Low-temperature curing powder coating composition with metal effect and coating of low-temperature curing powder coating composition

Abstract

The invention discloses a low-temperature curing powder coating composition with a metal effect and a coating of the low-temperature curing powder coating composition, the low-temperature curing powder coating composition comprises a powder coating base powder composition and effect pigments, and at least one effect pigment is attached to the powder coating base powder composition; wherein the powder coating base powder composition comprises polyester resin, epoxy resin and an imidazole catalyst; the viscosity of the epoxy resin at the temperature of 150 DEG C is 14 to 23 Pa.s; the high-leveling low-temperature curing coating with a metal effect is obtained by molding after a curing reaction is carried out under the condition that the temperature is not higher than 150 DEG C and the time is not longer than 25 minutes.

Description

Technical Field

[0001] The invention belongs to the field of powder coatings, and in particular relates to a low-temperature curing powder coating composition with a metallic effect. The invention also relates to a low-temperature curing coating prepared by using the low-temperature curing powder coating composition with a metallic effect. Background Art

[0002] Thermosetting powder coatings are widely used to replace paints and water-based paints to achieve protective decoration of products in various fields because of their advantages of being green, low energy consumption, easy to apply, and no (or at least very little) VOC emissions. Specifically, in some application areas, a high-leveling metallic appearance effect is desired. In order to achieve this appearance effect, the curing conditions of existing powder coating products usually need to be above 180°C. Under low-temperature curing conditions (not higher than 150°C and not more than 25 minutes), a high-leveling metallic appearance effect cannot be achieved.

[0003] Therefore, the applicant hopes to conduct research and development to solve the above technical problems. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a low-temperature curing powder coating composition with a metallic effect and a coating thereof, which is formed after a curing reaction at a temperature not higher than 150°C and not longer than 25 minutes to obtain a high-leveling low-temperature curing coating with a metallic effect.

[0005] The technical solution adopted by the present invention is as follows: A low-temperature curing powder coating composition with metallic effect, comprising a powder coating base composition and an effect pigment, wherein at least one effect pigment is attached to the powder coating base composition; wherein the powder coating base composition comprises a polyester resin, an epoxy resin and an imidazole catalyst; and the viscosity of the epoxy resin at 150° C. is 14-23 Pa.s.

[0006] Preferably, the polyester resin satisfies one or more of the following characteristics: i) an acid value of not less than 65 mgKOH / g, more preferably 70-95 mgKOH / g; ii) a viscosity at 200°C of not more than 2500 mPa.s, more preferably not more than 2200 mPa.s; iii) The glass transition temperature range is 45-60°C; iv) Softening point temperature range is 90-110℃.

[0007] Preferably, the softening point temperature of the epoxy resin is no more than 95°C.

[0008] Preferably, the epoxy equivalent of the epoxy resin is in the range of 550-800 g / eq.

[0009] Preferably, the weight ratio of the imidazole catalyst to the powder coating primer composition is 0.05-2wt%.

[0010] Preferably, the imidazole catalyst is a 2-phenyl-2-imidazoline compound.

[0011] Preferably, the weight ratio of the polyester resin to the powder coating primer composition is 30-45 wt %, and / or the weight ratio of the polyester resin to the epoxy resin is in the range of 0.5-2:1.

[0012] Preferably, the weight proportion of the effect pigment to the powder coating base composition is 1-10 wt %, preferably 2-6 wt %.

[0013] Preferably, a low-temperature curing coating with a metallic effect is obtained by spraying the low-temperature curing powder coating composition with a metallic effect as described above on a substrate, and then performing a curing reaction at a temperature not higher than 150°C and not longer than 25 minutes to obtain the low-temperature curing coating with a metallic effect.

[0014] Preferably, the low-temperature curing coating has a PCI leveling grade of not less than grade 8 and has a metallic appearance effect.

[0015] It should be noted that the viscosity value detection standard involved in this application is based on ASTM D 4287-1994, and the detection equipment used can be a standard commercial cone and plate viscometer (for example, ICI cone and plate viscometer (CONE&PLATE), brand CAP 2000 VISCOMETER from Brookfield); the acid value detection standard is based on ISO3682-1998; the glass transition temperature detection standard is based on ISO 11357-2-2013; the softening point temperature detection standard is based on GB / T 12007.6-1989; the epoxy equivalent data detection standard is based on ASTM D1652-11 (2019); the D50 particle size data involved is obtained by particle size distribution test using laser diffraction (for example, Malvern Particle Size Analyzer 2000), and the test standard is ISO 13320-2009.

[0016] The present application proposes a specific powder coating primer composition composed of a polyester resin, an epoxy resin having a viscosity of 14-23 Pa.s at 150°C, and an imidazole catalyst. The specific powder coating primer composition is then mixed with an effect pigment so that at least one effect pigment adheres to the specific powder coating primer composition, thereby obtaining a low-temperature curing powder coating composition with a metallic effect. After a curing reaction is carried out at a temperature not higher than 150°C and not longer than 25 minutes, the composition is molded to obtain a high-leveling low-temperature curing coating with a metallic effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a real photo of the low-temperature curing coating with metallic effect corresponding to Example 1. DETAILED DESCRIPTION

[0018] The embodiment of the present application provides a low-temperature curing powder coating composition with a metallic effect, comprising a powder coating base composition and an effect pigment, wherein at least one effect pigment is attached to the powder coating base composition; wherein the powder coating base composition comprises a polyester resin, an epoxy resin and an imidazole catalyst; Preferably, in order to facilitate the leveling effect under low temperature curing conditions, in this embodiment, the viscosity of the epoxy resin at 150°C is 14-23 Pa.s; preferably, the softening point temperature of the epoxy resin does not exceed 95°C, and is more preferably 82-94°C; preferably, in this embodiment, the epoxy equivalent of the epoxy resin is in the range of 550-800 g / eq, and is more preferably 580-750 g / eq; specifically preferably, in this embodiment, the epoxy resin can be selected from BE-502 Solid Epoxy resin provided by CHANG CHUN PLASTICS CO., LTD., which has a viscosity of 14-23 Pa.s at 150°C, a softening point temperature of 82-92°C, and an epoxy equivalent range of 600-650 g / eq; Preferably, in order to facilitate the leveling effect under low temperature curing conditions, in this embodiment, the polyester resin satisfies one or more of the following characteristics, and more preferably satisfies all of the following characteristics: i) an acid value of not less than 65 mgKOH / g, more preferably 70-95 mgKOH / g; ii) a viscosity at 200°C of not higher than 2500 mPa.s, more preferably not higher than 2200 mPa.s, and even more preferably 500-2000 mPa.s; iii) The glass transition temperature range is 45-60°C; iv) Softening point temperature range is 90-110℃.

[0019] Specifically preferably, in this embodiment, the polyester resin can be selected from Polyester Resin TM5013 provided by Zhejiang Chuanhua Tiansong New Materials Co., Ltd., which has an acid value of 75-85 mgKOH / g, a viscosity of 500-2000 mPa.s at 200°C, a glass transition temperature of 48-54°C, and a softening point temperature of 90-110°C.

[0020] Preferably, in this embodiment, the weight ratio of the imidazole catalyst to the powder coating primer composition is 0.05-2wt%, more preferably 0.08-1.5wt%, and further more preferably 0.1-1wt%; preferably, in this embodiment, the imidazole catalyst includes (preferably uses) a 2-phenyl-2-imidazoline compound; specifically preferably, in this embodiment, the imidazole catalyst can use Hardener MH31 provided by F&F Chem.

[0021] Preferably, in this embodiment, the weight ratio of the polyester resin to the powder coating primer composition is 30-45wt%, more preferably 35-42wt%; and / or preferably, in this embodiment, the weight ratio of the polyester resin to the epoxy resin is in the range of 0.5-2:1, more preferably 0.8-1.5:1, and further preferably 1-1.2:1; Preferably, in this embodiment, the weight proportion of the effect pigment to the powder coating primer composition is 1-10 wt %, preferably 2-6 wt %, further preferably 2-4 wt %.

[0022] Preferably, in this embodiment, the effect pigment includes aluminum powder; of course, any other known effect pigment can be used in other embodiments according to the actual metal effect requirements, and this application is not particularly limited in implementation; preferably, in this embodiment, the D50 particle size of the effect pigment is 10-20 microns.

[0023] All kinds of raw materials involved in this application can be directly purchased on the market, and the sources of raw materials are easy to obtain.

[0024] In the specific implementation of the present application, known leveling agents, degassing agents, antioxidants, dispersants, fillers, pigments, stabilizers, curing accelerators, functional additives and / or other additives may also be added to the powder coating base powder composition. These are conventional technical choices of those skilled in the art; specifically, fillers and / or pigments may be, for example, carbon black, aluminum hydroxide, barium sulfate, TiO2, etc.

[0025] When preparing the powder coating base powder composition of the present application, any known preparation process can be used for preparation; preferably, in this embodiment, the powder coating base powder composition is obtained by mixing, melt extrusion, and crushing. Of course, other known preparation processes can also be used to obtain the powder coating base powder composition of this embodiment, and the present application has no particular limitation on its preparation process.

[0026] Preferably, in this embodiment, the effect pigment is bonded to the coating base powder composition by a thermal bonding process; as an optional preparation method (but not recommended by the applicant), the powder coating base powder composition and the effect pigment are dry-mixed to obtain a low-temperature curing powder coating with a metallic effect (but its metallic effect and application stability will be deteriorated).

[0027] Preferably, in this embodiment, the thermal bonding process can adopt any known thermal bonding (bonding) process, and this embodiment does not specifically limit it; preferably, in the thermal bonding process, the thermal bonding temperature is recommended to be set at 46-60°C, more preferably 48-55°C, and the thermal bonding time is recommended to be selected at 2-5 minutes.

[0028] Preferably, this embodiment proposes a low-temperature curing coating with a metallic effect, and the low-temperature curing powder coating composition with a metallic effect as described above is sprayed on a substrate, and the low-temperature curing coating with a metallic effect is obtained by forming after a curing reaction at a temperature not higher than 150°C and not longer than 25 minutes; further preferably, in this embodiment, the PCI leveling grade of the low-temperature curing coating is not lower than grade 8, and it has a metallic appearance effect.

[0029] In order to verify the technical effect of the present application, the present application specifically conducted the following multiple groups of examples as raw materials for powder coating composition formulations for specific test performance comparison: Example 1: A powder coating composition with a metallic effect, comprising 96 wt% of a powder coating base composition and 4 wt% of aluminum powder (brand name: POWDAL from SCHLENK) ® 8500 HC, whose D50 particle size is about 15 microns); the effect pigment is compounded with the powder coating primer composition through a thermal bonding process, wherein in the thermal bonding process, the thermal bonding temperature is 53°C and the thermal bonding time is 2 minutes; In this embodiment 1, the powder coating primer composition is prepared according to the formula raw materials shown in Table 1 below:

[0030] Embodiment 2: The remaining technical scheme of this embodiment 2 is the same as that of embodiment 1, except that, in this embodiment 2, the powder coating primer composition is prepared according to the formula raw materials shown in Table 2 below:

[0031] Embodiment 3: The remaining technical scheme of this embodiment 3 is the same as that of embodiment 1, except that, in this embodiment 3, the powder coating primer composition is prepared according to the formula raw materials shown in Table 3 below:

[0032] Embodiment 4: The remaining technical scheme of this embodiment 4 is the same as that of embodiment 1, except that, in this embodiment 4, the powder coating primer composition is prepared according to the formula raw materials shown in Table 4 below:

[0033] Embodiment 5: The remaining technical solutions of Embodiment 5 are the same as those of Embodiment 1, except that, in Embodiment 5, the powder coating primer composition is prepared according to the formula raw materials shown in Table 5 below:

[0034] Example 6: The rest of the technical scheme of Example 6 is the same as that of Example 1, except that, in Example 6, the polyester resin brand in Example 1 is replaced by GH-3331 provided by Zhejiang Guanghua, which has a viscosity range of 2500-3500 mPa.s at 200°C and an acid value range of 32-37 mgKOH / g.

[0035] Example 7: The remaining technical solutions of Example 7 are the same as those of Example 1, except that in Example 7, the polyester resin grade in Example 1 is replaced by CRYLCOAT ® 4642-3 polyester resin, its viscosity at 200°C ranges from 1500-2300 mPa.s, and its acid value ranges from 32-38 mgKOH / g.

[0036] Example 8: The rest of the technical solutions of Example 8 are the same as those of Example 1, except that, in Example 8, the polyester resin brand in Example 1 is replaced by GH-3337 polyester resin provided by Zhejiang Guanghua, which has a viscosity range of 4300-5500 mPa.s at 200°C and an acid value range of 50-56 mg KOH / g.

[0037] Example 9: The rest of the technical solutions of Example 9 are the same as those of Example 1, except that, in Example 9, the polyester resin brand in Example 9 is replaced by Excalibur's SJ3B, which has a viscosity range of 3500-5000 mPa.s at 200°C and an acid value range of 68-75 mgKOH / g.

[0038] Example 10: The rest of the technical solutions of Example 10 are the same as those of Example 1, except that Example 10 provides a powder coating composition with a metallic effect, comprising 98 wt % of a powder coating base composition and 2 wt % of aluminum powder.

[0039] Example 11: The rest of the technical solutions of Example 11 are the same as those of Example 1, except that Example 11 provides a powder coating composition with a metallic effect, comprising 99 wt % of a powder coating base composition and 1 wt % of aluminum powder.

[0040] Example 12: The rest of the technical solutions of Example 12 are the same as those of Example 1, except that Example 12 provides a powder coating composition with a metallic effect, comprising 94 wt % of a powder coating base composition and 6 wt % of aluminum powder.

[0041] Comparative Example 1: The remaining technical solutions of Comparative Example 1 are the same as those of Example 1, except that, in this Comparative Example 1, The imidazole catalyst in Example 1 is replaced by a corresponding weight portion of titanium dioxide.

[0042] Comparative Example 2: The rest of the technical scheme of Comparative Example 2 is the same as that of Example 1, except that, in this Comparative Example 2, the powder coating primer composition is prepared according to the formula raw materials shown in Table 6 below:

[0043] Comparative Example 3: The rest of the technical scheme of Comparative Example 3 is the same as that of Example 1, except that, in this Comparative Example 3, the powder coating primer composition is prepared according to the formula raw materials shown in Table 7 below:

[0044] Comparative Example 4: The rest of the technical scheme of Comparative Example 4 is the same as that of Example 1, except that, in this Comparative Example 4, the powder coating primer composition is prepared according to the formula raw materials shown in Table 8 below:

[0045] The present application obtains the corresponding powder coating compositions according to the implementation schemes proposed in the above Examples 1-12 and Comparative Examples 1-4.

[0046] The powder coating compositions prepared in Examples 1-12 and Comparative Examples 1-4 were respectively used, and the same aluminum plate was selected as the substrate. Each powder coating composition was cured by baking heating, wherein the heating temperature was 150° C. and the heating time was 15 minutes, and coatings were obtained respectively. The film thickness of the cured coatings was 60-120 μm. The performance test comparison results are shown in Table 9 below: For the coating photos obtained in Example 1, please refer to Figure 1 As shown; it should be noted that this embodiment 1 also uses aluminum pipes (the surface of the pipes is smooth and flat) as the substrate, and the same home baking heating method is used to cure it. The obtained coating photos can also be found in Figure 1 As shown;

[0047] After comparative testing, it was found that the coatings prepared by the powder coating compositions provided in Examples 1-4 & 10-12 under low-temperature curing conditions have both significantly outstanding high leveling and metallic effects, and good application stability.

[0048] It should be noted that the coating performance test involved in this embodiment is carried out according to the test standard described in Table 10 below.

[0049]

[0050] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0051] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A low temperature curing powder coating composition having a metallic effect, characterized in that: The invention comprises a powder coating base powder composition and an effect pigment, wherein at least one effect pigment is attached to the powder coating base powder composition; wherein the powder coating base powder composition comprises a polyester resin, an epoxy resin and an imidazole catalyst; and the viscosity of the epoxy resin at 150° C. is 14-23 Pa.s.

2. The low temperature curing powder coating composition with metallic effect according to claim 1, characterized in that: The polyester resin meets one or more of the following characteristics: i) an acid value of not less than 65 mgKOH / g, more preferably 70-95 mgKOH / g; ii) a viscosity at 200°C of not more than 2500 mPa.s, more preferably not more than 2200 mPa.s; iii) The glass transition temperature range is 45-60°C; iv) Softening point temperature range is 90-110℃.

3. The low temperature curing powder coating composition with metallic effect according to claim 1, characterized in that: The softening point temperature of the epoxy resin does not exceed 95°C.

4. The low temperature curing powder coating composition with metallic effect according to claim 1, characterized in that: The epoxy equivalent of the epoxy resin is in the range of 550-800 g / eq.

5. The low temperature curing powder coating composition with metallic effect according to claim 1, characterized in that: The weight proportion of the imidazole catalyst to the powder coating primer composition is 0.05-2 wt %.

6. The low temperature curing powder coating composition with metallic effect according to claim 1 or 5, characterized in that: The imidazole catalyst is a 2-phenyl-2-imidazoline compound.

7. The low temperature curing powder coating composition with metallic effect according to claim 1, characterized in that: The weight ratio of the polyester resin to the powder coating primer composition is 30-45 wt %, and / or the weight ratio of the polyester resin to the epoxy resin is in the range of 0.5-2:

1.

8. The low temperature curing powder coating composition with metallic effect according to claim 1, characterized in that: The weight proportion of the effect pigment to the powder coating base composition is 1-10 wt %, preferably 2-6 wt %.

9. A low temperature curing coating with metallic effect, characterized in that: The low-temperature curing powder coating composition with a metallic effect as claimed in any one of claims 1 to 8 is sprayed on a substrate, and the low-temperature curing coating with a metallic effect is obtained by molding after curing reaction at a temperature not higher than 150° C. and not longer than 25 minutes.

10. The low temperature curing coating with metallic effect according to claim 9, characterized in that: The low-temperature curing coating has a PCI leveling grade of not less than grade 8 and has a metallic appearance effect.

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