阅读说明：本技术 无镀铜无缝药芯焊丝用涂料、制备方法、涂覆工艺 (Coating for copper-plating-free seamless flux-cored wire, preparation method and coating process ) 是由 魏梦飞 姚润钢 亢天佑 孔红雨 朱官朋 于 2019-11-01 设计创作，主要内容包括：本发明公开了无镀铜无缝药芯焊丝用涂料、制备方法、涂覆工艺,涂料包括如下组分：低结晶态的聚乙烯醇缩甲醛30~40份,DW水性聚合物活性溶液10~20份,丙酮溶液20~30份,蒸馏水70~80份,分散剂3~4份,阻燃剂2~4份,纳米镍粉1~2份。该涂料的制备方法为先向DW水性聚合物活性溶液中加入蒸馏水和丙酮溶液于55~65℃下搅拌均匀；再将低结晶态的聚乙烯醇缩甲醛加入到丙酮溶液中并充分搅拌,加入阻燃剂于55~60℃下高速搅拌均匀；将两种溶液混合,向混合液中加入分散剂,然后加入蒸馏水调节浓度,之后再加入纳米镍粉,在55~65℃下搅拌均匀,即得到涂料。将上述涂料涂覆于焊丝表面,即得到无镀铜无缝药芯焊丝,涂料与焊丝的结合力强,焊丝具有导电、润滑和防锈的综合功能。(The invention discloses a coating for a copper-plating-free seamless flux-cored wire, a preparation method and a coating process, wherein the coating comprises the following components: 30-40 parts of low-crystalline polyvinyl formal, 10-20 parts of DW water-based polymer active solution, 20-30 parts of acetone solution, 70-80 parts of distilled water, 3-4 parts of dispersing agent, 2-4 parts of flame retardant and 1-2 parts of nano nickel powder. The preparation method of the coating comprises the steps of adding distilled water and an acetone solution into a DW water-based polymer active solution, and uniformly stirring at 55-65 ℃; adding the polyvinyl formal with low crystallinity into the acetone solution, fully stirring, adding the flame retardant, and uniformly stirring at a high speed at 55-60 ℃; and mixing the two solutions, adding a dispersing agent into the mixed solution, adding distilled water to adjust the concentration, then adding the nano nickel powder, and uniformly stirring at 55-65 ℃ to obtain the coating. The coating is coated on the surface of the welding wire to obtain the copper-plating-free seamless flux-cored wire, the binding force of the coating and the welding wire is strong, and the welding wire has comprehensive functions of conductivity, lubrication and rust prevention.)

1. The coating for the copper-free seamless flux-cored wire is characterized by comprising the following components in parts by mass:

30-40 parts of polyvinyl formal with low crystallization state;

10-20 parts of DW aqueous polymer active solution;

20-30 parts of an acetone solution;

70-80 parts of distilled water;

3-4 parts of a dispersing agent;

2-4 parts of a flame retardant;

1-2 parts of nano nickel powder.

2. The coating for the copper-plating-free seamless flux-cored wire according to claim 1, wherein the nano nickel powder is non-nickel oxide powder, and has an average particle size of 50 to 100nm and a specific surface area of 23.2m²(ii)/g, powder conductivity 10000 s/m.

3. A method for preparing the coating for the copper-free seamless flux-cored wire according to claim 1, comprising the steps of:

(1) adding distilled water and an acetone solution into the DW aqueous polymer active solution, and uniformly stirring at 55-65 ℃ to obtain a solution A;

(2) adding the polyvinyl formal with low crystallinity into an acetone solution, fully stirring until the polyvinyl formal is completely dissolved, then adding a flame retardant, and uniformly stirring at a high speed at 55-60 ℃ to obtain a solution B;

(3) mixing the solution A obtained in the step (1) with the solution B obtained in the step (2) to obtain a mixed solution, adding a dispersing agent into the mixed solution, adding distilled water to adjust the concentration to be 30-35% of the concentration of the mixed solution, adding nano nickel powder into the diluted mixed solution, and uniformly stirring at 55-65 ℃ to obtain the coating.

4. A process for coating welding wires by using the coating of claim 1, which is characterized in that the welding wires are subjected to high-pressure water circulation cleaning; then dip-coating the cleaned welding wire by a dip-coating device filled with the coating of claim 1, heating and curing the dip-coated welding wire, and finally sizing by a sizing device to obtain the seamless flux-cored welding wire without copper plating.

5. The process for coating the welding wire by using the coating as claimed in claim 4, wherein after the welding wire is subjected to dip coating, the welding wire passes through a gas flow dividing device to remove the redundant coating and perform coating homogenization treatment on the welding wire by using gas, and then is subjected to heating curing; wherein the pressure of the gas is 0.5-1 MPa.

6. The process for coating a welding wire with the coating according to claim 4, wherein the temperature of the coating in the dip coating process is 60 to 70 ℃ when the welding wire is subjected to dip coating.

7. The process for coating a welding wire by using the coating as claimed in claim 4, wherein the temperature for heating and curing the welding wire is 120 to 150 ℃ and the linear velocity is 0.09 to 0.14 m/s.

8. The process for coating a welding wire with the coating according to claim 4, wherein the coating thickness of the coating in the welding wire is 15 to 30 μm.

Technical Field

The invention relates to the technical field of welding wires, in particular to a coating for a copper-plating-free seamless flux-cored wire, a preparation method and a coating process.

Background

Although the market demand of the traditional copper-plated welding wire and seamed flux-cored welding wire is huge, the following problems exist: the traditional copper-plated welding wire has poor bonding force between a copper plating layer and a substrate, is easy to peel off, blocks a wire guide pipe, influences wire feeding performance, releases copper steam in the welding process, damages the health of operators, has large welding spatter, and causes huge pollution to the environment due to the discharge of waste liquid in the production process of the copper-plated welding wire. The seamed flux-cored wire has serious moisture absorption and extremely poor anti-rust capability, the welding quality of the seamed flux-cored wire is difficult to ensure in an environment with high humidity, the problems of torsional stress, short wire feeding distance and poor alignment exist during use, and electric arc is unstable during welding. The copper-free seamless flux-cored wire has the advantages of the two and can make up for the defects of the two, so the copper-free seamless flux-cored wire is widely researched and applied, but the copper-free seamless flux-cored wire also has many problems, and the most prominent is that: the welding wire coating is too thick and uneven, so that welding arc is unstable, splashing is large and the like, and the welding process performance is influenced; the electric conductivity is poor, so that frequent arc extinction is caused in the welding process, and the welding efficiency is influenced; the lubricating property of the welding wire coating is poor, so that the welding wire can seriously wear the contact tip during welding; poor rust-proof performance and complex process.

Patent application No. CN201410053171.0 discloses an atmospheric corrosion resistant iron-based alloy and a copper-free welding wire, which mainly solves the problem of rust prevention of the welding wire, but fails to fully consider the comprehensive performance of rust prevention, conductivity and lubrication of the welding wire. The application number CN201710547395.0 discloses a coating for a copper-free welding wire and application thereof, which fully considers the comprehensive performances of rust prevention, conductivity and lubrication of the welding wire, but the coating is firstly carried out, and then the coating of a rust-proof surface coating is carried out, the two-step separate coating mode has complex process, the production efficiency is reduced, a layer of rust-proof oil is coated on the surface of the copper-free welding wire, and the oil film is not conductive, so the risk of influencing the conductivity of the welding wire exists, and the welding precision is finally influenced.

Therefore, the coating for the copper-plating-free seamless flux-cored wire is prepared, and the coating is matched with a corresponding coating process to prepare the welding wire with excellent comprehensive performances of rust prevention, electric conduction and lubrication, and is always the direction of exploration of the technical personnel in the field.

Disclosure of Invention

In order to solve the defects in the prior art, the first purpose of the invention is to provide the coating for the copper-plating-free seamless flux-cored wire and the preparation method thereof, the coating comprehensively considers the factors of the rust resistance, the surface lubricity, the wire feeding property, the conductivity of the welding wire, the binding force between a coating and the welding wire and the like, and can solve the problems that the copper plating layer of the traditional copper-plating solid-cored wire is poor in binding force with a substrate, the corrosion resistance is poor, copper steam is released in the welding process, and the physical health of an operator is damaged; and the problems of serious abrasion of a contact tip, weak binding force, poor rust resistance and the like during the welding of the solid welding wire without copper plating.

The coating for the copper-free seamless flux-cored wire comprises the following components in parts by mass: 30-40 parts of polyvinyl formal with low crystallization state; 10-20 parts of DW aqueous polymer active solution; 20-30 parts of an acetone solution; 70-80 parts of distilled water; 3-4 parts of a dispersing agent; 2-4 parts of a flame retardant; 1-2 parts of nano nickel powder.

The nano nickel powder is non-nickel oxide powder, the average particle size of the nano nickel powder is 50-100nm, and the specific surface area of the nano nickel powder is 23.2m²(ii)/g, powder conductivity 10000 s/m.

A method for preparing a coating for a copper-plating-free seamless flux-cored wire comprises the following steps:

(1) adding distilled water and an acetone solution into the DW aqueous polymer active solution, and uniformly stirring at 55-65 ℃ to obtain a solution A;

(2) adding low-crystalline polyvinyl formal into an acetone solution, fully stirring until the polyvinyl formal is completely dissolved, then adding a flame retardant, and uniformly stirring at a high speed at 55-60 ℃ to obtain a solution B;

(3) and (3) mixing the solution A obtained in the step (1) with the solution B obtained in the step (2) to obtain a mixed solution, adding a dispersing agent into the mixed solution, adding distilled water to adjust the concentration to be 30% -35% of the concentration of the mixed solution, adding nano nickel powder into the diluted mixed solution, and uniformly stirring at 55-65 ℃ to obtain the coating. The coating can be completely dissolved at 55-65 ℃, and the coating which is uniformly mixed can be more easily obtained during preparation.

In order to solve the defects in the prior art, the second purpose of the invention is to provide a process for coating the welding wire by using the coating, and the welding wire coated with the coating has comprehensive performances of conductivity, lubrication and rust prevention.

In order to achieve the purpose, the invention adopts the specific scheme that: the process of coating the welding wire by using the coating comprises the steps of firstly carrying out high-pressure water circulation cleaning on the welding wire; and dip-coating the cleaned welding wire by a dip-coating device filled with coating, heating and curing the dip-coated welding wire, and finally sizing by a sizing device to obtain the copper-plating-free seamless flux-cored wire. When the welding wire is coated with paint, the welding wire sequentially passes through the high-pressure water circulation cleaning device, the dip-coating device, the heating and curing device and the sizing device.

Preferably, after the welding wire is subjected to dip coating, redundant coating removal and homogenization treatment are carried out on the welding wire by utilizing gas through a gas distribution device, and then heating and curing are carried out, wherein the pressure of the gas is 0.5-1 MPa.

Preferably, when the welding wire is subjected to dip coating, the temperature of the coating in the dip coating device is 60-70 ℃. The coating can be completely dissolved at the temperature of 60-70 ℃, the coating is more uniform, and the coating is more easily homogenized during coating.

Preferably, the temperature for heating and curing the welding wire is 120-150 ℃, and the linear speed is 0.09-0.14 m/s.

Preferably, the coating thickness of the coating in the welding wire is 15-30 μm.

The polyvinyl formal (PVF) in a low crystalline state in the coating can be dissolved in acetone to form a solution, has good film forming property, strong adhesion with metal and good insulation but electric breakdown property, can be used in combination with the DW aqueous polymer active solution and the nano nickel powder, can effectively improve the breakdown probability of a welding wire coating, and simultaneously has the functions of lubrication and rust prevention. Compared with the polyvinyl formal with high crystallinity, the polyvinyl formal with low crystallinity forms a film on the surface of the welding wire to be thicker, has better wrapping effect on the welding wire, is more beneficial to rust prevention, but can influence the electric conductivity of the welding wire, and is the reason for matching with the nano nickel powder, and the addition of the nano nickel powder can compensate the influence of the polyvinyl formal with low crystallinity on the electric conductivity.

The DW water-based polymer active solution has self-drying property, and a dry film which is insoluble in water and has water irreversibility can be generated after the water in the solution is evaporated; and it has high glossiness, hardness, strong associativity with welding wire and good compactness.

The acetone solution is not only an organic solvent for preparing the polyvinyl formal solution, but also contributes to improving the curing speed of the welding wire coating during drying.

The purpose of adding the dispersing agent into the coating is to uniformly distribute all components in the solution and simultaneously help the welding wire to be wrapped by the coating more uniformly. However, the addition amount is too high, which is unfavorable for the welding performance of the welding wire, so that the mass portion is preferably controlled to be 3-4 parts under the condition of the mixture ratio.

The flame retardant is added into the coating, and the aim of matching polyvinyl formal is to mix the polyvinyl formal, because the polyvinyl formal is inflammable, a welding wire coating can burn due to overhigh temperature and move in a conductive nozzle during welding, so that the coating can not play a due role in lubrication, and a proper amount of flame retardant is required to be added to prevent the welding wire coating from burning when the temperature is overhigh. In the welding process, the welding wire exposed out of the contact tip is very short, and the length of the welding wire exposed out of the contact tip with the diameter of 1.2mm is generally about 10mm, so that the addition amount of the flame retardant is proper, too little flame retardant effect cannot be achieved, too much flame retardant effect can cause frequent arc extinguishing, and the mass part is preferably controlled to be 2-4 parts under the condition of the mixture ratio.

The nano nickel powder added into the coating is sphericalParticles of non-nickel oxide powder having an average particle size of 50 to 100nm and a specific surface area of 23.2m²(kg), powder conductivity 10000 s/m. The nano nickel powder is added mainly for improving the electric breakdown probability of the welding wire coating and playing a role of a conductive bridge. In the above-mentioned mixing ratio, the mass portion should be controlled within 1-2 portions.

Has the advantages that:

1. the polyvinyl formal with low crystallization state in the coating has strong adhesion with metal and good electric breakdown property; after the water in the DW aqueous polymer active solution is evaporated, a dry film which is insoluble in water and has water irreversibility can be generated; the nano nickel powder can improve the electric breakdown probability of the welding wire coating, so that the coating on the surface of the welding wire can meet the conductivity requirement during welding, and the three are matched for use, so that the breakdown probability of the welding wire coating can be effectively improved, and the lubricating and antirust functions are realized.

2. The nano nickel powder is mainly used for improving the conductivity of the copper-free seamless flux-cored wire in the welding process and increasing the probability of breakdown of a coating. The particle size of the nano nickel powder is selected to be 50-100nm, which is determined by the thickness (15-30 μm) of the coating coated on the surface of the welding wire on one hand, and on the other hand, the nano nickel powder with smaller particle size is relatively lighter in weight and is more uniformly distributed in the solution.

3. The seamless flux-cored wire without copper plating utilizes high-pressure water circulation cleaning to replace the traditional acid-base cleaning, and can reduce the problem of environmental pollution compared with the traditional copper-plated wire. After a layer of coating with the thickness of 15-30 microns is uniformly coated on the surface of the welding wire, the binding force of the coating and the welding wire is strong, the welding wire has comprehensive functions of conductivity, lubrication and rust prevention, the corrosion risk in the aspect of transportation and storage is reduced, and the abrasion of a contact tube in the use process is also reduced.

4. A gas shunting device is added behind the dip-coating device, so that the welding wire can act more uniformly on the surface of the welding wire for a circle after passing through the gas shunting device, and the coating is more uniform; the selection of the heating curing temperature is matched with the linear velocity of the welding wire, so that the consumption is reduced while the due curing effect of the coating is achieved, and the cost is saved.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.

It should be noted that various raw materials used in the following examples are conventional commercially available products unless otherwise specified.

The coating for the copper-free seamless flux-cored wire comprises the following components in parts by mass: 30-40 parts of polyvinyl formal with low crystallization state; 10-20 parts of DW aqueous polymer active solution; 20-30 parts of an acetone solution; 70-80 parts of distilled water; 3-4 parts of a dispersing agent; 2-4 parts of a flame retardant; 1-2 parts of nano nickel powder.

The dispersant selected by the invention is a water-based BYK190 dispersant, and the flame retardant is a water-soluble SW-603A flame retardant.

The nano nickel powder is non-nickel oxide powder, the average particle size of the nano nickel powder is 50-100nm, and the specific surface area of the nano nickel powder is 23.2m²(ii)/g, powder conductivity 10000 s/m.

A method for preparing a coating for a copper-plating-free seamless flux-cored wire comprises the following steps:

(1) adding distilled water and an acetone solution into the DW aqueous polymer active solution, and uniformly stirring at 55-65 ℃ to obtain a solution A;

(2) adding the polyvinyl formal with low crystallinity into an acetone solution, fully stirring until the polyvinyl formal is completely dissolved, then adding a flame retardant, and uniformly stirring at a high speed at 55-60 ℃ to obtain a solution B;

(3) mixing the solution A obtained in the step (1) with the solution B obtained in the step (2) to obtain a mixed solution, adding a dispersing agent into the mixed solution, adding distilled water to adjust the concentration to be 30% -35% of the concentration of the mixed solution, adding nano nickel powder into the diluted mixed solution, and uniformly stirring at 55-65 ℃ to obtain the coating.

The process for coating the welding wire by using the coating is to perform high-pressure water circulation cleaning on the welding wire; and then dip-coating the cleaned welding wire by a dip-coating device filled with the coating (in the dip-coating process, the temperature of the coating is controlled to be 60-70 ℃), installing a coating removing device for removing the redundant coating by using gas at a wire outlet of the dip-coating device, aiming at blowing off the redundant coating and homogenizing the coating on the surface of the welding wire, controlling the gas pressure to be 0.5-1 MPa, then heating and curing the dip-coated welding wire at the temperature of 120-150 ℃, with the linear speed of 0.09-0.14 m/s, and finally carrying out sizing treatment by a sizing device to ensure that the coating is combined with the welding wire more firmly, thus obtaining the seamless flux-cored welding wire without copper plating.

The coating thickness of the coating in the finally obtained copper-plating-free seamless flux-cored wire is 15-30 mu m.

The diameters of the finally obtained copper-plating-free seamless flux-cored wires are 1.0mm, 1.2mm and 1.4 mm.