Bio-based electrophoretic paint cross-linking agent composition and electrophoretic paint composition prepared from bio-based electrophoretic paint cross-linking agent composition

Abstract

The invention discloses a bio-based electrophoretic paint cross-linking agent composition S1. The bio-based electrophoretic paint cross-linking agent composition S1 comprises the following components: a bio-based polyol component; an isocyanate component; the catalyst comprises an organic bismuth or zinc catalyst; the solvent comprises propylene glycol methyl ether acetate or bio-based propylene carbonate. The electrophoretic paint cross-linking agent composition S2 comprises the following components: a cyclic carbonate monomer; a polyene polyamine; a thiol-ene click chemical reagent; an end-capping reagent and an organic tin catalyst component. An electrophoretic paint composition is prepared from the bio-based electrophoretic paint cross-linking agent composition. The invention provides a polyisocyanate cross-linking agent taking castor oil and bio-based polycarbonate diol as raw materials and a carbamate cross-linking agent prepared from cyclic carbonate and polyene polyamine, and the polyisocyanate cross-linking agent and the carbamate cross-linking agent have the following advantages that the bio-based content is greater than or equal to 60%, and the consumption of petroleum resources is reduced; the curing temperature is not more than 140 DEG C; vOC emission is reduced by more than 30%; and the adhesion, salt fog resistance and other properties of the coating reach or exceed those of a traditional system.

Description

Technical Field

[0001] This invention relates to the field of electrophoretic coating technology, and in particular to a bio-based electrophoretic paint crosslinking agent composition and an electrophoretic paint composition prepared therefrom. Background Technology

[0002] Electrophoretic coating is an environmentally friendly coating method that typically uses petroleum-based isocyanates as crosslinking agents, such as TDI, HDI, and their derivatives. However, these crosslinking agents have some problems:

[0003] 1. High VOC emissions: The synthesis and curing process of petroleum-based isocyanates releases volatile organic compounds, causing environmental pollution;

[0004] 2. Non-renewable: These raw materials rely on fossil fuels, which does not meet the requirements of sustainable development;

[0005] 3. High curing temperature: Traditional crosslinking agents need to be cured at high temperatures (at least 160°C), which leads to increased energy consumption.

[0006] Although existing technologies have attempted to use some bio-based raw materials (such as vegetable oil polyols), they suffer from problems such as low crosslinking efficiency, poor compatibility with electrophoresis processes, and insufficient mechanical properties of the coating. Therefore, there is an urgent need to develop a novel crosslinking agent with high bio-based content, low-temperature curing properties, and adaptability to electrophoresis processes. Summary of the Invention

[0007] The purpose of this invention is to provide a bio-based electrophoretic paint crosslinking agent composition and an electrophoretic paint composition prepared therefrom, thereby solving one or more of the aforementioned problems in the prior art.

[0008] In a first aspect, the present invention provides a bio-based electrophoretic paint crosslinking agent composition S1, comprising the following components:

[0009] Bio-based polyol components;

[0010] Isocyanate component: Its NCO / OH molar ratio with that of the polyol component is 1.5-2.5:1;

[0011] Catalyst: The catalyst includes organic bismuth or zinc-based catalysts;

[0012] Solvent: The solvent includes propylene glycol methyl ether acetate or bio-based propylene carbonate, so that the solid content is 50% to 70%.

[0013] In some embodiments, the bio-based polyol component comprises, by weight, 40-60 parts castor oil and 20-30 parts bio-based polycarbonate diol; the castor oil has a hydroxyl value of 160-180 mg KOH / g; and the bio-based polycarbonate diol has a number average molecular weight of 1000-2000 and a bio-based carbon content of ≥95%.

[0014] In some embodiments, the isocyanate component includes hexamethylene diisocyanate trimer or isophorone diisocyanate derivative; the catalyst includes 0.01 to 0.1 parts by weight of an organobismuth or zinc catalyst.

[0015] In some embodiments, the bio-based electrophoretic paint crosslinking agent composition S1 comprises the following components:

[0016] Castor oil (hydroxyl value 160-180 mg KOH / g), accounting for 40% to 60%; bio-based polycarbonate diol (number average molecular weight 1000-2000, bio-based carbon content ≥95%), accounting for 20% to 30%.

[0017] Isocyanate component: Hexamethylene diisocyanate (HDI) trimer or isophorone diisocyanate (IPDI) derivative, with an NCO / OH molar ratio of 1.5-2.5:1 to the polyol component.

[0018] Catalyst: Organic bismuth or zinc-based catalyst (0.01%–0.1%)

[0019] Solvent: Propylene glycol methyl ether acetate (PMA) or bio-based propylene carbonate, adjusting the solid content to 50%–70%.

[0020] In some embodiments, a bio-based electrophoretic paint crosslinking agent composition S1 is prepared by the following method:

[0021] Castor oil and bio-based polycarbonate diol were vacuum dehydrated at 120-140℃ for 1-2 hours; the temperature was then lowered to 60-80℃, isocyanate and catalyst were added, and the reaction was carried out under nitrogen protection for 3-5 hours until the NCO content reached the standard; solvent was added for dilution and the mixture was filtered.

[0022] Secondly, the present invention provides a bio-based electrophoretic paint crosslinking agent composition S2, comprising the following components in parts by weight:

[0023] Cyclic carbonate monomers;

[0024] Polyene polyamines;

[0025] Thiol-olefin click chemistry reagent: mercapto-modified castor oil;

[0026] End-capping agent: The end-capping agent includes ethyl acetoacetate or phenol, and the end-capping rate is ≥90%;

[0027] Catalyst: The catalyst comprises dibutyltin dilaurate;

[0028] Solvent: The solvent includes bio-based dimethyl carbonate or alcohol ether solvent, so that the solid content is 40% to 60%.

[0029] In some embodiments, the cyclic carbonate monomer comprises, by weight, 30-50 parts of vegetable oil-derived ethylene carbonate or propylene carbonate; the polyene polyamine comprises, by weight, 20-30 parts of triethylenetetramine; the thiol-ene click chemistry reagent comprises, by weight, 10-20 parts of mercapto-treated castor oil; the capping agent comprises, by weight, 5-10 parts of ethyl acetoacetate; and the catalyst comprises, by weight, 0.05-0.2 parts of dibutyltin dilaurate.

[0030] In some embodiments, the bio-based electrophoretic paint crosslinking agent composition S2 comprises the following components:

[0031] Cyclic carbonate monomers: ethylene carbonate or propylene carbonate derived from vegetable oils, accounting for 30% to 50%;

[0032] Polyene polyamine: one of triethylenetetramine and tetraethylenepentamine, with a primary amine content ≥60%, accounting for 20% to 30%;

[0033] Thiol-ene click chemistry reagent: Thiolized castor oil is obtained by addition of a certain amount of castor oil and 2-mercaptoethanol (the molar ratio of double bond to mercapto group is 1:1.5);

[0034] Capping agent: Ethyl acetoacetate or phenol (capping rate ≥90%);

[0035] Catalyst: Dibutyltin dilaurate, accounting for 0.05-0.2%;

[0036] Solvent: Bio-based dimethyl carbonate (DCM) or alcohol ether solvent, adjusting the solid content to 40%–60%.

[0037] In some embodiments, a bio-based electrophoretic paint crosslinking agent composition S2 is prepared by the following method:

[0038] Cyclic carbonates and polyene polyamines are reacted in a molar ratio of 1:1.2-1.5 with a catalyst and subjected to aminolysis at 80-100℃.

[0039] Dynamic cross-linked networks were constructed by adding thiol-olefin click chemistry reagents;

[0040] Free amino groups were blocked by ethyl acetoacetate at 60°C for 1 hour.

[0041] Add solvent to make the solid content 40% to 60%.

[0042] Preparation method:

[0043] Step 1: Cyclic Carbonate Synthesis

[0044] Raw materials: Vegetable oil (such as rapeseed oil) undergoes epoxidation and carbonation reactions to produce cyclic carbonates (yield ≥85%, carbonate equivalent 150-200 g / mol).

[0045] Reaction formula:

[0046] Step 2: Carbamate Synthesis

[0047] Amine hydrolysis: Cyclic carbonates and polyene polyamines are reacted at a molar ratio of 1:1.2 to 1.5 with a catalyst at 80 to 100 °C to produce carbamates, which are detected by NCO equivalent.

[0048] Dynamic crosslinking design: Introducing thiol-ene click chemical branches to improve the reversibility of the crosslinking network (Tg adjustment range 80-120℃).

[0049] Step 3: End sealing

[0050] Adding ethyl acetoacetate blocks free amine groups and reduces toxicity (free amine content ≤0.5%).

[0051] Thirdly, the present invention provides an electrophoretic paint composition comprising the following components:

[0052] Main resin: The main resin includes epoxy resin or acrylic resin;

[0053] The bio-based polyisocyanate crosslinking agent S1 according to claim 1;

[0054] The bio-based carbamate crosslinking agent S2 as described in claim 5;

[0055] Additives: The additives include leveling agents, neutralizing agents and deionized water.

[0056] In some embodiments, the product comprises, by weight, 5-15 parts of bio-based polyisocyanate crosslinking agent S1 and 5-10 parts of bio-based carbamate crosslinking agent S2.

[0057] Preparation of electrophoretic paint composition

[0058] Main resin: epoxy resin or acrylic resin;

[0059] Crosslinking agent: the bio-based polyisocyanate composition S1 of the present invention, added at an amount of 5% to 15%;

[0060] Bio-based carbamate composition S2, added at 5% to 10%;

[0061] Additives: leveling agents, neutralizing agents (such as lactic acid), deionized water;

[0062] The electrophoresis conditions are as follows:

[0063] Electrophoresis voltage: 100~250V, curing conditions: 130-140℃ / 20~30 minutes.

[0064] The electrophoretic paint composition of the present invention has the following technical effects:

[0065] 1. Environmental friendliness: Bio-based content reaches 65% to 75%, VOC ≤ 50g / L (35% lower than traditional systems);

[0066] 2. Low-temperature curing: Complete cross-linking can be achieved at 130℃ for 25 minutes, saving 20% ​​more energy than traditional processes;

[0067] 3. Performance data:

[0068] - Adhesion (cross-cut test): Grade 0;

[0069] - Salt spray resistance ≥1000 hours;

[0070] - Impact strength ≥ 50 kg·cm;

[0071] 4. Process compatibility: The stability of the electrophoresis bath solution is >6 months, with no sedimentation. Detailed Implementation

[0072] The present invention will be further described in detail below through embodiments.

[0073] Example 1

[0074] 50 parts of castor oil and 25 parts of bio-based polycarbonate diol (Mn=1500) were vacuum dehydrated at 120-140℃ for 1-2 hours, cooled to 60-80℃, and HDI trimer (NCO content 21%) and 0.05% organic bismuth catalyst were added. The reaction was carried out under nitrogen protection for 3-5 hours. After the NCO content was found to be up to standard, solvent was added for dilution to prepare crosslinking agent S1 with a solid content of 60%.

[0075] Electrophoretic paint formula: 30 parts epoxy resin, 15 parts S1 crosslinking agent, 2 parts lactic acid, add deionized water to 100.

[0076] Performance: 68% bio-based content, 45g / L VOC, 1000 hours salt spray resistance after curing at 130℃ for 25 minutes.

[0077] Example 2:

[0078] A crosslinking agent S2 with a solid content of 60% was prepared by adding 80 parts rapeseed oil-based cyclic carbonate, 25 parts triethylenetetramine, 12 parts mercapto-modified castor oil, and 0.1 parts dibutyltin dilaurate; aminolysis was carried out at 90℃ for 4 hours; 8 parts ethyl acetoacetate were added, and the end-capping temperature was 60℃ for 1 hour; then, bio-based dimethyl carbonate was added as a solvent.

[0079] Electrophoretic paint formulation: 32 parts epoxy resin, 10 parts S1 crosslinking agent, 5 parts S2 crosslinking agent, 2 parts lactic acid, and deionized water to 100.

[0080] Performance: 72% bio-based content, 40g / L VOC, 1200 hours salt spray resistance after curing at 130℃ for 25 minutes.

[0081] Comparative example:

[0082] It uses HDI trimer crosslinking agent (petroleum-based), VOC 75g / L, requires curing at 160℃ for 30 minutes, and is resistant to salt spray for 800 hours.

[0083] In summary, this invention provides a polyisocyanate crosslinking agent made from castor oil and bio-based polycarbonate diol, as well as a urethane crosslinking agent prepared from cyclic carbonates and polyene polyamines, which has the following advantages:

[0084] 1. Bio-based content ≥60%, reducing petroleum resource consumption;

[0085] 2. Curing temperature ≤140℃, shortening energy consumption and processing time;

[0086] 3. VOC emissions are reduced by more than 30%;

[0087] 4. The coating adhesion, salt spray resistance and other properties meet or exceed those of traditional systems.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these should also be considered within the scope of protection of the invention.

Claims

1. A bio-based electrophoretic paint crosslinking agent composition S1, characterized in that, Includes the following components: Bio-based polyol components; Isocyanate component: Its NCO / OH molar ratio with that of the polyol component is 1.5-2.5:1; Catalyst: The catalyst includes organic bismuth or zinc-based catalysts; Solvent: The solvent includes propylene glycol methyl ether acetate or bio-based propylene carbonate, so that the solid content is 50% to 70%.

2. The bio-based electrophoretic paint crosslinking agent composition S1 according to claim 1, characterized in that, Based on parts by weight, the bio-based polyol component comprises 40-60 parts castor oil and 20-30 parts bio-based polycarbonate diol; the hydroxyl value of the castor oil is 160-180 mg KOH / g; the number average molecular weight of the bio-based polycarbonate diol is 1000-2000, and the bio-based carbon content is ≥95%.

3. The bio-based electrophoretic paint crosslinking agent composition S1 according to claim 2, characterized in that, The isocyanate component includes hexamethylene diisocyanate trimer or isophorone diisocyanate derivative; the catalyst includes 0.01 to 0.1 parts by weight of organic bismuth or zinc catalyst.

4. The bio-based electrophoretic paint crosslinking agent composition S1 according to claim 3, characterized in that, It is prepared by the following method: Castor oil and bio-based polycarbonate diol were vacuum dehydrated at 120-140℃ for 1-2 hours; the temperature was then lowered to 60-80℃, isocyanate and catalyst were added, and the reaction was carried out under nitrogen protection for 3-5 hours until the NCO content reached the standard; solvent was added for dilution and the mixture was filtered.

5. A bio-based electrophoretic paint crosslinking agent composition S2, characterized in that, Includes the following components by weight: Cyclic carbonate monomers; Polyene polyamines; Thiol-olefin click chemistry reagent: mercapto-modified castor oil; End-capping agent: The end-capping agent includes ethyl acetoacetate or phenol, and the end-capping rate is ≥90%; Catalyst: The catalyst comprises dibutyltin dilaurate; Solvent: The solvent includes bio-based dimethyl carbonate or alcohol ether solvent, so that the solid content is 40% to 60%.

6. The bio-based electrophoretic paint crosslinking agent composition S2 according to claim 5, characterized in that, By weight, the cyclic carbonate monomer comprises 30-50 parts of vegetable oil-derived ethylene carbonate or propylene carbonate; by weight, the polyene polyamine comprises 20-30 parts of triethylenetetramine; by weight, the thiol-ene click chemistry reagent comprises 10-20 parts of mercapto-treated castor oil; by weight, the end-capping agent is 5-10 parts of ethyl acetoacetate; and by weight, the catalyst comprises 0.05-0.2 parts of dibutyltin dilaurate.

7. The bio-based electrophoretic paint crosslinking agent composition S2 according to claim 6, characterized in that, It is prepared by the following method: Cyclic carbonates and polyene polyamines are reacted in a molar ratio of 1:1.2-1.5 with a catalyst and subjected to aminolysis at 80-100℃. Dynamic cross-linked networks were constructed by adding thiol-olefin click chemistry reagents; Free amino groups were blocked by ethyl acetoacetate at 60°C for 1 hour; Add solvent to make the solid content 40% to 60%.

8. An electrophoretic paint composition, characterized in that, Includes the following components: Main resin: The main resin includes epoxy resin or acrylic resin; The bio-based polyisocyanate crosslinking agent S1 according to claim 1; The bio-based carbamate crosslinking agent S2 as described in claim 5; Additives: The additives include leveling agents, neutralizing agents and deionized water.

9. The electrophoretic paint composition according to claim 8, characterized in that, By weight, it includes 5-15 parts of bio-based polyisocyanate crosslinking agent S1 and 5-10 parts of bio-based carbamate crosslinking agent S2.