NL2030773B1

NL2030773B1 - Method for preparing powderable self-healing flame-retardant low-voc polyurethane coating and application in car seat leather

Info

Publication number: NL2030773B1
Application number: NL2030773A
Authority: NL
Inventors: Feng Lianxiang; Li Guorong; Hu Lecheng; Weng Yonggen; Tang Zhihai; Yu Han; Wang Xiangmin; Gu Lulu; Wang Quanjie; Duan Baorong
Original assignee: Univ Yantai
Priority date: 2022-01-28
Filing date: 2022-01-28
Publication date: 2023-08-08

Abstract

The present disclosure discloses a method for preparing a powderable self—healing flame—retardant low—VOC polyurethane coating and ah application thereof.

Description

P1065 /NLpd

METHOD FOR PREPARING POWDERABLE SELF-HEALING FLAME-RETARDANT LOW-

VOC POLYURETHANE COATING AND APPLICATION IN CAR SEAT LEATHER

TECHNICAL FIELD

The present disclosure relates to a method for preparation and application of a polyurethane coating, and particularly to a method for preparing a powderable self-healing flame-retardant low-VOC polyurethane coating and an application of the polyure- thane coating to car seat leathers.

BACKGROUND ART

In the field of automotive leathers, most polyurethane coat- ing agents are liquid, which increases the difficulty of transpor- tation for enterprises. Due to the curing of polyurethane, if it is not handled properly, it is difficult to restore its original properties by adding water. At present, there is no report on the powderable polyurethane coating agent at home and abroad, there- fore, it is necessary to conduct improvement on them.

SUMMARY

The technical solutions of the present disclosure are as fol- lows:

The powderable polyurethane coating A and the self-healing flame-retardant low-VOC polyurethane coating B are prepared re- spectively according to the following steps: adding 18.6 g of polytetrahydrofuran ether glycol and 11.8 g of diisocyanate to a nitrogen-protected reaction vessel, heating the system to 70-80°C and adding 0.24-0.31g of dibutyltin di- laurate, stirring to react for 2-4 h, then adding 0.4-3.2 g of a chain extender to the system, continuing the reaction for 2-3 h; cooling to 50-70 °C and adding 15-30 mL of a viscosity reducer N,N- diethylformamide (DEF); cooling to 40°C again and adding 1.7-2.5 g of triethylamine, continuing the reaction for 0.5-1 h, then adding 7-8 g of bentonite, 1-2 g of nano calcium carbonate and 1.6-2.4 g of 4,4-dinitrodiphenyl ether, continuing to stir and react at 60- 70°C for 1-2h to obtain a viscous liquid, vacuum drying for 4 h and grinding, and storing in a sealed manner to obtain the powderable polyurethane coating A; adding 65-75 mL of deionized water, 12-17 g of epoxy resin

E51, 0.9 g of trimethylolpropane trimethacrylate and 1.4 g of 3;4'-oxydianiline to 1.7-4.3 g of a nitrogen-phosphorus intumes- cent flame retardant, stirring to react for 60-90 min at 65-75°C, to obtain the self-healing flame-retardant low-VOC polyurethane coating B.

Positive effects: (1) The present disclosure uses polytetramethylene ether glycol and diisocyanate as the catalysts for the reaction. After the end-capping treatment with triethylamine, nano calcium car- bonate is used to support or disperse in the waterborne polyure- thane with the synergistic effect of 4,4-dinitrodiphenyl ether, then the resulting material is intercalated in the spatial layer of montmorillonite, preventing the potential polymerization of different molecular chain polyurethanes to form branched or retic- ulated polyurethane under close contact conditions. In order to reduce the possibility of polymerization reaction after subsequent vacuum drying, the cured polyurethane, the flame retardant and self-healing material B are stored separately, to facilitate the polyurethane transportation and stable performance. The cured pol- yurethane basically returns to its original properties under the action of DEF and stirring. (2) The carbon source is the basis for generating carbide by heating and forming a carbonaceous layer; the acid source is de- composed by heat, and the product can promote the dehydration of organic matter into carbon. On this basis, POCl: is added to sup- plement the acid source into the system, and ethanolamine is added as a gas source. The gas source is heated to generate incombus- tible and flame-retardant gas, which are distributed in the carbon layer to promote the foaming of the carbon layer, increase the distance between the heat source and the substrate, reduce the mass transfer and heat transfer during combustion, to achieve bet- ter flame retardant performance, and achieve the synergistic ef-

fect of nitrogen and phosphorus; boric acid is used as the acid source, and tetrakis hydroxymethyl phosphonium sulfate has both an acid source and a carbon source, under the catalysis of concen- trated sulfuric acid, a cage-like compound containing a hydroxyl group is synthesized, and 3-aminopropyltriethoxysilane is used to react with the cage-like compound containing a hydroxyl group, and silicon groups are introduced.

The synthesized intermediate B has both cage-like rigidity and ethoxy side chains, which improves the strength of the intermediate and achieves the coordinated flame retardancy of boron, phosphorus and silicon; then the flame- retardant intermediate A reacts with the intermediate B, and the hydroxyl group of the flame-retardant intermediate A will react with the hydroxyl group on the boron when heated, and the interme- diate A and the intermediate B are reacted and grafted, and the resulting product is dispersed on the sodium lignosulfonate with a polyphenol three-dimensional network space structure formed by connection of C-C bond, C-0-C bond, etc., to make the resulting product to be uniformly dispersed.

Then butyric anhydride and un- reacted hydroxyl groups in the product are used for ring-opening reaction, and 2,4-dihydroxybenzaldehyde reacts with the hydroxyl group obtained from the ring-opening reaction.

The carboxyl and aldehyde groups are introduced into the system, and ethylenedia- minetetraacetic acid and the system react, which not only intro- duces the carboxyl group, but also increases the rigidity of the system.

Then, 4-carboxyphenylboronic acid and 2-acetoxyisobutyryl chloride are used to react with the hydroxy group and amino group {imine) of the system, so that the resulting flame retardant con- tains a large number of hydroxyl, carboxyl, aldehyde and imine groups, which facilitates the subsequent flame-retardant self-

repair; meanwhile, the flame retardant system is dispersed in the three-dimensional network structure of sodium lignosulfonate to facilitate the formation of a dense carbon layer through the flame retardant structure, and the gas released during the combustion process is coated in the dense carbon layer, which is difficult to release in a short time, playing a role of heat insulation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Example 1 1. The powderable self-healing flame-retardant low-VOC polyu- rethane coating is prepared according to the following steps: (1) add 18.6 g of polytetrahydrofuran ether glycol (molecu- lar weuight of 1,000 g/mol) and 11.8 g of 4, 4'-diphenylmethane diisocyanate to a nitrogen-protected reaction vessel, heat the system to 70°C and ad 0.24 g of dibutyltin dilaurate, stir to react for 2 h, then add 0.4 g of 2,2-dimethylolpropionic acid to the system, continue the reaction for 2 h; cool to 50°C and adding 15 mL of a viscosity reducer N,N-diethylformamide (DEF); cool to 40°C again and add 1.7 g of triethylamine, continue the reaction for 0.5 h, then add 7 g of bentonite, 1 g of nano calcium carbonate and 1.6 g of 4,4-dinitrodiphenyl ether, continue to stir and react at 60°C for 1 h to obtain a viscous liquid, perform vacuum drying for 4 h and grinding, and store in a sealed manner to obtain the powderable polyurethane coating A; (2) Preparation of self-healing flame-retardant low-VOC pol- yurethane coating B: add 65 mL of deionized water, 12 g of epoxy resin E51, 0.9 g of trimethylolpropane trimethacrylate and 1.4 g of 3,4'-oxydianiline to 1.7 g of a nitrogen-phosphorus intumescent flame retardant, stir to react for 60 min at 65°C, to obtain the self-healing flame-retardant low-VOC polyurethane coating B.

The nitrogen-phosphorus intumescent flame retardant is pre- pared according to the following steps: (1) Add 27.2 g of pentaerythritol and 138.4 g of phosphoric acid to a three-necked flask, stir at room temperature for 30 min, increase the temperature of the system to 90°C, and react for 1 h to obtain PEPA; cool the PEPA to room temperature, add 20.8 g of phosphorus oxychloride, then heat the system to 45°C, kept warm and stir for 30 min, and cool to room temperature, add dropwise 12.2 g of ethanolamine within 30 min, continue to react for 1 h, to obtain the flame retardant intermediate A; (2) Add 6.2 g of boric acid, 81.2 g of tetrakis hydroxyme- thyl phosphonium sulfate, and 0.98 g of concentrated sulfuric acid to react at 70°C for 1 h while stirring, then add sodium hydroxide solution (mass fraction 20%, the same below), adjust the pH to 6.0, then add 2.5 g of 3-aminopropyl triethoxysilane (KH550) to the reaction vessel, stir and react at 70°C for 1 h to obtain the intermediate B; 5 (3) Take the flame retardant intermediate A {all) obtained in the step (1), the intermediate B (all) obtained in the step (2), and 4.2 g of sodium lignosulfonate, stir and react at 60°C for 1 h while stirring, then add 1.2 g of butyric anhydride, 0.6 g of 2,4-dihydroxybenzaldehyde, and react at 70°C for 1 h, then add 0.5 g of ethylenediaminetetraacetic acid, 0.2 g of 4- carboxyphenylboronic acid, and 0.1g of 2-acetoxyisobutyryl chlo- ride, react at 70°C for 2 h to obtain the nitrogen-phosphorus in- tumescent flame retardant. 2. Application example

Hanging, drying and regaining moisture adopts the convention- al process; (cowhide car seat leather of Haining Sende Leather

Co., Ltd. on June 15, 2021; the car seat leather crust is subject- ed to hanging, drying and moisture-regaining).

The coating process includes primer coating, intermediate coating and top coating in sequence. The coatings are all roller coatings, with a roller coating temperature of 101°C, three times for the primer coating, twice for the intermediate coating, and once for the top coating. The coatings of each layer are as fol- lows: (a), the ratio of components of primer coating in parts by weight: 0.7 part of waterborne pigment paste NEOSAN 2000 (CLARIANT

Chemical Co., Ltd.), 32 parts of water, 0.2 part of cationic oil, and 0.4 part of Euderm oil KWO-C (cation, LANXESS Chemical); (b) The ratio of components of intermediate coating in parts by weight: 30 parts of water at 40°C, 20 parts of matting polyure- thane MATT 200 (Wenzhou GSB Polymer Materials Co., Ltd.), and 7 parts of bright polyurethane HPV-C (U.S. CYTE), 2 parts of cross- linking agent XL-701 (U.S. STAHL), 6 parts of powderable self- healing flame-retardant low-VOC polyurethane coating, 0.3 part of carbodiimide, 1.4 parts of film-forming accelerator, 0.1 part of trimethylolpropane, 0.1 part of vinyloxytrimethylsilane and 0.05 part of p-phenylenediamine;

Preparation of the powderable self-healing flame-retardant low-VOC polyurethane coating: Mix 100 g of powderable polyurethane coating A, 18 g of N,N-diethylformamide, 180 g of self-healing flame-retardant low-VOC polyurethane coating B to react for 1 h at 40°C, leave the mixture to stand for layering for 2 h, allow the nano calcium carbonate and bentonite to fully precipitate, to ob- tain a filtrate, and obtain the powderable self-healing flame- retardant low-VOC polyurethane coating. The parts can be equiva- lent to grams, which can be adjusted according to the ratio, the same below;

Preparation of the film-forming accelerator: Stir 6 g of pol- yethyleneimine and 8.2 g of 2-acetoxyisobutyryl chloride to react at 50°C for 1 h, then add 1.1 g of salicylic acid and 1.1 g of semicarbazide to react for 30 min at 50°C, to obtain a film- forming accelerator. (c) The ratio of components of top coating in parts by weight: 16 parts of water, 1.6 parts of anti-adhesive material, 5 parts of feeling agent 2229W (Shandong Chuanze Trading Co., Ltd.) and 0.2 part of cationic oil Euderm oil KWO-C (cation, LANXESS

Chemical);

Wherein, the anti-adhesive material is prepared according to the following steps: add € parts of 1,2-benzenediol and 12 parts of water to 12 parts of trifluoroacetamide, stir to react for 1 h at 50°C, dry, and add 2.1 parts of phenylphosphoryl dichloride and 13 parts of benzene, stir to react for 1 h at 60°C, then distill off the remaining benzene, and dry the residuum to obtain the an- ti-adhesive material.

Example 2 1. The powderable self-healing flame-retardant low-VOC polyu- rethane coating is prepared according to the following steps: (1) add 18.6 g of polytetrahydrofuran ether glycol and 11.8 g of isophorone diisocyanate to a nitrogen-protected reaction ves- sel, heat the system to 80°C and add 0.31 g of dibutyltin di- laurate, stir to react for 4 h, then add 3.2 g of 2,2- dimethylolbutanoic acid to the system, continue the reaction for 3 h; cool to 70°C and add 30 mL of a viscosity reducer N,N-

diethylformamide (DEF); cool to 40°C again and add 2.5 g of tri- ethylamine, continue the reaction for 1 h, then add 8 g of benton- ite, 2 g of nano calcium carbonate and 2.4 g of 4,4- dinitrodiphenyl ether, continue to stir and react at 70°C for 2 h to obtain a viscous liquid, perform vacuum drying for 4 h and grinding, and store in a sealed manner to obtain the powderable polyurethane coating A; (2) Preparation of self-healing flame-retardant low-VOC pol- yurethane coating B: add 75 mL of deionized water, 17 g of epoxy resin E51, 0.9 g of trimethylolpropane trimethacrylate and 1.4 g of 3,4'-oxydianiline to 4.3 g of a nitrogen-phosphorus intumescent flame retardant, stir to react for 90 min at 75°C, to obtain the self-healing flame-retardant low-VOC polyurethane coating B.

The nitrogen-phosphorus intumescent flame retardant is pre- pared according to the following steps: (1) Add 27.2 g of pentaerythritol and 138.4 g of phosphoric acid to a three-necked flask, stir at room temperature for 60 min, increase the temperature of the system to 130°C, and react for 5 h to obtain PEPA; cool the PEPA to room temperature, add 20.8 g of phosphorus oxychloride, then heat the system to 50°C, kept warm and stir for 60 min, and cool to room temperature, add dropwise 12.2 g of ethanolamine within 60 min, continue to react for 2 h, to obtain the flame retardant intermediate A; (2) Add 8.4 g of boric acid, 81.2 g of tetrakis hydroxymethyl phosphonium sulfate, and 0.98 g of concentrated sulfuric acid to react at 90°C for 3 h while stirring, then add sodium hydroxide solution to adjust the pH to 6.0, then add 3.6 g of 3-aminopropyl triethoxysilane (KH550) to the reaction vessel, stir and react at 110°C for 7 h to obtain the intermediate B; (3) Take the flame retardant intermediate A (all) obtained in the step (1), the intermediate B (all) obtained in the step (2), and 8.6 g of sodium lignosulfonate, stir and react at 70°C for 2 h while stirring, then add 1.7 g of butyric anhydride, 1.2 g of 2,4-dihydroxybenzaldehyde, and react at 80°C for 3 h, then add 1.2 g of ethylenediaminetetraacetic acid, 0.4 g of 4- carboxyphenylboronic acid, and 0.4 g of 2-acetoxyisobutyryl chlo-

ride, react at 80°C for 3 h to obtain the nitrogen-phosphorus in- tumescent flame retardant. 2. Application example (cowhide car seat leather of Haining Sende Leather Co., Ltd. on June 15, 2021; the car seat leather crust is subjected to hang- ing, drying and moisture-regaining according to the company’s pro- cess, which belongs to a conventional process in the art).

The coating process includes primer coating, intermediate coating and top coating in sequence. The coatings are all roller coatings, with a roller coating temperature of 105°C, three times for the primer coating, twice for the intermediate coating, and once for the top coating. The coatings of each layer are as fol- lows: (a), the ratio of components of primer coating in parts by weight: 2.5 parts of waterborne pigment paste NEOSAN 2000 (CLARI-

ANT Chemical Co., Ltd.), 32 parts of water, and 0.5 part of cati- onic oil Euderm oil KWO-C (cation, LANXESS Chemical}; (b) The ratio of components of intermediate coating in parts by weight: 30 parts of water at 50°C, 70 parts of matting polyure- thane MATT 200 (Wenzhou GSB Polymer Materials Co., Ltd.), and 18 parts of bright polyurethane HPV-C (U.S. CYTE), 4 parts of cross- linking agent XL-701 (U.S. STRAHL), 8 parts of powderable self- healing flame-retardant low-VOC polyurethane coating, 0.6 part of carbodiimide, 2.8 parts of film-forming accelerator, 0.1 part of trimethylolpropane, 0.2 part of vinyloxytrimethylsilane and 0.05 part of p-phenylenediamine;

Preparation of the powderable self-healing flame-retardant low-VOC polyurethane coating: Mix 100 g of powderable polyurethane coating A, 25 g of N,N-diethylformamide, 200 g of self-healing flame-retardant low-VOC polyurethane coating B to react for 2 h at 50°C, leave the mixture to stand for layering for 2 h, allow the nano calcium carbonate and bentonite to fully precipitate, to ob- tain a filtrate, and obtain the powderable self-healing flame- retardant low-VOC polyurethane coating. The parts can be equiva- lent to grams, which can be adjusted according to the ratio, the same below; (c) The ratio of components of top coating in parts by weight: 16 parts of water, 2.1 parts of anti-adhesive material, 7 parts of feeling agent 2229W (Shandong Chuanze Trading Co., Ltd.) and 0.3 part of cationic oil Euderm oil KWO-C (cation, LANXESS

Chemical};

Wherein, the anti-adhesive material is prepared according to the following steps: add 9 parts of 1,2- benzenediol and 12 parts of water to 12 parts of trifluoroacetamide, stir to react for 2 h at 60°C, dry, and add 3.8 parts of phenylphosphoryl dichloride and 13 parts of benzene, stir to react for 1 h at 65°C, then distill off the remaining benzene, and dry the residuum to obtain the an- ti-adhesive material.

Preparation of the film-forming accelerator: Stir 6 g of pol- yethyleneimine and 9.4 g of 2-acetoxyisobutyryl chloride to react at 60°C for 2 h, then add 1.4 g of salicylic acid and 2.3 g of semicarbazide to react for 90 min at 70°C, to obtain a film- forming accelerator.

Table 1 Test data of car seat leather manufacturing process

Color fastness to wet rubbing/grade 4.5

Lightfastness/grade

Wear resistance (CS-10, 10009, 500 times) No obvious No obvious damage, damage, peeling peeling

Claims

CONCLUSIONS

A process for preparing a low VOC powder self-healing flame-retardant polyurethane coating comprising: mixing a powdered polyurethane coating A, N,N-diethylformamide and a low-content self-healing polyurethane flame-retardant coating B to VOCs, reacting with stirring, then filtering to obtain a low VOC powder self-healing flame retardant polyurethane coating; wherein the polyurethane powder coating A is prepared in accordance with the following method: adding polytetrahydrofuran ether glycol and diisocyanate, heating the system and adding dibutyltin dilaurate to a nitrogen-protected reaction vessel, stirring for 2 to 4 hours to react, then adding adding a chain extender to the system, continuing the reaction for 2 to 3 hours; cooling and adding a viscosity-lowering agent N,N-diethylformamide (DEF); cool again and add triethylamine, then continue the reaction for 0.5 to 1 hour, then add bentonite, nanocalcium carbonate and 4,4-dinitrodiphenyl ether, continue to stir and react for 1 to 2 hours to form a viscous liquid vacuum drying and grinding the viscous liquid, to obtain the polyurethane powder coating A; wherein the low VOC self-healing flame retardant polyurethane coating B is prepared by the following method: adding epoxy resin E51, trimethylolpropane trimethacrylate and 3,4'-oxydianiline to a nitrogen-phosphorus intumescent flame retardant, stirring to react to make the self-healing flame retardant polyurethane coating B with a low VOC content.

The method for preparing the low VOC self-healing polyurethane flame retardant coating powder according to claim 1, wherein the mass ratio of the polyurethane powder coating A of N,N-diethylformamide to the low VOC self-repairing flame retardant polyurethane coating B is to VOS 100 : (18-25) : (180-200) is; wherein the diisocyanate is one of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate and toluene diisocyanate; wherein the chain extender is one of 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.

Use of the low VOC powder self-healing flame retardant polyurethane coating according to claim 1 or 2 in an automotive seat leather coating process.