Colorful transparent corrosion-resistant primer composition as well as preparation method and application thereof

Abstract

The invention discloses a colored transparent corrosion-resistant primer composition as well as a preparation method and application thereof. The primer composition comprises the following raw material components in parts by weight: 12.7 to 20.4 parts of polyester resin; 1.0 to 2.0 parts of epoxy resin; 1.0 to 2.0 parts of blocked isocyanate; 5.7 to 8.9 parts of amino resin; 1.0 to 3.0 parts of color paste; 2.2 to 4.2 parts of an auxiliary agent; 68.9 to 74.9 parts of a solvent; wherein the auxiliary agent is prepared from 1.1 to 1.7 parts of a silane coupling agent; 1.0 to 2.3 parts of a corrosion inhibitor; 0.1 to 0.2 part of a leveling agent; the polyester resin has the following characteristics: (1) the molecular weight is 15000 to 18000; (2) the hydroxyl value is 5 to 7 mgKOH / g; (3) the glass transition temperature is 52-67 DEG C; and (4) the structure of the polyester resin molecule is a linear structure. The colored transparent corrosion-resistant primer composition can be matched with liquid varnish or transparent powder to be used in coating of an automobile aluminum alloy finish turning hub, and good color permeability, adhesive force, corrosion resistance and water resistance can be provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology. More particularly, it relates to a color transparent corrosion-resistant primer composition, and a preparation method and application thereof. BACKGROUND

[0002] With the development of the automobile industry, in the automobile wheel hub coating industry, in order to meet the requirements of beauty and personality, the demand for precision turning of the surface of the aluminum alloy wheel hub coated with powder primer and color paint is increasing. The exposed aluminum alloy bright surface is then sprayed with transparent primer and transparent varnish (transparent powder or liquid varnish). On this basis, in order to enhance the difference and beauty of color, the precision turning bright surface is matched with color transparent coating, which is more beautiful. Therefore, the development of color transparent primer becomes the key. The color transparent primer composition is mainly composed of polyester resin, epoxy resin, blocked isocyanate and amino resin as the main film-forming material. Through the chemical reaction between the components, a body network structure with insolubility and non-fusion is formed, which has excellent adhesion, good corrosion resistance, water resistance and other properties, and is widely used in the coating of precision turning aluminum alloy wheel hub of automobile. In order to protect the precision turning bright surface of aluminum alloy from corrosion and oxidation, liquid varnish or transparent powder is usually coated on the surface of the wheel hub after precision turning. At present, the wheel hub matched with transparent powder uses liquid varnish to adjust color as a color transparent layer. The liquid varnish is sprayed on the transparent powder layer after baking. Because the curing and baking temperature range of the liquid varnish is 140-160℃, it cannot withstand the temperature of 180-190℃ of the transparent powder baking, so it cannot be re-coated. For the wheel hub that does not meet the requirements of one-time product, it cannot be reworked and can only be scrapped. In addition, the wheel hub matched with liquid varnish also uses primer as color transparent corrosion-resistant primer, but the corrosion resistance cannot meet the performance requirements of CASS240H and TAC 8 cycles, and the primer is not resistant to high temperature, so it can only be matched with liquid varnish and cannot be matched with transparent powder, which is limited in use. At present, there is no report on a color transparent corrosion-resistant primer composition that meets the application requirements of both transparent powder and liquid varnish. SUMMARY

[0003] To solve the above problems, the first object of the present application is to provide a color transparent corrosion-resistant primer composition. The color transparent corrosion-resistant primer composition can be used with powder varnish or solvent type liquid varnish, has good color transparency, adhesion, corrosion resistance and water resistance, and can be well used in the coating of precision turning aluminum alloy wheel hub of automobile.

[0004] The second object of the present application is to provide a preparation method of the primer composition as described above.

[0005] The third object of the present application is to provide a color transparent corrosion-resistant primer.

[0006] The fourth object of the present application is to provide a color transparent corrosion-resistant primer coating.

[0007] The fifth object of the present application is to provide an application of the primer composition as described above in the coating of an automobile aluminum alloy finish wheel hub.

[0008] To achieve the above-mentioned first object, the present application adopts the following technical solution:

[0009] The present application discloses a color transparent corrosion-resistant primer composition, which comprises the following raw material components according to 100 parts of total weight:

[0010]

[0011] The auxiliary agent comprises

[0012] 1.1-1.7 parts of silane coupling agent;

[0013] 1.0-2.3 parts of corrosion inhibitor;

[0014] 0.1-0.2 parts of leveling agent;

[0015] The polyester resin has the following characteristics:

[0016] (1) a molecular weight of 15000-18000; (2) a hydroxyl value of 5.0-7.0 mgKOH / g; (3) a glass transition temperature of 52-67℃; and (4) a linear structure of the polyester resin molecule.

[0017] Further, the primer composition comprises the following raw material components according to 100 parts of total weight:

[0018]

[0019] Further, the polyester resin has a non-volatile content of 100.0%, a hydroxyl value of 6.0 mgKOH / g, and is selected from SKYBON ES 450 of Aisikai Environmental Protection Materials (Yantai) Co., Ltd. and / or DYNAPOL L 205 of Yincui Special Chemical (Shanghai) Co., Ltd.

[0020] Further, the epoxy resin is a bisphenol A type epoxy resin, and has a non-volatile content of 50.0-55.0%;

[0021] The non-volatile content of the blocked isocyanate is 74.0-76.0%, and the blocked NCO content is 10.5-11.1%;

[0022] The amino resin is a partially methyl etherified amino resin, and has a non-volatile content of 78.0-82.0%.

[0023] Further, the epoxy resin is selected from MAS 9003 of Shenzhen Li Hua Xin Trading Co., Ltd. and / or EP-0150 VARNISH of Nippon Shokubai Co., Ltd.

[0024] Further, the blocked isocyanate is selected from DESMODUR BL 3175SN and / or DESMODUR BL 3575SN of Bayer MaterialScience AG.

[0025] Further, the amino resin is selected from M 40 ST of Changchun Synthetic Resin Factory Co., Ltd. and / or Resimene 735 of Prefere Melamines LLC.

[0026] Further, the non-volatile matter content of the primer composition is 20.0-32.7%, and the viscosity is 17.0-27.0 seconds / 20℃*4 cups.

[0027] Further, the effective ingredient content of the silane coupling agent is >99.0%;

[0028] The corrosion inhibitor is selected from an organic corrosion inhibitor;

[0029] The leveling agent is selected from a polyester-modified silicone type;

[0030] The solvent is selected from one or more of an ester type solvent, a ketone type solvent and an aromatic hydrocarbon type solvent.

[0031] Further, the ester type solvent is selected from at least one of ethyl acetate, butyl acetate and propylene glycol methyl ether acetate;

[0032] The ketone type solvent is selected from at least one of cyclohexanone, methyl isobutyl ketone and isoforone;

[0033] The aromatic hydrocarbon type solvent is selected from one of S-150# solvent oil and S-100# solvent oil.

[0034] To achieve the above-mentioned second object, the application adopts the following technical scheme:

[0035] The application discloses a preparation method of the primer composition as described above, comprising the following steps:

[0036] (1) A part of the solvent is put into a container, and the polyester resin is put into the container under stirring, so that the polyester resin is completely dissolved to obtain a polyester resin mixture;

[0037] (2) The epoxy resin, the blocked isocyanate and the amino resin are sequentially put into the container under stirring, and after stirring for 20-30 min, a resin mixture is obtained;

[0038] (3) continue to put various types of additives, color paste and the remaining solvent into the container, stir for 20-30 min and adjust the color to the standard requirement to obtain the primer composition.

[0039] To achieve the third object, the application adopts the following technical scheme:

[0040] The application discloses a color transparent corrosion-resistant primer, which is prepared from raw materials of the color transparent corrosion-resistant primer composition.

[0041] To achieve the fourth object, the application adopts the following technical scheme:

[0042] The application discloses a color transparent corrosion-resistant primer coating, which is prepared from the color transparent corrosion-resistant primer.

[0043] To achieve the fifth object, the application adopts the following technical scheme:

[0044] The application discloses application of the primer composition in coating of an aluminum alloy fine-turning wheel hub.

[0045] The application has the following beneficial effects:

[0046] In the technical scheme of the application, the color transparent corrosion-resistant primer composition is prepared from selected raw materials, and the raw materials are matched and controlled in quantity, so that the primer composition can be wetly sprayed and constructed with transparent powder or liquid varnish, and the composite coating has good adhesion, corrosion resistance and water resistance. The color transparent corrosion-resistant primer composition provided by the application can be well applied in coating of an aluminum alloy fine-turning wheel hub, improves corrosion resistance of the fine-turning bright surface, and makes the appearance color of the fine-turning wheel hub diversified. DETAILED DESCRIPTION

[0047] In order to more clearly illustrate the application, the application will be further described below in combination with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than limiting, and should not limit the protection scope of the application.

[0048] In order to provide a color transparent corrosion-resistant primer composition suitable for coating of an aluminum alloy fine-turning wheel hub, which can be used in combination with transparent powder or liquid varnish, has good adhesion, corrosion resistance and water resistance, one specific embodiment of the application provides a color transparent corrosion-resistant primer composition, which contains the following raw material components, based on 100 parts of total weight:

[0049]

[0050]

[0051] The adjuvant contains:

[0052] 1.1-1.7 parts of silane coupling agent;

[0053] Corrosion inhibitor 1.0-2.3 parts;

[0054] Leveling agent 0.1-0.2 parts.

[0055] Furthermore, based on a total weight of 100 parts, the primer composition comprises the following raw material components:

[0056]

[0057] In the technical solution of this invention, polyester resin, blocked isocyanate, epoxy resin and amino resin with specific properties are used as the main film-forming substances. The combination of polyester resin, blocked isocyanate and amino resin improves the flexibility of the colored transparent primer film. When the colored transparent corrosion-resistant primer is used in combination with transparent powder, the adhesion is excellent and there are no abnormal phenomena such as paint peeling. With the addition of a small amount of epoxy resin, the salt spray resistance of the colored transparent primer is improved without sacrificing weather resistance.

[0058] In some examples, the polyester resin has the following characteristics:

[0059] (1) Molecular weight is 15,000-18,000;

[0060] (2) The hydroxyl value is 5.0-7.0 mg KOH / g;

[0061] (3) The glass transition temperature is 52-67℃;

[0062] (4) The structure of polyester resin molecules is linear.

[0063] In some examples, the polyester resin used in this invention has a non-volatile content of 100.0% and is solid at room temperature, including but not limited to SKYBON ES 450 (purchased from SK Environmental Materials (Yantai) Co., Ltd.), which has a non-volatile content of 100%, a molecular weight of 18000, a hydroxyl value of 6.0 mgKOH / g, and a glass transition temperature of 52°C; or DYNAPOL L 205 (purchased from Evonik Specialty Chemicals (Shanghai) Co., Ltd.), which has a non-volatile content of 100%, a molecular weight of 16000, a hydroxyl value of 6.0 mgKOH / g, and a glass transition temperature of 67°C. If thermoplastic, incompletely crystalline polyester resins are selected (such as DYNAPOL P 1500, etc.), their glass transition temperature is lower, their surface drying rate is slower than that of the polyester resin of this invention, and their adhesion to machined aluminum alloy surfaces is slightly worse.

[0064] The use of the aforementioned polyester resin, while meeting other performance requirements of the primer composition, also imparts good flexibility, corrosion resistance, and adhesion to the paint film. When using polyester resin, technicians can directly purchase solid polyester resin products that meet the above-mentioned characteristics. These products are solid polyester resins with a non-volatile content of 100.0% and are solid at room temperature (e.g., SKYBON ES 450 from SK Environmental Materials (Yantai) Co., Ltd.). Pre-dispersion treatment is required before use, or a pre-dispersed polyester resin dispersion with a good solvent can be used. The usage should be calculated based on the solid content of the polyester resin.

[0065] Furthermore, the epoxy resin is a bisphenol A type epoxy resin with a non-volatile content of 50.0-55.0%. For example, the non-volatile content of the epoxy resin includes, but is not limited to, 50.0%, 51.0%, 52.0%, 53.0%, 54.0%, 55.0%, etc.

[0066] In some examples, the use of epoxy resin described in this embodiment not only meets other performance requirements of the primer composition, but also imparts good adhesion, corrosion resistance and other properties to the paint film.

[0067] Specifically, the epoxy resin includes, but is not limited to, MAS 9003 (purchased from Shenzhen Lihua Xinmao Co., Ltd.), with a non-volatile content of 55.0%; or EP-0150VARNISH (purchased from Nippon Steel Chemical Co., Ltd.), with a non-volatile content of 50.0%.

[0068] In this technical solution, the combination of polyester resin and blocked isocyanate further enhances the flexibility of the paint film; a small amount of epoxy resin further improves the adhesion and corrosion resistance of the primer on aluminum alloy; and the combination with amino resin gives the paint film good cross-linking and curing properties. If the amounts of polyester resin, blocked isocyanate, and amino resin are not within the required range, the flexibility, hardness, and corrosion resistance of the paint film will be affected.

[0069] In some examples, the blocked isocyanate has one or more of the following characteristics:

[0070] (1) The content of non-volatile matter is 74.0-76.0%;

[0071] (2) The NCO content of the closed-type is 10.5-11.1%;

[0072] The use of the blocked isocyanate described in this embodiment not only meets other performance requirements of the primer composition, but also imparts good adhesion and flexibility to the paint film when used in combination with transparent powder.

[0073] Specifically, the blocked isocyanate includes, but is not limited to, DESMODUR BL 3175SN (purchased from Bayer MaterialScience AG), with a non-volatile content of 74.0-76.0% and a blocked NCO content of 11.1%; or DESMODUR BL 3575SN (purchased from Bayer MaterialScience AG), with a non-volatile content of 74.0-76.0% and a blocked NCO content of 10.5%.

[0074] Adding too much blocked isocyanate can cause the paint film to discolor and turn white due to water resistance issues; adding too little blocked isocyanate will affect the flexibility and adhesion of the paint film.

[0075] In some examples, the amino resin is a partially methylated amino resin with a non-volatile content of 78.0-82.0%.

[0076] Specifically, the amino resin may include, but is not limited to, M 40ST (purchased from Changchun Artificial Resin Factory Co., Ltd.), with a non-volatile content of 78.0-82.0%; or Resimene 735 (purchased from Prefere Melamines LLC), with a non-volatile content of 78.0-82.0%.

[0077] Excessive use of amino resin can lead to excessive cross-linking of the paint film, making the paint film brittle and resulting in substandard adhesion; insufficient use of amino resin can lead to substandard water resistance and corrosion resistance of the paint film.

[0078] In this embodiment, further research revealed that the ratio of film-forming resins also affects the water resistance and corrosion resistance of the final coating film. When the mass ratio of polyester resin, blocked isocyanate, epoxy resin, and amino resin is 12.7-13.5:1.3-1.7:1.0-1.5:6.0-6.3, the aforementioned effects are better overall.

[0079] Furthermore, the addition of silane coupling agents and corrosion inhibitors improves the copper-accelerated acetate mist (CASS) resistance and cyclic corrosion (TAC) resistance of the colored transparent corrosion-resistant primer.

[0080] In some examples, the active ingredient content of the silane coupling agent is >99.0%.

[0081] Specifically, the silane coupling agent is KBM 403 (purchased from Shin-Etsu Chemical Co., Ltd.), with an active ingredient content >99.0%; or it can be OFS-6040 (purchased from Dow Corning), with an active ingredient content >99.0%.

[0082] In some examples, the corrosion inhibitor is a solid powder with a non-volatile content of 100%.

[0083] Specifically, the corrosion inhibitor is CANFAIR PPOA (purchased from Guangzhou Chenhui Chemical Co., Ltd.), with a non-volatile content of 100%; or it can be HALOX 650 (purchased from HALOX Company), with a non-volatile content of 100%.

[0084] In some examples, the leveling agent is BYK 310 (purchased from BYK) with a non-volatile content of 25%; or it may be BYK 315 (purchased from BYK) with a non-volatile content of 25%.

[0085] Ketone solvents are good solvents for the polyester resin of this invention. Adding a portion of ketone solvents improves the solvent's solubility in the polyester resin, which facilitates coating production. At the same time, it improves the coating's storage stability and application solids content. The increase in application solids content also helps to increase film thickness under the same spraying parameters.

[0086] Specifically, the ketone solvent includes, but is not limited to, one or a combination of cyclohexanone, methyl isobutyl ketone or isoflurane. In some preferred embodiments, the ketone solvent is 3.2-5.2 parts of isoflurane and 7.2-9.2 parts of methyl isobutyl ketone.

[0087] In some examples, ester solvents play a dispersing and diluting role in the formulation of colored clear primers. Combined with ethyl acetate, which has a fast evaporation rate, the surface drying properties of the colored clear primers are improved, and abnormal sagging during application is avoided.

[0088] Specifically, the ester solvent is selected from one or a combination of ethyl acetate, butyl acetate and propylene glycol methyl ether acetate. In some preferred embodiments, the propylene glycol methyl ether acetate is 25.2-29.2 parts and the ethyl acetate is 10.6-12.6 parts.

[0089] Furthermore, the non-volatile content of the colored transparent corrosion-resistant primer composition is 20.0-32.7%, and the viscosity is 17.0-27.0 seconds (Ford Cup 4, 20°C).

[0090] According to another specific embodiment of the present invention, a method for preparing a colored transparent corrosion-resistant primer composition is provided, comprising the following steps:

[0091] (1) First, add some solvent (such as propylene glycol methyl ether acetate, isoflurone, methyl isobutyl ketone) to the container and stir at 400-500 r / min. Then add the amount of polyester resin in the formula. After the polyester resin is completely dissolved, a polyester resin mixture is obtained.

[0092] (2) While stirring, add the formulated amount of epoxy resin, blocked isocyanate and amino resin into the container in sequence, stir for 20-30 minutes to obtain a resin mixture;

[0093] (3) Continue to add the formulation amount of various additives (such as silane coupling agent, corrosion inhibitor, leveling agent) to the container, stir for 20-30 minutes, add color paste, and finally add the remaining solvent (such as ethyl acetate, S-100# solvent oil, etc.) to rinse the container wall and stirring paddle, stir for 20-30 minutes and adjust the color to the standard requirements to obtain the colored transparent corrosion resistant primer composition.

[0094] In the preparation of this primer composition, the polyester resin is first dispersed in a suitable solvent, such as a mixed solvent of propylene glycol methyl ether acetate, isoflurane and methyl isobutyl ketone. This combination of three solvents can quickly dissolve the polyester resin. If an aromatic solvent or a mixture of some ketone solvent and aromatic solvent is added first, the polyester resin cannot be fully dispersed and easily appears as white flocculent material.

[0095] In the preparation of this primer composition, if other resins besides polyester resin are added first, and then polyester resin is added, it will affect the dissolution and dispersion of polyester resin, and may result in fine particles, affecting the appearance and performance of the coating film.

[0096] Compared to using ketone solvents alone, adding different ester solvents and aromatic solvents can regulate the solvent evaporation rate, resulting in better workability of the primer composition and effectively reducing the strong irritating odor of ketone solvents.

[0097] According to another specific embodiment of the present invention, a colored transparent corrosion-resistant primer is provided, which is prepared from the raw materials of the colored transparent corrosion-resistant primer composition as described above.

[0098] According to another specific embodiment of the present invention, a colored transparent corrosion-resistant coating is provided, which is prepared by comprising the colored transparent corrosion-resistant primer as described above.

[0099] According to another specific embodiment of the present invention, the application of the colored transparent corrosion-resistant primer composition as described above in the coating of automotive aluminum alloy precision wheel hubs is provided.

[0100] In some instances, the application includes the following steps:

[0101] (1) Compatible with liquid varnish

[0102] The colored transparent corrosion-resistant primer composition is sprayed onto the precision-machined aluminum alloy wheel hub of an automobile, followed by flash-drying and leveling.

[0103] Continue spraying liquid varnish and let it cure to obtain a composite coating.

[0104] Furthermore, the flash drying and leveling conditions are at room temperature for at least 6 minutes.

[0105] Furthermore, the curing temperature is 140-150℃ and the time is 15-35 min, preferably 20 min.

[0106] Furthermore, the spraying method is air spraying and / or electrostatic cup spraying.

[0107] Furthermore, the thickness of the sprayed colored transparent corrosion-resistant primer composition is 15-20 μm.

[0108] Furthermore, the thickness of the sprayed liquid varnish is 25-30μm.

[0109] Furthermore, the thickness of the resulting composite coating is 40-50 μm.

[0110] (2) Compatible with transparent powder

[0111] The colored transparent corrosion-resistant primer composition is sprayed onto the precision-finished aluminum alloy wheel hub of an automobile, followed by flash drying, leveling, and curing.

[0112] Powder varnish is sprayed and cured to obtain a composite coating.

[0113] Furthermore, the flash drying and leveling conditions are at room temperature for at least 6 minutes.

[0114] Furthermore, the primer is cured at a temperature of 140-150℃ for 15-35 minutes, preferably 20 minutes.

[0115] Furthermore, the transparent powder is cured at a temperature of 180-190℃ for a time of 15-35 minutes, preferably 20 minutes.

[0116] Furthermore, the primer is applied by air spraying and / or electrostatic cup spraying, and the transparent powder is applied by electrostatic spraying.

[0117] Furthermore, the thickness of the sprayed colored transparent corrosion-resistant primer composition is 15-20 μm.

[0118] Furthermore, the thickness of the sprayed powder varnish is 80-100μm.

[0119] Furthermore, the thickness of the obtained composite coating is 95-120 μm.

[0120] The technical solution of the present invention will be described below with reference to some specific embodiments. Unless otherwise specified, the following parts (numbers) represent parts by weight.

[0121] The relevant raw material model and manufacturer used in the example are described as follows:

[0122] Polyester resins: SKYBON ES 450, purchased from SK Environmental Materials (Yantai) Co., Ltd.; DYNAPOL L205, purchased from Evonik Specialty Chemicals (Shanghai) Co., Ltd.

[0123] Epoxy resin: MAS 9003, purchased from Shenzhen Lihua Xinmao Co., Ltd.; EP-0150VARNISH, purchased from Nippon Steel Chemical Co., Ltd.

[0124] Blocked isocyanates: DESMODUR BL 3175SN, purchased from Bayer MaterialScience AG; DESMODUR BL 3575SN, purchased from Bayer MaterialScience AG;

[0125] Amino resins: M 40ST, purchased from Changchun Artificial Resin Factory Co., Ltd.; Resimene 735, purchased from Prefere Melamines LLC;

[0126] Silane coupling agents: KBM 403, purchased from Shin-Etsu Chemical Co., Ltd.; OFS-6040, purchased from Dow Corning.

[0127] Corrosion inhibitors: CANFAIR PPOA, purchased from Guangzhou Chenhui Chemical Co., Ltd.; HALOX 650, purchased from HALOX.

[0128] Leveling agents: BYK 310, purchased from BYK Company; BYK 315, purchased from BYK Company.

[0129] Example 1

[0130] Colored transparent corrosion-resistant primer composition 1

[0131] Colored transparent corrosion-resistant primer composition 1 was prepared according to the formulation shown in Table 1 below.

[0132] Table 1. Raw material weight parts for Example 1

[0133]

[0134] The preparation of the colored transparent corrosion-resistant primer composition 1 includes the following steps:

[0135] (1) First, add 27.20 parts of propylene glycol methyl ether acetate, 4.20 parts of isoflurane, and 8.20 parts of methyl isobutyl ketone to the container and stir at 400-500 r / min. Then add 13.50 parts of polyester resin. After the polyester resin is completely dissolved, a polyester resin mixture is obtained.

[0136] (2) Continue to add the following components in sequence while stirring: 1.50 parts of epoxy resin, 1.50 parts of blocked isocyanate and 6.15 parts of amino resin. Stir for 20-30 minutes to obtain a resin mixture.

[0137] (3) Add 0.15 parts of leveling agent BYK 310, 1.50 parts of silane coupling agent OFS-6040, and 2.00 parts of corrosion inhibitor HALOX 650. Stir for 20-30 minutes, add 1.50 parts of black resin-free pigment, and finally add 11.60 parts of the remaining solvent ethyl acetate and 21.00 parts of S-100# solvent oil to rinse the container wall and the stirring paddle. Stir for 20-30 minutes and adjust the color to the standard requirements to obtain the colored transparent corrosion-resistant primer composition 1.

[0138] Comparative Example 1

[0139] Colored transparent corrosion-resistant primer composition C1

[0140] The preparation process of Example 1 was repeated, except that commercially available polyester resin DYNAPOL P 1500 (100.0% non-volatile content, molecular weight 15000, glass transition temperature 25°C, solid) was used instead of polyester resin DYNAPOL L 205 in Example 1. The amounts of other materials remained unchanged. Compared to the polyester resin in Example 1, DYNAPOL P1500 is a thermoplastic, incompletely crystalline polyester resin.

[0141] Comparative Example 2

[0142] Colored transparent corrosion-resistant primer composition C2

[0143] The preparation process of Example 1 was repeated, except that commercially available epoxy resin EPIKOTE 1001-X-75 (with a non-volatile content of 74.0-75.0%) was used to replace the epoxy resin MAS 9003 in Example 1, while the amounts of other materials remained unchanged. Compared to the epoxy resin in Example 1, the epoxy resin EPIKOTE 1001-X-75 has a higher non-volatile content.

[0144] Comparative Example 3

[0145] Colored transparent corrosion-resistant primer composition C3

[0146] The preparation process of Example 1 was repeated, except that commercially available blocked isocyanate DESMODUR BL3475 was used instead of the blocked isocyanate in Example 1, while the amounts of other materials remained unchanged. Compared to the blocked isocyanate in Example 1, the blocked isocyanate DESMODUR BL 3475 has a non-volatile content of 75.0% and a blocked NCO content of 8.2%.

[0147] Comparative Example 4

[0148] Colored transparent corrosion-resistant primer composition C4

[0149] The preparation process of Example 1 was repeated, except that the amount of polyester resin and blocked isocyanate was adjusted. The specific raw material weight parts are shown in Table 2.

[0150] Table 2 Comparative Example 4 Raw Material Weight Parts

[0151]

[0152] Comparative Example 5

[0153] Colored transparent corrosion-resistant primer composition C5

[0154] The preparation process of Example 1 was repeated, except that the amount of polyester resin and blocked isocyanate was adjusted. The specific raw material weight parts are shown in Table 3.

[0155] Table 3 Comparative Example 5 Raw Material Weight Parts

[0156]

[0157]

[0158] Comparative Example 6

[0159] Colored transparent corrosion-resistant primer composition C6

[0160] The preparation process of Example 1 was repeated, except that the amount of epoxy resin and S-100# solvent oil was adjusted. The specific weight parts of the raw materials are shown in Table 4.

[0161] Table 4 Comparative Example 6 Raw Material Weight Parts

[0162]

[0163] Comparative Example 7

[0164] Colored transparent corrosion-resistant primer composition C7

[0165] The preparation process of Example 1 was repeated, except that the amount of epoxy resin and S-100# solvent oil was adjusted. The specific weight parts of the raw materials are shown in Table 5.

[0166] Table 5 Comparative Example 7 Raw Material Weight Parts

[0167]

[0168]

[0169] Comparative Example 8

[0170] Colored transparent corrosion-resistant primer composition C8

[0171] The preparation process of Example 1 was repeated, except that the amount of amino resin and S-100# solvent oil was adjusted. The specific weight parts of the raw materials are shown in Table 6.

[0172] Table 6 Comparative Example 8 Raw Material Weight Parts

[0173]

[0174] Comparative Example 9

[0175] Colored transparent corrosion-resistant primer composition C9

[0176] The preparation process of Example 1 was repeated, except that the amount of amino resin and S-100# solvent oil was adjusted. The specific weight parts of the raw materials are shown in Table 7.

[0177] Table 7 Comparative Example 9 Raw Material Weight Parts

[0178]

[0179]

[0180] Comparative Example 10

[0181] Colored transparent corrosion-resistant primer composition C10

[0182] The preparation process of Example 1 was repeated, except that the amount of solids such as commercially available liquid saturated polyester resin PB 296 (non-volatile content of 69.0-71.0%, liquid) was used to replace the amount of polyester resin DYNAPOL L 205 in Example 1, while the amounts of other materials remained unchanged.

[0183] Experimental Example 1:

[0184] Performance testing of colored transparent primer compositions

[0185] a) Constructability

[0186] Substrate: Pre-treated aluminum alloy wheel hub

[0187] Compatible with liquid varnish:

[0188] Coating 1 consists of: aluminum alloy precision wheel hub + colored transparent primer (flash-dry, level, room temperature * 8min) + liquid clear varnish (curing, curing temperature is 145℃, time is 20min), thus obtaining a colored transparent primer composite coating 1 with a thickness of 40-50μm sprayed on the aluminum alloy precision wheel hub.

[0189] Compatible with transparent powder:

[0190] Coating 2 consists of: aluminum alloy precision wheel hub + colored transparent primer (flash-dry, level, room temperature * 8min + curing, curing temperature is 140-150℃, time is 20min) + transparent powder (curing, curing temperature is 185℃, time is 20min), thus obtaining a colored transparent primer composite coating 2 with a thickness of 95-120μm sprayed on the aluminum alloy precision wheel hub.

[0191] Painting process:

[0192] Colored transparent primer: Air automatic spray gun, air pressure 0.25 MPa, output 100cc, primer spray viscosity 17.0-19.0 seconds / 20℃*Ford cup 4; dry film thickness 15-20μm.

[0193] Liquid varnish: electrostatic cup spraying, cup diameter 65mm, voltage 60Kv, cup speed 20000rpm, discharge volume 300cc, varnish spraying viscosity 22.0-24.0s / 20℃*Ford 4 cup; dry film thickness 25-30μm.

[0194] Transparent powder: electrostatic spraying, voltage 35Kv, powder output 40%, air pressure 3.5N / m 3 .

[0195] b) Preparation of test specimens for coating performance, namely, cutting off individual spokes of aluminum alloy precision wheel hubs with construction test coating for coating performance testing.

[0196] The testing methods for coating performance are shown in Tables 8 and 9.

[0197] Table 8. Coating performance testing methods (for use with liquid varnishes)

[0198]

[0199]

[0200] Table 9 Performance Testing Methods (with Transparent Powder)

[0201]

[0202] The performance of the colored transparent primers of Example 1 and Comparative Examples 1-10 was tested using the above method, and the results are shown in Tables 10 to 13.

[0203] Table 10 Performance of the primers in Examples 1 and Comparative Examples 1-4 (in conjunction with liquid varnish)

[0204]

[0205]

[0206] Table 11 Performance of primers in comparative examples 5-10 (combined with liquid clear coat)

[0207]

[0208]

[0209] Table 12 Performance of the primers in Examples 1 and Comparative Examples 1-4 (with transparent powder)

[0210]

[0211]

[0212] Table 13 Performance of primers in comparative examples 5-10 (with transparent powder)

[0213]

[0214]

[0215] As can be seen from Tables 10 and 12, the colored transparent corrosion-resistant primer composition prepared in Example 1, when sprayed under standard construction conditions, showed no abnormalities in the appearance of the paint film, and its adhesion, corrosion resistance, and water resistance were all qualified.

[0216] Comparative Example 1 used commercially available polyester resin DYNAPOL P 1500 (100.0% non-volatile content, molecular weight 15000, glass transition temperature 25°C) in equal amounts to replace the polyester resin in Example 1, while the amounts of other materials remained unchanged. Compared to the polyester resin in Example 1, DYNAPOL P 1500 is a thermoplastic, incompletely crystalline polyester resin. Using this type of polyester resin resulted in substandard corrosion resistance (CASS, SST, and Filiform) and adhesion. This was due to an imbalance in the ratio of reactive groups between the polyester resin and amino resin in Comparative Example 1 compared to Example 1, insufficient cross-linking of the paint film, and inherently poor corrosion resistance.

[0217] Comparative Example 2 used commercially available epoxy resin EPIKOTE 1001-X-75 (non-volatile content 74.0-75.0%) in solid form to replace the epoxy resin in Example 1, while the amounts of other materials remained unchanged. Compared to the epoxy resin in Example 1, EPIKOTE 1001-X-75 has a higher non-volatile content. This epoxy resin has poor miscibility with the main resin, resulting in a hazy and less transparent primer film, and also causing the corrosion resistance (CASS and Filiform) to fail the tests.

[0218] Comparative Example 3 used commercially available blocked isocyanate DESMODUR BL 3475 in solid quantities to replace the blocked isocyanate in Example 1, while the amounts of other materials remained unchanged. The blocked isocyanate DESMODUR BL 3475 has a non-volatile content of 75.0% and a relatively low blocked NCO content of 8.2%. Using this type of blocked isocyanate leads to reduced flexibility of the colored transparent primer. When used with transparent powder, it fails the scratch resistance test, exhibits paint film peeling at the scratch edge before the CASS test, exceeds the corrosion width limit in the CASS test, and fails the adhesion test after the CASS test.

[0219] In Comparative Example 4, with other resin dosages remaining constant, the amount of blocked isocyanate used was 3 parts, which exceeds the upper limit of the dosage range specified in this invention. Excessive use of blocked isocyanate will lead to unsatisfactory adhesion of the composite coating after salt spray and artificial aging tests.

[0220] In Comparative Example 5, with the amino resin dosage remaining constant, the amount of polyester resin used was 14.50 parts, exceeding the upper limit of the dosage range specified in this invention; the amount of the blocked isocyanate was 0.50 parts, lower than the lower limit of the dosage range specified in this invention. Excessive use of polyester resin and insufficient use of blocked isocyanate can lead to an imbalance in the crosslinking ratio of the paint film, resulting in substandard corrosion resistance (CASS, TAC) of the composite coating.

[0221] In Comparative Example 6, with the amounts of polyester resin, blocked isocyanate, and amino resin remaining constant, the amount of epoxy resin used was 0.50 parts, which is lower than the lower limit of the usage ratio specified in this invention. Too low an amount of epoxy resin will result in the corrosion resistance (SST) of the matching liquid varnish composite coating failing to meet the requirements.

[0222] In Comparative Example 7, with the amounts of polyester resin, blocked isocyanate, and amino resin remaining constant, the amount of epoxy resin was 2.50 parts, exceeding the upper limit of the dosage ratio specified in this invention. Excessive epoxy resin dosage leads to yellowing of the composite coating with the accompanying transparent powder and failure to pass the artificial aging test.

[0223] In Comparative Example 8, with the amounts of polyester resin, blocked isocyanate, and epoxy resin remaining constant, the amount of amino resin was 7.15 parts, which is higher than the upper limit of the proportion specified in this invention. Excessive use of amino resin can lead to over-crosslinking of the paint film, making the film brittle and resulting in failure to pass adhesion and scratch tests.

[0224] In Comparative Example 9, with the amounts of polyester resin, blocked isocyanate, and epoxy resin remaining unchanged, the amount of amino resin was 5.15 parts, which is lower than the lower limit of the amount ratio specified in this invention. Too low an amount of amino resin will result in insufficient crosslinking density of the paint film, leading to unsatisfactory water resistance and corrosion resistance (CASS, SST, and Filiform).

[0225] Comparative Example 10 used commercially available liquid saturated polyester resin PB 296 (non-volatile content 69.0-71.0%, liquid) in equal amounts to replace the polyester resin in Example 1, while the amounts of other materials remained unchanged. Compared to the polyester resin in Example 1, PB 296 is a liquid polyester with a non-linear structure. Using this type of polyester resin results in substandard corrosion resistance (CASS, SST, and Filiform) and adhesion.

[0226] Example 2

[0227] Colored transparent corrosion-resistant primer composition 2

[0228] Example 1 was repeated, except that the type and amount of polyester resin and the amount of S-100# solvent oil were adjusted. The raw material weight parts of Example 2 are shown in Table 14. The polyester resin is SKYBON ES 450, with a molecular weight of 18000, a hydroxyl value of 6.0 mgKOH / g, and a glass transition temperature of 52℃.

[0229] Table 14. Raw material weight parts for Example 2

[0230]

[0231] The preparation of the above-mentioned water-based corrosion-resistant transparent primer composition 2 includes the following steps:

[0232] (1) First, add 27.20 parts of propylene glycol methyl ether acetate, 4.20 parts of isoflurane and 8.20 parts of methyl isobutyl ketone to the container and stir at 400-500 r / min. Then add 14.30 parts of polyester resin. After the resin is completely dissolved, a polyester resin mixture is obtained.

[0233] (2) Continue to add the following components in sequence while stirring: 1.50 parts of epoxy resin, 1.50 parts of blocked isocyanate and 6.15 parts of amino resin. Stir for 20-30 minutes to obtain a resin mixture.

[0234] (3) Add 0.15 parts of leveling agent BYK 310, 1.50 parts of silane coupling agent OFS-6040, and 2.00 parts of corrosion inhibitor HALOX 650. Stir for 20-30 minutes, add 1.50 parts of black resin-free pigment, and finally add 11.60 parts of the remaining solvent ethyl acetate and 20.20 parts of S-100# solvent oil to rinse the container wall and the stirring paddle. Stir for 20-30 minutes and adjust the color to the standard requirements to obtain the colored transparent corrosion-resistant primer composition 2.

[0235] Example 3

[0236] Colored Corrosion-Resistant Transparent Primer Composition 3

[0237] Example 1 was repeated, except that the type and amount of epoxy resin and the amount of S-100# solvent oil were adjusted. The raw material weight parts of Example 3 are shown in Table 15. The epoxy resin was EP-0150VARNISH (purchased from Nippon Steel Chemical Co., Ltd.), and its non-volatile content was 50.0%.

[0238] Table 15. Raw material weight parts for Example 3

[0239]

[0240]

[0241] The preparation of the above-mentioned water-based corrosion-resistant transparent primer composition 3 includes the following steps:

[0242] (1) First, add 27.20 parts of propylene glycol methyl ether acetate, 4.20 parts of isoflurane and 8.20 parts of methyl isobutyl ketone to the container and stir at 400-500 r / min. Then add 13.50 parts of polyester resin. After the resin is completely dissolved, a polyester resin mixture is obtained.

[0243] (2) Continue to add the following components in sequence while stirring: 1.65 parts epoxy resin, 1.50 parts blocked isocyanate and 6.15 parts amino resin. Stir for 20-30 minutes to obtain a resin mixture.

[0244] (3) Add 0.15 parts of leveling agent BYK 310, 1.50 parts of silane coupling agent OFS-6040, and 2.00 parts of corrosion inhibitor HALOX 650. Stir for 20-30 minutes. Add 1.50 parts of black resin-free pigment. Finally, add 11.60 parts of the remaining solvent ethyl acetate and 20.85 parts of S-100# solvent oil to rinse the container wall and the stirring paddle. Stir for 20-30 minutes and adjust the color to the standard requirements to obtain the colored transparent corrosion-resistant primer composition 3.

[0245] Example 4

[0246] Colored transparent corrosion-resistant primer composition 4

[0247] Prepare colored transparent corrosion-resistant primer composition 4 according to the formulation shown in Table 16 below.

[0248] Table 16. Raw material weight parts for Example 4

[0249]

[0250] The preparation of the colored transparent primer composition 4 includes the following steps:

[0251] (1) First, add 27.20 parts of propylene glycol methyl ether acetate, 4.20 parts of isoflurane and 8.20 parts of methyl isobutyl ketone to the container and stir at 400-500 r / min. Then add 14.30 parts of polyester resin. After the resin is completely dissolved, a polyester resin mixture is obtained.

[0252] (2) Continue to add the following components in sequence while stirring: 1.50 parts epoxy resin, 1.50 parts blocked isocyanate and 6.30 parts amino resin. Stir for 20-30 minutes to obtain a resin mixture.

[0253] (3) Add 0.15 parts of leveling agent BYK 310, 1.50 parts of silane coupling agent OFS-6040, and 2.00 parts of corrosion inhibitor HALOX 650. Stir for 20-30 minutes, add 1.50 parts of black resin-free pigment, and finally add 11.60 parts of the remaining solvent ethyl acetate and 20.05 parts of S-100# solvent oil to rinse the container wall and the stirring paddle. Stir for 20-30 minutes and adjust the color to the standard requirements to obtain the colored transparent corrosion-resistant primer composition 4.

[0254] Example 5

[0255] Colored transparent corrosion-resistant primer composition 5

[0256] Prepare colored transparent corrosion-resistant primer composition 5 according to the formulation shown in Table 17 below.

[0257] Table 17. Raw material weight parts for Example 5

[0258]

[0259] The preparation of the colored transparent primer composition 5 includes the following steps:

[0260] (1) First, add 27.20 parts of propylene glycol methyl ether acetate, 4.20 parts of isoflurane and 8.20 parts of methyl isobutyl ketone to the container and stir at 400-500 r / min. Then add 12.70 parts of polyester resin. After the resin is completely dissolved, a polyester resin mixture is obtained.

[0261] (2) Continue to add the following components in sequence while stirring: 1.50 parts epoxy resin, 1.50 parts blocked isocyanate and 5.70 parts amino resin. Stir for 20-30 minutes to obtain a resin mixture.

[0262] (3) Add 0.15 parts of leveling agent BYK 310, 1.50 parts of silane coupling agent OFS-6040, and 2.00 parts of corrosion inhibitor HALOX 650. Stir for 20-30 minutes, add 1.50 parts of black resin-free pigment, and finally add 11.60 parts of the remaining solvent ethyl acetate and 22.25 parts of S-100# solvent oil to rinse the container wall and the stirring paddle. Stir for 20-30 minutes and adjust the color to the standard requirements to obtain the colored transparent corrosion-resistant primer composition 5.

[0263] Example 6

[0264] Colored transparent corrosion-resistant primer composition 6

[0265] The preparation process of Example 1 was repeated, except that the blocked isocyanate was replaced with DESMODUR BL 3575SN.

[0266] Example 7

[0267] Colored transparent corrosion-resistant paint composition 7

[0268] The preparation process of Example 1 was repeated, except that the amino resin was replaced with Resimene 735.

[0269] Example 8

[0270] Colored transparent corrosion-resistant primer composition 8

[0271] The preparation process of Example 1 was repeated, except that the corrosion inhibitor was replaced with CANFAIR PPOA.

[0272] Example 9

[0273] Colored transparent corrosion-resistant primer composition 9

[0274] The preparation process of Example 1 was repeated, except that the silane coupling agent was replaced with KBM 403.

[0275] Example 10

[0276] Colored transparent corrosion-resistant primer composition 10

[0277] The preparation process of Example 1 was repeated, except that the types of polyester resin, blocked isocyanate, epoxy resin, amino resin, corrosion inhibitor, and silane coupling agent and the amount of some components were adjusted. The raw material weight parts of Example 10 are shown in Table 17.

[0278] Table 17. Raw material weight parts for Example 10

[0279]

[0280] Example 11

[0281] Colored transparent corrosion-resistant primer composition 11

[0282] The preparation process of Example 1 was repeated, except that the composition and amount of the pigment paste were adjusted. The weight parts of the raw materials in Example 11 are shown in Table 18.

[0283] Table 18. Raw material weight parts for Example 11

[0284]

[0285]

[0286] Referring to the method described in Example 1 above, the main coating properties of the colored transparent corrosion-resistant primer compositions prepared in Examples 2-11 were tested, and the test results are shown in Tables 18 and 19. The test results are similar to those of Example 1, indicating that the components and proportions of the colored transparent corrosion-resistant primer specified in this invention can achieve good performance, and the types of polyester resin, blocked isocyanate, epoxy resin, and amino resin used in this invention have excellent effects.

[0287] Table 18. Main film properties of colored transparent corrosion-resistant primers in Examples 2-11 (used with liquid varnish)

[0288]

[0289]

[0290] Table 19. Main film properties of colored transparent corrosion-resistant primers in Examples 2-11 (with transparent powder)

[0291]

[0292]

[0293]

[0294] Comparative Example 11

[0295] Colored transparent corrosion-resistant primer composition C11

[0296] The preparation process of Example 1 was repeated, except that in step (1) of the preparation process of the colored transparent corrosion resistant primer composition C11, an aromatic solvent was first added to dissolve the polyester resin. As a result, it was found that the polyester resin could not be fully dispersed and appeared as white flocculent, and the sampling failed.

[0297] Comparative Example 12

[0298] Colored transparent corrosion-resistant primer composition C12

[0299] The preparation process of Example 1 was repeated, except that in step (1) of the preparation process of the colored transparent corrosion-resistant primer composition C12, other resins besides polyester resin were added first, and polyester resin was added in step (2). As a result, the colored transparent primer composition contained fine particles and could not be sprayed.

[0300] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A color transparent corrosion resistant primer composition characterized in that, The base paint composition comprises the following raw material components in 100 parts by total weight: The auxiliary comprises Silane coupling agent 1.1-1.7 parts; Corrosion inhibitor 1.0-2.3 parts; Leveling agent 0.1-0.2 parts; The polyester resin has the following characteristics: (1) Molecular weight is 15000-18000; (2) Hydroxyl value is 5-7 mgKOH / g; (3) Glass transition temperature is 52-67℃; (4) The structure of polyester resin molecule is linear structure.

2. The primer composition according to claim 1, characterized in that, The non-volatile content of the polyester resin is 100.0%, and the hydroxyl value is 6.0 mgKOH / g, selected from SKYBON ES 450 of Yekon Environmental Protection Materials (Yantai) Co., Ltd. and / or DYNAPOL L 205 of Wanhua Special Chemicals (Shanghai) Co., Ltd.

3. The primer composition according to claim 1, characterized in that, The epoxy resin is a bisphenol A type epoxy resin, and the non-volatile content is 50.0-55.0%; The non-volatile content of the blocked isocyanate is 74.0-76.0%, and the blocked NCO content is 10.5-11.1%; The amino resin is a partially methyl etherified amino resin, and the non-volatile content is 78.0-82.0%; Preferably, the epoxy resin is selected from MAS 9003 of Shenzhen Lihua Xin Trading Co., Ltd. and / or EP-0150 VARNISH of Nippon Steel Chemical Co., Ltd. Preferably, the blocked isocyanate is selected from DESMODUR BL 3175SN and / or DESMODUR BL 3575SN of Bayer MaterialScience Co., Ltd. Preferably, the amino resin is selected from M 40ST of Changchun Artificial Resin Factory Co., Ltd. and / or Resimene 735 of Prefere Melamines LLC.

4. The primer composition according to claim 1, characterized in that, The non-volatile content of the base paint composition is 20.0-32.7%, and the viscosity is 17.0-27.0 seconds / 20℃*4 cups.

5. The primer composition according to claim 1, characterized in that, The effective ingredient content of the silane coupling agent is >99.0%; The corrosion inhibitor is selected from organic corrosion inhibitors; The leveling agent is selected from polyester modified silicone; The solvent is selected from one or more of ester solvents, ketone solvents and aromatic hydrocarbon solvents.

6. The primer composition according to claim 5, characterized in that, The ester solvent is selected from at least one of ethyl acetate, butyl acetate and propylene glycol methyl ether acetate; The ketone solvent is selected from at least one of cyclohexanone, methyl isobutyl ketone and isofurole ketone; The aromatic hydrocarbon solvent is selected from one of S-150# solvent oil and S-100# solvent oil.

7. A process for the preparation of a primer composition according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: (1) A part of the solvent is put into a container, and the polyester resin is put in under stirring, so that the polyester resin is completely dissolved to obtain a polyester resin mixture; (2) The epoxy resin, the blocked isocyanate and the amino resin are sequentially put into the container under stirring, and after stirring for 20-30 min, a resin mixture is obtained; (3) The various auxiliaries, color paste and the remaining solvent are continuously put into the container, stirred for 20-30 min, and the color is adjusted to the standard requirement to obtain the base paint composition.

8. A color transparent corrosion resistant primer, characterized by, The colored transparent corrosion-resistant primer is prepared from the raw materials of the colored transparent corrosion-resistant primer composition according to any one of claims 1-6.

9. A color transparent corrosion resistant primer coating characterized by, Prepared from the colored transparent corrosion-resistant primer according to claim 8.

10. Use of the primer composition according to any one of claims 1-6 in the coating of automotive aluminum alloy finish-machined wheel hubs.

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