Rapid induction welding material and preparation method and application thereof

Abstract

The invention relates to a rapid induction welding material and a preparation method and application thereof, and relates to the technical field of welding materials, the rapid induction welding material is applied to plastic rapid induction welding, the rapid induction welding material structurally comprises a plurality of unit welding material structures, and each unit welding material structure comprises a plastic substrate and a conductive functional layer; and the plurality of unit welding material structures are repeatedly and periodically arranged. The rapid induction welding material of the special structure can adapt to different use scenes, the manufacturing process is simple, the production cost is relatively low, compared with a traditional plastic induction welding mode, the metal adding amount is greatly reduced, the welding speed is greatly increased, meanwhile, similar mechanical strength is kept, and the rapid induction welding material has wide application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of welding materials, and in particular relates to a rapid induction welding material and a preparation method and application thereof. Background Art

[0002] Plastics are characterized by light weight, waterproofness, drop resistance, corrosion resistance, low raw material prices, and simple production processes. They are widely used in daily life and production. Plastic products are generally made by injection molding, blow molding, and vacuum forming. For special structures such as complex shapes, hollows, or large sizes, welding is often used for connection. Traditional plastic welding usually uses hot plate welding or hot air welding. Hot plate welding belongs to the contact welding method. The material to be welded must be pressed against the hot plate first. After the weld is melted, the hot plate is withdrawn and the melted part is pressed and melted together. After welding, plastic residual liquid often remains on the hot plate. It is time-consuming and laborious to remove. If it is not handled in time or not handled cleanly, it will cause uneven welding and affect the product yield. Hot air welding uses hot air to melt the welded surface and then pressurizes and welds it. The welding speed is slow and the energy efficiency is low, which affects the production efficiency and is not suitable for mass production.

[0003] In addition to the above two welding methods, induction welding is a welding method that generates induced current in a conductive sample under a high-frequency induced electromagnetic field, and the current generates Joule heat to achieve rapid melting of the material. It has the advantages of non-contact heating, fast melting rate, and high welding efficiency. It has broad application prospects in the field of plastic manufacturing. However, most plastics are not conductive, and the induced electromagnetic field cannot directly heat the plastic. Therefore, it is necessary to add a conductive component that can be inductively heated to the material or use a conductive solder with induction heating function. However, the direct use of metal mesh or plastic to add conductive particles to prepare a conductive network is not only costly, but the macroscopic content of metal residues has an adverse effect on the physical properties and strength of the welded parts. Summary of the invention

[0004] The purpose of the present invention is to provide a rapid induction welding material and a preparation method and application thereof in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A first aspect of the present invention provides a rapid induction welding material, comprising a plurality of unit welding material structures, wherein the unit welding material structures comprise a plastic substrate and a conductive functional layer, and the plurality of unit welding material structures are arranged in a repeated periodic manner.

[0007] As a further optimization solution of the present invention, the rapid induction welding material is at least one of the following structures:

[0008] (A) A one-dimensional linear structure, which is made by linearly stacking at least two unit solder structures;

[0009] (B) a two-dimensional planar structure, which is made by linearly stacking at least two one-dimensional linear structures, wherein the stacking path is in the same plane as the stacking path of the one-dimensional linear structure and is perpendicular to each other;

[0010] (C) A three-dimensional structure is made by linearly stacking at least two two-dimensional planar structures, wherein the stacking path is perpendicular to the plane formed by the stacking path of the one-dimensional linear structure and the stacking path of the two-dimensional structure.

[0011] As a further optimization scheme of the present invention, an auxiliary functional layer for enhancing the bonding force and heat conduction efficiency between the plastic substrate and the conductive functional layer is also compounded between the plastic substrate and the conductive functional layer;

[0012] The auxiliary functional layer is formed by compounding any one of nitride, carbide, oxide or chloride between the plastic substrate and the conductive functional layer by any one of spraying, sputtering, evaporation or electroplating.

[0013] As a further optimization solution of the present invention, the structure of the conductive functional layer is arranged in a flat plate shape or a grid shape.

[0014] As a second aspect of the present invention, there is also provided an application of any of the above-mentioned composite welding material structures in the field of rapid induction welding of plastics.

[0015] As a third aspect of the present invention, there is also provided a method for preparing any of the above-mentioned rapid induction welding materials, comprising the following steps:

[0016] Step 1: preparing a plastic substrate, mixing the surface-treated functional material with a thermoplastic plastic, extruding and granulating the mixture to obtain a composite material, and preparing the composite material by any method such as injection molding, blow molding, vacuum forming or melt evaporation to obtain a plastic substrate;

[0017] Step 2: Prepare a unit solder structure, first roughen and activate the surface of the plastic substrate, then compound the conductive material on the surface of the plastic substrate by any method such as spraying, sputtering, evaporation or electroplating to form a conductive functional layer, and obtain the unit solder structure;

[0018] Step 3: The rapid induction welding material can be prepared by repeatedly arranging multiple unit welding material structures prepared in step 2 in a periodic manner.

[0019] As a further optimization scheme of the present invention, in step 1, the ratio of the functional material to the thermoplastic plastic is (1-2):(3-4).

[0020] As a further optimization scheme of the present invention, the thickness of the plastic substrate prepared in step 1 is 100 nm-100 μm.

[0021] As a further optimization scheme of the present invention, in step one, the functional material is at least one of ceramic crystals, graphite, graphene, glass fiber, carbon nanotubes or carbon fibers, and the functional material is surface treated by acid soaking or using a silane coupling agent.

[0022] As a further optimization scheme of the present invention, in the step 2, the conductive material is at least one of graphite, copper, aluminum or nickel, and the thickness of the conductive functional layer is 100nm-100μm.

[0023] The beneficial effects of the present invention are:

[0024] The present invention prepares a conductive functional layer and an auxiliary functional layer on a plastic substrate to obtain a unit welding material structure, and prepares a fast induction welding material with a one-dimensional linear structure, a two-dimensional planar structure or a three-dimensional structure in a special stacking manner. The fast induction welding material can be adapted to different usage scenarios, and has a simple manufacturing process and relatively low production cost, and has a fast welding speed and high mechanical strength, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A three-dimensional schematic diagram of a unit solder structure provided by the present invention without a nitride functional layer;

[0026] Figure 2 A three-dimensional schematic diagram of a unit solder structure provided with a nitride functional layer provided by the present invention;

[0027] Figure 3 A three-dimensional schematic diagram of a one-dimensional linear structure provided by the present invention;

[0028] Figure 4 A three-dimensional schematic diagram of a two-dimensional planar structure provided by the present invention;

[0029] Figure 5 A three-dimensional schematic diagram of a three-dimensional planar structure provided by the present invention;

[0030] Note: In the above figures, the conductive functional layer is taken as an example of a grid structure. DETAILED DESCRIPTION

[0031] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0032] The present invention provides a rapid induction welding material, comprising a plurality of unit welding material structures, wherein the unit welding material structures are as follows: Figure 1 As shown, the structure includes a plastic substrate and a conductive functional layer.

[0033] Specifically, the plastic substrate is made of a common polymer masterbatch and a functional material additive. The polymer masterbatch can be selected from thermoplastic plastics such as polyethylene, polypropylene, polystyrene, polyoxymethylene, polycarbonate, polyvinyl chloride, polyetheretherketone, nylon, etc. The functional material can be selected from one or more of ceramic crystals or graphite, graphene, carbon nanotubes, and carbon fibers. The purpose of adding the functional material to the polymer masterbatch is to improve the thermal conductivity, electrical conductivity, and mechanical strength of the plastic substrate after welding. Preferably, the ratio of the polymer masterbatch to the functional material is (1-2):(3-4).

[0034] The conductive functional layer is usually made of graphite, copper, aluminum, nickel or other conductive materials, with a thickness of about 100nm-100μm. The structure of the conductive functional layer can be a complete surface or a grid structure (the figures of the present invention all show the conductive functional layer with a grid structure), and the coverage area accounts for 10%-100% of the overall area of ​​the unit solder structure.

[0035] In order to further enhance the bonding force and heat conduction efficiency between the plastic substrate and the conductive functional layer, an auxiliary functional layer is compounded between the two, and a unit soldering material structure with auxiliary functions is provided. Figure 2 The auxiliary functional layer is formed by compounding any material among nitride, carbide, oxide or chloride between the plastic substrate and the conductive functional layer by spraying, sputtering, evaporation or electroplating, and the thickness is usually 10nm-10μm.

[0036] The method for preparing a unit welding material structure specifically comprises the following steps:

[0037] Step 1: First, ceramic crystals or one or more of graphite, graphene, carbon nanotubes, and carbon fibers are surface treated by acid immersion or silane coupling agent to improve the dispersion and bonding ability of the functional material in the polymer masterbatch. Then, the functional material and the polymer masterbatch are put into a twin-screw extruder in proportion, mixed evenly, and granulated. Finally, a plastic substrate is prepared by injection molding, blow molding, vacuum forming, or melt evaporation, and the thickness of the plastic substrate is 100nm-100μm.

[0038] Step 2: Using the plastic substrate prepared in step 1 as a basis, first roughen and activate its surface, and then, according to the needs of use, sequentially prepare an auxiliary functional layer and a conductive functional layer on the plastic substrate by spraying, sputtering, evaporation, electroplating, etc., or directly prepare a conductive functional layer on the surface of the plastic substrate by spraying, sputtering, evaporation, electroplating, etc., to obtain the unit solder structure.

[0039] The rapid induction welding material is specifically a composite structure made by repeatedly and periodically stacking a plurality of the unit welding material structures, and is at least one of the following structures:

[0040] (A) A one-dimensional linear structure, which is made by stacking at least two unit solder structures in the same direction ( Figure 3 );

[0041] (B) A two-dimensional planar structure is made by linearly stacking at least two one-dimensional linear structures, wherein the stacking path is in the same plane as the stacking path of the one-dimensional linear structure and is perpendicular to each other ( Figure 4 );

[0042] (C) A three-dimensional structure is made by linearly stacking at least two two-dimensional planar structures, wherein the stacking path is perpendicular to the plane formed by the stacking path of the one-dimensional linear structure and the stacking path of the two-dimensional structure ( Figure 5 ).

[0043] The content of the present invention is described in detail below in conjunction with specific implementation methods.

[0044] Example 1

[0045] This embodiment provides a method for preparing a rapid induction welding material, comprising the following steps:

[0046] Step 1: The carbon fiber is surface treated by an acid soaking method (using concentrated nitric acid at 40°C for 12 hours), and then the carbon fiber and thermoplastic plastic are put into a twin-screw extruder in a certain ratio of 1:3, mixed evenly and granulated to obtain a composite material, and the composite material is blown into a film with a thickness of 100 μm as a plastic substrate for rapid induction welding materials;

[0047] Step 2: The plastic substrate was polished with 2000-grit sandpaper, and then micro-etched with a mixed solution of chromic acid and sulfuric acid (1:3). The plastic substrate was roughened and activated, and niobium nitride was sputtered on the plastic substrate by a DC reactive magnetron sputtering system to obtain a niobium nitride functional layer. The DC power supply current was controlled at 40 mA, and the sputtering thickness was controlled at 10-20 nm. Subsequently, the current density was 5 A / dm in the electroplating tank. 2Electroplating copper, the composition of the copper plating solution is 160g / L of copper sulfate pentahydrate, 40g / L of sulfuric acid, and 0.02g / L of thiourea. The electroplating time is usually 5min, and a conductive functional layer with a thickness of about 10μm is prepared on the surface of the nitride functional layer (the total metal addition amount is 1%-10%), and a unit solder structure can be obtained;

[0048] Step 3: using at least two unit solder material structures prepared in step 2 to stack by linear hot pressing in the same direction to obtain a fast induction soldering material with a one-dimensional linear structure;

[0049] In addition, a fast induction welding material having a two-dimensional planar structure can be prepared by stacking at least two one-dimensional linear structures by linear hot pressing, wherein the stacking path is in the same plane as the stacking path of the one-dimensional linear structure and is perpendicular to each other;

[0050] In addition, a rapid induction welding material having a three-dimensional structure can be prepared by stacking at least two two-dimensional planar structures by linear hot pressing, wherein the stacking path is perpendicular to the plane formed by the stacking path of the one-dimensional linear structure and the stacking path of the two-dimensional structure.

[0051] Application examples of composite welding material structures:

[0052] The prepared one-dimensional rapid induction welding material is cut into a suitable size and placed on the welding surface for induction heating. A polyethylene plate of 70×30×2mm is used as the workpiece to be welded, and the rapid induction welding material mentioned in the present invention cut to a size of 30×30mm is placed on the welding surface, and the current of the induction heating machine is adjusted to 1000A, and the heating time is 5-10s. The temperature of the welding surface can be raised to about 340°C within 5s, and a pressure of 0.5MPa is applied to the workpiece with a pressure device. After the temperature cools to room temperature, the welding is completed. The entire heating process can be completed within 10s.

[0053] The mechanical strength of the welded parts was analyzed using a universal tensile testing machine. The maximum load on the welding surface of the polyethylene plate was 1208N, which is similar to the maximum tensile load of the polyethylene plate itself of 1265N. The fracture location was near the heat affected zone of the welded plate. It can be seen that the rapid induction welding material of the present application can maintain a very high level of welding strength while achieving a faster welding speed.

[0054] Example 2

[0055] This embodiment provides a method for preparing a rapid induction welding material, comprising the following steps:

[0056] Step 1: soak the glass fiber in a treatment solution containing silane coupling agent KH-550 for 10 minutes for surface treatment. The components of the treatment solution are calculated by mass percentage, including 20% ​​silane coupling agent KH-550 stock solution, 72% ethanol and 8% deionized water. Then, the glass fiber and thermoplastic plastic are put into a twin-screw extruder in a certain ratio of 1:4, mixed evenly and granulated to obtain a composite material. The composite material is blown into a film with a thickness of 100 μm as a plastic substrate for rapid induction welding materials;

[0057] Step 2: The plastic substrate was polished with 2000-grit sandpaper, and then micro-etched with a mixed solution of chromic acid and sulfuric acid (1:3) to complete the roughening and activation treatment. Titanium nitride was sputtered on the plastic substrate by a DC reactive magnetron sputtering system to obtain a titanium nitride functional layer. The DC power supply current was controlled at 40 mA, and the sputtering thickness was controlled at 10-20 nm. Subsequently, the current density was 4 A / dm in the electroplating tank. 2 Electroplating nickel is performed, and the composition of the nickel plating solution is 230g / L nickel sulfate, 75g / L sodium chloride, and 32g / L boric acid as a buffer. The electroplating time is usually 10 minutes, and a conductive functional layer with a thickness of about 8μm is prepared (the total metal addition amount is 0.5%-5%), and a unit solder structure can be obtained;

[0058] Step 3: Same as Example 1.

[0059] Application examples of composite welding material structures:

[0060] A polyethylene plate of 70×30×2mm is used as the workpiece to be welded. The prepared rapid induction welding material is cut into 30×30mm and placed on the welding surface. The current of the induction heating machine is adjusted to 1000A, and the heating time is 5-10s. The temperature of the welding surface can rise to about 340℃ within 5s. A pressure of 0.5MPa is applied to the workpiece with a pressure device. The welding is completed after the temperature cools to room temperature. The entire heating process can be completed within 10s.

[0061] The mechanical strength of the welded parts was analyzed using a universal tensile testing machine. The maximum load on the welded surface of the polyethylene plate was 1154N, which is similar to the maximum tensile load of the polyethylene plate itself, which is 1265N. The fracture location was near the heat-affected zone of the welded plate. This shows that while the welding speed is fast, the welding strength is still maintained at a very high level.

[0062] Comparative Example 1

[0063] Hot plate welding is usually used to weld polyethylene products in industrial production. A more common process parameter is selected, that is, the temperature of the hot plate is 210℃, the welding time is 140s, and the holding pressure after welding is 0.15MPa. Under this welding condition, a polyethylene plate with a size of 70×30×2mm is still used as the welded part. In terms of welding speed, the time it takes for the hot plate to heat up from room temperature to 210℃ varies from 5 to 20 minutes due to equipment differences. The welding time is 140s, and it takes at least 10 minutes to complete the welding operation.

[0064] The mechanical strength of the welded parts was analyzed using a universal tensile testing machine, and the maximum tensile load of the welded surface of the polyethylene plate was maintained at around 1200N (similar to the maximum tensile load of the polyethylene plate itself, 1265N).

[0065] Comparative Example 2

[0066] Polyethylene powder and ferrosoferric oxide powder were doped in a mass ratio of 7:3 (metal addition was 30%), and compared with the currently common induction solder prepared with doped conductive particles. A polyethylene plate with a size of 70×30×2mm was still used as the workpiece to be welded. The prepared rapid induction welding material was cut into 30×30mm and placed on the welding surface. The induction heating machine current was adjusted to 1000A, which was consistent with Example 1. Under the same heating conditions, the induction solder prepared by doping conductive particles heated up slowly. If the heating time was kept consistent with Example 1, welding could not be completed. The heating time was extended, and the workpiece to be welded could be melted at a heating time of about 170s to complete the welding.

[0067] Compared with the product of the present invention, the amount of metal added is greatly increased while the heating efficiency is greatly reduced, which increases the production time and material costs. The mechanical strength of the welded parts is analyzed using a universal tensile testing machine, and the maximum tensile load of the welding surface of the polyethylene plate is also maintained at about 1285N (similar to the maximum tensile load of the polyethylene plate itself, 1265N).

[0068] Comparative Example 3

[0069] The two-dimensional planar structure of the composite welding material with the one-dimensional linear structure of the present application is enlarged in proportion to the two-dimensional composite material of the present invention.

[0070] A polyethylene plate with a size of 70×30×2 mm is still used as the welded part. The above two rapid induction welding materials are cut into 30×30 mm and placed on the welding surface. The current of the induction heating machine is adjusted to 1000A, which is consistent with Example 1. The mechanical strength of the weld is analyzed using a universal tensile machine. The maximum load of the weld material enlarged in proportion is about 680N, while the maximum tensile load of the polyethylene plate using the two-dimensional material of the present invention as the weld material is maintained at about 1200N. The reason is analyzed. The metal dispersion of the weld material enlarged in proportion is too concentrated, forming defects at the welding surface, while the two-dimensional structure weld material of the present invention avoids this situation.

[0071] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A rapid induction welding material, characterized in that: It comprises a plurality of unit solder material structures, wherein the unit solder material structures comprise a plastic substrate and a conductive functional layer, and the plurality of unit solder material structures are arranged in a repeated periodic manner.

2. A rapid induction welding material according to claim 1, characterized in that: The rapid induction welding material is at least one of the following structures: (A) A one-dimensional linear structure, which is made by linearly stacking at least two unit solder structures in the same direction; (B) a two-dimensional planar structure, which is made by linearly stacking at least two one-dimensional linear structures, wherein the stacking path is in the same plane as the stacking path of the one-dimensional linear structure and is perpendicular to each other; (C) A three-dimensional structure is made by linearly stacking at least two two-dimensional planar structures, wherein the stacking path is perpendicular to the plane formed by the stacking path of the one-dimensional linear structure and the stacking path of the two-dimensional structure.

3. A rapid induction welding material according to claim 1, characterized in that: An auxiliary functional layer for enhancing the bonding force and heat conduction efficiency between the plastic substrate and the conductive functional layer is also provided between the plastic substrate and the conductive functional layer; The auxiliary functional layer is formed by compounding any one of nitride, carbide, oxide or chloride between the plastic substrate and the conductive functional layer by any one of spraying, sputtering, evaporation or electroplating.

4. A rapid induction welding material according to claim 1, characterized in that: The conductive functional layer (2) is structured in a flat plate or grid shape.

5. Use of the rapid induction welding material according to any one of claims 1 to 4 in the field of rapid induction welding of plastics.

6. A method for preparing a rapid induction welding material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: preparing a plastic substrate, mixing the surface-treated functional material with a thermoplastic plastic, extruding and granulating the mixture to obtain a composite material, and preparing the composite material by any method such as injection molding, blow molding, vacuum forming or melt evaporation to obtain a plastic substrate; Step 2: Prepare a unit solder structure, first roughen and activate the surface of the plastic substrate, then compound the conductive material on the surface of the plastic substrate by any method such as spraying, sputtering, evaporation or electroplating to form a conductive functional layer, and obtain the unit solder structure; Step 3: The rapid induction welding material can be prepared by repeatedly arranging multiple unit welding material structures prepared in step 2 in a periodic manner.

7. The method for preparing a rapid induction welding material according to claim 6, characterized in that: In the step 1, the ratio of the functional material to the thermoplastic plastic is (1-2):(3-4).

8. The method for preparing a rapid induction welding material according to claim 6, characterized in that: The thickness of the plastic substrate prepared in step 1 is 100 nm-100 μm.

9. The method for preparing a rapid induction welding material according to claim 6, characterized in that: In the step 1, the functional material is at least one of ceramic crystals, graphite, graphene, glass fiber, carbon black, carbon nanotubes or carbon fibers, and the functional material is surface treated by acid soaking or using a silane coupling agent.

10. The method for preparing a rapid induction welding material according to claim 6, characterized in that: In the step 2, the conductive material is at least one of graphite, copper, aluminum or nickel, and the thickness of the conductive functional layer is 100 nm-100 μm.

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