CN115368795B - Water-based high-solid amino baking paint and preparation method thereof - Google Patents

Abstract

The invention relates to a water-based high-solid amino baking paint and a preparation method thereof, belonging to the technical field of high polymer materials. The amino baking paint comprises the following components in parts by weight: 28-36 parts of modified amino resin, 45-60 parts of acrylic copolymer, 15-25 parts of coupling filler, less than or equal to 10 parts of pigment, 30-40 parts of diluent, 3-5 parts of flatting agent and 1-3 parts of drier; the modified amino resin is prepared by using melamine as a raw material, performing epoxidation modification by using epoxy chloropropane, reacting tetraethylenepentamine with a grafted epoxy group under the catalysis of strong base to obtain a resin containing branched long-chain amino on the molecule, and performing 'clamping' type crosslinking with an acrylic copolymer.

Description

Water-based high-solid amino baking paint and preparation method thereof

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to a water-based high-solid amino baking paint and a preparation method thereof.

Background

The amino baking varnish is widely applied to industries such as household appliances, agricultural machinery, automobile coating, mining machinery and the like, and has an important position in coating products, wherein the polyester amino baking varnish has excellent light and color retention, strong adhesive force and excellent impact resistance, is suitable for beautifying and protecting decoration of outdoor metal surfaces, and is widely applied.

With the improvement of environmental awareness and environmental requirements, the aqueous amino baking paint becomes the mainstream trend of development, the aqueous polyester resin and the amino resin are used as main film forming materials, the amino resin has high curing brittleness and poor adhesion, the brittleness is improved by crosslinking modification of the polyester resin, common polyester resin is selected to be aqueous modified alkyd resin, for example, chinese patent CN101747500B provides sulfonate-based water-dilutable alkyd resin and amino baking paint thereof, the sulfonate-modified alkyd resin has certain improvement on toughness and adhesion, but the hardness is obviously reduced, the pencil hardness is about 2H, and the strong protection effect is difficult to achieve, because the characteristics of the alkyd resin are determined, the toughness and the hardness can reach a certain balance through reasonable ingredients, and the higher promotion is difficult to achieve, therefore, the invention aims to develop the aqueous high-solid amino baking paint with good combination of hardness and toughness.

Disclosure of Invention

In order to solve the technical problems mentioned in the background technology, the invention aims to provide an aqueous high-solid amino baking paint and a preparation method thereof.

The purpose of the invention can be realized by the following technical scheme:

the water-based high-solid amino baking paint comprises the following raw materials in parts by weight:

28-36 parts of modified amino resin, 45-60 parts of acrylic copolymer, 15-25 parts of coupling filler, less than or equal to 10 parts of pigment, 30-40 parts of diluent, 3-5 parts of flatting agent and 1-3 parts of drier.

The modified amino resin is prepared by the following method:

step A1: preheating melamine and dimethyl sulfoxide to 60 ℃ under the protection of nitrogen, stirring and dissolving, adding epoxy chloropropane and an antioxidant 1135, mixing, heating to 130 ℃, performing reflux reaction for 80-100min, cooling to 100 ℃, adding caustic soda flakes, stirring for 20min, cooling to room temperature after the reaction is finished, filtering, washing the filtrate with brine ice, separating, taking out organic phase, and drying to prepare epoxy resin;

further, the dosage ratio of melamine, epichlorohydrin, dimethyl sulfoxide, antioxidant 1135 and caustic soda flakes is 0.1mol:0.32mol:15-20mL:0.1g:1-1.5g.

Step A2: mixing epoxy resin, tetrahydrofuran, potassium hydroxide and hydroquinone, heating to 45 ℃, stirring and activating for 15min, adding tetraethylenepentamine, mixing, heating to 68 ℃, performing reflux reaction for 20-25min, and performing reduced pressure rotary evaporation after the reaction is finished to prepare the modified amino resin.

Further, the dosage ratio of the epoxy resin, the tetraethylenepentamine, the tetrahydrofuran, the potassium hydroxide and the hydroquinone is 10g:0.1mol:18-25mL:0.5-0.7g:20mg.

The acrylic copolymer was prepared by the following method:

step B1: uniformly mixing methacrylic acid, butyl acrylate, methyl methacrylate and styrene, adjusting the solid content to 80% by using ethyl acetate, adding benzoyl peroxide, heating to 60 ℃, and carrying out reflux reaction for 40-60min to prepare an homopolymerization solution;

further, the amount ratio of methacrylic acid, butyl acrylate, methyl methacrylate, styrene and benzoyl peroxide is 0.2mol:0.1mol:30-50mmol:20-40mmol:0.2-0.3g.

And step B2: heating the homopolymerized liquid to 92-98 ℃, controlling the stirring speed to be 420rpm, slowly adding the RAFT reagent dropwise, controlling the whole dropwise adding reaction time to be 50-60min, adding ammonia water to quench polymerization after the reaction is finished, and simultaneously adjusting the solid content of the reaction liquid to be 60% to prepare the acrylic copolymer.

Further, the dosage ratio of the homopolymerization solution to the RAFT reagent is 100mL:20-30mg.

Further, the coupling filler is fumed silica treated with KH 550.

Further, the diluent is selected from diethylene glycol butyl ether.

Further, the leveling agent is selected from organosilicon leveling agents.

Further, the drier is selected from aqueous driers FR-801.

A preparation method of water-based high-solid amino baking paint comprises the following steps:

step S1: uniformly mixing the coupling filler, the pigment, the diluent and the flatting agent to prepare a premixed solution;

step S2: and controlling the stirring speed to be 600rpm, adding the modified amino resin and the acrylic copolymer into the premixed solution, stirring and mixing, adding deionized water to adjust the viscosity to be 50s, adding triethylamine to adjust the pH value to be 7.5, and preparing the amino baking paint.

The invention has the beneficial effects that:

1. the invention uses a self-made modified amino resin in amino baking paint, which is prepared by using melamine as a raw material, reacting epoxy chloropropane with amino in the melamine, using caustic soda flakes to carry out epoxy modification on the melamine, and then reacting tetraethylenepentamine with a grafted epoxy group under the catalysis of strong base to obtain the resin with branched long chain amino on the molecule, so that the resin has good water solubility and is easy to mix and manufacture.

2. According to the invention, methacrylic acid and butyl acrylate are used as main matrixes, methyl methacrylate is introduced to improve the cohesive force of the polymer, the good adhesion between the amino baking paint and the matrixes is ensured, styrene copolymerization is introduced, benzene rings are introduced to side chains, the rigidity of the polymer and the hardness of a paint film are improved, and tests show that after the amino baking paint prepared by the invention is cured, the hardness of the paint film can reach 4H to the maximum, and the adhesion grade reaches 0 level.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The coupling filler is prepared in the embodiment by the following specific implementation process:

mixing an ethanol solution with a volume concentration of 30% and KH550 according to a dosage ratio of 100mL:8mL of the components are mixed, hydrochloric acid is added dropwise to adjust the pH value to 6.0, the mixture is stirred at 300rpm for 20min at room temperature, fumed silica is added according to the solid-to-liquid ratio of 1.

Example 2

The modified amino resin is prepared by the following specific implementation process:

a1, adding melamine and dimethyl sulfoxide into a reaction kettle, introducing nitrogen for protection, preheating to 60 ℃, stirring and dissolving, adding epoxy chloropropane and an antioxidant 1135 for mixing, continuously heating to 130 ℃, performing reflux reaction for 80min, cooling to 100 ℃, adding caustic soda flakes, stirring for 20min, reacting epoxy chloropropane with amino in melamine, performing epoxy modification on melamine through caustic soda flakes closed loop, cooling to room temperature after reaction is finished, filtering, adding saturated ice brine with the volume being three times that of filtrate twice into the filtrate for washing and separating, taking an organic phase, and drying with anhydrous calcium chloride to obtain epoxy resin; in the reaction, the dosage ratio of melamine, epichlorohydrin, dimethyl sulfoxide, antioxidant 1135 and caustic soda flakes is 0.1mol:0.32mol:15mL of: 0.1g:1.5g.

a2, adding epoxy resin, tetrahydrofuran, potassium hydroxide and hydroquinone into a reaction kettle, stirring and mixing, heating to 45 ℃, stirring for 15min, activating an epoxy group on the epoxy resin through strong basicity of potassium hydroxide, inhibiting polymerization by using hydroquinone, adding tetraethylenepentamine, mixing, continuously heating to 68 ℃, carrying out reflux reaction for 20min, and carrying out rotary evaporation under reduced pressure of less than 10mmHg to obtain modified amino resin; in the above reaction, the amount ratio of the epoxidized resin, tetraethylenepentamine, tetrahydrofuran, potassium hydroxide and hydroquinone is 10g:0.1mol:25mL of: 0.7g:20mg.

Example 3

The modified amino resin is prepared by the following specific implementation process:

a1, adding melamine and dimethyl sulfoxide into a reaction kettle, introducing nitrogen for protection, preheating to 60 ℃, stirring and dissolving, adding epoxy chloropropane and an antioxidant 1135 for mixing, continuously heating to 130 ℃, performing reflux reaction for 100min, cooling to 100 ℃, adding caustic soda flakes, stirring for 20min, cooling to room temperature after the reaction is finished, filtering, adding saturated ice and brine with the volume being three times that of filtrate twice into the filtrate for washing and separating, taking an organic phase, and drying with anhydrous calcium chloride to obtain the epoxy resin; in the reaction, the dosage ratio of melamine, epichlorohydrin, dimethyl sulfoxide, antioxidant 1135 and caustic soda flakes is 0.1mol:0.32mol:15mL of: 0.1g:1g of the total weight of the composition.

a2, adding epoxy resin, tetrahydrofuran, potassium hydroxide and hydroquinone into a reaction kettle, stirring and mixing, heating to 45 ℃, stirring for 15min, adding tetraethylenepentamine, mixing, continuously heating to 68 ℃, performing reflux reaction for 20-25min, and performing rotary evaporation under reduced pressure of less than 10mmHg to obtain modified amino resin; in the above reaction, the amount ratio of the epoxidized resin, tetraethylenepentamine, tetrahydrofuran, potassium hydroxide and hydroquinone was 10g:0.1mol:18mL of: 0.5g:20mg.

Example 4

The modified amino resin is prepared by the following specific implementation process:

a1, adding melamine and dimethyl sulfoxide into a reaction kettle, introducing nitrogen for protection, preheating to 60 ℃, stirring and dissolving, adding epoxy chloropropane and an antioxidant 1135 for mixing, continuously heating to 130 ℃, performing reflux reaction for 90min, cooling to 100 ℃, adding caustic soda flakes, stirring for 20min, cooling to room temperature after the reaction is finished, filtering, adding saturated ice and brine with the volume being three times that of filtrate twice into the filtrate for washing and separating, taking an organic phase, and drying with anhydrous calcium chloride to obtain the epoxy resin; in the reaction, the dosage ratio of melamine, epichlorohydrin, dimethyl sulfoxide, antioxidant 1135 and caustic soda flakes is 0.1mol:0.32mol:18mL of: 0.1g:1.2g.

a2, adding epoxy resin, tetrahydrofuran, potassium hydroxide and hydroquinone into a reaction kettle, stirring and mixing, heating to 45 ℃, stirring for 15min, adding tetraethylenepentamine, mixing, continuously heating to 68 ℃, carrying out reflux reaction for 23min, and carrying out rotary evaporation under reduced pressure of less than 10mmHg to obtain modified amino resin; in the above reaction, the amount ratio of the epoxidized resin, tetraethylenepentamine, tetrahydrofuran, potassium hydroxide and hydroquinone is 10g:0.1mol:22mL of: 0.6g:20mg.

Example 5

This example prepares an acrylic copolymer as follows:

b1, adding methacrylic acid, butyl acrylate, methyl methacrylate and styrene into a reaction kettle, uniformly mixing, slowly adding ethyl acetate to adjust the solid content to 80%, adding benzoyl peroxide, heating to 60 ℃, and carrying out reflux reaction for 40min to obtain a homogeneous solution; in the above reaction, methacrylic acid, butyl acrylate, methyl methacrylate, styrene and benzoyl peroxide were used in a ratio of 0.2mol:0.1mol:50mmol:20mmol:0.3g.

b2, heating the homopolymerized liquid to 92 ℃, controlling the stirring speed to be 420rpm, slowly adding an RAFT reagent (commercially available, CPDB is the main component) dropwise, controlling the whole dropwise adding reaction time to be 60min, adding ammonia water after the reaction is finished, quenching and polymerizing, and simultaneously adjusting the solid content of the reaction liquid to be 60% to prepare the acrylic copolymer, wherein the dosage ratio of the RAFT reagent to the homopolymerized liquid is 20mg/100mL.

Example 6

This example prepares an acrylic copolymer as follows:

b1, adding methacrylic acid, butyl acrylate, methyl methacrylate and styrene into a reaction kettle, uniformly mixing, slowly adding ethyl acetate to adjust the solid content to 80%, adding benzoyl peroxide, heating to 60 ℃, and carrying out reflux reaction for 60min to obtain a homogeneous solution; in the above reaction, methacrylic acid, butyl acrylate, methyl methacrylate, styrene and benzoyl peroxide were used in a ratio of 0.2mol:0.1mol:30mmol:40mmol of: 0.2g.

b2, heating the homopolymerized liquid to 98 ℃, controlling the stirring speed to be 420rpm, slowly adding the RAFT reagent dropwise, controlling the whole dropwise adding reaction time to be 50min, adding ammonia water to quench polymerization after the reaction is finished, and simultaneously adjusting the solid content of the reaction liquid to be 60% to prepare the acrylic copolymer, wherein the dosage ratio of the RAFT reagent to the homopolymerized liquid is 30mg/100mL.

Example 7

The preparation of the aqueous high-solid amino baking paint according to the embodiment comprises the following specific implementation processes:

s1, preparing materials: taking the following components in parts by weight:

28 parts of modified amino resin prepared in example 2

45 parts of acrylic copolymer prepared in example 5

15 parts of coupling filler prepared in example 1

6 parts of pigment (commercial Black paste, model Luconyl Black 0066)

30 portions of diluent (diethylene glycol monobutyl ether)

3 parts of flatting agent (organic silicon flatting agent, model BYK-346)

Drier (aqueous drier FR-801) 1 part

Deionized water and triethylamine are added;

s2, premixing: adding the coupling filler, the pigment, the diluent and the flatting agent into a mixing kettle, and stirring and mixing at a high speed of 800rpm for 10min to obtain a premixed solution;

s3, compounding: and reducing the stirring speed to 600rpm, adding the modified amino resin and the acrylic copolymer into the premixed solution, stirring and mixing, adding deionized water to adjust the viscosity to 50s, and adding triethylamine to adjust the pH value to 7.5 to prepare the amino baking paint.

Example 8

This example is the same as the preparation of example 7, with the following raw materials:

30 parts of modified amino resin prepared in example 2

50 parts of acrylic copolymer prepared in example 6

19 parts of coupling filler prepared in example 1

7 parts of pigment (commercial Black paste, model Luconyl Black 0066)

32 parts of diluent (diethylene glycol monobutyl ether)

4 parts of flatting agent (organic silicon flatting agent, model BYK-346)

2 parts of drier (aqueous drier FR-801).

Example 9

This example is the same as the preparation of example 7, with the following raw materials:

33 parts of modified amino resin prepared in example 3

52 parts of acrylic copolymer prepared in example 5

18 parts of coupling filler prepared in example 1

9 parts of pigment (commercial Black paste, model Luconyl Black 0066)

36 portions of diluent (diethylene glycol monobutyl ether)

4 parts of flatting agent (organic silicon flatting agent, model BYK-346)

2 parts of drier (aqueous drier FR-801).

Example 10

This example is the same as the preparation of example 7, with the following raw materials:

36 parts of modified amino resin prepared in example 4

60 parts of acrylic copolymer prepared in example 5

25 parts of coupling filler prepared in example 1

10 portions of pigment (commercial Black paste, model Luconyl Black 0066)

40 portions of diluent (diethylene glycol butyl ether)

5 parts of flatting agent (organic silicon flatting agent, model BYK-346)

3 parts of drier (aqueous drier FR-801).

Comparative example 1

This comparative example was prepared in the same manner as in example 9 except that the modified resin prepared in example 3 was replaced with 46 parts of a commercially available highly methylated melamine formaldehyde resin.

Comparative example 2

The comparative example is the amino baking paint prepared by the method provided by the Chinese patent CN 101747500B.

The basic performance of the amino baking paint prepared in example 7-example 10 and comparative example 1-comparative example 2 was tested, and the specific test data is shown in table 1:

TABLE 1

As can be seen from the data in Table 1, the amino baking paint prepared by the invention has proper state at normal temperature, viscosity of 65s, solid content of 69-73% and high solid content.

Taking the amino baking paint prepared in the examples 7-10 and the comparative examples 1-2, taking a cold-rolled plate as a substrate, polishing the substrate by using 500-mesh sand paper and wiping the substrate by using ethanol, diluting the amino baking paint with water until the viscosity at normal temperature is 30s, spraying the amino baking paint on the surface of the substrate, placing the substrate in a drying oven, drying the substrate at 120 ℃ for 30min, and detecting the performance of a paint film, wherein the specific test data are shown in table 2:

TABLE 2

As can be seen from the data in Table 2, the cured amino baking paint has the pencil hardness of 4H at most, the flexibility of 1mm, good combination of hardness and toughness, adhesion grade of 0 grade, good combination strength with cold-rolled sheets, good impact resistance and high paint film glossiness.

The paint spraying samples prepared above were taken for tolerance testing, and the specific test data are shown in table 3:

TABLE 3

As can be seen from the data in Table 3, the cured paint film of the amino baking paint prepared by the invention has good water resistance, salt resistance, acid and alkali resistance, and can play a good role in protecting a matrix.

In the description of the specification, reference to the description of "one embodiment," "an example," "a specific example" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims (3)

1. The water-based high-solid amino baking paint is characterized by comprising the following raw materials in parts by weight:

28-36 parts of modified amino resin, 45-60 parts of acrylic copolymer, 15-25 parts of coupling filler, less than or equal to 10 parts of pigment, 30-40 parts of diluent, 3-5 parts of flatting agent and 1-3 parts of drier;

the modified amino resin is prepared by the following method:

step A1: preheating melamine and dimethyl sulfoxide under the protection of nitrogen to 60 ℃, stirring and dissolving, adding epoxy chloropropane and an antioxidant 1135, mixing, heating to 130 ℃, performing reflux reaction for 80-100min, cooling to 100 ℃, adding caustic soda flakes, stirring for 20min, cooling to room temperature after the reaction is finished, filtering, washing filtrate with brine ice, separating liquid, taking an organic phase, and drying to prepare epoxy resin, wherein the dosage ratio of the melamine, the epoxy chloropropane, the dimethyl sulfoxide, the antioxidant 1135 to the caustic soda flakes is 0.1mol:0.32mol:15-20mL:0.1g:1-1.5g;

step A2: mixing epoxy resin, tetrahydrofuran, potassium hydroxide and hydroquinone, heating to 45 ℃, stirring and activating for 15min, adding tetraethylenepentamine, mixing, heating to 68 ℃, performing reflux reaction for 20-25min, and performing reduced pressure rotary evaporation after the reaction is finished to prepare modified amino resin, wherein the dosage ratio of the epoxy resin, the tetraethylenepentamine, the tetrahydrofuran, the potassium hydroxide and the hydroquinone is 10g:0.1mol:18-25mL:0.5-0.7g:20mg;

the acrylic copolymer is prepared by the following method:

step B1: uniformly mixing methacrylic acid, butyl acrylate, methyl methacrylate and styrene, adjusting the solid content to 80% by using ethyl acetate, adding benzoyl peroxide, heating to 60 ℃, and carrying out reflux reaction for 40-60min to prepare an homopolymerization solution, wherein the dosage ratio of the methacrylic acid, the butyl acrylate, the methyl methacrylate, the styrene to the benzoyl peroxide is 0.2mol:0.1mol:30-50mmol:20-40mmol:0.2-0.3g;

and step B2: heating the homopolymerized solution to 92-98 ℃, controlling the stirring speed to be 420rpm, slowly dripping the RAFT reagent, controlling the whole dripping reaction time to be 50-60min, adding ammonia water to quench polymerization after the reaction is finished, and simultaneously adjusting the solid content of the reaction solution to be 60% to prepare the acrylic copolymer, wherein the dosage ratio of the homopolymerized solution to the RAFT reagent is 100mL:20-30mg;

the coupling filler is prepared by treating fumed silica with KH550, and the specific method comprises the following steps: mixing an ethanol solution with the volume concentration of 30% and KH550 according to the dosage ratio of 100mL:8mL of the components are mixed, hydrochloric acid is added dropwise to adjust the pH value to 6.0, the mixture is stirred at the room temperature for 20min at 300rpm, fumed silica is added according to the solid-liquid ratio of 1.

2. The aqueous high solids amino baking finish of claim 1 wherein the drier is selected from the group consisting of aqueous driers FR-801.

3. The method for preparing the aqueous high-solid amino baking paint as claimed in claim 2, which comprises the following steps:

step S1: uniformly mixing the coupling filler, the pigment, the diluent and the flatting agent to prepare a premixed solution;

step S2: and controlling the stirring speed to be 600rpm, adding the modified amino resin and the acrylic copolymer into the premixed solution, stirring and mixing, adding deionized water to adjust the viscosity to be 50s, adding triethylamine to adjust the pH value to be 7.5, and preparing the amino baking paint.