CN112466508A - Conductive composition, conductive film, circuit structure and wearable device - Google Patents

Abstract

A conductive composition comprises a polymer resin, metal powder, a conductive carbon material and a solvent, wherein each metal powder comprises a main part and a plurality of branch parts which are connected with the main part and face different directions, the polymer resin is dissolved in the solvent, and the metal powder and the conductive carbon material are dispersed in the solvent in which the polymer resin is dissolved. The conductive composition can be stretched after being cured and does not limit the stretchable direction, the polymer resin accounts for 10-40% of the solid content of the conductive composition, the metal powder accounts for 40-89% of the solid content of the conductive composition, the conductive carbon material accounts for 0.1-5% of the solid content of the conductive composition, and the solvent accounts for 25-40% of the conductive composition by weight. In addition, the invention also provides a conductive film, a circuit structure and wearable equipment applying the conductive composition.

Description

Conductive composition, conductive film, circuit structure and wearable device

Technical Field

The invention relates to a composition, in particular to a conductive composition, and a conductive film, a circuit structure and a wearable device applying the conductive composition.

Background

In recent years, with the rise of artificial sensing skin, smart skin (E-skin), robot arm, and smart wearing garment (E-textile), more and more people are paying attention to stretchable materials, such as stretchable elements, conductive connecting materials, and stretchable electrodes. However, the conventional sensing element and the metal conductor themselves do not have stretchable characteristics, which makes it difficult to apply the sensing element to wearable sensing elements. In the prior art, the stretchability of the material which is not stretchable per se is generally achieved by the design of the structure, for example, the design of the lines in the structure of waves, honeycombs, spirals, sponges, and the like. However, the resistance of the wiring increases sharply after a certain number of times of stretching. In addition, even though the non-stretchable material has a stretchable characteristic due to the structural design, the non-stretchable material is complex in process, high in cost, not easy to mass-produce, and can be stretched only in a specific direction.

Disclosure of Invention

In view of the above, there is a need for a conductive composition that is stretchable after curing and does not define a stretchable direction.

In addition, a conductive film, a circuit structure and a wearable device applying the conductive composition are also needed to be provided.

A conductive composition comprises a polymer resin, metal powder, a conductive carbon material and a solvent, wherein each metal powder comprises a main part and a plurality of branch parts which are connected with the main part and face different directions, the polymer resin is dissolved in the solvent, the metal powder and the conductive carbon material are dispersed in the solvent for dissolving the polymer resin, the polymer resin accounts for 10-40% of the solid content of the conductive composition, the metal powder accounts for 40-89% of the solid content of the conductive composition, the conductive carbon material accounts for 0.1-5% of the solid content of the conductive composition, and the solvent accounts for 25-40% of the conductive composition by weight.

Further, the elastic recovery of the elastomer formed of the polymer resin is greater than or equal to 95%.

The polymer resin is at least one selected from thermoplastic styrene block copolymer, nitrile rubber, polyurethane resin and polydimethylsiloxane resin, and the conductive carbon material is at least one selected from graphene, carbon black, carbon nano tubes, graphite powder, carbon fibers and expanded graphite.

Further, the branch portions in each metal powder face different directions.

Further, the solvent is an organic solvent with a boiling point of more than 150 ℃.

A conductive film obtained by drying and curing the conductive composition as described above.

A circuit structure comprising a conductive film as described above.

A wearable device comprising a circuit structure as described above.

The conductive composition of the present invention comprises the dendritic metal powder, and the branch parts of the dendritic metal powder are oriented in different directions to help form a three-dimensional network conductive path between the dendritic metal powder when the conductive film is formed, thereby reducing the conductive contact resistance value and making the stretching direction of the conductive film unrestricted. In addition, the dendritic metal powder is beneficial to improving the acting force between the dendritic metal powder and the polymer resin, and the cracking phenomenon caused by stretching is reduced when the conductive film is stretched.

Detailed Description

The conductive composition of the preferred embodiment of the present invention forms a conductive film after being dried and cured, and the conductive film can be used as a conductive circuit applied to circuit structures of various components or devices, such as circuit structures of wearable devices. The conductive composition comprises polymer resin, metal powder, a conductive carbon material and a solvent. Each metal powder comprises a main part and a plurality of branch parts connected with the main part, so that the metal powder is in a three-dimensional dendritic shape. Preferably, a plurality of the branch parts are oriented in different directions. The polymer resin is dissolved in the solvent, and the metal powder and the conductive carbon material are dispersed in the solvent in which the polymer resin is dissolved. The branch parts in the metal powder contribute to forming a three-dimensional mesh-shaped conductive path between the dendritic metal powders when the conductive film is formed, so that the conductive contact resistance is reduced, and the stretching direction of the conductive film is not limited. In addition, the dendritic metal powder is beneficial to improving the acting force between the dendritic metal powder and the polymer resin, and the cracking phenomenon caused by stretching is reduced when the conductive film is stretched.

In this embodiment, the polymer resin accounts for 10% to 40% of the solid content of the conductive composition, the metal powder accounts for 40% to 89% of the solid content of the conductive composition, and the conductive carbon material accounts for 0.1% to 5% of the solid content of the conductive composition.

The solvent is present in the conductive composition in an amount of 25 to 40 weight percent.

The elastic recovery rate of the elastomer formed by the polymer resin is greater than or equal to 95%. The polymer resin may be selected from at least one of thermoplastic styrene block copolymer, nitrile rubber, polyurethane resin, and polydimethylsiloxane resin.

The metal powder can be any conductive metal material and alloy material thereof, such as silver powder, copper powder, nickel powder, gold powder, platinum powder, palladium powder, aluminum powder, tin powder, silver-coated copper powder and the like. Preferably, the metal powder is made of silver-coated copper powder.

The conductive carbon material may be at least one selected from graphene, carbon black, carbon nanotubes, graphite powder, carbon fibers, expanded graphite, and the like. The addition of the conductive carbon material can improve the thixotropic property of the conductive composition and enhance the conductive effect of the conductive composition.

The solvent is an organic solvent and can dissolve the polymer resin. Preferably, the solvent is an organic solvent having a boiling point greater than 150 ℃, such as Aromatic hydrocarbon solvent S-150(High-Flash Aromatic Naphtha-150), to facilitate spreading of the conductive composition when the conductive composition is applied.

In the present embodiment, the size of each metal powder is preferably 1 to 20 μm.

Preferably, the conductive composition may further include other forms of conductive metal, such as flake or sphere conductive metal powder. When the conductive film is formed, the conductive metal powder is filled in the gaps of the formed three-dimensional mesh-shaped conductive path, so that the conductive path is further improved, and the resistance value is further reduced.

The present invention will be specifically described below with reference to examples.

Example 1

According to the weight percentage, 15.7 percent of thermoplastic styrene block copolymer, 47.1 percent of dendritic silver-coated copper metal powder, 0.5 percent of carbon black and 36.7 percent of S-150 are evenly mixed to prepare the conductive composition.

Example 2

According to the weight percentage, 15.7 percent of nitrile rubber, 47.1 percent of dendritic silver-coated copper metal powder, 0.5 percent of carbon black and 36.7 percent of S-150 are evenly mixed to prepare the conductive composition.

Example 3

According to the weight percentage, 15.7 percent of polyurethane resin, 47.1 percent of dendritic silver-coated copper metal powder, 0.5 percent of carbon black and 36.7 percent of S-150 are evenly mixed to prepare the conductive composition.

Example 4

According to the weight percentage, 15.7 percent of polydimethylsiloxane resin, 47.1 percent of dendritic silver-coated copper metal powder, 0.5 percent of carbon black and 36.7 percent of S-150 are evenly mixed to prepare the conductive composition.

Example 5

According to the weight percentage, 20 percent of polydimethylsiloxane resin, 50 percent of dendritic silver-coated copper metal powder, 0.5 percent of carbon black and 29.5 percent of S-150 are evenly mixed to prepare the conductive composition.

Example 6

The conductive composition was prepared by uniformly mixing 15.7% by weight of a thermoplastic styrene block copolymer, 47.1% by weight of a dendritic silver powder, 0.5% by weight of carbon black, and 36.7% by weight of S-150.

Example 7

The conductive composition is prepared by uniformly mixing 15.7 percent of thermoplastic styrene block copolymer, 42 percent of dendritic silver-coated copper metal powder, 5.1 percent of flaky silver powder, 0.5 percent of carbon black and 36.7 percent of S-150 according to weight percent.

Example 8

According to the weight percentage, 15.7 percent of thermoplastic styrene block copolymer, 40 percent of dendritic silver-coated copper metal powder, 7.1 percent of spherical silver powder, 0.5 percent of carbon black and 36.7 percent of S-150 are evenly mixed to prepare the conductive composition.

Comparative example 1

According to the weight percentage, 20 percent of nitrile rubber, 50 percent of flaky silver powder and 30 percent of S-150 are evenly mixed to prepare the conductive composition.

Comparative example 2

According to the weight percentage, 16 percent of nitrile rubber, 60 percent of flaky silver powder and 24 percent of S-150 are evenly mixed to prepare the conductive composition.

Comparative example 3

The conductive composition was prepared by uniformly mixing 15.7% by weight of a thermoplastic styrene block copolymer, 47.1% by weight of a plate-like silver powder, 0.5% by weight of carbon black and 36.7% by weight of S-150.

Comparative example 4

The conductive composition was prepared by uniformly mixing 15.7% by weight of a thermoplastic styrene block copolymer, 47.1% by weight of a spherical silver powder, 0.5% by weight of carbon black and 36.7% by weight of S-150.

12 kinds of conductive films having the same thickness and the same length were formed using the 12 kinds of conductive compositions prepared in examples 1 to 8 and comparative examples 1 to 4, and the 12 kinds of conductive films were subjected to initial resistance values R₀Measuring; and then testing whether the conductive film can be stretched for 500 times, wherein each time of stretching is to the original length1.5 times of the total amount of the conductive particles, and the resistance value R of the conductive film after 500 times of stretching₁(ii) a Performing a check adhesion test on the conductive film, wherein the check adhesion test is NG when the conductive film is torn off, and the check adhesion test is PASS when the conductive film is not torn off; and (3) testing the dead-fold characteristic of the conductive film, specifically, after the conductive film is folded by 180 degrees, detecting whether the surface of the conductive film has cracks, wherein the test result is NG when the cracks exist, and the test result is PASS when the cracks do not exist. The results of each test are reported in table 1.

TABLE 1

As can be seen from Table 1, the 8 kinds of conductive films formed from the conductive compositions of examples 1 to 8 of the present invention have better adhesive force in the form of a lattice and appearance of the surface after folding in half 180, compared to the 2 kinds of conductive films formed from the conductive compositions of comparative examples 1 to 2. Further, as can be seen from comparative examples 1 to 2, in order to reduce the resistance value of the conductive film, the content of the metal powder needs to be increased, which leads to an increase in cost. The resistance values of the 8 conductive films formed from the conductive compositions of examples 1-8 of the present invention were not too large after 500 stretches were completed, compared to the 2 conductive films formed from the conductive compositions of comparative examples 3-4. Further, in the case where the polymer resins are the same, the conductive compositions of examples 1 and 6 to 8 containing the dendritic metal powder of the present invention each formed a conductive film having a resistance value after 500 times of stretching which was much smaller than the resistance value of the conductive film containing no dendritic metal powder after 500 times of stretching.

The conductive composition of the present invention comprises the branch parts of the metal powder, which contribute to the formation of a three-dimensional network conductive path between the dendritic metal powder when forming a conductive film, thereby reducing the conductive contact resistance value and making the stretching direction of the conductive film unrestricted. In addition, the dendritic metal powder is beneficial to improving the acting force between the dendritic metal powder and the polymer resin, and the cracking phenomenon caused by stretching is reduced when the conductive film is stretched.

Claims (8)

Translated fromChinese

1.一种导电组合物，其特征在于，所述导电组合物包括聚合物树脂、金属粉、导电碳材及溶剂，其中，每一金属粉包括主干部及多个连接所述主干部的分枝部，所述聚合物树脂溶解于所述溶剂中，所述金属粉及导电碳材分散于溶解所述聚合物树脂的所述溶剂中，所述聚合物树脂占所述导电组合物固含量的10％至40％，所述金属粉占所述导电组合物固含量的40％至89％，所述导电碳材占所述导电组合物固含量的0.1％至5％，所述溶剂在所述导电组合物中的重量百分含量为25％至40％。1. A conductive composition, characterized in that the conductive composition comprises a polymer resin, metal powder, conductive carbon material and a solvent, wherein each metal powder comprises a main portion and a plurality of components connecting the main portion In the branch part, the polymer resin is dissolved in the solvent, the metal powder and the conductive carbon material are dispersed in the solvent for dissolving the polymer resin, and the polymer resin accounts for the solid content of the conductive composition 10% to 40% of the solid content of the conductive composition, the metal powder accounts for 40% to 89% of the solid content of the conductive composition, the conductive carbon material accounts for 0.1% to 5% of the solid content of the conductive composition, and the solvent is The weight percentage in the conductive composition is 25% to 40%.2.如权利要求1所述的导电组合物，其特征在于：所述聚合物树脂形成的弹性体的弹性回复率大于或等于95％。2 . The conductive composition according to claim 1 , wherein the elastic recovery rate of the elastomer formed by the polymer resin is greater than or equal to 95%. 3 .3.如权利要求1所述的导电组合物，其特征在于：所述聚合物树脂选自热塑性的苯乙烯嵌段共聚物、丁腈橡胶、聚氨酯树脂及聚二甲基硅氧烷树脂中的至少一种，所述导电碳材选自石墨烯、碳黑、碳纳米管、石墨粉、碳纤维及膨胀石墨中的至少一种。3. The conductive composition according to claim 1, wherein the polymer resin is selected from thermoplastic styrene block copolymer, nitrile rubber, polyurethane resin and polydimethylsiloxane resin. At least one, the conductive carbon material is selected from at least one of graphene, carbon black, carbon nanotubes, graphite powder, carbon fiber and expanded graphite.4.如权利要求1所述的导电组合物，其特征在于：每一金属粉中的多个所述分枝部朝向不同的方向。4 . The conductive composition of claim 1 , wherein a plurality of the branch portions in each metal powder face in different directions. 5 .5.如权利要求1所述的导电组合物，其特征在于：所述溶剂为沸点大于150℃的有机溶剂。5 . The conductive composition of claim 1 , wherein the solvent is an organic solvent with a boiling point greater than 150° C. 6 .6.一种导电薄膜，其特征在于，所述导电薄膜由如权利要求1至5任意一项所述的导电组合物干燥固化制得。6 . A conductive film, characterized in that, the conductive film is prepared by drying and curing the conductive composition according to any one of claims 1 to 5 .7.一种电路结构，其特征在于，所述电路结构包括如权利要求6所述的导电薄膜。7 . A circuit structure, wherein the circuit structure comprises the conductive film of claim 6 . 8 .8.一种可穿戴设备，其特征在于，所述可穿戴设备包括如权利要求7所述的电路结构。8 . A wearable device, wherein the wearable device comprises the circuit structure of claim 7 . 9 .