阅读说明：本技术 一种可重复使用的环保型导电胶黏剂 (Reusable environment-friendly conductive adhesive ) 是由 吴慧 汤祖武 赵梦婵 卢生昌 张敏 肖禾 刘凯 曾宏波 黄六莲 陈礼辉 于 2021-08-10 设计创作，主要内容包括：本发明公开了一种可重复使用的环保型导电胶黏剂,其是将没食子酸用沸水溶解,再将纳米纤维素分散在聚乙烯吡咯烷酮中,然后将所得没食子酸溶液与纳米纤维素/聚乙烯吡咯烷酮分散液混合,得到可重复使用的环保型导电胶黏剂。本发明将生物相容性的没食子酸、纳米纤维素和聚乙烯吡咯烷酮三者复配,制备具有可重复使用及良好导电性能的环保胶粘剂,其可应用于家具、建筑、电子等领域。(The invention discloses a reusable environment-friendly conductive adhesive, which is prepared by dissolving gallic acid in boiling water, dispersing nanocellulose in polyvinylpyrrolidone, and mixing the obtained gallic acid solution with a nanocellulose/polyvinylpyrrolidone dispersion solution. The invention compounds biocompatible gallic acid, nanocellulose and polyvinylpyrrolidone to prepare the reusable environment-friendly adhesive with good conductivity, which can be applied to the fields of furniture, buildings, electronics and the like.)

1. The reusable environment-friendly conductive adhesive is characterized in that: the preparation method comprises the following steps:

a. dissolving gallic acid in boiling water to obtain gallic acid solution;

b. dispersing nano-cellulose in polyvinylpyrrolidone to form nano-cellulose/polyvinylpyrrolidone dispersion liquid;

c. and adding the prepared gallic acid solution into the nano-cellulose/polyvinylpyrrolidone dispersion, and blending to obtain the reusable environment-friendly conductive adhesive.

2. The electrically conductive adhesive of claim 1, wherein: the concentration of the gallic acid solution obtained in the step a) is 1-30 wt%.

3. The electrically conductive adhesive of claim 1, wherein: the mass ratio of the gallic acid to the polyvinylpyrrolidone in the step c) is 1: 1.

4. The electrically conductive adhesive of claim 1, wherein: the content of polyvinylpyrrolidone in the obtained environment-friendly conductive adhesive is 20-35 wt%, and the content of nanocellulose is 0-8.5 wt%.

5. The electrically conductive adhesive of claim 1, wherein: the nano-cellulose comprises cellulose nano-crystal, cellulose nano-fiber, microcrystalline cellulose, bacterial cellulose and TEMPO oxidized cellulose nano-fiber.

Technical Field

The invention relates to a conductive adhesive, in particular to an environment-friendly conductive adhesive capable of being repeatedly used.

Background

The adhesive can connect two or more homogeneous or heterogeneous workpieces or materials together, and is widely applied to the fields of electronic industry, biomedical treatment, biosensing, wood processing, building and the like. Conductive adhesives synthesized today are mainly added with conductive materials such as gold, silver, nickel and carbon materials. Although they have good electrical conductivity, they lack reusability. Therefore, the development of an adhesive with reusability and good conductive performance is a problem to be solved urgently.

The cellulose is a natural organic polymer, and has the advantages of low price, easy obtainment, environmental friendliness, excellent biocompatibility and the like. Gallic acid is an organic acid, and has wide source and biocompatibility. Polyvinylpyrrolidone is widely used for glue, anticorrosion, antifouling and anti-biofilm surface coatings. Therefore, the gallic acid, the nano-cellulose and the polyvinylpyrrolidone are compounded to prepare the reusable environment-friendly conductive adhesive, and the reusable environment-friendly conductive adhesive can be applied to the fields of electronic products and the like.

Disclosure of Invention

The invention aims to provide a reusable environment-friendly conductive adhesive which has good conductive performance and can be applied to the fields of furniture, buildings, electronics and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

the preparation method of the reusable environment-friendly conductive adhesive comprises the following steps:

a. dissolving gallic acid in boiling water to obtain gallic acid solution;

b. dispersing nano-cellulose in polyvinylpyrrolidone to form nano-cellulose/polyvinylpyrrolidone dispersion liquid;

c. and adding the prepared gallic acid solution into the nano-cellulose/polyvinylpyrrolidone dispersion, and blending to obtain the reusable environment-friendly conductive adhesive.

The concentration of the gallic acid solution obtained in the step a) is 1-30 wt%.

The mass ratio of the gallic acid to the polyvinylpyrrolidone in the step c) is 1: 1.

The content of polyvinylpyrrolidone in the obtained environment-friendly conductive adhesive is 20-35 wt%, and the content of nanocellulose is 0-8.5 wt%.

The nano-cellulose comprises cellulose nano-crystal, cellulose nano-fiber, microcrystalline cellulose, bacterial cellulose and TEMPO oxidized cellulose nano-fiber.

The invention has the advantages that:

according to the invention, the biocompatible gallic acid, the nanocellulose and the polyvinylpyrrolidone are compounded through the hydrogen bond, so that the obtained adhesive has good environmental friendliness, reusability and conductivity, and can be applied to the fields of furniture, buildings, electronics and the like. Wherein, the polyvinylpyrrolidone is used as the skeleton of the composite adhesive to provide adhesiveness, and the nitrogen and oxygen on the tertiary amide are used as hydrogen acceptors to form hydrogen bonds with the gallic acid. The use of gallic acid is favorable for improving the conductivity of the composite adhesive, and the use of the nanocellulose can further improve the adhesive strength of the composite adhesive.

Drawings

FIG. 1 is a graph showing the effect of different CNC contents on the adhesive strength of PVP/GA/CNC composite adhesive.

FIG. 2 is a graph of the effect of different CNC contents on the conductivity of the PVP/GA/CNC composite adhesive.

FIG. 3 is a diagram showing the influence of different mass ratios of PVP/GA to the conductivity of the PVP/GA/CNC composite adhesive.

Fig. 4 is a graph showing the results of the reusability test of the conductive adhesive prepared in example 6.

Fig. 5 is a graph showing the conductivity of the conductive adhesive prepared in example 6 in wet state (a) and dry state (b).

Detailed Description

The reusable environment-friendly conductive adhesive comprises the following steps:

a. dissolving gallic acid in boiling water to obtain gallic acid solution;

b. dispersing nano-cellulose in polyvinylpyrrolidone to form nano-cellulose/polyvinylpyrrolidone dispersion liquid;

c. and adding the prepared gallic acid solution into the nano-cellulose/polyvinylpyrrolidone dispersion, and blending to obtain the reusable environment-friendly conductive adhesive.

The concentration of the gallic acid solution obtained in the step a) is 1-30 wt%.

The mass ratio of the gallic acid to the polyvinylpyrrolidone in the step c) is 1: 1.

The content of polyvinylpyrrolidone in the obtained environment-friendly conductive adhesive is 20-35 wt%, and the content of nanocellulose is 0-8.5 wt%.

The nano-cellulose comprises cellulose nano-crystal, cellulose nano-fiber, microcrystalline cellulose, bacterial cellulose and TEMPO oxidized cellulose nano-fiber.

1. The adhesive strength of the PVP/GA/CNC composite adhesive prepared by different CNC contents is tested, specifically, the PVP/GA/CNC composite adhesive prepared by different CNC contents (0%, 1.0%, 2.1%, 3.2%, 4.3%, 5.6%, 7.0%, 8.5%) is coated on the surface of an iron sheet, an aluminum sheet, wood or glass, another same material with the same size is covered on the PVP/GA/CNC composite adhesive, the adhesive strength of the PVP/GA/CNC composite adhesive is tested by an experimental tensile machine after the PVP/GA/CNC composite adhesive is cured for 48 hours at normal temperature, and the result is shown in figure 1.

As can be seen from the results of FIG. 1, the adhesive strength of the composite adhesive containing 0% CNC on iron sheets, aluminum sheets, wood and glass was 0.33 MPa, 0.73 MPa, 3.19 MPa and 3.82MPa, respectively. With the increase of the CNC content, the adhesive strength of the composite adhesive is increased, and the adhesive strength of the composite adhesive with the CNC content of 5.6% on iron sheets, aluminum sheets, wood and glass reaches the maximum value, namely 0.93 MPa, 3.03 MPa, 4.39 MPa and 4.91MPa respectively. And the adhesive strength gradually decreases with further increase of the CNC content. This is because excessive CNC disrupts the hydrogen bond balance between CNC, PVP and GA, resulting in a decrease in adhesive strength.

2. The conductivity of the PVP/GA/CNC composite adhesive prepared with different CNC contents was tested with a four-point probe, and the results are shown in fig. 2.

As can be seen from the results of FIG. 2, the conductivity of the composite adhesive with a CNC content of 0wt% was 6.0X 10^-4S/cm. The conductivity does not change greatly with the increase of the CNC content and is 6.0 multiplied by 10^-4S/cm to 7.0X 10^-4And the S/cm is smaller, so that the influence of the addition of the CNC on the conductivity of the composite adhesive is small.

3. The influence of different mass ratios of PVP/GA on the conductivity of the PVP/GA/CNC composite adhesive is explored by adopting a four-point probe, and the result is shown in figure 3.

From the results in FIG. 3, it can be seen that when the mass ratio of PVP to GA is 1:0.2, the conductivity of the obtained composite adhesive is 2.5 × 10^-4S/cm. As GA mass increases, conductivity increases. When the mass ratio of PVP to GA is 1.0:1.0, the conductivity of the composite adhesive reaches the maximum value of 6.5 multiplied by 10^-4S/cm. And as the GA quality further increases, the conductivity decreases.

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Adding the obtained gallic acid solution into 10g of 10% polyvinylpyrrolidone aqueous solution, stirring for 15 min, soaking with large amount of deionized water for 48 hr to obtain 3.0g of solution with weightThe reused conductive adhesive has the adhesive strength of 3.82MPa (glass) and the conductivity of 6.0 multiplied by 10^-4 S/cm。

Example 2

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 1.45g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form nanocellulose/polyvinylpyrrolidone dispersion liquid. Adding the obtained gallic acid solution into nano-cellulose/polyvinylpyrrolidone dispersion, stirring for 15 min, and soaking in deionized water for 48 hr to obtain about 3.8g of reusable conductive adhesive with adhesive strength of 3.87MPa (glass) and conductivity of 6.2 × 10^-4 S/cm。

Example 3

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 3.01g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form nanocellulose/polyvinylpyrrolidone dispersion liquid. Adding the obtained gallic acid solution into nano-cellulose/polyvinylpyrrolidone dispersion, stirring for 15 min, and soaking in deionized water for 48 hr to obtain about 3.8g of reusable conductive adhesive with adhesive strength of 4.5MPa (glass) and conductivity of 6.4 × 10^-4 S/cm。

Example 4

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 4.69g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form nanocellulose/polyvinylpyrrolidone dispersion liquid. Adding the obtained gallic acid solution into nano cellulose/polyvinylpyrrolidone dispersion, stirring for 15 min, soaking in deionized water for 48 hr to obtain 3.9g of solution with a certain weightThe reused conductive adhesive has the adhesive strength of 4.53MPa (glass) and the conductivity of 6.5 multiplied by 10^-4 S/cm。

Example 5

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 6.50g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form nanocellulose/polyvinylpyrrolidone dispersion liquid. Adding the obtained gallic acid solution into nano-cellulose/polyvinylpyrrolidone dispersion, stirring for 15 min, and soaking in a large amount of deionized water for 48 hr to obtain about 4.0g of reusable conductive adhesive with adhesive strength of 4.58MPa (glass) and conductivity of 6.4 × 10^-4 S/cm。

Example 6

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 8.47g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form a nanocellulose/polyvinylpyrrolidone dispersion liquid. Adding the obtained gallic acid solution into nano-cellulose/polyvinylpyrrolidone dispersion, stirring for 15 min, and soaking in a large amount of deionized water for 48 hr to obtain about 4.1g of reusable conductive adhesive with adhesive strength of 4.91MPa (glass) and conductivity of 6.5 × 10^-4 S/cm。

1. The conductive adhesive prepared in example 6 was subjected to a reuse test, in which the prepared adhesive was coated on the surface of one glass, another glass having the same size was covered thereon, and after curing at room temperature for 48 hours, the adhesive strength was measured with an experimental tensile machine. And placing the glass after being pulled open in water for a few minutes, closing again, curing at normal temperature for 48 hours, and measuring the adhesive strength. The adhesive strength was calculated after repeating the cycle several times, and the results are shown in FIG. 4.

As can be seen from the results of fig. 4, the maximum adhesive strength measured after the first adhesion is 4.91MPa, and the adhesive strength after repeated adhesion can still reach 4.69MPa, which proves that the adhesive has good adhesion characteristics and can be reused.

2. The conductive adhesives prepared in example 6 were tested for conductivity in both the wet and dry states. In a simple circuit of a Light Emitting Diode (LED) bulb and two dry cells, the conductive adhesive can serve as a conductive device to illuminate the LED, as shown in fig. 5 a. The reason is that the gallic acid can be ionized to generate phenoxy ions, carboxylate ions and hydrogen ions, so that ion conduction channels can be formed, the ion conduction channels can conduct electricity, and the conductive adhesive has conductivity.

Meanwhile, as shown in b in fig. 5, the conductive adhesive is attached to the two iron sheets and can bear a weight of 400g after being cured for 48 hours. And when the wall is connected to a closed circuit, the LED bulb is illuminated. This shows that the conductive adhesive at the interface not only has strong adhesive strength, but also has good conductivity in a dry state.

Example 7

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 10.62g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form nanocellulose/polyvinylpyrrolidone dispersion liquid. Adding the obtained gallic acid solution into nano-cellulose/polyvinylpyrrolidone dispersion, stirring for 15 min, and soaking in a large amount of deionized water for 48 hr to obtain about 4.1g of reusable conductive adhesive with adhesive strength of 3.63MPa (glass) and conductivity of 6.6 × 10^-4 S/cm。

Example 8

Adding 1g of gallic acid into 10g of deionized water, heating to 100 ℃ by using an oil bath pan, and stirring for 30 minutes to obtain the gallic acid solution. Dispersing 12.96g of cellulose nanocrystalline colloid with the mass fraction of 2.68wt% in 10g of polyvinylpyrrolidone aqueous solution with the mass fraction of 10%, stirring for 15 minutes and carrying out ultrasonic treatment for 30 minutes to form a nanocellulose/polyvinylpyrrolidone dispersion liquid. Mixing the obtained extract with waterThe seed acid solution is added into the nano-cellulose/polyvinylpyrrolidone dispersion liquid, stirred for 15 minutes and soaked in a large amount of deionized water for 48 hours to obtain about 4.2g of reusable conductive adhesive, the adhesive strength of the conductive adhesive is 3.44MPa (glass), and the conductivity of the conductive adhesive is 6.5 multiplied by 10^-4 S/cm。

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.