Hydroxyl graphene-modified plating sealants and preparation methods thereof

Abstract

A hydroxyl graphene-modified plating sealant and a preparation method thereof are disclosed. The plating sealant comprises a film-forming material, a resist, a defoaming agent, a levelling agent, and deionized water; the resist is a nanoscale hydroxyl graphene aqueous solution comprising hydroxyl graphene having a mass fraction of 3.5% to 4% and a pH of 8.0 to 9.5. Nanoscale hydroxyl graphene is used as a resist in the plating sealant of the disclosure, then the hydroxyl groups on hydroxyl graphene can react with the hydroxyl groups of the film-forming material, i.e. silica sol and the silane polymer, by dehydration condensation, thereby significantly improving the performance of the sealing film. The sealing film has higher corrosion resistance and abrasion resistance compared with that prepared by graphene or reduced graphene oxide sealant.

Claims

1. A hydroxyl graphene-modified plating sealant comprising components having the following parts by weight: TABLE-US-00002 film-forming material 40 to 60 parts; anti-corrosive agent 4 to 12 parts; deionized water 30 to 50 parts; wherein the resist is a nanoscale hydroxyl graphene aqueous solution comprising hydroxyl graphene having a mass fraction of 3.5% to 4.0%, and having a pH of 8.0 to 9.5; wherein a method of preparing hydroxyl graphene comprises: adding concentrated sulfuric acid and graphite into a reactor, preparing a graphene oxide by three-step oxidation at a low temperature, a medium temperature, and a high temperature using potassium permanganate as an oxidant in concentrated sulfuric acid, reducing excess potassium permanganate with hydrogen peroxide, removing sulfuric acid and salts in reaction products by electrodialysis, then adding 20% sodium hydroxide solution to pH of 11 to 12 to convert sulfated graphene into hydroxyl graphene, and removing excess sodium hydroxide by electrodialysis so as to obtain a hydroxyl graphene paste solution having a pH of 8.0 to 9.5; and the film-forming material is a mixture comprising a silica sol and one of organic film-forming materials such as a water-soluble silane polymer, a water-soluble polyurethane, and an acrylic resin.

2. The hydroxyl graphene-modified plating sealant according to claim 1, wherein the resist is a nanoscale hydroxyl graphene aqueous solution comprising hydroxyl graphene having a mass fraction of 3.8%.

3. The hydroxyl graphene-modified plating sealant according to claim 1, wherein the silica sol has a mass fraction ranging from 30% to 70% in the film-forming material.

4. The hydroxyl graphene-modified plating sealant according to claim 3, wherein the silica sol has a mass fraction ranging from 50% to 65% in the film-forming material.

5. The hydroxyl graphene-modified plating sealant according to claim 4, wherein the silica sol has a mass fraction of 60% in the film-forming material.

6. The hydroxyl graphene-modified plating sealant according to claim 3, wherein the silica sol has a nanoscale particle size and a pH of 9.0 to 9.5, and comprises silicon dioxide having a mass fraction of 40%.

7. The hydroxyl graphene-modified plating sealant according to claim 1, wherein the organic film-forming material is water-soluble silane polymer.

8. The hydroxyl graphene-modified plating sealant according to claim 7, wherein the water-soluble silane polymer has a product model PU 113.

9. The hydroxyl graphene-modified plating sealant according to claim 1 further comprising components having the following parts by weight: TABLE-US-00003 defoaming agent 0.4 to 0.6 parts; levelling agent 0.8 to 1.5 parts.

10. The hydroxyl graphene-modified plating sealant according to claim 9, wherein the defoaming agent is TANAFOAM S silicone defoaming agent having a mass fraction ranging from 46% to 49%.

11. The hydroxyl graphene-modified plating sealant according to claim 9, wherein the levelling agent is LA13-863 silicone leveling agent having a mass fraction of 25%.

12. A method of preparing a hydroxyl graphene-modified plating sealant according to claim 1, wherein the hydroxyl graphene-modified plating sealant is prepared by mixing respective raw materials together according to requirements on components and content of the sealant and uniformly stirring.

Description

DETAILED DESCRIPTION

(1) For better understanding the present disclosure, the present disclosure will be further specifically described by the following examples which should not to be construed as limiting the disclosure, and some non-essential improvements and adjustments made by those skilled in the art and based on the above-mentioned disclosure are also considered to fall within the protection scope of the present disclosure.

Example 1: Hydroxyl Graphene-Modified Plating Sealant

(2) Hydroxyl graphene-modified plating sealant of this example comprises the following components: film-forming material: 50 parts; resist: 4 parts; defoaming agent: 0.5 parts; levelling agent: 1 parts; deionized water: 40 parts.

(3) The film-forming material comprises a silica sol and a water-soluble silane polymer, the silica sol having a mass fraction of 60% in the film-forming material and the water-soluble silane polymer having a mass fraction of 40% in the film-forming material.

(4) The silica sol is industrial grade, comprises silicon dioxide having a mass fraction of 40%, and has a nanoscale particle size and a pH of 9.0 to 9.5. The water-soluble silane polymer is the water-soluble silane polymer with a product model PU 113 prepared by Dakin Chemical, Taiwan.

(5) The resist is a hydroxyl graphene paste aqueous solution having a pH of 8.0 to 9.5 and comprising hydroxyl graphene having a mass fraction of 3.8% and a nanoscale particle size.

(6) A method of preparing hydroxyl graphene is as follows:

(7) (1) low temperature oxidation: to a 1000 mL beaker was added 115 mL of concentrated sulfuric acid, the concentrated sulfuric acid was cooled to a temperature of 2 to 5 C. under an ice water bath, 5 g of 300-mesh flake graphite powder having a mass fraction of more than 99% was added, followed by 18 g of potassium permanganate slowly under stirring. The reaction was controlled at a temperature in the range of 2 to 10 C., and the mixture was reacted under stirring for 120 min;

(8) (2) medium temperature oxidation: the ice water bath was replaced with a warm water bath, the reaction was controlled at a temperature between 30 to 40 C., reacting under stirring for 90 min;

(9) (3) high temperature oxidation: the beaker was removed from the water bath after the medium temperature reaction, and the paste in the beaker was heated to 90 C. 100 mL of water was slowly added, the reaction was controlled at a temperature between 90 to 100 C., and the mixture was stirred for 30 min. 15 mL of 30% hydrogen peroxide was slowly added to the beaker, and reaction continued for 30 min;

(10) (4) sulfuric acid and salts in the reaction products were removed by electrodialysis, 20% sodium hydroxide solution was added to a pH of 11 to 12 to convert the sulfated graphene into hydroxyl graphene, and then the excess sodium hydroxide was removed by electrodialysis to obtain a hydroxyl graphene paste solution having a pH of 8.0 to 9.5.

(11) The defoaming agent is the TANAFOAM S silicone defoaming agent produced by Tuna, Netherlands and having a mass fraction of 46% to 49%.

(12) The levelling agent is the LA13-863 silicone levelling agent produced by Stahl, Netherlands and having a mass fraction of 25%.

(13) The respective materials were mixed together according to the above-mentioned requirement on components and content of the sealant, and stirred uniformly to obtain a hydroxyl graphene-modified plating sealant as described in this example.

(14) The specific process for preparing a plating piece and sealing the plating piece with the hydroxyl graphene-modified plating sealant of this example were as follows:

(15) (1) diluting the plating sealant 3 times with deionized water in a sealing bath to formulate a sealing solution;

(16) (2) barrel-plating a M8.030 screw having a material of steel A3 in a cyanide-free alkaline zinc plating bath, wherein the zinc plating has a thickness of 10 to 12 m;

(17) (3) passivating the plating piece with trivalent chrome blue-white passivation solution, washing with water and immersing in the sealing solution for 20 s, and drip-drying after taking out from the sealing bath;

(18) (4) blowing away the excess sealing solution on the surface of the plating piece by pressure-air, then baking at 80 C. for 40 min, and leaving for 24 h for aging.

(19) A neutral salt spray test was carried out according to ISO 9227: 2017 Corrosion Tests in Artificial AtmospheresSalt Spray Tests, white corrosion occurred on the surface of the plating after 312 h and red corrosion occurred on the surface of the plating after 648 h.

Example 2: Hydroxyl Graphene-Modified Plating Sealant

(20) Hydroxyl graphene-modified plating sealant of this example comprises the following components: film-forming material: 50 parts; resist: 10 parts; defoaming agent: 0.5 parts; levelling agent: 1 parts; deionized water: 40 parts.

(21) The film-forming material comprises a silica sol and a water-soluble silane polymer, the silica sol having a mass fraction of 60% in the film-forming material and the water-soluble silane polymer having a mass fraction of 40% in the film-forming material.

(22) The silica sol is industrial grade, comprises silicon dioxide having a mass fraction of 40%, and has a nanoscale particle size and a pH of 9.0 to 9.5. The water-soluble silane polymer is the water-soluble silane polymer with a product model PU 113 prepared by Dakin Chemical, Taiwan.

(23) The resist is a hydroxyl graphene paste aqueous solution having a pH of 8.0 to 9.5 and comprising hydroxyl graphene having a mass fraction of 3.8% and a nanoscale particle size.

(24) A method of preparing hydroxyl graphene is as follows.

(25) (1) low temperature oxidation: to a 1000 mL beaker was added 115 mL of concentrated sulfuric acid, the concentrated sulfuric acid was cooled to a temperature of 2 to 5 C. under an ice water bath, 5 g of 300-mesh flake graphite powder having a mass fraction of more than 99% was added, followed by 18 g of potassium permanganate slowly under stirring. The reaction was controlled at a temperature in the range of 2 to 10 C., and the mixture reacted under stirring for 120 min;

(26) (2) medium temperature oxidation: the ice water bath was replaced with a warm water bath, the reaction was controlled at a temperature between 30 to 40 C., and the mixture reacted under stirring for 90 min;

(27) (3) high temperature oxidation: the beaker was removed from the water bath after the medium temperature reaction, and the paste in the beaker was heated to 90 C. 100 mL of water was slowly added, the reaction was controlled at a temperature between 90 to 100 C., and the mixture was stirred for 30 min. 15 mL of 30% hydrogen peroxide was slowly added to the beaker, and reaction continued for 30 min;

(28) (4) sulfuric acid and salts in the reaction products were removed by electrodialysis, 20% sodium hydroxide solution was added to a pH of 11 to 12 to convert the sulfated graphene into hydroxyl graphene, and then the excess sodium hydroxide was removed by electrodialysis to obtain a hydroxyl graphene paste solution having a pH of 8.0 to 9.5.

(29) The defoaming agent is the TANAFOAM S silicone defoaming agent produced by Tuna, Netherlands and having a mass fraction of 46% to 49%.

(30) The levelling agent is the LA13-863 silicone levelling agent produced by Stahl, Netherlands and having a mass fraction of 25%.

(31) The respective materials were mixed together according to the above-mentioned requirement on components and content of the sealant, and stirred uniformly to obtain a hydroxyl graphene-modified plating sealant as described in the present disclosure.

(32) The specific process for preparing a plating piece and sealing the plating piece with the hydroxyl graphene-modified plating sealant of this example were as follows:

(33) (1) diluting the plating sealant 3 times with deionized water in a sealing bath to formulate a sealing solution;

(34) (2) barrel-plating a M8.030 screw having a material of steel A3 in a cyanide-free alkaline zinc plating bath, wherein the zinc plating has a thickness of 10 to 12 m;

(35) (3) passivating the plating piece with trivalent chrome blue-white passivation solution, washing with water and immersing in the sealing solution for 20 s, and drip-drying after taking out from the sealing bath;

(36) (4) blowing away the excess sealing solution on the surface of the plating piece by pressure-air, then baking at 80 C. for 40 min, and leaving for 24 h for aging.

(37) A neutral salt spray test was carried out according to ISO 9227: 2017 Corrosion Tests in Artificial AtmospheresSalt Spray Tests, white corrosion occurred on the surface of the plating after 320 h and red corrosion occurred on the surface of the plating after 672 h.

(38) Comparing Examples 1 and 2, it can be seen that when the content of hydroxyl graphene in the plating sealant is increased from 4 parts to 10 parts, in the neutral salt spray test, the time when the white corrosion occurred on the plating increases by 8 h, and the time when the red corrosion occurred on the plating layer increases by 24 h.

Example 3: Hydroxyl Graphene-Modified Plating Sealant

(39) Hydroxyl graphene-modified plating sealant of this example comprises the following components: film-forming material: 50 parts; resist: 4 parts; defoaming agent: 0.5 parts; levelling agent: 1 parts; deionized water: 40 parts.

(40) The film-forming material comprises a silica sol and a water-soluble polyurethane, the silica sol having a mass fraction of 60% in the film-forming material and the water-soluble polyurethane having a mass fraction of 40% in the film-forming material.

(41) The silica sol is industrial grade, comprises silicon dioxide having a mass fraction of 40%, and has a nanoscale particle size and a pH of 9.0 to 9.5.

(42) The resist is a hydroxyl graphene paste aqueous solution having a pH of 8.0 to 9.5 and comprising hydroxyl graphene having a mass fraction of 3.8% and a nanoscale particle size.

(43) A method of preparing hydroxyl graphene is as Example 1.

(44) The defoaming agent is the TANAFOAM S silicone defoaming agent produced by Tuna, Netherlands and having a mass fraction of 46% to 49%.

(45) The levelling agent is the LA13-863 silicone levelling agent produced by Stahl, Netherlands and having a mass fraction of 25%.

(46) The respective materials were mixed together according to the above-mentioned requirement on components and content of the sealant, and stirred uniformly to obtain a hydroxyl graphene-modified plating sealant as described in this example.

(47) The specific process for preparing a plating piece and sealing the plating piece with the hydroxyl graphene-modified plating sealant of this example were as follows:

(48) (1) diluting the plating sealant 3 times with deionized water in a sealing bath to formulate a sealing solution;

(49) (2) barrel-plating a M8.030 screw having a material of steel A3 in a cyanide-free alkaline zinc plating bath, wherein the zinc plating has a thickness of 10 to 12 m;

(50) (3) passivating the plating piece with trivalent chrome blue-white passivation solution, washing with water and immersing in the sealing solution for 20 s, and drip-drying after taking out from the sealing bath;

(51) (4) blowing away the excess sealing solution on the surface of the plating piece by pressure-air, then baking at 80 C. for 40 min, and leaving for 24 h for aging.

(52) A neutral salt spray test was carried out according to ISO 9227: 2017 Corrosion Tests in Artificial AtmospheresSalt Spray Tests, white corrosion occurred on the surface of the plating after 288 h.

Example 4: Hydroxyl Graphene-Modified Plating Sealant

(53) Hydroxyl graphene-modified plating sealant of this example comprises the following components: film-forming material: 50 parts; resist: 4 parts; defoaming agent: 0.5 parts; levelling agent: 1 parts; deionized water: 40 parts.

(54) The film-forming material comprises a silica sol and an acrylic resin, the silica sol having a mass fraction of 60% in the film-forming material and the acrylic resin having a mass fraction of 40% in the film-forming material.

(55) The silica sol is industrial grade, comprises silicon dioxide having a mass fraction of 40%, and has a nanoscale particle size and a pH of 9.0 to 9.5.

(56) The resist is a hydroxyl graphene paste aqueous solution having a pH of 8.0 to 9.5 and comprising hydroxyl graphene having a mass fraction of 3.8% and a nanoscale particle size.

(57) A method of preparing hydroxyl graphene is as Example 1.

(58) The defoaming agent is the TANAFOAM S silicone defoaming agent produced by Tuna, Netherlands and having a mass fraction of 46% to 49%.

(59) The levelling agent is the LA13-863 silicone levelling agent produced by Stahl, Netherlands and having a mass fraction of 25%.

(60) The respective materials were mixed together according to the above-mentioned requirement on components and content of the sealant, and stirred uniformly to obtain a hydroxyl graphene-modified plating sealant as described in this example.

(61) The specific process for preparing a plating piece and sealing the plating piece with the hydroxyl graphene-modified plating sealant of this example were as follows:

(62) (1) diluting the plating sealant 3 times with deionized water in a sealing bath to formulate a sealing solution;

(63) (2) barrel-plating a M8.030 screw having a material of steel A3 in a cyanide-free alkaline zinc plating bath, wherein the zinc plating has a thickness of 10 to 12 m;

(64) (3) passivating the plating piece with trivalent chrome blue-white passivation solution, washing with water and immersing in the sealing solution for 20 s, and drip-drying after taking out from the sealing bath;

(65) (4) blowing away the excess sealing solution on the surface of the plating piece by pressure-air, then baking at 80 C. for 40 min, and leaving for 24 h for aging.

(66) A neutral salt spray test was carried out according to ISO 9227: 2017 Corrosion Tests in Artificial AtmospheresSalt Spray Tests, white corrosion occurred on the surface of the plating after 276 h.

Comparative Example 1: Conventional Plating Sealant without Hydroxyl Graphene

(67) The conventional plating sealant having no hydroxyl graphene described in this comparative example was prepared with the following raw materials: film-forming material: 50 parts; defoaming agent: 0.5 parts; levelling agent: 1 parts; deionized water: 40 parts.

(68) The raw materials used in the sealing agent of this comparative example were the same as that in Example 1 except the hydroxyl graphene, and the preparation method was also the same as that in Example 1.

(69) The processes of preparing and sealing the plating piece were the same as those in Example 1.

(70) After the neutral salt spray test was carried out for 72 h according to the ISO 9227: 2017 Corrosion Tests in Artificial AtmospheresSalt Spray Tests, white corrosion occurred on the surface of the plating.

(71) The results of Examples 1 and 2 showed that after 312 to 320 h in the neutral salt spray test, white corrosion occurred on the plating piece sealed with the hydroxyl graphene-modified plating sealant, but in Comparative Example 1, only for 72 h after the neutral salt spray test the white corrosion occurred on the surface of the plating. It can be seen that by using hydroxyl graphene as a resist, the corrosion resistance of the plating piece can be significantly increased.

Comparative Example 2: Sealing Agent with the Addition of Graphene (GNP)

(72) The sealing agent with the addition of graphene for this comparative example was prepared with the following raw materials: film-forming material: 50 parts; resist: 10 parts; defoaming agent: 0.5 parts; levelling agent: 1 parts; deionized water: 40 parts.

(73) Graphene was used as the resist: a graphene paste aqueous solution having a pH of 6.5 to 7.0 and comprising graphene having a mass fraction of 3.8% and a nanoscale particle size was formulated using sodium dodecyl sulfonate as an emulsifier.

(74) The other components were the same as that in Example 1, the preparation method was the same as that in Example 1, the processes of preparing and sealing the plating piece were the same as those in Example 1.

(75) After the neutral salt spray test was carried out for 224 h according to the ISO 9227: 2017 Corrosion Tests in Artificial AtmospheresSalt Spray Tests, white corrosion occurred on the surface of the plating.

(76) The results of Example 2 show that white corrosion occurred on the plating piece sealed with the hydroxyl graphene sealant in the neutral salt spray test after 320 h, while white corrosion occurred after 224 h in Comparative Example 2. It can be seen that by using hydroxyl graphene as a resist, the corrosion resistance of the plating piece can be significantly increased.

(77) After the sealing solution of Comparative Example 2 was left for 1 week, graphene was completely sunk into the bottom of the sealing solution, indicating that the sealing solution of Comparative Example 2 was unstable and could not be used for industrial production.

(78) Each of the technical features of the above-described embodiments may be combined arbitrarily. To simplify the description, not all of the possible combinations of each of the technical features in the above embodiments are described. However, all of the combinations of these technical features should be considered as within the scope of the present specification, as long as such technical features do not contradict with each other.

(79) The above-described examples merely represent several embodiments of the present disclosure, and the description thereof is more specific and detailed, but it should not be construed as limiting the scope of the present disclosure. It should be noted that, for those skilled in the art, several variations and improvements may be made without departing from the concept of the present disclosure, and these are all within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the appended claims.