High-conductivity and high-adhesion primer composition for PP (polypropylene) and preparation method of high-conductivity and high-adhesion primer composition

Abstract

The invention relates to a high-conductivity high-adhesion primer composition for PP (polypropylene) and a preparation method thereof. The primer composition is prepared from the following raw materials in parts by mass: 40-60 parts of thermoplastic acrylic resin, 1-10 parts of modified polypropylene, 12-24 parts of modified titanium dioxide, 1-5 parts of white carbon black, 1-2 parts of a dispersing agent, 0.1-0.5 part of a defoaming agent, 0.1-1 part of a flatting agent and 25-40 parts of a solvent. According to the invention, titanium dioxide is modified by reduced graphene oxide, the modified titanium dioxide is good in dispersity, and meanwhile, the conductivity of the primer composition is improved by utilizing the conductivity of the reduced graphene oxide, so that electrostatic spraying of finish paint is realized; the modified polypropylene is used as a bridge for the adhesion of the PP substrate and the primer composition, and the adhesion of the primer composition and the PP substrate can be obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a high-conductivity and high-adhesion primer composition for PP and a preparation method thereof. BACKGROUND

[0002] Under the industry trend of automobile lightweight, the proportion of plastics in automobile parts is increasing due to its light weight, wide design space, ability to absorb and mitigate external impact, protection of vehicle body and passengers, corrosion resistance and other advantages. Polypropylene (PP) has been widely used in automobile interior and exterior parts, such as bumpers, instrument panels, door inner panels, pillar guard plates and other core automobile parts, due to its excellent comprehensive mechanical properties, high heat resistance, excellent fatigue resistance, excellent electrical insulation, good chemical resistance and almost all molding methods.

[0003] The polypropylene resin molecule has a non-polar linear structure, low surface activity, and no polarity, making it difficult for the coating film to adhere. Therefore, the key performance of polypropylene plastic coating is the adhesion of the coating, which is also a major concern in the coating industry. Automobile plastic parts are generally coated in three layers, namely primer, topcoat and clear coat. The primer ensures adhesion to the plastic part and fills the uneven surface of the plastic part. The topcoat mainly imparts color and decoration, and the outermost layer is clear coat to ensure good durability. In terms of construction method, for large parts such as bumpers, automatic electrostatic spraying has high production capacity and relatively good coating quality, with obvious advantages in material consumption and labor cost. At the same time, due to the large volume, the oven occupies a large area and consumes a lot of energy, so automatic electrostatic spraying process is generally used. Therefore, the PP primer must be designed as a conductive primer to enable electrostatic spraying of the topcoat. SUMMARY

[0004] The purpose of the present application is to provide a high-conductivity and high-adhesion primer composition for PP. The high-adhesion primer for PP prepared by the present application not only has good adhesion performance, but also has excellent conductivity, effectively improving the efficiency of electrostatic spraying of the topcoat.

[0005] To achieve the above-mentioned purpose of the present application, the following technical solutions can be used: The high-conductivity and high-adhesion primer composition for PP includes the following components by mass: Thermoplastic acrylic resin: 40-60 parts; Modified polypropylene: 1-10 parts; Modified titanium dioxide: 12-24 parts; White carbon black: 1-5 parts; Dispersing agent: 1-2 parts; Defoaming agent: 0.1-0.5 parts; Dispersant: 0.1-1 parts; Solvent: 25-40 parts.

[0006] In the specific embodiment of the present application, the modified polypropylene is prepared by mixing polypropylene, initiator DCP, acrylic acid and styrene, and then extruding by a double screw extruder.

[0007] In the specific embodiment of the present application, the mass ratio of polypropylene, initiator DCP, acrylic acid and styrene is 100: (0.2-0.5): (2-10): (1-5).

[0008] In the specific embodiment of the present application, the modified polypropylene is prepared by the following steps: After the polypropylene, initiator DCP, acrylic acid and styrene are uniformly mixed, they are added to a preheated double screw extruder for melt grafting reaction. The reaction section temperatures of the extruder are 180℃, 190℃, 200℃, 205℃ and 210℃ respectively, and the output section temperature is 200℃. After extrusion, underwater strand-pulling and granulation are performed.

[0009] In the specific embodiment of the present application, the modified titanium dioxide is prepared by mixing and heating reducing graphene oxide, titanium dioxide powder and deionized water.

[0010] In the specific embodiment of the present application, the modified titanium dioxide is prepared by the following steps: (1) The reducing graphene oxide is dispersed in deionized water by ultrasonic, and stirred for 30-90 minutes; (2) The titanium dioxide powder is added to the reducing graphene oxide dispersion, heated to 40-50℃, and stirred for 20-30 minutes until the solution becomes transparent; (3) The mixed solution is washed and vacuum dried to obtain the modified titanium dioxide.

[0011] In the specific embodiment of the present application, the dispersant includes commercially available BYK161; the defoaming agent includes commercially available BYK051; the leveling agent includes commercially available BYK333; and the solvent is selected from a combination of one or more of toluene, xylene and acetone.

[0012] The present application also provides a preparation method of the high-conductivity and high-adhesion primer composition for PP, which comprises the following steps: (1) According to the mass fraction, the thermoplastic acrylic resin, the modified polypropylene and the solvent are added to the reactor, and stirred until the resin is dissolved and uniformly mixed; (2) The dispersant, the defoaming agent and the leveling agent are sequentially added under low-speed stirring, and stirred uniformly; (3) The modified titanium dioxide and the white carbon black are sequentially added under low-speed stirring, and stirred uniformly to obtain the high-conductivity and high-adhesion primer for PP.

[0013] In the specific embodiment of the present application, the stirring speed in step (1) is 600-1000 r / min; the low-speed stirring speed in step (2) is 300-500 r / min, and the stirring time is 20-30 min; the low-speed stirring speed in step (3) is 300-500 r / min, and the stirring time is 20-30 min.

[0014] In the specific embodiment of the present application, the primer is ground to a fineness of 15-25 um.

[0015] Compared with the prior art, the present application has the following beneficial effects: The high-conductivity high-adhesion primer for PP is prepared from thermoplastic acrylic resin, modified polypropylene, modified titanium dioxide, white carbon black, dispersant, defoaming agent, leveling agent and solvent, etc. Based on the principle of similarity and compatibility, the modified polypropylene is introduced into the primer formula, so that the primer can tightly adhere to the PP substrate. The reduced graphene oxide with conductivity is used to modify the titanium dioxide through interface effect, and the modified titanium dioxide powder is uniformly distributed in the primer, so that the primer has good conductivity. The primer coating prepared by the above formula is applied to the PP substrate, and the formed paint film has high conductivity and long-term adhesion. The preparation method of the primer is simple, short in process, easy to operate and suitable for large-scale production. DETAILED DESCRIPTION

[0016] The technical solutions of the present application will be described clearly and completely in combination with the specific embodiments below, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market. Example 1

[0017] A high-conductivity high-adhesion primer composition for PP is prepared by using the following mass fractions: Thermoplastic acrylic resin: 40 parts; Modified polypropylene: 5 parts; Modified titanium dioxide: 12 parts; White carbon black: 2 parts; BYK161: 1 part; BYK051: 0.1 part; BYK333: 0.1 part; Solvent: 35 parts.

[0018] In this embodiment, the preparation method of the modified polypropylene comprises the following steps: The polypropylene (100 parts by mass), initiator DCP (0.4 parts), acrylic acid (8 parts) and styrene (2 parts) are mixed uniformly and then added to a preheated twin-screw extruder for melt grafting reaction. The reaction section temperature of the extruder is 180℃, 190℃, 200℃, 205℃ and 210℃ respectively, and the output section temperature is 200℃. After extrusion, underwater strand-pulling and granulation are performed.

[0019] Further, the preparation method of the modified titanium dioxide comprises the following steps: (1) The reduced graphene oxide (1 part by mass) is dispersed in deionized water by ultrasonic and stirred for 60 min; (2) The titanium dioxide powder (100 parts) is added to the reduced graphene oxide dispersion, heated to 40℃ and stirred for 30 min until the solution becomes transparent; (3) The mixed solution is washed with alcohol and vacuum dried to obtain the modified titanium dioxide.

[0020] In this embodiment, the preparation method of the high-conductivity high-adhesion primer composition for PP comprises the following steps: (1) The thermoplastic acrylic resin, modified polypropylene and solvent are added to the reactor, and the stirring speed is set to 800 r / min. Stirring is performed until the resin is completely dissolved and mixed uniformly; (2) The stirring speed is set to 300 r / min, and the dispersant, defoaming agent and leveling agent are added in sequence, and stirring is performed for 30 min; (3) The stirring speed is set to 300 r / min, and the modified titanium dioxide and white carbon black are added in sequence, and stirring is performed for 30 min to obtain the high-conductivity high-adhesion primer for PP. Example 2

[0021] A high-conductivity high-adhesion primer composition for PP is prepared with the following mass parts: Thermoplastic acrylic resin: 40 parts; Modified polypropylene: 10 parts; Modified titanium dioxide: 12 parts; White carbon black: 2 parts; BYK161: 2 parts; BYK051: 0.2 parts; BYK333: 0.1 parts; Solvent: 30 parts.

[0022] In this embodiment, the preparation method of the modified polypropylene comprises the following steps: Polypropylene (100 parts by mass), initiator DCP (0.4 parts), acrylic acid (10 parts) and styrene (2 parts) are mixed uniformly and then added to a preheated twin-screw extruder for melt grafting reaction. The reaction section temperature of the extruder is 180℃, 190℃, 200℃, 205℃, 210℃ respectively, and the output section temperature is 200℃. After extrusion, underwater strand-pulling and granulation are performed.

[0023] Further, the modified titanium dioxide preparation method comprises the following steps: (1) The reduced graphene oxide (1 part by mass) is dispersed in deionized water by ultrasonic and stirred for 60 min; (2) The titanium dioxide powder (100 parts) is added to the reduced graphene oxide dispersion, heated to 40℃ and stirred for 30 min until the solution becomes transparent; (3) The mixed solution is washed with alcohol and vacuum dried to obtain the modified titanium dioxide.

[0024] In this embodiment, the preparation method of the high-conductivity high-adhesion primer composition for PP comprises the following steps: (1) The thermoplastic acrylic resin, modified polypropylene and solvent are added to the reactor, and the stirring speed is set to 800 r / min. Stirring is performed until the resin is completely dissolved and mixed uniformly; (2) The stirring speed is set to 300 r / min, and the dispersant, defoaming agent and leveling agent are added in sequence, and stirring is performed for 30 min; (3) The stirring speed is set to 300 r / min, and the modified titanium dioxide and white carbon black are added in sequence, and stirring is performed for 30 min to obtain the high-conductivity high-adhesion primer composition for PP. Example 3

[0025] A high-conductivity high-adhesion primer composition for PP is prepared by using the following mass parts: Thermoplastic acrylic resin: 40 parts; Modified polypropylene: 10 parts; Modified titanium dioxide: 18 parts; White carbon black: 2 parts; BYK161: 1 part; BYK051: 0.2 parts; BYK333: 0.1 parts; Solvent: 25 parts.

[0026] In this embodiment, the preparation method of the modified polypropylene comprises the following steps: Polypropylene (100 parts by mass), initiator DCP (0.4 parts), acrylic acid (10 parts) and styrene (2 parts) are mixed uniformly and then added to a preheated twin-screw extruder for melt grafting reaction. The reaction section temperature of the extruder is 180℃, 190℃, 200℃, 205℃, 210℃ respectively, and the output section temperature is 200℃. After extrusion, underwater strand-pulling and granulation are performed.

[0027] Further, the preparation method of the modified titanium dioxide comprises the following steps: (1) The reduced graphene oxide (3 parts by mass) is dispersed in deionized water by ultrasonic and stirred for 60 min; (2) The titanium dioxide powder (100 parts) is added to the reduced graphene oxide dispersion, heated to 40℃ and stirred for 30 min until the solution becomes transparent; (3) The mixed solution is washed with alcohol and vacuum dried to obtain the modified titanium dioxide.

[0028] In this embodiment, the preparation method of the PP high-conductivity high-adhesion primer composition comprises the following steps: (1) The thermoplastic acrylic resin, modified polypropylene and solvent are added to the reactor, and the stirring speed is set to 800 r / min. Stirring is performed until the resin is completely dissolved and mixed uniformly; (2) The stirring speed is set to 300 r / min, and the dispersant, defoaming agent and leveling agent are added in sequence, and stirring is performed for 30 min; (3) The stirring speed is set to 300 r / min, and the modified titanium dioxide and white carbon black are added in sequence, and stirring is performed for 30 min to obtain the PP high-conductivity high-adhesion primer. Example 4

[0029] A PP high-conductivity high-adhesion primer composition is prepared by using the following mass parts: Thermoplastic acrylic resin: 40 parts; Modified polypropylene: 10 parts; Modified titanium dioxide: 18 parts; White carbon black: 2 parts; BYK161: 1.5 parts; BYK051: 0.2 parts; BYK333: 0.1 parts; Solvent: 25 parts.

[0030] In this embodiment, the preparation method of the modified polypropylene comprises the following steps: Polypropylene (100 parts by mass), initiator DCP (0.4 parts), acrylic acid (10 parts) and styrene (2 parts) are mixed uniformly and then added to a preheated twin-screw extruder for melt grafting reaction. The reaction section temperature of the extruder is 180℃, 190℃, 200℃, 205℃, 210℃ respectively, and the output section temperature is 200℃. After extrusion, underwater strand-pulling and granulation are performed.

[0031] Further, the modified titanium dioxide preparation method comprises the following steps: (1) The reduced graphene oxide (5 parts by mass) is dispersed in deionized water by ultrasonic and stirred for 60 min; (2) The titanium dioxide powder (100 parts) is added to the reduced graphene oxide dispersion, heated to 40℃, and stirred for 30 min until the solution becomes transparent; (3) The mixed solution is washed with alcohol and vacuum dried to obtain the modified titanium dioxide.

[0032] In this embodiment, the preparation method of the high-conductivity high-adhesion primer composition for PP comprises the following steps: (1) The thermoplastic acrylic resin, modified polypropylene and solvent are added to the reactor, and the stirring speed is set to 800 r / min. Stirring is performed until the resin is completely dissolved and mixed uniformly; (2) The stirring speed is set to 300 r / min, and the dispersant, defoaming agent and leveling agent are added in sequence, and stirred for 30 min; (3) The stirring speed is set to 300 r / min, and the modified titanium dioxide and white carbon black are added in sequence, and stirred for 30 min to obtain the high-conductivity high-adhesion primer composition for PP. Comparative Example 1

[0033] A high-conductivity high-adhesion primer composition for PP is prepared with the following mass fractions: Thermoplastic acrylic resin: 45 parts; Modified titanium dioxide: 12 parts; White carbon black: 2 parts; BYK161: 1 part; BYK051: 0.1 part; BYK333: 0.1 part; Solvent: 35 parts.

[0034] In this embodiment, the modified titanium dioxide preparation method comprises the following steps: (1) The reduced graphene oxide (1 part by mass) is dispersed in deionized water by ultrasonic and stirred for 60 min; (2) Add titanium dioxide powder (100 parts) into the reduced graphene oxide dispersion solution, heat to 40℃, and stir for 30 min until the solution becomes transparent; (3) Wash the mixed solution with alcohol and vacuum dry to obtain the modified titanium dioxide.

[0035] In this embodiment, the preparation method of the high-conductivity high-adhesion primer composition for PP includes the following steps: (1) Add the thermoplastic acrylic resin and the solvent into the reactor, set the stirring speed to 800 r / min, and stir until the resin is completely dissolved and uniformly mixed; (2) Set the stirring speed to 300 r / min, and sequentially add the dispersant, the defoaming agent, and the leveling agent, and stir for 30 min; (3) Set the stirring speed to 300 r / min, and sequentially add the modified titanium dioxide and the white carbon black, and stir for 30 min to obtain the high-conductivity high-adhesion primer composition for PP. Comparative Example 2

[0036] A high-conductivity high-adhesion primer composition for PP is prepared by using the following mass fractions: Thermoplastic acrylic resin: 40 parts; Modified polypropylene: 10 parts; Titanium dioxide: 12 parts; White carbon black: 2 parts; BYK161: 2 parts; BYK051: 0.2 parts; BYK333: 0.1 parts; Solvent: 30 parts.

[0037] In this embodiment, the preparation method of the modified polypropylene includes the following steps: After the polypropylene (100 parts by mass), the initiator DCP (0.4 parts), the acrylic acid (10 parts), and the styrene (2 parts) are uniformly mixed, they are added into a preheated twin-screw extruder for a melt grafting reaction. The reaction section temperatures of the extruder are 180℃, 190℃, 200℃, 205℃, and 210℃, respectively, and the output section temperature is 200℃. After extrusion, underwater strand-pulling and pelletizing are performed.

[0038] In this embodiment, the preparation method of the high-conductivity high-adhesion primer composition for PP includes the following steps: (1) Add the thermoplastic acrylic resin, the modified polypropylene, and the solvent into the reactor, set the stirring speed to 800 r / min, and stir until the resin is completely dissolved and uniformly mixed; (2) Set the stirring speed to 300 r / min, and sequentially add the dispersant, the defoaming agent, and the leveling agent, and stir for 30 min; (3) set the stirring speed to 300 r / min, add titanium dioxide and white carbon black in turn, and stir for 30 min to obtain a high-conductivity high-adhesion primer for PP.

[0039] To investigate the performance of the primers for PP substrates prepared in the above Examples 1-6, the primers, one-component PP color paint and two-component polyurethane topcoat were sprayed in turn to prepare a coating by 3C1B process.

[0040] The PP plate was wiped with solvent oil to remove surface dirt, and the above six primers were diluted with solvent to a construction viscosity, and sprayed onto the cleaned PP plate by air spray gun, wet spraying 2 times (with an interval of 1 min), to ensure the film thickness of 15-20 um. After spraying, the film was leveled at room temperature, and then dried in an oven at 60°C for 30 min. The adhesion, weather resistance, water resistance and conductivity of the film were tested, and the results are shown in Table 1 below:

[0041] The test methods for each test item are as follows: The adhesion test method is referred to ISO 2409-2024; The water resistance test method is referred to GB / T 5209-1985; The steam jet test method is referred to ISO 16925-2021; The cold and hot alternating test method is referred to BYDQ-A1901; As can be seen from the above table, the high-conductivity high-adhesion primer for PP of the application meets the standard requirements, and the conductivity of the primer is at a high level, the primer can be closely attached to the PP substrate, and has a wide application prospect.

[0042] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the above examples, those skilled in the art should understand that: they can still modify the technical solutions recorded in the above examples, or make equivalent replacement for part or all of the technical features: and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A highly conductive and high-adhesion primer composition for PP, characterized in that: The raw materials of the primer include the following components in parts by mass: Thermoplastic acrylic resin: 40-60 parts; Modified polypropylene: 1-10 parts; Modified titanium dioxide: 12-24 parts; White carbon black: 1-5 parts; Dispersant: 1-2 parts; Defoaming agent: 0.1-0.5 parts; Leveling agent: 0.1-1 part; Solvent: 25-40 parts.

2. The high-conductivity and high-adhesion primer composition for PP according to claim 1, characterized in that: Modified polypropylene is produced by mixing polypropylene, initiator DCP, acrylic acid and styrene and then extruding them through a twin-screw extruder.

3. The high-conductivity and high-adhesion primer composition for PP according to claim 2, characterized in that: The mass ratio of the polypropylene, initiator DCP, acrylic acid and styrene is 100: (0.2-0.5): (2-10): (1-5).

4. The high-conductivity and high-adhesion primer composition for PP according to claim 3, characterized in that: Modified polypropylene is prepared by the following steps: Polypropylene, initiator DCP, acrylic acid and styrene were mixed evenly and added into a preheated twin-screw extruder for melt grafting reaction. The temperatures of the reaction section of the extruder were 180°C, 190°C, 200°C, 205°C and 210°C, respectively, and the temperature of the output section was 200°C. After extrusion, the product was stretched underwater and pelletized.

5. The high-conductivity and high-adhesion primer composition for PP according to claim 1, characterized in that: The modified titanium dioxide is prepared by mixing reduced graphene oxide, titanium dioxide powder and deionized water, heating and stirring.

6. The high-conductivity and high-adhesion primer composition for PP according to claim 5, characterized in that: The modified titanium dioxide is specifically prepared by the following steps: (1) Dispersing reduced graphene oxide in deionized water by ultrasound and stirring for 30-90 minutes; (2) Add titanium dioxide powder to the reduced graphene oxide dispersion, heat to 40-50°C, and stir for 20-30 minutes until the solution becomes transparent; (3) The mixed solution is washed and vacuum-dried to obtain modified titanium dioxide.

7. The high-conductivity and high-adhesion primer composition for PP according to claim 1, characterized in that: The dispersant includes commercially available BYK161; the defoamer includes commercially available BYK051; the leveling agent includes commercially available BYK333; and the solvent is selected from a combination of one or more of toluene, xylene, and acetone.

8. The method for preparing a high-conductivity and high-adhesion primer composition for PP according to claim 1, characterized in that: The method comprises the following steps: (1) Add thermoplastic acrylic resin, modified polypropylene and solvent into a reactor according to parts by mass and stir until the resin is dissolved and mixed uniformly; (2) Add dispersant, defoamer and leveling agent in sequence under low-speed stirring and stir evenly; (3) Add modified titanium dioxide and white carbon black in sequence under low-speed stirring and stir evenly to obtain a high-conductivity and high-adhesion primer for PP.

9. The method for preparing a high-conductivity and high-adhesion primer composition for PP according to claim 8, characterized in that: The stirring speed in step (1) is 600-1000 r / min; the low-speed stirring speed in step (2) is 300-500 r / min, and the stirring time is 20-30 min; the low-speed stirring speed in step (3) is 300-500 r / min, and the stirring time is 20-30 min.

10. The method for preparing a high-conductivity and high-adhesion primer composition for PP according to claim 8, characterized in that: Grind to a fineness of 15-25um.

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