Paint for realizing multi-coating and multi-baking of bicycle and preparation method of paint

Abstract

The invention discloses paint capable of achieving multi-coating and multi-baking of a bicycle and a preparation method of the paint, and particularly relates to the technical field of paint. The coating comprises saturated polyester resin, a diluent, a pigment, a rheological additive, an adhesion promoter, an anti-settling agent, amino resin and a catalyst. The coating disclosed by the invention is high in crosslinking density and has flexibility and toughness, the impact resistance of the coating can still be kept after multiple coating and multiple baking (20 coating and 20 baking can be met), the requirements of multiple color register and reworking and reworking processes on a paint film can be met, and the phenomena of embrittlement, poor adhesion, softening and the like of the paint film are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a coating capable of realizing multiple coatings and baking on a bicycle and a preparation method thereof. Background Art

[0002] Paint is an important chemical material, widely used in construction, automobiles, machinery, household appliances, light industrial instruments, durable consumer goods, aerospace, ships and other fields. It is an indispensable material in the national economy. At present, the coatings used in the domestic bicycle and electric vehicle industries are mostly baking paints. The bicycle industry has very high requirements for the brightness, fullness, color diversity and other performance of the paint film. It can be said that the quality of the paint is directly related to the price of the bicycle, and it is regarded as a key process in bicycle manufacturing. Not only does it require the coating film to be plump and smooth, but it also has a strong demand for diversified appearance colors. It is necessary to use a multi-coating and multi-baking method for color coating. As a result, the performance requirements for the paint film are getting higher and higher, and the focus is on the adhesion performance and temperature resistance of the paint film when it is re-coated multiple times.

[0003] However, with current industry technology, the paint film can usually only be recoated 4 to 6 times under standard construction conditions. The thickness and fullness of the paint film cannot meet the design requirements of high-end bicycles. In addition, the paint film can easily become brittle after multiple high-temperature baking, resulting in the need for rework and re-processing, which affects production efficiency and yield rate.

[0004] Chinese patent CN107540826A, a new type of saturated polyester for high-end bicycles and its preparation method, belongs to the field of polyester materials. The saturated polyester of the present invention is obtained by reacting the following raw materials: 3-5% terephthalic acid, 12-25% hexahydrophthalic anhydride (also known as hexahydrophthalic anhydride), 5-10% trihydroxypropane, 5-10% neopentyl glycol, 3-5% tert-butyl glycidyl carbonate, 1-5% trimellitic anhydride, 0.5-1.5% antioxidant, 5-7% pentaerythritol, 15-20% DBE, 28-32% xylene, 0.5-1% catalyst. When used, the saturated polyester of the present invention has good recoating performance, can undergo repeated recoating and baking, the number of recoating times reaches more than 10 times, can maintain very good paint film flatness, the paint film thickness can reach more than 1 mm, and can resist stone impact collision during riding. However, the patent can only reach more than 10 times at most, and it is known in the art that more than 10 times means 10 to 15 times, which cannot meet the 20-coat and 20-bake requirement for high-end bicycle coatings.

[0005] Therefore, it is particularly necessary to develop a bicycle coating that can meet the requirements of the multi-coating and multi-baking coating process of bicycles and at the same time has excellent adhesion and impact resistance to meet the growing needs of the bicycle industry. Summary of the invention

[0006] To this end, the present invention provides a paint capable of realizing multiple coating and multiple baking of a bicycle and a preparation method thereof, so as to solve the above-mentioned problems.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] According to a first aspect of the present invention, a multi-coat and multi-bake bicycle paint is provided, wherein the paint comprises a saturated polyester resin, a diluent, a pigment, a rheological additive, an adhesion promoter, an anti-settling agent, an amino resin and a catalyst.

[0009] Furthermore, the proportions of the raw materials of the coating are: 36-52% saturated polyester resin, 8-11% diluent, 4-27% pigment, 0-1% rheological additive, 3-8% adhesion promoter, 3-4% anti-settling agent, 18-25% amino resin and 0.5-1.5% catalyst.

[0010] In the present invention, the saturated polyester resin and the amino resin need to be fed twice respectively when preparing the coating;

[0011] When the pigment-to-base ratio is lower than 1, a dispersant needs to be added.

[0012] The present invention flexibly adjusts the semi-finished product during the production process by adding saturated polyester resin and amino resin in batches, and effectively controls the reaction process in the preparation by adjusting the viscosity, reaction time and reaction conditions, so that the product has both flexibility and toughness, effectively improves its impact resistance, and has good adhesion and recoating performance.

[0013] As an example, a saturated polyester resin (article number: YS-897) is preferred.

[0014] Furthermore, the pigment is titanium dioxide or carbon black powder.

[0015] Furthermore, the rheological additive is bentonite.

[0016] Furthermore, the diluent is a polyurethane diluent (article number: W-AC-1).

[0017] Furthermore, the anti-settling agent is a gel paste with a diluent as a solvent; as an example, the anti-settling agent is a gel paste with ethylene glycol butyl ether and diethylene glycol butyl ether acetate as solvents, with W-2810 added, and is prepared by a high-speed dispersion process.

[0018] The invention adds a rheological additive and adjusts the dispersion system of the anti-settling agent during preparation, so as to give full play to the performance of the pigment powder in the polyester resin, so that the pigment powder can still maintain good flatness when repeatedly re-coated.

[0019] Furthermore, the amino resin is butyl etherified amino resin (article number: YS-168) and methyl etherified amino resin (article number: AC-5943).

[0020] The present invention effectively increases the crosslinking density by adding butylated amino resin and methylated amino resin respectively, so that the coating is more suitable for multiple baking in the recoating process, has a greater tolerance to the environment such as temperature and humidity, and improves the protective performance of the paint film while ensuring the appearance.

[0021] Furthermore, the adhesion promoter is an adhesion promoter formed by combining a modified resin and a silane coupling agent (article number: N-481).

[0022] According to a second aspect of the present invention, a method for preparing a multi-coat and multi-bake paint for a bicycle is provided, the method comprising:

[0023] Step 1: Preparation of semi-finished coating

[0024] Add saturated polyester resin, diluent, titanium dioxide, bentonite and anti-settling agent into a reaction container, disperse at high speed and grind to a fineness of less than 15 μm to obtain a semi-finished coating;

[0025] Step 2: Preparation of multi-coat and multi-bake paint

[0026] After the semi-finished paint is cooled to room temperature, it is placed in a reaction container, and amino resin and adhesion promoter are added in sequence while stirring. After stirring for 1.5-3 hours, saturated polyester resin, diluent and catalyst are added in sequence. Stir and mix evenly to obtain a paint that can be coated and baked multiple times.

[0027] As an example, a method for preparing a multi-coat and multi-bake paint for a bicycle is as follows: saturated polyester resin, diluent, titanium dioxide, bentonite, and anti-settling agent are added to a reaction container, and then dispersed at high speed and ground to a fineness of less than 15 μm to obtain a semi-finished paint;

[0028] After the semi-finished coating is cooled to room temperature, it is placed in a reaction container, and butylated amino resin, adhesion promoter, and methylated amino resin are added in sequence while stirring. After stirring for 2 hours, saturated polyester resin, diluent, and catalyst are added in sequence, and stirred for 2 hours to mix evenly.

[0029] A third aspect of the present invention provides a bicycle multi-coat and multi-bake paint for use in realizing 20-coat and 20-bake high-end bicycle paint.

[0030] The present invention has the following advantages:

[0031] 1. The coating of the present invention has a high cross-linking density, and has both flexibility and toughness. Its impact resistance can be maintained after multiple coatings and multiple bakings (it can meet the requirements of 20 coatings and 20 bakings), and can meet the requirements of multiple color matching, rework, and heavy work processes for the paint film, reducing the embrittlement of the paint film, poor adhesion, and softening.

[0032] 2. The paint layer of the coating of the present invention has good flatness, reduces the formation of defects such as pinholes, fish eyes, and craters, has good leveling when used, increases the film thickness of the paint film formed by brushing or spraying, and can still maintain good flatness when recoated multiple times, ensuring the fullness of the appearance;

[0033] 3. The coating of the present invention is more suitable for multiple baking in the recoating process, has a greater tolerance to the environment such as temperature and humidity, and can still maintain good adhesion and recoating performance after multiple baking, greatly improving the yield rate and production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0035] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0036] Figure 1 This is an example of a test sample preparation process provided in Experimental Example 1 of the present invention; wherein, from 1 to 20 is the spraying sequence of 20 layers of paint film;

[0037] Figure 2 This is an experimental diagram for testing hardness provided in Experimental Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are

[0039] All of them belong to the protection scope of the present invention.

[0040] The anti-settling agent is a gel paste made by high-speed dispersion process with ethylene glycol butyl ether and diethylene glycol butyl ether acetate as solvents and W-2810 added.

[0041] Catalyst:MG-4401.

[0042] Example 1

[0043] This embodiment provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0044] (1) Add 22 parts of saturated polyester resin, 5 parts of diluent, 27 parts of titanium dioxide, 1 part of bentonite, and 3 parts of anti-settling agent into a reaction container, and grind to a fineness of less than 15 μm after high-speed dispersion to obtain a semi-finished coating;

[0045] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 14 parts of saturated polyester resin, 6 parts of adhesion promoter, and 14 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 4 parts of methylated amino resin, 3 parts of diluent, and 1 part of catalyst are added in sequence. Stir for 1.5 hours to mix well.

[0046] Example 2

[0047] This embodiment provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0048] (1) Add 17 parts of saturated polyester resin, 5 parts of diluent, 4 parts of carbon black powder, 1 part of bentonite, and 3 parts of anti-settling agent into a reaction container, and grind to a fineness of less than 15 μm after high-speed dispersion to obtain a semi-finished coating;

[0049] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 34 parts of saturated polyester resin, 7 parts of adhesion promoter, and 22 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 3 parts of methylated amino resin, 3 parts of diluent, and 1 part of catalyst are added in sequence. Stir for 2 hours to mix well.

[0050] Example 3

[0051] This embodiment provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0052] (1) Add 26 parts of saturated polyester resin, 6 parts of diluent, 26 parts of titanium dioxide, 1 part of bentonite, and 4 parts of anti-settling agent into a reaction container, and grind to a fineness of less than 15 μm after high-speed dispersion to obtain a semi-finished coating;

[0053] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 10 parts of saturated polyester resin, 5 parts of adhesion promoter, and 13 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 6 parts of methylated amino resin, 2 parts of diluent, and 1 part of catalyst are added in sequence. Stir for 3 hours to mix well.

[0054] Example 4

[0055] This embodiment provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0056] (1) Add 24 parts of saturated polyester resin, 4 parts of diluent, 9 parts of carbon black powder, 0 parts of bentonite, and 3 parts of anti-settling agent into a reaction container, and grind to a fineness of less than 15 μm after high-speed dispersion to obtain a semi-finished coating;

[0057] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 23 parts of saturated polyester resin, 6 parts of adhesion promoter, and 18 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 6 parts of methylated amino resin, 6 parts of diluent, and 1 part of catalyst are added in sequence. Stir for 2 hours to mix well.

[0058] Comparative Example 1

[0059] This comparative example provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0060] (1) Add 22 parts of saturated polyester resin, 5 parts of diluent, 26 parts of titanium dioxide, 1 part of bentonite, and 3 parts of anti-settling agent into a reaction container, and grind to a fineness of less than 15 μm after high-speed dispersion to obtain a semi-finished coating;

[0061] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 14 parts of saturated polyester resin, 6 parts of adhesion promoter, 14 parts of butylated amino resin, 4 parts of methylated amino resin, 4 parts of diluent and 1 part of catalyst are added in sequence while stirring, and stirred for 2 hours to mix evenly.

[0062] Comparative Example 2

[0063] This comparative example provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0064] (1) Add 30 parts of saturated polyester resin, 7 parts of diluent, 37 parts of titanium dioxide, 2 parts of bentonite, and 4 parts of anti-settling agent into a reaction container, and grind to a fineness of less than 15 μm after high-speed dispersion to obtain a semi-finished coating;

[0065] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 9 parts of adhesion promoter are added in sequence while stirring. After stirring for 2 hours, 5 parts of saturated polyester resin, 5 parts of diluent and 1 part of catalyst are added in sequence. Stir for 2 hours to mix well.

[0066] Comparative Example 3

[0067] This comparative example provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0068] (1) Add 29 parts of saturated polyester resin, 7 parts of diluent and 7 parts of titanium dioxide into a reaction container, disperse at high speed and grind to a fineness of less than 15 μm to obtain a semi-finished coating;

[0069] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 19 parts of saturated polyester resin, 8 parts of adhesion promoter, and 19 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 5 parts of methylated amino resin, 5 parts of diluent, and 1 part of catalyst are added in sequence. Stir for 2 hours to mix well.

[0070] Comparative Example 4

[0071] This comparative example provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0072] (1) Add 41 parts of saturated polyester resin, 5 parts of diluent, and 28 parts of carbon black powder into a reaction container, disperse at high speed, and grind to a fineness of less than 15 μm to obtain a semi-finished coating;

[0073] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 7 parts of adhesion promoter and 15 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 4 parts of diluent are added in sequence and stirred for 2 hours to mix evenly.

[0074] Comparative Example 5

[0075] This comparative example provides a method for preparing a bicycle multi-coat and multi-bake paint:

[0076] (1) Add 58 parts of saturated polyester resin, 5 parts of diluent, and 4 parts of carbon black powder into a reaction container, disperse at high speed, and grind to a fineness of less than 15 μm to obtain a semi-finished coating;

[0077] (2) After the semi-finished coating is cooled to room temperature, it is placed in a reaction container and 7 parts of adhesion promoter and 23 parts of butylated amino resin are added in sequence while stirring. After stirring for 2 hours, 3 parts of diluent are added in sequence and stirred for 2 hours to mix evenly.

[0078] Experimental Example 1

[0079] Sample preparation:

[0080] The coatings of Examples 1-4 and Comparative Examples 1-5 of the present application were respectively applied on aluminum tubes, and each layer was re-applied 20 times with a thickness of 17-23 μm. After application, the coatings were dried and tested.

[0081] The paint film hardness test and evaluation method are based on GB / T 6739-2022;

[0082] The test and evaluation method of the cross-cut test are based on GB / T 9286-2021;

[0083] The impact resistance test and evaluation method is based on GB / T 20624.2-2006, with a drop height of 1 meter and a punch diameter of 12.7 mm.

[0084] The solvent resistance wiping test and evaluation method are based on Method A of GB / T 23989-2009.

[0085] The test results are shown in Table 1.

[0086] Table 1

[0087]

[0088]

[0089] Experimental Example 2

[0090] The product of the present invention is versatile and practical. Various colored paints and varnishes may be used multiple times to achieve color effects or repair modifications in the actual spraying process. The multiple coatings and baking achieved by the present invention or a single commercially available product alone are difficult to meet the actual production needs of customers.

[0091] The coatings prepared in Examples 1 and 2 and the comparative example were sprayed on the aluminum tube in sequence with commercial paint and varnish, wherein the prepared coating was re-coated 4 times, the general commercial paint was re-coated 7 times, and the general commercial varnish was re-coated 9 times; each layer had a film thickness of 17-23 μm; a total of 20 layers were applied to attach Figure 1 Process making attachment Figure 2 Test the style.

[0092] In the figure: 0: substrate;

[0093] 1, 2, 7, and 12 are coatings of Examples 1 (white) and 2 (black) of the present invention, respectively;

[0094] 3, 4, 5, 6, 8, 13, 14, 15: YS-7327 paint respectively;

[0095] The rest is varnish.

[0096] It can be seen that the present invention can achieve the expected effect in terms of hardness by over-coating commercially available colored paint.

[0097] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A multi-coat and multi-bake paint for bicycles, characterized in that: The paint comprises saturated polyester resin, diluent, pigment, rheological additive, adhesion promoter, anti-settling agent, amino resin and catalyst.

2. A bicycle multi-coat and multi-bake paint according to claim 1, characterized in that: The raw materials of the paint are as follows: 36-52% of saturated polyester resin, 8-11% of diluent, 4-27% of pigment, 0-1% of rheological additive, 3-8% of adhesion promoter, 3-4% of anti-settling agent, 18-25% of amino resin and 0.5-1.5% of catalyst.

3. The bicycle multi-coat and multi-bake paint according to claim 1, characterized in that: The pigment is titanium dioxide or carbon black powder.

4. The bicycle multi-coat and multi-bake paint according to claim 1, characterized in that: The rheological additive is bentonite.

5. The bicycle multi-coat and multi-bake paint according to claim 1, characterized in that: The diluent is a polyurethane diluent.

6. The bicycle multi-coat and multi-bake paint according to claim 1, characterized in that: The anti-settling agent is a gel paste with a diluent as a solvent.

7. The multi-coat and multi-bake paint for bicycles according to claim 1, characterized in that: The amino resin is butylated amino resin and methylated amino resin.

8. The bicycle multi-coat and multi-bake paint according to claim 1, characterized in that: The adhesion promoter is formed by combining a modified resin with a silane coupling agent.

9. A method for preparing a multi-coat and multi-bake paint for a bicycle, characterized in that: The method comprises: Step 1: Preparation of semi-finished coating Add saturated polyester resin, diluent, titanium dioxide, bentonite and anti-settling agent into a reaction container, disperse at high speed and grind to a fineness of less than 15 μm to obtain a semi-finished coating; Step 2: Preparation of multi-coat and multi-bake paint After the semi-finished paint is cooled to room temperature, it is placed in a reaction container, and amino resin and adhesion promoter are added in sequence while stirring. After stirring for 1.5-3 hours, saturated polyester resin, diluent and catalyst are added in sequence. Stir and mix evenly to obtain a paint that can be coated and baked multiple times.

10. Application of a bicycle multi-coat and multi-bake paint in realizing 20-coat 20-bake high-end bicycle coating.

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