Low-temperature curing powder coating composition and coating thereof
By using a low-temperature curing powder coating composition of high-acid-value polyester resin, epoxy resin, non-fluorinated texturer, and bentonite, the problem of excessive fluorine content in existing coatings is solved, achieving low fluorine content and excellent performance of the coating under low-temperature curing.
Patent Information
- Application Number
- CN202511996185.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-03-03
AI Technical Summary
Existing thermosetting powder coatings cannot meet the requirement of a total fluorine content of less than 200 ppm in certain fields, especially coatings made with polytetrafluoroethylene-based texture additives have excessively high fluorine content.
A low-temperature curing powder coating composition containing polyester resin with an acid value of not less than 60 mgKOH/g, epoxy resin with an epoxy equivalent of not less than 450 g/eq, non-fluorinated texturer, and bentonite is used. The coating effect is the same as or similar to that of existing fluorinated additives by electrostatic spraying and curing at a temperature below 150°C, while controlling the total fluorine content to be less than 200 ppm.
Under low-temperature conditions, the total fluorine content of the coating was reduced to less than 200 ppm, while maintaining a surface effect similar to that of existing fluorine-containing additives. The coating also exhibited excellent performance, particularly better mechanical properties and chemical resistance.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of powder coatings, specifically relating to a low-temperature curing powder coating composition and its coating. Background Technology
[0002] Thermosetting powder coatings are widely used to replace oil-based and water-based paints for protective and decorative purposes on products across various fields due to their advantages such as being environmentally friendly, energy-efficient, easy to apply, and having little to no VOC emissions. However, with the increasing application of thermosetting powder coatings in various fields and the emergence of new demands in certain application areas, the applicant has found that existing thermosetting powder coating products cannot meet these new requirements. In particular, with the continuous development of market applications, some specific fields (such as a well-known furniture brand) have proposed that the total fluorine content of the coatings used in their products should be less than 200 ppm. Currently, the thermosetting powder coatings they use are mainly low-temperature textured powders made from polytetrafluoroethylene (PTFE) texture additives, and the total fluorine content of the coatings made from these powders far exceeds 200 ppm, which cannot meet the requirements of these specific fields.
[0003] Therefore, the applicant hopes to conduct research and development to solve the aforementioned technical problems. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a low-temperature curing powder coating composition and its coating. The proposed low-temperature curing powder coating composition can still achieve the same or similar coating surface effect as existing fluorinated additives under low-temperature curing conditions. More importantly, it reliably ensures that the total fluorine content of the corresponding coating is less than 200 ppm. The technical solution adopted in this invention is as follows: A low-temperature curing powder coating composition includes a polyester resin with an acid value of not less than 60 mgKOH / g, an epoxy resin with an epoxy equivalent of not less than 450 g / eq, a non-fluorinated texture agent, and bentonite; the total fluorine content of the low-temperature curing powder coating composition, as tested according to method EN14582-2016, is ≤200 mg / kg; it should be noted that the “non-fluorinated texture agent” mentioned throughout this application refers to a texture agent synthesized based on a fluorine-free substance as a raw material.
[0005] Preferably, the non-fluorinated texturer accounts for 5-15 wt% of the weight of the low-temperature curing powder coating composition, more preferably 6-10 wt%; the bentonite accounts for 1-6 wt% of the weight of the low-temperature curing powder coating composition, more preferably 2-5 wt%.
[0006] Preferably, the total fluorine content of the non-fluorinated texture agent, as tested according to method EN14582-2016, is ≤200 mg / kg.
[0007] Preferably, the bentonite is an organic clay, and more preferably tetraalkylammonium bentonite.
[0008] Preferably, the polyester resin has an acid value range of 70-90 mg KOH / g; and / or the polyester resin has a viscosity range of 7-17 Pa·s at 160°C; and / or the polyester resin has a softening point temperature not higher than 120°C; and / or the polyester resin has a glass transition temperature not higher than 58°C.
[0009] Preferably, the epoxy resin has an epoxy equivalent range of 500-650 g / eq; and / or the softening point temperature of the epoxy resin is not higher than 110°C; and / or the viscosity of the epoxy resin at 150°C is in the range of 1000-4200 mPa·s.
[0010] Preferably, the weight ratio of the polyester resin to the epoxy resin is 1:2-4:1.
[0011] Preferably, the low-temperature curing powder coating composition further includes a catalyst, the catalyst comprising phosphorus bromide and / or phenylimidazole.
[0012] Preferably, the low-temperature curing powder coating composition further includes leveling agents and / or degassing agents and / or pigments and / or fillers.
[0013] Preferably, a low-temperature curing coating is obtained by electrostatic spraying and curing the low-temperature curing powder coating composition as described above on a substrate; wherein, during the curing process, the heating temperature is not higher than 150°C and the heating time is not more than 5 minutes; preferably, the powder coating composition is cured by infrared heating, wherein the heating temperature range is 130-140°C and / or the heating time range is 2-4 minutes.
[0014] It should be noted that the acid value testing standard involved in this application is based on ISO 3682-1998; the viscosity value testing standard is based on ASTM D 4287-1994; and the testing equipment used can be a standard commercial cone-plate viscometer (e.g., an ICI cone-plate viscometer (CONE&PLATE), brand name Brookfield CAP 2000 VISCOMETER); the epoxy equivalent data involved are all obtained by testing according to the testing standard GB / T 4612-2008; the glass transition temperature testing standard is based on ISO 11357-2-2013; and the softening point temperature standard is based on ISO 4625-1980.
[0015] This application first uses polyester resin and epoxy resin as the main resin curing system of the powder coating composition, and at the same time, it is compounded with a specific additive composed of non-fluorinated texture agent and bentonite to replace the existing fluorinated additive (usually PTFE polytetrafluoroethylene texture agent). The low-temperature curing powder coating composition proposed in this application can still achieve the same or similar coating surface effect as the existing fluorinated additive under low-temperature curing conditions. More importantly, it reliably ensures that the total fluorine content of the corresponding coating is less than 200 ppm. Detailed Implementation
[0016] This application provides a low-temperature curing powder coating composition comprising a polyester resin with an acid value of not less than 60 mg KOH / g, an epoxy resin with an epoxy equivalent of not less than 450 g / eq, a non-fluorinated texturer, and bentonite; the total fluorine content of the low-temperature curing powder coating composition is ≤200 mg / kg as determined by the EN14582-2016 method.
[0017] Preferably, in this embodiment, the non-fluorinated texturer accounts for 5-15 wt% by weight in the low-temperature curing powder coating composition, more preferably 6-10 wt%; or, preferably, in this embodiment, the non-fluorinated texturer accounts for 7-20 wt% by weight in the low-temperature curing powder coating composition, more preferably 9-12 wt%; or, preferably, in this embodiment, the non-fluorinated texturer accounts for 0.5-8 wt% by weight in the low-temperature curing powder coating composition, more preferably 1-5 wt%; and the bentonite accounts for 1-6 wt% by weight in the low-temperature curing powder coating composition, more preferably 2-5 wt%.
[0018] Preferably, in this embodiment, the total fluorine content of the non-fluorinated texture agent, as tested according to the EN14582-2016 method, is ≤200 mg / kg.
[0019] Preferably, in this embodiment, the bentonite is an organic clay, and more preferably tetraalkylammonium bentonite.
[0020] Preferably, in this embodiment, the acid value of the polyester resin is in the range of 70-90 mg KOH / g; and / or the viscosity of the polyester resin at 160°C is in the range of 7-17 Pa.s; and / or the softening point temperature of the polyester resin is not higher than 120°C; and / or the glass transition temperature of the polyester resin is not higher than 58°C.
[0021] Preferably, in this embodiment, the epoxy equivalent of the epoxy resin is in the range of 500-650 g / eq; and / or the softening point temperature of the epoxy resin is not higher than 110°C; and / or the viscosity of the epoxy resin at 150°C is in the range of 1000-4200 mPa·s.
[0022] Preferably, in this embodiment, the weight ratio of polyester resin to epoxy resin is 1:2-4:1, more preferably 1:1-3:1, and even more preferably 2:1-3:1; preferably, in order to further facilitate the low-temperature curing effect, in this embodiment, the low-temperature curing powder coating composition further includes phenolic resin, wherein preferably, the weight percentage of phenolic resin in the low-temperature curing powder coating composition is 1-15 wt%, more preferably 3-10 wt%, and even more preferably 6-9 wt%.
[0023] Preferably, in order to promote reactivity under low-temperature conditions, in this embodiment, the low-temperature curing powder coating composition further includes a catalyst, which includes phosphorus bromide and / or phenylimidazole.
[0024] All the raw materials involved in this application can be purchased directly on the market, and the source of raw materials is easy to obtain.
[0025] In specific implementations of this 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 powder coating composition. These are all conventional technical choices for those skilled in the art. Specifically, fillers and / or pigments can be, for example, carbon black, aluminum hydroxide, barium sulfate, TiO2, etc.
[0026] In preparing the powder coating composition of this application, any known preparation process can be used. Preferably, in this embodiment, the powder coating composition is obtained by mixing, melt extrusion, and crushing. Of course, other known preparation processes can also be used to obtain the powder coating composition of this embodiment. This application does not have any particular limitation on its preparation process.
[0027] Preferably, this embodiment also proposes a low-temperature curing coating, which is obtained by electrostatic spraying and curing the low-temperature curing powder coating composition as described above on a substrate; wherein, during curing, the heating temperature is not higher than 150°C and the heating time is not more than 5 minutes; preferably, in this embodiment, infrared heating is used to cure the powder coating composition, with a heating temperature range of 130-140°C and / or a heating time range of 2-4 minutes.
[0028] To verify the technical effects of this application, the following sets of embodiments were specifically tested and compared as raw materials for powder coating composition formulations: Example 1: A low-temperature curing powder coating composition, with the raw materials prepared according to the following Table 1:
[0029] The low-temperature curing powder coating composition of Example 1 is obtained by mixing all the above raw materials together, performing one-time melt extrusion and crushing. Example
[0030] The remaining technical solutions of this embodiment 2 are the same as those of embodiment 1, except that the raw materials for this embodiment 2 are prepared according to the following Table 2.
[0031]
[0032] Example 3: The remaining technical solutions of Example 3 are the same as those of Example 1, except that the raw materials for the formula are prepared according to Table 3 below.
[0033]
[0034] Example 4: The remaining technical solutions of Example 4 are the same as those of Example 1, except that the raw materials for the formula are prepared according to Table 4 below.
[0035]
[0036] Example 5: The remaining technical solutions of Example 5 are the same as those of Example 1, except that the raw materials for the formula are prepared according to Table 5 below.
[0037]
[0038] Example 6: The remaining technical solutions of Example 6 are the same as those of Example 1, except that the raw materials for the formula are prepared according to Table 6 below.
[0039]
[0040] Example 7: The remaining technical solutions of Example 7 are the same as those of Example 1, except that the raw materials for the formula are prepared according to Table 7 below.
[0041]
[0042] Example 8: The remaining technical solutions of Example 8 are the same as those of Example 1, except that the raw materials for the formula in Example 8 are prepared according to Table 8 below.
[0043]
[0044] Comparative Example 1: The remaining technical solutions of Comparative Example 1 are the same as those of Example 1, except that in Comparative Example 1, the weight parts of bentonite in Example 1 are reduced to 0 parts, and the weight parts of barium sulfate are increased to 24 parts.
[0045] Comparative Example 2: The remaining technical solutions of Comparative Example 2 are the same as those of Example 1, except that in Comparative Example 2, the weight of the non-fluorinated texture agent in Example 1 is reduced to 0 parts, and the weight of barium sulfate is increased to 20.5 parts.
[0046] Comparative Example 3: The remaining technical solutions of Comparative Example 3 are the same as those of Example 5, except that in Comparative Example 3, the weight parts of bentonite in Example 5 are reduced to 0 parts, and the weight parts of barium sulfate are increased to 15 parts.
[0047] Comparative Example 4: The remaining technical solutions of Comparative Example 4 are the same as those of Example 5, except that in Comparative Example 4, the weight of the non-fluorinated texture agent in Example 5 is reduced to 0 parts, and the weight of barium sulfate is increased to 11.5 parts.
[0048] Comparative Example 5: The remaining technical solutions of Comparative Example 5 are the same as those of Example 6, except that in Comparative Example 5, the weight parts of bentonite in Example 6 are reduced to 0 parts, and the weight parts of epoxy resin are increased to 25 parts.
[0049] Comparative Example 6: The remaining technical solutions of Comparative Example 6 are the same as those of Example 7, except that in Comparative Example 6, the weight of bentonite in Example 7 is reduced to 0 parts, and the weight of non-fluorinated texture agent is increased to 16 parts.
[0050] Comparative Example 7: The rest of the technical solutions of Comparative Example 7 are the same as those of Example 6, except that in Comparative Example 7, the polyester resin brand in Example 6 is replaced with ALLNEX's Crylcoat 2671-3, which has an acid value range of 45-51 mgKOH / g and a viscosity range of 4300-7300 mPa.s at 200°C.
[0051] Comparative Example 8: The rest of the technical solutions of Comparative Example 8 are the same as those of Example 6, except that: in Comparative Example 8, the EPOTEC YD 942 epoxy resin in Example 6 is replaced with GMA1618 from Ningbo Nanhai Chemical, which has an epoxy equivalent of 400-430 g / eq and a softening point temperature of 92-97℃.
[0052] According to the implementation schemes proposed in Examples 1-8 and Comparative Examples 1-8 above, the corresponding powder coating compositions were obtained by referring to the preparation process described in Example 1. In order to ensure the effect of each embodiment of this application, the total fluorine content of the non-fluorinated texture agent used in Examples 1-8 and the powder coating compositions obtained in each embodiment were first tested according to the EN14582-2016 method. The test results of the total fluorine content were all ≤200mg / kg.
[0053] The powder coating compositions prepared in Examples 1-8 and Comparative Examples 1-8 were used respectively. The same MDF board was selected as the substrate, and each powder coating composition was cured by infrared heating. The heating temperature was 130°C and the heating time was 3 minutes. Cured coatings were obtained respectively, and the performance of each cured coating was tested. The test results are shown in Table 9 below.
[0054]
[0055] It should be noted that, in the above embodiments of this application, the mechanical properties and chemical resistance of the coatings obtained in Examples 4, 5, 6, 7 and 8 are significantly better than those in Examples 1-3, and the coating gloss is more stable. They can completely replace existing fluorinated additives in low-temperature curing product formulations to achieve low-temperature curing coating.
[0056] It should also be noted that the performance tests involved in this embodiment or comparative example were conducted in accordance with the test standards or conditions described in Table 10 below.
[0057]
[0058] 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 invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A low-temperature curing powder coating composition, characterized in that, The composition includes a polyester resin with an acid value of not less than 60 mgKOH / g, an epoxy resin with an epoxy equivalent of not less than 450 g / eq, a non-fluorinated texturer, and bentonite; the total fluorine content of the low-temperature curing powder coating composition is ≤200 mg / kg as determined by method EN14582-2016.
2. The low-temperature curing powder coating composition according to claim 1, characterized in that, The non-fluorine-based texturer is present in the low-temperature curing powder coating composition at a weight ratio of 5-15 wt%, preferably 6-10 wt%; the bentonite is present in the low-temperature curing powder coating composition at a weight ratio of 1-6 wt%, preferably 2-5 wt%.
3. The low-temperature curing powder coating composition according to claim 1, characterized in that, The total fluorine content of the non-fluorinated texture agent, as tested according to method EN14582-2016, is ≤200 mg / kg.
4. The low-temperature curing powder coating composition according to claim 1, characterized in that, The bentonite is an organic clay, preferably tetraalkylammonium bentonite.
5. The low-temperature curing powder coating composition according to claim 1, characterized in that, The polyester resin has an acid value range of 70-90 mg KOH / g; and / or the polyester resin has a viscosity range of 7-17 Pa·s at 160°C; and / or the softening point temperature of the polyester resin is not higher than 120°C; and / or the glass transition temperature of the polyester resin is not higher than 58°C.
6. The low-temperature curing powder coating composition according to claim 1, characterized in that, The epoxy equivalent of the epoxy resin is in the range of 500-650 g / eq; and / or the softening point temperature of the epoxy resin is not higher than 110℃; and / or the viscosity of the epoxy resin at 150℃ is in the range of 1000-4200 mPa·s.
7. The low-temperature curing powder coating composition according to claim 1, characterized in that, The weight ratio of the polyester resin to the epoxy resin is 1:2-4:
1.
8. The low-temperature curing powder coating composition according to claim 1, characterized in that, The low-temperature curing powder coating composition further includes a catalyst, which comprises phosphorus bromide and / or phenylimidazole.
9. The low-temperature curing powder coating composition according to claim 1, characterized in that, The low-temperature curing powder coating composition further includes leveling agents and / or degassing agents and / or pigments and / or fillers.
10. A low-temperature curing coating, characterized in that, The powder coating is obtained by electrostatic spraying and curing on a substrate using the low-temperature curing powder coating composition as described in any one of claims 1-9; wherein, during the curing process, the heating temperature is not higher than 150°C and the heating time is not more than 5 minutes; preferably, the powder coating composition is cured by infrared heating, wherein the heating temperature range is 130-140°C and / or the heating time range is 2-4 minutes.