Fluoride-free powder coating composition and cured coating thereof

Abstract

The invention discloses a fluoride-free powder coating composition and a cured coating thereof, the fluoride-free powder coating composition comprises thermosetting resin, a curing agent and fluoride-free matting wax, the fluoride-free matting wax adopts polyethylene wax, the dripping temperature of the polyethylene wax is 127-132DEG C, and the test standard of the dripping temperature is ASTM D3954-15 (2022); the total fluorine content of the fluorine-free powder coating composition obtained by testing according to an EN14582-2016 method is less than or equal to 100mg / kg; implementation verifies that the fluorine-free powder coating composition can be used as a fluorine-free alternative scheme of an existing powder coating composition which adopts fluorine-containing wax powder for extinction.

Description

Technical Field

[0001] The invention belongs to the field of powder coatings, and in particular relates to a fluorine-free powder coating composition. The invention also relates to a cured coating prepared by using the fluorine-free powder coating composition. Background Art

[0002] PFAS (perfluoroalkyl / polyfluoroalkyl and their derivatives), including PFOA, PFOS, PFHxS and other substances, are man-made chemicals. Due to their difficult decomposition, bioaccumulation, wide application and multiple toxicity, they have become one of the focuses of concentrated restrictions in major regulations. More and more industries have required the provision of fluorine-free products with a total fluorine content (TF) ≤ 100ppm.

[0003] Furthermore, most existing powder coatings are matted by polytetrafluoroethylene-modified polyethylene wax powder, and the addition amount is generally 0.5-4wt%. The total fluorine (TF) content tested based on the EN:14582-2016 method is much greater than 100ppm, which cannot meet market requirements.

[0004] To this end, the applicant hopes to develop a fluorine-free powder coating composition with a total fluorine content (TF) ≤ 100 ppm, while ensuring that the basic properties of the coating are not affected. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a fluorine-free powder coating composition and a cured coating thereof. On the basis of achieving the expected matting performance, a fluorine-free powder coating composition with a total fluorine content of ≤100 mg / kg is obtained. It has been verified through implementation that the present application can be used as a fluorine-free alternative to existing powder coating compositions that use fluorine-containing wax powder for matting.

[0006] The technical solution adopted by the present invention is as follows: A fluorine-free powder coating composition comprises a thermosetting resin, a curing agent and a fluorine-free matting wax, wherein the fluorine-free matting wax is polyethylene wax, the dripping temperature of the polyethylene wax is 127°C-132°C, and the test standard for the dripping temperature is ASTM D3954-15(2022); the total fluorine content of the fluorine-free powder coating composition tested according to the EN14582-2016 method is ≤100 mg / kg.

[0007] Preferably, the D50 particle size of the polyethylene wax is 7.5 μm - 9.5 μm.

[0008] Preferably, the polyethylene wax has a density of 0.96-0.98 g / cm³ at 23°C.

[0009] Preferably, the acid value of the polyethylene wax is 0-1 mg KOH / g, more preferably 0 mg KOH / g.

[0010] Preferably, the sum of the weight of the thermosetting resin and the curing agent accounts for 40-80wt% of the weight of the fluorine-free powder coating composition, more preferably 45-75wt%; and / or the weight of the thermosetting resin accounts for 35-75wt% of the weight of the fluorine-free powder coating composition, more preferably 40-70wt%.

[0011] Preferably, the weight ratio of the fluorine-free matting wax to the fluorine-free powder coating composition is 0.1-5wt%, more preferably 0.2-4.5wt%, and further preferably 0.5-4wt%.

[0012] Preferably, the thermosetting resin comprises a carboxyl polyester resin, and the acid value of the carboxyl polyester resin is preferably 20-60 mgKOH / g; the curing agent comprises triglycidyl isocyanurate (TGIC) and / or hydroxyalkylamide (HAA).

[0013] A fluorine-free powder coating composition comprises a first fluorine-free powder coating composition and a second fluorine-free powder coating composition mixed together; wherein the first fluorine-free powder coating composition and the second fluorine-free powder coating composition are both made of the fluorine-free powder coating composition described above.

[0014] Preferably, the first fluorine-free powder coating composition comprises a first carboxyl polyester resin, and the second fluorine-free powder coating composition comprises a second carboxyl polyester resin, wherein the acid values ​​of the first carboxyl polyester resin and the second carboxyl polyester resin are not equal; preferably, the difference in acid value between the first carboxyl polyester resin and the second carboxyl polyester resin is 10-50, more preferably 15-40; preferably, the acid value of the first carboxyl polyester resin is 45-65 mgKOH / g, and the acid value of the second carboxyl polyester resin is 15-35 mgKOH / g.

[0015] A cured coating is obtained by spraying the fluorine-free powder coating composition described above on a substrate and curing the substrate by heating, wherein the gloss of the cured coating at a test angle of 60° according to ISO 2813-2014 is less than 80 GU.

[0016] It should be noted that the dripping temperature detection standard involved in this application is based on ASTM D3954-15 (2022); the total fluorine content detection standard involved is based on EN14582-2016; the acid value detection standard involved is based on ISO 3682-1998; The density test standard involved is based on ISO 1183-1:2019; the viscosity value test standard involved is based on ASTM D 4287-1994, and the testing 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 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.

[0017] The present application proposes to use polyethylene wax with a dripping temperature of 127°C - 132°C as a fluorine-free matting wax in a powder coating composition. On the basis of achieving the expected matting performance, a fluorine-free powder coating composition with a total fluorine content of ≤100 mg / kg is obtained. After implementation verification, the present application can be used as a fluorine-free alternative to existing powder coating compositions that use fluorine-containing wax powder for matting. DETAILED DESCRIPTION

[0018] An embodiment of the present application proposes a fluorine-free powder coating composition, comprising a thermosetting resin, a curing agent and a fluorine-free matting wax, wherein the fluorine-free matting wax is polyethylene wax, the dripping temperature of the polyethylene wax is 127°C-132°C, and the test standard for the dripping temperature is ASTM D3954-15 (2022); the fluorine-free powder coating composition is tested according to the EN14582-2016 method, and the total fluorine content obtained is ≤100 mg / kg, and more preferably the total fluorine content is ≤50 mg / kg.

[0019] Preferably, in this embodiment, the sum of the weight parts of the thermosetting resin and the curing agent accounts for 40-80wt% of the weight of the fluorine-free powder coating composition, and more preferably 45-75wt%; and / or preferably, in this embodiment, the weight part ratio of the thermosetting resin to the fluorine-free powder coating composition is 35-75wt%, more preferably 40-70wt%, and further more preferably 50-65wt%.

[0020] Preferably, in this embodiment, the thermosetting resin includes a carboxyl polyester resin, and the acid value of the carboxyl polyester resin is preferably 20-60 mgKOH / g; the curing agent includes triglycidyl isocyanurate (TGIC) and / or hydroxyalkylamide (HAA).

[0021] Preferably, in this embodiment, the D50 particle size of the polyethylene wax is 7.5 μm - 9.5 μm; preferably, in this embodiment, the density of the polyethylene wax at 23°C is 0.96-0.98 g / cm³; preferably, in this embodiment, the acid value of the polyethylene wax is 0-1 mg KOH / g, more preferably 0 mg KOH / g. Specifically preferably, in this embodiment, the polyethylene wax is Ceridust from CLARIANT ® 3620, with a D50 particle size of 7.5μm - 9.5μm, a density of 0.96-0.98g / cm³ at 23°C, and an acid value of 0mg KOH / g; in other embodiments, a fluorine-free matting wax with similar effects may also be used, and this embodiment does not make the sole limitation to this.

[0022] Preferably, in this embodiment, the weight ratio of the fluorine-free matting wax to the fluorine-free powder coating composition is 0.1-5wt%, more preferably 0.2-4.5wt%, and further preferably 0.5-4wt%.

[0023] Preferably, in order to further facilitate the achievement of superior matte effect, the present embodiment further provides a fluorine-free powder coating composition, comprising a first fluorine-free powder coating composition and a second fluorine-free powder coating composition that are mixed (preferably mixed by dry mixing); wherein the first fluorine-free powder coating composition and the second fluorine-free powder coating composition are both made of the fluorine-free powder coating composition described above.

[0024] Preferably, in this embodiment, the first fluorine-free powder coating composition includes a first carboxyl polyester resin, and the second fluorine-free powder coating composition includes a second carboxyl polyester resin, wherein the acid values ​​of the first carboxyl polyester resin and the second carboxyl polyester resin are not equal; preferably, in this embodiment, the difference in acid value between the first carboxyl polyester resin and the second carboxyl polyester resin is 10-50, more preferably 15-40.

[0025] Preferably, in the present embodiment, the acid value of the first carboxyl polyester resin is greater than 40 mg KOH / g, more preferably 45-65 mg KOH / g, and further preferably 50-60 mg KOH / g; preferably, in the present embodiment, the first carboxyl polyester resin adopts a saturated carboxyl polyester resin; specifically preferably, in the present embodiment, the first carboxyl polyester resin selects the GH-3337 saturated carboxyl polyester resin provided by Zhejiang Guanghua, and its acid value range is 50-56 mg KOH / g; of course, in other embodiments, a carboxyl polyester resin with a similar acid value range can also be used as the first carboxyl polyester resin in the embodiment of the present application.

[0026] Preferably, in the present embodiment, the acid value of the second carboxyl polyester resin is less than 40 mg KOH / g, more preferably 15-35 mg KOH / g, and further preferably 20-30 mg KOH / g; preferably, in the present embodiment, the viscosity range of the second carboxyl polyester resin at 200°C is 3000-6000 mPa.s; preferably, in the present embodiment, the second carboxyl polyester resin adopts a saturated carboxyl polyester resin; specifically preferably, in the present embodiment, the second carboxyl polyester resin uses the GH-3336 saturated polyester resin provided by Zhejiang Guanghua, which has an acid value range of 23-27 mg KOH / g, a viscosity range of 3800-4800 mPa.s at 200°C, and a glass transition temperature of 57°C; of course, in other embodiments, a polyester resin with a similar acid value range can also be used as the second carboxyl polyester resin in the embodiment of the present application.

[0027] Preferably, in order to further achieve a better matte effect, in this embodiment, the weight ratio of the first fluorine-free powder coating composition to the second fluorine-free powder coating composition is 0.4-3:1, more preferably 0.5-2:1, and even more preferably 0.8-1.5:1.

[0028] Preferably, this embodiment further proposes a cured coating, wherein the fluorine-free powder coating composition described above is sprayed on a substrate, and the cured coating is obtained after heating and curing, wherein the gloss of the cured coating at a test angle of 60° according to ISO 2813-2014 is less than 80 GU.

[0029] 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.

[0030] In the specific implementation of the present application, it is also possible to add known leveling agents, degassing agents, antioxidants, dispersants, fillers, pigments, stabilizers, curing accelerators, functional additives and / or other additives to the fluorine-free powder coating composition (including the first fluorine-free powder coating composition and / or the second fluorine-free powder coating composition), which are conventional technical choices of those skilled in the art; specifically, the addition ratio of fillers and / or pigments can be conventionally selected according to actual needs. The weight ratio can be preferably 0-40wt% of the corresponding first fluorine-free powder coating composition or the second fluorine-free powder coating composition, and more preferably 1-40wt%. The fillers and / or pigments can be selected, for example, from carbon black, aluminum hydroxide, barium sulfate, TiO2, etc.

[0031] When preparing the fluorine-free powder coating composition of the present application (including the first fluorine-free powder coating composition and / or the second fluorine-free powder coating composition), any known preparation process can be used for preparation. A typical preparation process includes: obtaining by mixing, melt extrusion, and crushing.

[0032] It should be noted that, of course, other well-known preparation processes can also be used to obtain the fluorine-free powder coating composition of this embodiment, and the present application does not have any particular limitation on its preparation process.

[0033] In order to verify the technical effect of the present application, the present application specifically carries out the following multiple groups of examples and comparative examples as raw materials for powder coating composition formulation for specific test performance comparison: Example 1: A fluorine-free powder coating composition, comprising 50 wt% of a first fluorine-free powder coating composition and 50 wt% of a second fluorine-free powder coating composition which are dry-mixed into one; wherein the first fluorine-free powder coating composition is prepared according to the formula raw materials shown in Table 1a below, and the second fluorine-free powder coating composition is prepared according to the formula raw materials shown in Table 1b below:

[0034]

[0035] Example 2. The remaining technical solutions of Example 2 are the same as those of Example 1, except that, in Example 2, the formula raw materials are prepared according to the formula tables shown in Tables 2a and 2b below:

[0036]

[0037] 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 formula raw materials of the first fluorine-free powder coating composition are prepared as shown in the following Table 3a:

[0038] 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 formula raw materials of the first fluorine-free powder coating composition are prepared as shown in the following Table 4a:

[0039] Embodiment 5: The rest of the technical scheme of Embodiment 5 is the same as that of Embodiment 1, except that, in Embodiment 5, the second fluorine-free powder coating composition is eliminated, and only the first fluorine-free powder coating composition provided in Embodiment 1 is used.

[0040] Embodiment 6: The rest of the technical scheme of Embodiment 6 is the same as that of Embodiment 1, except that, in Embodiment 6, the first fluorine-free powder coating composition is eliminated, and only the second fluorine-free powder coating composition provided in Embodiment 1 is used.

[0041] Example 7: The rest of the technical solutions of Example 7 are the same as those of Example 1, except that the fluorine-free powder coating composition provided in Example 7 comprises 60 wt % of a first fluorine-free powder coating composition and 40 wt % of a second fluorine-free powder coating composition which are dry-mixed into one.

[0042] Example 8: The rest of the technical scheme of Example 8 is the same as that of Example 1, except that the fluorine-free powder coating composition provided in Example 8 includes 45 wt % of a first fluorine-free powder coating composition and 55 wt % of a second fluorine-free powder coating composition which are dry-mixed into one.

[0043] Example 9: The remaining technical solutions of Example 9 are the same as those of Example 1, except that the weight portion of the fluorine-free matting wax in the first fluorine-free powder coating composition is reduced to 1 part, and the weight portion of TiO2 is increased to 25 parts; the weight portion of the fluorine-free matting wax in the second fluorine-free powder coating composition is reduced to 1 part, and the weight portion of TiO2 is increased to 25 parts.

[0044] Embodiment 10: The remaining technical scheme of this embodiment 10 is the same as that of embodiment 1, except that the weight portion of the fluorine-free matting wax in the first fluorine-free powder coating composition is reduced to 0.5 parts, and the weight portion of TiO2 is increased to 25.5 parts; the weight portion of the fluorine-free matting wax in the second fluorine-free powder coating composition is reduced to 0.5 parts, and the weight portion of TiO2 is increased to 25.5 parts.

[0045] Embodiment 11: The rest of the technical scheme of this embodiment 11 is the same as that of embodiment 1, except that the weight portion of the fluorine-free matting wax in the first fluorine-free powder coating composition is reduced to 0.2 parts, and the weight portion of TiO2 is increased to 25.8 parts; the weight portion of the fluorine-free matting wax in the second fluorine-free powder coating composition is reduced to 0.2 parts, and the weight portion of TiO2 is increased to 25.8 parts.

[0046] Example 12: The remaining technical solutions of Example 12 are the same as those of Example 1, except that the weight portion of the fluorine-free matting wax in the first fluorine-free powder coating composition is reduced to 0.1 parts, and the weight portion of TiO2 is increased to 25.9 parts; the weight portion of the fluorine-free matting wax in the second fluorine-free powder coating composition is reduced to 0.1 parts, and the weight portion of TiO2 is increased to 25.9 parts.

[0047] Example 13: The rest of the technical solutions of Example 13 are the same as those of Example 1, except that the weight portion of the fluorine-free matting wax in the first fluorine-free powder coating composition is reduced to 0 parts, and the weight portion of TiO2 is increased to 26 parts.

[0048] Example 14: The rest of the technical solutions of Example 14 are the same as those of Example 1, except that the weight portion of the fluorine-free matting wax in the second fluorine-free powder coating composition is reduced to 0 parts, and the weight portion of TiO2 is increased to 26 parts.

[0049] Example 15: The rest of the technical solutions of Example 15 are the same as those of Example 1, except that, in Example 15, the first carboxyl polyester resin brand of the first fluorine-free powder coating composition in Example 1 is replaced by Excalibur's SJ3B, which has an acid value range of 68-75 mgKOH / g.

[0050] Example 16: The rest of the technical scheme of Example 16 is the same as that of Example 1, except that, in Example 16, the first carboxyl polyester resin brand of the first fluorine-free powder coating composition in Example 1 is replaced by Zhejiang Guanghua's GH-5514 carboxyl polyester resin, whose acid value ranges from 52-60 mgKOH / g.

[0051] Example 17: The rest of the technical scheme of Example 17 is the same as that of Example 1, except that, in Example 17, the second carboxyl polyester resin of the second fluorine-free powder coating composition in Example 1 is replaced by Zhejiang Guanghua's GH-5514 carboxyl polyester resin, which has an acid value range of 52-60 mgKOH / g.

[0052] Example 18: The remaining technical solutions of Example 18 are the same as those of Example 1, except that in Example 18, the first carboxyl polyester resin brand of the first fluorine-free powder coating composition in Example 1 is replaced by CRYLCOAT from Allnex. ® 4642-3, with an acid value range of 32-38 mgKOH / g.

[0053] Comparative Example 1: The remaining technical solutions of this Comparative Example 1 are the same as those of Example 1, with the only difference being that in this Comparative Example 1, the weight portion of the fluorine-free matting wax in the first fluorine-free powder coating composition is reduced to 0 parts, and the weight portion of TiO2 is increased to 26 parts; the weight portion of the fluorine-free matting wax in the second fluorine-free powder coating composition is reduced to 0 parts, and the weight portion of TiO2 is increased to 26 parts.

[0054] Comparative Example 2: The rest of the technical scheme of Comparative Example 2 is the same as that of Example 1, except that in Comparative Example 2, all parts by weight of the fluorine-free matting wax in the first fluorine-free powder coating composition are replaced by polyacrylic acid wax powder (brand name: LANCO PP 1362 D from Lubrizol).

[0055] Comparative Example 3: The rest of the technical scheme of Comparative Example 3 is the same as that of Example 1, except that in Comparative Example 3, all parts by weight of the fluorine-free matting wax in the second fluorine-free powder coating composition are replaced by polyacrylic acid wax powder (brand name: LANCO PP 1362 D from Lubrizol).

[0056] Comparative Example 4: The remaining technical solutions of Comparative Example 4 are the same as those of Example 1, except that in Comparative Example 4, all parts by weight of the fluorine-free matting wax in the first fluorine-free powder coating composition are replaced by modified polytetrafluoroethylene wax (Lanco Wax TF 1890C of Lubrizol).

[0057] Comparative Example 5: The rest of the technical scheme of Comparative Example 5 is the same as that of Example 1, except that in Comparative Example 5, all parts by weight of the fluorine-free matting wax in the second fluorine-free powder coating composition are replaced by modified polytetrafluoroethylene wax (Lanco Wax TF 1890C of Lubrizol).

[0058] The present application prepares powder coating compositions for each of the above Examples 1-18 and Comparative Examples 1-5, respectively. The powder coating compositions provided in each of Examples 1-18 and Comparative Examples 1-5 are sprayed and cured on an aluminum substrate of the same model (the curing conditions are uniformly selected as: 200°C@10min) to obtain cured coatings, and the film thickness of the cured coatings is 70-90μm.

[0059] The present application tests the total fluorine content of the powder coating compositions provided in Examples 1-18 and Comparative Examples 1-5, and the test results are shown in Table 4 below. At the same time, the above cured coatings are also tested for performance comparison as shown in Table 4 below:

[0060] It should be noted that the performance tests involved in this embodiment or comparative example are performed according to the test standards or conditions described in Table 5 below.

[0061]

[0062] It should be noted that those skilled in the art can also apply the powder coating composition proposed in this application to the coating protection of other material substrates to obtain similar coating effects, which will not be described in detail in this application.

[0063] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0064] 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 fluorine-free powder coating composition, characterized in that: It includes a thermosetting resin, a curing agent and a fluorine-free matting wax, wherein the fluorine-free matting wax is polyethylene wax, the dripping temperature of the polyethylene wax is 127°C-132°C, and the test standard for the dripping temperature is ASTM D3954-15 (2022); the total fluorine content of the fluorine-free powder coating composition tested according to the EN14582-2016 method is ≤100 mg / kg.

2. The fluorine-free powder coating composition according to claim 1, characterized in that: The D50 particle size of the polyethylene wax is 7.5 μm - 9.5 μm.

3. The fluorine-free powder coating composition according to claim 1 or 2, characterized in that: The density of the polyethylene wax at 23° C. is 0.96-0.98 g / cm³.

4. The fluorine-free powder coating composition according to claim 1, characterized in that: The acid value of the polyethylene wax is 0-1 mg KOH / g, more preferably 0 mg KOH / g.

5. The fluorine-free powder coating composition according to claim 1, characterized in that: The sum of the weight of the thermosetting resin and the curing agent accounts for 40-80wt% of the weight of the fluorine-free powder coating composition, and more preferably 45-75wt%; and / or the weight of the thermosetting resin accounts for 35-75wt% of the weight of the fluorine-free powder coating composition, and more preferably 40-70wt%.

6. The fluorine-free powder coating composition according to claim 1 or 6, characterized in that: The weight proportion of the fluorine-free matting wax to the fluorine-free powder coating composition is 0.1-5wt%, more preferably 0.2-4.5wt%, and further preferably 0.5-4wt%.

7. The fluorine-free powder coating composition according to claim 1, characterized in that: The thermosetting resin includes a carboxyl polyester resin, and the acid value of the carboxyl polyester resin is preferably 20-60 mgKOH / g; the curing agent includes triglycidyl isocyanurate (TGIC) and / or hydroxyalkylamide (HAA).

8. A fluorine-free powder coating composition, characterized in that: The invention comprises a first fluorine-free powder coating composition and a second fluorine-free powder coating composition which are mixed; wherein the first fluorine-free powder coating composition and the second fluorine-free powder coating composition are both the fluorine-free powder coating composition according to any one of claims 1 to 7.

9. The fluorine-free powder coating composition according to claim 8, characterized in that: The first fluorine-free powder coating composition comprises a first carboxyl polyester resin, and the second fluorine-free powder coating composition comprises a second carboxyl polyester resin, wherein the acid values ​​of the first carboxyl polyester resin and the second carboxyl polyester resin are not equal; preferably, the difference in acid value between the first carboxyl polyester resin and the second carboxyl polyester resin is 10-50, more preferably 15-40; preferably, the acid value of the first carboxyl polyester resin is 45-65 mgKOH / g, and the acid value of the second carboxyl polyester resin is 15-35 mgKOH / g.

10. A cured coating, characterized in that: The fluorine-free powder coating composition according to any one of claims 1 to 9 is sprayed on a substrate, and the cured coating is obtained after heating and curing, wherein the gloss of the cured coating at a test angle of 60° according to ISO 2813-2014 is less than 80 GU.

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