Omnibearing conductive sponge and preparation method thereof

Abstract

The invention discloses an omnibearing conductive sponge and a preparation method thereof, and relates to the technical field of conductive materials. The three-dimensional porous polyurethane composite material comprises three-dimensional porous polyurethane, a flame-retardant conductive hot melt adhesive, a pre-plating layer and an electroplated layer, a layer of flame-retardant conductive hot melt adhesive is infiltrated on the surface of the three-dimensional porous polyurethane I, a pre-plating layer is plated on the surface of the flame-retardant conductive hot melt adhesive through secondary chemical plating, and the electroplated layer is electroplated on the surface of the pre-plating layer. According to the flame-retardant all-dimensional conductive sponge prepared by the preparation method disclosed by the invention, the three-dimensional porous polyurethane is adopted as an intermediate base material, so that the overall elastic compression effect is better realized, the flame-retardant conductive hot melt adhesive and the three-dimensional porous polyurethane belong to independent materials, and the flame retardant and conductive particles can be uniformly distributed very well; therefore, the overall flame retardance of the material and the stability of the shielding effect are improved. The omnibearing conductive sponge produced by the production process is uniform in coating thickness and volume resistance distribution, has good permanent conductivity and chemical stability, and can be widely applied to conductive sponge and conductive foam.

Description

Technical Field

[0001] The invention belongs to the technical field of conductive materials, and in particular relates to an omnidirectional conductive sponge and a preparation method thereof. Background Art

[0002] With the development of social economy and the improvement of people's living standards, high-tech electrical products are becoming more and more popular. Mobile phones, computers, televisions, and microwave ovens bring convenience to people's lives, but also bring certain confusion to people. The problem of electromagnetic radiation is becoming increasingly prominent. In order to reduce and avoid the harm caused by electromagnetic radiation to the human body, the demand for electromagnetic shielding materials is also increasing, and three-dimensional porous conductive structure materials represented by conductive sponges have emerged.

[0003] In the prior art, commonly used filling materials include: FOF (conductive cloth wrapped sponge) / CF (omni-directional conductive sponge) / metal reed, etc., but based on the current product requirements for higher performance of filling materials and cost considerations, flame retardant omni-directional conductive sponge is widely used. The omni-directional conductive sponge is mainly composed of a sponge and a conductive cloth wrapped around the sponge, wherein the sponge is provided with a metal material that has been vacuum-plated throughout, which has low cost, good three-dimensional shielding effect, and can exert excellent protective performance like metal.

[0004] Conductive sponge is a three-dimensional mesh structure functional material that integrates the functions of conduction and electromagnetic shielding. It is widely used in the field of conductive materials due to its long effective period of conduction, good electromagnetic shielding effect, and surface resistance value that can be set according to actual use. At present, conductive sponges produced by preparation methods such as chemical plating, vacuum plating, ion sputtering, vapor deposition, and conductive adhesive coating also have defects such as easy detachment of the coating, poor plating permeability, uneven coating resulting in unstable surface resistance, poor fire and moisture resistance, brittleness and easy powder loss, poor rebound, and short service life, which makes it difficult to meet the quality requirements of modern electronic products. In today's rapidly developing electronic technology, a material with good plating permeability, not easy to fall off, and can meet the requirements of ultra-thin electromagnetic shielding materials has become an inevitable demand for the development of conductive sponges. Summary of the invention

[0005] The purpose of the present invention is to provide an omnidirectional conductive sponge and a preparation method thereof to solve the existing problems.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] The present invention discloses an omni-directional conductive sponge, comprising a three-dimensional porous polyurethane, a flame-retardant conductive hot-melt adhesive, a pre-plating layer and an electroplating layer; a surface of the three-dimensional porous polyurethane is impregnated with a layer of flame-retardant conductive hot-melt adhesive, a pre-plating layer is plated on the surface of the flame-retardant conductive hot-melt adhesive by secondary chemical plating, and the electroplating layer is electroplated on the surface of the pre-plating layer;

[0008] The pre-plating solution used for the pre-plating layer is a pre-nickel plating solution, and the electroplating layer is a nickel layer or a copper-nickel layer.

[0009] Furthermore, in the flame-retardant conductive hot melt adhesive, the proportions of adhesive, flame retardant and conductive medium are 30-50%, 40-60% and 3-10% respectively, calculated by mass percentage; the adhesive is a polymer resin; the conductive medium is metallic nickel; and the flame retardant is an inorganic compound.

[0010] Furthermore, the pre-nickel plating solution is prepared from 20 g / l nickel sulfate, 30 g / l sodium hypophosphite, 16 g / l sodium citrate, and 28 g / l ammonium chloride.

[0011] A method for preparing an omnidirectional conductive sponge comprises the following steps:

[0012] S1. Pretreatment of three-dimensional porous polyurethane: put the three-dimensional porous polyurethane into an ethanol solution, clean it with ultrasonic vibration at 40-50°C for 6 minutes, then rinse it with clean water, then soak and press it with 1mol / L NaOH for 15 minutes, then soak and press it with 1mol / L HCl solution prepared with 38% HCl for 15 minutes, then clean it with clean water, and finally put it into clean water for ultrasonic vibration cleaning for 8 minutes;

[0013] S2. Infiltrating flame-retardant conductive hot melt adhesive: placing the treated three-dimensional porous polyurethane in the flame-retardant conductive hot melt adhesive, soaking it, rolling it in the melt, then taking it out for rolling and rinsing it with water, and the melt on the surface of the three-dimensional porous polyurethane dries to a wet film state at room temperature;

[0014] S3, preparation of pre-plating layer: placing the three-dimensional porous polyurethane soaked with conductive latex in a pre-plating solution with a pH of 8.3-8.7 and a temperature of 43-47°C for the first pre-plating, so that the conductive metal is attached to the surface of the three-dimensional porous polyurethane, the three-dimensional porous polyurethane has a moving speed of less than or equal to 1.4 m / min, and the surface resistance of the three-dimensional porous polyurethane reaches 105Ω after one pre-plating, and then the three-dimensional porous polyurethane after one pre-plating is oxidized and reduced;

[0015] The three-dimensional porous polyurethane after the first pre-plating is placed in a secondary pre-plating solution with a pH of 8.3-8.7 and a temperature of 43-47° C. for a second pre-plating, so that the conductive metal is attached to the surface of the three-dimensional porous polyurethane, the three-dimensional porous polyurethane has a moving speed of less than or equal to 1.4 / min, and the surface resistance of the three-dimensional porous polyurethane after the second pre-plating is 108Ω, and then the three-dimensional porous polyurethane after the second pre-plating is activated and anti-oxidation treated;

[0016] S4, electroplating layer preparation: placing the three-dimensional porous polyurethane subjected to secondary pre-plating treatment into an electroplating tank, and directly electroplating a nickel layer on the surface of the three-dimensional porous polyurethane or electroplating a copper layer first and then electroplating a nickel layer;

[0017] S5. Conductive sponge molding: The three-dimensional porous polyurethane after electroplating is washed with water in a washing tank, and then dried at 140-170°C, and the conductive latex is cross-linked and cured to obtain a full-dimensional conductive sponge.

[0018] The present invention has the following beneficial effects:

[0019] The flame retardant omnidirectional conductive sponge prepared by the present invention adopts three-dimensional porous polyurethane as the intermediate substrate, which better realizes the overall elastic compression effect, and the flame retardant conductive hot melt adhesive and the three-dimensional porous polyurethane are both independent materials, and the flame retardant and the conductive particles can be well evenly distributed, which effectively improves the flame retardancy and conductivity of the material, thereby improving the overall flame retardancy of the material and the stability of the shielding effect.

[0020] The three-dimensional porous polyurethane of the present invention is directly subjected to heat unsealing and cross-linking curing with the coating, so that the substrate and the coating have excellent bonding strength, heat resistance, corrosion resistance and moisture resistance. The substrate is continuously rolled during the pretreatment and infiltration process, so that the inside of the substrate can be better covered. The graded chemical plating of metal not only greatly reduces the leakage rate, but also forms a stable and uniform coating, and the product has a low shedding rate, and solves the defect of high solution requirements in a single chemical plating process.

[0021] The omnidirectional conductive sponge produced by the production process of the present invention has uniform coating thickness, small surface resistance, uniform volume resistance distribution, good permanent conductivity and chemical stability, and can be widely used in conductive sponges and conductive foams.

[0022] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the overall cross-section structure of an omni-directional conductive sponge;

[0025] In the figure: 1. Three-dimensional porous polyurethane; 2. Flame-retardant conductive hot melt adhesive; 3. Pre-plating layer; 4. Electroplating layer. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] See also Figure 1 As shown, the present invention is an omni-directional conductive sponge, comprising a three-dimensional porous polyurethane 1, a flame retardant conductive hot melt adhesive 2, a pre-plating layer 3 and an electroplating layer 4; a layer of flame retardant conductive hot melt adhesive 2 is impregnated on one surface of the three-dimensional porous polyurethane 1, a pre-plating layer 3 is plated on the surface of the flame retardant conductive hot melt adhesive 2 by secondary chemical plating, and the electroplating layer 4 is electroplated on the surface of the pre-plating layer 3;

[0030] The pre-plating solution used for the pre-plating layer 3 is a pre-nickel plating solution, and the electroplating layer 4 is a nickel layer or a copper-nickel layer.

[0031] In one of the embodiments, in the flame-retardant conductive hot melt adhesive, the proportions of adhesive, flame retardant and conductive medium are 30-50%, 40-60% and 3-10% respectively, calculated by mass percentage; the adhesive is a polymer resin; the conductive medium is metallic nickel; and the flame retardant is an inorganic compound.

[0032] In one embodiment, the nickel pre-plating solution is prepared by 20 g / l nickel sulfate, 30 g / l sodium hypophosphite, 16 g / l sodium citrate, and 28 g / l ammonium chloride.

[0033] A method for preparing an omnidirectional conductive sponge comprises the following steps:

[0034] S1. Pretreatment of three-dimensional porous polyurethane: put the three-dimensional porous polyurethane 1 into an ethanol solution, clean it with ultrasonic vibration at 40-50°C for 6 minutes, then rinse it with clean water, then soak and press it with 1mol / L NaOH for 15 minutes, then soak and press it with 1mol / L HCl solution prepared with 38% HCl for 15 minutes, then clean it with clean water, and finally put it into clean water for ultrasonic vibration cleaning for 8 minutes;

[0035] S2, impregnation with flame-retardant conductive hot melt adhesive: placing the treated three-dimensional porous polyurethane 1 in the flame-retardant conductive hot melt adhesive, soaking it, rolling it in the melt, then taking it out for rolling and rinsing it with water, and the melt on the surface of the three-dimensional porous polyurethane dries to a wet film state at room temperature;

[0036] S3, preparation of pre-plating layer: placing the three-dimensional porous polyurethane soaked with conductive latex in a pre-plating solution with a pH of 8.3-8.7 and a temperature of 43-47°C for the first pre-plating, so that the conductive metal is attached to the surface of the three-dimensional porous polyurethane, the three-dimensional porous polyurethane has a moving speed of less than or equal to 1.4 m / min, and the surface resistance of the three-dimensional porous polyurethane reaches 105Ω after one pre-plating, and then the three-dimensional porous polyurethane that has undergone one pre-plating is oxidized and reduced;

[0037] The three-dimensional porous polyurethane after the first pre-plating is placed in a secondary pre-plating solution with a pH of 8.3-8.7 and a temperature of 43-47° C. for a second pre-plating, so that the conductive metal is attached to the surface of the three-dimensional porous polyurethane, the three-dimensional porous polyurethane has a moving speed of less than or equal to 1.4 / min, and the surface resistance of the three-dimensional porous polyurethane after the second pre-plating is 108Ω, and then the three-dimensional porous polyurethane after the second pre-plating is activated and anti-oxidation treated;

[0038] S4, electroplating layer preparation: placing the three-dimensional porous polyurethane subjected to secondary pre-plating treatment into an electroplating tank, and directly electroplating a nickel layer on the surface of the three-dimensional porous polyurethane or electroplating a copper layer first and then electroplating a nickel layer;

[0039] S5. Conductive sponge molding: The three-dimensional porous polyurethane after electroplating is washed with water in a washing tank, and then dried at 140-170°C, and the conductive latex is cross-linked and cured to obtain a full-dimensional conductive sponge.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An omnidirectional conductive sponge, characterized in that: It comprises a three-dimensional porous polyurethane (1), a flame retardant conductive hot melt adhesive (2), a pre-plating layer (3) and an electroplating layer (4); a layer of flame retardant conductive hot melt adhesive (2) is impregnated on one surface of the three-dimensional porous polyurethane (1), the pre-plating layer (3) is plated on the surface of the flame retardant conductive hot melt adhesive (2) by secondary chemical plating, and the electroplating layer (4) is electroplated on the surface of the pre-plating layer (3); The pre-plating solution used for the pre-plating layer (3) is a pre-nickel plating solution, and the electroplating layer (4) is a nickel layer or a copper-nickel layer.

2. The omnidirectional conductive sponge according to claim 1, characterized in that: In the flame-retardant conductive hot melt adhesive, the proportions of adhesive, flame retardant and conductive medium are 30-50%, 40-60% and 3-10% respectively, calculated by mass percentage; the adhesive is a polymer resin; the conductive medium is metallic nickel; and the flame retardant is an inorganic compound.

3. The omnidirectional conductive sponge according to claim 1, characterized in that: The nickel pre-plating solution is prepared from 20 g / l nickel sulfate, 30 g / l sodium hypophosphite, 16 g / l sodium citrate and 28 g / l ammonium chloride.

4. The method for preparing an omnidirectional conductive sponge according to claim 1, applied to the omnidirectional conductive sponge according to any one of claims 1 to 3, characterized in that: The steps include: S1. Pretreatment of three-dimensional porous polyurethane: placing the three-dimensional porous polyurethane (1) in an ethanol solution, washing it with ultrasonic vibration at a temperature of 40-50° C. for 6 min, then washing it with clean water by pressing, then soaking and pressing it with 1 mol / L NaOH for 15 min, then soaking and pressing it with 1 mol / L HCl solution prepared with 38% HCl for 15 min, then washing it with clean water by pressing, and finally washing it with clean water by ultrasonic vibration for 8 min; S2, impregnating flame-retardant conductive hot melt adhesive: placing the treated three-dimensional porous polyurethane (1) in the flame-retardant conductive hot melt adhesive, soaking it, rolling it in the hot melt adhesive, then taking it out for rolling and rinsing it with water, and the hot melt adhesive on the surface of the three-dimensional porous polyurethane dries to a wet film state at room temperature; S3, preparation of pre-plating layer: placing the three-dimensional porous polyurethane soaked with conductive latex in a pre-plating solution with a pH of 8.3-8.7 and a temperature of 43-47°C for the first pre-plating, so that the conductive metal is attached to the surface of the three-dimensional porous polyurethane, the three-dimensional porous polyurethane has a moving speed of less than or equal to 1.4 m / min, and the surface resistance of the three-dimensional porous polyurethane reaches 105Ω after one pre-plating, and then the three-dimensional porous polyurethane that has undergone one pre-plating is oxidized and reduced; The three-dimensional porous polyurethane after the first pre-plating is placed in a secondary pre-plating solution with a pH of 8.3-8.7 and a temperature of 43-47° C. for a second pre-plating, so that the conductive metal is attached to the surface of the three-dimensional porous polyurethane, the three-dimensional porous polyurethane has a moving speed of less than or equal to 1.4 / min, and the surface resistance of the three-dimensional porous polyurethane after the second pre-plating is 108Ω, and then the three-dimensional porous polyurethane after the second pre-plating is activated and anti-oxidation treated; S4, electroplating layer preparation: placing the three-dimensional porous polyurethane subjected to secondary pre-plating treatment into an electroplating tank, and directly electroplating a nickel layer on the surface of the three-dimensional porous polyurethane or electroplating a copper layer first and then electroplating a nickel layer; S5. Conductive sponge molding: The three-dimensional porous polyurethane after electroplating is washed with water in a washing tank, and then dried at 140-170°C, and the conductive latex is cross-linked and cured to obtain a full-dimensional conductive sponge.

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