CN100567576C - Method for producing cathode of oxygen generator by dry pressing method - Google Patents

Abstract

The invention proposes a method for producing the cathode of an oxygen generator by dry pressing, which belongs to the technology of taking oxygen from the cathode of an electrochemical oxygen production unit and ion membrane in water. Phosphorus flake graphite and foaming agent and other auxiliary materials are added, and the cathode of the oxygen making unit is produced according to the steps of metering and batching, stirring and mixing, dry pressing into the mold and roasting and shaping. It has excellent air permeability and waterproof performance and good low resistance performance. Advantages, compared with the "wet rolling" method, the dry pressing forming technology proposed by the present invention significantly improves the process operability of the copper mesh electrode lead embedded in the cathode. It has simple process, convenient operation and high operating efficiency. , the production cost is low, and the cathode produced by the dry pressure method is equipped with the oxygen generator, which can significantly improve the oxygen production and work stability, and has a good effect on improving and improving the product quality of the oxygen generator. Promoting prospects for use.

Description

Method for producing cathode of oxygen generator by dry pressing method

Technical field:

The invention relates to the production technology of oxygen-generating electrode materials, and belongs to the technical field of cathode materials of electrochemical ion membrane oxygen-generating units and ion membrane oxygen extraction in water, and specifically relates to a method for producing cathodes of oxygen generators by dry pressing.

Background technique:

We know that existing home medical oxygen generators are generally divided into two methods: physical oxygen generation and chemical oxygen generation. Physical oxygen generation uses polymer sieve pressure swing adsorption separation technology to separate nitrogen and oxygen from the air medium to produce oxygen for absorption. Although physical oxygen generators have the advantages of rich oxygen resources, sufficient oxygen production and stable oxygen delivery, but Due to the shortcomings of physical oxygen generators such as complex structure, loud compressor operation noise, high production cost, and high price, it is difficult for ordinary families to accept it. The chemical oxygen generator, especially the family medical oxygen generator that adopts the cathode of the electrochemical ion membrane oxygen generator unit to extract oxygen from the ion membrane in water, has the advantages of small size, light weight, low price, rapid oxygen production, high oxygen delivery efficiency, and easy operation. Easy to use and other advantages, favored by the majority of users. There is no doubt that the cathode of the electrochemical ion membrane oxygen generator unit is the key core technology of the chemical oxygen generator, and the quality of the cathode material of the ion membrane oxygen generator unit will directly affect the working performance of the oxygen generator. In general: the cathode material of the oxygen generating unit is required to have low resistance and excellent waterproof and breathable performance, and the cathode is also required to have good mechanical strength and external dimension stability, and have good process operation in the production process It is easy to assemble electrode leads and ensure the firmness and reliability of electrode leads, and has long-term stable working performance during use. The existing method for producing the cathode of an oxygen generator is that the raw materials are fully stirred into a mud, then repeatedly rolled on a double-roll mill, and then roasted and shaped. The cathode products produced by this "wet rolling-roasting and shaping" method have the following defects: the process operation performance of the copper mesh electrode lead wire of the finished cathode product on the twin-roll rolling mill is poor, and the production efficiency is low , especially in the process of roasting and shaping, a large amount of liquid medium will evaporate in the muddy material, which not only affects the stability of the outer dimension of the finished cathode, but also buries bubbles and even hidden cracks in the finished cathode. It affects the mechanical strength and waterproof and breathable performance of the finished cathode. In actual use, it is manifested in the poor reliability of the electrode lead, which is prone to layered water permeability, resulting in a decrease in the electrical conductivity of the cathode, which will inevitably affect the working efficiency of the oxygen generator. This is a fatal technical defect that is difficult to overcome for the cathode products produced by the wet rolling method at present. This is also the problem to be solved by the present invention.

Invention content:

The purpose of the present invention aims at the technical defect that wet rolling cathode product exists, proposes a kind of method that produces oxygen generator cathode by dry pressing method, and it is the further improvement to existing oxygen generator unit cathode material and its production method and perfect.

The method that the present invention proposes produces the cathode of oxygen generator with dry pressing method, and it is base-material with polytetrafluoroethylene powder and carbon black, it is characterized in that: it carries out according to the following steps successively:

(1) Measuring ingredients: measure and prepare the base material according to the following weight ratio

PTFE powder 1 part

Carbon black 0.35～0.45 parts

Control base material: the particle size of polytetrafluoroethylene powder is less than or equal to 1000 microns,

The particle size of carbon black is less than or equal to 1000 microns,

Add graphite according to 2.5-5.0% of the total weight of the base material, and control the particle size of the graphite to ≤200 mesh,

Add foaming agent according to 3.5-5.0% of the total weight of the base material,

The graphite mentioned above is a phosphorus flake graphite product with low resistance and high conductivity.

Phosphorus flake graphite: particle size ≤ 200 mesh, carbon content ≥ 99%, volatile matter content ≤ 0.25%, the choice of phosphorus flake graphite material has obvious effects on reducing cathode resistance and improving cathode conductivity.

The blowing agent mentioned above is to select commercially available trade mark produced by Ningxia Risheng Industrial Co., Ltd. as ADC type blowing agent.

(2) Stir and mix: put the material weighed in the step (1) into the batching mixer and stir and mix to obtain the mix.

The stirring and mixing means that the stirring speed of the mixer is 1000-1500 rpm, and the continuous stirring time is 5-10 minutes. When the stirred material appears in the form of cotton fibers, the qualified mixed material, making it easy to enter the mold for dry pressing.

(3) Molding and dry pressing: adding the mixed material prepared in step (2) into the pressing mold for dry pressing to obtain a formed cathode, the control pressure is: 20-30 MPa.

The die is made according to the design process requirements of the finished cathode shape and size. When entering the mold for dry pressing, use a sieve with a specification of 60 to 100 mesh to sieve the mixture, put the sieved mixture into the die, press The design requires the control of the amount of materials put into the mixture, and the copper mesh electrode leads of the finished cathode are installed in the middle, and then pressurized, and the formed cathode can be obtained by one-time dry pressing. The method of dry pressing is used to ensure the firmness of the electrode leads. Reliability, preventing cathode delamination and water penetration have obvious effects.

(4) Roasting and finalizing: Roasting the formed cathode prepared in step (3) into the mold and dry pressing, controlling the calcining temperature: 200-380°C, and the calcining time: 6-8 hours, that is, the qualified stereotyped cathode is obtained cathode products.

The roasting refers to sending the shaped cathode into an oven for roasting and shaping. The roasting temperature is controlled as follows: within 1 to 1.5 hours, the temperature is slowly raised from room temperature to 200°C; within 2 to 4 hours, the temperature is slowly raised from 200°C to Roasting at 350°C can make the foaming agent in the mixture slowly volatilize from the formed cathode, forming uniform, dense, waterproof and breathable micropores, which has a significant effect on improving the waterproof and breathable performance of the cathode; at 370°C to 380°C Keep the temperature for 2 to 4 hours to bake and set the shape, so as to stabilize the size of the finished cathode and improve the mechanical strength, and then cool naturally to obtain a qualified cathode product.

The present invention also has following technical characteristics:

In the step of metering and compounding, among the polytetrafluoroethylene powders with particle diameters ≤ 1000 microns, polytetrafluoroethylene suspended fine powders with particle diameters ≤ 200 microns account for 60-80% by weight.

Among the PTFE materials with a particle size of ≤1000 microns: those with a particle size of ≤200 microns are PTFE suspended fine powder, and the rest are PTFE dispersed fine powder. The polytetrafluoroethylene suspended fine powder and polytetrafluoroethylene dispersed fine powder with different particle sizes matched according to a certain weight ratio to form the cathode mixture has a unique technical effect, which can significantly improve the compactness of the cathode material, effectively improve the performance of the cathode.

The advantages of the present invention are as follows:

(1) The method for producing the cathode of an oxygen generator by the dry pressing method proposed by the present invention has simple and convenient process flow, convenient operation and management, high production efficiency, and can greatly reduce production costs. In particular, the original dry pressing forming technology can significantly Improve and improve the process operability of copper mesh electrode leads embedded in the cathode, improve the firmness and reliability of the electrode leads, and have outstanding substantive characteristics and significant progress;

(2) The finished cathode of the oxygen generator produced by the dry pressure method has excellent air permeability and waterproof performance and good low resistance performance, and the working state of the cathode is stable;

(3) The cathode product of the oxygen generator produced by dry pressing method has stable appearance and size, good mechanical strength, and is convenient for assembly process and processing operations. In actual production, it is only necessary to replace the die to manufacture various specifications and shapes. The finished electrode can meet the needs of different oxygen generators and has strong adaptability;

(4) The cathode produced by the dry pressing method is assembled in the oxygen generator, which can significantly increase the oxygen production, has long-term working stability, and has a positive effect on improving and improving the working performance of the oxygen generator.

Detailed ways:

Embodiment one:

The method for producing the cathode of an oxygen generator by a dry pressing method is carried out in the following steps:

(1) Measuring ingredients: measure and prepare the base material according to the following weight ratio

PTFE powder particle size ≤ 1000 micron 8kg

Carbon black Particle size≤1000 microns 3.2kg

Phosphor flake graphite Particle size≤200 mesh 0.32kg

ADC type foaming agent 0.46kg

The ADC type blowing agent is to select commercially available foaming agent finished products produced by Ningxia Risheng Industrial Co., Ltd.

(2) Stirring and mixing: put the material weighed into the mixer, start the mixer, and stir at a high speed of 1000 rpm for 6 minutes, so that the stirred material appears in the form of cotton fibers, which is ready-made Qualified mixture;

(3) Die-in dry pressing: Install the die made according to the design process requirements of the finished cathode dimensions (for example: length 160mm, width 140mm, thickness 3mm) in the dry press, and then mix the prepared The mixed material is sent to a sieve with a specification of 80 meshes for sieving, and the sieved mixed material is put into the die, and the amount of the mixed material is accurately put in according to the design requirements, and the copper mesh electrode lead wire of the finished cathode is installed in the middle, and then Applying a pressure of 26MPa, the formed cathode can be obtained by one-time dry pressing;

(4) Roasting and shaping: send the formed cathode into the electric oven for roasting and shaping, and precisely control the heating and roasting temperature in the electric oven: slowly heat up to 200 ° C within 1.5 hours, and then continue within 3 hours Slowly raise the temperature to 350°C for calcination, then continue to raise the temperature to 380°C for 3 hours, and then cool naturally to obtain a cathode product that meets the design requirements.

Embodiment two

The method for producing the cathode of an oxygen generator by a dry pressing method is carried out in the following steps:

(1) Measuring ingredients: measure and prepare the base material according to the following weight ratio

PTFE suspension fine particle size ≤ 200 microns 5.8kg

PTFE dispersion fine material 200 microns < particle size ≤ 1000 microns 2.2kg

Carbon black Particle size ≤ 1000 microns 2.8kg

Phosphor flake graphite Particle size≤200 mesh 0.29kg

ADC type foaming agent 0.52kg

ADC type foaming agent is commercially available, and is the foaming agent finished product produced by Ningxia Risheng Industrial Co., Ltd.;

(2) Stirring and mixing: put the material weighed into the mixer, start the mixer, and stir at a high speed of 1200 rpm for 5 minutes, so that the stirred material appears in the form of cotton fibers, which is ready-made Qualified mixture;

(3) Dry pressing into the mold: Install the mold made according to the design process requirements of the finished cathode shape and size in the dry press, and then send the mixed material prepared by mixing the mixed material into a sieve with a specification of 80 mesh for sieving , the sieved mixture is put into the die, and the amount of the mixture is accurately put in according to the design requirements, and the copper mesh electrode lead wire of the finished cathode is installed in the middle, and then a pressure of 28MPa is applied to dry press it at one time. shaped cathode;

(4) Roasting and shaping: send the formed cathode into the electric oven for roasting and shaping, and precisely control the heating and roasting temperature in the electric oven: slowly increase the temperature to 200°C within 1 hour, and then continue within 3 hours Slowly raise the temperature to 350°C for calcination, then continue to raise the temperature to 370°C for 4 hours, and then cool naturally to obtain the cathode product.

Claims (2)

1. a method for producing the negative electrode of oxygen generator with dry pressing method, it is base-material with polytetrafluoroethylene powder and carbon black, it is characterized in that: it carries out by following steps successively: (1) Measuring ingredients: measure and prepare the base material according to the following weight ratio PTFE powder 1 part Carbon black 0.35～0.45 parts Control base material: the particle size of polytetrafluoroethylene powder is less than or equal to 1000 microns, The particle size of carbon black is less than or equal to 1000 microns, Add graphite according to 2.5-5.0% of the total weight of the base material, and control the particle size of the graphite to ≤200 mesh, Add foaming agent according to 3.5-5.0% of the total weight of the base material, (2) Stir and mix: put the material weighed in step (1) into the batching mixer and stir and mix to obtain the mix. (3) Dry pressing into the mold: adding the mixture prepared in the step (2) stirring the mixture into the compression mold for dry pressing to obtain a formed cathode, the control pressure is: 20-30MPa, (4) Roasting and finalizing: Roasting the formed cathode prepared in step (3) into the mold and dry pressing, controlling the calcining temperature: 200-380°C, and the calcining time is 6-8 hours, and then the shaped cathode can be obtained. Cathode products. 2. The method for producing the cathode of an oxygen generator according to claim 1, characterized in that: in the step of metering and proportioning, among the polytetrafluoroethylene powders with a particle diameter≤1000 microns, The polytetrafluoroethylene suspended fine powder with a particle diameter less than or equal to 200 microns accounts for 60-80% by weight.