filling the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is completed, and drying to obtain 1.648g of residues.

Comparative examples 2 to 2

4.8kg of guanidine nitrate and 5.2kg of basic copper nitrate were weighed and mixed, respectively. Weighing 2kg of polyvinyl alcohol with the solid content of 20%, adding the polyvinyl alcohol into the mixed guanidine nitrate and basic copper nitrate, uniformly stirring, granulating by a wet method to prepare granules with good fluidity, and pressing into circular tablets with the diameter of 5mm and the thickness of 2mm by a rotary tablet press to prepare the improved gas generant, wherein the water content of the improved gas generant is controlled to be less than or equal to 0.3%, and the actual measurement value is 0.21%. Weighing 40g of gas generating agent, filling the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is completed, and drying to obtain 1.894g of residues.

Comparative example 3-1

4.8kg of guanidine nitrate and 5.2kg of basic copper nitrate were weighed and mixed dry. After being made into granules with good fluidity by wet granulation, the granules are dried in an oven for 4 hours at 110 ℃, and round tablets with the diameter of 5mm and the thickness of 2mm are pressed by a rotary tablet press to prepare the improved gas generant, the water content of the improved gas generant is controlled to be less than or equal to 0.3 percent, and the measured value is 0.19 percent. Weighing 40g of gas generating agent, filling the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is completed, and drying to obtain 1.231g of residues.

Comparative examples 3 to 2

4.8kg of guanidine nitrate and 5.2kg of basic copper nitrate were weighed and mixed, respectively. Weighing 1kg of modified starch solution with the solid content of 50%, mixing the modified starch solution with guanidine nitrate and basic copper nitrate, preparing granules with good fluidity by wet granulation, drying the granules in an oven at 110 ℃ for 4 hours, and pressing the granules into round tablets with the diameter of 5mm and the thickness of 2mm by using a rotary tablet press to prepare the improved gas generant, wherein the water content of the improved gas generant is controlled to be less than or equal to 0.3 percent, and the measured value is 0.23 percent. Weighing 40g of gas generating agent, filling the gas generating agent into a standard generator, carefully cleaning and collecting sprayed residues after ignition of a 60L container is completed, and drying to obtain 1.758g of residues.

Moisture test of gas generant:

100g of each of the gas generants of examples and comparative examples was weighed, laid out in a pan, placed in a high humidity cabinet having a temperature of 23 ℃ 2 ℃ and a relative humidity of 70% + -5%, left for 12 hours, and then the moisture test of the gas generants was completed by dipping water on the surface of the tablets with dry cotton yarns and using a rapid moisture meter, respectively. See table 1.

TABLE 1 comparative data for tablet moisture and residue

From the above data on tablets after completion of the moisture absorption test, it is seen that the addition of the binder alone to the formulation has little effect on increasing the moisture resistance of the gas generant, but the addition of the curing agent ammonium zirconium carbonate greatly improves the moisture resistance of the gas generant, and the moisture absorption is about 50% of that of the corresponding comparative example. The improvement principle is that the polymer and ammonium zirconium carbonate on the outer surface and inside of the gas generating agent form a water repellent polymer network. The gas generating agent with strong moisture resistance can improve the environmental adaptability of the gas generator, keep the performance not to be reduced in the long-term use process and also reduce the cost for controlling the production environment. But also can greatly reduce the residue sprayed out by the gas generator, improve the performance of the gas generator and obtain a gas generating agent formula with excellent comprehensive performance.

The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are not particularly limited to the specific examples described herein.

Claims

1. The gas generating agent with excellent performance is characterized by comprising the following components in percentage by mass: 25% -60% of organic fuel; 37% -72% of an oxidant; 1-10% of high molecular adhesive added with water-resistant zirconium carbonate salt, wherein the proportion is calculated by the solid content of the effective components.

2. The gas generating agent with excellent performance according to claim 1, wherein the polymer binder is selected from cellulose derivatives and salts such as cellulose, hemicellulose, modified cellulose, reduced methyl cellulose salts, and cellulose acetate, and at least one of polyvinyl alcohol, guar gum, starch, modified starch, styrene acetate white latex, styrene butadiene latex, nitrile butadiene latex, soy protein, acrylic acid emulsion, styrene acrylic acid copolymer emulsion, acrylic acid copolymer modified emulsion, and styrene copolymer modified emulsion.

3. The gas generating agent with excellent performance as claimed in claim 2, wherein the solid content of the polymer binder is 10% to 60% when the polymer binder is in the form of emulsion.

4. The excellent gas generant of claim 1 wherein the water repellent zirconium carbonate is selected from at least one of ammonium zirconium carbonate or potassium zirconium carbonate.

5. The excellent gas generating agent according to claim 1, wherein the water repellent agent is used in an amount of 1% to 8% based on the polymer binder.

6. The excellent gas generant of claim 1 wherein the oxidizer comprises a primary oxidizer, the primary oxidizer being basic copper nitrate.

7. The excellent gas generating agent according to claim 6, wherein the oxidizing agent further comprises a secondary oxidizing agent selected from at least one of a metal oxide, a perchlorate, a hypochlorite and a nitrate.

8. The gas generating agent of claim 1, wherein the organic fuel is at least one selected from the group consisting of 5-aminotetrazole, guanidine nitrate, nitroguanidine, and derivatives thereof.

9. A preparation method of a gas generating agent with excellent performance comprises the following steps: