Water-based conductive liquid for plastic coating pretreatment and preparation method of water-based conductive liquid

Abstract

The invention discloses a water-based conductive liquid for plastic coating pretreatment. The water-based conductive liquid is prepared from the following components in parts by weight: 5.0 to 25.0 percent of conductive base liquid, 3.0 to 15.0 percent of wetting agent, 15.0 to 45.0 percent of solubilizer, 5.0 to 25.0 percent of emulsifier, 0.5 to 3.0 percent of defoaming agent, 0.05 to 0.5 percent of bactericide and the balance of pure water. The conductive liquid has the beneficial effects that the resistance of the ABS PP workpiece treated by the conductive water is less than 10 megohms, a water film on the surface of the treated workpiece is uniform before the treated workpiece enters a baking oven, the treated workpiece is well matched with paint, various test requirements of the paint are met, and after the blended conductive liquid is used for spraying or soaking the workpiece to be treated, the surface of the workpiece is not damaged. A layer of water film with good wettability is formed on the surface of the workpiece and enters a drying furnace, the dried workpiece directly enters a spraying link after having certain conductivity, and the coating requirement of the workpiece is met by adopting electrostatic spraying.

Description

Technical Field

[0001] The invention relates to the technical field of conductive agents, and in particular to an aqueous conductive liquid for pre-treatment of plastics for coating and a preparation method thereof. Background Art

[0002] At present, the main materials for bumpers or decorative parts of automobiles, motorcycles and other products are ABS or PP. In the subsequent painting process, this type of material can only be painted by traditional air spraying or by spraying a layer of conductive primer before using electrostatic spraying because the plastic itself is not conductive.

[0003] Advantages of electrostatic spraying: paint utilization rate is as high as 80-90%, and the economic benefits are good; the dead corners and inner edges of the workpiece can be painted well, and the qualified rate of finished products is high.

[0004] Disadvantages of air spraying: paint utilization rate is as low as 30-60%, resulting in large waste; the paintability is poor at the dead corners and inner edges of the workpiece, and the qualified rate of finished products is low.

[0005] The spraying of conductive primer has the disadvantages of high cost, high requirements on tooling and difficulty in construction, and has long been criticized by manufacturers.

[0006] Therefore, a method is proposed in which a conductive agent is added to the last water washing tank before painting without changing the factory production process. After the workpiece is treated with the conductive agent and dried, a conductive film layer can be formed on its surface, which is conducive to the subsequent electrostatic spraying. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides an aqueous conductive liquid for plastic pretreatment before coating and a preparation method thereof.

[0008] The technical scheme is as follows: an aqueous conductive liquid for pre-treatment of plastic coating, the main points of which are that it includes the following components in parts by weight:

[0009] Conductive base liquid: 5.0-25.0%;

[0010] Wetting agent: 3.0-15.0%;

[0011] Solubilizer: 15.0-45.0%;

[0012] Emulsifier: 5.0-25.0%;

[0013] Defoaming agent: 0.5-3.0%;

[0014] Fungicide: 0.05-0.5%;

[0015] Pure water: Balance

[0016] Preferably, the conductive base liquid is at least one of polyacetylene, polypyrrole, polyphenylene and polyphenylene vinylene.

[0017] Preferably: the wetting agent is fatty alcohol polyoxyethylene ether.

[0018] Preferably: the solubilizer is a solubilizer of M series.

[0019] Preferably: the emulsifier is emulsifier A series.

[0020] Preferably: the defoaming agent is Foamex830.

[0021] Preferably, the bactericide is at least one of BK and MBM.

[0022] A method for preparing an aqueous conductive liquid for pre-treatment of plastic coating comprises the following steps:

[0023] S1: Add all the solubilizing agent M into the reactor;

[0024] S2: Open the reactor, add polyacetylene, polypyrrole, polyphenylene, and polyphenylene vinylene into the reactor in sequence, and stir to react for 2 hours;

[0025] S3: slowly add emulsifier to the reactor and stir for 1 hour;

[0026] S4: Add the remaining pure water to the reactor 5 times on average, adding the pure water dropwise each time, the adding time shall not be less than 30 minutes, and stirring shall be performed for 2 hours after each addition;

[0027] S5: Add BK and MBM into the reactor in sequence and stir to react.

[0028] Compared with the prior art, the invention has the following beneficial effects: the resistance of the ABS PP workpiece after the conductive water treatment is less than 10MΩ. The water film on the surface of the treated workpiece is uniform before entering the oven. It has good matching performance with the paint and meets various test requirements of the paint.

[0029] After the blended conductive liquid is sprayed or soaked on the workpiece to be treated, a layer of water film with good wettability is formed on its surface and then enters the drying furnace. After the workpiece has a certain conductivity after drying, it directly enters the spraying stage and adopts electrostatic spraying to complete its coating requirements. DETAILED DESCRIPTION

[0030] Example 1

[0031] The components and proportions of an aqueous conductive liquid for pre-treatment of plastic coating are shown in Table 1 below:

[0032] Table 1 Components of Example 1

[0033]

[0034] A specific preparation process of an aqueous conductive liquid for plastic pre-treatment includes the following steps:

[0035] S1: Add solubilizer M series into the reactor;

[0036] S2: start the reactor;

[0037] S3: Add polyacetylene, polypyrrole, polyphenylene and polyphenylene vinylene into the reaction kettle in sequence, and stir to react for 2 hours;

[0038] S4: Add fatty alcohol polyoxyethylene ether and stir for 10 minutes;

[0039] S5: slowly add emulsifier series A and stir for 1 hour;

[0040] S6: Add Foamex830 and stir for 10 minutes;

[0041] S:7: The remaining pure water is added in 5 times on average, and the pure water is added dropwise each time. The adding time shall not be less than 30 minutes, and stirring shall be performed for 2 hours after each addition;

[0042] S8: Add BK and MBM to the reactor in sequence, stir for 1 hour and then take samples for testing to obtain the aqueous conductive liquid.

[0043] Embodiment 2-5

[0044] Compared with Example 1, the components and proportions of Example 2-5 are different, but the preparation methods are the same. The components and proportions of Example 2-5 are shown in Table 2 below:

[0045] Table 2 Components of Examples 2-5

[0046]

[0047] Test example

[0048] Test Example 1 Determination of Partial Base Liquid

[0049] The conductive base liquids with conductive properties are polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylene vinylene and polyaniline. After preparing them into aqueous solutions, they are sprayed on the test plates to evaluate them from the appearance and resistance. The appearance evaluation method is whether the water film is continuous and there is no spot after drying; the resistance evaluation method is that the resistance of the treated workpiece is less than 10MΩ. The results are shown in Table 3 below:

[0050] Table 3 Conductive base liquid test results

[0051]

[0052]

[0053] Conclusion: Polyacetylene, polypyrrole, polyphenylene and polyphenylene vinylene meet the design requirements and can be screened in the next step.

[0054] The dosage ratio test was conducted on the selected conductive base liquids of polyacetylene, polypyrrole, polyphenylene and polyphenylene vinylene, and they were evaluated in terms of appearance, resistance and paint film matching. The evaluation methods of appearance and resistance were consistent with the above, and the evaluation method of paint film matching was adhesion level 0. The test results are shown in Table 4 below:

[0055] Table 4 Conductive base liquid ratio test results

[0056] serial number Polyacetylene Polypyrrole Polyphenylene Polyphenylene vinylene Appearance Resistance MΩ Adhesion 1# 6 1 0.5 0.3 10s, evenly 10 qualified 2# 6 3 1.0 0.6 16s, even 8 qualified 3# 6 5 1.5 1.0 20s, evenly 6 qualified 4# 4 1 1.0 1.0 18s, even 12 qualified 5# 4 3 1.5 0.3 18s, even 9 qualified 6# 4 5 0.5 0.6 12s, even 8 qualified 7# 2 1 1.5 0.6 22s, even 15 qualified 8# 2 3 0.5 1.0 15s, evenly 12 qualified 9# 2 5 1.0 0.3 15s, evenly 10 qualified

[0057] Conclusion: The content of polyacetylene and polypyrrole has a great influence on conductivity. The higher the content, the smaller the resistance. Polyphenylene and polyphenylene vinylene have a great influence on the uniformity retention time of the water film. The higher the content, the longer the water film retention time. The optimal composition of the conductive base liquid is preliminarily determined to be 3# scheme.

[0058] After screening the proportion of the conductive agent, confirm the optimal ratio range of the solubilizer and emulsifier:

[0059] Solubilizer: Solubilizer M series (total amount is 40.0-45.0%);

[0060] Emulsifier: Emulsifier A series (total amount is 5.0-10.0%).

[0061] Passed the bacterial test and the original solution was stable after 6 months without the growth of bacteria and fungi.

[0062] Bactericide: BK 0.01-0.03% MBM 0.01-0.03%.

[0063] Test Example 2: Detection of aqueous conductive liquid

[0064] 1. Mix the prepared water-based conductive liquid product with pure water at a ratio of 10%, put it into a spray pot, and spray it on the surface of the degreased plastic parts. After observation, the water film is uniform and can be maintained for less than 20 seconds without breaking.

[0065] 2. After drying the ABS PP workpiece treated with conductive liquid, its surface resistance is tested. The tested resistance value is 8MΩ, which meets the design requirements.

[0066] 3. After drying the ABS PP workpiece treated with conductive liquid, spray electrostatic paint and then test its adhesion. The test results are shown in Table 5 below:

[0067] Table 5 Aqueous Conductive Liquid Test Results

[0068]

[0069] The resistance of the ABS PP workpiece after conductive water treatment is less than 10MΩ, and the water film on the surface of the treated workpiece is uniform before entering the oven. It has good matching performance with the paint and meets all the test requirements of the paint.

[0070] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, ordinary technicians in this field can make various similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the scope of protection of the present invention.

Claims

1. An aqueous conductive liquid for pre-treatment of plastics for coating, characterized in that: The composition includes the following parts by weight: Conductive base liquid: 5.0-25.0%; Wetting agent: 3.0-15.0%; Solubilizer: 15.0-45.0%; Emulsifier: 5.0-25.0%; Defoaming agent: 0.5-3.0%; Fungicide: 0.05-0.5%; Pure water: balance.

2. The aqueous conductive liquid for plastic pre-treatment according to claim 1, characterized in that: The conductive base liquid is at least one of polyacetylene, polypyrrole, polyphenylene and polyphenylene vinylene.

3. The aqueous conductive liquid for plastic pretreatment according to claim 1, characterized in that: The wetting agent is fatty alcohol polyoxyethylene ether.

4. The aqueous conductive liquid for plastic pretreatment according to claim 1, characterized in that: The solubilizer is a solubilizer M series.

5. The aqueous conductive liquid for plastic pre-treatment according to claim 1, characterized in that: The emulsifier is emulsifier A series.

6. The aqueous conductive liquid for plastic pre-treatment according to claim 1, characterized in that: The defoaming agent is Foamex830.

7. The aqueous conductive liquid for plastic pre-treatment according to claim 1, characterized in that: The bactericide is at least one of BK and MBM.

8. A method for preparing an aqueous conductive liquid as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1: adding a solubilizing agent into the reactor; S2: Open the reactor, add the conductive base liquid into the reactor, and stir to react; S3: Add wetting agent and stir to react; S4: slowly add emulsifier to the reactor and stir; S5: add defoamer and stir to react; S6: Add the remaining pure water into the reactor 5 times; S7: Add fungicides into the reactor in sequence and stir to react.

9. The method for preparing an aqueous conductive liquid for plastic pretreatment according to claim 8, characterized in that: The stirring time in step S2 is 2 hours; the stirring time in step S3 is 10 minutes; the stirring reaction time in step S4 is 1 hour, and the stirring reaction time in step S5 is 1 hour; the stirring time in step S6 is 10 minutes;.

10. The method for preparing an aqueous conductive liquid for plastic pre-treatment according to claim 8, characterized in that: In the step S6, the pure water is added dropwise.

11. A method for preparing an aqueous conductive liquid for plastic pre-treatment according to claim 10, characterized in that: The time for adding pure water should not be less than 30 minutes each time, and the reaction should be stirred for 2 hours after each addition.

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